ROTARY POSITIVE-DISPLACEMENT MACHINES

Abstract: A rotary positive-displacement machine which may be operatively connected to an internal combustion engine to act as a turbo-charger or super-charger and including an outer casing (11) within which is located a rotor comprising inner and outer drums (24, 9) rotatable together in the casing about offset axes (23, 19) with angularly spaced flexible vanes (30) between the two opposed drum surfaces serving to define compartments (32) between the drums whose volume changes cyclically as the rotor rotates owing to the offset axes, there being gas inlet and outlet ports (40, 73, 76) and communicating with the compartments and positioned so that gases may flow adequately through the compartments between the inlet and outlet ports which are positioned at mutually remote locations to ensure adequate mixing of gases within and scavenging of the compartments.

Description: ROTARY POSITIVE -DISPLACEMENT MACHINES THIS INVENTION relates to rotary positive-displacement machines. GB-A-1540057 describes a rotary positive-displacement machine having compartments which change volume cyclically as they are rotated. Inlet and outlet of gas to and from the compartments is through axial ports at one end of the machine. If the size of the compartments is increased by increasing the axial extent of the compartment, problems arise in obtaining satisfactory filling and scavenging of the compartments with adjacent axial inlet and outlet ports. According to this invention a rotary positive-displacement machine has a rotor providing compartments whose volume changes cyclically as the rotor rotates, having gas inlet and outlet ports compartments and positioned so that gas outflow is away from gas inflow. In one arrangement there may be angularly spaced radial inlet and outlet ports. In one case gas at elevated pressure may flow through an inlet port and a different gas may flow in through an angularly spaced port which also acts as an outlet port for a mixture of the gases. There may be an axial inlet port. In another arrangement there are two angularly spaced axial inlet ports and an axial outlet port for outflow away from the inlet ports. There may be a further axial outlet port angularly spaced from the two inlet ports for outflow away from the first outlet port. The machine may comprise a casing, the rotor comprising inner and outer drums rotatable together in the casing about offset axes, means defining the compartments between the drums, a peripheral wall of the outer drum providing radial inlet ports to the compartments, with end walls providing axial inlet and outlet ports. The means defining the compartments may comprise generally U-shaped blades secured to peripheral walls of the inner and outer drums. The securement may be by hinges. For example, coiled ends of the blades are embedded in flexible material. There may be means for varying the area of the inlet and/or outlet ports. For example, a closure plate may be slidable peripherally on the casing for reducing the area of a radial outlet port, or slidable rotationally on an end wall for reducing the area of an axial outlet port. In one example the inlet is connected to atmosphere, the outlet is connected to the inlet manifold of an internal combustion engine and the rotor is operatively connected to the engine crankshaft. The invention may be performed in various ways and some specific examples with possible modifications will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:- Fig. 1 is a section through a machine; Fig. 2 is an end view of Fig. 1 with part removed; Fig. 2a is a view taken on arrow A of Fig. 2. Fig. 3 is a part view of a drum periphery; Fig. 4 is similar to Fig. 2 of a modified machine; Fig. 5, 5A and 5B show closure plates; Fig. 6 shows a flexible blade; Fig. 7 shows a modified form of blade. Fig. 8 is a section through another rotary machine; Fig. 9 is a perspective view of the machine with part broken away; Figs. 10, 11 show control plates; Fig. 12 is an axial view of an end plate; Fig. 13 shows a connection device; Figs. 14 to 17 show control devices; Fig. 18 shows a modified vane; and Fig. 19 is a section of a further machine; A rotary positive-displacement fluid device 10 comprises a fixed casing 1 1 having a peripheral axial wall 12 and an end plate 13. A drum 9 is rotatable in the casing 11 and has a peripheral axial wall 14 and end plates 16, 17. A shaft 18 rotatable on axis 19 extends from wall 16 rotatably though plate 13. A cylindrical part 20 extends from wall 17 and is rotatably received in fixed block 21 from which extends an axial rod 22 defining an axis 23. An inner drum 24 is rotatable on the rod 22 about axis 23. The axis 23 is offset from the axis 19, as seen in Fig. 2. The drum 24 has a peripheral axial wall 25 and end walls 26, 27 operatively close to the inner surf aces of walls 16, 17 respectively. Angularly spaced generally U-shaped or hair-pin shaped flexible blades 30 are located in the space 31 between walls 14 and 25 and the ends of the blades are secured at 42, 43 respectively to these walls. As can be seen from Fig. 2, the blades 30 divide the space 31 into angularly adjacent compartments or chambers 32. Pin and slot connections 33 between walls 14 and 27 connect the drums 9 and 24 for rotation together when shaft 18 rotates. If the vanes are strong enough, drive between the drums may be transmitted through the vanes. Because the axes 19 and 23 are offset, as the shaft 18 rotates the chambers 32 change in volume cyclically from minimum to maximum to minimum each revolution and the blades 30 change shape accordingly. In the present embodiment, inlet and outlet of gas, which term includes air, to the chambers 32 is radially rather than axially. Ports are provided in walls 12 and 14. For example, as seen in Fig. 3, the wall 14 may comprise a circumferential series of axial bars 36 with axial spaces 37 between adjacent bars 36 to allow inlet and outlet of gas from the space 31 and chambers 32. The ports in wall 12 can vary depending on the intended use of the machine. For example, if the machine is to be used as a turbine, a circumferential slot 40 is provided in wall 12 for inlet of hot gas at elevated pressure. This mixes with the air, or air and gas mixture, in the successive chambers 32 as they pass the slot 40 and the gas expands to bottom centre (Fig. 1 ) at which each chamber has the maximum volume. This causes the shaft 18 to rotate. An outlet port is formed by circumferential slot 41 and the gas/air mixture is expelled through the slot 41 by centrifugal action and ambient air is blown in through the slot 41. The air can for example be blown in by a fan 39 driven by an electric motor 38. The radial inlet and outlet ports provide improved scavenging of the compartments; as drawn the ports extend the greater part of the axial extent of the compartments. The angular distance between successive connections 42 may be more or less than or equal to the angular extent of the slot 40. Such a turbine can act as a turbocharger or exhaust turbine for an internal combustion engine in which hot exhaust gas from the engine is admitted at port 40 and the shaft 18 is operatively connected to the engine crankshaft for example by a belt round pulleys on the two shafts. Another use of the machine in association with an internal combustion engine, typically a fuel-injected spark-ignition engine, is to locate the machine so that the inlet slot 40 receives atmospheric air at ambient pressure and the outlet slot 41 is connected to deliver the air to the engine inlet manifold, at which the pressure is less than or equal to ambient. Fan 39 is omitted. The pressure difference between ambient and the inlet manifold drives the machine and the shaft 18 is again operatively connected to the engine crankshaft to supply extra energy to the crankshaft and thus to recover some of the energy lost because the engine is producing the reduced pressure at the inlet manifold, so-called throttle loss. Thε area of inlet slot 40 is increased as the throttle is opened in order to increase the air flow to the inlet manifold. Thus a plate 60A on casing 12 can be connected for sliding movement and operatively connected to the accelerator pedal if the engine is on a vehicle so that at full throttle the plate 60a is moved to increase the area of slot 40. In practice, to improve efficiency the volume of the chambers 32 at their minimum may be reduced for example by the use of blocks 50, 51 , Fig. 4 (for each chamber) (only some blocks shown) which are respectively secured to the walls 14, 25 or the walls of the blade 30. In the top centre or minimum position the blades may lie along a significant part of the surfaces of the blocks 50, 51. The blocks 50, 51 are shaped to accommodate the change in shape of the blades because of the offset of the axes 19, 23. In a further example of use, the machine is used both as a turbine and as a compressor. For example, in association with an internal combustion engine as above, at low or idling engine speed (part throttle) the machine is used as a turbine to recover throttle loss, as above, but at higher speeds, e.g. full or largely open throttle, the machine can act as a supercharger. This may enable the engine to act at a lower compression ratio e.g. 5 to 1 than the more normal 10 to 1. The inlet port 40 is connected to ambient air. In this case the angular extent of outlet slot 41 is reduced at high or full throttle. For example, an arcuate plate 60A can be connected for sliding movement on the casing wall 12 and be operatively connected to the accelerator pedal if the engine is in a vehicle so that at full throttle the plate 60A is moved to increase the size of the slot 40 and increase the air flow to the inlet manifold. The blocks 50, 51 have the effect of avoiding compressed air being discharged into the slot 40. In this case the slot 41 is extended as at 41A Fig. 4 but at higher throttle opening the downstream part of the slot 41 is closed off so that compressed air is discharged to the inlet manifold. For example additional arcuate sliding plates 60B, 60C are arranged alongside plate 60A to slide at higher throttle opening to close off part of slot 41. During one revolution the fixing points 42, 43 of blades 30 move circumferentially and radially relative to each other by twice the offset of axes 19, 23 and this may introduce high stresses in the blades 30 unless they are thin but if too thin they may not be able to act both in turbine and compressor mode. In view of this the blades 30 may be hinged at 42, 43. For example, the ends of blades 30 can be coiled (Fig. 6) and embedded in an integral rubber boss 60 which is mounted on a fixed pin 61 secured at its ends in walls 16, 17. The blades 30 may take a different form and be constructed, for example, from generally non-flexible material with hinges or from a spring steel member, such as is shown in Fig. 7 having straight arms 63 (flexible or non-flexible) and a curved flexible portion 62. In a further embodiment, a rotary machine 70 Figs. 8 and 9 has cold air and hot gas inlets at one axial end and an outlet for air/gas mixture at the opposite axial end. This improves scavenging because the incoming air assists in expelling the mixture. The machine 70 has an outer cylindrical casing 71 (not shown in Fig. 8) having opposed end plates 71 A, 71 B and providing an enclosure. The inner drum at one end is supported in a static end plate 72 having an inlet port 73 for hot gas at elevated pressure supplied through conduit 74 to an inlet port in the axial end of the outer casing. Cold (ambient) air is blown in (for example by a fan driven by an electric motor or from the engine crankshaft) through conduit 75 leading to an air inlet port in the outer casing and port 76 in the plate 72. The port 76 can have an angular extent as appropriate, for example between sides 77, 78 of plate 72 (Fig. 10). The vanes 30 are operatively sealed in relation to plate 72. The outer drum 9 has an outlet port 79 for air/gas mixture leading to exhaust conduit 80 on the outer casing. A blanking plate 81 (Fig. 11) is mounted between end faces 16, 26 of the drums and provides an outlet port 82. The angular position of the port 82 can be adjusted to control the outflow of the mixture and the expansion of the gas. The vanes 30 are operatively sealed in relation to plate 81. The plate 81 can be linked to shaft 22 for adjustment. The end face 16 of the outer drum 9 is in the form of a spoked aperture (Fig. 12). Normally, as in the various embodiments, the force to rotate the inner drum is transmitted to the inner drum from the outer drum through the vanes 30. To reduce the stress on the vanes 30, if the outer drum quickly slows, a connection can be provided (Fig. 13) between the inner and outer drums which becomes effective on rapid deceleration. The connection can be a peg, pin or plate device in which pegs 90 on the outer drum engage between pegs 91 on the inner drum but under normal working conditions transmit no drive but move into engagement on sudden slowing of the outer drum. The pegs or pins can be of round or rectangular section. In a modification, the machine of Fig. 9 can be used as a combined exhaust turbine and supercharger. In this case an outlet 100 is provided from the inlet end of the outer casing for flow of air under pressure to the internal combustion engine so that, say, a piston /cylinder sized to produce a compression ratio of 6 to 1 can operate at a compression ratio of 10 to 1. The usual butterfly valve in the air flow would be provided linked, in the case of a vehicle, to the accelerator pedal. Blocks 50, 51 are omitted. Figs 14 to 17 indicate various positions for control rings 108, 109 which control the flow of compressed air for supercharging and air/gas exhaust mixture. The end plate 72 has an annular ring 108 which can be angularly adjusted in response to movement of the accelerator pedal. Fig. 14 shows the position of a gap 110 in the ring 108 for no supercharging. The angular distance between one end 111 of the gap and the nearest end 112 of the inlet port 76 for air blown in by a fan is less than the angular distance between two adjacent points 42. The volume of chambers 32 is a maximum at position 0 and least at position 180. For maximum supercharging, the ring 108 is moved to the position of Fig. 15 in which the gap 110 and air inlet port 76 are coincident as seen axially. The exhaust mixture control ring 109 in circular disc end plate 81A has an annular gap 113. To increase the energy recovered from the hot exhaust gas, it is desirable for the pressure of the gas/air mixture at the exit port to be ambient. As can be seen in Fig. 16, the mixture exit port is just downstream of position 0 (after expansion). At idling or low power the gap 1 13 is upstream of the port. In the angular space between the exit port and the gap 113 pressure operated pressure relief valves 114 are provided to prevent the pressure in the chambers 30 becoming sub-ambient (and thus retarding the drum) before reaching the port 80 by admitting ambient air. Fig. 17 shows the gap 113 coincident with the port 80 at maximum power. In one arrangement for example about a third of the compressed air goes to act as supercharging and two thirds passes to be mixed with the hot exhaust gas. The hot gas inlet can for example be positioned at 210° rather than 180° to avoid the possibility of the mixture remaining above ambient pressure at the outlet and thus not allowing full recovery of the energy in the exhaust. The increase in the volume of the chambers into which the hot gas is supplied assists in this. The angular distance between adjacent pressure relief valves is such that each valve at any one time communicates with a single chamber 31. In this configuration air is blown into the machine by a fan, the flow of air expels the spent mixture of air and exhaust gas and is then trapped and compressed as the machine rotates. Some of the air is released from the machine to feed the engine and the remainder is retained. Exhaust gas from the engine enters the retained air which increases the air temperature and pressure. The mixture is expanded until the incoming fan air expels it and the cycle begins again. This design enables one unit to be used without blocks or fillers 50, 51. If used on its own there would not be any throttle loss recovery. In this case where supercharging is not necessary the excess air would be leaked into the exhaust outlet and engine control would be by a conventional butterfly valve. If there was sufficient throttle loss to be worth recovering then a combination of supercharger and exhaust turbine with an additional throttle loss recovery turbine could be used or a combination of throttle loss recovery and supercharger with additional exhaust turbine could be used. In a modification shown in Fig. 18, the vanes 30 are in two parts 120, 121 hinged by coiling at 122. The thinner part 120 can be disposed to lie on the outer drum surface so that the hinge 122 is not radially in a control region of the space 31 between the inner and outer drums and is radially spaced from the hot gas inlet as seen axially, to reduce wear on the hinge 122. In a further modification Fig. 19 air is blown in axially at 130, and the hot exhaust gas flows in radially at G and the gas/air mixtures flows out radially at H generally similarly to Fig. 9. The radial outflow of mixture improves scavenging, as above. The rotary machines above could be used in association with an engine arranged to charge the battery of a battery-driven vehicle.

Claims: CLAIMS 1. A rotary positive-displacement machine having a rotor providing compartments whose volume changes cyclically as the rotor rotates, and gas inlet and outlet ports communicating with the compartments and positioned so that gas outflow is away from gas inflow. 2. A rotary positive-displacement machine according to Claim 1, wherein the gas inlet and outlet ports are radially or axially opposed. 3. A rotary positive-displacement machine according to Claim 1 or Claim 2, wherein the gas inlet and outlet ports are radially directed and angularly spaced. 4. A rotary positive-displacement machine according to Claim 1 or Claim 2, wherein the gas inlet and outlet ports are axially directed and angularly spaced. 5. A rotary positive-displacement machine according to any preceding claim, wherein the inlet and outlet ports are positioned so that a gas may flow through an inlet port and a different gas may flow through a further, angularly spaced, inlet port the latter serving also as an outlet port for a mixture of the gases. 6. A rotary positive-displacement machine according to Claim 4, including two angularly spaced axially directed inlet ports and at least one axially directed outlet port for outflow away from the inlet ports. 7. A rotary positive-displacement machine according to Claim 6, wherein the axially directed outlet port is angularly spaced from the two inlet ports. 8. A rotary positive-displacement machine according to any preceding claim, comprising a casing, the rotor comprising inner and outer drums rotatable together in the casing about offset axes, means defining the compartments between the drums, and a peripheral wall of the outer drum providing radial inlet ports to the compartments, with end walls providing axial inlet and outlet ports. 9. A rotary positive-displacement machine according to Claim 8, wherein the means comprising the compartments are formed as generally U-shaped flexible blades the ends of which are secured respectively to the inner and outer drums. 10. A rotary positive-displacement machine according to any preceding claim, including means for varying the area of the inlet and/or outlet ports. 11. A rotary positive-displacement machine according to Claim 10, wherein said varying means includes at least one closure plate slidable at least partially to occlude the associated inlet or outlet port. 12. A rotary positive-displacement machine according to Claim 8, and including means connecting the inner and outer drums for simultaneous rotation. 13. A rotary positive-displacement machine according to any preceding claim, wherein the or each inlet port is connected to atmosphere and the outlet is connected to the inlet manifold of an internal combination engine, the rotor being operatively connected to the engine crankshaft. 14. A rotary positive-displacement machine according to Claim 13, including a fan for blowing air into the or each said inlet port. 15. A rotary positive-displacement machine according to Claims 1 1 and 13, wherein the means for varying the area of the inlet port is operatively connected to the throttle for the engine such that the air flow through the inlet port is increased with increasing opening of the throttle. 16. A rotary positive-displacement machine according to any preceding claim, including means within the compartments to reduce their volume coincident with their cyclic minimum volume, said means being shaped to accommodate a change in shape of the compartments as the rotor rotates. 17. A rotary positive-displacement machine according to any preceding claim, having respective cold air and hot gas inlets at one axial end of the machine, and an outlet for air/gas mixture at the opposite axial end thereof. 18. A rotary positive-displacement machine according to Claim 8, having an outer cylindrical casing with axially opposed end plates and providing an enclosure, the inner drum at one end of the machine being supported in the adjacent end plate which has an inlet port for hot gas at elevated pressure and having a further inlet port for cold air, an outlet port being provided in the opposed end plate. 19. A rotary positive-displacement machine according to Claim 9, wherein each U-shaped blade is in two parts hingedly connected respectively to the opposed inner and outer drum surfaces.

Inventors: DRIVER ANN MARGARET, DRIVER RONALD WILLIAM, DRIVER, ANN, MARGARET, DRIVER, RONALD, WILLIAM
Applicants: DRIVER ANN MARGARET, DRIVER RONALD WILLIAM, DRIVER TECHNOLOGY LTD, DRIVER TECHNOLOGY LIMITED, DRIVER, ANN, MARGARET, DRIVER, RONALD, WILLIAM
Application year: 1998
Main classification: F01C1
IPC codes: F01C1, F01C5, F01C20, F01C21, F02B33, F02B37, F02B39, F04C18, F04C23