Electric machine with elastically spring-loaded separating element for a cooling channel

Abstract

An electric machine (1) for propelling a motor vehicle, comprising a housing (2) and a stator (3) received in the housing (2), the stator being formed in a ring shape overall, wherein a cooling channel (4) is formed radially between the stator (3) and the housing (2), the cooling channel (4) being circumferentially extending along an outer circumference of the stator (3), which cooling channel (4) is connected at a first circumferential position (5a) to an inlet channel (6) and at a second circumferential position (5b), offset relative to the first circumferential position (5a), wherein a strip-shaped separating element (8) is inserted in the circumferential direction between the two circumferential positions (5a, 5b), which bears tightly against both the housing (2) and the stator (3), at least under elastic preload in the radial direction, wherein the separating element (8) has an axially extending web section (9), from which web section (9) radially angled wing sections extend on both sides in the circumferential direction. (10a,10b) protrude, characterized in that the web section (9) is provided with elongated recesses (24) towards its radial outer side, so that corresponding transverse webs (25) are formed at regular intervals to each other.

Description

[0001] The invention relates to an electric machine for driving a motor vehicle, preferably a car, truck, bus or other commercial vehicle, having a housing and a stator which is accommodated in the housing and is of an overall annular shape, wherein a cooling channel is formed radially between the stator and the housing and runs along an outer circumference of the stator, which cooling channel is connected to an inlet channel at a first circumferential position and to a return channel at a second circumferential position which is offset relative to the first circumferential position.

[0002] Generic electrical machines with corresponding cooling channels are already well known from the prior art. In this regard, EP 3 020 123 B1, for example, discloses a cooling system with a cooling jacket on an outer circumference of a stator, wherein a barrier element connected to the cooling jacket is provided for spatially separating an inlet region from an outlet region. Document DE 10 2015 213 479 A1 discloses an electrical machine according to the preamble of patent claim 1. Publication JP 2017-118 668 A shows a shield that is inserted between an inlet and an outlet for cooling fluid of an electrical machine. Document WO 2021 / 079 858 A1 discloses a sealing element for a cooling fluid channel that is inserted between the housing and the stator housing.

[0003] However, in the known designs, it has been found that the barrier elements used require a certain differential pressure between the inlet channel and the return channel to achieve the required sealing effect. Furthermore, during operation of the vehicle with the electric motor, the stator can shift radially relative to the housing, which in turn leads to a change in the gap between the stator and the housing at the corresponding circumferential points. This can also lead to leakage during operation when a certain minimum pressure builds up. This leads to the desired sealing effect not being achieved and, ultimately, the stator and its components not being sufficiently cooled.

[0004] It is therefore an object of the present invention to provide an electrical machine with an integrated cooling system, which fulfills a reliable cooling function even during the usual relative movements of the stator to the housing that occur during operation.

[0005] This is achieved according to the invention by inserting a strip-shaped separating element in the circumferential direction between the two circumferential positions, which, at least under elastic prestress in the radial direction, tightly abuts both the housing and the stator. The separating element is thus inserted in a radial gap between the housing and the stator, under elastic prestress in the radial direction.

[0006] This makes it possible to reliably seal the circumferential positions of the inlet and return channels with the separating element, even with the perfectly permissible relative movements between the housing and stator. Furthermore, a reliable sealing effect is achieved when the inlet channel is depressurized. This results in significantly more efficient cooling.

[0007] Furthermore, the separating element has an axially extending web section, from which radially positioned vane sections protrude (transversely) on both sides in the circumferential direction. These vane sections form the radially elastic region of the separating element. This makes it possible to compensate for relatively large relative movements / displacements between the housing and the stator. The web section is also provided with elongated recesses on its radial outer side, thus forming corresponding transverse webs at regular intervals.

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

[0009] For efficient production of the separating element, it has also been found to be advantageous if the separating element is inserted in such a way that the wing sections are radially prestressed / deformed (inserted) between 0.3 and 0.6 mm compared to an unprestressed / relaxed state.

[0010] Furthermore, it is expedient if the stator is mounted so that it can move relative to the housing, and the separating element is designed such that it rests tightly against both the housing and the stator in any relative position that may occur during operation. Such a relatively movable mounting is achieved, for example, by supporting the stator and housing in a manner that allows relative movement to a certain extent relative to one another by means of elastically deformable insert elements, such as O-rings, which can also serve as seals.

[0011] To further improve the sealing effect of the separating element, it is also beneficial if the separating element has a radially inwardly projecting projection that positively engages a recess in the stator. Preferably, the projection is formed directly on a radial inner side of the separating element / web section, thereby keeping the structure of the separating element as simple as possible. This results in a clever axial and circumferential fixation of the separating element to the stator.

[0012] For damage-free mounting of the separating element on the stator, it is furthermore expedient if the projection is chamfered at its end region facing away from the web section, preferably in the form of a chamfer or a radius.

[0013] If the separating element has several projections, for example two, the separating element is fixed to the stator in a sufficiently defined manner.

[0014] The sealing effect of the separating element is further improved if the separating element is formed on one axial end face with an axially deformable clamping lug, which is inserted into an undercut in the stator under elastic deformation. Particularly preferably, such a clamping lug is provided on each end face of the separating element, each of which is inserted into a separate undercut in the stator.

[0015] The sealing effect is further improved if a vibration damper is inserted radially between the housing and the stator on both sides of the separating element.

[0016] The invention will now be explained in more detail below with reference to figures.

[0017] They show: Fig. 1 a cross-sectional view of an electrical machine according to the invention according to a preferred embodiment in the region of a separating element inserted in a radial gap between a housing and a stator, wherein the positioning of the separating element relative to an inlet channel and a return channel can be seen, Fig. 2 a detailed view of the Fig. 1 area marked “II”, Fig. 3 a longitudinal section of the electrical machine along the Fig. 2 section plane marked “III-III”, Fig. 4 a longitudinal section of the electrical machine along the Fig. 2 section plane marked “IV-IV”, Fig. 5 a detailed view of the Fig. 4 area marked with “V” to represent a clamping lug formed on the separating element, Fig. 6 a perspective holistic representation of the Fig. 1 to 5 used separating elements, Fig. 7 a detailed view of an axial end face of the separating element in the Fig. 6 area marked “VII”, Fig. 8 a longitudinal section of the separating element along the Fig. 6 section plane marked “VIII-VIII”, Fig. 9 two cross-sectional views of the separating element along the Fig. 6 with the section plane marked “IX-IX”, whereby a left-hand illustration shows the separating element in a relaxed state and a right-hand illustration shows the separating element in an assembled and pre-tensioned state, in which wing sections of the separating element are elastically pivoted compared to the relaxed state, and Fig. 10 a longitudinal sectional view of the electrical machine to illustrate a vibration-damped mounting of the stator in the housing.

[0018] The figures are merely schematic and serve solely to clarify the invention. The same elements are designated by the same reference numerals.

[0019] In connection with the Fig. 1 and Fig. 10 shows the electrical machine 1 in its entirety. The electrical machine 1 has a housing 2, within which a stator 3 is accommodated. The stator 3 is essentially annular in its entirety. A rotor 19 is arranged radially within the stator 3 in the usual manner ( Fig. 10), which in turn is also preferably implemented in a ring shape.

[0020] A rotational axis 20 of the rotor 19, which also corresponds to a longitudinal axis of the stator 3, is in Fig. 10. The rotation axis 20, which is Fig. 1 and Fig. 2 is perpendicular to the plane of the drawing, thereby defining the axial direction, the radial direction, and the circumferential direction of the electrical machine 1. The term "axial direction" is thus understood to mean a direction along the axis of rotation 20, the term "radial direction" is understood to mean a direction perpendicular to the axis of rotation 20, and the term "circumferential direction" is understood to mean a direction along a circular line concentrically encircling the axis of rotation 20.

[0021] With the preferred embodiment, as also shown in Fig. As indicated in Figure 10, the stator 3 is essentially mounted so that it can vibrate relative to the housing 2. For this purpose, vibration dampers 18a, 18b are provided, which ensure that the stator 3 is movable / vibrating to a limited extent, particularly in the radial and axial directions, relative to the housing 2. The vibration dampers 18a, 18b are designed, for example, as rubber elements, here as O-rings. The vibration dampers 18a, 18b also preferably fulfill a sealing function.

[0022] Furthermore, the stator 3, as in Fig. 1, the stator 3 has an annular stator support 22, which accommodates a stator core 21 in the usual way toward its radial inner side. The stator support 22 thus forms a radial outer side of the stator 3.

[0023] Radially between the stator 3, here in the form of an outer circumference of the stator 3 / the stator carrier 22, and the housing 2, here in the form of a radial inner circumference of the housing 2, an annular circumferential cooling channel 4 is formed.

[0024] During operation, a cooling fluid typically flows through the cooling channel 4. For this purpose, an inlet channel 6 is connected to the cooling channel 4 at a first circumferential position 5a of the stator 3, via which inlet channel 6 cooling fluid is supplied from a pump to the cooling channel 4. The inlet channel 6 extends radially from the outside through the housing 2 to the cooling channel 4. Offset in the circumferential direction (approximately at an angle between 3° and 6°) to the first circumferential position 5a, a return channel 7 is connected to the cooling channel 4 at a second circumferential position 5b. The return channel 7 also extends in the housing 2, radially away from the cooling channel 4, and during operation directs the cooling fluid that previously flowed through the cooling channel 4 / cooling jacket back into a reservoir / to the pump.

[0025] In the circumferential direction between the first circumferential position 5a and the second circumferential position 5b, a separating element 8 is inserted into the cooling channel 4 / an annular recess / groove forming the cooling channel 4. This essentially strip-shaped separating element 8 extends in the axial direction and over the entire axial length of the cooling channel 4. The separating element 8 serves as a seal and consequently prevents the cooling fluid from escaping directly again via the return channel 7 via a short route, and thus serves to ensure that the cooling fluid flows through the entire cooling channel 4 around almost the entire circumference of the stator 3.

[0026] In connection with the Fig. 2 to 9, the inventive design of this separating element 8 and its inclusion in the cooling channel 4 can be seen in more detail.

[0027] In summary, the Fig. 2 and Fig. 9, it should be noted that the separating element 8, in addition to an axially extending web section 9, has two wing sections 10a, 10b projecting toward opposite sides in the circumferential direction. The first wing section 10a and the second wing section 10b are of the same strip-shaped design and project in opposite directions from the web section 9 in the circumferential direction. The first wing section 10a projects from the web section 9 toward the circumferential side facing the first circumferential position 5a, while the second wing section 10b projects from the web section 9 toward the circumferential side facing the second circumferential position 5b. The wing sections 10a, 10b also project (obliquely) away from the web section 9 in the radial direction. The wing sections 10a, 10b thus form radially deformable sections of the separating element 8.

[0028] According to the Fig. The height difference h between the left partial position and the right partial position marked in Figure 9 is the wing sections 10a, 10b in the assembled state, which corresponds to the state of the Fig. 1 to 5, compared to an unassembled state in which the wing sections 10a, 10b are not prestressed, is radially elastically deformed / bent by a dimension between 0.3 and 0.6 mm.

[0029] The separating element 8 is thus inserted into the cooling channel 4 in such an elastically prestressed manner that the separating element 8 is in sealing contact both on the side of the stator 3 (with the web section 9) and on the side of the housing 2 (with the wing sections 10a, 10b) even in a pressureless state in which no pressure is applied to the inlet channel 6 or the return channel 7, as well as in a state in which there is no pressure difference between the inlet channel 6 and the return channel 7.

[0030] Regarding the Fig. 3 it can also be seen that a vibration damper 18a, 18b in the form of a sealing ring, which runs completely around the circumference, is preferably inserted axially next to the cooling channel 4, to each axial end face 15a, 15b of the separating element 8. With the addition of the Fig. 10, however, it is in principle also possible to insert further vibration dampers 18a, 18b radially and / or axially between sections of the stator 3 and the housing 2 in order to enable the aforementioned vibration decoupling / relative vibration capability between the stator 3 and the housing 2.

[0031] For receiving the separating element 8, it is further advantageous if it has a projection 11a, 11b on at least two longitudinal regions. Each of the two projections 11a, 11b present here is realized in this embodiment as a (hollow) pin-shaped extension. On its outer circumference (radial outer circumference viewed in the longitudinal direction of the projection 11a, 11b), in the region of its axial end region 13 (facing away from the web section 9), the respective projection 11a, 11b is provided with a bevel in the form of a (circumferential) chamfer 14.

[0032] For each projection 11a, 11b, a complementary recess 12a, 12b is formed in the form of a blind hole inserted radially inward into the stator carrier 22. An outer circumference of the projection 11a, 11b is matched to the diameter of the recess 12a, 12b, so that the projection 11a, 11b is firmly received / supported on the stator 3 in a form-fitting manner in the axial direction and in the circumferential direction.

[0033] Furthermore, clamping lugs 16a, 16b are formed on the axial end faces 15a, 15b of the separating element 8, namely on the web section 9 ( Fig. 4 and Fig. 5). The respective clamping lug 16a, 16b forms a radially inwardly and axially protruding elevation. While a first clamping lug 16a is formed onto the first end face 15a of the separating element 8, a second clamping lug 16b is formed onto the second end face 15b of the separating element 8. The first clamping lug 16a protrudes radially inwardly and axially toward a first axial side of the separating element 8 / the web section 9; the second clamping lug 16b protrudes radially inwardly and axially toward a second axial side of the separating element 8 / the web section 9, facing away from the first axial side.

[0034] The respective clamping lug 16a, 16b is axially and radially deformable. The respective clamping lug 16a, 16b is engaged / snapped into a complementary undercut 17a, 17b in the stator 3, namely the stator support 22. The separating element 8 is pressed / inserted under preload in the axial direction with a specific preload in the stator 3, namely between two shoulder regions 23a, 23b of the stator support 22 forming the undercuts 17a, 17b.

[0035] Combined with Fig. 6 and Fig. 8 it can also be seen that the web section 9 is provided with elongated, in particular rectangularly elongated recesses 24 towards its radial outer side, so that corresponding transverse webs 25 are formed at regular intervals from one another.

[0036] In other words, according to the invention, an electrical machine 1 is designed with a cooling channel 4 arranged circumferentially around the stator 3 / stator carrier 22, wherein the inlet and outlet of this cooling channel 4 are separated from one another by a separating web (separating element 8) in order to minimize leakage losses and mixing of the cooling medium. The separating web is suitable for reducing leakage losses and mixing effects for vibration-decoupled electrical machines with structurally provided and functionally required gaps. The separating web is also suitable for reducing tolerance- and gap-related leakage losses and mixing effects for electrical machines without vibration-decoupled.

[0037] The separator is designed with elastically spring-loaded wing sections on both sides (wing sections 10a, 10b). The separator is designed with outer and inner sealing sections. The elastically spring-loaded wing sections are radially preloaded by 0.3 to 0.6 mm when installed.

[0038] Furthermore, the separating web is designed with clamping hooks arranged on both sides (clamping areas / clamping lugs 16a, 16b) for fastening in the undercut areas (undercuts 17a, 17b) of the stator carrier 22 to ensure safe axial positioning during operation.

[0039] The separating web is also preferably designed with at least two pins (projections 11a, 11b, preferably including a chamfer 14 as an assembly aid) for fastening in the pin openings (recesses 12a, 12b) of the stator carrier 22, to ensure secure angular positioning during operation.

[0040] The separating web can also be designed with assembly chamfers and assembly radii to ensure assembly during the joining of the stator / stator carrier and housing.

[0041] The separating web can also be designed with ribs (cross webs 25) to reduce material accumulation and to ensure the elasticity of the wing areas.

[0042] The Fig. 1 to 5 show the elastically spring-loaded separator according to the invention in the installed state: The separator is arranged radially between the stator support 22 and the housing 2 of the system. The separator is arranged between the inlet (supply channel 6) and outlet (return channel 7) of the cooling medium in the area of ​​the cooling channel 4. The separator seals the cooling channel 4 in the outer area against the housing 2 and in the inner area against the stator support 22.

[0043] Leakage zones are created in the areas between the left and right ends of the separator and the seals / sealing rings (vibration dampers 18a, 18b). These zones are flow-calmed relative to the main flow of the cooling medium, significantly reducing leakage losses and mixing effects.

[0044] The Fig. Figures 6 to 9 show the separator according to the invention as a single part, clearly showing the following details: Separator designed with elastic wing sections on both sides. Height offset / preload (h) of the wing sections by 0.3 to 0.6 mm before installation compared to after installation of the separator. Separator designed with ribs to reduce material accumulation and to ensure and constructively influence the elasticity of the wing sections.

[0045] The solution according to the invention of an elastically spring-loaded separating web in the region of the cooling channel 4 of the electrical machine 1 thus enables a reduction of leakage losses and mixing effects of the cooling medium between the inlet and outlet of the cooling channel 4, both, particularly advantageously, when using electrical machines with vibration decoupling, and also when using electrical machines without vibration decoupling. List of reference symbols 1 electric machine 2 housings 3 Stator 4 cooling channel 5a first circumferential position 5b second circumferential position 6 Inlet channel 7 Return channel 8 Separator 9 Bridge section 10a first wing section 10b second wing section 11a first projection 11b second projection 12a first recess 12b second recess 13 End area 14 chamfer 15a first axial end face 15b second axial end face 16a first clamping nose 16b second clamping lug 17a first undercut 17b second undercut 18a first vibration damper 18b second vibration damper 19 Rotor 20 axis of rotation 21 Stator laminated core 22 stator carrier 23a first shoulder area 23b second shoulder area 24 recess 25 crossbar

Claims

[1] An electric machine (1) for driving a motor vehicle, comprising a housing (2) and a stator (3) of an overall annular shape accommodated in the housing (2), wherein a cooling channel (4) is formed radially between the stator (3) and the housing (2) and runs along an outer circumference of the stator (3), which cooling channel (4) is connected at a first circumferential position (5a) to an inlet channel (6) and at a second circumferential position (5b) offset relative to the first circumferential position (5a) to a return channel (7), wherein a strip-shaped separating element (8) is inserted in the circumferential direction between the two circumferential positions (5a, 5b), which element bears tightly against both the housing (2) and the stator (3), at least under elastic prestress in the radial direction, wherein the separating element (8) has an axially extending web section (9),from which web section (9) radially positioned wing sections (10a, 10b) protrude in the circumferential direction on both sides, , characterized by that the web section (9) is provided with elongated recesses (24) towards its radial outer side, so that corresponding transverse webs (25) are formed at regular intervals from one another. [2] Electrical machine (1) according to claim 1, characterized by that the separating element (8) is inserted such that the wing sections (10a, 10b) are radially prestressed between 0.3 mm and 0.6 mm compared to an unprestressed state. [3] Electrical machine (1) according to one of claims 1 or 2, characterized by that the stator (3) is accommodated so as to be movable relative to the housing (2) and the separating element (8) is designed such that it bears sealingly against both the housing (2) and the stator (3) in any relative position that may occur between the stator (3) and the housing (2) during operation. [4] Electrical machine (1) according to one of claims 1 to 3, characterized by that the separating element (8) has a radially inwardly projecting projection (11a, 11b) which engages positively in a recess (12a, 12b) of the stator (3). [5] Electrical machine (1) according to claim 4, characterized by that the projection (11a, 11b) is bevelled at its end region (13) facing away from the web section (9). [6] Electrical machine (1) according to claim 4 or 5, characterized by that the separating element (8) has a plurality of projections (11a, 11b). [7] Electrical machine (1) according to one of claims 1 to 6, characterized by that the separating element (8) is formed on an axial end face (15a, 15b) with an axially deformable clamping nose (16a, 16b) which is inserted into an undercut (17a, 17b) in the stator (3) under elastic deformation. [8] Electrical machine (1) according to one of claims 1 to 7, characterized bythat a vibration damper (18a, 18b) is inserted radially between the housing (2) and the stator (3) on both sides of the separating element (8).

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