Scroll Pump

Abstract

The non-contact scroll pump (100) comprises a housing (110), an orbiting scroll (130) disposed within the housing, and a thrust bearing assembly (170) disposed within the housing for axially supporting the orbiting scroll. The thrust bearing assembly comprises a first plate (171) secured to the orbiting scroll, a second plate (172) spaced apart from the first plate, a ball bearing (174) disposed between the first plate and the second plate, the ball bearing configured to roll relative to the first and second plates during orbital of the orbiting scroll, and a coupling structure (175) extending axially between the housing and the second plate and coupling the housing to the second plate, the coupling structure engaging the second plate, the coupling structure comprising a spring (175d) disposed to urge the coupling structure against the second plate.

Description

[Technical Field]

[0001] The present invention relates to a scroll pump. [Background technology]

[0002] Scroll pumps are a known type of pump used in a variety of different industries to pump fluids. Scroll pumps operate by utilizing the relative motion of two intermeshing 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.

[0003] One type of scroll pump is a non-contact scroll pump. In a non-contact scroll pump, the tips (i.e., the ends of the spiral walls) of the fixed and orbiting scrolls do not contact the other scroll. Furthermore, in a non-contact scroll pump, there are no tip seals between the tips of the fixed and orbiting scrolls and the other scroll. Therefore, in a non-contact scroll pump, there is a small gap (or clearance), e.g., 10-20 microns, between the tips of the fixed and orbiting scrolls and the other scroll. To maintain this clearance, a non-contact scroll pump typically includes a thrust bearing assembly that engages one of the scrolls to maintain the correct axial position relative to the other scroll. Summary of the Invention [Means for solving the problem]

[0004] In one aspect of the present invention, a non-contact scroll pump is provided, the non-contact scroll pump including: a housing; an orbiting scroll disposed within the housing; and a thrust bearing assembly disposed within the housing for axially supporting the orbiting scroll. The thrust bearing assembly includes a first plate fixed to the orbiting scroll, a second plate spaced from the first plate, and a ball bearing disposed between the first plate and the second plate, the ball bearing configured to roll relative to the first and second plates during orbiting of the orbiting scroll. The thrust bearing assembly further includes a coupling structure extending axially between the housing and the second plate and coupling the housing to the second plate, the coupling structure engaging the second plate and including a spring disposed to urge the coupling structure against the second plate.

[0005] The coupling structure can include a nut arranged such that when the nut is loosened, the spring urges the coupling structure toward the second plate and when the nut is tightened, the spring pulls the coupling structure away from the second plate.

[0006] The spring may be arranged to urge the coupling structure against the second plate with a force of between 500N and 2000N.

[0007] The non-contact scroll pump may include three thrust bearing assemblies. Each of the three thrust bearing assemblies includes a first plate fixed to the orbiting scroll, a second plate spaced from the first plate, and a ball bearing disposed between the first plate and the second plate, the ball bearing configured to roll relative to the first and second plates during orbital movement of the orbiting scroll. Each of the three thrust bearing assemblies further includes a coupling structure extending axially between the housing and the second plate and coupling the housing to the second plate, the coupling structure engaging the second plate, and the coupling structure including a spring disposed to urge the coupling structure against the second plate. The three thrust bearing assemblies may be evenly angularly distributed in a triangular configuration about the axis of rotation of the orbiting scroll.

[0008] The non-contact scroll pump may further include a first ball bearing cage sandwiched between the first plate and the second plate, and a second ball bearing cage sandwiched between the first plate and the second plate, the first and second ball bearing cages housing the ball bearings and limiting movement of the ball bearings.

[0009] The first ball bearing cage may be secured to the first plate and the second ball bearing cage may be secured to the second plate.

[0010] The first and second ball bearing cages each have a hole, the hole in the first ball bearing cage overlaps the hole in the second ball bearing cage, and the ball bearings are received within the overlapping holes in the ball bearing cages.

[0011] The coupling structure may be a pin.

[0012] The coupling structure may be for adjusting the axial position of the orbiting scroll.

[0013] In another aspect of the present invention, a vacuum pump system is provided that includes a plurality of vacuum pumps, one of which is a non-contact scroll pump according to the above aspect.

[0014] In yet another aspect of the present invention, there is provided use of the non-contact scroll pump of any of the above aspects for pumping a fluid.

[0015] In yet another aspect of the present invention, a user-implemented method for the non-contact scroll pump of any of the above aspects is provided, the method including the steps of loosening a nut on the coupling structure to allow a spring to press the spiral wall of the orbiting scroll into contact with the fixed scroll of the non-contact scroll pump; tightening the nut to move the coupling structure away from the fixed scroll, thereby moving the orbiting scroll axially away from the fixed scroll; using a sensor to track the amount of axial movement while tightening the nut; and stopping tightening the nut when the desired amount of axial movement is reached. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram (not to scale) showing a cross-sectional view of a non-contact scroll pump. [Figure 2] FIG. 1 is a schematic diagram (not to scale) showing an enlarged cross-sectional view of a thrust bearing assembly of a non-contact scroll pump. [Figure 3] FIG. 1 is a schematic diagram (not to scale) showing a perspective view of multiple thrust bearing assemblies of a non-contact scroll pump. [Figure 4] FIG. 1 is a schematic diagram (not to scale) showing an enlarged perspective view of a portion of a thrust bearing assembly of a non-contact scroll pump. DETAILED DESCRIPTION OF THE INVENTION

[0017] FIG. 1 is a schematic diagram (not to scale) showing a cross-sectional view of a non-contact scroll pump 100.

[0018] Scroll pump 100 includes a housing portion 110 , a fixed scroll 120 , an orbiting scroll 130 , a drive shaft 140 , an actuator 150 , a main bearing assembly 160 , and a plurality of thrust bearing assemblies 170 .

[0019] In this embodiment, housing portion 110 and fixed scroll 120 together define the overall housing of scroll pump 100 within which the other components of scroll pump 100 are disposed. However, it should be understood that in other embodiments, fixed scroll 120 does not define any of the overall housing of scroll pump 100, but instead can be disposed entirely within the overall housing. In this embodiment, orbiting scroll 130 is disposed within the overall housing of scroll pump 100.

[0020] Orbiting scroll 130 is meshed with fixed scroll 120 to define a space (or flow path) through which scroll pump 100 pumps a fluid (e.g., a gas) during operation. Orbiting scroll 130 is configured to orbit relative to fixed scroll 120 to pump a fluid from an inlet (not shown) of scroll pump 100 to an outlet (not shown) of scroll pump 100. The exact physical mechanisms by which fluid is pumped by orbiting scroll 130 relative to fixed scroll 120 are well understood and will not be described herein for the sake of brevity.

[0021] The fixed scroll 120 includes a first base 122 and a first spiral wall 124. The orbiting scroll 130 includes a second base 132 and a second spiral wall 134. The first spiral wall 124 and the second spiral wall 134 are interdigitated. Furthermore, the first spiral wall 124 extends perpendicularly from the first base 122 to the second base 132, and the end face (also referred to as the tip) of the first spiral wall 124 is close to but does not contact (e.g., 10-20 microns away from) the opposing surface of the second base 132. The second spiral wall 134 extends perpendicularly from the second base 132 to the first base 122, and the end face (or tip) of the second spiral wall 134 is close to but does not contact (e.g., 10-20 microns away from) the opposing surface of the first base 122. Thus, a gap or clearance (e.g., 10-20 microns) exists between the end faces of the first and second spiral walls 124, 134 and the opposing surfaces of the first and second bases 122, 132, respectively. The distance between the end face of the first spiral wall 124 and the opposing surface of the second base 132 is the same as the distance between the second spiral wall 134 and the opposing surface of the first base 122. The clearance is empty in the sense that no object or other scroll pump component is disposed within the clearance. For example, no tip seal is present within the clearance. Thus, the end faces of the first and second spiral walls 124, 134 do not come into contact with any object or other scroll pump component.

[0022] In this embodiment, the first base 122 and the first helical wall 124 are integrally formed with one another, and the second base 132 and the second helical wall 134 are integrally formed with one another. However, in other embodiments, one or both of the helical walls 124, 134 are not integrally formed with their respective bases 122, 132.

[0023] Drive shaft 140 is coupled to orbiting scroll 130 and configured to rotate to orbitally drive orbiting scroll 130. Drive shaft 140 is disposed within the overall housing of scroll pump 100 and is mounted via a main bearing assembly 160 that aids in the rotation of drive shaft 140. In this embodiment, drive shaft 140 extends through both fixed scroll 120 and orbiting scroll 130, with orbiting scroll 130 attached to the end of drive shaft 140.

[0024] An actuator 150 (e.g., an electric motor) is coupled to the drive shaft 140 and configured to actuate the drive shaft 140, causing the drive shaft 140 to rotate and drive the orbiting scroll 130. The actuator 150 is disposed within the overall housing of the scroll pump 100 and is mounted around the drive shaft 140.

[0025] The main bearing assembly 160 mechanically couples the drive shaft 140 to the orbiting scroll 130 and the overall housing of the scroll pump 100, allowing the drive shaft 140 to rotate within the scroll pump 100 and drive the orbiting scroll 130. In this embodiment, the main bearing assembly 160 includes a bearing disposed (mechanically coupled) between a first end of the drive shaft 140 and the overall housing of the scroll pump 100, a bearing disposed (mechanically coupled) between the orbiting scroll 130 and a second end of the drive shaft 140 opposite the first end, and a bearing disposed (mechanically coupled) between the fixed scroll 120 and the drive shaft 140.

[0026] Each of the plurality of thrust bearing assemblies 170 is disposed between the orbiting scroll 130 and a housing portion 110 axially spaced from the orbiting scroll 130. Each thrust bearing assembly 170 is coupled to (and engaged with) the orbiting scroll 130 to limit and / or control the axial position of the orbiting scroll 130 relative to the fixed scroll 120. In this embodiment, three thrust bearing assemblies 170 are evenly angularly distributed in a triangular configuration about the orbiting scroll's central axis of rotation (which is further shown in FIG. 3 ) to provide a steady axial force to the orbiting scroll 130. The exact structure of each thrust bearing assembly is described in more detail below with reference to FIG. 2 .

[0027] FIG. 2 is a schematic diagram (not to scale) showing an enlarged cross-sectional view of thrust bearing assembly 170 of non-contact scroll pump 100.

[0028] Thrust bearing assembly 170 includes a first plate 171, a second plate 172, a first ball bearing cage 173a, a second ball bearing cage 173b, a plurality of ball bearings 174, an adjustment pin 175, and a casing 176. These structures enable thrust bearing assembly 170 to provide axial support to orbiting scroll 130 while also assisting orbiting scroll 130 during operation, as described in more detail below.

[0029] Each of the first and second plates 171, 172 has a first side facing the orbiting scroll 130 and a second side opposite the first side facing away from the orbiting scroll 130. Similarly, each of the first and second ball bearing cages 173a, 173b has a first side facing the orbiting scroll 130 and a second side opposite the first side facing away from the orbiting scroll 130. The first side of the first plate 171 is fixed to the back surface of the orbiting scroll 130, and the second side of the first plate 171 is fixed to the first side of the first ball bearing cage 173a. The second side of the first ball bearing cage 173a is spaced from the first side of the second ball bearing cage 173b by a ball bearing 174, thereby allowing relative movement between the first and second ball bearing cages 173a, 173b. The second side of the second ball bearing cage 173b is fixed to the first side of the second plate 172. The second side of the second plate 172 engages with the end of the adjustment pin 175.

[0030] Each of the first and second ball bearing cages 173a, 173b includes a plurality of holes in which a plurality of ball bearings 174 are disposed. Each hole in the first ball bearing cage 173a partially overlaps a corresponding hole in the second ball bearing cage 173b to form a plurality of hole pairs. Each hole pair accommodates a single ball bearing 174. The partial hole overlap allows the first and second bearing cages 173a, 173b to accommodate the orbiting movement of the orbiting scroll 130 during operation while restricting the movement of the ball bearings 174. This is further shown in FIG. 4.

[0031] The plurality of ball bearings 174 are sandwiched between the first and second plates 171, 172 such that each of the first and second plates 171, 172 contacts a ball bearing 174. Each of the plurality of ball bearings 174 is housed in a pair of holes in the first and second ball bearing cages 173 a, 173 b, respectively. The plurality of ball bearings 174 may be made of steel or ceramic.

[0032] During operation, a plurality of ball bearings 174 roll against the first and second plates 171, 172 in pairs of holes in the first and second ball bearing cages 173 a, 173 b to assist in the orbiting of the orbiting scroll 130. During operation of the scroll pump 100, the first plate 171 and the first ball bearing cage 173 a are fixed to each other and to the orbiting scroll 130 and move together with the orbiting scroll 130. Thus, during operation, the first plate 171, the first ball bearing cage 173 a, and the orbiting scroll 130 all move together against the second plate 172 and the second ball bearing cage 173 b on the plurality of ball bearings 174.

[0033] The adjustment pin 175 extends axially between the housing portion 110 and the second plate 172 of the scroll pump 100. A first end 175a of the adjustment pin 175 is attached to the housing portion 110, and a second end 175b opposite the first end 175a of the adjustment pin 175 is engaged with a second side of the second plate 172. The first end 175a of the adjustment pin 175 is threaded and coupled to the housing portion 110 via a corresponding threaded nut 175c. The threaded nut 175c is located on the first end 175a of the adjustment pin 175 and is rotatable on the threads of the first end 175a to adjust the axial position of the adjustment pin 175, thereby facilitating control of the axial position of the orbiting scroll 130 via the remainder of the thrust bearing assembly 170. The adjustment pin 175 further includes a spring 175d, which acts to press the adjustment pin 175 against the second plate 172. To press the adjustment pin 175 against the second plate 172, the spring 175d extends between a surface of the housing portion 110 facing the second plate 172 and a surface of the adjustment pin 175 facing outward from the second plate 172. One end of the spring 175d presses against the surface of the housing portion 110 facing the second plate 172, and the other end of the spring 175d presses against the surface of the adjustment pin 175 facing outward from the second plate 172. This configuration allows a user to easily and reproducibly set the axial position of the orbiting scroll 130 relative to the fixed scroll 120 in order to control the gaps between the tips of the fixed scroll 120 and the orbiting scroll 130 and the other scroll, as will be described below.

[0034] The second end 175b of the adjustment pin 175 is positioned in a tapered recess 172a provided in the second side of the second plate 172. The tapered recess 172a has a generally conical shape. More specifically, the second end 175b of the adjustment pin 175 includes a rounded surface that engages with the surface of the second side of the second plate 172 that defines the tapered recess 172a. In this manner, the rounded surface of the second end 175b of the adjustment pin 175 and the surface that defines the tapered recess 172a together form a ball-and-socket joint that allows the second plate 172 and the second ball-bearing cage 173b to articulate / rotate on the first end 175b of the adjustment pin 175.

[0035] The casing 176 surrounds the adjustment pin 175 and acts as a barrier to prevent the escape of lubricants (e.g., oil or grease) used in the ball bearing 174, the first and second bearing cages 173a, 173b, and the first and second plates 171, 172. In this embodiment, the casing 176 has a bellows shape.

[0036] To set the axial position of the orbiting scroll 130 relative to the fixed scroll 120, the user first loosens the nut 175c, which causes the spring 175d to press the tip of the orbiting scroll 130 into contact with the fixed scroll 120 with a constant force (i.e., the same force each time). Next, the user places a depth gauge through a port (not shown) throughout the housing 110 of the scroll pump 100. The user then uses the depth gauge to measure the axial distance between the housing portion 110 to which the first end 175a of the adjustment pin 175 is attached and the orbiting scroll 130. The user then zeros the depth gauge. The user then tightens the nut 175c, pulling the adjustment pin 175 axially away from the fixed scroll 120, which causes the orbiting scroll 130 to move away from the fixed scroll due to the preload force from the main bearing assembly 160. While tightening the nut 175c, the user uses the depth gauge to track the travel distance and stops tightening the nut 175c when the desired axial distance is reached. The above procedure is repeated for all other thrust bearing assemblies 170 in scroll pump 100 to uniform the axial distance across orbiting scroll 130.

[0037] The operating force of spring 175d is selected to be significantly greater than the combined force of the gas pressure on orbiting scroll 130 and the preload force from main bearing assembly 160. This ensures that adjustment pin 175 is not displaced during operation of scroll pump 100. The operating force of spring 175d is also selected to be below a force that would cause any damage to main bearing system 160 during the setting operation. For example, the operating force of spring 175d can be between 500 N and 2000 N (e.g., 1000 N). Advantageously, spring 175d allows for a consistent, known force to be used during axial distance setting, which tends to reduce the risk of a user accidentally applying excessive force and damaging other components of scroll pump 100. The consistent force of spring 175d also tends to provide a consistent zero position for the depth gauge used during the setting process.

[0038] 3 is a schematic diagram (not to scale) showing a perspective view of multiple thrust bearing assemblies 170 of non-contact scroll pump 100. As shown, in this embodiment, scroll pump 100 includes three thrust bearing assemblies 170 that are evenly angularly distributed in a triangular configuration about the central axis of rotation of orbiting scroll 130 to provide a steady axial force to orbiting scroll 130.

[0039] FIG. 4 is a schematic diagram (not to scale) illustrating an enlarged perspective view of a portion of thrust bearing assembly 170 of non-contact scroll pump 100. Specifically, FIG. 4 illustrates an enlarged view of first and second ball bearing cages 173 a, 173 b of thrust bearing assembly 170. As shown, each hole in first ball bearing cage 173 a overlaps a corresponding hole in second ball bearing cage 173 b to form a plurality of hole pairs. Each of ball bearings 174 is disposed within a respective hole pair (only one is shown in FIG. 4).

[0040] The non-contact scroll pump 100 described above can be used as part of a vacuum pumping system that includes multiple pumps and / or other components.

[0041] It will be appreciated that various modifications / variations can be made to the above-described embodiments without departing from the scope of the present invention.

[0042] In the embodiment described above, a depth gauge is used to measure the axial distance during the set-up process, however, in other embodiments, a different type of suitable distance measuring sensor is used.

[0043] In the embodiment described above, the scroll pump includes three separate thrust bearing assemblies. However, in other embodiments, the scroll pump includes a different number of thrust bearing assemblies, such as only one, only two, or four or more thrust bearing assemblies.

[0044] In the above-described embodiment, the thrust bearing assembly comprises multiple ball bearings. However, in other embodiments, the thrust bearing assembly comprises only one ball bearing.

[0045] In the above-described embodiment, the thrust bearing assembly includes a ball bearing cage that restricts the movement of the ball bearings. However, in other embodiments, the ball bearing cage is omitted.

[0046] In the above-described embodiment, elongated alignment pins are used to couple the housing to the second plate. However, in other embodiments, different types of coupling structures, such as different types of elongated members, can be used. [Explanation of symbols]

[0047] 100 Non-contact scroll pump 110 Housing 120 Fixed Scroll 122 Fixed scroll base 124 Fixed Scroll Spiral Wall 130 Rotating Scroll 132 Rotating scroll base 134 Spiral Wall of the Rotating Scroll 140 drive shaft 150 Actuator 160 Main bearing assembly 170 Thrust bearing assembly 171 First Plate 172 Second Plate 172a Recess 173a first ball bearing cage 173b Second ball bearing cage 174 Ball bearings 175 Adjustment pin 175a first end of adjustment pin 175b second end of adjustment pin 175c nut 175d spring 176 Casing

Claims

1. A non-contact scroll pump, Housing and an orbiting scroll disposed within the housing; a thrust bearing assembly disposed within the housing for axially supporting the orbiting scroll; The thrust bearing assembly comprises: a first plate fixed to the orbiting scroll; a second plate spaced from the first plate; a ball bearing disposed between the first plate and the second plate, the ball bearing configured to roll relative to the first and second plates during orbiting of the orbiting scroll; and a coupling structure extending axially between the housing and the second plate and coupling the housing to the second plate; Equipped with The coupling structure includes a pin that engages the second plate, the coupling structure including a spring arranged to urge the pin against the second plate.

2. A non-contact scroll pump as described in claim 1, wherein one end of the spring presses against the surface of the housing facing the second plate, and the other end of the spring presses against the surface of the pin facing outward from the second plate.

3. A non-contact scroll pump as described in claim 1, wherein a first end of the pin is threaded and connected to the housing via a threaded nut, the nut being rotatable to adjust the axial position of the orbiting scroll.

4. A non-contact scroll pump as described in claim 3, wherein the nut is arranged so that when the nut is loosened, the spring pushes the pin toward the second plate, and when the nut is tightened, the spring pulls the pin away from the second plate.

5. 2. The non-contact scroll pump of claim 1, wherein the spring is arranged to urge the pin against the second plate with a force between 500N and 2000N.

6. the non-contact scroll pump comprises three of the thrust bearing assemblies; 2. The non-contact scroll pump of claim 1, wherein the three thrust bearing assemblies are evenly angularly distributed in a triangular configuration about the axis of rotation of the orbiting scroll.

7. a first ball bearing cage sandwiched between the first plate and the second plate; a second ball bearing cage sandwiched between the first plate and the second plate; Furthermore, 2. The non-contact scroll pump of claim 1, wherein the first and second ball bearing cages house the ball bearings and limit movement of the ball bearings.

8. 8. The non-contact scroll pump of claim 7, wherein the first ball bearing cage is fixed to the first plate and the second ball bearing cage is fixed to the second plate.

9. each of the first and second ball bearing cages having a hole, the hole of the first ball bearing cage overlapping the hole of the second ball bearing cage; 8. The non-contact scroll pump of claim 7, wherein the ball bearings are housed within the overlapping bores of the ball bearing cage.

10. A vacuum pumping system comprising a plurality of vacuum pumps, one of which is a non-contact scroll pump according to any one of claims 1 to 9.

11. Use of the non-contact scroll pump according to any one of claims 1 to 9 for pumping a fluid.

12. A method performed by a user on the non-contact scroll pump of any one of claims 1 to 9, comprising: loosening the nut of the coupling structure to allow the spring to press the spiral wall of the orbiting scroll into contact with the fixed scroll of the non-contact scroll pump; tightening the nut to pull the pin away from the fixed scroll, thereby moving the orbiting scroll axially away from the fixed scroll; using a sensor to track the amount of axial travel while tightening the nut; a step of stopping tightening of the nut when a desired amount of axial distance is reached; A method comprising:

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