DE102011006748A1 - Drive unit for a vehicle with an electric motor and a method for operating such a drive unit - Google Patents

Abstract

The present invention relates to a drive unit for a vehicle, which comprises an electric motor driving a vehicle wheel with a rotor, in which the transmission of the rotary movement from the electric motor to the vehicle wheel can be blocked by a locking device. In order to achieve a more energy-efficient standstill of the vehicle on an inclined plane, the locking device has a profiled locking wheel 22 and a locking element 24, the locking element 24 having an engagement area 26, the engagement area 26 for locking the locking device by a movement against gravity in the profile of the ratchet wheel 22 can be inserted.

Description

Field of the invention

The invention relates to a drive unit for a vehicle with an electric motor and to a method for operating such a drive unit.

In recent years, the interest in electric cars has increased more and more, in particular due to a growing environmental awareness.

In electric cars, among other things, in addition to central and Radnahen motors and wheel hub drives can be used. Hub drives are usually arranged on or in a vehicle wheel of a vehicle. Wheel hub drive conventionally have a motor unit, via which the wheel hub and thus the vehicle wheel of the vehicle can be driven.

To stop an electric vehicle, for example when stopping at a traffic light, in a traffic jam or during a parking operation, on an inclined plane, for example on a slope or mountain, and to avoid rolling back of the vehicle, usually either a mechanical brake must be actuated or the Electric motor to be maintained in the energized state. However, energizing the electric motor to maintain a stoppage of a vehicle on an inclined plane consumes a lot of power and may result in heating of the engine.

The object of the invention is therefore to provide a drive unit with which a standstill of a vehicle on an inclined plane can be maintained more energy efficient.

The subject of the present invention is a drive unit for a vehicle which comprises an electric motor driving a motor with a rotor, in which the transmission of the rotational movement from the electric motor to the vehicle wheel can be blocked by a locking device having a profiled locking wheel and a locking element, wherein the blocking element has an engagement region, wherein the engagement region for blocking the blocking device can be introduced by a movement against the force of gravity into the profile of the barrier wheel.

By means of the drive unit according to the invention, the position of the vehicle on an inclined plane, for example on a slope or hill, can advantageously be kept more energy-efficient, for example when being stopped at a traffic light, in a traffic jam or during a parking operation, and rolling back of the vehicle can be avoided. In this case, the blocking element can in particular be in a blocking position, in which the engagement region is introduced against the force of gravity in the profile of the barrier wheel. By deactivating the locking device, the engagement region of the locking element, in particular by gravity, can be brought into a non-locking position spaced from the barrier wheel, in which a rolling back of the vehicle, for example for parking or turning, is allowed.

Due to the fact that the engagement region can be introduced into the profile of the barrier wheel by a movement against the force of gravity, inadvertent activation of the locking device during travel can advantageously also be avoided, thus improving the reliability of the system.

The drive unit can be either a direct drive, for example a wheel hub motor, or a drive unit equipped with a transmission.

In the sense of the present invention, a barrier wheel can be understood to mean, in particular, a substantially rotationally symmetrical component which is rotatably mounted about the axis of rotation. In this case, it can essentially be understood that the component can deviate from an ideal body of revolution, in particular as a result of the profile.

For example, the profiled lock wheel may be a toothed and / or grooved wheel. The teeth or grooves may be formed on the outer circumferential surface, on an inner circumferential surface or on a side surface of the wheel. In particular, the profiled lock wheel, a gear, such as a spur gear, an internal gear, a crown wheel or a worm wheel, be.

In a preferred embodiment, the lock wheel is a gear. Thus, the lock wheel can be configured in a particularly simple and cost-effective manner. An embodiment in the form of a gear also has the advantage that gears which serve in the drive unit for other purposes, can also be used as a lock wheel.

In the context of a further preferred embodiment, the lock wheel is therefore a part of the electric motor, for example a wheel hub motor. On the installation of an additional barrier wheel can be advantageously dispensed with. This in turn has the advantage that the material costs and the weight of the drive unit can be optimized.

In the context of another preferred embodiment, the drive unit comprises a transmission. In a preferred embodiment of this embodiment, the lock wheel is a transmission gear. Even so, the material costs and the weight of the drive unit can be optimized.

However, the lock wheel can also be an additional component. For example, the lock wheel can be an additional component arranged in the electric motor or in the transmission, for example a toothed wheel. By an additional lock wheel, if necessary, the design effort can be reduced. In addition, an additional lock wheel can advantageously be configured in terms of its blocking function optimized.

In addition to a toothed or grooved wheel, the profiled lock wheel may also be another substantially rotationally symmetrical, rotatably mounted component, for example the rotor of the electric motor, which is on an outer lateral surface, an inner lateral surface or a side surface with a profile, for example provided with one or more teeth or grooves.

In the context of a further preferred embodiment, the barrier wheel in the form of a profile, in particular a toothing, on or in the outer or inner circumferential surface of the rotor or a rotor shaft is formed. For this purpose, the rotor or the rotor shaft itself represent the barrier wheel, in particular by the profile, in particular the toothing, in the outer or inner circumferential surface of the rotor or the rotor shaft is formed. However, it is also possible that on the outer or inner circumferential surface of the rotor or the rotor shaft, a profiled component, such as a gear, attached, for example, plugged is. This embodiment has proven particularly advantageous for direct drives, such as wheel hub motors, in which the locking wheel should preferably have the largest possible effective diameter. A simple solution thereof can be represented by a reshaped toothing in the radially remote area of the rotor.

In the context of a further preferred embodiment, the barrier wheel and the blocking element are parts of a, preferably (to) switchable, freewheel mechanism. A freewheeling mechanism may, in particular, be understood to mean a mechanism which has a shaft and an outer ring acting as a blocking wheel, in which case the shaft can also be designed as an inner ring. Between the shaft and acting as a lock wheel outer ring one or more locking elements acting as locking elements are arranged, which allow rotation of the shaft relative to the outer ring in a first direction, which is also referred to as a freewheeling direction, and a rotation of the shaft relative to the outer ring in one to the first reverse second direction, which is also referred to as locking direction lock. A switchable freewheeling mechanism may be understood to mean a freewheeling mechanism in which the latching element or elements can be brought into different positions.

For example, in a simple switchable freewheeling mechanism, the latching element (s) may be brought into a non-locking position in which the shaft is rotatable in both directions relative to the outer ring and into a blocking position in which the freewheeling mechanism performs the usual function of free-wheeling in shape a rotation of the shaft relative to the outer ring in one direction and a lock against rotation in the opposite direction.

However, the freewheeling mechanism is preferably a free-wheeling mechanism which can be switched between a first freewheeling direction and a second freewheeling direction opposite to the first freewheeling direction. In such a switchable freewheel mechanism, the latching element or the latching elements, for example, in a first locking position, in which the freewheel mechanism has a rotation of the shaft relative to the outer ring in the first direction of freewheeling and a lock against rotation in the reverse direction, and in a second locking position are brought, in which the freewheel mechanism has a rotation of the shaft relative to the outer ring in the second direction of freewheeling and a lock against rotation in the reverse direction. In addition, the latching element or the latching elements can be brought into a non-locking position in which the shaft is rotatable in both directions relative to the outer ring. A freewheel switchable between two freewheeling directions can advantageously be used both on positive (uphill) and negative (downhill) inclined planes.

Preferably, the freewheel mechanism is arranged between a rotor shaft and a housing of the electric motor. It is advantageous that in this case acts on the freewheel - compared to a load acting on the transmission output - low load.

In the context of the present invention, a blocking element can be understood in particular to be a component which has a region, the so-called engagement region, which can be introduced into the profile of the barrier wheel by a movement, in particular against the force of gravity. in particular to lock a rotation of the lock wheel and thus the locking device. For this purpose, the blocking element can be both linearly guided and rotatably mounted.

In the context of another preferred embodiment, the blocking element is a linearly guided, in particular pin-shaped, blocking element. Such a configured locking element has proven to be particularly advantageous in combination with an electromagnetic actuation and can be used for example as part of a freewheel mechanism.

In the context of another preferred embodiment, the blocking element is a pawl. A pawl may, in particular, be understood to mean a rotatably mounted mechanical device which has an engagement region which can be introduced into the profile of the barrier wheel in order to lock the blocking device. Such a configured locking element can be used in particular as part of a freewheel mechanism. In particular, a locking element in the form of a pawl from a non-locking position, in which the distal end of the pawl, the so-called engagement portion, spaced below the barrier wheel is arranged, in a blocking position, in which the distal end, that is, the engagement area, against gravity is introduced into the profile of the lock wheel, be rotatable.

In the context of another preferred embodiment, the blocking element is a rocker. A rocker may, in particular, be understood as meaning a mechanical device having at least two arms which are rotatably mounted about a rotation or tilting axis and which has an engagement region which can be introduced into the profile of the barrier wheel in order to lock the locking device. Also, such a configured locking element can be used as part of a freewheel mechanism. Also, a blocking element in the form of a rocker can from a non-locking position, in which a distal end of an arm, the so-called engagement portion, spaced below the barrier wheel is disposed, in a blocking position, in which the distal end of the arm, so the engaging portion opposite Gravity is introduced into the profile of the barrier wheel, be rotatable or tiltable. In particular, the blocking element may be a rocker arm. A rocker arm may refer to a rocker in which a movement of a first arm of the rocker by applying a force to a second arm of the rocker, for example by means of a rod, is executable.

The blocking element can be designed, for example, mechanically, electromotively or electromagnetically operable. By an electric motor actuation advantageously a high efficiency can be achieved. By a mechanical operation advantageously a particularly simple structure and easy handling are possible.

In a preferred embodiment, the blocking element is electromagnetically actuated. An electromagnetic actuation of a blocking element requires - compared to the energizing of the complete electric motor to maintain a standstill of the vehicle on an inclined plane - significantly less power. In addition, an electromagnetic actuation of the locking element has advantages with respect to its structural design. So it is possible, for example, to arrange the blocking element within the barrier wheel and raise the locking element without consuming constructive measures in the interior of the lock wheel by an electromagnetic force against gravity and in a profiled example on the inner circumferential surface lock wheel, for example, an internal gear, and introduce thus locking the locking device. Likewise, of course, an electromagnetic actuation of an outside, in particular below, the barrier wheel arranged locking element without complicated design measures possible.

In the context of a further preferred embodiment, the shape of the engagement region corresponds at least partially to the negative profile shape, in particular the negative tooth shape or groove shape, of the barrier wheel. By a corresponding shape advantageously a particularly good barrier effect can be achieved. The size of the engagement region may differ from the size of the negative profile shape of the barrier wheel. In particular, the engagement region may have a smaller size than the negative profile shape of the barrier wheel. This has the advantage that the blocking element can be more easily introduced into the negative profile shape.

The drive unit may in particular have two or more profiled locking wheels, which are arranged coaxially with an angular offset from one another, wherein the blocking element for blocking by a movement against gravity in the profiles of the lock wheels can be introduced. Thus, advantageously, the resolution of the locking device can be increased. The wheel circumference of a vehicle wheel can be for example 2 m. With a 1:10 reduction, every revolution of the motor would correspond to 20 cm of travel. In a lock wheel, such as a ratchet wheel, with 16 grooves this would give a resolution of 12.5 mm. By means of two such coaxial discs with angular offset, a resolution of 6.25 mm could be achieved or represented by three discs of about 4 mm.

With regard to further advantages and features of the drive unit according to the invention, reference is hereby explicitly made to the explanations in connection with the method according to the invention and the drawings.

Another object of the present invention is a method for operating a vehicle with a drive unit according to the invention.

• – Detektieren eines Stillstands des Fahrzeugs, insbesondere nach einem Bremsvorgang,
• – Aufbringen eines Drehmoments auf das Sperrenrad zum Einstellen einer Rastposition des Sperrenrades durch den Elektromotor,
• – Einbringen des Eingriffsbereichs des Sperrelements in das Profil des Sperrenrades, und
• – Entfernen des Drehmoments des Elektromotors,

umfassen.For detecting the vehicle, for example while holding the vehicle in an inclined plane, the method can be the method steps:

• Detecting a standstill of the vehicle, in particular after a braking operation,
• Applying a torque to the lock wheel for setting a locking position of the lock wheel by the electric motor,
• - Introducing the engagement portion of the locking element in the profile of the lock wheel, and
• Removing the torque of the electric motor,

include.

The application of a torque to the lock wheel for setting a locking position of the lock wheel by the electric motor can be effected in particular by a resolver of the electric motor.

For a first brief moment after the vehicle has stopped, the electric motor can hold the position of the vehicle. The locking position of the lock wheel can be electronically controlled, for example via the resolver. In this case, the rotor of the electric motor can be set in an optimal position in which the blocking element is ideally under a profile recess, such as a groove of the barrier wheel. This can be simplified by setting a clear clearance between the shape of the engagement region of the blocking element and the negative profile shape of the barrier wheel. Upon activation, for example by a control unit or by an instruction of the driver, the blocking element can be brought from a non-locking position against gravity into a locking, engaging in the profile of the lock wheel position. As soon as the blocking element is in the blocking position, the torque can be removed by the electric motor, in particular in order to save energy.

For electric motors with a precise angle of rotation measurement, the control unit can determine which of the flanks of the blocking element is loaded in the blocking position. Alternatively, however, the detection can also take place via a force or torque sensor. In particular, the drive unit according to the invention can therefore have a force or torque sensor for detecting the loaded flank of the blocking element or of the engagement region in the position introduced into the profile of the barrier wheel.

• – Aufbringen eines das Sperrelement entlastenden Drehmoments durch den Elektromotor, insbesondere einen Resolver des Elektromotors, und
• – Entfernen des Eingriffsbereichs des Sperrelements aus dem Profil des Sperrenrades,

umfassen.For starting the vehicle, for example after holding the vehicle in an inclined plane, the method can be the method steps:

• - Applying a locking element relieving torque by the electric motor, in particular a resolver of the electric motor, and
• Removing the engagement region of the blocking element from the profile of the barrier wheel,

include.

Whether a start by the driver is intended can be determined, for example, by means of an actuation of the accelerator pedal by the driver.

If the vehicle is to go up after holding, a relieving torque is applied anyway to the lock wheel and thus relieved the locking element. To minimize material wear and energy requirements, however, it is particularly advantageous to apply a relieving torque to the lock wheel when the vehicle is to drive down after holding, in particular in order then to be able to easily remove the engagement area of the lock element. Whether a start up or down should take place, can be detected by a rotation angle measurement of the electric motor, in particular wherein it is determined which of the flanks of the locking element is loaded. Alternatively, the detection can take place via a force or torque sensor, in particular with which the drive unit can be equipped.

Preferably, the engagement region of the locking element is automatically introduced into the profile of the barrier wheel during a charging process of the vehicle. By an automatic locking during the charging phase can be avoided accidentally starting the vehicle with plugged charging connection advantageously. Activation of the blocking element can be effected in particular by a signal from the charging device.

The stopping process may, for example, proceed as follows: the driver brakes the vehicle to a standstill. If necessary, the driver releases the brake. The electric motor moves to the next possible locking position of the lock wheel. The blocking element is brought from the non-locked position into the locked in the profile of the lock wheel position. Then the torque is removed from the engine. Then the vehicle is standing, without an active actuation of the driving or brake pedal of the driver.

The starting process may, for example, proceed as follows: Upon actuation of the accelerator pedal by the driver, the electric motor is activated and the engagement region of the blocking element is pulled out of the barrier wheel. If the vehicle is to go uphill starting from the locked position, the locking element is advantageously already relieved anyway and can be easily solved. If the vehicle is to travel downhill from the locked position, the engine is preferably initially driven backwards. In this way, the locking element can be relieved and also easily solved.

With regard to further advantages and features of the method according to the invention, reference is hereby explicitly made to the explanations in connection with the drive unit according to the invention and the drawings.

drawings

Further advantages and advantageous embodiments of the subject invention are illustrated by the drawings and explained in the following description. It should be noted that the drawings have only descriptive character and are not intended to limit the invention in any way. Show it

1 a schematic cross section through a locking device of an embodiment of a drive unit according to the invention; and

2 a schematic view of an embodiment of a drive unit according to the invention.

1 shows that the locking device designed as a gear profiled locking wheel 22 and a pin-shaped linearly guided blocking element 24 having. Alternatively, the blocking element may also be rotatably mounted, for example in the form of a pawl, rocker and / or a rocker arm, executed (not shown). 1 illustrates that the blocking element 24 an intervention area 26 which of a non-blocking, the barrier wheel 22 spaced position against gravity into a blocking position is movable, in which the engagement region 26 in the profile of the barrier wheel 22 is introduced. The actuation of the blocking element 24 is preferably carried out electromagnetically.

1 shows that the lock wheel 22 has teeth and intermediate grooves on the outer surface. At the barrier wheel 22 it may be both an already existing wheel, for example, a gear wheel, as well as an additional wheel, for example, a widened by an additional Nutenkranz gear wheel act.

1 illustrates that the blocking element 24 , which in the illustrated embodiment may also be referred to as a detent pin, in the engagement area 26 has a shape which the negative profile shape, in particular the negative tooth shape or groove shape of the barrier wheel 22 corresponds, wherein the engagement region of the blocking element 24 However, has a smaller size, in particular is designed narrower than the negative profile of the barrier wheel 22 , By such a configuration can advantageously both a slight introduction of the blocking element 24 in the profile of the barrier wheel 22 as well as a good fit.

2 shows that the drive unit according to the invention in this embodiment, a vehicle wheel 10 driving electric motor 20 as well as a transmission 30 includes. 2 also illustrates that both between the electric motor 20 and the transmission 30 as well as between the transmission 30 and the vehicle wheel 10 a rotary motion transmission is present. For example, by the in 1 Locking device shown here is the transmission of the rotational movement of the electric motor 20 on the vehicle wheel 10 ,

The arrows symbolize possible installation positions for such a locking device. The left arrow illustrates that a locking device in the engine 20 or may be formed at the motor output. A use directly on the engine 20 has the advantage that the translation advantageous to the representable positioning accuracy of the locking position of the lock wheel 22 In addition, the torque to be blocked when using the locking device on or in the engine 20 by the reduction ratio lower than the vehicle.

The middle arrow illustrates that the locking device at the entrance of the transmission 30 can be trained.

The right arrow illustrates that the locking device also at the output of the transmission 30 can be trained.

In addition, of course, a design of the lock wheel within the transmission, in particular in the form of a transmission gear, possible.

LIST OF REFERENCE NUMBERS

10

vehicle

20

electric motor

30

transmission

22

Sperrenrad

24

blocking element

26

engagement area

Claims (10)

Drive unit for a vehicle, comprising a vehicle wheel ( 10 ) driving electric motor ( 20 ) with a rotor, wherein the transmission of the rotational movement of the electric motor ( 20 ) on the vehicle wheel ( 10 ) is lockable by a locking device, wherein the locking device is a profiled lock wheel ( 22 ) and a blocking element ( 24 ), wherein the blocking element ( 24 ) an intervention area ( 26 ), wherein the engagement area ( 26 ) for locking the locking device by a movement against gravity in the profile of the lock wheel ( 22 ) can be introduced. Drive unit according to claim 1, wherein the blocking element ( 24 ) is electromagnetically actuated. Drive unit according to claim 1 or 2, wherein the barrier wheel ( 22 ) is a gear. Drive unit according to one of claims 1 to 3, wherein the blocking element ( 24 ) is a linearly guided, in particular pin-shaped, blocking element or a pawl or a rocker, in particular a rocker arm, is. Drive unit according to one of claims 1 to 4, wherein the lock wheel ( 22 ) is a part of the electric motor or an additional arranged in the electric motor component. Drive unit according to claim 5, wherein the barrier wheel ( 22 ) is formed in the form of a profile on or in the outer or inner circumferential surface of the rotor or a rotor shaft. Drive unit according to one of claims 1 to 6, wherein the drive unit is a transmission ( 30 ), in particular wherein the barrier wheel ( 22 ) is a transmission gear or an additional component arranged in the transmission. Drive unit according to one of claims 1 to 7, wherein the lock wheel ( 22 ) and the blocking element ( 24 ) Parts of a, in particular switchable, freewheel mechanism, in particular wherein the freewheel mechanism is a switchable between a first freewheeling direction and a second, opposite to the first freewheeling direction freewheeling mechanism. Drive unit according to one of claims 1 to 8, wherein the shape of the engagement area ( 26 ) at least partially the negative profile shape of the barrier wheel ( 22 ) corresponds. Method for operating a vehicle with a drive unit according to one of claims 1 to 9, wherein the method for detecting the vehicle, for example when holding the vehicle in an inclined plane, the method steps: - detecting a stoppage of the vehicle, in particular after a braking operation, - Applying a torque to the lock wheel ( 22 ) for setting a locking position of the lock wheel ( 24 ) by the electric motor ( 20 ), in particular a resolver of the electric motor, - introducing the engagement area ( 26 ) of the blocking element ( 24 ) in the profile of the barrier wheel ( 22 ), and - removing the torque of the electric motor ( 20 ), and / or wherein the method for starting the vehicle, for example after holding the vehicle in an inclined plane, the method steps: - applying a locking element relieving torque by the electric motor, in particular a resolver of the electric motor, and - Intervention area ( 26 ) of the blocking element from the profile of the barrier wheel ( 22 ), and / or wherein the engagement region ( 26 ) of the blocking element ( 24 ) during a charging process of the vehicle automatically in the profile of the lock wheel ( 22 ) is introduced.

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