Simplified Positive Displacement Syrup Pump Assembly For Drink Machines

Abstract

A simplified positive displacement syrup pump for a drink machine or the like in which a swingable retaining arm releasably holds inlet and outlet valve assemblies in position on an upper chamber shell having a lower peripheral flange which is releasably secured to a peripheral flange of a lower chamber shell with an integral O-ring on the pump diaphragm clamped between the flanges and with a spring bearing between the upper shell and a plate located over the central portion of the diaphragm and with the piston head of a piston rod, extending through the lower shell, in engagement with the underside of the diaphragm.

Description

BACKGROUND OF THE INVENTION

Positive displacement diaphragm pumps are employed in beverage dispensing machines to pump precise amounts of flavoring syrup from storage containers through a pre-cooling unit, and into a mixing chamber or a cup. Since the beverage must be potable, the syrup must remain free from contamination throughout the pumping process. The requirement of cleanliness, together with the tendency of the extremely viscous syrup to congeal within the pump and block the inlet and outlet valves, necessitate frequent disassembly of the syrup pump for cleaning, sanitary inspection and maintenance. Owing to the complexity of the pump assembly special training of maintenance men and tools are required for cleaning.

Existing multiple flavor beverage dispensing machines include four pumps within a single package with a common drive motor and driveshaft and individual cams mounted on the shaft to drive the pumps. Upon selection of a flavor, a solenoid energizes and brings a roller into contact with its associated cam to drive a piston. Despite the economy in the use of a single motor and shaft, the design has serious and expensive shortcomings: the complicated arrangement of solenoids actuating movable arms requires not only special tools but also special training for maintenance and cleaning. This considerably increases the cost of operation, since sanitary vending machines require frequent maintenance and inspection. Moreover the arrangement lacks flexibility in that to increase the number of pumps, thus to increase the flavors offered, would require redesign of the operating unit. A supplier would have to stock at least two models to fill the needs of customers for either four or six flavor machines.

Our improved syrup assembly does away with the disadvantages of pump assemblies of the prior art described above. Our unit provides for quick and easy disassembly, so that maintenance and inspection of four or six individual pumps take less time and less skill than for the more complicated six-pump package. Moreover, since the arrangement of individual pump and motor units is far simpler than the previously known single-motor, multiple-pump arrangement, it requires less maintenance and will have a longer operating life. The simplicity of the design also makes it cheaper to manufacture. Since each pump has its own drive motor, four or six flavor machines may readily be made. A six-flavor beverage machine, for example, would contain six individual pumps, each directly connected to a flavor selection button, rather than the more complicated single motor multi-pump arrangement in which a selector button both closes the motor circuit and energizes the appropriate solenoid.

SUMMARY OF THE INVENTION

One object of our invention is to provide an easily disassembled positive displacement diaphragm pump, requiring no special tools or skill to service or clean.

Another object of our invention is to provide a positive displacement pump assembly which eliminates selection solenoids required in drink machines of the prior art.

A further object of our invention is to provide a positive displacement pump assembly which is adapted for use in four, five or six flavor machines without modification.

Yet another object of our invention is to provide a positive displacement pump assembly which has a long life and which requires less maintenance than do syrup dispensing mechanisms of the prior art.

A still further object of our invention is to provide a syrup pump assembly which is relatively inexpensive to manufacture.

The following description illustrates further objects of our invention.

In general our invention contemplates a simplified positive displacement diaphragm pump comprising upper and lower chamber shells joined by manually removable screws at respective peripheral flanges. A swingable retaining arm releasably holds inlet and outlet valve assemblies in position on the upper chamber shell. The piston head of a piston rod, extending through the lower shell, engages the underside of a diaphragm to clamp an integral O-ring on the diaphragm between the flanges of the shells. A spring bears between the upper shell and a plate located over the center of the diaphragm.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which form part of the instant specification and which are to be read in conjunction therewith and in which like reference numerals are used to represent like parts in the various views:

FIG. 1 is a top plan view of our pump;

FIG. 2 is a sectional view of our pump taken along the line 1--1 of FIG. 1;

FIG. 3 is a side elevation of our pump with part of the lower housing shell removed to show the cam and follower assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Our syrup pump, indicated generally by reference character 10, comprises an upper housing shell 12 and a lower housing shell 14. We mold upper housing shell out of a suitable material such as Lexan, which is the registered trade mark of General Electric for a thermoplastic polycarbonate resin.

We die cast lower housing shell 14 out of a suitable material such as an aluminum alloy. The lower end of the lower housing shell 14 has a threaded bore 16 which receives a threaded bushing retainer 18 carrying a bushing 20 through which a piston rod 22 extends. A head 24 on the upper end of rod 22 supports the central portion of an odorless and tasteless, flexible rubber diaphragm 26, which includes an integral 0-ring 28 enclosing the circular central portion of the diaphragm supported by the piston head 24. The O-ring 28 rests in a channel formed jointly by annular grooves 30 and 32 respectively in a bottom flange 34 of the upper shell 12 and an upper flange 36 of the lower shell 14 to provide a liguid-tight seal between the upper shell and the lower shell. All parts other than the diaphragm 26 may be made of the same food grade Lexan as that used to form the upper housing shell 12.

Four knurled screws 8 pass through screw receptacles 40 in each of the four corners of the flange 34 of the upper shell 12, through holes 42 in each of the four corners of the diaphragm 26 and engage threads in corresponding holes 44 in each of the four corners of the flange 36 of the lower shell to secure upper shell 12 to lower shell 14 thus to clamp the diaphragm 26 between the flanges.

Before assembling the shells 12 and 14, we place a retainer plate 46 over the circular, control portion of the diaphragm. A recess 48 in the center of the plate receives a boss 50 formed at the center of the diaphragm to locate the plate. A compression spring 52 extends from the top of the plate 46 into a recess in the upper end of the upper shell 12. Respective guides 54 and 56 position the spring within the housing.

We form an inlet valve housing 72 integrally with upper shell 12 to receive a reduced diameter portion 74 of an inlet valve body 60. An O-ring 76 located in a channel 78 around the outer periphery of inlet valve body portion 74 provides a seal with the wall of a bore 80 in the inlet valve housing 72. A compression spring 82 bears between a shoulder 84 within the bore 80 of inlet valve housing 72 and a tapered valve 86 to urge the valve into engagement with a seat at the lower end of valve body 60.

We form an outlet valve retainer 88 integrally with upper shell 12 so as to be received in an enlarged diameter portion of a bore 90 in an outlet valve body 62. We place an O-ring 92 upon a shoulder 94 around the outer periphery of the outlet valve retainer and the inner wall of the outlet valve body. An outlet valve 96 engages a seat on the upper edge of an outlet valve retainer 88. We position a compression spring 98 so that it bears between outlet valve 96 and a shoulder 99 formed within the bore 90 of the valve body 62 to urge the valve 96 into engagement with its seat.

A knurled screw 66 passing through a centrally located hole 68 in a valve assembly retainer plate 58 and into the upper housing shell 12 permits plate 58 to swing around a vertical axis and to be releasably clamped in position. Respective slots adjacent the ends of plate 58 are adapted to receive connectors 64 and 65 formed on the upper ends of valve bodies 60 and 62 in one position of the arm 58 so that the arm engages the bodies 60 and 62 to hold them in assembled position. When arm 58 is in the broken line position shown in FIG. 1 the bodies 60 and 62 are free and the valves can readily be disassembled.

We mount a cam roller 100 on a shaft 104 in the lower bifurcated end 102 of the piston rod 22. A snap ring 106 located in a groove around the periphery of the shaft 104 holds the shaft in position.

We mount a cam 112 on a cam shaft 114, coupled to a motor shaft 116 through a gear train 118. A snap ring 120 locks into a groove around the outer periphery of cam shaft 114 adjacent to cam 112. A full cycle switch cam 124, formed integrally with cam 112, is formed with a recess 126 along its circumference for cooperation with the spring arm 128 of a full cycle switch 130, mounted on plate 132 by screws 134. Screws 136 secure the gear box 118 to plate 132.

When motor 142 is energized, it rotates motor shaft 116 which, through gear train 118, drives camshaft 114 and thus cam 112. Cam 112 causes cam roller 100, in continuous contact with cam 112, to move upward, which moves piston rod 22 upward. As piston 22 moves upward, head 24 moves upward against the action of spring 52 thus forcing diaphragm 26 to flex upward against retainer plate 46 and compressing spring 52. The upward flexure of diaphragm 26 decreases the shell assembly volume above the diaphragm to force a charge of syrup outwardly through the outlet valve body 62. When the diaphragm moves downwardly under the influence of spring 52 pressure differential forces syrup from the reservoir through inlet valve body 60. The pressure of the syrup against the valve 86 creates sufficient force to compress the inlet valve spring 82 and thus allow the syrup to flow into the interior of the upper housing shell 12.

Simultaneously, the rotation of the full cycle switch cam 124 (which rotates at the same rpm as cam 112) forces the full cycle switch cam follower 128 out of its groove 126 in the cam 124 thus closing the full cycle cam switch 130 for almost one revolution of the cam shaft 112 to hold the circuit between the motor 12 and its power source (not shown). When the follower arm 128 re-engages the grooved portion of the cam, it opens the switch 130, which opens the motor circuit, thus completing the cam cycle with a full revolution of the shaft 114.

To disassemble the pump, as for cleaning, we loosen knurled head screw 66, and rotate top retainer plate 58 to the broken line position. We then remove inlet valve body 60, outlet valve body 62, inlet valve spring 82, outlet valve spring 98, inlet valve 86, outlet valve 92, and inlet valve O-ring 75 and outlet valve O-ring 94.

Removal of four knurled head screws 88 from screw receptacles 46 frees upper shell 12 from lower shell 14. Separation of upper shell exposes pump components within the chamber of the upper shell. We can remove diaphragm spring 52 from retaining plate 46 and remove retaining plate 46 and diaphragm 26.

It will be seen that we have accomplished the objects of our invention. We have provided a syrup pump which has the following advantages over syrup pumps of the prior art:

1. the design is such that extensive machining operations are not required as the major components can be completely formed by die casting and injection molding;

2. the pump can be completely disassembled by manually removing five screws, permitting easy servicing and cleaning of diaphragm and internal parts;

3. removal of the upper shell permits removal of the diaphragm alone without tools or disassembly of additional parts;

4. the unitary pump motor combination lends itself easily to adaption to either four or six-flavor machines without modification of the basic unit;

5. the individual motor on each pump also eliminates the need for complex selection solenoids and hinged cam followers as used on four-flavor syrup pumps;

6. placing the diaphragm return spring in front of the diaphragm instead of behind it eliminates not only the need for holes in the diaphragm but also the need to remove the return spring in order to remove the diaphragm.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention. It is, therefore, to be understood that our invention is not to be limited to the specific details shown and described.

Claims

Having thus described our invention, what we claim is:

1. In a simplified positive displacement pump assembly, a chamber-forming shell, an inlet valve body integrally formed with said shell, an inlet valve seat-forming member removably received by said inlet valve body, an outlet valve seat-forming member integrally formed with said shell, an outlet body removably received by said outlet valve seat-forming member, an arm mounted on said shell for movement between a first position and a second position, and interengageable means on said arm and on said inlet valve seat-forming member and said outlet valve body for retaining said inlet valve seat-forming member and said outlet valve body assembled on said shell in said first position of said arm and for releasing said inlet valve seat-forming member and said outlet valve body in the second position of said arm, said arm being mounted for pivotal movement at a location intermediate its ends, said interengageable means comprising necks formed on said inlet valve seat-forming member and said outlet valve body respectively and means forming slots in the ends of said arm for receiving said necks.

2. A simplified positive displacement pump assembly including in combination, a first chamber forming shell, an inlet valve assembly, an outlet valve assembly, first readily releasable means for retaining said inlet and outlet valve assemblies in assembled relationship with said first shell, a second shell, a diaphragm, second releasable means for securing said shells in assembled relationship with a peripheral portion of said diaphragm clamped between said shells, the portion of said diaphragm within said peripheral portion being imperforate, a retainer plate in said first shell, said retainer plate engaging one side of said diaphragm in the absence of a positive connection thereto in the assembled condition of said shells and being free of said diaphragm upon disassembly of said shells, a rod mounted for movement on said second shell, a plate-like head on said rod engaging the other side of said diaphragm in the absence of a positive connection thereto in the assembled condition of said shells and being free of said diaphragm upon disassembly of said shells, a spring in said first shell for urging said retainer plate into engagement with said one side of said diaphragm and for urging said other side of said diaphragm into engagement with said head, and means for driving said rod against the return of said spring.

3. An assembly as in claim 2 in which said diaphragm is formed with a locating boss and in which said plate is formed with a recess for receiving said boss.

4. A pump assembly as in claim 2 in which said shells have respective peripheral flanges adapted to butt in the assembled condition of said shells, said flanges being formed with annular recesses, and an O-ring integrally formed with said diaphragm disposed in said recesses in the assembled condition of said shells.

5. A pump assembly as in claim 2 in which said valve-retaining means comprises an arm, means mounting said arm on said first shell for movement between a first position and a second position and interengageable means on said arm and on said valve assemblies for engaging in said first position to retain said assemblies and for disengaging in said second position to release said valve assemblies.

6. An assembly as in claim 2 in which said inlet valve assembly comprises a valve body formed integrally with said first shell and a valve seat-forming member releasably received in said body.

7. An assembly as in claim 2 in which said outlet valve assembly comprises a valve seat forming portion integrally formed with said first shell and a valve body removably received by said portion.

8. A pump assembly as in claim 5 including means for releasably clamping said arm in said first position.

9. A pump assembly as in claim 8 in which said arm is mounted on said shell for rotational movement and in which said interengageable means each comprise means forming a neck on a valve assembly and means forming a recess in an end of said arm for receiving said neck.

10. A pump assembly as in claim 9 in which said clamping means comprises a screw extending through said arm intermediate the ends thereof and into said shell.