Mixing device with variable speed drive and related control features
Contents
1. 366 203 5 348 393 A 9 1994 Pappas Jr 2004 0208082 10 2004 Huang et al 366 206 5 472 276 12 1995 Ratermann et al 2005 0122836 Al 6 2005 Boyle et al 5 547 278 A 8 1996 Xie 2005 0141340 Al 6 2005 Donthnier et al 366 207 5 570 955 11 1996 Swartwout et al 5 653 535 A 8 1997 Xie etal 366 100 FOREIGN PATENT DOCUMENTS 5 690 427 11 1997 Jennings 366 100 5 736 828 A 4 1998 Turner et al DE 3613231 A 10 1987 5 844 343 A 12 1998 Horst DE 3912361 AI 10 1990 5 872435 A 2 1999 Bolte et al EP 0293915 12 1988 5 906 432 A 5 1999 Wade et al EP 710442 A2 5 1996 5 934 802 A 8 1999 Xie 366 100 FEP 1130761 9 2001 5 955 861 A 9 1999 Jeong et al EP 1433382 6 2004 5 957 021 A 9 1999 Meredith et al FR 2805177 8 2001 6 066 074 5 2000 Marcinkiewicz GB 2134674 A 8 1984 6 313 597 B1 11 2001 Elliott et al JP 11114394 4 1999 6 429 612 B1 8 2002 Kume et al 318 139 6 704 212 B2 3 2004 Furukawa et al 363 41 D490 271 S 5 2004 Short et al Instruction manual entitled H600 amp L800 Mixers by Hobart 6 750 629 B2 6 2004 Shigemizu et al 318 801 Corporation Dec 1999 6 756 757 B2 6 2004 Marcinkiewicz et al The Characteristics Design and Applications of Switched Reluc 6 883 959 B2 4 2005 Donthnier et al 6 953 278 B2 10 2005 Short et al 6 972 541 B2 12 2005 Matsushiro et al2. 7 005 825 B2 2 2006 Eguchi 366 203 tance Motors and Drives Dr J M Stephenson and Dr R J Blake 318 801 318 727 cited by examiner US 7 273 315 B2 dn fies Sheet 2 of 9 28 30 Sep 25 2007 U S Patent 2 y Ad 7 1 SO SS Zl SE SS INY SAK NS Zu dh CZE 5 16 J ES Fig 2 s U S Patent Sep 25 2007 Sheet 3 of 9 US 7 273 315 B2 u Q lt CTS QA Y Dn A S x d Z f US 7 273 315 B2 Sheet 4 of 9 Sep 25 2007 U S Patent 901 OL 0350 SI Quvn9 033301 SI 8 0150 Anh 8NH dN SI 8 19 co 1081403 0301 3811 1103813 m09 08 00 1311 103 ONY 1 dOLS NNY YIXIW 00 32V 3831NI bas 84251 9015 3 9015 19510 U S Patent Sep 25 2007 Sheet 5 of 9 US 7 273 315 B2 U S Patent Sep 25 2007 Sheet 6 of 9 US 7 273 315 B2 U S Patent Sep 25 2007 Sheet 7 of 9 US 7 273 315 B2 US 7 273 315 B2 Sheet 8 of 9 Sep 25 2007 U S Patent 6 4 4 1 L e 4 H Las 1 1 1 be U S Patent Sep 25 2007 INTERFACE EAE STOP Sheet 9 of 9 US 7 273 315 B2 US 7 273 315 B2 1 MIXING DEVICE WITH VARIABLE SPEED DRIVE AND RELATED CONTROL FEATURES CROSS
3. and the motor torque is at least 135 in Ib and at speed 3 the planetary speed is between 35 and 50 RPM the motor speed is between 875 and 1250 RPM and the motor torque is at least 170 in lb A slower stir speed may also be provided In another implementation of a mixer incorporating the control system of FIGS 9 12 where the mixer is a 140 quart mixer at the highest speed speed 3 the motor speed may be less than 2500 RPM and produce a torque of at least 320 in Ib and the planetary speed may be at least 80 RPM In one example at speed 1 the planetary speed may be between 21 and 31 RPM the motor speed may be between 525 and 775 RPM and the motor torque is at least 690 in 1b at speed 2 the planetary speed may be between 40 and 52 RPM the motor speed may be between 1000 and 1300 RPM and the motor torque is at least 450 in Ib and at speed 3 the planetary speed is between 80 and 95 RPM the motor speed is between 2000 and 2375 RPM and the motor torque is at least 300 in lb A slower stir speed may also be provided Other implementations using the control system of FIGS 9 12 are possible Itis to be clearly understood that the above description is intended by way of illustration and example only and is not intended to be taken by way of limitation Other changes and modifications could be made including both narrowing and broadening variations and modifications of the appended claims What is claimed is 1 A mixing machine c
4. 65 2 tool A mixer body supports the head and includes a bowl receiving portion the bowl receiving portion mounted for movement between a lowered position away from the head and a raised position toward the head A power bowl lift mechanism is provided for moving the bowl receiving portion between the lowered position and the raised posi tion At least one sensor detects when the bowl receiving portion is in the raised position A drive assembly is pro vided for effecting rotation of the rotatable output member A first user input mechanism is provided for initiating mixing and a second user input mechanism is provided for activating the power bowl lift mechanism A control system receives input from each of the first user input mechanism the second user input mechanism and the sensor and con trols both the power bowl lift mechanism and the drive assembly The control system includes a plurality of speed settings for the drive assembly In response to the first input mechanism being actuated to initiate a mixing operation at a first speed setting when the bowl receiving portion is below the raised position the control system operates to activate the drive assembly at a slow speed which is less than the first speed setting In yet another aspect a mixing machine includes a rotatable output member positioned over a bowl receiving area and a drive assembly connected for effecting rotation of the rotatable output member At least one user
5. but phase shifted by 120 from each other thus synthesizing balanced 3 phase waveforms at the motor terminals 212 The fundamental frequency of the effective voltage is varied by the control section 210 by causing the frequency of output signals V_ Ven and Voy to vary in the same way Because winding inductance filters out the high frequency components of the PWM voltage signals current in the motor windings will have a frequency that is essentially the same as the funda mental frequency of the voltage as shown in FIG 12 but will be phase shifted by approximately 90 due to the inductance of the motor windings The characteristics of the AC induction motor 214 will generally cause the magnitude of the motor winding current to increase as the load on the AC induction motor 214 increases and the motor 214 begins to slip thereby providing increased torque when needed The speed of motor 214 varies according to the fundamental frequency of the synthesized waveforms and the control 20 25 30 35 40 45 50 55 60 65 12 210 can be configured to provide controlled acceleration and deceleration when mix speed changes are made In one implementation of a mixer incorporating the con trol system of FIGS 9 12 where the mixer is a 20 Qt mixer the mixer includes a stir speed and speeds 1 2 and 3 which speeds may be stored in memory and selected by the interface 80 as previously described At the highest speed speed
6. 3 the motor speed may be less than 3500 RPM and produce a torque of at least 25 in 1b and the planetary speed may be at least 130 RPM The planetary speed defines the speed at which the output shaft of the mixer orbits about the center axis of a bowl during mixing In one example at the stir speed the planetary speed may be between 18 and 28 RPM the motor speed may be between 320 and 500 RPM and the motor torque is at least 40 in Ib at speed 1 the planetary speed may be between 36 and 56 RPM the motor speed may be between 640 and 1000 RPM and the motor torque is at least 80 in lb at speed 2 the planetary speed may be between 70 and 100 RPM the motor speed may be between 1250 and 1775 RPM and the motor torque is at least 40 in Ib and at speed 3 the planetary speed is between 125 and 165 RPM the motor speed is between 2225 and 2950 RPM and the motor torque is at least 28 in lb In another implementation of a mixer incorporating the control system of FIGS 9 12 where the mixer is a 60 quart mixer at the highest speed speed 3 the motor speed may be less than 1500 RPM and produce a torque of at least 165 in Ib and the planetary speed may be at least 60 RPM In one example at speed 1 the planetary speed may be between 20 and 30 RPM the motor speed may be between 500 and 750 RPM and the motor torque is at least 175 in Ib at speed 2 the planetary speed may be between 26 and 36 RPM the motor speed may be between 650 and 900 RPM
7. control 76 could store a table of acceleration times or acceleration rpm values according to the speed changes being made Of course other types acceleration control values could be stored in such a table of memory of the timer control 76 to be communicated by the timer control 76 to the SR drive 74 during speed changes The combined operation of the control unit 72 and SR drive 74 advantageously enables closed loop control of mixer speed changes on the fly without having to adjust a gear box or drive linkage ratio In addition to communicating desired speed and an accel eration control value to the SR drive 74 when a mix operation is started the timer control 76 may also commu nicate a desired current limit to the SR drive 74 where a current limit may also be stored in memory of timer control 76 for each speed Alternatively the current limit may be pre set in memory of the SR drive 74 The SR drive 74 uses the current limit to monitor operation of the motor and can operate to prevent the current delivered to the motor 36 from exceeding the set current limit The control system 70 can be used to implement both count down mix operations and count up mix operations A count down mix operation is one that occurs for a time period that is set by the operator preferably with the time display 86 displaying a continuously decreasing time remaining for the mix operation A count up mix operation is one that continues until the operator causes the
8. input mecha nism is provided and a control system receives inputs from the user input mechanism The control system includes memory storing a plurality of operating settings and has at least one special function mode enabling at least one of the operating settings to be changed The control system is placed in the special function mode by receiving a prede termined sequence of inputs from the at least one user input mechanism In another aspect a mixing machine includes a rotatable output member positioned over a bowl receiving area and a drive assembly connected for effecting rotation of the rotat able output member A user interface includes at least a speed selection mechanism for selecting one of multiple speed levels A control system receives input from the speed selection mechanism and effects operation of the drive assembly the control system including memory storing a first plurality of speed settings corresponding to a first mixer configuration and a second plurality of speed settings cor responding to a second mixer configuration Only one of the first plurality of speed settings or the second plurality of speed settings is active at any given time BRIEF DESCRIPTION OF THE DRAWINGS FIG 1 is a perspective view of a mixing machine with top cover removed FIG 2 is a side elevation of the mixing machine of FIG 1 in partial cross section FIG 3 is a perspective view of an upper portion of the mixing machine of FIG 1
9. is continuously depressed When the bowl receiving portion 20 reaches the raised position the timer control 76 responsively communicates the set speed to the SR drive 74 and the SR drive 74 accelerates 20 25 30 35 40 45 50 55 60 65 8 the motor from the low speed to the set speed Further when the bowl receiving portion 20 reaches the raised position the timer control 76 responsively maintains a run signal to the SR drive 74 on line RUN STOP without requiring the mix start button to be continuously depressed According to the described control characteristic when an operator sets a desired speed and mix time while the bowl is in a lowered position and then simultaneously and continuously presses mix start and bowl raise the bowl raises and the mixing tool is rotated at a slow speed The slow rotation of the mixing tool reduces resistance of the food product within the bowl 22 to the insertion of the mixing tool as the bowl is raised In one embodiment the slow speed may be a slowest speed setting e g STIR of the mixer or in another embodiment may be a speed between the two slowest speed settings When the bowl 22 and bowl receiving portion 20 reach the raised position as indicated be sensor switch S1 the mix operation proceeds automatically at the higher set speed without requiring further action from the operator Thus when the bowl receiving portion 20 is below the raised position the control system 70 o
10. mix operation to stop e g presses the mix stop button 94 or until some situation other than time causes the mix opera tion to stop e g the bowl is moved out of its operating position or the bowl guard is opened During the count up mix operation the time display 86 preferably displays a continuously increasing time of the mix operation In one embodiment the timer control 76 includes memory storing a preset mix time for multiple positions of the speed selection switch 88 In other words when an operator desires to start a mix operation the operator may first utilize speed input mechanism 88 to select the desired speed When the timer control 76 recognizes the selected speed setting e g position of switch it responds by accessing from US 7 273 315 B2 7 memory a corresponding preset time for that speed setting and drives the display 86 to display the preset time If that preset time is the time desired by the operator the operator does not need to set the time However if the preset time is not the time desired by the operator the operator then utilizes the time input mechanism 84 to change the time e g upward or downward In this case the timer control 76 responsively drives the display 86 to reflect the change The timer control 76 may also responsively update memory to change the preset mix time for the selected speed setting to the new time input by the operator In one embodiment the memory update occurs immediately
11. on the fly and provide sufficient torque for commercial mixing applications SUMMARY In one aspect a mixing machine includes a head extend ing over a bowl receiving location the head including a rotatable output member for receiving a mixer tool A drive assembly includes a drive motor and a drive linkage opera tively connected to effect rotation of the rotatable output member A user interface includes at least one input mecha nism and a control system receives input from the user interface and is connected for controlling operation of the drive motor to provide closed loop control of motor speed and acceleration to effect mix speed changes on the fly solely by adjusting motor speed In another aspect a mixing machine includes a head extending over a bow receiving location the head including a rotatable output member for receiving a mixer tool and a gear system therewithin for effecting rotation of the rotatable output member A switched reluctance motor has an output operatively connected to drive the gear system A switched reluctance drive operates the switched reluctance motor A user interface includes at least one input mechanism and a control unit receives input from the user interface and is connected for controlling operation of the switched reluc tance drive In a further aspect a mixing machine includes a head including a rotatable output member for receiving a mixer 20 25 30 35 40 45 50 55 60
12. raised position and the mix start button 92 is depressed to initiate a mixing operation at a set speed the control system 70 can responsively operate to only permit operation of the motor 36 at a low speed less than the set speed If the bowl up down switch 82 is also depressed to move the bowl receiving portion 20 upward the control system can responsively operate to actuate the power bowl lift mechanism 54 appropriately at the same time that the motor 36 operates at the low speed This control characteristic is implemented by the timer control 76 out putting a signal on the BOWL LIFT line or by otherwise affecting the analog control circuit 78 e g by closing a circuit path in the analog control circuit to allow forward power bowl up direction to be delivered to the power bowl lift mechanism 54 outputting a signal on the TIMER READY line or otherwise affecting the analog control circuit e g by closing a circuit path in the analog control circuit to energize a relay that closes contacts to allow power delivery to the motor 36 outputting a run signal to the SR drive 74 on the RUN STOP line and communicating the low speed instead of the set speed to the SR drive 74 via bus 100 Preferably this control characteristic is only effected when the bowl guard is in the closed position Further this control characteristic is preferably only imple mented if the mix start button 92 is continuously depressed and the bowl up down switch 92
13. the need to pivot the bowl to the closed position in order for normal mixing US 7 273 315 B2 11 to be started Where the displays 86 and 90 are of the LED type the closed bowl indicator may be a simple indicator such as bc Where the displays 86 and 90 are more advanced the indicator could likewise be more advanced In another example if the bowl up sensor S1 indicates the bowl is not in the upward position and the operator temporarily depresses the mix button 92 in attempt to mix the control unit 72 can effect display of a bowl up indicator e g such as bu in either of displays 86 and 90 to communicate to the operator the need to raise the bowl to the upward position in order for normal mixing to be started If both problems exist when the operator temporarily depresses the mix button 92 the control unit can display the bowl up indicator in one of the displays 86 and 90 and the close bowl indicator in the other display or in the alternative the control unit 72 can cause a single one of the displays to alternatingly display both indicators The displays 86 and 90 could also be used to display other error codes if desired Referring now to FIGS 9 12 a more detailed description of the embodiment including an AC induction motor and variable frequency drive is provided In particular user interface 80 is associated with a control system 200 includ ing the variable frequency drive with a rectification section 202 for converti
14. when the operator changes the time while in another embodiment the memory update only occurs once the mix start button is depressed Further where an operator changes mix time during a mixing operation e g during a count down mix operation the timer control 76 could responsively update memory to change the preset mix time for the selected speed setting to that input by the operator As another example of the use of preset mix times for each speed setting where the mixer is running at a set speed for a certain time e g during a count down type mix operation if the operator changes the selected speed setting by using speed input mechanism 88 the timer control responsively drives the display 90 to reflect the newly selected speed setting communicates the new speed setting to SR drive 74 to change the motor speed accordingly and also accesses from memory the preset time corresponding to the newly selected speed setting and drives the display 86 to reflect the accessed preset mix time The timer control 76 then treats the accessed preset mix time as the new mix time for the count down mix operation In such an embodiment changing the speed setting during a count down mixing operation automatically changes the duration of the count down mix The control system 70 may also be configured to imple ment additional control characteristics as desired For example when the sensor S1 indicates that the bowl receiv ing portion 20 is below the
15. 4 via communications bus 100 and also outputs a RUN or STOP directive to the SR drive 74 via path 102 The SR drive 74 can also receive an emergency stop E STOP directive on path 104 The SR drive 74 controls three phase power delivery to the SR motor 36 and receives a speed indicating feedback signal from a rotary encoder 106 of the motor 36 as well as a temperature feedback signal from a temperature sensor 108 The SR drive 74 also monitors and can control the level of current delivered to the motor 36 Thus the SR drive 74 provides closed loop speed and acceleration control of the motor 36 and can prevent motor overload and reduce inrush current during motor starting operations In this regard in one embodiment the timer control 76 includes memory storing a pre set motor speed correspond ing to multiple positions of the switch 88 When the timer control 76 directs the SR drive 74 to begin running the motor 36 the timer control 76 communicates the desired speed to the SR drive 74 via path 100 The SR drive 74 then operates to controllably accelerate the motor 36 from zero rpm to the desired speed with the controlled acceleration reducing undesired inrush current Inrush current is a surge of current that can occur when a motor is started particularly where an jak 5 35 40 45 55 65 6 attempt is made to immediately drive the motor at the desired final speed The acceleration is controlled by the SR drive 74 based upo
16. FIG 4 is a control system schematic for the mixing machine of FIG 1 FIG 5 illustrates the user interface of the mixing machine of FIG 1 FIGS 6 and 7 illustrate one embodiment of a pivotal bowl mounting system and FIG 8 shows one embodiment of a bowl guard assembly FIG 9 is a control system schematic of a mixer system with a variable frequency drive US 7 273 315 B2 3 FIGS 10 and 11 depict exemplary PWM voltage signals of varying duty cycles delivered to respective motor termi nals FIG 12 depicts the exemplary effective voltage seen by the motor terminals based upon the PWM voltage signals of FIGS 10 and 11 DETAILED DESCRIPTION Referring to FIGS 1 3 a mixing machine 10 is shown and includes a base 12 a mixer body 13 including a column 14 extending upward from the base 10 and a head 16 extending outward from the column 14 and over a bowl receiving location 18 The bowl receiving location 18 may be defined by a bowl receiving portion 20 of the mixer body 13 where the bowl receiving portion 20 has a spaced apart curved arms 21 defining a curved shape to match the bowl 22 The head includes a downwardly extending rotatable output member 24 that can receive a mixer tool such as dough hook whisk or other tool The head 16 and upper portion of the column 14 typically include a detachable cover not shown for enclosing the components The mixing machine includes a drive assembly 26 for effecting rotation of the
17. REFERENCE TO RELATED APPLICATION This application is a continuation in part of application Ser No 10 329 040 filed Dec 23 2002 the entire specifi cation of which is incorporated herein by reference TECHNICAL FIELD The present application relates generally to commercial mixers utilized for mixing food products such as dough and more particularly to a commercial mixer with a variable speed drive and desirable control features BACKGROUND It is known in existing commercial mixers to provide multiple speed settings for the mixers The various available mixing speeds are primarily driven by a motor through combinations of gears and or belts and or variable adjustable pulleys where mechanical adjustments are made to change mix speeds Many such devices require that the mixer be stopped in order to change speeds USS Pat No 5 934 802 is representative of a mixer that did not utilize mechanical adjustment of any drive linkage or gear system to change speeds but instead simply adjusted the output speed of a DC motor However control of the DC motor was implemented in a relatively simple manner using a potentiometric speed control switch to adjust a PWM signal delivered to the motor No feedback of motor speed was provided In larger commercial mixers use of a DC motor is impractical due to the size of the DC motor needed to provide sufficient torque Accordingly it would be advantageous to provide a mixer that can change speeds
18. United States Patent US007273315B2 12 10 Patent No US 7 273 315 B2 Huang et al 45 Date of Patent Sep 25 2007 54 MIXING DEVICE WITH VARIABLE SPEED 2 616 673 A 11 1952 Van Guilder DRIVE AND RELATED CONTROL 3 422 330 A 1 1969 Swanke FEATURES 3 951 351 A 4 1976 Ernster et al 2411011 75 Inventors Joseph Huang Dayton US REA stal Brian E Bader Springfield OH US DUE Howard Hartley Jr Brookville 4 819 460 A 4 1989 Obradovic OH US 4 822 172 A 4 1989 Stottmann 366 142 4 860 816 8 1989 Bond 164 155 3 73 Assignee Premark Feg LLC Wilmington DE 4 893 942 1 1990 Stottmann 366 279 US 5 000 578 A 3 1991 Artin et al Notice Subject to any disclaimer the term of this patent is extended or adjusted under 35 U S C 154 b by 197 days Continued 21 Appl No 10 842 369 FOREIGN PATENT DOCUMENTS 22 Filed May 10 2004 CH 691103 A5 4 2001 65 Prior Publication Data US 2004 0208082 Al Oct 21 2004 Continued Related U S Application Data OTHER PUBLICATIONS 63 Continuation in part of application No 10 329 040 Service manual entitled Models H 600 and H 600 T and L 800 filed on Dec 23 2002 Mixers by Hobart Corporation Sep 1977 51 Int Cl Continued B01F 7 30 2006 01 B01F 15 00 S 95 Primary Examiner Charles E Cooley 52 U S CI 366 206 366 601 74 Attorney Agent
19. and 28 RPM 2 The mixing machine of claim 1 wherein the drive operates to control acceleration when changing from one mix speed to another 3 The mixing machine of claim 1 wherein the switching section is controlled by a plurality of PWM control signals 4 The mixing machine of claim 1 wherein a maximum speed of an output shaft of the AC induction motor for a highest of the plurality of mix speeds is less than 3500 RPM 5 The mixing machine of claim 1 wherein the 3 phase variable frequency output comprises first second and third PWM voltage signals 5 20 25 30 14 6 The mixing machine of claim 1 wherein the AC induction motor has at least six poles 7 A mixing machine comprising a head extending over a bowl receiving location the head including a rotatable output shaft for receiving a mixer tool the head including a gear system therewithin for effecting rotation of the rotatable output shaft about its axis and orbiting of the shaft axis about another axis an AC induction motor having an output operatively connected to drive the gear system a drive for operating the AC induction motor the drive including a rectification section for converting input AC power to DC power and a switching section for producing a 3 phase variable frequency output that is applied to the AC induction motor wherein the switch ing section is controlled to adjust frequency of the 3 phase variable frequency output to make mix speed c
20. echanism 88 can then be used to retrieve or change information for that particular mode Where the interface is more advanced such as in the case of a keypad the key pad could be used to input the combination By way of example where the mode enables retrieval of fault records upon entering the special function mode the timer control 76 drives display 86 to display a fault count for a pre established initial fault condition code To retrieve information on a next pre established fault code the speed input mechanism 88 can be turned between certain speed positions with the timer control 76 responding by driving display 86 to display other fault condition information To leave the special function mode the speed input mechanism 88 could be turned to a certain position e g the STIR speed position As another example where the mode enables resetting of mix speeds upon entering the special function mode the timer control 76 drives display 86 to display the active mixer model The operator then turns the speed input mechanism 88 to the speed position for which a change is desired The timer control 76 responsively drives display 90 to display the selected speed position and drives the time display 86 to display the rpm speed as retrieved from memory for that speed switch position The operator then rotates the time input mechanism 84 to change the rpm speed The procedure is repeated for any speed position desired to be changed To leave the s
21. es a processor or microcontroller based timer control unit 76 and an analog control circuit 78 A user interface 80 enables a user to input desired operations to the control unit 72 and a plurality of sensors S1 S2 and S3 are also connected with the control unit 72 and indicate the status of various parts of the mixer as will be described in more detail below In an embodiment using an AC induction motor a variable frequency AC drive could be used in place of the SR drive 74 Referring again to FIGS 1 and 5 an exemplary user interface 80 is located on the head 16 and includes a plurality of input mechanisms including a bowl up down switch 82 for activating the power bowl lift mechanism 54 a time input mechanism 84 and associated LED display 86 for inputting a desired mix time a speed input mechanism 88 and associated LED display 90 for inputting a desired mix speed a mix start button 92 and a mix stop button 94 It is recognized that display types other than LED could also be used Referring to FIGS 1 and 4 the bowl up down switch 82 may be a double pole double throw switch that closes a forward power path in the analog control circuit 78 when depressed in one direction e g upward for BOWL UP and closes a reverse power path in the analog control circuit 78 when depressed in the other direction e g downward for BOWL DOWN with both power paths of the analog control circuit 78 delivering power to the power lift mecha nism 54 for in
22. ging or setting stored current limits for the various mix speeds or changing the active model configuration of the mixing machine In one embodiment access to each of the special functions requires no more than use of the time input mechanism 84 and or speed input mechanism 88 of the user interface 80 In particular the timer control 76 can be configured to look for certain combinations of inputs from one or both mechanisms in order to activate or enter one or more special function modes Essentially one or both of the speed input mecha nism 88 and the time input mechanism 84 can be used to enter a preset combination or access code e g predeter mined sequence of inputs into the timer control 76 which responds by entering the special function mode Where multiple special function modes are used multiple combi nations or access codes can be provided one for each mode By way of example an exemplary combination for a special function mode may start with a certain speed switch position e g position 6 the position aligned with display 90 followed by a certain entered time e g 1 24 followed by a different speed switch position e g position 4 followed by another set time e g 1 52 followed by the initial speed switch position e g position 6 The timer control 76 then drives the displays 86 and 90 to display information perti nent to the particular special function mode and the time input mechanism 84 and speed input m
23. h 1 speed settings that have been selected as optimum or desirable for operations using the power take off e g slicing grating and grinding and ii speed settings that have been selected as optimum or desirable for normal in bowl mixing operations In connection with mixer embodiments configured in this manner the user interface 80 of FIG 5 can be configured to effectively communicate these settings to the operator For example the specific embodiment shown in FIG 5 could be altered by replacing the 3 and 4 speed setting designations of the speed switch with designations that read GRIND for meat grind ing and SLICE for vegetable slicing In such an embodi ment speed switch settings STIR 1 and 2 would be used by the operator for in bowl mixing operations the speed switch setting GRIND would be used by the opera tor when a grinding unit is attached to the power take off 200 and the speed switch setting SLICE would be used by the operator when a slicing unit is attached to the power take off 200 In another embodiment the control unit 72 may operate with the user interface 80 to display error codes to the operator For example if the bowl switch S2 indicates the bowl is not closed and the operator temporarily depresses the mix button 92 in attempt to mix the control unit 72 can effect display of a close bowl indicator in either of displays 86 and 90 to communicate to the operator
24. hanges on the fly solely by adjusting speed of the AC induction motor a user interface including at least one speed input mecha nism having a limited number of speed positions the drive is part of a control system including memory storing a plurality of distinct mix speeds corresponding to the speed positions of the speed input mechanism wherein at one mix speed of the plurality of distinct mix speeds the motor speed is between about 875 and 1250 RPM and the planetary speed is between about 35 and 50 RPM and at a slower mix speed of the plurality of distinct mix speeds the motor speed is between about 500 and 750 RPM and the planetary speed is between about 20 and 30 RPM
25. itiating either up or down movement as may be desired The time input mechanism 84 may be a rotating knob connected to a bi directional rotary encoder that out puts pulses directly to the timer control 76 via the signal path labeled TIME The timer control 76 responsively drives the LED display 86 to reflect the selected changing mix time e g in minutes and seconds The speed input mechanism 88 may be a rotating knob connected to a six position switch such as a Carling switch providing inputs to the timer control 76 via the signal path labeled SPEED The timer control 76 responsively drives the LED display 90 to reflect the selected speed e g Stir 1 2 3 4 Of course in the case of each input mechanism it is contemplated that other types of devices could be used It is also contemplated that more or less input mechanisms could be provided The mix start button 92 may be a normally open push button switch connected in the analog control circuit 78 and the mix stop button 94 may be a normally closed pushbutton switch connected in the analog control circuit 78 51 While numerous types of sensors could be used in a simple form the sensors S1 S2 and S3 may be limit switches incorpo rated in the analog control circuit 78 that open or close one or more signal or power paths based upon monitored mixer parts For example relative to FIG 4 sensor switch S1 may be located to close only when the bowl receiving portion 20 moves to its raised
26. king bracket 93 that couples with a retractable pin 95 that is spring biased in an upward position When the bowl 22 is in the closed operating position a portion of the bowl 22 actuates a switch plate assembly toward the front portion of the column 14 to close the sensor switch S2 behind the switch plate Further details of such pivoting bowl arrange ments are provided in U S patent application Publication No U S 2002 0 093 877 A1 published Jul 18 2002 Other sensor configurations could be used inclusive of mixers where the bowl 20 is not pivotally mounted to the bowl receiving portion in which case the switch could simply detect whether or not the bowl 20 has been loaded onto the bowl receiving portion 20 With respect to the bowl guard closed sensor switch S3 reference is made to FIG 8 showing an exemplary suitable bowl guard as described in U S Pat No 5 306 083 A front portion 97 of the bowl guard rotates between an open position for access to the bowl and a closed position for mixing operations A reed type switch 99 in combination with a magnet 101 that moves with portion 97 of the bowl guard detects when the bowl guard is in the closed position Other sensor configurations could be used including a limit switch actuated by physical contact with a portion of the bowl guard Referring again to FIG 4 the control unit 72 controls operation of the SR drive 74 In particular the timer control 76 communicates with the SR drive 7
27. ld identify when the bowl receiving portion is in the lower of the total movement length between the lowered and raised positions The control system 70 could then be configured so that 1 when the bowl receiving portion is in the lower region as indicated by the additional sensor switch the bowl receiving portion is able to move either upward or downward regard less of whether the bowl is in the closed position and 2 when the bowl receiving portion is higher than the lower region the bowl receiving portion is able to move upward only if the bowl is in the closed position and the bowl receiving portion is able to move downward regardless of whether the bow receiving portion is in the closed position In both of the latter embodiments when the bowl is not in the closed position the control system 70 would disable prevent operation of the drive assembly motor 36 The described mixing machine may also be provided with one or more special function modes that may be accessible to only certain personnel such as service personnel As used herein the terminology special function mode refers to any non mixing mode for the mixing machine Examples of US 7 273 315 B2 9 special function modes include retrieving data log informa tion e g mix hours total operating hours or fault records maintained in memory of the timer control 76 changing or setting stored mix speeds corresponding to the positions of the mix speed switch 88 chan
28. n feedback from the encoder 106 Simi larly if the motor is operating at one speed and the speed setting is changed via the user interface 80 the timer control 76 communicates the new speed setting to the SR drive 74 and the SR 74 drive then operates to controllably accelerate or decelerate the motor 36 to the new speed setting In one embodiment the acceleration may be controlled according to a pre established acceleration time set in memory of the SR drive 74 In another embodiment the timer control 76 may communicate an acceleration time to the SR drive 74 via path 100 As used herein the term acceleration time refers to the amount of time taken to accelerate from one speed to another In other words at the start of a mixing operation to occur at a drive motor speed setting of 2500 rpm if an acceleration time of five seconds is communicated to the SR drive 74 the SR drive responds by accelerating the drive motor 36 from zero rpm to 2500 rpm in the specified 5 seconds In another embodiment the timer control 76 may communicate an acceleration rpm value to the SR drive 74 with the SR drive then operating to accelerate the motor by the acceleration rpm value over a preset time As an example where an acceleration rpm value of 100 is deliv ered to the SR drive 74 the SR drive 74 operates to change the speed of the drive motor by 100 rpm every second where one second is an exemplary preset time in the SR drive Memory of the timer
29. ng AC input 204 to DC which is filtered by filter section 206 to remove ripple The AC input 204 is illustrated as 3 phase but could also be single phase The filtered DC voltage is input to a switching section 208 illustrated as including 3 transistor half bridge circuits A control section 210 is connected to control the transistors using PWM signals to produce a 3 phase variable frequency output that is applied to the coil terminals 212 of motor 214 The term 3 phase variable frequency output means that the frequency of the output can be varied if desired to adjust speed however during operation of the motor 214 at a set speed the frequency of the output remains substantially constant Each output takes the form of a PWM voltage signal of varying duty cycle as shown by V in FIG 10 Ven in FIG and Voy waveform not shown for the outputs to the A B and C terminals 212 of AC induction motor 214 V and V5 depict output signals at a set frequency which would correspond to a certain motor speed The three waveforms V V gy and V cy are identical in frequency and shape but are phase shifted from each other by one third of a cycle 120 The effective voltage seen by the A B motor terminals is shown in FIG 12 as V V gy having a fundamental frequency as represented by the sinusoidal dashed line waveform in FIG 12 The effective voltage seen by the B C motor terminals and the C A motor terminals is similar to FIG 12
30. nly permits operation of the motor 36 at a slow speed but when the bowl receiving portion 20 is in the raised position the control system 70 permits operation of the motor 36 at any of the available speed settings Relative to the bowl guard the preferred control charac teristics based upon bowl guard position are to disable prevent operation of the drive assembly motor 36 whenever the bowl guard is not in the closed position e g by opening a power delivery path to the motor 36 but to permit the bowl receiving portion 20 to be raised or lowered even when the bowl guard is not in the closed position In one embodiment when the bowl locked sensor S2 indicates the bowl is not in the closed position the control system 70 prevents the bowl receiving portion and bowl from being raised e g by opening a circuit path in the analog control circuit to prevent delivery of forward power bowl up direction to the power bowl lift mechanism 54 and also disables prevents operation of the drive assembly motor 36 but permits the bowl receiving portion and bowl to be lowered However in another embodiment the control system 70 could be configured to permit the bowl receiving portion and bowl to be both raised and lowered even if the bowl is not in the closed position In still another embodi ment an additional sensor switch could be provided to detect when the bowl receiving portion is located toward the lowest position e g the sensor switch wou
31. omprising a head extending over a bowl receiving location the head including a rotatable output shaft for receiving a mixer tool the head including a gear system therewithin for effecting rotation of the rotatable output shaft about its axis and orbiting of the shaft axis about another axis US 7 273 315 B2 13 an AC induction motor having an output operatively connected to drive the gear system a drive for operating the AC induction motor the drive including a rectification section for converting input AC power to DC power and a switching section for producing a 3 phase variable frequency output that is applied to the AC induction motor wherein the switch ing section is controlled to adjust frequency of the 3 phase variable frequency output to make mix speed changes on the fly solely by adjusting speed of the AC induction motor a user interface including at least one speed input mecha nism having a limited number of speed positions the drive is part of a control system including memory storing a plurality of distinct mix speeds corresponding to the speed positions of the speed input mechanism wherein at one mix speed of the plurality of distinct mix speeds the motor speed is between about 2225 and 2950 RPM and the planetary speed is between about 125 and 165 RPM and at a slower mix speed of the plurality of distinct mix speeds the motor speed is between about 320 and 500 RPM and the planetary speed is between about 18
32. or Firm Thompson Hine LLP 58 Field of Classification Search 366 96 98 57 ABSTRACT 366 199 207 288 601 99 348 See application file for complete search history 56 References Cited A mixing machine includes a drive assembly and control system for making speed changes on the fly and for provid U S PATENT DOCUMENTS ing controlled acceleration and deceleration A bowl receiv 1 767 002 A 6 1930 Meeker et al ing portion may be movable between a lowered position and 1781321 11 1930 474 31 raised position with a power bowl lift mechanism provided 2 019911 A 11 1935 Meeker A 366 288 to effect such movement Advanced control features and 2 181 079 A 11 1939 Dehuf 366 207 Special function modes may also be provided 2 185 155 A 12 1939 Meeker et al 2 251 903 A 8 1941 Anstice et al 7 Claims 9 Drawing Sheets US 7 273 315 B2 Page 2 U S PATENT DOCUMENTS 7 014 354 B2 3 2006 Donthnier et al 366 203 2002 0093877 Al 7 2002 Brunswick et al 5 087 864 2 1992 Abel 318 34 2003 0165068 Al 9 2003 Tomonaga 363 37 5 140 248 8 1992 Rowan et al 318 811 2004 0008005 Al 1 2004 Sakai et al 318 801 5 204 606 A 4 1993 Kuwahara et al 318 800 2004 0120213 Al 6 2004 Short et al 366 197 5 306 083 A 4 1994 Caldwell et al 2004 0120215 A1 6 2004 Huang et al
33. pecial function mode the speed input mechanism 88 is turned to the stir position and whichever model setting is displayed at that time is made active meaning the speed settings for that mixer model configuration are made active for subsequent mixing operations In another embodiment a hidden switch might be pro vided behind an overlay of the user interface 80 for initiating special function modes Depression of the switch may activate special function modes in a read only format unless a jumper is in place at a particular location in control unit 72 in which case the special function modes could be enabled in a read write format In one embodiment the timer control 76 stores two different types of speed settings Referring to FIGS 1 and 2 the mixer head 16 includes a power take off 200 at the front thereof with an internal drive component 202 that is also driven by the gear system within the head Such power take offs 200 have been commonly used for years in connection with auxiliary food processing mechanisms such as veg etable slicers cheese graters and meat grinders that are driven by component 202 In the noted embodiment of timer control 76 one or more speed settings are stored for use in connection with mixing operations using the rotatable out put component 24 and one or more speed settings are stored for use in connection with devices when attached to power take off 200 This configuration enables an operator to implement bot
34. pecial function mode the speed input mechanism 88 is set to the stir speed position at which time the newly entered speeds are recorded in memory of the timer control 76 In this regard the rpm speed corresponding to the stir speed position of mechanism 88 is preferably pre set and cannot be changed A similar technique would be used set current limits for each speed if a current limit special function mode were activated Another advantageous special function mode enables a mixer model setting to be selected In this regard memory of the timer control 76 may store multiple groups of speed 0 an 5 20 25 40 45 50 10 settings for multiple mixer model configurations In the simplest example first and second mixer configurations are provided and the memory stores a first group or plurality of speed settings corresponding to the first mixer model con figuration and also stores a second group or plurality of speed settings corresponding to the second mixer model configuration Only one group of speed settings is active and therefore available for use at any one time When the special function mode for mixer model setting is entered the timer control 76 drives the time display 86 to display the identity of the active model To change model settings the speed input mechanism 88 is repeatedly turned between two positions to advance to a next model setting which is in turn displayed in the time display 86 To leave the s
35. position e g BOWL IS UP sensor switch S2 could be located to close only when a mixer bowl is placed in an operating position relative to the bowl receiving portion 20 e g BOWL IS LOCKED and sensor switch 53 may be located to close only when a bowl guard positioned between the bowl 22 and the head 16 is in its closed position e g GUARD IS CLOSED In this regard the user interface 80 could be provided with one LED or other controllable visual indicator for indicating when the US 7 273 315 B2 5 bowl is in the raised position another LED or other con trollable visual indicator for indicating when the bowl is in the operating position and or another LED or other control lable visual indicator for indicating when the bowl guard is closed With respect to the bowl up sensor switch S1 a limit switch can be located toward the front portion of column 14 to be contacted by an upper portion of the control support 50 when the bowl receiving portion 20 is moved to the raised position With respect to the bowl locked sensor switch S2 in one embodiment the bowl 22 may be pivotally mounted at one side to the bowl receiving portion 20 to move between a non operating position FIG 6 and an operating position FIG 7 The pivotal mount may be achieved by a combi nation of pins on the bowl receiving portion 20 and bracket openings on the bowl 22 that engage each other to form a hinge The bowl 22 is held in the operating position by a loc
36. rotatable output member 24 In the illustrated machine the drive assembly is formed in part by a gear system 28 within the head 16 and having an upwardly extending input drive shaft 30 In the case of a planetary mixer the gear system 28 may take the form of a planetary gear system in which case the rotatable output member 24 rotates about its own axis 32 with the axis 32 orbiting around a central bowl axis 34 during mixing operations Also forming part of the drive assembly is a drive motor 36 that is mounted and located in line with the column 14 and includes an upwardly extending output shaft 38 A drive linkage 40 connects the motor output shaft 38 to the gear system input shaft 30 and may be formed by the illustrated belt 42 and pulleys 44 and 46 Alternative drive linkages could take the form of chain and sprocket combinations additional gearing and or or bar type linkages The illus trated drive linkage 40 is a fixed linkage meaning that the drive ratio between the motor output shaft 38 and the gear system input shaft 30 does not change The bowl receiving portion 20 may be mounted for movement between a raised position toward the head 16 and a lowered position away from the head 16 the raised position being used during mixing operations and the low ered position being used for bowl installation and removal as well as for installation and removal of mixing tools on the rotatable output member 24 In this regard the curved arms 21 of
37. the bowl receiving portion 20 connect with a central support 50 and the support 50 rides upward and downward on a pair of spaced apart guide rails 52 on the front side of the column 14 A power lift mechanism 54 such as a linear actuator may be provided for effecting upward and down ward movement of the bowl receiving portion 20 In one embodiment a suitable linear actuator is the Warner Electric DC24 10A5 series DC motor 8 stroke length gear train and ACME screw actuator Alternatively other types of power lift mechanisms could be used or a manual mechanism controlled by a crank handle could be used Where a linear actuator is used as shown a top portion 56 may be secured to mounts 58 unitary with an internal casting of the head and a lower moving rod portion 60 may be connected to mounts 62 on the support 50 as shown in FIG 3 In one embodiment a switched reluctance motor is pro vided as the drive motor 36 A switched reluctance motor is desirable because it can provide high torque at low operating 20 25 30 35 40 45 50 55 60 65 4 speeds such as those often used in mixing applications for planetary mixers In another embodiment an AC induction motor might be used Referring to FIG 4 an exemplary control arrangement for a switched reluctance motor embodiment is shown and includes a control system 70 formed by a control unit 72 and a switched reluctance SR drive 74 The control unit 72 includ
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