Booster

Abstract

Pressure booster having a reciprocable pumping piston incorporating significantly improved control valves continuously maintained in an "alive" condition under the bias of supply fluid in either of two stroke limit positions depending upon the direction of piston movement.

Description

This invention generally relates to pressure boosters and particularly concerns boosters of a type usable in a fluid system wherein fluid under supply pressure is used to provide a driving force to deliver a portion of the same fluid in predetermined quantities at increased pressures.

A primary object of this invention is to provide an improved pressure booster having a minimum number of different parts and which has no need for the customary external valve controls normally associated with devices for increasing pressure of delivered fluid.

Another object of this invention is to provide an improved pressure booster virtually free of the troublesome problems of dead center stalling.

A further object of this invention is to provide a pressure booster of the type described which is capable of automatic continuous delivery and which is particularly suited for miniaturized applications.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

A better understanding of the invention will be obtained from the following detailed description and the accompanying drawing of an illustrative application of the invention.

In the drawing:

FIG. 1 is a side view, partly in section, showing a pressure booster incorporating this invention with its pumping piston in a first position;

FIG. 2 is a side view, partly broken away and partly in section, showing the pumping piston in a second position; and

FIG. 3 is a reduced isometric view showing a contoured outside surface of the pressure booster cartridge.

Referring now to the drawing in detail wherein a preferred embodiment of this invention is illustrated, a pressure booster having a generally tubular cartridge body 10 is shown inserted into a cylindrical opening 12 of a body 14. The booster is maintained in a fixed position within the opening 12 by a suitable retaining ring 16. Opposite ends of the booster respectively communicate with an inlet passage 18 and a drain passage 20. In short, the booster is designed to step-up pressure of a portion of fluid supplied from the inlet passage 18 and to discharge that fluid under increased pressure at a controlled flow rate into an output passage 22 in the body 14.

The cartridge 10 has a contoured sidewall preferably provided with a plurality of lands 24 spaced apart by a circumferentially extending groove 26 intersecting a pair of longitudinal grooves 28, 28', the grooves 26, 28 and 28' providing passages constituting a portion of the output means for directing high-pressure fluid to the passage 22. To facilitate insertion of the cartridge 10 into a blind opening, e.g., while still ensuring direct communication between the high-pressure passages and the output passage 22, the longitudinal grooves 28, 28' preferably extend axially of the cartridge 10 a distance greater than one-half its length but less than the total cartridge length. Thus, if the circumferential passage 26 is misaligned relative to the output passage 22, the cartridge 10 need only be rotated to register a longitudinal passage 28 or 28' with the output passage 22.

The cartridge 10 has an internal necked-down central portion providing a pair of annular shoulders 30, 30'. A sleeve 32, 32' is fixed within each end of the cartridge 10 between one of the shoulders 30, 30'. Hollow plugs 34, 34' are respectively fitted within sleeves 32, 32'. Each plug 34 has an outwardly directed radial flange 36 abutting its sleeve 32. Each sleeve extends axially toward an end of the cartridge 10 from an inwardly directed radial flange 38 and surrounds a portion of its respective plug 34 in spaced concentric relation. Each sleeve 32 is fixed between its plug 34 and shoulder 30 by an end cap 40 threadably connected to an axial end of the cartridge 10 to readily clamp the plug and sleeve subassemblies in assembled relation. If desired, a suitable screen 42 may be interposed between each end cap 40 and the cartridge 10, and the threaded cap 40, e.g., may be provided with suitable holes such as 43 to permit the cap 40 to be readily tightened onto the cartridge 10 by a face spanner-type wrench, not shown.

The spaces concentric relation of each plug and sleeve subassembly provides flow passages 44, 44' communicating through suitable radial openings 46, 46' in the plugs 34, 34' and holes 48, 48' in the sleeves 32, 32', respectively, with compression chambers 50, 51 within the plugs 34, 34' and circumferential recesses 52, 52' extending about the sleeves 32, 32'. Ports such as at 54, 54' are formed in the longitudinal passages or grooves 28, 28' of the cartridge 10 to connect the compression chambers 50, 51 with the output passage 22 via the flow passages 44, 44'. Unintended fluid leakage between the cartridge 10 and each plug and sleeve subassembly is preferably minimized by O-ring seals as at 56, 58 extending around grooves in the sleeves 32, 32' and plugs 34, 34'.

Received for reciprocating rectilinear movement within the cartridge 10 is a one-piece double-acting differential piston 60. The piston has a low-pressure central operating section 62 received in a main central chamber 64 between the plug and sleeve subassemblies. The operating piston section 62 divides the main chamber 64 into first and second pumping compartments 66, 68. Coaxially extending from opposite sides of the operating piston section 62 are a pair of elongated tubular pressure pistons 70, 72 of reduced size. The pressure pistons 70, 72 have necked-down tubular extensions 74, 76 received, respectively, within the plugs 34, 34'. Each plug 34 has a pair of circular bearing surfaces such as at 78, 80 at opposite ends of their compression chambers 50, 51 to effect sliding and radial bearing support for the pressure pistons 70, 72 and their tubular extensions 74, 76.

To provide a pulsating delivery of fluid at increased pressure to the output passage 22 in accordance with this invention, but without the customary complex auxiliary external valve controls normally associated with devices of this type, a pair of control valves 82, 84 are supported for free floating movement in the operating section 62 of the piston 60. The control valves respectively serve as an actuating valve 82 and an exhaust valve 84 to automatically effect changeover of the fluid supply and exhaust connections to the pumping compartments 66 and 68 of the main chamber 64 at opposite ends of the operating piston section 62 and to reciprocate the piston 60 responsive to a demand imposed on the booster by the fluid system.

The freely floating valves 82, 84 are supported for sliding reciprocable movement within a pair of diametrically opposed openings 86, 88 extending through the operating piston section 62. The openings 86, 88 extend in parallel relation to axial openings 90, 92 in the pressure pistons 72, 70 and are respectively connected to the axial openings 90, 92 through passages 94 and 96. Passages 90, 94 comprise a supply passageway within the piston 60, and passages 96, 92 comprise an exhaust passageway within the piston 60.

Suitable snap rings 98, 100 are fixed to the piston 60 in spaced adjacent relation to each end of its operating section 62 to secure a pair of washers 102, 104 providing common stops establishing first and second stroke limit positions for the valves 82, 84 as illustrated, respectively, in FIGS. 1 and 2 of the drawing.

With the valves 82, 84 in their first stroke limit position (FIG. 1), supply fluid under line pressure is directed through the supply passageway 90, 94 by the actuating valve 82 to the first pumping compartment 66 and into compression chamber 50 through a pressure loaded check valve 106. The second pumping compartment 68 is simultaneously exhausted by the other valve 84 via the exhaust passageway 96, 92 formed in the piston 60 to direct fluid into the drain passage 20. The resulting differential pressure in the first and second pumping compartments 66, 68 drives the piston 60 from right to left (as viewed in the drawing), and pressure piston 70 compresses fluid within compression chamber 51 to force the compressed fluid through a second pressure loaded check valve 108' into recess 52' and port 54' leading to the output passage 22. The pressure loaded check valves 106, 106' and 108, 108' in each of the sleeve and plug subassemblies are shown comprising a pair of O-rings respectively biased against annular faces formed on the sleeves 32, 32' by a series of thin wave washers such as at 110, 112 seated against radial shoulders 114, 116 formed on the plug 34. It will be seen that with increased fluid pressures, the pressure loaded check valves 106, 108 improve the sealing of the flow passage 44 against reverse flow of fluid.

As the piston 60 approaches sleeve 32', the valves 82, 84 are mechanically deflected in synchronism upon striking the end of the sleeve 32' which serves both as an abutment to positively deflect the valves 82, 84 as well as a stop for the piston 60. As the valves 82, 84 are deflected into their second stroke limit position (FIG. 2), the supply and exhaust passageways 90, 94 and 96, 92 in the piston 60 are automatically changed over to opposite pumping compartments of the main chamber 64, reversing the pressure differential on the operating piston section 62 to thrust the piston 60 in the opposite direction. The supply fluid under line pressure is then directed from the second pumping compartment 68 into compression chamber 51 while the fluid in compression chamber 50 is stepped-up in pressure by the advanced of its pressure piston 72 and forced from the flow passage 44, past the check valve 108 and into the high-pressure passages 26, 28, 28' through the ports 54 to be directed to the output passage 22 of the fluid system. The fluid in the high-pressure passages, of course, remains trapped against reverse flow into the other flow passage 44' by the check valve 108' which is pressure loaded against unintended opening by both the thin wave washers 112' and the trapped fluid in the high-pressure passages.

It will now be seen that fluid under line pressure provides the driving force for delivering a portion of the same fluid at an increased pressure level and reduced flow rate. The booster will automatically pump until it has either satisfied the requirements of the demand imposed on the booster by the fluid system or until the booster has reached an equilibrium pressure which is a function of the maximum flow the booster can pass through an external restriction, e.g., at a point downstream in the output passage 22. The booster will then automatically stop and remain on standby until an additional demand is called for by a pressure drop in the output passage 22.

The above described booster virtually eliminates any possibility of dead center stalling of the piston 60 and valves 82, 84 in a neutral position. For example, if the valves 82, 84 were by chance positioned dead center in the operating piston section 62 under operating conditions permitting flow through the output passage 22, the application of supply fluid under line pressure would automatically move the piston 60 to the left, forcing fluid in the second pumping compartment 68 into the flow passage 44', either through the check valve 106' or between the pressure piston 70 and its plug bearing surface 78'. The piston movement would continue until the valves 82, 84 were positively deflected to the right by the sleeve 32'. Thereupon the pumping cycles would resume as previously described until the requirements imposed by the fluid system on the booster have been met.

Assuming dead center positioning of the piston 60 and valves 82, 84 under a no-flow condition in the output passage 22, the application of supply fluid under line pressure would initially move the piston 60 a discrete distance to the left whereupon the unbalanced pressures created in the pumping compartments 66, 68 would result in an overriding force in the second pumping compartment 68 to positively deflect both valves 82, 84 to the right into their second stroke limit positions whereupon the piston 60 would return to the right to its limit position, and the automatic pumping cycles would resume with a pulsating equal spill of pressurized fluid into the output passage 22 occurring during each pumping stroke of the piston 60.

By virtue of the freely floating valves 82, 84 carried by the operating piston section 62, the pressure differential in the pumping compartments 66, 68 will continuously maintain the two valves 82, 84 in synchronism and fully deflected substantially throughout the entire stroke length of the piston 60.

In addition, an automatic valving action is effected without any need for the conventional external auxiliary controls normally required and associated with devices of this type. To the contrary, all elements including the control valves 82, 84 are contained within the confines of a single tubular cartridge. The pressurized fluid in the output passage 22 can be used, for example, to deliver a high servo pressure while being supplied from a relatively low-pressure source. The illustrated booster has been designed to operate up to 720 pumping strokes per minute and to deliver to the output passage 22 approximately 1/10 of the total flow of fluid passing through the booster and to deliver that fluid at a high ratio of pressure increase, say, between 9 and 10 times the line pressure of the supply fluid.

From the foregoing it will be seen that the present invention provides a pressure booster that may be relied upon over long periods of repeated and rugged use with minimal service requirements. The booster incorporates only a minimum number of different parts and has been economically manufactured even in extremely small sizes having, for example, an overall cartridge length of about 1.00 inch, an outside diameter of 0.50 inch and a total valve stroke length of approximately 0.06 inch. Moreover, the described booster not only provides significantly improved control valves 82, 84 carried on the operating piston section 62 to control timing of the pumping action and shiftable by piston movement, but also overcomes the heretofore troublesome problem of sticking valves since the valves are continually "alive" under the bias of supply fluid, whereby dead center stalling is virtually eliminated by simple applying inlet pressure to the booster.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

Claims

I claim:

1. An automatic pressure booster usable in a fluid system and comprising a body having a main chamber and a compression chamber at each end thereof, a differential piston having an operating section reciprocable in the main chamber and a pressure section at opposite ends of the operating section reciprocable in the compression chambers for increasing the pressure of fluid supplied thereto from the main chamber, supply means and exhaust means for the main chamber formed in the piston, and valve means in the supply means and exhaust means shiftable between first and second stroke limit positions by the advance of the piston to automatically reverse its movement, the valve means being carried by the piston and maintained by a fluid bias in the last position to which the valve means was shifted during piston movement in a selected direction.

2. The booster of claim 1 further including abutment means fixed in the body for contact engagement with the valve means responsive to piston movement for shifting the valve means in synchronism between the first and second stroke limit positions for controlling piston reciprocation.

3. An automatic pressure booster usable in a fluid system and comprising a body having a main chamber and a compression chamber at each end thereof, a differential piston having an operating section reciprocable in the main chamber and a pressure section at opposite ends of the operating section reciprocable in the compression chambers for increasing the pressure of fluid supplied thereto from the main chamber, supply means and exhaust means for the main chamber formed in the piston, the piston carrying stops for establishing first and second valve stroke limit positions, and valve means received in the piston in its supply means and exhaust means shiftable between the first and second stroke limit positions by the advance of the piston to automatically reverse its movement, the valve means being received in the piston in free floating relation for reciprocating rectilinear movement between the stops in a direction parallel to an axis of movement of the piston, and the valve means being maintained by a fluid bias in the last position to which the valve means was shifted during piston movement in a selected direction.

4. An automatic pressure booster usable in a fluid system and comprising a body having a main chamber and a compression chamber at each end thereof, a differential piston having an operating section in the main chamber and a pressure section at each end of the operating section, the pressure sections being in the compression chambers and of reduced size relative to the operating section, the piston being reciprocable in the body for supplying fluid from its main chamber to the compression chambers, supply means and exhaust means for the main chamber formed in the piston, and valve means carried by the piston and connecting the supply means and the exhaust means respectively to the main chamber at opposite ends of the operating piston section, alternatively, to effect piston reciprocation.

5. The booster of claim 4 further including check valve means between each compression chamber and the main chamber, the check valve means being operable responsive to a predetermined pressure to alternately establish communication between each compression chamber and the main chamber.

6. The booster of claim 4 further including an output passage communicable with each compression chamber, and pressure operated check valve means for each compression chamber for alternately connecting it with the main chamber and output passage responsive to movements of the piston in opposite directions, while continuously preventing reverse fluid flow through the compression chamber from the output passage to the main chamber.

7. The booster of claim 4 wherein the body comprises a tubular cartridge insertable in a fluid passage of the fluid system, a plug positioned at each axial end of the cartridge to provide radial bearing support for the piston, the plugs and the piston jointly defining the chambers within the body, and an apertured end cap threadably secured at each axial end of the cartridge maintaining the components in assembled relation.

8. The booster of claim 4 wherein the body comprises a tubular cartridge insertable in a fluid passage of the fluid system, and wherein the cartridge includes a sidewall having grooves formed in its external surface to provide recesses and lands, the recesses having outlet ports formed therein in communication with the compression chambers.

9. The booster of claim 6 wherein the check valve means for each compression chamber comprises a first O-ring between the main chamber and the compression chamber and a second O-ring between the compression chamber and the output passage, the O-rings each being biased to prevent reverse fluid flow while permitting fluid flow from the main chamber to the output passage through the compression chamber responsive to a predetermined fluid pressure.

10. The booster of claim 8 wherein one of the recesses extends at least in part axially of the cartridge a distance greater than one-half its length.

11. An automatic pressure booster usable in a fluid system and comprising a body having a main chamber and a compression chamber at each end thereof, a differential piston received for reciprocable movement in the body and having an operating section and a pair of pressure pistons respectively in the main and compression chambers, check valve means between each compression chamber and the main chamber, the check valve means being operable responsive to a predetermined pressure to alternately establish communication between each compression chamber and the main chamber, fluid output means communicable with each compression chamber, fluid supply means, fluid exhaust means, and valve means in the operating piston section for connecting the fluid supply means and exhaust means to the main chamber at opposite ends of the operating piston section respectively, the valve means being shiftable with the piston for automatically effecting changeover of the fluid connections to the main chamber at opposite ends of the operating piston section.

12. The booster of claim 11 wherein the valve means includes first and second valves carried by the operating piston section and received in the supply means and exhaust means for movement between first and second stroke limit positions wherein the supply means and exhaust means are respectively connected to the main chamber at opposite ends of the operating piston section, alternately.

13. The booster of claim 11 wherein the output means includes grooves formed in a side wall of the cartridge to provide recesses and lands, and outlet ports formed in the recesses in communication with the compression chambers.

14. The booster of claim 11 wherein the body comprises a tubular cartridge insertable in a fluid passage of the fluid system, wherein the supply means and exhaust means respectively include passages extending axially through the pressure piston sections in constant open communication at the axial ends of the piston for establishing fluid supply and drain connections, and wherein the output means includes outlet ports formed in a cartridge sidewall in communication with the compression chambers.