Electric drive unit with perforated guide plate for hydraulic fluid degassing

Abstract

The invention relates to an electric drive unit (1) for a motor vehicle, comprising a housing (2) with an intake area (3) and a reservoir area (4) which, in operation, has a higher maximum hydraulic fluid level than the intake area (3), wherein the reservoir area (4) is arranged, in an intended installation position in the gravitational field, largely or completely above the intake area (3), wherein a pump (5) is furthermore provided which, in operation, is used to convey hydraulic fluid from the intake area (3), above the maximum hydraulic fluid level, into the reservoir area (4), and a perforated guide plate (6) is installed below a hydraulic fluid outlet (7) of the pump (5) and above the maximum hydraulic fluid level, inclined to a horizontal plane (8) such that a hydraulic fluid flowing out of the hydraulic fluid outlet (7) passes through this perforated guide plate (6).

Description

[0001] The invention relates to an electric drive unit, in particular an E-axle unit having an electric motor and a transmission arranged downstream thereof, for a motor vehicle, such as a car, truck, bus or other commercial vehicle, with a housing having an intake region and a reservoir region which, during operation, is equipped with a higher / higher maximum hydraulic fluid level than the intake region, wherein the reservoir region, in an intended installation position, is arranged largely or completely above the intake region in the gravitational field / in the direction of the acting force of gravity, and wherein a pump is also provided which, during operation, is used to convey hydraulic fluid from the intake region, above the maximum hydraulic fluid level, into the reservoir region.

[0002] Generic drive units are already well known from the prior art. In particular, the applicant is aware of internal prior art, which has already been filed as a German patent application with the German Patent and Trademark Office, but has not yet been published. This relates, on the one hand, to the applicant's application with the file number 10 2022 105 368.7, filed on March 8, 2022. This discloses an electric drive unit with a dry sump lubrication system, wherein two return channels running between a dry sump area and a hydraulic reservoir open into the dry sump area at spaced-apart circumferential regions of an annular wall. Further prior art relates, on the other hand, to the applicant's application with the file number 10 2022 113 288.9, filed on May 25, 2022.

[0003] Further lubrication systems with air separators are known from the publications DE 10 2018 211 360 A1, DE 24 38 551 A1, CH 716 640 A2 and DE 10 2019 114 611 A1.

[0004] Drive units with hydraulic systems are already known which have a lower housing section and a higher housing section and which use a pump to transport the hydraulic fluid from the lower housing section to the higher housing section. However, it has been found that, particularly when the pump is running without any gearbox speed, a relatively high level of foaming of the hydraulic fluid / oil can occur in the higher housing section. This is further exacerbated by the fact that the oil from the lower housing section is already being sucked out along with the corresponding air due to the higher suction capacity than the oil inlet to the gearbox. The oil then does not have the opportunity to degas sufficiently in the higher housing section and is passed back into the cooling circuit by the pump.This ultimately leads to a reduction in the heat capacity of the hydraulic fluid flow and poorer foaming behavior in the gearbox.

[0005] It is therefore the object of the present invention to reliably provide the highest possible heat capacity of the hydraulic fluid flow conveyed during operation.

[0006] This is achieved according to the invention in that a perforated guide plate is inserted below a hydraulic fluid outlet of the pump and above the maximum hydraulic fluid level, inclined to a horizontal plane, such that hydraulic fluid flowing from the hydraulic fluid outlet passes through this perforated guide plate. This perforated guide plate is understood, in particular, to be a perforated sheet, preferably formed by stamping. The pump and the perforated guide plate are housed in a common (second) housing area of ​​the housing. This results in the most effective defoaming / degassing of the hydraulic fluid, with the hydraulic fluid being able to be passed as directly as possible to a pump intake port.

[0007] During operation, the oil flows back toward the bottom / intake area through the holes (through holes) in the perforated baffle. Due to the angled position of the perforated baffle, it acts as a planer against the hydraulic fluid flowing past it, which contains foam bubbles, and effectively separates the air trapped in the bubbles from the hydraulic fluid / oil. This effectively degasses the hydraulic fluid. The perforated baffle thus divides a (second) housing section of the housing, in which the pump is located, into two subsections.

[0008] Further advantageous embodiments are claimed in the subclaims and explained in more detail below.

[0009] Accordingly, it is also advantageous if the housing has a first housing section that at least partially accommodates a transmission, and the pump is arranged outside this first housing section, in a second housing section (of the housing). This ensures that the individual components of the transmission are supplied with hydraulic fluid as effectively as possible.

[0010] If the first housing area is surrounded by a ring-shaped housing wall and the pump is arranged outside this housing wall, the housing is designed to be as compact as possible.

[0011] It is also advantageous if the perforated guide plate is inserted in such a way that it is inclined downwards from its first end region, facing the gearbox / an outer side of the housing wall, to a second end region, facing away from the gearbox / the outer side of the housing wall. This allows the perforated guide plate to be integrated as compactly as possible.

[0012] It is therefore also advantageous if a pump intake opening is located below the perforated guide plate.

[0013] The invention will now be explained in more detail below with reference to a figure.

[0014] It shows the only Fig. 1 a sectional view of a drive unit according to the invention according to a preferred embodiment, wherein in particular a housing and two housing areas formed in this housing can be seen.

[0015] This figure is merely schematic in nature and therefore serves solely to understand the invention.

[0016] Fig. Figure 1 shows the electric drive unit 1 according to the invention in the region of a transmission 9 arranged in a housing 2 of the drive unit 1 and a hydraulic arrangement 16 (also referred to as hydraulic supply or hydraulic system) likewise integrated in the housing 2. It should be noted in principle that the drive unit 1 has an electric drive motor (not shown here for the sake of clarity), which generates a rotary motion and transmits it to the transmission 9. The transmission 9 is therefore arranged downstream of the electric drive motor. The drive unit 1, designed as an electric axle / electric axle unit, forms a torque output with its transmission 9, by means of which a corresponding wheel of the motor vehicle can be driven during operation.It should also be noted that the drive unit 1 can be realized as a double drive unit and can therefore also have two gears and / or even two electric machines, each of which is assigned to its own output shaft.

[0017] In Fig. 1, the design of a housing 2 and the hydraulic arrangement 16 arranged in this housing 2 can be seen in more detail. The housing 2 has a first housing area 10, which is surrounded by a substantially annular housing wall 12. The transmission 9 is at least partially arranged within this first housing area 10. Fig. 1, the transmission has a planetary gear stage / planetary gear that is directly accommodated in this first housing area 10. Integrated on an underside of the first housing area 10 is an intake area 3 of the hydraulic arrangement 16, described in more detail below.

[0018] Outside the first housing area 10, a second housing area 11 of the housing 2 is formed, which in turn is closed off from the surroundings of the drive unit 1 by an outer wall 17 and surrounds the housing wall 12 from the outside. The second housing area 11 is arranged laterally to the first housing area 10.

[0019] The directions used above / top and below / bottom are in relation to the Fig. 1. The installation position is to be understood in relation to an effective gravitational field, which is Fig. 1 is marked by arrow 18.

[0020] Accordingly, the hydraulic arrangement 16 comprises the intake region 3 (located at the bottom of the housing 2) and a reservoir region 4 (located at the top of the housing 2, namely in particular in the second housing region 11). The intake region 3 is thus arranged below the reservoir region 4. The intake region 3 is further preferably directly connected to a so-called deep sump region, which is typically arranged at the lowest point in the first housing region 10. Here, the intake region 3 is even designed directly as the deep sump region, which serves as a collection area for the hydraulic fluid flowing out of the transmission during operation.

[0021] During operation, a pump 5 transports the hydraulic fluid located in the housing 2, which is further used to lubricate and cool the corresponding components of the transmission 9 and the electric drive motor, from the intake area 3 into the reservoir area 4 and from there onward to the individual consumers. For this purpose, the pump 5 is preferably designed as a dual-flow pump 5. It can be seen that the pump 5 is housed in the second housing area 11. In this embodiment, the intake area 3 is arranged at least partially below the transmission 9.

[0022] The pump 5 has an intake opening 15 arranged in the second housing region 11. The intake opening 15 is located in the reservoir region 4 formed directly by the second housing region 11, approximately at the level of the intake region 3. The intake opening 15 is thus arranged below a corresponding (maximum) hydraulic fluid level of the second housing region 11 / reservoir region 4 during operation.

[0023] The pump 5 is designed such that a flow of hydraulic fluid (indicated by flow arrows 19) previously directed from the first housing area 10 / intake area 3 into the reservoir area 4 / second housing area 11 ultimately collects on the underside of the second housing area 11. The (maximum) water level reached during operation is, for example, at the level of the horizontal plane 8 shown, but varies depending on the driving situation and the position of the motor vehicle.

[0024] Reservoir area 4 is located above the deep sump area. Specifically, pump 5 is located directly in reservoir area 4 and below the (maximum) water level. The hydraulic fluid pumped into the second housing area 11 by pump 5 during operation exits through a hydraulic fluid outlet 7 of pump 5. Hydraulic fluid outlet 7 is located above the (maximum) water level. From the second housing area 11 / reservoir area 4, the hydraulic fluid is then forwarded / distributed to various components of the transmission 9 and the electric drive motor in order to lubricate and cool their components.

[0025] According to the invention, a perforated guide plate 6 is inserted between the hydraulic fluid outlet 7 and the intake area 3, i.e., below the hydraulic fluid outlet 7 in the reservoir area 4, as viewed in the direction of gravity 18. This perforated guide plate 6 is implemented as a perforated sheet and thus has a matrix of several through holes (not shown here for the sake of clarity). The perforated guide plate 6 is inserted at a specific angle, in particular inclined to the Fig. 1 schematically drawn horizontal plane 8, to which the direction of weight force 18 is perpendicular.

[0026] It can be seen that the perforated guide plate 6 is inserted at an angle such that it extends downward from its first end region 13, which is preferably supported directly on the housing wall 12, to its opposite second end region 14. The second end region 14 is in turn preferably supported on the outer wall 17.

[0027] Thus, during operation, the perforated guide plate 6 serves to degas a hydraulic fluid / separate existing air bubbles from the hydraulic fluid. The air pockets collected at the top / top of the perforated guide plate 6 coalesce and escape upwards. The degassed hydraulic fluid then flows back toward the bottom of the reservoir area 4 and thus to the intake opening 15. List of reference symbols 1 drive unit 2 housings 3 Intake area 4 Reservoir area 5 Pump 6 perforated guide plate 7 Hydraulic fluid outlet 8 Horizontal plane 9 gearboxes 10 first housing area 11 second housing area 12 Housing wall 13 first end area 14 second end area 15 Intake opening 16 Hydraulic arrangement 17 Exterior wall 18 Arrow 19 Flow arrow

Claims

[1] An electric drive unit (1) for a motor vehicle, comprising a housing (2) having an intake region (3) and a reservoir region (4) which, during operation, is provided with a higher maximum hydraulic fluid level than the intake region (3), wherein the reservoir region (4) is arranged, in an intended installation position in the gravitational field, largely or completely above the intake region (3), and wherein a pump (5) is further provided which, during operation, is used to convey hydraulic fluid from the intake region (3), above the maximum hydraulic fluid level, into the reservoir region (4), wherein a perforated guide plate (6) is inserted below a hydraulic fluid outlet (7) of the pump (5) and above the maximum hydraulic fluid level, inclined to a horizontal plane (8) in such a way that a hydraulic fluid flowing out of the hydraulic fluid outlet (7) passes through this perforated guide plate (6), characterized bythat the pump (5) and the perforated guide plate (6) are accommodated in a common housing area (11) of the housing (2). [2] Drive unit (1) according to claim 1, characterized by that the housing (2) has a first housing region (10) which at least partially accommodates a gear (9) and the pump (5) is arranged outside this first housing region (10), in a second housing region (11). [3] Drive unit (1) according to claim 2, characterized by that the first housing area (10) is surrounded by an annular housing wall (12) and the pump (5) is arranged outside this housing wall (12). [4] Drive unit (1) according to claim 2 or 3, characterized by that the perforated guide plate (6) is inserted in such a way that it is inclined downwards from its first end region (13) facing the gear (9) to a second end region (14) facing away from the gear (9). [5] Drive unit (1) according to one of claims 1 to 4, characterized by that a suction opening (15) of the pump (5) is arranged below the perforated guide plate (6).

Images