Drive gear assembly with ventilation cavity

Abstract

A transmission gear assembly includes a housing having an axial centerline, the housing having a front wall and a circumferential wall with a vent opening. The front wall includes an annular groove that is in fluid communication with the vent opening and is covered by a generally circular plate having a periphery at a first distance (r) from the axial centerline and having a predetermined length L. On each lateral side of the axial centerline, in at least a lower portion, air / oil inlets and outlets (25, 26) are defined by peripheral grooves at a distance (r3, r4) from the axial centerline that is less than the first distance r, each groove having a circumferential length (l3, l4) and being in fluid communication with the annular groove. On each lateral side of the axial centerline, in an upper portion, air / oil inlets (23, 24) are defined by peripheral grooves at a distance (r1, r2) from the axial centerline that is less than the first distance r and having a circumferential length (l1, l2) that is less than the circumferential length (l3, l4) of the inlets / outlets (25, 26).

Description

Technical Field

[0001] The present invention relates to a transmission gear assembly, which includes a housing having an axial centerline. The housing has a circumferential wall extending in the axial direction, an end wall on the motor side, and a front wall on the output side. The end wall and the front wall extend in the radial direction, and the walls define an oil reservoir having an upper portion and a lower portion.

[0002] - An opening for receiving an input shaft is provided in the end wall.

[0003] - A gear system rotatably mounted in the housing and connectable to the input shaft.

[0004] - An opening for receiving an output shaft connectable to the gear system is provided in the front wall, and

[0005] - A vent is provided in the circumferential wall.

[0006] The present invention also relates to an electric motor connected to such a transmission gear assembly and an electric vehicle including the electric motor and the connected transmission gear assembly. Background Art

[0007] In a transmission gear assembly, the pressure increases due to temperature changes. A vent is provided in the transmission gear housing for balancing with the ambient pressure. Air can enter and exit the transmission housing through the vent, while preventing contaminants from entering the transmission housing and preventing oil from escaping from the transmission housing.

[0008] In order for the breather to work properly, a calm area in the oil reservoir is required, especially in the case of concentric planetary gears that are subject to a relatively high degree of oil splashing. In this case, the housing does not have a natural calm area for placing the breather. When the following factors are considered in the design, the correct placement of the breather becomes more complicated: the temperature range and the resulting change in oil viscosity; the rotational speed in forward and reverse drives, and the G-forces caused by acceleration; uphill and downhill driving, braking, and turning.

[0009] It is known to provide an annular channel in the oil reservoir of the transmission. The annular channel is in fluid communication with the breather through a complex maze channel system, and the maze channel prevents oil from reaching the breather and escaping to the environment. These known structures have a relatively large volume, which makes it difficult to package such a transmission gear assembly in a vehicle. Summary of the Invention

[0010] An object of the present invention is to provide a transmission gear assembly in which a ventilation device is effectively isolated from the oil in an oil reservoir while allowing a compact structure with a relatively large volume available for accommodating gears. An object of the present invention is to provide a transmission gear assembly that is relatively simple in design, reduces the number of parts, and is adaptable to various transmission gears with only minor adjustments. Yet another object of the present invention is to provide a compact transmission gear assembly having a relatively large quiet area.

[0011] Thus, the transmission gear assembly according to the present invention has a front wall that includes an annular groove that is in fluid communication with a ventilation opening located on the upper side of the front wall. The annular groove is covered by a generally circular plate that has a periphery at a first distance from the axial centerline and having a predetermined length L. The periphery extends close to the circumferential wall. On each lateral side of the axial centerline, the periphery has air / oil inlets and outlets in at least a lower portion. The air / oil inlets and outlets are defined by grooves in the periphery at a distance from the axial centerline that is less than the first distance. Each groove has a circumferential length and is in fluid communication with the annular groove. And on each lateral side of the centerline in an upper portion, there is an air / oil inlet that is defined by a groove in the periphery at a distance from the axial centerline that is less than the first distance and having a circumferential length that is shorter than the circumferential length of the inlet / outlet.

[0012] The quiet area of the oil in the oil reservoir according to the present invention is defined by the annular groove and a cover plate covering the groove. The peripheral air and oil holes in the plate provide a controlled flow and separation of oil and air. This results in a compact and stable ventilation device design that is well-suited for various designed transmission gears, particularly coaxial or in-line planetary transmission gears.

[0013] An embodiment of the transmission gear according to the present invention includes an air distribution member that has an air inlet opening disposed along the circumferential wall in a lower portion.

[0014] The air inlet opening allows a controlled air flow to enter the front portion of the housing defined by the circumferential wall and the front wall, and from there along the periphery of the plate into the annular groove, and from there to the ventilation opening.

[0015] In a particularly advantageous embodiment of the transmission gear assembly according to the present invention,

[0016] - a first inlet slot is arranged at an angular position where the midpoint is between 35 and 55 degrees and has a length l1 that is between 1% and 5% of the length L of the periphery,

[0017] - The second inlet slot is arranged such that its midpoint is at an angular position between 130 and 150 degrees and has a length l2 between 1% and 5% of the length L of the periphery.

[0018] - The first inlet / outlet slot is arranged such that its midpoint is at an angular position between 210 and 230 degrees and has a length l3 between 10% and 25% of the length L of the periphery, and

[0019] - The second inlet / outlet slot is arranged such that its midpoint is at an angular position between 305 and 325 degrees and has a length l4 between 5% and 20% of the length L of the periphery. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 An isometric view of the housing of the transmission gear assembly according to the present invention is shown.

[0021] Figure 2 A plan view of the housing according to the present invention as viewed from the motor side, with the plate removed,

[0022] Figure 3 Shows Figure 2 A plan view of the housing with the plate installed, and

[0023] Figure 4 Shows in an enlarged scale Figure 3 The view. DETAILED DESCRIPTION

[0024] Figure 1 An isometric view of the housing 2 of the gear assembly 1 is shown. The housing 2 has an axial centerline 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 the drive shaft of the motor (not shown) can pass. The drive shaft extends in the axial direction A. The motor is attached to the housing 2 at the motor side 6. The housing 2 includes a ventilation device 8 which is closed by a cover 9. Through the ventilation device 8, air can flow between the interior of the housing 2 and the environment to achieve pressure balance, while its structure prevents oil from flowing out of the gear assembly and prevents dust and water from entering.

[0025] Figure 2 A plan view of the gear assembly 1 as viewed from the motor side 6 is shown, and the gears 12 of the planetary gear system are shown in dashed lines. The housing 2 includes an inner wall 13 which can sealingly engage with the rear wall at the motor side 6 by its end face to form an oil reservoir 14 for the gears 12. An annular groove 15 is provided at the front wall 3. The annular groove 15 forms an air passage in fluid communication with the ventilation port 16. The ventilation port 16 is provided in the upper part 17 of the oil reservoir 14 above the transverse centerline 18.

[0026] Figure 3Shows the plate 20 in the oil reservoir 14, which covers the annular groove 15. The plate 20 is generally circular and has a peripheral edge 21 extending closely adjacent 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 the lower part 19 of the oil reservoir 14 located below the transverse center line 18. The air / oil inlets and outlets 25 extend in the upper part 17 and the lower part 19.

[0027] The plate 20 is connected to the air distribution member 30, which is parallel to the circumferential wall 4 and has three air inlets 31, 32, 33. The plate 20 is fixed to the annular front wall surface 36 via the connecting flange 35.

[0028] Figure 4 The plate 20 is shown in an enlarged scale, where the circular peripheral edge 21 extends at a distance r from the axial center line 7. The distance r of the peripheral edge 21 is, for example, 10 - 20 cm. The air inlet 23 is provided at an angle α1 of approximately 10° and has a length l1 of, for example, 3 mm. The air inlet 24 is provided at an angle α2 of 145° and may have a length l2 of 3 mm. The air / oil inlet and outlet 25 is provided at an angle α3 of 190° and may have a length l3 of 6.5 cm. The air / oil inlet and outlet 26 is provided at an angle α4 of 340° and may have a length l4 of 3 cm. The distances r1 - r4 of the bottoms of the grooves forming the inlets and outlets 23 - 26 in the peripheral edge 21 may be smaller than the distance r of the peripheral edge 21 by, for example, 0.5 cm.

Claims

1. A transmission gear assembly (1) comprising a housing (2) having an axial centerline (7), said housing having a circumferential wall (4) extending in the axial direction, an end wall on the motor side (6), and a front wall (3) on the output side, said end wall and said front wall extending in the radial direction, said circumferential wall, said end wall, and said front wall defining an oil reservoir (14), said oil reservoir (14) having an upper portion (17) and a lower portion (19). - An opening for receiving an input shaft is provided in the end wall. - A gear system (12) is rotatably mounted in the housing (2) and can be connected to the input shaft. - An opening (5) for receiving an output shaft that can be connected to the gear system (12) is provided in the front wall (3). - Vent openings (8, 16) are provided in the circumferential wall (4). The front wall (3) includes an annular groove (15), said annular groove (15) being in fluid communication with the vent openings (8, 16) on the upper side of the front wall (3), said annular groove (15) being covered by a substantially circular plate (20), said plate (20) having a periphery (21) at a first distance (r) from the axial centerline (7) and having a predetermined length L, said periphery (21) extending close to the circumferential wall (4), having air / oil inlets and outlets (25, 26) in at least the lower portion (19) on each transverse side of the axial centerline (7), said air / oil inlets and outlets (25, 26) being defined by grooves in the periphery (21) at a distance (r3, r4) from the axial centerline (7) less than the first distance r, each groove having a circumferential length (l3, l4) and being in fluid communication with the annular groove (15), and having air / oil inlets (23, 24) in the upper portion (17) on each transverse side of the axial centerline (7), said air / oil inlets (23, 24) being defined by grooves in the periphery (21) at a distance (r1, r2) from the axial centerline (7) less than the first distance (r) and having a circumferential length (l1, l2) less than the circumferential length (l3, l4) of the air / oil inlets and outlets (25, 26).

2. The transmission gear assembly (1) according to claim 1, wherein an air distribution member (30) having air inlet openings (31, 32, 33) is located in the lower portion (19) of the oil reservoir (14) along the circumferential wall (4).

3. The transmission gear assembly (1) according to claim 2, wherein the air distribution member (30) is attached to the periphery (21) of the plate (20) along the lower side.

4. The transmission gear assembly (1) according to claim 1, 2, or 3, wherein - The first air / oil inlet (23) of the air / oil inlets (23, 24) is arranged at an angular position where the midpoint is between 35 degrees and 55 degrees, and has a length l1 between 1% and 5% of the length L of the periphery (21). - The second air / oil inlet (24) among the air / oil inlets (23, 24) is arranged at an angular position with its midpoint between 130 degrees and 150 degrees, and has a length l2 between 1% and 5% of the length L of the periphery (21). - The first air / oil inlet and outlet among the air / oil inlets and outlets (25, 26) are arranged at an angular position with its midpoint between 210 degrees and 230 degrees, and has a length l3 between 10% and 25% of the length L of the periphery (21), and - The second air / oil inlet and outlet among the air / oil inlets and outlets (25, 26) are arranged at an angular position with its midpoint between 305 degrees and 325 degrees, and has a length l4 between 5% and 20% of the length L of the periphery (21).

5. The transmission gear assembly (1) according to claim 1, 2 or 3, comprising a planetary gear system (12).

6. An assembly comprising an electric motor having an output shaft and a transmission gear assembly (1) according to any one of the preceding claims connected to the output shaft, the output shaft of the electric motor being located on the axial center line (7).

7. An electric vehicle comprising the assembly according to claim 6.

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