WO2001058714A1

WO2001058714A1 - Method and device for terminating an active starting traction control function

Info

Publication number: WO2001058714A1
Application number: PCT/EP2001/001044
Authority: WO
Inventors: Rainer Klusemann; Jürgen DIEBOLD; Oliver Huth
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2000-02-10
Filing date: 2001-02-01
Publication date: 2001-08-16

Abstract

The invention relates to a method and device for terminating an active starting traction control function which assists the vehicle when starting on a gradient by building up a braking torque, which maintains said vehicle on said gradient, in the service brake according to external and/or internal variables such as the inclination of the vehicle and/or states of said vehicle, taking said variables into account until a corresponding torque has been created. In order to prevent the starting traction control from being turned off in an uncontrolled manner, the following steps occur: a state for the interruption of the active starting traction control function is determined before or during the build up of a driving torque required for starting according to at lease one measuring variable rendering the vehicle state, the braking torque of the service brake is reduced when the measuring variable is determined, and a vehicle reaction is triggered when the braking torque is reduced after a given amount of time has elapsed.

Description

Method and device for ending an active traction help function

The invention relates to a method and a device for ending an active starting aid function that supports starting a vehicle on an incline by providing a braking torque holding the vehicle on the incline in the service brake in accordance with external and / or internal variables, such as builds up the downhill drive torque and / or operating states or characteristic values of the vehicle and maintains it, including the large ones, until the build-up of a drive torque required for starting.

In vehicles that are equipped with or without an electric parking brake, it is the job of a traction help to support the driver when starting on the mountain. A traction help is therefore a comfort-oriented assistance function (DOA = Drive-Off Assistance). A vehicle is held on a slope with a traction help, for example: the vehicle is stopped, the drive motor is running, the driver is operating the clutch, the driver is using a braking device (service brake and / or

Parking brake). This means that the traction help is only activated when the driver is in the vehicle and his vehicle is ready to go brought the standstill with the braking pressure / force required to hold.

When initiating the starting process (actuating the clutch), the driver is assisted at a standstill in such a way that the vehicle is braked on a slope and the driver can release a previously operated braking device in order to start off without the vehicle rolling away in an uncontrolled manner. This bridges the period between releasing a brake control element and the actual starting process. The start-up process is determined by a suitable evaluation of vehicle information and quantified as drive torque, which is transmitted to the drive wheels via the clutch. The starting aid then assists during the starting process by reducing the braking torque in accordance with the drive torque present on the drive wheels. If the driver builds up sufficient drive torque via the clutch on the drive wheels, the starting aid reduces the braking torque to zero until further activation of the starting aid is initiated by the driver.

“Slope” is understood here to mean any road gradient that is suitable for triggering an automatic, drive-free vehicle movement.

A starting aid is used to ensure that the vehicle only travels in the direction desired by the driver and e.g. does not roll backwards against an obstacle in a parking space on a slope.

The function of the traction help places increased demands on, for example, the energy supply when the engine is switched off if the vehicle is equipped with a so-called automatic start / stop system that switches off the drive motor when the vehicle is stationary. The driver must restart the engine eg operate the accelerator pedal. By the time the drive motor has built up torque, a vehicle without a traction help function may have already rolled against an obstacle.

The traction help can be implemented in vehicles without an electric parking brake with an active or driver-independent service brake. This can e.g. an active brake booster of a hydraulic brake, a motor-pump unit and / or a high-pressure accumulator of an electro-hydraulic brake or an electric motor of an electro-mechanical brake. The difference to the realization with an electric parking brake is that energy is used to hold the vehicle on a slope; While the activated electric parking brake holds the vehicle only via the mechanical self-locking, the energy supply must be ensured for an active service brake. If the driver gets out of the vehicle and the power supply fails (e.g. the internal combustion engine stops and the active brake booster of a hydraulic brake no longer receives a vacuum), the vehicle can roll away. It must therefore be ensured with a traction help that is implemented with an active service brake that the driver is in the vehicle when the traction help is active.

From WO 99/20922 a method for ending the traction help function is known, with which a drive torque is determined when starting on a slope, which is actually available on the drive axle and according to which the braking torque is reduced to zero by the driver support when starting. The traction help function ends when the braking torque held by the active service brake is completely reduced. A starting aid that is intended to prevent the vehicle from rolling back is known from DE 199 41 482 AI. This does not take into account whether the driver is sitting in the vehicle or not. The driver can therefore get out in the belief that he has parked his vehicle properly and then find out too late that the vehicle is rolling away, for example because the engine is switched off and the brake booster no longer has a vacuum.

The invention has for its object to provide a method for ending an active traction help function, which prevents an uncontrolled shutdown of the traction help and allows the driver to take measures, if necessary, to prevent the vehicle from rolling away.

According to the invention, this object is achieved by the steps

Determine a state to interrupt the active one

Starting aid before or during the build-up of a drive torque required for starting in accordance with at least one

Measured variable which represents an operating state or a characteristic value of the vehicle,

Reduction of the braking torque of the service brake when the

Measurand, and

Triggering a vehicle reaction when the braking torque is reduced after a predetermined time course.

Furthermore, the object is achieved in that a generic starting aid is designed in such a way that the starting aid is a determining unit for determining a state for interrupting the active starting aid before or during the build-up of a drive torque required for starting according to at least one measured variable which indicates an operating state or reproduces a characteristic value of the vehicle, contains that the starting aid a control unit for controlling the reduction of the braking torque of the service brake when determined Measured variable, and that the control unit controls the reduction of the braking torque after a predetermined time course so that a vehicle reaction is triggered when the braking torque is reduced.

The function of the active traction help is advantageously limited in time. In other words, if the driver wants to get out of his vehicle, the traction help function must be interrupted and the braking torque held by the active service brake must be reduced. This dismantling should be done in such a way that the driver immediately feels the vehicle reaction, that the traction help function switches off, but still gives him enough time to adjust to it and to take suitable measures, e.g. actuating the parking brake. By limiting the braking torque held by the activated traction help to the braking torque required on the slope and a temporary active assistance phase, a traction help without an electric parking brake can be made available safely. As a vehicle reaction, the method therefore triggers a vehicle movement in correlation to the measured variable.

Detection of the driver's wish to leave the vehicle or detection of a situation that can lead to deactivation of the active service brake can be achieved by one measurement variable or several correlated measurement variables or vehicle information or derived from these measurement variables or vehicle information, calculated or estimated characteristic values from a clutch state representing a release of the clutch pedal and / or a transmission state containing gear information and / or a brake pedal state representing a release of a brake pedal, e.g. a release switch of an electromagnetically actuated brake booster, possibly including information about the actuation an accelerator pedal, and / or one, stopping an engine representing the engine operating state, and / or a vehicle operating state representing a disconnection of at least one electrical supplier is or are obtained.

Of course, further states that can be detected in the vehicle can be used to determine the state to interrupt the active starting aid in order to determine whether the driver wants to leave his vehicle or not. (e.g. belt buckle, driver's door, etc.) These operating states can be detected using sensors, but have disadvantages. Either the signal heads are not safety-critical components such as the door contact switch (additional costs) or they require that the driver abides by the rules and e.g. buckles. In principle, however, these states can be taken into account when determining the state for interrupting the active traction help and / or, if necessary, for plausibility checking.

An advantage of the invention lies in the fact that the method is based on the measurement variables which both withstand the safety-critical consideration and always reliably indicate whether the driver is in the vehicle or not or the active service brake is functioning or not.

An expedient embodiment of the method is characterized in that a set in response to an operation of the brake pedal braking torque M _Fah r _ERVOR g _abe is maintained after the determination of the measured variable maximum 2s to the driver when starting a change from the brake pedal to the accelerator pedal to enable if the brake pedal state and / or the accelerator pedal state is used as a measurement variable for the interruption of the active traction help function. The method provides that the driver is responsible for bringing the vehicle to a standstill in a vehicle equipped with a start-up aid function. Particularly when the road friction coefficients are inhomogeneous (μ-split), in order to bring the vehicle to a standstill, the driver applies a greater braking torque than would be necessary, as determined solely from the slope. It is therefore advantageous to adopt the braking torque (braking pressure, braking force) initially set by the driver as a target for the starting aid. This guarantees that the vehicle can be held on the slope by the traction help whenever the driver has brought it to a standstill. The braking torque set by the driver is taken over by the active service brake, taking into account the pedal behavior, ie the active service brake maintains a brake torque that is slightly below the driver's braking torque.

By means of a rapid reduction of the braking torque M _driving specification set via the brake pedal actuation to the braking torque Mßrems, Lim derived from the downhill driving torque in the determined state to interrupt the active starting aid, a vehicle reaction, such as a rolling away of the vehicle on the slope, can then be advantageous after the reduction time less than 2 seconds, preferably a maximum of 0.5s. It is expedient to ensure that the reduction to a power take-off in accordance with the slope M _Ha ngabtrie _b einzustellendes braking torque is achieved in an independent from the braking torque MFahrevorgabe reproducible period of time.

A fast vehicle response can be achieved in that a in accordance with the slope output torque M _HANGAB tri _e b adjusted brake torque M _braking, is reduced in a first step at least 20% to 50% in a period of at most 3 s, preferably in a time period less ls becomes. In The braking torque is then reduced to zero in at least one further step.

A reduction in the braking torque held by the active service brake to the braking torque required on a slope or on an incline is required for reproducible behavior of the vehicle. The vehicle begins when the braking torque M _Drive rv _or e _a s _e previously in an advantageously always the same amount of time to in accordance with the slope output torque M _downgrade set braking torque M _Br ems, was in the reduced, thus substantially independent of the slope gradient always at the same Time to roll away after the driver releases a pedal. This means that the driver is not tempted to get off even on slopes with small gradients, since the vehicle begins to roll away almost immediately, as usual.

In the case of active brake pressure build-up, a distinction is made between two independent variants of the brake pressure build-up of the traction help, which must be taken into account in a determined state to interrupt the active traction help function:

1. Activation via parking brake

If the driver only applies the parking brake (e.g. when starting the parked vehicle), the braking torque M _Br ems required on the slope, determined in accordance with the slope output torque M _Han g _a btrieb, is immediately built up. This braking torque takes into account the slope or road inclination (sin a),

which according to the relationship sin a = '""'""^" from that of one

8th

Longitudinal acceleration sensor estimated

Gravitational acceleration component is determined, possibly including a safety factor. 2. Activation via the service brake

The driver actuates the service brake (or service and parking brake), then is transferred to an embodiment, the set of the driver's brake torque M _Fah r _he v _orgabe or a determined in accordance with the slope output torque braking torque M _Br ems, Lim set. As long as the driver operates the brake pedal himself, it is not possible to set a brake pressure, which may be higher depending on the situation and which may be required with safety supplements for holding on a slope, since the brake pedal is “pulled away” from the driver when the braking torque is set by means of an active brake booster. If the driver releases the brake pedal, the braking torque applied by the driver is less than the downhill driving torque plus safety, the braking torque can be increased to this value.

It is advantageous if the braking torque M _brake , _L im is _reduced according to an exponential function, preferably according to the following exponential function

occurs, with t _nor m = 0 beginning of the degradation, t _norm ⁼ 1 end of the degradation and K = factor between -2 and +2, preferably the factor K is positive and lies in a range between 1.2 and 1.8.

In order to reduce the computing effort, the braking torque M _brake , Lim can also be reduced after approximation of an exponential function.

If the driver builds up drive torque, the starting aid should release the braking torque so that the vehicle both travels in the desired direction of travel and does not hinder the driver from starting by holding on. Even if the If the driver sets a greater braking torque than would actually be required for the slope, the brake should be released comfortably. It is therefore provided in the method according to the invention that, for at least one determined _quantity which represents a signal representing a start, for example information about the drive torque, a braking torque _braking , _Lιπ which was set after the downhill driving torque, according to the relationship

and a braking moment _Fa orgabe stirrer, which was adjusted to a Brempedalbetätigung, according to the relation

M Hangcihti i - M Ann leb lliems I alnei uιι Rühe 2)

M Hangcihliieh is dismantled.

Is advantageous if the drive torque reaches the value of the calculated slope output torque that a possibly set by the operator to high braking torque at M _Antr ι _{.theta..sub.B>} M Hanßahli I is reduced to zero, the torque balance in (2) is selected.

On the other hand, in μ-split situations, the vehicle is initially stopped with the braking torque set by the driver. When the drive torque is built up, the braking torque is then released in accordance with the comparison according to (2). Compared to (1), the braking torque is reduced compared to (1), in which, starting from the braking torque, which is dependent on the slope, via the balance of M _{Ant ιeb} and MHangabtrieb, there is less tendency to roll away against the desired direction of travel, since the the larger braking torque specified by the driver begins to decrease. An embodiment is shown in the drawing and will be described in more detail below.

Show it:

1 to 3 process diagrams about the possible sequence for ending the traction help function with different measured variables, whereby

1 relates to a clutch signal, FIG. 2 relates to a brake pedal signal, FIG. 3 relates to correlated brake and accelerator pedal signals

Fig. 4 is a diagram of the time course of a braking torque set by the traction help with premature interruption of the traction help function

Fig. 5 is a digram over the time course of the degradation of the braking moment M s _Brem the example of a set of the active service brake in accordance with the brake pedal braking moment M _r _Fa hrervo reproducing •

Fig. 6 shows a device for interrupting the traction help function

According to FIGS. 1 to 3, the traction help assistant function ends after determining a state for interrupting the active traction help before the build-up of a drive torque required for starting because the driver does not get out, believing that his vehicle is properly parked with the active service brake to have.

There are several ways to tell if the driver is in his vehicle: Determining a measurand via a clutch switch (Figure 1)

A switch on the clutch pedal, the switching point of which is above the clutch point, detects when the vehicle is at a standstill whether the traction help function must be interrupted prematurely, i.e. before or during the build-up of a drive torque required to start. Since, when entering the query, it has not yet been determined whether the driver has built up drive torque, it is initially queried in diamond 10 whether the vehicle is running. This situation query can be carried out by evaluating the wheel speeds, for example. If this situation exists, the further query for an interruption can be omitted since the braking torque set by the active service brake is zero (step 12). If the vehicle is at a standstill, diamond 11 asks whether there is a need to prematurely interrupt the traction help function. If the clutch pedal is actuated (e.g. via a clutch switch), the function of the traction help is retained. The braking torque M _braking , i _αm held by the starting aid is _reduced in step 13 as the driving torque M _{AntEιeb is} built up. The reduction takes place at a braking torque M _brake , Lir _r that was set after the downhill torque, according to the relationship

M Hiinμuhn I M office I

M Blair = M

.1 in

M n cihti i

and at a braking torque M _Farιr prescription / which was set after a brake pedal actuation, according to the relationship

This completes the function of the starting aid. If it is decided in diamond 11 that the clutch pedal is released, then that is assume that the driver gets out. The traction help is then, if it is still active, interrupted according to the measured variable generated by the clutch switch via the clutch state. That is, if the driver releases the clutch pedal without starting, the braking torque held by the active service brake is reduced after a predetermined time course, as described in connection with FIG. 4.

Determining a measured variable using a brake light switch (Figure 2)

Entry into the query (diamond 10 and step 12) encompasses the situation detection according to FIG. 1. If the vehicle is at a standstill, diamond 14 queries whether there is a need to prematurely interrupt the traction help function. If the brake pedal is depressed, activation of the traction help is retained. If it is decided in diamond 11 that the brake pedal is not actuated, it can be assumed that the driver gets out. The traction help is then interrupted based on the measured variable generated by the brake light switch (in the active brake booster, the release switch) via the brake pedal status, since if the brake pedal is not pressed, it cannot be reliably decided whether the driver is leaving the vehicle or not. The reduction of the braking torque held by the starting aid must therefore meet at least one condition with regard to its value. In step 15, it is required that the value of the braking torque M _Br ems, which is reduced after a predetermined time course (described in connection with FIG. 4). is below the braking torque M _Br ems, Anfah, which is reduced by the starting aid in the same way as the driving torque M M _ent ri _{eb is} built up. The reduction takes place at a braking torque M _Breras , which was set after the downhill torque, according to the relationship "* ^■ Haimuhii i M Ann i

M All / all) M lli ems hm (i)

M Hangahii teh

and ervogabe with a braking torque _driving? that was set after the brake pedal was pressed, according to the relationship

M Haiigabn teh M Ami ich lii vm s iψilti / tihi ei i i ι> abc '(2).

H, I think I |

The degradation according to M _Bre ms = M _Br ems, zeιι •, ie a degradation after the time course described in connection with Figure 4, always takes place when M _brake , _zeιt ι. <M _brake , start. , otherwise after M _Bre ms = M _Br ems, start. if Mßems, start. • <M _Brem s, zeiti. • A comparison of the determined values of the braking torques M _BreraSrZeι tι- and M _{ß e} ms, _start , takes place in step 15, the reduction following the lower braking torque. This reduction in braking torque takes into account the fact that the driver builds up driving torque only very slowly or hesitantly when the brake pedal is not actuated. In this situation, the function of the traction help is interrupted prematurely if the braking torque has already been reduced to zero after the specified time, but no starting torque suitable for starting has yet been built up.

Determination of a measurement variable via a brake light switch and accelerator pedal actuation (FIG. 3)

The determination of the measured variable comprises the situation detection (diamond 10, 14 and step 12) according to FIG. 2 until the brake pedal actuation is detected. Compared to the exemplary embodiment according to FIG. 2, the assistance phase can advantageously be improved if the braking torque is only reduced when the brake pedal and accelerator pedal are not actuated. For this purpose, diamond 16 queries whether the accelerator pedal is actuated (for example via a status signal of the accelerator pedal provided by the engine control). Is shown in diamond 16 determined that the accelerator pedal is actuated, it is decided in step 17 to abort the reduction of the braking torque initiated in step 15 (FIG. 2) according to the predetermined time profile as described in FIG. 4. In step 18, the braking torque is then reduced in accordance with the method described in step 13 of FIG. 1. If it is found in diamond 16 that the accelerator pedal is not actuated, the braking torque is reduced in step 19 in accordance with the predefined time profile, as described in connection with FIG. 4. The advantage over the method described in connection with FIG. 2 is that the driver can take any amount of time to start when the accelerator pedal is actuated, since the function of the starting aid is not interrupted prematurely.

According to the method, the state for the interruption of the active traction help function should be directly related to a vehicle reaction. The release of the clutch pedal or the accelerator pedal and / or the brake pedal is said to have interrupted (deactivated) the starting aid. Since the interruption of the traction help is determined by a driver action (e.g. releasing the clutch pedal or the accelerator pedal), this is also directly related to the vehicle reaction. That the braking torque should be reduced so that the vehicle starts moving immediately. The driver is not tempted to get out of the vehicle without first ensuring that the vehicle is properly parked or secured.

The immediate vehicle reaction is achieved if the braking torque held by the active service brake is limited to the value required on the slope or is reduced before the interruption of the traction help via an inclination angle sensor (e.g. longitudinal acceleration sensor) or after determining the condition to interrupt the active traction help in a possibly reproducible period of time, which is independent of the value of the braking torque, and which can still be regarded as an immediate reaction to the driver action.

An _exemplary embodiment according to the invention provides for the limitation of the braking torque M _brake , _Lιm held by the active service _brake to the braking torque required on the slope, which is advantageous for a simple, reproducible vehicle _reaction . The vehicle therefore begins to roll away almost independently of the slope slope at the same time after the driver has released a pedal. This means that the driver is not tempted to get off even on slopes with small gradients, since the vehicle immediately begins to roll away as usual.

The advantageous reduction in braking torque Mssrems, Lim shown in Figure 4 ensures that immediately after the driver releases a pedal, the vehicle immediately begins to roll away, but the further reduction takes place more slowly to allow the driver to react. The driver has time to pull off or bring the vehicle to a stop using the service brake. The reduction of the braking torque M _braking, _L i _m is carried out at a constructed in accordance with the slope output torque M _Han g _a b _t rubbed braking torque M _Br e _ms, in at least 20% (based on the related on a slope level) in a period between 0 and 3s, preferably in a time period of 0.5 to 1s, according to the measured variable determined. The braking torque (brake pressure) is then slowly reduced to zero, preferably in a time span of at most 10s, preferably at most 2s. The braking torque M _Br em _{s is} preferably reduced according to an exponential function according to the following relationship ι js | cg ''' ⁽ i -', ™., Ι ⁾ * <- 'fr.-ι _r n <+ - <ι ^m llvcms .lim ° ^{UL υ} - ^L nor ^ 1 with tnorm = 0 beginning of the degradation, t _norm = 1 end of the degradation and K = factor between -2 and 2. In Figure 4 the decrease of the Braking torque M _braking over the normalized time 0 to 1 after the exponential function designated 20. According to a further _exemplary embodiment, the braking torque M _{Breιns is reduced} according to approximation 21 of the exponential function in such a way that a rapid drop within .maximal Is to, for example, 60% of the braking pressure, followed by a slow reduction to 0 within, for example, a maximum of 2s. The dismantling is slower in the second step to allow the driver to react. The driver has time to pull off or bring the vehicle to a stop using the service brake.

Figure 5 shows in Digramm the time course of the degradation of the braking torque M _braking the example of a set of the active service brake in accordance with the brake pedal braking torque M _Fa rerorgabe • at 22 is the brake torque set by the driver in response to the introduced controlled in the brake braking pressure designates , at 23, the braking torque held in the active service brake by the starting aid at time t1 - after the standstill (v = 0) of the vehicle has been determined. The magnitude of this, for example via an active brake booster, in the service brake, driver-independent braking torque 23 is slightly below the braking torque 22 set via the brake pedal actuation in order to avoid a brake pedal reaction while the driver is actuating the brake pedal. Such limits are not necessary for an EMS (electro-hydraulic brake) or an EMB (electro-mechanical brake). The time at which the driver releases the brake pedal is designated t2.

The braking torque M _brake preferably drops in four steps, after the following time sequence, if the measured variable described in connection with FIGS. 1 to 3 has been determined at time t3, for example via the clutch state: a) The time period t2 to t3, in which the "driver brake pressure" is maintained, is 0 to 10 s, preferably a maximum of 2 s. b) The time period t3 to t4, in which the braking torque (the braking pressure, the braking force) depends on the slope required level 24 is reduced, is 0 to 2 s, preferably a maximum of 0.5 s c) The period t4 to t5 in which the braking torque (the braking pressure, the braking force) to a value between 50 and 80%, based on the Slope required level, preferably a maximum of 60%, is further reduced up to 3s, preferably a maximum of 0.7 to ls. D) The time period t5 to t6 in which the brake pressure is further reduced to zero is up to 10s, preferably maximum 2s.

The degradation can take place via the expotential function described in connection with FIG. 4, an approximation and / or the line course mentioned.

As FIG. 5 shows, the braking torque (or braking pressure, braking force) set by the driver is adopted by the starting aid, i.e. the target specification is equated with the driver specification and not reduced to the value required on the slope.

If one of the described deactivation criteria is now met (ie the driver releases the clutch without starting, for example, according to the description in FIG. 1), the braking torque is first reduced to the braking torque M _Han driving gear required on the slope. This first dismantling should take place as quickly as possible (eg via a fast ramp, ie with a large pressure reduction gradient).

The braking torque is to be reduced further in such a way that the driver can react to the rolling vehicle. An advantageous method for ending the traction help function provides that the setpoint specification for a braking torque M _Bre m _{s to} be set is specified as follows:

_Does the drive torque M _Äntr i _eb 25 of the drive motor reach the value of the slope output torque M _Han g acting on the vehicle? the setpoint for the braking torque M _B r _ems m time t7 can be reduced to zero. The advantage in this torque balance is that only the balance of the drive torque and the

Downhill torque comes into play. A possible excess of braking torque (e.g. due to safety thresholds or incorrectly assumed coefficients of friction or a braking torque set by the driver) is not reflected in this balance sheet. In this way it can be ensured that the vehicle is no longer held by the brake in the event of an excess of torque (in comparison to the slope) and moves in the direction desired by the driver. The reduction in the braking torque when building up a drive torque is designated by 26. The reduction takes place after comparison of the determined values of the braking torques M _B rem _s , time and M _Brem s, starting. instead, the degradation follows the lower braking torque.

FIG. 6 shows a device for ending an active starting aid function which supports starting a vehicle on an incline 33 by applying a braking torque holding the vehicle on the incline in the service brake 32 in accordance with external and / or internal variables, such as the Road inclination and / or conditions of the vehicle, builds up and maintains the inclusion of the large until a drive torque required for starting. The device has a determination unit 30 for determining a state for interrupting the active starting aid before the construction of a condition required for starting Drive torque according to at least one measurement variable, which reflects an operating state of the vehicle. Depending on at least one of the determination of the measurement variable described in connection with FIGS. 1 to 3, a control unit 31 controls the reduction of the braking torque of the service brake 32 when the measurement variable is determined in accordance with the method described above. The control unit controls the reduction of the braking torque after a predetermined time course in such a way that a vehicle reaction, in particular a drive-free (without engine power) vehicle movement, is triggered when the braking torque is reduced.

Claims

cLAIMS

Method for ending an active traction help function that supports starting a vehicle on an incline by applying a braking torque holding the vehicle on the incline in the service brake in accordance with external and / or internal variables, such as the downhill drive torque and / or operating states or . ' ^{_ ~} ; Characteristic values of the ^• vehicle, built up and maintained, including the large ones, until the build-up of a drive torque required for starting, characterized by the steps

Determining a state for interrupting the active start-up aid function before or during the build-up of a drive torque required for starting in accordance with at least one measurement variable which represents an operating state or characteristic values of a vehicle,

Reduction of the braking torque of the service brake when the measured variable is determined, and

A method according to claim 1, characterized in that a vehicle movement is triggered as a vehicle reaction in correlation to the measurement variable.

Method according to Claim 1 or 2, characterized in that the measured variable is a clutch state representing a release of a clutch pedal and / or a transmission status containing gear information and / or a brake pedal state representing a release of a brake pedal, for example a release switch of a Electromagnetically actuated brake booster, possibly including information about the actuation of an accelerator pedal, and / or an engine operating state that represents a shutdown of an engine and / or a vehicle operating state that represents a disconnection of at least one electrical supplier.

Method according to one of claims 1 to 3, characterized in that a set depending on an actuation of the brake pedal

Braking torque M _driver specification over a period of

0 to 10s, preferably up to a maximum of 2s, after the

Determination of the measurand is held by the starting aid.

A method according to any one of claims 1 to 4, characterized in that the braking torque M vorg _driver _a be in a period of maximum 2s on a Bremsmonent M _Brem s, Lim is reduced, which ngabtrieb accordance with the slope output torque M _Ha is determined.

Method according to one of claims 1 to 5, characterized in that a braking torque M _BL -ems, i built up in accordance with the downward slope torque M _Ha ngabtrieb is reduced by at least 20% in a period of maximum 3s.

A method according to claim 6, characterized in that the ¹ braking torque M _{BremS L} i _m reduced by at least 20% is reduced to zero in a time span of at most 10s ^' , preferably at most 2s.

8. The method according to any one of claims 1 to 7, characterized in that the braking torque M _Bre m _{s is} _reduced according to an exponential function.

9. The method according to claim 8, characterized in that the reduction of the braking torque M _Br e _ms after the following exponential function

^M Urans. Um ^{Σ ULU} ^ ^ norm ^ J-, with t _norm ⁼ 0 start of degradation, t _n orm = 1 end of degradation and K = factor between -2 and +2, preferably in the range between +1.2 and +1 ,8th.

10. The method according to any one of claims 1 to 9, characterized in that the reduction of the braking torque -M _brake takes place after approximation of an exponential function

11. Method for ending an active starting aid function that supports starting a vehicle on an incline by applying a braking torque that holds the vehicle on the incline in the service brake in accordance with external and / or internal variables, such as the road gradient and / or States of the vehicle, builds up and maintains the inclusion of the sizes up to the build-up of a drive torque required for starting, characterized in that, for a size that represents a signal representing a start, e.g. a drive torque, a according to the slope output torque M _Hanga btri _eb eigestelltes braking torque M _Brem s, in accordance with the relationship

or a braking torque M _driver set as a function of an actuation of the brake pedal according to the relationship

Hangahirieh - M drive

Urans ^' alirervoiγahe

Hanxnhtiϊeh is mined.

12. Device for ending an active starting aid function that supports starting a vehicle on an incline by applying a braking torque that holds the vehicle on the incline in the service brake in accordance with external and / or internal variables, such as the road inclination and / or States of the vehicle, builds up and maintains, including the large ones, until the build-up of a drive torque required for starting is characterized in that the device has a -. Determining unit (30) for determining a state for interrupting the active starting aid before or during the build-up of a drive torque required for starting according to at least one measurement variable, which represents an operating state or a characteristic value of the vehicle, contains that the starting aid contains a control unit (31) Controlling the reduction of the braking torque of the service brake (32) when the measured variable has been determined, and that the control unit controls the reduction of the braking torque after a predetermined time course in such a way that a vehicle reaction is triggered when the braking torque is reduced.