US3889577A

US3889577A - Pressure-responsive control body for use in fluid handling devices

Info

Publication number: US3889577A
Application number: US321853A
Authority: US
Inventors: Karl Eickmann
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-01-05
Filing date: 1973-01-08
Publication date: 1975-06-17
Anticipated expiration: 1992-06-17

Abstract

A pressure-responsive control body for use in a fluid handling device such as a hydraulic or pneumatic pump, compressor, motor, transmission or the like is movable axially in a housing and has a stationary control face adjacent to a control face of a fluid handling rotor. A fluid flow control area is formed between the control faces and two fluid containing pressure chambers are formed in the housing by two shoulders of the control body. The middles of the pressure chambers are eccentric relative to the rotor. The cross-sectional areas of the pressure chambers are a little larger than the cross-sectional area of the high-pressure equivalent zone of the fluid flow control area and the pressure centers of the high-pressure zones of the fluid flow control area and of the respective pressure chambers are located on an axis which is parallel to the axis of the rotor and one chamber extends in part radially beyond the control face of the control body. The housing is provided with a separable closing member for one of the pressure chambers.

Description

United States Patent 1 1 Eickmann [1 11 3,889,577 June 17, 1975 PRESSURE-RESPONSIVE CONTROL BODY FOR USE IN FLUID HANDLING DEVICES [22] Filed: Jan. 8, 1973 [21] Appl. No.1 321,853

Related US. Application Data [63] Continuation-impart of Ser. No. 239,551, March 30,

1972, Pat. No. 3,831,496.

[30] Foreign Application Priority Data OTHER PUBLICATIONS The British l-lydromechanics Research Association en- E I W F I L F titled The Thrust Balancing of Axial Piston Machines Published June 1963.

Primary Examiner-William L. Freeh Attorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT A pressure-responsive control body for use in a fluid handling device such as a hydraulic or pneumatic pump, compressor, motor, transmission or the like is movable axially in a housing and has a stationary control face adjacent to a control face of a fluid handling rotor. A fluid flow control area is formed between the control faces and two fluid containing pressure chambers are formed in the housing by two shoulders of the control body. The middles of the pressure chambers are eccentric relative to the rotor. The cross-sectional areas of the pressure chambers are a little larger than the cross-sectional area of the high-pressure equivalent zone of the fluid flow control area and the pressure centers of the high-pressure zones of the fluid flow control area and of the respective pressure chambers are located on an axis which is parallel to the axis of the rotor and one chamber extends in part radially beyond the control face of they control body. The housing is provided with a separable closing member for one of the pressure chambers.

11 Claims, 3 Drawing Figures PRESSURE-RESPONSIVE CONTROL BODY FOR USE IN FLUID HANDLING DEVICES RELATED APPLICATION The present application is a continuation-in-part application of my US. Pat. application Ser. No. 239,551, filed on Mar. 30, 1972, now US. Pat. No. 3,831,496.

BACKGROUND OF THE INVENTION The present invention is concerned with a fluid handling device wherein fluid is supplied into and out of working chambers in a rotor and which can operate as a pump, motor, compressor, transmission or the like. Highly effective and powerful fluid handling devices of this kind are well known in the art and widely applied in industries and vehicles. My US. Pat. No. 3,398,698 discloses two pressure responsive chambers in a housing portion for reception of two shoulders on a pressure responsive control body so that the stationary control face of the control body is pressed against the control face of the rotor.

My U.S. Pat. No. 3,561,328 was granted on an application of which my copending application Ser. No. 89,804 is a continuation. The present case is a continuation in part of Ser. No. 89,804. US. Pat. No. 3,561,328 discloses two fluid containing pressure chambers and a cylindrical sealing and bearing face therebetween. A further cylindrical sealing and bearing face is provided between two shoulders on portions of a control body which is partially located in the pressure chambers and the diameters of the sealing and bearing cylindrical faces are substantially identical and one thereof surrounds the other. These sealing and bearing faces have an axis which is eccentric to the axis of the outer face of one of the fluid containing pressure chambers and to the inner face of the other pressure chamber, and the control body can move axially within the pressure chambers at least to a limited extent.

The U.S. Pat. No. 3,561,328 further discloses an op- However. even the provision of an opposition chamber and/or balancing recesser in the stationary control face has not insured a maximum of efficiency and satisfactory operation at highest pressures.

Referring first to the utilization of balancing recesses in the control face, it has been discovered that the balancing recesses cause two more flows of leak fluid out of the control area between the stationary control face and the rotary control face and necessitate a larger diameter of the control faces for providing space for the balancing recesses. This in turn produces higher relative speeds between the stationary and rotary control faces and higher friction between the control faces resulting in greater leakage of fluid between the control faces because, due to the larger diameters of the control faces the fluid ports also became longer whereby the leakage areas became longer. These drawbacks, either singly or all together, reduce the volumetric efficiency and the mechanical efficiency and thereby the overall efficiency and power of such devices. The application of the balancing recesses made it further necessary to provide fluid passages in non-centric portions of the control body because, if disposed centrically, they would meet and thereby communicate with each other which would render the device inoperable.

An arrangement with opposition chambers requires a relatively long control body and also an additional sealing means for sealing the opposition chamber in one axial direction. For the provision of such sealing means for the opposition chamber, thecontrol body must be longer in the axial direction and so must be the housing portion which contains the control body and the fluid containing pressure chambers and opposition chamber. This elongation of the control body arrangement limits the radial movability of the control body because, for proper sealing, the clearances between the outer faces of the control body shoulders and the faces of the housing portion must be very small, for example 0.04 mm. The distance from the outer end of the conposition chamber atone of the shoulders of the control I body in order to guarantee safe operation at elevated pressure of fluid. US. Pat. No. 3,092,036 discloses balancing recesses for reception of pressure fluid in the stationary control face of the control body.

Each of the just discussed features renders the pres sure responsive control body with an eccentric shoulder more suited for operation of elevated pressures. A failure to provide an opposition chamber or balancing recesses has resulted in an overload under fluid pressure in one of the half zones of the control face or in an underload in one of the half zones of the control area so that the fluid was free to leak through the underloaded zone or friction developed in the overloaded zone of the controlface because the pressure centers of the control area and of the pressure chambers where not located on the same axis parallel to the axis of the rotor. Such arrangements were acceptable at low pressures and for operation with low efficiency. However,

iing recesses has partially overcome the just discussed lack of efficiency and inability to operate at elevated pressures.

control body can tilt in its seats only to a very limited extent, for example, 0.04 mm, the total tilting ability of the control body depends on the relation between the radial clearances around the control body and the axial distance between the remotest points of the seal means around the control body in the housing portion which contains the respective portions of the control body. This means that the ability of the control body to tilt decreases with increasing axial length of the seal places of the control body. Consequently, a control body arrangement which includes an opposition chamber is less able to tiltthan a control body without an opposition chamber. The restriction of the ability to tilt also restricts the ability of the control body to adapt itself to the control face of the rotor if the latter is slightly inclined due to machining tolerances of the bearing seats of the rotary fluid handling body, or if the rotor has some freedom of wobbling. An unpredictably rotating or wobbling rotor will cause leakage and friction between the stationary and rotary control faces if the control body can not adjust itself to such unprecise rotation of the rotor. It was attempted to enlarge the clear-' completely blocked. Consequently. the widening of clearances around the seal portions of the control body is not a suitable solution to allow for some tilting of the control body. In accordance with the present invention, the desired limited tiltability of the control body can be achieved by shortening that portion ofthe control body where it is surrounded by seats so that the ratio of the width radial clearances around the respective control body portions to the combined axial length of the seal portions of the control body arrangement becomes larger. This, however, means that such ratio can become larger only by eliminating the opposition chamher.

It is therefore an object of this invention to eliminate the opposition chamber and to thus reduce the axial length of the control body arrangement for the purpose of increasing the ability of the control body to tilt in order to be capable to conform its stationary control face to the control face of the rotor. With the elimination of the opposition chamber, the fluid passages to the opposition chamber and the fluid control cylinders and pistons thereof can be eliminated. The seal means for the opposition chamber can also be eliminated and the heretofore used balancing recesses in the stationary control face can be dispensed with. The elimination of the seal means for the opposition chamber eliminates friction which prevented the pressing of the control body against the control face of the rotor at low fluid pressures. The control body with opposition chamber was therefore often unsuitable for operation at low pressures because the pressure of fluid in the pressure chambers was unable to overcome the friction between the seal means surrounding the control body portions and the seal faces in the housing.

Another object of the invention is to simplify the control body arrangement to such an extent that it is easier and less expensive to build and is also more reliable, more economical and more efficient because it has fewer parts than heretofore known arrangement.

SUMMARY OF THE INVENTION It has been recognized that:

a. A control body arrangement with a centric and an eccentric shoulder cannot operate at high pressures without the provision of some means for equalizing the pressures at both ends of the control body.

b. Control body arrangements with an eccentric shoulder in an eccentric fluid containing pressure chamber which utilize balancing recesses in the stationary control face cause additional leakage through the respective portions of the flow control area.

c. Control body arrangements with opposition chambers are ineffective at certain pressures because they cannot adapt themselves to the rotary control face at low pressure. Also, they are expensive to build, too long and have too many machined portions.

The objects of the invention can be achieved in the following way:

a. The placing of pressure centers of the fluid flow control area between the stationary and rotary control faces on axes which are parallel to the axis of the rotor and of the control body but are eccentrically spaced therefrom and are also the axes of the centers of fluid containing pressure chambers at the opposite end of the control body;

b. The control body has an eccentric shoulder the outer portion of which extends in part radially beyond the outline of thes ta'tionary control face of the control body;

c. The housing which contains the control body is provided with a cover which applied after insertion of the control body so that it forms at least two fluid containing pressure chambers surrounding certain portions of the axially movable control body. One of the fluid containing pressure chambers and the respective portion of the control body remain partially within the outline of the control face of the control body and extend in part beyond the outline of such control face whereby d. one of the pressure chambers acts on the control body in opposite axial directions; namely towards the rotor at that part of the respective portion which remains within the outline of the control face and away from the rotor at that part of the control body portion which extends radially beyond the outline of the control face of the control body.

If the above features of the invention are incorporated inthe control body arrangement, the latter will operatemosteffectively at all desired pressures and velocities and will be easy to machine and simple in its structure. It is necessary, however, that the eccentricities, other dimensions, clearances, etc. satisfy the condition that the pressure centers of the control area and of the pressure chambers be located on the same axis parallel to the axis of the rotor and of the centric portions of the control body.

The pressure centers cannot be seen with the human eye. However, the exact positioning of such pressure centers is indispensable if the arrangement of the invention is to function properly. Therefore, the invention further resides in the provision of mathematical equations which facilitate the determination of diameters and eccentricites of eccentric portions and chambers for effective and convenient machining and opera tion.

' BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view through an embodiment of the invention;

FIG. 2 is a fragmentary cross sectional view as seen in the direction of arrows from the line IIII of FIG. 1; and

FIG. 3 is a fragmentary cross sectional view as seen in the direction of arrows from line III-III of FIG. 1.

The following conditions exist at the axial ends of portions of or the entire control body I:

At that end of the control body 1 which faces the rotary control face 30 of a rotary fluid handling body 36 of the fluid handling device. a stationary control face 31 of the body 1 defines with the control face 30 a fluid flow control area or control clearance 32.

This cylindrical end of the control body 1 is hereafter called the control portion 6 of the control body and its control face 3I is formed with

control ports

17 and 18. One of the ports 17 and I8 acts as a means for supplying fluid to fluid handling working chambers 34 in the body 36 through passages 33 of the body 36 and the other of the ports 17 and l8 acts as a means for conveying fluid out of the working chambers 34 and passages 33 of the body 36. The working chambers 34 receive fluid displacement means 35vand the rotor 36vrotates in bearings 38. Theprovision of a thrust bearing 37 is necessary to keep the rotor in its axially fixed position in at least oneaxialdirection. The purpose of two thrust chambers or pressure chambers 2 and 8 is similar to that of somewhat differently shaped and. located thrustchambers in the apparatus of my U.S. Pat. No. 3,561,328. The control body 1 has an end portion 12 and an eccentric cylindrical portion or shoulder 3. The shape and location of the shoulder 8 are different from those of my aforementioned US patent. The bearings 38 are located in a housing 39. The housing 39 has a cover portion or por portion 5 which forms with cylindrical portions 6 and 3 of the body 1 the two fluid containing pressure chambers 2 and 8 and these chambers allow the control body 1 to move axially in the housing 39. A further chamber 13 is formed in housing portion 5 for reception of the small end portion 12 of control body 1. The fluid flows through a

port

43 or 44, through a

passage

45 or 46, through the

control port

17 or 18 and one of the passages 33 into or out of the fluid handling chambers 34. The portion or shoulder 3 of control body 1 seals the chamber 2 in one axial direction; the portion 12 of control body 1 is located in the chamber 13 of housing 6 and the control portion 6 seals the chamber 8 in one axial direction. The locations, dimensions and eccentricities of the pressure chambers and control body portions of the apparatus of the present invention are different from those disclosed in my U.S. Pat. No. 3,561,328.

The control body 1 is axially movable in the housing portion 5 and the fluid pressure in one of the chambers 2 and 8 is a little higher than that in the control area 32 so that the control body 1 is urged toward the control face 30 of the rotor 36.

One of the

control ports

17 and 18 normally contains fluid under higher pressure, while the other control port contains fluid under lower pressure. During admission of pressurized fluid into one of the

control ports

17 and 18, some fluid can flow through the control clearance 32 and out from the high pressure area of the device. If no fluid would enter the clearance 32, then the stationary and rotary control faces 30 and 31 would touch each other by metal to metal contact and this would immediately lead to welding between the control faces 31 and 32, whereby the control faces and the fluid handling device would be damaged. However the escape of leakage fluid through the control area 32 is to be kept to a minimum in order to obtain a high volumetric efficiency. Since the interior of the housing portion 5 is normally maintained at atmospheric pressure or another pressure lower than the pressure in the

port

17 or 18, a radially inwardly directed first fluid pressure area develops radially of the

high pressure port

17 or 18 and a radially outwardly directed second fluid pressure area develops radially of the high-pressure port. In these areas which form part of the control area 32, the pressure is highest at the

control port

17 or 18, namely where the pressure of fluid is highest, and the pressure decreases gradually radially of the control area 32 away from such highest-pressure zone. The pressure drop is not in all cases linear because it is influenced by the viscosity of fluid, relative velocity between the stationary and rotary control faces 31 and 30 and local temperatures. All of these parameters influence the pressure gradient in the radial direction inwardly and outwardly from the respective high

pressure control port

17 or 18. The actual pressure drop in radial direction is measured locally estimated or known from experience. The thus determined radial distances ri 19 and r0 respectively represent the radii of inner and outer circles where the pressure is half the pressure differential between the high

pressure control port

17 or 18 and the interior of the housing portion 5. The radii ri and

r0

19 and 20 respectively extend from the center of the control area 32 to about the middle between the radially innermost and outermost portions of the

port

17 or 18 and the inner or outer diameters of the control face 31 or 30. However the exact dimensions of ri and r0 are dependent on temperature, centrifugal forces, viscosity of fluid, friction and contraction in the respective portion of the control area 32.

If the values of ri and

r0

19 and 20 are determined, it can be assumed for calculation that the high pressure acts in the control area 32 from ri to r0. The values ri and r0 are mathematical values. Actually, there is high pressure and pressure drop in the control area 32, but for mathematical calculation the actual gradient area is replaced by an exactly bordered high pressure area reaching from ri to r0 as the high pressure equivalent of the actual pressure area in the control area 32.

Since one of the

control ports

17 and 18 normally contains fluid at high pressure, while the other port contains fluid whose pressure is low, the area 32 includes a high pressure zone and a low pressure zone. The high pressure zone extends along an arc of about or one half of the pressure area 32, and the low pressure zone also develops along an arc of 180 or the other half of the control area 32. In actual operation of the device, the respective rotor passage 33, or a portion thereof, may extend at times beyond the

control port

17 or 18 of the body 36. Also, fluid may be drawn through that portion of the control area 32 which has no port, the so called closing area, when the control face 30 rotates because, due to its motion, the face 30 carries some fluid out of the

respective port

17 or 18 into the

other port

18 or 17. Due to the just mentioned factors, the high pressure zone does not extend exactly along an arc of 180 or one half the control area 32 but is a little wider. The enlargement of the high pressure zone in the control area 32 is indicated by the angle gamma and reference character 27. The axis of the rotor 36 is located in a plane 28 which is normal to the common plane of the axes of 36 and eccentric control body portion 3. The pressure equivalent zone G does not develop exactly along an arc of 180 of the control area 32 but actually along an arc of 180 plus 2 gamma. This is expressed in the equation (1) as follows:

In this equation, gamma is the constant value of the high pressure equivalent area. It is to be understood, however, that gamma is not constant but changes continuously during operation of the machine, depending upon how far a rotor passage 33 extends beyond the

control port

17 or 18 with which it communicates at a given time. The constant value gamma is therefore a median or average value per unit of time. As a rule, depending on size and configuration of the control area 32, the value of gamma is between 0 and 15.

With the above in mind, the control area 32 can be replaced for reasons of calculation by the high pressure equivalent area A HPm which can be determined as follows:

Once the high pressure equivalent A HPm of the control area 32 is known, it is relatively simple to determine the necessary cross-sectional area of the fluid containing pressure chamber on the respective shoulder of the control body 1.

The cross-sectional area A pc of the pressure chamber 2 or 8 is found by multiplication of the high pressure equivalent area A HPm with the balance factorfb. Consequently:

wherein the balance factor fb is normally 1.056 t 0.03 depending upon how strongly the control body 1 shall be pressed against the rotary control face 30 and on the resistance of frictional forces in the seals etc. Suitable seals, such as O-rings, are provided between the seats in the housing portion 5 and the

portions

3, 6, 12 of the control body 1.

The principle of multiplying the control area HP with the balance factor fb is known. However, the enlargement of the cross-sectional area through the pressure chamber at another end of a control body portion by the balance factor fb over the high-pressure equivalent area of the control area of the control faces provides only the overload for pressing the control body 1 against the rotary control face 30. This does not prevent local overheating and local leakage through the control area if no opposition chamber or balancing recesses are provided because the enlargement by balance factor jb does not prevent local overload and local underload in the control area 32. The enlargement of the pressure area at one end of a portion of the control body 1 is therefore suitable only for low pressure applications. In high pressure devices, local overpressing and local underpressing in other regions of the control area 32 leads to welding between the control faces along one half of the control area and to excessive leakage along the other half of the control area. This is the reason why the US. Pat. No. 3,092,036 discloses balancing recesses and the US. Pat. No. 3,561,328 discloses an opposition chamber.

In accordance with the present invention, tilting and the resulting localized overpressing and underpressing of the control body 1 against the rotary control face 30 of the rotor 36 is prevented without resorting to an opposition chamber and balancing recesses.

In order to achieve this, the pressure center of the fluid containing pressure chamber 2 or 8 is located on the axis of the pressure center of the respective high pressure equivalent area of the control area 32. This axis is parallel to the axis of the rotor 36 and the axis or axes of the eccentric portion or portions of the control body 1. The distance (eccentricity) between these axes is shown in FIG. 3 at e 23.

In order to realize such coincidence of locations of the pressure centers, the pressure center of the high pressure equivalent area of the control area 32 has to be found first.

Heretofore, it was assumed that the pressure center of the high pressure equivalent area of the control area 32 is located in the middle between the radii ri and r0, It has been found that such assumption is acceptable for low pressure devices only. In high pressure devices, the reliance on such assumption would lead to local overpressing in one zone of the control area 32 and to underpressing in another zone of the control area 32. This is'due to the fact that the-pressure center of the control area is not located midway between ri and r0.

According to the present invention, the pressure center of the high pressure equivalent area of the control area 32 can be determined by finding the integral median value of the high pressure equivalent area of the control area 32.

Thus, according to this invention, the integral median radius rgc is introduced.

Underrecognition of the area portion dF 28 of FIG. 2, the integral median radius rgc equals:

V lated.

This is achieved by resorting to the following equation:

a 2 1: rgc da L cosa d9:

sina, sina, rgc

a, a (a in arcus values) If in this equation rgc equals 1, then a fixed curve appears over the area which provides the factor fG. For the area extending from 0 to 180, the factor fG is 0.636.

For the actual calculation of the gravity center distance Gc the value fG is to be multiplied with the value rgc. Depending on angle gamma of equation (1), the value of f0 normally varies between 0.4 and 0.7. Only if the distance 00 50 distance between the line 28 and a line 29 is exactly known, for example by the preceding calculation, an efficient and highly reliable control body for operation at a pressure of many hundred atmospheres and even high relative velocity between the control faces 30 and 31 can be built. One of the main reasons why conventional control bodies with eccentric chambers at their outer ends could not work at highest pressures and high relative speeds with maximum efficiency is that such integral calculations of the pressure centers of the control area 32 were not done.

An important requirement for proper design of a control body which embodies the present invention is that, after the distance CC 50 of a pressure center of I the control area 32 is found, the fluid containing pressigned so that the distance gc between their pressure centers and the line 28 equals a distance Gc.

If the fluid handling device operates at all times in one flow direction, so that at all times, the same half zone of the control area 32 is the high pressure zone, only one of the fluid containing pressure chambers 2 and 8, namely that which is associated with the high pressure zone of the control area 32, must have its pressure center at the distance gc from the center line of the rotor 36 because the other pressure chamber is then at all times a low pressure chamber. For a low pressure chamber, the same pressure center is desired but not absolutely necessary because a low pressure device will operate also if the pressure centers Gc land gr: are not aligned and are not located at the same distance from the axis of the rotor.

However, if the fluid handling device is to operate in both directions, so that at different times the flow direction and pressure zones are reversed, it is necessary that the distances Gc between the pressure centers of both pressure chambers 2 and 8 from the line 28 equal the distances Gc between the line 28 and the pressure centers of the control area 32. ln such devices, each half zone of the control area 32 has a pressure center at a distance GL from the center line and the two pressure centers are located opposite each other. The pres- I sure center gc of chamber 2 is then located on an axis which is parallel to the axis of the rotor 36 and is disposed at a distance Gc 50 from the center line of the rotor 36.

The pressure center gc of the fluidcontaining pressure chamber 8 is then located on an axis which is parallel to the axis of the rotor 36 and is disposed at the distance Gc from the rotor axis. Since the two half zones of the control area 32 are normally equal and mirror symmetrical to each other, the distances Gc between both pressure centers of the control area 32 and the rotor axis are equal and these pressure centers are mirror symmetrical to each other. The distances gc between the pressure centers of fluid pressure chambers 2 and 8 and the rotor axis are then also equal and these pressure centers are also mirror symmetrical to each other.

For calculating the chambers 2 and 8 with pressure centers at distance gc from the rotor axis, first their cross-sectional areas Apc A HPmb should be calculated by resorting to the equation (3).

The smallest diameter d of the inner seal face of the inner chamber 2 is commonly a value determined by the design of the device. The median diameter 2m of the seal face between the two pressure chambers 2 and 8 is calculated by adding the cross-sectional area Apc to the cross-sectional area having the diameter d 25. And the outer diameter D 26 of the seal face of the outer pressure chamber 8 is calculated by adding the cross-sectional area Apc of the outer pressure chamber 8 to that of the inner pressure chamber 2 plus the crosssectional area having the diameter d. The crosssectional areas Ape of the pressure chambers 2 and 8 are then equal. lf the calculation is not started with a known diameter d, but if another diametric value is known or arbitrarily selected, the other two diameters can be calculated by resorting to the equation:

Thereby the inner diameter d of inner pressure chamher 2; the outer diameter D of outer pressure chamber 8; the radius m of the median seal face between the two pressure chambers 2 and 8; the outer 2m of the inner pressure chamber 2 and thus the inner diameter 2m of the outer pressure chamber 8 become known so that all dimensions of the pressure chambers 2 and 8 are determined. These values are shown in FIG. 3 by

reference characters

25, 26 and 24.

For the calculation of gravity centers gc of the pres sure chambers 2 and 8, the equations in the commonly owned US. Pat. No. 3,320,897 are utilized.

The US. Pat. No. 3,320,897 discloses a method of calculating the median integral value A of areas within two circles of different radii r and R and an eccentricity e. Since each of the pressure chambers 2 and 8 is bounded by two circles of different radii, namely m and D/2 for chamber 8 and m and (U2 for chamber 2, and both chambers have an eccentricity e whose value gc 23 or 42, see FIG. 3, the equation for the integral median value A (see FIG. 3, reference character 43 representing a sector having an angle tau character 41 in FIG. 3, can be used for calculating the value A of the pressure chamber 2 or 8.

This median integral value A is calculated according to US. Pat. No. 3,320,897 by equation:

sin zx da In this equation, r0 is the'radius of the outer circle of the pressure chamber 2 or 8, namely either m or D/2. The angle tau is the angle of the calculated interval. An interval tau 10 or 5 is normally satisfactory for the calculation. The interval section of angle tau is then bounded by the angle alpha character 40 and the angle alpha minus tau character 40 minus character 41. The eccentricity e corresponds to the desired pres sure center distance gc 23 for the inner pressure chamber 2 and for the outer pressure chamber 8 the eccentricity e in the equations corresponds to 23 plus 42 of FIG. 3.

The next step is to calculate the cross-sectional area of the interval between the angle alpha 40 of FIG. 3

and angle alpha minus tau (tau 41 in FIG. 3). This cross-sectional area is called Kl in accordance with US. Pat. No. 3,320,897 and is calculated by equation From the values of Kl the integral median value of K1 can be found by adding up all calculated intervals of Kl and dividing the thus obtained sum by the number .1 of

the intervals. This is done as follows:

otained with a sufficient degree of accuracy. According to the invention it is now necessary to make the distances Gc' betweenthe pressure centers of the pressure zones in the control area 32 and the axis of the rotor 5 36 equal to the distances go or gc+ between the pres- K sure centers of the fluid containing pressure chambers R, 1

l0

2 and 8 or 2 or 8 and the axis of the rotor 36. Thereby number of im u all measures of the fluid containing pressure chambers 2- and 8 are obtained. A control body 1, if designed ac- For finding out the pressure center f h fl id 10 cording to the above calculations, works suitably even taining pressure chamber 2 or 8, i1 i necessary 10 L at very high pressures and relative velocities between culate the pressure center of each section interval Kl of the Stationary and rotary Control faces 30 and the angle tau. finding the values gc or gc e for the pressure cham- It has been found the pressure center of an interval bets 2 and a number of Values are to be Cal u- Kl is not inthe radial middl between h inner d lated for a number ofdifferent eccentricities e. A curve outer seal faces because the outer part of each interval for 8 Values can then be drawn Over the r i y K1 is wider than its inner part. Consequently, the pres- At that Point, Where 8 is equal to the Suitsure center of an interval K1 is nearer to radially outerable eccentricity f 0f the median Seal face With a radius most part. It is therefore necessary to find the radius rg between the tWO Pressure ehalhbers 2 and 8 is found, on which the pressure center of an interval K1 is 10- whereby the dimensions of the Control y 1 and the cated. The radius rg is the radial integral median value fluid Containing Pressure Chamber 2 a 8 and that through the cross-sectional area of the interval Kl and 0f the Space Which Contains the aid p e re Cha an b l l d as f ll bers in housing portion 5 are defined.

The above developed exact calculations and equal- I I o I I ization of the pressure centers of the control area 32 I i f Z' l (H) and of the fluid containing pressure chambers 2 and 8 Kl K, 540 K,

needs some time. However, this calculation saves years For further Calculation the product Ba which is of development and testing time and expenses and is i therefore the most economical way to design and build equal to the interval area Kl multiplied by the integral no] bod arm emems of this invention median value of go is to be found. In this product, the con y integral median value of gc equals the median integral Instead F Y P out the aboi/e .mennoned exien' value of rg multiplied by cos (alpha minus tau/2). sive calculation, its possible for lim ted pressures in a Thereby it is possible to eliminate K1 as follows: fluid handlingdevice to resort to a simpler calculation 35 of the areal mlddles Ac of the pressure chamber 2 and- 9 /or 8. Such calculation gives however less accurate val- X T) ues and does not determine the pressure centers but 9 only areal centers. It is further applicable only for re- 540 (A- r.=*)cos a (l2) stricted configurations of the control body and its asso- 40 ciated pressure chambers. Such simplified calculation The desired distance gc of the gravity or pressure therefore often results in loss of time without obtaining center of the fluid containing pressure chamber 8 or gc satisfactory final results for high pressure applications. e of the pressure chamber 2 from the axis of the rotor A calculation of the sizes of the pressure chambers 2 36 can now be f und by calcula ing the in egr l ver Ba and 8 for a given size of the control area 32 shows that divided by the integral median value over the interval h entri it e of the median eal face.between the Kl as fOUOWSI pressure chambers 2 and 8 is so big that the outer diameter of the fluid containing pressure chamber 2 extends 8C .l (3) partially radially beyond the outer diameter of the control area 32. Consequently, the eccentric shoulder 3 of or: the control body 1 must also extend in part radially be- 3 'rlL e* 2 Sim! e sin(a0) .8 sinZa e sin2(oz0) {I cos 0 da (I4) 540 4r arc0 arcO Br arc0 Br arcfl '2 KI The equation 14) for finding the distance between yond the outer face of the control area 32. This is the the pressure center of the fluid containing pressure visible result of the invention. chamber 2 or 8 and the axis of the rotor 36 or the axis In order to facilitate the assembly of a control body of the centric portion(s) of the control body 1 is rather I with an eccentric shoulder 3 extending beyond the difficult to integrate. It is however very convenient to outer diameter ofthe control, area 32, it is necessary to calculate with this equation a number ofintervals Z and divide the casing. cover or housing portion 5 into two thereafter divide the thus obtained sum by the number parts or to add a cover means 7 to the housing portion ofintervals Z, as far as the value above the fraction line 5 and fix it thereto after the control body portion 3 is is concerned. Thereafter, the thus obtained value is diinserted the space 4 of the housing portion 5. This is anvided by the median value of K] which was obtained by other visible result and characteristic of this invention.

equation (10). Thereby the value gc of the location of the pressure center of the fluid containing pressure chamber 8 or gc plus 2 for the pressure chamber 2 is.

A further visible result and characteristic of the invention is that the pressure in that portion of the fluid containing pressure chamber 8 which remains radially within the outline of the control area 32 presses against the portion 6 of the control body 1 in a direction toward the control face 30 of the rotor 36, while the pressure in that portion of the fluid containing pressure chamber 8, which extends radially beyond the control area 32 presses in the opposite direction away from the rotor 36 towards the outer end of the fluid handling device against the respective portion of the eccentric shoulder 3 of the body 1. This is an important reason why, in accordance with this invention, no overheating in the control clearance 32 can occur even though the 7 pressure chamber 8 extends partially beyond the outline of the control clearance 32.

The control body arrangement of the invention operates effectively and reliably at all desired pressures and velocities of the fluid handling device, thereby improving its effectiveness, reliability and power. Many thou sand hours of operation under high pressures and rotary velocities have been actually obtained.

It is known that friction between two faces which slide along each other is proportional to the force with which the faces are pressed together. If the friction is x at a certain pressure, then the friction would be 10X at a ten times higher pressure. If however, the control body arrangement is designed and built in accordance with this invention, the aforediscussed laws regarding the friction do not apply. The floating of the stationary control face 31 along the rotary control face 30 insures such smooth running of the face 30 that the friction increases only l.6 to 1.8 times if the pressure increases ten times. This has been found by actual testing of the control bodies of this invention. At same time. the leakage through the control clearance 32 can be kept so small that it does not exceed the internal compression loss of oil during flow through the fluid handling device.

Consequently, the efficiency of the control body arrangement of the invention does not decrease if the pressure in the fluid handling device increases. On the contrary, an increase in pressure brings about a considerable increase in efficiency and power of the fluid handling device.

The divided casing portion or cover 7 is attached to or inserted into the housing portion 5 for confining the

control body portions

12, 3 and 6 therein and to partially close the fluid containing pressure chamber 8 in the axial direction towards the rotor 36 or the interior 'of the housing 5.

1 claim:

1. In a fluid handling device, a combination comprising a housing having inlet and outlet parts for admission and evacuation of fluid; 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; and a control body axially movably received in said housing and having a second control face adjacent to and defining with said first control .face a narrow control clearance, said body including at least one larger-diameter first cylindrical portion coaxial with said rotor and at least one smallerdiameter second cylindrical portion which is eccentric with respect to said rotor and extends in part radially beyond at least one of said control faces, said cylindrical portions having end faces facing away from said rotor and defining with said housing two fluid-filled pressure chambers communicating with said ports whereby the fluid in at least a portion of at least one of said chambers urges said body toward said rotor, said body further having second passages alternatingly connecting said first passages with said inlet and outlet ports when said rotor rotates in said housing, said control clearance including two pressure zones each having a first gravity center and each of said pressure chambers having a second gravity center, each of said gravity center being radially spaced from the axis of said rotor and each of said second gravity centers being aligned with one of said first gravity centers.

2. A combination as defined in claim 1, wherein said control faces are ring-shaped and have identical outer diameters.

3. A combination as defined in claim 1, wherein the area of one of said pressure zones is greater than the area of the other of said pressure zones.

4. A combination as defined in claim 1, wherein the maximum dimension of said body as considered in the axial direction of said rotor is less than the maximum dimension of said body as considered in the radial direction of said rotor.

5. Acombination as defined in claim 1, wherein the eccentricity of said second cylindrical portion of said body with respect to said rotor is less than the distance between one of said gravity centers and the rotor axis.

6. A combination as defined in claim 1, wherein said pressure zones are substantially mirror symmetrical to each other with respect to a plane including the axis of said rotor.

7. A combination as defined in claim 1, wherein said body has limited freedom of tilting movement in said housing so as to maintain said second control surface in substantial parallelism with said first control face.

8. A combination as defined in claim 1, wherein the fluid in that control chamber which is defined in part by said second cylindrical portion acts upon the radially outermost portion of the end face of said second cylindrical portion in a direction to urge said body away from said rotor and upon the remaining portion of said last mentioned end face in a direction to urge said body toward said rotor.

9. A combination as defined in claim 12, wherein said housing comprises a plurality of separable portions.

10. A combination as defined in claim 9, wherein one of said portions of said housing is of annular shape and is adjacent to one of said pressure chambers.

11. A combination as defined in claim 10, wherein said one portion of said housing surrounds one of said cylindrical portions.

Claims

1. In a fluid handling device, a combination comprising a housing having inlet and outlet parts for admission and evacuation of fluid; 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; and a control body axially movably received in said housing and having a second control face adjacent tO and defining with said first control face a narrow control clearance, said body including at least one larger-diameter first cylindrical portion coaxial with said rotor and at least one smallerdiameter second cylindrical portion which is eccentric with respect to said rotor and extends in part radially beyond at least one of said control faces, said cylindrical portions having end faces facing away from said rotor and defining with said housing two fluid-filled pressure chambers communicating with said ports whereby the fluid in at least a portion of at least one of said chambers urges said body toward said rotor, said body further having second passages alternatingly connecting said first passages with said inlet and outlet ports when said rotor rotates in said housing, said control clearance including two pressure zones each having a first gravity center and each of said pressure chambers having a second gravity center, each of said gravity center being radially spaced from the axis of said rotor and each of said second gravity centers being aligned with one of said first gravity centers.

5. A combination as defined in claim 1, wherein the eccentricity of said second cylindrical portion of said body with respect to said rotor is less than the distance between one of said gravity centers and the rotor axis.