Axle arrangement and motor vehicle having axle arrangement

Abstract

The invention relates to a shaft arrangement (10), which is designed to be coupled to a rotor shaft (102) of an electric machine (100) of a motor vehicle (K), comprising: a hollow shaft (20), which extends in the axial extension direction (X) thereof with a through-hole (22) for conducting a fluid for fluid exchange with the rotor shaft (102); and a shaft ground plane which is arranged on the hollow shaft (20) and which is designed to come into contact with the ground element (110) in order to discharge a current generated during operation of the electric machine (100) via the hollow shaft (20) in the direction of the housing (104). According to the invention, the shaft arrangement (10) has a tube insert (40) accommodated in the through-hole (22), which tube insert has a through-hole (42) having an inner diameter (I) that is smaller than a first inner diameter (I1) of the through-hole (22), and which tube insert is designed to form, together with a hollow shaft wall (38) of the hollow shaft (20), a step (70) in the through-hole (22) that impedes a return flow of the fluid. A further aspect of the invention relates to a motor vehicle (K) having such an axle arrangement (10).

Description

Technical Field

[0001] The present invention relates to a shaft device configured to be coupled to a rotor shaft of a motor vehicle. Another aspect of the present invention relates to a motor vehicle having the shaft device. Background Art

[0002] Such a shaft device can be used, on the one hand, to conduct a fluid, for example, a fluid for cooling and / or lubrication, and on the other hand, to conduct an electric current through a shaft grounding device, as mentioned, for example, in DE102021204098A1. From this publication, a device for electrically coupling a rotatably supported shaft to a component of a drive system is known, the shaft being a component of at least a partially electrical drive system. The device includes a first coupling unit formed of a conductive material and rotatably fixable or fixed together on the shaft. In addition, the device includes a second coupling unit formed of a conductive material and fixable relative to the shaft and fixed on the component in the drive system. In the installed state of the device (in which the first coupling unit is fixed on the shaft and the second coupling unit is fixed relative to the shaft and fixed on the component in the drive system), capacitive coupling can be generated between the first coupling unit and the second coupling unit through the gap therebetween. Summary of the Invention

[0003] The object of the present invention is to provide a shaft device of the type described at the beginning, which contributes to the reliable and energy-saving operation of a motor vehicle.

[0004] This object is solved by a shaft device having the features of claim 1 and by a motor vehicle having the features of claim 8. Advantageous designs with suitable expansions of the present invention are given in the dependent claims.

[0005] A first aspect of the present invention relates to a shaft device configured to be coupled to a rotor shaft of a motor vehicle, the shaft device including a hollow shaft having a through hole extending along an axial extension direction of the hollow shaft for conducting a fluid for fluid exchange with the rotor shaft; and including a shaft grounding surface provided on the hollow shaft, the shaft grounding surface being configured to contact a grounding element so as to conduct an electric current generated during motor operation through the hollow shaft in the direction of the housing. The housing can in particular be assigned to the motor.

[0006] According to the provisions of the present invention, the shaft device has a pipe insert accommodated in a through hole. The pipe insert has a through hole with an inner diameter smaller than the first inner diameter of the through hole, and the pipe insert is configured to form a step together with the hollow shaft wall of the hollow shaft in the through hole to prevent fluid from flowing back. This is advantageous because by the step that prevents fluid from flowing back, it can be ensured that even when the hollow shaft rotates during motor operation, a sufficient amount of fluid can be ensured, especially in the design where the step is rotationally symmetric about the rotation axis extending axially along the hollow shaft. The grounding element can advantageously be configured as a shaft grounding pin. Therefore (contrary to, for example, a disc-shaped or annular grounding element), this design has particularly high flexibility in the arrangement of the grounding element.

[0007] In an advantageous expansion scheme of the present invention, the pipe insert has a hollow tube region and a support region. The through hole extends through the hollow tube region. The hollow tube region is supported on the hollow shaft wall by the support region and is spaced apart from the hollow shaft wall. This is advantageous because through the hollow tube region and the support region, a particularly demand-compliant, especially weight-reducing design of the pipe insert can be achieved. Thus, for example, through the support region, linear or point-shaped support can be achieved on the hollow shaft wall, and the support region can act as a spacer retainer. Between the hollow tube region and the hollow shaft wall, an air gap can extend along the axial extension direction of the support region. Through this air gap, for example, fluid leakage occurring during motor operation can be discharged.

[0008] In another advantageous expansion scheme of the present invention, the support region has at least two ribs, and the ribs are at least mainly oriented along the axial extension direction. This is advantageous because through the at least two ribs, sufficient positional fixation can be ensured while the weight of the support region is relatively light. In addition, through the at least two ribs, it can be ensured in a simple manner that the air gap remains the same size even when the shaft device rotates. Depending on the number of ribs, although the air gap can be divided into multiple air gap segments on the circumferential side, the air gap is still large enough to reliably discharge the leakage.

[0009] In another advantageous expansion scheme of the present invention, the at least two ribs extend at least partially spirally between the hollow tube region and the hollow shaft wall. This is advantageous because through the spiral design of the at least two ribs, the fluid leakage between the hollow tube region and the hollow shaft wall that may occur during motor operation due to the rotation of the hollow shaft and the pipe insert together can be better discharged. In other words, the at least partial spiral of the at least two ribs can promote the discharge of the leakage from the gap between the hollow tube region and the hollow shaft wall.

[0010] In a further advantageous development of the invention, the hollow shaft is made of a metallic material and the tube insert is made of plastic. This advantageously constitutes a particularly desirable material combination by means of which weight can be saved in particular.

[0011] In a further advantageous development of the invention, the hollow shaft comprises a first hollow shaft region and a second hollow shaft region connected to the first hollow shaft region, in which first hollow shaft region the through-hole has a first inner diameter, and in which second hollow shaft region the through-hole has a second inner diameter which is larger than the first inner diameter, and the tube insert is received in the second hollow shaft region. This is advantageous because a rotationally symmetric grading of the through-hole can be achieved by means of the different first and second inner diameters of the respective hollow shaft regions, which grading enables the tube insert to be installed particularly simply in the through-hole.

[0012] In a further advantageous development of the invention, the tube insert has at least one locking element by means of which the tube insert is locked to the hollow shaft and is prevented from slipping out of the hollow shaft in the axial extension direction. By means of the locking element, a particularly simple and reliable positioning of the tube insert on the hollow shaft, in particular on the hollow shaft wall, can be achieved in an advantageous manner.

[0013] A second aspect of the invention relates to a motor vehicle comprising a shaft device according to the first aspect of the invention, wherein the rotor shaft of the electric motor is coupled to the hollow shaft of the shaft device for fluid exchange and the grounding element is in contact with the shaft ground surface. This enables reliable and energy-saving operation of the motor vehicle.

[0014] The preferred embodiments and their advantages mentioned with respect to one of the aspects apply correspondingly to the respective other aspects of the invention, and vice versa.

[0015] The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the drawings and / or shown individually in the drawings can be used not only in the respectively given combinations, but also in other combinations or individually, without departing from the scope of the invention.

[0016] Other advantages, features and details of the invention result from the claims, the following description of the preferred embodiments and the figures. Description of the drawings

[0017] The invention is now explained again with the aid of a specific embodiment. The drawings are as follows:

[0018] Figure 1Perspective sectional view showing a variant of the shaft device, which is configured to be coupled to the rotor shaft of a schematically shown electric motor of a motor vehicle also shown schematically. The shaft device has a hollow shaft, and a through hole extends along the axial extension direction of the hollow shaft for guiding a fluid to effect a fluid exchange with the rotor shaft. The shaft device has a shaft grounding surface provided on the hollow shaft, which is configured to contact a grounding element so as to conduct the current generated during the operation of the motor in the direction of the housing via the hollow shaft. The shaft device has a pipe insert accommodated in the through hole. The pipe insert has a through hole with an inner diameter smaller than the first inner diameter of the through hole, and the pipe insert is configured to form a step together with the hollow shaft wall of the hollow shaft in the through hole to prevent the fluid from flowing back;

[0019] Figure 2 Perspective view showing a first variant of the pipe insert, which shows a plurality of straight ribs that are at least mainly oriented along the axial extension direction;

[0020] Figure 3 Perspective view showing a second variant of the pipe insert, wherein the ribs are at least partially helically configured; and

[0021] Figure 4 Detail view showing the locking element of the pipe insert, by which the pipe insert is locked to the hollow shaft and is prevented from slipping out of the hollow shaft along the axial extension direction. Detailed implementation

[0022] Figure 1 A motor vehicle K with a shaft device 10 shown in a perspective sectional view is generally shown. The shaft device is coupled to the rotor shaft 102 of the electric motor 100 of the motor vehicle K. The shaft device 10 has a hollow shaft 20, which can be coupled to the rotor shaft 102, for example, to transmit torque through spline teeth, as Figure 1 exemplarily shown therein.

[0023] The hollow shaft may have a toothing shown in Figure 1 but not provided with a reference numeral, by which other currently unshown drive elements of the motor vehicle K can be driven.

[0024] The hollow shaft 20 has a through hole 22, which extends along the Figure 1 axial extension direction X indicated by an arrow in Figure 1 Therein. The axial extension direction X extends along the Figure 1is indicated by an arrow. The arrow tip of this arrow also gives the flow direction of the fluid flow 12 here. For the sake of clarity, other pipeline components of the motor vehicle K that guide the fluid flow 12 to the hollow shaft 20 are not shown.

[0025] On one end face of the hollow shaft 20, the hollow shaft has an axially contacting surface 21 that is currently oriented perpendicular to the axial extension direction X, and the axially contacting surface contacts the grounding element 110. Figure 1 The grounding element 110, which is also generally shown in, can be configured as an axial grounding pin, for example. Through the axially contacting surface 21 and the grounding element 110, the current generated during the operation of the electric machine 100 can be led out from the hollow shaft 20 towards the housing 104. The housing 104 can be assigned to the electric machine 100 and surround the shaft device 10, for example.

[0026] A pipe insert 40 of the shaft device 10 is accommodated in the through-hole 22, and the pipe insert has a through-hole 42. The hollow shaft 20 is made of a metallic material such as steel, while the pipe insert 40 can be made of plastic for weight reasons.

[0027] The hollow shaft 20 includes a first hollow shaft region 24 in which the through-hole 22 has a first inner diameter I1. In addition, the hollow shaft 20 includes a second hollow shaft region 34 directly connected to the first hollow shaft region 24, in which the through-hole 22 has a second inner diameter I2 that is larger than the first inner diameter 11. The pipe insert 40 is accommodated in the second hollow shaft region 34, as Figure 1 can be seen. In addition, a tooth part without a reference numeral is also assigned to the second hollow shaft region 34, while the spline teeth for coupling the hollow shaft 20 to the rotor shaft 102 are assigned to the first hollow shaft region 24.

[0028] The through-hole 42 has an inner diameter I that is smaller than the two inner diameters I1 and I2 of the through-hole 22. The pipe insert 40 and the hollow shaft wall 38 of the hollow shaft 20 thus form a step 70 in the through-hole 22 that hinders the backflow of the fluid flow 12.

[0029] According to Figure 2 and Figure 3 it can be seen that the pipe insert 40 generally has a hollow tube region 44, that is, in other words, a region configured as a hollow tube. The hollow tube can also be called a hollow cylinder. In addition, the pipe insert 40 has a support region 50 through which the hollow tube region 44 is supported on the hollow shaft wall 38 and spaced apart from the hollow shaft wall 38.

[0030] The support region 50 currently has three ribs 52, 54, and 56 evenly distributed on the circumferential side of the hollow tube region 44, and these ribs are Figure 2 oriented parallel to the axial extension direction X in the shown variant. In contrast, in Figure 3In the illustrated variant, the respective ribs 52, 54, 56, although also mainly oriented along the axial extension direction X, are at least locally helically configured and thus locally helically enclose the hollow tube region 44. In Figure 3 the illustrated variant of the tube insert 40, the ribs 52, 54, 56 extend at least locally helically between the hollow tube region 44 and the hollow shaft wall 38. The expression "at least mainly" within the scope of the present disclosure can be understood to mean that the ribs 52, 54, 56 mainly, i.e., on the main part of their spatial extension, extend along the axial extension direction X, which applies to Figure 2 or Figure 3 the two variants shown in

[0031] Figure 4 A partial schematic view shows an alternative design of the tube insert 40, which can be used for all variants of the tube insert 40. In this design, the tube insert 40 has a locking element 60 by which the tube insert 40 is locked to the hollow shaft 20 and is prevented from slipping out of the hollow shaft 20 along the axial extension direction X. For this purpose, the locking element 60 engages in a notch 36, which, for example, can extend along the hollow shaft wall 38 as an annular groove around the rotation axis R.

[0032] On the one hand, the shaft device 10 enables the guiding of the fluid flow 12 through the hollow shaft 20, wherein the step 70 prevents or at least impedes the fluid from flowing back. By means of the tube insert 40, which is preferably made of plastic, the shaft device 10 can be constructed particularly lightly. In the hollow shaft elements known from the prior art, the tube insert 40 is dispensed with and the different diameters (i.e., the inner diameter I and the first inner diameter I1) are provided only by the metal tube wall, while in the current shaft device 10, the tube insert 40 enables a relatively high weight reduction and thus avoids additional costs, high weight, and increased resource consumption.

[0033] Through the pipe insert 40, the through-hole 22 with the first inner diameter I1 and the second inner diameter I2 can be designed only considering the required stiffness, strength, natural frequency, and the requirements of the external interface with the hollow shaft 20. Thus, for example, rolling bearings, sliding bearings, gears, or toothed rings connected to the hollow shaft 20 can be reliably used without having to design the hollow shaft 20 to be too heavy here. The inner diameter I1 is currently provided by the pipe insert 40, which can also be referred to as a plastic insert. The pipe insert 40 can not only enable the guiding of the fluid through at least one region, namely the second hollow shaft region 34 of the hollow shaft 20, but also helps reduce (hinder) the fluid backflow with the aid of the step 70 and supports on the hollow shaft wall 38. The support region 50 (which can also be referred to as a support geometry) can enable the discharge of fluid leakage from the air gap 39 formed between the hollow pipe region 44 and the hollow shaft wall 38, and the support region 50 extends through the air gap. Advantageously, the leakage can be guided to the shaft grounding surface 21 and lubrication of the sliding contact between the shaft grounding surface 21 and the grounding element 110 can be ensured there, thereby improving the durability of the grounding element 110 and thus the reliability.

[0034] When the shaft device 10 rotates based on the operation of the motor 100, the support region 50 allows the leakage to be discharged from the air gap 39. In the helical design of the support region 50 or the ribs 52, 54, 56, the fluid can even be advantageously discharged from the air gap 39 rotationally. In other words, the ribs 52, 54, 56 can assist in the discharge of the fluid from the air gap 39, especially when the ribs extend at least partially helically in the air gap 39, that is, between the hollow pipe region 44 and the hollow shaft wall 38. Thus, possible dead volumes and / or possible accumulations of dirt elements (such as particles, fibers, etc.) in the air gap 39 can be avoided.

[0035] List of reference numerals

[0036] 10 Shaft device

[0037] 12 Fluid flow

[0038] 20 Hollow shaft

[0039] 21 Shaft grounding surface

[0040] 22 Through-hole

[0041] 24 First hollow shaft region

[0042] 34 Second hollow shaft region

[0043] 36 Notch

[0044] 38 Hollow shaft wall

[0045] 39 Air gap

[0046] 40 Pipe insert

[0047] 42 Through-hole

[0048] 44 Hollow tube region

[0049] 50 Support region

[0050] 52 Rib

[0051] 54 Rib

[0052] 56 Rib

[0053] 60 Locking element

[0054] 70 Step

[0055] 100 Motor

[0056] 102 Rotor shaft

[0057] 104 Housing

[0058] 110 Grounding element

[0059] I Inner diameter

[0060] I1 First inner diameter

[0061] I2 Second inner diameter

[0062] K Motor vehicle

[0063] R Axis of rotation

[0064] X Axial extension direction

Claims

1. A shaft device (10) configured to be coupled to a rotor shaft (102) of an electric machine (100) of a motor vehicle (K), the shaft device comprising a hollow shaft (20) and a shaft contact surface provided on the hollow shaft (20), a through hole (22) extending along the axial extension direction (X) of the hollow shaft for guiding a fluid to effect a fluid exchange with the rotor shaft (102), the shaft contact surface being configured to contact a grounding element (110) so as to conduct the current generated during operation of the electric machine (100) through the hollow shaft (20) towards the housing (104), characterized in that the shaft device (10) has a pipe insert (40) received in the through hole (22), the pipe insert having a through hole (42) with an inner diameter (I) smaller than a first inner diameter (I1) of the through hole (22), and the pipe insert being configured to form, together with the hollow shaft wall (38) of the hollow shaft (20), a step (70) in the through hole (22) that impedes fluid backflow.

2. The shaft device (10) according to claim 1, characterized in that, The pipe insert (40) has a hollow pipe region (44) through which the through hole (42) extends, and the pipe insert has a support region (50) through which the hollow pipe region (44) is supported on and spaced from the hollow shaft wall (38).

3. The shaft device (10) according to claim 2, characterized in that, The support region (50) has at least two ribs (52, 54, 56) that are at least mainly oriented along the axial extension direction (X).

4. The shaft device (10) according to claim 3, characterized in that, The at least two ribs (52, 54, 56) extend at least partially helically between the hollow pipe region (44) and the hollow shaft wall (38).

5. The shaft device (10) according to any one of the preceding claims, characterized in that, The hollow shaft (20) is made of a metallic material and the pipe insert (40) is made of plastic.

6. The shaft device (10) according to any one of the preceding claims, characterized in that, The hollow shaft (20) includes a first hollow shaft region (24) and a second hollow shaft region (34) connected to the first hollow shaft region (24), the through hole (22) having a first inner diameter (I1) in the first hollow shaft region and a second inner diameter (I2) larger than the first inner diameter (I1) in the second hollow shaft region, the pipe insert (40) being received in the second hollow shaft region (34).

7. The shaft device (10) according to any one of the preceding claims, characterized in that, The pipe insert (40) has at least one locking element (60) through which the pipe insert (40) is locked to the hollow shaft (20) and is prevented from slipping out of the hollow shaft (20) along the axial extension direction (X).

8. A motor vehicle (K) comprising a shaft device (10) according to any one of the preceding claims, wherein, The rotor shaft (102) of the electric machine (100) is coupled to the hollow shaft (20) of the shaft device (10) for fluid exchange, and the grounding element (110) contacts the shaft contact surface (21).

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