Pinion bearing arrangement

Abstract

A pinion bearing arrangement of a gearbox for a vehicle or aircraft, providing at least one roller bearing. At least one of the roller bearings is a ball bearing, having an inner ring and an outer ring, wherein both rings have raceways for balls being located between the rings. To ensure a sufficient lifetime of the roller bearings the invention includes that at least one of the rings is made from a ball bearing steel produced by a powder metallurgical process using a powder metallurgy component including 0.5 to 2.0 weight-% C, a maximum of 0.035 weight-% S, 3.0 to 5.0 weight-% Cr, 1.0 to 4.0 weight-% V, 1.0 to 12.0 weight-% W and 2.0 to 12.0 weight-% Mo, wherein at least one raceway has a radius (r.sub.I/O) and the balls have a diameter (D.sub.B) which fulfill the equation: r.sub.I/O/D.sub.B>0.53.

Claims

1. A gearbox for a vehicle or aircraft, comprising: a pinion comprising a shaft and a bevel gear, a pinion bearing arrangement comprising a first roller bearing and a second roller bearing located on the shaft, the first roller bearing comprises a first outer raceway, a first inner raceway, and a first set of rolling elements therebetween and the second roller bearing comprises a second outer raceway, a second inner raceway, and a second set of rolling elements therebetween, wherein at least one of the first roller bearing and the second roller bearing is a ball bearing and wherein at least one of the first inner raceway, the first outer raceway, the second inner raceway, and the second outer raceway is made from a ball bearing steel produced by a powder metallurgical process using a powder metallurgy component including 0.5 (zero point five) to 2.0 (two point zero) weight-% C, a maximum of 0.035 (zero point zero three five) weight-% S, 3.0 (three point zero) to 5.0 (five point zero) weight-% Cr, 1.0 (one point zero) to 4.0 (four point zero) weight-% V, 1.0 (one point zero) to 12.0 (twelve point zero) weight-% W and 2.0 (two point zero) to 12.0 (twelve point zero) weight-% Mo, wherein both the first outer raceway and the first inner raceway have a first radius (r.sub.I/O) and the first set of rolling elements have a first diameter (D.sub.B) which fulfill the equation:
0.545 (zero point five four five)>r.sub.I/O/D.sub.B>0.54 (zero point five four) wherein both the second outer raceway and the second inner raceway have a second radius (r.sub.2I/2O) and the second set of rolling elements have a second diameter (D.sub.2B) which fulfill the equation:
0.535 (zero point five three five)>r.sub.2I/2O/D.sub.2B>0.53 (zero point five three), and wherein the first roller bearing is located closer to the bevel gear than the second roller bearing.

2. The gearbox according to claim 1, wherein the powder metallurgy component includes 1.3 (one point three) to 1.4 (one point four) weight-% C, a maximum of 0.035 (zero point zero three five) weight-% S, 3.50 (three point five zero) to 4.25 (four point two five) weight-% Cr, 1.75 (one point seven five) to 2.20 (two point two zero) weight-% V, 5.75 (five point seven five) to 6.50 (six point five zero) weight-% W and 10.0 (ten point zero) to 11.0 (eleven point zero) weight-% Mo.

3. The gearbox according to claim 1, wherein the powder metallurgy component includes 5.0 (five point zero) to 12.0 (twelve point zero) weight-% Co.

4. The gearbox according to claim 1, wherein all of the first inner raceway, the first outer raceway, the second inner raceway, and the second outer raceway are made from the ball bearing steel produced by the powder metallurgical process.

5. The gearbox according to claim 1, wherein a surface of each of the first inner raceway, the first outer raceway, the second inner raceway, and the second outer raceway has a hardness between 65 (sixty five) HRC and 70 (seventy) HRC.

6. The gearbox according to claim 1, wherein at least one of the first and second roller bearings is a Deep Groove Ball bearing (DGBB).

7. The gearbox according to claim 6, wherein the first and second roller bearings are arranged adjacent to another to support the shaft of the pinion.

8. The gearbox according to claim 7, wherein the first roller bearing is a first ball bearing arranged at an outboard side and the second roller bearing is a second ball bearing arranged at an inboard side relatively to the bevel gear of the pinion.

9. The gearbox according to claim 7, wherein the first inner raceway and the second inner raceway are formed on a first inner ring and a second inner ring, respectively, and wherein the first inner ring and the second inner ring are each a one-piece element.

10. The gearbox according to claim 7, wherein the first outer raceway and the second outer raceway are formed on a first outer ring and a second outer ring, respectively, and wherein the first outer ring and the second outer ring are each a one-piece element.

11. The gearbox according to claim 1, wherein at least one of the first and second roller bearings is an Angular Contact Ball Bearing (ACBB).

12. The gearbox according to claim 11, wherein both of the first and second roller bearings are the Angular Contact Ball Bearings, and contact angles of the first and second roller bearings are different.

13. The gearbox according to claim 1, wherein at least one of the first and second roller bearings is a Four Point Contact Bearing (FPCB).

14. The gearbox according to claim 1, wherein at least one of the first and second roller bearings comprises a plurality of balls made of a ceramic material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings show an embodiment of the bearing arrangement according to the invention.

(2) FIG. 1 shows a cross sectional view of a pinion bearing arrangement according to an embodiment of the invention,

(3) FIG. 2 shows an enlarged view of a region of a ball bearing which is a part of the pinion bearing arrangement,

(4) FIG. 3 shows a cross sectional view of one of the bearings of the pinion bearing arrangement and

(5) FIG. 4 shows the view C according to FIG. 3 of the bearing.

DETAILED DESCRIPTION OF THE INVENTION

(6) In FIG. 1 a pinion bearing arrangement 1 is shown by which a pinion 10 with a shaft 9 and a bevel gear 11 is supported in the housing of a gear box. The shaft 9 of the pinion 10 is supported in two roller bearings 2 and 3 which are both designed as angular contact ball bearings ACBB. The ball bearing 2 which is arranged adjacent to the bevel gear 11 is the outboard bearing; the ball bearing 3 which is arranged remote from the bevel gear 11 is the inboard bearing.

(7) Both ball bearings 2, 3 have respective inner rings 4 and outer rings 5. Between the rings 4, 5 balls 8 made from ceramics are arranged. The inner ring 4 and the outer ring 5 have raceways 6 and 7 respectively for the balls 8 (see FIG. 2).

(8) In FIG. 2 the geometrical relations between the raceways of the bearing rings and the balls are depicted. The balls 8 have a diameter D.sub.B. The radius of the raceway of the inner ring 4 is denoted with r.sub.I. The radius of the raceway of the outer ring 5 is denoted with r.sub.O.

(9) The ratio between the radius of the raceway of the inner or outer ring and the diameter of the balls is the osculation between ring and ball and is according to the invention:
r.sub.I/O/D.sub.B>0.53.

(10) In a specific embodiment of the invention the osculation between the raceway of the inner ring 4 and the balls 8 and the osculation between the raceway of the outer ring 5 and the balls 8 are substantial equal, but there are differences between the two bearings 2 and 3. The outboard bearing 2 has an osculation of r.sub.I/O/D.sub.B>0.54, while the inboard bearing 3 has a smaller osculation of r.sub.I/O/D.sub.B>0.53.

(11) The mentioned ratio of osculation of the outboard bearing 2 is preferably between 0.54 and 0.545; the mentioned ratio of osculation of the inboard bearing 3 is preferably between 0.53 and 0.535.

(12) All mentioned ratios for the osculation remain preferably below 0.55.

(13) In FIG. 3 and FIG. 4 an alternative solution for the bearings is shown. Here, the bearing 2 is designed as a Four Point Contact Bearing (FPCB). The bearing 2 has two inner rings 4 and 4 being arranged adjacent to another. The outer ring 5 has flange elements 12 as can be seen from the synopsis of FIG. 3 and FIG. 4. This facilitates the fixation of the bearing 2 at the housing of the gearbox.

REFERENCE NUMERALS

(14) 1 Pinion bearing arrangement 2 Roller bearing (Ball bearing) 3 Roller bearing (Ball bearing) 4 Inner ring 4 First inner ring 4 Second inner ring 5 Outer ring 6 Raceway 7 Raceway 8 Ball 9 Shaft 10 Pinion 11 Bevel gear 12 Flange element r.sub.I Radius of the raceway of the inner ring r.sub.O Radius of the raceway of the outer ring D.sub.B Diameter of the ball