Patent Publication Number: US-6220835-B1

Title: Portion control dispensing pump

Description:
This application is a continuation-in-part of and claims priority from U.S. patent application Ser. No. 09/422,826, filed Oct. 21, 1999, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to dispensing systems, and more particularly to a pump for dispensing condiments and the like. 
     It is often desirable to dispense a condiment or the like by consistent amounts. Both mechanical and electronic devices have been used to control the portion dispensed with varying degrees of success. Some of the devices are rather complex and expensive. Others may be unsuitable for dispensing condiments that contain solids or semi-solids. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a pump for dispensing condiments or the like. The pump provides a simple and reliable mechanism for providing consistent portion control in dispensing, and is especially suitable for dispensing condiments that contain solids or semi-solids or particles such as in thousand island dressing and various “secret sauces” favored by restaurants. 
     The invention provides a reciprocating piston in a chamber. The piston has a transfer check valve which permits condiment flow only in a direction from an inlet side of the chamber to an outlet side of the chamber. The outlet side of the chamber includes an outlet with an outlet check valve. When the piston is moved from the outlet side to the inlet side of the chamber, the transfer check valve is open to permit condiment flow from the inlet side to the outlet side of the chamber, and the outlet check valve is closed to accumulate condiment therein. Upon accumulation of a desired amount of condiment in the outlet side of the chamber, the piston is moved from the inlet side to the outlet side of the chamber. During that time, the transfer check valve is closed and the outlet check valve is open to dispense the accumulated condiment in the outlet side of the chamber. At the same time, condiment is flowed into the inlet side of the chamber. The amount of condiment transferred to the outlet side of the chamber is determined by the piston stroke, and can be controlled to produce a consistent amount for each cycle of accumulating and dispensing condiment. The cycle is repeated to provide dispensing action with simple portion control. The outlet check valve and transfer check valve may be elastomeric check valves as described in U.S. patent application Ser. No. 09/422,826. 
     In accordance with an aspect of the present invention, a condiment dispensing pump comprises a pump chamber including a cavity having an inlet chamber cavity portion and an outlet chamber cavity portion. The pump chamber has an inlet fluidicly coupled with the inlet chamber cavity portion and an outlet fluidicly coupled with the outlet chamber cavity portion. An outlet check valve is disposed at or near the outlet of the pump chamber, and is openable to permit flow only in a direction from the outlet chamber cavity portion out through the outlet check valve. A piston is disposed in the pump chamber cavity between the inlet chamber cavity portion and the outlet chamber cavity portion. The piston is movable in the pump chamber cavity to reapportion the volume of the pump chamber cavity between the inlet chamber cavity portion and the outlet chamber cavity portion. The piston includes a piston check valve which is openable to permit flow only in a direction from the inlet chamber cavity portion through the piston check valve to the outlet chamber cavity portion. 
     In some embodiments, the piston is movable between a first position when the inlet chamber cavity portion has a minimum volume and the outlet chamber cavity portion has a maximum volume, and a second position when the inlet chamber cavity portion has a maximum volume and the outlet chamber cavity portion has a minimum volume. The piston check valve is closed and the outlet check valve is open when the piston moves from the first position to the second position to draw a flow from the inlet into the inlet chamber cavity portion and to produce a flow from the outlet chamber cavity portion out through the outlet. The piston check valve is open and the outlet check valve is closed when the piston moves from the second position to the first position to permit flow from the inlet chamber cavity portion to the outlet chamber cavity portion and to prevent backflow through the outlet into the outlet chamber cavity portion. 
     In specific embodiments, the piston is movable in the pump chamber cavity in a generally linear manner. The piston has a generally constant stroke. An air cylinder is coupled with the piston to move the piston in the pump chamber cavity. 
     In accordance with another aspect of the invention, a portion control dispensing apparatus comprises a chamber including a cavity having an inlet and an outlet. An outlet check valve is disposed at or near the outlet of the chamber, and is openable to permit flow only in a direction from the chamber cavity out through the outlet check valve. A transfer check valve is disposed in the chamber cavity. The transfer check valve is movable in the chamber cavity between a first position near the inlet and away from the outlet and a second position near the outlet and away from the inlet. The transfer check valve is closed when moved from the first position to the second position and is open when moved from the second position to the first position. 
     In accordance with another aspect of the invention, a condiment dispensing pump comprises a pump chamber including a cavity having an upstream chamber cavity portion and a downstream chamber cavity portion. The pump chamber has an inlet fluidicly coupled with the upstream chamber cavity portion and an outlet fluidicly coupled with the downstream chamber cavity portion. An outlet valve is disposed at or near the outlet of the pump chamber. A transfer valve is disposed in the pump chamber cavity. The pump includes a mechanism for increasing the volume of the downstream chamber cavity portion and decreasing the volume of the upstream chamber cavity portion when the transfer valve is open and the outlet transfer valve is closed to transfer fluid accumulated in the upstream chamber cavity portion into the downstream chamber cavity portion, and for decreasing the volume of the downstream chamber cavity portion and increasing the volume of the upstream chamber cavity portion when the transfer valve is closed and the outlet valve is open to transfer the fluid in the downstream chamber cavity portion out through the open outlet valve and to draw fluid through the inlet for accumulation in the upstream chamber cavity portion. 
     In some embodiments, the outlet valve comprises an outlet check valve which is openable to permit flow only in a direction from the downstream chamber cavity portion out through the outlet check valve. The transfer valve comprises an transfer check valve which is openable to permit flow only in a direction from the upstream chamber cavity portion to the downstream chamber cavity portion. In specific embodiments, the outlet check valve and transfer check valve may be elastomeric check valves. 
     Another aspect of the invention is directed to a method of providing portion control pumping, which comprises providing a transfer valve in a chamber between an inlet disposed at an inlet side of the chamber and an outlet disposed at an outlet side of the chamber. An outlet valve is provided at the outlet. The transfer valve is moved from the inlet side of the chamber to the outlet side of the chamber with the transfer valve closed and the outlet valve open to draw fluid through the inlet into the inlet side of the chamber and dispense fluid from the outlet side of the chamber out through the outlet. The transfer valve is moved from the outlet side of the chamber to the inlet side of the chamber with the transfer valve open and the outlet valve closed to transfer fluid from the inlet side of the chamber through the transfer valve to the outlet side of the chamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a check valve in a rest or closed position illustrating an embodiment of the present invention; 
     FIG. 2 is a perspective view of the valve seal in the check valve of FIG. 1; and 
     FIG. 3 is a cross-sectional view of the check valve of FIG. 1 in an open position. 
     FIG. 4 is a cross-sectional view of a pump illustrating an embodiment of the present invention; 
     FIGS. 5A and 5B are schematic views illustrating operation of the pump of FIG. 4; and 
     FIG. 6 is a cross-sectional view of a pump illustrating another embodiment of the present invention. 
    
    
     DESCRIPTION OF THE SPECIFIC EMBODIMENTS 
     Elastomeric Check Valve 
     FIG. 1 shows a check valve  10  having a valve body  12  which includes a first body portion  14  connected to a second body portion  16 . Disposed in the valve body  12  are a valve stem  18  and a valve seal or resilient valve member  20 . The valve seal  20  is disposed in a seat  22  provided in the first body portion  14 . The connection of the second body portion  16  to the first body portion  14  advantageously supports and retains the valve seal  20  and valve stem  18  in position. The body portions  14 ,  16  in the embodiment shown include threads that mate with each other to form an adjustable threaded connection. Of course other types of connections may be used instead. The use of two body portions  14 ,  16  to form the valve body  12  renders the assembly of the valve  10  more convenient, and makes it easier to replace the components such as the seal  20  or the stem  18 . 
     The valve stem  18  includes a stem body  26  connected to a plurality of spokes  28  that are supported between the body portions  14 ,  16 . The stem body  26  is generally axisymmetric with respect to an axis  34 . The stem body  26  is disposed between an upstream chamber  30  and a downstream chamber  32  of the valve  10 . Of course, the stem body  26  may be supported inside the valve body  12  by other mechanisms. 
     The valve seal  20  is disposed between the valve body  12  (body portion  14  in this embodiment) and the stem body  26 . As shown in FIGS. 1 and 2, the valve seal  20  is an annular member which is generally concentric with the valve stem body  26 . The seal  20  includes a proximal portion  40  that is attached to or held by the body portion  14  of the valve body  12  at the seat  22 . The distal portion  42  of the seal  20  is movable, as discussed in more detail below. The seal  20  separates the upstream chamber  30  from the downstream chamber  32 . The seal  20  has on an upstream side an upstream surface  44  at least partially exposed to the upstream chamber  30 , and has on a downstream side a downstream surface  46  at least partially exposed to the downstream chamber  32 . The seal  20  includes a distal end  50  in the distal portion  42 . The distal end  50  is disposed generally between the upstream surface  44  and the downstream surface  46 . In a specific embodiment, the upstream surface  44  is generally convex and the downstream surface  46  is generally concave. 
     The valve seal  20  is resilient, and includes a flexible material which resiliently biases the seal  20  with a resilient biasing force toward the rest position shown in FIG.  1 . The seal  20  includes a sealing surface in the distal portion  42  and adjacent the distal end  50 . In the rest position, the sealing surface is in contact with the contact surface  54  of the stem body  26  to prevent backflow from the downstream chamber  32  to the upstream chamber  30 . 
     FIG. 3 shows the valve seal  20  in the open position with the sealing surface being spaced from the contact surface  54  of the stem body  26  to permit fluid flow from the upstream chamber  30  to the downstream chamber  32 . The distal portion  42  of the valve seal  20  moves to the open position when the pressure in the upstream chamber  30  is sufficiently large compared to the pressure in the downstream chamber  32  to overcome the resilient biasing force of the seal  20  biasing it toward the closed position. 
     To facilitate movement between the open position and the closed position, the distal portion  42  of the seal  20  is typically more flexible than the proximal portion  40 . In the specific embodiment shown, the distal portion  42  is smaller in cross section than the proximal portion  40 . The cross section of the seal  20  preferably decreases in size generally gradually from the proximal portion  40  to the distal portion  42 . The seal  20  is desirably a single-piece member having a generally homogeneous material that is compatible with the condiment. Suitable materials include elastomeric materials such as silicone and the like. 
     For an annular seal  20 , the sealing surface is peripheral. In the embodiment shown in FIGS. 1-3, the sealing surface is generally inward-facing, while the contact surface  54  of the stem body  26  is generally outward-facing. The contact surface  54  is generally conical in a preferred embodiment. 
     In operation, the resilient biasing force of the resilient seal  20  biases the distal portion  42  toward the rest position with the sealing surface contacting the contact surface  54  of the valve stem  18 , as seen in FIG.  1 . During condiment flow, the pressure in the upstream chamber  30  builds up (e.g., by activating a condiment pump) and acts upon the upstream surface  44  of the seal. When the upstream pressure is sufficiently larger than the downstream pressure in the downstream chamber  32 , it overcomes the biasing force of the resilient seal  20  and moves the distal portion  42  of the seal  20  away from the valve stem  18 , as shown in FIG.  3 . 
     When the upstream pressure drops (e.g., by deactivating the condiment pump), the seal  20  returns to the rest position as shown in FIG.  1 . If the downstream pressure becomes greater than the upstream pressure, it may tend to move the distal portion  42  of the seal  20  toward the upstream chamber  30  to form an opening for backflow to occur. The downstream pressure does not separate the sealing surface from the contact surface  54  of the valve stem  18 , however, because the pressure acts on the downstream surface  46 , resulting in a force that has a component oriented generally toward the contact surface  54 . As a result, the downstream pressure helps maintain the contact between the sealing surface of the seal  20  and the contact surface  54  of the stem  18 . The conical shape of the contact surface  54  is beneficial because it essentially prevents exposure of any part of the seal  20  (i.e., the inward-facing part of the distal portion) to the downstream pressure which would result in a force that separates the sealing surface from the contact surface  54  of the stem  18 . 
     Portion Control Pump 
     FIG. 4 shows a portion control apparatus or pump  100  for providing consistent portion control in dispensing a condiment or the like. The pump  100  typically has a generally symmetrical configuration, and includes a pump chamber  102  having a chamber cavity which is typically cylindrical with a circular cross-section. The chamber  102  includes an inlet  104  which is coupled to a condiment source, and an outlet  106  which may be further coupled to a dispensing device. The inlet  104  and outlet  106  desirably are disposed near opposite ends of the chamber  102 . An outlet valve  110  is disposed at or near the outlet  106 . The outlet valve  110  is preferably a check valve that permits flow only in a direction from the chamber cavity out through the outlet check valve  110 . In a specific embodiment, the outlet check valve  110  is an elastomeric check valve. 
     Disposed inside the chamber cavity is a piston  112 , which is connected to a yoke  114  coupled to a shaft  116 . The shaft  116  extends through an opening of the chamber  102  and is coupled to an air cylinder  118 . The piston  112  includes a piston valve  120 , which is preferably a transfer check valve that permits flow only in a direction from the side of the chamber cavity adjacent the inlet  104  to the side of the chamber adjacent the outlet  106 . In a specific embodiment, the transfer check valve  120  is an elastomeric check valve. The piston  112  desirably makes sealing contact with the interior wall of the chamber  102  with piston seals  122  in the form of O-rings, lip seals, or the like. Shaft seals  124  are desirably provided between the shaft  116  and the opening of the chamber  102  to prevent leakage. 
     The air cylinder  118  drives the shaft  116  to move the piston  112  in a generally linear manner between two positions shown in FIGS. 5A and 5B. In FIG. 5A, the piston  112  is disposed at a first position near the inlet  104  moving away from the inlet  104  toward the outlet  106  in the direction indicated by the arrow  130 . This causes the volume in the inlet chamber cavity portion  132  adjacent the inlet  104  to expand from its minimum level shown in FIG. 5A, and the pressure therein to drop. This produces a suction to draw condiment from the condiment source  136  through the inlet  104  to accumulate in the inlet chamber cavity portion  132 . At the same time, the volume in the outlet chamber cavity portion  134  adjacent the outlet  106  decreases from its maximum level shown in FIG. 5A, and the pressure therein increases. The pressure buildup in the outlet chamber cavity portion  134  keeps the transfer check valve  120  closed to isolate the outlet chamber cavity portion  134  from the inlet chamber cavity portion  132 . The piston seals  122  prevent condiment leakage between the cavity portions  132 ,  134 . The pressure buildup also causes the outlet check valve  110  to open to release air or fluid contained therein. 
     In FIG. 5B, the piston  112  has moved to a second position near the outlet  106  where the inlet chamber cavity portion  132  reaches a maximum volume for accumulating condiment therein. The air cylinder  118  then moves the piston  112  via the shaft  116  away from the outlet  106  toward the inlet  104  in a direction indicated by the arrow  140 . This causes the pressure in the outlet chamber cavity portion  134  to fall, which closes the outlet check valve  110  to prevent backflow through the outlet  106  into the outlet chamber cavity portion  134 . As the volume of the inlet chamber cavity portion  132  decreases, the pressure therein rises. The pressure differential between the inlet chamber cavity portion  132  and the outlet chamber cavity portion  134  causes the transfer check valve  120  to open to permit condiment flow from the inlet chamber cavity portion  132  to the outlet chamber cavity portion  134 . There is typically sufficient vacuum in the outlet chamber cavity portion  134  to draw the condiment from the inlet chamber cavity portion  132  so that there will be no backflow of condiment from the inlet chamber cavity portion  132  into the condiment source  136 . 
     After the piston  112  is moved from the second position in FIG. 5B to the first position in FIG. 5A, an amount of the condiment is transferred from the inlet chamber cavity portion  132  to the outlet chamber cavity portion  134 . That amount of condiment is dispensed out of the outlet chamber cavity portion  134  through the open outlet check valve  110  when the piston  112  is moved from the first position in FIG. 5A to the second position in FIG.  5 B. Movement of the piston  112  reapportions the volume of the chamber cavity between the inlet chamber cavity portion  132  and the outlet chamber cavity portion  134 . The reciprocating action of the air cylinder  118  for moving the piston  112  repeats the cycle of accumulating condiment in the inlet chamber cavity portion  132  and transferring condiment from the inlet chamber cavity portion  132  to the outlet chamber cavity portion  134  for dispensing through the outlet  106 . 
     The piston stroke for the piston  112  is typically set at a level that provides a constant stroke, which produces a generally uniform accumulation of condiment for consistent dispensing in each cycle. The piston stroke can be adjusted by setting the limits of movement of the air cylinder  118  to select the desired amount of condiment for dispensing in each cycle. The portion control pump  100  provides a simple mechanism for reliably providing consistent portion control in dispensing condiments and the like. 
     The above-described arrangements of apparatus and methods are merely illustrative of applications of the principles of this invention and many other embodiments and modifications may be made without departing from the spirit and scope of the invention as defined in the claims. For instance, FIG. 6 shows a portion control apparatus  100 ′ in which both the outlet check valve  110 ′ and the transfer check valve  120 ′ are elastomeric check valves similar to that shown in FIGS. 1-3. In other embodiments, the outlet check valve and the transfer check valve may employ other types of check valves instead of the elastomeric check valve described above. Other drive mechanisms for moving the piston shaft can be used instead of the air cylinder. The piston shaft may also be operated manually. In addition, the chamber may have other shapes, and the piston may be configured to move in a nonlinear manner. Moreover, although the apparatus has been described in the context of condiment dispensing, the apparatus may be used for other fluids, including non-viscous fluids as well as viscous fluids such as beverages and water. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.