Scroll vacuum pump

Abstract

This enables high pumping performance of scroll vacuum pumps during continuous operation and / or improved cold-start characteristics of such scroll vacuum pumps. [Solution] The movable scroll member, in conjunction with the fixed scroll member, forms a circular annular portion and a spiral scroll portion, the annular portion and the scroll portion each extending from the inlet end to the outlet end, the scroll portion being formed by the engagement of a spiral scroll wall with a spiral scroll groove, and the annular portion being formed by the engagement of a circular annular wall with a circular annular groove, and in a thermally low state of the pump system, the minimum radial distance between the radially inward inner surface of the annular wall and the radially inward inner wall portion of the annular groove is smaller than the minimum radial distance between the radially outward outer surface of the annular wall and the radially outward outer wall portion of the annular groove.

Description

[Technical Field]

[0001] The present disclosure relates to an improvement of a scroll vacuum pump. The scroll vacuum pump according to the present invention comprises: a pump system including a fixed scroll member and a movable scroll member that interact with the fixed scroll member to perform a pumping action; a drive shaft having an eccentric portion for driving the movable scroll member, the drive shaft rotating about a rotation axis during operation; and an electric drive motor for the drive shaft. [Background Art]

[0002] Scroll vacuum pumps are basically known in European Patent Application Publication No. 3153708, European Patent Application Publication No. 3617511, and European Patent Application Publication No. 3647599.

[0003] Scroll pumps, particularly scroll vacuum pumps, are positive displacement pumps that compress against atmospheric pressure and can be used particularly as compressors. Scroll vacuum pumps may be used to generate a vacuum in a recipient connected to a gas inlet of the scroll vacuum pump.

[0004] Scroll vacuum pumps are also referred to as spiral vacuum pumps or spiral pumping devices. The pumping principle underlying scroll vacuum pumps is basically known in the prior art. The fixed scroll member has spiral-shaped grooves on a support body, and a spiral wall engages into the grooves, the spiral wall being arranged on a corresponding support body of the movable scroll member. Optionally, in order to improve the pumping effect, a circular groove may additionally be provided on the fixed scroll member, and a circularly configured wall may be provided corresponding to the movable scroll member.

[0005] These scroll members are inserted into each other, one inward and the other outward, such that the walls of the movable scroll member form a crescent-shaped volume, also called a pocket, in the groove of the fixed scroll member. The movable scroll member can move along a circular orbit via an eccentric portion of the drive shaft, and therefore, this movable scroll member, together with its support, is also called the orbital. Thus, this movable scroll member performs a so-called centrosymmetric oscillation relative to the fixed scroll member, which is also called "orbital motion" or "rocking motion." Accordingly, the fixed scroll member, together with its support, is also called the stator. The crescent-shaped volume formed in the wall and the corresponding groove gradually moves inward within the groove during the orbital motion of the movable scroll member, and as a result, the process gas to be pumped is pumped by the changing volume from the gas inlet located radially outward in the pump system to the gas outlet located radially inward, particularly in the center of the pump system.

[0006] The eccentric drive unit, i.e., the drive shaft having an eccentric portion, is located within the housing of a scroll vacuum pump on the side of the support away from the volume-changing portion relative to the housing, and is in practice often surrounded by a deformable sleeve, such as a bellows. This is used, on the one hand, to seal the drive unit away from the suction area, and on the other hand, as a rotation prevention device for the swivel portion, because without a rotation prevention device, the swivel portion can rotate around itself. To ensure this rotation prevention device, for example, the deformable sleeve may be connected to the support at a first end, while the second end of the deformable sleeve, opposite to the first end, may be screwed to the housing base within the housing by a plurality of fastening means.

[0007] Most known scroll vacuum pumps are designed for continuous operation. In this case, it is necessary to take into account the changes in the thermal load of the components of the scroll vacuum pump system, especially when the pump starts up. This is because these components are heated up, and it takes a certain amount of time for a stable temperature distribution to be established within the pump system. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] European Patent Application Publication No. 3153708 [Patent Document 2] European Patent Application Publication No. 3617511 [Patent Document 3] European Patent Application Publication No. 3647599 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, starting from the aforementioned known scroll vacuum pumps, the object of the present invention is to improve these scroll vacuum pumps. In particular, the object of the present invention is to enable high pumping performance of scroll vacuum pumps during continuous operation and / or improved cold-starting characteristics of such scroll vacuum pumps. [Means for solving the problem]

[0010] The problems of the present invention are solved by the configuration of the claims. In particular, the problems are solved by the scroll vacuum pump according to claim 1. Further developments of the scroll vacuum pump according to the present invention are evident from the dependent claims, specification and drawings.

[0011] According to one aspect of the present invention, the problem is solved by a scroll vacuum pump comprising a pump system including a fixed scroll member and a movable scroll member that interacts with the fixed scroll member to perform a pumping action, a drive shaft that rotates around a rotation axis during operation and has an eccentric portion for driving the movable scroll member, and an electric drive motor for the drive shaft, wherein the movable scroll member, together with the fixed scroll member, forms a circular annular portion and a spiral scroll portion that connects to the annular portion radially inward, and the annular portion and the scroll portion are respectively from the inlet end to the outlet end The scroll vacuum pump is provided, wherein the movable scroll member has a swivel support that interacts with a drive shaft, and the outlet end of the annular portion is connected to the inlet end of the scroll portion, and the movable scroll member has a swivel support that interacts with a drive shaft, and the fixed scroll member has a stator support, and the scroll portion is formed by a spiral scroll wall extending from the swivel support engaging with a spiral scroll groove located on the stator support, and further, the annular portion is formed by a circular annular wall extending from the swivel support engaging with a circular annular groove located on the stator support. The scroll vacuum pump according to the present invention is characterized in that, when the pump system is at a thermally low temperature, the minimum radial distance between the radially inner inner surface of the annular wall and the radially inner inner wall portion of the annular groove is smaller than the minimum radial distance between the radially outer outer surface of the annular wall and the radially outer outer wall portion of the annular groove.

[0012] The scroll vacuum pump according to the present invention represents a scroll vacuum pump having the pump system described above. The pump system has two scroll members, in this case one of which is fixedly positioned in the pump system, in other words, remains stationary relative to the other scroll vacuum pump during operation. The other scroll member, on the other hand, is movable. In particular, the movable scroll member is mechanically actuated to an eccentric portion of the drive shaft, so that this movable scroll member, driven by a drive motor, performs the aforementioned rotational or oscillating motion.

[0013] The pumping system of the scroll vacuum pump according to the present invention includes an annular portion and a scroll portion, in which case the scroll portion is located radially inward of the annular portion. Both the annular portion and the scroll portion extend from an inlet end to an outlet end, in which case the terms "inlet" and "outlet" are selected based on the pumping direction of the fluid to be pumped. The outlet end of the annular portion is connected to the inlet end of the scroll portion, so that an effective pumping section is obtained overall from the inlet end of the annular portion to the outlet end of the scroll portion. Preferably, the outlet end of the scroll portion is located radially in the center of the pumping system, thereby automatically positioning the inlet end of the scroll portion further radially outward than the outlet end of the scroll portion.

[0014] In both the annular and scroll portions, the aforementioned crescent-shaped volume is formed by wall elements that engage with grooves. The annular portion is provided with a circular annular wall, and the scroll portion is provided with a spiral scroll wall, both of which extend from the pivot support that interacts with the drive shaft, particularly the eccentric portion, as part of the movable scroll member. It should be noted that the annular wall usually does not form a complete 360° circle, but rather only a partial circle, for example, a wide range from 300° to 345°. On the other hand, the scroll wall can be mathematically described as an elongated line. In accordance with the form of the annular and scroll walls, the stator support of the fixed scroll member is provided with corresponding annular grooves and scroll grooves.

[0015] With the pump system assembled, the annular wall engages with the annular groove, and the scroll wall engages with the scroll groove, also engaging such that a crescent-shaped volume is formed between these members. The rotational motion of the movable scroll member, and consequently the annular wall in the annular groove and the scroll wall in the scroll groove, causes these volume to gradually move radially inward, thereby pumping the fluid to be pumped from the inlet end of the annular portion to its outlet end, then to the inlet end of the scroll portion, and through the scroll portion to its outlet end, preferably towards the radial center of the pump system.

[0016] The dimensional setting and, in particular, the arrangement of the annular walls and scroll walls relative to the annular groove or scroll groove are selected to achieve the best possible pump performance during operation, especially during continuous operation. This is achieved, in particular, by minimizing the minimum distance between each wall and the wall portion of the groove, i.e., between the scroll wall and each of the two wall portions of the scroll groove, and between the annular wall and each of the two wall portions of the annular groove. This ensures that a good seal is achieved at both extending ends of the properly formed crescent-shaped volume, thereby minimizing pump losses.

[0017] In this regard, it should be noted that the aforementioned minimum spacing resulting from the rotational motion of the movable scroll member relative to the fixed scroll member is not fixed in position, but moves from the entrance end to the exit end in both the scroll trajectory and the annular trajectory. Therefore, in the view of the present invention, “minimum spacing” represents the spacing between each wall and the wall portion of the groove, and its value is minimized by the appropriate relative positioning of the wall relative to the wall portion. This can usually be done without specifying a particular position, in which case the minimum spacing is expressed over the entire extension of each wall in the groove. Alternatively, the “minimum spacing” may be specified by specifying a position, such as “entrance end” or “exit end.” In this case, “minimum spacing” represents the minimum inferred value at that position, respectively.

[0018] As already mentioned, the pump system is thermally stable during continuous operation, and the components of the pump system are heated until this state is reached. This heating causes a change in the relative position of the scroll wall in the scroll groove and the annular wall in the annular groove. This change becomes larger as the radially outward position of each wall portion considered and as the temperature change becomes larger. The change in the radial position (dr) of each wall mainly follows the following equation. dr~α·r·dT Here, the material-dependent constant is α, the position of the radius is r, and the temperature change is dT.

[0019] It should be noted that this equation represents a simple case where the swivel support and stator support, and especially at least the scroll walls and annular walls, as well as the scroll grooves and annular grooves, are made from the same material. When the materials for these structural elements are varied, often exhibiting different expansion characteristics, the above equation becomes more complex to account for this situation.

[0020] According to the present invention, it is particularly advantageous that, in a thermally low state of the pump system, the minimum radial distance between the radially inner inner surface of the annular wall and the radially inner inner wall portion of the annular groove is smaller than the minimum radial distance between the radially outer outer surface of the annular wall and the radially outer outer wall portion of the annular groove. In the view of the present invention, a thermally low state is particularly the assembled or cold state of a scroll vacuum pump. In its thermally low state, the scroll vacuum pump is still in a non-operating state, and in particular, it has been in a long non-operating state, such as the previous one, where the components of the pump system have been completely cooled again. In other words, in the switched-off and cooled state of the scroll vacuum pump according to the present invention, the minimum gap that can be set between the annular wall and the corresponding wall portion of the annular groove in the annular portion varies depending on whether the annular wall forms a radially outer or radially inner definition of the gap. The minimum spacing is smaller when the annular wall is radially outward and larger when the annular wall forms a radially inward demarcation of the gap.

[0021] According to the above formula, the radial position of the annular wall changes until a certain operating temperature is reached, during which a radial displacement occurs, particularly radially outward. This radial position change may occur particularly relative to the annular groove, because the arrangement of the annular groove in the movable scroll member causes it to be further heated relative to the annular groove in the fixed scroll member. The difference set according to the present invention between the annular wall and the wall portion of the corresponding annular groove, radially inward or radially outward, makes it possible to compensate for the minimum gap that occurs on both sides of the annular wall during continuous operation. This makes it possible to adjust the minimum gap on both sides of the annular wall to be as small as possible overall, thereby achieving a good seal at the tapered end of the correspondingly formed crescent-shaped volume, and thereby minimizing pump losses.

[0022] According to one development, in the scroll vacuum pump according to the present invention, it can be envisaged that when the pump system is in a thermally low-temperature state, the minimum radial gap between the inner side surface of the scroll wall at the inlet end of the scroll portion and the inner wall of the scroll groove is smaller than the minimum radial gap between the inner side surface of the annular wall at the outlet end of the annular portion and the inner wall of the annular groove.

[0023] As already mentioned above, when the pump system and particularly the movable scroll member herein is heated, radial positional displacement of the scroll wall and the annular wall is expected, and according to the aforementioned formula, the more radially outward each wall portion is located, the more significant the displacement becomes. Starting from this, it is inferred that the minimum radial gap between the inner side surface of the scroll wall at the inlet end of the scroll portion and the inner wall of the scroll groove should be adjusted to be larger than the minimum radial gap between the inner side surface of the annular wall at the outlet end of the annular portion and the inner wall of the annular groove. However, contrary to expectations, it has been found that this leads or can lead to contact between the annular wall and the inner wall of the annular groove during cold start of the pump system, that is, at the start of operation. Such contact is also referred to as collision or abutment. The minimum gap between the inner side surface of the scroll wall and the inner wall of the radially inwardly arranged scroll groove, which is set in this embodiment and has a smaller value than the minimum gap between the annular wall and the inner wall of the radially inwardly arranged annular groove, can avoid so-called abutment of the annular wall against the inner wall of the annular groove. Overall, in this way, the cold performance of the scroll vacuum pump according to the present invention can be improved.

[0024] It should be noted here that in the foregoing embodiment, when the pump system is in a thermally low-temperature state, the minimum gap between the inner side surface of the scroll wall and the inner wall of the radially inwardly arranged scroll groove can preferably be optimized in accordance with the pump performance achievable in continuous operation. In other words, the radial position of the scroll wall is determined taking into account this setting criterion particularly related to the pump performance to be achieved, and based on this, the radial position of the annular wall is appropriately adapted.

[0025] Furthermore, the scroll vacuum pump according to the present invention may be characterized in that, in the thermally low-temperature state of the pump system, the minimum radial clearance between the inner side surface of the scroll wall in the scroll portion and the inner wall portion of the scroll groove increases from the inlet end toward the outlet end. According to the aforementioned formula, the expected change in the radial position of the scroll wall is greater particularly when the portion of the scroll wall is located further outward in the radial direction. Since the scroll wall extends spirally from the inlet end of the scroll portion arranged further outward in the radial direction further inward in the radial direction, preferably to the outlet end of the scroll portion positioned centrally in the radial direction, the scroll wall has different radii depending on the observed portion, whereby varying magnitudes of change in the respective radial positions of the scroll wall are expected on the other hand. In particular, the change is expected to decrease from the inlet end toward the outlet end. By means of the set increase in the minimum radial clearance between the inner side surface of the scroll wall in the scroll portion and the inner wall portion of the scroll groove from the inlet end toward the outlet end, this can preferably be compensated in continuous operation such that a constant minimum clearance is produced over the entire stretched portion of the scroll wall. As a result, pump losses can be particularly minimized.

[0026] In a preferred embodiment of the scroll vacuum pump according to the present invention, for example, the minimum radial clearance between the inner side surface of the scroll wall in the scroll portion and the inner wall portion of the scroll groove gradually increases from the inlet end toward the outlet end, and may preferably increase linearly.

[0027] In the scroll vacuum pump according to the present invention, it may also be intended that the movable scroll member, in conjunction with the fixed scroll member, forms at least one additional circular annular portion that continues to and is connected to the annular portion radially outward, the additional annular portion being formed by another circular annular wall extending from the inlet end to the outlet end and starting from the swivel support engaging with another circular annular groove positioned on the stator support. The main pumping effect of the scroll vacuum pump is provided by the scroll portion, in which case the additional annular portion provides support. Moreover, the annular portion requires very little effort to manufacture, because the elements of the annular portion, particularly the annular wall and / or annular groove, can be manufactured as machined parts, unlike the scroll wall and / or scroll groove, which require laborious milling. Therefore, by providing the additional annular portion, the pumping effect of the scroll vacuum pump according to the present invention, which includes it, can be improved without excessively increasing the labor required for manufacturing.

[0028] In a further embodiment of the scroll vacuum pump according to the present invention, the inlet and outlet ends of an annular portion and another annular portion are connected, respectively, so that the annular portion and the other annular portion are connected in parallel, or the outlet end of the other annular portion is connected to the inlet end of the annular portion, so that the annular portion and the other annular portion are connected in series. The parallel connection of the annular portions can increase the pumping product as a whole. On the other hand, the series connection can increase the compression that can be achieved by the entire pump system. Therefore, the scroll vacuum pump according to the present invention can be appropriately configured as required.

[0029] Note that if multiple other annular sections exist, it is possible to combine parallel and series connections of these individual annular sections.

[0030] Furthermore, the scroll vacuum pump according to the present invention may be configured such that, when the pump system is thermally cool, in another annular section, the minimum radial distance between the radially inner surface of another annular wall and the radially inner inner wall of another annular groove is smaller than the minimum radial distance between the radially outer surface of another annular wall and the radially outer outer wall of another annular groove. The annular wall of the other annular section is also heated at the start of operation, and as a result, the radial position of this annular wall is also displaced radially outward until continuous operation is achieved at a stable temperature. In this embodiment, in another annular section, the relative minimum distance between the annular wall and the inner or outer wall of the annular groove is formed in the same way as in the aforementioned annular section. All the advantages described above with respect to the configuration of the annular section can also be achieved with respect to the other annular section by corresponding configurations of the other annular section. In particular, minimizing pump losses can be achieved.

[0031] Furthermore, the scroll vacuum pump according to the present invention may be characterized in that, when the pump system is thermally cool, the minimum radial distance between the inner surface of an annular wall and the inner wall of an annular groove is the same as the minimum radial distance between the inner surface of another annular wall and the inner wall of another annular groove. As described above, in an annular portion arranged to continue radially from the scroll portion, the minimum distance between the annular wall and the inner wall of the annular groove can be selected to avoid the annular wall abutting against the inner wall of the annular groove. Therefore, the minimum distance adjusted for this annular portion is just enough to prevent this abutment. Thus, it may be advantageous to appropriately adjust the minimum distance between the inner surface of the annular wall and the inner wall of the annular groove in another annular portion, particularly to the same value. This avoids a cumbersome series of tests to determine the minimum distance to be adjusted for another annular portion to prevent abutment.

[0032] The scroll vacuum pump according to the present invention may be improved such that, when the pump system is at a thermally low temperature, the minimum radial distance between the outer surface of one annular wall and the outer wall portion of one annular groove is different from the minimum radial distance between the outer surface of another annular wall and the outer wall portion of another annular groove.

[0033] In the aforementioned embodiment of the scroll vacuum pump according to the present invention, the radially inward spacing between each of the inner surfaces of the plurality of annular walls and each of the inner walls of the plurality of annular grooves is formed to be the same. However, since the plurality of annular portions, i.e., at least one annular portion and another annular portion, are located at different radial positions and therefore have different radii, it may be advantageous to take into account the different changes in the radial position of each annular wall that can be expected according to the aforementioned formula during heating, thereby achieving, for example, the aforementioned compensation for the minimum spacing between each annular wall and the inner or outer wall of each annular groove. This can be achieved alternatively or additionally to the same minimum spacing on the radially inward surface of each annular wall by different configurations in which the minimum radial spacing between each annular wall and the outer wall of each annular groove is different, as proposed in this embodiment.

[0034] According to one advanced form of the scroll vacuum pump according to the present invention, it may be further intended that, in the thermally low state of the pump system, the minimum radial distance between the outer surface of an annular wall and the outer wall portion of an annular groove is smaller than the minimum radial distance between the outer surface of another annular wall and the outer wall portion of another annular groove. The other annular portion is located radially outward of the existing annular portion and therefore has a particularly larger radius. This results in a larger change in radius expected during cold starting until continuous operation is achieved, according to the above formula. This can be compensated for in the other annular portion by increasing the minimum distance radially outward of the annular wall, i.e., between the radially outward outer surface of the annular wall and the radially outward outer wall portion of the annular groove, thereby nevertheless, compensation for the minimum distance between the annular wall and the inner wall portion or outer wall portion of the annular groove and the outer wall portion is obtained radially inward and radially outward in the other annular portion.

[0035] Furthermore, according to the scroll vacuum pump of the present invention, it is possible to ensure that, when the pump system is thermally low, in an annular portion, the minimum radial distance between the inner surface of the annular wall and the inner wall portion of the annular groove between the inlet end and the outlet end is constant, and / or, when the pump system is thermally low, in another annular portion, the minimum radial distance between the inner surface of another annular wall and the inner wall portion of another annular groove between the inlet end and the outlet end is constant.

[0036] Each annular section, as a circular element, has a constant radius. Therefore, the aforementioned formula assumes that a constant change in radial position is expected across the entire annular section. This can be taken into account by the minimum distance between the inner surface of the annular wall and the corresponding inner wall of the annular groove, which is constant across the entire extended portion of each annular wall. This is because, as a result, if the change in radial position is the same across the entire annular wall, a constant value for each minimum distance will be obtained here as well.

[0037] Alternatively or additionally, the scroll vacuum pump according to the present invention may be configured such that, in a thermally low state of the pump system, the minimum radial distance between the outer surface of the annular wall and the outer wall portion of the annular groove is constant between the inlet end and the outlet end of the annular portion, and / or in a thermally low state of the pump system, the minimum radial distance between the outer surface of another annular wall and the outer wall portion of another annular groove is constant between the inlet end and the outlet end of another annular portion.

[0038] The considerations pointed out regarding the minimum radial spacing in the annular portion also apply to the minimum outer spacing, i.e., between the radially outer surface of each annular wall and the radially outer wall portion of the corresponding annular groove, and are equally applicable. For these radially outer minimum spacings, a constant minimum spacing can be achieved throughout the entire extended portion of each annular wall, and the same expected radial positional change throughout the entire annular wall, resulting in a constant value for each minimum spacing.

[0039] Furthermore, in the scroll vacuum pump according to the present invention, it may be intended that the radial wall thickness of the scroll wall and / or annular wall and / or other annular wall is constant. A constant wall thickness is particularly easy to produce mechanically. Moreover, annular walls and scroll walls having a constant radial wall thickness can also be manufactured particularly easily. Furthermore, such a constant radial wall thickness is advantageous in particular for annular walls that have a constant minimum distance from each inner or outer wall portion of the corresponding annular groove, especially at low thermal temperatures. This is because changes in the radial position of the annular wall are not affected or are hardly affected when heated to the continuous operating temperature. For scroll walls, please refer to the embodiments described above. In the embodiments described above, the minimum radial distance between the inner surface of the scroll wall and the inner wall portion of the scroll groove increases from the inlet end of the scroll portion to the outlet end of the scroll portion. In this configuration, the radial positional changes expected to differ along the extended portion of the scroll wall are already compensated for by this minimally spaced change, so a mechanically simple configuration with a constant radial wall thickness can be selected for the scroll wall as well.

[0040] In a further embodiment, the scroll vacuum pump according to the present invention may be characterized in that at least one coating is provided on the inner and / or outer surfaces of the scroll wall and / or annular wall and / or another annular wall. The coating may have many different properties. For example, the coating can reduce friction between parts, such as friction between the scroll wall and the scroll groove attached thereto. The surface hardness of the parts can also be altered, in particular increased, by the appropriate coating. Overall, the coating can enhance the surface's resistance to reactive elements, thereby enabling the use of the scroll vacuum pump according to the present invention with, for example, a reactive fluid to be pumped.

[0041] The coating may be formed in a single layer or multiple layers. In other words, the entire coating may consist of multiple individual coatings. In a multilayer coating, each layer may consist of the same coating material. Alternatively, at least two of the coating layers used may be made of different materials.

[0042] According to the first evolution, the scroll vacuum pump according to the present invention may further be intended to have a constant thickness of coating along the extended portion surrounding the scroll wall and / or annular wall and / or another annular wall. A coating of constant thickness means a type of coating that is particularly easy to manufacture. The coating can be applied, for example, by uniformly spraying the coating onto the inner and / or outer surfaces of the scroll wall or annular wall.

[0043] Alternatively or additionally, the scroll vacuum pump according to the present invention may further be intended to have a variable thickness of coating along the circumferential extended portion of the scroll wall and / or annular wall and / or another annular wall. As already mentioned several times, it may be reasonable and / or necessary to set an inner or outer minimum spacing between the scroll wall and the corresponding scroll groove wall, or between the annular wall and the corresponding annular groove wall. In this case, a coating of variable thickness offers two particular possibilities for influencing such a minimum spacing. On the one hand, the variable thickness of the coating can be used to compensate for inaccuracies that occur, for example, during the mechanical manufacturing of components, particularly, for example, the scroll wall or annular wall, when adjusting the minimum spacing. On the other hand, the variable thickness of the coating may be used to make this adjustment of the minimum spacing for the first time. Various methods may be used to create such a variable thickness. Without limitation, for example, areas of the scroll wall where a thicker coating is desired may be coated multiple times, or the feed rate of the spray head over these areas may be reduced, for example, when spray coating.

[0044] The present invention will be described below with reference to the drawings. [Brief explanation of the drawing]

[0045] [Figure 1]An embodiment of the scroll vacuum pump according to the present invention is shown in a cross-sectional view. [Figure 2] A cross-sectional view shows the pump system of the scroll vacuum pump according to the present invention. [Figure 3] A schematic diagram is shown to illustrate the minimum spacing between the scroll section and the two ring sections. [Modes for carrying out the invention]

[0046] Figures 1 and 2 schematically show the structure of the scroll vacuum pump 10 according to the present invention. Figure 1 shows an overall cross-sectional view of the scroll vacuum pump 10, and Figure 2 shows a cross-sectional view of the pump system 20 of the scroll vacuum pump 10 according to the present invention shown in Figure 1. Hereinafter, Figures 1 and 2 will be described together, and different figures will be examined separately.

[0047] The scroll vacuum pump 10 depicted in Figure 1, like substantially all scroll vacuum pumps 10, includes a pump system 20 having a fixed scroll member 30 and a movable scroll member 40, the fixed scroll member 30 and the movable scroll member 40 interacting to produce a pumping action during operation. Furthermore, the scroll vacuum pump 10 includes a drive shaft 22 that rotates around a rotation axis during operation, having an eccentric portion 24 that drives the movable scroll member 40. In addition, the depicted scroll vacuum pump 10 is provided with an electric drive motor 26, which is used to rotate the drive shaft 22 around the rotation axis.

[0048] At the front end of the pump housing 28 of the scroll vacuum pump 10 is a pump system 20 having a fixed scroll member 30 and a movable scroll member 40. The fixed scroll member 30, also called the scroll housing, is screwed to the front end of the pump housing 28 at its end face and is surrounded by a hood similarly attached to the pump housing 28.

[0049] The movable scroll member 40 includes a swivel support 42, and the fixed scroll member 30 includes a stator support 32. In the illustrated embodiment of the scroll vacuum pump 10 according to the present invention, a scroll wall 110, an annular wall 210 and another annular wall 310 originate from the swivel support 42, which engage with corresponding grooves located in the stator support 32, in particular a scroll groove 120, an annular groove 220 and another annular groove 320.

[0050] This forms a central scroll portion 100 in the radial direction and two annular portions 200 and 300 that extend radially outward, as shown in Figure 2. The two annular portions 200 and 300 are connected in parallel by connections between the entrance ends 202 and 302 of the annular portions 200 and 300 and the exit ends 204 and 304 of the annular portions 200 and 300. Furthermore, the exit ends 204 and 304 of the annular portions are connected to the entrance end 102 of the scroll portion 100 (not shown).

[0051] Crescent-shaped volumes or pockets are formed between the respective walls 110, 210, 310 and the wall portions 122, 124, 222, 224, 322, 324 (see Figure 3) of the grooves 120, 220, 320. The oscillating motion of the swivel section support 42 relative to the stator support 32, caused by the eccentric portion 24, generates movement of these volumes or pockets in the annular section 200 and the scroll section 100. As a result, the fluid to be pumped, usually a gas, is pumped from the inlet ends 102, 300 of the annular sections 200, 300 to the outlet ends 204, 304, then to the inlet end 102 of the scroll section 100, and finally to the outlet end 104 of the scroll section 100.

[0052] Furthermore, the scroll wall 110, the annular wall 210 and / or another annular wall 310 may have a coating 50, particularly on their respective inner sides 114, 214, 314 or outer sides 116, 216, 316 (see Figure 3). Such a coating 50 can reduce friction, for example, within the pump system 20, and / or increase the resistance of the 110, 210, 310 in particular to reactive or aggressive gases. The coating 50 may consist of one or more materials in a single or multilayer structure. The thickness of the coating may be uniform or variable, in which case the latter variable wall thickness may be considered for adjustment of the minimum spacing 130, 132, 134, 136, 230, 323, 330, 332 (see Figure 3).

[0053] Figure 3 shows the scroll vacuum pump 10 shown in Figures 1 and 2, with the scroll section 100 (Figure A), the annular section 200 (Figure B), and another annular section 300 (Figure C) along the extension between the inlet ends 102, 202, and 302 (on the right in the drawing, respectively) and the outlet ends 104, 204, and 304 (on the left in the drawing). The selected figures show the minimum possible spacings 130, 132, 134, 136, 230, 232, 330, and 323 that can be occupied when the swivel section support 42 is positioned correspondingly relative to the stator support 32 (see Figures 1 and 2), respectively, along the extension. Therefore, it does not show, for example, a developed view of a specific positioning of the annular wall 210 within the annular groove 220. This is because these figures show the change in the spacing of the annular wall 210 relative to the walls 222 and 224 of the annular groove 220, which in turn forms the aforementioned pocket.

[0054] The intervals 130, 132, 134, 136, 230, 232, 330, and 332 shown in the diagram represent the state of the scroll vacuum pump 10 at a thermally low temperature. In other words, there are values ​​provided at the start of a cold start of the scroll vacuum pump 10. Due to the heating that occurs during operation, each wall 110, 210, and 310 is displaced radially outward as it moves away from the center.

[0055] From Figure A, it can be clearly seen that in the scroll portion 100, the minimum radially inward spacing 130 at the inlet end 102 is smaller than the minimum radially inward spacing 134 at the outlet end 102. Both spacings 130 and 134 are defined between the inner surface 114 of the scroll wall 110 and the radially inward inner wall portion 122 of the scroll groove 120. Conversely, at the same time, the minimum radially outward spacings 132 and 136, determined between the outer surface 116 of the scroll wall 110 and the radially outward outer wall portion 124 of the scroll groove 120, decrease from the inlet end 102 to the outlet end 104. Both changes take into account that the outlet end 104 of the scroll portion 100 is preferably located in the center of the pump system 20, and the inlet end 102 is correspondingly located further outward in the radial direction (see Figure 2). During continuous operation of the scroll vacuum pump 10, i.e., at a constant temperature after the temperature rise, preferably a constant minimum inner spacing 130, 134 and minimum outer spacing 132, 136 can be obtained.

[0056] Figures B and C show the situation for the annular sections 200 and 300, respectively. Unlike the scroll section 100 (Figure A), the annular walls 210 and 310 are located on a nearly constant radius. For this reason, the minimum inner spacing values ​​230 and 330 are determined between the inner sides 214 and 314 of the annular walls 210 and 310 and the radially inward inner wall portions 222 and 322 of the annular grooves 220 and 320, respectively, and are the same at the inlet ends 202 and 302 and the outlet ends 222 and 322. The same applies to the minimum outer spacing values ​​232 and 332. These values, too, are determined between the outer sides 216 and 316 of the annular walls 210 and 310 and the radially outward outer wall portions 224 and 324 of the annular grooves 220 and 320, respectively, as is the case with the scroll section.

[0057] Preferably, the minimum radially inward spacing 230 (see Figure 2) of the annular portion 200 located radially inward and the minimum radially inward spacing 330 of another annular portion 300 may be the same value.

[0058] In particular, in this case, it may be intended that the minimum radially inward spacing 230 of the radially inward annular portion 200 at the exit end 204 of the radially inward annular portion 200 is greater than the minimum radially inward spacing 130 of the scroll portion 100.

[0059] To take into account the radial position of another annular portion 300 located outside the radially inward annular portion 200, the minimum radially outward spacing 232 of the annular portion 200 may be smaller than the minimum radially outward spacing 332 of the other annular portion 300.

[0060] In summary, the minimum spacing values ​​of 130, 132, 134, 136, 230, 232, 330, and 332 are selected so that these spacings compensate for the relative changes in the temperature rise of the respective walls 110, 210, and 310. At the same time, these values ​​should not be selected so as to hinder the starting of the walls 110, 210, and 310 in the corresponding grooves 120, 220, and 320 during cold starts. [Explanation of Symbols]

[0061] 10 Scroll Vacuum Pump 20 Pump System 22 Drive shaft 24 Eccentric part 26 Drive motor 28 Pump Housing 30 Fixed scroll member 32 Stator support 40 Movable scroll member 42 Swivel section support 50 Covering 100 Scroll section 102 Inlet end 104 Outlet end 110 Scroll Wall 112 wall thickness 114 Medial side 116 Outer side 120 scroll grooves 122 Inner wall 124 Outer wall 130 Minimum radially inward spacing (entrance end) 132 Minimum radially outward spacing (entrance end) 134 Minimum radially inward spacing (exit end) 136 Minimum radially outward spacing (exit end) 200 Circular section 202 Inlet end 204 Outlet end 210 Circular Wall 212 wall thickness 214 Medial side 216 Outer side 220 Circular groove 222 Inner wall 224 Outer wall 230 Minimum radially inward spacing 232 Minimum radially outer spacing 300 Another annular section 302 Inlet end 304 Outlet end 310 Another ring wall 312 wall thickness 314 Medial side 316 Outer side 320 Another annular groove 322 Inner wall 324 Outer wall 330 Minimum radially inward spacing 332 Minimum radially outer spacing

Claims

1. A scroll vacuum pump (10), - A pump system (20) including a fixed scroll member (30) and a movable scroll member (40) that interacts with the fixed scroll member (30) to perform a pumping action, - A drive shaft (22) that rotates around the axis of rotation during operation, having an eccentric portion (24) that drives a movable scroll member (40), - Includes an electric drive motor (24) for the drive shaft (22), The movable scroll member (40), in conjunction with the fixed scroll member (30), forms a circular annular portion (200) and a spiral scroll portion (100) that connects to the annular portion (200) radially inward. The annular portion (200) and the scroll portion (100) extend from the entrance end (202, 102) to the exit end (204, 104), respectively, and the exit end (204) of the annular portion (200) is connected to the entrance end (102) of the scroll portion (100). The movable scroll member (40) has a pivot support (42) that interacts with the drive shaft (22), and the fixed scroll member (30) has a stator support (32), and the scroll portion (100) is formed by a spiral scroll wall (110) extending from the pivot support (42) engaging with a spiral scroll groove (120) located on the stator support (32), and further, the annular portion (200) is formed by a circular annular wall (210) extending from the pivot support (42) engaging with a circular annular groove (220) located on the stator support (32), A scroll vacuum pump (10) in which, when the pump system (20) is at a thermally low temperature, the minimum radial distance (230) between the radially inner inner surface (214) of the annular wall (210) and the radially inner inner wall portion (222) of the annular groove (220) is smaller than the minimum radial distance (232) between the radially outer outer surface (214) of the annular wall (210) and the radially outer outer wall portion (224) of the annular groove (220).

2. The scroll vacuum pump (10) according to claim 1, wherein, when the pump system (20) is in a thermally low state, the minimum radial distance (130) between the inner surface (114) of the scroll wall (110) and the inner wall portion (122) of the scroll groove (120) at the inlet end (102) of the scroll portion (100) is smaller than the minimum radial distance (200) between the inner surface (214) of the annular wall (210) and the inner wall portion (222) of the annular groove (220) at the outlet end (204) of the annular portion (200).

3. A scroll vacuum pump (10) according to claim 1 or 2, wherein, when the pump system (20) is in a thermally low state, the minimum radial distance (130, 134) between the inner side surface (114) of the scroll wall (110) and the inner wall portion (122) of the scroll groove (120) in the scroll portion (100) increases from the inlet end (102) to the outlet end (104).

4. A scroll vacuum pump (10) according to any one of claims 1 to 3, wherein the movable scroll member (40), together with the fixed scroll member (30), forms at least one other circular annular portion (300) connected to the annular portion (200) radially outward, the other annular portion (300) is formed by another circular annular wall (310) extending from an inlet end (302) to an outlet end (304) and starting from and extending from the swivel support (42) engaging with another circular annular groove (42) located in the stator support (32).

5. The entrance ends (202, 302) and exit ends (204, 304) of the annular portion (200) and the other annular portion (300) are connected, respectively, so that the annular portion (200) and the other annular portion (300) are connected in parallel, or The exit end (304) of another annular section (300) and the inlet end (202) of an annular section (200) are connected, thereby connecting the annular section (200) and the other annular section (300) in series. The scroll vacuum pump (10) according to claim 4.

6. A scroll vacuum pump (10) according to claim 4 or 5, wherein, in a thermally low state of the pump system (20), in another annular portion (300), the minimum radial distance (330) between the radially inner side surface (314) of another annular wall (310) and the radially inner inner wall portion (322) of another annular groove (320) is smaller than the minimum radial distance (332) between the radially outer side surface (314) of another annular wall (310) and the radially outer outer wall portion (324) of another annular groove (320).

7. A scroll vacuum pump (10) according to any one of claims 4 to 6, wherein, in a thermally low state of the pump system (20), the minimum radial distance (230) between the inner surface (214) of an annular wall (210) and the inner wall portion (222) of an annular groove (320) is the same as the minimum radial distance (330) between the inner surface (314) of another annular wall (310) and the inner wall portion (322) of another annular groove (320).

8. A scroll vacuum pump (10) according to any one of claims 4 to 6, wherein, in a thermally low state of the pump system (20), the minimum radial distance (232) between the outer surface (214) of an annular wall (210) and the outer wall portion (224) of an annular groove (220) is different from the minimum radial distance (332) between the outer surface (314) of another annular wall (310) and the outer wall portion (324) of another annular groove (320).

9. The scroll vacuum pump (10) according to claim 8, wherein, when the pump system (20) is at a thermally low temperature, the minimum radial distance (232) between the outer surface (214) of an annular wall (210) and the outer wall portion (224) of an annular groove (220) is smaller than the minimum radial distance (332) between the outer surface (314) of another annular wall (310) and the outer wall portion (324) of another annular groove (320).

10. In the thermally low state of the pump system (20), in the annular portion (200), the minimum radial distance (230) between the inner side surface (214) of the annular wall (210) and the inner wall portion (222) of the annular groove (220) between the inlet end (202) and the outer end (204) is constant, and / or In the thermally low state of the pump system (20), in another annular portion (300), the minimum radial distance (330) between the inner side surface (314) of another annular wall (310) and the inner wall portion (322) of another annular groove (320) is constant between the inlet end (302) and the outer end (304). A scroll vacuum pump (10) according to any one of claims 1 to 9.

11. In the thermally low state of the pump system (20), in the annular portion (200), the minimum radial distance (232) between the outer surface (214) of the annular wall (210) and the outer wall portion (224) of the annular groove (220) between the inlet end (202) and the outer end (204) is constant, and / or In the thermally low state of the pump system (20), in another annular portion (300), the minimum radial distance (332) between the outer side surface (314) of another annular wall (310) and the outer wall portion (324) of another annular groove (320) is constant between the inlet end (302) and the outer end (304). A scroll vacuum pump (10) according to any one of claims 1 to 10.

12. The scroll vacuum pump (10) according to any one of claims 1 to 11, wherein the radial wall thicknesses (112, 212, 312) of the scroll wall (110) and / or the annular wall (210) and / or another annular wall (310) are constant.

13. A scroll vacuum pump (10) according to any one of claims 1 to 12, wherein at least one coating (50) is provided on the inner surfaces (114, 214, 314) and / or outer surfaces (114, 214, 314) of the scroll wall (110) and / or the annular wall (210) and / or another annular wall (310).

14. The scroll vacuum pump (10) according to claim 13, wherein the thickness of the coating (50) is constant along the circumferential extended portion of the scroll wall (110) and / or the annular wall (210) and / or another annular wall (310).

15. The scroll vacuum pump (10) according to claim 13 or 14, wherein the thickness of the coating (50) is variable along the circumferential extended portion of the scroll wall (110) and / or the annular wall (210) and / or another annular wall (310).

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