GB2133084A - Rotary positive-displacement fluid-machines - Google Patents

Abstract

A machine that can be an I.C. engine, a compressor, a motor, or a pump has a rotor 12 encircled by a stator comprising segments 20 and furnished with sliding vanes 28, which are biased towards the rotor by an annular spring 30. Working-fluid inlet and discharge valves 38, 46 are provided in each stator segment. <IMAGE>

Description

SPECIFICATION Pump or motor This invention concerns pumps or motors of the kind comprising a plurality of radially or chordally-disposed vanes which define a plurality of chambers the volume of which increases and decreases cyclically upon operation of the pump or motor.

To avoid the need for repetition of the reference to "pump or motor", such will be referred to herein as a "mover" simply for convenience. Thus, where used herein the term mover is intended to comprehend within its scope a pump or compressor, or a motor which may be fluid-powered (i.e. caused to operate by pressurized gas or liquid supplied thereto) or may be powered by controlled combustion of fuel within the chambers.

Movers of the kind above referred to usually comprise a rotor from which the vanes project so as to contact and seal with a surrounding housing. Such a construction involves considerable sealing problems at the axial ends of the rotor, along the sides of the vanes, and at the outer ends of the vanes; moreover, the outer ends of the vanes sweep the confronting inner surface of the housing at a very high velocity, so that there is substantial wear at least at these surfaces.

An object of the present invention is to provide a construction of mover as aforesaid wherein the above-discussed problems are minimised, and which lends itself to being constructed in a particularly simple form involving a minimum of movina components.

With this object in view, the present invention provides a mover (as hereinbefore defined) comprising a stator defining a cylindrical space occupied by an eccentric rotor, the cylindrical space being divided into a plurality of chambers, whose volumes change upon rotation of the rotor, by a plurality of vanes slidably located in the stator and resiliently loaded inwardly to engage and seal with the rotor by their inner ends, and port means providing for fluid flow to and from each of the chambers.

The shape of the eccentric rotor is preferably such as to provide a lobe whose profile is partcylindrical, fitting closely to the confronting surface of the stator.

With such a construction, one achieves the advantages, as compared with the prior known proposals as above referred to: (a) that the movement of the vanes is restricted to inward and outward movement relative to the rotor, rotation of the vanes relative to a surrounding housing being eliminated; (b) that sealing of the edges of the vanes can be achieved much more readily than in the case where the vanes are disposed to move relative to and have to the sealed relative to a surrounding casing; (c) the relative speeds of the rubbing surfaces of the vanes, the rotor, and the stator all of which have to be sealed relative to one another, are substantially lower than in the prior known arrangements, so that the sealing is easier and wear is much less than in the known arrangements; and (d) the manner in which the vanes are loaded resiliently inwards towards the rotor can be achieved extremely simply.

In the mover of the invention, the stator may comprise a plurality of stator segments bolted between side bearing plates. The bolts holding these components together may extend right through the two side bearing plates and the segments therebetween.

Resilient inward loading of the vanes may be achieved by a surrounding spring ring which circumscribes the outer ends of the vanes. This ring may locate in notches or recesses in the outer ends of the vanes.

The port means may comprise, for each chamber, an inlet port and an outlet port spaced apart circumferentially of the stator and relative to the rotor, respective axially-disposed passages connecting these ports with respective annular grooves in the side bearing plates.

Each inlet port and outlet port may be provided with a respective unidirectional valve. These valves may comprise respective spring-loaded flaps.

The invention will be described further, by way of example, with reference to the accompanying drawing in which: Fig. 1 is a part-sectional elevation illustrating a practical embodiment of the mover of the invention; and Fig. 2 is a sectional side view, with parts cut away, of the mover of Fig. 1.

As shown in the drawing, the illustrated practical embodiment of the mover of the invention, which is a pump or compressor, comprises a drive shaft 10 carrying an eccentric rotor 12 and journalled by bearings 14 in side bearing plates 16 and 18, of which the plate 16 is an inlet plate and the plate 18 is an outlet plate.

The plates 16 and 18 are bolted one to each side of four stator segments 20 by means of bolts 22 which extend right through the plates 16, 1 8 and the segments 20 the thickness of which corresponds substantially to the axial thickness of the rotor 12, so that the confronting surfaces of the rotor 12 and the plates 16, 18 (which may be ground together) are effectiveiy sealed against gas losses therebetween.

The shapes of the segments 20 are such as to provide inwardly-directed arcuate surfaces 24 which define a substantially circular cylindrical interior spaced within which the rotor 12 is disposed. Over about a quarter of its extent, the outer curved surface of the rotor 1 2 is correspondingly arcuate, as at lobe 26, with there being a minimum of clearance between this lobe portion 26 of the rotor and the confronting surfaces 22 of the segments 20.

The external shapes of the segments 20 is, of course, not critical. At their confronting ends, the adjacent segments 20 define between themselves respective slots which accommodate respective vanes 28 which in the illustrated case are radially disposed, but may, for instance, alternatively be chordally disposed. As will readily be understood, these vanes 28 divide the interior cylinder space of the stator defined by segments 20 and the side bearing plates 1 6, 18 into four compartments which have been indicated by the letters A, B, C and D in Fig. 1 of the drawing. The vanes 28 are of width corresponding to the axial thickness of the rotor 12 and are in sliding engagement by their side edges with the respective side bearing plates 1 6, 1 8.

Additionally, the vanes 28 are loaded resiliently inwards, so that their inner edges contact and seal with the rotor 12. This resilient loading is achieved in a very simply manner by means of a circular spring ring 30 which circumscribes the outer ends of the vanes 28 and is retained in place by locating in notches or recesses 32 in the vanes 28.

A casing 34, U-shaped in radial section, fits to the side bearing plates 16, 18 and serves to enclose the exposed parts of the vanes 28 and the ring 30.

Port means in each stator segment 20 comprises a radial inlet port 36 fitted with a unidirectional inlet valve 38, including a flap 40 loaded by a spring 42, which permits fluid to pass therethrough only into the interior of the rotor, as well as a radial outlet port 44 fitted with a respective unidirectional outlet valve 46, including a flap 48 loaded, by a spring 50, which permits fluid to pass therethrough away outwards from the interior of the rotor.

Respective axially-directed ducts 52, 54 connect with the valves 38, 46 and these register with respective annular grooves 56, 58 in the inner faces of the side bearing plates 1 6, 18 so that all of the ducts 52 of the inlet valves 38 are in communication and are connected with a common inlet tube 60, and all of the ducts 54 of the outlet valves 46 are in communication and are connected with a common outlet tube 62.

O-rings 64 around the shaft 10 serve to seal the latter relative to the side bearing plates 16, 18.

The manner of operation of the pump will readily be understood from the foregoing description. During rotation of the rotor 12, the vanes 28 merely reciprocate radially to remain in contact with the rotor 12 and keep the four compartments A, B, C and D separated from one another.

Considering just the compartment C, this is shown in Fig. 1 at minimum volume and substantially wholly occupied by the lobe 24. As the rotor 12 rotates (e.g. in the direction indicated by the arrow in the figure) the volume of the compartment gradually increases, passing through an intermediate volume corresponding to that shown for compartment D, and eventually achieving maximum volume as shown for compartment A after 1800 of rotation. During this increase in volume, fluid is drawn into the compartment C by way of the inlet tube 60, annular groove 58 and the inlet valve 38, and is prevented from being drawn in from the outlet tube 62 by the outet valve 46.

This maximum volume having been achieved, the next 1 800 of rotation results in the volume of the compartment diminishing back to the minimum as shown in Fig. 1, during which the fluid is forced out through the outlet valve 46, groove 58 and outlet tube 62.

This cycle of operation occurs, of course, for each of the compartments A, B, C and D simultaneously but at 900 offset phases, so that a single rotation of the rotor achieves four successive pumping actions, approaching a continuous pressurising action on the fluid being handled.

As will be understood, there are only a minimum of moving compartments, in the pump, there being only a restricted radial movement of the vanes 28 and rotation of the rotor 12 and its shaft 10. Sealing of these relative to the stator provided by the segments 20 and the side bearing plates 1 6, 18 is a simple matter as compared with the case where vanes are carried by a rotor and seal by their outer ends and side edges with a surrounding casing or cylinder.

Naturally, the invention is not confined to the precise details of the foregoing example and variations may be made thereto. Thus, of course, the number of compartments into which the interior space of the stator is divided can vary from what is shown, from as few as two compartments up to a maximum which will be limited by practical considerations. The forms of the segments, vanes, stator and rotor can, of course, vary from what is shown as also may the manner in which the vanes are loaded radially inwardly to engage with the rotor.

The vanes do not have to be radially disposed relative to the rotational axis of the rotor, but may be offset to a chordal disposition relative thereto.

The invention is not restricted to a pump or compressor as shown but can equally be applied to a motor such as a fluid-driven motor, in which case appropriate driving fluid will be supplied to the compartments under the control of appropriately-actuated control valves which may be provided in the place of or in addition to the inlet and outlet valves 38, 46 shown. Moreover, the device can be appropriately designed, if desired, with ignition means (such as spark plugs) associated with each compartment, to operate as an internal combustion engine.

It will naturally be understood that the term "fluid" as used herein includes both gases and liquids.

Claims (9)

Claims

1. A mover (as hereinbefore defined) comprising a stator defining a cylindrical space occupied by an eccentric rotor, the cylindrical space being divided into a plurality of chambers, whose volumes change upon rotation of the rotor, by a plurality of vanes slidably located in the stator and resiliently loaded inwardly to engage and seal with the rotor by their inner ends and port means providing for fluid flow to and from each of the chambers.

2. A mover as claimed in claim 1 in which the stator comprises a plurality of stator segments bolted between side bearing plates.

3. A mover as claimed in claim 2 wherein bolts holding the side bearing plates and stator segments together extend right through the plates and the segments therebetween.

4. A mover as claimed in clairn 1,2 or 3 wherein resilient inward loading of the vanes is achieved by a surrounding spring which circumscribes the outer ends of the vanes.

5. A mover as claimed in claim 4 wherein the ring locates in notches or recesses in the outer ends of the vanes.

6. A mover as claimed in any preceding claim wherein the port means comprises, for each chamber, an inlet port and an outlet port spaced apart circumferentially of the stator and relative to the rotor, respective axially-disposed passages or ducts connecting these ports with respective annular grooves in the side bearing plates.

7. A mover as claimed in claim 6 wherein common inlet and outlet pipes connect with the respective annular grooves.

8. A mover as claimed in claim 6 or 7 wherein each inlet port and outlet port is provided with a respective unidirectional valve.

9. A mover (as hereinbefore defined) substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.