US2642802A

US2642802A - Dual rotary pump for power transmissions

Info

Publication number: US2642802A
Application number: US65157A
Authority: US
Inventors: Duncan B Gardiner
Original assignee: Vickers Inc
Current assignee: Vickers Inc
Priority date: 1948-12-14
Filing date: 1948-12-14
Publication date: 1953-06-23
Anticipated expiration: 1970-06-23

Description

INVENTOR. DUNCAN B. GARDI N ER BY ATTORNEY @4- smu snm l D. B. GARDINER DUAL ROTARY PUMP FOR POWER musursszons FIG. 2

June 23, 1953 Filed Dec 14, 1948 June 1953 D. a. GARDINER 3 5 mm. ROTARY PUMP FOR Pom mmxssron's Filed Dec. 14, 1948 DUNCAN B. GARDINER ATTORNEY 4 Sheets-Sheet 2 Q I INVENTOR.

o. a sARomsn pwu. ROTARY PUIIP FOR PQIER TRANS||IS8ION.. I

Jume 23, 1953 t Quota-Shut 32 Filed Dec. 14, 199

DUNCAN B. GARDI N ER ATTORN EY June 23, 1953 v g; GARDNER 2,642,8 2

mm. ROTARY PUIIP FOR Pom Filed 1m. 14, 1948. simzwsum 4 FIG. 8

yaw, 1 11 I INVENTOR. DUNCAN B. GARDI NER ATTORN EY Patented June 23, 1953 orrics DUAL ROTARY PUMP FOR POWER TRANSMISSIONS Duncan B. Gardiner, Detroit, Mich., assignor to Vickers Incorporated, Detroit, Mich., a. corporation of Michigan Application December 14, 1948, Serial No. 65,157

(Cl. l 34) 11 Claims.

This invention relates to power transmissions and is particularly applicable to those of the type comprising two or more fluid pressureenergy translating devices, one of which may function as a pump and another as a fluid motor.

The invention is generally concerned with multiple pumping units and is more particularly concerned with a dual pumping unit of the rotary vane type. Unitsof this type are adaptable for use in hydraulic power transmissions'having a plurality of fluid motors which must be separately driven. Although each pumping unit is separately connected to a fluid motor for separately operating the same, the pumps may be driven from a common prime mover and supplied with fluid from a single fluid supply source. Multiple pumping units of this type are also utilized with control valves adapted to cooperate therewith in circuits wherein a large volume of fluid is required against a fairly low pressure and at other times a smaller volume of fluid is required against a high pressure. The latter type of circuit is common in machine tool drives where a large volume of fluid is required for rapidly advancing a machine part to its working position and where a small volume of fluid is required for slowly feeding the part on its working stroke. "In addition, there are many difier- I ent hydraulic circuits which may utilize a plurality of pumps in various other ways.

Multiple pumping units have been provided for circuits of the type mentioned which have been proven eflicient and which are moreeconomical than the use of separate pumps because of combining in one compact unitary structure the multiple pumping units required for the purposes of the circuit. However, because of the great variety of circuits in which multiple pumpunits may be incorporated and the diflerent volume and pressure requirements of each circuit it has been necessary to provide a variety of multiple pumping unitsto meet the various circuit volume and pressure requirements. One popular type of multiple pumping unit of the dual rotary vane type comprises two pumping units identical as to construction, each of which comprises a cam ring having an inner elliptical I 2 retained in their respective pumping recesses by separate means, usually by. head plates which have to be independently mounted and adapted to fit snugly in their recesses to insure equal distribution of clamping pressure over their respective units. 'In some cases, in addition to separate ihead plates, bearing plates'are provided which are mounted independently of the head plate so as to avoid adjustment which would interfere with the clamping pressure and cause binding. a

The present invention obviatesthe use of separate bushings for each pumpingunit by providing a valve plate common to both pumping units and also avoids the use of separate head plates by utilizing a novel pressure head and ing engagement with the valve plate. The present invention avoids the disadvantages of other constructions where itiisnecessary to mechanically adjust the clamping pressure to provide fluid sealing engagement of the rotary pumping units. In this latter type of. construction, well meaning, but negligent workmen frequently .pull up exposed bolts for adjusting head plates too tightly resulting in binding and failure of the pumping units. I

It is, therefore an object of this invention to provide an improved multiple pumping unit of the rotary vane type.

It is also an object of this invention to provide a dual rotary vane pumping unit which'is readily adaptable for interchangeability to meet a variety of circuit pressure and volume requirements. I

s It is also an object of this invention topro vide a dual rotary vane pumping unit which eliminates the use of separate supporting bushings for each pumping unit.

s It is a further object of this invention to providea dual rotary vane pumping unit'which also eliminates the use of any mechanical adjustable clamping means for maintaining the rotary pumping units in fluid, sealing engagement against their respective cooperating stationary bearing surfaces.

.It is an additional object of this'invention' to eliminate separate bushing elements for each'rotary vane pumping unit by providing a valve plate common to both rotors and to provide a fluid sealing engagement of the rotors with the valve plate by pressure responsive means.

It is also an object of this invention to provide a dual rotary vane pumping unit which is of an improved, simplified, compact, and reliable construction, which may be produced at low cost and which because of interchangeable features will meet a variety of circuit requirements.

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

In the drawings:

Figure l is a longitudinal sectional view of a preferred form of the present invention on line ll of Figure 2.

Figure 2 is a top view of the present invention.

Figure 3 is a sectional view on line 3-3 of Figure l.

Figure 4 is a sectional view on line 4-4 of Figure 1.

Figure 5 is a sectional view on line 5--5 of Figure 1.

Figure 6 is a sectional view on line 6--6 of Figure 1.

Figure I is a partial sectional view on line l1 of Figure 5.

Figure 8 is a sectional view on line 8-8 of Figure 1.

Figure 9 is a partial sectional view on line 9-9 of Figure 3.

Figure 10 is a partial sectional view on line l0l 8 of Figure 3.

Referring to Figure 1, there is shown a dual rotary pumping unit l0 having a casing which preferably is in three sections consisting of a right end section l2, a left end section l4, and a center section I6, all of which are connected together by suitable screws 18, two of which are shown in Figure 2. The right end section I2 is provided with a common inlet supply flange and the left end section with independent

outlet delivery flanges

22 and 24 for two pumping units of identical construction but of different sizes, one of which is mounted in the center section l6 and indicated by the numeral 26, and the other of which is mounted in the left end section [4 and indicated by the numeral 28.

The

pumping units

26 and 28, shown more clearly in Figures 4 and 8, respectively, comprise

rotors

30 and 32, each of which carry a plurality of reciprocating vanes 34 held in bearing contact with the inner contours of their respective cam rings l6 and 38, the former of which comprises the center section of the unitary casing. The

rotors

30 and 32 are mounted on a common drive shaft which is splined at 42 and 44 to provide a driving connection for each of the pumping units. The casing section [2 carries bearings 46 and 48 in which the shaft 40 is rotatably mounted and a suitable sealing ring indicated by the numeral 50.

The inner contours of the cam rings [6 and 38, which are respectively indicated by the numerals 52 and 54, are generally elliptical in shape to provide

balanced working chambers

56 and 58 for the larger pumping unit and balanced working chambers 60 and 62 for the smaller unit.

The right end casing section is provided with an inlet passage indicated by the numeral 64 which registers with the inlet connection 20 (Figure 1) and which is branched, said branches being indicated by the numerals 65 and 61 and each being respectively provided with an arcuate shaped port at its termination indicated by the

numerals

66 and 68 and shown in Figure 3,

The

ports

66 and 68 register, respectively, with 4 a portion of the

working chambers

56 and 58 of the larger pumping unit, and also register, respectively, with a plurality of port holes 10 and a duplicate plurality of port holes 12 in the cam ring IS, the latter of which are respectively located immediately adjacent to the

working chambers

56 and 58. The series of port holes 10 and '12 which extend completely through the ring l6 cooperate, respectively, with a pair of arcuate shaped inlet ports 18 and in a fluid distributing valve plate or cheek plate 82 (Figures 1 and 5) which is mounted in the left end casing section 14 so as to provide a supply of fluid to the inlet side of the smaller pumping unit.

As shown in Figures 1 and 3, the plurality of port holes 10 and I2 register respectively on the right side of the cam ring I6 with

inlet ports

66 and 68 of the casing section l2 and on the opposite side register, respectively, with the

arcuate inlet ports

18 and 88 of the valve plate 82.

Referring to Figures 1 and 5, a curved passage 84 of the valve plate 82 connects the arcuate inlet port 18 with an arcuate inlet port 86 on the opposite side of the valve plate 82 while a duplicate curved passage 88 connects the arcuate inlet port 80 with an arcuate inlet port 90 on the opposite face of the valve plate 82. The

arcuate inlet ports

86 and 90 register, respectively, with a portion of the working chambers 68 and 62 of the smaller pumping unit shown in Figure 8. In addition to the arcuate inlet ports located on opposite sides of the valve plate 82, the latter is also provided with

arcuate delivery ports

92 and 94 for the large pumping unit 26 (Figure 5) which extend completely through the valve plate. The

arcuate delivery ports

92 and 94 register on the right side of the valve plate with the remainin portions of the working

chambers

58 and 56 of the larger pumping unit as shown in Figure 4.

Although the

ports

92 and 94 should not appear in Figure 4, which is a view on line 4-4 of Figure l, the ports have been shown in dotted lines in Figure 4 for the purpose of illustrating the registry of said ports with the remaining portion of the working

chambers

58 and 56. The

delivery ports

92 and 94 register on the opposite side of the valve plate 82 with an outlet chamber 96 which is formed in the left end casing section l4 (Figure '7). As the ports are duplicates and register with the outlet chamber 96 in the same manner, it has been deemed suilicient to show only one of said ports in Figure '7. The outlet chamber 96 is connected directly to an outlet passage 98, the latter of which registers with the outlet opening in the outlet flange connection 2 The outlet chamber 96 is formed in the left end casing section I4 in the following manner. The valve plate 82 is mounted in the casing section [4 which is hollow. Mounted on the valve plate 82 is the cam ring 38 and a closure member I00. The cam ring 33 and closure member I00 are fastened to the valve plate 82 by means of screws indicated by the numeral I02. Thus, the outlet chamber 96 constitutes the space of the end section i4 between the outer peripheries of the closure member I08, the cam ring 38, and the exposed portion of the valve plate 82, and the walls of the hollow portion of the section 14.

The valve plate 82 and also the cam plate 38 and the head plate Hill which are connected thereto, are prevented from rotary movement by means of pins I04, one of which is shown in Figure 9 which extends through the large cam ring I6 and projects on either side thereof into The outer ends of the vanes of the larger pumping unit 28 are maintained against the inner periphery 52 of the cam ring I6 by means of pressure. This is accomplished by connecting the

delivery ports

92 and 94 of the larger pumping unit 26 which are located in the valve plate 82 to a groove I06 of the rotor 30 by means of passages I08 and I 09 and delivery passages H8 and III in the valve plate 82 (Figures 4, and 7). As shown in Figure 4, the inner ends of slots H2 within which the vanes 34 reciprocate are rounded, as indicated by'the numeral H8, and are connected to the groove I06. Thus, pressure fluid delivered by the pumping unit 26 to the delivery port 92 is delivered by the passages B08 and I09 to the groove I05 while pressure fluid delivered through the delivery port 94 is directed to the groove I06 by means of passages IE0 and HI.

Fluid delivery from the smaller pumping unit 28 is delivered to a separate outlet passage H4 the" smaller rotor are identical in construction with that of the larger rotor except as tosize and'are roundedzat their inner ends as indicated at I32. The groove I30'is in communication with the rounded portion of th slots and thus pressure fluid from the outlet chamber I 20 enters v the groove I30 through the plurality of holes which registers with the opening in the outlet flange 22 as follows. Referring to Figures 1 and 6, mounted within the closure member I00 is a pressure loaded cheek plate I I5 for a smaller pumping unit 28 which contains arcuate delivery ports HS and l I8 extendingcompletely through the plate. These ports are connected to the outlet side of the pumping unit 28 on one side of the plate and on the opposite side of the plate are connected to a separate outlet chamber I20 of the smaller pumping unit which is formed within the closure member I00.

The outlet ports H6 and H8 of the pressure loaded cheek plate H5 are shown in Figure 6 while Figure 8 discloses the manner in which the ports H0 and H8 register, respectively, with a portion of the working chambers 82 and 60 of the smaller pumping unit 28. A telescoping fluid connection member I22, one end of which is mounted in a bore I24 ofthe casing section I4 and the other end of which is mounted in a bore 526 of the closure member I00 connects the outlet chamber I20 directly to the outlet passage I I4. In addition the member I22 acts as a blocking valve in preventing fluid delivery from the outlet side of the large pumping unit in outlet chamber 88 from entering the outlet passage I I4 of the smaller pumping unit. It can be clearly seen that bore I24 is actually a portion of the outlet passage H4 and is connected to the hollow portion of easing section I4. By locating the tele: scoping fluid connection member I22, as illusrated, fluid delivered from the smaller pumping unit through the delivery ports H6 and H8 of the cheek plate H5 into the outlet chamber I20 is directed through the member I22 to the outlet passage H4, and is prevented from entering the outlet chamber 95 oi the large pumping unit. Conversely, fluid delivered from the larger pumping unit through the valve

plate delivery ports

82 and 80 into the outlet chamber 96 of the larger pumping unit is prevented from flowing into the outlet passage H4 of the smaller pumping unit.

Means for maintaining the outer edges of the vanes of the smaller pumping unit 28 against the inner contour 54 of the smaller cam ring 38 is provided by a plurality of holes I28 in the cheek plate H5 (Figure 6) which extend therethrough and permit pressure fluid from the outlet chamber I20 to enter a groove I30 of the small rotor (Figure 8). The slots for the vanes of I28 and maintains the outer edges of the vane in engagement with the inner contour 54 of the cam ring 38. 1

One of the most important features of the dual pumping unit is the provision for automatically maintaining both rotors in fluid sealing engagethem with the single valve plate bypressure fluid means. As shown in Figure 1, it should be noted that the valve plate 82 is slightly shiftable axially in' a mounting recess of the casing section I4 indicated by the numeral I34." However, the valve plate 82 is maintained by pressure fluid in the rightward position shown in engagement against a portion of the surface area of the cam ring I6 and in fluid sealing engagement with the total surface area of one side of the large rotor 30. Pressure fluid in the outlet chamber 06 of the large pumping unit acts against the leftsurface area of the closure member I00 and a portion of the outer surface of the valve plate 02 to maintain the valve plate 82 in fluid sealing engagement with the rotor 30. The total effective surface area included amounts to the total surface area of the valve plate 82 minus the area of the member I22. If, for any reason, the pressure'in the outlet chamber is extremely low, the valve plate 82 is still maintained in fluid sealing engagement with the rotor 30 by nieans of light springs I mounted in the outlet chamber 9801 guide pins I36 the latter of which are mounted in the valve plate 82 and extend therefrom into the outlet chamber 98. g a

Separate means for maintaining the smaller rotor 32 in fluid sealing engagement with the opp site surfaceof the'valve plate 82 is provided'by the cheek plate I I5, the surface area of one side of which is exposed to pressure in the outlet chamber I20 of the smaller pumping unit.

In case of extremely low'pressure in the outlet chamber I20, a light spring I38 mounted in the outlet chamber I20 will hold the cheek plate H5 in fluid sealing engagement with the small rotor 32 and against a portion of the upper surface of the small cam ring 38. The pressure loaded cheek plate also maintains the rotor 32 in fluid sealing engagement with the valve plate 82. t

The check plate H5 is prevented from rotary movement by pins I40 shown in Figure 10 which are mounted in the cam ring 38 and extend therefrom into the closure member I00 and the valve plate 82.' Suitable sealsl42, I44, and I are provided, respectively, for the inlet flange 20 and the outlet flanges I44 and I48. Suitable sealing rings I48 and I50 are also provided for sealing engagement between the center section It and the end section casings I4 and I2.

In operation, with a suitable supply source of fluid connectedto the inlet flange 20, fluid will enter the inlet flange 20 and the inlet passage 54, the latter of which is branched and terminates in arcuate inlet'ports indicated by the

numerals

66 and 68. As the rotor 30 is rotated by the shaft 40, fluid will enter that portion of the working chambers and 58 in registry withxthe arcuate inlet ports and 68 of the end casing I2. Pressure fluid will be drawn into aeaaaoa a portion of the working chamber 6'0 of; the smaller pumping unit by means of the plurality of holes 10 in the center section l6, valve; plate inlet port 18, passage 84, and port 86. Pressure fluid will also be drawn into. a portion of the working chamber 62 of the smaller pumping unit by means of the plurality of port holes 12, valve plate inlet port 80, passage; 88, and port 90. Pressure fluid will be discharged from the remaining portion of the working

chambers

56 and 58 of the larger pumping unit through the

delivery ports

94 and 92 which register with a portion of the working chambers, 56 and, 58 of the larger pumping unit. Fluid delivery'from the

delivery ports

92 and 94 of the valve plate 82 enters the outlet chamber 96 of the larger pumping units and from the outlet.- chamber 96 is delivered to the outlet passage; 98 and through the outlet connection flange 24. Fluid delivery, from the smaller pumping unit isdelivered from the remaining portions of working chambers 60. and 62 through the: pressure delivery ports H8 and I [6 of the cheek plate H5 from whence fluid is delivered to the outlet connection 22 via the smaller outlet chamber I20, member I22, and outlet passage H4. The member I22 prevents fluid delivery from the larger pumping unit entering the outlet passage N4 of the smaller pumping unit and conversely prevents fluid delivery from the smaller pumping unit entering outlet chamber 96 and, outlet passage 96 of the larger pumping unit.

As can be clearly seen, the pumping action of both pumping units is similar to the vane pump described in the patent to Harry F. Vickers, No. 1,989,900. The shape and dimensions, of the working chambers of the pumping units cooperate with the shape. and arrangement of the inlet and outlet ports to provide, vane pumps of the balanced type.

It is important to note that the use of supporting bushings have been completely eliminated. The construction of'the valve plate is such that it cooperates with inlet passages in the right end casing section l2 and the center section Hi to distributev fluid to the inlet side of the smaller pumping unit. In addition, the valve plate contains delivery ports which connect the outlet side of the large pump to the outlet chamber and outlet passages for the large pump in the left end casing sections. The'valve plate also cooperates in directing pressure fluid to the inner ends of thevanes of thelarge pumping unit to maintain the outer ends of the vanes thereof in engagement with the inner contour of its cam ring.

It is also important to note that the separate rotors are maintained in fiuidsealing engagement with the valve plate by pressure fluid means. In the case of the large pumping unit pressure fluid from the discharge side of the large pumping unit maintains the valve plate in fluid sealing engagement with the rotor of the large pumping unit. In the case of the smaller pumping unit pressure fluid from' the discharge side of said unit maintains the cheek plate in fluid sealing engagement with the rotor and this in turn maintains the rotor in fluid sealing engagement with the valve'plate. No mechanical adjustment, which in many cases re sults in pump failure because of excessive clamping pressure, is necessary for maintainingthis fluid sealing engagement.

It should also benotedfthat several different combinations. of; sizes. .of the different pumping units may be arranged. By mass production means, a variety of sizes of each section may be provided which may be combined to meet the demands of a variety of volumes and pressures of difierent circuits. In this manner, separate dual pumping units to meet each circuit requirement is obviated.

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

What is claimed is as follows:

1. A dual vane pump comprising a casing having an inlet section and an outlet section between which is a first pumping unit, means forming a first pressure, chamber in the outlet section having an outlet passage connected thereto. a first pressure responsive cheek plate in the first pressure chamber, one side of which is maintained in fluid sealing engagement against the first pumping unit, a second pumping unit on the opposite side of the first cheek plate, each pumping unit including means forming a pumping recess, a rotor in the recess, and a plurality of reciprocating vanes carried by the rotor, said vanes being held in bearing contact with the contour of the pumping recess to form suction and pressure working chambers, a common drive shaft for the rotors, a closure member mounted in the first pressure chamber and forming a second pressure chamber within the first pressure chamber, a second cheek plate in the second pressure chamber and pressure loaded against the second pumping unit, means forming an inlet supply flow path connected to the suction working chambers of both pumping units, means separately, respectively, connecting the pressure working chambers of the first and second pumping units to the first and second pressure chambers, a second outlet passage in the outlet section, and means hydraulically connecting the second pressure chamber to the sec ond outlet passage.

2. A dual rotary pump comprising in combination a casing having two pumping units therein, each of which includes a stator and a rotor forming suction and pressure working chambers, a common drive shaft for driving the rotors, means forming an inlet supply path connected to the suction chambers respectively of both pumping units, means forming two pressure outlet chambers in the casing, one outlet chamber being inside the other outlet chamber, means separately, respectively, hydraulically connecting the pressure working chambers of the pumping units to the pressure outlet chambers, an outlet passage connected to the outer pressure outlet chamber, a second outlet passage for the inner pressure outlet chamber, and means hydraulically connecting the inner pressure outlet chamber to the second outlet passage.

3. A dual rotary pumping unit comprising in combination a casing having two pumping units therein, each of which includes a stator and a rotor forming suction and pressure working chambers, a common drive shaft for driving the rotors, means forming an inlet supply path connected to the suction chambers respectively of both pumping units, means forming two pressure outlet chambers in the casing, one outlet chamber being inside the other outlet chamber, means separately, respectively, hydraulically connecting the pressure working chambers of the pumping units to the pressure outlet chambers, an

outlet passage connected to the outer pressure outlet chambena second outlet passage for the inner pressure outlet chamber, and a telescoping fluid connection member hydraulically connecting the inner pressure outlet chamber to the second outlet passage.

4:. A dual rotary pumping unit comprising in combination a casing having two pumping units therein, each of which includes a stator and a rotor forming suction and pressure working chambers, a common drive shaft for the rotors, means forming two pressure outlet chambers in the casing, one outlet chamber being inside the other outlet chamber, separate cheek plates for each pumping unit in each'pressure outlet cham her and pressure loaded against their associated pumping units. means forming an inlet supply flow path to the suction working chambers of the 1 pumping units, means separately, respectively, hydraulically connecting the pressure working chambers of the pumping units to the pressure outlet chambers, an outlet passage connected to the outer pressure outlet chamber, a second out let passage for the inner pressure outlet oham-- her, and means hydraulically connecting the inner pressure outlet chamber to the second outlet passage.

5. A dual rotary pump comprising a first pumping unit and a second pumping unit, each pumping unit including a stator and a rotor forming suction and pressure working chambers, a common drive shaft for therotors, a cheek plate between the pumping units in fluid sealing engagement therewith, means forming an inlet fluid supply flow path leading to the suction chamber of the first pumping unit and to the cheek plate, means forming two separate fluid delivery flow paths, one of which leads from the pressure chamber of the second pumping unit and the other of which leads from the cheek plate, and a fluid supply port and a fluid delivery port in the cheek plate respectively connecting the suction chamber of the second pumpingunit to the inlet flow path and the pressure chamber of the first pumping unit to the other fluid delivery flow path.

6. A dual rotary pump comprising a first pumping unit and a second pumping unit, each pumping unit including a stator and a rotor forming suction and pressure working chambers, a common drive shaft for the rotors, a cheek plate floatably mounted between the pumping units, means forming an inlet fluid supply flow path leading to the suction chamber of the first pumping unit and to the cheek plate, means forming two separate fluid delivery flow paths, one of which leads from the pressure chamber of the second pumping unit and the other of which leads from the cheek plate, a fluid supply port and a fluid delivery port in the cheek plate respectively connecting the suction chamber of the second pumping unit to the inlet flow path and the pressure chamber of the first pumping unit to the other fluid delivery flow path, and pressure responsive means connected to the fluid delivery flow paths maintaining the cheek plate in fluid sealing engagement with both pumping units.

7. A dual rotary pump comprising a first pumping unit and a second pumping unit, each pumping unit including a stator and a rotor forming suction and pressure working chambers,

a common drive shaft for the rotors, a cheek plate floatably mounted between the pumping units, means forming an inlet fluid supply flow one of which leads from the pressure chamber of the second pumping unit and the other of which leads from the cheek plate, a fluid supply port and a fluid delivery port in the cheek plate respectively connecting the suction chamber of the second pumping unit to the inlet flow path and the pressure chamber of the first pumping unit to the otherfluid delivery flowpath, and separate pressure responsive means separately connected to the'fluid delivery flow paths of the pumping units separately maintaining the rotors in fluid sealing engagement with the cheek plate.

8. A dual rotary" pump comprising a first pumping unit and a'second pumping unit, each pumping unit including a stator and a rotor forming'suction and pressure working chambers, a common drive shaft for the rotors, a cheek plate floatably mounted between the pumping units, means forming 'an inlet fluid supply flow path leading to the suction chamber of the first pumping unit and to the cheek plate, means forming two separate fluid delivery flow paths,

one of which leads from the pressurechambe'r of the second pumping unitandthe othe'r'of which leads from the cheek plate, a fluid supply port and'a fluid delivery port in the cheek" plate respectively connecting the suction chamber of cheek plate in communication withone of the delivery flow paths for maintaining the cheek plate in fluid sealing engagement with one of the rotors, and a second pressure responsive cheek plate one side of which is in communication with the otherdelivery flow path for maintaining the other rotor in fluid sealing engagement with the first cheek plate.

9. A dual rotary vane pump comprisinga casing provided with a pair of pumping recesses, a first pumping unit and a second pumping unit separately mounted in the recesses, each pumping unit including a rotor and a plurality of reciprocating vanes, said vanes being held in bearing contact with the contour of their respective pumping recesses to form suction and pressure working chambers, a common drive shaft for the rotors, a fluid distributing valve plate floatably mounted in the casing between the pumping units, means forming an inlet fluid supply flow path leading to the suction chamber of the first pumping unit and to the valve plate, means forming two separate fluid delivery flow paths, one of which leads from the pressure chamber of the second pumping unit and the other of which leads from the valve plate, a fluid supply port and a fluid delivery port in the valve plate respectively connecting the suction chamber of the second pumping unit to the inlet supply flow path and connecting the pressure chamber of the first pumping unit to the other fluid delivery flow path, pressure responsive means including one side of the valve plate in communication with one of the delivery flow paths for maintaining the valve plate in fluid sealing engagement with one of the rotors, and a pressure responsive cheek plate having one side thereof in communication with the other delivery flow path for maintaining the other rotor in fluid sealing engagement with the valve plate.

10. A dual rotary pump. comprising a casing having an inlet section and an outlet section between which is a first pumping unit, means form,- ing a first pressure outlet chamber in the outlet section having an outlet passage connected thereto, a first pressure responsive cheek plate in the first pressure outlet chamber one side of which is maintained in fluid sealing engagement against the first pumping unit, a second pumping unit on the opposite side of the first cheek plate, each pumping unit including a stator and a rotor iorming suction and pressure working chambers, a common drive shaft for the rotors, a closure member mounted in the first pressure outlet chamber and forming a second pressure outlet chamber within the first pressure outlet chamber, a second cheek plate in the second pressure outlet chamber and pressure loaded against the second pumping unit, means forming an inlet supply flow path leading from the inlet section to the suction working chambers of the pumping units, means forming two fiuid delivery flow paths separately connecting the pressure working chambers of the first and second pumping units respectively to the first and second pressure outlet chambers, a second outlet passage in the outlet section, and means hydraulically connecting the second pressure outlet chamber to the second outlet passage.

11. A dual rotary pump comprising a casing having an inlet section and an outlet section between which is a first pumping unit, means forming a first pressure outlet chamber in the outlet section having an outlet passage connected thereto, a first pressure responsive cheek plate in the first pressure outlet chamber one side of which is 12 maintained in fluid sealing engagement against the first pumping unit, a second pumping unit on the opposite side of the first cheek plate, each pumping unit including a stator and a rotor forming suction and pressure working chambers, a common drive shaft for the rotors, a closure member mounted in the first pressure outlet chamber and forming asecond pressure outlet chamber within the first pressure outlet chamber, a second cheek plate in the second pressure outlet chamber and pressure loaded against the second pumping unit, means forming an inlet supply flow path leading from the inlet section to the suction working chambers of the pumping units, means forming two fluid delivery flow paths separately connecting the pressure working chambers of the first and second pumping units respectively to the first and second pressure outlet chambers, a second outlet passage in the outlet section, and a telescopic connection from inside the second pressure outlet chamber to the second outlet passage hydraulically connecting the second pressure outlet chamber to the second outlet passage,

DUNCAN B. GARDINER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,607,383 Aurand Nov. 16, 1926 1,984,664 Teves Dec. 18, 1934 2,373,457 Chisholm Apr. 10, 1945 2,411,606 Wilson Nov. 26, 1946