阅读说明：本技术 用于电动驱动器的滑动离合器装置 (Slip clutch device for an electric drive ) 是由 M·施奈德 于 2019-09-03 设计创作，主要内容包括：本发明涉及一种用于电动驱动器(2)的滑动离合器装置(1),其具有至少以下部件：-输入端(3)；-输出端(4),其中所述输入端(3)和所述输出端(4)可围绕共同的旋转轴(5)旋转；-电绝缘元件(6),借由所述电绝缘元件(6)防止所述输入端(3)和所述输出端(4)之间出现电击穿放电线路；以及-滑动离合器(7),所述滑动离合器以限制扭矩的方式将所述输入端(3)和所述输出端(4)相互连接,其中所述滑动离合器(7)包括摩擦片(8)和对立的摩擦板(9),所述摩擦片和所述对立的摩擦板在接触区(10)中以摩擦扭矩传递的方式相互压靠,并且其中所述滑动离合器(7)包括所述绝缘元件(6)。根据本发明,所述滑动离合器装置(1)具体特征在于,所述摩擦片(8)和/或所述摩擦板(9)至少在径向延伸地覆盖所述接触区(10)的绝缘区(11)中由电绝缘材料形成,其中所述绝缘区(11)设计为用于在径向方向上传递扭矩的承载结构。根据本发明所述的滑动离合器装置具有成本低廉的结构,所述结构对安装空间要求低且集成有击穿放电绝缘功能。(The invention relates to a slip clutch device (1) for an electric drive (2), comprising at least the following components: -an input (3); -an output (4), wherein the input (3) and the output (4) are rotatable about a common axis of rotation (5); -an electrical insulation element (6), by means of which electrical breakdown discharge lines between the input (3) and the output (4) are prevented by means of the electrical insulation element (6); and-a slip clutch (7) which connects the input (3) and the output (4) to one another in a torque-limiting manner, wherein the slip clutch (7) comprises a friction plate (8) and a counter friction plate (9) which are pressed against one another in a contact region (10) in a friction torque-transmitting manner, and wherein the slip clutch (7) comprises the insulating element (6). According to the invention, the slip clutch device (1) is particularly characterized in that the friction plates (8) and/or the friction plates (9) are formed from an electrically insulating material at least in an insulating region (11) which extends radially over the contact region (10), wherein the insulating region (11) is designed as a load-bearing structure for transmitting torque in the radial direction. The slip clutch device according to the invention has a cost-effective construction which has low requirements for installation space and is integrated with a breakdown voltage insulation function.)

1. A slip-clutch device (1) for an electric drive (2) has at least the following components:

-an input (3);

-an output (4), wherein the input (3) and the output (4) are rotatable about a common axis of rotation (5);

-an electrical insulation element (6) by means of which an electrical breakdown discharge line between the input (3) and the output (4) is prevented; and

-a slip clutch (7) which connects the input (3) and the output (4) to one another in a torque-limiting manner, wherein the slip clutch (7) comprises a friction plate (8) and a counter friction plate (9) which are pressed against one another in a contact region (10) in a frictionally engaged torque-transmitting manner, and wherein the slip clutch (7) comprises the insulating element (6),

it is characterized in that the preparation method is characterized in that,

the friction lining (8) and/or the friction plate (9) is formed from an electrically insulating material at least in an insulating region (11) that extends radially over the contact region (10), wherein the insulating region (11) is designed as a load-bearing structure for transmitting torque in the radial direction.

2. The slip clutch device (1) according to claim 1, wherein the slip clutch (7) for transmitting torque comprises only the friction plates (8) and the friction plates (9).

3. The slip clutch device (1) according to claim 1 or 2, wherein the friction plates (8) and/or the friction plates (9) are formed entirely of an electrically insulating material.

4. A sliding clutch device (1) according to one of the preceding claims, wherein a disc spring (12) acting axially is provided for pressing the friction plates (8) and the friction plates (9).

5. A slip-clutch device (1) according to any one of the preceding claims, wherein the friction plate (8) is formed integrally with the input end (3) formed as an input hub and/or the friction plate (9) is formed integrally with the output end (4) formed as an output hub.

6. Slip clutch device (1) according to one of the preceding claims, wherein the friction plates (8) or the friction plates (9) are connected to the input (3) or the output (4) by means of a form-fitting connection, preferably by means of a spline (13), axially displaceably in a torsionally rigid manner, wherein the disc spring (12) according to claim 3 is preferably axially supported on the input (3) or the output (4).

7. A drive train (14) having: electric drive (2) with drive shaft (15), transmission (16) with transmission input shaft (17) and transmission output shaft (18) and slip clutch device (1) according to one of the preceding claims, wherein the drive shaft (15) is connected to the transmission input shaft (17) in a torque-transmitting manner by means of the slip clutch (7) overcoming an electrical breakdown discharge line and preventing overload torques, so that torques with improved and/or variable transmission ratios can be transmitted via the transmission output shaft (18) to consumers (20, 21).

8. A motor vehicle (19) comprising at least one consumer (20, 21) drivable by means of a drive train (14) according to claim 7.

Technical Field

The invention relates to a slip clutch device for an electric drive, a drive train having such a slip clutch device and a motor vehicle having such a drive train.

Background

Modern motors driving vehicles are controlled by frequency converters. High clock frequencies in the range of 20kHz (20 kHz) or higher are used to obtain an almost sinusoidal current profile on the motor. Due to the high clock frequency and the short switching times, the capacitances between the housing and the rotor, between the housing and the winding and between the winding and the rotor in the machine can no longer be ignored. This capacitive coupling can create a voltage between the motor housing and the rotor or shaft. When bearings with metallic rolling elements are used, such tensions arise at the bearing lubrication gaps. If the bearing voltage exceeds the breakdown discharge voltage of the lubricant film, an electrical breakdown discharge occurs. This situation can lead to spark erosion and can lead to bearing damage and even failure. In modern motor vehicle electric drives, for example in the motor shaft, the electric motor is directly flanged to the transmission or even integrated into the transmission housing. Thus, there is an electrical connection from the motor housing to the transmission housing. Since the motor shaft is directly connected to the input shaft of the transmission, there is also an electrical connection here, so that parasitic currents also pass through the transmission and the bearings located there and the rolling contacts in the tooth parts of the respective gears. Here, the current can also cause spark erosion of the bearings and gear teeth.

In contrast to conventional internal combustion engine-driven vehicles, electric vehicles do not require a friction clutch as a starting element for pure driving operation. In addition to the function of transmitting the drive torque from the drive to the transmission, such friction clutches also have the advantage that the introduction of a jerking torque into the drive train by the wheels is limited, since the clutch slips in the event of an overload. Slip clutches are also commonly used in hybrid vehicles to protect the driveline. However, there is also an impact torque or an overload torque introduced into the drive train by the wheels in the electric vehicle. Therefore, the entire drive train must be designed for high loads, which may exceed the driving torque by a factor of 3 to 4, or the load must be limited to protect the drive train.

The subsequently published patent document DE 102018115083 a1 discloses a motor vehicle drive train and an electrically insulated sliding clutch for a motor vehicle drive train. Herein, it is proposed, among other things, to use a multi-plate clutch having an inner plate carrier and an outer plate carrier as a slip clutch, wherein an insulating sheet is arranged between the outer toothed output plate carrier and the output hub, i.e. at the shaft connection of the transmission input shaft, the slip clutch. The slip clutch is shown in fig. 1. Although many standard components can be used here and strict installation space requirements can be complied with, the construction is complicated and therefore costly.

Disclosure of Invention

It is therefore an object of the present invention to at least partially overcome the disadvantages known from the prior art. The features according to the invention emerge from the independent claims, advantageous embodiments of which are shown in the dependent claims. The features of the claims may be combined in any technically reasonable manner and the explanations in the following description and the features in the drawings, including additional embodiments of the invention, may also be used for this purpose.

The invention relates to a slip clutch for an electric drive, comprising:

-an input terminal;

-an output; wherein the input and output ends are rotatable about a common axis of rotation;

-an electrical insulation element by means of which an electrical breakdown discharge line between the input and the output is prevented; and

a slip clutch, which connects the input and the output to one another in a torque-limiting manner, wherein the slip clutch comprises a friction plate and an anti-friction plate, which are pressed against one another in a friction-torque-transmitting manner in a contact region, and wherein the slip clutch comprises an insulating element.

The main feature of the slip clutch device is that the friction plates and/or friction plates are made of an electrically insulating material, at least in an insulating region which covers the contact region in a radially extending manner, wherein the insulating region is designed as a bearing structure for transmitting torque in the radial direction.

In the following, reference is made to the mentioned rotating shaft if the axial direction, the radial direction or the circumferential direction and the corresponding terms are used without further explicit indication.

It should be noted that the slip clutch device proposed herein is just put into a narrow installation space between the electric motor and the transmission case, for example, as an insulating member having an overload protection function in a motor vehicle. In the radial direction, this mounting space generally corresponds approximately to the rotor diameter and is, for example, less than 200mm (200 mm). For example, in the axial direction, when the motor is directly fixed to the transmission, the maximum clearance between the motor bearing and the seal or transmission input bearing is 15mm (15 mm) to 30 mm. Instead of a conventional continuously connected shaft, which is divided into two partial shafts, for example the drive shaft of an electric drive and the transmission input shaft of a transmission, the slip clutch device is intended to connect the electric drive and the transmission. A slip-clutch device may be used, for example, as described in the subsequently published patent document DE 102018115083 a 1.

Suitable electric drives are arranged axially parallel, coaxially (with the drive shaft as a hollow shaft) or transversely to the output shaft and are connected in a torque-transmitting manner to the output shaft via a transmission. The transmission is a step-up transmission, such as a simple gear stage or transmission or a continuously variable belt transmission, and/or a differential for distributing the applied torque based on demand. For example, an electric drive can be used on the rear axle or front axle of a motor vehicle, i.e. as a single drive (electric vehicle), as an additional drive in addition to another drive (e.g. an internal combustion engine), or as a starter generator to support and/or start the internal combustion engine and to convert mechanical energy into electrical energy, for example by means of recovery of braking energy.

The slip clutch device comprises an input via which a torque can be input and preferably, conversely, a torque can also be received in the direction of the electric drive. The input may be connected to an electromotive drive. If the input is part of a separate assembly of the slip clutch or a separate (consistently preassembled) assembly, it is designed as an input hub. The input hub can be connected directly or indirectly to the drive shaft of the electric drive in a form-fitting manner (for example by means of a key slot or by means of a bolt rivet) and/or in a force-fitting manner (for example by means of a threaded connection) in a torque-transmitting manner, preferably in a torque-proof manner. In an alternative embodiment, the input is a component of the slip clutch itself, such as the friction plate itself.

The slip clutch device also comprises an output via which a torque can be output and preferably can be received in the direction of the electric drive. The output may be connected to a drive shaft. If the output end is part of a separate assembly or a separate (consistently preassembled) assembly of the slip clutch, it is designed as the output hub. The output shaft hub can be connected directly or indirectly to a transmission shaft of the transmission in a form-fitting manner (for example by means of a key slot or by means of a bolt rivet) and/or in a force-fitting manner (for example by means of a threaded connection) in a torque-transmitting manner, preferably in a rotationally fixed manner. In an alternative embodiment, the output is a component of the sliding clutch itself, such as the friction plate itself.

The input end (e.g., input hub) and the output end (e.g., output hub) are rotatable about a common axis of rotation with a tolerance range within an axial offset of less than 1mm (1 mm), preferably up to 0.7mm (700 microns).

A slipping clutch interconnects the input and output in a torque-transmitting manner, wherein the maximum transmittable torque is limited to a maximum set point, for example 10% (ten percent) to 25% above the maximum torque that an electric drive can produce (demand). This means that the connection between the input and the output is torque limited. Such a limited torque transmission takes place, for example, in the form of a brake having a brake disk and brake pads, with friction plates on the input side, i.e. connected in a torque-transmitting, preferably rotationally fixed manner to the input side, and with friction plates on the output side, i.e. connected in a torque-transmitting, preferably rotationally fixed manner to the output side. The friction plate and/or the friction plate are axially movable, preferably detachable, such that the (axial) pressure causes the contact areas of the friction plate and the friction plate to abut against each other, thereby forming a frictional connection by means of the contact areas. Therefore, when pressure is applied, the friction plates and the friction plates are pressed against each other in a frictional engagement, torque transmission manner. At least during use, the pressure can be applied in a defined manner from the outside by means of pretensioning. The pressure force is generated, for example, by a compression spring mounted in a tensioned manner in the embedding space. If the torque applied during operation is greater than the maximum set value, the axially movable friction pair, i.e. the friction plate and/or the friction plate, is lifted against the applied pressure with an axial stroke, so that the transmittable torque is reduced. Thus, the electric drive is protected from overload torque from a maximum set value higher than the output, and the transmission is protected from impact torque from a maximum set value higher than the motor.

A slip clutch is proposed which comprises an electrically insulating element, wherein an electrical flashover discharge path between the input and the output is prevented by means of the electrically insulating element. For this purpose, the insulating element is configured such that its own impedance and the distance between the (better) electrically conductive adjacent parts of the slip clutch are so large that the expected voltage potential does not cause an electrical breakdown discharge. When used for the electric drive of a motor vehicle, the desired voltage potential is, for example, 2kV (2000 volts) to 8kV, preferably 3kV to 6 kV. It follows that an air gap or distance of about 1mm (1 mm) to 4mm, for example 2mm to 3mm, is required in an air environment.

Proposed is a friction plate and/or friction plate of a slip clutch, which comprises an insulating region made of an electrically insulating material, for example ceramic or electrically non-conductive (for example fiber-reinforced) plastic. In order to satisfy the above conditions, the insulating region is formed with an extension portion that far exceeds the contact region, thereby reliably preventing an electrical breakdown discharge from passing through the insulating material and air. At the same time, the insulation region forms a contact region or bearing structure for the friction lining, wherein preferably the friction lining is (only) an electrically non-conductive. The insulating region is configured as a bearing structure for transmitting torque in a radial direction. The insulation region is thus configured for a sufficiently high torque transmission which is sufficiently rigid in terms of vibrations and (low) dissipation losses. Conventional rubber connections, which lead to high dissipation losses in the drive train subjected to vibrations and changing the direction of the torque, can therefore be excluded from being used as an insulation zone, since the slip clutch must be configured for changing the torque, for example, as is required in mobile devices such as motor vehicles. In this context, it should be noted that slipping of the slipping clutch caused by overload torque or impact torque is a rare operating state, for which the aim is to transmit torque with as little loss as possible. This can be achieved by the present slip clutch device and the rigid insulation zone.

The insulating sheet disclosed in the subsequently published patent document DE 102018115083 a1 transmits torque only in the circumferential direction or via (axial) shear. The large number of friction linings in the plate pack are usually made of electrically insulating material, but are also designed to transmit torque only in the circumferential direction or by (axial) shear. In addition, the air gap or distance between two adjacent plates made of an electrically conductive material (e.g. steel) is too small to prevent an electrical breakdown discharge. In addition, the friction lining forms (i.e., defines) the contact area, and thus does not form an insulating region that extends beyond the contact area. Therefore, the conventional plate group disclosed in the later-disclosed cited document is designed not to have an insulating property (sufficient to prevent an electrical breakdown discharge).

The advantage of the slip clutch device proposed here is that a simple, i.e. inexpensive, construction can be achieved, and only a small installation space is required. In addition, it enables a longer service life and an overall protection against spark-over, i.e. no spark-over in the case of the intermediate component. This measure also eliminates the need for (relative) grounding of the intermediate part, in particular by means of sliding contacts, or a correspondingly robust design of such an intermediate element against spark erosion.

According to an advantageous embodiment of the slip clutch device, the slip clutch for transmitting torque comprises only friction plates and friction plates.

As an alternative embodiment presented herein, a plurality of friction plates and/or friction plates are provided for transmitting torque, wherein each friction plate and/or friction plate is configured as described above to prevent electrical breakdown discharges. An advantage of this embodiment is that with this friction pack having a plurality of friction pairs in a small radial installation space, a plurality of torques (corresponding approximately to the number of friction pairs) can be transmitted with (approximately) the same pressure.

According to one embodiment, a slip clutch for transmitting torque comprises only friction plates and friction plates as described above, i.e. only a single friction plate and a single friction plate, which form a single (common) friction pair on the contact area. The above-described construction is particularly simple and requires only little axial installation space. By means of the feasible (thick) design of the friction plates and friction plates, high pressures can be applied, whereby high torques can be transmitted by means of frictional engagement. Since this is a passive slipping clutch, the pressure can be designed to be significantly higher than that of an actively opening and closing friction clutch, for example by means of which the transmission ratio is changed.

According to an advantageous embodiment of the slip-clutch device, the friction plates and/or friction plates are completely made of an electrically insulating material.

In this embodiment, the production of the friction plates or friction plates from an electrically insulating material is particularly simple, for example by means of injection molding (for example 1K) in the case of plastics or sintering in the case of ceramics. In addition, due to the mechanical requirements and the resulting thickness or (radial) spread of the components, the risk of arcing from one conductive component of the slip clutch or slip clutch device to the other is essentially eliminated.

According to an advantageous embodiment of the sliding clutch device, an axially acting disk spring is provided for pressing the friction plates and friction plates.

The coil springs require a small axial space to generate or maintain a very high axial force. In addition, given a suitable prestress, the gradient of the spring characteristic curve is small, which results in only a slight increase in force during the axial stroke in which the friction plates or friction plates are pressed. This means that the pressure-receiving components for normal operation, i.e. the frictionally engaged torque-transmitting devices, can be designed to approach their respective load limits. For example, in the case of an axial stroke to which an overload torque is applied, the deflection of the friction surface (since the force does not increase very sharply) does not increase excessively, so that in this state, a reduction in torque and/or strong grinding of the line contact between the friction plate and the friction plate due to excessive bending is prevented.

According to an advantageous embodiment of the slip-clutch device, the friction plates are formed integrally with the input end formed as an input hub and/or the friction plates are formed integrally with the output end formed as an output hub.

In this embodiment, the number of components of the slip-clutch device is significantly reduced compared to the subsequently disclosed embodiment according to patent document DE 102018115083 a 1. Overall, the structure is simpler and the cost is lower. Where the friction plates are of unitary design with the input hub and/or the friction plates are of unitary design with the output hub, it is not excluded to form the friction linings separately, for example. However, the radial extension of the friction plates to the input hub and/or the radial extension of the friction plates to the output hub are designed as a single unit, i.e., the radial transfer of torque is accomplished by the transfer of the integral friction plates and/or plates to the respective hubs. Preferably, the input hub and/or the output hub comprise a form-fitting connection, particularly preferably by means of (outside or inside) keyways.

According to an advantageous embodiment of the slip clutch device, friction plates or friction plates are connected to the input or output in order to be axially displaced in a rotationally fixed manner by means of a form-fit connection.

In this embodiment, the friction plates are axially fixed and the friction plates are axially movable, e.g. detachable, or the friction plates are axially fixed and the friction plates are axially movable, e.g. detachable. Axially displaceable friction pairs, i.e. friction plates or friction plates, are connected to the respective ends only in a rotationally fixed, form-fitting manner.

In one embodiment, a damper or shock absorber or another element is interposed between the (axially movable) friction pair and the respective hub, i.e. the input shaft hub or the output shaft hub. In this case, the friction pair in question is connected directly to the respective hub in a torsionally fixed manner only. The associated friction pair is only indirectly connected to the respective hub in a torque-transmitting manner. In this case, the end in question cannot be considered identical to the hub, even if the slip-clutch device forms a preassembled assembly.

In one embodiment, the form-fitting connection is a keyway. In one embodiment, the keyways are designed to be inserted into complementary keyways of an input hub or an output hub, wherein the complementary keyways of the hub in question are configured to be connected to a drive shaft or a transmission input shaft.

According to one embodiment, the disc spring is axially supported on the input end or the output end according to the above-described embodiments for pressing the friction plates and the friction plates. In this embodiment, the coil spring is supported within the assembly of the slip-clutch device, so that assembly by the customer is not required. For example, the customer is an assembly worker of an OEM (original equipment manufacturer; in the automotive industry, this means one of the brand manufacturers (generally known by the end consumer)).

In one embodiment, one or more disc springs are arranged between components interconnected in a rotationally fixed manner, for example between the flange of the input hub and the (axially movable) friction plate and/or between the flange of the output hub and the (axially movable) friction plate.

According to another aspect, a drivetrain is disclosed having: an electric drive with a drive shaft, a transmission with a transmission input shaft and a transmission output shaft, and a slip clutch device according to the above-described embodiments, wherein the drive shaft is connected to the transmission input shaft in a torque-transmitting manner by means of a slip clutch which prevents electrical flashovers to the discharge line and prevents overload torques, so that torques with modified and/or variable transmission ratios can be transmitted via the transmission output shaft to the consumers.

The drive train is configured to transmit the torque provided by the electric drive and output via its drive shaft to at least one consumer in a limited manner, i.e. only up to a desired maximum set value. An exemplary consumer end is at least one drive wheel and/or an auxiliary device of the motor vehicle, such as an air conditioning pump. Conversely, inertial energy may also be received from the drive wheels, for example. In the generator mode of the electric drive, the inertial energy is converted into electrical energy by means of the slip clutch device in a torque-limiting manner, i.e. for example the braking energy of the motor vehicle is recovered, i.e. either for direct power supply from the consumer or for power storage. Furthermore, in a preferred embodiment, a plurality of drivers is provided. An example is a hybrid drive consisting of one or more electric drives and at least one internal combustion engine.

The slip clutch device proposed herein is particularly advantageous in order to transmit torque only to a limited extent. The sliding clutch device is compact in the axial direction, so that rotor bearings (conventionally provided) for the rotor of the electric drive can be dispensed with at the sliding clutch end, so that only single roller bearings for the rotor shaft and the transmission input shaft are required at the transmission end. Such roller bearings can also be realized inexpensively, since the slip-clutch device is also a complete insulator against electrical breakdown discharges, for example (pure) metal roller bearings can be used at the transmission end.

According to another aspect, a motor vehicle is proposed, comprising at least one drive wheel which can be driven by means of a drive train according to an embodiment as described above.

At present, the energy storage space of electric vehicles is large, such as lithium batteries, so that the available installation space is small. In addition, most electric vehicles are equipped with an additional internal combustion engine as a hybrid vehicle, for example as a range extender, so that the installation space is further reduced. Therefore, the use of a small-sized slip clutch device is particularly advantageous. Similar problems are associated with the use of slip clutch devices in motor two-wheeled vehicles.

The transmission has a slip clutch device of particularly small dimensions. At the same time, it is inexpensive to produce and low-cost conventional roller bearings can be used on the transmission side.

Drawings

The invention as described above is explained in detail below on the basis of the related art background and with reference to the associated drawings showing preferred embodiments. The invention is in no way limited by the purely schematic drawings, it being noted that the drawings are not dimensionally accurate and are not suitable for defining proportions. Hereinafter, the following description will be given of,

FIG. 1: a slip clutch device with a plate pack is shown;

FIG. 2: showing a slip-clutch device with an integrated insulating element;

FIG. 3: another embodiment of a slip clutch device with an integrated insulator element is shown;

FIG. 4: a drive train in a motor vehicle with a slip clutch device is shown.

Detailed Description

Fig. 1 shows a conventional slip-clutch device 27 in cross section, as described for example in the subsequently published patent document DE 102018115083 a 1. In this respect, for a more thorough understanding of the conventional feedback means 27, reference is made to the more detailed description provided in this document. In the present invention, the drive shaft 15 (shown in phantom) is connected to the transmission input shaft 17 (shown in phantom) via the input 3, which is splined, and the transmission input shaft is connected via the output 4, which is also splined in this embodiment, and is insulated to prevent electrical arcing and limit torque. The torque about the axis of rotation 5 is provided by a plate pack 29 having a plurality of inner plates suspended in a rotationally fixed manner in an inner plate casing 32, which in turn is connected in a rotationally fixed manner to the output 4, and having a plurality of outer plates 33 suspended in a rotationally fixed manner, which in the present invention is in turn connected in a rotationally fixed manner to the input 3. The enclosing springs 35, which are designed as coil springs, press the plates of the plate package 29 with a predetermined pressure. For this purpose, the encapsulation spring 35 is supported on a cover 34, wherein the cover 34 is axially and rotatably fixed to the outer plate casing 33. In order to ensure the insulating function, an insulating sheet 28 is provided on the output terminal 4, via which an inner board outer frame 32 is mechanically connected to the output terminal 4 in a torque-transmitting manner. For this purpose, in the exemplary embodiment shown, rivets (therefore not visible in the figures) are arranged alternately in the circumferential direction, which connect the internal board casing 32 and the insulating sheet 28 or the insulating sheet 28 and the output 4 to one another. In this case, it is necessary to transmit torque by the insulating sheet 28, and the material of the insulating sheet 28 must be selected accordingly. However, the torque is transmitted from the insulating sheet 28 to the adjacent elements (the inner board outer frame 32 and the output terminal 4) only in the circumferential direction by shearing. Further, due to the structure shown in the drawing, a cover insulator 31 is required between the inner plate outer frame 32 and the cover 34. In addition, a shaft insulator 30 is disposed between the drive shaft 15 and the transmission input shaft 17. This embodiment has the advantage that it uses a particularly large number of standard components, so that the conventional slip-clutch device 27 can be produced inexpensively. In principle, the number of plates is arbitrary or, instead of a plate pack, press plates and friction plates can be implemented, for example with friction linings arranged on both sides, and counterplates. Alternatively, the pressure plate may be pressed against the counterplate without a friction plate for torque transmission of the frictional engagement.

In fig. 2, the slip clutch device 1 is shown in a schematic sectional view. Here, the input 3, which is designed as an input hub with (input) key ways 22, and the output 4, which is designed with (output) key ways 23, are connected to each other in a torque-limiting manner around a common axis of rotation 5 and are electrically insulated from each other. As shown in fig. 1, the input 3 and the output 4 are substantially reversible, i.e. the input 3 can also be connected in a rotationally fixed manner to a transmission input shaft 17 (see fig. 1 or 4) and the output can also be connected in a rotationally fixed manner to a drive shaft 15 (see fig. 1 or 4). Further intermediate elements, such as dampers or shock absorbers, may also be inserted.

In the illustrated embodiment, in the slip clutch device 1 according to fig. 2 and according to the (reversible) designation of the input 3 and output 4, the input 3 here optionally has integrated a friction plate 8, which is in frictional engaging contact with a friction plate 9 in a contact region 10, so that a slip clutch is formed. Optionally inserted into the output end keyway 23 of the output end 4 by means of the insulating keyway 13, the friction plate 9 is formed separately from the output end 4 and is axially removable relative to the output end 4 so as to be connected thereto in a torsionally rigid manner. In this embodiment the friction plate 9 forms the insulating element 6 by means of the entire friction plate 9, which in this alternative embodiment is made of an insulating material, for example ceramic.

The torque is transmitted in frictional engagement to the friction plates 9 via the contact regions 10 with the friction plates 8 and is directed in the radial direction towards the key grooves 13, so that the insulating element 6 is designed as a bearing structure. The insulating zone 11 extends both radially outwards and radially inwards (in the present invention to the axis of rotation 5 or over the entire radial extent) and, in the present embodiment, also over the entire axial extent outside the contact zone 10 (optionally). In this embodiment, the shaft insulator 30 required in the embodiment according to fig. 1 can therefore be dispensed with. The cap insulator 31 shown in the embodiment according to fig. 1 is also omitted. For a defined pressure, the invention is equipped with a disc spring 12 which acts between the output 4 (by means of a flange) and the friction plate 9 on the sliding clutch 7, so that torque can be transmitted by means of frictional engagement and is limited to a maximum setpoint between the input 3 and the output 4. It should again be noted that even if the input 3 is connected to the electric drive 2 or its drive shaft 15 (see fig. 4) and the output is connected to the transmission input shaft 17 of the transmission 16 (see fig. 4), torque can be transmitted from the output 4 to the input 3 in the opposite direction, for example for recuperation of brake energy.

For the sake of clarity, fig. 3 shows an almost identical embodiment of the slip-clutch device 1 as shown in fig. 2, wherein reference is made to the description of fig. 2 in this section. In contrast to the exemplary embodiment according to fig. 2, in fig. 3, a separate friction lining 36 is provided on the friction lining 8, wherein the friction lining can be provided additionally or alternatively on the friction plate 9. Whether the friction lining 36 is provided depends on the installation space, the desired pressure and the achievable dimensions of the contact region 10, since friction pairs with a high friction coefficient can be provided, without the material of the friction lining needing to form a bearing structure for the radial transmission of torque. Alternatively or (correspondingly) additionally, a surface structure is provided, for example roughened or corrugated, in order to increase the coefficient of friction in the friction plate and/or friction plate.

Whether or not a friction lining 36 is provided, the insulating zone 11 in the embodiment according to fig. 2 is significantly smaller than the insulating zone 11 in the illustration, so that a highly conductive material, for example steel, can be used radially in the insulating zone. The material of the insulating region 11 is connected to the rest of the friction plate 9 in a form-fitting, force-fitting and/or material-fitting manner. In the present exemplary embodiment, the torque transmitted by the contact region 10 in frictional engagement is also transmitted radially within the insulating region 11 to the inserted toothing 13 of the friction plate 9.

In an advantageous embodiment, a fixing ring 37 is also provided, made of a conventional (highly conductive) material or an insulating material, to prevent the inserted shaft, for example the drive shaft 15 (see fig. 1 or 4), from coming too close to the conductive area of the friction plate 9, or from thermal expansion during operation to come too close to the friction plate 9. In an alternative embodiment, only one zone is connected towards the output 4 or input 3 (in this embodiment on the output), which is made of a highly conductive material, for example only the key 13.

In one embodiment, the friction plate 8 is axially movable and/or the friction plate 9 is axially fixed.

In fig. 4, a drive train 14 is schematically shown, which comprises an electric drive 2 with a drive shaft 15, and also a slip clutch device 1 and a transmission 16 connected in a torque-limiting manner in a motor vehicle 19. In the present embodiment, the drive train 14 is configured to drive the left and right drive wheels 20, 21, which thus form the consumption end. In the embodiment, the drive train 14 is arranged at the rear of the motor vehicle 19 with respect to the longitudinal axis 25, and the cab 24 is arranged at the front. In an embodiment, the electric drive 2 is arranged axially parallel to the (two-part) transmission output shaft 18, and in an embodiment, the electric drive is also aligned with a motor shaft 26 transverse to the longitudinal axis 25. The drive shaft 15 is connected to the transmission input shaft 17 by means of the slip clutch device 1 in a torque-limiting manner, wherein the electric drive 2 is therefore also electrically insulated from the components of the transmission 16 or drive train 14 connected downstream of the slip clutch device 1, i.e. the breakdown discharge voltage due to the accumulated capacitance is prevented. In the embodiment, the transmission 16 is only schematically illustrated as having a (reduction) gear 38 and a (e.g., bevel) differential 39. Thus, the left and right drive wheels 20, 21 can be driven by the electric drive 2 at a (e.g. fixed) reduction ratio according to the torque demand, so that the motor vehicle 19 can move in one direction along the longitudinal axis 25 (at least infinitely small when cornering).

The slip clutch device provided by the invention has a structure with high cost efficiency, low requirement on installation space and integration of the breakdown discharge insulation function.

Description of the reference numerals

1 slip-clutch device 2 electric drive 3 input 4 output 5 rotation shaft 6 insulator 7 slip-clutch 8 friction plate 9 friction plate 10 contact 11 insulator 12 disc 13 friction plate keyway 14 drive shaft 16 transmission 17 transmission input shaft 18 transmission output shaft 19 motor vehicle 20 left drive wheel 21 right drive wheel 22 input end keyway 23 output end keyway 24 cab 25 longitudinal shaft 26 conventional slip-clutch device 28 insulation plate 29 plate 30 shaft insulator 31 insulator 32 outer plate outer frame 33 outer plate outer frame 34 cover 35 packing spring 36 friction lining 37 fixed ring 38 reduction gear 39 differential gear 39