GB2614581A

GB2614581A - Scroll pump

Info

Publication number: GB2614581A
Application number: GB2205795.4A
Authority: GB
Inventors: Yap Emily; Jonathan Grant Nicolas; Chromek Lukas
Original assignee: Edwards Ltd
Current assignee: Edwards Ltd
Priority date: 2022-04-21
Filing date: 2022-04-21
Publication date: 2023-07-12
Anticipated expiration: 2042-04-21
Also published as: GB2614581B; WO2023131806A3; WO2023131806A2; GB202205795D0

Abstract

A scroll pump comprises a housing, a fixed scroll, an orbiting scroll and a rotation-resisting assembly including first and second devices 340, 342. The first device comprises a first body portion 402 and first and second arms 404, 406 extending therefrom. The first arm is coupled to the orbiting scroll and the second arm is coupled to a relatively fixed component of the scroll pump. The first and second arms extend and flex to allow movement of the orbiting scroll relative to the housing in generally orthogonal directions. The second device comprises a second body portion 502 and third and fourth arms 504, 506 extending therefrom. The third arm is coupled to the orbiting scroll and the fourth arm is coupled to the relatively fixed component. The third and fourth arms extend and flex to allow movement of the orbiting scroll relative to the housing in generally orthogonal directions. The first and second arms may each be one of a pair of first and second arms on opposing sides of the first body portion.

Description

SCROLL PUMP

FIELD OF THE INVENTION

The present invention relates to scroll pumps, which are often referred to as scroll compressors.

BACKGROUND

Scroll pumps are a known type of pump used in various different industries to pump fluid. Scroll pumps operate by using the relative motion of to two intermeshed scrolls (known as a fixed scroll and an orbiting scroll) to pump fluid. Each of the fixed and orbiting scrolls includes a spiral wall extending from a base.

Figure 1 is schematic illustration (not to scale) of a first prior art scroll pump 100. The scroll pump 100 comprises a pump housing 102 and a drive shaft 104 having an eccentric shaft portion 106. The shaft 104 is driven by a motor 108 and the eccentric shaft portion 106 is connected to an orbiting scroll 110 so that during use rotation of the shaft 104 imparts an orbiting motion to the orbiting scroll 110 relative to a fixed scroll 112, thereby to pump fluid along a fluid flow path between a pump inlet 114 and a pump outlet 116 of the scroll pump 100.

The radial clearances between the orbiting and fixed scrolls are accurately controlled so that lubricant is generally not required in the scroll arrangement. The axial clearances between the scrolls are sealed with tip seals. The arrangement means that a scroll pump is suitable for pumping a dry or clean environment such as a semi-conductor processing tools. However, the concentric shaft 104 and the eccentric shaft portion 106 are supported by bearings 118 and 120 which are typically lubricated. A bellows arrangement 122 is located on the orbiting scroll side of the scroll arrangement and isolates the bearings from the high vacuum region 124 at the inlet 114, thereby to define a region 126 containing the bearings, which region 126 is typically at or close to atmospheric pressure and may thus be considered a near-atmospheric or low vacuum region 126. In this way, the bellows arrangement 122 prevents contamination of the high vacuum region 124 by lubricant and other contaminants. The bellows arrangement 122 also acts to prevent rotation of the -2 -orbiting scroll but is sufficiently flexible to allow orbiting motion. A counterweight 128 is provided for balancing the weight of the orbiting components of the pump.

Figure 2 is schematic illustration (not to scale) of a second prior art scroll pump 200. In the second scroll pump 200, instead of a bellows arrangement, an anti-rotation device 202 resists rotation of the orbiting scroll 110 relative to a fixed, or housing, part 204. The anti-rotation device 202 is fixed to the housing part 204 and the orbiting scroll 110 by fixing members 206 and flexes to allow orbiting motion of the orbiting scroll. The anti-rotation device 202 may be lubricant free. Shaft seals 208, 210 are provided to seal the bearings 118, 120 from the high vacuum region 124 of the pump.

SUMMARY OF INVENTION

In an aspect, there is provided a scroll pump comprising: a pump housing; a fixed scroll, the fixed scroll being fixed relative to the pump housing; an orbiting scroll; a first device; and a second device. The first device comprises a first body portion, a first arm extending from the first body portion, and a second arm extending from the first body portion. The first arm of the first device is coupled to the orbiting scroll, and the second arm of the first device is coupled to a relatively fixed component of the scroll pump. The first arm is configured to flex to allow movement of the orbiting scroll relative to the housing in a first direction, and the second arm is configured to flex to allow movement of the orbiting scroll relative to the housing in a second direction generally orthogonal to the first direction. The second device comprises a second body portion, a third arm extending from the second body portion, and a fourth arm extending from the second body portion. The third arm of the second device is coupled to the orbiting scroll, and the fourth arm of the second device is coupled to the relatively fixed component of the scroll pump. The third arm is configured to flex to allow movement of the orbiting scroll relative to the housing in the second direction, and the fourth arm is configured to flex to allow movement of the orbiting scroll relative to the housing in the first direction.

The first device may be a first rotation-resisting device for resisting rotation of the orbiting scroll and allowing for said orbiting motion. The second -3 -device may be a second rotation-resisting device for resisting rotation of the orbiting scroll and allowing for said orbiting motion.

The scroll pump may further comprise a counterweight arranged to balance the weight of orbiting components of the scroll pump. The scroll pump may further comprise a counterweight arranged to balance the weight of at least the orbiting scroll, the first device, and the second device.

The first device may be made from a flexible polymer material, a flexible plastics material, and/or a flexible spring steel. The second device may be made from a flexible polymer material, a flexible plastics material, and/or a flexible spring steel.

The first arm may extend from the first body portion in a direction that is substantially orthogonal to the direction in which the second arm extends from the first body portion.

The first device may comprise at least two pairs of opposing arms extending from the first body portion. The at least two pairs of opposing arms of the first device may include a first pair of arms and a second pair of arms. The first arm may be an arm of the first pair of arms. The first pair of arms may be coupled to the orbiting scroll. The second arm may be an arm of the second pair of arms. The second pair of arms may be coupled to the relatively fixed component of the scroll pump, e.g. the housing. The first pair of arms may be configured to flex to allow movement of the orbiting scroll relative to the housing in the first direction. The second pair of arms may be configured to flex to allow movement of the orbiting scroll relative to the housing in the second direction. The first pair of arms may extend from the first body portion in directions that are substantially parallel to each other. The second pair of arms may extend from the first body portion in directions that are substantially parallel to each other. The first pair of arms may extend from the first body portion in directions that are substantially orthogonal to the directions in which the second pair of arms extend from the first body portion.

The second device may further comprise a fifth arm extending from the second body portion. The fifth arm of the second device may be coupled to either the orbiting scroll or the relatively fixed component of the scroll pump. -4 -

The third arm may extend from the second body portion in a direction that is substantially orthogonal to the direction in which the fourth arm extends from the second body portion.

The second device may comprise at least two pairs of opposing arms extending from the second body portion. The at least two pairs of opposing arms of the second device may include a third pair of arms and a fourth pair of arms. The third arm may be an arm of the third pair of arms. The third pair of arms may be coupled to the orbiting scroll. The fourth arm may be an arm of the fourth pair of arms. The fourth pair of arms may be coupled to the relatively fixed component of the scroll pump. The third pair of arms may be configured to flex to allow movement of the orbiting scroll relative to the housing in the second direction and the fourth pair of arms are configured to flex to allow movement of the orbiting scroll relative to the housing in the first direction. The third pair of arms may extend from the second body portion in directions that are substantially parallel to each other. The fourth pair of arms may extend from the second body portion in directions that are substantially parallel to each other. The third pair of arms may extend from the second body portion in directions that are substantially orthogonal to the directions in which the fourth pair of arms extend from the second body portion.

The second device may have substantially the same mass as the first device. The second device may have substantially the same shape and/or size as the first device. The second device may be substantially identical to the first device.

The scroll pump may further comprise a drive shaft coupled to the orbiting scroll, the drive shaft being arranged such that rotation of the drive shaft imparts an orbiting motion to the orbiting scroll relative to the fixed scroll.

In a further aspect, there is provided a rotation-resisting assembly for use with a scroll pump. The rotation-resisting assembly comprises: a first device comprising a first body portion, a first arm extending from the first body portion in a first direction, and a second arm extending from the first body portion in a second direction generally orthogonal to the first direction; and a second device comprising a second body portion, a third arm extending from the second body -5 -portion in the second direction, and a fourth arm extending from the second body portion in the first direction. The first arm is connected to the third arm. The second arm is connected to the fourth arm.

In a further aspect, there is provided use of the scroll pump of any preceding aspect to pump fluid.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is schematic illustration (not to scale) of a first prior art scroll pump; Figure 2 is schematic illustration (not to scale) of a second prior art scroll pump; Figure 3 is schematic illustration (not to scale) of a scroll pump; Figure 4 is a schematic illustration (not to scale) showing an example of a first rotation-resisting device for use in a scroll pump; and Figures 5 and 6 are schematic illustrations (not to scale) showing first and second rotation-resisting devices coupled together, for use in a scroll pump.

DETAILED DESCRIPTION

Figure 3 is schematic illustration (not to scale) of a scroll pump 300. The 20 scroll pump 300 comprises a pump housing 302 and a drive shaft 304 having a concentric portion 305 and an eccentric shaft portion 306. The scroll pump 300 further comprises a motor 308 arranged to drive the drive shaft 304.

The scroll pump 300 further comprises a fixed scroll 310 and an orbiting scroll 312. The fixed scroll 310 is fixed relative to the pump housing 302.

The eccentric shaft portion 306 is connected to the orbiting scroll 312 so that, during use, rotation of the drive shaft 304 imparts an orbiting motion to the orbiting scroll 312 relative to the fixed scroll 310, thereby to pump fluid along a fluid flow path between a pump inlet 314 and a pump outlet 316 of the scroll pump 300.

In this embodiment, the fixed scroll 310 comprises an opening 318 through which the drive shaft 304 extends. The drive shaft 304 (in particular, the -6 -eccentric shaft portion 306 of the drive shaft 304) is connected to the orbiting scroll 312 on an opposing side of the fixed scroll 310 to the motor 308.

A high vacuum region 320 is located at the pump inlet 314. A low vacuum, or atmospheric, region 322 is located at the pump outlet 316.

A first bearing 324 supports the drive shaft 304 for rotation. The first bearing 324 is fixed relative to the pump housing 302 or, as shown, the fixed scroll 310. A second bearing 326 connects the eccentric portion 306 of the drive shaft 304 to the orbiting scroll 312, allowing angular movement of the orbiting scroll 312 relative to the eccentric portion 306. A first shaft seal 328 resists the passage of lubricant from the first bearing 324 towards an interface 330 between the orbiting scroll 312 and the fixed scroll 310. A second shaft seal 332 resists the passage of lubricant from second bearing 326 to the interface 330.

The scroll pump 300 implements a so-called reverse scroll arrangement. In this arrangement, the bearing arrangement is located in the low vacuum region, and thus a relatively small pressure differential exists across the bearings and therefore leakage can be effectively prevented by the first and second shaft seals 328, 332. Further, the below-described rotation-resisting devices can be located in the high vacuum region with reduced or eliminated risk of contamination. Nevertheless, in other embodiments, the scroll pump may be a scroll pump other than one which implements the reverse scroll arrangement.

The scroll pump 300 further comprises a first rotation-resisting device 340. The first rotation-resisting device 340 is described in more detail later below with reference to Figure 4. The coupling of the first rotation-resisting device 340 to the other components of the scroll pump 300 is described in more detail later below.

In this embodiment, the first rotation-resisting device 340 is located in the high vacuum region 320 of the scroll pump 300. The first rotation-resisting device 340 is coupled between the orbiting scroll 312 and the pump housing 302. In use, the first rotation-resisting device 340 resists rotation of the orbiting scroll 312 but allows orbiting motion of the orbiting scroll 312 relative to the fixed scroll 310. In this embodiment, the first rotation-resisting device 340 is lubricant- -7 -free. In this embodiment, the first rotation-resisting device 340 is made from a flexible material such as a plastics material. The first rotation-resisting device 340 may be a single-piece polymer component made, for example, by Additive Manufacturing.

The scroll pump 300 further comprises a second rotation-resisting device 342. The second rotation-resisting device 342 is described in more detail later below with reference to Figures 5 and 6. The coupling of the second rotation-resisting device 342 to the other components of the scroll pump 300 is described in more detail later below.

In this embodiment, the second rotation-resisting device 342 is located in the high vacuum region 320 of the scroll pump 300. The second rotation-resisting device 342 is coupled between the orbiting scroll 312 and the pump housing 302. In use, the second rotation-resisting device 342 may resist, at least to some extent, rotation of the orbiting scroll 312 but allow orbiting motion of the orbiting scroll 312 relative to the fixed scroll 310. In this embodiment, second rotation-resisting device 342 is lubricant-free. In this embodiment, the second rotation-resisting device 342 is made from a flexible material such as a plastics material. The second rotation-resisting device 342 may be a single-piece polymer component made, for example, by Additive Manufacturing.

In this embodiment, the scroll pump 300 further comprises a counterweight 344. The counterweight 344 may be coupled to an orbiting component of the scroll pump 300, such as the orbiting scroll 312. The counterweight 344 balances the weight of the orbiting components of the scroll pump 300. Specifically in this embodiment, the counterweight 344 tends to balance the weights of the orbiting scroll 112, the second bearing 326 and the eccentric portion 306 of the drive shaft 304. Also, as described in more detail later below, the counterweight 344 tends to balance the weights of the first rotation-resisting device 340 and the second rotation-resisting device 342, the motion of which combination of elements, in use, tends to be substantially equivalent to an orbiting mass. The orbiting scroll 312 tends to constitute the majority of the weight of the orbiting components, and its centre of mass is located relatively close to the scroll plate of the orbiting scroll 312. -8 -

In this embodiment, the scroll pump 300 further comprises a cap 346. The cap 346 is fixed to a raised seat 348 of the orbiting scroll 312 and seals the low vacuum region 322, containing the counterweight 344 and the bearings 324, 326 from the high vacuum region 320.

Figure 4 is a schematic illustration (not to scale) showing an example first rotation-resisting device 340 which may be implemented in embodiments of the invention. The first rotation-resisting device 340 comprises a first central body portion 402, and a plurality of arms (namely, a pair of first arms 404, and a pair of second arms 406) extending from the first body portion 402. The arms 404, 406 are arranged in two opposing pairs. Each of the arms 404, 406 has a respective connecting portion at a distal end thereof. In particular, each of the first arms 404 comprises a first connecting portion 408, and each of the second arms 406 comprises a second connecting portion 410. In this embodiment, when installed in the scroll pump 300. one of the pairs of arms 404, 406 is connected to the housing 302 and the other of the pairs is connected to the orbiting scroll 312.

In the orientation showing in Fig 4, the first arms 404 are oriented along an x-axis, while the second arms 406 are oriented along a y-axis which is substantially perpendicular to the x-axis.

Figures 5 and 6 are schematic illustrations (not to scale) each showing the first rotation-resisting device 340 and the second rotation-resisting device 342. Figures 5 and 6 illustrate the coupling together of the first rotation-resisting device 340 and the second rotation-resisting device 342. Figure 5 shows a front view of the coupled-together rotation-resistant devices, while Figure 6 shows a rear view of the coupled-together rotation-resistant devices.

The second rotation-resisting device 342 comprises a second central body portion 502, and a plurality of arms (namely, a third arm 504, and a fourth arm 506) extending from the second body portion 502. Each of the arms 504, 506 has a respective connecting portion at a distal end thereof. In particular, the third arm 504 comprises a third connecting portion 508, and the fourth arm 506 comprises a fourth connecting portion 510. In this embodiment, when installed in the scroll pump 300, one of the arms 504, 506 is connected to the housing 302 and the other is connected to the orbiting scroll 312. -9 -

In the orientation showing in Figures 5 and 6, the third arm 504 is oriented along the y-axis, while the fourth arms 506 is oriented along the x-axis. In this embodiment, the second rotation-resisting device 342 is a generally L-shaped device.

In this embodiment, the third connecting portion 508 of the third arm 504 is connected to the first connecting portion 408 of one or the first arms 404, such as by a fastener that passes through the first and third connecting portions 408, 508 (as illustrated in Figure 5 by an arrow and the reference numeral 512).

In this embodiment, the fourth connecting portion 510 of the fourth arm 506 is connected to the second connecting portion 410 of one or the second arms 406, such as by a fastener that passes through the second and fourth connecting portions 410, 510 (as illustrated in Figure 5 by an arrow and the reference numeral 514).

Preferably, the second rotation-resisting device 342 has substantially the same mass as the first rotation-resisting device 340.

Referring back to Figure 3, in this embodiment the pair of first arms 404 and the third arm 504 are connected by first fasteners 350 to the orbiting scroll 312. In particular, one first fastener 350 passes through the first and third connecting portions 408, 508 of a first arm 404 and the third arm 504 (as illustrated in Figure 5 by an arrow and the reference numeral 512) and connects to the orbiting scroll 312. Another first fastener 350 passes through the first connecting portion 408 of the other first arm 404 and connects to the orbiting scroll 312.

Also, in this embodiment the pair of second arms 406 and the fourth arm 506 are connected by second fasteners 352 to a relatively fixed component of the scroll pump 300, i.e. one or more components that are fixed relative to the orbiting scroll 312. In particular, in this embodiment, the pair of second arms 406 and the fourth arm 506 are connected by second fasteners 352 to the housing 302. More specially, one second fastener 352 passes through the second and fourth connecting portions 410, 510 of a second arm 406 and the fourth arm 506 (as illustrated in Figure 5 by an arrow and the reference numeral 514) and connects to the housing 502. Another second fastener 352 passes -10 -through the second connecting portion 410 of the other second arm 406 and connects to the housing 302.

In use, as the orbiting scroll 312 moves (i.e. is driven by the drive shaft), the pair of first arms 404 flex to allow movement of the orbiting scroll 312 (relative to fixed component of the scroll pump 300, e.g. the housing 302) in a first direction, which in this embodiment is the 'y' direction. Also, the pair of second arms 406 flex to allow movement of the orbiting scroll 312 in a second direction, which in this embodiment is the 'x' direction.

This flexing of the first and second arms 404, 406 as the orbiting scroll 312 moves results in an oscillating, linear motion of the first body portion 402 of the first rotation-resisting device 340. In particular, the first body portion 402 tends to move back-and-forth along one of the first or second directions (i.e., the y-or x-directions).

Also, in use, as the orbiting scroll 312 moves (i.e. is driven by the drive shaft), the third arms 504 flexes to allow movement of the orbiting scroll 312 (relative to fixed component of the scroll pump 300, e.g. the housing 302) in the second direction, i.e. the 'x' direction. Also, the fourth arm 506 flexes to allow movement of the orbiting scroll 312 in the first direction, which in this embodiment is the 'y' direction This flexing of the third and fourth arms 504, 506 as the orbiting scroll 312 moves results in an oscillating, linear motion of the second body portion 502 of the second rotation-resisting device 342. In particular, the second body portion 502 tends to move back-and-forth along the other of the first or second directions to the direction along which the first body portion 402 move.

Thus, in use, the first body portion 402 and the second body portion 502 oscillate along generally orthogonal directions. The frequencies of oscillation of the first body portion 402 and the second body portion 502 tend to be equal to each other. In use, the motion of the combination of the first and second rotation-resisting devices 340, 342 tends to be equivalent to that of a single entity or mass undergoing orbital motion (i.e. about the same point or axis as the orbital scroll 312). The orbital angular momentum of the combined first and second rotation-resisting devices 340, 342 tends to be equivalent to a single orbiting mass.

Advantageously, the motion of the combination of the first and second rotation-resisting devices 340, 342 being equivalent to that of a single orbiting entity or mass facilitates balancing or countering of the weights of the first and second rotation-resisting devices 340, 342 by the counterweight 344. In this embodiment, the counterweight balances the weight of orbiting components of the scroll pump, and moreover balances the weights of the first rotation-resisting device and the second rotation-resisting device (whose body portions are oscillating linearly).

As described above, the orbital motion of the orbiting scroll 312 imparts oscillating, linear motion on the body portion of a rotation-resisting device. If only a single such rotation-resisting device is implemented in the scroll pump, the oscillation of the body portion of the of the rotation-resisting device along a linear direction can cause undesirable vibration of the scroll pump. Such vibration can result in undesirable noise and/or damage to the scroll pump. Advantageously, by implementing two rotation-resisting devices coupled as described in more detail above, the orthogonal linear oscillations of the body portions of the of the rotation-resisting devices tend to be equivalent to a single orbiting entity, which is more easily countered with a standard counterweight.

Advantageously, the masses of either or both of the rotation-resisting devices, and/or the counterweight, can be tailored dependent on one or more characteristics of the scroll pump and/or pumping parameters.

Preferably the body portion of the either or both of the rotation-resisting devices is an annular or loop-shaped element that may fit around the drive shaft. For example, a body portion may be a square or round loop. This tends to make the rotation-resisting device dynamically more stable.

The above-described scroll pump 300 may be used as part of a vacuum pumping system including multiple pumps and/or other components.

-12 -It will be appreciated that various modifications/deviations may be made to the above-described embodiments without departing from the scope of the invention.

In the above-described embodiments, the first rotation-resisting device comprises two pairs of opposing arms extending from the first body portion.

However, in other embodiments, the first rotation-resisting device comprises a different number of arms extending from the first body portion. Preferably, the first rotation-resisting device comprises at least two pairs of opposing arms extending from the first body portion.

In the above-described embodiments, the second rotation-resisting device comprises two arms extending from the second body portion. However, in other embodiments, the second rotation-resisting device comprises a different number of arms extending from the first body portion. For example, the second rotation-resisting device may comprise two pairs of opposing arms extending from the second body portion. In some embodiments, the second rotation-resisting device is substantially identical to the first rotation-resisting device. This tends to make the second rotation-resisting device dynamically more stable. Additionally, this tends to reduce the manufacturing burden. Preferably, the second rotation-resisting device comprises at least two arms extending from the second body portion. More preferably, the second rotation-resisting device comprises more than two arms extending from the second body portion. For example, in some embodiments, the second rotation-resisting device comprises three or more arms extending from the second body portion, including the third arm, the fourth arm, and a fifth arm. The fifth arm of the second rotation-resisting device may be coupled to either the orbiting scroll or a relatively fixed component of the scroll pump such as the housing. The fifth arm may tend to oppose twisting movement of the second rotation-resisting device in use.

In the above embodiments, the second rotation-resisting device is positioned at an axial position along the length of the scroll pump further away from the motor than the first rotation-resisting device. However, in other embodiments, the second rotation-resisting device is positioned at an axial position that is closer to the motor than the first rotation-resisting device.

-13 -Preferably, the first and second rotation-resisting devices are positioned at substantially the same axial position along the length of the scroll pump as each other. For example, one of the rotation-resisting devices may be located radially inwards or outwards of the other. This advantageously tends to reduce bending moment of the devices.

In the above embodiments, the first and second rotation-resisting devices are proximate to one another, and indeed are directly connected together. This tends to facilitate countering of the weights of the rotation-resisting devices by the counterweight. However, in other embodiments, the first and second rotation-resisting devices may be spaced apart in the axial direction.

In the above embodiments, the second rotation-resisting device is configured to resist rotation of the orbiting scroll relative to the fixed scroll, at least to some extent, but to allow for orbiting motion of the orbiting scroll relative to the fixed scroll. However, in other embodiments, the second rotation-resisting device does not resist rotation of the orbiting scroll relative to the fixed scroll to any significant extent. Instead, the rotation of the orbiting scroll relative to the fixed scroll may be prevented or opposed by the first rotation-resisting device only.

In the above embodiments, the first and second rotation-resisting devices are made of a flexible plastics material. However, in other embodiments, one or both of these devices is made of a different material. For example, one or both of the first and second rotation-resisting devices may be made from a flexible polymer material, a flexible plastics material, and/or a flexible spring steel.

-14 -REFERENCE NUMERAL LIST 100 -first prior art scroll pump 102-pump housing 104 -drive shaft 106 -eccentric shaft portion 108-motor -orbiting scroll 112-fixed scroll 114 -pump inlet 116-pump outlet 118, 120 -bearings 122-bellows arrangement 124-high vacuum region 126-low vacuum region 128-counterweight

-second prior art scroll pump

202 -anti-rotation device 204 -fixed part 206 -fixing members 208, 210-shaft seals 300 -scroll pump 302 -pump housing 304 -drive shaft 305 -concentric portion 306 -eccentric portion 308 -motor 310 -fixed scroll 312-orbiting scroll 314-pump inlet 316-pump outlet 318-opening 320 -high vacuum region 322 -low vacuum region 324 -first bearing 326 -second bearing 328 -first shaft seal 330 -interface 332 -second shaft seal 340 -first rotation-resisting device 342 -second rotation-resisting device 344 -counterweight 346 -cap 348 -raised seat to 350 -first fasteners 352 -second fasteners 402 -first central body portion 404 -pair of first arms 406 -pair of second arms 408 -first connecting portion 410-second connecting portion 502 -second central body portion 504 -third arm 506 -fourth arm 508 -third connecting portion 510 -fourth connecting portion 512, 514 -connections by fasteners

Claims

-16 -CLAIMS1. A scroll pump comprising: a pump housing; a fixed scroll, the fixed scroll being fixed relative to the pump housing; an orbiting scroll; a first device; and a second device wherein the first device comprises: a first body portion; a first arm extending from the first body portion; and a second arm extending from the first body portion; the first arm of the first device is coupled to the orbiting scroll, and the second arm of the first device is coupled to a relatively fixed component of the scroll pump; the first arm is configured to flex to allow movement of the orbiting scroll relative to the housing in a first direction, and the second arm is configured to flex to allow movement of the orbiting scroll relative to the housing in a second direction generally orthogonal to the first direction; the second device comprises: a second body portion; a third arm extending from the second body portion; and a fourth arm extending from the second body portion; the third arm of the second device is coupled to the orbiting scroll, and the fourth arm of the second device is coupled to the relatively fixed component of the scroll pump; and the third arm is configured to flex to allow movement of the orbiting scroll relative to the housing in the second direction, and the fourth arm is configured -17 -to flex to allow movement of the orbiting scroll relative to the housing in the first direction.
2. The scroll pump of claim 1, wherein the first device is a first rotation-resisting device for resisting rotation of the orbiting scroll and allowing for said orbiting motion.
3. The scroll pump of claim 1 or 2, wherein the second device is a second rotation-resisting device for resisting rotation of the orbiting scroll and allowing for said orbiting motion.
4. The scroll pump of any of claims 1 to 3, further comprising a counterweight arranged to balance the weight of orbiting components of the scroll pump.
5. The scroll pump of any of claims 1 to 4, further comprising a counterweight arranged to balance the weight of the orbiting scroll, the first device, and the second device.zo
6. The scroll pump of any of claims 1 to 5, wherein the first device is made from a flexible polymer material, a flexible plastics material, and/or a flexible spring steel.
7. The scroll pump of any of claims 1 to 6, wherein the second device is made from a flexible polymer material, a flexible plastics material, and/or a flexible spring steel.
8. The scroll pump of any of claims 1 to 7, wherein the first arm extends from the first body portion in a direction that is substantially orthogonal to the direction in which the second arm extends from the first body portion.
9. The scroll pump of any of claims 1 to 8, wherein: the first device comprises at least two pairs of opposing arms extending from the first body portion, the at least two pairs of opposing arms of the first device including a first pair of arms and a second pair of arms; the first arm is an arm of the first pair of arms; the first pair of arms are coupled to the orbiting scroll; the second arm is an arm of the second pair of arms; the second pair of arms are coupled to the relatively fixed component of the scroll pump; and wherein the first pair of arms are configured to flex to allow movement of the orbiting scroll relative to the housing in the first direction and the second pair of arms are configured to flex to allow movement of the orbiting scroll relative to the housing in the second direction.
10. The scroll pump of claim 9, wherein: the first pair of arms extend from the first body portion in directions that are substantially parallel to each other; the second pair of arms extend from the first body portion in directions that are substantially parallel to each other; the first pair of arms extend from the first body portion in directions that are substantially orthogonal to the directions in which the second pair of arms extend from the first body portion.
11. The scroll pump of any of claims 1 to 10, wherein the second device further comprises a fifth arm extending from the second body portion, the fifth arm of the second device being coupled to either the orbiting scroll or the relatively fixed component of the scroll pump.
12. The scroll pump of any of claims 1 to 11, wherein the third arm extends from the second body portion in a direction that is substantially orthogonal to the direction in which the fourth arm extends from the second body portion.
13. The scroll pump of any of claims 1 to 12, wherein the second device comprises at least two pairs of opposing arms extending from the second body portion, the at least two pairs of opposing arms of the second device including a third pair of arms and a fourth pair of arms; the third arm is an arm of the third pair of arms; the third pair of arms are coupled to the orbiting scroll; the fourth arm is an arm of the fourth pair of arms; the fourth pair of arms are coupled to the relatively fixed component of the scroll pump; and wherein the third pair of arms are configured to flex to allow movement of the orbiting scroll relative to the housing in the second direction and the fourth pair of arms are configured to flex to allow movement of the orbiting scroll relative to the housing in the first direction.
14. The scroll pump of claim 13, wherein: the third pair of arms extend from the second body portion in directions that are substantially parallel to each other; -20 -the fourth pair of arms extend from the second body portion in directions that are substantially parallel to each other; the third pair of arms extend from the second body portion in directions that are substantially orthogonal to the directions in which the fourth pair of 5 arms extend from the second body portion.
15. The scroll pump of any of claims 1 to 14, wherein the second device has substantially the same mass as the first device.
16. The scroll pump of any of claims 1 to 15, wherein the second device is substantially identical to the first device.
17. The scroll pump of any of claims 1 to 16, further comprising a drive shaft coupled to the orbiting scroll, the drive shaft being arranged such that rotation of the drive shaft imparts an orbiting motion to the orbiting scroll relative to the fixed scroll.
18. A rotation-resisting assembly for use with a scroll pump, the rotation-resisting assembly comprising: a first device comprising: a first body portion; a first arm extending from the first body portion in a first direction; and a second arm extending from the first body portion in a second direction generally orthogonal to the first direction; and a second device comprising: a second body portion; a third arm extending from the second body portion in the second direction; and -21 -a fourth arm extending from the second body portion in the first direction; wherein the first arm is connected to the third arm; and the second arm is connected to the fourth arm.
19. Use of the scroll pump of any of claims 1 to 17 to pump fluid.