Double-acting diaphragm pump and reversing mechanism therefor

Claims

I claim:

1. A reciprocating pump and reversing mechanism therefor comprising in combination:

(a) a pump housing including a pair of laterally spaced-apart chambers each of which has a diaphragm member therein dividing each chamber into a driving section and a discharge section, each of said discharge sections having an inlet port and an outlet port and each of said driving sections having inlet-outlet port means;

(b) said diaphragm members being interconnected by a shaft mounted in said housing for reciprocating movement, whereby said shaft moves with said diaphragm members such that as the driving section of one chamber expands, forcing its discharge section to contract, the driving section of the other chamber contracts while its discharge section expands;

(c) protrusion means fixedly connected to said shaft and extending transversely therefrom for use in coupling the movement of said shaft to the movement of the below-recited valve actuating member;

(d) said housing also including a fluid outlet manifold interconnecting said outlet ports of said discharge sections, a fluid inlet manifold interconnecting said inlet ports of said discharge sections, and driving fluid manifold means for feeding driving fluid to and from said inlet-outlet port means of said driving sections;

(e) inlet and outlet valves in said housing in fluid communication with said fluid inlet and outlet manifolds, respectively, for controlling the flow of fluid to be pumped to and from each of said discharge sections;

(f) control valve means including valve housing means for housing said control valve means, said valve housing means being connected to said pump housing and including reciprocable spool valve element means in said valve housing means and being in fluid communication with said driving fluid manifold means and being movable between two alternate positions for alternately directing driving fluid to one of said two driving sections, while also alternately allowing driving fluid to flow from the other one of said two driving sections, said spool valve element means having first contact surface means for being contacted by the below-recited valve actuating member;

(g) a valve actuating member mounted for reciprocating movement between two control valve-actuated end positions, said valve actuating member having second contact surface means positioned adjacent said first contact surface means of said spool valve element means for alternately snap contacting said first contact surface means to alternately snap said spool valve element means back and forth between its two positions, said valve actuating member also having third contact surface means for use in coupling the movement of said shaft to the movement of said valve actuating member, coupling means including said protrusion means and said third contact surface means for operatively coupling said protrusion means to said valve actuating means for alternately initiating each reciprocating stroke of said valve actuating member as said shaft reciprocates, the completion of each of said reciprocating strokes of said valve actuating member being carried out by the below-recited snap-acting means;

(h) snap-acting means, including at least one pin, a helicoidal compression spring at least partially surrounding said pin and a pin mounting element, for completing the movement of said valve actuating member from one of its two positions to the other initiated by said coupling means, said pin mounting element being pivotably secured for at least partial rotation about an axis stationary with respect to one of said valve actuating member and said housing, said pin being slidably mounted to said pin mounting element for sliding motion in a direction perpendicular to said axis; and

(i) wherein said pin mounting element is in the form of a tubular socket for receiving an end of said pin and at least a portion of said compression spring.

2. A reciprocating pump and reversing mechanism therefor comprising in combination:

(a) a pump housing including a pair of laterally spaced-apart chambers each of which has a diaphragm member therein dividing each chamber into a driving section and a discharge section, each of said discharge sections having an inlet port and an outlet port and each of said driving sections having inlet-outlet port means;

(b) said diaphragm members being interconnected by a shaft mounted in said housing for reciprocating movement, whereby said shaft moves with said diaphragm members such that as the driving section of one chamber expands, forcing its discharge section to contract, the driving section of the other chamber contracts while its discharge section expands;

(c) a protrusion fixedly connected to said shaft and extending transversely therefrom;

(d) said housing also including a fluid outlet manifold interconnecting said outlet ports of said discharge sections, a fluid inlet manifold interconnecting said inlet ports of said discharge sections, and a driving fluid manifold interconnecting said inlet-outlet port means of said driving sections;

(e) inlet and outlet valves in said housing in fluid communication with said fluid inlet and outlet manifolds, respectively, for controlling the flow of fluid to be pumped to and from each of said discharge sections;

(f) control valve means including a valve housing connected to said pump housing between said chambers and including a reciprocable spool valve element therein in fluid communication with said driving fluid manifold and movable between two alternate positions to alternately direct driving fluid to said two driving sections while also alternately allowing driving fluid to flow from the other one of said two driving sections, said spool valve element having a pair of opposite contact ends;

(g) a yoke-shaped valve actuating member mounted for reciprocating movement between two control valve-actuated end positions, said valve actuating member having a pair of spaced-apart arms positioned one each adjacent respective ones of said opposite contact ends of said spool valve element for alternately snap contacting said opposite contact ends to alternately snap said spool valve element back and forth between its two positions, said valve actuating member also having a pair of spaced-apart surfaces positioned one each on opposite sides of said protrusion for alternately being contacted by said protrusion as said shaft reciprocates for initiating each reciprocating stroke of said valve actuating member, the completion of each of said reciprocating strokes being carried out by the below-recited snap-acting means;

(h) snap-acting means connected to said valve actuating member for completing the movement of said valve actuating member from one of its two positions to the other initiated by said protrusion engaging one of said pair of surfaces of said valve actuating member, said snap-acting means including a pair of opposed spring means connected to said valve actuating member and being located on opposite sides thereof, each of said spring means including at least one pin, a helicoidal compression spring at least partially surrounding said pin and a pin mounting element, said pin mounting element being pivotably secured for at least partial rotation about an axis stationary with respect to one of said valve actuating member and said pump housing, said pin being slidably mounted adjacent one end thereof to said element for sliding motion in a direction perpendicular to said axis, and said pin being pivotably mounted adjacent its other end to the other of said control valve actuating member and said pump housing; and

(i) wherein each of said pin mounting elements includes a bore therein having an axis perpendicular to said stationary axis for receiving both an end of a respective one of said pins and at least a portion of a respective one of said compression springs.

3. A reciprocating pump and reversing mechanism therefor comprising in combination:

(a) a pump housing including a pair of laterally spaced-apart chambers each of which has a diaphragm member therein dividing each chamber into a driving section and a discharge section, each of said discharge sections having an inlet port and an outlet port and each of said driving sections having inlet-outlet port means;

(b) said diaphragm members being interconnected by a shaft mounted in said housing for reciprocating movement, whereby said shaft moves with said diaphragm members such that as the driving section of one chamber expands, forcing its discharge section to contract, the driving section of the other chamber contracts while its discharge section expands;

(c) protrusion means fixedly connected to said shaft and extending transversely therefrom for use in coupling the movement of said shaft to the movement of the below-recited valve actuating member;

(d) said housing also including a fluid outlet manifold interconnecting said outlet ports of said discharge sections, a fluid inlet manifold interconnecting said inlet ports of said discharge sections, and driving fluid manifold means for feeding driving fluid to and from said inlet-outlet port means of said driving sections;

(e) inlet and outlet valves in said housing in fluid communication with said fluid inlet and outlet manifolds, respectively, for controlling the flow of fluid to be pumped to and from each of said discharge sections;

(f) control valve means including valve housing means for housing said control valve means, said valve housing means being connected to said pump housing and including movable valve element means therein in fluid communication with said driving fluid manifold means and movable between two alternate positions for alternately directing driving fluid to one of said two driving sections while also alternately allowing driving fluid to vent from the other one of said two driving sections, said valve element means having contact means for being contacted by the below-recited control valve actuating member for moving said valve element means back and forth between its two positions;

(g) a control valve actuating member mounted for movement between two control valve-actuated positions, said control valve actuating member having contacting means for engaging said contact means, said contacting means being positioned adjacent said contact means of said valve element means for alternately moving said valve element means back and forth between its two positions, said control valve actuating member also having contact surface means for use in coupling the movement of said shaft to the movement of said valve actuating member, and coupling means including said protrusion means and said contact surface means for operatively coupling said protrusion means to said valve actuating means for initiating each reciprocating stroke of said control valve actuating member, the completion of each of said reciprocating strokes being carried out by the below-recited snap-acting means;

(h) snap-acting means connected to said control valve actuating member for completing the movement of said control valve actuating member from one of its two positions to the other initiated by said coupling means, said snap-acting means including at least one pin, a helicoidal compression spring at least partially surrounding said pin and a pin mounting element, said pin mounting element being pivotably secured for at least partial rotation about an axis stationary with respect to one of said control valve actuating member and said pump housing, said pin being slidably mounted adjacent one end thereof to said pin mounting element for sliding motion in a direction perpendicular to said axis, and said pin being pivotably mounted adjacent its other end about an axis stationary with respect to the other of said control valve actuating member and said pump housing; and

(i) wherein said pin mounting element includes a bore therein that is perpendicular to said pin mounting axis, said bore slidably receiving an end of said pin and receiving at least a portion of one end of said compression spring.

4. A reciprocating pump and reversing mechanism therefor comprising in combination:

(a) a pump housing including a pair of laterally spaced-apart chambers each of which has a diaphragm member therein dividing each chamber into a driving section and a discharge section, each of said discharge sections having an inlet port and an outlet port and each of said driving sections having inlet-outlet port means;

(b) said diaphragm members being interconnected by a shaft mounted in said housing for reciprocating movement, whereby said shaft moves with said diaphragm members such that as the driving section of one chamber expands, forcing its discharge section to contract, the driving section of the other chamber contracts while its discharge section expands;

(c) protrusion means fixedly connected to said shaft and extending transversely therefrom for use in coupling the movement of said shaft to the movement of the below-recited valve actuating member;

(d) said housing also including a fluid outlet manifold interconnecting said outlet ports of said discharge sections, a fluid inlet manifold interconnecting said inlet ports of said discharge sections, and driving fluid manifold means for feeding driving fluid to and from said inlet-outlet port means of said driving sections;

(e) inlet and outlet valves in said housing in fluid communication with said fluid inlet and outlet manifolds, respectively, for controlling the flow of fluid to be pumped to and from each of said discharge sections;

(f) control valve means including valve housing means for housing said control valve means, said valve housing means being connected to said pump housing and including reciprocable spool valve element means in said valve housing means and being in fluid communication with said driving fluid manifold means and being movable between two alternate positions for alternately directing driving fluid to one of said two driving sections, while also alternately allowing driving fluid to flow from the other one of said two driving sections, said spool valve element means having first contact surface means for being contacted by the below-recited valve actuating member;

(g) a valve actuating member mounted for reciprocating movement between two control valve-actuated end positions, said valve actuating member having second contact surface means positioned adjacent said first contact surface means of said spool valve element means for alternately snap contacting said first contact surface means to alternately snap said spool valve element means back and forth between its two positions, said valve actuating member also having third contact surface means for use in coupling the movement of said shaft to the movement of said valve actuating member, coupling means including said protrusion means and said third contact surface means for operatively coupling said protrusion means to said valve actuating means for alternately initiating each reciprocating stroke of said valve actuating member as said shaft reciprocates, the completion of each of said reciprocating strokes of said valve actuating member being carried out by the below-recited snap-acting means;

(h) snap-acting means, including at least one pin, a helicoidal compression spring at least partially surrounding said pin and a pin mounting element, for completing the movement of said valve actuating member from one of its two positions to the other initiated by said coupling means, said pin mounting element being pivotably secured for at least partial rotation about an axis stationary with respect to one of said valve actuating member and said housing, said pin being slidably mounted to said pin mounting element for sliding motion in a direction perpendicular to said axis; and

(i) wherein said third contact surface means comprises a plurality of arms projecting from said valve actuating member on the opposite side thereof from said second contact surface means, and extending in the direction toward said protrusion means.

5. The reciprocating pump and reversing mechanism therefor as recited in claim 4 wherein said second contact surface means comprises a plurality of arms extending in a direction toward said first contact surface means.

6. A reciprocating pump and reversing mechanism therefor comprising in combination:

(a) a pump housing including a pair of laterally spaced-apart chambers each of which has a diaphragm member therein dividing each chamber into a driving section and a discharge section, each of said discharge sections having an inlet port and an outlet port and each of said driving sections having inlet-outlet port means;

(b) said diaphragm members being interconnected by a shaft mounted in said housing for reciprocating movement, whereby said shaft moves with said diaphragm members such that as the driving section of one chamber expands, forcing its discharge section to contract, the driving section of the other chamber contracts while its discharge section expands;

(c) protrusion means fixedly connected to said shaft and extending transversely therefrom for use in coupling the movement of said shaft to the movement of the below-recited valve actuating member;

(d) said housing also including a fluid outlet manifold interconnecting said outlet ports of said discharge sections, a fluid inlet manifold interconnecting said inlet ports of said discharge sections, and driving fluid manifold means for feeding driving fluid to and from said inlet-outlet port means of said driving sections;

(e) inlet and outlet valves in said housing in fluid communication with said fluid inlet and outlet manifolds, respectively, for controlling the flow of fluid to be pumped to and from each of said discharge sections;

(f) control valve means including valve housing means for housing said control valve means, said valve housing means being connected to said pump housing and including movable valve element means therein in fluid communication with said driving fluid manifold means and movable between two alternate positions for alternately directing driving fluid to one of said two driving sections while also alternately allowing driving fluid to vent from the other one of said two driving sections, said valve element means having contact means for being contacted by the below-recited control valve actuating member for moving said valve element means back and forth between its two positions;

(g) a control valve actuating member mounted for movement between two control valve-actuated positions, said control valve actuating member having contacting means for engaging said contact means, said contacting means being positioned adjacent said contact means of said valve element means for alternately moving said valve element means back and forth between its two positions, said control valve actuating member also having contact surface means for use in coupling the movement of said shaft to the movement of said valve actuating member, and coupling means including said protrusion means and said contact surface means for operatively coupling said protrusion means to said valve actuating means for initiating each reciprocating stroke of said control valve actuating member, the completion of each of said reciprocating strokes being carried out by the below-recited snap-acting means;

(h) snap-acting means connected to said control valve actuating member for completing the movement of said control valve actuating member from one of its two positions to the other initiated by said coupling means, said snap-acting means including at least one pin, a helicoidal compression spring at least partially surrounding said pin and a pin mounting element, said pin mounting element being pivotably secured for at least partial rotation about an axis stationary with respect to one of said control valve actuating member and said pump housing, said pin being slidably mounted adjacent one end thereof to said pin mounting element for sliding motion in a direction perpendicular to said axis, and said pin being pivotably mounted adjacent its other end about an axis stationary with respect to the other of said control valve actuating member and said pump housing; and

(i) wherein said contact surface means comprises a plurality of arms projecting from said valve actuating member on the opposite side thereof from said contacting means and extending in the direction toward said protrusion means.

7. The reciprocating pump and reversing mechanism therefor as recited in claim 6 wherein said contacting mean comprises a plurality of arms extending in a direction toward said contact means.

8. A reciprocating pump and reversing mechanism therefor comprising in combination:

(a) a pump housing including a pair of laterally spaced-apart chambers each of which has a diaphragm member therein dividing each chamber into a driving section and a discharge section, each of said discharge sections having an inlet port and an outlet port and each of said driving sections having inlet-outlet port means;

(b) said diaphragm members being interconnected by a shaft mounted in said housing for reciprocating movement, whereby said shaft moves with said diaphragm members such that as the driving section of one chamber expands, forcing its discharge section to contract, the driving section of the other chamber contracts while its discharge section expands;

(c) protrusion means fixedly connected to said shaft and extending transversely therefrom for use in coupling the movement of said shaft to the movement of the below-recited valve actuating member;

(d) said housing also including a fluid outlet manifold interconnecting said outlet ports of said discharge sections, a fluid inlet manifold interconnecting said inlet ports of said discharge sections, and driving fluid manifold means for feeding driving fluid to and from said inlet-outlet port means of said driving sections;

(e) inlet and outlet valves in said housing in fluid communication with said fluid inlet and outlet manifolds, respectively, for controlling the flow of fluid to be pumped to and from each of said discharge sections;

(f) control valve means including valve housing means for housing said control valve means, said valve housing means being connected to said pump housing and including reciprocable spool valve element means in said valve housing means and being in fluid communication with said driving fluid manifold means and being movable between two alternate positions for alternately directing driving fluid to one of said two driving sections, while also alternately allowing driving fluid to flow from the other one of said two driving sections, said spool valve element means having first contact surface means for being contacted by the below-recited valve actuating member;

(g) a valve actuating member mounted for reciprocating movement between two control valve-actuated end positions, said valve actuating member having second contact surface means positioned adjacent said first contact surface means of said spool valve element means for alternately snap contacting said first contact surface means to alternately snap said spool valve element means back and forth between its two positions, said valve actuating member also having third contact surface means for use in coupling the movement of said shaft to the movement of said valve actuating member, coupling means including said protrusion means and said third contact surface means for operatively coupling said protrusion means to said valve actuating means for alternately initiating each reciprocating stroke of said valve actuating member as said shaft reciprocates, the completion of each of said reciprocating strokes of said valve actuating member being carried out by the below-recited snap-acting means;

(h) snap-acting means, including at least one pin, a helicoidal compression spring at least partially surrounding said pin and a pin mounting element, for completing the movement of said valve actuating member from one of its two positions to the other initiated by said coupling means, said pin mounting element being pivotably secured for at least partial rotation about an axis stationary with respect to one of said valve actuating member and said housing, said pin being slidably mounted to said pin mounting element for sliding motion in a direction perpendicular to said axis; and

(i) wherein said pin mounting element is provided with an aperture traversed by said pin.

9. The reciprocating pump and reversing mechanism therefor as recited in claim 8 wherein said pin mounting element is pivotably mounted on said valve actuating member.

10. The reciprocating pump and reversing mechanism therefor as recited in claim 9 wherein said pin mounting element is in the form of a tubular socket for receiving an end of said pin and at least a portion of said compression spring.

11. A reciprocating pump and reversing mechanism therefor comprising in combination:

(a) a pump housing including a pair of laterally spaced-apart chambers each of which has a diaphragm member therein dividing each chamber into a driving section and a discharge section, each of said discharge sections having an inlet port and an outlet port and each of said driving sections having inlet-outlet port means;

(b) said diaphragm members being interconnected by a shaft mounted in said housing for reciprocating movement, whereby said shaft moves with said diaphragm members such that as the driving section of one chamber expands, forcing its discharge section to contract, the driving section of the other chamber contracts while its discharge section expands;

(c) a protrusion fixedly connected to said shaft and extending transversely therefrom;

(d) said housing also including a fluid outlet manifold interconnecting said outlet ports of said discharge sections, a fluid inlet manifold interconnecting said inlet ports of said discharge sections, and a driving fluid manifold interconnecting said inlet-outlet port means of said driving sections;

(e) inlet and outlet valves in said housing in fluid communication with said fluid inlet and outlet manifolds, respectively, for controlling the flow of fluid to be pumped to and from each of said discharge sections;

(f) control valve means including a valve housing connected to said pump housing between said chambers and including a reciprocable spool valve element therein in fluid communication with said driving fluid manifold and movable between two alternate positions to alternately direct driving fluid to said two driving sections while also alternately allowing driving fluid to flow from the other one of said two driving sections, said spool valve element having a pair of opposite contact ends;

(g) a yoke-shaped valve actuating member mounted for reciprocating movement between two control valve-actuated end positions, said valve actuating member having a pair of spaced-apart arms positioned one each adjacent respective ones of said opposite contact ends of said spool valve element for alternately snap contacting said opposite contact ends to alternately snap said spool valve element back and forth between its two positions, said valve actuating member also having a pair of spaced-apart surfaces positioned one each on opposite sides of said protrusion for alternately being contacted by said protrusion as said shaft reciprocates for initiating each reciprocating stroke of said valve actuating member, the completion of each of said reciprocating strokes being carried out by the below-recited snap-acting means;

(h) snap-acting means connected to said valve actuating member for completing the movement of said valve actuating member from one of its two positions to the other initiated by said protrusion engaging one of said pair of surfaces of said valve actuating member, said snap-acting means including a pair of opposed spring means connected to said valve actuating member and being located on opposite sides thereof, each of said spring means including at least one pin, a helicoidal compression spring at least partially surrounding said pin and a pin mounting element, said pin mounting element being pivotably secured for at least partial rotation about an axis stationary with respect to one of said valve actuating member and said pump housing, said pin being slidably mounted adjacent one end thereof to said element for sliding motion in a direction perpendicular to said axis, and said pin being pivotably mounted adjacent its other end to the other of said control valve actuating member and said pump housing; and

(i) wherein each of said pin mounting elements includes a bore in which one end of a respective one of said pins is slidably received.

12. The reciprocating pump and reversing mechanism therefor as recited in claim 11 wherein each of said pin mounting elements is pivotably mounted on said control valve actuating member.

13. The reciprocating pump and reversing mechanism therefor as recited in claim 12 wherein each of said bores also receives at least a portion of a respective one of said springs.

14. The reciprocating pump and reversing mechansim therefor as recited in claim 11 wherein said control valve actuating member is located at least partially above said shaft and between said control valve means and said shaft.

15. The reciprocating pump and reversing mechanism therefor as recited in claim 14 wherein said snap-acting means is connected adjacent the bottom of said control valve actuating member.

16. The reciprocating pump and reversing mechanism therefor as recited in claim 15 wherein said pair of spring means exert equal and opposite forces on said valve actuating member in directions transverse to the axis of said shaft throughout all positions of movement of said valve actuating member on said shaft.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a pneumatically-operated diaphragm pump utilized in a Post-mix beverage syrup dispensing system and more specifically to a reciprocating pump including a spring actuated reversing means for reversing the direction of a reciprocating pump at the end of its respective strokes.

2. Description of the Prior Art

Diaphragm pumps are widely used particularly for pumping liquid solutions and highly viscous materials and are frequently used under conditions such that the viscosity of the fluid being pumped, the head of the suction side of the pump and the back pressure on the pump discharge may all vary as conditions under which the pump is operating vary. The speed of such pumps has generally been controlled by inserting an adjustable valve in the air line leading to the pump. However, this approach requires that the operation of the pump be kept under continuous observation and the valve adjusted to suit varying conditions, otherwise the speed of the pump will vary substantially depending upon the conditions of operation. For example, if the back pressure on the pump should increase or decrease for any particular reason, or if the viscosity of the liquid being pumped should vary, then the speed of operation and the quantity of liquid being pumped per unit of time will accordingly be affected. Therefore, it is highly desirable that the pump be controlled such that it operates at a substantially constant speed under varying conditions. Furthermore, it is essential that the entire pumping cycle be completed so as to ensure continuous delivery of the medium being pumped at a constant consistency or concentration. In order to ensure the latter, means have been suggested such as disclosed in U.S. Pat. No. 4,008,984 wherein opposed coil springs are provided for assisting the respective valve member in the completion of its pumping cycle. The coil compression springs of identical force under the pressurized gas system assist in completion of the pumping cycle first in one direction, and then by asserting a positive reversing effect when either of the springs becomes fully compressed. Although providing a reversing mechanism for the double acting pump disclosed, there are inherent disadvantages with such a system. For example, if for some reason the pressurized system is effected in such a way that a back pressure is created or established so as to inhibit or reverse the pumping cycle before it is completed, there is no means for overcoming the undesirable effect, and the fully compressed state of the spring is not reached. Thus, it is possible that the pumping cycle could be reversed regardless of the presence of the compression springs, before the cycle is completed, thus effecting the efficiency, if not the complete purpose, of the reciprocating pump.

It is, therefore, an object of the present invention to provide a reciprocating diaphragm pump for delivering, under constant pressure, syrup to a Post-mix beverage dispensing system which will overcome the above noted disadvantages.

It is a further ob3ect of the present invention to provide a double-acting reciprocating pump for syrup in a Post-mix beverage dispensing system wherein a reversing means is provided for reversing the direction of the pump at the end of each respective stroke.

Yet, still a further object of the present invention is to provide a gas-operated diaphragm pump including a specialized valve, actuated by a springloaded member attached to a common shaft, which alternates the supply of pressurized gas to the respective diaphragms.

It is still a further object of the present invention to provide a double-acting reciprocating pneumatic pump for dispensing syrup to a dispensing outlet wherein the pump cycle reversing system includes a snap-acting reversing means which ensures the completion of the pumping cycle and precludes the sticking of the pneumatic reversing mechanism in an intermediate position.

Yet, still another object of the present invention is to provide a pneumatic double-acting reciprocating pump having a reversing system which includes a valve, a valve actuating member, and a snap-acting spring member which reliably directs the supply of pressurized gas to the surface of either one of the two diaphragms in a cyclic manner.

A further object of the present invention is to provide a reciprocating pneumatic diaphragm pump including a reversing means which allows for the dispersing of fluid from either one of two diaphragm chambers at the respective ends of the pump in a systematic, controlled manner.

Other objects and further scope of applicability of the present invention will become more apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration only since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. Any such changes and modifications should be considered to be within the scop of this invention.

SUMMARY OF THE INVENTION

The foregoing objects and others are accomplished in accordance with the present invention generally speaking by providing a pumping device comprising a pair of flexible diaphragms mounted on the respective ends of a common shaft. The outer surface of the diaphragms are in contact with the liquid to be dispensed by the system, more particularly syrup for a Post-mix beverage dispensing system. The chamber within the pump housing contains an inner wall in which passages are provided for directing compressed air, introduced into the reciprocating pump, to the surfaces of the diaphragms. The flow of air is controlled by a reversing valve adapted so as to redirect the flow of compressed air to the respective diaphragm at the completion of each stroke of the pump in a cyclic manner. A valve actuating member or yoke is provided which engages the shaft within the inner chamber of the pump housing and travels with the pumping action of the shaft. The yoke is designed so as to engage the reversing valve during the terminal phase of the pumping stroke, thus activating the valve and reversing the piston action of the pump. To complete the pump reversing system, a snap-acting spring actuating means interconnected with the yoke of the shaft, is centered within the inner chamber of the housing of the pump, pivotably mounted beneath the shaft connecting the diaphragms. The valve is provided with O-rings positioned within the valve body with respect to the air passages of the valve such that during the first half of the reciprocating cycle, pressurized gas is introduced through the respective passageways and directed to the air chamber of one of the diaphragms. At the same time, a passage is provided for exhaust gases to be released from the air chamber of the remaining diaphragm. Upon interaction with the shaft yoke and the spring mounted actuating means, the relationship of the valve openings to the pressurized gas acting on the surface of the respective diaphragm is changed at the completion of the pumping stroke so as to reverse the action of the pump. The snap-action mechanism provided precludes the sticking of the pneumatic reversing system in an intermediate position.

In operation, pressurized gas is introduced through a passageway into a valve member and is directed via a passageway within the inner wall of the pump housing to the air chamber of one of the diaphragms within the pump. As the piston action of the diaphragm forces syrup from the diaphragm chamber out the appropriate passage to the dispensing outlet, movement of the shaft also moves the remaining diaphragm in a non-pressurizing direction. This same shaft movement also engages the shaft yoke. As the shaft yoke moves, it initiates the pivotal action of a pair of snap-acting compression springs which, prior to rotating off-center, are pushing against each other. As the springs rotate off-center, they uncoil and push the shaft and yoke along in the direction of the established movement. The action of the spring mechanism ensures that the movement of the diaphragm, initiated by the air pressure, is taken to completion by the snap action of the compression springs, while at the same time reversing the flow of pressurized air within the valve member. This procedure is then repeated as long as the dispensing outlet is open and the syrup is being dispensed as a pressurized stream. When the dispensing outlet is closed, sufficient back pressure is exerted on the diaphragms to prevent shaft movement.

It has been determined in the course of the present invention that a reciprocating diaphragm pump for syrup in a Post-mix beverage dispensing system can be provided such that the liquid can be delivered under controlled pressure conditions in a reliable manner. A reversing valve is provided which includes a pair of compression springs bearing one on the other so as not to apply pressure of the bearing surfaces on the pump shaft.

In an alternative embodiment of the present invention, the control or reversing valve, the reciprocating actuating member and the opposed coil springs are provided in a common housing or module. This module is removably secured to the pump body adjacent to the pump shaft and can be removed as a unit for ease of repair. The module housing is preferably molded from plastic in two pieces which slide toge