WO2005026500A1

WO2005026500A1 - Rotary and pivoting vane pump

Info

Publication number: WO2005026500A1
Application number: PCT/IB2004/003008
Authority: WO
Inventors: Andries Petrus De Klerk Coetzee
Original assignee: Coetzee Andries Petrus De Kler
Priority date: 2003-09-16
Filing date: 2004-09-16
Publication date: 2005-03-24
Also published as: ZA200601649B

Abstract

The invention relates to a pump (10). The pump includes a stator (12) and a rotor assembly (30), defining between them an annular fluid space (14) extending circumferentially about a central axis (16), about which axis the rotor assembly is rotatable. The stator has a fluid inlet (20) and a fluid outlet (22), respectively leading into and out of the fluid space and dividing the fluid space into a fluid flow path (24) and an obstruction zone (26). An obstruction (28) providing a gap (29) is located in the obstruction zone. A plurality of vanes (36) and a plurality of plugs (35) are mounted, in alternating fashion, on the rotor assembly, each vane and each plug being located in the fluid flow space. Each vane is pivotable, by means of a pivot arrangement, between an operative displacement condition in which it displaces fluid along the flow path, and an inoperative condition in which it passes through the gap. Each plug is fixedly mounted in an attitude which permits passing thereof through the gap, substantially to close the gap during passage of successive vanes through the gap, so that fluid displaced along the flow path leaves the fluid space via the outlet.

Description

ROTARY AND PIVOTING VANE PUMP

This invention relates to a pump. It relates also to a pump assembly.

In accordance with one aspect of the invention there is provided a

pump which includes: a stator; a rotor assembly in sealing abutment with the stator and comprising a

rotor rotatable about a central axis, the stator and the rotor assembly defining

between them an annular fluid space extending circumferentially about the

central axis, the stator having a fluid inlet leading into the fluid space, and a fluid outlet leading out of the fluid space, the inlet and outlet being spaced

circumferentially from each other along the fluid space, and dividing the fluid

space along its length into a major portion and a minor portion, the major portion

constituting a fluid flow path for fluid flowing from the inlet towards the outlet, and

the minor portion constituting an obstruction zone in which fluid flow between the

inlet and the outlet is obstructed; at least one vane mounted on the rotor at a position spaced radially

outwardly from the central axis and located in the flu id space for displacing fluid

along the major portion of the fluid space from the inlet^" along the fluid flow path

to the outlet in response to rotation of the rotor in a forward direction, each vane having opposed major faces, one of which is a front face facing in the forward direction, and each vane being pivotally mounted on the rotor for pivoting between an operative displacement condition in which its front face is transverse to the direction in which fluid is, in use, displaced and in which edges of the vane are spaced with a sealing clearance from the periphery of the fluid space to permit displacement along the fluid flow path of fluid by the vane as the vane moves along the fluid space in the forward direction, and an inoperative condition in which the front face of the vane is substantially parallel to the direction in which fluid is, in use, displaced; an obstruction located in the obstruction zone for obstructing fluid flow along the minor portion of the fluid space from the inlet to the outlet, the obstruction defining a gap arranged to permit passage of each vane along the obstruction zone when the vane is in its inoperative condition, while obstructing said fluid flow along the obstruction zone, so that fluid displaced along the fluid flow path from the inlet to the outlet in response to forward rotation of the rotor assembly is caused to leave the fluid space via the outlet; at least one plug fixedly mounted on the rotor assembly at a position spaced radially outwardly from the central axis and located in the fluid space, each plug having opposed major faces, and being mounted on the rotor assembly such that its major faces are substantially parallel to the direction in which fluid is, in use, displaced, each plug being shaped and located on the rotor to permit passage of the plug through the gap and to permit pivoting of each vane between its operative displacement and its inoperative conditions, each plug acting substantially to close the gap during intervals between successive occupations of the gap by a said vane; and a pivot arrangement, at least part of which is connected to each vane, for pivoting each vane between its operative displacement condition and its inoperative condition, the pivot arrangement being arranged, in response to forward rotation of the rotor, to pivot each vane, as it approaches the obstruction, into its inoperative condition in which inoperative condition it remains when in the obstruction zone and passing through the gap in the obstruction, and to pivot the vane into its operative displacement condition as it leaves the obstruction, in which operative condition the vane remains as it moves along the fluid flow path, to displace fluid along the fluid flow path.

The pump may include a plurality of said vanes and a l ike plurality of said plugs mounted on the rotor in a circumferentially extending series in the fluid space, the plugs alternating with the vanes.

Each vane may be pivotable, independently of any other said vane, successively into its operative displacement condition and into its inoperative condition about its pivot axis.

There may be at least two of the vanes and two of the plugs, the vanes being equally circumferentially spaced in series and the vanes also being equally circumferentially spaced in series, the plugs alternating with the vanes. The spacing of the vanes and the plugs relative to each other may be such that opposing edges of successive vanes and plugs are circumferentially spaced with no more than a working clearance therebetween when the vanes are in their inoperative conditions.

The fluid space may be of rectangular cross-section, its periphery being made up of a pair of curved radially inner and outer walls spaced radially from each other, and a pair of flat annular side walls axially spaced from each other and normal to the central axis, the obstruction being constituted by two spaced opposed blocks fixedly located in the fluid space between the inlet and the outlet to define the obstruction zone, the gap being defined between said blocks and extending circumferentially relative to said central axis and transversely across the fluid space between opposed walls of the fluid space.

The blocks may be radially spaced from each other, respectively being a radially inner block having a radially outwardly facing convex surface arcuate about the central axis and a radially outer block having a radially inwardly facing concave surface arcuate about the central axis and opposed to said convex surface, the gap being defined between said convex surface and said concave surface and extending axially relative to the central axis, the pivot axis of each vane being parallel to the central axis, the major faces of each plug being substantially circumferential relative to the central axis, each vane and each plug being arcuately shaped and being flattened, such that each vane has two oppositely outwardly facing major faces, namely its front face which is concave and a major rear face which is convex, and each plug has said two major faces, namely a radially inner face which is concave and a radially outer face which is convex, the inoperative condition of each vane being such that its front and rear faces are substantially circumferential relative to the central axis, each vane being of rectangular outline when viewed face-on, each vane having dimensions in face-on outline corresponding to the rectangular cross-sectional dimensions of the fluid space, and each plug extending axially across the entire fluid space between the side walls of the fluid space, said major faces of each vane and each plug respectively being complementarily curved with regard to the respective opposed faces of the blocks defining the gap, each vane and each plug having a thickness corresponding to the radial spacing between the opposed curved faces of said opposed blocks such that each vane, when in its inoperative condition passing along the obstruction zone, and each plug when passing along the obstruction zone, slides with a sealing clearance along the gap upon forward rotation of the rotor, substantially to close the gap.

The stator may provide an axially directed flat face located in a plane normal to the central axis, with the fluid space being defined by a groove in said flat face, the rotor comprising a vane-mounting disk mounted to rotate about the central axis and on which disk each vane and plug are mounted, the mounting disk being provided with a flat face normal to the central axis, from which flat face the vanes and the plugs project, the respective flat faces of the stator and the mounting disk facing each other across the annular fluid space, such .that the stator defines the radially- inner and outer walls and one side wall of the fluid space, and the flat face of the mounting disk defines the other side wall of the fluid space.

Each vane may have a stub shaft fast therewith and providing the pivot axis of the vane, the stub shaft projecting from an edge of the vane, each stub shaft being pivotally supported by, and projecting through, the mounting disk.

The pivot axes of the vanes may be spaced along a circumferential ring located radially midway between the inner and outer walls of the fluid space, the plugs being radially spaced midway between the inner and outer walls of the fluid space.

The rotor assembly may include a drive shaft rotatable about an axis co-axial with the central axis, for connection to a rotational drive for rotatingly driving the rotor in the forward direction, the mounting disk being fast with and projecting radially outwardly from the drive shaft.

The pump may include a stationary drive shaft casing provided on the side of the mounting disk remote from the stator, the drive shaft casing rotatably supporting the drive shaft and having a central passage co-axial with the central axis, along which passage the drive shaft passes.

The pivot arrangement may comprise a cam path/cam follower arrangement. The pivot arrangement may include a cam follower for each vane and fast with the stub shaft of the vane, the cam follower of each vane being located on the opposite side of the mounting disk from the fluid space, the cam path being defined by a groove extending eccentrically about the central axis and provided by a cam plate mounted on the drive shaft casing, each cam follower projecting into the groove and operatively engaging cam surfaces provided by the cam path, so that each vane is rotated about its pivot axes upon forward rotation of the rotor assembly, the eccentricity of the cam path about the rotor axis being selected such that each vane is pivoted to be in its inoperative condition when in the obstruction zone and in its operative displacement condition as it passes along the major portion of the fluid space.

Each cam follower may be cylindrical, being rotatable about an axis parallel to the central axis and radially spaced from the axis of its associated stub shaft.

The pump may include seals operative between the stator and the mounting disk for resisting leakage in a radial direction of fluid from the fluid space between the stator and the mounting disk. The seals may comprise annular labyrinth-type arrangements located radially inwardly and radially outwardly of the fluid space and operative between the stator and the mounting disk, each of the labyrinth-type arrangements being operative between the mounting disk and said flat face of the stator.

The rotor assembly may include a rotor assembly housing fast with the mounting disk and extending away from the stator, the rotor assembly housing sealingly engaging the drive shaft casing at an end of the drive shaft casing remote from the mounting disk, so that the rotor assembly housing together with the mounting disk forms an annular cavity for receiving lubricant and within which part of the drive shaft casing and the cam plate are housed.

The rotor assembly may include an arcuate side wall extending concentrically about the rotor axis, one end of the side wall being fast with the radially outer peripheral edge of the mounting disk and the other end of the side wall being axially spaced, in a direction away from the stator, from said one end, the rotor assembly also including an annular end plate substantially parallel to the mounting disk and extending radially inwardly from said other end of the side wall, a radially inner edge of the end plate being provided with an annular seat on which is seated an annular seal which sealingly engages the drive shaft casing to seal the cavity. The stator may be provided with a central passage co-axial with the central axis and in which the drive shaft or an axial extension of the drive shaft is rotatably journalled.

The stator may include a cover releasably secured to the side of the stator opposite the mou nting disk, for sealingly covering the end of the central passage remote from the mounting disk.

In accordance with another aspect of the invention there is provided a pump assembly which includes a pump as hereinbefore described having a rotational drive operatively connected to the rotor assembly for rotatingly driving the pump.

The invention is now described by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings: Figure 1 shows an end elevation of a pump in accordance with the invention; Figure 2 shows an axial section of the pump taken at II - II in Figure 1 ; Figure 3 shows a view of the rotor assembly of the pump more or less corresponding to the view of the pump shown in Figure 1 , with the stator forming part of the pump removed; Figure 4 shows a three-dimensional view of the stator forming part of the pump illustrating its axially inner end; Figure 5 shows a three-dimensional view of a vane forming part of the pump and mounted on a base from which a stem projects; and Figure 6 shows, fragmentarily, an end view of a cam plate forming part of the pump, the cam plate being provided with a guide path.

With reference to the drawings, a pump in accordance with the invention is generally indicated by reference numeral 10. The pump 10 includes a circular-cylindrical stator 12 defining an annular fluid space 14 extending circumferentially about a central axis 16. The stator 12 is fixedly secured to a mounting arrangement such as a base or pedestal (not shown) on which the pump 10 is mounted in an operative position, so that the stator 12 is stationary, i.e. it does not rotate.

The stator 12 has an elongated arcuately-shaped fluid inlet in the form of a window 20 (Figure 1 ) leading into the annular fluid space 14, and a similar elongated arcuately-shaped fluid outlet 22 (Figure 1 ) leading out of the annular fluid space 14. Both the fluid inlet 20 and the fluid outlet 22 are provided in a more or less flat operatively outer wall 21 of the stator 12, the inlet and outlet 20, 22 being curved about the central axis 16, which central axis 16 is normal to the wall 21. The fluid outlet 22 is spaced circumferentially along the annular fluid space 14 from the fluid inlet 20. The fluid inlet 20 and the fluid outlet 22 divide the annular fluid space 14 along its length in to a major portion constituting a fluid flow path 24 for fluid flowing from the fluid inlet 20 towards the fluid outlet 22, and a minor portion constituting an obstruction zone 26 in which fluid flow from the fluid inlet 20 to the fluid outlet 22 or vice versa is obstructed as hereinafter described.

The pump 10 also includes a rotor assembly generally indicated by reference numeral 30 including a drive shaft 32 co-axial with and mounted on the pump base or pedestal for rotation about the central axis 16. The rotor assembly 30 also includes a rotor in the form of an annular vane-mounting disk 34 fast with the drive shaft 32 and protruding radially outwardly therefrom. A plurality of vanes 36 (see also Figure 5) are mounted on the vane-mounting disk 34. Each vane 36 is mounted on the mounting disk 34 at a position spaced radially outwardly from the central axis 16, such that the vane 36 is located in the fluid space 14.

Furthermore, a plurality of plugs 35 are fixedly mounted on the mounting disk 34, the plugs 35 also being spaced from the central axis 16, and located on the mounting disk 34 such that they too are located in the fluid space 14. The vanes 36 and the plugs 35 are equally circumferentially spaced in series from each other along the fluid space 14. The plugs 35 alternate with the vanes 36, such that a plug 35 is located between each pair of adjacent vanes 36. The vanes 36 project in an axial direction from one side 37 of the mounting disk 34 and, as mentioned above, are located in the annular fluid space 14 for displacing fluid from the fluid inlet 20 along the fluid flow path 24 to the fluid outlet 22 in response to rotation of the drive shaft in a forward direction indicated by arrow 33. Likewise, the plugs 35 project in an axial direction from said one side 37 of the mounting disk 34.

The fluid space 14 has a rectangular cross-section defined by flat radially inner and outer walls 14.1 , 14.3 spaced radially from each other, and a pair of annular flat side walls 14.2, 14.4 axially spaced from each other and normal to the central axis 16. The walls 14.1 , 14.2, 14.3 are provided by walls of an annular recess or groove, also designated 14, provided in the axially inner side of the stator 12. Said recess or groove 14 thus has a rectangular cross- section. The side wall 14.4, on the other hand, is provided by the mounting disk 34, so that the stator 12 and the mounting disk 34 face each other across the fluid space14.

An obstruction (Figure 2), generally indicated by reference numeral 28 and described in more detail hereinafter, is located in the obstruction zone 26 for obstructing fluid flow along the obstruction zone 26 from the fluid inlet 20 to the fluid outlet 22 or vice versa. The obstruction 28 provides a gap 29 permitting free passage of the vanes 36 and of the plugs 35 past the obstruction zone 26 while obstructing fluid flow past the obstruction zone 26, so that fluid displaced by forward rotation of the rotor 30 in the direction of arrow 33 along the fluid flow path 24 away from the fluid inlet 20 leaves the fluid space 14 via the fluid outlet 22.

Each of the vanes 36 has a front major face 38, and a rear major face 40 opposite its front face 38. Each of the vanes 36 is somewhat arcuately- shaped, with its front face 38 being concave and its rear face 40 being convex and parallel to the front face 38, the curvature of the faces 38, 40 of each vane 36 being about a common axis parallel to the axis 16. The front- and rear faces 38, 40 of each vane 36 have more or less rectangular outlines complementary to that of the cross-section of the fluid space 14, and are of a size closely corresponding to that of the cross-section of the fluid space 14.

Each of the plugs 35, in turn, has two opposed parallel major faces, namely a convex radially outer face 45 and a concave radially inner face 47, the curvature of the faces 45, 47 of each plug 35 being about a common axis provided by the central axis 16. The major faces 45, 47 of each plug 35 are thus substantially circumferential relative to the central axis 16.

Each vane 36 is pivotally mounted on the mounting disk 34 about a pivot axis parallel to the central axis 16, for pivoting between an operative displacement condition (see e.g. vane numbered 36.1 in Figure 3) and an inoperative condition (see e.g. vane numbered 36.2 in Figure 3).

When a vane 36 is in its operative displacement condition, the vane 36 has its front face 38 transverse to the direction in which fluid is displaced along the fluid flow path 24, so that its peripheral edges are sufficiently closely spaced from the walls 14.1 , 14.2, 14.3, to provide a sealing clearance therebetween, so that acceptably little leakage between edges of the vanes 36 and the walls 14.1 , 14.2 and 14.3 of the fluid space 14 occurs upon displacement of fluid by the vane 36 along the fluid flow path 24 in the direction of arrow 33.

When in its inoperative condition, each vane 36 has its front face 38 facing radially inwardly and extending more or less circumferential to the central axis 16 for reasons which will become apparent hereinafter.

Each plug 35 extends axially across the entire fluid space 14 between the side walls 14.2 and 14.4 thereof, a free edge of each plug 35 being sufficiently closely spaced from the wall 14.2, so that when each plug 35 is located in the gap 29, it occupies the entire volume of the gap. Each plug 35 is thus in a similar attitude to the vane 36.1 in its inoperative condition. Thus, in practice, each plug 35 can be regarded as a vane 36 which is fixedly, i.e. non- pivotally, mounted on the mounting disk 34, in its inoperative condition.

In this example, the pivot axes of the vanes 36 are spaced in a circumferential ring located midway between the radially inner wall 14.1 and the radially outer wall 14.3 of the fluid space 14. The plugs 35 are also located radially midway between the radially outer wall 14.1 and the radially inner wall 14.3 of the fluid space 14.

The respective parts of the pump 10 are secured together by means of bolts and screws. So as not to clutter up the drawings, however, the respective bolts and screws are not numbered and, accordingly, for most part of this description, the manner in which the respective components of the pump 10 are secured together is not described.

The obstruction 28 is constituted by two spaced opposing blocks 42, 44 (Figure 4) fixedly located in and defining the obstruction zone 26 and secured to the stator 12. The block 42 has a radially outwardly facing convex surface 46 arcuate about the central axis 16, and the other block 44 has a radially inwardly facing concave surface 48 arcuate about the central axis 16 and opposing the convex surface 46 of the block 42. The gap 29 is thus defined between the surfaces 46, 48 such that it extends both circumferentially relative to the central axis 16 and axially relative to the central axis 16 between the end walls 14.2, 14.4 of the fluid space 14. In this example, the gap 29 is spaced radially midway between the radially inner wall 14.1 and the radially outer wall 14.3 of the fluid space 14. The surfaces 46, 48 are respectively complementarity curved with regard to the respective faces 38, 40 of the vanes 36, and with regard to the respective faces 45, 47 of the plugs 35. Also, the radial spacing between the faces 46, 48 is substantially equal to the thickness of each of the vanes 36 and each of the plugs 35, so that each vane 36 when in its inoperative condition and passing along the obstruction zone 26, and each plug 35 passing along the obstruction zone 26, passes freely with a sealing sliding clearance through the gap 29 upon rotation of the drive shaft 32, substantially to close the gap 29.

The vanes 36 and the plugs 35 are spaced circumferentially about the axis 16 relative to each other such that opposed edges of successive vanes 36 and plugs 35, when the vanes 36 are in their inoperative condition, are closely spaced, typically with only a working clearance between them, so that little or no fluid is located between the peripheral edges of successive vanes 36 and plugs 35 when the vanes 36 are in their inoperative conditions and passing along the gap 29. During intervals between the passage of adjacent vanes 36 along the gap 29, the plug 35 located between the adjacent vanes 36 will thus be passing along the gap 29, substantially to keep the gap 29 closed.

The gap 29 has a circumferential length more or less equal to the width of one of the vanes 36 or one of the plugs 35 in the direction circumferential to axis 16, and, as will be apparent from the aforementioned, the spacing between the vanes 36 and the plugs 35 is such that there is always part of at least one vane 36 or one plug 35 in the gap 29, substantially to close the gap 29. Because the gap 29 is always substantially closed, substantially all the fluid displaced along the fluid flow path 24 away from the fluid inlet 20 thus leaves the fluid space 14 via the fluid outlet 22.

The pump 10 further includes a drive shaft casing 50 (Figure 2) provided with a circular central passage 52 along which the drive shaft 32 passes and in which the drive shaft 32 is rotatably supported by means of ball bearings 54, 56 spaced apart along the drive shaft 32. The end of the drive shaft casing 50 remote from the stator 12 is, like the stator 12, secured to the base or pedestal on which the pump 10 is mounted in use, so that it too is stationary.

As can be seen in Figure 5, each vane 36 is mounted on a circular disk-like base 39 located in a plane normal to the vane faces 38, 40, an elongated circular cylindrical stem 41 projecting co-axially from that side of the base 39 opposite the vane 36. The base 39 of each vane is received in a complimentarily shaped circular recess 43 in the mounting disk 34 (Figure 2).

The stem 41 of each vane 36 passes along a passage 73 through the mounting disk 34 and is rotatably supported by means of two axially spaced ball bearings 74, 76 in the passage 73. The bearings 74, 76 are spaced apart along the length of each stem 41. Although not shown in the drawings, each plug 35, typically, includes a stem projecting from an edge thereof, parallel to the axis 16, which stem is received through an opening in the mounting plate 34, to project through the mounting plate 34, and by means of which stem the plug is secured to the mounting plate 34. Typically, the free end portion of each stem will be screw- threaded, a nut being screw-threadingly received on each stem, to secure each plug 35 to the mounting plate 34. To resist or prevent pivotal movement of each plug 35, each plug can be provided with a base, similar to the base 39 of each vane 36, but which base is of non-circular outline when viewed face-on, said base of each plug 35 being received in a complementarily shaped recess provided in the mounting plate 34.

The pump 10 yet further includes a pivoting arrangement (Figures 2 and 6) constituted, on the one hand, by a plurality of guide members or cam followers 60 respectively fast with their stems 41 and, on the other hand, by two cam surfaces 62 defined by radially opposed walls of a guide path 64 provided in an annular cam plate 66 in the form of a flange fast with and protruding radially outwardly from the drive shaft casing 50. The cam followers 60 are not shown in Figure 5. The cam plate 66 is parallel to the mounting disk 34 and is located on that side of the mounting disk 34 remote from the stator 12.

In this example, the guide path 64 is defined between opposed radially- inwardly and outwardly facing edges or faces 62 of a radially outer ring 68 and a radially inner ring 70 respectively fast with and forming extensions of the cam plate 66. The guide members or cam followers 60, which are located in the guide path 64, are fast with spacers 72 connected respectively to ends of the stems 41. The guide members or cam followers 60 are rotatably fast with said spacers 72 to rotate about axes parallel to the central axis 16 and spaced radially from the pivot axes of the vanes 36.

As can be seen in Figure 6, the guide path 64 extends eccentrically about the central axis 16. The guide path 64 is provided with an eccentricity such that, upon rotation in the direction of arrow 33 of the rotor assembly 30, each vane 36 is pivoted towards its inoperative condition when approaching the gap 29, to be in its inoperative condition as it passes through the gap 29, and is pivoted towards its operative displacement condition as it leaves the gap 29 to remain in its operative displacement condition as it moves along most of the length of the fluid flow path 24, to displace fluid along the fluid flow path 24.

The stator 12 is provided with an axially directed operatively inner face 80 opposite its outer face 21 in which the annular recess or groove defining the walls 14.1 , 14.2, 14.3 is provided. The inner face 80 is flat and is located in a plane normal to the central axis 16. The stator 12 and the mounting disk 34 are mounted respectively on the base or pedestal such that their respective faces 37, 80 face and abut each other to define the annular fluid space 14, with the face 37 defining the part of the side wall 14.4 of the fluid space 14 which is unoccupied by the bases 39 and their recesses 43. The pump 10 yet further includes two annular labyrinth-type seals, known in the trade as labyrinths, indicated respectively by reference numerals 84, 86 (Figures 2 and 4), fast with the face 80 of the stator 12 and located respectively radially inwardly and radially outwardly of the annular fluid space 14. The annular labyrinth-type seals 84, 86 are operative between the faces 37, 80 for resisting radial leakage of fluid from the fluid space 14 between the stator 12 and the mounting disk 34. The faces 37, 80 are axially spaced relative to each other such that there is sufficient axial clearance between the seals 84, 86 and the face 37 to permit relative rotational movement without contact between the seals 84, 86 and the face 37, the clearance simultaneously being sufficiently small to resist radial leakage between the respective members 84, 86 and the face 37.

The pump 10 further includes annular seals 88 surrounding the stems 41 of the vanes 36 and located in the openings 73 for resisting axial leakage of fluid from the fluid space 14 between the mounting disk 34 and the stems 41.

The rotor assembly 30 also includes a rotor assembly housing constituted by a circular cylindrical arcuate side wall 90 (Figure 2) fast with the radially outer periphery of the mounting disk 34 and extending away from the stator 12, and an annular end wall 92 parallel to the mounting disk 34 and fast with the end of the side wall 90 remote from the mounting disk 34. The end wall 92 extends radially inwardly from said end of the circular cylindrical side wall 90 towards the drive shaft casing 50, and has a circular central opening 93 through which the drive shaft casing 50 passes with clearance. Upon rotation of the drive shaft 32, the rotor assembly housing rotates together with the mounting disk 34.

The inner periphery of the end wall 92 which defines the circular central opening 93 is provided with an annular seat 97 for seating an annular seal (not shown) for resisting axial leakage from the annular cavity or compartment 94 defined by the end wall 92, the mounting disk 34, the side wall 90 and the drive shaft casing 50. In use, lubricant is received in the cavity 94 for lubricating moving parts of the pump 10 located in the cavity 94. Although not shown in the drawings, the drive shaft casing 50 includes a radially extending passage leading radially inwardly from the cavity 94 into an annular space 95 defined between the drive shaft 32 and the drive shaft casing 50 to enable lubricant to flow from the cavity 94 into the cavity 95 for lubricating the bearings 54, 56.

As can be seen in Figure 2, the drive shaft 32 is a composite shaft constituted by a major portion 32.1 rotatably jou mailed in the drive shaft casing

50, and a minor portion 32.2 rotatably supported by means of axially spaced ball bearings 96, 98 located in a circular central passage 100 provided in the stator

12. The major portion 32.1 of the drive shaft 32 is provided with an axially extending spigot formation 32.3 which is received in a complementarily shaped axial socket formation 32.4 provided in the minor portion 32.2. The minor portion 32.2 of the drive shaft 32 is thus in the shape of a cap receivable over the spigot formation 32.3 of the major portion 32.1.

The major portion 32.1 and the minor portion 32.2 of the drive shaft 32, respectively include annular, radially outwardly protruding axially spaced flanges 102, 104 which oppose each other when the portions 32.1 , 32.2 are assembled together. When the two portions 32.1 , 32.2 of the drive shaft 32 are assembled together, the flanges 102, 104 define between them a circumferentially extending recess 105 in which a radially inwardly protruding circumferential rib or ridge 106 of the mounting disk 34 is received. The radially inwardly protruding ridge 106 of the mounting disk 34 is thus sandwiched between the respective flanges 102, 104, and the mounting disk 34 is secured to the drive shaft 32 by means of screws 107 spaced circumferentially about the drive shaft 32 and extending through the flanges 102, 104 and into the mounting disk 34.

The major portion 32.1 and the minor portion 32.2 of the drive shaft 32 are thus secured together via the mounting disk 34, to which disk 34 they are secured by the screws 107. Opposed abutting faces of the major portion 32.1 and the minor portion 32.2 of the drive shaft 32 include a plurality of circumferentially spaced aligned keyholes respectively indicated by reference numerals 108, 110 in which keys 112 are received when the respective portions 32.1 , 32.2 are secured together, to increase the torque-withstanding capabilities of the composite drive shaft 32.

It is to be appreciated that the particular construction of the drive shaft 32 is not essential for functioning of the pump 10, but that the drive shaft 32 merely has this particular construction to reinforce securement of the mounting disk 34 to the drive shaft 32. Thus, in other examples (not shown), the drive shaft 32 can be of unitary construction and will then not include the flanges 104, 106.

The central passage 100 is closed by means of a circular disk-like cover 114 releasably attached, by means of screws or bolts, to the outer face 21 of the stator 12.

In use, the drive shaft 32 is connected to a rotary power input (not shown) for rotating the rotor assembly 30 to pump fluid. Upon forward rotation of the rotor assembly 30 (arrow 33), fluid to be pumped flows from a fluid source or supply via the fluid inlet 20 into the fluid space 14 and is displaced by means of the vanes 36 along the fluid flow path 24 towards the fluid outlet 22. Because the obstruction 28, when a vane 36 or a plug 35 is in the gap 29 and substantially closes the gap 29, obstructs fluid flow along the obstruction zone 26, fluid is forced to flow out of the fluid space 14 via the fluid outlet 22. The pump 10 is a positive-displacement device and can thus be used either as a liquid pump or as a gas compressor. When used as a pump, the fluid inlet 20 will be in communication with a space from which a liquid is to be displaced and the fluid outlet 22 will be in communication with either the atmosphere or a vessel, dam, ditch, or the like to which said liquid is to be displaced. On the other hand, when the pump 10 is to be used as a compressor, the fluid inlet 20 can be in communication with the atmosphere or a gas reservoir containing gas to be compressed, and the fluid outlet 22 will be in communication with a vessel in which the gas is to be compressed, unless the pump is used as a vacuum pump, venting to atmosphere.

Because of the particular construction of the pump in accordance with the invention, it is expected that the pump will be suited for pumping relatively contaminant-free fluids such as, for example, air.

Although the pump 10 is described and illustrated as being a device which employs rotation to pump fluid or to place fluid under pressure, it will be appreciated that fluid such as steam under pressure or containing potential energy, e.g. generated by combustion, can be used to drive the pump 10 as a motor and accordingly rotate the drive shaft 32, such that the pump can be employed as a motor or engine driven by a fluid under pressure or by potential energy generated by combustion. Thus, although the pump in accordance with the invention is described as being a device which converts a rotational power input into fluid flow, it will be appreciated that the device can also be employed to convert energy derived from fluid flow into rotational power output, such that the device can be employed as a fluid-driven motor or engine.

Claims

CLAIMS:

1. A pump which includes: a stator; a rotor assembly in sealing abutment with the stator and comprising a rotor rotatable about a central axis, the stator and the rotor assembly defining between them an annular fluid space extending circumferentially about the central axis, the stator having a fluid inlet leading into the fluid space, and a fluid outlet leading out of the fluid space, the inlet and outlet being spaced circumferentially from each other along the fluid space, and dividing the fluid space along its length into a major portion and a minor portion, the major portion constituting a fluid flow path for fluid flowing from the inlet towards the outlet, and the minor portion constituting an obstruction zone in which fluid flow between the inlet and the outlet is obstructed; at least one vane mounted on the rotor at a position spaced radially outwardly from the central axis and located in the fluid space for displacing fluid along the major portion of the fluid space from the inlet along the fluid flow path to the outlet in response to rotation of the rotor in a forward direction, each vane having opposed major faces, one of which is a front face facing in the forward direction, and each vane being pivotally mounted on the rotor for pivoting between an operative displacement condition in which its front face is transverse to the direction in which fluid is, in use, displaced and in which edges of the vane are spaced with a sealing clearance from the periphery of the fluid space to permit displacement along the fluid flow path of fluid by the vane as the vane moves along the fluid space in the forward direction, and an inoperative condition in which the front face of the vane is substantially parallel to the direction in which fluid is, in use, displaced; an obstruction located in the obstruction zone for obstructing fluid flow along the minor portion of the fluid space from the inlet to the outlet, the obstruction defining a gap arranged to permit passage of each vane along the obstruction zone when the vane is in its inoperative condition, while obstructing said fluid flow along the obstruction zone, so that fluid displaced along the fluid flow path from the inlet to the outlet in response to forward rotation of the rotor assembly is caused to leave the fluid space via the outlet; at least one plug fixedly mounted on the rotor assembly at a position spaced radially outwardly from the central axis and located in the fluid space, each plug having opposed major faces, and being mounted on the rotor assembly such that its major faces are substantially parallel to the direction in which fluid is, in use, displaced, each plug being shaped and located on the rotor to permit passage of the plug through the gap and to permit pivoting of each vane between its operative displacement and its inoperative conditions, each plug acting substantially to close the gap during intervals between successive occupations of the gap by a said vane; and a pivot arrangement, at least part of which is connected to each vane, for pivoting each vane between its operative displacement condition and its inoperative condition, the pivot arrangement being arranged, in response to forward rotation of the rotor, to pivot each vane, as it approaches the obstruction, into its inoperative condition in which inoperative condition it remains when in the obstruction zone and passing through the gap in the obstruction, and to pivot the vane into its operative displacement condition as it leaves the obstruction, in which operative condition the vane remains as it moves along the fluid flow path, to displace fluid along the fluid flow path.

2. A pump as claimed in Claim 1 , which includes a plurality of said vanes and a like plurality of said plugs mounted on the rotor in a circumferentially extending series in the fluid space, the plugs alternating with the vanes.

3. A pump as claimed in Claim 2, in which each vane is pivotable, independently of any other said vane, successively into its operative displacement condition and into its inoperative condition about its pivot axis.

4. A pump as claimed in Claim 3, in which there are at least two of the vanes and two of the plugs, the vanes being equally circumferentially spaced in series and the vanes also being equally circumferentially spaced in series, the plugs alternating with the vanes.

5. A pump as claimed in Claim 3 or Claim 4, in which the spacing of the vanes and the plugs relative to each other is such that opposing edges of successive vanes and plugs are circumferentially spaced with no more than a working clearance therebetween when the vanes are in their inoperative conditions.

6. A pump as claimed in Claim 5, in which the fluid space is of rectangular cross-section, its periphery being made up of a pair of curved radially inner and outer walls spaced radially from each other, and a pair of flat annular side walls axially spaced from each other and normal to the central axis, the obstruction being constituted by two spaced opposed blocks fixedly located in the fluid space between the inlet and the outlet to define the obstruction zone, the gap being defined between said blocks and extending circumferentially relative to said central axis and transversely across the fluid space between opposed walls of the fluid space.

7. A pump as claimed in Claim 6, in which the blocks are radially spaced from each other, respectively being a radially inner block having a radially outwardly facing convex surface arcuate about the central axis and a radially outer block having a radially inwardly facing concave surface arcuate about the central axis and opposed to said convex surface, the gap being defined between said convex surface and said concave surface and extending axially relative to the central axis, the pivot axis of each vane being parallel to the central axis, the major faces of each plug being substantially circumferential relative to the central axis, each vane and each plug being arcuately shaped and being flattened, such that each vane has two oppositely outwardly facing major faces, namely its front face which is concave and a major rear face which is convex, and each plug has said two major faces, namely a radially inner face which is concave and a radially outer face which is convex, the inoperative condition of each vane being such that its front and rear faces are substantially circumferential relative to the central axis, each vane being of rectangular outline when viewed face-on, each vane having dimensions in face-on outline corresponding to the rectangular cross- sectional dimensions of the fluid space, and each plug extending axially across the entire fluid space between the side walls of the fluid space, said major faces of each vane and each plug respectively being complementarily curved with regard to the respective opposed faces of the blocks defining the gap, each vane and each plug having a thickness corresponding to the radial spacing between the opposed curved faces of said opposed blocks such that each vane, when in its inoperative condition passing along the obstruction zone, and each plug when passing along the obstruction zone, slides with a sealing clearance along the gap upon forward rotation of the rotor, substantially to close the gap.

8. A pump as claimed in Claim 7, in which the stator provides an axially directed flat face located in a plane normal to the central axis, with the fluid space being defined by a groove in said flat face, the rotor comprisi ng a vane-mounting disk mounted to rotate about the central axis and on which disk each vane and plug are mounted, the mounting disk being provided with a flat face normal to the central axis, from which flat face the vanes and the plugs project, the respective flat faces of the stator and the mounting disk facing each other across the annular fluid space, such that the stator defines the radially- inner and outer walls and one side wall of the fluid space, and the flat face of the mounting disk defines the other side wall of the fluid space.

9. A pump as claimed in Claim 8, in which each vane has a stub shaft fast therewith and providing the pivot axis of the vane, the stub shaft projecting from an edge of the vane, each stub shaft being pivotally supported by, and projecting through, the mounting disk.

10. A pump as claimed in Claim 9, in which the pivot axes of the vanes are spaced along a circumferential ring located radially midway between the inner and outer walls of the fluid space, the plugs being radially spaced midway between the inner and outer walls of the fluid space.

11. A pump as claimed in Claim 10, in which the rotor assembly includes a drive shaft rotatable about an axis co-axial with the central axis, for connection to a rotational drive for rotatingly driving the rotor in the forward direction, the mounting disk being fast with and projecting radially outwardly from the drive shaft.

12. A pump as claimed in Claim 11 , which includes a stationary drive shaft casing provided on the side of the mounting disk remote from the stator, the drive shaft casing rotatably supporting the drive shaft and having a central passage co-axial with the central axis, along which passage the drive shaft passes.

13. A pump as claimed in Claim 12, in which the pivot arrangement comprises a cam path/cam follower arrangement.

14. A pump as claimed in Claim 13, in which the pivot arrangement includes a cam follower for each vane and fast with the stub shaft of the vane, the cam follower of each vane being located on the opposite side of the mounting disk from the fluid space, the cam path being defined by a groove extending eccentrically about the central axis and provided by a cam plate mounted on the drive shaft casing, each cam follower projecting into the groove and operatively engaging cam surfaces provided by the cam path, so that each vane is rotated about its pivot axes upon forward rotation of the rotor assembly, the eccentricity of the cam path about the rotor axis being selected such that each vane is pivoted to be in its inoperative condition when in the obstruction zone and in its operative displacement condition as it passes along the major portion of the fluid space.

15. A pump as claimed in Claim 14, in which each cam follower is cylindrical, being rotatable about an axis parallel to the central axis and radially spaced from the axis of its associated stub shaft.

16. A pump as claimed in Claim 15, which includes seals operative between the stator and the mounting disk for resisting leakage in a radial direction of fluid from the fluid space between the stator and the mounting disk.

17. A pump as claimed in Claim 16, in which the seals comprise annular labyrinth-type arrangements located radially inwardly and radially outwardly of the fluid space and operative between the stator and the mounting disk, each of the labyrinth-type arrangements being operative between the mounting disk and said flat face of the stator.

18. A pump as claimed in Claim 17, in which the rotor assembly includes a rotor assembly housing fast with the mounting disk and extending away from the stator, the rotor assembly housing sealingly engagin g the drive shaft casing at an end of the drive shaft casing remote from the mounting disk, so that the rotor assembly housing together with the mounting dis k forms an annular cavity for receiving lubricant and within which part of the drive shaft casing and the cam plate are housed.

19. A pump as claimed in Claim 18, in which the rotor assembly includes an arcuate side wall extending concentrically about the rotor axis, one end of the side wall being fast with the radially outer peripheral sdge of the mounting disk and the other end of the side wall being axially spaced, in a direction away from the stator, from said one end, the rotor assembly also including an annular end plate substantially parallel to the mounting disk and extending radially inwardly from said other end of the side wall, a radially inner edge of the end plate being provided with an annular seat on which is seated an annular seal which sealingly engages the drive shaft casing to seal the cavity.

20. A pump as claimed in Claim 19, in which the stator is provided with a central passage co-axial with the central axis and in which the drive shaft or an axial extension of the drive shaft is rotatably joumalled.

21. A pump as claimed in Claim 20, in which the stator includes a cover releasably secured to the side of the stator opposite the mounting disk, for sealingly covering the end of the central passage remote from the mounting disk.

22. A pump assembly which includes a pump as claimed in any one of the preceding claims having a rotational drive operatively connected to the rotor assembly for rotatingly driving the pump.