US2149337A

US2149337A - Rotary pump

Info

Publication number: US2149337A
Application number: US756989A
Authority: US
Inventors: Deming Robert
Original assignee: DEMING ROTARY PUMP Co
Current assignee: DEMING ROTARY PUMP Co
Priority date: 1934-12-11
Filing date: 1934-12-11
Publication date: 1939-03-07
Anticipated expiration: 1956-03-07

Description

. March 7, 1939. R. bEMING "2,149,337

' ROTARY PUMP Filed Dec. 11, 1954 2 Sheets-Sheet 1 v INVENTOR I Robert Demin F17. 5 t Y v .7 W Mafia ATTORNEYS March 7, 1939.

R DEMING ROTARY PUMP Filed Dec. 11, 19:54

2 Sheets-Sheet 2 Robe BY kWcCumvl-i OR Demi n ATTORNEY 6 Patented Mar. 7, 1939 I ROTARY PUMP 1mm Deming, Norwood, Ohio, assignor to Dem- I ing. Rotary Pump -Company,'Cincinnati, Ohio a corporation of Ohio Application December 11, 1934, Serial No. 756,989

12 Claims. (01. 103-436) This invention relates to fluid pressure or vacv uum pumps of the rotary piston type and has for its object to provide a pump in which the leakage of the fluid being pumped past relatively moving parts of the pump is reduced to a minimum, and in which the pressure in the high pressure side of the pump chamber is utilized to maintain a fluid-tight engagement between the vanes which act as pistons .or sea-ling members and the relatively movable parts with which the engage, so as to reduce leakage past such pistons or sealing members from the high pressure side to the low pressure side ofthe pump chamber. A further object of the invention is to'provide a pump in which the relatively movable parts are provided with sealing grooves so disposed as to effectively check flow of the fluid being pumped between the relatively'movable contacting surfaces of the pump elements.

[ A further object is to so conduct, apply and utilize the normal forces generated by the pump- .ing operation as to make the sealing provisions more effective.

With the'above. andother objects in view, the

A; invention may be said to comprise the pump as illustrated in the accompanying drawings hereinafter described and particularly-set forth in the appended claims, together with such variations.

and modifications thereof as will'be apparent to one'skilled in the art to which] the invention appertains.

Reference should be had to the accompanying drawings forminga part of this specification,

in which:

Figure 1 is a transverse section through a ro-,

tary pump embodying the invention,- a section being taken at right angles to the axis of the pump and through the body of the rotor;

Fig. 2 is a perspective view of the body portion of a pump vane;

- Fig. 3 is a perspective view of a sealing shoe with a convex working face for engagement interiorly with a cylindrical surface;

Fig. 4 is a perspective view of a sealing shoe witha concave working face for engagement exteriorly with a cylindrical surface;

Fig. 5 is a diagrammatic view showing the pressures exerted upon the shoes;

.Fig. 6 is a diagrammatic view showing the pressures exerted upon the vane;

. Fig. 'l is a sectional view showing a pump with a one-piece vane:

Fig. Bis a perspective view of theone-piece' vane shownin Fig. 7; I

Fig. 9 is a diagrammatic view showing the effect the axis of rotation,; are referred -to as end of centrifugal force on a'vane disposed at an angle to the radius;

Fig. 10 is a view similar to Fig. 9 showing the vane oppositely inclined; and

Fig. 11 is a sectional view showing a multivane 5 pump embodying the invention.

An important feature of the present invention is the provision of an efiective seal between relatively sliding parts of a rotary pump such as a sliding vane or an oscillatable shoe, and the parts 10 with which the vane or shoe has sliding contact. In the following description, it is to be understood that by working face of a vane or shoe, is meant that face of the vane or shoe which engages with a part of the pump which is rela- 15 tively rotatable with respect to the part which carries the vane or shoe. The faces of the shoe or vane perpendicular to faces.

The faces of the vane or shoe opposite the working face, are referred to as "bottom faces".

The side of the shoe or vane disposed transversely to the direction of. rotation-and which receives the initial pressure from the fluid being pumped, is referred to as "the high pressure side or face, and the corresponding side of. the recess in which the shoe or vane is mounted is referred to as the high pressure side or face. The face of a shoe or recess opposite the high pressure side 30 or face is referred to as the low pressure face or side. Grooves, channels, recesses, or spaces provided for the purpose of applying and directing pressures forces are sometimes referred to herein as pressure pockets. v 35 'In Figure 1 of the drawings, there is shown a pump housing I enclosing a cylindrical chamber in which there is mounted a rotor 2, the axis 3 of which is disposed eccentrically with respect to the cylindrical housing, the rotor 2 being of 40 cylindrical form and of smaller diameter than the chamber in which it is mounted. The rotor is positioned withits periphery in contact with the chamber wall along a longitudinal tangent line to provide a seal between the inlet and outlet 45 ports. 'The rotor has a longitudinal slot 4 in which is slidably'mounted the body portion 5 of a sealing vane, the working face of which is provided with an oscillatable shoe 6 having an arcuate convex bottom or seating face I which fits 50 in an arcuate recess in the body portion 5.

The shoe I has'a convex working. face- 8, the radius of which*corresponds to that ofthe cy lindrical chamber, and which contacts with the wall of the cylindrical chamber. ,I'he bottom I or seating face I of the shoe 6 is of shorter radius than the working face 8 and intersects the working face at'opposite sides of the shoe.

During operation of. the pump the vane consisting of the slidable body portion 5 and oscillatable shoe 6 is pressed outwardly towards the cylindrical wall of the pump chamber, to maintain the working face 8 of the shoe incontact throughout its width and lengthwith the cylindrical wall of the chamber.

fluid from the inlet to the outlet of the pump.

In order to provide a more eifective seal between-the rotor and the chamber wall along the line of contact between the rotor and wall, an oscillatable shoe 9 is mounted in a recess in the housing and this shoe has an arcuate convex bottom or seating face ill which fits in an arcu ate recess in the housing wall, and anarcuate concave working face H of the same radius as the rotor which bears against the surface of the rotor. The bottom or seating face in is a shorter radius than the working face ii and intersects the working face at opposite sides of the shoe.

'The shoe 9 maintains contactvwith the rotor to provide a more eife'ctive seal between the inlet and outlet.

As shown in Fig. 2 of the drawings, the body portion of the vane has parallel longitudinal grooves i2 on its low pressure face and'longitudinal channels it on the high pressure, face thereof. On the high pressure side there is at least one passage i5'which opens at one end to the shoe seating recess and at its opposite end to the bottom of the vane. The passage I5 is intersected by the channels 14 which provide pressure pockets along the high pressure face of the vane for fluid under pressure which acts to press the vane toward the low pressure wallv of its recess or slot so that the sealing grooves l2 are effective to prevent leakage of fluid from the bottom of the recess through the space between pressureypockets on the high pressure side of the low pressurmwall of the vane and the-adjacent wall of the recess. The ends of the body portion 5 of the vane are provided with diagonal grooves or channels i6 which serve to retard leakage past the ends bf the vane. The diagonal channels IQ also receive fluid under pressure which exerts a force on the vane toward the low pressure wall. The grooves or channels it aid in scavenging'to the high pressure side the space between the bottom of the vane and the bottom of the slot 4 when the vane is retreating'into the'slot.

As shown in Fig. 3 of the drawings, the shoe lihas longitudinal channels I! on the high pressure side of its working face 8 and longitudinal channels [8 on the high pressure side of its seating face I. The channels I! and I8 are intersected by at least one channel l9 intermediate thee'nds of the shoeanddisposed at right angles to the channels I! and iii. The channel I9 is open to the high pressure side of the vane and registers with. the passage [5 of the body portion 5 of' the vane todeliver fluid under pressure to the channels it and to the bottom of the slot 4. Thegr'ooves or channels l1 and" provide the shoe, and the channel l9, which opens to the interior ofthe' pump. chamber on the pressure side of the v'ane supplies fluid under pressure to these grooves or channels as well as to the passage l5v which conducts fluid under pressure to the channel Mon the high pressure face of the body portion of the vane and to the bottom of The vane pr o-. vides a partition moving with the rotor to force the slot 4'.- f The shoe 6 also has longitudinal sealing grooves 20 on the low pressure side of the working face 8 and. similar grooves 2| on the low pressure side of the bottom or seating face 1. One or both end faces of the shoe 6 may be provided with transverse sealing grooves 22 to impede the-flow between the end face of the shoe and the end walls of the pump chamber.

Referring to Fig. 4 of the drawings, the shoe 9 has longitudinal channels 24 forming pressure pockets on the high pressure side of its working face H and longitudinal channels 25' forming pressure pockets on the seating face I0 thereof.

Channels

24 and 25 are intersected by at least one channel '26 intermediate the ends of the shoe which extends substantially at right angles to the grooves or

channels

24 and 25. The channel 26 opens to the high'pressure side of the shoe 9, and conducts fluid under pressure to the pressure pockets formed by the channels 24' and 25. The shoe 9 has longitudinal sealing grooves 2'2! onthe low pressure side of its working face and similar sealing grooves 28 on the low pressure side of its seating face it.

. to the pressure of the fluid being pumped at each instant of the pumping cycle.

In Figffi of the drawings, the arrows 29 and 30 r indicate the forces applied by thefluid under pressure to the shoes 5 and 9. The force of the fluid under pressure indicated by the arrows 29. is

outwardly of the center of curvature 3| otthe bottom or seating face I of the'shoe 6 and tends.

to rotate the shoe in a direction to move the leading edge of the shoe inwardly, opposing the frictional drag exerted on the working face 8. Similarly the, fluid pressure on the shoe 9, in-' dicated bythe arrows-30, is outwardly of the center of curvature 32 of the bottom or seating -face ill and tends to rotate the shoe in a direction to move the high pressure side thereof, into the shoe recess. These forces are transmitted tothe faces of the shoes in which the sealing grooves are located, as indicated by the arrows 31, 38 38 and 40, the pressure on the shoes being commensurate' with the pressure under which the vane is working. It should be noted that the low pressure side of the sealing shoe 6 is wedgeshaped so'that the shoe is pressed ag'ainstthe wall of the hbusing, as indicated by the arrows 38, and against the recess wall, as indicated by the arrows 31, so that the sealing grooves in these spaces can effectively impede the leakage of fluid past the shoe. Similarly, the low pressure side faces in which the sealing grooves'are located are pressed against the rotor and the recess wall, as indicated by the a

rows

39 and 40.. v

1of the shoe 9 is wedge-shaped, so that the sur- It will be observed that the high pressure side no ofthe recess in which the-shoes is mounted;

opens to the pump chamberrat or near theline where the'rotor 2 contacts with the wall of the housing,- so that as the shoe 8 comes into contact with the shoe '9 the working faces of both subwardly and the high pressure side of the shoe 8 5 outwardly, a clearance is provided between the opposed sharp edges of the shoes and there is no interference to the passage in the shoe 6 past the shoe 9. b

Figure 6 of the drawings illustrates diagrammatically the forces acting upon a vane. The arrow 42 represents the direction and amount of pressure due to the film of fluid between the face of therotor chamber'and the face of the vane. The arrow 43 represents the force due to the working pressure against the bottom of the-vane of the fluid admitted to the bottom of'the slot 4.

r The

forces

42 and 43 are normally equal and opposed and are equalized. The arrow 44 represents the force-of a spring commensurate with 20 operating conditions, such a spring being used where the speed of rotation and delivery pressure and physical properties of fluid being pumped are such that a force in addition to the centrif- Vugal force and that of fluid pressure is desirable.

25 The arrow 45 represents the added force encountered when'the vane is receding into its slot and scavenging the chamber at the bottom of the slot. This force is a valuable factor as it adds to the pressure making the seal at the 30 working face of the vane during a portion ofrotation in which the fluid is being compressed or delivered.

It will be noted that the vane of the present invention adds to theefliciency and capacity of the pump, since it acts as a piston pump, causing the fluid which has filled the chamber at the bottom of the slot 4 during the outward movement of the vane .to be'discharged against a higher pressure at the delivery side of the vane during the retreating movement of the vane.

The arrow 46 represents a force due to friction.

r The arrow 41 represents a force at the point of application due tothe pressure of the load. The

at its point of application.

In the usual vane pump the force 48 is opposed by a force, indicated by the arrow 49, at a fulcrum point formed by the edge of the slot 4 6n the low pressure side thereof. A force, indicated by the arrow 50,. is also exerted. against the bottom corner of the vane on the high pressure side thereof. The forces 48 and'50 the fulcrum point 49 tend to cant the value in its slot, creating localized pressures. at thepoints of application of the

forces

49 and 50, which are the cause of rapid wear of the. vane and slotand quick deterioration .in' efliciency of operation. I The present invention provides means for more advantageously distributing the forces acting, on

60 .the vane so as to increase the efliciency and reduce wear on the sliding parts. The arrow represents the force exerted on the vane by the fluid under pressure in the pressure pocket channels l4. -The;pres sure, indicated byAzhe arrow 65 5|, ismore than sumcient to eliminate the pressure 50 of the bottom corner of the vane against- .the high pressure-wall, and distributes the pressure of the vane over the low pressure wall of the slot-so as to eliminate the fulcruming pressure '70 indicated by the arrow. The wear is thus distributed over thesurfaces'of the vaneand slot arrow .48 represents the resultant of 45 and 41.

, h balanced against The arrow 53 represents the resultant of forces indicated by the

arrows

42, 43, 44 and 45 acting 1 longitudinally of the vane. The center of weight of the vane is indicated at 54 and the arrow 55 represents the centrifugal force derived therefrom, and this force is also exerted radially.

Variationsin dimensions and speed of rotationalter the force 55. The'principie of the present invention is applicable to pumps operating at high speed or at low speed, and for pumping gases or liquids.

vane. This pump has a housing 10 and a rotor H within the housing which carries a sliding vane 12 mounted in a slot 13 in the rotor. The

vane'12 has a convex working face 14 which is.

provided with longitudinal. sealing grooves 16 on the low pressure face thereof and with pressure pocket channels I1 extending iongitudinally of the high pressure face near the bottom thereof. A passage 18 adjacent the high pressure face of' the vane extends from the working face 14 to the bottom of the vane and intersects each of the channels 11. The upper end of the passage 18 has a lateral opening 19 to the high pressure face of the vane so-that fluid under pressure passes through the passage 18 to each I of the pressure pocket channels 11 and to the space at the bottom of the slot between the bottom of the slot and thebottom face of the vane, so that, during operation of the pump, lateral pressure is applied to the high pressure face of the vane near the bottom edge thereof, and radial pressure is also applied to the bottom face of the vane to force .the same outwardly against the wall of the pump chamber. Diagonal grooves '80 are provided on the ends of the vane to impede leakage of fluid past the ends of the vane between the ends of the vane and the end walls of the pump chamber, the grooves 8llalso serving to apply an additional lateral thrust to the vane andto facilitate the escape of fluid from the bottom of the-slotduring the receding movement of the vane to the high pressure side.

In some pumps it maybe desirable to modify action'of centrifugal force upon the vane by disposing the slots, in which the'vanes slide, at an angle to the radius. If it. is desired to reduce the high frictional resistance due to the load or speed of rotation, or both, the vane may be placed as shown diagrammatically in, Fig. 9, with its working face advanced relative to the direction of rotation. The force 85 representing the thrust of the fluid. being pumped in a direction' perpendicular to a radius is shown resolved'into its components, and 81, component 86 being perpendicular to the vane, and component .81 acting inwardly in a directionof movement ofthe vane. The centrifugal force at' the center of. weight 54 is shown resolved into its components 8 8 and 59; component. acting perpendicular to the vane, and component" acting outward1y.- w

The componentst'l and]! act'in' the same line but in opposite directions.- They must be subtracted, and the resultant outward force which causes frictional resistance is reduced, as 'desired, by thedegree of the angle at which the vane is placed. Also, it is obvious that a resiiltant of forces .86- and 58 maybe found perdirection of movement of the vane are not 019- pendicular to the radius and that it will be less than the coipresponding resultant on the radial vane illustrated in Fig. 6. Since this force perpendicular to the radius is a measure of the torque, it isapparent that less power will be required to operate a: pump having its vane or vanes inclined as shown in Fig. 9.

The force 98 is added to the force 5B which holds the vane against the low pressure wall of its recess surface to surface, due to the fact that the center of weight is transferred from a position on the high pressure side to a position on-the low pressure side of aradial line passing through the fulcrum t9.

In Fig. 10 of the drawings the angularity of the vane is the reverse of that'shown inFig. 9, the thrust of the fluid being pumped which is indicated by the arrow 85 being resolved into components 86*,and 81 and the centrifugal force at thecenter of weight indicated by the arrow '55 being resolved into

components

88 and 89;

In this case the components 81 and 89" in the posed as in Fig. 9 but act in the same direction and their resultant is their sum instead of their difference.

It is to be understood that the pressure pockets at the high pressure sides of the vane and shoe and the passages for conducting fluid from the pump chamber to, such pockets may be formed in various ways, it being essential only that such pockets and passages be so disposed as to cause the fluid to exert an effective pressure against the grooved sealing faces.

' InFlg. 11 of the drawings there is shown a multi-vane pump having a casing 92 with :a cylindrical chamber 99, a rotor 96 disposed eccentrically of the chamber and having a series of vanes 95 which are mounted in slots 98 in the rotor which are disposed. at an angle to radii of the rotor. The casing and vane are provided with

shoes

97 and 98 which may be of the same construction as the

shoes

8 and 9 previously described; 'Iheshoe 98 may be wider than the vane in which case the rotor has recesses 99 at the high pressure sides of its slots to accommodate the shoes. The vanes 95 have their inner ends tapered, providing an inclined face too which is subjected to fluid pressurewhich. acts ,to press the vane against the low pressure wall of its slot. The inclined face 100 provides a pressure pocket on the high pressure side of'the vane which is in communication at all times with the bottom of the slot to which fluid under pressureis conducted by channels or passages; as in the modifications previously described.

It will be apparent that the present invention provides a simple construction in which the various forces acting onthe. vanes and shoes are advantageously distributed to lessen sliding friction and wear on the parts and to provide .an effective seal.

Furthermore, it i to be understood that the particular form of apparatus shown and de- -scribed, and the particular procedure set forth, are presented-for purposes of explanation and illustration and that various modifications of said apparatus and procedure can be made withhavingaslidingiltin out departing from my invention as defined in the-appended claims.

What I claim is:

u i. In a pumpof the rotary piston type having relativelfrotatable elements forming walls of. the pump chamber, .anda movable sealing member ments and provided with a face engaging the sura recess of-o'ne of eleface of a relatively rotatable elementand substantially conforming to said surface to maintain a seal between high pressure and low pressure portions of the pump chamber, said sealing member and said recess inwhich it is mounted being shaped to provide spaced pressure pockets be- 4 tween the member and its recess at the high pressure and under sides of said member, said sealing member and its recess having bearing surfaces extending the full length of said member and in sliding and sealing engagement on the low pres-. sure side thereof, said sealing member having a passage for fluid under pressure-opening at oneend to the pump chamber on the high pressure side of said member and communicating with said pockets to maintain a fluid pressure therein substantially the same as in the high pressure portion of the pump chamber to press said member against the relatively rotatable element and against the low pressure side of its recess.

2. In a pump of the rotary piston type having relatively rotatable elements forming. walls of the pump chamber, and a movable sealing memher having a sliding flt in a recess of one of said elements and provided with a face engaging the surface of a relatively rotatable element and sub- 'stantially conforming to said surface to maintainportions of the pump chamber, said member hav ing parallel sealing grooves extending through: out its length in the face thereof which engages the relatively rotatable element and also in the a seal between high pressure and low pressure face thereof which engages the wall of the re-= I cess on thelow pressure side, said sealing member and said recess in which it is mounted being 'shaped to provide spaced pressure pockets bepassagefor fluid under pressure opening at one end to the pump chamber on the high pressure side of saidmember and communicating with said pockets to maintain a fluid pressure thereinsubstantially the same as in the high pressure portion of the pump chamber to press said member against the relatively rotatable element and against the low pressure side of its recess.

3. A'pump of the-rotary piston type having relatively rotatable elements forming walls of the pump chamber, a member slidably mounted in of a relatively rotatable element and substantially conforming to said surface to maintain a.

- which engages the recesswallbn the high pressure side and a passage communicating with said a recess of one element and engaging the surface channels and opening to the pump chamber .on

the high pressure side of said member.

4. A pump of the rotary piston type having relatively rotatable elements forming walls of a pump-chamber, one of said elements having a slot, aivane in said slot for maintaining a seal .between high pressure andlow pressure portions of the pump chamber, said vane comprising a body portion slidable in said slot and having an arcuate recess and a shoe havingan arcuate face 75 seating in said recess whereby the shoe is adapted to rock laterally in said arcuate recess, said shoe being interposed between the said body portion and a relatively. rotatable element, means for applying fluid pressure to the bottom and low pressure side of the body portion of the vane, and

means including passages formed between the arcuate face of the shoe and the arcuate recess' in the vane for applying fluid pressure to the bottom of said shoe, and sealing grooves for impeding the flow of fluid past said vane between 'the shoe and relatively rotatable member, between the shoe and. the low pressure side of its recess and between the body portion of the vane and the low pressure side of the slot.

cl 5. A pump of the rotary piston type having relatively rotatable elements forming walls of a pump chamber, one of said elements having a Y slot, a vane in said slot for maintaining a seal 20. between high pressure and low pressure portions of the pump chamber, said vane comprising a body portion slidable in said slotand having an ,arcuate recess and a shoe mounted to rock laterally in said arcuate recess and interposed be- 25 tween the said body portion and a relatively rotatableelement, the body portion of the vane having a passage extending from the arcuate recess to the bottom of the vane, the shoe havlng an arcuate bottom seated in said recess, means 30 forming a-transverse passageextending partially across the bottom of the shoe from the high pressure side thereof andregistering with the passage in the body portion of the vane to maintain communication between thebottom of the slot '35 and'the portion of the pump chamber immedi- "ately in front of the vane, grooves longitudinal,

with respect to the vane impeding flow of fluid between the vane and low pressure side of its slot and between the low pressure sides of, the seat ing and working faces of the shoe and surfaces engaged thereby, pressure pockets-on the seating and working faces of the slide at the high pressureside which communicate with said transverse passage, and a pressure pocket on the high 5 pressure side of the. body portion of the vane which communicates with the passage in the body portion of the vane. a Y

6. A pump of the rotary piston type having relatively rotatable elements forming walls of a 5'0 pump chamber, one of said elements having a slot opening to the space between said elements,

, a vane 'slidably fitting in said'slot and having a working face slidably-engaging the other of said elements'to'maintain a seal between high pres- 55' sure and low pressure portions of the pump 'chamber, said vane having a plurality of parallel sealing grooves on its working face, a plurality of parallel sealing grooves on its low pressure side inwardly of the open end of the slot and a recess.

( forming a pressure pocket on the high pressure side of the vane inwardly of the open end of the slot, anda passage in said vane opening to the high pressure side thereof adjacent the working face, said passage'extending'to the bottom of the pocket, Y I l v 3 'l. A pump of, the rotary piston type having relatively'rotatable elementsforming walls of a 70 pump chamber, one ofsaid elements having a slot,

'a' vane in said slot for maintaining a seal between high pressure and low-pressure portions .of the pump chamber, said vane having sealing grooves on its working face" and itslow pressure- 75 side, diagonal grooves. on its end faces, pressure the high pressure side of the an arcuate working vane and communicating with said pressure pockets on its high pressure side, and a passage communicating with said pockets and opening to vane-adjacent its working face. I

'8. In a-pump of the character described, relatively rotatable elements forming walls of a pump chamber, one of said elements having an arcuate surface, the other of said elements having an arcuate recess with a radius of curvature less than that of said surfac'e,. a sealing shoe having an arcuate seating face fltting in said recess and an arcuate working face which conforms to said arcuate surface to provide a seal between high and low pressure portions of the pump chamber, each of. said arcuate faces of the shoe having a transverse channel extending from the high pressure side thereof partially across said face, and longitudinal grooves in said faces intersecting said channels and forming pressure pobkets on the working and seating faces'of the shoe adjacent the high pressure side thereof.

9. In a pump of the character described, relatively rotatable elements forming walls of a pump chamber, one of said elements having an arcuate .surface, the other of said elements having an arcuate recess with a radius of curvature less than that of said surface, a sealing shoe having an arcuate seating face fitting in said recess and 'an arcuate working face which conforms to said arcuate-surface to provide a seal between high and low pressure portions of the pump chamber, each of said arcuate faces of the shoe having a transber and the other being of smaller diameter and forming the cylindrical inner wall of the chamber and tangentially disposed with respect to the outer wall, a vane carried by one element and comprising a slidably mounted body portion pro-\ vided with an arcuate recess and a shoe having an arcuate face'of a curvature corresponding to that of the recess and "seating in said recess and face of the. same curvature as the relatively rotatable element, an arcuate recess in the other element and an arcuate shoe in 'said recess-having a seating face conforming to said recess and a working face conforming to the surface'of the rotating element, thearcuate seating face ofsaid last named shoe being slidable in the arcuate recess in a direction trans- I versely of the axis of the seating faceand adapt- 1 ed to turn aboutthe axis of its seating face, and

means for applying fluid pressure, to arcuate faces of said'shoes in directions tending to ro-. tateeach shoe on its seat in a direction'to relieve on the.r otating element approaches the shoe on the stationary element.

11. A rotary piston pump having relatively rotatable, 'eccentrically disposed elements, one

- the pressure on the working face adjacent the w highpressure side'of the shoe whereby the 6pposed edges of the shoes are retracted asthe shoe and forming the cylindrical inner wall of the chamber and tangentially disposed with respect to the outer wall, a vane carriedby one element and comprising a slidably mounted body portion provided with an arcuate recess and a shoe having an arcuate face of a curvature corresponding to that of the recess and seating in said recess and an arcuate working face of the same curvature as the relatively rotatableelement, an arcuate recess in the'other element and an armate shoe in said recess having a seating face conforming to said recess and a working face conforming to the surface of the rotating element, each shoe having pressure pockets adjacent its high pressure edge adapted to receive fluid under pressure which tends to rotate the shoe about the center 01 curvature of its seating face.

12. A rotary piston pump having relatively rotatable, eccentrically disposed elements, one

forming the cylindrical outer wall of the pump chamber and the other being of smaller diameter and forming the cylindrical inner wall of the chamber and tangentially disposed with respect to the enter wall, one of said elements having a slot, a vane slidably mounted in the slot andengaging the relatively rotatable element, said vane having a passage opening at one end at the high pressure side of the vane to the pump chamber and at the other end to the bottom of said slot whereby said vane acts as a piston pump during a relative rotation of said elements, said vane having grooves on its end faces which extend diagonallynfrom the bottom to the high pressure side of the \vane to impede flow toward the low pressure side and to conduct fluid to the high pressure side of the vane.

ROBERT DEMING.