Ball bearing of a spiral compressor with optimised cage design

Abstract

According to the invention, an electromechanically operated spiral compressor having an orbital bearing arrangement (1) is proposed, wherein the cage (8) of the orbital bearing, which is configured as a rolling bearing (3), has a plurality of spherical cage pockets (18) for receiving the balls (7), the centre points 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 in each case two adjacent cage pockets (18) are connected to a connection piece (14), the connection pieces (14), in a sectional plane (15) perpendicular to the cage rotational axis (16), have material only radially within said pocket pitch circle (10) and at the same time thus expose a bulged / parabolic / wave-like recess (19) radially outside the pocket pitch circle (10), and the connection pieces (14) extend in an axial direction starting from a first axial cage end (20) to over half of the cage (8), but not completely to the second axial cage end (21).

Description

[0001] P240298

[0002] - 1 -

[0003] Ball bearing of a spiral compressor with optimized cage design

[0004] The invention relates to a ball bearing of a spiral compressor with an optimized cage design.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] DE 10 2016 222 031 A1 shows a rolling bearing cage designed as a comb cage, which has a side ring and several webs projecting axially from it, by P240298

[0010] - 2 - the axially open pockets are formed, which serve to accommodate one rolling bearing ball each.

[0011] 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.

[0012] 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.

[0013] DE 10 2017 115 881 A1 shows a rolling bearing cage with a cage ring from which retaining arms extend, which are designed to securely hold a rolling body. P240298

[0014] - 3 - pers, namely a sphere, forming rolling element pockets, 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.

[0015] The task is to improve the cage of a ball bearing in an electromechanically operated spiral compressor.

[0016] 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.

[0017] 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.

[0018] On the side opposite the spiral-shaped side of the compressor wheel – the bearing side – a chamber is defined by the orbital bearing, the motor shaft, and a balancing ring. This chamber allows a mixture of lubricant and refrigerant to collect and form a lubricant mixture. The lubricant enters via lubricant channels. P240298

[0019] - 4 - into the chamber. 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.

[0020] 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.

[0021] 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.

[0022] 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. 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.

[0023] The cage's function is to keep the balls at their designated distance and to absorb these high ball forces. Consequently, there are situations in which the cage must continue to push the balls forward while simultaneously protecting other components. P240298

[0024] - 5 - The forces attempt to brake the cage. In ordinary deep groove ball bearing applications, the balls run concentrically around the bearing center point, which is why the described forces have a subordinate influence on the cage load.

[0025] 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.

[0026] 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 keep the rolling elements at their intended distance.

[0027] 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 arm as a counterweight to the rotatable mass of the compressor wheel, thereby defining a chamber on the side diametrically opposite the arm which can receive a lubricant mixture and supply this lubricant mixture to the chamber P240298,

[0028] - 6 - adjacent rolling bearings, in particular the balls, is solved according to the invention in that the cage has several spherical cage pockets for receiving the balls, 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 cage axis of rotation provide 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.

[0029] 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:

[0030] 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 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.

[0031] 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.

[0032] The deliberately induced higher state of deformation, from which P240298

[0033] - 7 - Normally, higher stresses would result, but these are 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 at the same time, the reduced deformation component in the pocket area significantly reduces the stress concentration and stress level in the pocket area.

[0034] 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.

[0035] 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.

[0036] Preferably, the ribs do not connect the cage pockets with centrally located ribs. Instead, the ribs are arranged asymmetrically around the inner diameter. Thus, when rotating, the ball contacts an area of ​​the cage pocket that is not directly supported by a rib. This prevents crushing / compression. P240298

[0037] - 8 - avoided and preferably an elastic (bending) deformation occurs in the area of ​​the cage web. Because the cage web also deforms during this type of movement, since it is sufficiently flexible, the load in the pocket base decreases.

[0038] Alternatively, this embodiment can be replaced by a central bridge arrangement if the space between the retaining claws becomes too small.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Preferably, the spherical cage pockets are open in the radial direction both inwards and outwards. This allows contact between the balls and the outer surface. P240298

[0045] - 9 - inner ring so that the balls can run in the grooves of the outer and inner rings.

[0046] 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.

[0047] 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, thus locking the balls into the cage pockets.

[0048] 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.

[0049] Further aspects of the invention are explained in more detail with reference to the figures. They show:

[0050] Figure 1 shows an orbital bearing arrangement in an electromechanically operated spiral compressor,

[0051] Figure 2 shows the cage of the rolling bearing according to the invention of the orbital bearing arrangement according to Figure 1 ,

[0052] Figure 3 shows a first embodiment of the cage's struts,

[0053] Figure 4 shows a second version of the cage's struts,

[0054] Figure 5 shows the formation of the cage's starting zone on the outer ring and

[0055] Figure 6 shows the formation of the recess in the area of ​​the bridge.

[0056] Figure 1 shows an orbital bearing arrangement 1 in an electromechanically operated scroll compressor. The scroll compressor and the orbital bearing arrangement 1 comprise the following components for the illustration in Fig. 1: a housing 28, a main shaft bearing P240298

[0057] - 10 - ger 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.

[0058] 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 seal 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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 provided on the diametrically opposite side of the cantilever 12. In this chamber 13 P240298

[0063] - 11 - the introduced coolant collects and mixes with the lubricant present there to form a lubricant mixture.

[0064] 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.

[0065] 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.

[0066] Figure 2 shows the cage 8 of the rolling bearing 3 of the orbital bearing arrangement 1 according to Figure 1, as shown in the invention. 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 a better view of the invention. The second axial cage end 21 is the one 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 in the circumferential direction. 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 the respective retaining claw 25 facing the corresponding sphere 7 is spherical and / or congruent to the spherical shape of the corresponding sphere 7. Alternatively, this surface can also assume an oval shape. In any case, any surface curved in space is suitable within the scope of the invention, analogous to the spherical or oval shape, which does not define the sphere-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 indefinite mixture of the aforementioned contacts; the essential difference lies in the fact that the load on the sphere 7 on the retaining claw 25 during operation, due to the spherical and / or congruent surface shape, is characterized by a contact with respect to P240298.

[0067] - 12 -

[0068] Hertzian pressure-optimized contact is formed to match the deformation of the webs 14 and the cage 8 to the durability of the cage 8.

[0069] 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 imaginary, intangible 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 better illustrated in Figures 3 and 4. Essentially, 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.

[0070] 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.

[0071] 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).

[0072] 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 depiction of the outer ring 6 also provides a better view of the position and shape of the leading-edge zones 24 formed by the cage 8.

[0073] - 13 - understand. 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 due to its deformation by the balls 7 during operation during forward and / or reverse movement of the rolling bearing 3, can come into contact with the inner surface of the outer ring 6 via the running zone 24 – however, not necessarily all running zones 24 of the cage 8 simultaneously. It is sufficient if at least a few of the running zones 24, which come into contact with the outer ring 6 due to deformation of the cage 8, support the cage 8 on the outer ring 6, so that the load on the cage 8 is limited and it is not destroyed.

[0074] 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.

[0075] Figure 4 shows a second embodiment of the webs 14 of the cage 8. In this embodiment, which is an alternative to Figure 3, the webs 14 are located on the pocket pitch circle 10 – at least a portion of the web 14 intersects the pocket pitch circle 10. The recesses 26 are now located not only radially outside the pocket pitch circle 10, but also radially inside the pocket pitch circle 10.

[0076] The different effects of the two designs in Figures 3 and 4 lie in the fact that, although the ball 7 experiences a very similar contact start-up in the cage pocket 18 during operation in both designs, the force exerted by the ball 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 driven spiral compressor (e-scroll) by using different web placements, and the cage 8 can be adapted accordingly. P240298

[0077] - 14 -

[0078] 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 passes through these ball centers 31 in the geometrically ideal position of the balls 7 in the cage pockets 18.

[0079] 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 explained 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.

[0080] 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.

[0081] Figure 6 shows the design of the recess 26 in the area of ​​the web 14. Figure 6 shows the cage 8 from Figure 3 with the corresponding design of the recess 26. Figure 6 further 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 the circumferential direction (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 shape according to the invention. P240298

[0082] - 15 - follows the course and at the end forms a mirror-image edge zone to the next approach zone 24.

[0083] 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.

[0084] P240298

[0085] - 16 -

[0086] List of reference signs

[0087] 1 Orbital bearing arrangement

[0088] 2 compressor spirals

[0089] 3 rolling bearings

[0090] 4 Motor shaft

[0091] 5 inner ring

[0092] 6 outer ring

[0093] 7 balls

[0094] 8 cage

[0095] 9 Balancing ring

[0096] 10 pocket circle

[0097] 11 Motor shaft rotation axis

[0098] 12 outriggers

[0099] 13th Chamber

[0100] 14 Bridge

[0101] 15 Section plane

[0102] 16 Cage pivot axis

[0103] 17 compressor wheel

[0104] 18 cage bags

[0105] 19 main shaft bearings

[0106] 20 First axial cage end

[0107] 21 Second axial cage end

[0108] 22 Eccentricity

[0109] 23 levels

[0110] 24 Approach zone

[0111] 25 retaining claws

[0112] 26 Exclusion

[0113] 27 Seal

[0114] 28 cases

[0115] 29 Recess length

[0116] 30 -

[0117] 31 Center of sphere P240298

[0118] - 17 -

[0119] 32 Contact area to the outer ring

[0120] 33 Pocket Ground

[0121] 34 Inner surface area

[0122] 35 running groove

Claims

P240298 - 18 - Patentansprüche 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 in 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 the 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 P240298 - 19 - - 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 in 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 in 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 in 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 one of the preceding claims, characterized in that the spherical cage pockets (18) at the second axial cage end (21) are designed to be open and form retaining claws (25). P240298 - 20 - 6. Electromechanically operated spiral compressor according to one of the preceding claims, characterized in 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 one of the preceding claims, characterized in that the spherical cage pockets (18) are flexible in such a way that a ball (7) can be clipped into each cage pocket (18).

8. Electromechanically operated spiral compressor according to claim 7, characterized in 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.

Images