US3451346A

US3451346A - Power transmission

Info

Publication number: US3451346A
Application number: US682905A
Authority: US
Inventors: Raymond B Pettibone
Original assignee: Sperry Rand Corp
Current assignee: Vickers Inc
Priority date: 1967-11-14
Filing date: 1967-11-14
Publication date: 1969-06-24
Anticipated expiration: 1986-06-24
Also published as: DE1808826A1; GB1251816A

Description

R. B. PETTIBONE POWER TRANSMISSION June 24, 1969 Filed Nov. 14, 1967 M/ w f m.. lllrl lill' 2 |F. j u Il T l 6 L /8 m 1 Gym/2 84 uw F C24-.Jn n 911/ QRS; M 2 /(w wmHK/M r M FIG. 44

` INVENTOR. RAYMOND B. PETTIBONE ATTORNEYS United States Patent O U.S. Cl. 103-136 6 `Claims ABSTRACT F THE DISCLOSURE A rotary fluid pressure energy translating device having a vane cam track within which is rotatably mounted a rotor carrying radially sliding vanes to form iluid inlet and Huid outlet working zones located between the periphery of the rotor and the vane track, the vanes being of the type having a thrust member telescopically disposed within each vane and forming an expansible pressure chamber therein, a surface of which is effective under pressure to urge the vane into engagement with the cam track, each vane having a balancing cavity on the face thereof, intersecting and in iluid communication with the said expansible pressure chamber, and a pressure porting arrangement for transmitting fluid under pressure to said expansible pressure chamber.

Background of the invention This invention relates to power transmissions, and is particularly applicable to those of the type comprising two or more uid pressure energy translating devices, one of which may function as a pump, and the other as a fluid motor. More particularly, this invention relates to an improvement in sliding vane type pumps and motors such as illustrated in the patent to Duncan B. Gardiner, No. 2,967,488.

Units of this type generally comprise a stator including a vane cam track within which is rotatably mounted a rotor carrying radially sliding vanes to form iluid inlet and uid outlet working zones located between the periphery of the rotor and the vane track, either of which may be a low or a high pressure working zone dependent upon the pump or motor function of the device. In such devices the vanes as followers are adapted to follow the cam track and to provide proper sealing between inlet and outlet porting corelated with the iluid inlet and fluid outlet zones. Thus, it is essential for efficient operation that the vanes be completely extended outwardly and that the outer edges of the vanes be maintained in engagement with the track during the complete rotary cycle of the device.

During operation of such a device, the vanes are urged outwardly and into engagement with the track by centrifugal force and also by providing a controlled pressure unbalanced condition between an outer track engaging surface and an inner and an intermediate surface of the vane. The vane is urged inwardly by mechanical cam action of the track. The level of leakage between the inner, intermediate, and outer surfaces of the vane is kept within acceptable limits to assure the pressure unbalanced condition by providing a relatively small clearance space between the vane and the walls of the coresponding rotor slots. However, there are many conditions existing and forces created tending to prevent the vanes from acting as free followers and also causing the vanes to collapse, or retract, from the vane track, such as mechanical friction and bearing loads between the vanes and the walls of the slots in which they are carried. These adverse conditions result in the development of localized wear points between the vane and slot wall interface, scoring, or vane 3,451,346 Patented June 24, 1969 ICC seizure, creating unfavorable resultant forces on the extreme inner and outer end areas of the vanes.

In the Gardiner patent, the adverse condition are minimized by providing enlarged feed passages in the rotor slot walls on opposite Sides of each vane, thus, a means is established for providing pressure fluid to the opposite interface surfaces of each vane and to the intermediate surface therein `and the resultant opposing hydraulic forces between the vane and slot wall interface tends to laterally stabilize the vane. However, at extremely high speed and high pressure operation, the leakage between the inner, intermediate, and outer surfaces of the vane exceeds the herebefore mentioned `acceptable limits necessary to assure a proper pressure unbalanced condition for maintaining the vane in engagement with the track. Elimination of one of the enlarged feed passages was found to bring the aforementioned leakage to within acceptable limits, however, scoring and vane seizure occurred. This problem is believed to have resulted from lack of lateral stabilization of the vanes. This invention eliminates the scoring and seizure problems while maintaining very low leakage levels.

Summary of the invention This invention comprises a rotary fluid energy translating device of the sliding vane type with a rotor having radial slots with a plurality of pressure chambers associated therewith, a balancing cavity in fluid communication with one of said pressure chambers for preventing contact between the vane and corresponding slot wall.

It is, therefore, an object of this invention to provide an improved, low cost, eicient and long wearing fluid pressure energy translating device of the sliding vane type.

More specifically, it is an object of this invention to provide such a device having an improved vane structure which reduces wear between the vanes and guiding slot walls.

It is another object of this invention to provide such a device having an improved vane biasing arrangement which insures complete extension of the v-anes and maintenance of the same in engagement with the vane track without an excessive scoring or seizure between the vanes and guiding slot walls.

It is still another object of this invention to provide an improved vane structure which will provide lubrication between the interface of the vanes and guiding slot walls While tending to laterally stabilize the same at extremely high pressure and high speed operation without an excessive amount of leakage therein.

It is still another object of this invention to provide such a device having all of the advantages previously recited without increasing the overall dimensions currently in production.

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

In the drawings:

FIG. l is a longitudinal, sectional view of a device embodying the present invention and taken on line 1--1 of FIG. 2.

FIG. 2 is a sectional view taken on line 2-2 of FIG. 1.

FIG. 3 is an enlarged partial sectional view of the vanes and porting arrangement associated therewith shown in FIG. 2.

FIG. 4 is a partial sectional view taken on line 4-4 of FIG. 3.

Referring now to the drawings, especially FIG. 1, there is shown a rotary, sliding vane device or pump, indicated generally by the numeral 10, the housing of which comprises a vane cam track section 12 sandwiched between a body member 14 and an end cover 16, all of which are secured to each other by bolts 18 extending through cover 16 and cam section 12 into threaded holes in body 14. The body section 14 is provided with an inlet supply connection port 20 having an inlet passage 22 leading therefrom which has two

branches

24 and 26 respectively terminating in a pair of

fluid port openings

28 and 30 which are shown in hidden lines in FIG. 2. An outlet connection port 32 is provided in the end cover 16 which is directly connected to a pressure delivery chamber 34 formed in an enlarged bore 36 of the end cover 16 where a pressure plate 38 is fioatably mounted in the bore 36. The pressure plate 38 is urged rightwardly by outlet pressure in the chamber 34 so that the outer portion of a plane side surface thereof and indicated by the numeral 40, is maintained in engagement with the immediately adjoining surface of a rotor 42 and vanes carried thereby within the cam section 12. Spring 43 initially biases the pressure plate 38 toward the rotor until pressure builds up in the pressure chamber.

The rotor 42 is rotatably mounted within cam section 12 on the splined end 44 of shaft 46 which is rotatably mounted within

bearings

48 and 50 mounted within the body section 14. The shaft 46 is provided with a seal 52 while O ring seals 53 and 54 prevents leakage at the juncture of the cam ring section 12 with the body 14 and end cover 16.

The contour of the inner surface of the cam section 12 forms a vane track substantially elliptical in shape indicated by the numeral 56 which together with the periphery of the rotor and the adjoining surfaces of the body and pressure plate dene two opposed working chambers indicated by the numerals 58 and 60, each of which, for the purposes of convenience, may be divided into fluid inlet and uid outlet zones and which forms a sliding vane device of the double throw type. The fluid inlet zones comprise those portions of the working chambers 58 and 60 respectively registering with the fluid

inlet port openings

28 and 30 of the

inlet passages

24 and 26.

The fluid delivery zones comprise those portions of the working chambers 58 and 60 registering respectively with opposed arcuately shaped uid delivery port openings 62 and 64 (shown in dot-dash lines in FIG. 2 to indicate positional relationship) which are recessed in the surface 40 of the pressure plate 38 and which are directly connected to the pressure chamber 34 by means of duplicate passages 66 leading therefrom, one of which is shown in FIG. l.

The vane track of the device includes an inlet zone ramp extending from a to b, a true arc portion extending from b to c, a delivery zone ramp extending from c to d and another true arc portion extending from d to e. The track is symmetrical about each of its major and minor axes, thus each of the ramp and true arc portions from a to e are duplicated in the remaining opposed portions of the track. As the ends of vanes 68 carried by the rotor traverse the inlet ramps, the vanes move radially outward with respect to the rotor, and while the vane ends traverse the delivery ramps, the vanes move radially inwardly. In the true arc portions, the vanes partake of no radial movement.

The radial slots 70 in the rotor are formed by the parallel walls which guide the vanes as they move radially inward and outward and are indicated by the numbers 71 and 72 (FIG, 3) and also the enlarged pressure chamber at the inner end of each slot and indicated by the numeral 73. The spacing between each pair of vanes is adapted to span the distance between each pair of ports in a manner to provide proper sealing between the inlet and outlet porting connected to the working chambers of the device. A plurality of angular passages 74 is provided, one for each slot, which lead from the periphery of the rotor to the inner enlarged chambers 73 0f the vane slots.

The passages 74 are adapted to transmit to the vane slot pressure chambers 73 and thus to the inner surfaces of 75 the vanes indicated by the numeral 75, the cyclically changing pressure which is exerted on the outer edges 76 of the vanes 68 as they traverse the inlet and outlet ramps of the vane track. A reaction member for each vane, indicated by the numeral 78, which together with a correlated porting arrangement provides a controlled unbalance on the suction stroke or inlet phase of the device which insures complete extension of the vanes and also maintenance of the outer edges of the vanes in contact with the vane track through the complete rotary cycle of the device.

Referring now to the several figures, the vanes 68 of the present invention device differ from the flat sided substantially rectangular vanes of the conventional devices by having two rectangular milled out sections, one of which extends from the inner end of the vane to substantially the mid-section thereof, which is indicated by the numeral 80, and the side walls of which are indicated by the numeral 82. The second rectangular milled out section comprises a balancing cavity 84 later described.

The aforementioned reaction member 78 comprises a fiat sided blade substantially equal in width and thickness to that of the milled out section 80 of the vane so as to have a sliding telescoping fit within the side walls 82 of the vane and the side walls 71 and 72 of each vane slot. Each vane 68 also includes an oval shaped expansible pressure chamber 86 defined by the side walls of the vane slot and the extended cutaway portion of the vane and in which is exposed a pressure responsive outer end surface 88 of the reaction member 78. The inner end 90 of each reaction member 78 extends from the inner end of the vane into the pressure chamber 73 of the vane slot.

The second of the aforementioned milled out sections, balancing cavity 84, extends across a face 91 of the vane 68 at substantially the mid-section thereof in an axial direction and is in communication with the expansible pres| sure chamber 86 preferably by intersecting the same as shown in FIG. 4. The balancing cavity will operate most effectively when it has a shallow depth. By limiting the depth of the cavity, there is created a restricted flow path across the cavity, thus the level of leakage losses may be maintained at an acceptable level, while a pressure field, which is sufiicient to laterally stabilize the vane, may be maintained between the vane and slot wall surfaces. The depth, indicated by the numeral 92 in FIG. 3, has been exaggerated for purposes of illustration.

Due to the shallowness of the cavity, the strength of the vane is not impaired, since the cross section of the vane between the faces 91 and 104 is not substantially reduced. Further, due to the limited depth of the cavity, the vane achieves step bearing effect as it slides within the rotor slots, thus, in addition to laterally stabilizing the vanes, friction between the vane and slot walls is reduced due to this increased bearing capability of the vane surface 91. Units employing vanes having a balancing cavity have performed in a desired manner when the balancing cavity is maintained at a depth of approximately .005 inch.

Pressure from the outlet side of the device continuously transmitted to the reaction member pressure chambers 86 and to each cavity 84, serves to initiate development of a hydrodynamic film between the vane face 91 and th slot wall 71 regardless of the operating pressure of the device. Pressure in the pressure chamber 86 also acts against the outer exposed surface of said chambers to urge the reaction members 78 to the position recited, wherein the tapered inner end thereof is bottomed against an inner surface 93 of the vane slot pressure chamber 73.

With the reaction members 78 slidably mounted between the confining side walls 71 and 72 of the vane slots and the milled out sections of the vanes, a pressure responsive surface opposing the pressure responsive surface 88 of the reaction members 78 is formed on each vane, indicated by the numeral 94, comprising a portion of the upper surface, as viewed in FIG. 4, of the reaction pressure chamber 86. The effective area of the surface 94 is equal to the projected area of the pressure responsive surface 88 of the reaction member 78.

Por the purpose of connecting the high pressure outlet side of the device to the reaction member pressure chambers 86 and balancing cavities 84, the pressure plate 38 is provided with a plurality of passages 9S, one of which is shown in FIG. 1, lwhich extends from the pressure chamber side of the plate through said plate to a circular pressure groove 96 recessed in the plane surface 40 of the plate immediately adjacent the rotor. A mirror image 98 of this pressure groove may be constructed in a plane surface 100 of the body section 14 on the opposite side of the rotor. The

pressure grooves

96 and 98 register with the opposite ends of a plurality of half-round holes 102 arranged in circular formation in the rotor. The holes 102 extend completely through the rotor on each wall 72 of the slots 70 while also communicating with the reaction member pressure chamber 86 at the face 104 of the vanes 68.

In operation, with a prime mover, not shown, connected to the shaft 46 for turning the rotor 42 clockwise as viewed in FIG. 2 and the inlet port 20 connected to a source of fluid supply, fluid is conducted to the

inlet port openings

28 and 30 adjacent the inlet ramp portion -of the vane track by means of passage 22 and

branch passages

24 and 26. As the vanes traverse the inlet ramps of the vane track, fluid is Withdrawn through the

inlet port openings

28 and 30 into the intervane spaces and carried to the

outlet ports

62 and 64 from where it is discharged through the outlet port 32 by the medium of the pressure

plate outlet ports

62 and 64, the pressure plate outlet passages 66, and the pressure chamber 34 which is directly connected to the outlet port 32.

As the outer ends of the vanes pass through the inlet zones of the working chambers of the device, the pressure existent in said zones, which is imposed on the outer edges 76 of the vanes, will also be transmitted to the inner surfaces 75 of the vanes by the medium of passages 74 extending from the periphery of the rotor to the vane slot pressure chambers 73.

A controlled vane pressure unbalance for aiding centrifugal force in rapidly and completely extending the vanes and maintaining the outer edges thereof in engagement with the vane track is provided by the transmission of pressure from the pressure chamber on the outlet side of the device to the reaction member pressure chambers 86, through the medium of pressure plate passages 94 and groove 96 and the rotor passages i102. The outer surfaces 88 of the reaction members are exposed to the pressure within the chambers 86 and the reaction members 78 are urged to a bottoming position with their inner ends 90 engaging the inner surfaces 93 of the vane slot pressure chambers 73. The pressure transmitted to the pressure chamber 86 is transmitted equally tothe balancing cavity 84 and while the vane moves inwardly and outwardly, a hydrodynamic film is established between the vane face 91 and the slot wall 71 which will tend to laterally stabilize the same while providing a lubricating medium for preventing metal to metal contact between the vane and slot wall. Further, any debris or other contaminants from the vane-rotor slot interface areas which may be trapped therein will be flushed out through the balancing cavity which otherwise would promote scoring of the vane faces, and slot walls or possible vane seizure and ultimately prevent the vane from properly maintaining contact with the vane track 56.

It will be clearly seen that the connection of the outlet side of the device to the reaction member pressure chambers produces a resultant outward force on the vane which not only aids centrifugal force in completely extending the same, but produces a continuous, controlled force in favor of maintaining the outer edges 76 of the vane 68 in contact with the vane track 56 and connection of the outlet side of the device also to the balancing cavity 84, produces a balanced condition between the vane and slot wall which allows the vane to move radially inward and outward with a minimum amount of friction. The balancing cavity 84 is located on the vane face 91 and produces a hydraulic lforce which tends to separate the vane from the slot wall 71. The hole 102 is located on the slot wall 7,2 and produces a hydraulic force which. tends to separate the vane from it. The size of each balancing cavity and hole relative to the vanes is preselected in order that the total resultant force balance between the vanes and the slot walls will be such as to laterally stabilize the vane to prevent contact between the walls and vanes so as to insure rapid, complete movement of the vanes.

As the rotor continues to turn and the vanes pass through the true arc section of the track, they, as aforementioned, will partake of no radial movement.

As the vanes traverse the outlet ramps of the vane track and the outer portions thereof pass through the outlet working zones of the device, they are retracted by the cam contour of the vane track. During this operating phase of the device, the resultant inward and outward forces on the vanes are substantially balanced. The pressure existent in the outlet working zones of the device and imposed on the outer edges 76 of the vanes 68 is transmitted to the innermost areas 7S of the vanes through the medium of the passages 74. Pressure is conducted to the surface 94 and groove 96 an dthe rotor passages 102. As the resultant forces on the extreme inner and outer ends of the reaction members are the same, the vanes are thus substantially balanced during the discharge phase of the device.

The balancing cavity 84 'of each vane will function in the same manner when the vanes pass through the outlet working zones of the device, as the herebefore described operation when the vanes pass through the inlet Zones of the working chambers of the device.

It will thus be seen that the present invention has provided a rotary fluid pressure energy translating device wherein a controlled pressure balance between each vane and corresponding slot walls is provided for laterally stabilizing the vane, thus preventing metal to metal contact between the vane and rotor slot walls, while providing a limited amount of leakage between 'the inner, intermediate and outer surfaces of the vane, thus, assuring an extension 'of the vanes for engagement with the track.

Devices embodying the invention operate at much higher pressures and speeds than conventional devices of the type herebefore used, yet minimize excessive rwear while providing utmost efliciency and long life.

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. In a rotary fluid energy translating device of the sliding vane type including low and high pressure operating passages, one of which is an inlet passage and the other an outlet passage, and a vane track; a rotor having a plurality of radial slots, each slot being defined by two parallel side surfaces, and rotatably within the track; a vane slidable in each slot having parallel side surfaces guided by said corresponding slot surfaces, a track engaging outer end surface, an intermediate surface and an inner end surface, both of said latter two surfaces being effective under pressure for urging the vane outer surface toward the track; a reaction member including an outer end surface radially disposed within each vane for telescopic movement relative thereto and forming an expansible chamber, two directly opposed walls of which are the intermediate vane surface and associated reaction member outer end surface; passage means connecting the high pressure operating passages `of the device to said expansible chamber; that improvement which comprises means forming a shallow balancing cavity in one of said vane surfaces on each vane and facing one of said corresponding slot surfaces; and passage means connecting said cavity with said expansible chamber for lubricating said vanes and tending to laterally stabilize the same and prevent metal to metal contact of the corresponding vane and slot parallel side surfaces.

2. A combination as in claim 1 wherein said passage means connecting the high pressure operating passages of the device to said eXpansible chamber includes a recess formed in each of said slots on the side surface opposite the said one corresponding slot surface, said recess being in fluid communication with said expansible chamber.

3. ,In a rotary fluid energy translating device of the sliding vane type including low and high pressure operating passages, one of which is an inlet passage and the other an outlet pasage, and a vane track; a rotor having a plurality of radial slots, each slot being defined by two parallel side surfaces, and rotatable within the track; a vane slidable in each slot having parallel side surfaces guided by said corresponding slot surfaces, a track engaging outer end surface upon which cyclically changing pressure is irnposed, and also having an intermediate surface and an inner end surface, both of said latter two surfaces being effective under pressure for urging the vane outer surface toward the track; a reaction member including an outer end surface radially disposed Within each vane for telescopic movement relative thereto and forming an expansible chamber, two directly opposed walls of which are the intermediate vane surface and associated reaction member outer end surface, means forming a second eXpansible chamber in communication with the inner surfaces of the vanes, first passages means for conducting the cyclically changing pressure to one of said expansible chambers, and second passage means for conducting the high pressure passage to the other of said expansible chambers; that improvement which comprises means forming a shallow balancing cavity in one of said vane parallel side surfaces on each vane and facing one of said corresponding slot surfaces; and passage means connecting said cavity to one of said expansible chambers for lubricating said vanes and tending to` laterally stabilize the same and prevent metal to metal contact of the corresponding vane and slot surfaces.

4. A combination as in claim 3 wherein said first passage means is connected to said first expansible chamber; said second passage means is connected to said second eX- pansible chamber; and said balancing cavity means is connected to said first expansible chamber.

5. A combination as in claim 3 wherein said first passage means includes a recess formed in each of said slots 8 on the surface 'opposite the said one corresponding slot surface, said recess being connected to said first expansible chamber; said second passage means is connected to said second expansible chamber; `and said balancing cavity means being connected to said first expansible chamber.

6. In a rotary fiuid energy translating device of the sliding vane type including lozw and high pressure operating passages, one of which is an inlet passage and the other an outlet passage, and a vane track; a rotor having a plurality of radial slots, each slot being defined by two parallel side surfaces, a Vane slidable in each slot having parallel side surfaces guided by said corresponding slot surfaces, a track engaging outer end surface upon which cyclically changing pressure is imposed; means forming separate surfaces associated with each vane, said surfaces being effective under pressure to urge the vanes towards the track; means forming separate pressure chambers in each slot one of which is associated with one of said separate surfaces, the other associated with the other of said separate surfaces; a first passage means for conducting the cyclically changing pressure to one of said expansible chambers, and a second passage means for conducting the high pressure passage to the other of said expansible chambers; that improvement which comprises means forming a shallow balancing cavity in one of said vane parallel side surfaces on each vane and facing one of said corresponding slot surfaces; and, passage means connecting said cavity means to one of said expansible chambers for lubricating said vanes and tending to laterally stabilize the same and prevent metal to metal contact of the correspending vane and slot surfaces.

References Cited UNITED STATES PATENTS W. I. KRAUSS, Assistant Examiner.

U.S. Cl. X.R.