Scroll vacuum pump and method for producing a scroll vacuum pump

Abstract

To provide a scroll vacuum pump and a method for manufacturing the scroll vacuum pump capable of manufacturing a simple, quick and inexpensive spiral element.SOLUTION: The movable spiral element includes a spiral structure having a spiral wall 69, a spiral groove defined by the spiral wall, and a spiral base constituting a bottom of the spiral groove, and a carrier for the spiral structure cooperating with the eccentric portion of the drive shaft, and the fixed spiral element includes a spiral structure having a spiral wall 49 and a spiral base, and a carrier for the spiral structure. One spiral wall has a reduced thickness that is less than a thickness of a portion upstream of the free end portion that transitions into the free end portion of the spiral wall. One spiral wall has a free end portion with a recess relative to a portion upstream of the free end portion that transitions radially outward and / or radially inward into the free end portion of the spiral wall.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a scroll vacuum pump having a pump system comprising a fixed spiral element and a movable spiral element cooperating with the fixed spiral element in a pumping action, a drive shaft having an eccentric portion for driving the movable spiral element, which rotates about an axis of rotation during operation, and an electric drive motor for the drive shaft, wherein the movable spiral element comprises a spiral structure having a spiral wall, a spiral groove defined by the spiral wall, and a spiral base constituting the bottom of the spiral groove, and a carrier for the spiral structure cooperating with the eccentric portion of the drive shaft, and the fixed spiral element comprises a spiral structure having a spiral wall and a spiral base, and a carrier for the spiral structure.

[0002] Additionally, the present invention relates to a method for manufacturing such a scroll vacuum pump. [Background technology]

[0003] Scroll vacuum pumps are known in principle, for example from EP-A-3153708, EP-A-3617511, EP-A-3647599, EP-A-4174285 and EP-A-4253720.

[0004] A scroll pump is a positive displacement pump that compresses against atmospheric pressure, particularly as a compressor. A scroll vacuum pump can be used to create a vacuum in a recipient connected to the gas inlet of the scroll vacuum pump.

[0005] Scroll vacuum pumps are also called spiral vacuum pumps or spiral conveying devices. The pumping principle underlying scroll vacuum pumps is basically known from the prior art and will therefore only be briefly explained below.

[0006] Typically, the pumping system of a scroll vacuum pump has two spiral cylinders, nested or inserted into each other, e.g., Archimedes', also simply called spirals or spiral elements. Each spiral cylinder has at least one spiral wall, in particular having a plate-like carrier provided on the end face of the spiral wall, and the outer turns of the spiral cylinder, e.g., the outermost two or three turns of the spiral cylinder, may each be constituted by wall sections spaced at regular intervals in the circumferential direction from the center of the spiral. Even if these wall sections do not strictly constitute spiral sections but circular sections, in the context of the present disclosure, these wall sections are included in the spiral and are called spiral turns.

[0007] The spiral cylinders are inserted into each other so that they partially enclose a crescent- or sickle-shaped space (transport chamber). One of the spirals is stationary or fixedly arranged in the pump housing, while the other spiral, together with its carrier, can move on a circular path via an eccentric part of the drive shaft; therefore, these spirals, together with their carrier, are also called orbiters. This moving spiral element therefore performs a so-called centrosymmetric oscillation, also called "orbiting" or "oscillating." The crescent-shaped space (transport chamber) defined between the spiral cylinders moves increasingly inward during the orbiting of the moving spiral element within the spiral. As a result, the process gas to be pumped is transported by the moving space from a gas inlet located radially outside the pump system to a gas outlet located radially inward, particularly at the center of the spiral of the pump system.

[0008] The manufacture of spiral elements for scroll vacuum pumps requires a great deal of effort, especially since the spiral wall must be manufactured with extremely high precision. Predetermined manufacturing tolerances must not be exceeded, since even slight dimensional deviations can cause so-called gap bridging during operation of the scroll vacuum pump, which can result in wear and noise. Elastic deformation of the spiral wall at its free end portion has been found to be one of the causes of insufficient dimensional precision. When the spiral wall is manufactured by machining, for example, when a rotating end mill presses against the radially inward or outward side of the spiral wall to be manufactured during machining, the spiral wall is deflected due to its elastic deformation capacity. This results in less material being removed from the wall side than in the case of a highly rigid spiral wall that would otherwise be deflected only slightly or not at all under the same conditions. When the machining tool is removed, the spiral wall springs back to its original position. Due to the smaller material removal, it is possible that the specified manufacturing tolerances are not observed.

[0009] These springback effects are particularly pronounced at the free end portions of the spiral wall because the spiral wall has a lower stiffness than the wall portion upstream of the free end portion. These springback effects can seriously affect dimensional accuracy, and machined spiral walls have been found to spring back at their free end portions beyond their respective manufacturing tolerances.

[0010] These springback effects are therefore problematic because they complicate the manufacturing process during mass production of spiral elements. In practice, the dimensional accuracy of each individual spiral element is automatically checked immediately after its production, for example, by a coordinate measuring machine. Based on the test measurements, the machine tool settings are corrected as necessary to adapt the contour expected from machining to a target contour for the next spiral element to be manufactured, within the respective manufacturing tolerances. The compensation algorithms used in practice cannot take the mentioned springback effects into account, and these effects disrupt the interpretation of the compensation measurements. As a result, rapid automatic compensation adjustments of the machining machine from spiral element to spiral element are not possible. Instead, each operator must manually intervene in the evaluation of the compensation measurements, for example, because parts of the workpiece affected by the springback effect, especially the free end portion of the spiral wall, are ignored or otherwise taken into account when evaluating the compensation measurements.

[0011] This makes the manufacturing process significantly longer in duration and therefore significantly more expensive. [Prior art documents] [Patent documents]

[0012] [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 [Patent Document 4] European Patent Application Publication No. 4174285 [Patent Document 5] European Patent Application Publication No. 4253720 Summary of the Invention [Problem to be solved by the invention]

[0013] The object of the present invention is to provide a scroll vacuum pump and a method for manufacturing a scroll vacuum pump which allows for a simple, fast and inexpensive production of scroll vacuum pump components, in particular spiral elements, with high dimensional accuracy, and in particular should allow for fast and automatic checking of the dimensional accuracy and, if necessary, correction of the settings of the machine tool used for processing. [Means for solving the problem]

[0014] This problem is solved by the features of the independent claims.

[0015] The scroll vacuum pump according to the invention as defined in independent claim 1 is particularly characterized in that at least one spiral wall has a reduced thickness in its free end portion which is smaller than the thickness of the portion of the spiral wall upstream of the transition to the free end portion.

[0016] The scroll vacuum pump according to the invention as defined in independent claim 2 is characterized in that at least one spiral wall has a free end portion which is radially outwardly and / or radially inwardly recessed relative to the upstream part of the free end portion that transitions into the free end portion of the spiral wall.

[0017] Both of these aspects of the invention are based on the idea of ​​manufacturing the respective free end portions of the radially inner and / or radially outer spiral wall in such a way that springback effects no longer cause parts of the free end portions to fall outside the respective predetermined tolerances. For this purpose, the free end portions are provided with a reduced thickness and / or recess during manufacturing, i.e., more material is removed from the free end portions than would be required in a stiff free end portion. It has been found that the measures according to the invention avoid the disadvantages mentioned at the outset, but do not impair the performance of the scroll vacuum pump.

[0018] The thickness of the free end portion does not necessarily have to be reduced, as contemplated in the first aspect of the invention. The free end portion may, according to the second aspect of the invention, be provided with a recess, either radially inward or radially outward, which does not reduce the thickness of the entire free end portion, even if it has a radial extension on the opposite side, but which nevertheless ensures that the free end portion on the side in question remains within the respective tolerances after processing, despite elastic deflection during processing.

[0019] Thus, non-compliance with specified tolerances due to springback effects is avoided by the present invention, which has the advantage that the results of test measurements, obtained, for example, by an automatic coordinate measuring machine, can be better automatically interpreted and, if necessary, substituted into the correction settings of the respective processing machine. Manual intervention by an operator in this automatic optimization process is no longer necessary, which simplifies, accelerates, and makes the manufacturing process overall more economical. A further advantage is that greater tolerances can be set for machining due to reduced thickness or recess, i.e., greater material removal, which fundamentally simplifies manufacturing.

[0020] Advantageous further developments of the invention are also described in the dependent claims, the following description and the drawings.

[0021] According to some embodiments, it may be envisaged that each free end portion of each spiral wall has a reduced thickness or recess.

[0022] It may further be contemplated that the reduced thickness of the free end portion is smaller than the thickness of the upstream portion over the entire wall height, and / or that the recess extends over the entire wall height of the free end portion.

[0023] In particular, it may be provided that the reduced thickness of the free end portion is constant over the entire wall height and / or that the concavity is constant over the entire wall height of the free end portion.

[0024] However, this is not necessary. The stiffness of the free end portion is higher at the spiral base than in the region of the tip of the spiral wall. Thus, according to some embodiments, it can be envisaged that the reduced thickness of the free end portion decreases continuously from the spiral base to the tip of the spiral wall, in particular that at the spiral base the free end portion and the upstream portion of the spiral wall have the same thickness, or that the recess of the free end portion decreases continuously from the tip of the spiral wall to the spiral base, in particular that at the spiral base the recess is equal to zero.

[0025] According to some developments of the invention, it can be provided that the free end portion has a recess relative to the upstream portion both radially inward and radially outward. Alternatively, according to some embodiments, it can be provided that the free end portion has a recess relative to the upstream portion only radially inward.

[0026] Some developments provide for the spiral wall to be produced by machining with a machine tool, which machine tool has a rotary tool, in particular a milling tool, which during machining is pressed against the radial inside or the radial outside of the spiral wall to be produced. In particular, it is provided for the tool to be guided during machining on a path that sets a reduced thickness and / or a recess in the free end portion of the spiral wall.

[0027] It may be contemplated that a target contour of the spiral wall is set in at least one plane extending perpendicular to the rotation axis of the drive shaft, and the path of the tool is set so that the free end portion of the spiral wall, which is deflected by the tool during machining and springs back after machining, remains within the target contour.

[0028] The target contour refers in particular to the plane where the tip of the spiral wall is located, since in this region the deflection of the spiral wall during machining is greatest.

[0029] It is contemplated that, according to some embodiments, the movable spiral element and the fixed spiral element are each made from aluminum or a material that includes aluminum.

[0030] It may further be provided that the reduced thickness of the free end portion is 85% to 89%, in particular 92% to 95%, of the thickness of the upstream portion, or that the reduced thickness of the free end portion is 1 / 10 mm to 3 / 10 mm smaller than the thickness of the upstream portion. Alternatively or additionally, it may be provided that the recess of the free end portion is 0.5 / 10 mm to 2 / 10 mm.

[0031] For example, the free end portion having a constant thickness can have a recess of 1 / 10 mm on both sides, resulting in an overall thickness reduction of 2 / 10 mm. For example, the thickness of the upstream portion can be in the range of 3.5-3.7 mm, so that the reduced thickness of the free end portion is in the range of 3.3-3.5 mm, which corresponds to about 94% of the thickness of the upstream portion.

[0032] According to some embodiments, it may be provided that the length of the free end portion measured in the extension direction of the spiral wall is in the range of 3 mm to 10 mm.

[0033] In the method according to the invention for manufacturing the scroll vacuum pump disclosed herein or for manufacturing a spiral element for a scroll vacuum pump disclosed herein, it is envisaged that the spiral wall is manufactured by machining with a machine tool, which machine tool has a rotary tool, in particular a milling tool, which during machining is pressed against the radial inside or the radial outside of the spiral wall to be manufactured.

[0034] The milling tool is in particular an end mill, for example a cylindrical milling cutter or a shell end mill.

[0035] Furthermore, it can be provided that the tool is guided during machining on a path that sets a reduced thickness and / or a recess in the free end portion of the spiral wall.

[0036] It may further be provided that a target contour of the spiral wall is set in at least one plane extending perpendicular to the rotation axis of the drive shaft, and that the path along which the tool is guided during machining is set so that the free end portion of the spiral wall, which is deflected by the tool during machining and springs back after machining, remains within the target contour.

[0037] In particular, it is intended that the path is set depending on the target contour and the respective situation, which in particular relates to the mechanical properties of the spiral wall to be produced, the force with which the tool is pressed against the inside or outside of the spiral wall, and, if necessary, other parameters of importance for material removal by the machine tool. This results in a potential measure of the error caused by springback of the spiral wall, i.e., a potential deviation from the respectively set tolerance, so that the tool path can be set accordingly in order to sufficiently remove material from the spiral wall to be produced, so that springback does not actually cause a deviation from the tolerance.

[0038] Furthermore, it may be provided that different dimensional tolerances are set for the reduced thickness of the free end portion and / or the recess in the free end portion and for the thickness of the upstream part of the free end portion, in particular the dimensional tolerances may be + / - 1 / 10 mm, in particular + / - 1 / 100 mm to + / - 6 / 100 mm, respectively.

[0039] However, such dimensional tolerances are not mandatory, i.e. other dimensional tolerances can be specified, i.e. the respective machine tools can be operated with other cutting data.

[0040] The invention will now be described, by way of example only, with reference to the drawings, in which: [Brief explanation of the drawings]

[0041] [Figure 1] An example of a conventional scroll vacuum pump is shown below to explain the basic structure of such a scroll vacuum pump. [Figure 2] Diagram of a conventional moving spiral element of a scroll vacuum pump according to Fig. 1 to illustrate the structure of such a spiral element, also called an orbiter [Figure 3] Diagram of a conventional moving spiral element of a scroll vacuum pump according to Fig. 1 to illustrate the structure of such a spiral element, also called an orbiter [Figure 4] Schematic diagram to explain the springback problem at the free end of the spiral wall [Figure 5] FIG. 4 is a diagram illustrating the springback effect. [Figure 6] 1 is a partial view of a movable spiral element according to one embodiment of the present invention; [Figure 7] An enlarged view of the free end portion of the spiral wall of the spiral element of FIG. [Figure 8] 1 is a schematic diagram illustrating the inventive manufacture of a spiral wall formed in accordance with the present invention; [Figure 9] 1 is a schematic diagram illustrating the inventive manufacture of a spiral wall formed in accordance with the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0042] Figure 1 shows a conventional scroll vacuum pump having the basic structure described below. The structure and function of such scroll vacuum pumps are known to those skilled in the art. This conventional scroll vacuum pump can be further developed according to the present invention, as will be explained with reference to Figures 6 to 9.

[0043] The scroll vacuum pump according to Figure 1 comprises a pumping system having a fixed spiral element 11 and a moving spiral element 13 which cooperate in a pumping manner during operation. The scroll vacuum pump further comprises a drive shaft 17 having an eccentric portion 19 for driving the moving spiral element 13, which rotates about an axis of rotation 15 during operation. The scroll vacuum pump further comprises an electric drive motor 21, 23 which is used to rotate the drive shaft 17 about the axis of rotation 15. The electric drive motor comprises a radially inner motor rotor 21, also called a runner, and a radially outer motor stator 23.

[0044] The drive shaft 17 is rotatably supported in the pump housing 41 at two axially spaced bearing locations 25, 27. The front bearing location 25 is constituted by a front rolling bearing configured as a fixed bearing, while the rear bearing location 27 is constituted by a rear rolling bearing configured as a floating bearing. To support the drive shaft 17, the pump housing 41 is provided with a sleeve-like portion, hereinafter also referred to as bearing sleeve 115. The two rolling bearings 25, 27 are thus located radially between the drive shaft 17 and the bearing sleeve 115.

[0045] Both bearing locations 25, 27 are located on the side of the drive motors 21, 23 facing the eccentric portion 19 of the drive shaft 17. Therefore, all bearing locations 25, 27 are located in front of the drive motors 21, 23 within the pump housing 41. The bearing locations 25, 27 are located in the atmospheric region of the pump, i.e., not in the region where a vacuum prevails during pump operation. The eccentric portion 19 is integrally connected to the front end of the drive shaft 17, and the drive motors 21, 23 are located at the rear end of the drive shaft 17. This structure allows the drive motors 21, 23 to be attached to the rear end of the drive shaft 17. This simplifies assembly and replacement of the drive motors 21, 23 or their components.

[0046] The balancing concept for balancing the rotating system, in particular comprising the drive shaft 17 and the moving spiral element 13, comprises a front balance weight 29 and a rear balance weight 31 attached to the drive shaft 17. The front balance weight 29 is arranged in the region of the front end of the drive shaft 17 and the eccentric part 19. The rear balance weight 31 is located in front of the bearing point 27 and thus in front of the drive motor.

[0047] In variations of this basic design, other balancing concepts are also possible: for example, a rear balance weight or an additional balance weight can be arranged at the rear end of the drive shaft in the area of ​​the drive motor.

[0048] Furthermore, a pressure element 87 is provided which is attached to the end face at the rear end of the drive shaft 17 and which is formed rotationally symmetrically and which is not used as a balance weight.

[0049] The pressure element 87 is connected to the drive shaft 17 by a central screw 83. To adapt the outer diameter of the rear part of the drive shaft 17 to the inner diameter of the motor rotor 21, the rear part of the drive shaft 17 is provided with a sleeve element 33. The sleeve element 33 is clamped together with the motor rotor 21 by the pressure element 87 and the central screw 83. The sleeve element 33 is fixed to the drive shaft by a locating pin 33a. Furthermore, an annular intermediate element 34 is arranged axially between a shoulder 17a formed on the drive shaft 17 and the motor rotor 21. The motor rotor 21 is clamped via the intermediate element 34 between the pressure element 87 and the shoulder 17a of the drive shaft 17, which serves as an abutment for the intermediate element 34. A wave spring 99 is arranged in the area of ​​the shoulder 17a between the intermediate element 34 and the floating bearing 27 constituting the rear bearing part 27.

[0050] The drive motors 21, 23 are completely disposed within the pump housing 41, i.e., they are circumferentially surrounded by the pump housing 41 over their entire axial length and do not protrude rearward. At their rear end, the pump housing 41 is closed by a separate motor cover 103.

[0051] At the front end of the pump housing 41 is located a pump system having a fixed spiral element 11 and a moving spiral element 13. The fixed spiral element 11, also called the spiral housing, is screwed to the end face of the front end of the pump housing 41 and is surrounded by a hood 105, which is also attached to the pump housing 41, and which also houses a fan 95.

[0052] The movable spiral element 13 is supported on the eccentric part 19 via a flanged bearing 91, which is designed as a rolling bearing. A thrust washer 93 is located axially between the movable spiral element 13 and the eccentric part 19. A shim 94 is located between the annular shoulder of the drive shaft 17 at the transition to the eccentric part 19 and the flanged bearing 91. Exact circumferential alignment between the fixed spiral element 11 and the pump housing 41 is ensured by a single locating pin 97. In variations of this basic design, multiple locating pins 79 can also be provided.

[0053] The fixed spiral element 11 comprises a spiral structure having a spiral wall 49 and a spiral base 51, and a carrier 53 for the spiral structure, the side of which facing the movable spiral element 13 constitutes the spiral base 51. For example, two radially outer spiral walls 49 may be provided, which are located concentrically and circumferentially interrupted. This results in a parallel pump structure consisting of parallel pumping channels formed by respective spiral grooves between the spiral walls 49, which merge into a pump channel extending radially inward in a spiral manner, which is formed by spiral grooves and defined by the spiral wall 49.

[0054] The movable spiral element 13 also comprises a spiral structure with a spiral wall 69 and a spiral base 71, and a plate-like carrier 73 for the spiral structure, the side of which facing the fixed spiral element 11 constitutes the spiral base 71. Depending on the spiral structure of the fixed spiral element 11, two radially outer spiral walls 69 may be provided, which are located concentrically and are interrupted circumferentially in the region of the gas inlet (not shown). The radially inner spiral wall 69 extends helically.

[0055] Both the spiral wall 49 of the fixed spiral element 11 and the spiral wall 69 of the movable spiral element 13 are provided with elongated sealing elements 75 (tip seals) at the ends opposite the respective spiral bases 51 or 71 .

[0056] The spiral structure of both spiral elements 11, 13 may be formed differently.

[0057] Via the inlet flange 77, the gas to be pumped reaches the pump system comprising both spiral elements 11, 13 and is discharged via an outlet flange, not shown.

[0058] The pump housing 41 is supported on a base formed by the electronics housing 43. The pump housing 41 is screwed to the electronics housing 43. The electronics housing 43, not shown in full, has legs on its underside, not shown. The electronics housing 43 houses the electronics, which includes electronic, electrical, and electromechanical components used, among other things, to power and control the scroll vacuum pump.

[0059] Furthermore, the scroll vacuum pump is provided with a gas ballast valve (not shown). In a variation of this basic structure, a multi-stage gas ballast system may be provided instead of the gas ballast valve.

[0060] The eccentric drive, constituted by the drive shaft 17 with the eccentric portion 19, is located in the pump housing 41 and is surrounded by a deformable sleeve in the form of a bellows 89. The bellows 89 serves, on the one hand, to seal the eccentric drive against the suction area of ​​the scroll vacuum pump and, on the other hand, as an anti-rotation device for the moving spiral element 13. For this purpose, the bellows 89 is fixed to the side of the moving spiral element 13 facing the drive. The rear end of the bellows 89 is attached to the housing base within the pump housing 41 by means of a screw.

[0061] Figures 2 and 3 show the moving spiral element 13 of the scroll vacuum pump of Figure 1 and are used to explain the basic structure of such a moving spiral element 13. An embodiment of a fixed spiral element (not shown) according to the invention can have a corresponding basic structure.

[0062] The movable spiral element 13 comprises a spiral structure with spiral walls 69 and a spiral base 71, and a plate-like carrier 73 for the spiral structure. The two radially outer spiral walls 69 extend concentrically and are interrupted circumferentially in the region of the gas inlets 67 and, as already mentioned above, are also called spiral walls, despite being part-circular. The spiral wall 69 located radially inner extends helically. At the end opposite the spiral base 71, the spiral wall 69 is provided with a sealing element 75 (tip seal) not shown here.

[0063] A radially outer spiral groove 70 is provided between the two part-circular spiral walls 69. Another spiral groove 70 extending helically is defined by the helical spiral wall 69.

[0064] Each spiral wall 69 has two free end portions 111. The wall thickness WD of the spiral wall, including the free end portions 111, is constant over its entire length, with the exceptions described below. Only the free end portions 111 located in the recesses 67 of both semicircular spiral walls 69 have radial extensions 111a at their free ends, with the end of the radially outer spiral wall 69 widening radially inward and the end of the inner spiral wall 69 widening radially outward. Thus, the thickness of both spiral walls 69 increases at these ends.

[0065] In FIG. 4, purely for the sake of illustration, the problem of springback of the free end portion 111 of the spiral wall 69, 49 of the spiral element machined therein is shown.

[0066] A spiral wall that is not radially deflected at its free end portion 111 by the machining tool during machining, i.e., that is, that has an infinitely high stiffness, will, after machining, i.e., after the machining tool is removed, occupy its free end portion in the ideal position 127 shown by the dashed line in Figure 4, and therefore within the tolerance range 128 shown by the dashed-dotted line. In Figure 4, a dashed line indicates the original position 130 of the inner side of the spiral wall 69, 49 that the inner side occupies before machining. This dashed line 130 has a certain distance from the inner side of the machined, infinitely high stiffness spiral wall, i.e., the certain distance indicates that in the case of an infinitely high stiffness spiral wall, the free end portion 111 will undergo the same material removal as the upstream portion 113. In fact, due to the elastic deformation of the spiral walls 69, 49 at their free end portions 111, these spiral walls are deflected during machining, which causes the machining tool, moving along a path set by the programming of the machine tool, to remove less material than would be the case with an infinitely stiff spiral wall that does not yield to the machining tool. The free end portion 111 deflected by the machining tool springs back after machining and assumes the actual position 129 shown in Fig. 4 by the solid line, since it does not achieve the predetermined target profile (to which the tolerance 128 is adjusted) due to the very small material removal. As a result, the free end portion 111 is partially outside the tolerance 128.

[0067] Figure 5 shows how the springback effect described with reference to Figure 4 can actually have an effect when manufacturing a spiral element by means of a machine tool. In the control of the machine tool, for example, a target contour 131 is set for the inside of the spiral wall to be manufactured, and a tolerance range defined by a radially outer tolerance range 133 and a radially inner tolerance range 135 is determined for this target contour.

[0068] The target contour 131 and both tolerances 133, 135 are shown here as part circles and therefore for a part-circular spiral wall. In the case of a spirally extending spiral wall, these lines extend correspondingly spirally.

[0069] Ideally, the inside of the manufactured spiral wall lies on the target contour 131. For an actually manufactured spiral wall that adheres to the specified dimensions within the specified tolerances, its inside 137 obtained by measurement with a coordinate measuring machine (measured inside 137) lies within the tolerance ranges 133, 135. Except for the free end portion, this measured inside 137 is substantially shifted only relative to the target contour 131, and two "critical regions" 139 are shown in which the measured inside 137 lies near or on the respective tolerance ranges 133 or 135.

[0070] However, the above-mentioned springback effects at the free end portions of the manufactured spiral wall result in "disturbances" 141 in the form of exceeding tolerances 135 during measurement. However, these exceedances do not result from merely suboptimal settings of the machine tool but rather from the above-mentioned springback effects. The automatic correction of the machine tool can detect the above-mentioned shift of the measured inside 137 relative to the target contour 131 and, if no disturbance areas 141 exist, perform a corresponding automatic correction of the machine tool. Since these disturbances caused by springback practically make automatic measurement correction impossible, manual intervention by the operator must ensure that the disturbance areas 141 are excluded from the correction. As explained at the beginning, since each spiral wall is measured after its manufacture and then the machine tool settings are corrected as necessary based on the measurement results, the springback free end portions of the spiral wall consequently delay the overall manufacturing process.

[0071] A spiral element according to the invention, here taken as an example of a movable spiral element 13 (orbiter), is shown in Figures 6 and 7. The free end portion 111 of the spiral wall 69 is in particular manufactured according to the invention. The free end portion of the spiral wall of the fixed spiral element (spiral housing) can also be manufactured in this way.

[0072] The free end portion 111, which does not have a radial extension at its end, is in the example shown here provided with recesses RS on both sides, i.e. both radially inner and radially outer sides, respectively, which extend over the entire wall height, so that overall the free end portion 111 has a reduced thickness WDr (see also Figures 8 and 9) which is smaller than the thickness WD of the portion 113 of the spiral wall 69 upstream of the free end portion 111 (see also Figures 8 and 9). The transitions 112 to the radially inner and radially outer free end portions 111 can basically have any desired course.

[0073] Each of the free end portions 111, which are provided with a radial extension 111a at their end, has a recess RS on the side opposite the radial extension, and on this side only, they are set back relative to the upstream portion 113 of the spiral wall 69.

[0074] FIG. 8 illustrates a method for manufacturing the spiral wall 69, 49 by means of a milling tool 119, e.g., an end mill, rotating about an axis 121. The dashed lines indicate a conventional setup for manufacturing the free end portion 111 of the spiral wall 69, 49, whereby the free end portion 111 has the same wall thickness WD as the upstream portion 113. According to the present invention, the setup for machining the free end portion 113 is such that the free end portion 111 is provided with recesses RS by the tool 119 during machining on both the outer side 117 and the inner side 115. As a result, the free end portion 111 is recessed relative to the upstream portion 113 on both the outer side 117 and the inner side 115, resulting in a reduced wall thickness WDr that is smaller than the wall thickness WD of the upstream portion 113. The length L of the free end portion 111 with the reduced wall thickness WDr is preferably in the range of 3 mm to 10 mm.

[0075] According to an optional embodiment, shown diagrammatically in FIG. 9, a reduced wall thickness WDr may be formed by forming a recess RS only on one side of the free end portion 111, here radially inward 115, by means of a machining tool not shown here.

[0076] If such a free end portion 111 with one or two recesses RS springs back after machining, the free end portion 111 will remain within the target contour, i.e., within the tolerance range, not shown here, because the settings for machining cause the machining tool to remove more material than would be the case if there were no settings for forming the reduced thickness WDr or one or two recesses RS.

[0077] The reduced wall thickness WDr or the one or two recesses RS are set in terms of size depending on the respective situation, i.e., as mentioned at the beginning, depending on the mechanical properties of the spiral wall to be produced and the machining parameters of the machine tool, in particular depending on the force with which the tool 119 (see Figure 8) is pressed against the inside 115 or outside 117 of the spiral wall 69, 49 to be produced during machining. [Explanation of symbols]

[0078] 11 Fixed spiral element, spiral housing 13 Moving Spiral Element, Orbiter 15 Rotation axis 17 Drive shaft 17a Shoulder 19 Eccentric part 21 Motor rotor 23 Motor stator 25 Front bearing location (fixed bearing) 27 Rear bearing part (floating bearing) 29 Front balance weight 31 Rear balance weight 33 Sleeve Elements 34 Intermediate Elements 41 Pump housing 43 Electronic equipment housing 49 Spiral Wall of Fixed Spiral Elements 51 Spiral base 53 Career 67 Recess 69 Spiral Wall of Moving Spiral Element 70 spiral groove 71 Spiral base 73 Career 75 sealing elements 77 Inlet flange 83 Center screw 87 Pressure Element 89 Bellows 91 flanged bearing 93 Thrust washer 94 Sim 95 fans 97 Locating pin 99 Wave Spring 103 Motor cover 105 Food 111 Free end part 111a Extension 112 Transition 113 Upstream section 115 Inside 117 Outside 119 Tools 121 Rotation axis 123 Groove 127 Ideal position of the free end 128 tolerance 129 Actual position of the free end 130 Inner original position 131 Target Contour 133 Radial outer tolerance 135 Radial inner tolerance 137 Measured Inside 139 Critical region 141 Springback "disorder" WDr Reduced Thickness WD Thickness RS recess L length

Claims

1. a pump system comprising a fixed spiral element (11) and a movable spiral element (13) cooperating with the fixed spiral element in a pumping manner; a drive shaft (17) having an eccentric portion (19) for driving the movable spiral element (13), which rotates during operation about the axis of rotation (15); electric drive motors (21, 23) for the drive shafts (17); 1. A scroll vacuum pump having: The movable spiral element (13) comprises a spiral structure having a spiral wall (69), a spiral groove (70) defined by the spiral wall, and a spiral base (71) constituting the bottom of the spiral groove, and a carrier (73) for the spiral structure cooperating with an eccentric portion (19) of the drive shaft (17), The fixed spiral element (11) comprises a spiral structure having a spiral wall (49) and a spiral base (51), and a carrier (53) for the spiral structure. In scroll vacuum pumps, A scroll vacuum pump, characterized in that at least one spiral wall (69, 49) has a reduced thickness (WDr) at a free end portion (111) that is smaller than a thickness (WD) of a portion (113) upstream of the free end portion (111) that transitions to the free end portion (111) of the spiral wall (69, 49).

2. a pump system comprising a fixed spiral element (11) and a movable spiral element (13) cooperating with the fixed spiral element in a pumping manner; a drive shaft (17) having an eccentric portion (19) for driving the movable spiral element (13), which rotates during operation about the axis of rotation (15); electric drive motors (21, 23) for the drive shafts (17); 1. A scroll vacuum pump having: The movable spiral element (13) comprises a spiral structure having a spiral wall (69), a spiral groove (70) defined by the spiral wall, and a spiral base (71) constituting the bottom of the spiral groove, and a carrier (73) for the spiral structure cooperating with an eccentric portion (19) of the drive shaft (17), The fixed spiral element (11) comprises a spiral structure having a spiral wall (49) and a spiral base (51), and a carrier (53) for the spiral structure. In scroll vacuum pumps, 1. A scroll vacuum pump comprising: at least one spiral wall (69, 49) having a free end portion (111) radially outwardly and / or radially inwardly with a recess (RS) relative to an upstream portion (113) of the free end portion (111) that transitions to the free end portion (111) of the spiral wall (69, 49).

3. 3. A scroll vacuum pump according to claim 1 or 2, characterized in that the reduced thickness (WDr) of the free end portion (111) is smaller than the thickness (WD) of the upstream portion (113) over the entire wall height and / or the recess (RS) extends over the entire wall height of the free end portion (111).

4. 4. The scroll vacuum pump according to claim 1, wherein the reduced thickness (WDr) of the free end portion (111) is constant over the entire wall height and / or the recess (RS) is constant over the entire wall height of the free end portion (111).

5. 4. The scroll vacuum pump according to claim 1, wherein the reduced thickness (WDr) of the free end portion (111) decreases continuously from the spiral root (71) to the tip of the spiral wall (69, 49), in particular at the spiral root (71) the free end portion (111) and the upstream portion (113) of the spiral wall (69, 49) have the same thickness (WD); and / or the recess (RS) of the free end portion (111) decreases continuously from the tip of the spiral wall (69, 49) to the spiral root (71), in particular at the spiral root (71) the recess (RS) is equal to zero.

6. 6. The scroll vacuum pump according to claim 1, wherein the free end portion (111) has a recess (RS) relative to the upstream portion (113) on both the radially inner side (115) and the radially outer side (117), or the free end portion (111) has a recess (RS) relative to the upstream portion (113) only on the radially inner side (115).

7. 7. A scroll vacuum pump according to claim 1, wherein the spiral wall (69) is manufactured by machining using a machine tool, the machine tool having a rotary tool (119), in particular a milling tool, which during machining is pressed against the radially inner side (115) or the radially outer side (117) of the spiral wall (69, 49) to be manufactured, in particular the tool (119) being guided during machining over a path which sets a reduced thickness and / or a recess (RS) in the free end portion (111) of the spiral wall (69, 49).

8. 8. The scroll vacuum pump according to claim 7, wherein a target contour of the spiral wall (69, 49) is set in at least one plane extending perpendicular to the rotation axis (15) of the drive shaft (17), and the path of the tool (119) is set so that a free end portion (111) of the spiral wall (69, 49), which is deflected by the tool (119) during machining and which springs back after machining, remains within the target contour.

9. 9. The scroll vacuum pump according to claim 1, wherein the movable spiral element (13) and the fixed spiral element (11) are each made of aluminum or a material containing aluminum.

10. 10. The scroll vacuum pump according to claim 1, wherein the reduced thickness (WDr) of the free end portion (111) is 85% to 98%, in particular 92% to 95%, of the thickness (WD) of the upstream portion (113); or wherein the reduced thickness (WDr) of the free end portion (111) is 1 / 10 mm to 3 / 10 mm smaller than the thickness (WD) of the upstream portion (113); and / or wherein the recess (RS) of the free end portion (111) is 0.5 / 10 mm to 2 / 10 mm.

11. 11. The scroll vacuum pump according to claim 1, wherein the length (L) of the free end portion (111) measured in the extension direction of the spiral wall (69, 49) is in the range of 3 mm to 10 mm.

12. A method for manufacturing a scroll vacuum pump according to any one of claims 1 to 11 or for manufacturing a spiral element (13, 11) for a scroll vacuum pump according to any one of claims 1 to 11, comprising: The spiral wall (69, 49) is produced by machining with a machine tool, which machine tool has a rotary tool (119), in particular a milling tool, which during machining is pressed against the radially inner side (115) or the radially outer side (117) of the spiral wall (69, 49) to be produced.

13. 13. The method according to claim 12, characterized in that the tool (119) is guided on a path that sets a reduced thickness (WDr) and / or a recess (RS) in the free end portion (111) of the spiral wall (69, 49) during machining.

14. 14. The method according to claim 12 or 13, characterized in that a target contour of the spiral wall (69, 49) is set in at least one plane extending perpendicularly to the rotation axis (15) of the drive shaft (17), and the path along which the tool (119) is guided during machining is set in such a way that a free end portion (111) of the spiral wall (69, 49), which is deflected by the tool (119) during machining and which springs back after machining, remains within the target contour.

15. 15. The method according to claim 12, wherein different dimensional tolerances are set for the reduced thickness (WDr) of the free end portion (111) and / or for the recess (RS) of the free end portion (111) and for the thickness (WD) of the upstream portion (113), in particular the dimensional tolerances are + / - 1 / 10 mm, in particular + / - 1 / 100 mm to + / - 6 / 100 mm, respectively.

Images