GB2098278A - Rotary positive displacement fluid - Google Patents

Abstract

In a machine, which may be an engine, a pump or a compressor (as shown) comprising radially inner and outer rotors 10, 12 the rotational axes of the rotors are mutually spaced apart but parallel and vanes (22) are attached e.g. pivotally (as shown), to one of the rotors, the free ends of the vanes making continuous sealing sliding contact with the other rotor (12). The working fluid is inducted and ejected via an inlet port (25) and an outlet port (29) in a fixed hollow cylindrical body (18), which is concentric with the inner rotor. Ports (27) that co-operate with the ports in the fixed body (18) may be provided in the inner rotor. Preferably, the rotors revolve unidirectionally at the same angular velocity. <IMAGE>

Description

SPECIFICATION Rotary mechanism This invention relates to rotary mechanisms such as rotary engines, pumps, compressors and the like.

Pumps and compressors with nested rotating cylinders are known, the cylindrical wall of an inner rotor being located so as to be in substantially sealing line contact with the wall of the cylindrical bore of the outer rotor on at least one sealing line. The inner rotor is normally provided with a recess in which the vane is received. Advantageously the vane may be shaped so that its outer surface forms a continuation of the surface of the rotor which the vane contacts.

The invention provides an improvement in a rotary mechanism comprising first and second rotors having cylindrical bores about the axis of which they are arranged to rotate, the rotational axes of the two rotors being spaced apart but parallel with the second rotor being located within the bore of the first rotor, and a plurality of vanes attached to one of the rotors, the free end of the vanes making continuous sealing sliding contact with the wall face of the other rotor, the improvement comprising the provision of inlet and outlet ports in an elongated hollow cylindrical body concentric with the inner rotor, the inner rotor having communication with the said inlet and outlet, the communication with the inlet corresponding with the chamber of maximum volume and the communication with the outlet corresponding with the chamber of minimum volume.The two rotors are preferably arranged, according to the invention to rotate unidirectionally at the same angular speed. They may for example be connected together through a gearing device. Any rotary mechanism constructed according to the invention thus has the characteristic that the space enclosed between the two rotors is divided effectively into separate chambers bounded by the walls of the two rotors, the vanes and the line of contact between the two rotors. Alternatively with no gearing device, the relative speed of the rotors will automatically assume the condition of minimum friction. As the rotors rotate the volumes of the chambers vary from substantially zero to a maximum depending on physical dimensions of the two rotors, and the difference of their radii.

In a preferred form of the invention the two rotors are arranged to rotate at substantially the same angular speed and in the case of a compressor or pump or the iike the outer rotor also constitutes the casing of the machine. This casing may, according to the present invention, be finned or otherwise formed to present a large surface to the air so that a very efficient cooling system is provided due to its rotation. This solves the heating problems associated with prior art compressors.

A feature of the invention is that the two rotors may be supplemented by further rotors all located inside the other making up, for example, a multistage compressor. Further, the rotors can be provided in a wide variety of cross-sectional shapes. For example, they may be substantially circular, square or polygonal.

An embodiment of the invention is illustrated in the attached drawings in which: Figure 1 is a sectional side view through a compressor; and Figure 2 is a diagrammatic sectional view on line Il-Il in Figure 1.

In Figure 1 only the left-hand mounting block is shown for the sake of clarity, the right hand block, being substantially the same.

The compressor comprises an inner rotor 10 and an outer rotor 12 whose axes are eccentric with respect to each other. The inner rotor 10 is journalled in ball races 14 to rotate about an axis 15, while the outer rotor 12 is journalled in ball races 1 6 to rotate about an axis 17, the ball races 1 6 being off-centre with respect to the ball races 14. A stationary cylindrical body 1 8 is located in the inner rotor 10 to serve as a porting sleeve and a clearance 20 is provided for free rotation of the rotor 10 on the sleeve 1 8.

In Figure 2, the inner rotor 10 have five vanes 22 which divide the space between inner and outer rotors 10, 1 2 into a series of chambers 24A and 24E.

The sleeve 1 8 is formed with a rectangular port 25 which registers with ports 27 formed in the wall of the inner rotor 10 on the portion of the inner rotor cycle corresponding to the expansion of the chambers 24. Air is thus introduced into the chambers as they expand and move clockwise past the bottom dead centre point beyond which the size of the chambers 24 starts reducing. The inlet ports 25 and 27 move out of register a fraction before the tip of the particular vane passes the bottom dead centre point so that the reduction in the size of the chambers 24 leads to a compression of the air therein.

In Figure 1 the sleeve 18 is divided by a plug 28, on the right hand side of which is the inlet port 25 and on the left hand side of which is an outlet port 29.

The outlet port 29 is shown in dotted outline in Figure 2. As each chamber 24 approaches its position of minimum volume and maximum compression, the port 27 associated therewith moves into register with the outlet port 29 expelling the compressed air down the bore of the sleeve 1 8 to a discharge line.

A pipe 30 carries an emulsion of oii in water which enters through a conduit 34 into the space 20 between the cylindrical body 18 and the inner rotor 10 to provide a suitable air seal. The emulsion also travels to other movable parts thus providing adequate lubrication.

Dust seals 36 are provided at either side of the casing 38.

In use, referring to Figure 2 and assuming a clockwise rotation, the inner and outer rotors 10 and 12 revolve around the stationary sleeve 1 8.

In this drawing, chamber 24A has just commenced opening, the expansion thereof drawing air (arrow 31) in through the inlet port 25 and the port 27 associated therewith. Chamber 24B is fully open to the inlet port 25 and still expanding. The trailing vane 22 of chamber 24C is on the bottom dead centre point, the port 27 associated therewith is out of register with the inlet port 25 and further rotation will result in the air in the chamber being compressed as is happening in chamber 24D, the volume of which is greatly reduced. The port 27 associated with the chamber 24D is about to move into register with the outlet port 29 behind the plug 28, while the chamber, 24E, having discharged (arrow 33) the compressed air therein through the outlet port, is on the point of closing, the ports associated therewith moving out of register with the outlet port 29.

Claims (2)

1. In a rotary mechanism comprising first and second rotors having cylindrical bores about the axis of which they are arranged to rotate, the rotational axes of the two rotors being spaced apart but parallel, with the second rotor being located within the bore of the first rotor, and a plurality of vanes attached to one of the rotors, the free ends of the vanes making continuous sealing sliding contact with the wall face of the other rotor, the improvement of which comprises the provision of inlet and outlet ports in an elongated hollow cylindrical body concentric with the inner rotor, the inner rotor having communication with the inlet corresponding with the chamber of maximum volume and the communication with the outlet corresponding with the chamber of minimum volume.

2. A rotary mechanism substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.