Patent Grant
9532682
This application is a continuation-in-part of, and claims the benefit under 35 U.S.C. 120 of, application Ser. No. 13/007,257 filed Jan. 14, 2011, which is hereby incorporated by reference.
Field of the Invention
This invention generally relates to food grinders, and more particularly, to electric food grinders, such as electric coffee grinders.
Discussion of the Prior Art
Electrically powered food grinders, such a coffee grinders are well known for both commercial and home use. Such grinders are often provided in the coffee sections of grocery stores at which are shelved bags of unground coffee beans or which hoppers with coffee beans from which customers may fill empty bags provided near the hoppers. Customers who purchase the unground coffee are encouraged to use the provided coffee grinder to freshly grind their coffee.
Many such commercial coffee grinders found in stores have potential problems due to the inexperience of the customers using the grinders or due to inattentiveness. In ordinary course of operation, a customer first selects a prefilled bag of coffee beans or fills a bag from a supply container. The bag is then opened, if not already open, and the contents are poured into the top opening of a hopper. The now empty bag is then placed in a bag fill position beneath an outlet of the grinder from which the ground coffee is emitted. The customer may then manually adjust a knob or other mechanical device to select the coarseness of the grind. The customer then manually actuates a start switch which energizes a grinding drive motor to commence the grinding operation. The grinding operation may end a preselected amount of time after actuation of the start switch. The amount coarseness, or fineness, selected by the customer may also determine the length of time that the grinding continues.
One problem associated with know grinders is that the adjustment of the grinding burrs relative position for different degrees of coarseness of the grind does not allow fine adjustments or maintenance of batch-to-batch coarseness uniformity for the same grind setting.
Also, sometimes the grinding time is longer than necessary which causes excessive wear and tear on the grinding elements and the grinder drive motor. Another disadvantage of some known coffee grinders of the type used in stores is that they take up too much shelf space which is more profitably used to display products to be sold.
The correct operation of the grinder may not be intuitively known and written directions are often provided, but there is no assurance that customers will necessarily follow the directions and admonitions concerning proper use either due to lack of comprehension or subsequent attention to precisely what they are doing and when. Moreover, known food grinders employ mechanical adjustment that are subject to vibration, rough handling and wear due to excessive or abusive use which disadvantageously causes unintended, erroneous changes to actual grinding gap size for different selected grind settings.
Another problem associated with known food grinders is that the mechanical mechanisms for changing grinding gaps are designed for only a single set of tolerances for a given size and type of grinding burrs. Only the original exact grinding burr size and type will enable proper initial adjustment, thereby precluding field service replacement with grinding burrs of a type, configuration, thickness or size different from those of the original grinding burrs for which the grinder is designed.
A need therefore exists to provide a food grinder that overcomes these and other problems and disadvantages and the like.
It is therefore the object of the present invention to provide a food grinder that overcomes or ameliorates the problems and disadvantages of known food grinders noted above.
This object is achieved in part by providing a food grinder having a frame, a grinding chamber, a hopper for holding food ingredient to be ground with a chute for selectively passing the food ingredient to the grinding chamber, with a coarseness controllable grinding mechanism, having an electrical, rotary, drive motor with a motor frame supporting a fixed stator surrounding a rotor mounted for elongate movement relative to the stator, said rotor fixedly attached to a central, rotary, motor axle with opposite ends that are accessible outside of opposite ends of the motor frame, respectively; a fixed grinding burr contained within the grinding chamber; a rotary grinding burr contained within the grinding chamber and separable from the fixed grinding burr by a grinding gap; means attaching the rotary grinding burr to one of the opposite ends of the motor axle; and a controllable electromechanical device engaged with another one of the opposite ends of the motor axle for selectively, longitudinally moving the motor axle relative to the motor frame to selectively adjust the grinding gap.
Preferably, the grinder includes means for controlling the controllable electromechanical device to move the rotating grinding burr into contact with the fixed grinding burr until the electrical drive motor temporarily stalls to establish a null, or zero distance set point, from which subsequent gap distances are measured. In some embodiments, the controllable electromechanical device is a stepper motor and in other embodiments, the motor is a piezoelectric motor, or piezo motor. In some embodiments the stepper motor has a housing and a pusher rod that moves longitudinally relative to the housing pushes against a thrust bearing engaged with the other end of the movable axle when the stepper motor is energized. The pusher rod is connected to a rotary thrust bearing that is engaged with the other one of the opposite ends of drive motor axle.
In another embodiment, the stepper motor has a rotary axle that is linked to the other one of the opposite ends of the motor drive axle by a pusher linkage including a rotary thrust bearing engaged with the other one of the opposite ends of the motor drive axle in a pushing relationship.
In some embodiments the movable drive motor axle is vertically aligned, having the one of the opposite accessible ends of the motor axle is a lower end with which the controllable electromechanical device is engaged located beneath and opposite to the other upper end to which the rotary grinding burr is attached. In such case, the weight of the rotor and the drive motor axle is supported at least in part by the controllable electromechanical device, and upward movement of the axle by the electromechanical means being resisted by the weight of the drive motor rotor and axle while downward movement of the electromechanical device is followed by downward movement of the longitudinally movable rotor and axle due to the weight of the rotor and axle.
In other embodiments in which the movable drive motor axle is horizontally aligned. In such case in which the force of gravity will not press against the controllable electromechanical adjustment, and means are provided for resiliently spring biasing the other one of the accessible ends of the movable drive motor axle and the movable rotor in a direction toward the one end other end of the axle linked to the controllable electromechanical adjustment device. Preferably, in which the resilient pressing means includes at least one spring washer surrounding the movable axle.
The objective of the invention is also obtained in part by provision of a method of grinding food ingredient with a food grinder having a pair of grinding burrs by performing the steps of selecting a level of grind coarseness from a plurality of different levels; electronically controlling an electromechanical device to selectively move at least one of a pair of mating grinding burrs a preselected distance to establish a preselected gap size between the grinding burrs associated with the selected level of grind coarseness; calibrating the electromechanical device before establishing the preselected gap size and before a grinding operation is performed by first moving the grinding burrs into direct contact with each other to establish a zero gap set point from which subsequent gap settings are determined; increasing the gap by moving the at least one grinding burr by the preselected distance from the zero gap set point to establish the preselected gap size associated with the selected level of grind coarseness; and performing a grinding operation with the grinding burrs by rotating at least one of the grinding burrs while being separated from the other grinding burr by the preselected gap size.
The step of calibrating may be performed before each grinding cycle, periodically after each of a preselected plurality of grinding operations or periodically after each of a plurality of preselected time periods.
Preferably, the step of calibrating includes the steps of rotating one of the pair of grinding burrs with an electric drive motor, moving at least one of the pair of mating grinding burrs into sufficient contact with another one of the pair of mated grinding burrs to cause the drive motor to momentarily stall, storing a position of the at least one mating grinding burr being moved when the drive motor stalls, and setting the stored position as a zero set point from which to measure subsequent the amounts of movement of the at least one grinding burr to establish different preselected gaps. During the calibration step, the output power and speed of the drive motor may be reduced beneath that provided for regular grinding operation. The duration of the contact needed to establish the null calibration point may be so brief that it is not discernable. The relationship between the plurality of different gaps sizes may be either linearly related or non-linearly related to each other or to the associated coarseness settings.
Preferably, the grinding method of claim includes the step of automatically decreasing the gap to a minimum gap size associated with the least level of grind coarseness after completion of a grinding operation to prevent intrusion of food ingredient particles larger than the minimum gap size until the start of a new grinding operation.
Thus, achievement of the object of the invention is also partly acquired by providing a food grinder having a pair of grinding burrs with a coarseness setting apparatus, having means for selecting a level of grind coarseness from a plurality of different levels; an electronic controller controlling an electromechanical device to selectively move at least one of a pair of mating grinding burrs a preselected distance to establish a preselected gap size between the grinding burrs associated with the selected level of grind coarseness; means for calibrating the electromechanical device before establishing the preselected gap size and before a grinding operation is performed by first moving the grinding burrs into direct contact with each other to establish a zero gap set point from which subsequent gap settings are determined, means for increasing the gap by moving the at least one grinding burr by the preselected distance from the zero gap set point to establish the preselected gap size associated with the selected level of grind coarseness; and means for performing a grinding operation with the grinding burrs by rotating at least one of the grinding burrs while being separated from the other grinding burr by the preselected gap size.
Achievement of the object of the invention is also obtained by providing a method of grinding for use in a food grinder having a pair of grinding burrs contained within a grinding chamber and a hopper for holding food ingredient to be ground and selectively passing the food ingredient to the grinding chamber, by performing the steps of manually selecting one of a plurality of different coarseness settings respectively associated with a plurality of different sized spatial gaps between the grinding burrs; and linearly moving a rotary one of the pair of grinding burrs attached to a front end of a rotatable motor axle of an electrical grinder drive motor by linearly moving the axle by pushing on a back end of the rotatable motor axle until the gap between the pair of grinding burrs is corresponds to the one selected coarseness setting. Preferably, the electrical grinder drive motor has a rotor to which the axle is attached and a stator, and the method includes the step of longitudinally moving the rotor relative to the stator in response to movement of the axle relative to the stator.
Also, partly acquiring the object of the invention, a method is provided for use in a food grinder having a frame, a grinding chamber, a hopper for holding food ingredient to be ground with a chute for selectively passing the food ingredient to the grinding chamber, the improvement being a method of grinding, by performing the steps of providing an electric, rotary, drive motor with a hollow, elongate, rotary, motor drive shaft extending through the motor between a front and a back of the motor; attaching an end of the hollow, rotary drive shaft to a rotary grinding burr contained within the grinding chamber to selectively rotate the rotary grinding burr when the electric, rotary, drive motor is energized; attaching a fixed, non-rotary grinding burr contained within the grinding chamber in grinding relationship with the rotary grinding burr to an elongate, positioning control shaft extending though the hollow, elongate, rotary motor drive shaft; selectively sliding the elongate, positioning control shaft within the hollow drive shaft to different relative positions to selectively, longitudinally move the fixed, non-rotary grinding burr to different, longitudinal, grinding positions relative to the rotary grinding burr to selectively change the coarseness of the grind.
Preferably, the step of selectively sliding the control shaft includes the steps of selectively actuating an electromechanical drive mechanism, linking the electromagnetic drive mechanism to the elongate, positioning control shaft to longitudinally move the control shaft when the electromechanical drive mechanism is energized, and selectively controlling the electromechanical drive mechanism to selectively change the grinding position of the fixed grinding burr relative to the rotary grinding burr.
The object is also partly obtained by providing a food ingredient grinder having a pair of grinding burrs contained within a grinding chamber and a hopper for holding food ingredient to be ground and selectively passing the food ingredient to the grinding chamber, with a grinding gap adjustment device having means for manually selecting one of a plurality of different coarseness settings respectively associated with a plurality of different sized spatial gaps between the grinding burrs, and means for longitudinally linearly moving a rotary one of the pair of grinding burrs attached to a front end of a rotatable motor axle of a movable rotor drive motor by linearly moving the axle until the gap between the pair of grinding burrs corresponds to the one selected coarseness setting.
The foregoing advantageous features and objectives of the invention will be described in detail, and others will be made apparent, from the detailed description of the preferred embodiment given below with reference to the several figures of the drawing, in which:
Referring to
Supported on a back portion 46 of the top 34 of the lower housing section 32 is a manually, toolessly, removable hopper housing assembly 48 having an upper section 50 with a hopper 56. The hopper housing assembly 48 may be manually removed from, and operatively reattached to, the remainder of the grinder 10 without the need for any tools. The upper section 50 is formed of four, substantially identical, outwardly extending, convex, curved, interconnected sidewalls. A front sidewall 52 of the interconnected sidewalls is translucent, preferably transparently translucent, at least in part, to enable viewing of food ingredient 54 to be ground, such as coffee beans, contained within the hopper 56 in the upper section 50.
The hopper 56 is protectively housed within and supported by the four interconnected sidewalls of the upper section 50 including the front sidewall 52. The back of a top cover 57 is pivotally mounted to the top of the hopper 56 by means of a pair of hinges 59 at the back 61 of the hopper 56, as seen in
The top cover 57 may be manually opened by pivoting it upwardly, but preferably it is selectively automatically opened by an electromechanical, automatic opener that is selectively controlled to pivot the top cover 57 to the open position, as shown in
A lower section 60 of the hopper housing assembly 48 is defined by four lower sidewalls that are a downward continuation of the four interconnected sidewalls of the upper section 50. All the sidewalls of the lower section 60 are opaque to prevent viewing into the lower section 60. The lower section 60 protectively surrounds other operational elements of the food ingredient grinder 30 that will be explained in detail below with reference to other drawing figures. These other operational grinding elements grind the unground ingredient 54 to make it into ground ingredient and then pass the ground ingredient 55 to a chute 62. The ground ingredient 55, such as ground coffee beans, passes from the operational grinding elements within the lower section 60 through the chute 62 to an outlet 64. The outlet 64 faces downwardly and directly, vertically overlies a bag support surface 66 of the recessed bag support section 44.
The bag support surface 66 is preferably the bottom of a removable catch pan 67 with surrounding sidewalls 69,
During the grinding operation an empty, open bag 68, or other suitable container, is supported within the catch pan 69 with the open top facing upwardly beneath the outlet 64 of the chute 62 for receipt of ground coffee beans or other food ingredient released from the outlet 64.
The forwardly extending control panel section 42 has an interior side wall 70 that provides lateral support for the bag 68 and also provides an alignment indicator to guide the bag in proper position on the bag support surface 66 directly beneath the outlet 64. The interior sidewall 70 extends from a front wall 72 of the control panel section 42 to a front wall 72 of the bag support section 44. The front wall 72 is generally aligned with and forms a continuous surface with the front wall 52 of the upper, removable hopper assembly 48. The back wall 74 provides another guide for correctly locating the bag 68 on the bag support aligned beneath the outlet 64. An outer sidewall 76 of the control panel forms a continuous surface with the sidewall 78 of the back portion 46 of the lower housing assembly.
The top, or control panel, 80 of the control panel section 42 is sloped downwardly and forwardly from the front wall 52 adjacent the top 34 of the lower housing section to the front wall 72 of the of the control panel section 42. This slope facilitates visibility of the control panel 80 and the display and operator controls mounted to the control panel 80. In addition, it prevents resting drinks and the like on the control panel 80 that might cause damage, stains or otherwise or interfere with operation of the controls.
Preferably, a forwardly facing photosensor 81 in the back wall detects when a bag is laterally aligned with the chute outlet 64, and a sideways looking photosensor 83 in the sidewall 70 senses when a bag 68 is forwardly aligned with the chute outlet 64. In order to prevent spillage, both sensors 81 and 83 must sense the presence of the bag 68 in order for a grinding cycle to begin, or if a grinding cycle has already begun, for the grinding operation to continue. In lieu of photosensors, the sensors 81 and 83 may be replaced by capacitive sensors, touch sensors or any other like bag detection devices.
The front wall 72 of the control panel section 42 is preferably a translucent backlit advertising panel containing color advertising graphics, photographs and advertising messages. Preferably, the advertising panel is formed of double-walled, transparent plate with a gap for receipt of different, interchangeable, translucent advertising inserts that carry the advertising material.
The display and operator controls preferably include a liquid crystal display 82 for display of alphanumeric messages and associated graphics that may be used to communicate with the user to provide prompts for operation of the grinder. The display 82 is also usable for communications with an operator, maintenance technicians or installer during parameter programming and operations monitoring. The display 82 may also be an interactive screen, or touch-screen, which may be used for inputting information simply by touching the screen at selected displays of icons to select the control functions associated with grinder operations. Preferably, a voice simulator speaks whatever message is being displayed.
In addition, mounted to the control panel are three backlit switches including a start-grind switch 84, a grind setting selection switch 86 and a screen navigation switch 88. There are preferably six grind settings: Espresso, represented by a espresso machine icon shown on the display 82; Drip Single cup, represented by the number one within a small flat bottom filter; Drip Four Cup, represented by the number four within a small flat bottom filter icon; Drip Twelve Cup, represented by the number twelve within a larger flat bottom filter; Drip Woven Wire Screen, represented by a woven wire filter icon; and French Press, represented by a French Press icon. The actual different relative grinding positions between the grinding elements associated with the six possible settings are preferably pre-set at the point of manufacture, but they may also be adjusted in the field by qualified personnel that have access codes to enable changing the preselected grind settings.
Referring to
At the tops of all the walls are substantially identical, inwardly extending, horizontally aligned shoulders, or support ledges, 98 upon which the bottom edge 100 of the mating walls 102, 104, 106 and 108 of the hopper and housing assembly 48 are releasably supported. The shoulders are preferably outwardly and downwardly sloped to facilitate fitting the bottom edges 100 onto the shoulders 98. Also, located inwardly adjacent each of the support ledges are downwardly and outwardly extending guide surfaces 110 to guide the bottom edges 100 outwardly onto the support ledges 98 as the hopper assembly 48 is lowered down onto the main frame.
Likewise, referring to
Once the hopper and housing assembly 48 has been lowered into place, a pair of lateral restraint members 112 and 114 respectively mounted to the outside surfaces of the side walls 90 and 92 and extend above the support ledges 98 to block bottom edges from moving outwardly off of the support ledges 98. The lateral restraint members 112 and 114 overlap the junction between the bottom edge 100 and the support ledge 98.
Referring to
Referring also to
The walls 102, 104 and 106 extend generally straight down from the juncture of the upper section 120 and the lower conical section 126 and protectively surrounded the conical section 126 in spaced relationship. They also protectively surround other elements located between the conical section 126 and the walls 102, 104, 106 and 108 and beneath the open hopper outlet 64. The bottoms of the walls 102, 104, 106 and 108 are merely resting upon the top edge 100 of the top of the lower housing section, or frame, 32, as seen in
The terms tooless-manually or toolessly is intended to mean that the item in question is manually removable or mountable without the need for, or use of any hand tools, such as wrenches, screw drivers and the like. Dismounting of the hopper assembly 56 is achieved merely by manually grasping and manually lifting the hopper assembly 56 off of the lower housing section, or frame, 32. Mounting of the hopper assembly 48 is likewise achieved simply by manually lowering the hopper assembly down onto the top edge 102 of the lower section 32 between the lateral restraint members 112 and 114 without the use of tools. The magnetic connectors 129 and 131 eliminate the need to mechanically latch or lock the hopper assembly 56 to the lower housing section 32. Advantageously, this tooless attachment and separation of the hopper assembly 56 significantly increases the speed with which one hopper may be replaced with another or removed for access to the lower elements of the food grinder 30 located beneath the hopper outlet 128 and then reconnected.
Once the hopper assembly 48 is removed from the top of the lower section, the other elements of the food ingredient grinder 30 located beneath the hopper assembly 48 may also be toolessly removed for repair, replacement or cleaning.
Referring also to
The fixed grinding burr 134 is preferably attached beneath fixed burr mounting table 138 by a plurality of substantially identical magnetic pins 139 that extend into upward facing mating holes in the top of the burr 134 and through aligned fastener openings in the mounting table. The magnetic pins 139 have handles 141,
The mounting table 138 is supported above the horizontal frame member 96 by a pair of vertical, rectangular legs 140 extending downwardly from opposite sides of the top of the mounting table 138. The bottom ends of the legs 140, in turn, are supported by a pair of outwardly extending, horizontal foot members 142.
The horizontal foot members 142 are toolessly releasably attached to the top of the horizontal frame member 96 by means of a pair of manually actuatable fasteners 144. The bottom ends of the manually actuatable fasteners 144 pass through mating holes in the foot members 142 and into releasably locked engagement with mating female fasteners 143 carried by the horizontal frame member 96. The mating female fasteners are preferably threaded bores for receiving threaded male members located at the bottoms of the manually actuatable fasteners 144. Alternatively, rotatable interlocks within the bores interlock with a mating interlocking member at the bottom ends of the manually actuatable fasteners 144. The fasteners 144 have elongate, relatively narrow bodies with handles 146 that are relatively wider to provide a mechanical advantage facilitate manual rotation of the manually actuatable fasteners 144 without the use of any tools. In order to remove the mounting table 138, all that is needed is to first toolessly remove the hopper assembly 148 and then manually rotate the fasteners 144 to an unfastened position. The mounting table 138 with the fixed grinding burr 134 attached is then simply, manually lifted off the horizontal frame member 96. The magnetic pins 139 may then be pulled out of engagement with the fixed grinding burr 134 and the fixed grinding burr may then be toolessly removed and a new grinding burr toolessly installed. The mounting table 138 may then be toolessly reattached to the horizontal frame member 96.
Referring also to
The rotary mounting plate 149 is centrally supported at the top end of, and is preferably integrally formed with, an elongate rotary drive member 151. Adjacent the rotatable grinding burr 150 and near the top of the drive member 151 is an outwardly radiating releasable male locking member 153.
Referring also to
The rotary drive member 151 is slidably received within the hollow drive shaft 152 until the male locking member 153 is slidably received in a mating locking slot 155 at the top of the drive shaft 152, as shown in
Referring now to
When the stepper motor 168 is energized, the reciprocal drive member 174 is caused to either slidably move upwardly or downwardly within the hollow drive member 152 depending upon the direction in which the stepper motor 168 driven. If the movement is upward, the movable, rotary grinding burr 150 is moved upwardly and closer to the fixed grinding burr 130 for a relatively finer grind. If the movement is downward, the movable, rotary grinding burr 150 is moved downwardly away from the fixed grinding burr 130 for a relatively coarser grind. A stepper motor position sensor 212,
Referring also to
Referring now to
The drive motor load sensor 216 is electronic sensor that responds to the changes in input electrical power to determine when the entire amount of the ingredient has been ground and there is no longer ingredient between the grinding burrs. The electrical input power is determined by the microprocessor controller 202 from inputs from an input current sensor 223 and an input voltage sensor 225,
The microprocessor controller 202, in addition to responding to a decrease in input power to determine when grinding is completed, the microprocessor controller also responds to a tachometer 227. The tachometer senses the rotational speed of the drive motor 154 and the controller 202 increases input power when a momentary decrease in rotational speed occurs beneath a preselected minimum, such as one thousand revolutions per minute. Such a reduction in speed may occur when the grinder motor meets with a larger than usual output load. When such a decrease in speed occurs, the controller 202 increase the input power being provided to the drive motor 154 by a power controller 229 to help the drive motor 154 regain and maintain the preselected rotary speed. The controller 202 may also respond to a decrease in speed or the rotary drive motor to increase the time period of a maximum grind time clock period,
The controller 200 responds to these inputs to control various elements of the grinder assembly 30 in accordance with the logic flow chart of
Referring to
The level of reduced power that corresponds to a an empty grind chamber is empirically determined, and when the input power falls beneath this level, the input power controller 229 is caused to terminate input power to the rotary drive motor automatically. A backup timer associated with the controller 202 may also shut off power to the rotary drive motor 154 after a preselected maximum time period in the event the power is not automatically terminated in response to a decrease in input power to the drive motor.
Referring now to
Referring now to
Once it is detected that the cover is fully closed in step 256, in step 258, the display is cause to show the message “PLEASE PLACE BAG IN THE BAG HOLDER”. After the user places the bag in position and it is detected to be in position in step 260, as indicated by the bag position sensor inputs 214 from the sensors 81 and 83, in step 262 the stepper motor 168 is actuated to adjust the relative grinding burr position according to the grind setting that was selected during step 240. After the adjustment has been made, in step 264 a grind clock is started to time the period of grinding and in step 266 the grinding operation is started by energizing the rotary drive motor 154. The grind clock is internal to the microprocessor 202 and provides an elapsed time indication. During the grinding operation, the display shows the message, “THANK YOU. PLEASE WAIT FOR GRINDING TO FINISH”.
If in step 270, it is determined that he grinding operation is completed, as indicated drive motor load sensor 216, then the grinding operation is ended in step 272. If not, but it is determined in step 274 that the maximum grind time, as measured by the grind time clock 264, has lapsed, then again the program proceeds to step 272 to end the grinding operation. Since finer grinds generally take longer than coarser grinds, a potentially different maximum grind time for each of the different grind settings may be stored in a the parameter and input data memory. After step 272, in step 275, the message “IT IS NOW SAFE TO REMOVE YOUR BAG” is shown to the user who may then remove the bag. Once it is determined that the bag has been removed in step 276, in step 278, the program returns to start 224,
Referring now to
Likewise, the same control system described above with respect to
The coarseness controllable grinding mechanism 299 of
A motor, such as the 1934 or 1935, Model 1692 FET1 and 1692 FET2 motors, made by FIR-Elettromeccanica-S-R-L, or FIR Group/Kinetek has been found to work successfully, but other makes and models with different specifications could also probably be used as the movable rotary motor 300. When energized, the adjustable rotor motor 300 causes the adjustable rotor 302 and the attached axle 304 to rotate at approximately 1780 rpm. Preferably, the power is not less than one horse power. The length of the motor is approximately 9.75-inches; the diameter is approximately 5.31-inches and the rotor has a degree of movement of approximately ⅜-inch.
The slidable movable axle 304 has a pair of opposite ends 308 and 310 that are accessible outside of opposite ends lower and upper ends of the motor frame. An upwardly facing, rotary grinding burr 312 is attached to the upper end 310 and rotates with rotation of the axle. The rotating grinding burr is located opposite of and spaced from the fixed grinding burr 314 by a variable grinding gap. As in the above embodiment, the downwardly facing, fixed grinding burr is preferably fixedly attached against movement within a grinding chamber 316. The grinding chamber 316 is only schematically illustrated, but it should be appreciated that the actual grinding chamber is substantially like that shown as part of the toolessly removable grinding assembly 130 of
In the embodiment of
The stepper motor 324 can be finely controlled by means of digital control inputs. For every two hundred control pulses of one polarity, the stepper motor rotates the threaded axle 326 one complete revolution in one direction, and for every two hundred control pulses of an opposite polarity, the stepper motor rotates the threaded axle 326 one radial degree in the opposite direction. If the threaded axle has twenty-five threads per inch, then the finest adjustment obtainable is 0.025-in×0.04 rev./in=0.001 inch. Using a stepper motor that requires more control pulses per inch or a threaded member with more threads per inch will increase the fineness of the adjustments to gap size that can be obtained
The bearing support member is mounted for sliding movement only within a noncircular control mechanism housing 332. Whenever the threaded axle is rotated in one direction, the bearing support member 328, and thus, the thrust bearing 330 and the movable drive motor axle 304 slide upwardly to move the opposite top end 310 of the rotary drive axle 304 and the attached rotary grinding burr 312 to move closer to the fixed grinding burr 314 to lessen the grinding gap. Likewise, when the threaded stepper motor axle 326 is rotated in a direction opposite to the one direction, the movable axle 304 moves downwardly. When the movable axle moves downwardly the grinding gap is lessened, with the thrust bearing 330 fastened against removal from the bearing support member 328, the downward movement of the bearing support member 328 pulls the end 308 downwardly but the downward force of the weight of the axle 304, the rotary grinding burr 312 and the rotor 302 assists in this downward movement.
Referring to
Thus, in the mating threaded embodiment of
Referring now to
The output arm 350 of the piezoelectric motor 348 is attached to a bearing support member 352 that is not threaded but is slidably mounted within the interior of a control mechanism housing 354. The control mechanism housing 354 is attached to the bottom of the motor housing 306 and protectively houses the piezoelectric motor 348, bearing support member 352 and the thrust bearing 330. When the output of the piezoelectric motor 348 pushes upwardly against the bearing support member, the grinding gap is lessened. When the output of the piezoelectric motor 348 moves downwardly, the downward force of the weight of the rotor 302 and the axle 304 causes the axle to follow the bearing support member 352 to slide downwardly to increase the grinding gap.
Referring now to
This movement to the right is resisted by a set of springs 370, such as spring washers, mounted within a spring housing 372 attached to the right end of the motor 300. The springs 370 press against a shoulder in the end 309 and are supported against lateral movement away from the motor 300 by the spring housing 372. The spring 370 may press against the end 309 by means of a thrust bearing such as thrust bearing 360. Because the driven pulley 366 is smaller than the driven pulley 362, it takes more than one revolution of the relatively smaller pulley to achieve one rotation of the relatively larger pulley. Accordingly, the resolution of control achievable by a given stepper motor is increased relative to a drive between the stepper motor and the threaded adjustment member in a one to one ratio as in embodiments of
Referring to
Referring to
Referring now to
In accordance with a method of the present invention, the microprocessor 202,
The plurality of different grind coarseness settings are not necessarily divided equally into the maximum range of possible grinding gaps such that they have a linear relationship. For each selectable coarseness setting, the parameters and input data memory 204,
Referring to
Referring to
The frequency with which calibration should be performed to insure that the gaps distance achieved for a given setting remains the same over multiple operations is dependent on such matters such as the material from which the grinding burrs are made, the configuration of the grinding burrs and other factors such as the hardness of the ingredient being ground, and must be determined by experiment with a particular grinder unit. Operator and owner of the grinder may also be permitted to manually select a calibration whenever desired.
In any event, if a calibration is due, then the calibration is performed before the next grinding operation in step 266. If not, then the program moves directly to step 262 to adjust the grinding gap to that which has been selected by the user. This calibration is performed by first moving the grinding burrs into direct contact with each other to establish a zero gap set point from which subsequent gap settings are determined. This is preferably performed while the rotating grinding burr is rotating. The zero gap point is determined to have been achieved when the movable rotary drive motor can no longer drive the rotary grinding burr to rotate because of its engagement with the non-rotating grinding burr. This is detected of the detection circuit described above with reference to
When the motor 300 stops, or stalls, despite being energized, a position counter or other register or the like of the parameters and input data memory 204, whose count determines the number of incremental movements of the stepper motor 324 or the piezo motor 348 that are needed for any given grinding gap size, is reset to zero. The grinding burrs 312 and 314 are engaged with each other for only a brief moment less than one second so that the stall of the drive motor is only momentary. In addition, the input power and speed of rotation of the drive motor 300 may be reduced before the grinding burrs are moved into contact with each during calibration. It is from this re-zeroed, or reset, position register from which subsequent measurements are made based, such as by counting from zero the number of control pulses needed to achieve a given amount of movement of counted for a given gap are to be counted or measured. The gap is later increased by moving the adjustable grinding burr by the preselected minimum starting distance from the zero gap set point to establish the preselected gap size associated with the selected level of grind coarseness. In this way, distance measurements are always measured from a zero gap calibration position.
While a particular embodiment has been disclosed in detail, it should be appreciated that many variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4821966 | Ephraim | Apr 1989 | A |
| 5509610 | Gibbons | Apr 1996 | A |
| 5605290 | Brenholdt | Feb 1997 | A |
| 20060261197 | Chan | Nov 2006 | A1 |
| 20120006922 | Wilson | Jan 2012 | A1 |
