DE102023203152A1 - Method for defined tensioning of a rotor shaft of an electric motor, computer program, computer program product, system and vehicle - Google Patents

Abstract

A method is proposed for the defined clamping of a rotor shaft (RW) of an electric motor, in particular for driving a vehicle, after the rotor shaft (RW) has been positioned in a defined rotational angle position and a form-locking element (FE) of a locking actuator (SA) has been moved into the rotor shaft (RW) in a lifting movement without constraint in order to lock it. The positioning of the rotor shaft (RW) is absolutely recorded by means of a rotor (shaft) position sensor. And in addition, the rotor shaft (RW) is struck in a defined clockwise or anti-clockwise direction against the form-locking element (FE) in this locked state in order to clamp the rotor shaft (RW) against the form-locking element (FE) in a defined way. A computer program, a computer program product, a system and a vehicle are also proposed.

Description

The invention relates to a method for the defined tensioning of a rotor shaft of an electric motor, in particular for driving a vehicle.

The invention also relates to a computer program and a computer program product, each of which depicts this method, a system with a locking actuator and a control unit connected to the locking actuator, wherein the control unit has such a computer program or computer program product, and a vehicle with such a computer program or computer program product.

Parking locks are known in which an electrically actuated lever with a so-called ratchet tooth interacts with a gear wheel of a drive train in order to block or lock the drive train. For example, see the publication DE 102017 102 804 A1 which describes such a parking lock with a ratchet mechanism.

Parking locks are also known in which the locking device or locking element can be adjusted or moved in a straight line along a path of movement. For example, see the publication DE 10 2019 110 384 A1 which describes such a parking lock with a locking bolt.

The object of the present invention is to protect such parking locks against attempts at manipulation by third parties or unauthorized persons.

This object is achieved by a method proposed and protected according to claim 1.

A method is proposed for the defined clamping of a rotor shaft of an electric motor, in particular for driving a vehicle, after the rotor shaft has been positioned in a defined rotational angle position and a positive locking element of a locking actuator has been moved into the rotor shaft in a lifting movement without constraint in order to lock it.

The positioning of the rotor shaft is absolutely recorded by means of a rotor (shaft) position sensor.

In addition, in this locked state, the rotor shaft is struck against the form-locking element in a defined clockwise or anti-clockwise direction in order to clamp the rotor shaft against the form-locking element in a defined manner.

Using a so-called rotor (shaft) position sensor, a position or location of a rotor of the electric motor and thus a position or location of the said rotor shaft on which the rotor is arranged can be precisely determined relative to the three phases or to the poles of a stator of the electric motor. The rotor (shaft) position sensor thus enables efficient commutation of the electric motor on the one hand and provides an absolute rotational angle position of the rotor shaft on the other.

The rotor (shaft) position sensor can be designed in the form of an inductively acting signal transmitter or in the form of a Hall sensor, the functioning of which is sufficiently known to the person skilled in the art. The rotor (shaft) position sensor can be provided on the electric motor side or on the vehicle drive side, i.e. on a traction drive of a vehicle in the form of an electric motor or on the locking actuator side, i.e. on the locking actuator.

The tension deliberately induced by the proposed method creates or ensures efficient protection against manipulation, which prevents unlocking of the locking actuator by third parties or unauthorized persons or at least makes it significantly more difficult. And if an attempt is made to manipulate the locking actuator when the locking mechanism is in a tensioned state, for example by applying a current to the actuator, the force generated by the actuator is not sufficient for the unlocking process.

The rotor shaft can be struck against the form-locking element until a definable electromotive shutdown torque of the electric motor is reached, at which point the rotation of the rotor shaft is interrupted.

The switch-off torque of the electric motor corresponds to a monitorable current consumption of the electric motor, so that when a definable reference value for the current consumption is reached, the electric motor is switched off or the rotation of the rotor shaft is interrupted.

In order to determine a plurality of definable ideal rotation angle positions or ideal positions of the rotor shaft in which the rotor shaft can be locked or unlocked without constraint by means of the form-locking element, the rotor shaft is divided over its circumference into individual circular segment sections in such a way that each of these circular segment sections is assigned a form-locking element section which can be joined to a complementarily shaped form-locking element section of the locking actuator.

Starting from an initial position of the rotor shaft that has to be determined or specified once, which is understood to be one of these ideal angle of rotation positions or ideal positions of the rotor shaft relative to the form-fitting element of the locking actuator, the rotor shaft can be rotated or moved into the respective ideal positions according to the said, definable division - and taking into account its current, precisely recorded angle of rotation position. These so-called ideal positions represent support points that are stored in a software or computer program of a control unit for controlling or rotating the rotor shaft.

In this context, “free from constraint” means that the two interacting form-locking element sections do not come into contact with respect to their associated flanks in the circumferential direction of the rotor shaft or the locking actuator, or they mesh with one another without contact, or they are in contact with one another without contact.

It is proposed to use a uniform division to subdivide the circumference of the rotor shaft. This simplifies the positioning of the rotor shaft, starting from the initial position once determined and fixed.

It is also proposed that the rotor shaft is positioned in such a way that a form-locking element section of the rotor shaft does not enclose a relative angle to or with a complementary form-locking element section of the locking actuator. This means that ideal angle of rotation positions are used in which the two form-locking element sections that interact with one another do not enclose a relative angle to one another or with one another. This means that the two form-locking element sections are located or arranged centrally to one another in the circumferential direction of the rotor shaft or the locking actuator.

Alternatively, rotation angle positions in the sense of ideal positions can also be used, in which the two interacting form-locking element sections enclose a relative angle to one another or to each other, so that they form an off-center arrangement in the circumferential direction of the rotor shaft or the locking actuator, provided that no contact is made with respect to the said flanks of the form-locking element sections in the circumferential direction of the rotor shaft or the locking actuator. In this case, a mechanical play between the two form-locking element sections in the circumferential direction of the rotor shaft or the locking actuator would be provided accordingly. Such a mechanical play enables - depending on the design - a large number of possible positions of the two interacting form-locking element sections in relation to one another, in which the said contact between the said flanks does not occur.

In one embodiment, a locking mechanism is proposed in which the form-locking element is moved in an axial stroke movement and longitudinally to the rotor shaft. In this case, a rotor shaft with an external toothing in an area of one of its ends and a complementary form-locking element can be used, which is moved in an axial stroke movement and longitudinally to the rotor shaft against and into the rotor shaft.

Furthermore, a computer program for carrying out the method described above is proposed, as well as a computer program product comprising program code means stored on a computer-readable data carrier in order to carry out the method described above when the program code means are executed on a computer.

Furthermore, a system with a locking actuator and a control unit connected to the locking actuator is proposed, wherein the control unit has a computer program or a computer program product of the type described above, as well as a vehicle with a computer program or a computer program product of the type described above.

A vehicle is understood to mean any type of vehicle or motor vehicle that is powered by an electric motor, but in particular passenger cars and/or commercial vehicles in the form of electric or hybrid vehicles. These can be partially or fully autonomous vehicles.

• 1 eine Anordnung eines Sperraktuators und einer sperrbaren Rotorwelle eines Elektromotors,
• 2 eine systemische Darstellung eines Inverters mit einer Steuereinheit und des in 1 gezeigten Sperraktuators mit einer Steuereinheit,
• 3 einen Verriegelungsvorgang des in 1 gezeigten Sperrmechanismus und
• 4 einen Entriegelungsvorgang des in 1 gezeigten Sperrmechanismus.

They show, partly schematically:

• 1 an arrangement of a locking actuator and a lockable rotor shaft of an electric motor,
• 2 a systemic representation of an inverter with a control unit and the 1 shown locking actuator with a control unit,
• 3 a locking process of the 1 shown locking mechanism and
• 4 an unlocking process of the 1 locking mechanism shown.

The locking mechanism according to 1 illustrates two complementary designed and rotatable relative to one another, namely a first form-locking element FE of a locking actuator SA and a second form-locking element in the form of a lockable rotor shaft RW of an electric motor (not shown) for driving a vehicle. The locking actuator SA is attached to a housing (not shown) of the electric motor of an electric motor drive unit, which as such can include a gear, and can therefore be supported on this housing. Depending on the state of the locking mechanism, these two form-locking elements FE, RW are arranged coaxially to one another (unlocked state) or concentrically in sections (locked state).

In this case, an internal toothing IV of the form-locking element FE interacts with an external toothing AV of the rotor shaft RW, which is formed as such in a region of one end of the rotor shaft RW, in that the form-locking element FE is electrically actuated in an axial stroke movement and longitudinally to the rotor shaft RW and is thereby joined to the rotor shaft end in sections.

The vehicle in question, which includes this locking mechanism, has an electric motor drive unit with an electric motor in the form of a permanent or separately excited synchronous machine for driving the vehicle, wherein the electric motor can optionally be combined with a reduction gear, a high-voltage battery and an inverter, which is included in the vehicle's power electronics and which establishes the connection between the electric motor and the high-voltage battery. The power electronics can optionally include an integrated voltage converter, which supplies a low-voltage electrical system of the vehicle from the vehicle's high-voltage electrical system.

A control unit of the inverter controls, regulates and monitors the electric motor and ensures that the torque supply and speed control of a vehicle's drive train are as required. The inverter also converts the direct current of the high-voltage battery into the alternating current required by the electric motor.

The power electronics or the inverter included in the power electronics not only supplies the electric motor with electricity, but also the high-voltage battery - namely when the electric motor works as a generator and feeds electricity into the high-voltage battery. In this process, known as recuperation, it converts the alternating current generated by the electric motor into direct current and uses it to charge the high-voltage battery.

2 illustrates a systemic connection between the inverter or an inverter-specific control unit SE _Inv and the locking actuator or a locking actuator-specific control unit SE _SA . The control unit SE _Inv issues a control command SB to the control unit SE _Sa , depending on the input parameters FP of the vehicle (FP = vehicle parameters), whereupon the locking actuator SA locks or unlocks the rotor shaft RW. The control unit SE _SA displays or outputs an actuator state AZ and a locking or locking state VZ.

3 illustrates a wound arrangement of the internal toothing IV of the form-locking element FE and the external toothing AV of the rotor shaft RW relative to one another, namely relative to a circumferential direction and a longitudinal direction of the two form-locking elements FE, RW. The internal toothing IV is stationary relative to the circumferential direction of the two form-locking elements FE, RW and the external toothing AV is rotatable relative to the internal toothing IV.

Both the form-locking element FE and the rotor shaft RW are divided into uniform circular segment sections according to a definable common division over the respective assigned circumference (circular segment section = 360°/n; n = number of teeth), which thus all have the same angular extension.

In the rolled-up representation after 3 This angular extension of such a circular segment section is illustrated as the segment length SL. And in relation to a radius from the center of the form-locking element FE or from the center of the rotor shaft RW, this angular extension corresponds to a pitch-related arcuate distance between the centers of two adjacent teeth of the internal toothing IV or the centers of two adjacent tooth gaps of the external toothing AV.

This segment length SL after 3 - expressed in degrees (angle) - describes a step size from one ideal alignment to the next ideal alignment of the two form-locking elements FE, RW to each other, whereby in these ideal alignments the respectively assigned segment lengths SL do not have or include any angular offset to each other. This means that these respectively assigned segment lengths SL coincide exactly relative to each other and thus do not represent any displacement or deviation from each other in the circumferential direction of the two form-locking elements FE, RW.

Such an ideal alignment of the two form-locking elements FE, RW to each other is achieved by the in 3 The topmost arrangement of the internal toothing IV and the external toothing AV is illustrated. In this arrangement, the two form-locking elements FE, RW are not joined together. The locking mechanism formed by the two form-locking elements FE, RW is therefore unlocked or unlocked. One of these ideal alignments in a direction of rotation of the rotor shaft RW must be determined in the sense of an initial position or location in which the two form-locking elements FE, RW can be joined together with respect to the respective assigned tooth flanks without contact and thus without constraint and consequently with optimized force from the perspective of the locking actuator SA.

Knowing this initial position, the rotor shaft RW can be rotated according to the specified pitch, i.e. the number of circular segment sections, which is defined by the number of teeth, into the respective ideal orientations or into the corresponding rotation angle positions (illustrated by the penultimate arrangement in 3 ). An absolute rotational angle position of the rotor shaft RW is precisely recorded by means of a rotor (shaft) position sensor.

In this way, the circumferences of the two form-locking elements FE, RW can be divided into, for example, n = 32 (because each has 32 teeth) circular segment sections, so that uniform circular segment sections of 360°/32 = 11.25° are obtained. The said ideal alignments or the corresponding rotation angle positions of the rotor shaft RW thus represent support points that are stored as such in the control unit SE _Inv and can be approached.

The 3 The second and third arrangements of the internal toothing IV and the external toothing AV shown each illustrate a deviation Abw. 01, Abw. 02 between the associated segment lengths SL, whereby these deviations Abw. 01, Abw. 02 do not allow a positive locking of the locking mechanism.

In a parking situation in which the vehicle is to be brought to a standstill and locked, the rotor shaft RW can be rotated in a first or in an opposite second direction of rotation or clockwise or counterclockwise to one of the said ideal orientations.

The rotor shaft RW can be rotated - along the shortest path - to the nearest ideal alignment or to the next support point, i.e. to the ideal alignment that encloses the smallest angle with the currently recorded absolute rotation angle position of the rotor shaft RW or forms the smallest angle difference, provided the ambient conditions permit it. The rotor shaft RW is therefore rotated by one of these recorded angle differences to the corresponding support point.

In the penultimate in 3 In the arrangement shown, in which such an ideal alignment of the rotor shaft RW to the form-locking element FE is illustrated, the control command SB for locking the rotor shaft RW is issued by the control unit SE _Inv of the inverter to the control unit SE _A of the locking actuator SA, whereupon the form-locking element FE is eclectically actuated or moved against the rotor shaft RW while the vehicle is stationary (vehicle speed = 0 km/h). The form-locking element FE is thereby moved into the rotor shaft RW without constraint, i.e. without contact with the respective tooth flanks and consequently with optimized force from the perspective of the locking actuator SA.

In the last or lowest arrangement in 3 a form-locking of the locking mechanism is illustrated. The two form-locking elements FE, RW are slightly offset from each other due to play. This means that the associated circular segment sections of the two form-locking elements FE, RW are no longer exactly aligned with each other.

4 On the other hand, it illustrates an unlocking or release of the locking mechanism starting from the 4 . shown top arrangement, in which a blocking state or locking state of the locking mechanism is illustrated. This top arrangement illustrates a state in which the external toothing AV is struck against the internal toothing IV. In this arrangement, a deviation Abw. 03 between the respectively assigned segment lengths SL is illustrated.

This can be caused by the vehicle being parked on an uneven surface, so that the vehicle leans against the locking actuator SA and thus against the housing of the electric motor. This in turn causes the rotor shaft RW to be tensioned against the form-locking element FE.

Such a clamping of the rotor shaft RW against the form-locking element FE can also be caused by the rotor shaft RW, after it has been locked by the form-locking element FE without any constraint, being struck against the form-locking element FE in a defined clockwise or anti-clockwise direction in order to clamp the rotor shaft RW against the form-locking element FE in a defined way. This provides protection against manipulation by third parties or unauthorized persons. which prevents or at least significantly complicates the unlocking of the locking actuator.

When the vehicle is started up, the control unit SE _A displays a locking status VZ and outputs it to the control unit SE _Inv . The control unit SE _Inv outputs a control command SB to unlock the rotor shaft RW to the control unit SE _A. The rotor shaft RW is then positioned - with the vehicle at a standstill (vehicle speed = 0 km/h) and with knowledge of the exact recorded absolute position or location of the rotor shaft RW - in the rotational angle position in which it was previously locked and with which the currently recorded absolute rotational angle position of the rotor shaft RW encloses an angle or forms an angular difference in order to relax the rotor shaft RW. The rotor shaft RW is therefore rotated by this angular difference to the last support point approached.

The form-locking element FE is then moved out of the rotor shaft RW without any constraint, i.e. without contact with the respective assigned tooth flanks and consequently with optimized force from the perspective of the locking actuator SA, so that a form-locking of the locking mechanism is released. The vehicle can then be moved.

The deviation Abw. 03 according to 4 is not only due to play, ie not only due to a mechanical play between the form-locking element FE and the rotor shaft RW in the circumferential direction of the locking actuator SA, but also due to an elasticity underlying the locking mechanism, through which a corresponding position of the rotor shaft RW relative to the form-locking element FE is established as a result of an occurring load acting on the locking mechanism. This elasticity depends on the design of the two form-locking elements FE, RW.

Such a deviation Abw. 03, in which the rotor shaft RW is braced against the form-locking element FE, can also be caused by an elasticity underlying the locking mechanism, whereby the deviation Abw. 03 occurs in connection with an occurring or occurring load, which as such acts on the locking mechanism. This depends on how the two interacting form-locking elements FE, RW are shaped or formed in sections. At this point, a gear pair in the form of a Hirthz gear should be mentioned, which as such does not allow any mechanical play.

The positioning of the rotor shaft RW can be carried out via a so-called speed control or a so-called torque control with a so-called P component and a so-called I component.

The said ideal alignments of the two form-locking elements FE, RW to each other or the corresponding rotational angle positions of the rotor shaft RW, which as such - as previously described - represent support points and are stored in the control unit SE _Inv , can also be taught by means of a learning or adaptation process, so that manufacturing tolerances between the two form-locking elements FE, RW can advantageously be compensated.

The previously described control units SE _Inv , SE _A comprise a digital microprocessor unit (CPU) data-connected to a memory system and a bus system, a working memory (RAM) and a storage means. The CPU is designed to process commands that are implemented as a program stored in a memory system, to detect input signals from the data bus and to output output signals to the data bus. The memory system can have various storage media in the form of magnetic, solid-state and other non-volatile media on which a corresponding computer program for carrying out the method and the advantageous embodiments is stored. The program can be designed in such a way that it embodies or is capable of carrying out the method aspects described here, so that the CPU can carry out the steps of such methods and thus control both the vehicle and the parking lock or locking device.

Suitable for carrying out the proposed method is a computer program which has program code means for carrying out all the steps of any of the claims or method claims when the program is executed in the CPU.

The computer program can be easily read into existing control electronics and used to control both the vehicle and the locking actuator - or the parking lock or locking device.

For this purpose, a computer program product is provided with program code means stored on a computer-readable data carrier in order to carry out the method according to any of the claims when the computer program product is executed in the CPU. The computer program product can also be integrated into the control electronics as a retrofit option.

Although exemplary embodiments are explained in the preceding description, it should be noted that a large number of modifications are possible. It should also be noted that the exemplary embodiments are merely examples that are not intended to limit the scope of protection, applications and structure in any way. Rather, the preceding description provides the person skilled in the art with a guide for implementing at least one exemplary embodiment, whereby various changes, in particular with regard to the function and arrangement of the components described, can be made without departing from the scope of protection as it results from the claims and combinations of features equivalent to these.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102017102804 A1 [0003]
• DE 102019110384 A1 [0004]

Claims (9)

Method for the defined clamping of a rotor shaft (RW) of an electric motor, in particular for driving a vehicle, after the rotor shaft (RW) has been positioned in a defined rotational angle position and a form-locking element (FE) of a locking actuator (SA) has been moved into the rotor shaft (RW) in a lifting movement without any constraint in order to lock it, wherein the positioning of the rotor shaft (RW) is absolutely detected by means of a rotor (shaft) position sensor, wherein the rotor shaft (RW) in this locked state is struck in a defined clockwise or anti-clockwise direction against the form-locking element (FE) in order to clamp the rotor shaft (RW) against the form-locking element (FE) in a defined manner. procedure according to claim 1 , wherein, in order to determine a plurality of definable rotational angle positions of the rotor shaft (RW) in which the rotor shaft (RW) can be locked or unlocked without constraint by means of the form-locking element (FE), the rotor shaft (RW) is subdivided over its circumference into individual circular segment sections in such a way that each of these circular segment sections is assigned a form-locking element section which can be joined to a complementarily shaped form-locking element section of the locking actuator (SA). procedure according to claim 2 , whereby a uniform pitch is used to subdivide the circumference of the rotor shaft (RW). Method according to one of the preceding claims, wherein the rotor shaft (RW) is positioned such that a form-locking element section of the rotor shaft (RW) does not enclose a relative angle to a complementarily shaped form-locking element section of the locking actuator (SA). Method according to one of the preceding claims, wherein the form-locking element (FE) is moved in an axial stroke movement and longitudinally to the rotor shaft (RW). Computer program for carrying out a method according to one of the preceding Claims 1 until 5 . Computer program product comprising program code means stored on a computer-readable data carrier for carrying out the method according to one of the preceding Claims 1 until 5 to be carried out when the program code means are executed on a computer. System with a locking actuator (SA) and a control unit (SE _Inv , SE _SA ) for actuating the locking actuator (SA), wherein the control unit (SE _Inv , SE _SA ) is a computer program product according to claim 7 has. Vehicle with a computer program product according to claim 7 .

Images