Abstract:
A method of controlling coffee density exiting from a coffee densifier is disclosed. The method includes the steps of feeding a ground coffee into a mixing chamber having a discharge door. A mixer motor load on a mixer motor driving mixing members agitating the ground coffee in the mixing chamber is measured. The discharge door is moved when the mixer motor load is outside a predefined mixer motor load operating range.

Description:
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/545,757, filed on Oct. 11, 2011. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to systems for processing coffee. 
     BACKGROUND OF THE INVENTION 
     Industrial coffee grinders have been well known for a number of years. Coffee grinders frequently comprised one or more coffee grinding sections which may be stacked above a mixer. The mixer, which may comprise a screw conveyor, blends and conveys the coffee through a screw conveyor section to a discharge section. 
     Industrial coffee grinder mixer assemblies are frequently intended to be used to agitate and blend coffee to an increased bulk density level so that the ground coffee can be fit into a given amount of volume. This might be useful for products such as pods, capsules, and cans with smaller volume metric dimensions than standard. The present inventor recognized that it would be an advantage to provide a grinder mixer machine and method for producing high density coffee which could be adjusted to meet the specific requirements of downstream packaging. 
     As shown in U.S. Pat. No. 4,786,001, it is known to provide paddles within a coffee mixer, where the paddles extend from a rotatable mixer shaft. The paddles include a paddle arm fixed at one end to the mixing shaft and a paddle member extending perpendicularly from the paddle arm at an end of the paddle arm opposite the mixing shaft so that the paddles are a substantially T-shape. 
     The present inventor recognized that the paddles of the prior art mixers encounter a limit in the coffee density that can be imparted by the use of paddle mixing without creating excessive heat, which can over roast the coffee. The inventor recognized the paddles of the prior art mixers imparted unnecessary drag on the mixing motor during operation. 
     The present inventor recognized that, it would be desirable to provide a coffee densifier that produced a higher density coffee with less energy. The present inventor recognized that it would be desirable to provide a coffee densifier that is capable of producing coffee having a coffee density higher than that achievable by prior art paddle mixers. 
     Further the present inventor has recognized it would be desirable to provide an automatically control system for controlling the resulting coffee density being processed through a coffee densifier so as to maintain a consistent coffee density in the coffee exiting the densifier. 
     SUMMARY OF THE INVENTION 
     A method of controlling coffee density exiting from a coffee densifier is disclosed. The method includes feeding a ground coffee into a mixing chamber having a discharge door, measuring a mixer motor load on a mixer motor driving mixing members agitating the ground coffee in the mixing chamber, and moving the discharge door when the mixer motor load is outside a predefined mixer motor load operating range to increase or decrease the denisty of the coffee exiting the mixing chamber.
         In some embodiments, the step of moving comprises the step of retracting the discharge door a predefined distance to increase the density of the coffee exiting the mixing chamber when the mixer motor load is below the mixer motor load operating range. In some embodiments, the step of moving comprises the step of opening the discharge door a predefined distance to decrease the density of the coffee exiting the mixing chamber when the mixer motor load is above the mixer motor load operating range.   In some embodiments, the step of positioning the discharge door to a full closed position during mixer startup until the mixer motor load reaches the mixer motor load operating range.   In some embodiments, the step of positioning the discharge door in a full open position after a predetermined time period when no coffee grounds are being added to the mixing chamber.       

     Another method of controlling coffee density exiting from a coffee densifier is disclosed. The method includes the steps of feeding a ground coffee into a mixing chamber having a discharge door. A mixer motor load on a mixer motor driving mixing members agitating the ground coffee in the mixing chamber is measured. The discharge door is moved when the mixer motor load is outside a predefined mixer motor load operating range. 
     In some embodiments, the step of moving the discharge door comprises the step of retracting the discharge door a predefined distance to increase the mixer motor load when the mixer motor load is below the mixer motor load operating range. The step of moving the discharge door further comprises the step of opening the discharge door a predefined distance to decrease the mixer motor load when the mixer motor load is above the mixer motor load operating range. 
     In some embodiments, the step of moving is further defined in that the predefined mixer motor load operating range is a mixer motor load setpoint. 
     Another method of controlling coffee density exiting from a coffee densifier is disclosed. The method includes feeding a ground coffee into a mixing chamber having a discharge door, measuring a mixer motor load on a mixer motor driving mixing members agitating the ground coffee in the mixing chamber, and moving the discharge door when the mixer motor load is outside a predefined mixer motor load operating range to increase or decrease the mixer motor load. 
     In some embodiments, the step of moving comprises the step of retracting the discharge door a predefined distance to increase the mixer motor load when the mixer motor load is below the mixer motor load operating range. In some embodiments, the step of moving comprises the step of opening the discharge door a predefined distance to decrease the mixer motor load when the mixer motor load is above the mixer motor load operating range. 
     Another method of controlling coffee density exiting from a coffee densifier is disclosed. The method includes feeding a ground coffee into a mixing chamber having a discharge door, measuring a mixer motor load on a mixer motor driving mixing members agitating the ground coffee in the mixing chamber, and moving the discharge door when the mixer motor load is outside a predefined mixer motor load operating range to increase or decrease the amount of residence time the ground coffee is retained in the mixing chamber. 
     In some embodiments, the step of moving comprises the step of retracting the discharge door a predefined distance to increase the amount of residence time the coffee is retained in the mixing chamber when the mixer motor load is below the mixer motor load operating range. 
     In some embodiments, the step of moving comprises the step of opening the discharge door a predefined distance to decrease the amount of residence time the coffee is retained in the mixing chamber when the mixer motor load is above the mixer motor load operating range. 
     In some embodiments, the step of moving comprises the step of moving the discharge door when the mixer motor load is outside a predefined mixer motor load operating range to increase or decrease the amount of coffee chaff within the ground coffee exiting the mixing chamber. 
     In some embodiments, the step of moving comprises the step of retracting the discharge door a predefined distance to decrease the amount of coffee chaff within the ground coffee exiting the mixing chamber when the mixer motor load is below the mixer motor load operating range. 
     In some embodiments, the step of moving comprises the step of opening the discharge door a predefined distance to increase the amount of coffee chaff within the ground coffee exiting the mixing when the mixer motor load is above the mixer motor load operating range. 
     Each of the foregoing method steps can be implemented as a function of a controller programmed to instruct the discharge door actuator to move the discharge door the carry out the steps. 
     Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a coffee processor of the invention. 
         FIG. 2  is a top view of a mixer of the coffee processor of  FIG. 1 . 
         FIG. 3  is an end view of the coffee processor of  FIG. 1 . 
         FIG. 4  is a cross-section view of a portion of a coffee grinder of the coffee processor of  FIG. 1 . 
         FIG. 5  is a grinder roller drive system of the coffee processor of  FIG. 1 . 
         FIG. 6  is a cross-section end view the coffee grinder of the coffee processor of  FIG. 1 . 
         FIG. 7  is a cross-section end view of an inlet section of the coffee processor of  FIG. 1 . 
         FIG. 8  is an enlarged view of pins of the mixer. 
         FIG. 9  is a section view of the mixer taken along the line  9 - 9  of  FIG. 1 . 
         FIG. 10  is a section view of the mixer taken along line  10 - 10  of  FIG. 2 . 
         FIG. 11  is a section view of the mixer taken along line  11 - 11  of  FIG. 10 . 
         FIG. 12  is a schematic view of the machine controller and connected components. 
         FIG. 13  is an exemplary screen of a display that is connected to the machine controller. 
     
    
    
     DETAILED DESCRIPTION 
     While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
       FIG. 1  shows coffee processor  100  having a coffee grinder  105  mounted above a mixer  200 . The grinder section is for grinding coffee, such as whole bean coffee, into coffee grounds. The mixer polishes the rough edges of the coffee particles that come out of the grinder to increase the coffee density. 
     The grinder has a top grinding section  110 , a middle grinding section  120 , and a bottom grinding section  130 . Each grinding section comprises a pair of grinding rollers  112 ,  114 ,  122 ,  124 ,  132 ,  134 . The grinding rollers are journaled for rotation in a grinding roller support frame  116 . The support frame  116  in each section  110 ,  120 ,  130 , comprises a top entry opening  111   a  capable of allowing coffee product flow  199  to fall into the section and to come in contact with the rollers  112 ,  114 . The support frame  116  also has bottom exit opening  111   b  to allow product flow to exit the section and proceed to through the top entry opening of the next adjacent section below or into the mixer  200 . The support frame also includes side access doors  113  on opposite longitudinal sides of the section. 
     Each pair of grinder rollers comprise a fast roller  112 ,  122 ,  132  and a slow roller  114 ,  124 ,  134 . The fast roller is close to an electric drive motor  118  and is rigidly mounted to the frame  116 . The slow roller  114  is mounted on a movable frame member  117  to allow the slow roller to be adjusted in position relative to the fast roller. There exists a roller gap  119  between the rollers. The adjustment of the position of the slow roller  114  relative to the fast roller  112  changes the width of the roller gap  119  between the rollers. 
     A slow roller deflector  140  and the fast roller deflector  142  are each mounted to the frame  116  to guide the coffee out of the section. The fast roller deflector and the slow roller deflector are arranged in a converging orientation as shown in  FIG. 4 . Adjacent the bottom of the rollers are a scraper blocks  144  movably mounted to the frame  116  via an adjustment screw  148 . A scraper bar  146  is mounted to each scraper block  144 . The scraper bar is positionable in close proximity to the roller to prevent build-up of coffee material on the roller. 
     A second embodiment slow roller deflector  141  is shown in  FIG. 6 . The second embodiment slow roller deflector is arranged substantially in parallel to the product flow direction, labeled as direction A. As is shown in  FIG. 6 , each of the top grinding section  110 , the middle grinding section  120 , and the bottom grinding section  130  are arranged the same, except that the width of a roller gap  119  between the rollers in each section may be different than the gaps in the other sections and the bottom grinding section  130  does not have a slow roller deflector. 
     The fast roller  112  and the slow roller  114  are both driven by the electric drive motor  118  via a belt  150 . The drive motor is mounted to a motor frame  115  that is mounted the grinding roller support frame  116 . 
     A drive motor pulley  152  is connected to an output shaft of the drive motor  118 . The belt  150  extends from the drive motor pulley  152  around a tensioner pulley  156  to a fast roller pulley  154  to a slow roller pulley  158  and back around the drive motor pulley  152 . The fast roller pulley is connected to the fast roller. The slow roller pulley is connected to the slow roller. The belt drives the fast and slow rollers in opposite directions. As shown in  FIG. 4 , the fast roller  112  rotates in direction B and the slow roller  114  rotates in direction C. The slow roller pulley  158  is larger than the fast roller pulley  154  and therefore the slow roller rotates slower than the fast roller pulley. In some embodiments, the rollers are corrugated. The corrugation size, shape, and spiral affect the final particle size of the coffee. In some embodiments, the rollers are smooth. 
     Above the top grinding section  110  is an infeed section  160 . The end of each section has a housing  164  with a top in feed inlet  162 . Coffee, such as roasted whole bean coffee, is loaded through the inlet  162  and is guided to the feed roller  180  by a first guide plate  168 , a second guide plate  172 , a first stop plate  169 , and a metering bar  178 . The metering bar  178  is connected to the second guide plate  172 . The metering bar  178  is adjustably positionable along the second guide plate  172  to vary the metering gap  175  between the end of the metering bar  178  and the feed roller  180 . The metering gap  175  allows only a predefined amount of product to exit the inlet section through an exit opening  176  at the bottom and into of the top grinding section  110 . An exit guide plate  174  ensures that coffee is directed into the correct location in the top grinding section  110 . The infeed section  160  has a side opening covered by a door  170  that is bolted to the housing  164 . 
     The rollers  112 ,  114  of the top grinding section  110  may be considered crusher rollers. The rollers of the middle grinding section  120  may be considered finish rollers. The rollers of the bottom grinding section  130  may be considered fine rollers. In some embodiments, the rollers are water cooled by a water cooling system that circulates water through the rollers during the grinder&#39;s operation. 
     In some embodiments, the processor  100  has a machine controller  404 . The controller  404  controls aspects of machine operation including startup, shutdown, grind adjustment, roller gap, and coffee density control. The operator controls controller  404  using a user input device, such as a touch screen controller display panel  408  through a series of menus and user prompts provided on the user input device by the controller  404 . 
     The controller  404  is signal connected with each motor  118 ,  128 ,  138  to control the operation of each motor. Each motor has a grinder motor power transducer  444 ,  446 ,  448  that reports the real-time power load being used by the motor. The controller  404  is connected with a plurality of sensor that report to the controller  404  the gap distance between each of the pair of rollers. The controller  404  is signal connected to a sensor that reports the operation and rate of feed of the feed roller  180  via a feed motor speed controller  442 . The controller  404  is signal connected and controls a feeder motor  181  that drives the feed roller  180 , thereby controlling the rate at which coffee is infeed to the grinding rollers. 
     The controller  404  is signal connected to a grinder thermocouple and a mixer discharge thermocouple. The grinder thermocouple is located at the bottom grinding section  130  to report by signal to the controller  404  the temperature of the coffee exiting section  130 . The discharge temperature thermocouple is located on a discharge extension  348  to report by signal to the controller  404  the temperature of the coffee exiting the mixer. The controller  404  also controls the operation of the mixer as explained below. 
     Mixer. Product exiting the bottom exit opening  131   b  of the bottom grinding section  130  enters the mixer  200 . The mixer  200  has an elongated housing  260  which is generally U-shaped in transverse cross-section. The upper portions of the side walls  262  are generally vertically orientated and parallel. The lower portion of the sides merge with a bottom  264  in a generally semicircular configuration in transverse cross-section. The housing has a chamber  213  provided with vertical rear and front walls  211 ,  238 . The housing has two sections, a receiving portion  210  and a densifier portion  230 . The housing provides a top opening  212  so that the coffee discharged from the grinder may drop into and be received in the receiving section. The housing has a top cover  266  covering the housing from the top opening  212  to a least the front wall  238 . 
     The mixer  200  has a mixer frame  202  that supported by four frame legs  204 . The legs are configured to support the mixer  200  and the grinder  105  on an external surface such as the ground or a floor. The legs maybe connected at an end opposite the housing  260  by a pair of floor rails  206 . Behind the rear most pair of frames legs  204 , as shown in  FIG. 1 , is a mixer drive motor  220 . The mixer drive motor is mounted to a mixer support frame  208  that connects with the rear pair of frame legs  204  and the floor rails  206 . 
     The mixer comprises a mixer shaft  250  extending along a longitudinal centerline  252  of the mixer. The shaft  250  is supported at opposite ends of the shaft by front and rear bearing support members  240 ,  244 . The bearing support members  240 ,  244  are connected to the mixer frame  202 . The front bearing support member  240  receives a front mixer shaft bearing assembly  242  through which a front portion of the mixing shaft  250  is journaled for rotation. The rear bearing support member  244  receives and supports a rear mixer shaft bearing assembly  246  through which a rear portion of the mixing shaft  250  is journaled for rotation. 
     The front bearing support member  240  is located adjacent a front wall  238  of the densifier  230 . The rear bearing support member  244  is located adjacent a rear wall  211  of the receiving portion  210 . 
     The mixer motor  220  drives the mixing shaft  250  through a belt drive system. The belt drive system comprises a drive pulley  224 , a driven pulley  226 , and the drive belt  228 . The drive pulley  224  is connected to the output shaft  222  of the mixer motor  220 . The driven pulley  226  is connected to the mixing shaft  250 . The drive belt is connected around the driven pulley  226  and the drive pulley  224  to transfer the rotary motion of the motor to the driven pulley and thereby to the mixing shaft  250 . The mixer motor  220  is positioned below the housing  260  and supported on a support platform  209  connected to the mixer support frame  208 . 
     A spiral auger  270  is connected to the mixing shaft by protruding tabs  272 . The tabs are attached to the mixing shaft  250  by fasteners. As shown in  FIG. 9 , the tabs  272  space the auger  270  apart from the mixing shaft  250 . The protruding tabs  272  extend from a portion of the spiral auger  270 . The spiral auger turns in sync with the mixing shaft  250 . The tabs  272  are at least located on opposite sides of the auger  270  about the mixing shaft  250 . Therefore when the mixing shaft  250  is in the position shown in  FIG. 2  the tabs  272  attached at a first tab connection on a surface of the mixing shaft and at an opposite second tab location  273 . The spiral auger  270 , as it rotates, moves coffee from the receiving portion  210  towards the densifier portion  230 . In some embodiments, the auger  270  extends at least 50 percent of the length of the chamber  213 . In some embodiments, the auger  270  extends between 40 and 70 percent of the length of the chamber  213  with the remaining length comprising the densifier portion. 
     Pins  231 ,  232 ,  233 ,  234  are connected to the mixing shaft  250  in the densifier portion  230 . Pins  231 ,  232 ,  233 ,  234  are all identical. As is shown in  FIG. 2 , the pins  232 ,  234  begin along the mixing shaft adjacent the end of the spiral auger  270 . As is shown in  FIGS. 2 and 9 , the pins are arranged in four rows that provide a cross formation extending radially from the mixing shaft  250 . Each radially adjacent pin is positioned ninety degrees from the other radially adjacent pins in each radial direction. Pins  231  are opposite pins  233  and are aligned through a vertical cross-section. Pins  232  are opposite pins  234  and are aligned through a vertical cross-section. Radially adjacent pins, such as pins  231  and  233 , are offset in the longitudinal direction of the shaft  250  as shown in  FIG. 2 . Therefore pins  231 ,  232  are not aligned with pins  234 ,  233 , through a vertical cross-section. The radially adjacent offset nature of the pins allows better contact with coffee during the normalization and densifying process in the densifier. 
     In some embodiments, the each longitudinally adjacent pin along the length of the mixing shaft is paced 0.875 inches from the next longitudinally adjacent pin. In some embodiments, a longitudinally centerline of the each longitudinally adjacent pin along the length of the mixing shaft is paced 1.5 inches from a longitudinally centerline of the next longitudinally adjacent pin. 
     Each pin  231 ,  232 ,  233 ,  234  has a shaft  236  extending from a nut head  235 . Opposite the nut head  235  is a tapered distal end  237 . In some embodiments, the shaft  250  comprises a plurality of thread pins studs  251  extending from the distal surface of the shaft  250 . Each pin has a hollow threaded opening opposite the tapered distal end  237 . The hollow threaded opening mates with the threaded pin stud  251  and the nut head  235  enables the user to tighten the pins down to the surface of the mixing shaft  250 . In some embodiments, the mixing shaft  250  has a plurality hollow threaded holes that receive a threaded stud extending from the nut head  235  of each pin. In either embodiment, the removal ability of the pins through the threaded attachment with the mixing shaft  250  allows pins to be individually replaced if they are worn or damaged. 
     In some embodiments, the pins  231 ,  232 ,  233 ,  234  are hardened through a traditional process of hardening metal, which may include heading the pins to a predefined temperature and then cooling the pins to increase pin strength. During operation the pins are rotated by the shaft  250  to agitate a bed of coffee within densifier portion  230 . This agitation by the pins increases the bulk density of the coffee by polishing the rough edges of the coffee particles that come out of the grinder. The more time the coffee particles spend in the densifier portion  230  the more polished the coffee particles become. As the rough edges are polished the particles can fit closer together relative to the others and therefore the resulting coffee density is increased. 
     Referring to  FIG. 9 , the tapered distal end  237  of the pins  231 ,  232 ,  234  are located in close proximity to the inside surface  261  of the housing  260 . This ensures that all coffee in the densifier portion  230  is agitated during the rotation of the pins and moved and no substantial amount coffee is allowed to sit at the bottom of the housing  260  unmoved. The housing  260  is provided with the cover  266 . The cover has support wings  267  which rest on top of the frame  202  on opposite sides of the housing  260  and support the cover. Between the wings  267 , and an opposite the top surface  266   a  is a semicircular lid bottom  268 . The lid bottom  268  is connected to a top surface  266   a  of the cover by lid side walls  269 . An open space  268   a  exists between the top surface  266   a  and the lid bottom  268 . The lid sidewalls  269  contact with or are in close proximity to the upper side walls  265  of the housing  260 . When the cover is placed over the housing  260  as shown in  FIG. 9 , the lid bottom to  268  and the inside surface  261  of the housing below a lower most edge  268   b  of the lid bottom form a chamber  263  within which the pins operate the densification process on the coffee. More space is provided between the lid bottom  268  and the pins then is provided between the inside surface  261  of the housing  260  and the pins. The cover  266  and the lid bottom  268  insurer that coffee is kept in close proximity to the pins during operation and that coffee is not thrown into dead space above the pins that might otherwise exist without the lid bottom  268 . 
     The mixing shaft of mixer  200  having pins  231 ,  232 ,  233 ,  234  can be operated at twice the rotation speed of certain prior art mixers using paddles. The mixer  200  having pins realizes a 30% to 35% reduction the energy needed to turn the mixer shaft with pins, as compared to prior art mixers using paddles, to achieve the same density in the coffee output from the mixer as the prior art paddle mixers. This reduction in energy is achieved even with an increased rotation speed of the pins as compared to prior art paddle mixers. The mixer  200  having pins is capable of achieving a higher coffee density without negatively impacting the coffee, such as by imparting too much heat to the coffee, than can be achieved with prior art mixers using paddles. This is due, at least in part, to the reduced drag against the coffee created by the pins as compared to the prior art paddles. Further, in some embodiments, the mixing shaft  250  has more pins than paddles found in prior art mixers. 
     Automatic Density Control System. The mixer  200  has an automatic density control system (ADCS)  300 . The ADCS  300  controls a discharge door  310  through a linear actuator, such as pneumatic cylinder  336 . The discharge door  310  is located in a discharge door opening  239  of the front wall  238 . The pneumatic cylinder is connected to a pressurized are supply system. 
     The discharge door arrangement is shown in  FIGS. 1, 2, 10, and 11 . The discharge door  310  occupies a discharge door opening  239  in the front wall when the discharge door is in a full closed position. The discharge door is movable between the full closed position and a full open position and any position between the full closed and full open positions. The discharge door is fixed to a pivot rod  302  by a pair of door brackets  320 . At a top end of the door bracket, a pair of fasteners  322  fix the door bracket to the pivot rod  302 . At a bottom end of the door bracket opposite the top end, a door bracket spacer  324  is positioned between the back surface of the door bracket  320  and a surface of the discharge door  310 . A pair of fasteners (not shown) are fixed through a pair of the mounting holes  326  that extend through the door bracket, through the door bracket spacer, and into the door. The door bracket spacer  324  may be a circular shape such as shown in  FIG. 11  or may be any other shape. The door brackets  320  are spaced apart about a vertical mid-line  311  of the door  310  as shown in  FIG. 11 . 
     The rod  302  is pivotally connected to the front wall  238  by a pair of spaced apart pivot rod supports  304 . The pivot rod supports  304  are attached to the front wall  238  by a pair of fasteners  306 . Each pivot rod support  304  has an opening  304   a  through which the pivot rod extends and pivots therein. A pair of pivot rod collars  308  may be fixed to the pivot rod adjacent inside walls  305  of each pivot rod support  304 . The collars  308  prevent the transverse movement of the pivot rod and thereby maintain the transverse position of the discharge door  310  relative to the discharge door opening  239 . In some embodiments, a bearing assembly is contained within the pivot rod support to facilitate the movement of the pivot rod. 
     The discharge door  310  has a center opening  312 . The center opening  312  comprises an upper semicircular portion and a lower semicircular portion. Each semicircular portion allows gaps  314  between the discharge door  310  and the shaft  250  in the upper and lower areas of the center opening  312  when the door is in the closed position. The gaps  314  allows a bottom end  313  of the discharge door  310  can move away from the front wall  238  in the direction E shown in  FIG. 11  to create an opening between the discharge store  310  and the front wall  238 . In some embodiments, the gaps  314  are sufficient to allow the discharge door  310  to move in the direction E to the point where the bottom of discharge door makes contact with or is adjacent to the bearing support plate  240 . As the door pivots open about the pivot rod  302 , the gap between the discharge door  310  and a bottom edge  238   a  of a front wall  238  is greater than the distance between the discharge door  310  and a top edge  238   b  of a front wall  238 . A mixing shaft collar  254  is located on the densifier side of the discharge door adjacent the pins as shown in  FIG. 11 . The mixing shaft collar  254  prevents coffee from escaping from the densifier portion  230  through the gaps  314  when the door is in the full closed position. 
     The pivot rod  302  extends outside of a frame member of the frame  202  to connect to pivot arm  330  as shown in  FIG. 10 . A top end  331   a  of the pivot arm  330  is fixed to the pivot rod  302 . A bottom end  331   b  receives a pin connecting a connector  332  attached to a piston rod  334  of the pneumatic cylinder  336 . A rear end of the pneumatic cylinder  336  is pivotally attached to a linear actuator support  340  that is fixed to the frame  202  as shown in  FIGS. 1 and 9 . 
     In some embodiments, a knurled adjustment collar  333  is located along the cylinder rod  334 . The location of the adjustment collar  333  can be moved along the rod to manually set a cylinder rod minimum beyond which further retraction into the cylinder is not possible. Turning the collar  333  changes the preload on an internal pilot (not shown) inside the cylinder. The adjustment collar is held in place with two lock screws that must be loosened before turning the collar. 
     When the discharge door  310  is in any open position, as positioned by the pneumatic cylinder, coffee will be allowed to be discharged passed the discharge door  310 , down through a discharge passage  342 , along a discharge path  344 , passing out a discharge opening  346  and out though a discharge extension  348  to an external receptacle (not shown). The discharge extension  348  has a flange  349 . The flange  349  has at least to bolt holes (not shown) for securing the attachment of an external pipe, hose, or other connector. 
     The ADCS  300  comprises a mixer motor power transducer  402 , the controller  404 , and a cylinder controller  406 , the cylinder  336 , and the discharge door  310 . The power transducer  402  measures the power consumed by the mixer motor  220  and sends a load signal in the range of 4 milliamps (mA) to 20 mA to the controller  404  depending on the power consumed by the mixer motor  220 . The pneumatic cylinder is positioned by the properly distributed compressed air provided by the cylinder controller  406 , using the supplied air pressure, and positions the pivot arm  330  and thereby a discharge door  310  in any position within of the stroke pneumatic cylinder. In some embodiments, the cylinder controller is a current-to-pneumatic controller. In some embodiments, the cylinder controller is a current-to-position controller. 
     The controller  404  has, or is in signal communication with, a controller display panel  408 . In some embodiments, the controller display panel  408  is a touch screen having user-interactive portions where the display panel is capable of receiving user input by a user touching one or more touch areas of the display panel. In some embodiments, the controller display has a screen displaying a power value display portion  412 , a mixer motor load setpoint value display portion  414 , a mixer speed setpoint display portion  410 , a status display portion  418 , a door position display portion  416 , manual/auto selector button  426 , an up value button  420 , a down value button  422 , and a reset button  424 . The power value display portion  412  is configured to display the current power being consumed as reported to the controller the power transducer  402 . The mixer motor load setpoint value displayed portion  414  is configured to display a mixer motor load setpoint. The mixer speed setpoint display portion  410  is configured to display the mixer shaft rotation speed setpoint. In some embodiments, when the display panel  408  is a touch screen, buttons  420 ,  422 ,  424 ,  426  are touch areas capable of receiving user input. In some embodiments, each of the display portions  410 ,  412 ,  414 ,  416 ,  418  comprise a digital display and the buttons  420 ,  422 ,  424 ,  426  are physical buttons. In some embodiments, less than all of the display portions shown in  FIG. 13  may be provided on the display panel  408 . In some embodiments, the mixer speed setpoint display portion  410  is provided on a separate display (not shown) connected to the controller. It will be appreciated that the display portions shown in  FIG. 13  can be provided on the same display panel or on one or more separate displays and/or remote displays. 
     In some embodiments, instead of providing one machine controller  404  that controls the operation of the entire grinder and mixer combination, a separate grinder controller and mixer controller are provided. In such an embodiment, the controllers are signal connected to each other so that appropriate data can be passed between each. 
     The door position display portion  416  is configured to display the degree to which the discharge door  310  is open. In one embodiment, the door position display portion  416  comprises a number of indicators  416   a  between a bottom  416   b  and a top  416   c.  The position of the discharge door  310  is shown by the proportion of indicators illuminated between the bottom and the top of the discharge display portion  416 . The more indicators  416   a  that are illuminated correspond to a greater degree of opening of the discharge door  310 . In some embodiments, the degree of discharge door opening is displayed in as a numeric value. In some embodiments, the degree of discharge door opening is represented as a graphical picture showing the degree of door opening. 
     The status display portion  418 , provides a number of mode indicators (not shown) that indicate the status of various components of the automatic density control system. For example, a manual/automatic mode status indicator may be provided in the status display portion  418  to indicate whether the automatic density control system is in a manual mode or in automatic mode. The manual/auto selector button  426  enables a user to select between the manual mode or the automatic mode. 
     The up value button  420  and the down value button  422  are configured to enable a user to adjust any user adjustable values or settings, including the mixer load setpoint when the automatic density control system is in the automatic mode and the discharge door  310  position when the automatic density control system is in the manual mode. The reset button  424  enables a user to reset user definable settings, such as the mixer motor load setpoint value to a predefined default and also to reset the door position value to a predefined default. 
     In operation, the machine controller  404  implements a mixer load control function that is configured to compare a mixer motor load signal received from the power transducer  402  to the mixer motor load setpoint, which may be predefined or may be set by the operator at the controller display panel  408  by using the up value button  420  or the down value button  422 , or via a physical or on-screen keyboard (not shown). The controller  404  receives real-time data on the power being consumed by the mixer motor  220  through the power transducer  402 , which is displayed on the power value display portion  412  of the controller display panel  408  by the controller  404 . 
     The controller  404  has a mixer startup function that functions during initial grinding. The controller  404  positions the discharge door in the full closed position until coffee in the mixer has reached a predefined level defined by the motor load setpoint that was predefined or defined by the operator at the controller display panel  408 . If the motor speed remains constant, larger amounts of coffee in the mixer will result in a higher motor load and smaller amounts of coffee in the mixer will result in a lower motor load. Therefore there is a correlation between the amount of coffee in the mixer and the mixer motor load for a given mixer speed. 
     If the discharge door is in the completely closed position and coffee is being added to the mixer by the grinder the the amount of coffee in the mixer will increase. The increase in the amount of coffee in the mixer will increase the load on the mixer motor  220  because additional energy will be required to rotate spiral auger  270  and the pins  232 ,  234  against the increased amount of coffee in the mixer. Once the load on the mixer motor  220  reaches the motor load set point, the controller  404  will signal the pneumatic cylinder  336 , through the cylinder controller  406 , to extend the cylinder rod  334  and open the discharge door  310  a predefined distance. As coffee is allowed to escape through the discharge, the motor load will increase at a decreasing rate, will stabilize, or will be reduced depending on the rate of inflow of coffee from the grinder and the degree to which the discharge door is open. Preferably, the door will be opened a sufficient distance so that the motor load stabilizes at the predefined set point. 
     During operation the a mixer load control function of the controller  404  continuously, or at regular intervals, monitors the load on the mixer motor  220  through the signal received from the power transducer  402 . When coffee is being constantly fed into the mixer from the grinder, a flow of coffee is passing through the mixer from the receiving portion  210  through the densifier portion  230  and out the discharge extension  348 . The controller  404  will continuously, or at regular interval, signal the cylinder controller  406  to signal the cylinder rod to extend to open the discharge door a predefined amount or to retract the discharge door a predefined amount to maintain a consistent motor load by adjusting the amount of coffee resident in the mixer at a given time. 
     If the mixer motor load signal is above the mixer motor load setpoint, the controller  404  will send a signal to the cylinder controller  406 , which will signal to the pneumatic cylinder to extend the cylinder rod a predetermined distance to open the discharge door in the direction E in  FIG. 11  a predetermined amount. Further opening the discharge door will result coffee in the mixer being discharged at a faster rate, so that less coffee is retained in the mixer and the coffee spends a less amount of time in the mixer. As less coffee is retained in the mixer, the coffee will provide less of a load the mixer motor  220  because less energy is required to rotate a smaller amount of coffee within the mixer. 
     If the mixer motor load signal is below the mixer motor load setpoint, the machine controller  404  will send a signal to the cylinder controller  406  which will signal to the pneumatic cylinder to retract the cylinder rod a predetermined distance to retract the discharge door  310  in the direction opposite direction E in  FIG. 11  a predetermined amount. Retracting the discharge door will result in coffee in the mixer being discharged at a slower rate, so that more coffee is retained in the mixer and the coffee spends a longer amount of time in the mixer. As more coffee is retained in the mixer, the coffee will increase the load the mixer motor  220  because additional energy is required to rotate spiral auger  270  and the pins  232 ,  234  against the increased amount of coffee in the mixer. 
     When coffee is resident within the densifier portion  230 , the coffee is subjected to the impact of the pins  232 ,  234  and a corresponding agitation with other coffee materials within the densifier portion  230 . One way of increasing the density in the coffee discharged from the mixer, is to increase the motor load set point. A higher mixer motor load setpoint will reduce the coffee chaff and increase coffee density. Coffee chaff is created during the grinding operation and the densifier operates to break up the chaff as well as to densify the coffee. An increased motor load set point corresponds to coffee being retained in the densifier portion  230  for a longer period of time. A higher mixer motor load setpoint will also raise the coffee temperature. Therefore, it is preferred to use to lowest motor load set point that will achieve the desired coffee density. 
     A higher mixer shaft rotation speed setpoint will result in higher coffee density. An increase in the mixer shaft rotation speed will increase the speed at which coffee in the densifier achieves a given density. Therefore operating the mixer shaft at an increased speed on the same amount of coffee in the densifier will increase the load on the mixer motor, thereby causing the discharge door to be opened to a larger degree to maintain the load at the motor load set point. Operating the mixer at a faster speed on a given volume of coffee in the densifier will increase the throughput of coffee out of the mixer. Correspondingly, throughput can remain constant if the volume of coffee is reduced proportionally when the mixer shaft speed is increased. 
     Retracting the discharge door while the mixer is operating and being fed with a relatively constant flow of coffee grounds from the grinder will (1) decrease the rate at which coffee exits the mixer, (2) increase the mixer motor load, (3) increase the density of the coffee exiting the mixer, (4) increase the resident time which the coffee grounds are retained in the mixer before exiting, and (5) will decrease the amount of coffee chaff in the exiting coffee. Opening the discharge door while the mixer is operating and being fed with a relatively constant flow of coffee grounds from the grinder will (1) increase the rate at which coffee exits the mixer, (2) decrease the mixer motor load, (3) decrease the density of the coffee exiting the mixer, (4) decrease the resident time which the coffee grounds are retained in the mixer before exiting, and (5) increase the amount of coffee chaff in the exiting coffee. 
     In some embodiments, the mixer motor load setpoint is a mixer motor load operating range. The controller  404  is configured to move the discharge door when the mixer motor load is outside of the mixer motor load operating range. 
     In one embodiment the controller  404  utilizes proportional-integral-derivative logic to calculate the output signal that should be sent to the cylinder controller  406 . In some embodiments the cylinder controller  406  converts a signal in the range of 4 mA to 20 mA from the machine controller  404  to the proper cylinder position. In some embodiments, the controller  404  is programmable by the operator to adjust the maximum full open and full close positions of the discharge door  310  by setting a fully extended cylinder rod position and a fully retracted cylinder rod position. 
     In some embodiments, the controller  404  comprises a cleanout function. The cleanout function opens the discharge door  310  to the full open position after a predefined no-grind time period has elapsed in which the control receives a signal that the grinder motor load from one of the motors  118 ,  128 , or  138  is below a predefined in-operation load setpoint. When such motor load is below the in-operation grinding load setpoint, no coffee is being ground as the grinding of coffee between the rollers generates the in-operation grinding load on the corresponding motor  118 ,  128 , or  138 . After the motor load has dropped below the in-operation grinding load set point for a predefined elapsed no-grind time period, the controller  404  signals to open the discharge door  310  for a predefined cleanout time period to allow the coffee material in the mixer to be discharged. The cleanout function is beneficial because if no additional coffee is being feed into the machine, then the motor load in the mixer will decrease. If the motor load in the mixer decreases, the controller  404  will signal the discharge to close proportionally the discharge door to maintain the mixer motor load at the predefined set point. Eventually the discharge door will close completely and the mixer will continue to agitate and rotate the coffee grounds. Excessive densification by the mixer may result in resulting coffee grounds that do not meet the operator&#39;s output requirements for coffee density. 
     In some embodiments, the controller  404  allows a user to set the cleanout door position that is used during the cleanout function so that the user may control the rate of coffee grounds discharged during the cleanout operation. The controller  404  may display a cleanout progress indicator on the display panel  408 , which shows the progress in completely discharging the contents of the mixer. 
     In some embodiments, the mixer is water cooled. The mixer comprises a stainless steel water cooled jacket within the walls  262  and/or bottom  264  of the housing. The water cooling is achieved by circulating water through the water jacket. Water is circulated by one or more pumps controlled by the machine controller  404 . The temperature of the coffee exiting the mixer is measured by the discharge temperature thermocouple. Circulating water through the water jacket dissipates heat from the mixer and the coffee therein. Water flow is started, stopped, increased or decreased to change the temperature of the mixer and the coffee therein. 
     The controller  404  may be a an application-specific integrated circuit (ASIC) having one or more processors and memory blocks including ROM, RAM, EEPROM, Flash, or the like; a programmed general purpose computer having a microprocessor, microcontroller, or other processor, a memory, and an input/output device; a programmable integrated electronic circuit; a programmable logic controller or device; or the like. Any device or combination of devices on which a finite state machine capable of implementing the procedures described herein can be used as the controller  404 . 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred.