Scroll compressor

Abstract

The invention relates to a scroll compressor (1) that can be operated without lubricating oil and comprises a housing (9), which has a base plate (7) fixed to the housing and a movable base plate (8), on which base plates a spiral (2) fixed to the housing and a spiral (3) movable with the movable base plate (8) are respectively formed, protruding in the axial direction; in said scroll compressor the two spirals (2, 3) are arranged such that they radially and axially engage in each other, wherein the two spirals (2, 3) each have a spiral wall (11, 15) running in a plurality of spiral windings (12a, 12b, 16a, 16b), wherein the movable spiral (3) is movable by means of an eccentric drive (4) into an orbital path leading around the spiral (2) fixed to the housing, wherein spiral passages (17a, 17b, 17c, 17d) formed between the two spiral walls (11, 15) narrow continuously during operation of the scroll compressor, and in said scroll compressor the spiral walls (11, 15) can make contact in some sections as a result of the design of the scroll compressor or the way it is operated. According to the invention, at least one wall section (19a, 19b, 19c, 19d, 20a, 20b, 20c, 20d) of at least one of the two spiral walls (11, 15), in which a potential contact region (18a, 18b, 18c, 18d) of the two spiral walls lies, is geometrically modified in such a way that any contact between the two spiral walls (11, 15) or at least any increase in the frictional force between the two spiral walls in said wall section is ruled out.

Description

[0001] spiral compressor

[0002] The invention relates to a lubricating oil-free spiral compressor with a housing comprising a housing-fixed base plate and a movable base plate, on which a housing-fixed spiral and a spiral movable with the movable base plate are formed, respectively, projecting axially, wherein the two spirals are arranged so that they interlock radially and axially, wherein each of the two spirals has a spiral wall extending in several spiral turns, wherein the movable spiral can be moved by means of an eccentric drive into an orbital path leading around the housing-fixed spiral, wherein spiral channels formed between the two spiral walls continuously narrow during operation of the spiral compressor, and wherein the spiral walls can touch section by section due to design and / or operational reasons.

[0003] Spiral compressors, also known as scroll compressors, are available in various designs. In vehicles, for example, they are used as air compressors for compressed air supply systems or for compressing refrigerants in air conditioning systems. In a common design, two spirals are arranged interlocking, one of which is movable and orbits the other, stationary spiral. For this purpose, the orbiting spiral can be deflected in a plane perpendicular to a geometric center axis by means of an eccentric arrangement, without rotating around its own longitudinal axis. During operation, the two spirals mesh with each other, with the spiral channels formed between them becoming progressively narrower. As a result, with a rotational movement of the drive, a fluid drawn in or supplied from the outside is increasingly compressed within these spiral channels, and the compressed fluid is discharged through a central outlet.To minimize pressure losses during the compression process of the spiral compressor, the nested spirals are arranged so closely together that the spiral walls, which are movable relative to each other, come very close to one another during orbital motion and the formation of the fluid-carrying spiral channels, at least in sections of the spiral turns, so that they just barely touch or just barely do not touch in these areas. Such spiral compressors exhibit high efficiency and have proven their worth many times over.

[0004] However, it has been observed that undesirable wear marks can form on certain wall areas of such spiral compressors. These wear marks can occur when the spiral walls of the moving spirals are pressed together at relatively high pressures in the relevant contact areas, resulting in significant frictional forces acting on the wall surfaces during the relative movement of the spirals. These frictional forces arise primarily from the thermal expansion of the spiral walls due to the compressor heating up considerably during compression operation. However, they can also be exacerbated by unfavorable manufacturing tolerances, material deformation caused by high centrifugal forces and / or high fluid pressures, as well as by wear on the shafts and bearings of the eccentric drive. The consequence is disruptive wear of the spiral walls on one or more of the affected wall sections.

[0005] From DE 10 2021 210 295 A1, a scroll compressor for compressing a refrigerant in a refrigerant circuit of a motor vehicle air conditioning system is known. The scroll compressor has a housing-mounted scroll and an orbiting scroll surrounding it, which are axially and radially nested within one another. The scroll walls of the scrolls form several conveying chambers between the partially contacting spiral walls for compressing a mixture of refrigerant and oil. The oil serves to lubricate the two scrolls, thus reducing friction and consequently increasing the efficiency of the scroll compressor.

[0006] In certain applications, lubrication of the spiral wall contact surfaces is possible if the fluid being conveyed has a certain lubricity. This is possible, for example, in cooling circuits of compressors with mixtures of refrigerants and oil, but not, or at least not without significant additional effort, in a compressed air supply system where the goal is to produce compressed air that is as oil-free and low in moisture as possible.

[0007] Furthermore, many vehicles already feature spiral compressors with cooling devices on one or both spirals or their base plates, which limits the heating and thus the thermal expansion of the spiral walls.

[0008] Nevertheless, even with cooling, undesirable wear marks have appeared on the spiral walls of compact air compressors with high delivery rates, such as those required in many commercial vehicles. This can increase the energy consumption of the spiral compressor over its operating life, while simultaneously reducing efficiency and shortening its maximum service life.

[0009] Against this background, the invention aims to provide a spiral compressor that can be operated without lubricating oil, exhibits low wear during operation, and simultaneously enables high efficiency. In particular, such a spiral compressor should be suitable for generating compressed air in a motor vehicle.

[0010] The solution to this problem arises from the features of the independent claim, while advantageous embodiments and further developments of the invention can be derived from the associated dependent claims.

[0011] The invention therefore relates to a lubricating oil-free spiral compressor with a housing which has a housing-fixed base plate and a movable base plate, on which a housing-fixed spiral and a spiral movable with the movable base plate are formed projecting in the axial direction, in which the two spirals are arranged so that they interlock radially and axially, wherein the two spirals each have a spiral wall extending in several spiral turns, wherein the movable spiral can be moved by means of an eccentric drive into an orbital path leading around the housing-fixed spiral, wherein spiral channels formed between the two spiral walls continuously narrow during operation of the spiral compressor, and in which the spiral walls can touch section by section due to design and / or operation.

[0012] To solve the problem posed, this spiral compressor is designed in such a way that at least one wall section of at least one of the two spiral walls, in which a potential contact area of ​​the two spiral walls lies, is geometrically modified in such a way that contact between the two spiral walls or at least an increased frictional force between the two spiral walls in this wall section is excluded.

[0013] A wall section is understood to be a portion of the spiral wall of a spiral compressor. Such a wall section has a radially outer wall side and a radially inner wall side.

[0014] A potential contact area is understood to be an area located radially between the spiral wall of the housing-fixed spiral and the spiral wall of the orbitable spiral, in which the radially outer wall side and the radially inner wall side of the two spiral walls touch or can touch each other.

[0015] The invention solves the described technical problem by incorporating relatively small geometric modifications, such as small recesses or flattening, into the spiral walls in the wear-prone areas. These geometric modifications are sufficient to compensate for effects in the relevant wall sections such as deformation of the spiral walls due to thermal expansion and / or centrifugal forces, material wear in the eccentric drive, or tolerances in the manufacturing and assembly of the components.

[0016] If, due to the typical involute curve of the spiral windings of the spiral walls, one or more localized contact surfaces would exist during the rolling of the orbiting spiral against the housing-fixed spiral, such contact surfaces can be completely avoided or their effect minimized by the formation of suitable localized recesses or the like. At the very least, the invention ensures that no additional increased frictional forces can arise due to the aforementioned adverse effects, and thus no additional wear is generated on the existing contact surfaces.

[0017] If, however, the geometry and arrangement of the spiral walls are designed such that contact is not intended at any point, the invention ensures that contact and thus wear-inducing friction between the spiral walls cannot occur due to the aforementioned adverse effects. The areas of the spiral walls adjacent to the geometric modifications designed according to the invention, i.e., the spiral turns outside said wall sections, can remain structurally unchanged. In other words, the invention essentially comprises a spiral winding construction with geometric modifications to the winding curves in certain areas.

[0018] In any case, the advantage of the virtually wear-free operation of the spiral compressor in the area of ​​its spiral walls outweighs the slight pressure loss resulting from the geometric modifications during the conveying operation of the spiral compressor.

[0019] According to a further development of the described spiral compressor, it can be provided that the at least one geometrically modified wall section has a recess, such as a radially and axially extending flattening, wherein this modified wall section is formed at least on a radially outer wall side of the spiral wall.

[0020] Accordingly, a localized flattening of a coil arc on the wall of one of the two spirals protects a potential contact area, where undesirable abrasion marks would very likely occur without this geometric modification, from such wear. Advantageously, such flattening can be formed on several of the corresponding coil arcs on one or both spirals. Preferably, the recess is formed on the radially outer wall surface of a spiral. Alternatively, such a recess can be formed in the form of a cavity or the like on the radial inner surface of a spiral wall.

[0021] Another embodiment of the spiral compressor provides that the at least one geometrically modified wall section has a radially inwardly directed first chamfer, which begins at the level of the base plate or axially spaced from it on the spiral wall and runs at a first chamfer angle α to a geometric longitudinal axis perpendicular to the base plate.

[0022] In an investigation, traces of wear were found at least at one contact point of the spiral walls of the two spirals of a spiral compressor. These traces did not extend across the entire wall height, but only occurred in a portion of the axial wall height. This area is therefore most susceptible to wear. Such wear marks on the radially outer wall can be specifically prevented by a radially inward chamfering of the spiral wall in the affected area. This chamfering can be advantageously combined with a flattening of the spiral arc. This results in a three-dimensional geometric modification of the spiral wall, providing particularly effective wear protection that is better adapted to the characteristically different wear patterns of the spiral walls in the axial direction.

[0023] According to a further embodiment of the invention, it can be provided that the at least one geometrically modified wall section has a radially inward directed second chamfer and a radially outward directed third chamfer, which begins at the level of the base plate or axially spaced therefrom on the spiral wall, wherein the second chamfer extends at a second angle of inclination β and the third chamfer at a third angle of inclination y to a longitudinal axis perpendicular to the base plate.

[0024] By chamfering the spiral wall radially outwards in the relevant area, such wear marks on the radially inner wall side can be specifically prevented. The two chamfers, i.e., radially inwards and radially outwards, can advantageously be combined, whereby the angle of the chamfer relative to an axis perpendicular to the base plate can differ on the two radial sides of the spiral wall.

[0025] According to another embodiment of the invention, the at least one geometrically modified wall section can be formed at a potential contact area between the two spiral walls, the first of which is in the direction of movement. In a spiral compressor with a housing-fixed spiral and an orbiting, i.e., movable, spiral, a revolution begins with the intake of the fluid to be compressed and ends with the discharge of the fluid compressed in the compressor. Surprisingly, it has been found that the first potential contact area in the direction of travel during a revolution is particularly susceptible to wear. Therefore, it is advantageous that a suitable geometric modification of the spiral wall is formed on the relevant wall section of one of the two spirals. Additional such geometric modifications can be formed on the subsequent contact areas in the direction of movement.

[0026] According to a further embodiment, the at least one geometrically modified wall section can be formed on a radially outer spiral turn of the spiral wall. Investigations have shown that the geometric position of the wear marks between the spiral walls is more likely to occur and be more pronounced on the radially outer spiral turns than on the radially inner spiral turns. Therefore, it is advantageous if a geometric modification is formed on a radially outer spiral turn of at least one of the two spirals in a contact area. Additional geometric modifications can also be formed on the radially inner spiral turns of one or both spirals.

[0027] Finally, the invention also relates to a vehicle, such as a commercial vehicle or a passenger car, with a scroll compressor, for example for generating compressed air in a vehicle's compressed air supply system, which is constructed according to one of the device claims. The invention is further explained below with reference to an embodiment illustrated in the accompanying drawing. The drawing shows

[0028] Fig. 1 shows a simplified longitudinal section through a partial area of ​​a spiral compressor with a housing-fixed spiral and a movable spiral; Fig. 2 shows a schematic cross-sectional view of a spiral compressor according to the prior art.

[0029] Fig. 3 shows a schematic cross-sectional view of a spiral compressor according to the invention.

[0030] Fig. 4 shows a simplified longitudinal section through a partial area of ​​a spiral wall of a spiral compressor according to Fig. 3 with a bevel on one side, and Fig. 5 shows a simplified longitudinal section through a partial area of ​​a spiral wall of a spiral compressor according to Fig. 3 with a bevel on both sides.

[0031] Some components in the figures are identical, so they are designated with the same reference numbers.

[0032] Fig. 1 shows a scroll compressor 1, which has a housing-fixed first scroll 2 and a movable second scroll 3, both arranged in a housing 9, which is shown only in sections. The housing-fixed scroll 2 is integrally mounted on a housing-fixed base plate 7 and is preferably formed integrally with it. The movable scroll 3 is integrally mounted on a movable base plate 8. The two scrolls 2 and 3 are arranged radially and axially nested within one another. The movable base plate 8 and the movable scroll 3 connected to it can be deflected in a plane transverse to a geometric center axis 10 of the scroll compressor 1 by means of an eccentric drive 4, so that the movable scroll 3 performs an orbiting motion around the housing-fixed scroll 2 during operation.The eccentric drive 4 is positively connected to the rotor of an electric drive motor 6 via a drive shaft 5 to drive the movable spiral 3. Such a spiral compressor 1 could, for example, be an electrically driven air compressor in a compressed air supply system of a commercial vehicle. As a cross-sectional view of a known spiral compressor 1.1 shown in Fig. 2 illustrates, the housing-fixed spiral 2 has a first spiral wall 11.1, which extends in a radially outer spiral turn 12a from a radially outer fluid inlet 13 and continues in a radially inner spiral turn 12b to a central fluid outlet 14. The fluid inlet can also be arranged and / or aligned radially or tangentially, i.e., without an axial bore in the housing-fixed base plate 7. Accordingly, the movable spiral 3 has a second spiral wall 15.1, which runs in a radially outer spiral turn 16a and further in a radially inner spiral turn 16b. The two nested spirals 2, 3 intermeshed with each other, with the movable spiral 3 orbiting around the stationary spiral 2. During this orbital movement, four crescent-shaped spiral channels 17a, 17b, 17c, 17d, formed between the spiral walls 11.1, 15.1 in the example shown, narrow, so that when the eccentric drive 4 rotates, fluid drawn in from the outside, for example air, is continuously compressed in the spiral channels 17a, 17b, 17c, 17d, and the compressed fluid, i.e., the compressed air, is discharged through the central fluid outlet 14.

[0033] As can be clearly seen in the known spiral compressor 1.1 shown in Fig. 2, in the present example there are several, in this case four, contact areas 18a, 18b, 18c, 18d between the two spiral walls 11.1, 15.1. During the compression operation of the known spiral compressor 1.1, the two spirals 2, 3, which are movable relative to each other, can, due to the aforementioned adverse influences such as thermal expansion, material deformation and other factors, produce wear marks in these contact areas 18a, 18b, 18c, 18d on the respective radial outer and inner surfaces of four pairs of adjacent wall sections 19a, 19b, 19c, 19d, 20a, 20b, 20c, 20d of the two spiral walls 11.1, 15.1. These grinding marks can increase the energy consumption of the eccentric drive 4 and shorten the maximum service life of the spiral compressor.The invention addresses the idea of ​​preventing such wear from the outset by means of geometric modifications to the spiral walls 11.1, 15.1 in the contact areas 18a, 18b, 18c, 18d. In contrast to the known spiral compressor 1.1 according to Fig. 2, the spiral compressor 1 according to the invention, shown in Fig. 3, has a recess 31a, 31b, 31c, 31d on one of the spiral walls 11, 15 in each of the contact areas 18a, 18b, 18c, 18d. In the present example, a first recess 31a is formed on a first wall section 19a and a second recess 31b on a second wall section 19b of the spiral wall 11 of the housing-fixed first spiral 2, as well as a third recess 31c on a third wall section 20c and a fourth recess 31d on a fourth wall section 20d of the spiral wall 15 of the movable spiral 3.The four recesses 31a, 31b, 31c, 31d each extend radially and axially as a flattening of the radially outer wall side of the respective spiral wall 11, 15. The recesses 31a, 31b, 31c, 31d can each be formed or arranged at any angular position around the central axis 10.

[0034] Fig. 4 shows a schematic longitudinal section through a partial area of ​​the housing-fixed spiral 2 or the movable spiral 3 of the spiral compressor 1 according to the invention. On the spiral wall 11, 15 projecting axially from the respective base plate 7, 8, a radially inwardly directed first chamfer 32 is additionally formed at the respective recess 31a, 31b, 31c, 31d or instead of a recess in the relevant wall section 19a, 19b, 20c, 20d, which has a first chamfer angle α relative to an imaginary longitudinal axis 35 perpendicular to the base plate 7, 8. This imaginary longitudinal axis 35 runs parallel to the central axis 10 of the movable spiral 3.

[0035] Fig. 5 shows a further schematic longitudinal section through a partial area of ​​the housing-fixed spiral 2 or the movable spiral 3 of the spiral compressor 1 according to the invention. In contrast to the first chamfer 32 according to Fig. 4, a second chamfer 33, directed radially inwards with a different second chamfer angle β, and a third chamfer 34, directed radially outwards with a third chamfer angle γ, are formed on the spiral wall 11, 15 projecting axially from the base plate 7, 8. The two spirals 2, 3 mesh with each other during compression operation of the spiral compressor 1, with the movable spiral 3 orbiting around the housing-fixed spiral 2. During the orbital movement of the movable spiral 3 around the case-fixed spiral 2, the orbiting spiral 3 sweeps over the potential contact areas 18a, 18b, 18c, 18d between the two spiral walls 11 , 15.Due to the recesses 31a, 31b, 31c, 31d formed on the two wall sections 19a, 19b of the housing-fixed spiral 2 and on the two further wall sections 20c, 20d of the movable spiral 3 in the form of wall flattening, it is ensured that the orbital movement of the movable spiral 3 during operation of the spiral compressor 1 according to the invention causes no or at most only very minor abrasion marks on the spiral walls 11, 15 of the two spirals 2, 3. This allows the spiral compressor 1 to be operated reliably and permanently with minimal wear on its spiral walls 11, 15, in particular almost independently of thermal loads, deformation forces, eccentric bearing wear and / or manufacturing tolerances.

[0036] Reference numeral list (part of the description)

[0037] 1 spiral compressor (according to the invention)

[0038] I.1 Spiral compressor (state of the art)

[0039] 2 Case-fixed spiral

[0040] 3 Orbital spiral

[0041] Eccentric drive

[0042] 5 Drive shaft

[0043] 6 Electric drive motor

[0044] 7 Housing-mounted base plate

[0045] 8 Movable base plate

[0046] 9 cases

[0047] 10 Geometric central axis

[0048] 11 Spiral wall of the movable spiral

[0049] II.1 Spiral wall of the housing-fixed spiral (state of the art)

[0050] 12a Radial outer spiral turn of the housing-fixed spiral wall 11 , 11.1

[0051] 12b Radial inner spiral winding of the housing-fixed spiral wall 11 , 11.1

[0052] 13 Fluid inlet

[0053] 14 Fluid outlet

[0054] 15 Spiral wall of the movable spiral

[0055] 15.1 Spiral wall of the movable spiral (state of the art)

[0056] 16a Radial outer spiral turn of the spiral wall 15, 15.1

[0057] 16b Radial inner spiral turn of the spiral wall 15, 15.1

[0058] 17a - 17d First to fourth spiral turns

[0059] 18a - 18d First to fourth contact areas

[0060] 19a-19d First to fourth wall sections of the spiral wall 11, 11. of the housing-fixed spiral 2

[0061] 20a - 20d First to fourth wall sections of the spiral wall 15, 15.1 of the movable spiral 3

[0062] 31a - 31d First to fourth returns

[0063] 32 First chamfer

[0064] 33 Second chamfer 34 Third chamfer

[0065] 35 Longitudinal axis a First helix angle ß Second helix angle y Third helix angle

Claims

Patent claims 1. Oil-free spiral compressor (1) with a housing (9) comprising a housing-fixed base plate (7) and a movable base plate (8), on which a housing-fixed spiral (2) and a spiral (3) movable with the movable base plate (8) are formed, respectively, projecting axially in the axial direction, wherein the two spirals (2, 3) are arranged so that they interlock radially and axially, wherein the two spirals (2, 3) each have a spiral wall (11, 15) extending in several spiral turns (12a, 12b, 16a, 16b), wherein the movable spiral (3) is movable by means of an eccentric drive (4) into an orbital path leading around the housing-fixed spiral (2), wherein spiral webs (17a, 17b, 17c, 17d) formed between the two spiral walls (11, 15) are located in the Operation of the spiral compressor (1) continuously narrows, and in which the spiral walls (11 , 15) may touch section by section due to design and / or operation,characterized in that at least one wall section (19a, 19b, 20c, 20d) of at least one of the two spiral walls (11, 15), in which a potential contact area (18a, 18b, 18c, 18d) of the two spiral walls (11, 15) lies, is geometrically modified in such a way that contact between the two spiral walls (11, 15) or at least an increased frictional force between the two spiral walls (11, 15) in this wall section (19a, 19b, 20c, 20d) is excluded.

2. Spiral compressor according to claim 1, characterized in that the at least one geometrically modified wall section (19a, 19b, 20c, 20d) has a recess (31a, 31b, 31c, 31d) such as a radially and axially extending flattening, wherein this modified wall section (19a, 19b, 20c, 20d) is formed at least on a radially outer wall side of the spiral wall (11, 15).

3. Spiral compressor according to claim 1 or 2, characterized in that the at least one geometrically modified wall section (19a, 19b, 20c, 20d) has a radially inwardly directed first chamfer (32) which begins at the level of the base plate (7, 8) or axially spaced therefrom on the spiral wall (11, 15) and in a first inclined angle (a) to a geometric longitudinal axis (35) perpendicular to the base plate (7, 8).

4. Spiral compressor according to claim 1 or 2, characterized in that the at least one geometrically modified wall section (19a, 19b, 20c, 20d) has a radially inward directed second chamfer (33) and a radially outward directed third chamfer (34), which begins at the level of the base plate (7, 8) or axially spaced therefrom on the spiral wall (11, 15), wherein the second chamfer (33) extends at a second angle of inclination (β) and the third chamfer (34) extends at a third angle of inclination (ν) to a longitudinal axis (35) perpendicular to the base plate (7, 8).

5. Spiral compressor according to one of claims 1 to 4, characterized in that the at least one geometrically modified wall section (19a, 19b, 20c, 20d) is located at a first potential contact area in the direction of movement. (18a, 18b, 18c, 18d) is formed between the two spiral walls (11, 15).

6. Spiral compressor according to one of claims 1 to 5, characterized in that the at least one geometrically modified wall section (19a, 19b, 20c, 20d) is formed on a radially outer spiral turn (12a, 16a) of the spiral wall (11 , 15).

7. Vehicle, such as a commercial vehicle or passenger car, with a spiral compressor (1), for example for generating compressed air in a compressed air supply system or for compressing a refrigerant in an air conditioning system of the vehicle, which is constructed according to one of the device claims.

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