ANGULAR CONTACT BALL BEARING AND TRANSMISSION ASSEMBLY

Abstract

An angular contact ball bearing includes an outer ring having an outer diameter D and a first rolling surface and an inner ring having an inner diameter d and a second rolling surface, and no more than one row of balls between the first rolling surface and the second rolling surface, each of the balls having a diameter D.sub.w. The diameter D.sub.w of the balls, the outer diameter D of the outer ring, and the inner diameter d of the inner ring satisfy the relationship:

[00001]$\frac{2.Math.D_w}{D-d}>0.7.$

Claims

1. An angular contact ball bearing, comprising: an outer ring having an outer diameter D and having a first rolling surface, an inner ring having an inner diameter d and having a second rolling surface, and no more than one row of balls disposed between the first rolling surface and the second rolling surface, each of the balls having a diameter D.sub.w, wherein the diameter D.sub.w of the balls, the outer diameter D of the outer ring, and the inner diameter d of the inner ring are chosen such that they satisfy the relationship: $\frac{2.Math.D_w}{D-d}>0.7.$

2. The angular contact ball bearing according to claim 1, wherein the outer ring includes a radially inwardly directed shoulder having a minimum diameter D.sub.1, wherein the first rolling surface has a diameter D.sub.2 at a base of the first rolling surface, and wherein a ratio of D.sub.1 to D.sub.2 is between 0.85 and 0.91.

3. The angular contact ball bearing according to claim 2, wherein the inner ring has a radially outwardly directed shoulder having a maximum diameter d.sub.1, wherein a reciprocal ratio of d.sub.1 to a diameter d.sub.2 of a raceway base of the second rolling surface is between 0.79 and 0.85.

4. The angular contact ball bearing according to claim 3, wherein a minimum axial width of the shoulder of the inner ring is wider than a maximum axial width of the shoulder of the outer ring.

5. The angular contact ball bearing according to claim 1, wherein a number Z of balls, where $Z=\left(\frac{180}{\arcsin .Math.\frac{D_w}{D_{p.Math..Math.W}}}\right)-1$ is disposed between the inner ring and the outer ring, where D.sub.pW indicates a pitch circle diameter of the angular contact ball bearing and Z is rounded to a whole number.

6. The angular contact ball bearing according to claim 1, wherein a pressure angle of the angular contact ball bearing is between 15 and 35.

7. The angular contact ball bearing according to claim 1, including a cage for guiding the balls, wherein the second rolling surface includes an elevation directed radially outward and axially opposite the radially inward directed shoulder of the outer ring, the elevation being configured to cooperate with the radially inward directed shoulder and the cage such that the balls are captively retained on the inner ring.

8. The angular contact ball bearing according to claim 4, wherein a number Z of balls, where $Z=\left(\frac{180}{\arcsin .Math.\frac{D_w}{D_{p.Math..Math.W}}}\right)-1$ is disposed between the inner ring and the outer ring, where D.sub.pW indicates a pitch circle diameter of the angular contact ball bearing and Z is rounded to a whole number, and wherein a pressure angle of the angular contact ball bearing is between 15 and 35.

9. The angular contact ball bearing according to claim 1, wherein the first rolling surface has a first cylindrical portion and a second portion curving away from the first cylindrical portion toward the inner ring and wherein the second rolling surface has a first cylindrical portion and a second portion curving away from the first cylindrical portion of the second rolling surface toward the outer ring and wherein the balls contact the first cylindrical portion of the first rolling surface and the second portion of the first rolling surface and the first cylindrical portion of the second rolling surface and the second portion of the second rolling surface.

10. A transmission assembly for a motor vehicle including: a housing; a shaft having a gear element rotatably supported in the housing via at least two axially spaced angular contact ball bearings according to claim 1.

11. The transmission assembly according to claim 10, wherein the at least two angular contact ball bearings are identical and set in back-to-back arrangement with respect to each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 shows an embodiment of the invention,

[0030] FIG. 2 shows a cage, and

[0031] FIG. 3 shows a section of a transmission assembly according to an embodiment of the invention.

DETAILED DESCRIPTION

[0032] In FIG. 1 an angular contact ball bearing 1 according to a preferred embodiment of the disclosure is depicted. The angular contact ball bearing 1 comprises an outer ring 3, an inner ring 5, between which balls 7 are disposed. The balls 7 are retained by a cage 9. On the outer ring 3 a radially inwardly directed shoulder 13 is formed, beginning on whose inner side a raceway 15 is formed for the balls 7. Analogously on inner ring 5 a radially outwardly directed shoulder 17 is formed, beginning on whose inner side a raceway 19 for the balls 7 is formed. The balls 7 osculate on a radius r.sub.a of the raceway 15 and a radius r.sub.i of the raceway 19 in the region of the contact. Here the osculation is selected to be significantly narrower in comparison to angular contact ball bearings of known design, whereby a better compression can be achieved. For further optimization of the compression it is preferably the same size on both raceways 15 and 19, which is thus achieved on outer ring 3 by providing a smaller osculation on the raceway 19, i.e., on the inner ring 5 in comparison to the raceway 15. r.sub.a>r.sub.i consequently applies.

[0033] The angular contact ball bearing 1 differs significantly from known angular contact ball bearings with respect to its size ratios. Thus the diameter D.sub.w of the balls, the outer diameter D of the outer rings, and the inner diameter d of the inner rings is chosen such that they have the relationship

[00005]$\frac{2.Math.D_w}{D-d}>0.7$

[0034] to one another. Consequently due to their large diameter in comparison to the structural height Dd of the bearing the balls occupy a large part of the installation space. This has the result that at the point that lies radially outside the balls 7 the outer ring 3 is relatively thin. Likewise, the thickness of the inner ring 5 is comparatively thin at the location radially inside the balls 7. Due to the large ball diameter D.sub.w the angular contact ball bearing 1 is able to assume unusually high loads for this bearing type. The load rating is exceptionally high, with the result that it is even suitable for applications for which other bearing types, such as, for example, tapered roller bearings or double row angular contact ball bearings are otherwise used. It has been shown that higher load ratings can be achieved even than with double row angular contact ball bearings of identical outer dimensions (B, D and d). At the same time friction is significantly reduced. This decisively results from a reduced rolling resistance in comparison to the two other bearing types. In addition, the angular contact ball bearing 1 is less sensitive in the case of misalignments.

[0035] The outer ring 3 which is thin in places in cross-section includes a shoulder 13 of relatively greater thickness DD.sub.1. The ratio of D.sub.1 to the diameter D.sub.2 of the raceway base of the first rolling surface falls between 0.85 and 0.91. This increases the stability and the loadability of the angular contact ball bearing 1. The same applies for the inner ring 5 and its shoulder 17, whose radial thickness d.sub.1d is even greater than DD.sub.1. The reciprocal ratio of d.sub.1 to the diameter d.sub.2 of the raceway base of the second rolling surface falls between 0.79 and 0.85.

[0036] In addition the shoulder 17 is wider than the shoulder 13 with respect to its axial thickness. The dimensioning of the shoulder in the axial direction makes it possible, among other things, to replace existing bearings of another design, e.g., tapered roller bearings or double row angular contact ball bearings, by a single row angular contact ball bearing according to the disclosure and to fill the existing, usually significantly larger-dimensioned installation space.

[0037] On the inner ring 5 an elevation 11 is formed axially adjacent to the raceway 17. This serves to form a captive unit from inner ring 5, balls 7, and cage 9, even when the outer ring 3 is not yet present. In numerous situations the manufacturing process of more complex mechanical units requires a separate assembly of outer ring 3 and inner ring 5. Then it is advantageous when the balls 7 and the cage 9 are already captively held in on the inner ring 5 and the assembly is thus simplified.

[0038] The balls 7 have a defined pressure angle with the raceways 13 and 17. The angular contact ball bearing is thus able to support both axially and radially acting forces. The pressure angle preferably falls between 15 and 35, ideally at 25. This has proven to be advantageous in particular for high loads, since the load rating is particularly high in combination with the relatively large balls 7.

[0039] The cage 9 guiding and retaining the balls 7 is depicted sectionally in FIG. 2. It is designed such that a relatively high number Z of balls can be used in angular contact ball bearing 1, which in turn leads to an increase of the load rating of the angular contact ball bearing 1. The number Z is defined as follows:

[00006]$Z=\left(\frac{180}{\arcsin .Math.\frac{D_w}{D_{p.Math..Math.W}}}\right)-1$

[0040] wherein D.sub.pW is the pitch circle diameter of the angular contact ball bearing 1 and Z is rounded to a whole number. If a higher load rating and a greater stiffness is required, then more balls 7 can also be used. Only on its left side the cage 9 includes an annular guide structure 31 on which claw-type extensions 33 extend essentially in the axial direction. A plurality of the extensions 33 respectively form a pocket for receiving a ball of the angular contact ball bearing 1. In a cage 9 configured in this manner relatively many balls 7 can be held.

[0041] In FIG. 3 a part of a transmission assembly 101 is sectionally depicted. A drive pinion 103 is connected to a drive shaft 105, depicted here shortened, which is supported in a housing 109 via two angular contact ball bearings 107 and 107. Due to the high loads, tapered roller bearings or double row angular contact ball bearings are typically currently used in such applications. In this application the angular contact ball bearing 107 lying closer to the drive pinion 103 is subjected to particularly high loads, which makes necessary a correspondingly high load rating C in the range of more than 30 kN in typical application cases. This cannot be achieved using known single row angular contact ball bearings. Therefore the angular contact ball bearings 107 and 107 are embodied according to the embodiment depicted in FIG. 1 and accordingly suitable for this application.

[0042] Preferably the angular contact ball bearings 107 and 107 are dimensioned with respect to their outer dimensions such that they are suitable for replacing existing double row angular contact ball bearings or tapered roller bearings in already existing transmission assemblies. This is illustrated in FIG. 3 by the inner rings of the angular contact ball bearings 107 and 107 being axially wide enough such that they fit into a receptacle of a previously used tapered roller bearing or double row angular contact ball bearing and can replace them without effort. Thus a reduction can be achieved therein of the friction by relatively simple replacing of the bearing, for example, in the case of service. The design of the angular contact ball bearings 107 and 107 allows this due to the thinly embodied inner and outer rings, the large balls, and the shoulder embodied axially wide.

[0043] Angular contact ball bearings according to the disclosure can also be used analogously in newly designed applications. Here an axially narrower design of the inner rings is also possible, which approximately corresponds to the axial width of the outer ring. Thus angular contact ball bearings according to the disclosure can be used in numerous applications and correspondingly flexibly designed.

[0044] Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved angular contact ball bearings.

[0045] Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

[0046] All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

REFERENCE NUMBER LIST

[0047] 1 Angular contact ball bearing [0048] 3 Outer ring [0049] 5 Inner ring [0050] 7 Balls [0051] 9 Cage [0052] 11 Elevation [0053] 13, 17 Shoulder [0054] 15, 19 Raceway [0055] 31 Guide structure [0056] 101 Transmission assembly [0057] 103 Drive pinion [0058] 105 Drive shaft