Transmission Gear Assembly with a Breather Cavity

Abstract

A transmission gear assembly including a housing with an axial center line, having a front wall and a circumferential wall with a breather opening. The front wall includes an annular groove in fluid communication with the breather opening and covered by a substantially circular plate having a perimeter at a first distance (r) from the axial center line and with a predetermined length (L). On each transverse side in at least the lower part, an air/oil inlet and outlet is defined by a recess of the perimeter at a distance (r.sub.3,r.sub.4) from the axial center line smaller than the first distance (r), each recess being in fluid communication with the annular groove. On each transverse side in the upper part, an air/oil inlet is formed by a recess of the perimeter at a distance (r.sub.1,r.sub.2) from the axial center line smaller than the first distance (r) and having a circumferential length (l.sub.1,l.sub.2) shorter than a circumferential length (l.sub.3,l.sub.4) of the inlet/outlets.

Claims

1. A transmission gear assembly, comprising: a housing with an axial center line, the housing having a circumferential wall extending in an axial direction, and an end wall at a motor side and a front wall at an output side, the end wall and the front wall extending in a radial direction, the walls defining an oil reservoir having an upper part and a lower part, an opening being provided in the end wall for receiving an input shaft, a gear system being rotatably mounted in the housing and connectable to the input shaft, an opening being provided in the front wall for receiving an output shaft that is connectable to the gear system, a breather opening being provided in the circumferential wall, and the front wall comprising an annular groove that is in fluid communication with the breather opening at an upper side of the front wall, the annular groove being covered by a substantially circular plate having a perimeter at a first distance (r) from the axial center line and with a predetermined length (L), the perimeter extending near the circumferential wall, with on each transverse side of the axial center line in at least the lower part an air/oil inlet and outlet defined by a recess of the perimeter at a distance (r.sub.3,r.sub.4) from the axial center line that is smaller than the first distance r, each recess having a circumferential length (l.sub.3,l.sub.4) and being in fluid communication with the annular groove, and with on each transverse side of the axial center line in the upper part an air/oil inlet is defined by a recess of the perimeter at a distance (r.sub.1,r.sub.2) from the axial center line that is smaller than the first distance (r) and having a circumferential length (l.sub.1,l.sub.2) that is shorter than the circumferential length (l.sub.3,l.sub.4) of the inlet/outlets.

2. The transmission gear assembly according to claim 1, an air distribution member having air inlet openings, being situated along the circumferential wall in the lower part of the oil reservoir.

3. The transmission gear assembly according to claim 2, the air distribution member being attached to the perimeter of the plate, along a lower side.

4. The transmission gear assembly according to claim 1, wherein: a first inlet is situated with a midpoint at an angular position of between 35 and 55 degrees and has a length l.sub.1 of between 1% and 5% of the length (L) of the perimeter, a second inlet is situated with a midpoint at an angular position of between 130 and 150 degrees and has a length (l.sub.2) of between 1% and 5% of the length (L) of the perimeter, a first inlet/outlet is situated with a midpoint at an angular position of between 210 and 230 degrees and has a length (l.sub.3) between 10% and 25% of the length (L) of the perimeter, and a second inlet/outlet is situated with a midpoint at an angular position of between 305 and 325 degrees, and has a length (l.sub.4) between 5% and 20% of the length (L) of the perimeter.

5. The transmission gear assembly according to claim 1, further comprising a planetary gear system.

6. The transmission gear assembly according to claim 1, further comprising an electric motor assembly with an output shaft connected to the transmission gear assembly, the output shaft of the electric motor assembly being situated on the axial center line.

7. An electric vehicle, comprising: an electric motor assembly with an output shaft, and a transmission gear assembly connected to the output shaft of the electric motor assembly, the transmission gear assembly comprising: a housing with an axial center line, the housing having a circumferential wall extending in an axial direction, and an end wall at a motor side and a front wall at an output side, the end wall and the front wall extending in a radial direction, the walls defining an oil reservoir having an upper part and a lower part, an opening being provided in the end wall for receiving an input shaft, a gear system being rotatably mounted in the housing and connectable to the input shaft, an opening being provided in the front wall for receiving an output shaft that is connectable to the gear system, a breather opening being provided in the circumferential wall, and the front wall comprising an annular groove that is in fluid communication with the breather opening at an upper side of the front wall, the annular groove being covered by a substantially circular plate having a perimeter at a first distance (r) from the axial center line and with a predetermined length (L), the perimeter extending near the circumferential wall, with on each transverse side of the axial center line in at least the lower part an air/oil inlet and outlet defined by a recess of the perimeter at a distance (r.sub.3,r.sub.4) from the axial center line that is smaller than the first distance r, each recess having a circumferential length (l.sub.3,l.sub.4) and being in fluid communication with the annular groove, and with on each transverse side of the axial center line in the upper part an air/oil inlet is defined by a recess of the perimeter at a distance (r.sub.1,r.sub.2) from the axial center line that is smaller than the first distance (r) and having a circumferential length (l.sub.1,l.sub.2) that is shorter than the circumferential length (l.sub.3,l.sub.4) of the inlet/outlets.

8. The electric vehicle according to claim 7, an air distribution member having air inlet openings, being situated along the circumferential wall in the lower part of the oil reservoir.

9. The electric vehicle according to claim 8, the air distribution member being attached to the perimeter of the plate, along a lower side.

10. The electric vehicle according to claim 7, wherein: a first inlet is situated with a midpoint at an angular position of between 35 and 55 degrees and has a length l.sub.1 of between 1% and 5% of the length (L) of the perimeter, a second inlet is situated with a midpoint at an angular position of between 130 and 150 degrees and has a length (l.sub.2) of between 1% and 5% of the length (L) of the perimeter, a first inlet/outlet is situated with a midpoint at an angular position of between 210 and 230 degrees and has a length (l.sub.3) between 10% and 25% of the length (L) of the perimeter, and a second inlet/outlet is situated with a midpoint at an angular position of between 305 and 325 degrees, and has a length (l.sub.4) between 5% and 20% of the length (L) of the perimeter.

11. The electric vehicle according to claim 7, further comprising a planetary gear system.

12. The electric vehicle according to claim 7, the output shaft of the electric motor assembly being situated on the axial center line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 shows an isometric view of the housing of a transmission gear assembly according to the present disclosure.

[0014] FIG. 2 shows a plan view of the housing according to the present disclosure form a motor side, with the plate removed.

[0015] FIG. 3 shows the plan view of the housing of FIG. 2, with the plate installed.

[0016] FIG. 4 shows the view of FIG. 3 on an enlarged scale.

DESCRIPTION OF EMBODIMENTS

[0017] FIG. 1 shows an isometric view of a housing 2 of a gear assembly 1 with an axial center line 7. The housing has a front wall 3 and a circumferential wall 4. The front wall 3 extends in the radial direction R and is provided with an opening 5 through which a drive axle of a motor (not shown) can pass, the axle extending in the axial direction A. The motor is attached to the housing 2 at a motor side 6. The housing 2 includes a breather 8 that is closed by a cap 9. Through the breather 8, air can travel between the interior of the housing 2 and the ambient for pressure equalization, while its construction prevents oil from exiting from the gear assembly and dirt and water from entering.

[0018] FIG. 2 shows a plan view of the gear assembly 1 from the motor side 6, and shows with dotted lines the gears 12 of a planetary gear system. The housing 2 includes an inner wall 13 that can with its end face sealingly engage with a rear wall at the motor side 6 to form an oil reservoir 14 for the gears 12. At the front wall 3, an annular groove 15 is provided that forms an air channel that is in fluid communication with a breather opening 16. The breather opening 16 is provided in an upper part 17 of the oil reservoir 14, situated above the transverse center line 18.

[0019] FIG. 3 shows a plate 20 in the oil reservoir 14, covering the annular groove 15. The plate 20 is of generally circular shape and has a perimeter 21 that extends in close proximity to the circumferential wall 4. The plate has two air/oil inlets 23,24 in the upper part 17 of the oil reservoir 14, and two air/oil inlets and outlets 25, 26 in a lower part 19 of the oil reservoir 14, situated below the transverse center line 18. The air/oil inlet and outlet 25 extends in both the upper part 17 and the lower part 19.

[0020] The plate 20 is connected to an air distribution member 30, that is parallel to the circumferential wall 4 and that has three air inlet openings 31,32, 33. The plate 20 is fixed to an annular front wall surface 36 via the connecting flange 35.

[0021] FIG. 4 shows the plate 20 on an enlarged scale with the circular perimeter 21 extending at a distance r from the axial center line 7. The distance r of the perimeter 21 is for instance 10-20 cm. The air inlet 23 is provided at an angle α.sub.1 of about 10° and has a length l.sub.1 of for instance 3 mm. The air inlet 24 is provided at an angle α.sub.2 of 145° and may have a length l.sub.2 3 mm. The air/oil inlet and outlet 25 is provided at an angle α.sub.3 of 190° and may have a length l.sub.3 of 6.5 cm. The air/oil inlet and outlet 26 is provided at an angle α.sub.4 of 340° and may have a length l.sub.4 of 3 cm. The distances r.sub.1-r.sub.4 of the bottom of the recesses in the perimeter 21 that form the inlets and outlets 23-26 may be for instance 0.5 cm smaller that the distance r of the perimeter 21.