Scroll pump with improved access to suction area for mounting purposes

Abstract

The present invention relates to a scroll pump comprising a housing and an orbiter located in the housing, the orbiter having a carrier plate and a spiral extending from the carrier plate. Several through-holes are formed in the carrier plate, through which a housing area located on one side of the carrier plate facing away from the spiral of the orbiter is accessible to a tool for assembly purposes.

Description

[0001] The present invention relates to a scroll pump according to the preamble of claim 1, as is known in its type, for example, from US 6 123 517 A. A scroll pump of comparable type is also disclosed in US 10 221 852 B2.

[0002] Further prior art can also be found in the documents EP 3 153 708 B1 and EP 3 647 599 B1.

[0003] A scroll pump is a positive displacement pump that compresses against atmospheric pressure and can be used, among other things, as a compressor. A scroll vacuum pump can be used to create a vacuum in a chamber connected to the gas inlet.

[0004] Scroll vacuum pumps are also known as spiral vacuum pumps or spiral conveying devices. The pumping principle underlying a scroll pump is generally well known in the art and will therefore only be briefly explained below.

[0005] A pumping stage of a scroll pump has two nested or inserted into one another, for example Archimedean spiral cylinders, which are also referred to simply as spirals below. Each spiral cylinder consists of at least one equidistant spiral wall with a support plate provided on one end face of the spiral wall, wherein the outer turns of the spiral cylinder, for example the two or three outermost turns of the spiral cylinder, can be formed by wall sections that are each at a constant distance in the circumferential direction from the center of the spirals. Even if these wall sections do not strictly speaking form spiral sections, in the context of the present invention they are attributed to the spiral and referred to as turns thereof.

[0006] The spiral cylinders are nested in such a way that the two spiral cylinders enclose crescent-shaped or sickle-shaped volumes in sections. One of the two spirals is immobile or fixed in the pump housing, whereas the other spiral, along with its support plate, can be moved along a circular path via an eccentric drive, which is why this spiral, together with its support plate, is also referred to as an orbiter. The movable spiral thus performs a so-called centrally symmetric oscillation, which is also referred to as "wobbling" or "orbiting." A crescent-shaped volume enclosed between the spiral cylinders migrates increasingly inward within the spirals as the movable spiral orbits. This moving volume transports process gas from a radially outer gas inlet radially to a gas outlet located in the center of the spiral.

[0007] The eccentric drive or its eccentric shaft is located in the pump housing on the side of the carrier plate facing away from the orbiter's spiral and is surrounded by a deformable sleeve, such as a bellows, which serves both to seal the drive from the intake area and to prevent the orbiter from rotating, as it could otherwise rotate on its own without a rotation lock. To ensure this rotation lock, the sleeve or bellows is connected to the carrier plate at a first end, while the second end of the sleeve or bellows, opposite the first end, is screwed to the housing base inside the housing using several fasteners.

[0008] The assembly consisting of the orbiter and the bellows is pre-assembled during the pump assembly so that the assembly in question can then be inserted into the pump housing as a unit, after which the second end of the sleeve or the bellows must be screwed to the base of the housing using the fastening means in question.

[0009] Since a circumferential annular gap is formed between the orbiter and in particular its carrier plate and the housing, a corresponding tool can be guided through this gap into the intake area up to the fastening means in question in order to be able to screw these to attach the second end of the sleeve to the housing base.

[0010] To improve the suction capacity of existing scroll vacuum pumps, it is desirable for the orbiter, and especially its carrier plate, to have the largest possible diameter. However, this results in the annular gap between the carrier plate and the pump housing being too small to allow a tool to be inserted into the suction area of ​​the pump to actuate the fastening devices in the manner described above.

[0011] The invention is therefore based on the object of improving access to the suction area for assembly purposes in a generic scroll pump.

[0012] This object is achieved with a scroll pump, in particular a scroll vacuum pump, having the features of claim 1 or those of claim 12.

[0013] According to claim 1, the object is achieved in particular by forming a first, a second, and at least one third through-opening in the carrier plate, which are arranged evenly distributed in the circumferential direction around the center of the spiral. For example, the through-openings can be located on a circle concentric with the center of the spiral and can be evenly spaced from one another in the circumferential direction. The distance from the first through-opening to the second through-opening is thus equal to the distance from the second through-opening to the third through-opening.

[0014] Even if more than three through-openings are formed in the carrier plate, these can be equally spaced from one another in the circumferential direction. By forming a plurality of through-openings in the carrier plate, the fastening means for attaching the second end of the sleeve to the housing base are particularly easily accessible. The fastening means are distributed around the circumference of the sleeve, so that not all fastening means are accessible from one and the same through-opening using a corresponding tool. However, by also arranging the through-openings at a distance from one another in the circumferential direction in the manner according to the invention, easier access to all fastening means is created.

[0015] When dimensioning the orbiter, it is therefore not necessary to consider whether the annular gap between the carrier plate and the pump housing is large enough to allow a tool to be passed through it to attach the sleeve or bellows to the housing base. Rather, to improve the suction capacity, the orbiter's carrier plate can be dimensioned so large that it does not collide with the inner wall of the pump housing during its orbiting movement, without this complicating the installation of the sleeve or bellows, since this can be achieved in the manner according to the invention through the through-openings specially designed in the carrier plate, which is why these can also be referred to as installation openings.

[0016] Preferred embodiments of the invention will now be discussed below. Further embodiments may also emerge from the dependent claims, the description of the figures, and the drawings themselves.

[0017] To allow a tool to be guided through the through-opening for assembly purposes past the corrugated bellows located on the side of the carrier plate facing away from the orbiter's spiral, one embodiment may provide for the through-openings in the carrier plate to be formed between radially successive turns of the spiral, particularly between the two outermost turns. Under certain circumstances, it may even be expedient to form the through-openings radially outside the outermost turn of the spiral in the carrier plate.

[0018] According to a further embodiment, it can be provided, in particular, that the number of fastening means corresponds to the number of through-holes in the support plate. Thus, each fastening means is assigned a through-hole aligned with it, so that each fastening means can be easily accessed and operated using a tool without the risk of the tool slipping off the fastening means due to an undesired tilt or misalignment of the tool.

[0019] As previously explained, the through-openings in the support plate are provided in the manner according to the invention because, with sufficiently large dimensions of the orbiter or its support plate, the annular gap between the support plate and the pump housing is too small to allow a tool to be inserted through the annular gap into the pump's intake area. However, reducing the size of the annular gap also means that the process gas from the intake area can no longer flow completely unhindered past the support plate into the pump stage.

[0020] Accordingly, according to a further embodiment, it can be provided that an indentation or recess is formed in the peripheral edge of the carrier plate, through which the process gas can be sucked from the intake area in the axial direction directly into the pumping stage. According to a preferred embodiment, it can be provided, in particular, that the indentation in question merges into one of the through-openings. The through-opening in question thus merges into the indentation in the radial direction, so that, in a sense, a particularly large assembly opening is created, through which even difficult-to-access areas in the intake area are accessible for maintenance or assembly purposes.

[0021] Since the assembly tool must be inserted through the orbiter's spiral into the through-hole, the maximum possible inclination of the tool is limited by the wall height of the spiral. To ensure that the fastening means are nevertheless accessible through the through-holes for assembly purposes in the desired manner, according to a further embodiment, each of the through-holes can be formed at a respective location on the carrier plate, which is selected such that an imaginary straight line on which a through-hole and the fastening means closest to this through-hole lie does not have an intersection point with the orbiter's spiral. For the purpose of actuating the fastening means, a tool can thus be guided through the through-holes without colliding with the orbiter's spiral.

[0022] Since the process gas transported through the orbiter tends to flow back into the intake area, particularly through the through-openings formed in the support plate, a further embodiment may provide for each through-opening, except for the one into which the aforementioned indentation merges, to receive a closure element, such as a screw, that seals the respective through-opening. The closure elements can, for example, be screwed into the respective through-openings to seal them, so that process gas already compressed by the pumping stage cannot flow back through the through-openings into the intake area of ​​the pump.

[0023] According to a further embodiment, in addition to the design of the carrier plate with at least one through-opening, the housing can have at least three radial bulges at a location radially outside the orbiter, through which the housing region located on the side of the carrier plate facing away from the spiral of the orbiter is accessible to a tool for assembly purposes. For example, the housing can have a rectangular and, in particular, a square cross-sectional shape in a radial plane in which the carrier plate of the orbiter is located, so that the bulges in question are formed by the corners of the rectangle radially outside the carrier plate.

[0024] Since process gas can also flow back into the suction area of ​​the pump through the bulges in question, it can be provided according to a further embodiment that a closure body designed complementary to the respective bulge is detachably fitted into each bulge.

[0025] Like the through-holes in the support plate, the recesses can also be evenly spaced from one another, so that, for example, the distance from a first recess to a second recess is the same as the distance from the second recess to a third recess. Thus, all areas of the pump's intake area are equally accessible through the recesses in question.

[0026] Since the fastening means for attaching the second end of the sleeve to the housing base are provided at equal distances around the sleeve, it may be appropriate according to a further embodiment that the number of bulges is the same as the number of fastening means, so that each fastening means is assigned a bulge through which the respective fastening means is accessible for assembly purposes by means of a suitable tool.

[0027] However, in the case where the carrier plate is formed with an indentation on its peripheral edge, which facilitates the flow of process gas into the orbiter, it may be sufficient in this case for the number of indentations to be one less than the number of fastening means, since one of the fastening means is accessible through the indentation of the carrier plate.

[0028] As previously explained, it may be advantageous to place the through holes radially outside the outermost turn of the spiral in the carrier plate. If the distance between a through hole and the center of the spiral is increased even further, the through hole can even merge into the peripheral edge of the carrier plate. In this case, the through hole does not have a circumferential edge, but rather opens toward the peripheral edge of the carrier plate and merges into it.

[0029] According to one embodiment of the present invention, in addition to or as an alternative to the design of the carrier plate with a plurality of through-openings in the carrier plate, it is provided that an indentation is formed in the peripheral edge, which can be used as an assembly opening through which the housing area, which is located on a side of the carrier plate facing away from the spiral of the orbiter, is accessible to a tool for assembly purposes.

[0030] According to a specific embodiment, it can be provided that the spiral comprises a plurality of consecutive turns in the radial direction, wherein the indentation comprises a circumferential section that is located radially outside the outermost turn of the spiral and extends in the circumferential direction with respect to the center of the spiral over an arc angle of between 10° and 30°, in particular between 15° and 25° and preferably between 18° and 22°. If it is mentioned here that the circumferential section is located radially outside the outermost turn of the spiral, this means that the circumferential section is flanked on its radially inner side by a section of the outermost turn of the spiral.Due to the fact that the circumferential section extends over a relatively large arc angle in the circumferential direction, any section of the housing area located on a side of the carrier plate facing away from the orbiter's spiral is accessible for assembly purposes. Furthermore, the circumferential section allows the process gas to be drawn axially from the intake area directly into the pump stage, thus ensuring minimal flow losses.

[0031] In order to further improve both the accessibility of the intake area and the access of process gas into the pumping stage, it can be provided according to a further embodiment that the indentation comprises a radial section into which the circumferential section merges at one end and which extends from the circumferential edge of the carrier plate in the radial direction inwards to beyond the outermost turn of the spiral, which means that the outermost turn of the spiral is interrupted by the radial section in the region of the same.

[0032] In the following, the invention will now be described purely by way of example with reference to the drawings in which: Fig. 1 shows a conventional scroll vacuum pump in a sectional view; Fig. 2 shows a plan view of the orbiter in a scroll vacuum pump designed according to the invention; and Fig. 3 shows a sectional view of the section of the scroll vacuum pump of the Fig. 3 according to the cutting line RR.

[0033] The Fig. 1 shows a vacuum pump designed as a scroll pump 10. This comprises a first housing element 12 and a second housing element 14 connected to it via screws 15, wherein the second housing element 14 has a pumping-active structure, namely a fixed spiral wall 16. The second housing element 14 thus forms a fixed spiral component of the scroll vacuum pump 10. The spiral wall 16 interacts with a spiral wall 18, which is formed on a movable support plate 20 and, together with the latter, forms the orbiter 21 of the scroll vacuum pump 10, which is driven eccentrically via an eccentric shaft 22 to generate a pumping effect. A process gas to be pumped is conveyed from an inlet 24, which is defined in the first housing element 12, to an outlet 26, which is defined in the second housing element 14.

[0034] As in particular the Fig. 2 As can be seen, in the embodiment shown here, the outer two turns 19 of the spiral wall 18 are formed by wall sections which are each at a constant distance in the circumferential direction from the center of the spirals 18. Even though these wall sections therefore do not strictly speaking form spiral sections, in the context of the present invention they are attributed to the spiral 18 and referred to as turns 19 thereof. However, the principles of the present invention apply equally to embodiments in which the spiral turns expand continuously from the center of the spiral towards their free end.

[0035] The eccentric shaft 22 is driven by an electric motor 28 and supported by two roller bearings 30. The eccentric shaft 22 comprises an eccentric pin 32 arranged eccentrically to its rotational axis, which transmits its eccentric deflection to the movable spiral component 20 via another roller bearing 34.

[0036] To seal the drive, a seal in the form of a Fig. 1 The bellows 36 is attached to the left-hand first end, the right-hand second end of which is attached to the housing base of the first housing element 12. The left-hand first end of the bellows 36 follows the deflection of the movable support plate 20. The bellows 36 surrounding the eccentric shaft 22 is flexible, but inherently torsionally rigid, and thus, due to the fact that it is attached to the support plate 20 on the one hand and to the first housing element 12 on the other, prevents the support plate 20 or the orbiter 21 from rotating about itself.

[0037] The scroll vacuum pump 10 further comprises a fan 38 for generating a cooling air flow 46. An air guide hood 40 is provided for this cooling air flow 46, to which the fan 38 is also attached. The air guide hood 40 and the housing elements 12 and 14 are shaped such that the cooling air flow 46 flows substantially around the entire pump housing, thus achieving good cooling performance.

[0038] The scroll vacuum pump 10 further comprises an electronics housing 42, in which a control device and power electronics components for driving the motor 28 are arranged. The electronics housing 42 also forms a base for the pump 10. A channel 44 is formed between the electronics housing 42 and the first housing element 12, through which the air flow 46 generated by the fan 38 is guided along the first housing element 12 and also along the electronics housing 42, so that both are effectively cooled.

[0039] As already mentioned, the right-hand second end of the bellows 36 is fastened to the housing base of the first housing element 12 by means of several fastening elements 50 which are arranged at equal distances around the bellows 36, see Fig. 3 . Since the assembly consisting of orbiter 21 and bellows 36 is pre-assembled during pump assembly and subsequently inserted as a unit into the first housing element 12, the fastening elements 50 in question must be accessible for an assembly tool in order to be able to attach them to the housing base of the first housing element 12. Since the Fig. 1 In the scroll vacuum pump 10 shown, a sufficiently large annular gap 23 is formed between the orbiter 21, in particular its carrier plate 20, and the first housing element 12, a corresponding tool can be inserted through this gap into the suction area 48 to the fastening means in question (in the Fig. 1 not shown) in order to be able to screw them to the base of the housing in order to attach the second end of the bellows 36.

[0040] In the Fig. 3 However, in the scroll vacuum pump 10 shown, the diameter of the support plate 20 has a diameter so large that the annular gap 23 between the support plate 20 and the first housing element 12 is too small to allow a tool to be inserted into the suction area 48 for actuating the fastening means 50 in the manner described above. Furthermore, in the case of the pump, the Fig. 3 the remaining annular gap 50 is covered by a circumferentially extending web 52 which is formed on the inside of the first housing element 12.

[0041] In order to still have access to the suction area 48 and in particular to the fastening means 50 for assembly purposes, it is therefore provided according to the invention that a plurality of through openings 54 are formed in the carrier plate 20, through which the suction area 48, which is located on the side of the carrier plate 20 facing away from the spiral 18 of the orbiter 21, is accessible to a tool for assembly purposes.

[0042] As in particular the Fig. 1 can be seen, in the embodiment shown there, a total of four through openings 54 are formed in the carrier plate 20, which are arranged uniformly distributed in the circumferential direction around the center of the spiral 16. If it is mentioned here that the through openings 54 are arranged uniformly distributed in the circumferential direction around the center of the spiral 16, this means that the through openings 54 are spaced from one another by the same radian measure or by the same arc angle α with respect to the center of the spiral 16, for which the following applies for a number of n through openings: α = 360° / n.

[0043] Again Fig. 1 can further be removed, an indentation 56 or recess is formed in the peripheral edge of the carrier plate 20, through which the process gas can be sucked from the intake region 48 into the orbiter 21. In the embodiment shown here, the indentation 56 in question merges into one of the through-openings 54. Alternatively, however, the indentation 56 can also be formed on the peripheral edge of the carrier plate 20 at a location between two through-openings 54. Since, due to the special shape of the indentation 56, all areas of the intake region 48 are accessible for assembly purposes, the formation of the through-openings 54 in the carrier plate 20 can also be dispensed with under certain circumstances.

[0044] Again Fig. 2 can be removed, the indentation 56 comprises a circumferential section 64 which is located radially outside the outermost turn 19 of the spiral 18 and which extends in the circumferential direction with respect to the center of the spiral over an arc angle of approximately 20°. The circumferential section 64 extends radially inwards as far as the outermost turn 19 of the spiral 18, wherein it is flanked radially inside by a cut of the outermost turn 19 of the spiral 18. Due to the fact that the circumferential section 64 extends in the circumferential direction over a relatively large arc angle, any section of the suction region 48 is accessible to a tool for assembly purposes through this circumferential section 64, which is why the through openings 54 are not absolutely necessary in this case.

[0045] In order to further improve the accessibility of the intake region 48, the indentation 56 in the embodiment shown here further comprises a radial section 66, into which the circumferential section 64 merges at one end and which extends from the circumferential edge of the carrier plate 20 in the radial direction inwards to beyond the outermost turn 19 of the spiral 18, for which purpose the outermost turn 19 is interrupted in the region of the radial section 66.

[0046] Since the fastening means 50 for attaching the second end of the corrugated bellows 36 are arranged distributed around the circumference of the corrugated bellows 36, the number of through-openings 54 corresponds to the number of fastening means 50. Thus, in a sense, each fastening means 50 is assigned a through-opening 54. In particular, the through-openings 54 are aligned with the fastening means 50 assigned to them in such a way that an imaginary straight line 58 (see the Fig. 3 ), on which a through-hole 54 and the fastening means 50 closest to it are located, has no intersection point with the spiral 18 of the orbiter 21. Thus, along the Fig. 3 A tool can be guided through the through-opening 54 to the fastening means 50 along the straight line 58 shown in order to be able to screw these to the housing base of the first housing element 12.

[0047] To prevent the process gas from flowing back into the intake area 48 through the through openings 54, the through openings 54 are closed by means of suitable closure elements 60, which can be, for example, screw elements screwed into the through openings 54.

[0048] In addition or alternatively to the through-openings 54, it can be provided that the first housing element 12 has radial bulges 62 at a location radially outside the orbiter 21, as shown in the Fig. 2 are indicated schematically in dashed lines. These bulges 62 also ensure access to the intake area 48, which is located on the side of the carrier plate 20 facing away from the spiral 18 of the orbiter 21.

[0049] In the embodiment shown here, the first housing element 12 has only three bulges 62, which are spaced apart from one another by an arc angle of 90° in the circumferential direction and are thus located at the half-past-five, half-past-eight, or half-eleven o'clock position of the carrier plate 20, since the intake region 48 is accessible in the region of the half-past-two o'clock position through the indentation 56 provided there on the peripheral edge of the carrier plate 20. However, if such an indentation is not provided or is provided at a different location, the first housing element 12 can also have a corresponding bulge 62 at the half-past-two o'clock position in order to gain access to the corresponding areas of the intake region 48.

[0050] In principle, the number of protrusions 62 corresponds to the number of fastening elements 50 for attaching the second end of the bellows 36 to the housing base; however, on the outer peripheral edge of the carrier plate 20 according to the illustration of the Fig. 2 an indentation 56 is formed, it may be sufficient if the number of bulges is 1 less than the number of fastening means 50, since the indentation 56 on the peripheral edge of the carrier plate 20 allows access to that fastening means 50 which is not accessible through the three bulges 62. Bezugszeichenliste

[0051] 10Scroll vacuum pump 12First housing element 14Second housing element 15Screws 16Spiral wall / spiral 18Spiral wall / spiral 19Turnings 20Carrier plate 21Orbiter 22Eccentric shaft 23Annular gap 24Inlet 26Outlet 28Motor 30Rolling bearing 32Eccentric pin 34Rolling bearing 36Bellows 38Fan 40Air guide hood 42Electronics housing 44Duct 46Air flow 48Intake area 50Fastening element 52Web 54Through opening 56Indentation 58Straight line 60Closing element 62Bulge 64Circumferential section 66Radial section

Claims

1. A scroll pump, in particular a scroll vacuum pump (10), comprising a housing (12, 14) and an orbiter (21) which is located in the housing (12) and which has a carrier plate (20) and a spiral (18) extending from the carrier plate (20), wherein, in the carrier plate (20), a plurality of passage openings (54) are formed through which a housing region (48), which is located on a side of the carrier plate (20) facing away from the spiral (18) of the orbiter (21), is accessible for a tool for assembly purposes, characterized in that a first, a second and at least a third passage opening (54) are formed in the carrier plate (20) and are arranged uniformly distributed in the peripheral direction around the center of the spiral (18).

2. A scroll pump according to claim 1, characterized in that the spiral comprises a plurality of windings, with the passage openings (54) in the carrier plate (20) being formed between windings following one another in the radial direction, in particular between the two outermost windings.

3. A scroll pump according to claim 1 or 2, characterized in that the carrier plate (20) has a peripheral margin, with an indentation (56) being formed in the peripheral margin.

4. A scroll pump according to claim 3, characterized in that the indentation (56) transitions into one of the passage openings (54).

5. A scroll pump according to at least one of the preceding claims, characterized in that the scroll pump further comprises, within the housing (12) on the side of the carrier plate (20) facing away from the spiral (18) of the orbiter (21), an eccentric shaft (22) drive-effectively connected to the carrier plate (20) and a deformable sleeve, in particular in the form of a corrugated bellows (36), which surrounds the eccentric shaft (22) and which is connected to the carrier plate (20) at a first end, with the sleeve being attached to the housing (12) at a second end disposed opposite the first end by means of a plurality of fastening means (50) which are uniformly spaced apart from one another in the peripheral direction and whose number corresponds to the number of passage openings (54).

6. A scroll pump according to claim 5, characterized in that each of the passage openings (54) is formed at a respective position of the carrier plate (20) that is selected such that a straight line (58), on which a passage opening (54) and the fastening means (50) disposed closest to this passage opening (54) lie, does not have a point of intersection with the spiral (18) of the orbiter (21).

7. A scroll pump according to at least one of the preceding claims, characterized in that each passage opening (54) releasably receives a closure element (60) sealing the respective passage opening (54), in particular a screw element which is screwed into the passage opening (54).

8. A scroll pump according to at least one of the preceding claims, characterized in that, in addition to the design of the carrier plate (20) with at least three passage openings (54), it is provided that the housing (12) has at least three bulges (62) at a position radially outside the orbiter (21), through which bulges (62) the housing region (48), which is located on the side of the carrier plate (20) facing away from the spiral (18) of the orbiter (21), is accessible for a tool for assembly purposes.

9. A scroll pump according to claim 8, characterized in that the spacing from a first bulge (62) to a second bulge (62) is equal to the spacing from the second bulge (62) to a third bulge (62).

10. A scroll pump according to claim 8 or 9, characterized in that the scroll pump further comprises, within the housing (12) on the side of the carrier plate (20) facing away from the spiral (18) of the orbiter (21), an eccentric shaft (22) drive-effectively connected to the carrier plate (20) and a deformable sleeve, in particular in the form of a corrugated bellows (36), which surrounds the eccentric shaft (22) and which is connected to the carrier plate (20) at a first end, with the sleeve being attached to the housing (12) at a second end disposed opposite the first end by means of a plurality of fastening means (50) which are uniformly spaced apart from one another in the peripheral direction and whose number is equal to or one greater than the number of bulges (62).

11. A scroll pump according to at least one of the claims 8 to 10, characterized in that a closure body formed complementary to the respective bulge (62) is releasably fitted into each bulge (62).

12. A scroll pump, in particular a scroll vacuum pump (10), comprising a housing (12, 14) and an orbiter (21) which is located in the housing (12) and which has a carrier plate (20) and a spiral (18) extending from the carrier plate (20), characterized in that the carrier plate (20) has a peripheral margin, with an indentation (56) being formed in the peripheral margin, through which indentation (56) a housing region (48), which is located on a side of the carrier plate (20) facing away from the spiral (18) of the orbiter (21), is accessible for a tool for assembly purposes.

13. A scroll pump according to claim 12, characterized in that the spiral (18) comprises a plurality of windings (19), with the indentation (56) comprisig a peripheral section (64) which is located radially outside the outermost winding (19) of the spiral (18) and which extends in the peripheral direction with respect to the center of the spiral (18) over an arc angle of between 10° and 30°, in particular between 15° and 25° and preferably between 18° and 22°.

14. A scroll pump according to claim 13, characterized in that the indentation (56) comprises a radial section (66) which extends inwardly in the radial direction from the peripheral margin of the carrier plate (20) to over the outermost winding (19) of the spiral (18).

Images