Scroll vacuum pump and manufacturing method thereof

Abstract

The present invention relates to a scroll vacuum pump comprising: a pump system having a fixed scroll member and a movable scroll member forming an effective pumping fit with the fixed scroll member; a drive shaft rotating about a rotational axis during operation and having an eccentric section for driving the movable scroll member; and an electric drive motor for driving the shaft. The movable vortex component comprises a vortex device and a carrier, the vortex device is composed of a vortex wall, a vortex groove defined by the vortex wall and a vortex base formed at the bottom of the vortex wall, and the carrier is matched with the eccentric section of the driving shaft and used for the vortex device. The fixed vortex component comprises a vortex device composed of a vortex wall and a vortex base, and a carrier used for the vortex device. According to a first aspect, at least one scroll wall has a reduced thickness at a free end section thereof that is less than a thickness of a section located upstream of and transitioning to the free end section of the scroll wall. According to a second aspect, at least one scroll wall has a free end section that forms a turnup on a radially outer side and / or radially inner side thereof with respect to a section of the scroll wall that is upstream of and transitions to the free end section.

Description

TECHNICAL FIELD

[0001] The invention relates to a scroll vacuum pump having a pump system comprising a fixed scroll part and a movable scroll part cooperating therewith for pumping, a drive shaft rotating in operation about an axis of rotation and having an eccentric section for driving the movable scroll part, and an electric drive motor for the drive shaft, wherein the movable scroll part comprises a scroll device consisting of scroll walls, scroll grooves defined by the scroll walls, and a scroll base formed by the bottom of the scroll grooves, and a carrier cooperating with the eccentric section of the drive shaft for said scroll device, and the fixed scroll part comprises a scroll device consisting of scroll walls and a scroll base, and a carrier for the scroll device.

[0002] The invention also relates to a method for manufacturing such a scroll vacuum pump.

[0003] Scroll vacuum pumps are known, for example from EP 3 153 708 A2, EP 3 617 511 A2, EP 3 647 599 A2, EP 4 174 285 A1 and EP 4 253 720 A2.

[0004] A scroll pump is a positive displacement pump that compresses gas to atmospheric pressure and can be used as a compressor. A scroll vacuum pump can be used to evacuate a vessel connected to a gas inlet of the scroll vacuum pump.

[0005] A scroll vacuum pump is also known as a spiral vacuum pump or spiral conveyor. The basic pumping principle of a scroll vacuum pump is known to the person skilled in the art, so only a brief description is given below.

[0006] Generally, the pump system of a scroll vacuum pump has two mutually nested or inserted, for example Archimedean, scroll cylinders, which can also simply be referred to as scrolls or scroll parts. Each scroll cylinder comprises at least scroll walls and, on the end face of the scroll walls, a carrier, in particular a plate-like carrier, wherein the outer spiral turns, for example the two to three outermost turns, of the scroll cylinder can be formed by wall sections that keep a constant distance in the circumferential direction between the center of the scroll. Although these wall sections are not spiral sections in the strict sense, but rather circular arc sections, they are still considered to be part of the scroll and referred to as spiral turns of the scroll in the context of the present invention.

[0007] The scroll cylinders are nested into each other such that partial areas of the two scroll cylinders form crescent- or sickle-shaped volume chambers (delivery chambers). One of the two scrolls is fixedly arranged in the pump housing, while the other scroll and its carrier can be moved along a circular path by means of an eccentric section of the drive shaft, so that the scroll and its carrier are collectively referred to as the movable scroll (Orbiter). The movable scroll component performs a so-called central-symmetrical oscillating movement, also referred to as "revolution" or "wobble". The crescent-shaped volume chambers (delivery chambers) located between the scroll cylinders move stepwise inwards during the revolution of the movable scroll component, so that the process gas to be pumped is transported from the gas inlet on the radially outer side of the pump system through the moving volume chambers to the gas outlet in the center of the scroll.

[0008] The manufacture of the scroll components of a scroll vacuum pump is very labor-intensive, since, in particular, the scroll walls have to be machined with very high precision. The predefined manufacturing tolerances must not be exceeded, since even small deviations in size can cause so-called gap crossings during the operation of the scroll vacuum pump, which in turn can lead to wear and noise. One reason known for the lack of dimensional accuracy is the elastic deformation of the scroll walls at their free end sections. When the scroll walls are manufactured by means of chip removal machining, for example using a rotating end mill, the scroll walls are deflected due to their elastic deformation if the tool acts on the radially inner or radially outer side of the scroll wall. As a result, under the same conditions, less material is removed on that side than on a scroll wall which is less or not deflected due to its higher rigidity. When the machining tool is moved away, the scroll wall springs back to its original position. Due to the smaller amount of material removed, it can be possible that the prescribed manufacturing tolerances are not met.

[0009] This spring-back effect is particularly pronounced at the end of the scroll wall, since the rigidity of the scroll wall is lower there than in the wall section upstream of the free end section. It has been observed that this spring-back effect can severely impair the dimensional accuracy, so that the machined scroll wall springs back at its end beyond the manufacturing tolerances.

[0010] This spring-back effect also makes the series production of scroll components more complex. In practical production, each scroll component is usually immediately after completion of the manufacture automatically checked for dimensional accuracy by means of a coordinate measuring machine. Based on the measurement results, if necessary, the settings of the machine tool are corrected so that the contour of the next scroll component to be produced approximates as closely as possible to the target contour and remains within the tolerance range. However, existing correction algorithms cannot take into account the above-mentioned spring-back effect, so that the interpretation of the correction measurements is disturbed, which makes it impossible to automatically correct the machine tool for each scroll component individually and quickly. Instead, the operator has to manually intervene in the correction of the measurements, for example by ignoring or otherwise processing the workpiece parts affected by the spring-back effect, in particular the free end section of the scroll wall. This significantly increases the time required for the manufacturing process and correspondingly increases the costs.

[0011] The object of the present application is to provide a scroll vacuum pump and a method for manufacturing the same, which can make the production of the scroll vacuum pump components, especially the scroll components, simpler, faster and lower cost while ensuring high dimensional accuracy, wherein in particular the dimensional accuracy can be quickly and automatically detected and the setting of the machining tool can be corrected if necessary.

[0012] The present application solves the above-mentioned technical problems by the features described in the independent claims.

[0013] According to the scroll vacuum pump of the present application according to independent claim 1, it is characterized in that at least one scroll wall has a reduced thickness at the free end section, which is smaller than the section of the scroll wall upstream of and transitioning to the free end section.

[0014] According to the scroll vacuum pump of the present application according to independent claim 2, it is characterized in that at least one scroll wall has a free end section, which forms a setback on its radially outer side and / or radially inner side with respect to the section upstream of and transitioning to the free end section.

[0015] The two aspects of the present application are based on the idea that the end section of the scroll wall is machined on the radially inner side and / or radially outer side such that the springback effect no longer causes a certain part of the end section to exceed the respective predetermined tolerance range. To this end, the end section is provided with a reduced thickness and / or a setback during machining, i.e. more material is removed at the end section than at a stiffer end section. It has proven that the measures according to the present application avoid the aforementioned disadvantages while not affecting the performance of the scroll vacuum pump.

[0016] According to the first aspect of the present application, the reduced thickness of the free end section is not mandatory. According to the second aspect of the present application, the end section can be provided with a setback on its radially inner side or radially outer side. For example, when the end section has a radial expansion on the opposite side, the setback ensures that the end section is still within the respective tolerance range after machining despite the elastic offset during machining, although it does not reduce the thickness of the entire end section.

[0017] The present application thus avoids the exceeding of the predetermined tolerance range due to the springback effect, in particular with the following advantages: the detection results obtained by the automatic coordinate measuring machine can be better automatically analyzed and, if necessary, automatically used for adjusting the correction parameters of the respective machining device. In this automatic optimization, manual intervention by an operator is no longer required, thus simplifying and accelerating the overall production process and reducing the manufacturing costs. Another advantage is that by reducing the thickness or providing a setback, i.e. removing more material, it is also possible to preset larger tolerances for machining, thus fundamentally simplifying the manufacturing process.

[0018] Advantageous refinements of the present application are also shown in the dependent claims, the following description and the drawings.

[0019] According to some embodiments, the free end section of each scroll wall has a reduced thickness and / or a setback.

[0020] Furthermore, it can be provided that the reduced thickness of the free end section is smaller than the thickness of the preceding section over the entire wall height, and / or that the setback extends along the entire wall height of the free end section.

[0021] In particular, it can be provided that the reduced thickness of the free end section remains constant over the entire wall height, and / or that the setback remains constant over the entire wall height of the free end section.

[0022] However, this is not mandatory. The rigidity of the free end section at the scroll base is higher than at the scroll tip. According to some embodiments, it can be provided that the reduced thickness of the free end section decreases gradually from the scroll base to the tip of the scroll wall, in particular where the free end section has the same thickness as the upstream section of the scroll wall at the scroll base; or that the setback of the free end section decreases gradually from the tip of the scroll wall to the scroll base, in particular where the setback is zero at the scroll base.

[0023] According to some developments of the application, it can be provided that the free end section is provided with a setback relative to the upstream section both at its radially inner side and at its radially outer side. Alternatively, according to some embodiments, it can be provided that the free end section is provided with a setback relative to the upstream section only at its radially inner side.

[0024] Some developments provide that the scroll wall is manufactured by means of a machine tool having a rotating tool, in particular a milling tool. The tool is pressed against the radially inner side or the radially outer side of the scroll wall to be manufactured during the machining process. In particular, it is provided that the tool is guided along a predefined path during the machining process, which path defines the reduced thickness and / or the setback at the free end section of the scroll wall.

[0025] It can be provided that a target profile of the scroll wall is defined in at least one plane perpendicular to the rotational axis of the drive shaft, and that the guide path of the tool is defined in such a way that the free end section of the scroll wall, which is deflected by the tool during the machining process and springs back after the machining, remains within the target profile.

[0026] The target profile in particular refers to the plane in which the tip of the scroll wall is located, since the greatest deflection of the scroll wall occurs in this region during the machining.

[0027] According to several embodiments, both the movable scroll member and the stationary scroll member are made of aluminum or an aluminum-containing material.

[0028] Furthermore, it can be provided that the reduced thickness of the free end section is 85% to 98%, in particular 92% to 95%, of the thickness of the upstream section; or that the reduced thickness of the end section is 0.1 mm to 0.3 mm less than the thickness of the upstream section. Alternatively or additionally, it can be provided that the undercut of the end section is between 0.05 mm and 0.2 mm.

[0029] According to one specific embodiment, the end section with constant thickness is provided with an undercut of 0.1 mm on both sides, so that the overall thickness is reduced by 0.2 mm. For example, the thickness of the upstream section is in the range of 3.5 mm to 3.7 mm, so that the reduced thickness of the end section is in the range of 3.3 mm to 3.5 mm, approximately 94% of the thickness of the upstream section.

[0030] According to several embodiments, the length of the end section measured along the course of the scroll wall is between 3 mm and 10 mm.

[0031] According to the application, the method for manufacturing a scroll vacuum pump as disclosed herein or the method for manufacturing a scroll component of a scroll vacuum pump, it is provided that the scroll wall is manufactured by means of a machine tool having a rotating tool, in particular a milling tool. The tool is pressed against the radially inner or radially outer side of the scroll wall to be machined during machining.

[0032] The milling tool mentioned above in particular refers to an end mill, for example a cylindrical end mill or a cylindrical face mill.

[0033] Furthermore, it can also be provided that the tool is guided along a predefined path during machining, which path defines the reduced thickness and / or the undercut at the end section of the scroll wall.

[0034] Furthermore, it can also be provided that a target profile of the scroll wall is defined in at least one plane perpendicular to the rotational axis of the drive shaft, and that the guide path of the tool is defined in such a way that the free end section of the scroll wall, which is deflected by the tool during machining and springs back after machining, remains within the target profile.

[0035] In particular, it is provided that the guide path is defined in accordance with the target profile and specific conditions. The specific conditions in particular relate to the mechanical properties of the scroll wall to be manufactured, the force exerted by the tool on the inner or outer side of the scroll wall, and, if necessary, further material removal-related parameters of the machine tool. Thereby, potential errors due to spring-back of the scroll wall, i.e. potential deviations from the predefined tolerances, can be determined, so that the guide path of the tool can be defined accordingly in order to remove sufficient material so that spring-back does not actually cause a tolerance deviation.

[0036] Furthermore, it can be provided that the reduced thickness and / or the setback of the end section and the thickness of the section upstream of the end section are each set to a different dimensional tolerance, in particular a dimensional tolerance of ± 0.1 mm, in particular between ± 0.01 mm and ± 0.06 mm.

[0037] Such dimensional tolerances are not mandatory, i.e. other dimensional tolerances can also be set, which means that other cutting parameters can be used for each machine tool. BRIEF DESCRIPTION OF DRAWINGS

[0038] Next, the application will be described exemplarily with reference to the accompanying drawings. Shown in the drawings are: Figure 1 An example of a prior art scroll vacuum pump is shown for illustrating the basic structure of such a scroll vacuum pump; Figure 2 and Figure 3 An example of a prior art scroll vacuum pump is shown for illustrating the basic structure of such a scroll vacuum pump; Figure 1 Different views of the movable scroll member of the prior art scroll vacuum pump shown for illustrating the structure of the scroll member, also referred to as "orbiting scroll"; Figure 4 A schematic diagram for illustrating the spring-back problem of the scroll wall end section is shown; Figure 5 A schematic diagram for illustrating the spring-back effect is shown; Figure 4 Figure 6 A partial view of a movable scroll member according to one embodiment of the application is shown; Figure 7 An enlarged schematic view of the scroll wall end section of the scroll member shown; Figure 6 Figure 8 and Figure 9 A schematic diagram for illustrating the manufacturing method of the scroll wall according to the application is shown. DETAILED DESCRIPTION

[0039] Figure 1 A prior art scroll vacuum pump is shown, the basic structure of which is described as follows. The structure and the working principle of such a scroll vacuum pump are known to the person skilled in the art. The prior art scroll vacuum pump can be further improved according to the application, the relevant improvements will be described in connection with Figures 6 to 9 the description of the application.

[0040] Figure 1 ​​The shown scroll vacuum pump comprises a pump system comprising a fixed scroll part 11 and a movable scroll part 13, which form an effective pumping fit during operation. The scroll vacuum pump further comprises a drive shaft 17, which rotates about a rotational axis 15 during operation and has an eccentric section 19 for driving the movable scroll part 13. Furthermore, the scroll vacuum pump is provided with an electric drive motor 21, 23 for driving the drive shaft 17 about the rotational axis 15. The electric drive motor comprises a radially inner motor rotor 21, also called "armature", and a radially outer motor stator 23.

[0041] The drive shaft 17 is rotatably supported on the pump housing 41 by two axially spaced-apart bearing sites 25, 27. The front bearing site 25 is constituted by a front rolling bearing, which is designed as a fixed bearing, while the rear bearing site 27 is constituted by a rear rolling bearing, which is designed as a floating bearing. For supporting the drive shaft 17, the pump housing 41 is provided with a sleeve-shaped section, hereinafter also called bearing sleeve 115. The two rolling bearings 25, 27 are located radially between the drive shaft 17 and the bearing sleeve 115.

[0042] Both bearing sites 25, 27 are located on the side of the drive motor 21, 23 facing the eccentric section 19 of the drive shaft 17. Thus, all bearing sites 25, 27 are located inside the pump housing 41 in front of the drive motor 21, 23. Therein, the bearing sites 25, 27 are located in the atmospheric pressure region of the pump, i.e. not in the region in which a vacuum is formed during pumping operation. The eccentric section 19 is integrally connected with the front end of the drive shaft 17, while the drive motor 21, 23 is mounted on the rear end of the drive shaft 17. By this construction, the drive motor 21, 23 can be fitted to the rear end of the drive shaft 17, thus simplifying the mounting and replacement of the drive motor 21, 23 or parts thereof.

[0043] The dynamic balancing scheme for balancing the rotating system comprising the drive shaft 17 and the movable scroll part 13 comprises a front counterweight 29 and a rear counterweight 31, both of which are arranged on the drive shaft 17. The front counterweight 29 is arranged in the region of the front end of the drive shaft 17 and the eccentric section 19. The rear counterweight 31 is located in front of the rear bearing site 27, i.e. on the front side of the drive motor.

[0044] In variants of this basic construction, other dynamic balancing schemes can also be used. For example, a rear counterweight or an additional counterweight can be arranged in the region of the rear end of the drive shaft, the drive motor.

[0045] Furthermore, the rear end face of the drive shaft 17 is provided with a pressure element 87, which has a rotationally symmetrical construction and is not used as a counterweight.

[0046] The pressure element 87 is connected to the drive shaft 17 by means of a center screw 83. In order to adapt the outer diameter of the rear section of the drive shaft 17 to the inner diameter of the motor rotor 21, the rear section of the drive shaft is provided with a sleeve element 33. The sleeve element 33 is clamped to the motor rotor 21 by means of the pressure element 87 and the center screw 83. The sleeve element 33 is fixed to the drive shaft 17 by means of a positioning pin 33a. Furthermore, an annular intermediate element 34 is arranged axially between a shoulder 17a of the drive shaft 17 and the motor rotor 21. The motor rotor 21 is clamped between the pressure element 87 and the shoulder 17a of the drive shaft 17 by means of the intermediate element 34, wherein the shoulder 17a serves as a thrust face for the intermediate element 34. In the region of the shoulder 17a, a wave spring 99 is arranged between the floating bearing 27, which forms the rear bearing site 27, and the intermediate element 34.

[0047] The drive motors 21, 23 are arranged completely inside the pump housing 41, i.e. the drive motors 21, 23 are surrounded circumferentially by the pump housing 41 over their entire axial length and do not protrude rearward. The rear end of the pump housing 41 is closed by a separate motor end cap 103.

[0048] At the front end of the pump housing 41, a pump system is arranged, which comprises the fixed scroll member 11 and the movable scroll member 13. The fixed scroll member 11, also referred to as "scroll housing", is fixed to the front end of the pump housing 41 by means of end face screws and is surrounded by a shroud 105, which is also mounted on the pump housing 41, inside which a fan 95 is arranged.

[0049] The movable scroll member 13 is supported on the eccentric section 19 by means of a flange bearing 91, which is designed as a rolling bearing. A pressure plate 93 is arranged axially between the movable scroll member 13 and the eccentric section 19. A matching spacer 94 is arranged between the annular shoulder of the drive shaft 17, which transitions into the eccentric section 19, and the flange bearing 91. The circumferential positioning of the fixed scroll member 11 with respect to the pump housing 41 is ensured by means of a positioning pin 97. In a variant embodiment of the basic structure, a plurality of positioning pins 79 can also be provided.

[0050] The fixed scroll member 11 comprises a scroll device consisting of scroll walls 49 and a scroll base 51, as well as a carrier 53 for the scroll device, which forms the scroll base 51 on the side facing the movable scroll member 13. For example, two radially outer scroll walls 49 can be provided, which are located on concentric circles and are circumferentially interrupted. A parallel pumping structure is thus formed, which consists of a plurality of parallel pumping channels formed by the scroll grooves between the scroll walls 49, which ultimately merge into a pumping channel extending helically to the radially inner side; the pumping channel is formed by a helical scroll groove and is bounded by a helical scroll wall 49.

[0051] The movable scroll member 13 likewise comprises a scroll device consisting of scroll walls 69 and a scroll base 71, as well as a plate-shaped carrier 73 for the scroll device, which forms the scroll base 71 on the side facing the stationary scroll member 11. Depending on the configuration of the scroll device of the stationary scroll member 11, two radially outer scroll walls 69 can be provided, which are located on concentric circles and are interrupted circumferentially in the region of the not shown gas inlet. The radially inner scroll wall 69 is distributed in a spiral.

[0052] The scroll walls 49 of the stationary scroll member 11 and the scroll walls 69 of the movable scroll member 13 are each provided with an elongated sealing element 75 (Tip Seal) at the end facing away from the scroll base 51, 71.

[0053] The scroll devices of the two scroll members 11, 13 described above can also be designed in other ways.

[0054] The gas to be pumped enters the pump system comprising the two scroll members 11, 13 via a gas inlet flange 77 and is discharged via a not shown gas outlet flange.

[0055] The pump housing 41 is supported on a base formed by an electronics housing 43 and is fixedly connected to the electronics housing 43 by means of screws. The electronics housing 43, which is not completely shown, is provided at its bottom with not shown feet. Inside the electronics housing 43 there are provided electronic devices, which include electronic, electrical and electromechanical components for providing power and control for the scroll vacuum pump.

[0056] In addition, the scroll vacuum pump also comprises a not shown gas ballast valve. In a variant of the basic construction, a multi-stage gas ballast system can be provided instead of the gas ballast valve.

[0057] The eccentric drive mechanism formed by the drive shaft 17 and its eccentric section 19 is located inside the pump housing 41 and is covered by a deformable sleeve in the form of a bellows 89. The bellows 89 serves on the one hand to seal off the eccentric drive mechanism from the suction area of the scroll vacuum pump and on the other hand as an anti-rotation device for the movable scroll member 13. For this purpose, the bellows 89 is fixed to the side of the movable scroll member 13 facing the drive mechanism. The rear end of the bellows 89 is fixed by means of screws to the housing bottom inside the pump housing 41.

[0058] Figure 2 and Figure 3 shown Figure 1 The movable scroll member 13 of the scroll vacuum pump shown is shown and serves to illustrate the basic construction of such a movable scroll member 13. The embodiment of the stationary scroll member (not shown) according to the application can have a corresponding basic construction.

[0059] The movable scroll member 13 comprises a scroll device and a plate-like carrier 73 for the scroll device, which is composed of scroll walls 69 and a scroll base 71. Two radially outer scroll walls 69 are distributed on concentric circles and are interrupted in the circumferential direction in the region of the inlet opening 67. As already mentioned, they are referred to as scroll walls, although they are in the form of partial circular arcs. The radially inner scroll wall 69 is distributed in the form of a spiral. The scroll walls 69 are provided at their end remote from the scroll base 71 with sealing elements 75, which are not shown here.

[0060] Between the two partial circular arc-shaped scroll walls 69, radially outer scroll grooves 70 are provided. Another scroll groove 70, which is distributed in the form of a spiral, is defined by the spiral-shaped scroll wall 69.

[0061] The scroll walls 69 each have two free end sections 111. With the exception of the cases described below, the wall thickness WD of the scroll walls, including their end sections 111, remains constant over the entire length. Only the end sections 111 of the two partial circular arc-shaped scroll walls 69 at the inlet opening 67 are each provided at their free end with a radial expansion 111a, wherein the end of the radially outer scroll wall 69 expands radially inwards and the end of the inner scroll wall 69 expands radially outwards. Thus, at these ends, the thickness of the two scroll walls 69 increases.

[0062] Figure 4 For illustrative purposes only, the problem of springback of the free end sections 111 of the scroll walls 69, 49 of a scroll member which has been machined on the inside.

[0063] If the end section 111 of a scroll wall is not radially offset by the machining tool during machining, i.e. has an infinite stiffness, then after machining, removal of the machining tool, the end section will be in the ideal position 127 indicated by the dashed line, thus within the tolerance limit 128 indicated by the dash-dotted line. Figure 4 The ideal position 127 is indicated by the dashed line. The end section 111 of the scroll wall 69, 49 will thus be in the ideal position 127 indicated by the dashed line, thus within the tolerance limit 128 indicated by the dash-dotted line. Figure 4 The original position 130 of the inside of the scroll wall 69, 49 before machining is indicated by the dashed line. This dashed line 130 maintains a constant distance from the inside of the machined scroll wall with infinite stiffness, i.e. the constant distance indicates that for the scroll wall with infinite stiffness the amount of material removed at the end section 111 is the same as the amount of material removed at the upstream section 113. In practice, there is the problem that due to the elastic deformability of the scroll wall 69, 49 at its end section 111, a springback occurs during machining, so that the amount of material removed by the machining tool moving along the preset path of the CNC machine is less than the amount of material removed by the ideal scroll wall with infinite stiffness, which does not allow for the let-in of the tool during machining. The end section 111, which has been displaced by the machining tool, springs back after machining, but due to the insufficient amount of material removed, it does not reach the preset target contour which matches the tolerance limit 128, so that it is in the position 131 indicated by the dash-dotted line after machining. Figure 4The actual position 129 is indicated by a solid line. This results in the end section 111 exceeding the tolerance limit 128.

[0064] Figure 5 Further explained Figure 4 The described spring-back effect can have a practical impact when manufacturing scroll components using a machine tool. For example, in a machine tool control system, a target profile 131 can be set for the inner side of a scroll wall to be machined, and a tolerance range can be specified, which is defined by a radially outer tolerance limit 133 and a radially inner tolerance limit 135.

[0065] Here, the target profile 131 and the two tolerance limits 133, 135 are shown in the form of partial circular arcs, corresponding to a partial circular arc-shaped scroll wall. For a scroll wall extending in the form of a spiral, the lines would extend in the form of a spiral accordingly.

[0066] Ideally, the manufactured scroll wall inner side should lie on the target profile 131. When the actually manufactured scroll wall has dimensions within the given tolerance range, the inner side 137 measured by means of a coordinate measuring machine (measured inner side 137) should lie between the tolerance limits 133, 135. With the exception of the end section, this measured inner side 137 is essentially only offset relative to the target profile 131, as shown in the two "critical regions" 139, where the measured inner side 137 approaches or reaches the respective tolerance limit 133 or 135.

[0067] However, the spring-back effect at the end section of the aforementioned manufactured scroll wall can cause "interference" 141 when measuring, in the form of an exceeding of the tolerance limit 135. This exceeding is not simply due to a poor machine tool parameter setting, but is caused by the described spring-back effect. In the absence of the interference region 141, an automatic correction of the machine tool can identify the offset of the measured inner side 137 relative to the target profile 131 and perform a corresponding automatic correction. In practice, however, the interference caused by the spring-back effect makes it impossible to implement an automatic measurement correction, and manual intervention by an operator is necessary to ensure that the interference region 141 is excluded during the correction process. As mentioned at the beginning, each scroll wall is measured after completion of the manufacture and the settings of the machine tool are corrected as necessary on the basis of the measurement results. The spring-back effect at the end section of the scroll wall can cause a delay in the entire manufacturing process.

[0068] Figure 6 and Figure 7 A scroll component according to the application is shown here by way of example of a movable scroll component 13 (orbiting scroll). The end section 111 of the scroll wall 69 is manufactured using the specific method according to the application. The end section of the scroll wall of a stationary scroll component (scroll housing) can likewise be manufactured in this way.

[0069] In the present embodiment, the radially non-expanding end section 111 is provided with a setback RS along the entire wall height on both sides, i.e. on the radially inner side and on the radially outer side, so that each free end section 111 as a whole has a reduced thickness WDr (see Fig. 8) which is smaller than the thickness WD of the section 113 of the scroll wall 69 upstream of the free end section 111. The transition 112 to the free end section 111 on the radially inner side and on the radially outer side can in principle assume any profile. Figure 8 and Figure 9 ), which is smaller than the thickness WD of the section 113 of the scroll wall 69 upstream of the free end section 111. The transition 112 to the free end section 111 on the radially inner side and on the radially outer side can in principle assume any profile.

[0070] The end sections 111 with the radial expansions 111a each have a setback RS on the side thereof which faces away from the radial expansion. This end section 111 is set back on this single side only with respect to the upstream section 113 of the scroll wall 69.

[0071] Figure 8 A method for machining the scroll wall 69, 49 with a milling tool 119, e.g. an end mill, which rotates about the axis 121, is shown. The dashed line shows the machining setting of the free end section 111 of the scroll wall 69, 49 in the prior art, i.e. the free end section 111 has the same wall thickness WD as the upstream section 113. According to the application, the machining setting for the free end section 111 is such that, by means of the tool 119 during machining, the outer side 117 and the inner side 115 of the free end section 111 are each provided with a setback RS. As a result, the free end section 111 is set back on the outer side 117 and on the inner side 115 with respect to the upstream section 113, so that a reduced wall thickness WDr is obtained which is smaller than the wall thickness WD of the upstream section 113. The length L of the end section 111 with the reduced wall thickness WDr is preferably between 3 mm and 10 mm.

[0072] According to a further embodiment which is shown schematically in Fig. 9, the setback RS and thus the reduced thickness WDr can also be formed on only one side of the free end section 111, here the radially inner side 115, by means of a tool which is not shown.

[0073] When the end section 111 with one or two such setbacks RS is machined with springback, the end section 111 is still within the target profile which is not shown, i.e. within the tolerance range. This is because, according to the machining setting, the tool removes more material than without the setting of the reduced thickness WDr or without the formation of the setback RS.

[0074] The dimensions of the reduced thickness WDr and of the setback RS are set in dependence on the specific conditions, in particular, as mentioned in the introduction, in dependence on the mechanical properties of the scroll wall to be manufactured and on the machining parameters of the machine tool, in particular the pressure which the tool 119, see Fig. 8, exerts on the inner side 115 or on the outer side 117 of the scroll wall 69, 49 during machining.

[0075] BRIEF DESCRIPTION OF DRAWINGS 11 stationary scroll member, scroll housing 13 movable scroll member, mobile scroll 15 axis of rotation 17 drive shaft 17a shaft shoulder 19 eccentric section 21 motor rotor 23 motor stator 25 front bearing location (fixed bearing) 27 rear bearing location (floating bearing) 29 front counterweight 31 rear counterweight 33 sleeve element 34 intermediate element 41 pump housing 43 electronics housing 49 scroll wall of the fixed scroll member 51 scroll base 53 carrier 67 inlet 69 scroll wall of the movable scroll member 70 scroll groove 71 scroll base 73 carrier 75 sealing element 77 inlet flange 83 center screw 87 pressure element 89 bellows 91 flange bearing 93 pressure plate 94 mating gasket 95 fan 97 positioning pin 99 wave spring 103 motor end cap 105 shroud 111 end section 111a extension 112 transition zone 113 upstream section 115 inner side 117 outer side 119 knife 121 axis of rotation 123 groove 127 ideal position of the end section 128 tolerance limit 129 actual position of the end section 130 original position of the inner side 131 target profile 133 radially outer tolerance limit 135 radial inner tolerance limit 137 measured inner side 139 critical area 141 spring-induced "interference" WDr reduced thickness WD thickness RS retreat L length

Claims

1. A scroll vacuum pump, comprising: a pump system comprising a fixed scroll part (11) and a movable scroll part (13) forming an effective pumping cooperation with the fixed scroll part; a drive shaft (17) which, in operation, rotates about a rotation axis (15) and has an eccentric section (19) for driving the movable scroll part (13); and an electric drive motor (21, 23) for the drive shaft (17), wherein the movable scroll part (13) comprises: a scroll device consisting of a scroll wall (69), a scroll groove (70) defined by the scroll wall (69), and a scroll base (71) formed by the bottom of the scroll groove (70); and a carrier (73) cooperating with the eccentric section (19) of the drive shaft (17) and for the scroll device; wherein the fixed scroll part (11) comprises: a scroll device consisting of a scroll wall (49) and a scroll base (51); and a carrier (53) for the scroll device, wherein at least one scroll wall (69, 49) has a reduced thickness (WDr) at a free end section (111), which is smaller than the thickness (WD) of a section (113) of the scroll wall (69, 49) upstream of and transitioning to the free end section (111).

2. A scroll vacuum pump, comprising: a pump system comprising a fixed scroll part (11) and a movable scroll part (13) forming an effective pumping cooperation with the fixed scroll part; a drive shaft (17) which, in operation, rotates about a rotation axis (15) and has an eccentric section (19) for driving the movable scroll part (13); and an electric drive motor (21, 23) for the drive shaft (17), wherein the movable scroll part (13) comprises: a scroll device consisting of a scroll wall (69), a scroll groove (70) defined by the scroll wall (69), and a scroll base (71) formed by the bottom of the scroll groove (70), and a carrier (73) cooperating with the eccentric section (19) of the drive shaft (17) and for the scroll device; wherein the fixed scroll part (11) comprises: a scroll device consisting of a scroll wall (49) and a scroll base (51), and a carrier (53) for the scroll device, wherein at least one scroll wall (69, 49) has a free end section (111) which forms a setback (RS) with respect to a section (113) of the scroll wall (69, 49) upstream of and transitioning to the free end section (111) on its radially outer side and / or radially inner side.

3. The scroll vacuum pump of claim 1 or 2, wherein, The reduced thickness (WDr) of the free end section (111) is smaller than the thickness (WD) of the upstream section (113) over the entire wall height, and / or the setback (RS) extends along the entire wall height of the free end section (111).

4. The scroll vacuum pump of any of the preceding claims, wherein, The reduced thickness (WDr) of the free end section (111) is constant over the entire wall height, and / or the setback (RS) is constant over the entire wall height of the end section (111).

5. The scroll vacuum pump of any one of claims 1 to 3, wherein, The reduced thickness of the free end section (111) gradually decreases from the scroll base (71) towards the top end of the scroll wall (69, 49), in particular, the free end section (111) of the scroll wall (69, 49) has the same thickness (WD) as the upstream section (113) at the scroll base (71), and / or the setback (RS) of the free end section (111) gradually decreases from the top end of the scroll wall (69, 49) towards the scroll base (71), in particular, the setback (RS) is zero at the scroll base (71).

6. The scroll vacuum pump of any one of the preceding claims, wherein, The free end section (111) has a setback (RS) relative to the upstream section (113) on both its radially inner side (115) and radially outer side (117), or the free end section (111) has a setback (RS) relative to the upstream section (113) only on its radially inner side (115).

7. The scroll vacuum pump according to any one of the preceding claims, wherein the scroll wall (69) is manufactured by machine tooling with a rotating tool (119), in particular a milling tool, which is pressed towards the radially inner side (115) or radially outer side (117) of the scroll wall (69, 49) to be manufactured during machining, in particular, the tool (119) is guided along a predefined path during machining, which path defines the reduced thickness and / or setback (RS) at the free end section (111) of the scroll wall (69, 49).

8. The scroll vacuum pump of claim 7, wherein, A target profile of the scroll wall (69, 49) is predefined in at least one plane perpendicular to the rotational axis (15) of the drive shaft (17), and the guide path of the tool (119) is set such that the free end section (111) of the scroll wall (69, 49) which is deflected by the tool (119) during machining and springs back after machining is kept within the target profile.

9. A scroll vacuum pump according to any one of the preceding claims, wherein, Both the movable scroll member (13) and the stationary scroll member (11) are made of aluminum or an aluminum-containing material.

10. A scroll vacuum pump according to any one of the preceding claims, wherein, The reduced thickness (WDr) of the free end section (111) is 85% to 98%, in particular 92% to 95%, of the thickness (WD) of the upstream section (113); or the reduced thickness (WDr) of the free end section (111) is 0.1 mm to 0.3 mm smaller than the thickness (WD) of the upstream section (113), and / or the setback (RS) of the free end section (111) is between 0.05 mm and 0.2 mm.

11. A scroll vacuum pump according to any one of the preceding claims, wherein, The length (L) of the free end section (111) measured along the course of the scroll wall (69, 49) is between 3 mm and 10 mm.

12. A method for manufacturing a scroll vacuum pump according to any of the preceding claims or a method for manufacturing a scroll component (13, 11) of a scroll vacuum pump according to any of the preceding claims, wherein, The scroll wall (69, 49) is produced by machine tooling with a rotating tool (119), in particular a milling tool, which is pressed against the radially inner side (115) or the radially outer side (117) of the scroll wall (69, 49) to be produced during machining.

13. The method of claim 12, wherein, The tool (119) is guided along a predefined path during machining, which path specifies a reduced thickness and / or a setback (RS) at the free end section (111) of the scroll wall (69, 49).

14. The method of claim 12 or 13, wherein, The target contour of the scroll wall (69, 49) is provided in at least one plane perpendicular to the axis of rotation (15) of the drive shaft (17), and the guide path of the tool (119) is set such that the free end section (111) of the scroll wall (69, 49), which is deflected by the tool (119) during machining and springs back after machining, is kept within the target contour.

15. The method of any one of claims 12-14, wherein, Different dimensional tolerances are specified for the reduced thickness (WDr) and / or the setback (RS) of the free end section (111) and for the thickness (WD) of the upstream section (113), in particular a dimensional tolerance of ±0.1 mm, in particular ±0.01 mm to ±0.06 mm.

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