KR20230001370U - sliding vane pump - Google Patents

Abstract

Sliding vane pumps, vacuum pumps lubricated by such pumps, and vanes for sliding vane pumps are disclosed. Sliding vane pumps include a rotor rotatably mounted within a stator. The rotor includes at least one vane slidably mounted within the corresponding at least one cavity, at least one end surface of the vane being configured to abut an inner wall of the stator. The rotor, stator and at least one vane form a plurality of variable volume pumping chambers for conveying fluid from a fluid inlet to a fluid outlet upon rotation of the rotor, the at least one vane separating adjacent pumping chambers. The pump further includes a channel configured to provide a passage between adjacent pumping chambers.

Description

sliding vane pump

The field of the present invention relates to sliding vane pumps, vanes used in such pumps and vacuum pumps lubricated by such pumps.

Sliding vane pumps are used to pump liquids such as oil. Sliding vane pumps can be used with vacuum pumps to lubricate shafts and drive suction valves. These pumps operate at high rotational speeds and have a variable volume pumping chamber formed by the rotor, sliding vanes and stator inner walls. The variable volume pumping chamber draws lubricant into the chamber through an inlet and compresses the lubricant as it moves from the inlet to the outlet of the pump.

In such pumps, cavitation problems can occur in the fluid, especially when the density of the pumped fluid and the rotational speed of the rotor are high. Cavitation is the formation of small vapor-filled cavities in a low-pressure region due to rapid pressure changes in a liquid. If the pressure in this area increases, the bubble may collapse and a strong shock wave may be generated near the bubble, which may cause the pump to vibrate and generate noise.

Chemical-resistant lubricants such as PTFE lubricants are increasingly being used in vacuum pumps that pump aggressive chemicals in semiconductor chambers. These lubricants are dense, close to twice the density of mineral oil, and cavitation is becoming a growing problem in these pumps.

It is desirable to suppress cavitation of sliding vane pumps.

A first aspect provides a sliding vane pump, the pump comprising: a rotor rotatably mounted in a stator, the rotor comprising at least one vane slidably mounted in a corresponding at least one cavity; at least one end surface of the vane is configured to abut the inner wall of the stator; The rotor, stator and at least one vane form a plurality of variable volume pumping chambers for conveying fluid from a fluid inlet to a fluid outlet as the rotor rotates, the at least one vane separating adjacent pumping chambers. - and; and a channel configured to provide a passage between the adjacent pumping chambers.

Designers have recognized potential problems associated with sliding vane pumps that pump fluids such as oil. These pumps create a low pressure region where the volume of the pumping chamber increases and fluid is sucked into the pumping chamber through an inlet. Then, the pumping chamber decreases in volume toward the outlet, and the fluid is compressed and discharged through the outlet. In some circumstances, such as when the pump is rotating at high speed and/or the fluid is particularly dense, bubbles can form in the low pressure region, which can lead to cavitation in which the bubbles formed at low pressure collapse during compression of the fluid. . Cavitation in pumps causes excessive noise and vibration and should be avoided where possible. A fluid communication channel is provided between adjacent pumping chambers, allowing fluid to flow from the high pressure region of one pumping chamber to the low pressure region of the adjacent pumping chamber, relieving excessive pressure drop in the low pressure region and eliminating air bubbles in a simple, inexpensive and robust manner. formation can be inhibited.

There may be a technical bias against providing channels allowing fluid communication between pumping chambers, as this may reduce pumping efficiency and consequently cause leakage. If cavitation can be a problem, providing the size of the passageway to a controlled, predefined and limited size such that the leakage is controlled to a desired value can provide an efficient solution to the cavitation problem. A passage through or around a vane may be a solution that is simple to manufacture and provides a defined channel size that is relatively independent of pump component tolerances.

One or more sliding vanes are longitudinal elements mounted to slide along a longitudinal axis in correspondingly shaped cavities in the rotor. This sliding movement can create a variable volume pumping chamber as the rotor rotates eccentrically within the stator.

Although the channels providing passages between adjacent pumping chambers may be formed in different ways, in some embodiments the channels are formed within the at least one vane.

In some embodiments, the channels include grooves in the end surfaces of the vanes, at least a portion of which abuts the inner stator wall.

One simple and convenient way to provide the channels is to provide them as grooves in the end surfaces of the vanes.

In some embodiments, the at least one end surface is curved to provide a sealing surface with the inner stator wall.

A groove provides a depression in this sealing surface, forming a channel connecting adjacent pumping chambers and providing a passage between the leading and trailing edges of the vane during pump operation.

In another embodiment, the channel includes a passage in the vane.

Another alternative may be to provide a channel as a passageway extending through the vane. Since this vane is a sliding vane that extends out of the cavity of the rotor in an amount that varies with the position of the eccentrically mounted rotor, the passage can be made by the cavity of the rotor even if the vane is in a concave position opposite to the extended position. It is configured to be within the portion of the vane that is not obscured.

Alternatively and/or additionally, the channels may include grooves in the inner stator wall.

The location of the channels may be in the rotor or stator walls or both, and their actual location is not critical provided passages are provided to allow some flow between the pumping chambers. The amount of flow provided depends on the size of the passage. The fabrication of passages or grooves allows precise control of the bypass path between chambers and makes it relatively independent of other pump tolerances. The size of the channels can be selected to provide a desired bypass flow sufficient to suppress cavitation without unduly interfering with the performance of the pump. This may vary to some extent depending on the density of the fluid to be pumped and the rotational speed of the pump. Channels can be machined in the inner stator walls, but it may be desirable to provide channels in the vanes as they may be simpler to manufacture.

In some embodiments, both end surfaces of the vane include a groove, the groove forming a channel between the pumping chambers.

Although there may be a plurality of individual vanes extending from individual recesses or cavities in the rotor, in some embodiments the vanes may extend through the rotor with both ends of the vanes abutting diametrically opposed surfaces of the inner wall of the stator. . The vane slides within the cavity and both ends of the vane include grooved channels.

In some embodiments, the rotor is mounted for eccentric rotation within the stator.

The center of rotation of the rotor can be offset with respect to the center of the chamber formed by the inner wall of the stator, so that when it rotates its motion relative to the inner wall of the stator is eccentric.

In some embodiments, a cross section of at least a portion of the length of the sliding vane comprises a protruding portion projecting from an outer surface and configured to cooperate with a correspondingly shaped cavity in the rotor so that the vane rotates about its longitudinal axis. Prevent twisting.

To provide a channel between the leading and trailing edges during rotation of the vane, restrain the vane from twisting or rotating about its longitudinal axis so that the entry to the channel remains aligned with the opening pumping chamber. Should be. This may be done by providing a protruding portion configured to cooperate with a shaped cavity corresponding to the rotor. The protruding portion may extend from the longitudinally extending side of the vane, thereby inhibiting rotation about the longitudinal axis. In some embodiments, where the channel includes a groove extending straight from the leading edge to the trailing edge, the protruding portion projects substantially perpendicular to the groove.

The pump may be configured to pump multiple fluids, but in some embodiments the pump is configured to pump lubricant.

In some embodiments, the pump is configured to pump a high-density lubricant, wherein the lubricant has a density greater than 1.5 kg per liter.

Cavitation is a particular problem if the pump pumps high-density fluids, and lubricants with densities greater than 1.5 kg/liter can trigger cavitation in sliding vane pumps, so the embodiment is particularly suitable for such pumps.

In some embodiments, the channel comprises a cross section of 1 to 2 mm ² .

The size of the channels required to suppress cavitation will depend on the density of the fluid being pumped and the rotational speed of the pump. Channels should be limited in size so that pumping efficiency does not drop too much, but they should be large enough to relieve some pressure and suppress cavitation. In many scenarios a cross section of 1 to 2 mm ² will provide the flow necessary to suppress cavitation without unduly affecting the performance of the pump.

In some embodiments, the channels are sized such that the ultimate pressure achievable by the pump is reduced by 5 to 15%.

As mentioned earlier, the channels will reduce the ultimate pressure the pump can reach, but will have the advantage of inhibiting cavitation. It has been found that if the channel size is selected such that the ultimate pressure that the pump can reach is reduced by a limited amount, it is possible to effectively reduce cavitation while still providing an efficient pump.

In some embodiments, there may be multiple channels. In some embodiments, these may take the form of a plurality of grooves in the end surface of the vane.

In some embodiments, the channels form a substantially straight path between the two pumping chambers, while in other embodiments the channels may not be straight.

If there is a single channel and it is formed as a straight channel, there may be an advantage in ease of manufacture. However, there may be embodiments where two or more channels are provided and/or the channels form more complex angled paths.

In some embodiments, the pump includes a lubricant pump for driving the valve and supplying lubricant to the vacuum pump.

An oil pump supplying lubricant to the vacuum pump may be mounted on the same shaft as the vacuum pump, so that its rotational speed is set according to the rotational speed of the vacuum pump and can be very high. In addition, since vacuum pumps are often used to pump harmful chemicals, the lubricant inside the pump must be resistant to these chemicals, and these lubricants can have a high density. Thus, cavitation problems may occur in pumps for vacuum pumps and the embodiment may provide a particularly effective solution to this.

In some embodiments, the largest portion of the vane comprises a circular cross section; At least one additional portion of the vane has a non-circular cross section.

A second aspect provides a sliding vane pump comprising a rotor rotatably mounted within a stator, wherein the rotor comprises at least one vane slidably mounted within a corresponding at least one cavity; The rotor, stator and at least one vane form a plurality of variable volume pumping chambers for conveying fluid from a fluid inlet to a fluid outlet during rotation of the rotor, the at least one vane separating adjacent pumping chambers; ; The largest portion of the vane has a circular cross section; At least one additional portion of the vane has a non-circular cross section.

A circular cross-section for the main part of the vane means that the corresponding part of the cavity in which the vane slides has a corresponding circular cross-section. This leads to easier machining and robust components. However, the circular cross-section means that axial rotation or twisting of the vanes can occur. The heads of the vanes have a shape that must remain aligned with the stator inner wall to provide an effective seal. Therefore, some means of restraining the rotation of the vanes is required to maintain alignment of the heads. This problem is addressed by providing a portion of the vane with a non-circular cross-section that would impede rotation of the vane. Most of the vanes have a circular cross section, making it easy to machine the vane and the cavity inside the rotor into which the vane is inserted. Suppressing axial rotation of a portion of the vane will suppress axial rotation of the entire vane, so that only a portion has a non-circular cross section.

In some embodiments, the at least one additional portion is located at one end of the vane.

In some embodiments, a cross section of an annular recess in the stator configured to receive the sliding vane includes a non-circular cross section corresponding to a non-circular cross section of the vane.

It may be advantageous to have a non-circular portion at one end of the vane, and in some cases a portion of the vane extending out of the rotor cavity when the rotor is at a position furthest from the inner wall of the stator. The stator inner wall is provided with a corresponding annular recess of non-circular cross-section, which holds the vanes in a specific alignment and inhibits axial rotation as they extend from the rotor into the stator.

In some embodiments, the at least one additional portion is at both ends of the vane.

If the vane extends through the rotor, it may be advantageous for both ends of the vane to have a non-circular cross section, so that always at least one end of the vane extends into a correspondingly shaped stator, and therefore always at least one end of the vane rotates. is hindered, and thus the rotation of the entire vane is hindered.

In some embodiments, the at least one cavity in the rotor includes a circular cross-section along the length of the cavity.

If the non-circular cross-sectional portions of the vane are at both ends, it is the end portion of the vane that impedes the axial rotation of the vane and the corresponding stator shape, and the cavity in the rotor may be circular along its entire length. This makes machining easier.

In other embodiments, some of the cavities in the rotor may have non-circular cross-sections and the largest portion may have circular cross-sections.

In some embodiments, the rotor includes an additional anti-rotation component mounted to a portion of the rotor cavity configured to receive at least one additional portion of the vane.

In some embodiments, the non-circular cross-section portion of the cavity may not be formed within the rotor itself, but may be formed by additional components such as fins extending across the cavity. In some embodiments, a pin may be located at one end of the cavity, the pin obscuring a portion of the circular cross-section and positioned so as to be within a portion of the cavity that receives a portion of the non-circular cross-section of the vane, thereby preventing rotation of the sliding vane. can This may be necessary if the vanes do not extend through the rotor and only one end has a non-circular cross section.

In some embodiments, the non-circular cross section is smaller than the circular cross section.

If the non-circular cross-section of the vane is smaller than the circular cross-section, it may be advantageous because the circular cross-section portion can be machined first. Also, the vane may fit into a circular cross-section cavity in the rotor, with only a small portion of the cavity having a corresponding non-circular portion to impede rotation. This makes it possible to simply machine the cavity and to add additional anti-rotation components, such as pins, to the machined cavity.

In some embodiments, the at least one additional portion includes at least one recessed section machined from the outer surface of the vane.

As mentioned earlier, if the non-circular cross-section is smaller than the circular cross-section, the non-circular cross-section can be machined from the outer surface to form a concave section.

In some embodiments, the at least one concave section includes a flat axially extending surface.

A flat axially extending surface can be used to suppress axial rotation, and this surface is easy to machine. In this regard, a corresponding flat surface of a recess or cavity into which the vane extends may be in the rotor, or a corresponding shape into which the ends of the vane extend into if a concave section is at one or both ends of the vane. The recess of may be in the stator of the pump. This may be easier to machine than machining a shape into a cavity of a rotor.

A third aspect provides a vacuum pump including the sliding vane pump according to the first aspect or the second aspect to supply lubricant to the vacuum pump.

A fourth aspect provides a vane for a sliding vane pump according to the first aspect, wherein the vane is slidably mounted in a corresponding cavity of a rotor, and at least one end surface of the vane abuts against an inner wall of a stator. wherein the vane is configured to extend from the cavity to separate adjacent pumping chambers when mounted within the rotor of the pump, and wherein the vane is configured to provide a passageway between adjacent pumping chambers when mounted within the pump. contains channels.

In some embodiments, the channel includes a groove in the at least one end surface.

In another embodiment, the channel includes a passage extending from a leading edge to a trailing edge of the vane when the vane is mounted on the rotor.

A fifth aspect provides a vane for a sliding vane pump according to the second aspect, wherein the vane has a substantially circular cross section for a larger portion of the length of the vane and has a cross section for a smaller portion of the length of the vane. configured to have a circular cross-section, wherein the vane is slidably mounted within a correspondingly shaped cavity of the rotor, and the vane is configured to extend from the cavity such that at least one end surface of the vane abuts an inner wall of the stator; , which separates adjacent pumping chambers when mounted within the pump's rotor.

In some embodiments, the vane further includes a channel configured to provide a passage between the adjacent pumping chambers when the vane is mounted in the pump.

In some embodiments, the at least one channel is in at least one of the end surfaces.

More specific and preferred aspects are set out in the attached independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and may be combined in combinations other than those expressly provided in the claims.

Where a device feature is described as being operable to provide a function, it is understood that this includes the device feature providing that function or a device feature that is adapted or configured to provide that function.

Now, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In the drawing,
1 shows a cross section through a sliding vane pump according to one embodiment;
2 shows an end view of a pump according to one embodiment;
3 shows a stator or cylinder of a pump according to one embodiment;
Figure 4 shows a sliding vane and the sliding vane mounted in the rotor;
5 shows the cylinder of the pump mounted on the rotor;
6 shows two vanes according to a different embodiment;
7 shows a cross section through a pump according to an embodiment with a rotor in different positions;
8 schematically shows a sliding vane pump as an oil pump in a vacuum pump.

Before discussing the embodiments in more detail, an overview will be provided first.

1 shows a cross section through a sliding vane pump. This pump has a rotor (40) mounted for eccentric rotation within a stator (50). The rotor 40 is equipped with a sliding vane 10, and the sliding vane 10 contacts the inner wall of the stator 50 and is configured to slide within the rotor when rotating. Pumping chambers are formed between the sliding vane, the inner wall of the stator and the outer wall of the rotor. When the rotor rotates, counterclockwise rotation of the rotor 40 pushes the oil from the inlet 30 toward the outlet 20.

Although in this embodiment only one vane is shown extending across the diameter of the rotor, in other embodiments two or more vanes may be mounted in correspondingly shaped recesses at different locations of the rotor, the vanes being It extends from its recess and is biased into contact with the inner stator wall. The vanes, rotor and inner stator walls form a pumping chamber.

In this embodiment, there are anti-rotation components in the form of pins 41 extending across a portion of the circular cross-section at both ends of the cavity of the rotor that accommodates the vanes. The vane 10 has recesses at portions of both ends in other circular cross-sections. This recess slides against the pin so that the pin inhibits axial rotation of the vane. In other embodiments, such as those shown in FIGS. 3 and 4 , the cross-sectional shape of the stator receiving the vanes matches the non-circular shape of the vane ends, which eliminates the need for additional non-rotating components such as pins 41 to the vanes. is sufficient to suppress the rotation of However, in embodiments where the vanes do not extend through the stator (not shown), when the rotor is in a position where the vanes do not extend out of the cavity (the position to the left of the vane in this figure), the rotor cavity itself to inhibit rotation. A change in the shape of the rotor cavity or the anti-rotation component within it would be necessary.

FIG. 2 shows an end view of the pump of FIG. 1 and shows an exhaust pipe leading to the exhaust outlet 20 and an inlet machined opening leading to the inlet 30 . A pressure limiter 60 is also shown. In this embodiment, the sliding vane pump is a lubricant pump for supplying lubricant to the vacuum pump. The pressure limiter 60 controls the pressure of the lubricant supplied to the vacuum pump. In this embodiment, the rotor of the sliding vane pump is mounted on the same shaft as the vacuum pump rotor and rotates at the same high speed. During operation, the temperature of the pump will rise, which will affect the viscosity of the lubricant and the pressure of the lubricant supplied to the vacuum pump. The pressure limiter 60 serves to control the supply of lubricant to the vacuum pump.

Some components of a sliding vane pump are shown in FIGS. 3 and 4 . 3 shows a stator 50 or cylinder of the pump, the stator having a sealing surface 52 configured to correspond to the truncated circular cross sectional shape of the end portion of the vane shown in FIG. 4 and It has an annular recess or groove with an anti-rotation surface (53). This corresponding non-circular shape inhibits rotation of the vanes in the axial direction. The main part of the vane has a circular cross-section corresponding to the cross-section of a cylindrical cavity extending through the rotor.

4 shows a rotor 40 with sliding vanes 10 . The sliding vanes are shown separately from the rotor and are mounted inside the rotor. The vane on the left has a circular cross-section for most of its length, and also has a concave end portion that mates with a similarly shaped surface 52 of the stator 50 of FIG. 3, so that the vane rotates about its longitudinal axis. hinder things In the figure on the right there is a side portion protruding from the longitudinal side of the sliding vane, which side portion further hinders rotation or twisting of the vane about its longitudinal axis when mounted within the correspondingly shaped cavity of the rotor. .

5 shows a pump cylinder or stator 50 mounted on a rotor. 5 also shows a shaft 42 on which the rotor is mounted.

6 shows the end surface 8 of the vane 10 in more detail. The upper left view of FIG. 6 shows a vane of one embodiment of the second aspect, wherein the end surface 8 forms a sealing surface for sealing with the inner wall 52 of the stator, isolating the pumping chambers from one another. The sealing surface is curved to correspond to the curved inner wall 52 (see FIG. 3) of the pumping cylinder or stator 50. There is a recess on one side towards the end, making the cross section non-circular. This corresponds to the non-circular cross section of the pumping cylinder in the stator, which counteracts the rotation of the vane 12 about its longitudinal axis.

The upper right figure shows a similar embodiment, in which there is a channel 12 in the end surface 8 of the vane 10, which provides a passage between adjacent pumping chambers separated by the vane, Allows fluid to pass from a lower pressure region on one side of the vane to a higher pressure region on the other side of the vane, and this fluid flow can suppress the formation of air bubbles in the low pressure region. The channels 12 are arranged to provide a path between the leading and trailing edges of the vanes during pump operation and to provide a bypass passage between adjacent pumping chambers. It should be noted that forming the channels 12 in the end surfaces of the vanes is easy, inexpensive, and robust to manufacture. Alternatively, substantially all positions of the rotor may have passages having a cylindrical shape extending through portions of the vanes extending from recesses or cavities of the rotor. Alternatively, the channels 12 may be formed as grooves in the inner stator wall rather than the sliding vanes themselves.

The lower view of FIG. 6 shows exemplary dimensions of this particular embodiment. The grooved channels in this example are 1 mm wide and 1.4 mm deep. The overall width of the vane is 4.9 mm, and its length is 40 mm. The length of the vane corresponds in this embodiment to the distance between opposing surfaces 52 of the pumping cylinder 50, where the vane extends through the rotor.

7 shows a section through the pump, with the rotor in different positions. Arrows indicate counterclockwise rotation of the rotor. Arrow 72 points to the compression chamber (i.e., the location of the pumping chamber where rotation of the rotor reduces the size of the pumping chamber to force oil from the chamber toward and through the outlet 20). Chamber 74 is a low pressure chamber in which the pumping chamber is expanding and oil is drawn from inlet 30 into the expanding pumping chamber 74 . Region 70 is a low pressure region within the expanding chamber and is therefore where cavitation may occur. The passageway formed by grooves 12 in the end surfaces of the vanes between adjacent pumping chambers provides a flow route for fluid from the higher pressure region 72 to the lower pressure region 70 (where cavitation may occur). do. This increases the pressure in the low pressure region and suppresses cavitation. As can be appreciated, this will reduce the efficiency of the pump slightly, and the size of the channels is chosen such that cavitation is suppressed but the efficiency of the pump is still maintained at the desired level. This level can be set such that the ultimate pressure the pump can produce is reduced by only 15%, preferably less than 10%. In this regard, the pressure produced by the oil pump may in some embodiments be higher than the pressure normally required and may be controlled by a pressure limiter as shown in FIG. 2, in which case the ultimate pressure achievable by the pump may be Decreasing may not be permitted.

FIG. 8 shows one embodiment in which an oil pump 80 is mounted to lubricate and drive the valves of vacuum pump 90 . As shown, the oil pump is mounted on the shaft 42 of a vacuum pump driven by a motor 95. The rotational speed of the rotor of the oil pump is set according to the requirements of the vacuum pump. Therefore, the rotor can rotate at a very high rotational speed, typically around 1500 to 1800 rpm. Additionally, when vacuum pumps are used to evacuate chemically hazardous products, such as in semiconductor processing, the oil or lubricant supplied by pump 80 is selected to be chemically resistant. These lubricants can be dense, and one such lubricant can have a density of 1.88 kg per liter. This is more than twice the density of normal mineral oil, and the combination of high pumping speed and high density of the pumped fluid increases the likelihood of cavitation occurring within the pump, which can cause knocking. Providing channels allowing restricted fluid flow between adjacent pumping chambers can inhibit cavitation and improve pump performance.

It should be understood that while in the illustrated embodiment there is a single vane extending through the rotor, in other embodiments the vane may be formed of two separate vanes extending from opposite sides of the rotor and spring biased against the inner stator wall. do. Other embodiments with more pumping chambers and more vanes are conceivable and may benefit from limited pressure relief channels between adjacent pumping chambers.

Embodiments also provide a way to upgrade a pump by replacing a vane with a vane having grooves or passages so that an existing pump can operate at higher speeds and with a higher density of lubricant while still suppressing cavitation.

Embodiments also provide a method of servicing a sliding vane pump to replace worn vanes with grooved or passaged vanes.

Exemplary embodiments of the present invention have been disclosed in detail herein, but referring to the accompanying drawings, the present invention is not limited to the exact embodiments, and the present invention defined by the appended claims and equivalents thereof by those skilled in the art. It will be understood that various changes and modifications may be made without departing from the scope of

8 end surface of vane
10 vanes
12 channels
20 exit
30 entrance
40 rotor
41 pin
42 shaft
50 stator or pump cylinder
52 stator annular recess sealing surface
53 anti-rotation surface
60 pressure limiter
70 Potential cavitation site behind the vane head
72 compressed pumping chamber
74 Depressurized pumping chamber
80 oil pump
90 vacuum pump
95 motor

Claims (30)

In the sliding vane pump,
A rotor rotatably mounted within a stator, the rotor comprising at least one vane slidably mounted within a corresponding at least one cavity, wherein at least one end surface of the vane is configured to abut an inner wall of the stator. is; The rotor, stator and at least one vane form a plurality of variable volume pumping chambers for conveying fluid from a fluid inlet to a fluid outlet as the rotor rotates, the at least one vane separating adjacent pumping chambers. - and;
and a channel configured to provide a passage between the adjacent pumping chambers. 2. The sliding vane pump of claim 1, wherein the channel is formed in the at least one vane. 3. The sliding vane pump according to claim 2, wherein the channel includes a groove in an end surface of the vane, and at least a portion of the end surface abuts an inner wall of the stator. 3. The sliding vane pump of claim 2, wherein the channel comprises a passage in the vane. 5. The sliding vane pump according to any one of claims 1 to 4, wherein the at least one end surface corresponds to an inner wall of the stator and is curved to provide a sealing surface against the inner wall of the stator. 6. The sliding vane pump according to any one of claims 1 to 5, wherein the channel comprises a groove in an inner wall of the stator. 7. The sliding vane pump according to any one of claims 1 to 6, wherein the sliding vane pump includes a single vane slidably mounted in a cavity extending through the rotor, and both ends of the vane are connected to an inner wall of the stator. tangential, sliding vane pumps. 8. The sliding vane pump according to claim 7 when dependent from claim 3, wherein both end surfaces of the vanes include the grooves. 9. The sliding vane pump according to any one of claims 1 to 8, wherein the rotor is mounted for eccentric rotation within the stator. 10. The method of claim 1 , wherein a cross section of at least a portion of the length of the sliding vane includes a protruding portion configured to cooperate with a correspondingly shaped depression of a cavity in the rotor, the protruding portion comprising: A sliding vane pump that restrains the vanes from twisting about their longitudinal axis. 11. The sliding vane pump according to any one of claims 1 to 10, wherein the pump is configured to pump lubricant. 12. The sliding vane pump of claim 11, wherein the pump is configured to pump a high density lubricant, wherein the density of the lubricant is greater than 1.5 Kg/liter. 13. The sliding vane pump according to any one of claims 1 to 12, wherein the channel comprises a cross section of 1 to 2 mm ² . 14. The sliding vane pump according to any one of claims 1 to 13, wherein the channel is sized such that the ultimate pressure achievable by the pump is reduced by 5 to 15%. 15. A method according to any one of claims 1 to 14, wherein the largest part of the vane comprises a circular cross-section;
A sliding vane pump, wherein at least one additional portion of the vane comprises a non-circular cross section. A sliding vane pump comprising a rotor rotatably mounted in a stator, comprising:
the rotor includes at least one vane slidably mounted within the corresponding at least one cavity;
The rotor, stator and at least one vane form a plurality of variable volume pumping chambers for conveying fluid from a fluid inlet to a fluid outlet during rotation of the rotor, the at least one vane separating adjacent pumping chambers; ;
The largest portion of the vane has a circular cross section;
and wherein at least one additional portion of the vane has a non-circular cross section. 17. The sliding vane pump according to claim 15 or 16, wherein the at least one additional portion is at one end of the vane. 18. The sliding vane pump of claim 17, wherein the at least one additional portion is at both ends of the vane. 19. The sliding vane pump according to any one of claims 15 to 18, wherein a cross section of a recess in the stator configured to receive the sliding vane comprises a non-circular cross section corresponding to a non-circular cross section of the vane. 20. The sliding vane pump according to any one of claims 15 to 19, wherein at least one cavity in the rotor comprises a circular cross-section along the length of the cavity. 21. The sliding vane pump according to any one of claims 15 to 20, wherein the rotor includes an additional anti-rotation component mounted in a portion of the rotor cavity configured to receive at least one additional portion of the vane. 22. The sliding vane pump according to any one of claims 15 to 21, wherein the non-circular cross section is smaller than the circular cross section. 23. A sliding vane pump according to any one of claims 15 to 22, wherein the at least one additional portion comprises at least one recessed section machined from the outer surface of the vane. 24. The sliding vane pump of claim 23, wherein the at least one concave section comprises a flat axially extending surface. 25. The sliding vane pump according to any one of claims 1 to 24, wherein the pump comprises a lubricant pump for driving the valve and supplying lubricant to the vacuum pump. A vacuum pump comprising the sliding vane pump according to any one of claims 1 to 25 for supplying a lubricant to the vacuum pump. A vane for a sliding vane pump according to any one of claims 1 to 15, wherein the vane is slidably mounted in a corresponding cavity of a rotor, and at least one end surface of the vane is attached to an inner wall of the stator. wherein the vane is configured to extend from the cavity so as to abut and separate adjacent pumping chambers when mounted in the rotor of the pump;
wherein the vane includes a channel configured to provide a passage between the adjacent pumping chambers when mounted in the pump. 28. The vane of claim 27, wherein the channel comprises a groove in at least one end surface of the vane. 29. The vane of claim 28, wherein the channel comprises a passageway extending through the vane. 25. A vane for a sliding vane pump according to any one of claims 15 to 24, wherein the vane has a substantially circular cross section for a larger portion of the length of the vane and for a smaller portion of the length of the vane. configured to have a non-circular cross-section, wherein the vane is slidably mounted within a correspondingly shaped cavity of the rotor, and wherein the vane extends from the cavity such that at least one end surface of the vane abuts an inner wall of the stator. vane, which separates adjacent pumping chambers when mounted within the pump's rotor.

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