Vane-type Pumps

Abstract

A rotary vane fluid power unit in which a plurality of vanes slidably supported in a rotor are individually maintained in engagement with an encircling cam surface by fluid pressure acting radially on the inner surfaces of pistons which engage the vanes. A fluid passageway is provided internally of the pump which includes a valve for maintaining under pressure the fluid that reacts against the pistons.

Description

BACKGROUND OF THE INVENTION

This invention is directed to improvements in fluid pressure energy translating devices of the vane type which include hydraulic means for vane control and which are known in the art as "three-area" devices. More specifically, the invention relates to valve means in a vane pump for preventing damage to the vane tips and the cam ring such as is normally encountered where there is an insufficient total force acting outwardly on the vanes as the vanes traverse the cam ring surface. A typical hydraulic pump of the vane type includes a rotor having a plurality of radially movable vanes carried in slots around its periphery. The vanes engage the cam ring surface of a fixed stator or cam ring which surrounds the rotor. Inlet and outlet ports open at spaced positions into the area between the periphery of the rotor and the cam surface and are swept or traversed sequentially by the vanes as the rotor turns, whereby fluid received at the inlet port is transferred by the vanes to the outlet port.

In a vane pump of the three-area type, fluid pressures act on the three areas associated with each vane and the forces resulting from these pressures cooperate to urge each vane into operative engagement with the cam surface, i.e., to maintain a dynamic seal between the vane tip and the cam surface. By utilization of the three-area vane control principle, a limited predetermined hydraulic force for urging or moving the vanes outwardly is obtained.

The fluid pressures acting on two of the areas associated with each vane are substantially equal but act in opposite directions. And the forces resulting from these pressures thus tend to counteract each other. The first area comprises a surface on the radially outer end of the vane and is subjected to pressure which urges the vane inwardly in its slot. The second vane area comprises a surface and on the radially inner end of the vane. The second area is subjected to a pressure equal but opposed to that acting on the first area, which pressure urges the vane outwardly in its slot.

A third area associated with each vane is also subjected to fluid pressure which urges the vane outwardly. Pressure on this third area provides a controlling hydraulic force which, in addition to centrifugal force, urges the vane outwardly to effect and maintain a fluid seal between the outer end of the vane or vane tip and cam ring surface.

Three-area pumps of the type to which this invention relates include a rotor assembly having an internal pressure chamber and a pressure operated pin or piston associated with each vane, the piston being slidable in a bore intersecting the pressure chamber and leading radially to the vane. Fluid pressure in the chamber acts on the pistons and provides the third area force holding the vanes outwardly against the cam surface. Pressure is supplied to this chamber through passageways from a high-pressure zone of the pump whenever the pressure in the chamber tends to drop sufficiently below the pressure in the high-pressure zone.

The basic principles of the three-area concept for controlling vanes are taught in U.S. Pat. No. 2,832,293 for a "Vane Pump," Cecil E. Adams et al. According to one form of the three-area device as disclosed in the Adams et al. patent, there is associated with each vane a piston mounted in the rotor for sliding movement in the radial direction to engage the inner end of the vane. Fluid under pressure for operating the pistons is supplied through a channel or chamber in the rotor adjacent the operating shaft which in turn is fed through grooves formed in the cheek plate surfaces adjacent the rotor and leading from the high-pressure zone. Because the fluid being fed to the rotor channel must pass from or through the cheek plates across the clearance gaps between the rotor and cheek plate, considerable quantities of fluid under pressure can escape through these clearance gaps. This loss of fluid under pressure reduces the overall efficiency of the device.

Prior to the present invention, no satisfactory means had been known for supplying fluid under pressure to the third area means of the type shown in U.S. Pat. No. 2,832,293 without an excessive amount of leakage. As previously suggested, one object of this invention includes the provision of a pump including the three-area vane control principle in which the passageway through which fluid under pressure is supplied to the third area is contained wholly within the rotating assembly including the rotor body and shaft and, therefore, is not exposed to leakage paths (such as the mentioned clearance gaps) from which leakage of high-pressure fluid from the high-pressure fluid passageway can occur.

A further object of the present invention is to provide a valve means disposed in the internal passageway or conduit means for maintaining under pressure the fluid acting upon the pistons.

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

IN THE DRAWINGS

FIG. 1 is a vertical longitudinal or axial sectional view of a three-area vane-type pressure energy-translating device including the invention;

FIG. 2 is a view in section taken generally on line 2-2 of FIG. 1 and showing an enlarged view of the relative positions of the fluid ports;

FIG. 3 is an enlarged perspective view depicting the resilient sleeve structure used in one embodiment of the invention; and

FIG. 4 is an enlarged view of another embodiment showing a unitary shaft and rotor element which includes the features of this invention.

GENERAL CONSTRUCTION

The three-area vane pump of this invention is a first described with reference to FIG. 1 of the drawings. It includes a housing or casing formed by a body casing 10 having a generally cylindrical interior chamber. An end cap 11 having a cylindrical boss 12 telescopes into the end of the body and is sealed by an O-ring 13.

The end wall 14 of the body opposite end cap 11 includes a bore through which the pump operating shaft 15 extends. Shaft 15 is supported for rotation in this bore by a bearing (not shown) which is secured against axial movement in the bore. Shaft 15 extends from the body 10 into end cap 11 and is carried for rotation therein by a plain bearing 16 mounted within a central bore 17 in the end cap 11. The bearing 16 is held against axial movement at one end by a snap ring 18. Cylindrical boss 12 of end cap 11 is finished to form a flat inner surface which is clamped against a side or radial face 19 of a cam ring or stator 20. It may be mentioned here that the cam ring itself as well as the housing and cam ring together is sometimes referred to in the art as a stator.

A fluid intake passageway 21 extends radially into body 14 and communicates with a pair of annular channels 22, 23 which encircle the internal cavity within the body 14. These annular channels 22, 23 distribute fluid from the intake passageway 21 to suction ports later to be described in detail.

The cam ring 20 is supported radially by an annular rib 24 formed in the body 11 between the annular channels 22, 23. The cam ring 20 encircles a rotor 25 which is connected to and supported by the shaft 15 through a motion permitting spline joint 26 that permits proper running alignment between the rotor, the flat surface of the cylindrical boss 19, and a movable cheek or port plate 27. The rotor 25 is provided with a plurality of radial vane slots 28 in each of which a radially pressure balanced vane 29 is mounted. This may best may be seen in FIG. 2 of the drawings.

The cam ring 20 has a cam surface 30 that is contoured to provide a balanced or symmetrical pump construction in which there are diametrically opposite low-pressure or suction zones 31, fluid transfer zones 32, high-pressure or exhaust zones 33, and sealing zones 34 formed between the cam surface and the rotor 25. In order to provide the opposed zones, the cam surface 30 is formed in part, by a first pair of arcs of equal radii which extend across the fluid transfer zones 32 and, in part, by a second pair of arcs of shorter radii than the first pair of arcs which extends across the sealing zones 34. These pairs of arcs are interconnected by cam surfaces which extend across the low- and high-pressure zones 31 and 33, respectively.

Cheek plate 27 is finished to provide a smooth flat radial surface on the inner side thereof which abuts the cam ring 20. A central bore 35 in cheek plate 27 is surrounded by a cylindrical boss 36 which extends into the bore in the wall 14 of the body 10 and is sealed by an O-ring 37. The outer cylindrical surface of cheek plate 27 is sealed with respect to body 10 by an O-ring 38. The cheek plate 27 is movable axially in the body 10 and is urged toward rotor 25 by fluid pressure supplied from the high-pressure zone 33 through passageways 39 and 40 to a pressure chamber 41 formed between the body and the outer face 31 of the cheek plate. The cheek plate functions in the nature of an axially movable, nonrotatable piston, under pressure supplied by the fluid in chamber 41 to maintain it in engagement with the adjacent side face of the cam ring 20.

Intake passageway 21 communicates through annular channels 22 and 23 around cam ring 20 to suction ports spaced 180.degree. apart. Two suction ports, 43 and 44 shown in FIG. 2, are formed in cheek plate 27 and are fed by channel 23. Two additional suction ports (not shown) are formed in end cap 11 and are fed by channel 22. These suction ports in the end cap and cheek plate are identical in shape and are axially aligned with the suction zone 31 between the rotor 25 and cam surface 30. Each suction port has a branch passage, the opening of one of which is designated at 45, and the other of which is designated at 46, whereby these suction ports communicate with the inner ends 47 of vane slots 28 in the rotor 25 as well as with the inlet zones 31.

As shown in FIG. 1, the end cap 11 includes two diametrically opposed crescent-shaped exhaust or pressure ports 48 which are based substantially 90.degree. from the suction ports. Similarly, pressure ports 49 are formed in cheek plate 27 and are axially aligned with the pressure zones 33 and with ports 48 in the end cap 11. Each pressure port 48 and 49 communicates with the inner ends 47 of the vane slots 28 in the rotor 25 as the vane slots pass the ports through branch ports 50 and 51. Pressure ports 48 are connected with a fluid outlet or delivery port 52 by passageway 53 in the end cap 11.

OPERATION

In the direction of rotor movement (clockwise as shown by the arrow in FIG. 2), the cam surface 30 progressively recedes from the periphery of the rotor 25 across the suction zones 31. In the transfer zones 32, cam surface 30 has nearly constant radial spacing from the rotor, and across the exhaust zones 33 the cam surface progressively approaches the rotor 25 as it comes into close proximity with the periphery of the rotor 25 in the sealing zone 34. Fluid from the suction ports 43 and 44 is drawn into the fluid transport pockets defined between the successive vanes as those pockets become larger when the vanes 29 move through the suction zones 31. As the vanes move through the pressure zones 33, the volume of the pockets between the vanes diminishes and the fluid is positively displaced to effect a pumping action.

Each vane 29 is provided with grooves 54 which are formed in the radially outer surface 70 and opposite side surfaces 71. One ore more channels or bores 55 are also provided in each vane which communicate between the outer groove 54 of the vane and the inner end 47 of the vane slot. The grooves 54 and channels or bores 55 insure that fluid pressure acting on the first area or outer end surface of any given vane will be substantially balanced at all times by the pressure acting on the secondary or inner end surface of that vane.

For the pump to operate at high efficiency, it is necessary to maintain a continuous sealing engagement between the cam surface 30 and the outer end surfaces 70 of the vane, regardless of changes in the arcuateness of the cam surface. To provide the hydraulic pressure for this purpose, one or more radial bores or piston cylinders 56 is formed in the rotor 25, extending inwardly from the inner end 47 of each vane slot 28. The bores 56 are interconnected at their inner ends with an annular pressure chamber 57 formed in a cylindrical resilient seal 58 disposed between the rotor 25 and shaft 15. The seal 58, best seen in FIG. 3 of the drawings, may be constructed from neoprene or any similar material. With some materials it may be desirable to bond seal 58 to rotor 25.

A generally cylindrical piston or hydraulic actuator 59 is slidingly and sealingly disposed within the cylinder 56. Each piston 59 is closely fitted to the bore 56 so that leakage of fluid along the external walls of the piston is negligible. Fluid which is admitted under pressure to the radial bores 56 flows from the high-pressure chamber or exhaust port 53, through passageways 60 in end cap 11, ports 61 in bushing 16, ports 62 in shaft 15, port 63 in bushing 64, around check valve 65, spring 65', passageway 66 and into radially interconnecting passageways 67 through ports 68 in resilient seal 58 and thus into bores 56. The bushing 64, check valve 65 and spring 65' are retained within the shaft 15 by a threaded plug 69. Once the interconnecting passageways 56, 57, 68, 67, 66 have been charged with high-pressure fluid, the check valve 65 will maintain that fluid under pressure. If for any reason, the pressure of the fluid in the aforesaid mentioned passageway should become less than the pressure of the fluid in the outlet chamber 53, then high-pressure fluid will flow from chamber 53 past the check valve 65 and into the passageways previously described, thus maintaining the fluid in those passageways at a pressure substantially equal to the pressure in the outlet or exhaust chamber 53.

The basic elements of the pump are included in a modified embodiment of the invention which is illustrated in FIG. 4. Component elements of the pump 10 similar to components of the pump structure previously described are identified by the same reference numbers used in FIG. 1. The embodiment illustrated in FIG. 4 of the drawings differs from the one shown in FIG. 1 in that the shaft and rotor in FIG. 4 is one unitary element 15', i.e., the rotor and shaft are made of one piece of metal. By using the unitary rotor and shaft element 15' as illustrated in FIG. 4, it is possible to eliminate the need for the seal 58 and spline connection 26, that are required with the multiple piece structure (rotor 25 and shaft 15) shown in FIG. 1.

From the foregoing, it will be obvious to those skilled in the art that by this invention I have provided a fluid pressure energy translating device including the three-area principle described in the previously mentioned Adams et al. patent wherein there is no material volumetric loss of fluid from that portion of the passageway means which is constantly pressurized to act upon the third area means and that the valve means in the internal passageway means opens only when it is necessary to maintain pressure in the constantly pressurized portion of the passageway means and that the valve means need only open slightly to accomplish this function.

Claims

I claim:

1. A fluid energy-translating device of the vane type comprising:

a casing having side and peripheral walls forming a rotor chamber, circumferentially spaced low and high-pressure ports in the walls;

a rotor supported on a shaft for rotation in the chamber;

vanes mounted in vane slots in the rotor, the vanes and rotor cooperating with the side and peripheral walls to form fluid transfer pockets;

imperforate piston means disposed in the rotor and operable to urge each vane outwardly, each piston having an end surface interconnected with the high pressure port by a fluid passage means, said passage means including a portion within said shaft into which pressure fluid is applied from said pressure port; and

one-way valve means in said passage means within said shaft for preventing release of fluid acting on the end surface of each piston.

2. The fluid energy-translating device of claim 1 wherein the passage means includes a portion on the axis of said shaft and said one-way valve means is in that axial portion.

3. A fluid energy-translating device of the vane type comprising:

a casing having side and peripheral walls forming a rotor chamber, circumferentially spaced low- and high-pressure ports in the walls;

a rotor supported by a shaft for rotation in the chamber;

vanes mounted in vane slots in the rotor, the vanes and rotor cooperating with the side and peripheral walls to form fluid transfer pockets;

imperforate piston means disposed in the rotor and operable to urge each vane outwardly, each piston having an end surface interconnected with the high-pressure port by a fluid passage means internally of the shaft and rotor;

said passage means including a portion extending longitudinally within said shaft into which pressure fluid is admitted radially through said shaft, said passage means also including a portion in said rotor which opens to the end surfaces of the pistons; and

valve means in said longitudinal portion of said passage means for controlling the fluid acting on the end surface of each piston.

4. A fluid energy-translating device of the vane type comprising:

a casing having side and peripheral walls forming a rotor chamber, circumferentially spaced low- and high-pressure ports in the walls;

a rotor supported by a shaft for rotation in the chamber;

vanes mounted in vane slots in the rotor, the vanes and rotor cooperating with the side and peripheral walls to form fluid transfer pockets;

imperforate piston means disposed in the rotor and operable to urge each vane outwardly, each piston having an end surface interconnected with the high-pressure port by a fluid passage means internally of the shaft and rotor; and

valve means for controlling the fluid acting on the end surface of each piston, said valve means being disposed in the fluid passage means internally of the shaft.

5. A fluid energy-translating device of the vane type comprising:

a casing having side and peripheral walls forming a rotor chamber, circumferentially spaced low- and high-pressure ports in the walls;

a rotor supported by a shaft for rotation in the chamber;

vanes mounted in vane slots in the rotor, the vanes and rotor cooperating with the side and peripheral walls to form fluid transfer pockets;

imperforate piston means disposed in the rotor and operable to urge each vane outwardly, each piston having an end surface interconnected with the high-pressure port by a fluid passage means internally of the shaft and rotor; and

valve means for controlling the fluid acting on the end surface of each piston, said valve means being a spring biased ball-type check valve.

6. A fluid energy-translating device of the rotary vane type comprising:

a casing having side and peripheral walls forming a rotor chamber, circumferentially spaced fluid inlet and outlet ports in the wall, the peripheral wall having a cam surface;

a rotor disposed upon a shaft and supported for rotation in the chamber;

vanes projecting from the rotor in slots, the vanes engaging the sidewalls and cam surface to form fluid transfer pockets;

a piston disposed in the rotor in relation to each vane such that a force applied to the pistons will be applied outwardly to each vane;

conduit means provided internally of the rotor and the shaft for supplying fluid under pressure from the outlet port to end surface of the pistons; and

a valve disposed in the conduit means in the shaft for controlling the fluid acting on the end surface of each piston.

7. A fluid energy-translating device of the vane type comprising:

a casing having side and peripheral walls forming a rotor chamber, circumferentially spaced low- and high-pressure ports in the walls;

a rotor supported by a shaft for rotation in the chamber, said rotor being integral with the shaft;

vanes mounted in vane slots in the rotor, the vanes and rotor cooperating with the side and peripheral walls to form fluid transfer pockets;

imperforate piston means disposed in the rotor and operable to urge each vane outwardly, each piston having an end surface interconnected with the high-pressure port by a fluid passage means internally of the shaft and rotor; and

valve means for controlling the fluid acting on the end surface of each piston, said valve means being disposed in the passage means internally of the integral shaft and rotor.

8. A fluid energy-translating device of the vane type comprising:

a casing having side and peripheral walls forming a rotor chamber, circumferentially spaced low- and high-pressure ports in the walls;

a unitary shaft and rotor supported by bearing means for rotation in the chamber;

vanes mounted in vane slots in the rotor, the vanes and rotor cooperating to form fluid transfer pockets;

imperforate piston means disposed in the rotor and operable to urge each vane outwardly, each piston having an end surface interconnected with the high-pressure port by a fluid passage means internally of the unitary shaft and rotor and bearing means; and

valve means for controlling the fluid acting on the end surface of each piston.

9. A fluid energy-translating device, as defined in claim 8, wherein the fluid passageway passes through the sidewall of the bearing means.

10. A fluid energy-translating device of the rotary vane type comprising:

a casing forming side and peripheral walls forming a rotor chamber, circumferentially spaced fluid inlet and outlet ports in the wall, the peripheral wall forming a cam surface;

a rotor connectedly disposed upon a shaft and supported for rotation in the chamber;

a resilient seal disposed between and in sealing engagement with the shaft and rotor;

vanes projecting from the rotor in slots, the vanes engaging the sidewalls and cam surface to form fluid transfer pockets;

pistons disposed in the rotor in relation to each vane such that a force applied to the pistons will be applied outwardly to each vane;

conduit means provided in the shaft, resilient seal and the rotor for supplying fluid under pressure from the outlet port to the underside of the pistons; and

a valve disposed in the conduit means in the shaft for controlling the fluid acting on the end surface of each piston.