Tapered roller bearing and arrangement

Abstract

The present invention relates to a tapered roller bearing (1) which has an improved CO2 balance. According to the invention, the tapered roller bearing, which has a maximum outside diameter (D) of 100 mm and a maximum bearing cross-sectional height (H) of 22.5 mm, wherein the bearing height is described by half the difference between the bearing outside diameter and the bearing inside diameter (d), comprises an outer bearing ring (5), an inner bearing ring (3), a plurality of tapered rollers (7), and a cage (8). The tapered rollers (7) are each received in respective pockets, which are defined by the ring-shaped part on the side with a small diameter, by the ring-shaped part on the side with a large diameter and by two adjacent support parts, and form contact faces. The bearing forms a radial diameter distance (X) between the supporting rim outside diameter (SBA) and the raceway tip diameter (LSD) that is 4.5 mm > X > 1.5 mm. The outer bearing ring of the bearing has an outer ring cross section at the point of intersection between the nominal pressure angle vector (9) and the outer bearing ring (Q1) that is defined by the bearing height multiplied by an outer ring cross section factor (S), wherein the outer ring cross section factor is 0.2 < S < 0.3, and wherein the inner bearing ring has an inner ring cross section at the point of intersection between the nominal pressure angle vector and the outer bearing ring (Q2) that is defined by the bearing height multiplied by an inner ring cross section factor (M), wherein the inner ring cross section factor is 0.15 < M < 0.23.

Description

[0001] Roller bearings and arrangement

[0002] The present invention relates to a tapered roller bearing and a manufacturing method for a tapered roller bearing.

[0003] Tapered roller bearings are used in many applications and are used to transfer radial-axial loads between bearings. In typical design, such a rolling element bearing comprises two bearing rings and tapered rollers arranged between the bearing rings. The tapered rollers are often guided in a cage. Due to their high bearing load ratings, roller bearings are suitable for applications requiring high load capacities.

[0004] The fundamental aim is to design rolling bearings with as little friction as possible and a sufficiently high load-bearing capacity. DE 102017 105 479 A1 describes a tapered roller bearing of this type. The roller bearing essentially consists of several tapered rolling elements arranged between an inner bearing ring and an outer bearing ring, which are guided by the bearing cage. A support rim is provided on the sides of the inner bearing ring. The bearing rings are sufficiently dimensioned to support the calculated loads.

[0005] DE 10 2005 017 588 B3 describes a method for producing a bearing ring for a tapered roller bearing, in which an annular disk is provided and then axially deep-drawn. The blank requires post-processing, for example, a stamping step in which the axially deep-drawn area of ​​the blank is further shaped. It is emphasized that cold sheet forming appears suitable, particularly for small and medium-sized tapered roller bearings. One advantage cited is that, in contrast to hot forming, turning the tapered roller bearing ring blanks is unnecessary. The object of the present invention is to improve a roller bearing with regard to its CO2 balance and to propose an improved manufacturing method.

[0006] According to the invention, the object is achieved by a tapered roller bearing according to claim 1 and by a method for producing a tapered roller bearing according to claim 7.

[0007] The invention is particularly effective for tapered roller bearings with a maximum outer diameter of 100 mm and a maximum bearing cross-sectional height of 22.5 mm, where the bearing height is defined as half the difference between the bearing outer diameter and the bearing inner diameter, which primarily reflects applications in the automotive sector. Such a bearing comprises an inner bearing ring with an inner raceway formed on an outer peripheral surface thereof, an outer bearing ring with an outer raceway formed on an inner peripheral surface thereof, and a plurality of tapered rollers arranged between the inner raceway of the inner bearing ring and the outer raceway of the outer bearing ring. The rollers have a small roller diameter and a large roller diameter, as well as a roller length, and a cage configured to hold the tapered rollers in a plurality of positions in a circumferential direction.The inner bearing ring has a support rib at least on the larger-diameter side, with the outer diameter of the support rib defining the support rib outer diameter. The outer raceway of the outer bearing ring defines the raceway tip diameter on its smaller-diameter side.

[0008] A radial diameter distance is formed between the support rim outer diameter and the raceway tip diameter, wherein this radial diameter distance is more than 1.5 and less than 4.5 mm. The outer bearing ring has an outer ring cross-section at the intersection point between the nominal pressure angle vector and the outer bearing ring Q1, which is defined by the bearing cross-sectional height multiplied by an outer ring cross-sectional factor, wherein the outer ring cross-sectional factor is more than 0.2 and less than 0.3, and wherein the inner bearing ring has an inner ring cross-section at the intersection point between the nominal pressure angle vector and the inner bearing ring Q2, which is defined by the bearing height multiplied by an inner ring cross-sectional factor, wherein the inner ring cross-sectional factor is more than 0.15 and less than 0.23. The nominal pressure angle vector itself runs as a perpendicular to the tapered roller axis of rotation through the center of the roller length.

[0009] As mentioned above, the bearing rings available in the state of the art for tapered roller bearings are designed for sufficient load-bearing capacity. Due to their original use in industrial applications, no need for improvement in their CO2 footprint has been identified to date. As a result, the material required for tapered roller bearings is relatively high in the state of the art.With regard to an improved CO2 balance, it has surprisingly been discovered that previously unknown tapered roller bearings with a maximum outer diameter of 100 mm and a maximum bearing cross-sectional height of 22.5 mm, where the bearing height is described as half the difference between the bearing outer diameter and the bearing inner diameter, with the aforementioned inner or outer ring cross-sections at the intersection point between the nominal contact angle vector and the respective bearing ring, can achieve an almost equivalent load-bearing capacity of the bearing with significantly reduced material usage. The lower limit of the inner ring or outer ring cross-sectional factor is influenced on the one hand by ensuring sufficient roundness of the bearing ring during production. It has been found that above this limit, such bearing rings are no longer shape-stable and therefore only require minimal blank machining.Furthermore, this value provides a bearing ring with sufficient load-bearing capacity. The upper limit of the inner ring and outer ring cross-sectional factor is derived from a particularly energy- and material-saving manufacturing process for the blanks.

[0010] The radial diameter distance in the range of more than 1.5 mm and less than 4.5 mm has the effect of allowing particularly ideal, energy- and material-saving production. Ideally, this is achieved starting from a forged tower blank, which enables the production of an inner bearing ring and an outer bearing ring using an optimized forged blank. It has been found that with this type of bearing design, up to 20% CO2 can be saved by the time a tapered roller bearing is completed. In a preferred embodiment of the tapered roller bearing, the ratio of the roller length of the tapered rollers to the large roller diameter, i.e. the diameter of the tapered rollers on their larger diameter side, is more than 1.1 and less than 1.7.This range of the ratio of the large roller diameter to the roller length ensures that the length of the rolling elements is kept short relative to the diameter in order to provide the smallest possible ring widths, with regard to material use and weight, combined with sufficient load-bearing capacity.

[0011] It is particularly advantageous to also design the cage with reduced CO2 emissions. In one embodiment, this is made of plastic. It is conceivable and particularly advantageous for the cage to be made of biomass-based polyamide with a glass fiber content. Biomass-based or biobased PAs are polyamides made from annually renewable biomass such as vegetable oils. These materials are particularly characterized by their excellent mechanical strength and chemical resistance.

[0012] Furthermore, it is advantageous if the inner and outer bearing rings of the tapered roller bearing are made of chromium steel with a secondary content of 10% to 95%. Due to the high secondary content, i.e., recycled material in the form of melted scrap, the carbon footprint is particularly favorable. In the context of this invention, chromium steel is understood to mean through-hardening bearing steel with a carbon content of approximately one percent (+ / -0.1%) and a chromium content between one and two percent. Examples include 100Cr6 or 100CrMnSi6-4.

[0013] To achieve a particularly positive CO2 balance for the aforementioned bearing, a manufacturing process is proposed as follows. First, a forged tower blank is provided whose overall width is smaller than the combined width of the outer bearing ring and the inner bearing ring in their final dimensions. This enables a particularly energy- and material-saving blank. Furthermore, this blank exhibits an ideal grain pattern with ideal mechanical characteristics for the bearing rings to be manufactured from it. In general, this manufacturing process differs significantly from manufacturing processes using deep drawing from semi-finished sheet metal. The same applies to the bearing rings manufactured in this way.

[0014] The blank is then separated into two annular sections within the radial diameter distance. The radial diameter distance is the distance between the outer diameter of the support rib of the manufactured inner bearing ring and the raceway tip diameter of the manufactured outer bearing ring. It is also conceivable to implement this in the same tool. The annular sections are then machined to form an inner bearing ring and an outer bearing ring. After hardening, the bearing rings are machined to their final dimensions. The bearing rings manufactured in this way can then be assembled with the other bearing components, such as the cage and tapered rollers, to form a CO2-reduced tapered roller bearing.

[0015] The tapered roller bearing described is particularly suitable for use in transmissions of electrically powered vehicles, both in pure electric vehicles and in so-called plug-in hybrid vehicles, for example, for supporting the intermediate shaft or differential shaft. The CO2 footprint plays a particularly important role in such applications.

[0016] The preferred embodiment of the invention is explained in more detail below with reference to the accompanying drawings.

[0017] They show:

[0018] Fig. 1 shows a schematic section through a tapered roller bearing;

[0019] Fig. 2 is a sectional view of a forged tower blank with the schematic arrangement of the bearing rings for the method of manufacturing a tapered roller bearing;

[0020] Figure 1 shows a schematic section through a tapered roller bearing 1 in a representation longitudinal to the axis of rotation 2. The tapered roller bearing 1 comprises an inner bearing ring 3 with an inner raceway 4 formed on an outer circumferential surface thereof, an outer bearing ring 5 with an outer raceway 6 formed on an inner circumferential surface thereof, a plurality of tapered rollers 7 arranged between the inner raceway 4 of the inner bearing ring 3 and the outer raceway 6 of the outer bearing ring 5, and a cage 8 (not shown in detail) which is configured to hold the plurality of tapered rollers 7 in a plurality of positions in a circumferential direction.

[0021] The tapered roller bearing 1 has a maximum outer diameter D of 100 mm and a maximum bearing cross-sectional height H of 22.5 mm, wherein the bearing height H is described by half the difference between the bearing outer diameter D and the bearing inner diameter d. The tapered rollers have a small roller diameter DS and a large roller diameter DW as well as a roller length LW. The inner bearing ring 3 has a support rib 8 at least on the larger diameter side, the outer diameter of which describes a support rib outer diameter SBA, wherein the outer racing surface 6 of the outer bearing ring 5 describes a raceway tip diameter LSD on its smaller diameter side, wherein a radial diameter distance X is formed between the support rib outer diameter LSD and the raceway tip diameter SBA, the radial diameter distance being 4.5 mm > X > 1.5 mm.The outer bearing ring 5 has an outer ring cross-section at the intersection point between the nominal pressure angle vector 9 and the outer bearing ring Q1, which is defined by the bearing height H multiplied by an outer ring cross-section factor S, where the outer ring cross-section factor is 0.2.

[0022] < S < 0.3. The nominal pressure angle vector 9 runs as a perpendicular to the tapered roller axis of rotation through the center of the roller length LW. The inner bearing ring 3 has an inner ring cross-section at the intersection point between the nominal pressure angle vector 9 and the inner bearing ring Q2, which is defined by the bearing height H multiplied by an inner ring cross-section factor M, where the inner ring cross-section factor is 0.15

[0023] < M < 0.23.

[0024] Figure 2 shows a cross-sectional view of a forged tower blank, illustrating the arrangement of the bearing rings for the process for manufacturing a tapered roller bearing. The forged tower blank has a total width BG that is smaller than the combined width of the outer bearing ring 5BA and the inner bearing ring 3BI in the final dimension. The blank is separated into two annular sections YA and YB in the area of ​​the radial diameter distance X.

[0025] List of reference symbols

[0026] 1 tapered roller bearing

[0027] 2 axis of rotation

[0028] 3 Inner bearing ring

[0029] 4 Inner tread

[0030] 5 Outer bearing ring

[0031] 6 Outer tread

[0032] 7 tapered rollers

[0033] 8 cage

[0034] 9 Nominal pressure angle vector

[0035] 3BI Width of the inner bearing ring

[0036] 5BA Width of the outer bearing ring aO Nominal contact angle

[0037] BG Total width of the tower blank

[0038] D Bearing outer diameter d Bearing inner diameter

[0039] DS small roll diameter

[0040] DW large roll diameter

[0041] SBA support board outer diameter

[0042] H maximum bearing cross-sectional height

[0043] LSD raceway tip diameter

[0044] LW roll length

[0045] M inner ring cross-sectional factor

[0046] Q1 Outer ring cross-section at nominal pressure angle

[0047] Q2 Inner ring cross-section at nominal pressure angle

[0048] S Outer ring cross-sectional factor

[0049] X radial diameter distance

[0050] YA, YB annular sections

Claims

Patent claims 1 . Tapered roller bearing (1 ) with a maximum outer diameter (D) of 100 mm and a maximum bearing cross-sectional height (H) of 22.5 mm, wherein the bearing height (H) is described by half the difference between the bearing outer diameter (D) and the bearing inner diameter (d), comprising: - an inner bearing (3) having an inner raceway (4) formed on an outer peripheral surface thereof; - an outer bearing (5) having an outer race (6) formed on an inner peripheral surface thereof; - a plurality of tapered rollers (7) arranged between the inner raceway (4) of the inner bearing ring (3) and the outer raceway (6) of the outer bearing ring (5) and having a small roller diameter (DS) and a large roller diameter (DW) and a roller length (LW); and - a cage (8) configured to hold the tapered rollers (7) in a plurality of positions in a circumferential direction, wherein the inner bearing (3) has a support rim at least on the larger diameter side, the outer diameter of which has a Support rim outer diameter (SBA), wherein the outer raceway (6) of the outer bearing ring (5) describes a raceway tip diameter (LSD) on its smaller diameter side, wherein a radial diameter distance (X) is formed between the support rim outer diameter (SBA) and the raceway tip diameter (LSD), wherein the radial diameter distance is 4.5 mm > X > 1.5 mm, and wherein the outer bearing (5) has an outer ring cross-section at the intersection point between the nominal pressure angle vector (9) and the outer bearing (Q1), which is defined by the bearing height H multiplied by an outer ring cross-section factor (S), wherein the outer ring cross-section factor is 0.2 < S < 0.3, and wherein the inner bearing ring (3) has an inner ring cross-section at the intersection point between the nominal pressure angle vector (9) and the inner bearing ring (Q2), which is defined by the bearing height (H) multiplied by an inner ring cross-section factor M, wherein the inner ring cross-section factor is 0.15 < M < 0.

23.

2. Tapered roller bearing (1) according to claim 1, wherein the ratio of the large roller diameter (DW) to roller length (LW) of the tapered rollers (7) is 1.1 < LW / DW < 1.

7.

3. Tapered roller bearing (1) according to one of the preceding claims, wherein the cage (8) is made of a plastic.

4. Tapered roller bearing (1) according to one of the preceding claims, wherein the cage (8) comprises biomass-based polyamide with a glass fiber content.

5. Tapered roller bearing (1) according to one of the preceding claims, wherein the inner bearing ring (3) and the outer bearing ring (5) comprise chromium steel with 10% up to 95% secondary content.

6. A transmission for an electrically operated vehicle, the transmission shaft bearing of which comprises a tapered roller bearing according to one of the preceding claims.

7. A method for producing a tapered roller bearing according to one of the preceding claims, comprising a) providing a forged tower blank whose total width (BG) is smaller than the combined width of the outer bearing ring (5BA) and the inner bearing ring (3BI) in the final dimension. b) separating the blank into two annular sections (YA, YB) in the region of the radial diameter distance (X). c) machining the annular sections to form an inner bearing ring (3) and an outer bearing ring (5). d) hardening e) machining the bearing rings to the final dimension d) mounting the bearing.

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