DE102008037809A1 - Method for operating electrical parking brake in vehicle, involves adjusting locking force to locking value, when vehicle is not in starting mode or pass over into operating condition - Google Patents

Abstract

The method involves adjusting a locking force (F-FBS) to a locking value, when a vehicle is not in starting mode or pass over into an operating condition. The locking force adjusts a locking value opposite to another reduced locking value, where reduced locking value is determined as a function of a parking situation. An independent claim is included for a device for operating an electrical parking brake in a vehicle.

Description

The The invention relates to a method and an apparatus for operation an electric parking brake in a motor vehicle according to the The preambles of claims 1 and 8, respectively.

In the DE 102 38 870 A1 is an automatic braking operation of a vehicle described in which after the standstill of the vehicle and when a certain triggering criterion is met, a braking torque for maintaining the vehicle is established at a standstill by the service brake. After a holding time interval and if the vehicle has not been restarted in the meantime, the parking brake is automatically applied and the service brake released. Tripping criteria can be: the termination of the operation of the service brake by the driver after the vehicle is at a standstill, the departure of the vehicle seat by the driver or the operation of a control element provided for this purpose.

At the same place will carry out this procedure described at the start of a vehicle, wherein after the start of the Vehicle engine by means of the service brake a parking brake torque corresponding braking torque is generated while simultaneously the parking brake is released. Thereafter, a holding time interval started in which the service brake applies the braking torque. If the vehicle is not started by the end of the holding time interval, so again the parking brake is automatically operated and the service brake released. If the vehicle is hit, the service brake releases automatically.

The Release the parking brake takes longer in this process as a usual starting process. At the same time the driver notices when starting the vehicle a resistance, since he against the partial not yet released brake anfährt.

Of the The invention is therefore based on the object, an improved method and an improved apparatus for operating an electric parking brake specify.

The Task is according to the invention in terms of Method by the features specified in claim 1 and in terms the device solved by the features specified in claim 8.

advantageous Embodiments of the invention are the subject of the dependent claims.

at a method of operation according to the invention an electric parking brake in a motor vehicle is in the at a release of the parking brake a locking force to stop the vehicle is generated at a standstill and the parking brake is in response to a request and provision of a startup the vehicle sufficiently high starting torque solved. there the locking force is set to a first detection value when the vehicle is in a non-approaching operating state or is in such an operating state. If, on the other hand, the vehicle is in a ready-to-start operating state or goes into such an operating state, is the locking force on a relative to the first detection value reduced second set value, the second Detection value is determined so that the vehicle until the request and providing sufficient for starting the vehicle high Starting torque remains safely braked.

By the reduction of the locking force before starting the vehicle, is also required for the start of release time to Release the parking brake reduced and the driver notices when starting only a small braking resistor, which a comfortable start is possible. Wear and tear Load on suspension components is reduced. has the motor vehicle via a manual transmission, can on a clutch travel sensor for detecting the position of the clutch or be dispensed with the clutch pedal.

Of the first detection value preferably corresponds to a maximum value of locking force achievable with the parking brake.

Preferably If the vehicle is in the approaching operating state, when a drive motor of the vehicle is running or started or if an accelerator operation is sufficient to one To provide drive torque.

Preferably is the reduced second detection value of the locking force in dependence determined by a parking situation, in particular depending of at least one of the following sizes: one Vehicle inclination, a brake temperature at the parking brake, a Battery condition of a vehicle battery, a vehicle mass of the vehicle, a wheel diameter of at least one braked by the parking brake Wheel.

From the knowledge of the vehicle inclination, a mass of the vehicle and a tire diameter so required for holding the vehicle against a downgrade force parking brake torque and a corresponding parking brake force can be determined and adjusted as the second setpoint, preferably increased by a safety factor. A vehicle parked on a level road, without a slope, can be equipped with a lower parking brake force to be kept at a standstill than a parked on a slope motor vehicle. The parking brake force adapted accordingly to the second parking value results in a reduced release time when starting the vehicle when the parking brake is released. By knowing the brake temperature, thermal expansion effects in the parking brake can be taken into account in the calculation of the second setpoint value, so as to ensure that the vehicle can be held even after the brake has cooled down, if the locking force is reduced to the second setpoint value. If the brake temperature is high, for example if the vehicle is restarted after a journey with frequent brake use and a short break, the parking brake force can thus be increased in relation to a cold brake in order to keep the vehicle safely at a standstill. With knowledge of the battery state, the reduction of the locking force can be prevented to the second set value for safety reasons, if not enough energy is available to adjust the locking force again at any time to the higher first detection value.

In an advantageous embodiment of the method is the parking brake from the reduced second detection value to one opposite higher value, in particular to the first detection value, increases when a vehicle roll is detected.

In an advantageous further embodiment of the method is the Parking brake in response to a trigger request a Driver of the vehicle, in particular in response to an operation of a the parking brake assigned key, operated.

According to one advantageous embodiment of the invention may be a state parameter Drive state are queried to the time at which the Vehicle should start and the service brake be released must determine.

A Inventive device for operating a electric parking brake in a vehicle comprises a control device for providing a control signal for controlling the parking brake and setting a detection signal corresponding to the control signal in the parking brake. The control device is set up here, to generate the control signal such that the parking brake in response upon a request and provision of one for starting the vehicle sufficiently high starting torque is released, and that the Locking force depending on an operating condition of the vehicle between a predetermined first detection value and a second detection value reduced here opposite to vary, the second detection value being determined in such a way that the vehicle until the request and provision of sufficient high starting torque remains safely braked.

Preferably the control device is set up at least one of the following To receive information and to calculate the locking force to consider: an information about the operating condition the vehicle, an information about a vehicle inclination, an information about a brake temperature at the parking brake, an information about a battery condition of a vehicle battery, an inforation about a vehicle mass of the vehicle, an inforation about a wheel diameter of at least a wheel braked by the parking brake.

One Embodiment of the invention will be described below a drawing explained in more detail. Showing:

1 schematically an electric parking brake and a device for controlling and / or regulating the electric parking brake.

In 1 is schematically an electric parking brake 1 a motor vehicle with a control device 2 for controlling the electric parking brake 1 shown. The control device 2 gives as a control signal a parking brake force F _FSB , which is the parking brake 1 should exercise. For this purpose, the device information from a number of sensor devices 3.1 to 3.8 and a storage device 4 to disposal. The vehicle has a drive motor, not shown in the figure, which can be designed as an internal combustion engine or electric motor.

The sensor device 3.1 determines an engine operating condition MBZ. In the simplest case, it can be seen from the engine operating state MBZ whether an engine of the motor vehicle is running or has been switched off. The sensor device 3.2 determines a vehicle inclination FN, in particular a longitudinal inclination of the motor vehicle. The sensor device 3.3 determines a battery state BZ of a vehicle battery. The two sensor devices 3.4 . 3.5 determine brake temperatures T _B1 , T _{B2 of} the brakes of the motor vehicle. It may also be provided a larger number of sensor devices for determining brake temperatures, in particular for determining the brake temperatures of more than two braked with the electric parking brake wheels of the motor vehicle. Alternatively, the brake temperatures T _B1 , T _B2 in the control device 2 can be calculated from an energy balance of the brakes made.

The sensor device 3.6 detects a rolling of the vehicle by detecting wheel rotation pay N. The sensor device 3.7 determines a requested by the driver of the vehicle via an accelerator pedal actuation torque MA. The sensor device 3.8 determines a provided by a drive motor to driven wheels drive torque MB.

There may be a smaller number of sensor devices 3.1 to 3.n be provided, wherein not all of the signals MBZ, FN, BZ, T _B1 to T _Bn , N must be determined and taken into account.

In the storage device 4 are vehicle-typical parameters P stored, for example, the mass of the vehicle and tire radii of the parking brake 1 braked wheels.

The electric parking brake 1 may include multiple units on multiple wheels of the motor vehicle. The control device 2 may specify different parking brake forces F _FSB for each of these wheels, for example at different brake temperatures T _B1 to T _BN .

The parking brake 1 is actuated when there is a lock command. The detection command is given by the driver of the vehicle by operating one of the parking brake 1 associated switch generated. Also conceivable is an automatic generation of the detection command, for example, the fact that the drive motor of the vehicle is stopped or that the driver leaves the vehicle while the drive motor is running, and this opens a door and / or solves a seat belt, which by means of a door switch or buckle switch on easy way is detectable. If there is no locking command, the parking brake will be activated 1 not activated.

The control device 2 controls the electric parking brake 1 by the following procedure, in each case on condition that a locking command is present, ie that the activation of the parking brake 1 is desired:
It is first determined whether the vehicle is in a ready-to-start operating state or not ready-to-start operating state. The vehicle is ready to start when the drive motor of the vehicle is already running or is started or when an accelerator pedal operation is sufficient to provide the drive torque requested via the accelerator pedal actuation. Accordingly, the vehicle is in a non-approaching operating condition when the drive motor has been turned off, for example by actuation of an ignition key or when the vehicle is in a secured state via another conditional access system.

When transferring the vehicle in the not approaching operating state, for example, when stopping the engine, receives the control device 2 from the sensor device 3.1 a corresponding information about the engine operating state MBZ. As a result, the parking brake force F _FSB becomes the parking brake 1 set to a first detection value, so that the motor vehicle is safe. The first detection value corresponds to a predetermined maximum value of the locking force F _FSB .

If the vehicle is transferred to the approaching operating state, for example by starting the drive motor, receives the control device 2 again the corresponding information about the engine operating state MBZ. The control device 2 then reduces the locking force F _FSB to a second detection value. This second detection value is determined on the basis of at least one of the information MBZ, FN, BZ, T _B1 to T _Bn such that the vehicle is securely held when the locking force F _{FSB is set} to the second detection value

For example, from the knowledge of the vehicle inclination FN, a known mass of the vehicle and a known tire diameter, a parking brake torque required for holding the vehicle against a downhill force and a corresponding parking brake force F _FSB can be determined. The value of this preferably by a safety factor increased locking force F _FSB corresponds to the second parking value, the approachable operating state of the vehicle to the parking brake 1 is set.

The parking brake 1 is then solved when the drive motor is started and a starting torque is requested and provided, which is sufficiently high for starting. This can also be transmitted in the information on the engine operating state MBZ or in a further information on the drive state.

To the effectiveness of the parking brake 1 To take into account, the brake temperature T _B1 , T _{B2 can be} taken into account for evaluating the parking situation and for determining the sufficiently high starting torque and / or the required, reduced parking brake force F _FSB , ie the second parking value. If the brake temperature T _B1 , T _{B2 is} high, for example, when the vehicle is restarted after a frequent brake use and a short break, the parking brake force F _FSB may be increased as compared with a cold brake to keep the vehicle at a standstill.

Further, for evaluating the parking situation and for determining the sufficiently high starting torque and / or the required, reduced parking brake force F _FSB further parameters of a Motor operating state can be determined.

In addition, to assess the parking situation and to determine the sufficiently high starting torque and / or the required, reduced parking brake force F _FSB, the battery state BZ can be taken into account. This is determined, for example, if the vehicle has enough energy available to a renewed automatic actuation of the parking brake 1 with the engine off. If the energy is not sufficient for this purpose, a reduction of the parking brake force F _{FSB can} be omitted in order to ensure that the motor vehicle remains safely braked even when the running engine is switched off again without starting up.

The sensor device 3.2 for the vehicle inclination FN may be formed, for example, as a capacitive tilt sensor or a magnetoresistive angle sensor.

The sensor devices 3.4 . 3.5 For example, they can be designed as thick-film resistors, which are attached to a respective vehicle brake.

The sensor device 3.3 For determining the battery state BZ, for example, the battery state BZ can be calculated from the elementary battery characteristics voltage, current and temperature.

The sensor device 3.6 may include one or more commonly present in the vehicle wheel speed sensors for detecting the rolling of the vehicle.

The sensor device 3.7 may include a path sensor for detecting the accelerator pedal operation.

The sensor device 3.8 may include a torque sensor provided on a drive axle of the vehicle. Alternatively, the provided drive torque MB can also be determined from a current gear ratio and engine speed.

1

electrical parking brake

2

control device

3.1 to 3.n

sensor

BZ

battery status

FN

vehicle inclination

F _FSB

Parking brake force

MBZ

Engine operating condition

T _B1 to T _Bn

brake temperature

N

wheel speed

MA

requested drive torque

MB

-provided drive torque

P

typical automotive parameter

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10238870 A1 [0002]

Claims (9)

Method for operating an electric parking brake ( 1 ) in a vehicle in which, when the parking brake is triggered ( 1 ) a parking force (F _FBS ) is generated for holding the vehicle at a standstill and in which the parking brake ( 1 ) is achieved in response to a request and provision of a sufficiently high starting torque for starting the vehicle, characterized in that the locking force (F _FBS ) is set to a first detection value when the vehicle is in a non-approaching operating state or in such Operating state, and that the locking force (F _FBS ) is set to a second setpoint reduced compared to the first detection value when the vehicle is in a starting operating state or in such an operating state, wherein the second detection value is determined such that the vehicle remains safely braked until the request and provision of the sufficiently high starting torque. A method according to claim 1, characterized in that the reduced second detection value of the locking force (F _FBS ) is determined in dependence on a parking situation. A method according to claim 1 or 2, characterized in that the reduced second detection value of the locking force (F _FBS ) is determined as a function of at least one of the following variables: - a vehicle inclination (FN), - a brake temperature (T _B1 to T _Bn ) the parking brake ( 1 ), - a battery state (BZ) of a vehicle battery - a vehicle mass (M) of the vehicle, - a wheel diameter of at least one by the parking brake ( 1 ) braked wheels. Method according to one of the preceding claims, characterized in that the vehicle is in the approaching Operating state is when a drive motor of the vehicle is running or is started or if an accelerator pedal operation is sufficient to provide a drive torque. Method according to one of the preceding claims, characterized in that the first detection value of the parking brake force (F _FSB ) one with the parking brake ( 1 ) corresponds to the maximum achievable braking force. Method according to one of the preceding claims, characterized in that the parking brake force (F _FBS ) is increased from the reduced second parking value to a value which is higher here, in particular to the first parking value, if a vehicle rolling up is detected. Method according to one of the preceding claims, characterized in that the parking brake ( 1 ) in response to a triggering request of a driver of the vehicle, in particular in response to actuation of one of the parking brake ( 1 ) button is pressed. Device for operating an electric parking brake ( 1 ) in a vehicle, with a control device ( 2 ) for providing a control signal for controlling the parking brake ( 1 ) and setting a control signal corresponding to the locking force (F _FBS ) in the parking brake ( 1 ), wherein the control device ( 2 ) is arranged to generate the control signal such that the parking brake ( 1 ) is achieved in response to a request and provision of a sufficiently high starting torque for starting the vehicle, characterized in that the control device ( 2 ) is further configured, depending on an operating condition of the vehicle, to vary the locking force (F _FBS ) between a predetermined first locking value and a second locking value reduced thereto, wherein the second locking value is determined such that the vehicle until the request and provision of the sufficiently high starting torque remains safely braked. Apparatus according to claim 8, characterized in that the control device ( 2 ) is adapted to receive at least one of the following information and to take into account in the calculation of the locking force (F _FBS ): - an inforation about the operating state of the vehicle, - an information on a vehicle inclination (FN), - an information on a brake temperature (T _B1 to T _Bn ) on the parking brake ( 1 An information about a battery state (BZ) of a vehicle battery - an information about a vehicle mass (M) of the vehicle, - an inforation about a wheel diameter of at least one by the parking brake ( 1 ) braked wheel.