US3831496A

US3831496A - Pressure responsive control body arrangement

Info

Publication number: US3831496A
Application number: US00239551A
Authority: US
Inventors: K Eickmann
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-04-07
Filing date: 1972-03-30
Publication date: 1974-08-27
Anticipated expiration: 1991-08-27
Also published as: ATA298771A; AT326484B; DE2214771A1

Abstract

A pressure responsive control body arrangement is provided in a fluid handling device thereby, that axially of one end of the fluid handling rotor which contains the fluid intaking and expelling working chambers a pressure responsive fluid flow control body is adapted against the rotary control face of the rotor to seal with its stationary control face along said rotary control face while said control body is partially contained in a fluid containing pressure chamber; axially moveable therein in a limited extend, forming separated portions of said pressure chamber therein and having a cylindrical but radially eccentrically located portion or control body shoulder extending into a respectively located portion of said pressure chamber and sealing therein one portion of the fluid containing chamber from another portion thereof, while in order to locate the pressure centre of said eccentric portion of said control body at the same position relatively to the axis of the rotor of the device as the control faces between said rotor and said control body have, the eccentric shoulder of said control body partially extends radially over the outer diameter of said control faces. This location of the eccentric shoulder of the invention provides a smooth running of the control faces along each other whereby tilting or sticking between them is effectivley prevented, so, that the control mirror between the rotary and the stationary control faces of the device operate at high efficiency also at high pressures in fluid and high relative velocities between them.

Description

United States Patent [191 Eickmann Aug. 27, 1974 [76] Inventor: KearlEickmann, 2420 Isshiki,

Hayama-machi, Japan [22] Filed: Mar. 30, 1972 [21] Appl. No.: 239,551

[30] Foreign Application Priority Data OTHER PUBLICATIONS N. A-Shute & D. E. Trunbull; The Thrust Balancing of Axial Piston Machines, May 1963 & June 1963, published by British l-lydromechanics, Research Association.

Primary ExaminerWil1iam L. Freeh Assistant ExaminerG. P. LaPointe Attorney, Agent, or Firm-Michael S. Striker [57 ABSTRACT A pressure responsive control body arrangement is provided in a fluid handling device thereby, that axially of one end of the fluid handling rotor which contains the fluid intaking and expelling working chambers a pressure responsive fluid flow control body is adapted against the rotary control face of the rotor to seal with its stationary control face along said rotary control face while said control body is partially contained in a fluid containing pressure chamber; axially V moveable therein in a limited extend, forming sepaand sealing therein one portion of the fluid containing chamber from another portion thereof, while in order to locate the pressure centre of said eccentric portion of said control body at the same position. relatively to the axis of the rotor of the device as the control faces between said rotor and said control body have, the eccentric shoulder of said control body partially extends radially over the outer diameter of said control faces. This location of the eccentric shoulder of the invention provides, a smooth running of the control faces along each other whereby tilting or sticking between them is effectivley prevented, so, that the control mirror between the rotary and the stationary control faces of the device operate at high efficiency also at high pressures in fluid and high relative velocities between them.

8 Claims, 2 Drawing Figures PRESSURE RESPONSIVE CONTROL BODY ARRANGEMENT BACKGROUND OF THE INVENTION The present invention relates to a pressure responsive control body atrangement in a fluid handling device, such as a hydraulic or pneumatic pump, compressor, motor, engine or transmission or the like, having working chambers whereto displacement members are associated for taking fluid into and out of said working chambers. Rotary fluid handling devices of this type are well known and have been proven reliable. A typical apparatus of this kind is disclosed in my U.S. Pat. No. 3,561 ,328. The said known fluid handling device how ever and the related devices have the disadventage that the structure is not compact enough, that the production costs and times are still too expensive and that the efficiency should still be improved. The device of my above mentioned patent has further the disadvantage that for higher pressure or relative velocities between the stationary and rotary control faces the application of the opposition chamber was nevessary in order to counteract to locally too strong pressure forces, which otherwise pressed the rotary and stationary control face of the locally too strongly together.

SUMMARY OF THE INVENTION rection to the rotor of the device wherein the controlbody assembly is of most simple design, can easiliy be machined, machined accurately and supply a control of the flow of fluid into and out of the rotor of the device with reduced friction, reduced leakage of fluid and with high efficiency for both, high and low pressure and velocity applications.

Another object of the invention is, to spare the heretofore used opposition chamber on a shoulder of the control body and also to spare the communications and control arrangements associated to said opposition chamber of said control body.

A further object of the inventionis, to acheave the elimination of the expensive opposition chamber and its associated members without reducing the reliability of the pressure responsive control body of the fluid handling device.

It has been known from my above mentioned patent, that many of the applied control bodies for controling the flow of fluid to and out of the rotor of a fluid handling device had a useful life at certain pressures and relative velocities between relatively to each other moving faces, but that they were either difficult to be manufactured accurately enough or that they failed to acheave their aim with good enough efficiency and reliability so, that it became necessary to improve their configuration to including the eccentric portion of the control body of said patent in combination with the opposition chamber and its control members associated thereto, when a higher pressure or rotary velocity was desired in the device. When the said opposition chamber was not associated to the eccentric shoulder of the control body of my U.S. Pat. No. 3,561,328, then the stationary control face of the control body of the device was still locally pressed too strongly against the rotary control face of the device, so, that as soon as a certain pressure was higher than the reliably useable pressure, welding and sticking between the control faces appeared. This fatality was overcome by applying the opposition chamber at higher pressure to the control body of my said patent. However, to apply the opposition chamber needed space, time, expense and a lot of additional members in praxis, like flow control piston, passages and so on, so, that the opposition chamber of my said patent byside of its feature of making the con trol body effective also had the disfeature of making it too expensive and place consuming. In addition it appeared, that the sealing means needed to be associated to the opposition chamber of my U.S. Pat. No. 3,561,328 narroed the flexible move ability of the control body, which in turn restricted the use of the control body to higher pressure applications. When on the other hand, the opposition chamber of my U.S. Pat. No. 3,561,328 was not associated to the eccentric shoulder of the controlbody of the said patent, then already at medial pressures and rotary velocities the said welding ad stickeng between the stationary and rotary control faces of control body and rotor appeared during opeartion of the device.

It has now been found in accordance with this present invention, that the welding between the control faces of U.S. Pat. No, 3,561,328 in case of non application of the opposition chamber was due to a too close location of the centre of the shoulder of the control body to the axis of the device, which resulted in the said local over pressure in the control clearance. The application of the opposition chamber has prevented the welding, but resulted in the increasing of the diameter of the shoulder of the control body and also in expensive additions.

It has now further been found in accordance with this present invention, that the device could be very much simplified and effectively improved for practical building and operation, if

a. the diameter of the shoulder of the control body would be narrowed together with b. the pressure centre of the fluid pressure chamber portion, whereinto the control body shoulder extends, would be moved more radially away from the centre line of the rotor of the device in order to get the same distance from the axis of the machine as the pressure centre in the fluid between the stationary and rotary control face has. It has further been found in accordance with this invention, that only one single seal would be needed in association with the fluid containing pressure chamber and the control body with an eccentric portion, if the eccentric portion would be correctly dimensioned andlocated in a one directional delivery or intaking fluid handling device.

In accordance with these findings of the invention the fluid handling devices will be improved by the provisions of this invention, which consist therein,

1st, that the shoulder of the control body is of cylindrical configuration, but eccentrically distanced from the axis of the rotor in such extend, that even at the de sired small, but necessary diameter of the eccentric shoulder of the controlbody a part of said eccentric shoulder extends radially at one location beyond the outer diameter of the stationary or rotary control face of the fluid handling device; or, that 2nd, in a one directionl flow device the control body has only one single centric portion and only one single eccentric portion, why one portion thereof may be unsealed; or that 3rd, the member containing the fluid containing pressure chambers and partially containing said control body is assembled by two different portions, so that the eccentric shoulder of said control body may be contained between both portions; or that 4th, the end portion of the control body is reduced to a minimal diameter in order to make the radial extension of the eccentric shoulder over the outer diameter of the control face possible; or that 5th, the rotor passages are inclined from the bottoms of the working chambers radially inwanrdly in order to port at the smallest possible distance to the axis of the rotor through the respective axial end of the rotor in order to make a small diameter control body possible, so, that the eccentric shoulder of the control body can extend over the outer diameter of the control face without becoming too big in diameter itself; because if it would become too big in diameter itself, it would again need an opposition chamber of U.S. Pat. No. 3.561.328 which this invention actually prevents. Common to each controlbody of the invent on is, that the eccentric shoulder of the control body partially extends beyond the diameter of the control face.

Common to all controlbodies of the invention is also, that the pressure centre of the eccentric shoulder lies behind the pressure centre of the controlface.

Common to all control bodies of the invention is also, that the crossection through the respective pressure chamber is only a few percent larger in area than the responsive crossectional area through the respective high pressure aquivalent area in the control clearance between the control body and the rotor is. The modification of the embodiments of the invention consist therein, that:

either, the fluid containing pressure chamber is located in a single body or located in a body assembled by a plurality of parts;

That the fluid containing pressure chamber has only one sealed chamber portion or two sealed chamber portions;

that the control body has only one eccentric and one centric portion or it has one eccentric and two centric portions;

that either fluid passages extend through the control body or only control ports extend into it or only balancing ports extend into it.

The novel features which are considered as characteristic for the invention are set force in particular in the appended claims. The invention itself, however, both as to its characteristics of construction and its method of operation together with additional objects and adventages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal view through an embodiment of the invention, and

FIG. 2 is a longitudinal sectional view through a portion of a fluid handling device containing another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a known housing, which is not shown in the drawings, a rotor l is rotatably borne in bearings and axially at one end of said rotor supported on a thrust bearing 37. The rotor contains the fluid handling working chambers, for example 2 and 3 or a plurality thereof and displacement members 4 are associated to the working chambers 2 or 3 in order to guide the expan' sion and contraction of the volume of the working chambers. Rotor passages 12 and 13 extend from the respective working chambers to an end of the rotor l and therethrough to form rotor ports in an axial end of the fluid handling rotor l for leading fluid into or out of said working chambers 2 or 3 in the rotor of the fluid handling device. n a hosing portion or cover portion 14 of the device a fluid containing

pressure chamber

8,9,21,22 is provided and a control body, also called thrust member or control chuck 7 is partially located in said fluid containing pressure chamber and forms a stationary controlface face 20 on the end of said controlbody adjacent to said rotor for sliding and sealing along the rotary control face 19 on the adjacent axial end of the rotor l. The fluid acting in the fluid containing pressure chambers 8,9,2] or 22 are pressing the control body 7 axialwardly against the endface 19 of the fluid handling rotor 1, so, that no leakage or only small leakage escapes through the control clearance, which is formed between the two control faces, the stationary control face 20 of control body 7 and the rotary control face 19 of rotor 1. The control body 7 has at least one

centric portion

7 or 7 and 15 and at least one excentric portion 31. Fluid flows from port 10 through passage 5 and port 5 (control port 5 and through rotor passages 12 or 13 into the respective fluid handling working chambers 2 or 3 and out of them through the respective rotor passages 12 or 13 and control port 6 and passage 6 to and out out of port 11 or vice versa.

The device described heretofore is well known in the art for example from my above mentioned patent, U.S. Pat. No. 3,561,328.

At said patent however, the counter balancing opposition chamber was applied onto the control body for acting contrary in direction to the fluid forces which acted onto the control body in the direction against the rotor. The latter was necessary, because the end portion of the control body of the said U.S. Pat. No. 3,561,328 had a bid diameter axial end portion on the backwards end of the control body. That made a large diameter of the excentric shoulder of the control body necessary, while on the other hand the big diameter of the end portion of the control bpdy prevented a larger excentric location of the excentric shoulder of the control body. Because the diameter of an end portion on the backward end of the control body limits the eccentric location of the eccentric portion of the control body. Thereby the eccentric portion of the control body became so big in diameter and so became the seals of the chamber portions of the fluid containing pressure chamber, that the control body was too strongly pressed against portions of the rotary control face of the rotor, which made it necessary to apply the counter acting opposition chamber of US. Pat. No. 3,561,328 in order to prevent said too strong pressing of the control body against the rotary control face.

The latter draw back of the application of the expensive counter balancing opposition chamber is fully overcome by the present invention, which consists therein, that the eccentric shoulder 31 of (thecontrol) of the control body or control chuck or thrusting body 7 extends partially radially beyond the outer diameter of the contril face 19 or 20. This feature of thne invention makes it possible, to eliminate the heretofore used counter balancing opposition chamber, because; only if the eccentric portion extends radially partially beyond the outer diameter of the control face is it possible to place the pressure centre of the fluid containing pressure chamber portion and of the eccetric shoulder 31 of control body 7 exactly into the same position relatively to the rotor axis, which the pressure centre of the fluid in thne fluidfilm between the stationary and rotary controlfacees 19 and has. Only if said both pressure centres have the same axis parallel to the axis of the rotor is an even pressing of the control body against the rotor 1 possible without local over pressures and under pressures. The precise location of the pressure centre of the eccentric portion 31 of control body 7 by the application of the characterization of the invention, that the eccentric portion 31 of control body 7 partially extends radially beyond the outer diameter of the control face 19,20, makes it possible to reduce the crossectional area through the eccentric shoulder or through the pressure chambers 8 or 9 to a few percent larger than the crossectional area through the associated portion of the fluid film in the control clearance between the control faces 19 and 20. The associated portion in thne fluid film is to be considered to be the high pressure aquivalent area within said control clearance between said stationary and rotary control faces 19 and 20. This aquivalent area consists actually of a high pressure area plus an area of pressure drop, which i mean has a lesser fluid pressure, but beeing calculated as a lesser area of high pressure, called the high pressure equivalent area. In US. Pat. No. 3,561,328 the eccentric shoulder extended also beyond the outer diameter of the control face, but the crossectional area through the eccentric shoulder was many percent larger than thne associated pressure aquivalent area in the control clearance, whereby the application of the opposition chamber became necessary. According to the invention however, the opposition chamber is spared, because the excentric extension of the eccentric shoulder 31 oever the diameter of control face 19,20 is combined with the reduction of the crossectional area through the eccentric shoulder 31 to a few percent over the area of the pressure aquivalent area in the control clearance 19-20. And, thereby, the opposition chamber is spared by this invention.

The most simplest embodiment of the invention is demonstrated in FIG. 2. From port 24 flows fluid through the fluid containing suction chamber or intake chamber 22 and through passage and control port 6 and through the control clerance 19 20 and through the respective rotor passages 13 or 12 into the respective working chambers in rotor l and out thereof through again respective rotor passages 12 or 13 and the control clearance 19 20 into and through control port 5 and through passage 5 and through pressure chamber 21 into and through exit port 23 of the fluid separated from each other and sealed against each other by the seat 16, which is preferred to be a cylindrical configuration. This cylindrical configuration how ever has an axis, which is eccentric relatively to the centric axis of rotor 1 and of the centric portion 7 of control body 7. The fluid pressure chamber 22 may further be sealed by the seat 17. This seat is also of prefferedly cylindrical configuration. However this cylindrical configuration is centred around the centrical axis of control body or control chuck or thrust member 7. Saif centrical axis is equal to the axis of the revolving rotor l of the fluid handling device. Thus, high pressure in fluid can either be present in pressure chamber 21 or in pressure chamber 22 and in each case the pressure in fluid in the respective fluid containing

pressure chamber portion

21 or 22 will presse the control body 7 in axial direction against the end 19 or the rotor l of the device, so, that both control faces 19 and 20 are pressed together and form together the self sealing control clearance 19 20 between the stationary control face 20 and the rotary control face 19. The control body 7 is axxially within a limited extend moveable within the pressure chambers 21 22. Thecrossectional area through the eccentric portion or shoulder 31 of the control body should be, according to the invention, restricted to be only a few percent, f.e. 4 to 6 percent, larger than the crossectional area through the respective high pressure aquivalent area in the respective portion between the control faces 19 and 20 of the device. And, the eccentricity of the eccentric portion or shoulder 31 should be of such dimension, that the pressure centres of the shoulder 31 and of the respective portion of the control means between faces 19 and 20 are in the same axis, eccentric to, but also parallel to the axis of the rotor 1 of the device. If these conditions of the invention are met, then the device operates effectively also at high and very high pressures and relative velocities between the control faces 19 and 20. In such case of obeying the condition of the invention, the eccentric shoulder 31 of control chuck 7 will exxtend partially beyomd the outer diameter of control face 20, while no opposition chamber will be present at the opposite end of the eccentric shoulder 31.

If the flow of the fluid through the device of FlG. 2 is alltimes so, asto enter as law pressure into port 24 or to flow as low pressure through port 24 and as high pressure through port 23, than the fluid containing pressure chamber portion 21 will alltimes be the high pressure chamber, while fluid containing pressure chamber portion 22 will then alltimes be the low pressure portion, or low pressure chamber. A low pressure chamber however sometimes needs no seal or only a rough seal. When no seal is needed for the low pressure chamber 22, then the machining of the the control chuck 7 of the invention and of its associated seats or housing means becomes especially easy and simple. Be-

could be catsed or pressed with a rough tolerance and also with a rough tolerenace could the outer diameter of the centric portion 7 of the control body or control chuck 7 be made. The centric portion 7 could even have a big clearance within housing means 17, so as to float therein in a limited extend. The machibing of seat and seal 16 of the eccentric chamber portion and control

body shoulder

22 and 31 is then very simple, easy and inexpensive and no no specific care has than to be taken to the location of the adjacent centric portion 7 with housing means 17. The easiness of machining appears analog toa more reliable and effecitive working of the control means of this invention.

For fluid handling devices with reversal of pressure or flow direction it is often necesseary or desired to have a small shaft portion extending through the whole achsial length of the device. Then it is necessary to provide a backwards end portion of the control body 17 in a seat of the housing or cover portion 14, of the fluid handling device. End portion 15 in seat 15 must then be sealed against the fluid pressure chamber 8, because otherwise no shaft portion could be extended through the heck of the machine without fluid leaking out of chamber 8. The seat 15 is centrically and provided within housing portion 14. All seats,

seats

15,16 and 17 are again preferred to by cylindrical. The control body or control chuck with an end portion 15 in seat 15 is demonstrated in FIG. 1. This embodiment is mostly utilized for reversible flow and reversing of the high pressure chambers 8 and 9. Therefore, in the standard device of FIG. 1 all

seats

15,16 and 17 are sealed. The sealing is done commonly by a diamterical clearance of about 50 thousandth of a millimeter and plastic or expanding ring type seals. Ports lo and 11 acts as ports 23 and 24 of FIG. 2, while the pressure chambers 8 and 9 overtake the

duties pressure chambers

21 and 22 of FIG. 2. The members with equal referentials as in FIG. 2 take over equal functions as in H6. 2 and do not need any specific discussion referering to FIG. 1, because their location and action is understood from the description of FIG. 2.

The portion 31 in seat 16 is the eccentric shoulder 31 of the control body or control chuck, 7. Since it partially extends radially beyond the outer diameter of the control face of the controlbody or control chuck 7; it is necessary. if the seat 17 shall also seal, as it must, if the device is of the flow reversing type, to divide the housing portion 14 along the face 18 or a face parallel to face 18, in order to make the machining of the housing portion 14 with its seat 16 and the insertion of the control body 7 thereinto possible. After such divisoon and insertion of the control body 7 into its seats, the housing portion 18 has to be assembled again and a seal hs to take place along the face 18. The control, body or control chuck 7 remains movebale in axial direction within housing portion 14 and sealed within

seats

15,16 and 17, if built in accordance with the rooles of this invention.

It should be recognized, that for providing an axially thrusting control body towards a rotor, it will be necessary to obey the rooles of this invention. If the configuration of the control body or its location is mistaken only slightly, then welding between the controlfaces or high leakage through them will appear. Therefore strickt measures must be taken to obey the teaching of this invention.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of fluid handling devices differing from the types described above.

While the invention has been illustrated and described as embodied in a control body arrangement for a fluid handling device, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying correct knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore such adaptions should and are intended to be comprehendend within the meaning and range of aquivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

What I claim is:

1. In a fluid handling device, a combination comprising a housing; a rotor mounted in said housing and having a first control face at one axial end thereof, a plurality of working chambers and first passages extending between said working chambers and said first control face, said housing having inlet and outlet ports for admission and evacuation of fluid and pressure chamber means communicating with said ports; and a control body axially movably received in said pressure chamber means and having a second control face adjacent to and defining with said first control face a narrow control clearance, said control body being urged toward said rotor by fluid in said pressure chamber means and including at least one larger-diameter first cylindrical portion coaxial with said rotor and at least one smaller-diameter second cylindrical portion which is eccentric relative to said rotor and extends in part radially beyond at least one of said control faces, said control body further having second passages alternatingly connecting said first passages with said inlet and outlet ports when said rotor rotates relative to said housing.

2. A combination as defined in claim 1, wherein said housing comprises a plurality of parts assembled with and connected to each other upon insertion of said control body into said pressure chamber means.

3. A combination as defined in claim 1, wherein said housing is provided with first and second seats respectively receiving said first and second cylindrical portions of said control body, said first seat receiving said first cylindrical portion with a clearance greatly exceeding the clearance between said second seat and said second cylindrical portion.

4. A combination as defined in claim 1, wherein said pressure chamber means includes a high-pressure chamber for said second cylindrical portion and a lowpressure chamber for said first cylindrical portion of said control body.

5. A combination as defined in claim 4, wherein one of said second passages is provided in said second cylindrical portion of said control body.

6. A combination as defined in claim 1, wherein each of said working chambers has a bottom portion and said first passages extend from the bottom portions of the respective working chambers and substantially radially inwardly of said rotor so that the distance between said first passages and the axis of said rotor in the region of said first control face is less than the distance between said bottom portions and the axis of said rotor.

7. In a fluid handling device, a combination comprising a housing; a rotor mounted in said housing and having a first control face at one axial end thereof, a plurality of working chambers and first passages extending between said working chambers and said first control face, said housing having inlet and outlet ports for admission and evacuation of fluid and pressure chamber means communicating with said ports; and a control body axially movably received in said pressure chamber means and having a second control face adjacent to and defining with said first control face a narrow control clearance, said control body being urged toward said rotor by fluid in said pressure chamber means and including at least one larger-diameter first cylindrical portion coaxial with said rotor, at least one smaller-diameter second cylindrical portion which is eccentric relative to said rotor and extends in part radially beyond at least one of said control faces, and a third cylindrical portion which is coaxial with said first cylindrical portion and has a diameter which is a fraction of the diameter of said first cylindrical portion, said control body further having second passages alternatingly connecting said first passages with said inlet and outlet ports when said rotor rotates relative to said housing. 8. In a fluid handling device, a combination comprising a housing; a rotor mounted in said housing and having a first control face at an axial end thereof, a plurality of working chambers and first passages extending between said working chambers and said first control face, said housing having inlet and outlet ports for admission and evacuation of fluid and pressure chamber means communicating with said ports; and a control body axially movably received in said pressure chamber means and having asecond control face adjacent to and defining with said first control face a narrow control clearance, said control body being urged toward said rotor by fluid in said pressure chamber means and including at least one larger-diameter first cylindrical portion coaxial with said rotor, at least one smaller-diameter second cylindrical portion which is eccentric relative to said rotor, and a third cylindrical portion which is coaxial with said first cylindrical portion and has a diameter which is a fraction of the diameter of said first cylindrical portion, said control body further having second passages altematingly connecting said first passages with said inlet and outlet ports when said rotor rotates relative to said housing.

Claims

4. A combination as defined in claim 1, wherein said pressure chamber means includes a high-pressure chamber for said second cylindrical portion and a low-pressure chamber for said first cylindrical portion of said control body.

7. In a fluid handling device, a combination comprising a housing; a rotor mounted in said housing and having a first control face at one axial end thereof, a plurality of working chambers and first passages extending between said working chambers and said first control face, said housing having inlet and outlet ports for admission and evacuation of fluid and pressure chamber means communicating with said ports; and a control body axially movably received in said pressure chamber means and having a second control face adjacent to and defining with said first control face a narrow control clearance, said control body being urged toward said rotor by fluid in said pressure chamber means and including at least one larger-diameter first cylindrical portion coaxial with said rotor, at least one smaller-diameter second cylindrical portion which is eccentric relative to said rotor and extends in part radially beyond at least one of said control faces, and a third cylindrical portion which is coaxial with said first cylindrical portion and has a diameter which is a fraction of the diameter of said first cylindrical portion, said control body further having second passages alternatingly connecting said first passages with said inlet and outlet ports when said rotor rotates relative to said housing.

8. In a fluid handling device, a combination comprising a housing; a rotor mounted in said housing and having a first control face at an axial end thereof, a plurality of working chambers and first passages extending between said working chambers and said first control face, said housing having inlet and outlet ports for admission and evacuation of fluid and pressure chamber means communicating with said ports; and a control body axially movably received in said pressure chamber means and having a second control face adjacent to and defining with said first control face a narrow control clearance, said control body being urged toward said rotor by fluid in said pressure chamber means and including at least one larger-diameter first cylindrical portion coaxial with said rotor, at least one smaller-diameter second cylindrical portion which is eccentric relative to said rotor, and a third cylindrical portion which is coaxial with said first cylindrical portion and has a diameter which is a fraction of the diameter of said firSt cylindrical portion, said control body further having second passages alternatingly connecting said first passages with said inlet and outlet ports when said rotor rotates relative to said housing.