Electric drive module with labyrinth seal

Abstract

Electric drive module (1) for a motor vehicle, comprising a housing (2), a shaft (5) projecting through an opening (3) in the housing (2) into an interior (4) of the housing (2), and a bearing (6) supporting the shaft (5) relative to the housing (2), wherein a labyrinth seal (8) is inserted between the housing (2) and the shaft (5) to act on a side (7a) of the bearing (6) facing the environment of the housing (2), said labyrinth seal (8) comprising an inner ring (9) and an outer ring (10) arranged radially and without contact with the inner ring (9), wherein the outer ring (10) further comprises a plurality of return holes (11) penetrating it radially, and the return holes (11) are connected to a return channel (12) introduced into the housing (2), wherein the sealing ring (16b) inserted between the outer ring (10) and the housing (2) is axially facing side (17a) of the return holes (11).

Description

[0001] The invention relates to an electric drive module for a motor vehicle, such as a car, truck, bus, or other commercial vehicle. The drive module is preferably designed as a so-called electric axle / electric drive axle.

[0002] DE 42 20 754 A1 shows a gearbox for rail traction vehicle drives with several labyrinth seals.

[0003] DE 199 28 450 A1 shows a labyrinth seal.

[0004] US 2 245 281 A shows a lubricating device which is sealed by a stepped labyrinth seal.

[0005] US 6 273 429 B1 shows a labyrinth seal.

[0006] DE 44 03 776 A1 shows a seal with a labyrinth-like sealing gap.

[0007] DE 203 12 235 U1 shows a gearbox with seals designed as labyrinth seals.

[0008] The aim of the invention is to improve the efficiency of the drive module and at the same time not to increase the available installation space or to increase it only slightly.

[0009] This is achieved according to the invention by the subject matter of claim 1. Claim 1 claims an electric drive module for a motor vehicle, which has a housing, a shaft projecting through an opening in the housing into an interior of the housing and a bearing for the shaft relative to the housing, wherein a labyrinth seal is inserted between the housing and the shaft to act on a side of the bearing facing the surroundings of the housing, wherein this labyrinth seal further has an inner ring and an outer ring arranged radially to the inner ring without contact, wherein the outer ring further has a plurality of return holes penetrating it radially and the return holes are connected to a return channel introduced into the housing.

[0010] By designing such a labyrinth seal, a clever compromise is achieved between sufficient sealing effectiveness and the lowest possible friction loss caused by the labyrinth seal. The friction loss caused by the labyrinth seal is virtually eliminated, although a certain degree of leakage is intentionally present. However, this is kept within limits by the labyrinth and can be conveniently redirected through the existing return holes.

[0011] It has also proven advantageous to insert a sealing ring between the inner ring and the shaft and / or between the outer ring and the housing. The sealing ring is preferably a radially compressed sealing ring, such as an O-ring. This further improves the sealing of the interior of the housing.

[0012] If the sealing ring acting between the outer ring and the housing is positioned on a side of the return holes that is axially facing the environment, the lubricant return is not adversely affected during operation.

[0013] Further advantageous embodiments are claimed in the subclaims and explained in more detail below.

[0014] Accordingly, it is further advantageous for a compact design if the return holes are arranged axially at the same height, i.e. in a common extension plane to which a rotational axis of the shaft is perpendicular, and are evenly distributed over the circumference.

[0015] Furthermore, it is advantageous if at least fifteen, more preferably at least twenty, return holes are provided (in the outer ring). This results in a particularly clever compromise between sufficient lubricant return and manufacturing costs.

[0016] Furthermore, it is advantageous for simple production if the inner ring is formed in one piece and / or the outer ring is formed in several parts (i.e. composed of several circular segments / shell sections).

[0017] If the return holes open into a radially outward-opening annular groove in the outer ring, a lubricant, such as oil, can be drained via the return channel at a circumferential location, which is preferably located on the underside of the labyrinth seal in relation to the installation position and the prevailing gravity. This further reduces manufacturing costs.

[0018] For a sufficient sealing effect, it is also advisable if the inner ring and the outer ring are provided / equipped with several disc areas arranged alternately in the axial direction.

[0019] In order to achieve the highest possible sealing effect, but at the same time to maintain a compact design, it has proven advantageous if the outer ring has at least two, preferably at least three or only three, axially spaced disc areas.

[0020] For an efficient installation of the return holes, it is expedient if they are introduced into the outer ring between a first disc area (of the outer ring) which is axially closest to the surroundings and a second disc area (of the outer ring) which is (axially) adjacent to it.

[0021] Furthermore, it is expedient for the inner ring to have at least two, preferably at least three, more preferably at least four, or only four, axially spaced disc regions. This, in conjunction with the outer ring, achieves the highest possible sealing effect.

[0022] The drive module preferably has at least one electric drive motor within the housing. Further preferably, the drive module also has a transmission downstream of this drive motor, which is preferably also housed in the housing.

[0023] The invention will now be explained in more detail below with reference to figures.

[0024] They show: Fig. 1 a longitudinal sectional view of a partially illustrated drive module according to the invention according to a preferred embodiment, wherein the drive module is shown in the region of a shaft projecting from a housing and mounted in the housing, Fig. 2 a detailed view of the Fig. 2 shown drive module in the area of ​​a bearing supporting the shaft and a labyrinth seal, Fig. 3 a perspective view of a longitudinal section of the shaft having the bearing and the labyrinth seal in a full view, and Fig. 4 a perspective view of the longitudinal section of the shaft of the Fig. 3 with the outer ring removed from the labyrinth seal to reveal an inner ring.

[0025] The figures are merely schematic and serve solely to clarify the invention. The same elements are designated by the same reference numerals.

[0026] Fig. Figure 1 shows part of an electric drive module 1 of a motor vehicle according to the invention, which is preferably implemented as a so-called electric axle. The drive module 1 has a housing 2, which Fig. 1 is shown in sections. Within the housing 2, an electric drive motor and, more preferably, a transmission device coupled to an output of the drive motor are arranged in the usual way, which are not shown further here for the sake of clarity. A shaft 5 entering / exiting from the drive module 1, which is used as an input shaft or output shaft, is arranged in the Fig. 1 to 4. In the illustrated embodiment, the shaft 5 is provided with an integral (here helically toothed) toothing area 18, which meshes with at least one other gear during operation. The shaft 5 is thus preferably a component of the transmission device and forms a transmission input shaft or transmission output shaft.

[0027] The shaft 5 is connected by two Fig. 1, are rotatably mounted relative to the housing 2 by bearings 6 and 19. The bearing that is axially offset further along the shaft 5 into the interior 4 of the housing 2 is referred to as the second bearing 19. The second bearing 19 is designed as a rolling bearing, specifically a ball bearing. The bearing that is arranged closer to the surroundings of the housing 2 is referred to as the first bearing 6. The first bearing 6 is designed as a rolling bearing, specifically a ball bearing. Both bearings 6, 19 serve to rotatably support / radially and preferably also axially support the shaft 5 relative to the housing 2.

[0028] The first bearing 6 is arranged in the region of an opening 3 in the housing 2. The opening 3 is penetrated by the shaft 5. The first bearing 6 is thus inserted radially between a (circular) wall 20 (also referred to as the bore area) describing the opening 3 and a radial outer side of the shaft 5.

[0029] In this regard, it should be noted that the directions used herein, axial, radial, and circumferential, are to be understood with respect to a rotational axis 21 of the shaft 5. Consequently, the axial / axial direction is understood to mean a direction along / parallel to the rotational axis 21, the radial / radial direction is understood to mean a direction perpendicular to the rotational axis 21, and the circumferential direction is understood to mean a direction along a circular line coaxially encircling the rotational axis 21.

[0030] A labyrinth seal 8 according to the invention, which is described in more detail below, is inserted between the housing 2 and the shaft 5 to act on a (first) axial side 7a of the first bearing 6, which faces the surroundings of the housing 2. A second axial side 7b of the first bearing 6, facing away from the first axial side 7a of the first bearing 6, is consequently a side facing the toothed area 18 and thus the interior 4 of the housing 2.

[0031] The labyrinth seal 8 serves to seal the interior 4 of the housing 2 relative to the surroundings of the housing 2 in a radial gap 25 between the housing 2 and the shaft 5.

[0032] In connection with the Fig. Figures 2 to 4 show the detailed design of the labyrinth seal 8. In this regard, it should first be noted that the inner ring 9 is preferably implemented as a one-piece, i.e., a one-piece, integrally formed ring. The inner ring 9 is preferably made of a plastic. The inner ring 9 is placed as a whole, for example, by pressing, onto the shaft 5.

[0033] The inner ring 9 has a sleeve-shaped base section 22, which at least partially rests on the shaft 5 from the outside. Several disc regions 15a, 15b, 15c, 15d protrude radially outward from the base section 22, which has a constant diameter (inner diameter). In this embodiment, a total of four disc regions 15a to 15d are formed, which are radially aligned and run parallel to one another. In this regard, however, it should be noted that the number of disc regions for the inner ring 9 is not fixed at four, which is why it is naturally also possible to use more or fewer than four disc regions in other embodiments.

[0034] It can also be seen that the two outermost disc regions 15a and 15d of the inner ring 9, viewed in the axial direction, have a larger diameter (outer diameter) than the two inner disc regions 15b and 15c of the inner ring 9 located between these two outermost disc regions 15a, 15d. The two inner disc regions 15b and 15c of the inner ring 9 again have the same diameter (outer diameter).

[0035] The outer ring 10 is furthermore constructed in several parts, in this case in two parts. The outer ring 10 consists of two circular segments 23a, 23b / arc segments / shell segments, each extending at 180°, which are more preferably implemented as essentially identical parts. The circular segments 23a, 23b and thus the outer ring 10 are made of a plastic. During assembly, the two circular segments 23a, 23b are placed radially from the outside over the inner ring 9 and ultimately brought into contact with one another in the circumferential direction, so that the alternating arrangement of the disc regions 14a, 14b, 14c, 15a, 15b, 15c, 15d in the axial direction creates a labyrinth-shaped sealing passage / sealing gap within the labyrinth seal 8. The outer ring 10 composed of the two circular segments 23a, 23b is preferably inserted / pressed directly into the opening 3 / the wall 20.

[0036] For the axial fixing of the outer ring 10 on the housing 2 and / or the inner ring 9 on the shaft 5, corresponding retaining rings (not shown in detail for the sake of clarity) can be used.

[0037] The outer ring 10 also has a sleeve-shaped base section 24, which is arranged radially outside the inner ring 9. The base section 24 of the outer ring 10 has a certain radial distance from the inner ring 9 and thus from the individual disc regions 15a to 15d as well as the base section 22 of the inner ring 9. Thus, the outer ring 10 is arranged without contact with the inner ring 9. The base section 24 of the outer ring 10 has a constant diameter (outer diameter).

[0038] It can also be seen that the outer ring 10 in this embodiment has three disc regions 14a to 14c, each of which projects into a gap between two adjacent disc regions 15a to 15d of the inner ring 9. The disc regions 14a to 14c and 15a to 15d are thus arranged alternately with one another in the axial direction. This results in the labyrinth-shaped / zigzag-shaped sealing passage between the inner ring 9 and the outer ring 10, which serves to prevent the hydraulic fluid / lubricant located inside 4 of the housing 2 during operation from escaping into the environment. In this embodiment, the disc regions 14a to 14c of the outer ring 10 are provided with a uniform diameter (inner diameter). In this embodiment, a total of three disc regions 14a to 14c are formed, which are radially aligned and run parallel to one another.In this regard, however, it should be noted that the number of disc areas for the outer ring 10 is not fixed at three, which is why it is of course also possible to use more or fewer than three disc areas in further embodiments.

[0039] Furthermore, it can be seen that the outer ring 10 has a plurality of return holes 11 arranged offset / evenly distributed in the circumferential direction. These return holes 11 penetrate the outer ring 10 in the radial direction. The return holes 11 are designed, for example, as through holes. The return holes 11 are arranged at a uniform distance from one another in the circumferential direction. The number of return holes 11 is selected such that lubricant / oil / hydraulic fluid can flow downward through these return holes 11 in any rotational position of the inner ring 9 or the shaft 5.

[0040] The return holes 11 are arranged in an axial region between two axially directly adjacent / adjacent disc regions 14b and 14c of the outer ring 10. The return holes 11 are arranged / introduced between a first disc region 14a of the outer ring 10, which is axially closest to the surroundings, and a second disc region 14b of the outer ring 10, which is adjacent to the interior 4 of the housing 2.

[0041] All return holes 11 are located at the same height in the axial direction and are thus arranged along a line concentric with the rotational axis 21 / perpendicular to the rotational axis 21. All return holes 11 open radially outward into a fully circumferential annular groove 13, which in turn is open radially outward.

[0042] At a circumferential area of ​​the outer ring 10, preferably at an underside / lowest point of the labyrinth seal 8 (with respect to the installation position and the acting gravitational force), a return channel 12 connects to the annular groove 13. The return channel 12 is incorporated into the housing 2. Thus, a lubricant flowing through the return holes 11 during operation is returned through the return channel 12 into a tank of a hydraulic circuit. It can be seen that the return channel 12 extends from the labyrinth seal 8 essentially axially obliquely back toward the interior 4 of the housing 2.

[0043] It should also be noted that a seal in the form of a sealing ring 16a, 16b is inserted between the inner ring 9 and the shaft 5 on the one hand, and the outer ring 10 and the housing 2 on the other. Each sealing ring 16a, 16b, indicated only schematically here, is shaped, for example, as an O-ring. A first sealing ring 16a is inserted between the inner ring 9 and the shaft 5. A second sealing ring 16b is operatively inserted between the outer ring 10 and the housing 2. The second sealing ring 16b is arranged on a (first) axial side 17a of the return holes 11, which faces axially towards the environment. This prevents the hydraulic fluid from flowing away to the environment.

[0044] In this context, it should be noted that the sealing rings 16a and 16b can each be used directly to fix the inner ring 9 and the outer ring 10 to the shaft 5 and the housing 2, respectively. A type of fleece can also be incorporated. A combination of the labyrinth seal 8 with a grounding system is also possible.

[0045] In other words, the invention provides a labyrinth seal 8 designed such that, should oil enter the labyrinth, there is a return flow through a bore, return holes 11, and a return channel 12 into an oil-free space. The entire assembly is constructed from three plastic parts. The outer ring 10 is two-part, while the inner ring 9 is a single-part. It can be secured using retaining rings or snap-in lugs. The oil drains through transverse bores (return holes 11) and an additional groove (annular groove 13) to prevent contact with the rotor labyrinth.

[0046] Possible additional features: Sealing rings 16a, 16b for sealing to the housing 2 (e.g. O-rings); fixation can be achieved via the seals; a type of fleece can also be inserted; a combination to form a grounding system is also possible. List of reference symbols 1 drive module 2 housings 3 Opening 4 Interior 5 Wave 6 first camp 7a first axial side of the bearing 7b second axial side of the bearing 8 Labyrinth seal 9 inner ring 10 Outer ring 11 Return hole 12 Return channel 13 Ring groove 14a first disc area of ​​the inner ring 14b second disc area of ​​the inner ring 14c third disc area of ​​the inner ring 15a first disc area of ​​the outer ring 15b second disc area of ​​the outer ring 15c third disc area of ​​the outer ring 15d fourth disc area of ​​the outer ring 16a first sealing ring 16b second sealing ring 17a first axial side of the return holes 17b second axial side of the return holes 18 Gearing area 19 second camp 20 wall 21 axis of rotation 22 Base section of the inner ring 23a first circle segment 23b second circle segment 24 Base section of the outer ring 25 gap

Claims

[1] Electric drive module (1) for a motor vehicle, comprising a housing (2), a shaft (5) projecting through an opening (3) of the housing (2) into an interior (4) of the housing (2), and a bearing (6) supporting the shaft (5) relative to the housing (2), wherein a labyrinth seal (8) is inserted between the housing (2) and the shaft (5) to act on a side (7a) of the bearing (6) facing the surroundings of the housing (2), wherein this labyrinth seal (8) has an inner ring (9) and an outer ring (10) arranged radially and without contact with the inner ring (9), wherein the outer ring (10) further has a plurality of return holes (11) penetrating it radially, and the return holes (11) are connected to a return channel (12) introduced into the housing (2), wherein the sealing ring (16b) inserted between the outer ring (10) and the housing (2) to act on a side facing the surroundings axially facing side (17a) of the return holes (11). [2] Drive module (1) according to claim 1, characterized by that the return holes (11) are arranged axially at the same height and evenly distributed over the circumference. [3] Drive module (1) according to claim 1 or 2, characterized by that the inner ring (9) is formed in one piece and / or the outer ring (10) is formed in several parts. [4] Drive module (1) according to one of claims 1 to 3, characterized by that the return holes (11) open into a radially outwardly open annular groove (13) of the outer ring (10). [5] Drive module (1) according to one of claims 1 to 4, characterized by that the inner ring (9) and the outer ring (10) are provided with several disc areas (14a, 14b, 14c, 15a, 15b, 15c, 15d) alternating in the axial direction. [6] Drive module (1) according to one of claims 1 to 5, characterized by that the outer ring (10) has at least two axially spaced disc regions (14a, 14b, 14c). [7] Drive module (1) according to claim 6, characterized by that the return holes (11) are introduced into the outer ring (10) between a first disc region (14a) axially closest to the surroundings and an adjoining second disc region (14b). [8] Drive module (1) according to one of claims 1 to 7, characterized by that the inner ring (9) has at least two axially spaced disc regions (15a, 15b, 15c, 15d). [9] Drive module (1) according to one of claims 1 to 8, characterized by that a sealing ring (16a, 16b) is inserted between the inner ring (9) and the shaft (5) and / or between the outer ring (10) and the housing (2).

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