Driven Vane Compressor

Abstract

A rotary vane device comprising a rotor and a vane positioned in a pumping chamber in a housing for rotation about respective eccentric axes, wherein the rotor has a rotor slot in which the vane is positioned, characterized by the vane being driven and the rotor following the vane.

Description

FIELD OF THE INVENTION

The present invention relates to rotary vane machines and, more particularly, to a rotary vane machine wherein the vane is driven rather than the rotor.

BACKGROUND OF THE INVENTION

Rotary vane machines are distinguished from virtually all other fluid displacement machines in their remarkable simplicity. The operating efficiency of such machines, however, is negatively impacted by machine friction. Friction in non-guided rotary vane machines can arise from the rubbing of the tip of the sliding vane against the inner contour of the stator wall. Governing the motion of the vane by the stator wall contour also can inhibit the area through which fluid can enter or exit the machine. This can result in increased fluid flow pressure losses in the inlet and outlet port regions.

Over the years, proposals have been made to move the vanes radially other than through the direct action of the vane tips rubbing along the inside casing or stator wall. Prior attempts have focused upon the use of wheels or rollers pinned to the sides of the vanes wherein these rollers follow a circular or non-circular track of an appropriate configuration. The cooperation of the rollers in the roller guide track controls the radial location of the vane which is pinned to the roller follower and hence determines the position of the tip of the vane.

Another known and advantageous fluid-handling device employs a single vane. In essence, this single vane device operates in a manner similar to most conventional vane compressors, with two key exceptions: the rotor incorporates only a single slot for the simple vane, and that vane does not contact the housing while the rotor is spinning. Instead, an extremely thin air gap exists between the vane tip and the stator wall. In operation, air enters through a port on one side of the unit and is compressed by the front side of the vane. The vane's rear side, meanwhile, draws gas into the housing.

SUMMARY OF THE INVENTION

In contrast to the above-mentioned single vane and other rotary vane devices, the present invention provides a rotary vane device wherein the vane is rotatably driven rather than the rotor. This has been found to beneficially reduce the side load acting on the vane, essentially to whatever is the bearing drag acting on the rotor that is rotatably driven by the vane. Benefits arising from the invention include less power consumption, longer life, fewer stack-up tolerances between the vane and housing, the ability to use plastic for the rotor and vane due to the reduced loads, and/or fewer components.

Accordingly, the invention provides a rotary vane device comprising a rotor and a vane positioned in a pumping chamber in a housing, wherein the rotor has a rotor slot in which the vane is positioned, characterized by the vane being driven and the rotor following the vane.

More particularly, the rotary vane device comprises a housing including a pumping chamber having an axis and flow passages for flow of fluid to and from the pumping chamber. A rotor is eccentrically positioned in the pumping chamber and supported in the housing for rotation about an axis eccentric to the pumping chamber axis whereby a variable volume space is formed between a radially outer surface of the rotor and a radially inner surface of the housing. The rotor has a radially extending slot opening to the radially outer surface of the rotor, and a vane drive member is supported in the housing for rotation about the pumping chamber axis. A vane is disposed in the rotor slot and coupled to the vane drive shaft independently of the rotor for rotation with the vane drive member about the pumping chamber axis. The vane has a radially outer end adjacent the radially inner surface of the housing and a side wall for engaging an opposed side wall of the rotor slot while permitting relative radial movement between the vane and the rotor slot, whereby rotation of the vane about the chamber axis will rotatably drive the rotor about the rotor axis within the chamber while the vane moves radially relative to rotor.

The vane drive member may include a drive shaft coaxial with the pumping chamber axis, and the vane may be fixedly joined to the shaft for radial extension away from the shaft.

The rotor slot may increase in width going from a radially outer end of the slot to a radially inner end of the slot, for accommodating relative pivotal movement of the vane relative to the side wall of the slot when the vane is rotatably driven about the pumping chamber axis.

The vane may be attached to the drive shaft by a pair of axially spaced apart vane supports fixed to the drive shaft for rotation with the drive shaft, and the vane may extend axially between the vane supports. The housing may have axially spaced apart side walls defining respective axial ends of the pumping chamber, and the drive shaft may have opposite axial ends supported by bearings in the side walls, respectively. The vane may be radially outwardly spaced from the drive shaft for mass reduction purposes.

The housing may include a stator plate having a through bore forming the pumping chamber, and opposite end plates may close the ends of the pumping chamber.

The radially inner surface of the housing preferably is curved concentrically around the pumping chamber axis, and the radially outer surface of the rotor preferably is curved concentrically around the rotor axis.

A seal member may be provided at the radially outer end of the vane for sealingly engaging the radially inner surface of the housing.

The rotor may have opposite ends thereof supported by respective bearings in the housing. Each bearing may include an inner race, an outer race and anti-friction elements between the inner and outer races.

The vane and rotor may be about equal in longitudinal length, and they may be rotationally (dynamically) balanced.

The radially outer end of the vane may be convexly curved concentrically with the pumping chamber axis.

Further features of the invention will become apparent from the following detailed description when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

In the annexed drawings:

FIG. 1 is a perspective view of a rotary vane device in accordance with the invention;

FIG. 2 is a perspective view of the rotary vane device of FIG. 1, but with an end plate removed to show interior components of the device including bearing elements;

FIG. 3 is a perspective view similar to FIG. 2, but with bearing elements removed;

FIG. 4 is a perspective view similar to FIG. 3, but with a rotor end member removed from the rotor body to show an end of a vane and drive member assembly;

FIG. 5 is an end elevational view of the rotary vane device of FIG. 1, with the end plate removed to show interior components of the device including bearing elements;

FIG. 6 is a perspective view of the vane and drive member assembly; and

FIGS. 7-10 are views similar to FIG. 4, but shown in end elevation with the vane and drive member assembly shown at relatively rotated positions.

DETAILED DESCRIPTION

Referring now to the drawings in detail, and initially to FIGS. 1-5, an exemplary rotary vane device according to the invention is designated generally by reference numeral 20. As shown, the device 20 generally comprises a housing 21, a rotor 22 (FIGS. 3 and 4) and a vane and drive assembly 23 (FIGS. 4 and 6). In the illustrated embodiment, the vane and drive assembly 23, as best seen in FIG. 6, comprises a single vane 26 mounted, or formed integrally with, a vane drive member 27. Although these components will be described below in greater detail, it will be appreciated that such components can vary in various respects without deviating from the basic principles of the present invention. In addition, the illustrated rotary vane device is particularly suited for use as a gas compressor and will be chiefly described in this context. A rotary vane device according to the invention, however, may be adapted for use with other fluids, in particular as a pump for liquids. Additionally, as is typical of many conventional compressors and pumps, the rotary vane device 20 can be reversely operated as a motor, where pressurized fluid is supplied to the device to effect rotation of the vane 26 to output a rotary motion. Those skilled in the art will readily appreciate the reversibility of the operation of the rotary vane device.

Turning now to details of the various components, the housing 21 includes a pumping chamber 30 having an axis 31 and ports formed by inlet/outlet port members 34 and 35 for flow of fluid to and from the pumping chamber. The ports can be positioned in a conventional manner for supplying fluid to the pumping chamber and discharging pressurized fluid from the pumping chamber when operating as a compressor or pump, or conversely when operating as a motor.

Preferably the housing 21 is assembled from several components. As shown, the housing 21, which may be supported by a bracket 37, includes a stator plate (block) 38 having a through bore forming the pumping chamber 30, and opposite end (cover) plates 40 and 41 that close the ends of the through bore. The through bore is bounded by a radially inner surface 42 of the housing that preferably is curved concentrically around the pumping chamber axis, as is typical of known rotary vane type devices. The stator and end plates may be assembled together and secured to one another by suitable fasteners, such as the illustrated screws 43. In the illustrated embodiment, the cylindrical wall of the stator plate 38 is provided with two openings that are covered by the port members 34 and 35.

The rotor 22 is eccentrically positioned in the pumping chamber 30 and supported in the housing 21 by bearings for rotation about an axis 49 eccentric to the pumping chamber axis 31 whereby a variable volume space is formed between a radially outer surface 50 of the rotor and the radially inner surface 42 of the housing. Preferably, the radially outer surface of the rotor is curved concentrically around the rotor axis. That is, the rotor is in the form of a right cylindrical body.

As above noted, the rotor 22 is supported by bearings in the housing 21. One such bearing is indicated at 53 in FIGS. 2 and 5, the bearing 53 having been removed in FIGS. 3 and 4. Although any suitable bearing may be employed, the bearing 53 includes an inner race 54 and an outer race 55 with a plurality of anti-friction elements, such as ball bearings, interposed therebetween. The inner race 54 is fitted on a tubular stub shaft 56 (FIG. 3) projecting from the rotor 22. In the illustrated embodiment, the stub shaft is provided on a rotor end member 57 fastened to an axial end of a rotor body 58 by suitable means, such as the fasteners 59. The outer race is received in a correspondingly sized pocket formed in the end plate 40 of the housing. A similar arrangement is provided at the other end of the rotor. The bearings 53 provide for essentially friction-free rotation of the rotor in the pumping chamber about the rotor axis 49.

The rotor 22, at its top as shown in FIG. 5, is in near contact with the inner surface 42 of the stator plate 38. This provides a non-contact seal between the rotor and the inner surface of the stator plate at a location between the inlet/outlet ports 34 and 35, thereby isolating one from the other although some leakage may occur. Consequently, the radius of the rotor plus the offset is only slightly less than the radius of the pumping chamber 30 so that no contact will occur while still minimizing any leakage between the rotor and the inner surface of the bore. On the other hand, the radius of the rotor should not be greater than the radius of the pumping chamber less offset between the pumping chamber axis and the rotor axis. Otherwise the outer surface of the rotor would engage the inner housing surface and preclude rotation of the rotor.

The rotor 22 also is provided with a radially extending vane slot 68 opening to the radially outer surface of the rotor as best seen in FIG. 4. In the illustrated embodiment, the slot 16 extends the entire longitudinal length of the rotor body 58 which in turn is equal in width of the pumping chamber 30, except for provision of necessary clearances to allow rotation of the rotor in the pumping chamber. Because the slot reduces the mass of the rotor on the side containing the slot, the other side may have material removed to dynamically balance the rotor, as desired.

The slot 68 in the rotor 22 is configured to receive the vane 26, which may have generally parallel side walls and a longitudinal length essentially the same as the longitudinal length of the rotor body 58. In the illustrated embodiment, the vane is integrally formed as part of the vane and drive assembly 23. The vane and drive assembly, as best seen in FIG. 6, further comprises a drive shaft (axle) 69 that is supported at each end by a respective bearing 71 in the housing for rotation about the pumping chamber axis 31. Although any suitable bearing may be employed, the bearing 71 includes an inner race and an outer race with a plurality of anti-friction elements, such as ball bearings, interposed therebetween. The inner race is fitted on a reduced diameter end portion 72 of the shaft. The outer race is received in a correspondingly sized pocket formed in the end plate 40 of the housing 21. The bearing 71 is axially outwardly spaced in relation to the bearing 53 that rotatably supports the rotor stub shaft 56. The bearing 71 and 53 will also be radially offset from one another to provide the offset between the rotor axis 49 and the pumping chamber axis 31. A similar arrangement is provided at the other end of the vane shaft 69.

The vane 26 preferably is fixedly joined to the drive shaft 69 for radial extension away from the shaft. As shown in FIG. 6, the vane may be attached to the drive shaft by a pair of axially spaced apart vane supports 75 and 76 fixed to the drive shaft for rotation with the drive shaft, and the vane may extend axially between the vane supports. The vane may be radially outwardly spaced from the drive shaft, particularly for mass reduction purposes. The vane preferably is dynamically balanced and to this end a counterweight 77 may be assembled between the vane supports diametrically opposite the vane.

The vane 26 preferably has a radial length such that its radially outer end is in near contact with the inner surface 42 of the stator plate 38. That is, the outer end (or tip) of the vane is spaced from the inner surface 42. This provides a non-contact seal between the vane and the inner surface 42. Opposite sides of the vane when projecting from the rotor form respective ends of variable volume spaces between the rotor and inner surface of the stator plate, although some leakage may occur through the small gap between the vane end and inner surface of the stator plate. The radially outer end of the vane may be convexly curved concentrically with the pumping chamber axis 31. A clearance between the vane tip and the inner surface 42 surrounding the stator bore, in the range of 0.002 inches to 0.004 inches, has been found to provide desirable operating results while still permitting relatively low cost for manufacture of the unit. The same clearance can be provided between the top of the rotor 22 and the inner surface 42.

At its radially outer end, side walls of the vane 26 are positioned adjacent and for sliding engagement with respective side walls of the rotor slot 68 such that upon rotation of the vane, the leading side wall of the vane will push against the opposed side wall of the rotor slot while permitting relative radial movement between the vane and the rotor slot. In this manner, rotation of the vane about the chamber axis will rotatably drive the rotor 22 about the rotor axis 49 within the pumping chamber 30 while the vane moves radially relative to rotor. In the illustrated embodiment, surfaces of the vane and rotor function as bearing surfaces that provide the sliding engagement between the vane and slot in the rotor. As will be appreciated, such sliding engagement can be effected by other means such as the use of bearing devices, for example roller bearings.

Any suitable means may be provided for transfer of rotary motion from outside the housing to the vane 26 for use of the rotary vane device as a compressor/pump, or for taking out rotary motion from the vane for use of the device as a motor. In the illustrated exemplary embodiment, one end of the drive shaft 69 is extended to project axially from the housing for coupling to an external device, such as a prime mover (e.g. electric motor, engine, etc.) or to a component to be driven by the device if used as a motor.

It can now be appreciated that the vane 26 is coupled to a vane drive, in particular the vane drive shaft 69, independently of the rotor 22 for rotation with the vane drive member about the pumping chamber axis. That is, vane is driven and the rotor follows the vane. This is in contrast to the conventional arrangement where the rotor is driven instead of the vane.

In the case where the vane 26 is fixed to the drive shaft 69 against any relative movement, the vane, during rotation about the pumping chamber axis, will pivot relative to the rotor slot 68 while still drivingly engaging the rotor. To accommodate this relative pivotal movement, the rotor slot 68 in the rotor increases in width going from the radially outer end of the slot to a radially inner end of the slot.

If desired, a seal member may be provided at the radially outer end of the vane 26 for sealingly engaging the radially inner surface 42 of the housing. The seal member may be a vane seal held and guided in a slot in the end of the vane such that the vane seal can move radially relative to the vane. The seal may be biased against the inner surface surrounding the pumping chamber or reliance can be had on centrifugal force to cause the seal to be urged radially outwardly against the inner surface when the vane is rotated.

As will now be appreciated by those skilled in the art, the driving of the vane 26 rather than the rotor 22 will beneficially reduce the side load acting on the vane, essentially to whatever is the bearing drag acting on the rotor that is rotatably driven by the vane. This leads to less power consumption, longer life, fewer stack-up tolerances between the vane and housing, the ability to use plastic for the rotor and vane due to the reduced loads, and/or fewer components. As noted, the rotor and vane can be made of plastic, such as a suitable nylon of PFE material. For other applications, a carbon rotor and ceramic ball bearings can be used to stand up to corrosion associated with the hydrogen on board in fuel cells when the device is used as a compressor for hydrogen recirculation. Another version may employ steel ball bearings, as when the device serves as a cathode air compressor, for example in a fuel cell stack. In addition, many of the components can be formed from extrusions.

In operation, rotation of the vane 26 in a clockwise direction in FIGS. 6-9 will cause fluid, such as a gas, to be drawn in from the port 35 then functioning as an inlet port. This gas will flow into the expanding volume space behind vane as the vane moves clockwise from its position shown in FIG. 6. At the same time, the gas volume in front of the rotating vane will be decreasing in size as the rotor vane assembly continues to rotate to its positions shown in FIGS. 7 and 8. When the pressure within the compressing volume ahead of the vane exceeds the pressure into which the compressed gas is to be discharged, the gas will flow out through the other port 34.

Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.

Claims

1. A rotary vane device comprising: a housing including a pumping chamber having an axis and flow passages for flow of fluid to and from the pumping chamber;a rotor eccentrically positioned in the pumping chamber and supported in the housing for rotation about an axis eccentric to the pumping chamber axis whereby a variable volume space is formed between a radially outer surface of the rotor and a radially inner surface of the housing, the rotor having a radially extending slot opening to the radially outer surface of the rotor;a vane drive member supported in the housing for rotation about the pumping chamber axis; anda vane disposed in the rotor slot and coupled to the vane drive shaft independently of the rotor for rotation with the vane drive member about the pumping chamber axis, the vane having a radially outer end adjacent the radially inner surface of the housing and a side wall for engaging an opposed side wall of the rotor slot while permitting relative radial movement between the vane and the rotor slot, whereby rotation of the vane about the chamber axis will rotatably drive the rotor about the rotor axis within the chamber while the vane moves radially relative to rotor.

2. A rotary vane device according to claim 1, wherein vane drive member includes a drive shaft coaxial with the pumping chamber axis, and the vane is fixedly joined to the shaft and extends radially from the shaft.

3. A rotary vane device according to claim 1, wherein the rotor slot increases in width going from a radially outer end of the slot to a radially inner end of the slot, for accommodating relative pivotal movement of the vane relative to the side wall of the slot when the vane is rotatably driven about the pumping chamber axis.

4. A rotary vane device according to claim 2, wherein the vane is attached to the drive shaft by a pair of axially spaced apart vane supports fixed to the drive shaft for rotation with the drive shaft, and the vane extends axially between the vane supports.

5. A rotary vane device according to claim 2, wherein the housing has axially spaced apart side walls defining respective axial ends of the pumping chamber, and the drive shaft has opposite axial ends supported by bearings in the side walls, respectively.

6. A rotary vane device according to claim 2, wherein the vane is radially outwardly spaced from the drive shaft.

7. A rotary vane device according to claim 1, wherein the rotor has opposite ends thereof supported by respective bearings in the housing.

8. A rotary vane device according to claim 7, wherein each bearing includes an inner race, an outer race and anti-friction elements between the inner and outer races.

9. A rotary vane device comprising a rotor and a vane positioned in a pumping chamber in a housing, wherein the rotor has a rotor slot in which the vane is positioned, characterized by the vane being driven and the rotor following the vane.

10. A rotary vane device according to claim 1, wherein the rotor slot increases in width going from a radially outer end of the slot to a radially inner end of the slot, for accommodating relative pivotal movement of the vane relative side wall of the slot when the vane is rotatably driven about the pumping chamber axis.

11. A rotary vane device according to claim 1, wherein the housing has axially spaced apart side walls defining respective axial ends of the pumping chamber, and the rotor and vane are rotatably supported by respective eccentrically disposed bearings in each side wall.

12. A rotary vane device according to claim 1, comprising a seal member at the radially outer end of the vane for sealingly engaging the radially inner surface of the housing.

13. A rotary vane device according to claim 1, wherein the housing includes a stator plate having a through bore forming the pumping chamber, and opposite end plates closing the ends of the pumping chamber.

14. A rotary vane device according to claim 1, wherein the vane and rotor are about equal in longitudinal length

15. A rotary vane device according to claim 1, wherein the rotor and vane are each rotationally balanced.

16. A rotary vane device according to claim 1, wherein the radially outer end of the vane is convexly curved concentrically with the pumping chamber axis.

17. A rotary vane device according to claim 1, wherein the radially inner surface of the housing is curved concentrically around the pumping chamber axis.

18. A rotary vane device according to claim 1, wherein the radially outer surface of the rotor is curved concentrically around the rotor axis.