US2461235A

US2461235A - Fluid pressure energy translating device

Info

Publication number: US2461235A
Application number: US689548A
Authority: US
Inventors: Thomas E Raymond
Original assignee: SIMPLEX ENGINEERING Co
Current assignee: SIMPLEX ENGINEERING Co
Priority date: 1946-08-09
Filing date: 1946-08-09
Publication date: 1949-02-08
Anticipated expiration: 1966-02-08

Description

Feb. 8, 1949. 'r. E. RAYMOND FLUID PRESSURE ENERGY TRANSLATING DEVICE Filed Aug. 9, 1946 INVENTOR Thomas E120 BY ymond .v 9 i I ATTORNEY 2 Patented Feb. 8, 1949 FLUID PRESSURE ENERGY TRANSLATING DEVICE Thomas E. Raymond, Zanesville, Ohio. assignor to Simplex Engineering Company, Zanesville,

Ohio

Application August 9, 1946, Serial No. 689,548

This invention relates to fluid pressure energy translating apparatus and is particularly directed to an improved hydraulic pump or motor for use in circuits employing high fluid pressure. This application is a continuation in part of my co-pending application Serial No. 529,957, filed April 7, 1944, now abandoned.

An object of this invention is to provide a pump or motor having a plurality of radially arranged cylinders in which pistons are disposed for move- I, ment, and a centrally located actuating or cooperating member with which the pistons directly engage, the pistons serving either to cause fluid to flow from a reservoir or storage place to a hydraulic system for use therein or to transmit motion to the centrally arranged member when the device is employed as a motor.

Another object of this invention is to provide a pump having a bodywith a central chamber,

and a plurality of cylinders radiating therefrom,v

the pistons being disposed. for movement in the cylinders to withdraw fluid from the central chamber and force it under pressure into a chamber and radiating sockets which open to the exterior of the body to receive cylinder sleeve and piston assemblies which can be individually removed, repaired and replaced without further dismantling the pump.

A still further object consists in providing a pump having a casing with a central chamber and a plurality of cylinders radiating from the chamber and receiving pistons, an eccentric for cooperation with the pistons being carried by a shaft which is journalled in the casing and has a portion projecting from the casing through a. hollow boss formed with the casing, the shaft being formed for connection with a driving member, the hollow boss receiving a mounting sleeve which serves to connect the pump casing to a support and hold the pump shaft in proper alignment with the driving member, thus eliminating strain and incidental coupling noises.

It is also an object to providea novel piston and cylinder sleeve assembly wherein the piston is formed with a passage having a valve seat for engagement by a valve when the piston is moved in a direction to force fluid out of the cylinder and away from the seat when the piston is moved in the opposite direction, the piston having an 14 Claims. (Cl. 103-482) I,

expansible skirt to sealingly engage the cylinder walls and prevent the escape of fluid around the piston during the pumping strokes.

An object of the invention also consists in provlding a piston with a hollow interior which is shaped to form a thin expansible skirt wall, a valve chamber separated from the thin skirt portion by an internal shoulder and passage means extending from the valve chamber to one end of the piston, a ball valve being disposed in the valve chamber to control the direction of fluid flow through the piston and a perforated abutment being engaged with the internal shoulder to limit the movement of the ball valve away from its seat and thus increase the speed of operation of the valve.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of embodiment of the invention is clearly shown.

In the drawings:

Fig. 1 is a vertical longitudinal sectional view taken through a hydraulic pump formed in accordance with the present invention showing the same operatively connected with a driving unit;

Fig. 2 is a vertical transverse sectional view taken on the plane indicated by the line 2-2 of Fig. 1; and

Fig. 3 is a detail horizontal sectional view taken on the plane indicated by the line3--3 of Fig. 2.

In the embodiment of the invention illustrated in the drawings, the pump comprises a circular casing 20 having a body 2| and inner and outer end caps 22 and 23. The caps 22 and 23 are length of the member 26 is such that when it occupies its innermost position in the recess 25, the outer portion of the recess will serve as a chamber 28, closed at its end by the inner end cap 22. .The latter cap also has a recess 29 substantially conforming in diameter to the inner diameter of the member 26. Races 3| of

needle bearings

32 and 33 are-disposed in the recess ;2

and member 26 and these races contain-roller 24 which receive and rotatably support the shaft 35 of the pump. t

and is supplied to the manifold 2'! through an inlet pipe 4| which has a threaded connection 42 with thebody 2|. The pipe I communicates with an inlet port 43 formed in the body 2| and communicating in turn with the inlet manifold 21. The formation of the member 28 provides a wall 44 between themanifold 21 and the chamber, which wall 44 is provided at circumferentially spaced intervals with ports 45 to establish communication between the manifold 21. and

Y the chamber 28. These ports are of suilicient the recesses 46 are reamed to an accurate size while the portions of the cylinder sleeves 4 9 positioned therein may be formed with a slight taper terminating immediately below the threaded portion in a diameter at least one thousandth of an which thecylindersleeves may be inserted and withdrawn.

As mentioned above, the inner portions of the cylinder sleeves are accurately ground and lapped inside to receive, for sliding movement, the hollow piston members Ill. The outer surfaces of the pistons are also ground and lapped. The piston members and the cylinder sleeves form an assembly which may be withdrawn and reinserted without otherwise dismantling the pump.

A coil spring 60 is arranged between the inner end wall 6| of each cylinder sleeve and a perforated abutment plate 62 disposed in the piston 50 against a shoulder 63 formed therein, the coil spring 60 tending to urge the piston out of the sleeve and into the chamber 28. The portion of the piston wall surrounding the spring 6.] is made thin and expansible so that on the working strokes of the piston, the thin skirt-like wall will expand and closely engage the inner surface of the cylinder sleeve thus sealing this junction against fluid flow. On the-return stroke the pistons, not being under any expanding pressure, will return to normal size and slide freely in the sleeves under the influence of the springs 60.

Preferably the pistons are formed of different steel than the sleeves and are heat treated to different hardness than the sleeves for the purpose of minimizing wear and adhesion between the pistons and sleeves. Either the steel of pistons or the steel of sleeves may contain graphite, and in the preferred embodiment, the steel of the pistons contain the graphite.

The sleeves 49 are formed of steel bar stock of as s. A. E. specification No. 4145, heat treated to inch greater than that of the reamed portions I of the recesses. This construction provides a secure seal against fluid leakage around the sleeves. It also serves to compress the sleeves to a limited extent. to secure a better seal between the pistons so disposed for sliding movement in the sleeves l5, and the inner walls of the sleeves. To prevent this compression of the sleeves-from binding the pistons, the inner surfaces of the sleeves are ground while the sleeves are held in a fixture (not shown) under the same conditions whichare imposed when the sleeves are mounted in the body II. In actual practice, it has been found that substantially the same results can be obtained without tapering the sleeve. Preferably the inner surfaces of the recesses 46 are ground and lapped and the outer surfaces of the sleeves 49 are treated in l ke manner so that the sleeves 49 fit snugly within the recesses. This is known in the trade as "ring fitting." When extreme accuracy is desirable, it canbe reduced to zero by selecting sleeves that accurately fit the recesses.

The outer ends of the cylinder sleeves have heads 52 which, in the present instance. are formed with wrench receiving sockets 53 to facilitate threading the cylinder sleeves into the body 2|. Each of the cylinder sleeves is provided with a washer 54 for engagement with a seat 55 formed around the outer end of each socket 41. These washers seal the joints between the cylindersleeves and the body 2| and effectively prevent the escape of hydraulic fluid at these locations.

A channellike ornamental ring 56 surrounds the body 2| and the heads '52 of the cylinder sleeves and serves to protect the heads 52 from injury when the pump is in use. The outer wall of this ring is provided with openings 51 through C. Rockwell after machining. In one embodiment of the apparatus, the exterior of the sleeve 49 is ground to a microfinish of 15 R. M. S., the

diameter being .7505 inch with tolerance of' +.0(l00 andv -.0002 inch. The interior of the sleeve is reemed to .625 inch and honed to .627 inch. The inner surfaces of the sleeves are finished to a microflnish of 10 R.M.S. after honing and held to a tolerance of +.0005 and -.0000

inch. The pistons are formed of the suitable die steel which preferably contains some graphite, and one of the steels that work highly satisfactorily is manufactured by Timken Steel and Tube Division of the Timken Roller Bearing Company of Canton, Ohio, which steel is sold under the trade name of "Graph-Mo." This steel is heat treated to 59 to 61 C. Rockwell and the exterior is microfinished to 10 R. M. S. after honing and held to a tolerance of +.0005 and .0000

inch. The surfaces of the pistons are ground to an outside diameter of .627 inch and honed to an outside diameter of .625 inch. This finished diameter is maintained to tolerances of +1101 and --.000. The inside diameter of outer skirt portion of the 'pistons is .5312 inch and this dimension is held to the tolerance of .005 inch.

Obviously, the tolerances between the outer diameter of the pistons and the inner diameter of the sleeves can be minimized by selecting pistons which have the desired tolerance with respect to the inner diameter of the sleeves.

Obviously the outer skirt portion of the piston can be varied somewhat, particularly when the pistons are made of smaller or larger diameters, however,- it is important to provide for the expansion of the skirt during the working stroke of the piston, and it is also important to limit the degree of expansion of the piston to well within the elastic limit of the steel since it is highly desirable that the pistons contract in the cycle of pump.

the inner end of the valve chamber 84. The seat- 88 and the shoulder 88 are so spaced that the valve 85 will be limitedin its movement away from the seat to the extent necessary to provide sufllcient flow through the piston. Thusin switching from the intake to the compression strokes of the piston, there will be no appreciable time lag in the closing of thevalve and the efficiency of the pump will lie-high. Passages 81 and 88 establish communication between the interior of the piston and the chamber 28. The former, passages 81, extend transversely. of the piston and terminate in ports in the side walls of the piston. A port 88 is also formed in the inner end of the piston 58, this port. registering with an annular groove 18 provided in the outer surface of an anti-friction bearing 'li.

The bearing II is carried by an eccentric enlargement I2 formed on the shaft 88 withinthe chamber 28. This bearing II eliminates the friction which in the absence ofthe bearing, would result when the-eccentric moved from'one side of the longitudinal axis of a piston to the other during the rotation of the eccentric,

thereby-prolonging thev life of the pump. The; elimination-of friction at this point also assistsin reducing the power required to operate the As; illustrated in Figs. 1 and 2, the sockets or recesses 41 are enlarged circumferentially, as at 13, at the inner ends of the threaded portions 48 and. when the cylinder'sleeves are inserted in the body, these enlargements of the recesses cooperate with the cylinder sleeves to form chambers 14 which communicate with the interior of the cylinder sleeves through outwardly ex-, tending channels 15 formed in the threaded; exeterior portions of the cylinder sleeves and through ports 18 extending through the side walls ofthe sleeves. Each chamber I4 communicates with a longitudinally extending passage 'I'I formed-in the body 2|, which passage communicates with an angularly extending passage 18,- the latter terminating in an exhaust or outlet manifold -I8 formed in the outer end face 88 of thebody 2|.

This manifold chamber is closedby the end cap 28, an outlet port 8| being formedcentrally of this cap to permit the flow of hydraulic fluidfrom the outlet manifold. A pipe 82 is threaded into the outlet port 8| to conduct fluid from the pump to the hydraulic system;

The passages are formed by drilling holes into the body 2| from the outer end face 88.

These holes 88 are reduced in diameter between their points of connection with the angular passages I8 and the chambers I4 to provide valve seats 84 for engagement bybaliyalves 88 disposed in the holes 88. These valves are urged into engagement with the seats by coil springs.

Members 88 aeeaass are retained in the body 2| through threaded engagement therewith, each member "having ahead 8| formed with a .wrench socket (not shown). The head 8| engages a washer 82 to prevent the escape of fluid around the threaded portion of the stop member. also positioned between the end cap 28 and the body 2| to prevent the escape of high pressure fluid at the joint the'rebetween.

[The pump 28 is connected .jgr operation by positioning a mounting sleeve 84 on the boss 81 and. connecting the outer end of this mounting sleeve with a support 85 for a driving member 88, this member being splined as at 81 to the shaft 85. In the present instance, the member 88' constitutes the armature shaft of a driving motor and the support 85 constitutes the motor casing. The sleeve 84 is preferablysplit at one side and is clampingly secured to the casing 85 and boss 81 by drawing the spaced. portions of. the sleeve together with clamping screws 88. :A third screw 88 is provided to spread the spaced portions apart when it is desired to remove the sleeve. This method of mounting insures theaccurate regg istration of the pump shaft 85 with the shaft 88 of the driving motor, the latter having a socket in its outer end to receive the end of the shaft 85; If desired, the end of shaft 88 can be formed.

with a socket to receive a nut which in turn has splined connection with the pump shaft 85.

As shown in Fig. 1, the inner end wall of the armature shaft 88 is provided with a reduced socket IN to receive a small compression spring I82. One end of this spring engages the end of the pump shaft 85 and tends to urge it outwardly of the socket. This force causes the opposite end of the motor shaft to engage a bearing disk I88, inserted in the body 2| at the end o'f-the recess 28 and thus preclude longitudinal 4o movement of the shaft during use of the pump.

To facilitate the removal of the disk I88 and the bearing 38, the casing 2| has a plurality of openings I84 throughwhicha suitable tool can be passed to force out these members. In normal use, the openings I84 are. closed by plug screws The operation of the pump is as follows: Current is introduced to the driving motor to cause This shaft in turn im parts revolving motion to the shaft 88 and the the shaft 88 to revolve.

eccentric I2 forming a part thereof. As this eccentric revolves, pistons 58 are reciprocated in the cylinder sleeves 48. The springs 88 urge the heads of the pistons into engagement with the bearing 1| carried by the eccentric and when the low side of the eccentric approaches each piston,

the piston is moved into chamber 28 by its spring 88. During this motion, fluid -will flow from the chamber 28 through the passages 81, and 88, past the valve 85 through valve chamber 84 and the openings in plate 82 into the spring chamber of into the cylinder sleeve.

the piston. Since the valve 85 merely-rests on its seat 88, the movement of the piston into the fluid in the chamber 28 willbe suflicient to permit the fluid to raise the valve from its seat and flow When the high side of the eccentric approaches each piston and moves it outwardly, the valve will engage its seat, trapping the fluid in the piston and cylinder sleeve. Con.- tinued outward movement of the piston will force the fluidout through ports I8 and channels I5 to passages 11 and 18 to the outlet manifold I8. Re-

verse flow of this fluid is prevented by the valve 88 engaging seat 84. Thus, when a, particular piston moves into the chamber v28 on the following A washer 88 is stroke, a fresh charge of fluid will be supplied to construction is the ability to quickly change from one fluid pressure capacity to another by merely exchanging the pistons and cylinders in the pump I for others having the required diameters. When a high fluid pressure is to be developed, the piston and cylinder diameter is decreased in order to preserve safe bearing loads.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all'coming within the go scope of the claims which follow:

) l. A hydraulic pump comprising a casing having a chamber and a plurality of recesses radiating therefrom, said recesses opening at their outer ends to the exterior of said casing, said casing.'25

having inlet and outlet passages communicating with the chamber and recesses respectively; actuating means in said chamber; piston and cylinder assemblies removably disposed in each recess,

each of said assemblies having a cylinder sleeve ao inserted in a recess in said casing and a piston being formed of metal and slidably disposed in said sleeve, said piston having a longitudinally extending passage; and valve means in said passage to prevent fluid flow from the interior of said sleeve to the chamber in said casing.

2. A hydraulic pump comprising a casing having a chamber and a plurality of recesses radiating therefrom, said recesses Opening at their outer ends to the exterior of said casing, said casing w having inlet and outlet passages communicating with the chamber and recesses respectively; actuating means in said chamber; piston and cylinder assemblies removably disposed in each recess,

each of said assemblies having a cylinder sleeve 4 inserted in a recess in said casing and a piston being formed of metal and slidably disposed in said sleeve, said piston having an internal chamber connected by a passage with the chamber in said casing; valve means to control fluid flow from the piston chamber to the chamber in said casing; and resilient means in said piston chamber tending to move said piston from said cylinder sleeve into said casing chamber.

3. A hydraulic pump comprising a casing having a chamber and a plurality of recesses radiating therefrom, said recesses opening at their outer ends to the exterior of said casing, said casing having inlet and outlet passages communicating with the chamber and recesses respectively; actuating means in said chamber; piston and cylinder assemblies removably disposed in each recess, each of said assemblies having a cylinder sleeve inserted in a'recess in said casing and a piston being formed of metal and slidably disposed in said sleeve, said piston having a skirt, portion at the outer end of such thickness so as to expand radially under pressure within the skirt for sealing engagement with the inner wall of said cylinder sleeve; a passage extending from the inner to the outer end of said piston; valve means controlling fluid flow through said passage; and means between said piston and cylinder sleeve tending to move said piston out of said cylinder sleeve.

ing a chamber and a plurality of recesses radiating therefrom, said recesses opening at their outer ends to the exterior of said casing, said casing having inlet and outlet passages communicating with the chamber and recesses respectively; actuating means in said chamber; piston and cylinder assemblies removably disposed in each recess, each of said assemblies having a cylinder sleeve inserted in a recess in said casing and a piston being formed of metal and slidably disposed in said sleeve, said piston having a spring chamber and a valve chamber; a shoulder between said chambers; a perforated plate engaging said shoulder and serving as a spring abutment; a spring engaging said abutment and said cylinder sleeve; a passage connecting said valve chamber and the chamber in said casing; and valve means in said valve chamber to prevent reverse fluid flow through said passage. said perforated plate serving to limit the movement of said valve means in said valve chamber.

5. A fluid pressure energy translating device comprising a housing having a chamber with a plurality of recesses radiating therefrom and inlet and outlet passages communicating with the chamber and recesses respectively; a cylinder sleeve removably positioned in each recess, the interiors of said sleeves being in communication with said passages; valve means in said outlet passages to prevent reverse flow of fluid therethrough; a shaft journalled in said housing, said shaft having an eccentric portion in said chamber; a metallic piston disposedfor longitudinal movement in each cylinder sleeve; means urging said pistons toward said eccentric, rotation of said eccentric serving to move said pistons in opposition to said urging means, said pistons having passages. extending therethrough; and valve means in said piston passages to prevent fluid flow from said cylinder sleeves to said chamber.

6. A hydraulic pump comprising a housing having a chamber with a plurality of recesses radiating therefrom and inlet and outlet passages communicating with the chamber and recesses respectively; a cylinder sleeve removably disposed in each recess, said sleeves having their interiors in communication with said outlet passages; metallic pistons disposed for longitudinal movement in said cylinder sleeves; means between said cylinder sleeves and pistons tending to urge the latter elements toward said chamber; means in said chamber for successively moving said pistons in opposition to said urging means; and valved passages connecting said chamber and the interior of said cylinder sleeves at the outer ends of said pistons.

7. A hydraulic pump comprising a casing having a chamber and a plurality of recesses radiating therefrom; said casing having inlet and outlet passages communicating with the chamber and recesses respectively, the recesses opening at the outer ends to the exterior of said casing; a cylinder sleeve removably positioned in each recess; a metallic piston disposed for longitudinal movement in each cylinder sleeve; and means in the chamber in said casing for imparting movement to said pistons. l

8. In a fluid pressure energy translating device, a piston and cylinder sleeve assembly comprising, in combination, a sleeve-like body having one end closed, the wall of said body being provided with port means at the closed end; a metallic piston disposed for sliding movement in said body, said piston being open at the end within said body v 4. A hydraulic pump comprising a casing hav- (5 andhaving a passage extending to theopposite end; valve means in said passage to control the fluid flow through said passage; and means between said piston and said body tending to urge the former out of the latter.

9. In a fluid pressure energy translating device, a piston and cylinder sleeve assembly comprising, in combination, a sleeve-like body having one end closed, the wall of said body being provided with port means at the closed end; metallic pisvice, a piston and cylinder sleeve assembly comprising, in combination, a sleeve-like body having one end closed, the wall of said body being provided with port means at the closed end; a hollow metallic piston disposed for sliding movement in said body, said piston being open at the end within said body; a perforated abutment plate dividing the interior of said piston into spring and valve chambers; said piston forming a passage establishing communication between said valve chamber and the outer end of said piston; valve means in said valve chamber to control fluid flow through said passage, said abutment plate limiting the movement of said valve means; and spring means between the closed end of said sleeve and said abutment plate, said spring tending to urge said piston out of said sleeve.

11. In a fluid pressure energy translating device, in combination, a cylinder; a piston within the cylinder, said piston having a diameter normally less than the diameter of the interior of the cylinder, said piston having a head and a resilient metallic, skirt, said skirt being of such thickness so as tolexpand radially under pressure within the skirt, the characteristics or the metal skirt being such that the skirt contracts to normal diameter when the pressure is removed; and movable. means operatively associated with the head of the piston.

12. In a fluid pressure energy translating device, in combination, a metallic cylinder; a piston within the cylinder, said piston having a diameter normally less than the diameter of the interior of the cylinder, said piston having a head and a resilient metallic skirt, said skirt being of such thickness so as to expand radially under pressure within the skirt, the characteristics of the metal skirt being such that the skirt contracts to normal diameter when the pressure is removed, one of said metals containing graphite; and movable means operatively associated with the head of the piston.

' 13. In a fluid pressure energy translating device, in combination, a hardened metallic cylinder a piston within the cylinder, said piston having a diameter normally less than the diameter of the interior of the cylinder, said piston having a head and a resilient hardened metallic skirt, said skirt being of such thickness so as to expand radially under pressure '.Jithin the skirt, the characteristics of the metal skirt being such that the skirt contracts to normal diameter when the pressure is removed, one of said metals having a different hardness than the other; and movable means operatively associated with the head of the piston.

14. In a fluid pressure energy translating device, in combination, a hardened metallic cylinder; a piston within the cylinder, said pistonhaving a diameter normally less than the diameter of theinterior of the cylinder, said piston having a head and a resilient hardened metallic skirt, said skirt being of such-thickness so as to expand radially under pressure within the skirt, the characteristics of the metal skirt being such that the skirt contracts to normal diameter when the pressure is removed, one of said metals containing graphite and one of said metals having a different hardness than'the other; and movable means operatively associated with the head of THOMAS E. RAYMOND. REFERENCES crrnn .The following references are of record in the file of this patent:

UNITED sra'ms PATENTS v the piston.

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