NO343543B1

NO343543B1 - A rotary vane machine with a cam track and vane mechanisms

Info

Publication number: NO343543B1
Application number: NO20180300A
Authority: NO
Inventors: Tobias Dahl; Jan Kvalem
Original assignee: Tocircle Ind As
Priority date: 2018-02-27
Filing date: 2018-02-27
Publication date: 2019-04-01
Also published as: WO2019168405A1; NO20180300A1

Description

The invention relates to a rotary vane machine for fluid processing, comprising a housing with an internal wall forming a cavity with an axis, and an inlet and outlet for process fluid; a rotor with a rotor body rotatable about a rotor axis in the cavity, a distance between an outer face of the rotor and the housing internal wall varies during the rotation; and vanes forming part of the rotor, movable relative to the rotor body.

In a rotary vane machine of this kind, closed spaces are defined in the cavity between the vanes, the outer face of the rotor and the internal wall of the housing. Since the distance between the outer face of the rotor and the housing internal wall varies in the rotational direction, the volumes of the closed spaces also vary in the rotational direction. During operation, these spaces are filled with process fluid. The location and shape of the inlet and outlet are adapted to provide a flow of process fluid from the inlet to the outlet.

The ends of the cavity are closed by end caps, and the rotor and the vanes extend throughout the cavity in axial direction. The rotor may be driven by an external driver. The rotor then drives the vanes, and the vanes move the process fluid. In this case, the rotary vane machine works as a pump if the process fluid is a liquid, and as a compressor if the process fluid is a gas or 2-phase, i.e. a mixture of liquid and gas. In other uses, the process fluid may drive the vanes and thereby the rotor, which can do external work. In this case, the rotary vane machine works as a hydromotor if the process fluid is a liquid, and as an expander if the process fluid is a gas or 2-phase.

GB2010401A describes a machine, e.g. a compressor or an engine, in which a housing and a rotor define an "eccentric annulus" divided into compartments by vanes pivoted at the rim of the rotor and held by mechanical means e.g. cranks, at their operative positions. Each vane may comprise two parts which are connected to each other by a hinge.

US2121660A discloses a rotating internal combustion motor having a rotor with swinging vanes. It is disclosed cam followers riding along a cam track for guiding the vanes. The vanes may have convex faces cylindrical about vane pivot axes, and the convex faces may have extensions extending inwardly of the rotor.

GB327153A describes engines or pumps having hollow ported rotors with movable or flexible flaps forming non-return valves. The rotor has hinged vanes and perforations leading to a hollow interior and covered by the flaps. Vanes engage an idling drum mounted on bearings.

GB230193A describes a rotary vane machine with hinged vanes.

US 3130673 A describes a rotary vane pump with a housing with a cavity and a rotor eccentrically located in the cavity, in which vanes slide freely in slots in the rotor, and thereby during rotation bear against the internal wall of the housing due to the centrifugal force. In addition, the pressure in the pump acts on the inner side of the vanes and force them against the housing internal wall.

GB190621345A describes a rotary vane pump with a casing with a cylindrical cavity and two vanes independently rotatable about a stationary spindle centrically located in the cavity. The vanes have a length equal to the internal radius of the cavity. A driven rotor with a cylindrical wall is eccentrically located in the casing, with the spindle inside the wall. The vanes pass through the wall of the rotor in two diametrically opposite openings. During the rotation, the rotor drives the vanes to rotation about the spindle. The spindle and a shaft for driving the rotor extend into the cavity from opposite sides. In this way the spindle does not interfere with the rotor, and the shaft does not interfere with the vanes, during the rotation.

W09943926A1 describes a rotary- piston machine comprising a housing having a cavity, a rotor received in the housing, which rotor having a rotor axis and a peripheral surface, inlet and outlet passages in communication with said cavity, one or more vanes radially slidably received in slots in the rotor, each vane extending radially from the internal surface of the housing to the rotor axis, and at least one working chamber being part of the cavity and which is defined by the internal surface of the housing, the peripheral surface of the rotor and the side surface of at least one vane. Each vane is articulated connected about an axis to one end of a control arm and is in the other end pivotably journaled in a fixed axle shaft having a central axis being coincident with the axis extending centrally through the cavity of the housing, which axis extend in parallel with and spaced from the rotor axis, and the rotor proper constitute the unit for power take off or power input.

US 3130673 A thus describes a rotary sliding vane machine with freely sliding vanes, while GB190621345A and W09943926A1 describe a rotary sliding vane machine with guided vanes. For a high-performance rotary sliding vane machine, guided vanes are preferable to freely sliding vanes, because guided vanes make it easier to provide sealing between the vanes and the housing internal wall without excessive wear of the vanes. The rotary sliding vane machine of GB190621345A is a low-pressure machine, which is not suited for high performance. The rotary sliding vane machine of W09943926A1 is suited for high performance. In this machine, the vanes are guided both slidably and pivotally. A more compact and less complex design, would, however be preferable.

For all rotary vane machines, the pressure va ries from the inlet to the outlet.

Consequently, in a rotary sliding vane machine there are varying differential pressures across the vanes, which causes varying tangential forces acting on the vanes.

Normally, there is also a change of direction of the tangential forces during the rotation. The forces in the slots increase friction during sliding of the vanes in the slots, which may reduce sliding and increase wear of the vanes. One way of reducing the friction is to use slide bearings in the slots. The slide bearings can be either dry, solid-state lubricated, lubricated by a liquid lubricant or lubricated by the process fluid.

In many services, to not contaminate the process fluid, lubricants other than liquid process fluid may be undesirable. Examples include using the rotary sliding vane machine as a steam expander in electric power generation or as a compressor in a heat pump in an industrial process. The process fluid, e.g. water, may, however, not be particularly suited as a lubricant. Thus, in many services high wear of the vanes is a problem.

A purpose of the invention is to provide a high-performance rotary vane machine with guided vanes that is not encumbered with the above discussed drawbacks of the rotary sliding vane machine. A further purpose is to provide a rotary vane machine with guided vanes which compared to prior art has an improved guiding system.

Another purpose is that the invention at least shall provide an alternative to prior art.

Further features, advantages and purposes of the invention and how they are achieved will appear from the description, the drawings and the claims. The purposes of the invention are achieved by the features of the independent claim, while the dependent claims specify further features of the invention.

The invention thus relates to a rotary vane machine for fluid processing, comprising a housing with an internal wall forming a cavity with an axis, and an inlet and outlet for process fluid; a rotor with a rotor body rotatable about a rotor axis in the cavity, a distance between an outer face of the rotor and the housing internal wall varies during the rotation; and vanes forming part of the rotor, movable relative to the rotor body, for defining closed spaces for process fluid, the volumes of the spaces vary during the rotation.

According to the invention the rotary vane machine comprises a cam track around the cavity axis, the cam track is fixed relative to the housing; and vane mechanisms forming part of the rotor. Each vane mechanism comprises a cam follower riding along the cam track; a radial guide for guiding the cam follower radially relative to the rotor body; a vane shaft pivotally connected to the rotor body, with a vane pivot axis parallel to the rotor axis; a vane rigidly connected to the vane shaft, having a distal end with a sealing portion for sealing against the housing internal wall; a crank rigidly connected to the vane shaft; and a connecting rod pivotally connected to the crank and the cam follower. During rotation, the cam follower follows the cam track and moves radially relative to the rotor body, the connecting rod transfers the movement of the cam follower to the crank, the crank pivots the vane shaft, and the vane shaft pivots the vane. The vane mechanism, the shape of the cam track and the shape of the housing internal wall, is adapted to position the sealing portion of the vane distal end close to or in contact with the housing internal wall.

Compared to prior art rotary vane machines with guided vanes, the invention provides a rota ry vane machine with guided vanes in which the sealing portions of the vane distal ends are more accurately located close to or in contact with the housing internal wall. Thus, the sealing between the sealing portions of the vane distal ends and the housing internal wall is improved, which in turn provides a better performance.

The vane mechanisms are part of the rotor. To distinguish the vane mechanisms from the rest of the rotor, the rest of the rotor is designated rotor body.

The number of vane mechanisms depends on the actual design and is typically between 2 and 10.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 is a cross sectional view of a rotary vane machine according to the invention;

Fig. 2 shows a detail of fig. 1 in larger scale;

Fig. 3 is a cross sectional view of another rotary vane machine according to the invention;

Fig. 4 shows a detail of fig. 3 in larger scale; and

Fig. is a perspective cutaway view of a practical embodiment of the rotary vane machine of fig. 1.

Fig. 1 is a cross sectional view of a rotary vane machine 1 according to the invention, seen in axial direction. A housing 2 has an internal wall 3 that forms a cavity 4 with a cavity axis 5. Housing 2 further has an inlet 7 with an inlet flange 8 for supplying process fluid to cavity 4, an outlet 10 with an outlet flange 11 for delivering process fluid from cavity 4, and support feet 13.

A cam track 40 is arranged around cavity axis 5 and is fixed relative to housing 2. Cam track 40 is directly or via structural elements rigidly connected to housing 2. A stationary spindle 14 forming part of these structural elements is centrally located in cavity 4. In order not to obscure the elements forming the invention, cam track 40 is illustrated by a line only, and other structural elements than spindle 14 are not shown.

A rotor 20 is connected to a rotor shaft (not illustrated in fig. 1) and rotates eccentrically in cavity 4 about a rotor axis 22 in direction 23. Rotor 20 comprises a rotor body 21 and five vane mechanisms.

Fig. 2 shows the upper vane mechanism of fig. 1 in larger scale. The following discussion refers both to fig. 1 and 2. In order not to overload fig. 1 with reference numerals, some reference numerals are left out from fig. 1.

Each vane mechanism comprises a cam follower riding along cam track 40. The cam follower comprises an arm 45 and a cam roller 42 rotatably connected to arm 45 by a cam roller pin 43, for rotation about a cam roller axis 44 when riding along cam track 40.

Each vane mechanism further comprises a radial guide 50 for guiding the cam follower radially relative to rotor body 21. Radial guide 50 is directly or via structural elements rigidly connected to rotor body 21. In order not to obscure the elements forming the invention, the illustration of radial guide 50 is simplified, and the structural elements connecting radial guide 50 and rotor body 21 is not shown. Radial guide 50 comprises two guide tracks 51. The radial guiding of the cam follower is achieved by arm 45 being arranged between the two guide tracks 51 and sliding along them. Radial guide 50 is thus a slide bearing. This kind of slide bearing is well known and will not be described in further detail.

Each vane mechanism further comprises a vane 30 rigidly connected to a vane shaft 31. Vane shaft 31 is pivotally connected to rotor body 21, with a vane pivot axis 32 parallel to rotor axis 22. Vane 30 is thereby pivotal about vane pivot axis 32. Pivoting of vane 30 makes a distal end 34 of vane 30 move towards and away from rotor body 21. Each vane mechanism also comprises a crank 41, which is also rigidly connected to vane shaft 31. Vane 30 can thus be pivoted by pivoting crank 41. Vane distal end 34 has a sealing portion 35 for sealing against housing internal wall 3, which will be discussed below.

Each vane mechanism further comprises a connecting rod 60 with an outer end 62 which is pivotally connected to crank 41 by a crank pin 53 to rotate about an axis 54, and an inner end 61 which is pivotally connected to the cam follower. Connecting rod inner end 61 is connected to arm 45 of the cam follower by the same cam roller pin 43 that connects cam roller 42 to arm 45. Connecting rod 60 is thereby pivotable about cam roller axis 44.

Alternatively, instead of arm 45 being guided by radial guide 50, cam roller pin 43 could have been guided by radial guide 50. In this alternative design, cam roller pin 43 could connect cam roller 42 and connecting rod 60, and arm 45 could have been dispensed with.

During rotation, the cam follower follows cam track 40. Since cam track 40 is fixed relative to housing 2, and thereby also fixed relative to cavity 4, and since rotor 20 rotates eccentrically in cavity 4, the cam follower moves in and out relative to rotor body 21. Radial guide 50 makes the cam follower movement radial. Connecting rod 60 transfers the movement of the cam follower to crank 41. Crank 41 is thereby pivoted about vane pivot axis 32, which, since crank 41, vane shaft 31 and vane 30 are rigidly connected to each other, pivots vane shaft 31 and vane 30.

The vane mechanism, the shape of cam track 40 and the shape of housing internal wall 3, is adapted to position sealing portion 35 of vane distal end 34 close to or in contact with housing internal wall 3 during rotation. This is achieved by correct sizing of the elements forming the vane mechanism. In one alternative, cam track 40 is cylindrical, and the elements forming the vane mechanism and housing internal wall 3 are adapted in such a way that sealing portion 35 of vane distal end 34 is always close to or in contact with housing internal 3 wall during rotation. In another alternative, housing internal wall 3 is cylindrical, and the elements forming the vane mechanism and cam track 40 are adapted in such a way that sealing portion 35 of vane distal end 34 is always close to or in contact with housing internal 3 wall during rotation.

The sealing between vane sealing portion 35 and housing internal wall 3 is achieved by a small gap. Sealing portion 35 may be manufactured with a small oversize and initially be in contact with housing internal wall 3. Sealing portion 35 will then be worn down during break-in of the rotary vane machine, to produce a good sealing between vane distal end 34 and housing internal wall 3. For this alternative, vane sealing portion 35 should preferably be made of an abradable material softer than the material of housing 2.

Due to the eccentricity of rotor 20 in cavity 4, a distance between an outer face 24 of rotor 20 and housing internal wall 3 varies in rotational direction 23. Spaces 12 are formed between rotor outer face 24, vanes 30 and housing internal wall 3, and since the distance between rotor outer face 24 and housing internal wall 3 varies in rotational direction 23, the volumes of spaces 12 also vary in rotational direction 23. During use of the rota ry vane machine, spaces 12 are filled with process fluid. The varying volumes of spaces 12 ensure that the net flow of process fluid is from inlet 7 to outlet 10. The outer face 33 of each vane 30 has a convex shape adapted to the concave face of housing internal wall 3. This is for minimising space 12 between vanes 30 and housing internal wall 3 when vanes 30 are close to housing internal wall 3, as for the right vane 30 in fig. 1. This is favourable for increasing the ratio between minimum and maximum space 12 during the rotation, and consequently increasing the performance of the rotary vane machine.

In the proximal end of vane 30, i.e. the end where vane shaft 31 is located, vane 30 has a convex face 36 which is cylindrical about vane pivot axis 32, and which faces a corresponding concave face 26 of rotor body 21. A groove 16 is located in rotor body concave face 26. Since vane convex face 36 is cylindrical about vane pivot axis 32, the distance between g roove 16 and vane convex face 36 is constant during pivoting of vane 30. A seal 25 in groove 16 seals against vane convex face 36 and prevents process fluid from entering the inner portion of the rotor during pivoting of vane 30. The seal may be a braided carbon packing or PTFE strip.

Alternatively, not illustrated, the seal could have been placed on vane 30, for sealing against rotor body concave face 26.

In another alternative, not illustrated, a seal of rotor body 21 seals against vane shaft 31. In this alternative, the seal may be a lip seal or shaft seal.

Fig. 3 is a cross sectional view of another rotary vane machine according to the invention. The rotary vane machine of fig. 3 has many similarities with the rotary vane machine of fig. 1 and 2, and similar items will only be described in detail if necessary for understanding fig. 3.

Like the rotary vane machine of fig. 1, the rotary vane machine of fig. 3 has a housing 2 with an internal wall 3 that forms a cavity 4 with a cavity axis 5, an inlet 7 and an outlet 10 for process fluid. Further, like fig. 1, a cam track 40 around cavity axis 5 is fixed relative to housing 2. Further, like fig. 1, a rotor 20 comprising a rotor body 21 and five vane mechanisms, is connected to a not illustrated rotor shaft, and rotates eccentrically in cavity 4 about a rotor axis 22 in direction 23.

Fig. 4 shows the upper vane mechanism of fig. 3 in larger scale. The following discussion refers both to fig. 3 and 4. In order not to overload fig. 3 with reference numerals, some reference numerals are left out from fig. 3.

Like the vane mechanism of fig. 1 and 2, each vane mechanism of fig. 3 and 4 comprises a cam follower riding along cam track 40. The cam follower comprises an arm 45 and a cam roller 42 rotatably connected to arm 45 by a cam roller pin 43, for rotation about a cam roller axis 44 when riding along cam track 40.

Like fig. 1 and 2, each vane mechanism of fig. 3 and 4 comprises a radial guide 50 comprising two guide tracks 51 for guiding the cam follower radially relative to rotor body 21 by arm 45 being slidably arranged between the two guide tracks 51. The illustration of radial guide 50 is simplified, and structural elements connecting radial guide 50 and rotor body 21 is not shown.

Like fig. 1 and 2, each vane mechanism of fig. 3 and 4 also comprises a vane 30 rigidly connected to a vane shaft 31 which is pivotally connected to rotor body 21, for pivoting about a vane pivot axis 32 parallel to rotor axis 22. Further, like fig. 1 and 2, a crank 41 is also rigidly connected to vane shaft 31, for pivoting vane 30. Further, vane distal end 34 has a sealing portion 35 for sealing against housing internal wall 3.

Further, like fig. 1 and 2, a connecting rod 60 comprises an outer end 62 which is pivotally connected to crank 41 by a crank pin 53 to rotate about an axis 54, and an inner end 61 which is pivotally connected to the cam follower. Unlike fig. 1 and 2, however, connecting rod inner end 61 is connected to arm 45 of the cam follower by a connecting rod pin 63 to rotate about an axis 64. Axis 64 is offset from cam roller axis 44, and connecting rod 60 is thereby pivotably connected to arm 45 offset from cam roller 42.

The vane mechanism of fig. 3 and 4 functions the same way as the vane mechanism of fig. 1 and 2. The shape of vane 30, and the sealing between vane 30 and rotor body 21, are, however, different.

The distal end of vane 30, i.e. the end away from vane shaft 31, has an extension 38 pointing inwardly of the rotor. Rotor body 21 has a slot 18 for receiving extension 38 when vane 30 pivots inwards towards rotor body 21. Extension 38 has a convex face 37 which is cylindrical about vane pivot axis 32, and which faces a corresponding concave face 27 of slot 18. A groove 17 is located in slot concave face 27. Since vane convex face 37 is cylindrical about vane pivot axis 32, the distance between groove 17 and vane convex face 37 is constant during pivoting of vane 30. A seal 29 in groove 17 seals against vane convex face 37 and prevents process fluid from entering the inner portion of the rotor during pivoting of vane 30. The seal may be a braided carbon packing or PTFE strip.

Alternatively, not illustrated, the seal could have been placed on vane extension 38, for sealing against slot concave face 27.

Fig. 5 is a perspective cutaway view of a practical embodiment of the rotary vane machine of fig. 1. The housing, the rotor body, and all vane mechanisms except one has been removed. Fig. 5 illustrates some elements that is not visualized in fig. 1 and 2. It is seen that each vane mechanism comprises a vane 30, a vane shaft 31, two cranks 41, two connecting rods 60, two cam rollers 42 (only one is visible), two cam roller pins 43 (only one is visible), a cam follower arm 45 common for both cam rollers 42, and a radial guide 50 for cam follower arm 45. Two cam tracks 40 form part of cam track discs 46. Cam track discs 46 are rigidly connected to stationary spindle 14, which is rigidly connected to the not illustrated housing. A rotor shaft 28 is visible on left side of the machine.

The process fluid is typically water. Typically, the rotational speed is 500-3600 rpm, and the process fluid pressure is typically 1-16 bar.

Claims

PATENT CLAIMS

1. A rotary vane machine (1) for fluid processing, comprising:

- a housing (2) with an internal wall (3) forming a cavity (4) with an axis (5), and an inlet (7) and outlet (10) for process fluid;

- a rotor (20) with a rotor body (21) rotatable about a rotor axis (22) in the cavity (4), a distance between an outer face (24) of the rotor (20) and the housing internal wall (3) varies during the rotation; and

- vanes (30) forming part of the rotor (20), movable relative to the rotor body (21), for defining closed spaces (12) for process fluid, the volumes of the spaces (12) vary during the rotation;

c h a r a c t e r i z e d i n comprising:

- a cam track (40) around the cavity axis (5), the cam track (40) is fixed relative to the housing (2); and

- vane mechanisms forming part of the rotor (20), each vane mechanism comprises:

- a cam follower (42) riding along the cam track (40);

- a radial guide (50) for guiding the cam follower (42) radially relative to the rotor body (21);

- a vane shaft (31) pivotally connected to the rotor body (21), with a vane pivot axis (32) parallel to the rotor axis (22);

- a vane (30) rigidly connected to the vane shaft (31), having a distal end (34) with a sealing portion (35) for sealing against the housing internal wall (3); - a crank (41) rigidly connected to the vane shaft (31); and

- a connecting rod (60) pivotally connected to the crank (41) and the cam follower (42);

wherein, during rotation, the cam follower (42) follows the cam track (40) and moves radially relative to the rotor body (21), the connecting rod (60) transfers the movement of the cam follower (42) to the crank (41), the crank pivots the vane shaft (31), and the vane shaft pivots the vane (30); the vane mechanism, the shape of the cam track (40), and the shape of the housing internal wall (3) is adapted to position the sealing portion (35) of the vane distal end (34) close to or in contact with the housing internal wall (3).

2. The rotary vane machine (1) of claim 1, wherein the cam follower comprises a rotatable cam roller (42) with a cam roller axis (44), for riding along the cam track (40).

3. The rotary vane machine (1) of claim 2, wherein the connecting rod (60) is pivotable about the cam roller axis (44).

4. The rotary vane machine (1) of any of the preceding claims, wherein the cam follower comprises an arm (45) which is guided by the radial guide (50).

5. The rotary vane machine (1) of claim 4, wherein the connecting rod (60) is pivotably connected to the arm (45).

6. The rotary vane machine (1) of any of the preceding claims, wherein the radial guide (50) is a slide bea ring.

7. The rotary vane machine (1) of any of the preceding claims, wherein a seal of the rotor body (21) seals against the vane shaft (31).

8. The rotary vane machine (1) of any of the preceding claims, wherein the vane (30) has a convex face (36, 37) cylindrical about the vane pivot axis (32), and a seal (25, 29) of the rotor body (21) seals against this face (36, 37).

9. The rotary vane machine (1) of claim 8, wherein the convex cylindrical face (37) is in the vane distal end (34), and the vane distal end has an extension (38) extending the convex cylindrical face (37) inwardly of the rotor (20).

10. The rotary vane machine (1) of any of the preceding claims, wherein the rotor body (21) has a concave face (26, 27) cylindrical about the vane pivot axis (32), and a seal of the vane (30) seals against this face (26, 27).