RADIAL VANE PUMP OR MOTOR WITH ROLLING CHAMBER

Abstract

A radial vane pump or motor device includes a stationary housing provided with a cylinder supported for rotation relative to the housing about a central axis. A rotor is fixed to a shaft for rotation with the cylinder about an axis offset or eccentric relative to the central axis. A plurality of vanes slide radially in the rotor for contact with the inner surface of the cylinder.

Description

BACKGROUND OF THE INVENTION

1. Technical Field

This invention related generally to vane pumps and motors.

2. Related Art

Radial vane pumps and motors are known in which a rotor is disposed within a fixed housing and mounted on an off-center shaft. Slideable vanes are supported by the rotor and slide in and out to maintain contact with the inner housing wall. The rotation of the vanes in contact with the housing creates chambers of changing volume. In the case of a pump, fluid enters the housing at a large chamber and is forced to exit under pressure through an outlet at a smaller chamber. The opposite occurs in the case of a motor, wherein fluid enters at a small chamber and exits at a large chamber while imparting rotation to the shaft via the vanes and rotor.

High friction can occur at the tips of the vanes as they rub against the wall of the fixed housing, impairing the efficiency of such pumps and reducing their longevity.

BRIEF SUMMARY OF THE INVENTION

A radial vane pump or housing in accordance with one aspect of the invention includes a stationary housing, a rotatable shaft mounted off-center within the housing; a rotor fixed to said shaft for rotation therewith within the housing; a plurality of radially disposed vanes slideably supported by said rotor; and a cylinder disposed within and supported for rotation relative to said housing and to said rotor and having a radially inner wall thereof disposed in contact with outer ends of said vanes.

The inclusion of a rotatable cylinder between the fixed housing and rotatable vanes has the beneficial effect of reducing excessive friction and drag of the vanes running against the housing. It further prolongs the life cycle of vane pumps and motors. Only when the pressure within a chamber exceeds the force of frictional drag between the vanes and cylinder will the vanes be caused to slide relative to the cylinder, otherwise the cylinder rotates with the vane and the same or lesser rate.

According to an embodiment, the rotatable support of the cylinder may be provided by rolling element bearings, such as a roller or ball bearings, disposed between the housing and cylinder.

According to an embodiment, the rotatable cylinder may take the form of a rolling element bearing having an outer race that is pressed into the housing and fixed against rotation, an inner race having an inner surface thereof in contact with the vanes, and a plurality of bearing elements disposed between the inner and outer races for supporting the inner race for rotation relative to the outer race.

According to a further aspect, the housing may be provided with an adjustment screw that is operative to impart a radial displacement load on the outer race to urge it inwardly toward the inner race preferably at the close point of the inner race where it is nearest to the axis of the rotor shaft to control contact pressure of the vane at or near the close point.

According to another embodiment, the rotatable cylinder may be vented and through which vents the inlet and outlet ports in the housing may communicate with the variable volume chambers formed by the interaction of the vanes and cylinder.

According to another embodiment, the vanes may be magnetically biased toward engagement with the rotatable cylinder.

THE DRAWINGS

These and other aspects of the present invention will be more readily appreciated when considered in conjunction with the accompanying description and drawings, in which

FIG. 1 is a schematic cross-sectional view of a first embodiment of the invention;

FIG. 2 is a schematic cross-sectional view of a second embodiment of the invention;

FIG. 3 is a schematic cross-sectional view of a third embodiment of the invention; and

FIG. 4 is a schematic cross-sectional view of a fourth embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 illustrates a radial vane pump or motor device 10.

The device 10 has a stationary housing 12 with a chamber 14.

A cylinder or cylindrical drum or sleeve 16 is disposed within the chamber 14. The cylinder 16 has a central cylinder axis A. The cylinder 16 is rotatable about the axis A relative to the stationary housing 14. Support for rotation may be provided by a bearing 18. The bearing 18 may take the form of a plurality of rollable elements, such as roller or ball bearings disposed between the outer surface of the cylinder 16 and the inner surface of the housing chamber 14 to provide low friction support of the cylinder for free rotation relative to the housing 12. The inner surface of the cylinder 16 defines a cylindrical space in which a rotor 20 is disposed. The rotor 20 is cylindrical and smaller in diameter than that of the cylindrical space of the cylinder 16. The rotor 20 is mounted on a shaft 22 for rotation therewith. The shaft 22 is supported by the housing 12 for rotation relative to the housing 12 about an axis B of the shaft 22 and rotor 20. The axis B is offset relative to the axis A of the cylinder, meaning the rotor is supported off center within the cylindrical space of the cylinder 16.

The rotor 20 supports a plurality of radial vanes 24 which are slidable in and out relative to the rotor 20 within radial slots 26 of the rotor 20 to cause outer tips of the vanes to contact the inner diameter surface of the cylinder 16 during rotation of the rotor 20. As the rotor 20 rotates with the shaft 22 relative to the housing 12, the vane tips are caused to sweep across the inner surface of the cylinder 16. The offset relation of the rotor axis B in relation to the cylinder axis A creates wedge-shaped spaces between adjacent vanes 24 which are variable in volume, both in relation to one another (i.e., wedge-to-wedge) and in relation to a given space as it rotates with the rotor 20 and the vanes 24 are caused to slide inward and outward in the rotor 20 while maintaining contact with the inner cylinder wall 16. The offset arrangement of the rotor relative to the cylinder presents a wedge of greatest space of volume at the point where the outer surface of the rotor 20 is furthest from the inner surface of the cylinder 16, and a space of minimum volume (the close point) where the outer surface of the rotor is closest to the inner surface of the cylinder 16. These extremes are shown at the top and bottom, respectively, of FIG. 1. Fluid inlets and outlets 28, 30 are provided at these locations. In the case of a pump, the fluid inlet 28 is provided at the maximum volume space where a fluid such as air or steam is introduced to the largest space and as the rotor 20 is driven under power by the shaft 22 the decreasing volume of the spaces formed between the rotor and cylinder wall in cooperation with the vanes 24 as they retract into the rotor, the fluid is caused to be compressed whereupon it exits the outlet port 30 at or near the close point under higher pressure. In the case of a motor, the opposite arrangement is provided, wherein fluid under pressure is introduced at or near the close point and is caused to act upon and rotate the vanes and rotor to drive the shaft and then exists the outlet port at or near the large volume space.

According to a particular aspect of the invention, the rotatable cylinder 16 is able to rotate relative to the housing 12 and rotor 20 during operation of the device 10. More particularly, the offset axes A and B and different diameters between the cylinder 16 and rotor 20 cause the rotor 20 and cylinder 16 to rotate at different speeds such that there is both slippage between the vanes 24 as they sweep across the inner surface of the cylinder 16 while at the same time the cylinder 16 is rotating in the same direction as the rotor 20. It is believed that rotation of the cylinder lends to increased longevity and decreased wear over time, as the interaction between the vanes 24 and cylinder 16 is modified by enabling rotation of the cylinder 16.

As mentioned, the cylinder 16 is preferably supported by bearings 18. There are at least three such bearings and more preferably many more such that they provide maximum support of the cylinder 16 without interfering with one another. In the embodiment of FIG. 2, the same arrangement is shown as in the embodiment of FIG. 1 (and the same reference numerals are used but are offset by 100) except that the cylinder 116 in this case is in the form of a full bearing 118 including an inner race 116a, and outer race 116b and a plurality of rolling elements 116c captured between the inner and outer races. The outer race 116b is pressed into the housing 112 and is stationary therewith, whereas the inner race 116a is free to rotate as in the embodiment of FIG. 1. Also provided is an adjustment device in the preferred form of a set screw 32. The screw 32 is threaded in the housing 112 and has a leading and prefereably pointed free end is able to act with force when turned on the outer surface of the outer race 116b and may preferably be received in a corresponding recess in the outer race 116b. The location is preferably at the close point and the purpose is to be able to adjust with micro-precision the position of the bearing 118 relative to the outer surface of the rotor 120 at the close point. In practice, tightening the set screw 32 urges the outer race 116b inward and in turn forces the inner race 116a further inward toward the rotor 120 at the close point to in effect squeeze the effected components at the close point in order to adjust the sealing effect of the fluid. Once initially calibrated, the device 110 should operate without need for further adjustment.

FIG. 3 shows another variant which is the same as described above in relation to the embodiment of FIG. 1 (and same reference numerals are used except offset by 200), except that the vanes 224 in this embodiment are magnetically biased toward engagement with the cylinder wall 216. The can be achieved by providing a magnetic pole (such as south) at the base of the vane slots and an identical magnetic pole (i.e., south in this example) on the bottom ends of the vanes 224 which has the effect of magnetically forcing the vanes 224 outward of the slots and toward the cylinder wall 226.

Finally, FIG. 4 shows yet another embodiment which is the same as that described in FIG. 1 (and the same reference numerals used except offset by 300), except that the rotating cylinder 316 is vented at 34 (i.e., plurality of vents or openings in cylinder wall) and these vents 34 cooperate with inlet and outlet ports in the housing through reed valves 36.

The above illustrated and described embodiments are intended to be representative but not limiting of the invention. The invention is defined in the accompanying claims.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that the invention may be practiced otherwise than as specifically described while still being within the scope of the invention.

Claims

1. A sliding vane pump or motor device, comprising: a housing;a cylinder disposed within the housing and having a central cylinder axis A;a shaft supported for rotation relative to the housing about a shaft axis B;a rotor fixed for rotation with the shaft within the cylinder;a plurality of radial vanes slideably supported by the rotor for engaging an inner wall of the cylinder;the shaft axis B being offset relative to the cylinder axis A; andwherein said cylinder is rotatable relative to both the housing and the rotor.

2. The device of claim 1 including a rolling element bearing supporting the cylinder 16 for rotation relative to the housing.

3. The device of claim 2 wherein the rolling element bearing includes ball or roller elements.

4. The device of claim 1 including a bearing having an outer race, an inner race and a plurality of rolling elements captured between the inner and outer races, and wherein the outer race is pressed into the housing and the inner race forms the rotatable cylinder whose inner surface is engaged by the vanes.

5. The device of claim 4 including an adjustment screw supported by the housing and selectively acting on the outer race for displacing the bearing relative to the housing in a radial direction.

6. The device of claim 1 wherein the cylinder is provided with a plurality of vents.