SEALING ARRANGEMENT IN THE COOLING CIRCUIT OF AN E-AXLE MODULE

Description

Technical area

[0001] The invention relates to an e-axle module comprising at least one electric motor and at least one power electronics unit. Furthermore, a sealing arrangement for a cooling circuit of the e-axle module is provided. State of the art

[0002] DE 10 2012 019 106 A1 relates to a plug-in piece. This piece is used for sealingly connecting two associated cylindrical surfaces and comprises a substantially tubular support body. This support body has annular sealing elements at its ends. These sealing elements can be brought into engagement with one of the cylindrical surfaces to be sealed to create a tight connection, with at least one of the sealing elements being designed as a sealing bead with a spherically curved sealing surface on the outer surface of the support body. The spherical radius of the sealing surface is selected such that the center of the sphere lies approximately on the axis of symmetry of the support body. This ensures a largely constant contact pressure across the sealing surface, regardless of the angular position of the plug-in piece in the installation space.

[0003] DE 10 2014 225 925 A1 relates to a sealing arrangement and a method for assembling a sealing arrangement. On the outer circumference of a substantially annular sealing part, two beads protrude radially beyond the circumference. Contact pressure is achieved by resilient elements located on both end faces of the substantially annular sealing body. These resilient elements press the beads molded onto the outer circumference against the inner surface of the housing when the sealing bushing is assembled, so that the beads form a sealing contact against the inner surface.

[0004] DE 10 2004 058 302 A1 relates to a sealing bushing, in particular for a hydraulic device. The sealing bushing is made of a plastic material and has a preferably conical protrusion on one end face, which can be sealingly applied to a contact shoulder or the like. A frustoconical protrusion is formed on a rear end face, into which a sealing bushing bore opens. The protrusion tapers off into a front face at a distance from the outer circumference of the sealing bushing.

[0005] DE 10 2011 076 312 A1 relates to a cooling device for a housing. At least one component of a power electronics system is housed in the housing. A cooling structure represents a cooling surface for the housing. The cooling structure to be overmolded is supported during the housing's manufacture by a medium acting on the cooling structure to be overmolded.

[0006] Further e-axle modules or sealing arrangements are known from EP 3 663 689 A1, US 2014 / 217 727 A1, FR 2 790 303 A1, WO 2007 / 040 408 A1, DE 10 2019 124 280 A1 and WO 2020 / 189 826 A1. Description of the invention

[0007] According to the invention, an e-axle module is proposed, comprising at least one electric machine and at least one power electronics unit and a cooling circuit with a sealing arrangement therein, wherein the sealing arrangement comprises a tubular insert on which a first sealing element is arranged, wherein a further sealing element is assigned to one of the end faces of the tubular insert, wherein an overflow opening is provided between the sealing elements, wherein the tubular insert is received in a recess of a housing of the electric machine and the overflow opening is designed in a wall of the recess of the housing.

[0008] This solution allows the cavity of a power electronics unit to be effectively and reliably sealed against cooling medium flowing through the cooling circuit due to the arrangement of the overflow hole in a housing wall, so that the functionality of the power electronics unit is guaranteed at all times.

[0009] The overflow opening in a wall of the housing is dimensioned in particular in such a way that the flow of the cooling medium continuously flowing through the tubular insert can be diverted and the tightness of the cavity of the power electronics with the electronic semiconductor components accommodated therein is always guaranteed.

[0010] In a further advantageous embodiment of the sealing arrangement proposed according to the invention, the tubular insert is designed with a conicity that corresponds to the conicity of a recess in the housing. The conicity of the tubular insert and the recess prevents damage to a sealing element on the circumference of the tubular insert when inserted vertically into the recess, which significantly simplifies production.

[0011] The sealing arrangement proposed according to the invention comprises the first sealing element, which can be designed as an O-ring and sits on a lateral surface of the tubular insert. For this purpose, the insert can be provided with at least one circumferential groove extending in the circumferential direction of the tubular insert. It is also possible to design the first sealing element as a V-shaped sealing disc and arrange it on one of the end faces of the tubular insert. As the pressure of the cooling medium increases, the V-shape of the sealing disc causes the seal to expand and the sealing parts of the V-shaped sealing parts to be pressed firmly against opposing walls of the housing or the tubular sealing element, so that the cavity of the power electronics remains sealed at all times.

[0012] In a further advantageous embodiment of the sealing arrangement proposed according to the invention, the additional sealing element can also be designed as an O-ring and arranged on a circumferential surface of the tubular insert. In addition, it is possible to design additional sealing elements as V-shaped sealing discs or as X-rings and to assign them to one of the end faces of the tubular insert. Even with this design option for the additional sealing element, the geometry of the additional sealing element, in particular designed as a V-shaped sealing disc or as an X-ring, can widen the sealing element and thus achieve better contact between the sealing parts of the additional sealing element and opposing walls.

[0013] In a further advantageous embodiment of the sealing arrangement proposed according to the invention, the first sealing element and the further sealing element can each be designed as an O-ring, which are arranged at a vertical distance from one another with respect to the tubular insert.

[0014] By means of the sealing arrangement proposed according to the invention, the cavity of the power electronics can be effectively sealed against the cooling medium flowing through the housing or the tubular insert via the first sealing element. Advantages of the invention

[0015] The solution proposed by the invention allows for the creation of a compact sealing arrangement that allows for multiple sealing. In addition to the tubular insert, the sealing arrangement proposed by the invention comprises said sealing elements, namely at least a first sealing element and a further sealing element. These can be implemented in various variants, but in all variants, they are located at a vertical distance from one another with respect to the axial extent of the tubular insert.

[0016] In particular, the solution proposed according to the invention ensures that, when the tubular insert is mounted in a recess on a housing, the incoming cooling medium is discharged via an overflow opening in the housing located between the first sealing element and the further sealing element. The overflow opening in the wall of the housing or in the wall of the recess in the housing, for example, of the electric machine, is dimensioned to ensure that the cooling fluid flowing through the tubular insert can be safely discharged.

[0017] If, for example, one of the sealing elements is designed as a V-shaped sealing disc, the geometry of the sealing element can also absorb an increased pressure level. With a V-shaped sealing geometry or a sealing element designed as an X-ring, the pressure increase, for example, due to a constantly flowing coolant, ensures that the V-shaped sealing geometry is pressed with increased contact pressure against contact surfaces, whether against the wall of the recess or the outer surface of the tubular insert. This increases the sealing effect and reliably prevents unwanted penetration of coolant into the cavity of the power electronics.This applies both to the first sealing element and to the further sealing element, regardless of whether the sealing elements are respectively received on the outer surface of the tubular insert or on one of the end faces of the tubular insert or are assigned to them.

[0018] If, for example, both the tubular insert and the recess are designed with a conicity, it can be ensured when assembling, for example, two O-ring-shaped sealing elements that damage the O-ring-shaped sealing elements due to existing burrs in the area of ​​the overflow opening can be ruled out during production.

[0019] The solution proposed by the invention seals the cooling circuit between the power electronics (inverter) and the electric motor of an e-axle module cost-effectively. Furthermore, the use of the solution proposed by the invention ensures simple assembly. Furthermore, the sealing arrangement proposed by the invention with a double seal ensures that under no circumstances can cooling fluid enter the cavity of the power electronics, in which the semiconductor components are arranged. The solution proposed by the invention is characterized overall by the use of fewer components, and furthermore, the manufacturing effort is significantly reduced. Assembly effort is also reduced, and assembly reliability is increased, since damage to the first sealing element or the additional sealing element, for example due to the conicity of the tubular insert and corresponding recess, is prevented.Furthermore, the integration of the tubular insert into a recess in one of the housings reduces the space requirement, as the sealing arrangement is, to a certain extent, enclosed by the housing, for example of the electrical machine.

[0020] The sealing arrangement proposed by the invention, which offers a dual sealing option, seals the cooling circuit and the power electronics against the environment. The two seals are spatially separated from each other, so that if one seal fails, the overflow opening continuously discharges incoming cooling fluid, thus ensuring that incoming cooling fluid does not penetrate the cavity of the power electronics. Furthermore, the spatial separation of the first and second sealing elements has the advantage of making it easier to perform a leak test during service or in the event of a failure, and any leaks can be located more quickly. Short description of the drawings

[0021] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0022] They show: Figures 1 to 3 show a sealing arrangement between an electrical machine on the one hand and a housing of a power electronics system on the other hand, using a plastic cable running outside the housing and using a sealing bushing. Figure 4 shows a first embodiment of the sealing arrangement proposed according to the invention. Figure 5 shows a further embodiment of the sealing arrangement proposed according to the invention using a tubular insert having a conicity. Figure 6 shows a further embodiment of the sealing arrangement proposed according to the invention with a further sealing element designed as a V-shaped sealing disc. Figure 7 shows a further embodiment of the sealing arrangement proposed according to the invention with a sealing element designed as a V-shaped sealing disc.

[0023] Figure 1shows an e-axle module 10, in whose housing 12 an electric motor 14 is housed. A plastic cable 16 runs on the outside of the housing 12, which is connected to a housing wall 22 and is attached to the housing 12 via several mounting flanges 18.

[0024] Figure 2 shows the housing 12 of the electric machine 14 in a side view. The housing 12 accommodates the electric machine 14; a cooling line extends from it to the plastic line 16, into which a sealing bushing 30 is embedded. The sealing bushing 30 is, as shown in Figure 2 enclosed by a nozzle 28 which is sealed by means of a seal 26 on the housing 12.

[0025] Figure 3shows an enlarged view of the sealing bushing 30, which is sealed at one end in the nozzle 28 and at its other end in the plastic line 16. The nozzle 28, in turn, is sealed into the housing 12 by means of a seal 26 designed as an O-ring. A cavity 42 of a power electronics unit 24 is sealed against the cooling medium flowing through the plastic line 16 via the sealing bushing 30. Embodiments of the invention

[0026] In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

[0027] Figure 4shows a first embodiment of a sealing arrangement 40 proposed according to the invention. A cavity 42 of the power electronics 24 of the E-axle module 10 is sealed against a cooling medium circulating in the cooling circuit of an E-axle module 10 by means of the sealing arrangement 40. From the illustration according to Figure 4 It can be seen that the cavity 42 of the power electronics 24 is delimited by a housing plate 44, which is shown only schematically here. The sealing arrangement 40 essentially comprises a tubular insert 48, which is embedded in a recess 52 of a housing wall 22 of the housing 12 of the e-axle module 10 or the electric machine 14. From the illustration according to Figure 4 It can be seen that the tubular insert 48 is designed symmetrically to an axis of symmetry 46. According to Figure 4The housing 12 comprises an overflow opening 56 extending from its inner surface 50, which can be designed, for example, as a bore. On a surface 54 of the tubular insert 48, there are a first sealing element 62 and a further sealing element 64. These are arranged at a vertical distance 70 from one another with respect to the axis of symmetry 46 of the tubular insert 48. The sealing elements 62, 64, designed, for example, as O-rings, can be embedded in recesses 58, 60 formed on the surface 54 of the tubular insert 48 and can be axially fixed. From the illustration according to Figure 4 It can be seen that the overflow opening 56 is located approximately centrally between the two sealing elements 62, 64.

[0028] If the additional sealing element 64 fails and becomes leaky, cooling fluid flowing out of the housing 12 flows through the overflow opening 56, ensuring that the cavity 42 of the power electronics 24 remains sealed against the incoming cooling medium by the first sealing element 62. Consequently, the cavity 42 of the power electronics 24, including the semiconductor components arranged therein, remains dry, thus maintaining the functionality of an electrically powered vehicle.

[0029] While according to the sealing arrangement 40 as shown in Figure 4 As shown, the cavity 42 of the power electronics 24 remains sealed in the event of failure of the further sealing element 64, the cooling circuit is sealed against the environment via the further sealing element 64. The Figure 4 The overflow opening 56 shown is designed so that sufficient cooling medium can be discharged through it. Instead of the overflow opening shown in the sectional view according to Figure 4 In addition to the overflow opening 56 shown, several overflow openings 56 can also be formed in the wall of the recess 52 of the housing 12.

[0030] Figure 5 shows another version of the Figure 4 illustrated embodiment of the sealing arrangement 40 according to the invention. In contrast to the illustration according to Figure 4 are in the Figure 5 In the embodiment shown, both the tubular insert 48 and the recess 52 are manufactured with respect to their inner surface 50 in conicities 66 and 68, respectively. In the illustration according to Figure 5O-rings 86 are used as sealing elements 62, 64. The conicity 66 of the outer surface 54 of the tubular insert 48 as well as the conicity 68 of the recess 52 ensure that when installing the further sealing element 64 in the form of an O-ring 86, damage caused, for example, by remaining burrs on the inner surface 50 of the recess 52 in the area of ​​the overflow opening 56 does not damage the further sealing element 64. Even in the embodiment according to Figure 5the at least one overflow opening 56 is dimensioned such that sufficient cooling fluid can be discharged, wherein the tightness of the cavity 42 of the power electronics 24 is ensured by the first sealing element 62, designed as an O-ring 86, being in contact with its first recess 58 on the one hand and with the inner surface 50 of the depression 52 on the other hand. A first end face of the tubular insert 48 is identified by reference numeral 96, while an opposite second end face of the tubular insert 48 is designated by reference numeral 98. In the region of the first end face 96, the tubular insert 48 is enclosed by the housing sheet 44. In the embodiments of the sealing arrangement 40 according to the invention according to the Figures 4 and 5The two sealing elements 62, 64 - here each designed as O-rings 86 - are spaced apart in the vertical direction by a distance 70. Within this distance 70, the at least one overflow opening 56 is located in the housing wall 22 of the housing 12 of the electrical machine 14. Also in the embodiment according to Figure 5 the tubular insert 48 is manufactured symmetrically to its axis of symmetry 46.

[0031] Figure 6shows a further embodiment of the sealing arrangement 40 proposed according to the invention. According to this embodiment, the further sealing element 64 is designed as a V-shaped sealing disc 72. While the further sealing element 64 - here designed as an O-ring 86 - is received in the second recess 60 on the outer surface 54 of the tubular insert 48, the further sealing element 64 in the form of the V-shaped sealing disc 72 is assigned with an end face 74 of the first end face 96 of the tubular insert 48. From the illustration according to Figure 6 It can be seen that in this embodiment, too, the at least one overflow opening 56 is located in the area between the first sealing element 62 in the form of the V-shaped sealing disc 72 and the further sealing element 64 designed as an O-ring 86. Also in the embodiment of the sealing arrangement 40 proposed according to the invention according to Figure 6several overflow openings 56 can be formed in the wall which delimits the recess 52.

[0032] If the additional sealing element 64 in the form of the O-ring 86 fails, the cooling medium flowing in the gap between the outer surface 54 of the tubular insert 48 and the inner surface 50 forces the V-shaped sealing disc 72 apart. Consequently, the material of the additional sealing element 64 in the form of the V-shaped sealing disc 72 is pressed against the material of the inner surface 50 of the recess 52 on the one hand and against the outer surface 54 of the tubular insert 48 on the other, so that the sealing effect is improved with increasing pressure. Consequently, the cavity 42 of the power electronics 24, including the semiconductor components accommodated therein, remains sealed against incoming cooling medium.

[0033] In the embodiment of the sealing arrangement 40 proposed according to the invention according to Figure 7the first sealing element 62 is designed as an O-ring 86. The first sealing element 62 is inserted into the first recess 58 on the outer surface 54 of the tubular insert 48. The tubular insert 48 is also in the embodiment according to Figure 7 symmetrical to its axis of symmetry 46.

[0034] In the version according to Figure 7 the further sealing element 64 is designed as a V-shaped sealing disc 76. This rests on a flat surface 78 at the bottom of the, for example, pot-shaped recess 52 of the housing 12. The further sealing element 64 in the form of the V-shaped sealing disc 76 lies between the second end face 98 of the tubular insert 48 and the flat surface 78 at the bottom of the, for example, pot-shaped recess 52. Also in the embodiment according to Figure 7the overflow opening 56 is located in the area between the first sealing element 62, designed as an O-ring 86, on the one hand, and the further sealing element 64, which in this case is designed as a V-shaped sealing disc 76, on the other hand. In the embodiment according to Figure 7If the pressure of the cooling medium acts on the sealing arrangement 40, the V-shaped sealing disk 76 used as a further sealing element 64 is pressed against the second end face 98 of the tubular insert 48 on the one hand due to its V-shaped geometry and on the other hand against the flat surface 78 at the bottom of the recess 52. If, however, the further sealing element 64 fails, the cavity 42 of the power electronics 24 with its liquid-sensitive components remains in its sealed state via the first sealing element 62 designed as an O-ring 86, ie the cooling medium can be discharged via the overflow opening 56 in the wall of the recess 52 of the housing 12.

[0035] As an alternative to the V-shaped sealing disc 76 as shown in Figure 7The additional sealing element 64 can also be designed as an X-ring 80. Due to its deformability, due to its geometry, this is also suitable for generating higher sealing forces as the pressure of the cooling medium in the cooling circuit increases, since, due to its geometry, areas of the X-ring 80 are pressed either against the flat surface 78 at the bottom of the recess 52 on the one hand and against the second end face 98 of the tubular insert 48 on the other hand, thus achieving an increased sealing effect.

[0036] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible within the scope of the claims, which are within the scope of one skilled in the art.

Claims

1. E-axle module (10), comprising at least one electric machine (14) and at least one power electronics system (24) and a cooling circuit having a seal assembly (40) therein, wherein the seal assembly (40) comprises a tubular insert (48) on which a first sealing element (62, 72) is arranged, wherein a further sealing element (64, 76, 80) is assigned to one of the end faces (96, 98) of the tubular insert, wherein an overflow opening (56) is provided between the sealing elements (62, 72; 64, 76, 80), wherein the tubular insert (48) is received in a recess (52) of a housing (12) of the electric machine (14) and the overflow opening (56) is made in a wall of the recess (52) of the housing (12).

2. E-axle module according to Claim 1, characterized in that the tubular insert (48) is designed with a conicity (66) that corresponds to a conicity (68) of the recess (52) in the housing (12).

3. Seal assembly (40) according to Claims 1 and 2, characterized in that the first sealing element (62) is designed as an O-ring (86) and sits on a lateral surface (54) of the tubular insert (48).

4. Seal assembly (40) according to Claims 1 and 2, characterized in that the first sealing element (62) is designed as a V-shaped sealing washer (72) and sits on one of the end faces (96, 98) of the tubular insert (48).

5. Seal assembly (40) according to Claims 1 and 2, characterized in that the further sealing element (64) is designed as an O-ring (86) and sits on a lateral surface (54) of the tubular insert (48).

6. Seal assembly (40) according to Claims 1 and 2, characterized in that the further sealing element (64) is designed as a V-shaped sealing washer (72) or as an X-ring (80) and is assigned to one of the end faces (96, 98) of the tubular insert (48).

7. Seal assembly (40) according to Claims 1 and 2, characterized in that the first sealing element (62) and the further sealing element (64), which are designed as an O-ring (86), are arranged at a vertical distance (70) from each other on the tubular insert (48).

8. Seal assembly (40) according to Claims 1 to 7, characterized in that a cavity (42) of the power electronics system (24) is sealed off by means of the first sealing element (62, 72) against the cooling medium still flowing through the housing (12).