US3676022A - Pneumatic/hydraulic pressure actuated positive displacement pump - Google Patents

Abstract

A PNEUMATIC OR HYDRAULIC PRESSURE ACTUATED POSITIVE DISPLACEMENT PUMP OF RECIPROCATING TYPE WITH PISTON ASSEMBLY SHIFTABLE FROM ONE OPEN PUMP POSITION ENABLING PUMP PRIMING THROUGH THE VOID PROVIDED IN THE PUMP CHAMBER WHEN THE WORKING FLUID PRESSURE IS RELIEVED, INTO THE SECOND POSITION FOR PUMPING OUT THE CONTENTS TRAPPED IN SAID PUMP CHAMBER UPON THE APPLICATION OF THE WORKING FLUID TO THE OPPOSITE END OF SAID PISTON ASSEMBLY, AND SUBSEQUENT RETURN OF THE PISTON TO THE ORIGINAL POSITION WHEN SAID WORKING FLUID IS RELIEVED, BY THE SUCTION FORCE THAT IS GENERATED DURING THE FORWARD PISTON MOVEMENT WHEN IT IS ENERGIZED BY PRESSURE OF THE WORKING FLUID, PISTON ASSEMBLY COMPRISING ONE LARGE WORKING PISTON WITH U-CUP SEALS AT EXTREMITIES AND ORIENTED SO AS TO EXPAND UNDER PRESSURE FOR BETTER SEALING, AND TWO SMALLER PISTONS AT EACH END OF LARGE PISTON FACE, ONE FOR ACTING AS A SUCTION CUP TO RETURN PISTON ASSEMBLY TO THE ORIGINAL POSITION WHEN WORKING FLUID PRESSURE IS RELIEVED FROM THE PISTON ENERGIZATION PORT, INCLUDING APPROPRIATE SEALS, ANOTHER PISTON AT THE OPPOSITE END FOR PLUGGING-OFF FLUID PUMPED FROM THE SUPPLY SOURCE IN ORDER TO FACILITATE IMPROVED PUMPING WITH MINIMUM SLIPPAGE.

Description

United Patent Qflice 3,676,022 Patented July 11, 1972 US. Cl. 417392 2 Claims ABSTRACT OF THE DISCLOSURE A pneumatic or hydraulic pressure actuated positive displacement pump of reciprocating type with piston assembly shiftable from one open pump position enabling pump priming through the void provided in the pump chamber when the working fluid pressure is relieved, into the second position for pumping out the contents trapped in said pump chamber upon the application of the working fluid to the opposite end of said piston assembly, and subsequent return of the piston to the original position when said working fluid is relieved, by the suction force that is generated during the forward piston movement when it is energized by pressure of the working fluid; piston assembly comprising one large working piston with U-cup seals at extremities and oriented so as to expand under pressure for better sealing, and two smaller pistons at each end of large piston face, one for acting as a suction cup to return piston assembly to the original position when working fluid pressure is relieved from the piston energization port, including appropriate seals, another piston at the opposite end for plugging-off fluid pumped from the supply source in order to facilitate improved pumping with minimum slippage.

In the past, the positive displacement pumps actuated by pneumatic or hydraulic actuation means have been provided with either double acting or single acting-spring return shifts. Also, most pumps of the conventional design require the use of complicated valving systems to control the directional flow of fluid pumped. Further, such pumps incorporate extremely complex packings for sealing pump chamber and the associated movers. In turn it is practically impossible to ascertain the integrity of pump seals in existing pumps until complete seal failure prevails. Further the problem is aggrevated by the difficulties to maintain such pumps because of their overall complexity. In general, pumps of conventional design are to complicated, too bulky, and too costly.

The present invention provides a positive displacement pump which is simple in design, light in weight, easily serviceable and relatively inexpensive. The pump of present invention is not limited to any specific capacity range and is capable of delivering exact amounts of fluids pumped regardless of fluid condition, be it pure liquid, viscous grease or aerated eggnog, in volumetric flows controllable by an easily accessible adjustment.

The problem associated with the prior art construction in terms of spring return shifts have been eliminated here through the use of simple suction cup slidable axially within its mating bore to result in ample suction energy necessary for pump operation by consecutive stroking constitutin g simple single acting novel pump design without the use of springs.

The integration of working piston with the pumping piston within a single spool wherein the pumping spool end terminates with an additional piston for fluid suction, pump priming and control of pressurization during pumping by virtue of differential pressure area in pumping surfaces including the incorporation of appropriately selected and oriented seals offer means of extreme simplification of pump design subject to the present invention.

These and other objects and advantages of the invention will become fully apparent from the following description of the embodiment of the invention taken together with the accompanying drawing.

In the drawing:

The figure illustrates cross sectional view of the device embodying the invention and representing a positive displacement pump of this invention.

Shown in the figure is the position of the pump prior to its actuation. In the figure is a pump body 10 of tubular configuration and having a continuous central bore 11 symetrically oriented over end closures 13 and 14 and provided with tube end threads 12-a and 12-b for an easy assembly with said closures. The end closure 13 constitutes pump end and is provided with a central fluid entrance port 15 providing fluid communication between the reservoir (not shown) and the pump chamber 16. The end closure 14 constitutes actuator end and is provided with a central hole 17 external end of which is threaded to receive screw adustment 20, and internal end of which is provided with an enlarged bore 18 for housing the suction cup 19. A port 21 provides actuating fluid communication with piston assembly 22 inside the pump body 10 for subsequent pressurization and subsequent shift of piston assembly 22 toward pump end closure 13 to result in pumping and fluid exhaust via pump exit port 33 provided therein. Threaded boss 13-a at the closure end 13 provides means for pump mounting to a tank. The piston assembly 22 comprises a spool 23 of the diameter equivalent to the diameter of the tubular bore 11, said spool provided with a symmetrical piston 24 at one extremity of spool 23 and opposing piston 26 at the other extremity of spool 23, and a third piston 28 of smaller diameter attached to piston 26, including a reduced size detachable piston 29 secured by threaded connection to piston 24, all pistons provided with appropriate seals.

Piston 24 is exposed to the actuating fluid pressure and provides driving energy to the pump. Piston 26 including piston 28 are exposed to the pumping media. The area of piston 24 less the area of detachable piston 29 at one end of spool 23 when exposed to the actuating fluid constitutes the net force available for pumping media at the other end of spool 23. This actuating net force provides pressure energy to the area of piston 26 of spool 23 less area-piston 28. By reducing the diameter of piston 26 a condition can be obtained in which the pumping media will be boosted in pressure in proportion with decreasing diametral area due to the net force availability across smaller area, and in accordance with the following equation: A P =a p where A, is actuator net area available P is actuating fluid pressure A P =Available net force a is pumping net area p is pressure at pumping surface or net area and A P pressure increase potential over smaller a2 pumping area (not illustrated in the figure).

Seals 25, 27, and 30 are of U-cup configuration. Seal 31 could be of O-ring configuration.

Seal 25 is mounted over piston 24 with U-channel facing high pressure working fluid (same is actuating fluid) to facilitate improved sealing affect as a result of U- channel expansion and improved sealing with increase of pressure, the characteristics inherent in seals of U-cup configuration.

The same pertains to seals 27 and 30, each of which is mounted over its respective piston to face high pressure region of its respective media for improvements in sealingduring pressure increase within pressurized chamber subject to seal.

A bleeder hole 32 placed into pump body for the purpose of allowing air escape during piston actuation serves very useful dual purpose by also permitting identification of possible failure of seals 25 or 27 and thus allowing for immediate remedy of pump failure.

Screw adjustment comprises a long threaded stud 20-a one end of which terminates with a shouldered stub 20-12 of larger diameter, and the other end of which is provided with a slot 20-0 to receive a screw driver, normally, employed for turning threaded connections within their seats. Locking nut 34 secured over the slotted stud end provides the means for locking screw adjustment in any position along its threaded length within said threaded portion of central hole 17 of the end closure 14. Thread washer 34-a entailing appropriate thread seal is employed to facilitate proper seal of bore 18. Suction cup 19 is provided along its length with a central bore 19-a which terminates with hole 19-b of small enough size to clear threaded stub 20-0. Shouldered stub 20-h is slidably received within bore 19-a of suction cup 19 and acts as a stop during the forward travel of the piston assembly 22 upon its actuation by the working fluid.

Seal cap 35 is provided to cover said screw adjustment 20 and to prevent tampering with preset adjustment during pump operation as well as to facilitate extra sealing of threaded connections of screw adjustment 20 in case of failure of washer 34-a to insure proper seal of bore 18 during pumping.

This invention is not restricted to the slavish imitation of each and every one of details described above which have been set forth merely by way of example with the intent of most clearly setting forth the teachings of the invention. Obviously, devices may be provided which change, eliminate, add certain specific structural details without departing from the spirit of this invention.

What is claimed is:

1. A penumatic/hydraulic pressure actuated positive displacement pump for delivering exact amounts of fluid pumped regardless of fluid state, be it ultra pure liquid, viscous grease or aerated eggnog, in volumetric flows controllable by adjustment, comprising a tubular pump hous ing having a central bore means along its entire length and with threaded ends at each extremity, a piston assembly slideably received within said tubular housing, including end closures, said end closures incorporating threaded connections to fit pump housing ends and comprising the pump actuating end at one pump end, and the pumping end at the other pump end, the actuating and the pumping ends provided with fluid communication ports for pump energization, for fluid pumped entering and leaving pumping end and for screw adjustment, said piston assembly dividing the interior of pump housing bore means into an actuating end for contact with working fluid creating pressure energy for pumping end, and a pumping end in communication with fluid pumped for dispersing said fluid via exit ports provided therein, said pumping and .Said actuating ends sealed from each other by appropriate seals, each pump end provided with one large and one smaller piston in which large piston assumes dimensions of housing bore whereas smaller piston axially attached to the central portion of large piston enters bore of the closure end respectively with seals of appropriate sizes to provide close relationship within said bores and to aid in pumping and in operating pump during piston shift upon application of working fluid into the actuating pump end whereby small piston on one side of pump end slidably received in the end closure of actuating pump end acts as a suction cup upon each pump stroke returning piston assembly to the original position as a result of suction energy created therein, and the small piston on the other side of pump end slideably received in the pumping end of the pump acts as a plug for the fluid entrance port aiding in fluid pressurization and fluid dispersion via exit port, doing so in conjunction with the pumping action of the large pumping piston, said suction cup provided with central bore for receipt of a shouldered stub of the screw adjustment stud, said screw adjustment stud threaded along its length and inserted into the threaded portion of stationary actuator end, said screw adjustment provided with a seal washer and a lock nut easily accessible for change of adjustment and for sealing said adjustment with a seal cap provided therein.

2. A pump as in claim 1 including means for pump reciprocation through working fluid supply and exhaust means in said housing end closure of the pump actuation end having oif-set port, and in the pumping end closureend having an off-set hole for fluid exhaust means of fluid pumped, means for air relieving between said large piston seals, said air relieving comprising a vent hole in the said tubular pump housing member receiving said large piston of close relationship the said bore of said tubular housing member, appropriate seals wherein said large diameter piston receives two opposing each other seals located at piston extremities and oriented so as to facilitate improved sealing upon application of pressures during pump operation, said third piston of smaller diameter provided with identical seal as the seals of the larger diameter piston and preferably all seals of U-cup configuration with U-channels facing said pressure and thereby offering the inherent seal property to expand with pressure improving sealing characteristics during the pumping while affording little friction upon removal of the working fluid from said fluid supply ports via said exhaust port means while said piston assembly returns to the original position for pump filling as a result of the suction force provided by said suction cup assembled thereto and provided with seals preferable of O-ring configuration.

References Cited UNITED STATES PATENTS 2,486,617 11/1949 Soberg 417-378 2,562,584 7/1951 Soberg 417-378 ROBERT M. WALKER, Primary Examiner

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