GB2096704A - Rotary positive-displacement fluid-machines - Google Patents

Abstract

A pump, an I.C. engine, or a motor comprises a casing (11) with an internal peripheral web (10), and a pair of rotors (3, 4) mounted on a shaft (5) such that they have the web therebetween and having mutually- opposed helicoidal cam-surfaces (20, 21), which are angularly separated by 180 DEG . Sliding vanes (13A-G) are located in radial slots formed in the web and are in permanent sealing engagement with each of the cam surfaces. When the machine is in use the vanes reciprocate axially in the slots. Spaces (6, 7) between the vanes, the cam surfaces, the web, and the casing vary in volume as the rotors revolve. Inlet ports (8, 9), and outlet ports (22A-G, 23A-G) communicate sequentially with the inter-vane spaces through grooves (15, 16) in the rotors. <IMAGE>

Description

SPECIFICATION Rotary engines and pumps This invention relates to a rotary pump or motor.

Known rotary pumps and motors of the sliding vane type comprise a stator and a rotor mounted on a shaft. The stator has cam-surfaces which act upon laminated pistons or vanes mounted in slots on the rotor. As the rotor rotates, the laminated pistons are made to slide axially by the camsurfaces. Each chamber of the pump or motor is bounded by the pair of vanes, the shaft, the outer casing, the rotor and the cam surface.

During the operation of such pumps and motors the sliding vanes are heated by friction against the outer case of the pump, for this reason they have a service life which is shorter than it would be without such frictional heating.

In accordance with the present invention there is provided a rotary, positive displacement fluid pump or motor comprising a casing solid with an internal web having a plurality of slots, and a pair of rotors mounted on a shaft and separated by the web, the rotors having helicoidal cam surfaces, angularly separated by 1800 and being on facing surfaces of the rotors, vanes located in the slots and in permanent sealing engagement with the cam surfaces, and which in use reciprocate axially, enclose between themselves, the cam surface, the web and the casing, spaces which are increased and reduced in volume; and a plurality of inlet and outlet ports arranged to communicate with the spaces, the arrangement being such that in use, the volume of each space containing the working fluid is progressively reduced and increased during rotation of the rotors.

By placing the sliding vanes on the stator instead of the rotor the frictional heating generated by the relative motion of the outer edge of the vane and the casing is reduced. Although the inner edge of the vane is now moving relative to the central shaft, the relative speed is much less due to the smaller circumferential distance.

Conveniently there are seven vanes.

By employing seven vanes, a balance is struck between operation without pulsation in torque or delivery, which is improved by increasing the number of vanes, and mechanical simplicity or torque at low angular speeds, which is improved by decreasing the number of blades.

The invention will be further described with reference to the accompanying drawings in which: Figure 1 is a sectional view of a rotary motor according to one form of the invention the section being taken parallel to the rotor shaft; Figure 2 is a cross-section of Figure 1 along the doubly cranked line A-A, looking in the direction of the arrows, and Figure 3 is a schematic representation based upon a development of one chamber of the motor viewed in the radial direction.

As best illustrated in Figures 1 and 2 the motor comprises spaced end-walls 1 and 2, located adjacent to the external faces of the rotors 3 and 4, shaft 5 which has an axial manifold 12 connecting with chambers 6 and 7 via ports 8 and 9, web 10 solid with the cylindrical casing 11 and a set of seven laminated vanes 1 3 A-G mounted to the radial slots 14 A--G.

The internal faces of rotors 3 and 4 are each formed with a cam surface 21,20. Each cam surface being substantially helical being two parts of one turn of a screw thread each of 1 800 angular distance, one right-hand and the other left-hand, joined at one end by the high-land and at the other end by the low-land. The cam-surface 21 of rotor 3 is angularly disposed with respect to the cam surface 20 of the rotor 4 by 1800,so that the high-land on one cam surface lies opposite the low-land on the other, to leave between the rotors 3 and 4 an annular channel of rectangular crosssection which is divided by the web 10 and by the laminated vanes 13 A-G locating in slots 14A-G.

The axial lengths of the laminated vanes are such that they remain in permanent sealing engagement with both cam surfaces during rotation of the rotors 3 and 4 and the shaft 5.

Rotors 3 and 4 are solid with shaft 5 and are fluid-tight with the respective end walls 1 and 2 and the casing 11.

An inlet port 8 is provided for chamber 6 and a similar port 9 is provided for chamber 7. Seven circumferentially disposed exhaust ports are provided in the end walls. Chamber 6, for example, exhausts through ports 22 (A-G) while chamber 7 exhausts through ports 23 (A-G). The ports are so formed as to be connected to the space between any pair of laminated vanes by grooves 1 5 and 16, when that space is at maximum volume. At any time other than that at which maximum volume is attained the exhaust ports 22 and 23 are masked by the rotors 4 and 3. The inlet ports 8 and 9 are not angularly displaced with respect to the grooves 22 and 23 respectively.

Hence they connect the manifold 12 only with spaces between any pair of vanes when those spaces are at maximum volume.

In the embodiment illustrated a "glowplug" ignites the fuel air mixture at maximum compression. A plug socket, for example 17, is provided with a "glowplug" 1 8.

Turning now to Figure 3, the chamber between the laminated vanes 1 3D and 1 3E locating in slots 1 4D and 1 4E is at maximum volume. The exhaust port 23D is connected with this space via groove 1 5 and the manifold 12 is connected to the same space by the inlet port 9.

As the rotor 3 rotates, in the direction shown by the arrow the cam surface 21 moves past the laminated vanes 13 and causes them to retreat axially. The exhaust port 23D is masked by the body of the rotor 3, and the inlet port moves beyond the vane 1 3E locating in slot 14E. The charge is compressed as the space is reduced and is ignited by the "glowplug" 1 8. The cycle continues until the exhaust port 23D is unmasked and the inlet port 9 communicates with the space between the.laminated vanes 1 3D and 13E locating in slots 1 4D and 14E. The spent charge is then exhausted via the groove 1 5 and the exhaust port 23D while a fresh charge enters through the inlet port 9.

Claims (3)

1. A rotary, positive displacement fluid pump or motor comprising a casing solid with an internal web with a plurality of slots, and a pair of rotors mounted on 3 shaft and separated by the web, the rotors having helicoidal cam surfaces, angularly separated by 1 80O and being on facing surfaces of the rotors, vanes located in the slots and in permanent sealing engagement with the cam surfaces, and which in use reciprocate axially, enclose between themselves, the cam surface, the web and the casing spaces which are increased and reduced in volume; and a plurality of inlet and outlet ports arranged to communicate with the spaces, the arrangement being such that in use, the volume of each space containing the working fluid is progressively reduced and increased during rotation of the rotors.

2. A pump or motor as claimed in claim 1, in which there are seven vanes.

3. A rotary, positive displacement fluid pump or motor substantially as described herein with reference to the accompanying drawings.