Electric vehicle traction motor

Abstract

The invention relates to an electric vehicle traction motor (10) having a liquid-cooled motor stator (20), a dry-running motor rotor (30) and a fluid-tight sealing tube (50) which fluidically separates the motor stator (20) from the motor rotor (30) from one another, wherein the sealing tube (50) is formed from a fiber composite (52), wherein a sealing tube axial clamping device (70) is provided by means of which the sealing tube (50) is permanently subjected to an axial pretension.

Description

TECHNICAL FIELD

[0001] The invention relates to an electric vehicle traction motor having a liquid-cooled motor stator, a dry-running motor rotor and a fluid-tight sealing tube separating the motor stator and the motor rotor from one another. BACKGROUND

[0002] Electric vehicle traction motors provide a drive power in the range of several 2-digit to 4-digit kilowatts, so that high power losses in the form of heat occur, in particular in the motor stator in which the motor windings are arranged, which have to be dissipated by means of liquid cooling. Such electric vehicle traction motors are therefore constructed as so-called sealing tube motors, in which the liquid-cooled motor stator is fluidically separated from the dry-running motor rotor by means of a sealing tube, wherein the sealing tube is a thin-walled tube.

[0003] Different concepts are known for the sealing tube. Thus, the sealing tube or sealing tube body can be designed to be self-stable, i.e. it is designed to be rigid, so that the sealing tube retains its shape and design outside the installed state. In addition, the liquid pressure of the cooling liquid in the stator chamber does not deform the sealing tube. The sealing tube can be formed from a fiber composite material, as this is known, for example, from DE 10 2009 032 158 Al or DE 20 2011 103 644 Ul. Such a sealing tube can be realized with a small material thickness, since a relatively small radial gap between the motor stator and the motor rotor can be achieved thereby, which enables a high electrical efficiency of the traction motor. However, a problem of a sealing tube formed from a fiber composite is its mechanical sensitivity to deformation. SUMMARY

[0004] In relation thereto, it is an object of the present invention to propose an electric vehicle traction motor with high efficiency.

[0005] According to the invention, this object is achieved by an electric vehicle traction motor according to the invention.

[0006] The electric vehicle traction motor according to the invention has a liquid-cooled motor stator and a dry-running motor rotor, which is preferably designed as an inner armature, so that the motor stator preferably surrounds the motor rotor annularly. A liquid-cooled stator chamber in which the motor stator is arranged is fluidically separated from a rotor chamber in which the motor rotor is arranged by means of a fluid-tight sealing tube. The sealing tube is formed here from a fiber composite, i.e. from a body made of, for example, fiber-reinforced plastic.

[0007] According to the application, it is proposed that an axial clamping device for the sealing tube is provided, by means of which the sealing tube is permanently subjected to axial pretensioning. The sealing tube formed from a fiber composite can be relatively thin-walled. In particular, the fiber composite can be implemented by means of a corresponding manufacturing method, for example by hardening on a mandrel, to a thin-walled sealing tube sleeve with a precisely manufactured inner peripheral wall. The fiber composite is tensioned in tension by the permanent axial pretensioning of the fiber composite sealing tube. In the event of external forces acting perpendicular to the local sealing tube plane, i.e. in the radial direction, the sealing tube is only slightly bulged, since the relatively high stiffness and the axial pretensioning of the fibers make it difficult for the sealing tube to deform.

[0008] Since the sealing tube is formed from a fiber composite with a relatively thin wall, the annular gap between the motor stator and the motor rotor is also relatively small, so that a very good electrical efficiency is achieved. The mechanical robustness of the sealing tube with respect to the force action in the radial direction is achieved by the axial pretensioning of the sealing tube. Thereby, advantages also arise with respect to the manufacture and assembly of the traction motor, since in particular the sealing tube can be manufactured relatively inexpensively and the requirements with respect to the manufacturing precision of the motor stator, in particular of the lamination stack of the motor stator, are also relatively low.

[0009] Preferably, the longitudinal end of the sealing tube is fixed in a fixed manner to the motor housing, while an axial clamping device for the sealing tube is provided at the other longitudinal end. Naturally, however, it is alternatively also possible for an axial clamping device to be provided at both longitudinal ends of the sealing tube.

[0010] The axial clamping device for the sealing tube preferably has an axially displaceable axial clamping ring, to which the longitudinal end of the sealing tube is connected in a tension-proof manner. The axial clamping ring can be axially positioned by means of at least one corresponding clamping element, so that the axial clamping ring can be pressed or tensioned in the direction of the relevant axial longitudinal end of the traction motor, in order to axially clamp the sealing tube fastened on the axial clamping ring in this way. The axial clamping during assembly can thereby be relatively simple and can be adjusted very precisely from the outside.

[0011] A clamping ring seal is preferably arranged between the axial clamping ring and a guide flange of the motor housing, which is fixed relative to the housing. The clamping ring seal can be formed, for example, by means of an annular O-ring. Thereby, the annular gap between the axially movable axial clamping ring and the guide flange of the motor housing, which is unavoidable, is permanently and reliably sealed in a fluid-tight manner.

[0012] Preferably, at least one longitudinal end of the sealing tube fiber composite is held in a force-locked manner by a clamping assembly. In this way, the holding force can be distributed evenly over the entire circumference of the sealing tube. It is particularly preferred that the clamping assembly has an outer clamping ring and an inner clamping ring, wherein the associated end region of the sealing tube fiber composite is clamped or clamped in radially between the two clamping rings. The outer clamping ring and / or the inner clamping ring can be formed by a plurality of sub-clamping rings, for example by four clamping rings each of 90°.

[0013] Instead of a clamping assembly, a plurality of holding openings can be provided in the sealing tube fiber composite at at least one longitudinal end, which are held by corresponding holding bolts on the housing side, which have for example a radial extension. For this purpose, a corresponding strength of the sealing tube fiber composite is required in the region of the holding openings. The holding bolts can for example be formed by threaded head bolts which are screwed radially into a component of the housing side.

[0014] At the longitudinal end of the sealing tube provided with an axial clamping device, the holding openings can be designed as clamping openings in the fiber composite, into which clamping openings wedge elements which can be tensioned radially outwards or inwards in the radial direction radially engage. Here, the wedge surface of the wedge elements tensions the associated opening edges of the clamping openings in the sealing tube fiber composite.

[0015] At at least one longitudinal end of the sealing tube, a separate elastically deformable fluid seal can be provided radially on the inside of the sealing tube fiber composite, which reliably closes the gap between the sealing tube and a corresponding component of the housing side in a fluid-tight manner.

[0016] Preferably, the sealing tube is flared or conically widened at at least one longitudinal end, so that the inner radius at the widened longitudinal end of the fiber composite is greater than the inner radius of the fiber composite at the axial middle of the sealing tube. Thereby, the radial load capacity of the sealing tube is further improved. Furthermore, by flaring one or both longitudinal ends of the sealing tube, the flow guidance of the cooling liquid in the stator chamber can also be improved if necessary. It is particularly preferred that the sealing tube fiber composite is designed as a constant cylinder at the longitudinal ends before assembly, and only the assembly process widens the longitudinal ends flared or conically. BRIEF DESCRIPTION OF DRAWINGS

[0017] Three embodiments of the application are explained in more detail below with the aid of the drawings. In the drawings:

[0018] Figure 1 A first embodiment of an electric vehicle traction motor according to the application is shown schematically in a longitudinal section, which has an axially displaceable axial clamping ring;

[0019] Figure 2 A second embodiment of an electric vehicle traction motor according to the present application is schematically shown in longitudinal section with a clamping assembly for force-locked fixing of a fiber composite and funnel-shaped widenings of a sealing tube at both longitudinal ends of the sealing tube; and

[0020] Figure 3 A third embodiment of an electric vehicle traction motor according to the present application is schematically shown in longitudinal section with a plurality of wedge-shaped elements engaged into corresponding clamping openings of a sealing tube.

[0021] Figure 4 A partial top view is shown in Figure 3 DETAILED DESCRIPTION

[0022] An electric vehicle traction motor 10 is schematically shown in the drawing with a liquid-cooled motor stator 20 and a dry-running motor rotor 30. The motor rotor 30 is designed as a so-called inner armature, such that the motor stator 20 annularly surrounds the central motor rotor 30. The motor rotor 30 and the motor stator 20 are arranged inside a motor housing 11 and are fluidically separated from each other by a fluid-tight sealing tube 50; 50'; 50". Thereby, an annular stator chamber 40 is formed, in which the motor stator 20 is arranged and is continuously liquid-cooled during motor operation by a suitable cooling liquid. The cooling liquid flows into the stator chamber 40 inwardly through a cooling liquid inlet 41 at a motor longitudinal end and flows out of the stator chamber 40 through a cooling liquid outlet 42 at the other motor longitudinal end.

[0023] The motor stator 20 is generally formed by a stator lamination stack 26 formed by a plurality of stator laminations 26' and a plurality of stator coils 24, wherein each stator coil 24 has a coil head 22, also referred to as winding head, respectively extending out of the stator lamination stack 26 at its longitudinal end. The motor rotor 30 schematically shown here has a rotor shaft 32 which is rotatably supported in bearings 35, 36 at its two longitudinal ends, respectively. The rotor shaft 32 carries an electromagnetic motor rotor body 34 which can be designed, for example, as a permanent magnet.

[0024] In all three embodiments, the sealing tube 50; 50'; 50" is formed by a fiber composite 52 which is designed as a constant hollow cylinder before assembly. The fiber composite 52 is relatively thin-walled and can be manufactured in different ways, for example by wet winding or dry winding. The winding of the fiber composite 52 can be carried out on a mandrel, whereby a high dimensional accuracy of the inner wall of the fiber composite can be achieved.

[0025] ​In the assembled state, the sealing tube 50; 50'; 50" is permanently subjected to axial pretension by means of the sealing tube axial clamping device 70; 170; 270. The axial clamping device 70; 170; 270 is arranged on the longitudinal end of the sealing tube 50; 50'; 50", respectively, while the other longitudinal end of the sealing tube 50; 50'; 50" is fixed to the housing by the stationary support 60; 160 and held in an axially non-adjustable manner. The fiber composite 52 can have a lower expansion coefficient than the motor housing 11, so that the axial stress of the sealing tube 50; 50'; 50" increases upon heating. It is particularly preferred that the thermal expansion coefficients are identical (or at least similar).

[0026] In the three embodiments, two different ways of fixing the longitudinal end of the sealing tube are shown. As shown in Figure 2 , at both longitudinal ends, respectively, a clamping assembly 160 can be provided, by means of which the two longitudinal ends of the sealing tube fiber composite 52 are held force-locked and by a largely uniform force distribution over the entire circumference. The clamping assembly 160 accordingly has an inner clamping ring 162' and an outer clamping ring 162 in the radial direction, wherein the relevant end region of the sealing tube fiber composite 52 is firmly clamped between the two clamping rings 162, 162', so that the force-locking between the two clamping rings 162, 162' and the clamped annular face of the sealing tube fiber composite 52 can transmit a high axial clamping force. A clamping ring fixing bolt 164 radially presses the outer clamping ring 162 against the inner clamping ring 162', so that the relevant longitudinal end of the sealing tube fiber composite 52 is uniformly clamped. The outer clamping ring 162 can be formed in multiple parts, so that, for example, four clamping ring subrings of each approximately 90° are provided in the circumferential direction.

[0027] In Figure 1 and Figure 3 , another embodiment for fixing the longitudinal end of the sealing tube at the housing-side component is shown, namely a classic screw assembly 74. The screw assembly 74 accordingly consists of a plurality of openings 76, which are distributed annularly on the relevant end region of the sealing tube fiber composite 52. In each opening 76, a threaded head bolt 74' is accordingly inserted, which with its outer thread 79 is screwed into the corresponding inner thread 78 of the housing-side, externally cylindrical annular flange 62. Between the annular flange 62 and the inner side of the sealing tube fiber composite 52, a rubber-elastic sealing ring 81 is accordingly arranged, which is arranged axially directly adjacent to the screw joint.

[0028] In Figure 1The image illustrates a first embodiment of the axial clamping device 70 for the sealing tube. The axial clamping device 70 is generally formed by an axially displaceable and adjustable axial clamping ring 72, which is radially fixed by a guide flange 12 fixed to an annular housing and guided axially displaceable. The axial clamping ring 72 can be adjusted axially by a plurality of circumferentially distributed clamping bolts 84. The clamping bolts 84, with their bolt shanks 84', respectively pass through axial holes 83 in the motor housing end wall 13 and engage with corresponding axial internal threads 86 of the axial clamping ring 72 with their respective external threads 85. By rotating the clamping bolts 84, the axial clamping ring 72 can be moved axially in the distal clamping direction F, thereby axially stretching and tensioning the sealing tube fiber composite 52. A clamping ring seal 80 formed of an elastic O-ring is arranged between the guide flange 12 and the axial clamping ring 72.

[0029] exist Figure 2 The image shows a second embodiment of the axial clamping device 170 for sealing tubes, which differs from the previous embodiment in only one detail. Figure 1 The axial clamping device 70: The contact surface 162' of the axial clamping ring 172 is designed to be tapered on the outside, causing the relevant longitudinal end of the sealing tube 50' to be widened in a funnel shape. The longitudinal end of the sealing tube fiber composite 52 on the fixed support side is also widened in a funnel shape because the relevant flange 162' fixed relative to the housing is also designed in a funnel shape on its outer periphery. In this way, the inner radius RE at these two widened longitudinal ends of the sealing tube is greater than the inner radius RM at the axial midpoint of the sealing tube 50', for example, by at least 3%.

[0030] exist Figure 3 The image illustrates a third embodiment of the axial clamping device 270 for the sealing tube, which comprises a plurality of circumferentially distributed clamping openings 276 in a ring shape within the fiber composite 52 and a corresponding number of wedge elements 280, which radially engage with the elliptical clamping openings 276. Each wedge element 280 has a wedge surface 282 at its distal end. The wedge elements 280 can be adjusted in their radial position by means of clamping bolts 274, thereby pre-tightening the fiber composite 52 axially along the clamping direction F. The clamping bolts 274 are radially screwed into an annular guide flange 272 fixed relative to the housing.

Claims

1. An electric vehicle traction motor (10) comprising: a liquid-cooled motor stator (20); a dry-running motor rotor (30); and a fluid-sealed sealing tube (50; 50'; 50”) that fluidly separates the motor stator (20) from the motor rotor (30), wherein the sealing tube (50; 50'; 50”) is formed of a fiber composite (52). Its features are, An axial clamping device for the sealing tube is provided, and the sealing tube (50; 50'; 50") is permanently pre-tightened by the axial clamping device.

2. The electric vehicle traction motor (10) according to claim 1, wherein the sealing tube axial clamping device has an axially displaceable axial clamping ring (72; 172), the longitudinal end of the sealing tube (50; 50') is connected to the axial clamping ring in a tensile manner, and the axial clamping ring can be axially positioned by a clamping element (84).

3. The electric vehicle traction motor (10) according to claim 1 or 2, wherein at least one longitudinal end of the fiber composite (52) of the sealing tube (50') is held in a force-locking manner by a clamping assembly (160).

4. The electric vehicle traction motor (10) according to claim 1 or 2, wherein at at least one longitudinal end, the fiber composite (52) of the sealing tube (50; 50”) has a plurality of retaining openings (76) held by corresponding retaining bolts (74).

5. The electric vehicle traction motor (10) according to claim 1 or 2, wherein the sealing tube (50') is funnel-shaped widened at at least one longitudinal end such that the inner radius (RE) at the widened longitudinal end of the fiber composite (52) is greater than the inner radius (RM) of the axial center of the sealing tube (50').

6. The electric vehicle traction motor (10) according to claim 1 or 2, wherein the sealing tube axial clamping device is formed by a plurality of clamping openings (276) and a wedge element (280) in the fiber composite (52), the wedge element being radially engaged into the clamping openings (276) and capable of being pulled tight in the radial direction.

7. The electric vehicle traction motor (10) according to claim 1 or 2, wherein a fluid sealing ring (81) is provided radially on the inner side of the fiber composite (52) at at least one longitudinal end of the sealing tube (50; 50'; 50”).

8. The electric vehicle traction motor (10) according to claim 3, wherein the clamping assembly (160) has an outer clamping ring (162) and an inner clamping ring (162”), wherein the relevant end regions of the fiber composite (52) are radially clamped between the outer clamping ring (162) and the inner clamping ring (162”).

9. The electric vehicle traction motor (10) according to claim 2, wherein a clamping ring seal (80) is arranged between the axial clamping ring (72; 172) and the guide flange (12) of the motor housing (11).

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