A ROTARY MACHINE

Abstract: A rotary machine having a rotor (10) eccentrically mounted in a rotary casing (11) and having circumferentially spaced vanes (14) adapted to pivot inwardly and outwardly whereby the outermost extremity of each vane is constrained to follow closely at the internal wall of the casing (11). Pivoting movement of the vanes is created by a slipper (19) eccentrically connected to the pivotal shaft (17) of each vane (14) and adapted to slide within a groove (20) in a disc (21) freely rotatable upon the same axis as the casing (11).

Description: A ROTARY MACHINE THIS INVENTION concerns rotary machines of the kind having a rotor eccentrically mounted within a casing the rotor having a plurality of movable vanes disposed about its circumference, each vane being connected to means whereby it may swing inwardly and outwardly as the rotor rotates so that the tips of the vanes are constrained to follow closely the internal wall of the casing. The machine operates such that gaseous fluid introduced into the spaces between the vanes is alternately compressed and expanded in different zones of the eccentric rotation. Valves or ports in the wall of the casing of the machine are provided for the supply or recovery of air or gases within the spaces whereby the machine may be used either as a compressor or a turbine, or both. The machine has many uses such as enhancement of the efficiency and economic operation of an internal combustion engine which in certain cases can overcome the problems of throttle loss at low engine speeds, or it may operate as a heat pump. The mechanism used to cause the v anes to swing inwardly and outwardly as the machine rotates , conventionally comprises a crank on the pivotal axis of each vane, the offset pivot of the crank being connected to a spoke rotationally mounted on the axis of the casing. Particularly when such a machine is used as a heat pump or if the required speed is excessive the loads on the rotating connecting rods or spokes increase considerably. To maintain the bearing lo ads withi n acceptab le l imi ts the spokes must be of considerable thickness which, however, excessively increases the weight and the overall length of machine. To overcome this problem there have been proposals to dispense with the spokes and to provide, instead, a device which slides within a groove in a fixed end member. However, this presents further difficulties in the design and running conditions of the bearing surfaces of the sliding member and groove. According to the present invention, there is provided a rotary machine having a rotor eccentrically mounted in a casing, the rotor having a plurality of vanes disposed about its circumference, each vane being connected to means to cause the vane, during rotation of the rotor, to pivot radial ly outwardly such that the outermost extremity of each vane is constrained to follow closely the internal wall of the casing, said means being constrained to follow at least one track in a member rotatable upon the same axis as the casing. The means may be slidably engaged within at least one groove in said casing. Lubrication means may be provided within the groove or grooves. The groove is preferably provided in a disc which is freely rotatably mounted about the centre of the circle described by the vane tips whereby its rotational speed is determined by any frictional drag forces of the sl iding means within the groove or grooves, which frictional force will be proportional to the load times the speed. By allowing the disc to be freely rotatable its rotational speed is established automatically as that which gives the least frictional force to the sliding members. The disc speed will be at or close to the speed of rotation of the rotor. An embodiment of the invention will now be described, by way o f examp le only , w i th ref erence to the accompanying drawings, in which:- Fig. 1 is a schematic end view of a rotary machine of the kind incorporating the invention; Fig. 2 is a schematic perspective view of part of the machine; and Fig. 3 is a cross-sectional view of a modified form thereof. Referring now to Figs. 1 and 2 of the drawings, in a rotary machine of the kind referred to there is provided a rotor 10 adapted to rotate within a cylindrical casing 1 1 the axes of the rotor ( 10a) and the casing ( 1 1 a) being mutually offset. The rotor 10 comprises a pair of axially spaced discs 9 defining a central channel 12 about the reduced circumference 13 of which there is provided a series of pivotal vanes 14 which thus divide the channel 12 into a number of discrete arcuate spaces 15. Such a machine is known, for example, from International Patent Publication No. WO 96/39571. The vanes 14 are pivotally mounted about their innermost ends so that their tips 16 are able to swing inwardly and outwardly in a general radial direction as the rotor rotates such that the tips 16 may follow a circular path equivalent to the inner wall of the casing 1 1 . This can be seen from Fig. 1. Thus, as the rotor 10 is driven in rotation the spaces 15 defined within the channel 12 between the vanes 14 are progressively enlarged and reduced in volume by the offset axes 10a and 1 1 a of the rotor and casing. Therefore, gaseous fluid introduced into these spaces is alternatively compressed and expanded as the machine rotates, this expansion and compression being utilised for various purposes as referred to in the patent publication mentioned above. In accordance with the invention there is provided an improved mechanism connected through one or both discs 9 of the rotor 10 to each vane 14. On its axis of rotation at one or both ends of a shaft 17 is a crank arm 18 from the radially outer end of which there extends in a direction parallel to the shaft 17 a slipper 19 adapted to slide within a groove 20 in an outer disc 21 which is freely rotatably mounted on the axis 1 1 a of rotation of the casing 1 1. The sliding engagement o f the slipper 19 within the groove 20 ensures accurate varying displacement of the associated vane 14 as the machine rotates. Since the disc 21 is freely rotatable minimal bearing friction between the groove and the slipper is achieved. Referring now to Fig. 3 in an improved embodiment the slipper 19 is replaced by a pair of stub axles 22 pivotally mounted within an enlarged slipper 23 which again slides within a groove 20 of the disc 21. Lubrication ports 24 and 25 may be provided if required. By attaching the slipper 23 in tandem, any tendency for bending or twisting movement on the crank arm 18 is avoided or at least substantially reduced. The two bearings ensure that the load placed upon the slipper mechanism is more evenly distributed and reduces any stresses. In the assembly illustrated in Fig. 3, the item containing the lubrication port 25 is, in effect, formed by the radial inner wall of the groove 20. This prevents the slipper, and thus the vane tips, from moving radially inwardly at slow speeds when gaseous fluids within the spaces 15 might otherwise overcome the centrifugal forces tending normally to move the vanes outwardly. The crank arm 18 may be bonded to the vane shaft 17 for ease of assembly. The crank arm 18 may instead carry a clevis, with a roller bearing or the like mounted between the legs of the clevis. The slipper 19, 23 may carry, or be replaced by, a pair of needle roller bearings for smoother running, which could therefore be grease sealed to avoid the need for oil lubrication.

Claims: CLAIMS 1. A rotary machine having a rotor eccentrically mounted in a casing, the rotor having a plurality of vanes disposed about its circumference, each vane being connected to means to cause the vane, during rotation of the rotor, to pivot radially outwardly such that the outermost extremity of each vane is constrained to follow closely the internal wall of the casing, said means being constrained to follow at least one track in a member rotatable upon the same axis as the casing. 2. A rotary machine according to Claim 1 , wherein the said means is slidably engaged within at least one groove in said member. 3. A rotary machine according to Claim 2, wherein said means is slidably engaged within a pair of grooves in said casing. 4. A rotary machine accordi ng to C l aim 2 , including lubrication means provided within the groove or grooves. 5. A rotary machine according to Claim 2, wherein said at least one groove is provided in a disc which is freely rotatably mounted about the centre of the circle described by the vane tips whereby its rotational speed is determined by any friction drag forces of the sliding means within the groove or grooves. 6. A rotary machine according to Claim 5, wherein the rotational speed of the disc is at or close to the speed of rotation of the rotor. 7. A rotary machine according to Claim 2, wherein each vane is pivotally mounted on a shaft, on one or both ends of which is a crank arm, from the radially outer end of which there extends in a direction parallel to the shaft a slipper adapted to slide within the groove or grooves. 8. A rotary machine according to Claim 7, wherein the means of pivoting the of each vane is provided in the form of a pair of stub axles pivotally mounted within a slipper adapted to slide within the or each groove whereby the slipper is attached to the stub axle in tandem to avoid any tendency for bending or twisting of the crank and to ensure that the load placed upon the slipper is evenly distributed to reduce stresses. 9. A rotary machine according to Claim 6, wherein each crank arm is bonded to its associated vane shaft. 10. A rotary machine according to Claim 1 , wherein said means is engaged within at least one groove in said member, by roller bearings or ball bearings.

Inventors: DRIVER RONALD WILLIAM, DRIVER, RONALD, WILLIAM
Applicants: DRIVER RONALD WILLIAM, DRIVER TECHNOLOGY LTD, DRIVER TECHNOLOGY LIMITED, DRIVER, RONALD, WILLIAM
Application year: 1999
Main classification: F01C1
IPC codes: F01C1