Ball bearings of a spiral compressor with optimized cage design

Abstract

According to the invention, an electromechanically operated spiral compressor with an orbital bearing arrangement (1) is proposed, wherein the cage (8) of the orbital bearing, which is designed as a rolling bearing (3), has several spherical cage pockets (18) for receiving the balls (7), the centers of the spherical cage pockets (18) define a pocket pitch circle (10), the cage pockets (18) are regularly spaced apart from one another in the circumferential direction, and each pair of adjacent cage pockets (18) is connected by a web (14), the webs (14) in a section plane (15) perpendicular to the cage axis of rotation (16) only have material radially within this pocket pitch circle (10) and thus simultaneously provide a bulbous / parabolic / wave-like recess (19) radially outside the pocket pitch circle (10), the webs (14) extend in the axial direction from a first axial cage end (20) to more than half of the cage (8),however, they do not extend fully to the second axial cage end (21).

Description

[0001] The invention relates to a ball bearing of a spiral compressor with an optimized cage design.

[0002] DE 10 2021 100 612 B3 discloses a bearing arrangement in a spiral compressor. For this purpose, the cage has at least one guide structure designed as a recess, which can guide the lubricant or lubricant mixture axially from the chamber through the rolling bearing much more effectively. The guide structure is arranged outside the area necessary for cage strength and cage guidance in order not to impair the cage's function and to avoid increasing the required installation space and weight of the orbital bearing arrangement.

[0003] Rolling bearings in the form of ball bearings and ball snap cages are known, for example, from DE 10 2007 061 589 A1. DE 10 2007 061 589 A1 discloses a ball bearing and an associated mounting structure, and more specifically a ball bearing for use in a motor vehicle transmission and the like, in which lubricating oil is supplied in the axial direction to forcibly lubricate the ball bearing and its mounting structure.

[0004] DE 10 2009 013 978 A1 shows a cage for radial rolling bearings, with projections connected by web parts, which form pockets distributed over the circumference of the cage and which guide rolling elements, and in which the projections extend from the web parts in the axial direction of the rolling bearing.

[0005] JP 2011 094546 A and JP 2012 207547 A show spiral compressors with shaft bearings, with JP 2011 202671 A showing a ball bearing with a cage.

[0006] DE 10 2016 222 031 A1 shows a rolling bearing cage designed as a comb cage, which has a side ring and several axially projecting webs through which axially open pockets are formed, which serve to receive one rolling bearing ball each.

[0007] DE 10 2021 120 024 A1 discloses a rolling bearing designed as a ball bearing with an inner bearing ring and an outer bearing ring as well as with ball rolling elements, guided by a cage, comprising a cage ring from which retaining claws extend axially on one side, forming rolling element pockets provided for the captive reception of each ball rolling element, wherein the retaining claws are connected to each other between the rolling element pockets by intermediate sections that adjoin the cage ring in the axial direction and are evenly distributed between the rolling element pockets in the circumferential direction.

[0008] DE 10 2021 100 612 B3 discloses an orbital bearing arrangement with a rolling bearing for supporting a compressor wheel having a compressor spiral relative to a motor shaft, wherein the rolling bearing has an inner ring and an outer ring, wherein a plurality of rolling elements are arranged between the inner and the outer ring, which are spaced apart from each other by means of a cage in the circumferential direction, or in the direction of rotation of the outer ring relative to the inner ring, wherein the outer ring is rotationally fixed to the compressor wheel and coaxially supported by it, and the inner ring is rotationally fixed to a balancing ring, wherein there is an eccentricity between the axis of rotation of the inner ring and the axis of rotation of the motor shaft, wherein the balancing ring is arranged eccentrically to the axis of rotation of the motor shaft, and the balancing ring has a radially projecting extension as a counterweight to the rotatable mass of the compressor wheel.wherein a chamber is defined on the side diametrically opposite the cantilever which can receive a lubricant mixture and supply this lubricant mixture to the rolling bearing adjacent to the chamber, in particular to the rolling elements, the cage having at least one guide structure designed as a recess which can guide the lubricant mixture axially from the chamber through the rolling bearing, wherein the guide structure is arranged outside the area necessary for the cage strength and / or for the cage guidance.

[0009] DE 10 2017 115 881 A1 shows a rolling bearing cage with a cage ring from which retaining arms extend, forming rolling element pockets designed for the secure reception of a rolling element, namely a ball, wherein the retaining arms are connected to each other in the circumferential direction between the rolling element pockets by intermediate sections adjoining the cage ring in the axial direction, which are weakened in the radial direction compared to the cage ring and to the retaining arms, characterized in that the thickness of each intermediate section measured in the radial direction of the cage ring corresponds to at least 10 percent and at most 20 percent of the diameter of the rolling element pocket.

[0010] The task is to improve the cage of a ball bearing in an electromechanically operated spiral compressor.

[0011] Scroll compressors are used as refrigeration compressors or heat pumps. They have a compressor wheel with a spiral shape, usually arranged as a groove or channel on one end face of the wheel. This compressor wheel is driven by a motor shaft. The motor shaft is driven by an electric motor that operates independently of the drive train. The rotation of the motor shaft moves the compressor wheel in a circular path without it rotating around its own axis. An orbital bearing, designed as a rolling bearing, is used to support the compressor wheel on the motor shaft. The term "orbital bearing" derives from the fact that the bearing rotates both around its own axis and around an axis offset from it. The axis of rotation of the orbital bearing coincides with the axis of rotation of the compressor wheel, and the axis offset from it is defined by the axis of rotation of the motor shaft.Consequently, the orbital bearing, with its inner ring, also sits on this axially offset journal of the motor shaft. The journal has an eccentricity relative to the motor shaft.

[0012] During operation, the refrigerant (operating as a refrigeration compressor) is thermodynamically processed on the spiral-shaped side of the compressor wheel to achieve the desired cooling (or heating) effect.

[0013] On the side of the compressor wheel opposite the spiral shape – the bearing side – the orbital bearing, the motor shaft, and a balancing ring define a chamber in which a mixture of lubricant and refrigerant can collect and form a lubricant mixture. The lubricant enters the chamber via lubricant channels. Targeted lubrication of the orbital bearing, for example via an oil-carrying bore that delivers the oil to the rolling elements, is not possible due to the structural design of the spiral compressor and the kinematic processes of the aforementioned components.

[0014] Electromechanically operated spiral compressors exert different forces and loads on the cage of the orbital bearing than is known from conventional deep groove ball bearing applications.

[0015] The stresses in ordinary deep groove ball bearings are typically due to two causes. Firstly, the cages are subjected to high centrifugal forces due to high rotational speeds (such as those occurring in rotor bearings in electric motors). The expansion in the cage diameter caused by this centrifugal force puts such a strain on the cages that they break within the rolling element pockets. Secondly, cages can be subjected to very high lead-in and lead-out of the rolling elements, which increases cage deformation due to the pulling and pushing of the rolling elements against the cage pockets, resulting in disproportionately high stress in the thinnest cross-section of the cage pocket.

[0016] Electromechanically driven spiral compressors (e-scroll) have an eccentric design, resulting in significantly different forces acting on the orbital bearing cage than those described above. These significantly different forces and loads on the orbital bearing cage stem from the fact that conventional deep groove ball bearings are mounted concentrically to the shaft system, whereas orbital bearings are mounted eccentrically. The eccentric design means that the rolling elements are subjected to highly variable acceleration and deceleration. These processes are strongly dependent on the position of the compressor and the eccentric design. This specific design results in a unique kinematic pattern in which the bearing partially rotates around individual balls. This unique kinematic pattern, characterized by the strong acceleration and deceleration of the rolling elements and the orbital motion of the entire bearing, results in high ball forces acting on the cage pockets.

[0017] The cage's function is to maintain the balls at their specified distance and absorb these high ball forces. Consequently, there are situations where the cage must continue to push the balls forward while other balls simultaneously attempt to slow the cage down. In typical deep groove ball bearing applications, the balls run concentrically around the bearing center, which is why the forces described have a minor influence on the cage load.

[0018] Furthermore, due to their design and operation, e-scroll bearings are subject to insufficient lubrication. To ensure proper bearing function, the contact area between the rolling elements, outer ring, and inner ring must always be adequately lubricated. A lack of lubrication would lead to increased friction and ultimately to bearing failure. General lubrication of the bearing is not possible due to refrigerant contamination. This means the bearing has access only to a refrigerant-oil mixture located in the bearing environment (the so-called back-pressure chamber). The more oil from the environment reaches the bearing, the longer its service life.

[0019] The cage must therefore absorb the rolling element forces resulting from the alternating acceleration and deceleration processes as well as from the orbital bearing rotation and be able to keep the rolling elements at their intended distance.

[0020] The task is described in an electromechanically operated spiral compressor with an orbital bearing arrangement, the orbital bearing being designed as a rolling bearing for supporting a compressor wheel having a compressor spiral relative to a motor shaft. The rolling bearing has an inner ring and an outer ring, with a plurality of balls arranged between the inner and outer rings. These balls are spaced apart from each other by means of a cage in the circumferential direction, or in the direction of rotation of the outer ring relative to the inner ring. The outer ring is rotationally fixed and coaxially supported by the compressor wheel, and the inner ring is rotationally fixed by a balancing ring. There is an eccentricity between the axis of rotation of the inner ring and the axis of rotation of the motor shaft, and the balancing ring is arranged eccentrically to the axis of rotation of the motor shaft.wherein the balancing ring has a radially projecting cantilever as a counterweight to the rotatable mass of the compressor wheel, whereby a chamber is defined on the side diametrically opposite the cantilever which can receive a lubricant mixture and supply this lubricant mixture to the rolling bearing adjacent to the chamber, in particular to the balls, according to the invention in that, The cage has several spherical cage pockets for receiving the spheres, wherein the centers of the spherical cage pockets define a pocket partial circle, wherein the cage pockets are regularly spaced apart from each other in the circumferential direction and each pair of adjacent cage pockets is connected by a web, the webs in a section plane perpendicular to the axis of rotation of the cage create a bulbous / parabolic / wave-like recess, wherein the webs extend in the axial direction from a first axial cage end to more than half of the cage, but not completely to the second axial cage end.

[0021] The solution according to the invention is based on the aim of reducing the deformation in the thinnest cross-section of the cage pocket and thus reducing the stress concentration in this zone: The spherical or oval cage pocket shape causes the force direction to be altered, rotating the resulting force vector in a more advantageous direction compared to a cylindrical pocket shape. The force is no longer directed straight into the cage to compress it at the point of load. Instead, the force now attempts to twist the cage by applying a radial force component to the retaining claw. This targeted twisting of the retaining claws also deforms the cage web, thus reducing the deformation at the bottom of the pocket.

[0022] The radial height in the web area is reduced by a wave-like shape, thereby making the cage web, which is typically unloaded and only slightly deformable in prior art designs, more flexible. The intention is that the ball(s) deform the cage in such a way that the cage attempts to twist within the flexible web. The resulting elasticity leads to an improved distribution of deformations throughout the cage, which in turn reduces the stress concentration at the bottom of the pocket.

[0023] The deliberately induced higher degree of deformation, which would normally result in higher stresses, is cushioned by a cage guide acting as a starting zone on the outer ring flange. The deformations are thus dissipated via the outer ring. By supporting the cage on the outer ring, the magnitude of the deformation is limited, and simultaneously, the reduced deformation component in the pocket area significantly lowers the stress concentration and stress level there.

[0024] According to the invention, the cage has a step in the axial direction from the web, whereby a running zone to the outer ring is formed, which in operation forms an approximately linear contact area between the running zone and the outer ring due to the deformation of the cage.

[0025] The cage's outer diameter is stepped down towards the retaining claws. This means that the cage's outer diameter preferably has a step in the axial direction, defining and geometrically limiting the contact area with the outer ring. This prevents the cage from deforming or expanding to such an extent that a point load and support would occur between the cage's outer diameter and the outer ring. This load case previously resulted from the cage's greater expansion in the claw area and the unfavorable geometry in the contact zone. Now, despite the cage's expansion in the claw area, an almost linear contact area can be created because the expansion is nearly horizontal due to the direct connection to the cage flange. The improved support in the contact zone avoids point contact forces, reduces the Hertzian contact stress, and consequently reduces bearing friction.Due to its significantly more elastic design, individual cage pockets can selectively engage the outer ring at the moment of peak ball force. With a rigid cage, multiple cage pockets would engage the outer ring simultaneously. This solution therefore offers advantages in terms of friction and wear both within a single engagement zone and across all engagement zones of the cage.

[0026] Preferably, the webs do not connect the cage pockets with centrally located webs. Instead, the webs are arranged asymmetrically around the inner diameter. Thus, during rotation, the ball contacts an area of ​​the cage pocket that is not directly supported by a web. This prevents crushing / compression and preferably results in elastic (bending) deformation in the area of ​​the cage web. Because the cage web deforms along with the ball during this type of movement, due to its sufficient flexibility, the stress at the bottom of the pocket is reduced.

[0027] Alternatively, this embodiment can be replaced by a central bridge arrangement if the space between the retaining claws becomes too small.

[0028] In a first embodiment of the invention, the webs in the section plane only have material radially within this pocket segment circle and thus expose the bulbous / parabolic / wave-like recess radially within the pocket segment circle.

[0029] Another embodiment of the invention provides that the webs in the section plane only have material radially outside this pocket segment circle and thus expose the bulbous / parabolic / wave-like recess radially outside the pocket segment circle.

[0030] In another embodiment of the invention, the webs in the section plane have material around the pocket segment circle and thus provide both a bulbous / parabolic / wave-like recess radially inside the pocket segment circle and radially outside the pocket segment circle.

[0031] The wave-shaped, arc-shaped, or parabolic recess in the radial height in the web area allows for improved lubricant supply into the bearing interior or through the rolling bearing.

[0032] In one embodiment of the invention, the spherical cage pockets at the second axial cage end are designed to be open and form retaining claws. The retaining claws hold the balls in the cage, allowing the balls to rotate within the cage pockets.

[0033] Preferably, the spherical cage pockets are open on the inside and outside in a radial direction. This allows the balls to contact the outer and inner rings, respectively, so that the balls can run in the raceways of the outer and inner rings.

[0034] The spherical cage pockets are particularly advantageous because they are so flexible that a ball can be clipped into each one. This makes mounting the balls easy.

[0035] In a further development of the invention, the ball can be clipped into the cage pocket from the second axial end of the cage. Advantageously, several balls can be clipped into the cage in this way by pressing the cage onto several pre-positioned balls, causing the balls to snap into place in the cage pockets.

[0036] The solution according to the invention also consists of the rolling bearing with the cage in an electromechanically operated spiral compressor with at least one of the aforementioned configurations. Thus, such a rolling bearing with the cage properties according to the invention can also be used as a main shaft bearing, where it exhibits the same advantages in operation, even without an eccentric load.

[0037] Further aspects of the invention are explained in more detail with reference to the figures. They show: Fig. 1 an orbital bearing arrangement in an electromechanically operated spiral compressor, Fig. 2 the cage of the rolling bearing according to the invention of the orbital bearing arrangement Fig. 1, Fig. 3 a first version of the cage's struts, Fig. 4 a second version of the cage's struts, Fig. 5 the formation of the cage's starting zone on the outer ring and Fig. 6. The formation of the recess in the area of ​​the footbridge.

[0038] The Fig. Figure 1 shows an orbital bearing arrangement 1 in an electromechanically driven scroll compressor. The scroll compressor and the orbital bearing arrangement 1 are shown in the illustration in Fig. 1 for the following components: a housing 28, a main shaft bearing 19, a motor shaft 4, a compressor wheel 17 with a compressor spiral 2 (not explicitly shown here), a balancing ring 9, a rolling bearing 3 and a sealing ring 27.

[0039] Reference numeral 2 indicates a compressor spiral on the shown end face of the compressor wheel 17, which is located only on this end face but is not shown geometrically in its entirety here. The compressor wheel 17 has a sealing ring 27 on the end face opposite the compressor spiral 2, which seals the compressor chamber, in which the compressor spiral 2 compresses the coolant, by contacting the housing 28.

[0040] The compressor wheel 17 also has a receptacle for the rolling bearing 3 on its end face opposite the compressor spiral 2. This rolling bearing 3 is also called an orbital bearing and consists of an outer ring 6, an inner ring 5 arranged concentrically to it, and rolling elements arranged between these two rings 5, 6, which are designed as balls 7. The balls 7 are usually held spaced apart circumferentially by a cage 8. The outer ring 6 of the rolling bearing 3 is fixedly seated in the receptacle of the compressor wheel 17.

[0041] The motor shaft 4 has an eccentrically arranged journal on which the balancing ring 9 is fixedly mounted relative to the motor shaft 4. The inner ring 5 of the rolling bearing 3 is fixedly mounted on this balancing ring 9. When the motor shaft 4 is rotated about its own axis of rotation 11, the eccentrically arranged journal causes the balancing ring 9 and the rolling bearing 3, and thus also the compressor wheel 17, to spin around the axis of rotation 11.

[0042] The eccentricity 22 exists between the axis of rotation of the inner ring 5 and the axis of rotation of the motor shaft 11. The axis of rotation of the inner ring 5 coincides with the axis of rotation of the cage 16, since in a rolling bearing the two rings 5 ​​and 6 and the cage 8 are arranged concentrically to each other.

[0043] The balancing ring 9 has a cantilever 12, which serves to compensate for the imbalance during operation of the eccentric arrangement. Thus, a chamber 13 is located on the diametrically opposite side of the cantilever 12. The coolant collected in this chamber 13 mixes with the lubricant present there to form a lubricant mixture.

[0044] This lubricant mixture is distributed circumferentially during operation by the boom 12 and reaches both the main shaft bearing 19 and the rolling bearing 3. Due to the kinematic conditions, the rolling bearing 3 is subject to higher stresses than the main shaft bearing 19.

[0045] In order to meet these higher demands in confined installation spaces, the cage 8 has the properties according to the invention, which are explained in the following figures.

[0046] The Fig. Figure 2 shows the cage 8 of the rolling bearing 3 of the orbital bearing arrangement 1 according to the invention. Fig. 1. The rolling bearing 3 shown comprises the cage 8, several balls 7, and the inner ring 5. The outer ring 6 has been omitted for better visibility of the invention. The second axial cage end 21 is what the viewer is currently looking at. The first axial cage end 20 is located behind the rolling bearing 3 shown. This makes it visible that the cage pockets 18 at the second axial cage end 21 are open and that the ball 7 is held in each cage pocket 18 by two retaining claws 25, which contact and hold the ball 7 circumferentially. In the radial direction – viewed at the cage axis of rotation 16 – the cage pockets 18 are also open both inside and out so that the balls 7 can run on their raceways in the rings 5 ​​and 6. The surface of each retaining claw 25 facing the corresponding ball 7 is spherical and / or congruent with the spherical shape of the corresponding ball 7. Alternatively, this surface can also take on an oval shape.In any case, any curved surface in space is suitable within the scope of the invention, analogous to a spherical or oval shape, which does not define the ball-retaining claw contact as a point contact (e.g., plane against sphere) or line contact (e.g., cylinder against sphere). In reality, the design of the spherical surface certainly allows for an indeterminate mixture of the aforementioned contacts; the essential difference lies in the fact that, during operation, the load on the ball 7 against the retaining claw 25, due to the spherical and / or surface shape congruent with the ball 7, forms a contact optimized with respect to the Hertzian contact pressure in order to match the deformation of the webs 14 and the cage 8 to the durability of the cage 8.

[0047] To allow deformation of the cage 8, the webs 14 arranged between two retaining claws 25 are provided with a recess 26 radially outside the pocket circle 10. The pocket circle 10 is an ideal, imaginary circle formed by the centers 31 of the spheres 7 in the unloaded state. The pocket circle 10 defines the (axial) section plane 15 in which the pocket circle 10 lies completely. The geometric possibilities for shaping the recesses 26 are shown in the figures of the Fig. 3 and Fig. Figure 4 illustrates this better. Basically, the radial height of the webs 14 is reduced in the web area, thereby making the normally unloaded and only slightly deformable cage 8 more flexible.

[0048] In any case, the axial extension – along the direction of the cage rotation axis 16 – of the webs 14 is such that the axial end of the web 14 does not project beyond the axial end of the retaining claws 25, in order to allow the flexibility of the retaining claws 25. Thus, in a further embodiment of the design, the webs 14 can extend axially to a maximum of the pocket pitch circle 10. In any case, all webs 14 are interconnected at the first axial cage end 20.

[0049] The cage 8 also features a discrete radial step 23 in the region of the first axial cage end 20, where the cage pockets 18 are closed by the cage material. This step 23 forms a running-up zone 24, set back from the retaining claws 25, which is intended for contact with the outer ring 6 (not shown here).

[0050] The Fig. Figure 3 shows a first embodiment of the webs 14 of the cage 8. The webs 14 are located radially inside the pocket pitch circle 10. This also means that the recesses 26 are arranged radially outside the pocket pitch circle 10. In the circumferential direction, the recesses 26 are bounded by the retaining claws 25. The retaining claws 25 are located almost symmetrically to and on the pocket pitch circle 10, as can be clearly seen in the figure. The illustration of the outer ring 6 also provides a better understanding of the position and shape of the running zones 24 formed by the cage 8. The running zones 24 ideally follow the inner contour of the outer ring 6, so that the cage 8, when positioned disaxially during operation and / or through its deformation by the balls 7 during operation by forward and / or reverse movement of the rolling bearing 3, can come into contact with the inner surface of the outer ring 6 with the running zone 24 - however, not necessarily all running zones 24 of the cage 8 at the same time.It is sufficient if at least a few of the contact zones 24, which come into contact with the outer ring 6 through deformation of the cage 8, support the cage 8 on the outer ring 6, so that the cage 8 is limited in its load and is not destroyed.

[0051] The recess 26 has a clearly recognizable curved profile, here in the form of a parabola, with the ends of the parabola being rounded towards the approach zones 24. This contour can also be seen as a wave trough or wave crest, and then has a wave-like profile. In any case, at least one arc-shaped contour element is present, preferably several, which can depict the aforementioned profiles.

[0052] The Fig. Figure 4 shows a second embodiment of the webs 14 of the cage 8. The webs 14 are located in this version facing... Fig. Three alternative designs on the pocket pitch circle 10 – in any case, the pocket pitch circle 10 is intersected by part of the web 14. The recesses 26 are now located not only radially outside the pocket pitch circle 10, but also radially inside the pocket pitch circle 10.

[0053] The different effects of the two designs in the Fig. 3 and Fig. The difference lies in the fact that, although the ball 7 experiences a very similar contact start in the cage pocket 18 during operation in both versions, the force of the balls 7 on the cage 8 is supported differently due to the different radial placement of the webs 14. This affects the flexible behavior of the cage 8, so that different flexibilities can be achieved depending on the performance class of the electromechanically operated spiral compressor (e-Scroll) by different placements, and the cage 8 can be adapted accordingly.

[0054] The Fig. Figure 5 shows the formation of the running zone 24 of the cage 8 on the outer ring 6. This sectional view of the rolling bearing 3 now allows a view in the circumferential direction onto the section plane. The ball center 31 and the section plane 15, which is defined by the pocket pitch circle 10, are clearly visible here. The pocket pitch circle 10 runs through these ball centers 31 in the geometrically ideal position of the balls 7 in the cage pockets 18.

[0055] The placement of the first and second axial cage ends 20 and 21 is now clearly visible and transferable to the other figures. The cage 8 is closed circumferentially in a ring shape at the first axial cage end 20 and has a flat end face as cage end 20. In contrast, on the opposite side, at the second axial cage end 21, the axially open cage pockets 18 are explainable by the fact that there is no cage material on this side in this section plane. Likewise, the ball 7 conceals the retaining claw 25.

[0056] The running-up zone 24 in this sectional view is bounded on one side by the first axial cage end 20 and on the other side by the step 23, which radially separates the cage material. The step 23 thus influences not only the dimensions of the running-up zone 24, but also the flexibility of the cage 8, since the radial height is reduced in the root area of ​​the retaining claws 25 and in the pocket base 33. When the cage 8 twists during operation, at least one of the running-up zones 24 comes into contact with the inner surface 34 of the outer ring 6, which is located outside the raceway 35 of the balls 7.

[0057] The Fig. Figure 6 shows the formation of the recess 26 in the area of ​​the footbridge 14. Fig. Figure 6 shows cage 8 from the Fig. 3 with the corresponding training of the recess 26. Continue with Fig.Figure 6 illustrates the circumferential length (arc length) of the ramp zone 24 and the recess 26, which alternate along the circumference. The ramp zone 24 forms a permissible contact area with the outer ring 32 in arc length, which is longer in arc length than the recess length 29 (in arc length). At the edge zones of the ramp zone 24, the curvature of the contour increases, creating a seamless, continuous transition into the contour of the recess 26. The contour of the recess 26 then follows the arc-shaped, wave-like, parabolic profile according to the invention and ultimately forms a mirror-image edge zone to the next ramp zone 24.

[0058] The step 23 extends circumferentially over the entire cage pocket 18 and its flanking retaining claws 25. The radial inner boundary of the cage 8 follows a simple circle without any special contour changes. Reference symbol list 1 Orbital bearing arrangement 2 compressor spirals 3 rolling bearings 4 Motor shaft 5 inner ring 6 outer ring 7 balls 8 cage 9 Balancing ring 10 pocket circle 11 Motor shaft rotation axis 12 outriggers 13th Chamber 14 Bridge 15 Section plane 16 Cage pivot axis 17 compressor wheel 18 cage bags 19 main shaft bearings 20 First axial cage end 21 Second axial cage end 22 Eccentricity 23 levels 24 Approach zone 25 retaining claws 26 Exclusion 27 Sealing ring 28 cases 29 Recess length 30 - 31 Center of the sphere 32 Contact area to the outer ring 33 Pocket Ground 34 Inner surface area 35 running groove

Claims

[1] Electromechanically operated spiral compressor with an orbital bearing arrangement (1) comprising a rolling bearing (3) for supporting a compressor wheel (17) having a compressor spiral (2) relative to a motor shaft (4), wherein the rolling bearing (3) has an inner ring (5) and an outer ring (6), wherein a plurality of balls (7) are arranged between the inner and outer rings (5, 6), which are spaced apart from each other by means of a cage (8) in the circumferential direction, or in the direction of rotation of the outer ring (6) relative to the inner ring (5), wherein the outer ring (6) is rotationally fixed and coaxially supported by the compressor wheel (17) and the inner ring (5) is rotationally fixed by a balancing ring (9), wherein an eccentricity (22) exists between the axis of rotation of the inner ring (5) and the axis of rotation of the motor shaft (11), wherein the balancing ring (9) is eccentric to the axis of rotation of the motor shaft (11) is ordered,wherein the balancing ring (9) has a radially projecting cantilever (12) as a counterweight to the rotatable mass of the compressor wheel (17), whereby a chamber (13) is defined on the side diametrically opposite the cantilever (12), which can receive a lubricant mixture and supply this lubricant mixture to the rolling bearing (3) adjacent to the chamber (13), in particular to the balls (7), . characterized by , that - the cage (8) has several spherical cage pockets (18) for receiving the balls (7), - the centers of the spherical cage pockets (18) determine a pocket partial circle (10), - the cage pockets (18) are regularly spaced apart from each other in the circumferential direction and each pair of adjacent cage pockets (18) is connected by a bridge (14), - the webs (14) in a section plane (15) perpendicular to the cage rotation axis (16) create a bulbous / parabolic / wave-like recess (26), - the webs (14) extend in an axial direction from a first axial cage end (20) to more than half of the cage (8), but not completely to the second axial cage end (21), wherein - the cage (8) has a step (23) in the axial direction from the web (14), whereby a running zone (24) to the outer ring (6) is formed, which in operation forms an approximately linear contact area between the running zone (24) and the outer ring (6) due to the deformation of the cage (8). [2] Electromechanically operated spiral compressor according to claim 1, characterized by , that the webs (14) in the section plane (15) only have material radially within this pocket part circle (10) and thus expose the bulbous / parabolic / wave-like recess (26) radially within the pocket part circle (10). [3] Electromechanically operated spiral compressor according to claim 1, characterized by, that the webs (14) in the section plane (15) only have material radially outside this pocket part circle (10) and thus expose the bulbous / parabolic / wave-like recess (26) radially outside the pocket part circle (10). [4] Electromechanically operated spiral compressor according to claim 1, characterized by , that the webs (14) in the section plane (15) have material around the pocket part circle (10) and thus provide both a bulbous / parabolic / wave-like recess (26) radially inside the pocket part circle (10) and radially outside the pocket part circle (10). [5] Electromechanically operated spiral compressor according to any one of the preceding claims, characterized by , that the spherical cage pockets (18) at the second axial cage end (21) are designed to be open and form retaining claws (25). [6] Electromechanically operated spiral compressor according to any one of the preceding claims, characterized by, that the spherical cage pockets (18) are designed to be open in the radial direction inwards and outwards. [7] Electromechanically operated spiral compressor according to any of the preceding claims, characterized by , that the spherical cage pockets (18) are so flexible that a ball (7) can be clipped into each cage pocket (18). [8] Electromechanically operated spiral compressor according to claim 7, characterized by , that the ball (7) can be clipped into the cage pocket (18) from the second axial cage end (21). [9] Rolling bearing (3) with the cage (8) of the electromechanically operated spiral compressor according to one of the preceding claims.

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