DE102017222005A1 - Electric motor for a vehicle component of a motor vehicle, vehicle component and motor vehicle - Google Patents

Abstract

The invention relates to an electric motor (3) for a vehicle component (2) of a motor vehicle (1), in particular a compressor, comprising a stationary unit (4) having a stator (8) for magnetic field generation and having a rotating unit (5) A rotor (9) rotatably mounted relative to the stator (8) and a rotor shaft (10) connected to the rotor (9) for providing a driving movement for the vehicle component (2), the electric motor (3) comprising a braking device (6) with a mechanical drive and / or pyrotechnic brake unit (12, 20), which is designed to brake the rotating unit (5) in order to prevent voltage generation by the electric motor (3) after a critical event of the motor vehicle (1). The invention also relates to a vehicle component (2) and a motor vehicle (1).

Description

The invention relates to an electric motor for a vehicle component of a motor vehicle, in particular for a compressor, having a stationary unit comprising a stator for magnetic field generation, and a rotating unit having a stator rotatably mounted relative to the stator and a rotor shaft connected to the rotor for providing a drive movement for the vehicle component. The invention also relates to a vehicle component and a motor vehicle.

In the present case, the interest is directed to electric motors or electrical machines which serve to drive vehicle components. Such a vehicle component may be, for example, a compressor in the form of a fuel cell compressor for fuel cell vehicles or a compressor for at least partially combustion engine driven vehicles. Furthermore, electric motors or traction electric motors are of interest, which generate a torque required for the vehicle drive of the motor vehicle. Particularly in the case of critical events of the motor vehicle, for example in the case of an accident of the motor vehicle, it is necessary for the electric motor to be braked or switched off as quickly as possible. This is intended to prevent the electric motor from generating electrical voltages after the critical event of the motor vehicle which could jeopardize persons or safety-relevant systems. In particular, the supply of electrical energy in an electrical system of the motor vehicle, for example, in a high-voltage vehicle electrical system and / or a low-voltage electrical system should be prevented. For braking electrical machines, it is known from the prior art to produce an active short circuit or AKS. For this purpose connection cables of the electric motor are short-circuited. The duration of time after which the electric motor is braked, however, is very long in the case of an active short circuit, measured in terms of the time during an accident, and can be, for example, up to 1 s. However, the turn-off speeds required in an accident usually need to be less than 50 ms, e.g. Be 15ms. Braking due to an active short circuit can therefore be too slow in the event of an accident to prevent energy from being fed into the vehicle electrical system.

It is an object of the present invention to provide a solution, as an electric motor of a vehicle component of a motor vehicle can be switched off particularly quickly and easily in a critical event of the motor vehicle.

This object is achieved by an electric motor, a vehicle component and a motor vehicle with the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the figures.

An inventive electric motor for a vehicle component of a motor vehicle, in particular for a compressor, has a stationary unit with a stator for magnetic field generation and a rotating unit with a rotor rotatably mounted relative to the stator and with a rotor shaft connected to the rotor for providing a drive movement for the vehicle component on. In addition, the electric motor has a braking device with a mechanical and / or pyrotechnic brake unit, which is designed to brake the rotating unit to prevent voltage generation by the electric motor after a critical event of the motor vehicle.

The electric motor is designed in particular as a high-voltage electric motor for driving a vehicle component in the form of a compressor or compressor of the motor vehicle. However, the electric motor may also be designed as an electric drive machine or a traction machine for driving the motor vehicle. The electric machine has the stationarily mounted in the motor vehicle stationary unit with the stator and with respect to the stationary unit rotatably mounted rotary unit with the rotor. The stator may for example have a hollow cylindrical shape, wherein the rotor is rotatably mounted in the cylindrical cavity of the stator. In the radial direction, therefore, the rotor is surrounded by the stator, wherein a longitudinal axis of the stator corresponds to an axis of rotation of the rotor. The electric motor may be, for example, a permanent-magnet or a current-excited synchronous machine. In the case of a permanent magnet synchronous machine, the rotor has a permanent magnet for excitation. In the case of a current-excited synchronous machine, the rotor has an energizable exciter winding for excitation. The rotor is connected to a rotor shaft which, for example, can rotate together with the rotor and projects beyond the stator at at least one axial end of the stator. The rotor shaft can convert the rotational movement of the rotor into the drive movement for the vehicle component and transmitted thereto.

In order to prevent the electric motor from continuing to operate after a critical event and unwanted voltage being generated by the rotating unit that continues to revolve despite the critical event, the rotating unit should be braked in the event of a critical event. Such a critical event may be, for example Accident of the motor vehicle in the form of a collision of the motor vehicle or in the form of a rollover of the motor vehicle. In order to decelerate the electric motor as quickly as possible, this has the braking device with the mechanical and / or pyrotechnic brake unit. The brake unit is actuated in particular mechanically and / or pyrotechnically for providing a braking force which acts on the rotating unit and brakes it. The pyrotechnic brake unit may, for example, have a propellant charge for storing braking energy. The propellant may release the braking energy by generating a gas pressure which is used to decelerate the rotating unit. The mechanical brake unit may, for example, have a tensioned spring for storing the braking energy, wherein the braking energy is released by relaxing the spring. For example, when relaxing, the spring can move a braking element, which after the critical event is moved from a rest position to a braking position and brakes the rotating unit, for example by friction or positive engagement between the braking element and the rotating unit.

By the pyrotechnic and / or mechanical brake unit, the braking device is designed in particular to turn off the electric motor faster than is possible by an active short circuit. For example, the braking device can switch off the electric motor in less than 15 ms, whereas, in the case of an active short circuit, the electric motor is switched off only after 1 s. By braking the rotating unit, so by switching off the electric motor, it can be prevented that the electric motor generates energy in the form of an electrical voltage after the critical event, which is relevant for high-voltage safety and endanger people when fed into an electrical system of the motor vehicle could. An equipped with an electric motor according to the invention vehicle component is therefore designed very safe.

Preferably, the braking device has a control unit which is designed to detect the critical event based on sensor data of a vehicle-side sensor unit and to control the brake unit for braking the rotating unit. The pyrotechnic and / or mechanical brake unit is thus controlled by the control unit. For example, the control unit can be integrated into an airbag control unit which can trigger airbags of the motor vehicle in the event of the critical event for vehicle occupant protection. The sensor unit may include, for example, acceleration sensors for detecting a collision of the motor vehicle and yaw rate sensors for detecting a rollover of the motor vehicle. Such sensors may already be present in the motor vehicle in connection with the deployment of the airbag. As soon as the critical event of the motor vehicle has been detected by the control unit on the basis of the sensor data of the sensor unit, the control unit can control the pyrotechnic brake unit and / or the mechanical brake unit for braking the rotating unit. For example, the control unit may provide a control signal for igniting the propellant charge and / or relaxing the spring for moving the brake element from the rest position to the braking position.

In a development of the invention, the braking device is designed to exert a braking force on the rotor shaft coupled to the rotor for braking the rotating unit. By braking the rotor shaft and the rotor is braked. This embodiment is based on the finding that the rotor shaft is led out of the stator at at least one axial end and is therefore more easily accessible than the rotor enclosed by the stator. By applying the braking force to the rotor shaft, the rotating unit can thus be braked in a particularly simple manner.

It proves to be advantageous if the stationary unit has a shaft bearing for supporting the rotor shaft and the pyrotechnic brake unit is designed to decelerate the rotor shaft to plastically deform the shaft bearing and press it onto the rotor shaft. The shaft bearing is in particular formed as a bearing shell, which surrounds the rotor shaft at least partially and in which the rotor shaft is rotatably mounted. The shaft bearing is deformed by the pyrotechnic brake unit such that the shaft bearing rests after the deformation of the rotor shaft. Due to the friction between the rotor shaft and the shaft bearing, the rotor shaft and thus the rotor are braked. Also, the shaft bearing is located outside the stator and thus easily accessible. Thus, the pyrotechnic brake unit can be arranged without great effort on the shaft bearing.

It can be provided that the pyrotechnic brake unit comprises an air cushion surrounding the shaft bearing and a pyrotechnic gas generator, wherein the pyrotechnic gas generator is adapted to fill the air cushion for plastic deformation of the shaft bearing with gas. The air cushion may be, for example, annular and enclose or surround the shaft bearing. As long as no critical event occurs, the air cushion is unfilled and the shaft bearing is undeformed, so that the rotor can move with the rotor shaft as intended. The propellant charge is formed in this case as the pyrotechnic gas generator, which has, for example, a Anzündeeinheit and a fuel, for example, a solid propellant. The ignition unit can be activated when the critical event occurs, for example, by a current pulse of the control unit, which then ignites the fuel. The resulting gas is released into the air cushion, so that the air cushion is filled or inflated abruptly. By filling the air cushion, the shaft bearing is deformed and pressed onto the rotor shaft, so that it is braked. Such a pyrotechnic brake unit designed in this way can be integrated into the electric motor in a particularly simple manner, in particular without the electric motor having to be extensively reconfigured.

Alternatively or additionally, the pyrotechnic brake unit may comprise a pyrotechnic gas generator which is designed to decelerate fluidically for braking the rotor shaft an impeller of the vehicle component configured as a compressor coupled to the rotor shaft. The rotor shaft is thus coupled here with the impeller and transmits the rotational movement of the rotor to the impeller. For example, the gas generated by the inflator after the critical event may be directed in vanes of the impeller. In this case, the gas has a flow direction counter to a direction of rotation of the impeller, so that the impeller, the rotor shaft coupled to the impeller and the rotor coupled to the rotor shaft are decelerated by the gas flowing counter to the blades.

It can also be provided that the braking device has at least one piston-shaped brake element, which is fixedly arranged on one of the two units and locked there and which for braking the rotating unit with a pyrotechnic unlocking the pyrotechnic brake unit and / or with a mechanical unlocking the mechanical brake unit can be unlocked, wherein the brake member is in the unlocked state in mechanical contact with the other unit. In particular, the mechanical unlocking element has a mechanical spring which is coupled to the brake element. Alternatively or additionally, the pyrotechnic unlocking element has a pyrotechnic gas generator and a cylinder tube for receiving the brake element.

The piston-shaped brake element or the brake piston is in the locked state in the rest position and thereby allows a relative movement between the rotating unit and the stationary unit. In the unlocked state, the brake piston is in the braking position, blocking the relative movement between the rotating unit and the stationary unit. For example, the brake element may be part of the rotating unit and arranged on the rotor shaft. In the braking position, the braking element is pressed against the stationary unit, for example against the shaft bearing. Also, the braking element may be part of the stationary unit and be arranged for example on the shaft bearing. In the braking position, the braking element is pressed against the rotating unit, for example against the rotor shaft. In the braking position, the brake element is thus in the radial direction between the stationary unit and the rotating unit.

For example, the unit with which the brake element is in mechanical contact in the unlocked state, at least one stopper corresponding to the brake element. Such a stopper may for example be a recess in which the piston-shaped brake element is arranged in the braking position, so that the positive movement between the rotating and the stationary unit is blocked by this positive engagement. Also, the stopper may be an elevation against which the piston-shaped brake element strikes in the braking position and by which the relative movement between the rotating and the stationary unit is prevented.

The mechanical unlocking element has in particular the mechanical spring, with which the brake element is coupled. In the locked state of the brake element, the mechanical spring is tensioned. By an electrical pulse, the spring can be relaxed and thereby the spring coupled to the brake element can be transferred from the rest position to the braking position. Also, the brake element can be unlocked by means of the pyrotechnic unlocking element. The pyrotechnic unlocking element in the form of a pyrotechnic actuator may comprise the pyrotechnic gas generator and the cylinder tube, in which the piston-shaped brake element is arranged in the rest position. In the critical event, the gas generator can generate gas, through which the brake piston arranged in the cylinder tube is abruptly pushed out of the cylinder tube and thus transferred from the rest position to the braking position.

The invention also relates to a vehicle component, in particular compressor, for a motor vehicle having an electric motor according to the invention or an advantageous embodiment thereof. The compressor is in particular a fuel cell compressor for providing an air supply to a fuel cell of a motor vehicle designed as a fuel cell vehicle.

A motor vehicle according to the invention comprises at least one vehicle component according to the invention. The motor vehicle may be designed as a fuel cell vehicle or as an at least partially internal combustion engine driven motor vehicle, for example as a hybrid vehicle or as a purely internal combustion engine vehicle.

The embodiments presented with reference to the electric motor according to the invention and their advantages apply correspondingly to the vehicle component according to the invention and to the motor vehicle according to the invention.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or in isolation.

The invention will now be explained in more detail with reference to a preferred embodiment and with reference to the drawings.

• 1 eine schematische Darstellung einer Ausführungsform eines erfindungsgemäßen Kraftfahrzeugs;
• 2 eine schematische Längsschnittdarstellung einer Ausführungsform eines erfindungsgemäßen Elektromotors;
• 3 eine schematische Querschnittsdarstellung eines Teils des Elektromotors mit einer ersten Ausführungsform einer Bremseinrichtung;
• 4a, 4b eine schematische Querschnittsdarstellung eines Teils des Elektromotors mit einer zweiten Ausführungsform einer Bremseinrichtung; und
• 5a, 5b eine schematische Querschnittsdarstellung eines Teils des Elektromotors mit einer dritten Ausführungsform einer Bremseinrichtung.

Show it:

• 1 a schematic representation of an embodiment of a motor vehicle according to the invention;
• 2 a schematic longitudinal sectional view of an embodiment of an electric motor according to the invention;
• 3 a schematic cross-sectional view of a portion of the electric motor with a first embodiment of a braking device;
• 4a . 4b a schematic cross-sectional view of a portion of the electric motor with a second embodiment of a braking device; and
• 5a . 5b a schematic cross-sectional view of a portion of the electric motor with a third embodiment of a braking device.

In the figures, identical and functionally identical elements are provided with the same reference numerals.

1 shows a motor vehicle 1 according to the present invention. The car 1 is designed in particular as a fuel cell vehicle, as a hybrid vehicle or as a purely internal combustion engine driven motor vehicle. The car 1 includes a vehicle component 2 , which is formed in the present case as a compressor. For example, the compressor may be used as a fuel cell compressor for a fuel cell of the motor vehicle 1 be educated. To drive the vehicle component 2 indicates the vehicle component 2 an electric motor 3 on. The electric motor 3 has one in the motor vehicle 1 fixedly arranged, stationary unit 4 and one opposite the stationary unit 4 rotating unit 5 on. In case of a critical event of the motor vehicle 1 , For example, in an accident of the motor vehicle 1 , the electric motor 3 To be able to switch off, the electric motor 3 a braking device 6 on. The braking device 6 serves to the rotating unit 5 To stop or brake, so that in case of accident can be prevented, that the electric motor 3 unintentionally generates an electrical voltage and this in an electrical system 7 of the motor vehicle 1 feeds.

An embodiment of the electric motor 3 is in 2 in longitudinal section along a longitudinal direction L of the electric motor 3 shown. The stationary unit 4 includes a stator 8th for generating a magnetic field. The rotating unit 5 has a rotor 9 on, which here within the hollow cylindrical stator 8th is arranged and in one direction of rotation D around the longitudinal axis L is rotatably mounted. In the radial direction R is the rotor 9 So from the stator 8th surround. The rotor 9 can in the case of a permanent-magnet electric motor 3 have a permanent magnet. In the case of a current-excited electric motor 3 can the rotor 9 have a field winding. In addition, the rotating unit points 5 a rotor shaft 10 on which with the rotor 9 is coupled and together with the rotor 9 is rotatable. The rotor shaft 10 is in a shaft bearing 11 stored, which is also part of the stationary unit 4 is and therefore stationary in the vehicle 1 is stored.

During operation of the electric motor 3 the rotor turns 9 inside the stator 8th and transfers the rotary motion to the rotor shaft 10 , The rotor shaft 10 For example, it may be coupled to an impeller of the compressor and thus the rotational movement of the rotor 9 transferred to the wheel. In order now in the case of the critical event of the motor vehicle 1 the electric motor 3 to be able to switch off is the braking device 6 provided, which is the rotating unit 5 , For example, by braking the rotor shaft 10 , can stop. It can be prevented in the event of an accident by the unintentionally further rotating rotor 9 Voltage generated and in the electrical system 7 of the motor vehicle 1 is fed. The braking device 6 here has a pyrotechnic brake unit 12 on.

In 3 is the pyrotechnic brake unit 12 , the rotor shaft 10 as well as the shaft bearing 11 shown in cross section. The pyrotechnic brake unit 12 For example, an annular air cushion 13 and have a pyrotechnic gas generator, not shown here. The air cushion 13 surrounds the shaft bearing 11 in the radial direction R and is suddenly filled with gas by the gas generator in the event of a critical event. By filling the air cushion 13 this will be on the shaft bearing 11 pressed, which then plastically deformed. Due to the plastic deformation is the shaft bearing 11 on the rotor shaft 10 pressed, which is then braked or stopped. By braking the rotor shaft 10 becomes the entire rotating unit 5 braked.

In 4a . 4b . 5a and 5b are further embodiments of the braking device 6 shown. The braking device 6 here has a piston-shaped brake element 14 on. The piston-shaped brake element 14 can be from a resting position, as in 4a and 5a shown in a braking position, as in 4b and 5b shown to be moved. In 4a and 4b is the brake element 14 Part of the rotating unit 5 and here on the rotor shaft 10 arranged. In 5a and 5b is the brake element 14 Part of the stationary unit 4 and here at the shaft bearing 11 arranged. According to 4a and 5a is the brake element 14 locked and is therefore in the rest position. In the rest position blocks the brake element 14 a relative movement between the rotor shaft 10 and the waveguard 11 Not. In 4b and 5b is the brake element 14 unlocked and therefore has the braking position. In the braking position is the brake element 14 in mechanical contact with the shaft bearing 11 ( 4a) or the rotor shaft 10 ( 5b) and blocks the relative movement between the rotor shaft 10 and the waveguard 11 , The shaft bearing 11 according to 4a . 4b wells 15 on, in which the brake element 14 is arranged in the braking position. According to 5a . 5b has the rotor shaft 10 increases 16 on which the brake element 14 in the braking position. The wells 15 or increases 16 form stopper, which with the brake element 14 corresponding. But it can also be provided that no stopper is provided so that the rotating unit 5 only by friction between the brake element 15 and the shaft bearing 11 or the rotor shaft 10 is slowed down.

To unlock the brake element 14 , So to transfer the brake element 14 from the rest position to the braking position, the braking device has 6 according to 4a and 4b the pyrotechnic brake unit 12 with a pyrotechnic unlocking element 17 on. The pyrotechnic unlocking element 17 here comprises a pyrotechnic actuator with a cylinder tube 18 in which the brake element 14 is arranged, and a pyrotechnic gas generator 19 , The gas generator 19 is designed to generate a gas pressure through which the brake element 14 from the rest position in the cylinder tube 18 is moved to the braking position.

According to 5a and 5b has the braking device 6 for unlocking the brake element 14 a mechanical brake unit 20 with a mechanical unlocking element 21 in the form of a spring 22 on. The spring 22 is in the locked state of the brake element 14 strained and is used to unlock the brake element 14 relaxed. This will be the braking element 14 along the radial direction R in the direction of the rotor shaft 10 Moves until there is the rotor shaft 10 touched and slowed down.

The mechanical brake unit 20 and / or the pyrotechnic brake unit 12 For example, from a control unit, not shown here, the braking device 6 be controlled. The control unit can use sensor data of an accident sensor system of the motor vehicle 1 recognize the critical event and then the brake unit 12 . 20 enable them to be the rotating unit 5 controls.

LIST OF REFERENCE NUMBERS

1

motor vehicle

2

vehicle component

3

electric motor

4

stationary unit

5

rotating unit

6

braking means

7

board network

8th

stator

9

rotor

10

rotor shaft

11

shaft bearing

12

pyrotechnic brake unit

13

air cushion

14

braking element

15

deepening

16

increase

17

pyrotechnic unlocking element

18

cylinder tube

19

inflator

20

mechanical brake unit

21

mechanical unlocking element

22

feather

L

longitudinal direction

R

radial direction

D

direction of rotation

Claims (10)

Electric motor (3) for a vehicle component (2) of a motor vehicle (1), in particular a compressor, comprising - a stationary unit (4) comprising a stator (8) for magnetic field generation, and - a rotating unit (5) having a relation to the stator (8) rotatably mounted rotor (9) and connected to the rotor (9) rotor shaft (10) for providing a drive movement for the vehicle component (2), characterized in that the electric motor (3) comprises a braking device (6) with a mechanical and / or pyrotechnic brake unit (12, 20), which is designed to brake the rotating unit (5) in order to prevent voltage generation by the electric motor (3) after a critical event of the motor vehicle (1). Electric motor (3) after Claim 1 , characterized in that the braking device (6) has a control unit which is designed to detect the critical event based on sensor data of a vehicle-side sensor unit and to control the brake unit (12, 20) for braking the rotating unit (5). Electric motor (3) after Claim 1 or 2 , characterized in that the braking device (6) is adapted to exert a braking force on the coupled to the rotor (9) rotor shaft (10) for braking the rotating unit. Electric motor (3) after Claim 3 , characterized in that the stationary unit (4) has a shaft bearing (11) for supporting the rotor shaft (10) and the pyrotechnic brake unit (12) is adapted for plastically deforming the shaft bearing (11) for braking the rotor shaft (10) and to press on the rotor shaft (10). Electric motor (3) after Claim 4 , characterized in that the pyrotechnic brake unit (12) comprises a shaft bearing (11) surrounding the air cushion (13) and a pyrotechnic gas generator, wherein the pyrotechnic gas generator is adapted to the air cushion (13) for plastically deforming the shaft bearing (11) Gas to fill. Electric motor (3) according to one of Claims 3 to 5 , characterized in that the pyrotechnic brake unit (12) comprises a pyrotechnic gas generator, which is designed to decelerate the rotor shaft (10) coupled to the rotor shaft (10) impeller of the configured as a compressor vehicle component (2) fluidly decelerate. Electric motor (3) according to one of the preceding claims, characterized in that the braking device (6) has at least one piston-shaped brake element (14), which is fixedly arranged on one of the two units (4, 5) and locked there and which is used to decelerate the rotating unit (5) with a pyrotechnic unlocking element (17) of the pyrotechnic brake unit (12) and / or with a mechanical unlocking element (21) of the mechanical brake unit (20) can be unlocked, wherein the brake element (14) in the unlocked state in mechanical contact with the other unit (5, 4) stands. Electric motor (3) after Claim 7 , characterized in that the mechanical unlocking element (21) has a mechanical spring (22) which is coupled to the brake element (14), and / or the pyrotechnic unlocking element (17) comprises a pyrotechnic gas generator (19) and a cylinder tube (18 ) for receiving the brake element (14). Vehicle component (2), in particular compressor, for a motor vehicle (1) with an electric motor (3) according to one of the preceding claims. Motor vehicle (1) with at least one vehicle component (2) according to Claim 9 ,

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