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In-rush current jam proof sensor control

1. To free the shredder of the papers the user typically reverses the direction of rotation of the cutter elements via a switch until the papers become free Occasionally the jam may be so severe that reversing may not free the paper entirely and the paper must be pulled out manually which may be difficult with the paper bound between blades of the cutter elements In some cases when article s are inserted into the shredder that are too thick or irreversible the shredder may be overloaded or overheated and the motor of the shredder mechanism may stall and thus shut down In order to prevent such motor stall some existing designs use other detection devices to anticipate a motor s current limit For example such designs may include load meters readings based on motor current speed based jam detec tors hall effect sensors for reading motor speed or other types of speed sensors e g provided on the cutter shafts In some existing cases detection of possible overload or motor stall may be prevented by reversing the motor when the sys tem becomes jammed U S Pat No 4 495 456 entitled Automatic Reversing System for Shredder illustrates an example of such a machine Some shredders may employ a stall or overload detection circuit which monitors a motor s current draw to determine maximum capabilities of the shredding machine and to deter mine if when a motor might stall In such shredders the idea is to prevent the m
2. shredder apparatus used interchangeably throughout this specification are not intended to be limited to devices that literally shred documents and articles but US 8 382 019 B2 5 instead intended to cover any device that destroys documents and articles in a manner that leaves such documents and articles illegible and or useless As noted the shredder 10 also comprises a shredder mechanism 20 shown generally in FIG 2 in the shredder housing 12 When articles are inserted into the at least one input opening or throat 14 they are directed toward and into shredder mechanism 20 e g see FIG 4 Shredder mecha nism is a generic structural term to denote a device that destroys articles using at least one cutter element Destroying may be done in any particular way For example the shredder mechanism may include at least one cutter element that is configured to punch a plurality of holes in the document or article in a manner that destroys the document or article Shredder mechanism 20 includes a drive system 32 with at least one motor 34 such as an electrically powered motor and a plurality of cutter elements 21 shown in FIG 4 The drive system 32 may have any number of motors and may include one or more transmissions The motor 34 may be an AC induction motor for example In another embodiment the motor may be a DC motor a permanent magnet motor a universal motor or any other type of motor In the illustrated
3. 10 will be a standard power cord 44 with a plug 48 on its end that plugs into a standard AC outlet Also a control panel may be pro vided for use with the shredder 10 Generally the use of a control panel is known in the art As shown in FIG 1 a power switch 35 or a plurality of switches may be provided to control operation of the shredder 10 The power switch 35 may be provided on the upper side 24 of the shredder housing 12 for example or anywhere else on the shredder 10 The upper side 24 may have a switch recess 28 with an opening therethrough An on off switch 35 includes a switch module not shown mounted to housing 12 underneath the recess 28 by fastening devices and a manually engageable portion 30 US 8 382 019 B2 7 that moves pivotally within recess 28 i e a rocker switch The switch module has a movable element not shown that connects to the manually engageable portion 30 to move the switch module between its states Movement of the manually engageable portion of switch 35 moves the switch module between states In the illustrated embodiment shown in FIG 2 the switch module connects the motor 34 to the power supply This connection may be direct or indirect such as via a controller 42 shown in FIG 3 The term controller is used to define a device or microcontroller having a central processing unit CPU or microprocessor and input output devices that are used to monitor parameters from devices that at oper
4. 460 Bl 1 2004 Motsenbocker DE 4207292 1 1993 6 698 640 B2 3 2004 Hakozaki DE 4237861 5 1994 6 724 324 Bl 4 2004 Lambert DE 4437348 4 1996 6 802 465 10 2004 Norcott et al DE 19835093 2 1999 6 979 813 B2 12 2005 Avril DE 202004000907 5 2005 6 983 903 B2 1 2006 Chang DE 102006036136 1 2008 6 997 408 B2 2 2006 Watano DE 202010001577 U1 11 2010 7 025 293 B2 4 2006 Matlin et al EP 268244 11 1987 7 040 559 B2 5 2006 Matlin EP 0392867 10 1990 7 166 561 B2 1 2007 Allen EP 562076 9 1992 7 210 867 Bl 5 2007 Silverbrook EP 524708 1 1997 7 213 780 B2 5 2007 Chen EP 0792691 9 1997 7 311 276 B2 12 2007 Matlin et al EP 0818241 1 1998 7 520 452 B2 4 2009 Watano et al EP 856945 1 1998 7 624 938 B2 12 2009 Aries et al EP 855221 7 1998 7 631 822 B2 12 2009 Matlin et al EP 1177832 2 2002 7 631 823 B2 12 2009 Matlin et al EP 1195202 4 2002 7 631 824 B2 12 2009 Matlin et al EP 2180290 7 2008 7 635 102 B2 12 2009 Matlin et al EP 2022566 2 2009 7 661 614 B2 2 2010 Matlin et al GB 1199903 7 1970 7 663 769 B2 2 2010 Hayashihara et al GB 2171029 8 1986 7 712 689 B2 5 2010 Matlin et al GB 2209963 6 1989 2003 0016365 Al 1 2003 Liess et al GB 2440651 2 2008 2003 0042342 Al 3 2003 Kroger et al GB 2442942 4 2008 2004 0008122 Al 1 2004 Michael GB 2451513 2 2009 2004 0069883 Al 4 2004 Watanabe et al JP 5311911 3 1978 2004 0159198 Al 8 2004 Peot et al JP 57 76734 1 1982 US 8 382 019 B2 Page 3 JP 57 070445 4 1982 WO 2005070553 8 2005 JP 57 070445 U 4 1
5. a plastic material or any other material The shredder housing 12 and its upper wall 24 may have any suitable construction or configuration Shredder housing 12 also comprises an output opening 16 ona lower side 26 or bottom side or bottom wall or underside or bin side shown in FIG 2 In an embodiment shredder housing 12 may include a bottom receptacle 38 with lower side 26 to receive shredder mechanism 20 along with a motor 34 transmissions etc therein For example the bottom receptacle 38 may have a bottom wall forming lower side 26 four side walls and an open top Bottom receptacle 38 is generally defined as a device or part of housing 12 for at least assisting in securing the shredder mechanism 20 within and or to the housing 12 The bottom receptacle 38 may be molded from a plastic material or any other material Bottom recep tacle 38 may be affixed to the underside of the upper side 24 or top wall base fasteners for example The receptacle 38 has output opening 16 in its bottom side 26 or bottom wall through which shredded particles are discharged Though lower side 26 is shown as comprising a bottom receptacle 38 the configuration shape or design of lower side 26 or recep tacle 38 should not be limiting Generally speaking the shredder 10 may have any suitable construction or configu ration and the illustrated embodiments provided herein are not intended to be limiting in any way In addition the term shredder or
6. published on Feb 10 1997 JP 2000346288 12 2000 U S Appl No 60 613 750 filed Sep 27 2004 Pierce JP 2002 239405 8 2002 U S Appl No 60 686 490 filed May 31 2005 Pierce JP 2002239405 8 2002 U S Appl No 60 688 285 filed Jun 7 2005 Pierce JP 2004 321840 11 2004 JP 2004321993 11 2004 cited by examiner U S Patent Feb 26 2013 Sheet 1 of 11 US 8 382 019 B2 US 8 382 019 B2 Sheet 2 of 11 Feb 26 2013 U S Patent FIG 2 U S Patent Feb 26 2013 Sheet 3 of 11 US 8 382 019 B2 DETECTOR CONTROLLER 46 CURRENT SENSOR SHREDDER MECHANISM FIG 3 U S Patent Feb 26 2013 Sheet 4 of 11 US 8 382 019 B2 U S Patent Feb 26 2013 Sheet 5 of 11 US 8 382 019 B2 56 TIME sec 5 Sor ea EON A EVENT SET 50 58 7 0 52 U S Patent Feb 26 2013 Sheet 6 of 11 US 8 382 019 B2 61 X BEGIN SHREDDING EVENT 22 64 DRAW CURRENT USING MOTOR DETECT INITIAL AMOUNT INRUSH 66 CURRENT DRAWN USING CURRENT SENSOR SET PARAMETER OF SHREDDER BASED ON 68 INRUSH CURRENT USING CONTROLLER 70 END SHREDDING EVENT FIG 6 U S Patent Feb 26 2013 Sheet 7 of 11 US 8 382 019 B2 72 En 74 BEGIN SHREDDING EVENT 76 DRAW CURRENT USING MOTOR DETECT INITIAL AMOUNT INRUSH 78 CURRENT DRAWN USING CURRENT SENSOR SET OVERLOAD DETECTION THRESHOLD 80 OF SHREDDER BASED ON INRUSH CURRENT USING CONTROLLER 82 END SHREDDING EVENT FIG 7 U S Patent
7. 0 e e oo US 8 382 019 B2 1 IN RUSH CURRENT JAM PROOF SENSOR CONTROL BACKGROUND OF THE INVENTION 1 Field of Invention The present invention relates to shredders for destroying articles such as documents CDs etc 2 Description of Related Art Shredders are well known devices for destroying substrate articles such as documents CDs floppy disks etc Typically users purchase shredders to destroy sensitive articles such as credit card statements with account information documents containing company trade secrets etc A common type of shredder has a shredder mechanism contained within a housing that is removably mounted atop a container The shredder mechanism typically has a series of cutter elements that shred articles fed therein and discharge the shredded articles downwardly into the container The shredder typically has a stated capacity such as a number of sheets of paper typically of 20 Ib weight that may be shred ded at one time however the feed throat of a typical shredder can receive more sheets of paper than the stated capacity A common frustration of users of shredders includes feeding too many papers into the feed throat only to have the shredder jam after it has started to shred the papers
8. 496 A1 12 409 896 12 466 775 12 487 220 12 348 420 and 11 770 223 U S Patent Application Publication No 2007 0246586 A1 also owned by Fellowes Inc as detectors that may be used Other examples of known shredders with thickness sensing features US 8 382 019 B2 15 designed to prevent the cutter elements from jamming are U S Patent Application Publication Nos 2009 0025239 Al 2007 0246582 A2 and 2009 0032629 Al U S patent appli cation Ser No 12 790 517 filed May 28 2010 is also an example of a thickness sensor that may be used with shredder 10 and may be set in real time based on the detected inrush current Each of the references provided herein are incorpo rated by reference in their entirety and are not meant to be limiting As is described in the above references if a detector 44 determines that the thickness of an article in the throat 14 is substantially equal to or great than the maximum thickness threshold e g there are too many sheets or pages the con troller 42 is used to stop or prevent the motor 34 from driving the cutter elements 21 in the shredding direction Likewise the controller 42 can stop the current flow to the motor 34 In an embodiment the thickness of the shredder may not need to be set or reset for each consecutive shredding event For example the thickness may remain at its current setting based on the detected inrush current of two consecutive shredding events Logic or other algorit
9. 8 Munakata et al 50100134803 A1 5 772 129 A 222 Nishio et al 2010 0170967 Al 7 2010 Jensen et al EDE dai 2010 0170969 Al 7 2010 Jensen etal 823 2010 0176227 Al 7 2010 Davis et al 5 850 342 12 1998 Nakamura et al 2010 0181398 Al 7 2010 Davis et al 5 850 588 A 12 1998 Yoshikawa 399 327 2010 0213296 Al 8 2010 Sued et al 5 871 162 A 2 1999 Rajewski 2010 0213297 Al 8 2010 Sued et al 5 924 637 A 7 1999 Niederholtmeyer 2010 0213300 Al 8 2010 Matlin et al D412 716 S o Kroger 2010 0243774 Al 9 2010 Hu etal AUR 2 mn 2010 0252661 Al 10 2010 Matlin et al 2010 0252664 Al 10 2010 Matlin et al 5 988 542 A 11 1999 Henreckson 2010 0270404 Al 10 2010 Chen sp a PR 2010 0282879 Al 11 2010 Chen 2010 0288861 Al 11 2010 Caietal 6 079 645 A 6 2000 Henreckson et al 2010 0320297 Al 12 2010 Matlin et al 6 116 528 9 2000 Schwelling 2010 0320299 Al 12 2010 Matlin et al 6 141 883 11 2000 Mitchell et al 6 265 682 Bl 7 2001 Lee 6 376 939 Bl 4 2002 Suzuki et al 2011 0272504 Al 11 2011 Matlin et al 2011 0272505 Al 11 2011 Matlin et al 2011 0280642 Al 11 2011 Ikeda etal 6 418 004 7 2002 Mather et al a 6550701 Bl 4 2003 Chang 2011 0297769 Al 12 2011 Matlin et al 6 561444 Bl 5 2003 Yokomine et al 2011 0297770 1 12 2011 Matlin et al 6 601 787 Bl 8 2003 Langenecker 6 655 943 B1 12 2003 Peterson FOREIGN PATENT DOCUMENTS 6 666 959 B2 12 2003 Uzoh et al DE 4121330 1 1993 6 676
10. 982 WO 2006019985 2 2006 JP 58 223448 12 1983 WO 2006036370 4 2006 JP 59150554 8 1984 WO 2007109753 9 2007 JP 61 000702 1 1986 WO 2007122364 11 2007 JP 62183555 11 1987 WO 2007137761 12 2007 JP 63 173342 11 1988 2 277560 11 1990 OTHER PUBLICATIONS us eere yo ACCO Rexel Mainstream 1050 2150 2250 3150 3250 and 3350 IP 04 0180852 6 1992 115V Machines Illustrated Parts Lists and Services Instructions Mar JP 5 96198 4 1993 25 2002 Issue No 4 JP 05 092144 4 1993 ACCO Rexel Deckside and Office 115V Machines Illustrated Parts JP 6 277548 10 1994 Lists and Service Instructions Aug 18 1999 JP 7 299377 11 1995 ACCO Rexel Deckside and Office 230V Machines Illustrated Parts JP 8 108088 4 1996 Lists and Service Instructions Aug 1 2000 JP 8 131861 5 1996 GBC Shredmaster Service Manual Part 6001054 referencing JP 08 131962 5 1996 Models 2230S and 2250X Paper Shredders Nov 1997 JP pepe 6 1996 The Stati d Business Machines Japan DS 4000 by Carl TP 52 11601 1 1997 he Stationary and Business Machines Japan y Car 9 38513 2 1997 Jimuki Jun 2003 IP 09075763 3 1997 The Stationary and Business Machines Japan NSE 501CN by Jp 09 150069 10 1997 Nakabayashi Oct 2004 JP 9 262491 10 1997 International Search Report and Written Opinion for PCT US2011 JP 10 048344 2 1998 031922 dated Oct 6 2011 JP 11 216383 8 1999 English Translation of Japanese Patent Application Publication No JP 11 304942 11 1999 9 385 13
11. Feb 26 2013 Sheet 8 of 11 US 8 382 019 B2 84 86 BEGIN SHREDDING EVENT 88 DRAW CURRENT USING MOTOR DETECT INITIAL AMOUNT INRUSH 90 CURRENT DRAWN USING CURRENT SENSOR SET THICKNESS OF SHREDDER BASED ON 92 INRUSH CURRENT USING CONTROLLER 94 END SHREDDING EVENT FIG 8 ea S1JJHS e 5 im 6 Old a q V e awy IWIL DN l GZ OLLO 00 00000 10 00 00005 00 00 000 05 00 00 00006 00 00 000 02 00 00 000 0 00 00 000 00 00 00 _ 000 00 0 00 0 001 30 po usg es AG I X 00 lt FOOL OL x 00 9 70 122 S 2 WEE a p s 009 lt 0 002 07 3 00 KI R4 E sea 050 5 as 006 0 99 m000l 050 090 en ool Lose 9 cg 5 oz fool e le roor 07 S 00 L 11715 ETA 2002 09 E 00 1 zo Osr SP gg of 00 S MEM pL pod os 06 0091 80 2 09 S6 00l LOSS 2626 001 0091 60 SLL GOL PN 1009 09 Ol 0061 679 Sll 0002 Ol 059 5 59 cl U S Patent U S Patent Feb 26 2013 Sheet 10 of 11 US 8 382 019 B2 RI 82K 120 324 R13 R12 1 Pec Q4 200K 2 2UF 50V 7 AV RIA 1013 0 3 10W ZN i 1 1 1 1 1 1 1 IN4148 4 1 1 1 1 U S Patent Feb 26 2013 Sheet 11 of 11 US 8 382 019 B2 MOTOR_CURRENT_AC SAFE LINE IN4007 CAP POLL 479 25 RL 7747 100
12. US008382019B2 a2 United States Patent 10 Patent No US 8 382 019 B2 Romanovich et al 45 Date of Patent Feb 26 2013 54 IN RUSH CURRENT JAM PROOF SENSOR 4 378 717 A 4 1983 Schneider et al CONTROL 4 489 897 A 12 1984 Turner 4 495 456 A 1 1985 Vercillo et al R 4 497 478 A 2 1985 Reschenhofer 75 Inventors Dmitry Romanovich Wheaton IL 4 683 381 A 7 1987 Dufoug ae Dale Jensen Wood Dale Continued FOREIGN PATENT DOCUMENTS 73 Assignee Fellowes Inc Itasca IL US DE 3313232 10 1984 DE 8619856 4 10 1988 Notice Subject to any disclaimer the term of this Continued patent is extended or adjusted under 35 U S C 154 b by 316 days OTHER PUBLICATIONS 21 Appl No 12 772 722 Complaint for Declaratory Judgment filed on Nov 15 2010 by Royal Applicance Manufacturing Co d b a TII Floor Care North 22 Filed May 3 2010 America and Techtronic Industries Co Ltd against Fellowes Inc 65 Prior Publication Data Continued US 2011 0266379 Al 3 2011 Primary Examiner Bena Miller Agent or Firm Pillsbury Winthrop Shaw 51 Int Cl ittman 02 4 32 2006 01 02 7 14 2006 01 57 ABSTRACT 02 9 04 2006 01 shredder and a method for monitoring a motor of a shredder 52 USCI aiii ela 241 36 241 100 241 236 comprises a housing having a throat for receiving an article 58 Field of Classification Search 241 33 shredder mechanism received
13. ation ofa detector and shredder mechanism in the shredder of FIG 1 in accordance with an embodiment of the present invention FIG 5 is a 3 D graph illustrating relationships between current time and shredding events in accordance with embodiments of the invention FIG 6 is a flow diagram of a method for monitoring opera tion of a shredder in accordance with an embodiment of the invention FIG 7 is a flow diagram of a method for setting of an overload detection threshold for the shredder FIG 8 is a flow diagram of a method for setting a thickness of an article that may be accepted by the shredder FIG 9 is a 2 D graph illustrating relationships between current shredding events thickness and time in accordance with an embodiment of the invention 25 40 45 60 4 FIGS 10 and 11 are exemplary schematic motor current detection circuit diagrams which may be used in accordance with an embodiment of the invention DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT S OF THE INVENTION As will become further evident in the description below the herein described jam proof sensor is defined as a sensor that is configured to consider an initial inrush current of a motor when the motor is initially supplied with power to operate e g rotate in order to determine at what current draw the motor will stall The initial inrush current is used to set a parameter e g overload detection threshold or maxi mum thickness thresho
14. atively coupled to the controller 42 e g field pro grammable gate array The input output devices also permit the CPU to communicate and control the devices e g one or more sensors such as current sensor 46 described below that are operatively coupled to the controller 42 The controller 42 may be one controller or comprises multiple controllers For example in an embodiment each one of the multiple control lers may be provided in shredder 10 for one or more specific functions At least one controller is coupled to current sensor 46 and or used to detect inrush current For example in an embodiment the controller may be a part of a separate dis tinct system that is designed for monitoring the current sensor 46 and motor 34 Also the controller and its related compo nents for the current sensor 42 may be added to an existing machine and or provided at the time manufacturing The con troller 42 as shown and described is used for explanatory purposes only and should not be limiting As is generally known in the art the controller 42 may optionally include any number of storage media such as memory or storage for monitoring or controlling the sensors coupled to the control ler The controller 42 likewise communicates with the motor 34 of the shredder mechanism 20 as shown by the schematic illustration in FIG 3 When the switch 35 is moved to an on position the controller 42 can send an electrical signal to the drive of the mot
15. claim 2 wherein the control ler is configured to adjust the overload detection threshold based on the detected inrush current for each shredding event 4 shredder according to claim 2 wherein the threshold is set based on a fraction of the detected inrush current 5 shredder according to claim 1 wherein the controller is configured to set a maximum thickness threshold for shred ding articles with the shredder mechanism and wherein upon detection by the controller that the at least one article received by the throat is substantially equal to or greater than the maximum thickness threshold the controller is config ured to limit the electrical power to the motor thereby pre venting the motor from driving the cutter elements in the shredding direction 6 The shredder according to claim 5 wherein the control ler is configured to adjust the maximum thickness threshold based on the detected inrush current for each shredding event 7 The shredder according to claim 1 further comprising a detector for detecting the at least one article received in the throat the detector being coupled to the controller 8 The shredder according to claim 7 wherein the detector is a thickness detector configured to detect a thickness of the at least one article and wherein the controller is coupled to the thickness detector and the parameter is a maximum thick ness threshold 9 The shredder according to claim 8 wherein the control ler is c
16. d B an increase in thickness of the article the paper itself or the number of sheets can affect the motor drawn current during a shredding event Thus setting or adjusting a maximum thickness thresh old in real time relative to the motor s characteristics e g peak torque can prevent possible motor stalls For example using both runs A and B of FIG 9 as an exemplary guide the measured peak inrush is virtually on the stall current The measured inrush current in these cases may be approximately 90 to 95 percent of the measured stall current or vice versa For a typical system it is known to designate an x amount of sheets to trigger current limit rather than allowing the system to go to full stall For example if a sheet thickness is approximately to be about 0 1 mm the thickness capacity may be set to no greater than 1 0 mm or 10 sheets Depending on the desired sheet count considered acceptable for shredding the percentage could be adjusted i e the thickness parameter setting can be adjusted For example referring to FIG 9 in an embodiment it may be desirable to trigger the system as being at capacity at a nomi nal voltage frequency e g approximately 75 50 of the inrush current By adjusting this percentage paramter the amount of load to the system before triggering a current limit can be detected It is noted that the percentage or parameter may vary based on different cutting blocks different sized moto
17. detection by the controller 42 that a load on the motor 34 is substantially equal to or greater than the overload detection threshold the controller 42 is config ured to limit the electrical power to the motor 34 thereby preventing the motor 34 from driving the cutter elements 21 in the shredding direction As previously noted the controller is configured to adjust or set the overload detection threshold based on the detected inrush current for each shredding event in real time FIG 7 is a flow diagram of a method 72 for setting of this overload threshold As shown in FIG 6 the US 8 382 019 B2 11 method 72 of FIG 7 begins with a shredding event at 74 i e the motor 34 is supplied with power via the power source in order to rotate the shredder mechanism 20 The motor draws current at 76 At 78 the inrush current drawn or supplied to the motor for each shredding event is determined or detected using the current sensor 46 Then at 80 the controller 42 sets the overload detection threshold of the shredder based on the determined inrush current at 78 if needed The shredding event ends as shown at 82 and the process repeats for each shredding event The method or algorithm used to set the overload detection threshold should not be limiting In an embodiment the over load detection threshold may be directly or indirectly set based on the inrush current detected In an embodiment the overload detection threshold is set at a fractio
18. diment shredder housing 12 comprises a lip 22 seat or other structural arrangement that corresponds in size and shape with a top edge 19 of the container 18 The container 18 receives paper or articles that are shredded by the shredder 10 within its opening 15 More specifically after inserting materials into input opening 14 for shredding by cutter elements 21 the shredded materials or articles are deposited from the output opening 16 on the lower side 26 of the shredder housing 12 into the opening 15 of container 18 The container 18 may be a waste bin for example In an embodiment the shredder 10 may comprise roller members 23 in the form of wheels or casters to assist in moving the shredder 10 For example the container 18 may include wheels on its bottom e g near the corners as shown in FIG 1 so that the shredder 10 can be transported from one place to another In an embodiment the container 18 may be positioned in a frame or a freestanding housing e g formed of molded plastic or other material beneath the shredder housing 12 For example the frame may be used to support the shredder housing 12 as well as comprise a container receiving space so that the container 18 may be removed therefrom The frame may include a bottom wall three side walls an open front and an open top The side walls of the frame provide a seat on which the shredder housing 20 is removably mounted For example in an embodiment a container 18 may be
19. e to be shredded a shredder mechanism received in the housing and includ ing an electrically powered motor and cutter elements the shredder mechanism enabling the at least one article to be shredded to be fed into cutter elements and the motor being operable to drive the cutter elements in a shredding direction so that the cutter elements shred the articles fed therein upon receiving electrical power via a power source a current sensor for detecting current flowing through the motor acontroller coupled to the motor for controlling operation of the motor the controller also being coupled to the current sensor and configured to detect at least an inrush current supplied to the motor for each shredding event of a plurality of shredding events and the controller being configured to set a parameter of the shredder based on the detected inrush current supplied to the motor 2 A shredder according to claim 1 wherein the controller is configured to set an overload detection threshold at or before which the motor will stall and wherein upon detec tion by the controller that a load on the motor is substantially equal to or greater than the overload detection threshold the controller is configured to limit the electrical power to the motor thereby preventing the motor from driving the cutter elements in the shredding direction 5 0 20 25 30 35 40 45 50 55 60 65 18 3 The shredder according to
20. e to be shredded a shredder mechanism received in the housing and including an electri cally powered motor and cutter elements the shredder mechanism enabling the at least one article to be shredded to be fed into cutter elements and the motor being operable to drive the cutter elements in a shredding direction so that the cutter elements shred the articles fed therein upon receiving power via a power source a current sensor for detecting current flowing through the motor and a controller coupled to the current sensor and coupled to the motor for controlling operation of the motor the method including detecting with the controller an inrush current supplied to the motor for each shredding event and setting with the controller a parameter of the shredder basedon the determined inrush current supplied to the motor Other objects features and advantages of the present invention will become apparent from the following detailed description the accompanying drawings and the appended claims BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a perspective view of a shredder constructed in accordance with an embodiment of the invention FIG 2 is an exploded perspective view of the shredder of FIG 1 FIG 3 is a schematic illustration of an embodiment of a detector a controller a current sensor and a shredder mecha nism with a motor in accordance with an embodiment of the invention FIG 4 is a cross section showing a schematic illustr
21. echanism 20 The motor draws current at 88 At 90 the inrush current drawn or supplied to the motor for each shred ding event is determined or detected using the current sensor 46 Then at 92 the controller 42 sets the maximum thickness threshold of the shredder based on the determined inrush current at 90 if needed The shredding event ends as shown at 94 and the process repeats for each shredding event The graph in FIG 5 shows anumber of spikes labeled as 74 that occur during the period of time of the shredding events These spikes 74 indicate that additional current is being sup plied or drawn by the motor 34 Such spikes 74 may occur due to an increase in an article s thickness during shredding such due to paper folds or creases that may occur during feeding or due to one or more additional articles pages being added to the throat as the article is pulled into the cutter elements 21 during shredding When thicker articles are inserted into the throat 14 or when additional articles are added to the throat 14 that increase the thickness the shredder mechanism 20 becomes more susceptible to jams Moreover if a jam does occur and the motor 34 can not reverse its direction the motor is likely to stall due to any one or more of reaching peak forward torque peak current limit peak temperature etc Determining or tracking the time between successive shredding events can allow for adjustment of the thickness settings e g if multip
22. edetermined thicknesses between the first and second predetermined thicknesses The yellow lights may be used to train the user into getting a feel for how many docu ments should be shredded at one time The red light s indi cate that the detected thickness is at or above the second predetermined thickness which may be the same as the pre determined maximum thickness threshold thereby warning the user that this thickness has been reached U S Application Publication No 20090090797 Al Ser No 11 867 260 filed on Oct 4 2007 and assigned to the same assignee Fellowes Inc illustrates and describes such a progressive system and is hereby incorporated by reference in its entirety Similarly the aforementioned indicators ofthe progressive indicator system may be in the form of audible signals rather than visual signals or lights For example like the yellow lights described above audible signals may be used to pro vide a progressive indication of the thickness of the item Also in an embodiment the visual and audible signals may be used together in a single device Also other ways of indicating progressive thicknesses ofthe items inserted in the throat 14 may be used and the illustrations and descriptions of indicator 37 should not be limiting Other embodiments include incorporating the above method into a computer program product or a set of computer executable instructions readable by a computer and stored on a data carrier o
23. embodiment the cutter elements 21 are generally mounted on a pair of parallel mounting shafts 25 as shown in FIG 4 The motor 34 operates using electrical power to rotatably drive first and second rotatable shafts 25 of the shredder mecha nism 20 and their corresponding cutter elements 21 through a conventional transmission 36 so that the cutter elements 21 shred or destroy materials or articles fed therein via throat 14 and subsequently deposit the shredded materials into open ing 15 of container 18 via the output opening 16 The opera tion and construction of such a shredder mechanism 20 are well known and need not be described herein in detail Gen erally any suitable shredder mechanism 20 known in the art or developed hereafter may be used The shredder mechanism 20 may also include a sub frame 31 for mounting the shafts 25 motor 34 and transmission 36 of the drive system 32 and cutter elements 21 In some cases the subframe 31 may be connected to both an upper side 24 e g on an underside of upper side 24 and a lower side 26 e g on an upper side of receptacle 38 to secure the shredder mechanism 20 within or to the housing 12 For example one or more connecting portions 40 may be provided to secure or fasten the frame 31 thereto Generally devices such as fas teners screws or bolts and nuts may be used to secure the frame 31 to the upper side 24 and lower side 26 ofhousing 12 Additionally and or alternatively shock abs
24. ent supplied to the motor Another aspect of the invention provides a method for monitoring operation of a shredder the shredder comprising ahousing having a throat for receiving at least one article to be shredded and a shredder mechanism received in the housing and including an electrically powered motor and cutter ele US 8 382 019 B2 3 ments The shredder mechanism enables the at least one article to be shredded to be fed into cutter element and the motor is operable to drive the cutter elements in a shredding direction so that the cutter elements shred the articles fed therein upon receiving power via a power source The shred der has a current sensor for detecting current flowing through the motor and a controller coupled to the current sensor and coupled to the motor for controlling operation of the motor The method includes powering the motor with electrical power via the power source detecting with the controller an inrush current supplied to the motor for each shredding event and setting with the controller a parameter of the shredder based on the determined inrush current supplied to the motor Yet another aspect of the invention provides a computer program product having a computer usable data carrier stor ing instructions that when executed by a computer cause the computer to perform a method for monitoring operation of a shredder the shredder including a housing having a throat for receiving at least one articl
25. equency and power may cause potential overload of the motor A spike of current caused at stall is shown generally at 118 as a high current peak that lasts approximately 1 second Also shown in an inrush spike The inrush and stall spikes in this run are rela tively close because paper was already in the throat when the machine was turned on during testing so the machine went right from in rush to stall Such a load 10 sheets or more may cause potential over load of the motor A spike of current caused at stall is shown generally at 109 as a high current peak that lasts approxi mately 1 second Also shown in an inrush spike which is relatively larger but shorter in duration as compared to the 20 25 30 35 40 45 50 55 60 65 14 stall spike In this illustration it can generally be seen that the stall spike at is slightly greater than the inrush spike of cur rent It is noted that in the particular example shown in FIG 7 the power factor of the tested motor was less when run at 50 Hz as compared to the 60 Hz function of the same motor which may be likely due to flux saturation in the windings for example For this reason the 50 Hz signals sag from no load while shredding while at 60 Hz the current increases during shredding Other motors may produce alternate results for current load during shredding however the inrush current and stalling concepts will be similar As shown in each of the runs A an
26. hms may be used with the shredder 10 to make such determinations FIGS 10 and 11 are exemplary schematic motor current detection circuit diagrams which may be used in accordance with an embodiment of the invention The circuit diagram of FIG 10 shows the use of a current sensor in the form of a resistor R14 and an op amp circuit to monitor the current As the current passes through the TRIAC Q3 and thus resister R14 a voltage is generated The diode half wave D11 recti fies the voltage to make it a DC output voltage which is readable by processors or CPUs such as those in controller 42 Then a conditioning circuit 120 is used to filter and amplify the circuit The circuit diagram of FIG 11 shows the use of a current sense transformer T1 The current passes through transformer T1 through the primary windings on the right side and burden resistor R5 turns the current through the secondary windings on the left side of the transformer into a voltage The diode D2 is used to half wave rectify the signal to give a DC output The resistor and capacitor networks are used to smooth the signal to eliminate AC content For example if 25 Amps is passed through the primary windings then with a 1000 1 turn ratio the secondary windings would give 0 025 Amps at the output When that current passes through a 200 ohm resistor 5 volts would be achieved The processor or controller or computer would see that voltage less the diode drop and less
27. ied to the shredder 10 power is not being used by the motor 34 to drive the shafts 25 Thus a shredding event is not occurring However if the controller 24 instructs the motor 34 to activate the shredder mechanism 20 for example upon receipt of an article in the throat 14 then the motor 34 receives electrical power and in turn rotates the shredder mechanism 20 The motor 34 may stop rotation after the article is no longer detected or after a delay period after it is no longer detected e g the article has been shredded Thus the shredding event lasts the period from which the controller 42 controls operation of the motor 34 and power is drawn by the motor 34 to rotate the mechanism 20 until the controller 42 stops operation of the motor 34 When a shredding event begins the controller 42 detects an initial amount of current that is supplied to the motor 34 In the art this initial amount of current is known as inrush current Inrush current is the maximum input current drawn by an electrical device when it is first turned on or first draws power i e when power is supplied to the motor 34 to rotate the shredder mechanism 20 which can be for each shredding event The level of inrush current relative to motor stall run may vary based on motor type but any inductive load has an inrush For example FIG 5 is an exemplary 3 D graph illus trating relationships between current noted as 48 in Amps time noted as 50 in seconds
28. in the housing for shred 241 35 36 100 236 27 30 ding the article the mechanism including an electrically pow See application file for complete search history mn Vane and 2 elements v uos being oper e to drive the cutter elements in a shredding direction to shre 56 References Cited articles A current sensor for detecting current flowing through the motor and a controller coupled to the motor for U S PATENT DOCUMENTS controlling operation of the motor are also provided The 2 221 516 A 4 1937 Hathaway controller is also coupled to the current sensor and configured 3 619 537 A 11 1971 Hosokawa et al to detect at least an initial amount of current or inrush cur 3 724 766 A 4 1973 Bosland rent supplied to the motor for each shredding event Based on 3 764 819 10 1973 Muller the inrush current the controller sets a parameter e g over 3 785 230 A 1 1974 Lokey 5 c 3820850 A 8 1974 Guetersloh load or thickness to prevent overloading or stalling of the 3 947 734 3 1976 Fyler motor such as caused by a jam or overheating 4 192 467 A 3 1980 Hatanaka 4 352 980 A 10 1982 Hibari 22 Claims 11 Drawing Sheets US 8 382 019 B2 Page 2 U S PATENT DOCUMENTS 2004 0194594 Al 10 2004 Dils et al 2004 0226800 Al 11 2004 Pierga 4 707 704 A 11 1987 Allen 2005 0046651 Al 3 2005 Askren et al 4 757 949 A 7 1988 Horton 2005 0150986 Al 7 2005 Castronovo 4 814 632 A 3 1989 Glaeser 2005 0213106 Al 9 2005 Weijers et a
29. ing block assembly For example as shown in FIG 5 the inrush current and thus the peak motor stall current may change during operation of the shredder 10 By tracking this change the limitations of the machine can be observed and one or more parameters of the shredder 10 can be adjusted accordingly Using the herein described method and devices also elimi nates the need for additional components or sensors for sens ing performance characteristic s of the motor 34 The system will know the capabilities of the machine regardless of other characteristics For example the shredder 10 automatically compensates for motor heat line voltage frequency varia tions as well as for component tolerances and assembly variances There is no need for a motor temperature sensor to detect the temperature of the motor because the overload detection threshold is set based on the inrush current and the motor would not reach a peak temperature before this thresh old Of course although such sensors are not required in an embodiment the shredder 10 may include one or more sen sors not shown for sensing a performance characteristic e g temperature of the motor 34 Monitoring such a per formance characteristic is generally known in the art and therefore is not explained in detail herein From a development sales point of view this system and method may be beneficial when developing shredders for those markets which operate in both 50 amp 60 Her
30. l 4 815 669 A 3 1989 Fuji 2006 0016919 Al 1 2006 Castronovo 4 842 205 A 6 1989 Araki 2006 0054725 Al 3 2006 Matlin 4 889 291 A 12 1989 Goldhammer et al 2006 0091247 AI 5 2006 Matlin 4 890 797 A 1 1990 Fujii et al 2006 0243631 Al 11 2006 Duke 4 914 721 A 4 1990 Glaeser 2007 0007373 Al 1 2007 Matlin 5 017 972 A 5 1991 Daughton 2007 0025239 Al 2 2007 Jain etal 5 081 406 A 1 1992 Hughes et al 2007 0063082 Al 3 2007 Coleman 5 139 205 A 8 1992 Gallagher et al 2007 0080252 Al 4 2007 Pierce 5 166 679 A 11 1992 Vranish et al 50010087022 AT 2a DOO AER 5 167 374 12 1992 Strohmeyer 2007 0164135 Al 7 2007 Zhong 5 186 398 A 2 1993 Vigneau Jr 2007 0164138 Al 7 2007 Allen 5 198 777 A 3 1993 Masuda et al 2007 0215728 Al 9 2007 Priester 5 342 033 A 8 1994 Iwata 2007 0221767 Al 9 2007 Matlin 5 345 138 A 9 1994 Mukaidono et al 2007 0246582 Al 10 2007 Aries et al 5 353 468 10 1994 Yap 2007 0246586 Al 10 2007 Matlin et al 5 397 890 A 3 1995 Schueler et al 2008 0093487 Al 4 2008 Lee 5 409 171 4 1995 Stangenberg et al 2008 0231261 Al 9 2008 Dengler et al 5 415 355 A 5 1995 Gollwitzer 2009 0025239 Al 1 2009 Pan 5 429 313 A 7 1995 Schwelling 2009 0032629 Al 2 2009 Aries et al 5 453 644 A 9 1995 Yap 2009 0090797 Al 4 2009 Matlin et al 5 494 229 A 2 1996 Rokos 2010 0051731 Al 3 2010 Matlin et al 5 539 322 A 7 1996 Zoughi et al 2010 0084496 Al 4 2010 Matlin et al 5 662 280 A 9 1997 Nishio et al 2010 0102153 Al 4 2010 Matlin et al 5 743 521 A 4 199
31. ld of the shredder so that stalling or overheating can be prevented i e before reaching a current draw at which the motor will stop FIG 1 is a perspective view of a shredder apparatus 10 constructed in accordance with an embodiment of the present invention The shredder 10 is designed to destroy or shred articles such as paper paper products CDs DVDs credit cards and other objects The shredder 10 comprises a shred der housing 12 that sits on top of a container 18 for example The shredder housing 12 comprises at least one input opening 14 on an upper side 24 or upper wall or top side or top wall of the housing 12 for receiving materials to be shredded The input opening 14 extends in a lateral direction and is also often referred to as a throat The input opening or throat 14 may extend generally parallel to and above a shredder mecha nism 20 described below and shown in FIG 4 The input opening or throat 14 may be relatively narrow so as to prevent overly thick items such as large stacks of documents from being fed into therein However the throat 14 may have any configuration In some cases one or more additional or sec ond input openings 14a may be provided in shredder housing 12 For example input opening 14 may be provided to receive paper paper products and other items while a second input opening 14a may be provided to receive objects such as CDs and DVDs credit cards etc The upper wall 24 may be molded from
32. le successive passes have occurred In another embodiment adjustment s of the thickness setting are made directly according to variations in the inrush current e g based on percentage changes from an initial reading stored in memory to a second reading FIG 7 is a 2 D graph illustrating relationships between current shredding events thickness of articles and time for an exemplary shredder Using this shredder a first run A of shredding events were performed at 110 volts and at a fre quency of 50 Hz and a second run B of shredding events were performed at 90 volts and at a frequency of 60 Hz using an AC induction motor As previously noted some markets runs machines using both frequencies However it is to be under stood that the same effects described below would apply to a steady voltage and frequency rate In first run A when power is turned on at 100 there is an initial inrush current 102 of approximately 6 Amps and cur rent is briefly drawn at approximately 4 5 Amps before stop ping A first shredding event 104 is run indicating the same approximate initial inrush current of 6 Amps The first shred ding event 104 was performed using a single 1 sheet of paper for shredding by the shredder mechanism As shown US 8 382 019 B2 13 during shredding the current and power here measured in Watts remain substantially steady the current remains sub stantially close to 4 5 Amps during the shredding of the single shee
33. med at the factory or during manufacture in whicha threshold ofa shredder is adjusted to a specific load e g sheet count on that specific machine This second method may be effective at preventing a user from operating above the ratings of the machine before stalling but it too can also not track variances in drawn motor current due to heat and or AC fluctuations This in turn causes the initial threshold to fluctuate which can either allow excessive load on the system or it can prematurely limit the user from operating the machine within its capabilities In other designs assumptions have to be made using soft ware based on time or an extra thermal device has to be added to the motor to track motor temperature For example assumptions of the current thermal condition of the motor and therefore the maximum load could be approximated by a software algorithm Such assumptions generally assume that all of the motors in mass production have similar thermal characteristics and that the efficiencies of the cutting blocks are similar However such assumptions are generally incor rect Although two motors of the same model can have similar measured temperatures this does not equate to them having the same performance characteristics Variances in material and assembly can change this relationship for example In addition variations in line voltage and frequency are not generally accounted for This can significantly impact the perf
34. ment a visual signal indicating that an article such as article 122 is too thick may be provided in the form of a red warning light which may be emitted from an LED using indicator 37 for example It is also contemplated that a green light may also be provided to indicate that the shredder 10 is ready to operate In an embodiment an indicator 37 may beused which is a progressive indication system that includes a series of indicators in the form of lights to indicate the thickness ofthe stack of documents or other article relative to the capacity of the shredder is provided For example the progressive indication system may include one or more green lights a plurality of yellow lights and one or more red light The green light s indicate that the detected thickness of the item e g a single paper a stack of papers a compact disc a credit card etc that has been placed in the throat 14 of the shredder 10 is below a predetermined thickness and well within the capacity ofthe shredder The yellow lights provide a progressive indication of the thickness of the item In an embodiment a first yellow light located next to the green light would be triggered when the detected thickness is at or above a first predetermined thickness but below a second predetermined thickness that triggers the red light s If there is more than one yellow light each additional yellow light may correspond to thicknesses at or above a corresponding number of pr
35. n of the detected inrush current For example if the detected inrush current is detected and records to be 17 Amps the overload detection threshold may be set at a percentage e g approximately 90 15 5 Amps or approximately 70 12 Amps so that the motor will be reduced or prevented from drawing its peak motor stall current By monitoring in real time the peak inrush current of the motor for each shredding event the herein disclosed system and method can effectively determine the maximum capabil ity of the motor at a given instant The system and method eliminate design assumptions and limitations typically set by using fixed limits or factory calibration methods for overload detection as described in the Related Art section For example in the previously described two traditional methods during manufacture and or before distribution the threshold either has to be calibrated on the line or a fixed value has to be established during the design phase Calibrating on the production line requires paper waste and introduces margin for error The shredder 10 does not require the need for a shredding operation e g shredding paper with shredder mechanism 20 at the factory in order to set the current limit threshold as may be the case in some prior art methods because the current limit threshold is set based on the inrush current detection Also using a fixed current limit setting does not compensate for variability during cutt
36. onfigured to prevent the motor from driving the cutter elements in the shredding direction based on the at least one article received by the throat being substantially equal to or greater than the maximum thickness threshold 10 The shredder according to claim 9 wherein the con troller is configured to adjust the maximum thickness thresh old based on the detected inrush current for each shredding event 11 The shredder according to claim 1 wherein the current sensor is integrated within the controller 12 The shredder according to claim 1 wherein the current sensor is separate from the controller 13 The shredder according to claim 1 wherein the motor is selected from the group consisting of an AC induction motor a DC motor a permanent magnet motor ora universal motor 14 A method for monitoring operation of a shredder the shredder comprising a housing having a throat for receiving at least one article to be shredded a shredder mechanism received in the housing and including an electrically powered motor and cutter elements the shredder mechanism enabling the at least one article to be shredded to be fed into cutter elements and the motor being operable to drive the cutter elements in a shredding direction so that the cutter elements shred the articles fed therein upon receiving power via a power source a current sensor for detecting current flowing through the motor and a controller coupled to the current sensor and coupled
37. or 34 e g contacts in the switch module are closed by movement of the manually engageable portion 30 and the movable element to enable a delivery of electrical power to the motor 34 so that it rotates the cutting elements 21 of the shredder mechanism 20 in a shredding direction thus enabling paper sheets to be fed in the throat 14 to be shredded Additionally or alternatively when the switch 35 is in an on position the switch 35 may be set to an idle standby or ready position which communicates with the control panel The idle or ready position may correspond to selec tively activating the shredder mechanism 20 for example Such a position may allow the controller 42 to selectively enable the operation of the shredder mechanism 20 based on the detection of the presence or insertion of at least one article e g paper in the throat 14 by or based ona waste level or bin full sensing device The switch 35 may also be moved to an off position e g contacts in the switch module are opened to disable the delivery of electric power to the motor 34 which causes the controller 42 to stop operation of the motor 34 Alternatively the switch may be coupled to a controller which in turn controls a relay switch TRIAC etc for con trolling the flow of electricity to the motor 34 The switch module contains appropriate contacts for sig naling the position of the switch s manually engageable por tion As an option the switch 35 may also ha
38. orbing elements vibration absorbing elements and or springs may be used when connecting the shredder mechanism 20 and shredder housing 12 Also the plurality of cutter elements 21 may be mounted on first and second rotatable shafts 25 in any suitable manner For example in an embodiment the cutter elements 21 are rotated in an interleaving relationship for shredding paper sheets and other articles fed therein In an embodiment the cutter elements 21 may be provided in a stacked relationship The operation and construction of such a shredder mecha nism 20 is well known and need not be discussed herein in detail As such the at least one input opening or throat 14 is configured to receive materials inserted therein to feed such materials through the shredder mechanism 20 and to deposit or eject the shredded materials through output opening 16 Shredder housing 12 is configured to be seated above or upon the container 18 The container 18 is formed of molded plastic material or any other material The container 18 includes a bottom wall four side walls and an open top for example As shown in FIG 2 shredder housing 12 may 20 25 30 35 40 45 50 55 60 65 6 comprise a detachable paper shredder mechanism that sits atop container 18 That is in an embodiment the shredder housing 12 may be removed in relation to the container 18 to ease or assist in emptying the container 18 of shredded mate rials In an embo
39. ormance of the motor and impact the stall current reading relative to a fixed threshold As noted above the inrush current initially drawn by a motor when a shredder mechanism is turned on is ignored in prior designs to prevent false readings of overload However as described further herein this disclosure determines and uses this inrush current to determine parameters related to the motor as well as occurrences at which the motor will stall e g due to a jam in the shredder SUMMARY OF THE INVENTION One aspect of the invention provides a shredder having a housing having a throat for receiving at least one article to be shredded and a shredder mechanism received in the housing and including an electrically powered motor and cutter ele ments The shredder mechanism enables the at least one article to be shredded to be fed into cutter elements and the motor is operable to drive the cutter elements in a shredding direction so that the cutter elements shred the articles fed therein upon receiving electrical power via a power source The shredder also has a current sensor for detecting current flowing through the motor and a controller coupled to the motor for controlling operation of the motor The controller is also coupled to the current sensor and configured to detect at least an inrush current supplied to the motor for each shred ding event The controller is configured to set a parameter of the shredder based on the detected inrush curr
40. otor from going into or remaining in a stall condition which not only draws excessive current but also heats the motor prematurely Traditionally these circuits either have a delay or a limiting device e g a thermistor or have software to ignore the initial in rush current drawn by the motor to prevent false positive reactions for possible stalls or short circuits For example a first known traditional method for setting the overload detection threshold includes setting a fixed value close to the stall current ofa machine at its cold state and then determining if a motor s current draw is close to the fixed value 1 using a comparator during operation This first method may be effective on a cold motor 1 a motor that is not running The overload detection circuitry of this type of shredder will only trigger when the motor is stalled about to stall 1 e drawn current is close to the fixed value However 20 25 30 35 40 45 50 55 60 65 2 as a motor heats during use the amount of current being drawn by the motor tends to decrease and AC fluctuations may occur This first method is unable to track any decrease in drawn current as the motor heats or fluctuations This means that a hot i e working or rotating motor will often stall before or without the overload detection circuitry detecting the event A second known method for overload detection is a cali bration that is perfor
41. ould the inrush current change and thus the peak forward torque and or motor temperature at which stalls may occur will also change the controller 42 is configured to set a parameter of the shredder 10 based on the detected initial amount of current inrush current supplied to the motor 34 for each shredding event FIG 6 shows the method 61 for monitoring operation of shredder 10 via motor 34 At 62 a shredding event begins and power is turned on i e the motor 34 is supplied with power via the power source in order to rotate the shredder mecha nism 20 This may be done by the switch 35 being turned to an on position or by one or more sensors sensing an article for shredding The motor draws current at 64 At 66 the inrush current drawn or supplied to the motor for each shredding event is determined or detected using the current sensor 46 Then at 68 the controller 42 sets a parameter of the shredder based on the determined inrush current at 66 1f needed The shredding event ends as shown at 70 and the process repeats for each shredding event In an embodiment the parameter of the shredder may not need to be set or reset for each consecutive shredding event For example the detected inrush current for a first shredding event may be substantially equal or similar to the detected inrush current for a second consecutive shredding event Thus the parameter may remain at its current setting Also in embodiments two or more paramete
42. oviding instructions storing data message packets or other machine readable information associated with the method 61 The computer readable product or medium for example may include non volatile memory and other permanent storage devices that are useful for example for transporting information such as data and computer instructions In any case the medium or product should not be limiting All patents and applications mentioned herein including those in the Related Art section are hereby incorporated herein by reference in their entirety While the principles of the invention have been made clear in the illustrative embodiments set forth above it will be apparent to those skilled in the art that various modifications may be made to the structure arrangement proportion ele ments materials and components used in the practice of the invention It will thus be seen that the objects of this invention have been fully and effectively accomplished It will be realized however that the foregoing preferred specific embodiments have been shown and described for the purpose of illustrating the functional and structural principles of this invention and are subject to change without departure from such principles Therefore this invention includes all modifications encom passed within the spirit and scope of the following claims What is claimed is 1 A shredder comprising a housing having a throat for receiving at least one articl
43. provided to slide like a drawer with respect to a frame e g a pull out bin be hingedly mounted to a frame or comprise a step or pedal device to assist in pulling or removing it therefrom from a front or side of the frame Container 18 may comprise an opening a handle or a recess 17 to facilitate a user s ability to grasp the bin or grasp an area approximate to the recess 17 and thus provide an area for the user to easily grasp to separate the container 18 from the shredder housing 12 thereby pro viding access to shredded materials The container 18 may be substantially or entirely removed from being in an operative condition with shredder housing 12 in order to empty shred ded materials such as chips or strips 1 e waste or trash located therein In an embodiment the shredder 10 may com prise one or more access openings not shown for example in part of the container or part of the shredder housing to allow for the deposit of larger articles therein Generally the terms container waste bin and bin are defined as devices for receiving shredded materials dis charged from the output opening 16 of the shredder mecha nism 20 and such terms are used interchangeably throughout this specification However such terms should not be limit ing Container 18 and or frame may have any suitable con struction or configuration and the illustrated embodiment is not limiting Typically the power supply to the shredder
44. r otherwise a computer readable medium such that the method 61 is automated In a possible embodiment the method may be incorporated into an operative set of processor executable instructions configured for execution by at least one processor ora controller or computer The instruc tions may be incorporated or added to an existing shredder In an embodiment it is envisioned that the controller 42 may comprise program code of machine or processor executable instructions in a memory that when executed instructs the controller 42 to perform the method of monitoring the shred der to operate the shredder 10 detect at least an inrush current and or set a parameter of the shredder 10 The controller 42 processes the instructions and subsequently applies them by detecting the inrush current and setting the parameter FIG 6 shows a flow chart of such computer readable instructions US 8 382 019 B2 17 For example in an embodiment when the executable instruc tions are executed by a computer or processor they cause a computer or processor to automatically perform a method for monitoring operation of the shredder In alternative embodi ments hard wired circuitry may be used in place of or in combination with software instructions to implement the dis closure Thus embodiments of this disclosure are not limited to any specific combination of hardware circuitry and soft ware Any type of computer program product or medium may be used for pr
45. rs gearing etc and a desired trigger point s Therefore in embodi ments the parameters set by the controller may be defined on a per project or per machine basis Thus because the thickness threshold or capacity may be adjusted it is to be understood that in an embodiment one or more detectors 44 may also be provided in the shredder as shown in FIG 3 Detector s 44 are coupled to the controller 42 Inan embodiment a detector 44 may be provided to detect at least one article received in the throat In an embodiment a detector 44 may be a thickness detector configured to detect a thickness ofthe at least onearticle For example the thickness detector 44 may be provided in or adjacent the throat 14 ofthe shredder The assignee of this application Fellowes Inc has developed thickness sensing technologies for shredders By sensing thickness of paper or articles being fed into the shred der the shredder can be stopped or not started before a severe jam occurs U S Pat Nos 7 631 822 7 631 824 7 635 102 and 7 631 823 and U S Patent Application Publi cation Nos 2006 0054725 Al 2009 0090797 Al and 2007 0221767 A1 disclose among other things a detector that can determine if an overly thick object is being inserted in a shredder throat See also U S patent application Ser Nos 12 616 567 U S Patent Application Publication No 2010 0051731 A1 12 579 905 12 578 292 U S Patent Applica tion Publication No 2010 0084
46. rs may be set or reset based on the detected inrush current supplied to the motor Logic or other algorithms may be used with the shredder 10 to make such determinations As such it is to be understood that the parameter examples described further below are not meant to be limiting The parameter set by the controller for each shredding event if setting of such a parameter is needed is designed to be adjusted in real time relative to the maximum capabilities ofthe machine so that elements affecting the working opera tion ofthe motor 34 during shredding events are accounted or compensated for The real time or instantaneous adjustment ofthe parameter allows for a more accurate determination of when motor stalling may occur Additional advantages of setting the parameter based on the inrush current are further described below In an embodiment the parameter set by the controller 42 may bean overload detection threshold at or before which the motor will stall That is the overload detection threshold may be set to a limit that is substantially equal to or less that a maximum load of the motor before stalling will occur The maximum load of a motor can refer to either an amount of mechanical work the motor is performing e g an amount of torque applied to the shafts 25 through each revolution or an electrical load e g resistance of the motor The load may affected by any number of variances torque temperature frequency etc Upon
47. sec and shredding events noted as 52 in numbers s The graph provides data relat ing to an AC induction motor It is noted that the data pre sented throughout this disclosure is related to using an AC induction motor however as noted above the methods and concepts described herein should not be limited to a specific type of motor More specifically FIG 5 shows a series of shredding events using a machine suchas shredder 10 At zero seconds there is no load or power supply i e zero current drawn by the motor of the shredder mechanism as indicated by arrow 54 When a shredding event begins there is a large current spike i e an initial or inrush current that is sup plied to drawn by the motor as shown by arrow 56 It is this measured or detected current that is determined e g using current sensor 46 and recorded for use by the controller further described below When a shredding event has ended e g when there is no article present in the throat and the controller instructs the motor to stop rotation of the shredder mechanism the current gradually decreases back to zero Amps as shown by arrows 58 and 60 Further visual inspection of the graph of FIG 5 shows a slight decrease in inrush current e g see arrow 56 as the number 52 of shredding events occur Inrush current is pro portional to peak forward torque e g feed forward torque and inversely proportional to motor temperature That is as inrush curren
48. such as but not limited to overheating bin open bin full paper jam and flashing indi cators such as when the shredder has stopped or sensed a condition As shown in the schematic illustration of FIG 3 shredder 10 further comprises a current sensor 46 for detecting current flowing through the motor 34 The current sensor 46 may be integrated within the controller 42 or it may be separate from the controller 42 The controller 42 is operatively coupled to the current sensor 46 and is configured to detect at least an initial amount of current supplied to the motor 34 for each shredding event For purposes of this disclosure a shredding event is defined as a period in which electrical power is received by the motor 34 to rotatably drive the first and second rotatable shafts 25 of the shredder mechanism 20 That is when switch 35 is turned to an on position to rotate the shredder mechanism 20 the shredding event begins The shredding event ends when the motor 34 no longer receives power to rotate the shredder mechanism 20 e g when the switch 35 is moved to an off position Alternatively the shredder mechanism 20 may be set to be selectively activated e g upon detection of an article being inserted into the throat 14 by detector 44 with the switch 35 in an idle or standby position Even though switch 35 may be set to an idle US 8 382 019 B2 9 standby or ready position for selective activation and power is being suppl
49. t decreases the peak forward torque decreases In contrast as inrush current decreases motor temperature increases Peak forward torque is the maximum amount of torque that a motor can deliver to a load prior to stalling For example for an AC induction motor the peak torque may be approximately 80 percent of the rated speed In an AC induction motor the peak forward torque may be a torque the motor will deliver if its shaft is prevented from turning e g such as in the case of a jam in the shredder mechanism 20 Alternatively when article s that are too thick are inserted into the throat of the shredder the motor may work harder and the amount of torque required to rotate the shafts and cutter elements may increase near peak forward torque In particu lar if the motor is delivering substantially near or at peak forward torque the motor may be overloaded to stall opera tion and or the motor temperature will be greatly increased Increases in motor temperature due to high torques thick 0 5 20 35 40 45 50 55 60 65 10 articles repeated use etc may also be more likely to cause stalling due to overheating The inrush current is approxi mately equal to the peak motor stall current Based on such information and knowing that motor stall can be a problem and or inconvenience for users this disclosure provides a method for measuring the inrush current for each shredding event so that sh
50. t of paper before dropping off at the end of the shredding event A second shredding event 106 is run using ten 10 sheets of paper The initial inrush current is higher 1 approxi mately 6 5 Amps for this shredding event 106 During the period of the shredding event the current drawn by the motor sags or drops below 4 0 Amps This is a result of poor power factor and the motor being run at an unsatisfactory or abnor mal voltage frequency i e 110V 50 Hz While the current decreases the power slightly increases Then just before the end of the shredding event the current again increases to approximately 4 5 Amps before dropping to zero The third shredding event 108 is run using twelve 12 sheets of paper Here the initial inrush current is approxi mately 6 0 Amps Like the previous shredding event during the period of the shredding event the current drawn by the motor sags or drops again below 4 0 Amps and the power further increases In the illustrated embodiment the current then again increases to approximately 4 5 Amps after shred ding due to run on i e a no load operation of the motor for a time period e g approximately 2 seconds to clean the cutter elements Thereafter once the motor is stopped or turned off the current and power may be dropped to zero Such a load 12 sheets or more may cause potential over load of the motor A spike of current caused at stall is shown generally at 109 as a high curren
51. t peak that lasts approxi mately 1 second Also shown in an inrush spike In this illustration it can generally be seen that the inrush spike is relatively larger but shorter in duration as compared to the stall spike In second run B the current drawn by the motor and power used is much lower at this voltage and frequency When power is turned on at 110 there is an initial inrush current 112 of approximately 5 Amps and current is briefly drawn at approximately 1 25 Amps before stopping A first shredding event 114 is run indicating the same approximate initial inrush current of 5 Amps The first shredding event 114 was performed using a single 1 sheet of paper for shredding by the shredder mechanism As shown during shredding the current and power here measured in Watts remain substan tially steady the current remains substantially close to 1 25 Amps during the shredding of the single sheet of paper before dropping off at the end of the shredding event A second shredding event 116 is run using ten 10 sheets of paper The initial inrush current is slightly higher 1 approximately 5 25 Amps for this shredding event 116 Dur ing the period of the shredding event the current drawn by the motor increases from approximately 1 25 Amps to numerous current spikes between 2 0 and 3 5 Amps This is a result of the load on the motor Thereafter the current and power may be dropped to zero Such a load 10 sheets or more at this fr
52. the filtering loss from the RC network depen dant upon line frequency Of course it is to be understood that in correlation with the thickness detector 44 in some embodiments the shredder 10 may further comprise an alarm indicator system and the predetermined operation e g performed by the controller 42 1s alerting the user via the alarm indicator system For example in an embodiment upon detecting that the article s inserted into the throat 14 exceed the predetermined maxi mum thickness threshold the controller 42 may communi cate with an indicator such as indicator 37 or 39 shown in FIG 1 to provide a warning or alarm signal to the user This signal may be an audible signal in which the controller 42 sounds an audible alarm and or a visual signal wherein the controller 42 may illuminate a visual indicator Examples of audible signals include but are not limited to beeping buzz ing and or any other type of signal that will alert the user via sound s that the article or document that is about to be shredded is above a predetermined maximum thickness threshold and may cause the shredder mechanism 20 of the shredder 10 to jam This gives the user the opportunity to 20 25 30 35 40 45 50 55 60 65 16 reduce the thickness ofthe article or to reconsider forcing the article into the throat 14 and through the shredder knowing that any such forcing may jam and or damage the shredder In an embodi
53. to the motor for controlling operation of the motor the method comprising powering the motor with electrical power via the power source detecting with the controller an inrush current supplied to the motor for each shredding event of a plurality of shredding events and setting with the controller a parameter of the shredder based on the determined inrush current supplied to the motor 15 The method according to claim 14 wherein the con troller sets an overload detection threshold at which the motor will stall and further comprising limiting via the controller the electrical power to the motor to prevent the motor from driving the cutter elements in US 8 382 019 B2 19 the shredding direction upon a load on the motor is substantially equal to or greater than the overload detec tion threshold 16 The method according to claim 15 further comprising adjusting via the controller the overload detection threshold based on the detected inrush current for each shredding event 17 The method according to claim 14 wherein the con troller sets a maximum thickness threshold for shredding articles with the shredder mechanism and further compris ing limiting via the controller the electrical power to the motor to prevent the motor from driving the cutter elements in the shredding direction upon detection by the controller that the at least one article received by the throat is substantially equal to or greater than the maxim
54. truction for these may be used For example a touch screen switch membrane switch or toggle switches are other examples of switches that may be used The switch need not be mechanical and could be of the electro sensitive type Also the switch need not have distinct positions correspond ing to on off idle reverse and these conditions may be states selected in the controller by the operation of the switch Likewise such a switch may be entirely omitted and the shredder can be started based on insertion of an article to be shredded Any of the conditions could also be signaled by lights on a display screen or otherwise For example in an embodi ment one or more indicators such as indicator 37 or 39 shown in FIG 1 may be included to provide a warning signal to the user such as an audible signal and or a visual signal In an embodiment and as further described later indicator 37 may comprise a sheet capacity indictor that pro gressively indicates the thickness of article s or document s being inserted into the opening 14 so as to prevent overload ing and possible jams U S Application Publication No 20090090797 Al Ser No 11 867 260 filed on Oct 4 2007 and assigned to the same assignee Fellowes Inc illustrates and describes such a progressive system and is hereby incor porated by reference in its entirety In an embodiment indi cator 39 may comprise a number of indicators corresponding to functions of the shredder
55. tz Hz frequencies e g such as in Japan As shown and described with reference to FIG 7 for example changes in frequency 20 25 30 35 40 45 50 55 60 65 12 and voltage affect the amount of current and power used by the machine Because the overload threshold parameter is set based on the inrush current the peak motor stall current will not be affected by these fluctuating characteristics In addition to or as an alternative to setting the overload detection threshold in an embodiment the parameter set by the controller 42 may be a maximum thickness threshold for shredding articles with the shredder mechanism 20 The con troller 42 is configured to adjust the maximum thickness threshold based on the detected initial inrush current for each shredding event 1 instantaneously in real time The maximum thickness threshold can be altered e g reduced to reflect any loss in shredder capability over time and or to compensate for the performance of the shredder 10 Based on the drift of the peak inrush as shown by arrow 56 in FIG 5 the parameter at which a detector determines that an article is too thick be automatically adjusted FIG 8 is a flow diagram of a method 84 for setting a thickness of an article that may be accepted by the shredder 10 The method 84 of FIG 8 begins witha shredding event at 86 i e the motor 34 is supplied with power via the power source in order to rotate the shredder m
56. um thickness threshold 18 The method according to claim 17 further comprising adjusting via the controller the maximum thickness threshold based on the detected inrush current for each shredding event 20 19 The method according to claim 14 further comprising detecting with a detector the at least one article received in the throat the detector being coupled to the controller 20 The method according to claim 19 wherein the detector is athickness detector wherein the controller is coupled to the thickness detector and the parameter is a maximum thickness threshold and further comprising detecting a thickness of the at least one article received by the throat 21 The method according to claim 20 wherein the con troller is configured to prevent the motor from driving the cutter elements in the shredding direction based on the at least one article received by the throat being substantially equal to or greater than the maximum thickness threshold 22 The method according to claim 21 further comprising adjusting via the controller the maximum thickness threshold based on the detected inrush current for each shredding event
57. ve a reverse position that signals the controller to operate the motor 34 in a reverse manner This would be done by using a reversible motor and applying a current that is of reverse polarity rela tive to the on position The capability to operate the motor 34 in areversing manner is desirable to move the cutter elements 15 20 25 30 35 40 45 50 55 60 65 8 21 in a reversing direction for clearing jams for example provide each of the noted positions the switch 35 may be a sliding switch e g sliding laterally a rotary switch or a rocker switch For example in an off position the manually engageable portion and the movable element could be located generally in the center of the switch recess and the on and reverse positions would be on opposing lateral sides of the off position A middle or center position could be an idle or standby position Also the switch 35 may be of the push switch type that is simply depressed to cycle the controller through a plurality of conditions Additionally the controller may determine that throat 14 e g via one or more sensors is not clear of articles and thus operate the motor 34 in a reverse direction e g for a short period of time so as to clear any remaining articles or parts thereof from the throat 14 of the shredder 10 Generally the construction and operation of the switch 35 and controller 42 for controlling the motor are well known and any cons

In-rush current jam proof sensor control

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