Scroll pump
By using ball bearings and thrust bearing components of thermal blockers in non-contact scroll pumps, the axial position deviation problem of the scroll disc caused by heat transfer is solved, and the accuracy and efficiency of pumping fluid are improved.
Patent Information
- Application Number
- CN202380032481.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-03-30
- Filing Date
- 2023-03-30
- Publication Date
- 2024-12-13
AI Technical Summary
During operation, the non-contact scroll pump causes the axial position of the scroll disc to be offset due to heat transfer, which affects the pumping efficiency and accuracy.
Using a thrust bearing assembly including ball bearings and thermal blockers, axial support and thermal management are achieved through coupling structures and adjustment pins to ensure stable position and temperature matching of the scroll during operation.
It effectively reduces heat transfer, prevents the axial position of the scroll disc, improves the accuracy and efficiency of pumping fluid, and enhances the stability of the equipment.
Smart Images
Figure CN119137351A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a vortex pump. Background Art
[0002] A scroll pump is a known type of pump used in a variety of different industries to pump fluids. A scroll pump operates by using the relative motion of two intermeshing scrolls, called a fixed scroll and an orbiting scroll, to pump fluids. Each of the fixed and orbiting scrolls includes a spiral wall extending from a base.
[0003] One type of vortex pump is a non-contact vortex pump. In a non-contact vortex pump, there is no contact between the end of each of the fixed and orbiting scrolls (i.e., the end of the spiral wall) and the other scroll. In addition, in a non-contact vortex pump, there is no end seal between the end of each of the fixed and orbiting scrolls and the other scroll. Therefore, in a non-contact vortex pump, there is a small gap (or gap), such as 10-20 microns, between the end of each of the fixed and orbiting scrolls and the other scroll. In order to maintain the gap, the non-contact vortex pump generally includes a thrust bearing assembly engaged with one of the scrolls to keep the scroll in the correct axial position relative to the other scroll. Summary of the invention
[0004] In one aspect of the present invention, a non-contact scroll pump is provided, the non-contact scroll pump comprising a housing, an orbiting scroll located in the housing, and a thrust bearing assembly located in 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 apart from the first plate, and a ball bearing located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during the orbiting of the orbiting scroll. The thrust bearing assembly further comprises a coupling structure extending between the housing and the second plate to couple the housing to the second plate, wherein the coupling structure comprises a thermal blocker for reducing heat transfer from the second plate to the coupling structure during operation of the non-contact scroll pump.
[0005] The coupling structure may include a pin having a hollow section. The hollow section may extend axially from near the end of the pin that contacts the second plate. The thermal interrupter may be provided at least in part by the hollow section.
[0006] The pin may have the same coefficient of thermal expansion as the section of the housing from which the pin extends.
[0007] The coupling structure may comprise one or more inserts located between the second plate and the remainder of the coupling structure, wherein the thermal interrupter is at least partially provided by the one or more inserts.
[0008] The non-contact scroll pump may further include a first ball bearing retainer sandwiched between the first plate and the second plate, and a second ball bearing retainer sandwiched between the first plate and the second plate, wherein the first and second ball bearing retainers accommodate the ball bearings to constrain movement of the ball bearings.
[0009] A first ball bearing cage may be secured to the first plate and a second ball bearing cage may be secured to the second plate.
[0010] The first and second ball bearing cages may each include a hole, the hole of the first ball bearing cage overlapping the hole of the second ball bearing cage, and wherein the ball bearings are received within the overlapping holes of the ball bearing cages.
[0011] 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 apart from the first plate, and a ball bearing located between the first plate and the second plate, wherein the ball bearing is configured to roll against the first and second plates during the orbiting of the orbiting scroll. Each of the three thrust bearing assemblies also includes a coupling structure extending between the housing and the second plate to couple the housing to the second plate, wherein the coupling structure includes a thermal blocker for reducing heat transfer from the second plate to the coupling structure during operation of the non-contact scroll pump. The three thrust bearing assemblies may be evenly angularly distributed around the rotation axis of the orbiting scroll in a triangular form.
[0012] The coupling structure may be used to adjust the axial position of the orbiting scroll.
[0013] In another aspect of the present invention, a vacuum pumping system is provided, comprising a plurality of vacuum pumps, wherein one of the vacuum pumps is the non-contact scroll pump of the above aspect.
[0014] In yet another aspect of the present invention, there is provided use of the non-contact scroll pump according to any one of the above aspects for pumping a fluid. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 is a schematic diagram (not to scale) showing a cross-sectional view of a non-contact scroll pump;
[0016] Figure 2 is a schematic diagram (not to scale) showing a close-up cross-sectional view of a thrust bearing assembly of a non-contact scroll pump.
[0017] Figure 3 is a schematic diagram (not to scale) showing a perspective view of a plurality of thrust bearing assemblies of a non-contact scroll pump; and
[0018] Figure 4is a schematic diagram (not to scale) showing a close-up perspective view of a portion of a thrust bearing assembly of a non-contact scroll pump. DETAILED DESCRIPTION
[0019] Figure 1 is a schematic diagram (not to scale) showing a cross-sectional view of non-contact scroll pump 100 .
[0020] The 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 .
[0021] In this embodiment, the housing portion 110 and the fixed scroll 120 together define the overall housing of the scroll pump 100, and the other components of the scroll pump 100 are located within the overall housing. However, it will be understood that in other embodiments, the fixed scroll 120 may not define any overall housing of the scroll pump 100, but may be completely located within the overall housing. In this embodiment, the orbiting scroll 130 is located within the overall housing of the scroll pump 100.
[0022] The orbiting scroll 130 is meshed with the fixed scroll 120 to define a space (or passage) used by the scroll pump 100 during operation to pump a fluid (e.g., a gas). The orbiting scroll 130 is configured to orbit relative to the fixed scroll 120 to pump the fluid from an inlet (not shown) of the scroll pump 100 to an outlet (not shown) of the scroll pump 100. The precise physical mechanism of pumping fluid by the orbiting of the orbiting scroll 130 relative to the fixed scroll 120 is well known and will not be described herein for the sake of brevity.
[0023] 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 meshed with each other. In addition, the first spiral wall 124 extends vertically from the first base 122 toward the second base 132, so that the end surface (also referred to as the end) of the first spiral wall 124 is close to (e.g., 10-20 microns away) but does not contact the opposite surface of the second base 132. The second spiral wall 134 extends vertically from the second base 132 toward the first base 122, so that the end surface (or end) of the second spiral wall 134 is close to (e.g., 10-20 microns away) but does not contact the opposite surface of the first base 122. Therefore, there is a gap or void (e.g., 10-20 microns) between the end surfaces of the first and second spiral walls 124, 134 and the corresponding opposite surfaces of the first and second bases 122, 132. The distance between the end surface 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 gap is empty because no object or other vortex pump components are located in the gap. For example, there is no end seal in the gap. Therefore, the end surfaces of the first and second spiral walls 124, 134 do not contact any object or other vortex pump components.
[0024] In this embodiment, the first base 122 and the first spiral wall 124 are integrally formed with each other, and the second base 132 and the second spiral wall 134 are integrally formed with each other. However, in other embodiments, one or both of the spiral walls 124, 134 are not integrally formed with their respective bases 122, 132.
[0025] The drive shaft 140 is coupled to the orbiting scroll 130 and is configured to rotate to drive the orbiting of the orbiting scroll 130. The drive shaft 140 is located within the overall housing of the scroll pump 100 and is mounted via a main bearing assembly 160, which facilitates the rotation of the drive shaft 140. In this embodiment, the drive shaft 140 extends through both the fixed scroll 120 and the orbiting scroll 130, and the orbiting scroll 130 is mounted at the end of the drive shaft 140.
[0026] An actuator 150 (eg, an electric motor) is coupled to the drive shaft 140 and is configured to actuate the drive shaft 140 to cause the drive shaft 140 to rotate, thereby driving the orbiting of the orbiting scroll 130. The actuator 150 is located within the overall housing of the scroll pump 100 and is mounted around the drive shaft 140.
[0027] 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, so that the drive shaft 140 can rotate within the scroll pump 100 to drive the orbiting scroll 130. In this embodiment, the main bearing assembly 160 includes a bearing located between (and mechanically coupling) a first end of the drive shaft 140 and the overall housing of the scroll pump 100, a bearing located between (and mechanically coupling) the orbiting scroll 130 and a second end of the drive shaft 140 opposite the first end, and a bearing located between (and mechanically coupling) the fixed scroll 120 and the drive shaft 140.
[0028] A plurality of thrust bearing assemblies 170 are each located between the orbiting scroll 130 and the 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 constrain and / or control the axial position of the orbiting scroll 130 relative to the fixed scroll 120. In this embodiment, there are three thrust bearing assemblies 170 evenly distributed angularly around the central rotation axis of the orbiting scroll in a triangular form to provide a stable axial force on the orbiting scroll 130 (which is Figure 3 The exact structure of each thrust bearing assembly will be referred to in Figure 2 Describe in more detail.
[0029] Figure 2 is a schematic diagram (not to scale) showing a close-up cross-sectional view of the thrust bearing assembly 170 of the non-contact scroll pump 100 .
[0030] The thrust bearing assembly 170 includes a first plate 171, a second plate 172, a first ball bearing holder 173a, a second ball bearing holder 173b, a plurality of ball bearings 174, an adjustment pin 175, and a housing 176. Through these structures, the thrust bearing assembly 170 provides axial support for the orbiting scroll 130 while also facilitating the orbiting of the orbiting scroll 130 during operation, as will be described in more detail below.
[0031] Each of the first and second plates 171, 172 has a first side facing the orbiting scroll 130 and a second side opposite to the first side and facing away from the orbiting scroll 130. Each of the first and second ball bearing holders 173a, 173b also has a first side facing the orbiting scroll 130 and a second side opposite to the first side and facing away from the orbiting scroll 130. The first side of the first plate 171 is fixed to the rear 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 holder 173a. The second side of the first ball bearing holder 173a is spaced apart from the first side of the second ball bearing holder 173b by the ball bearing 174, thereby allowing relative movement of the first and second ball bearing holders 173a, 173b. The second side of the second ball bearing holder 173b is fixed to the first side of the second plate 172. The second side of the second plate 172 is engaged with the end of the adjustment pin 175.
[0032] The first and second ball bearing retainers 173a, 173b each include a plurality of holes in which the plurality of ball bearings 174 are located. Each hole of the first ball bearing retainer 173a partially overlaps with a corresponding hole of the second ball bearing retainer 173b to form a plurality of hole pairs. Each hole pair accommodates a single ball bearing 174. The partial overlap of the holes enables the first and second bearing retainers 173a, 173b to accommodate the orbiting motion of the orbiting scroll 130 during operation while constraining the motion of the ball bearings 174. This is particularly useful in Figure 4 Further shown in .
[0033] A plurality of ball bearings 174 are sandwiched between the first and second plates 171, 172 so that each of the first and second plates 171, 172 is in contact with the ball bearing 174. Each of the plurality of ball bearings 174 is accommodated in a corresponding pair of holes of the first and second ball bearing retainers 173a, 173b. The plurality of ball bearings 174 may be formed of steel or ceramic.
[0034] During operation, in order to facilitate the orbiting of the orbiting scroll 130, the plurality of ball bearings 174 roll against the first and second plates 171, 172 within the pair of holes of the first and second ball bearing retainers 173a, 173b. During operation of the scroll pump 100, the first plate 171 and the first ball bearing retainer 173a, which are fixed to each other and to the orbiting scroll 130, move together with the orbiting scroll 130. Therefore, during operation, the first plate 171, the first ball bearing retainer 173a, and the orbiting scroll 130 all move together on the plurality of ball bearings 174 relative to the second plate 172 and the second ball bearing retainer 173b.
[0035] 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 engages 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 at the first end 175a of the adjustment pin 175 and can be rotated 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.
[0036] The second end 175b of the adjustment pin 175 is disposed in the tapered groove 172a in the second side of the second plate 172. The tapered groove 172a has a generally conical shape. More specifically, the second end 175b of the adjustment pin 175 includes a circular surface that engages with a surface of the second side of the second plate 172 that defines the tapered groove 172a. In this manner, the circular surface of the second end 175b of the adjustment pin 175 and the surface that defines the tapered groove 172a together form a ball-and-socket joint, which enables the second plate 172 and the second ball bearing retainer 173b to articulate / rotate on the first end 175b of the adjustment pin 175.
[0037] The adjustment pin 175 has the same coefficient of thermal expansion as the housing portion 110. This is to prevent changes in ambient temperature from causing the housing portion and the adjustment pin 175 to expand at different rates, which would result in an undesirable shift in the axial position of the orbiting scroll 130. During operation of the scroll pump 100, the orbiting scroll 130, the first plate 171, the second plate 172, the ball bearing retainer 173a, 173b and the ball bearing 174 all heat up at a much greater rate than the housing portion 110. The adjustment pin 175 is in thermal contact with the second plate 172 and therefore in thermal contact with the hotter parts of the scroll pump 100. It is desirable that the adjustment pin 175 heats up at substantially the same rate as the housing portion 110 (i.e., slower than the second pad 172) so that the thermal expansion of the adjustment pin 175 can match the thermal expansion of the housing portion 110. Again, this is to prevent an undesirable shift in the axial position of the orbiting scroll 130 during operation of the scroll pump 100.
[0038] In order to match the thermal expansion rate of the adjustment pin 175 with the thermal expansion rate of the housing portion 110 during operation, the adjustment pin 175 also includes a hollow section 300. The hollow section 300 extends axially from the second end 175b so that there is still enough material (e.g., at least 1 mm thick) at the second end 175b to withstand the axial force of contact with the second plate 172. The hollow section 300 acts as an isolating thermal blocker, which generally reduces the heat transfer from the second plate 172 to the adjustment pin 175. This tends to help thermally isolate the adjustment pin 175 from the second pad 172 so that the adjustment pin 175 is maintained at substantially the same temperature as the housing portion 110. Since the adjustment pin 175 and the housing portion 110 have the same coefficient of thermal expansion, they expand at substantially the same rate.
[0039] In this embodiment, the hollow section 300 is cylindrical, but it will be appreciated that other shapes may be used as long as the hollow section 300 still acts as a suitable thermal blocker.
[0040] As an alternative or additional thermal blocker to the hollow section 300, the thrust bearing assembly 170 may include one or more inserts (not shown) located between the second end 175b of the adjustment pin 175 and the second plate 172. The one or more inserts act as a physical barrier, thereby providing a thermal blocker to help reduce heat transfer from the second plate 172 to the adjustment pin 175. The one or more inserts may be formed of steel or a ceramic material.
[0041] The housing 176 surrounds the adjustment pin 175 and acts as a barrier to prevent the escape of lubricant (eg, oil or grease) for the ball bearing 174, the first and second bearing holders 173a, 173b, and the first and second plates 171, 172. In this embodiment, the housing 176 has a bellows shape.
[0042] Figure 3 is a schematic diagram (not to scale) showing a perspective view of a plurality of thrust bearing assemblies 170 of the non-contact scroll pump 100. As shown, in this embodiment, the scroll pump 100 includes three thrust bearing assemblies 170 that are evenly angularly distributed around the central rotation axis of the orbiting scroll in a triangular form to provide a stable axial force on the orbiting scroll 130.
[0043] Figure 4 is a schematic diagram (not to scale) showing a close-up perspective view of a portion of the thrust bearing assembly 170 of the non-contact scroll pump 100. Specifically, Figure 4A close-up view of the first and second bearing cages 173a, 173b of the thrust bearing assembly 170 is shown. As shown, each hole of the first ball bearing cage 173a partially overlaps with a corresponding hole of the second ball bearing cage 173b to form a plurality of hole pairs. The ball bearings 174 are each located within a corresponding hole pair ( Figure 4 Only one ball bearing 174 is shown.
[0044] The non-contact scroll pump 100 described above may be used as part of a vacuum pumping system including a plurality of pumps and / or other components.
[0045] It will be appreciated that various modifications / alterations may be made to the above-described embodiments without departing from the scope of the present invention.
[0046] In the above-described embodiment, the scroll pump includes three independent thrust bearing assemblies. However, in other embodiments, the scroll pump includes a different number of thrust bearing assemblies, for example, only one, two, or more than three.
[0047] In the above-described embodiments, the thrust bearing assembly comprises a plurality of ball bearings. However, in other embodiments, the thrust bearing assembly comprises only one ball bearing.
[0048] In the above-described embodiments, the thrust bearing assembly includes a ball bearing cage to constrain the movement of the ball bearings. However, in other embodiments, the ball bearing cage is omitted.
[0049] In the above described embodiments, an elongated adjustment pin is used to couple the housing to the second plate. However, in other embodiments, a different type of coupling structure may be used, such as a different type of elongated member.
[0050] Reference Signs
[0051] 100: Non-contact vortex pump
[0052] 110: Shell
[0053] 120: Fixed scroll
[0054] 122Fixed scroll base
[0055] 124Spiral wall of fixed scroll
[0056] 130: Orbiting scroll
[0057] 132 Orbiting scroll base
[0058] 134 The spiral wall of the orbiting scroll
[0059] 140: Drive shaft
[0060] 150: Actuator
[0061] 160: Main bearing assembly
[0062] 170: Thrust bearing assembly
[0063] 171: First board
[0064] 172: Second board
[0065] 172a: Groove
[0066] 173a: First ball bearing cage
[0067] 173b: Second ball bearing cage
[0068] 174: Ball bearing
[0069] 175: Adjustment pin
[0070] 175a: First end of the adjustment pin
[0071] 175b: Second end of the adjustment pin
[0072] 175c: Nut
[0073] 176: Shell
[0074] 300: Hollow section
Claims
1. A non-contact vortex pump, comprising: case; an orbiting scroll located within the casing; as well as A thrust bearing assembly located in the housing for axially supporting the orbiting scroll, wherein the thrust bearing assembly comprises: a first plate secured to the orbiting scroll; a second plate spaced apart from the first plate; a ball bearing located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during orbiting of the orbiting scroll; and A coupling structure extends between the housing and the second plate to couple the housing to the second plate, wherein the coupling structure includes a thermal blocker for reducing heat transfer from the second plate to the coupling structure during operation of the non-contact scroll pump.
2. The non-contact scroll pump according to claim 1, wherein: The coupling structure comprises a pin having a hollow section extending axially from adjacent an end of the pin in contact with the second plate, and wherein the thermal interrupter is at least partially provided by the hollow section.
3. The non-contact scroll pump according to claim 2, wherein: The pin has the same coefficient of thermal expansion as the section of the housing from which the pin extends.
4. A non-contact scroll pump according to any preceding claim, wherein: The coupling structure comprises one or more inserts located between the second plate and the remainder of the coupling structure, wherein the thermal interrupter is at least partially provided by the one or more inserts.
5. A non-contact scroll pump according to any preceding claim, further comprising: a first ball bearing cage sandwiched between the first plate and the second plate; as well as a second ball bearing cage sandwiched between the first plate and the second plate, The first and second ball bearing retainers accommodate the ball bearings to restrict the movement of the ball bearings.
6. The non-contact scroll pump according to claim 5, wherein: A first ball bearing retainer is secured to the first plate and a second ball bearing retainer is secured to the second plate.
7. The non-contact scroll pump according to claim 5 or 6, wherein: the first and second ball bearing cages each include a hole, the hole of the first ball bearing cage overlapping the hole of the second ball bearing cage, and Therein, the ball bearings are accommodated in overlapping holes of the ball bearing cage.
8. A non-contact scroll pump according to any preceding claim, wherein: The non-contact vortex pump includes three thrust bearing assemblies, Wherein, each of the three thrust bearing assemblies comprises: a first plate secured to the orbiting scroll; a second plate spaced apart from the first plate; a ball bearing located between the first plate and the second plate, the ball bearing being configured to roll against the first and second plates during orbiting of the orbiting scroll; and a coupling structure extending between the housing and the second plate to couple the housing to the second plate, wherein the coupling structure includes a thermal blocker for reducing heat transfer from the second plate to the coupling structure during operation of the non-contact scroll pump, The three thrust bearing assemblies are evenly distributed angularly around the rotation axis of the orbiting scroll in a triangular form.
9. A non-contact scroll pump according to any preceding claim, wherein: The coupling structure is used to adjust the axial position of the orbiting scroll.
10. A vacuum pumping system comprising a plurality of vacuum pumps, wherein: One of the vacuum pumps is a non-contact scroll pump according to any preceding claim.
11. Use of the non-contact scroll pump according to any one of claims 1 to 9 for pumping fluid.