US1828056A - High pressure pump piston - Google Patents

Description

' Oct. 20, 1931. l c. LAMB HIGH PRESSURE PUMP PISTON Filed Sept. 26. 1927 v/z R V r v .fMx/EMTOB (Dew/e1. E5 4 67MB Patented ea. 20, -1931 CHARLES LAMB, OF LOS ANGELES, CALIFORNIA, ASSIGNOR OF ONE-HALF TO M. G. BRUMB'LY, 0F WALNUT PARK, CALIFORNIA HIGH IEREISSUIRE PUMP PISTON Application filed September pumps handling fluids which carry abrasive sequently if the pump is in operation for but a short time the piston becomes worn soithat it is very ineflicient. In order that the pump operate efliciently, it is'necessary at frequent intervals to mechanically adjust the piston into proper working contact with the cylinder of the pump.

One of the objects of my invention is to provide a pump piston which is self-adjustin tamed in proper contact with the cylinder of the pump. I have found that the initial wear on the pump piston is at the ends thereof and works toward the center. I have also found that if the ends of the piston are al ways in proper contact with the cylinder that the central part will not be subjected to wear. In accordance with these findings I have constructed a pump piston formed of a resilient material, such as rubber having a central part which is adapted to be forced into pressural engagement withthe cylinder'by a mechanical adjustment and having end portions which areretained in proper working contact with the cylinder by hydraulic pressure in the cylinder ends.

It is accordingly one of the objects of this invention to provide a piston in which thecentral portion is mechanically held in engagement withthe cylinder and the end portions are hydraulically held .in engagement with thecylinder.

If the rotary fluid or slush which is handled by the pump is allowed to come into direct contact with the ends of the rubber pis-- ton, the ends thereof will be rapidly worn and which will automatically be main- 26, 1927. Serial No. 22,171.

away and the life of the piston will be very short.

It is an object ofthis invention to provide a pump piston in which the rubber body will Fig. 2 is a cross section of the piston of my invention before it isv inserted into the pump cylinder.

- Fig. 3 is a cross section similarto Fig. 2 showing the pump piston inserted into a pump cylinder.

' Fig. 3.

Referring in detail to the drawings and particularly to Fig. 1, the slush pump has a driven end 11 in which the rotary fluidor slush is handled and a drive'end 12.- The driven or slush end of the pump has a cylinder 13 in which the piston 14 embodying the features of my invention is adapted to be reciprocated. The piston 14 is attached to a piston rod 16 which extends outward from the cylinder 13 througha suitable gland 1-7 This rod 16 extends to the drive. end of the slush pump where it is caused to reciprocate..

Referring to Figs. 2 to 4, the details of the invention will be described. The piston 14 of the invention provides a resilient piston body 20. This body 20 ispreferably made Fig. 4: is a sectiontaken on the line 44 of of a rubber or rubber composition having good wearing qualities. Formed through the center of this resilient piston body 20 is a tapered opening 21 through'which a tapered and is formed. of a mabe protected from direct contact with the sition known as Whalite.

terial which is harder and tougher than the material forming the other part of the resilient piston body. In actual practice I form this reinforcement of a rubber compo- It should be understood that any other suitable material may be substituted. v

The central portion of the resilient iston body 20 is cylindrical and is of suc av diameter that this' ortion may be moved into the cylinder 13 wit out requiring it to be constricted or with but a minimum of constriction. The end portions of the resilient piston body 20 are provided in the form of end lips 26. These end lips 26 are conical and are largest in diameter at their outer ends. These end lips 26 are formed so that they are normally of a larger diameter than the diameter of the cylinder 13, so that when the piston 14 is inserted in the cylinder 13 the end lips must be forced inward or constricted.

Formed at the ends of the resilient piston 16,- and the other plate 29 is provided with a hub 31 which is engaged by a. nut 32 adapted to be screwed onto a threaded portion 33 of the rod. The plates 29 have inner faces 35 which are adapted to contact end faces 36 of the resilient piston bod 20. The end plates 29 are but slightly sm er in diameter than the cylinder 13. It is preferable to have the end plates 29 about one-sixteenth to oneei hth of an inch smaller in diameter than the cylinder 13. -The end plates cover the annular channels 27 and are provided wlth openings 39 which connect to. the annular channels 27 so that fluidmay pass thereinto. Projecting inward from the inner faces 35 of the end plates 29 are compressing means in the form of compressing rings 40. These compressing rings 40 extend into annular cavities 41 which are formed in the opposite ends of the resilient piston body 2 around the reinforcement 23. The inner faces 42 of the compressing rings 40 are made conical, as illustrated, for the purpose of pressin the hub ends 44 ofthe resilient piston b0 y 20 (which are provided by forming the body 20 with the annular cavities 41) .inward into fluid-tight contact with the tapered portion 22 of the rod 16.

In Fig. 2 the piston 14 is shown assembled on the rod 16 before it is inserted in the cylinder 13. The left end of the body resilient material 20 must be mechanically constricted so that it will enter the cylinder 13. When this is done, the piston is moved into the cylinder 13 so that only the nut 32 is accessible. The nut 32 is then screwed onto the threaded portion'33 and the parts are moved into the posltlon shown in Fig. 3. In the .first place, it will be seen that'the end lips 26 pressurally englage the-cylinder 13,. due to the fact that t ey are constricted when the piston 14 is inserted. When the nut is screwed up and the plates are forced together, the entire resilient piston body 20 is placed under compression. The result is that the end faces 36 of the resilient piston body are moved together so that the inner portion of the resilient piston body is moved inward into fluid-tight contact with the tapered portion 22 of the rod 16, and the central portion 25 of the resilient piston body 20 is forced outward into pressural contact with the cylinder 13. The compressing rings 40 assist in compressing the resilient pistonbody, for

the most part forcing the hub ends 44 inward into fluid-tilght contact with the tapered portion 22 of t e rod 16. a

When the pump, is set into operation, the pump piston-14 is= reciprocated and a fluid pressure is alternately built up in opposite ends of the cylinder 13. When the piston is moving to the left, the fluid premure is on the left side thereof. The fluidunder pressure will pass through the openings 39 in the left end plate 29 and into the left annular channel 27. This fluid under pressure forces outward on-the left end lip 26 and maintains it in fluid-tight contact with the cylinder 13. When the piston 14 is initially installed, the pressure of the end lips, due to their being constricted, is suflicient to maintain a fluidtight engagement, but when the end lips become worn this engagement is not so strong due to the constriction of the end lips, but the fluid pressure makes up for this and preservesa fluid-tight engagement. By always maintaining the end lips in fluid-tight contact, practically no abrasive will get to the central portion 25 and wear it away. For this reason the wear at the central ortion 25 will not be very great and mechanlcal adjustment will not be r uired.

By extending the en plates 29 outward so as to cover the ends of the resilient piston body 20, they are protected from the abrasive fluid carried by the slush pump and will not be worn'awa-y as they would were these ends exposed. In practice I find that the best protection is procured when the end plates are but slightly smaller in diameter than the cylinder 13. This is particularly true where a very high pressure of the fluid must be obtained. Of course, ,where the pressure is lower the wear on the resilientpiston body 20 is not so great and it will not be necessary to extend the end plates 29 out so far. Since the annularchannels 27 are covered by the end plates 29, the openings 3 9/are provided.

In the drawings I have shown a preferred form of the invention for high pressure pumps. In pumps of lower pressure the design shown is not necessary and a cheaper construction may be provided. For example,

IOI

'aeeaose the end plates 29 may be made much smaller in diameter than the cylinder 13, and the compressing rings 40 may be eliminated. Where the pressure is very high it is quite essential that a fluid-tight engagement be maintained between the resilient iston body 20 and the tapered portion 22 0 the rod 16 so that no fluid will leak therethrough, since if anyfluid leaks therethrough a passage is soon worn through the resilient piston body and it is ruined.

In the construction herein disclosed, the entire body of the piston comprises a composite resilient body which is applied directly to the piston rod or shaft between two end plates, one of which is stationary and the other of which is axially adjusted upon the rod to compensate for wear of the piston. Such take-up for wear may be efi'ected from time to time without removing the piston from the cylinder, by merely tightening up the nut 32, this progressive tightening up of said nut being possible since the adjustable end plate 29 does not .at any time engage any abutment shoulder. i

The tougher core portion 23 of the composite piston body is of particular advantage in that it produces a more firm grip of the piston body upon the piston rod than if the entire body were made of softer rubber, and it also provides the piston rod bore 21 with a more substantial wall surface which is less liable to injury due to careless or hurried installation.

The annular grooves on each side of the piston body 20 may be defined as an'outer primary channel 27 and an inner secondary channel 41, the primary'channel 27 defining an outer peripheral lip 26, the secondary channel 41 defining a hub end 44, and both channels defining an inneror secondary lip 45. With a piston body of this character the relative compressing movement of the end plates causes the rings 40 to exert an inward radial compressing force upon the hub ends 44 so that said hub ends firmly grip the piston rod and provide an effective seal against leakage of fluid through the bore of the piston. The secondary lip 45 is of particular value since under the influence of the pressure in the primary or pressure channel 27 said lip 45 grips the ring 40 and forms a seal against leakage of the fluid inwardly along the end plates.

I claim as my invention:

1. In combination: a piston rod; a piston consisting of a composite resilient piston body mounted directly on said rod, said body having a relatively-harder and tougher annular core surrounding said rod, said core being diametrically enlarged intermediate its ends; end plates engaging opposite ends of said piston body; and means for causing rel ative movement of said plates towards each other to axially compress and radially exadapted to operate, and to further axially compress and radially expand said resilient body to compensate for wear.

2. In combination: a piston rod; a piston consisting of a resilient piston body mounteddirectly on said rod, the opposite end walls of said body having formed therein an outer concentric channel defining an outer peripheral lip and an inner concentric channel defining an end hub; end plates engaging opposite ends of said; piston body, each plate having a concentric flange extending inwardly into the companion inner channel of said body to confine the adjacent end hub thereof and each plate being of suflicient diameter to cover the respective outer channel of said body and thereby form an annular pressure chamber, there being in each plate passages communicatin with the respective pressure chamber and t e exterior of said piston; and

means for causing relative movement of said end plates towardseach other whereby the resilient. piston body will be axially compressed and radially expanded to working contact with the wall of'a cylinder in which it is adapted to operate, and to further axially compress and radially expand said resilient body to compensate for wear, said compression causing the plate flanges to clamp the end hubs of said body upon the piston rod.

3. In combination: a piston rod; a piston consisting of a composite resilient piston body having a relatively harder and tougher annular core mounted directly on said rod, the opposite end walls of said body each hav-' ing formed therein an outer concentric channel defining an outer peripheral lip and an inner concentric channel defining an end hub; a relatively stationary end plate engaging one end of said piston body; a relatively movable end plate engaging the opposite end of said piston body, each end plate'having a concentric flange extending inwardly into the fine the adjacent end hub thereof and each plate being of sufficient diameter to cover the respective outer channel of said body and thereby form an annular pressure chamber, there being in each plate passages communicating with the res ective pressure chamber and the exterior 0 said piston; and means cooperating with said piston rod to urge the movable end plate towards the stationary end plate whereby the resilient piston body will be axially compressed and radially expanded to working contact with the wall of a cylinder in which it is adapted to operate, and to further axially compress and radially expand said resilient body to compensate for wear, said compression causing the plate flanges to clamp the end hubs of said body upon the piston rod.

companion inner channel of said body to con- 4. In combmatmn: a piston rod; a piston consisting of a composite resilient piston body having a relatively harder and tougher core mounted directly on said rod, the opposite end walls of said body having formed therein an outer concentric channel defining an 'outer peripheral lip and an inner concentric channel defining an end hub; end lates engaging opposite ends of said piston ody, each plate having a concentric flange extend- 1 ing inwardly into the companion inner channel of said body to confine the adjacent end hub thereof and each plate being of sufiicient diameterto cover the respective outer channel of said'body and thereby form an annu- 15 lar pressure chamber, there being in each plate passages communicating with the respective ressure chamber and the exterior of said piston; and means for causing relative movement of said end plates towards 20 each other whereby the resilient piston body will be axially compressed and radially expanded to working contact with the wall of a cylinder in which it is adapted-to operate,

' and to further axially compress and radially 25 expand said resilient body to compensate for wear, said compression causing the late flanges to clamp the end hubs of said ody upon the piston rod. Y 5. A pistoli body comprising a cylindrical body of resilient material having an axial bore adapted to receive apiston rod, the end walls of said body each being formed to provide an outer concentric primary channel defining an outer peripherallip and an inner conceritric secondary channel defining an end hub, both channels defining an intermediate concentric secondary lip.

6. A piston body comprising a cylindrical composite tubular body of resilient material having a relatively harder and tougher core surrounding the bore thereof, the end walls of said body each being-formed to provide an outer' concentric primary channel definingan outer peripheral lip and an inner concentric, secondary channel defining an end hub, both channels defining an intermediate concentric secondary lip,

7. A cylindrical tubular composite resilient piston body having axially disposed hubs at its opposite ends and provided with a relativel harder and tougher annular core surroun its bore throughout the length of said he y andits end hubs;

8. A cylindrical tubular composite resilient piston body havin an outer annular portion of relatively resllie'nt, material and an inner coreof harder material, there being a shaft opening throughjsaid core, said core beiplglenlarged intermediate its ends so that it grip a shaft on which it'is placed when axial pressure is laced on said core.

In testimon w ereof, I have hereunto set my hand at Angeles, California, this 17th dayof September 1927. r v t CHARLES LAMB.

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