Cage for a bearing for a strut bearing unit

Abstract

Disclosed is a cage (1) for a bearing for a strut bearing unit, characterized in that the cage (1) is formed as a ring comprising a plurality of recesses forming cage pockets (6), wherein the recesses are configured to receive rolling elements (7) and to keep the rolling elements (7) spaced apart from each other, wherein an outer circumferential surface (3) and / or an inner circumferential surface (2) of the cage is configured to provide a sliding functionality when in contact with a part of the strut bearing unit.

Description

[0001] 202400200

[0002] 1

[0003] Cage for a bearing for a strut bearing unit

[0004] Technical field of the invention

[0005] The present invention relates to a cage for a bearing of a strut bearing unit according to claim 1. The present invention further relates to a corresponding strut bearing unit for a motor vehicle according to claim 5.

[0006] Background of the invention

[0007] In rolling bearings, cages are used to separate the rolling elements at equal distance to reduce frictional heat generated by the rolling elements in the bearing. Cages keep the rolling elements spaced apart from each other to ensure a consistent load distribution.

[0008] Rolling bearings, such as ball bearings, support and guide rotating or oscillating elements, such as shafts, axles or wheels, and transfer loads between machine components, wherein the rolling elements transfer the load between inner and outer rings. Radial bearings accommodate loads that are predominantly perpendicular to the shaft. Some radial bearings can support only pure radial loads, while most radial bearings can additionally accommodate axial loads.

[0009] Such rolling bearings may also be used in strut bearing units. A support strut may be used in automobile suspension systems for supporting an axle and a wheel of a vehicle. A strut bearing unit or suspension bearing unit is disposed in the upper part of the support strut, opposite the wheel and the ground, between a suspension spring and an upper member, which is integral with the chassis of the vehicle or can be mounted to the chassis of the vehicle. Such a strut bearing unit is adapted for transmitting axial forces between the suspension spring and the chassis of the vehicle. The strut bearing unit consists of a lower cup and an upper cup, wherein a bearing is arranged between the lower and the upper cup. In such strut bearing units, the bearing is required to support axial and / or radial loads. However, the currently used bearings are mainly configured to support axial loads, using the rolling elements.

[0010] It is therefore object of the present invention to provide an easy and cost-efficient possibility to support radial and axial loads in a strut bearing unit. 202400200

[0011] 2

[0012] Summary of the invention

[0013] This object is solved by a cage for a bearing for a strut bearing unit according to claim 1 and by a corresponding strut bearing unit according to claim 5.

[0014] In the following, a cage for a rolling bearing, particularly a ball bearing, for a strut bearing unit is provided. The cage comprises a plurality of recesses forming cage pockets. The cage pockets are configured to receive rolling elements and to keep the rolling elements spaced apart from each other. The ring comprises an inner and an outer circumferential surface as well as two end surfaces, wherein the recesses are formed in at least one of the end surfaces. Preferably, the recesses are formed as through openings from one end surface to the other end surface so that rolling elements being accommodated in the recesses may contact raceways arranged in contact with both end surfaces.

[0015] To provide a flexible and cost-efficient way of supporting axial and radial loads, an outer circumferential surface and / or an inner circumferential surface of the cage is configured to provide a sliding functionality when in contact with a part of the strut bearing unit. Thus, apart from the rolling functionality provided by the rolling elements which can be accommodated in the pockets, the cage is configured to provide a sliding functionality due to a possible contact between the inner and / or outer circumferential surface and the strut bearing unit. Thus, when the rolling bearing is applied with radial loads, the outer circumferential surface and / or inner circumferential surface slide alongside a part of the strut bearing unit. Thus, the cage provides a hybrid functionality by supporting radial loads via the sliding functionality of the inner and / or outer circumferential surfaces and axial loads via the rolling functionality of rolling elements within the pockets.

[0016] This has the advantage that the cage design improves the accommodation of radial and / or axial loads, which is a requirement for a wide range of motor vehicles. At the same time, the cage is flexibly applicable and thereby minimizes costs.

[0017] According to an embodiment, the cage further comprises a lubrication tank and through openings being provided in the outer circumferential surface, the inner circumferential surface and / or end surfaces of the cage, wherein the through openings are configured to provide a lubrication functionality by releasing lubricant from the lubrication tank to the outside of the 202400200

[0018] 3 cage. The lubrication tank and through openings in the outer and / or inner circumferential surfaces and / or end surfaces of the cage allow an easy way of supply of a lubricant. The lubrication tank and the through openings, which provide lubrication channels, are used to keep grease / oil and to distribute it over the sliding surfaces.

[0019] This may further improve the sliding functionality as the lubricant may be directly guided to the contact surfaces of the sliding functionality, i.e., to the inner / outer circumferential surfaces as well as the corresponding parts or surfaces of the strut bearing unit. Further, the functionality of the rolling bearing may be improved as the lubricant may be guided to the rolling contact surfaces, i.e., the raceways for the rolling elements provided by the strut bearing unit.

[0020] Preferably, the lubricant may be filled into the cage once before installation in the strut bearing unit. Thus, the cage and thus the bearing may be greased for the whole lifetime of the bearing.

[0021] According to a further embodiment, the lubricant is grease or oil. As explained above, the lubricant may facilitate the sliding functionality for cooperating in a sliding manner of the inner and / or outer circumferential surfaces of the cage with a part of the strut bearing unit.

[0022] According to a further embodiment, the cage is manufactured of low-friction material, in particular low-friction plastic material. For example, polymers with or without fillers (fibers) may be used, such as PEEK, POM, PA4.6, PA66, PA6-GF, or PA66-GF or other polymers. Particularly advantageous here are the good sliding properties of polymer cages, which produce little friction and, therefore, permit high speeds. For example, polymer cages may be made with a carbon or glass fiber content of 15% to 30%. Using (fiber) reinforcement may be advantageous and may provide a more stable material. In addition, low-friction material may provide the advantage that, under poor lubrication conditions, the cage with low-friction material reduces the risk of seizure and secondary damage because the cage can operate for some time with limited lubrication.

[0023] According to a further aspect, a strut bearing unit is provided. The strut bearing unit as further disclosed herein, also called suspension bearing unit, may particularly be of the MacPherson type (so called MacPherson suspension bearing unit). The strut bearing unit may be disposed 202400200

[0024] 4 in the upper part of the support strut, opposite the wheel and the ground, between a suspension spring and an upper member. The upper member may either be integral with the chassis of the vehicle or may be mounted to the chassis of the vehicle.

[0025] The strut bearing unit comprises a lower cup configured to support the suspension spring, an upper cup configured to couple with the top mount which provides a connection to a chassis of the motor vehicle, and a bearing interposed between the upper cup and the lower cup.

[0026] The bearing of the strut bearing unit as described herein may comprise an inner ring, an outer ring and a cage as described above. The bearing may further comprise a plurality of rolling elements which are interposable between the inner ring and the outer ring and accommodatable within the pockets provided by the cage. As will be described in the following, the bearing may be provided with none, some, or a plurality of rolling elements.

[0027] In order to provide a less expensive and more simple design, the bearing of the strut bearing unit as described herein may comprise an inner ring formed by the lower cup of the strut bearing unit and / or an outer ring formed by the upper cup of the strut bearing unit.

[0028] The above-described design of the strut bearing unit results in a flexible design and reduced costs. In contrast to previously used strut bearing units, the here described unit facilitates the accommodation of radial and / or axial loads for rolling bearings due to the cage as described above.

[0029] According to an embodiment, none of the cage pockets of the strut bearing unit receives rolling elements. Thus, the cage may be free of rolling elements. For example, all cage pockets of the strut bearing unit may be free of rolling elements, when the strut bearing unit is applied with low radial loads. In such a case, the strut bearing unit is required to support mainly radial loads. The cage design, which is able to support radial loads due to the sliding functionality, allows a flexible application of the strut bearing unit. Low radial loads may be, for example, loads up to 8000 N, which may be supported by the sliding functionality. Higher loads, for example loads above 8000 N may be supported in addition to by the rolling contact as will be described above. It should be noted that the exact numbers of higher and / or lower loads may vary depending on the specific bearing and application. 202400200

[0030] 5

[0031] According to a further embodiment, some of the cage pockets receive rolling elements. For example, more than one of the cage pockets may receive rolling elements when the strut bearing unit is applied with radial and / or axial loads. The rolling elements may be equally distributed around the circumference of the cage, providing an even distribution of the applied load.

[0032] In another embodiment, all cage pockets receive rolling elements. This may be specifically provided, when high radial and axial loads are applied to the strut bearing unit. This may improve the support of radial and / or axial loads of the strut bearing unit.

[0033] For example, the cage may be formed as a solid ring which provides enough stability for providing a main contact with the strut bearing unit in case of low loads and may be flexible enough to allow a rolling element contact in case of high loads.

[0034] According to a preferred embodiment, the strut bearing unit comprises an inner and / or an outer raceway being formed as a separate annular raceway element being disposed on the inner and / or the outer ring, respectively. The raceway element may be disposed as a separate element on the inner and / or outer ring, respectively, for example by means of injection molding or similar processes well known in the art. This ensures an improved sliding contact and rolling contact of the rolling bearing. In particular, the separate raceway elements may be formed by different materials than the upper and / or lower cup of the strut bearing unit. Thus, the raceway elements may be formed using a material improving the characteristics and functions of the rolling elements and rolling bearing. In contrast to that, the material of the upper and / or lower cup of the strut bearing unit may be chosen to improve for example the stability and service life of the strut bearing unit itself.

[0035] In alternative embodiments, the inner and / or outer ring do not comprise an inner and / or outer raceway being formed by separate elements. In this case, the raceways may be directly formed by the upper and / or lower cup.

[0036] According to a further embodiment, the raceway is made of low friction material. The low friction material may be polymers, such as PEEK, PA4.6, PA6.6, PA6-GF, or PA66-GF. Such a material may particularly improve the functionality of the rolling bearing and may reduce the wear of the rolling elements. The raceway elements may also be made of sheet metal. 202400200

[0037] 6

[0038] Further preferred embodiments are defined in the dependent claims as well as in the description and the figures. Thereby, elements described or shown in combination with other elements may be present alone or in combination with other elements without departing from the scope of protection.

[0039] Brief description of the drawings

[0040] In the following, preferred embodiments of the invention are described in relation to the drawings, wherein the drawings are exemplarily only, and are not intended to limit the scope of protection. The scope of protection is defined by the accompanied claims, only.

[0041] The figures show:

[0042] Fig. 1 : a perspective view of an exemplary cage for a strut bearing unit;

[0043] Fig. 2A: a sectional view of a cage pocket of the cage of Fig. 1;

[0044] Fig. 2B: a sectional view of the cage of Fig. 1;

[0045] Fig. 3 A: a sectional view of the cage pocket together with a rolling element of a rolling bearing in a strut bearing unit;

[0046] Fig. 3B: a sectional view of the cage of a rolling bearing in strut bearing unit;

[0047] Fig. 3C: a sectional view of the cage together with a lubrication tank of a rolling bearing in a strut bearing unit; and

[0048] Fig. 4: a perspective view of a strut bearing unit.

[0049] Detailed description of the invention

[0050] In the following same or similar functioning elements are indicated with the same reference numerals.

[0051] Fig. 1 shows a cage 1 for a bearing 10 for a strut bearing unit 20, being formed as a ring. The ring comprises a plurality of recesses forming cage pockets 6. The recesses are configured to receive rolling elements 7 and to keep the rolling elements 7 spaced apart from each other. The cage 1 comprises an outer circumferential surface 3 and an inner circumferential surface 2. At least one of the circumferential surfaces 2, 3 is configured to provide a sliding functionality when in contact with a part of the strut bearing unit (not shown in Fig. 1). 202400200

[0052] 7

[0053] As shown in Fig. 2A in a sectional view of Fig. 1, the cage pocket 6 may comprise a rolling element 7 for transmitting loads. As it can further be seen, besides the inner circumferential surface 2 and outer circumferential surface 3, the cage further comprises the end surfaces 4. Fig. 2B shows in a further, different sectional view of Fig. 1, the inner circumferential surface 2, the outer circumferential surface 3 and the end surfaces 4.

[0054] Apart from the cage 1, Fig. 2A and 2B show the outer raceway 5a and the inner raceway 5b which are not part of the cage 1 but are elements of the rolling bearing. The inner raceway 5b and / or the outer raceway 5a may be preferably disposed as a separate element on the inner ring formed by a lower cup 21 of the strut bearing unit 20 and / or outer ring formed by an upper cup 22 of the strut bearing unit 20 (as shown and explained in further detail with respect to Figs. 3A, 3B, 3C, and 4). By this arrangement, an improved sliding and rolling contact of the rolling bearing 10 is achieved.

[0055] Other arrangements are also possible, for example the inner ring formed by the lower cup 21 of the strut bearing unit 20 and the outer ring formed by the upper cup 22 of the strut bearing unit 20 may not comprise an inner raceway 5b and / or an outer raceway 5a being formed by separate elements. In this case, the raceways may be directly formed by the lower cup 21 of the strut bearing unit 20 and / or the upper cup 22 of the strut bearing unit 20.

[0056] As can be seen in Figs. 3A, 3B, and 3C, the strut bearing unit 20 comprises a bearing 10 being arranged between the upper cup 22 and the lower cup 21. In the illustrated embodiment, the inner ring of the bearing 10 is formed by the lower cup 21 of the strut bearing unit 20 and the outer ring of the bearing 10 is formed by the upper cup 22 of the strut bearing unit 20. Alternatively, the inner ring and / or the outer ring could also be formed by separate elements being inserted into the upper cup 22 or the lower cup 21. The cage 1 with the inner circumferential surface 2, the outer circumferential surface 3, and the end surfaces 4 is arranged between the inner ring and outer ring.

[0057] The strut bearing unit 20 may comprise the inner raceway 5b and the outer raceway 5a being formed by separate elements. In a preferred arrangement, the raceways 5a and 5b are disposed as separate elements on the inner ring formed by the lower cup 21 of the strut bearing unit 20 and / or outer ring formed by the upper cup 22 of the strut bearing unit 20. In a possible other 202400200

[0058] 8 arrangement, the strut bearing unit 20 may not comprise separate elements for the inner raceway 5b and / or the outer raceway 5a.

[0059] With reference to Fig. 3 A, the rolling element 7 is shown which is arranged in the cage pocket 6 of the cage 1 of the rolling bearing 10. In the illustrated embodiment, the strut bearing unit 20 comprises the inner raceway 5b and the outer raceway 5a being formed by separate elements being disposed on the inner ring formed by the lower cup 21 of the strut bearing unit 20 and / or outer ring formed by the upper cup 22 of the strut bearing unit 20, respectively. The raceway 5a, 5b ensures an improved sliding contact and rolling contact of the rolling bearing 10. The raceway 5a, 5b may be formed using a material improving the characteristics and functions of the rolling elements 7 and rolling bearing 10, such as low friction material. The low friction material may be polyamide, such as PEEK, PA4.6, PA6.6, PA6-GF, or PA66-GF, which may particularly improve the functionality of the rolling bearing 10 and may reduce the wear of the rolling elements 7.

[0060] As can be seen in Fig. 3B, the inner circumferential surface 2 and the outer circumferential surface 3 of the cage 1 are configured to provide a sliding functionality 11 when in contact with a part of the strut bearing unit 20. The sliding functionality 11 supports radial forces. When the bearing 10 is applied with radial loads, the inner circumferential surface 2 and / or outer circumferential surface 3 may slide alongside a part of the strut bearing unit 20, transmitting the radial loads from the cage 1 to the upper and / or lower cup 21, 22 of the strut bearing unit 20 and vice versa.

[0061] Fig. 3C shows a possible arrangement of the lubrication tank 9 and through openings 12 being provided in the inner circumferential surface 2 and the outer circumferential surface 3 and / or end surfaces 4. The openings allow the supply of a lubricant onto the sliding contact surfaces, i.e., the circumferential surfaces and the corresponding surfaces of the strut bearing unit 20, as well as onto the rolling contact surfaces, i.e., the raceways 5a, 5b and the rolling elements 7. Other arrangements are also possible, e.g., the at least one through opening may be configured as refill opening for introducing the lubricant into the lubrication tank of the cage (not shown in Fig. 3C).

[0062] With reference to Fig. 4, the assembly of the strut bearing unit 20 will be described in further detail. 202400200

[0063] 9

[0064] The strut bearing unit 20 comprises the cage 1 formed as a ring for the bearing 10 with inner circumferential surface 2, outer circumferential surface 3, and end surface 4. The cage 1 is arranged between the inner ring of the bearing 10 formed by the lower cup 21 of the strut bearing unit 20 and the outer ring of the bearing 10 formed by the upper cup 22 of the strut bearing unit 20.

[0065] The strut bearing unit 20 provides the outer raceway 5a and the inner raceway 5b. The raceway 5a, 5b may be preferably disposed as a separate element on the inner ring formed by the lower cup 21 of the strut bearing unit 20 and / or the outer ring formed by the upper cup 22 of the strut bearing unit 20. As can be seen in Fig. 4, the outer raceway 5a and the inner raceway 5b are configured as annular raceway elements which can easily be inserted into the upper cup 22 and / or the lower cup 21. Alternatively, the raceway elements 5a, 5b may be formed via injection molding or the like.

[0066] In other arrangements, the strut bearing unit 20 may not comprise separate elements as outer raceway 5a and / or the inner raceway 5b and the raceways 5a, 5b may be provided directly by the inner ring and / or outer ring.

[0067] After assembly of the strut bearing unit 20, the outer circumferential surface 3 and the inner circumferential surface 2 of the cage 1 provide a sliding functionality 11 when in contact with a part of the strut bearing unit 20.

[0068] In summary, the herein described cage for a bearing and strut bearing unit associated therewith provides a flexible design along with reduced costs and improves the accommodation of radial and / or axial loads. 202400200

[0069] 10

[0070] Reference numerals

[0071] 1 cage

[0072] 2 inner circumferential surface

[0073] 3 outer circumferential surface

[0074] 4 end surface

[0075] 5 a outer raceway

[0076] 5b inner raceway

[0077] 6 cage pocket

[0078] 7 rolling element

[0079] 9 lubrication tank

[0080] 10 bearing

[0081] 11 sliding functionality

[0082] 12 through openings

[0083] 20 strut bearing unit

[0084] 21 lower cup

[0085] 22 upper cup

Claims

20240020011C l a i m sCage for a bearing for a strut bearing unit1. A cage (1) for a bearing for a strut bearing unit, characterized in that the cage (1) is formed as a ring comprising a plurality of recesses forming cage pockets (6), wherein the recesses are configured to receive rolling elements (7) and to keep the rolling elements (7) spaced apart from each other, wherein an outer circumferential surface (3) and / or an inner circumferential surface (2) of the cage is configured to provide a sliding functionality when in contact with a part of the strut bearing unit.

2. The cage (1) according to claim 1 further comprising a lubrication tank (9) and through openings (12) being provided in the outer circumferential surface (3), the inner circumferential surface (2) and / or end surfaces of the cage, wherein the through openings (12) are configured to provide a lubrication functionality by releasing lubricant from the lubrication tank (9) to the outside of the cage.

3. The cage (1) according to claim 2, wherein the lubricant is grease or oil.

4. The cage (1) according to any one of the preceding claims, wherein the cage (1) is made of low-friction material, in particular low-friction plastic material.

5. A strut bearing unit (20) for a motor vehicle, comprising a lower cup (21) configured to support a suspension spring, an upper cup (22) configured to connect to a chassis of the motor vehicle, and a bearing (10) interposed between the upper cup (22) and the lower cup (21), characterized in that the bearing (10) comprises an inner ring, an outer ring and a cage (1) according to any one of the claims 1 to 5, wherein a plurality of rolling elements (7) is interposable between the inner ring and the outer ring and accommodatable within the pockets (6) provided by the cage.202400200126. The strut bearing unit (20) according to claim 5, wherein the inner ring is formed by the lower cup (21) and / or wherein the outer ring is formed by the upper cup (22).

7. The strut bearing unit (20) according to claim 5 or 6, wherein the cage pockets (6) are free of rolling elements (7).

8. The strut bearing unit (20) according to claim 5 or 6, i) wherein some of the cage pockets (6) are filled with rolling elements (7), or ii) wherein all cage pockets (6) are filled with rolling elements (7).

9. The strut bearing unit (20) according to any one of claims 5 to 8, comprising an outer raceway (5a) and / or an inner raceway (5b) formed as a separate annular raceway element (23) being disposed on the inner and / or the outer ring, respectively.

10. The strut bearing unit (20) according to claim 9, wherein the outer and / or the inner raceway (5a, 5b) is made of low friction material.

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