GB2094890A - Rotary positive-displacement fluid-machines - Google Patents

Abstract

In a machine of the sliding-vane type, which may be an I.C. engine (as shown), the inner peripheral wall of the casing 30 has a non-uniform radius and inlet and exhaust ports 34, 38 are formed in e.g. one or each of the end plates 32 of the casing. A spark plug 36 may be mounted in the said wall. The vanes 12 may be guided by roller bearings 24 lodged in the slots therefor in the rotor 10; and the inner ends of the vanes may have flanges 16 to which the pressure of the working fluid is applied through passages 26 to urge the vanes towards the said wall of the casing. The configuration of the inner peripheral wall of the casing may be modified to form a combustion chamber, Figure 3 (not shown). The machine may be adapted for use as a compressor or a pump. <IMAGE>

Description

SPECIFICATION Improved fluid machine The present invention relates to an improved fluid machine, particularly but not exclusively an internal combustion engine of the rotary sliding vane type.

Sliding vane rotary engines are known in which a rotor carries a plurality of radially-disposed vanes capable of sliding into or out of the rotor, the vane tips contacting the inner surface of a casing surrounding the rotor and defining with the outer surface of the rotor a plurality of chambers whose volume varies on variation of the distance between the casing and the rotor.

Prior rotary engines of this type have suffered from many disadvantages, for example, the wear caused by the vane tips sliding over the casing surface, gas sealing at the vane tips and the sliding friction between the vanes and their mountings in the rotor.

It is an object of the present invention to obviate or mitigate these disadvantages.

According to the present invention there is provided a fluid machine comprising a rotor having a plurality of vanes arranged at its periphery and capable of movement in a substantially radial direction relative to the rotor, a casing surrounding the rotor and having a variable radius, end plates for the casing'and inlet and outlet ports leading to the chamber defined between the rotor and the casing and by the end plates, roller bearings mounted in said rotor being provided for guiding said sliding vanes.

Further according to the present invention there is provided a fluid machine comprising a rotor having a plurality of vanes arranged at its periphery and capable of movement in a substantially radial direction relative to the rotor, a casing surrounding the rotor and having a variable radius, end plates for the casing and inlet and outlet ports leading to the chamber defined between the rotor and the casing and by the end plates, each vane having a flanged base and slots in which the bases of each are mounted having a transverse dimension such that the flanged base is a sliding fit therein, passage means being provided in the rotor to connect the portion of the enlarged slot below the flanged base of the vane with the chamber on the down-stream side of the vane.

Preferably the rotor is provided with six equispaced vanes.

The internal surface of the casing is preferably so shaped that the vanes and the casing define an induction chamber at least one compression chamber, a combustion chamber and an exhaust chamber. Desirably first and second compression chambers are provided.

Preferably in the combustion chamber the spacing between the rotor and the casing is such that the vanes on full extension do not abut the inner surface of the casing.

Preferably the vane tip is inclined upwardly towards its leading edge.

The fluid may be operated as a pump or compressor but preferably is operated as an internal combustion engine in which case a spark plug may be provided in the casing to provide a spark in the combustion chamber. Alternatively when it is operating as an internal combustion engine the compression ratio can be arranged such that it operates on the compression-ignition principle.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Fig. 1 is a diagrammatic and elevation of a rotary engine with one end plate removed; Fig. 2 is a perspective diagrammatic view of a portion of the rotor of the engine of Fig. 1 showing the mounting arrangement for a sliding vane; Fig. 3 is a diagrammatic view of a further engine accoridng to the invention; and Fig. 4 is a cut away perspective view of part of the rotor of the engine shown in Fig. 3.

The rotary engine shown in Figs. 1 and 2 comprises a cylindrical rotor 10 having six sliding vanes 1 2 equispaced about its circumference in slots 14, the slots extending in the radial direction of the rotor.

The arrangement of the sliding vanes 12 in the slots 14 is best illustrated in Fig. 2 and it can be seen that each vane 1 2 is an inverted T-shaped elevation, that is it has a flanged base 1 6 at its inner end. The outer end of the vane has an inclined surface 18, the upper end of the inclined surface being the leading edge of the vane.

The width of the slot 1 4 is enlarged at its inner end 20 to accommodate the flange 16, the clearance between the sides of the flange and the enlarged slot 20 being at a minimum. A further enlargement 22 is provided in the slot intermediate the enlargement 20 and the periphery of the rotor and two roller bearings 24, one on each side of the vane 12, are mounted in this enlargement to guide the roller during its radially inward and outward movement relative to the rotor, with the minimum of friction.

A passage 26 is formed in the rotor leading from a V-shaped groove 28 downstream of the vane to the base of the enlargement 20 such that the flanged base 1 6 of the vane is subjected to the pressure of gas in the engine downstream of the vane. This assists in the inwards and outwards movement of the vane as the positive or negative pressure exerted on its base by the gas will be greater than the positive or negative pressure exerted on its inclined upper surface 18, in view of the greater area of the base.

It will be realised that the maximum extension of the vanes from the rotor can be determined either by abutment of the upper surface of the flanged base 1 6 against the end of the enlargement 20 or, by the enlargement of roller bearings 24.

The rotor is surrounded by a casing 30 and two end plates 32 one of which is removed in Fig. 1.

The radius of the inner surface of the casing 30 varies and commencing from the top position shown in Fig. 1 remains constant over the first sixth of the rotor circumference (in the direction of rotor rotation as shown by arrow A), the distance between the outer periphery of the rotor and the inner surface of the casing over this sixth being substantially equal to the maximum extension of the vanes 12 from the rotor such that the leading end oft le vane tips just touch the inner surface of the casi.ig. This provides an induction chamber and one or both of the end plates 32 are provided with induction ports 34 such that fuel/air mixture can be admitted into the induction chamber.

Over the next sixth of the circumference of the rotor the inner surface of the casing moves progressively towards the rotor and it will be realised that the fuel/air mixture between two adjacent vanes passing over this section will be compressed. The spacing between the rotor and the casing remains constant over the next sixth so that this compression is maintained and towards the end of this next sixth there is a sudden increase in the spacing between the rotor periphery and the outer surface of the casing, this spacing being greater than the maximum extension of the vane from the rotor such that there is a space between the end of the vane and the casing.A spark plug 36 may be provided at this point to initiate combustion of the compressed fuel/air mixture which, on combustion expands in the combustion chamber which extends over the next third of the rotor periphery, the spacing between the rotor and the casing remaining constant in the combustion chamber or reducing.

Over the last sixth of the rotor circumference the spacing between the casing and the rotor circumference gradually decreases to provide an exhaust chamber, one or both end plates in this chamber being provided with exhaust ports 38.

It will be realised that at the beginning of the combustion chamber the static pressure resulting from combustion will be converted to velocity pressure past the ends of the vanes and will give a turbine-like impulse to each vane. As the vane tips in the combustion area are not in contact with the inner surface of the casing there is no frictional loss in the combustion chamber.

Figs. 3 and 4 show a rotary engine similar to that shown in Figs. 1 and 2 except that the casing 100 is of constant radius over more than half of the circumference. The casing 100 is provided with fuel inlet pocket 102 in which there is situated an electrode 103 and a fuel injection nozzle 104, the latter being designed to impart a swirling motion to the fuel as it enters the pocket 102. A guide member 106 is provided to separate the pocket 102 from the working space and aiso to provide a guide surface by which ends of the successive vanes are allowed to emerge smoothly from the rotor. This occurs under the influence either of the compressed gas which has access to the space 108 below each vane by virtue of passages (not shown) similar to the passages 26, or of the gas below the vane having being compressed by movement of the vanes into the rotor.

The guide member 106 is provided with a number of perforations 107 to allow compressed gas from the working space to enter the pocket, and a large aperture 110 is provided to allow for expansion of the ignited fuel/air mixture. An exhaust port 112 is provided almost radially opposite the pocket 102 and an inlet port 114 for air is provided near the exnaust port.

The casing is of constant radius from the pocket 102 in the direction of rotation up to a point a short distance beyond the inlet port. From this point the radius of the casing and thus the size of the working space decreases until the guide 106 is reached. The vanes at their greatest extension do not touch the constant-radius portion of the wall of the casing; a small gap of the order of twenty thousandths of an inch, 7.87 x 10-6 mm is required over this portion.

The vanes are movable radially in the rotor by means of roller bearings.

The engine, it is believed will work as follows. A charge of air under pressure in working space A is forced into the pocket 1 06 and meets a jet of fuel.

The mixture is then ignited by the electrode and the gas expands, partly acting to push the vane in a clockwise direction as shown in the diagram.

The gas rushes through the gap between the end of the vane and the casing causing a lowering of pressure on the forward side of the vane. This lowering of the pressure causes the vane to move forward. The velocity of the gas decreases as it moves towards the next vane ahead and increases as it travels through the gap between the edge of that vane and the casing, again causing that vane to move forward. This process is repeated with all the vanes between the pocket 106 and the exhaust port 112, where the spent gases are exhausted. Further air is drawn at the inlet port 114 and compressed as the gas is propelled towards the guide member 106.

Various modifications can be made without departing from the scope of the invention. For example, in the embodiments described above the compression ratio, i.e. the difference in spacing between the rotor and casing in the induction chamber and that in the compression chamber is 1 :10. This can be increased to 1:18-20 so that compression ignition techniques may be utilised.

In further modifications the general principles of the embodiment described above can be incorporated in a rotary sliding vane pump, compressor, or turbine.

Modifications common in the art of internal combustion engines or fluid machines cna be incorporated, for example, the exhaust gases can be used to pre-heat the inlet gases and/or to drive exhaust turbo-chargers.

Claims (14)

1. A fluid machine comprising a rotor having a plurality of vanes arranged at its periphery and capable of movement in a substantially radial direction relative to the rotor, a casing surrounding the rotor and having a variable radius, end plates for the casing and inlet and outlet ports leading to the chamber defined between the rotor and the casing and by the end plates, roller bearings mounted in said rotor being provided for guiding said sliding vanes.

2. A fluid machine comprising a rotor having a plurality of vanes arranged at its periphery and capable of movement in a substantially radial direction relative to the rotor, a casing surrounding the rotor and having a variable radius, end plates for the casing and inlet and outlet ports leading to the chamber defined between the rotor and the casing and by the end plates, each vane having a flanged base and slots in which the bases of each vane are mounted having a transverse dimension such that the flanged base is a sliding fit therein, passage means being provided in the rotor to connect the portion of the enlarged slot below the flanged base of the vane with the chamber on the down-stream side of the vane.

3. A fluid machine as claimed in claim 1 or claim 2 in which the rotor is mounted with six equispaced vanes.

4. A fluid machine as claimed in any preceding claim in which the internal surface of the casing is preferably so shaped that the vanes and the casing define an induction chamber at least one compression chamber, a combustion chamber and an exhaust chamber.

5. A fluid machine as claimed in claim 4 in which first and second combustion chambers are provided.

6. A fluid machine as claimed in any preceding claim in which, in the combustion chamber the spacing between the rotor and the casing is such that the vanes on full extension do not abut the inner surface of the casing.

7. A fluid machine as claimed in any preceding claim in which the vane tip is inclined upwardly towards its leading edge.

8. A fluid machine as claimed in any preceding claim which is operated as an internal combustion engine and a spark plug is provided in the casing to provide a spark in the combustion chamber.

9. A fluid machine as claimed in any of claims 1-7 which is operated as an internal combustion engine and in which the compression ratio is arranged so that the engine operates on the compression ignition principle.

10. A fluid machine as claimed in claim 8 or claim 9 in which is provided a guide surface cooperable with the vane tips in the region of the combustion chamber to prevent the vane tips emerging from the rotor into the combustion chamber.

11. A fluid machine as claimed in claim 10 in which the said guide surface is provided with apertures connecting the working space between the vanes and the casing in the region of the combustion chamber with the combustion chamber.

12. A fluid machine as claimed in any preceding claim in which each vane has at its base a movement limiting flange housed in a cavity in the rotor and a channel is provided opening at one end into the cavity below the flange and at another end on the rotor surface on a trailing side of the vane.

13. A fluid machine substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings.

14. A fluid machine substantially as hereinbefore described with reference to Figs. 3 and 4 of the accompanying drawings.