GB2219630A - Oscillating-vane pumping and transmission device - Google Patents

Abstract

The device comprises a housing in which are mounted three sector-shaped vanes 8-10. The vanes are oscillated circumferentially to effect pumping by varying the volume of the chambers 14, 15, 16 defined between them. The vanes are oscillated by means of crank shafts (17, Fig. 1) which are coupled to respective vanes by means of bearing blocks 19 mounted on the crank pins 18 of the crank shafts. Each crank shaft has fixed thereon a gear (21) which is in mesh with a common gear (22) driven by an input shaft (23). The housing may be rotatably mounted in which case by controlling the outlet pressure of the pumping device the torque transmitted from the input shaft to the housing may be controlled so that the pumping device acts as a variable torque transmission device. <IMAGE>

Description

RECIPROCATING VANE PUMPING DEVICE This invention relates to a pumping device and in the preferred embodiment provides a reciprocating vane pumping device which can be used either simply as a pump, or can be used as a variable ratio rotary coupling.

According to one aspect of the present invention there is provided a pumping device comprising a housing having an inner right circular cylindrical wall; an inner right circular cylindrical wall coaxial with the outer wall t. define therebetween an annular space; a plurality of generally sector-shaped vanes mounted in the annular space, each vane including part cylindrical inner and outer walls disposed adjacent the inner and outer walls respectively of the housing whereby a chamber is defined between each pair of vanes; inlet means for supplying fluid to each chamber; outlet means for receiving fluid from each chamber; a respective crankshaft associated with each vane, each crankshaft being rotatably mounted in the housing and being coupled to its associated vane such that continuous rotation of the crankshaft relative to the housing produces circumferential reciprocating movement of the vane relative to the housing; and means for rotating the crankshaft to reciprocate the vanes and thereby cyclical vary the volume of each chamber whereby fluid may be supplied to each chamber via the inlet means when the volume of the chamber is at or close to its maximum and then pressurized as the volume of the chamber is reduced by movement of the vanes.

In the preferred embodiment of the invention the means for rotating the crankshafts comprises a respective gear secured to each crankshaft, the crankshaft gears being in mesh with a common drive gear which is rotated by an input shaft about the axis of the cylindrical walls to rotate the crankshaft gears and thus the crankshafts. With such an arrangement, a single continuous rotary input will effect the desired reciprocation of all vanes. Further, because each vane is driven by a crankshaft which carries a gear in mesh with the drive gear, the correct phase relationship between the crankshafts will be maintained throughout operation of the pumping device.

In the preferred embodiment of the invention in which the input drive is a rotary drive delivered to a drive gear which is mounted to rotate about the axis of the cylindrical walls, it will be necessary to restrain the housing against rotation in order to drive the crankshafts to reciprocate the vanes. If no restraint against rotation of the housing is provided, the housing will spin as a unit with the drive gear, and there will be no rotation of the drive gear relative to the housing. If, in the alternative, the housing is fixed against rotation the rotating input will drive the crankshafts and thereby reciprocate the vanes relative to the housing in order to deliver pressurized fluid via the outlet means.The torque required to restrain the housing against rotation will increase as the pressure differential between the fluid supplied to the inlet means and the maximum chamber pressure at top dead centre increases.

It follows from this that if the housing of the pumping device is used as a rotary output drive, for example by connecting an output drive shaft to the housing for rotation about the axis of the cylindrical walls, the torque which can be transmitted from the rotary input to the rotary output can be varied by variably throttling the pressurized fluid leaving the outlet means. In particular, if pressurized fluid is permitted to leave the outlet means without restriction the pumping device will transmit very little torque from the input to the output, i.e. very little torque at the output will be necessary to prevent rotation of the housing.In the alternative extreme case in which outlet from the chambers is substantially prevented, the crankshafts will be prevented from rotating and the housing, vanes, and crankshaft will turn as a unit with the drive gear and the full input torque will be transferred to the output.

It will accordingly be appreciated that the pumping device may either be used simply as a pump, or as a variable ratio drive coupling in which the speed and torque of the output shaft may be varied from zero up to substantially the speed and torque of the input drive by controlling the pressure at which fluid is permitted to leave the chambers.

In one embodiment of the invention the inner cylindrical wall is defined by the housing, and the crank pin of each crankshaft extends through a radially oriented slot in its associated vane. In this way, the radially inner and outer peripheral surfaces of each vane are of simple part-cylindrical shape. In this case, the inner cylindrical wall of the housing is preferably hollow and is formed with ports which are opened and closed by the vanes as they reciprocate within the annular space. The inlet means is then constituted by the hollow interior of the inner cylindrical wall and the ports formed therein.

In an alternative embodiment of the invention the crankshafts are located exterior to the annular space, and each vane is mounted on a tube which extends from the vane through an end plate closing the annular space. The end of the tube remote from the vane carries one or more radially outwardly extending arms which are engaged by the crank pin of the crankshaft in order to reciprocate the arm in the circumferential direction, and thereby reciprocate the vane via the mechanical connection formed by the tube. Such an arrangement is particularly desirable if each tube carries a diametrically opposed pair of vanes and a pair of diametrically opposed radial arms, each engaged by a respective crankshaft.

In a particularly preferred embodiment of the invention there are three tubes each carrying two vanes and two radially extending arms whereby the pumping device comprises six vanes and six crankshafts. The tubes are nested within each other and each have a cylindrical surface whereby the cylindrical surfaces of the tubes together constitute the inner cylindrical wall. Each vane is accordingly fixed to one tube, and includes an inner part-cylindrical surface which slides over the cylindrical surfaces of the other tubes as the vanes reciprocate. In this case, the various tubes may be formed with ports which, at the correct moment for fluid admission, will be aligned to permit fluid to flow into a chamber from the interior of the innermost tube.

The invention will be better understood from the following description of preferred embodiments thereof, given by way of example only, reference being had to the accompanying drawing wherein: Figure 1 is an axial cross-sectional view taken on the line I-I of Figure 2 of one embodiment of the invention; Figure 2 is a radial cross-section taken on the line II-II of Figure 1; Figure 3 is an exploded isometric view of components of the embodiment of Figures 1 and 2; Figure 4 is a view corresponding to Figure 1 of a second embodiment of the invention; Figure 5 is a schematic axial view of the vanes and crankshafts of the embodiment of Figure 4 illustrating the phase relationship therebetween; and Figure 6 is an isometric view of one of the vane units of the embodiment of Figures 4 and 5.

Referring firstly to Figures 1-3 the pumping device 1 comprises a housing 2 having an outer right circular cylindrical wall 3 and a coaxial inner right circular cylindrical wall 4. The walls are interconnected by end plates 5,6 and define an annular space 7 bounded on the outer periphery by the wall 3, on the inner periphery by the wall 4 and at each end by the plates 5,6.

Three generally sector-shaped vanes 8,9,10 are mounted within the annular space 7, each vane having an outer part-cylindrical wall 11 disposed adjacent the wall 3, and an inner part cylindrical wall 12 disposed adjacent the wall 4. If desired, sliding seals can be provided between the wall 11 and the wall 3 on the one hand and between the wall 12 and the wall 4 on the other hand, but in general this should not be necessary.

Each vane further includes two radial walls 13 whereby three chambers 14,15,16 are defined within the annular space. Each chamber is bounded by the walls 3 and 4, and by opposed walls 13 of an adjacent pair of vanes.

In use, the vanes 8-10 reciprocate in the circumferential direction within the annular space 7 whereby the volume of the chambers 14-16 is cyclically varied as described in greater detail hereinafter.

In order to reciprocate the vanes each vane has associated therewith a respective crankshaft 17. The crankshafts are rotatably mounted in the end plates 5,6 and each includes a crank pin 18 rotatably received in a bearing block 19 which is free to slid within a respective slot 20 formed in the associated vane. It will be appreciated that continuous unidirectional rotation of a crankshaft will produce circumferential reciprocating movement of its associated vane with an amplitude determined by the through of the crank.

Each crankshaft has fixed thereon a gear 21, the three gears 21 being in mesh with a common drive gear 22 which is keyed to an input drive shaft 23. Rotation of the shaft 23 relative to the housing will cause simultaneous rotation of the gears 21, and thereby simultaneous rotation of the crankshafts 17 and corresponding reciprocating movement of the vanes within the annular space 7. Because the gears 21 remain permanently in mesh with the drive gear 22 the phase relationship between the vanes determined by the initial setting of the gears will be maintained as the vanes reciprocate.

Fluid to be pumped is supplied by inlet means comprising the hollow interior 24 of the wall 4 and ports 25 in the wall 4. Suitable outlet means are provided for fluid pressurized by the pump, for example non-return valves prnvided in the end plate 6.

Operation of the above described pumping device will be best understood by considering movement of the vanes 8 and 10 from the position illustrated in Figure 2.

As viewed in Figure 2, all crankshafts are rotating clockwise and the crank pin of the crankshaft associated with the vane 10 is located such that the vane 10 is in its extreme anti-clockwise position relative to the central axis 27 of the housing and is about to start moving clockwise about this axis. At this point, the port 25 associated with the chamber 14 is open so that fluid to be pressurized is admitted to the chamber 14 via the port 25 and the hollow interior 24 of the inner wall 4.

As the vane 10 starts to move clockwise it will begin to close the port 25. At this time the vane 8 will still be moving clockwise because of the phase relationship between the cranks associated with the vanes 10 and 8.

Accordingly, there will at this time be substantially no change in the volume of the chamber 14, and accordingly fluid will not be discharged through the port 25. Shortly after the vane 10 closes the port 25 the vane 8 will arrive at its extreme clockwise position relative to the axis 27, and will start to move anti-clockwise. At this time the vane 10 will still be moving clockwise, and accordingly the confronting faces 13 of the vanes 10 and 8 will move rapidly towards each other, pressurizing the contents of the chamber 14. When the pressure within the chamber 14 exceeds a value determined by the conditions prevailing at the outlet means, pressurized fluid will be discharged from the chamber 14. This process will continue until the pistons 8 and 10 arrive at a minimum spacing.In Figure 2, the minimum spacing between two pistons is that spacing illustrated between the pistons 9 and 10. It will be noted that the unswept volume of the chambers is very small, and accordingly the pumping device is capable of achieving a very high compression ratio.

The chamber 14 will attain its minimum value shortly after the piston 10 has attained its most clockwise position relative to the axis 27, and has started to move again in the anti-clockwise direction. At this time, the vane 8 will still be moving in the anti-clockwise direction and accordingly for a portion of the stroke of both vanes the volume of the chamber 14 will remain close to its minimum value, although the actual position of the chamber relative to that housing will move anti-clockwise.

Eventually, the vane 8 will achieve its fully anticlockwise position and will start to move again in the clockwise direction, whilst the vane 10 continues to move anti-clockwise. At about this time the port 25 will again be uncovered and fluid will be admitted to the partially evacuated chamber 14.

The operating cycles of the remaining chambers will be as described above in relation to chamber 14, the pumping chamber moving clockwise around the housing as the vanes reciprocate.

As illustrated in Figure 3, the vanes may be fabricated to two parts having a hollow interior in order to reduce the moment of inertia of the vanes.

Although in the illustrated embodiment of the invention there are three vanes, other embodiments are possible. For example, in the embodiment of Figures 4-6 a total of six vanes are provided.

Referring now to Figures 4-6 there is shown a second embodiment of the invention. In this embodiment the pumping device 101 comprises a housing 102 including a right circular cylindrical wall 103. A second right circular cylindrical wall 104 is coaxial with the wall 103.

End plates 105 and 106 extend between the walls 103 and 104 and close the axial ends of an annular space 107 defined between the walls 103 and 104. Six generally sector shaped vanes 108,108A,109,1099,110 and 110A are located within the annular space 107 to define six pumping chambers.

Referring to Figure 6, the vanes 108 and 108A are diametrically opposed and are both secured to a common tube 128. Similarly, each pair of diametrically opposed vanes 109,109A and 110,110A are secured to respective common tubes 129 and 130. The tubes 128-130 are nested within each other and extend through the end plate 5 to a point external of the annular space 107. The inner wall 104 is made up of surface portions of the tubes 128-130. Each vane accordingly includes at its inner periphery a portion which is secured to its associated tube, and a part cylindrical portion which is located closely adjacent to the portions of the remaining tubes forming the wall 104.

Referring again to Figure 6, the tube 128 carries at its outer end a pair of radially extending arms 131,132 each of which is formed with a slot 133 for receiving a bearing block 119 generally similar to the bearing blocks 19 of Figure 2. Each bearing block 119 receives the crank pin 118 of a crankshaft 117 which is located external to the annular space 107, and is journaled in the housing.

Continuous rotation of the crankshafts 117 in the same direction will cause the radial arms 112,113 to perform reciprocating circumferential movement, and this movement will be transferred by the tube 128 to the vanes 108,108A.

Each tube 128-130 carries a pair of radially extending arms similar to those illustrated in Figure 6, and each radially extending arm has associated therewith a crankshaft. The phase relationship between the crankshafts is substantially as illustrated in Figure 5.

Each crankshaft 117 has secured thereto a gear 121, the gears 121 all being in mesh with a common drive gear 122 which is connected to an input shaft 123.

Accordingly, if the housing 102 is fixed and the drive shaft 123 is rotated the crankshafts 117 will be simultaneously driven in the same rotational direction and edch of the six vanes located within the annular space 107 will perform reciprocating circumferential movement to produce a pumping cycle substantially the same as that described above with reference to the embodiment of Figures 1-3.

In order to effect rotation of the input shaft 23,123 relative to the housing 2,102 it will be necessary to restrain the housing against rotation. If the housing is permitted to rotate - i.e. is substantially not restrained against rotation, the entire pumping device will tend to rotate as a unit with the input shaft 23,123. The torque necessary to restrain the housing against rotation will increase progressively as the outlet pressure of the pump increases. If the outlet of the pumping device is totally closed, the vanes will be unable to reciprocate within the annular space, and the input shaft 23 will be prevented from turning.

It will be appreciated from the above that the pumping device may be used as a variable ratio drive coupling. Referring particularly to Figure 4, an output shaft 134 may be coupled to the housing 102 to rotate about the axis 127 of the input shaft 123 and the annular walls 103,104. If the input shaft 123 is rotated and substantially no restriction is imposed on the outlet of fluid from the chambers, a relatively small output torque will be transmitted to the housing 102 and thus to the output shaft 134. Under these circumstances, the input shaft 123 will rotate and the shaft 134 will either not rotate (if the torque applied to it is insufficient to overcome the resistance of the load connected to it) or will rotate more slowly than the shaft 123. Fluid at a relatively low pressure will be discharged from the pumping device.If the flow of fluid from the pumping device is restricted so that the mean pressure within the pumping chambers is increased, a larger torque will be transmitted through the pumping device, and, if this torque is sufficient to overcome the load applied to the shaft 134, the shaft 134 will rotate. The torque which is transmitted through the pumping device can accordingly be progressively increased from substantially zero to substantially the torque available at the input shaft by progressively throttling the output from the pumping device from a condition in which there is substantially no restriction, to a condition in which substantially no fluid is permitted to leave the pumping chambers.

In a typical use of the pumping device as a variable ratio coupling, the input shaft 123 will be connected to a prime mover and the output shaft 134 will be connected to a load. The load will have some basic rolling resistance, and when there is substantially no restriction on fluid leaving the pumping chambers, the pumping device will in general be incapable of transmitting sufficient torque to overcome the rolling resistance of the load. In order to start the load rotating, the output of the pumping chambers is restricted until the torque transmitted through the coupling is capable of overcoming the rolling resistance of the load. The housing 102 and shaft 134 will then begin to turn slowly.As the load begins to turn, the resistance to rotation will in general decrease, and if the restricted flow of fluid from the pumping chambers is maintained, the shaft 134 will begin to turn more rapidly.

If the restriction on outlet from the pumping chambers is sufficiently large, the housing 102 and shaft 134 will turn progressively faster until the speed of the shaft 134 approaches the speed of the shaft 123. As the relative rotational speeds between the housings 102 and the shaft 123 decreases due to the increase speed of rotation of the housing 102, the speed of rotation of the crankshafts will be reduced and with it the speed of reciprocation of the vanes and the volume of fluid produced by the pump.

In general, an equilibrium situation will be reached in which for a constant speed input, the output shaft will rotate at a constant speed less than the speed of the input and the pumping device will deliver fluid at the pressure determined for the particular torque transmitting need of the coupling.

The above described pumping device may be used simply as a pump by preventing rotation of the housing 102.

In the alternative, it can be used as part of a transmission system, for example a transmission system of a vehicle as described in our co-pending British patent application . If the pumping device is used as part of a vehicle transmission system, the working fluid can advantageously be air, and the pressurized air delivered by the pumping device can be utilized for purposes associated with the vehicle, for example it may be expanded through a nozzle to produce cold air as part of an air conditioning system or as part of a system for improving the charging capacity of the cylinders of the engine.

Claims (8)

1. A pumping device comprising a housing having an inner right circular cylindrical wall; an inner right circular cylindrical wall coaxial with the outer wall to define therebetween an annular space; a plurality of generally sector-shaped vanes mounted in the annular space, each vane including part cylindrical inner and outer walls disposed adjacent the inner and outer walls respectively of the housing whereby a chamber is defined between each pair of vanes; inlet means for supplying fluid to each chamber; outlet means for receiving fluid from each chamber; a respective crankshaft associated with each vane, each crankshaft being rotatably mounted in the housing and being coupled to its associated vane such that continuous rotation of the crankshaft relative to the housing produces circumferential reciprocating movement of the vane relative to the housing; and means for rotating the crankshaft to reciprocate the vanes and thereby cyclical vary the volume of each chamber whereby fluid may be supplied to each chamber via the inlet means when the volume of the chamber is at or close to its maximum and then pressurized as the volume of the chamber is reduced by movement of the vanes.

2. A pumping device according to claim 1 wherein the means for rotating the crank shafts comprises a respective gear secured to each crank shaft, the crank shaft gears being in mesh with a common drive gear which is rotated by an input shaft about the axis of the cylindrical walls to rotate the crank shaft gears and thus the crank shafts.

3. A pumping device according to claim 1 or claim 2 wherein the inner cylindrical wall is defined by the housing and each vane includes a part-cylindrical surface complimentary to the inner cylindrical wall.

4. A pumping device according to claim 3 wherein the crank pin of each crank shaft extends through a radially oriented slot in its associated vane.

5. A pumping device according to claim 1 or claim 2 wherein the crank shafts are located exterior to the annular space, and each vane is mounted on a tube which extends from the vane through an end plate closing the annular space to couple to vane to its associated crank shaft.

6. A pumping device according to claim 5 wherein each tube carries a pair of diametrically opposed vanes and a pair of diametrically opposed radial arms located exterior to the annular space for connecting the tube to a pair of crank shafts.

7. A pumping device according to any preceding claim in which the input drive is a rotary drive delivered by rotary input means rotatable about the axis of the cylindrical walls, wherein the housing is mounted in a manner which permits rotation of the housing, the pumping device being provided with means for controlling the pressure of fluid medium pumped by the pumping device whereby the amount of torque transferred from the rotary drive to the housing is selectively variable.

8. A pumping device substantially as hereinbefore described with reference to the accompanying drawings.