DE102009052227B4 - Method for operating a motor vehicle - Google Patents

Abstract

Method for operating a motor vehicle, wherein the motor vehicle comprises at least one drive unit, a transmission, a service brake and a parking brake, wherein a tendency of the motor vehicle determined by measurement or computation and the operation of the motor vehicle is controlled and / or regulated so that in an inclination located motor vehicle can be kept at a standstill, characterized in that when the inclination of the motor vehicle is less than a slope limit and a speed of the motor vehicle in the desired direction of travel is less than or reaches a defined speed limit, initially for a defined first period of time defined, maximum creep torque is provided, in which case, if during this defined first time period, the motor vehicle, despite the defined creeping torque does not creep in the desired direction of travel or if the motor vehicle despite the defined Creep torque opposite to the desired direction of travel rolls, the motor vehicle via the service brake by building and / or holding brake pressure is automatically held for a defined second period of time at a standstill, and wherein if there is no start-up during this defined second time period, after the defined second period of time, the motor vehicle is automatically held by the parking brake at a standstill.

Description

The invention relates to a method for operating a motor vehicle according to the preamble of claim 1.

From the DE 10 2004 030 795 A1 as well as the DE 101 21 158 A1 In each case, methods for operating a motor vehicle are known, by means of which, when a motor vehicle is operated on an incline, unwanted rolling back of the motor vehicle thereby avoided and thus the vehicle located in the inclination can be kept at a standstill that automates a brake of the motor vehicle is actuated. Although with these known from the prior art method, in principle, an undesired rolling back of an operated in a slope or inclination motor vehicle can be avoided, but it is not possible to control such operating situations safely and reliably, in which a in a slope or Tilt-operated motor vehicle from a drive in a desired direction of travel out so slowed down that a defined speed limit is reached or reached.

Furthermore, a method for operating a motor vehicle with the features of the preamble of the DE 199 49 203 A1 known.

The present invention has for its object to provide a novel method for operating a motor vehicle. This object is achieved by a method for operating a motor vehicle according to claim 1. According to claim 1, when the inclination of the motor vehicle is less than a tilt limit and a speed of the motor vehicle in the desired direction of travel is less than or reaches a defined speed limit value, first a defined maximum creeping torque is provided for a defined first period of time if, during this defined first time period, the motor vehicle does not creep in the desired direction of travel despite the defined creep torque or if the motor vehicle rolls contrary to the desired direction of travel despite the defined creep torque, the motor vehicle automatically via the service brake by building and / or holding brake pressure for a defined second time period is kept at a standstill, and wherein, if during this defined second period of time no start-up request, after the defined second time period, the motor vehicle by the parking brake au is held automatically at a standstill.

With the present invention, it is proposed, when a motor vehicle is operated at a relatively small inclination, which is smaller than an inclination limit, after reaching or falling below the defined speed limit initially for a defined first period of time to provide the defined maximum creep. Then, if during this defined first period of time the motor vehicle does not creep in the desired direction of travel despite the defined maximum creeping torque or if the motor vehicle rolls contrary to the desired direction of travel despite the defined maximum creep torque, the motor vehicle automatically shifts over the service brake for a defined second period of time kept at a standstill. Then, if there is no start-up during this defined second time period, the function of holding the motor vehicle is automatically transferred from the service brake to the parking brake, so then automatically after the defined second period, the motor vehicle is held by the parking brake at a standstill.

This makes it possible, when a motor vehicle during operation at a relatively low inclination reaches the standstill or approaches the same, to keep the motor vehicle reliably and safely at a standstill.

The speed of the motor vehicle is preferably determined on the basis of a rotational speed of a transmission shaft, in particular a transmission input shaft. The detection of the speed of the motor vehicle due to a rotational speed of the transmission shaft has the advantage that the speed of the motor vehicle can be determined with very high accuracy hereby.

According to an advantageous embodiment of the invention, when the inclination of the motor vehicle is greater than a limit and a speed of the motor vehicle in the desired direction of travel is less than a defined speed limit or reaches the same, first the motor vehicle on the service brake by building and / or holding is automatically held by the brake pressure for a defined third period of time at a standstill, wherein if no start-up is present during this defined third period of time, after the defined third time period, the motor vehicle is automatically held by the parking brake at a standstill.

Due to the fact that according to the advantageous development of the invention for a motor vehicle operated at a relatively high inclination, when the speed falls below or reaches a defined speed limit, the motor vehicle is first stopped by the parking brake via the service brake for a defined third time duration and with the defined third time duration via the parking brake can be achieved that a motor vehicle at a Operating in a relatively large slope and when operating in a relatively small slope for the driver shows a uniform behavior. Then, when the motor vehicle is operated in a relatively large pitch, in contrast to the operation in a relatively small pitch before building up the brake pressure on the service brake no maximum creeping torque is provided.

Preferably, the presence of the driver is monitored in the motor vehicle, wherein when it is determined that the driver is not in the motor vehicle, the holding of the motor vehicle stopped automatically by the service brake at standstill and the motor vehicle is automatically held by the parking brake automatically at a standstill. By monitoring the presence of the driver in the motor vehicle, the safety of the vehicle operation can be increased.

Preferred embodiments of the invention will become apparent from the dependent claims and the description below. Embodiments of the invention will be described, without being limited thereto, with reference to the drawings. Showing:

1 a view of an operated in a gradient in forward drive motor vehicle;

2 a view of an operated in a gradient in reverse drive motor vehicle;

3 a schematic view of a motor vehicle;

4 a first diagram to illustrate the method according to the invention; and

5 a second diagram to illustrate the method according to the invention.

The present invention relates to a method for operating a motor vehicle.

1 and 2 show a motor vehicle 10 which is in a slope or inclined roadway 11 is operated, in 1 the car 10 along the sloping roadway 11 is operated forward in the desired direction, while an obstacle 12 comes to a standstill.

In 2 on the other hand, the motor vehicle becomes 10 along the sloping roadway 11 operated backwards in the desired direction and also comes at an obstacle 12 comes to a standstill.

The present invention particularly relates to such details for operating a motor vehicle 10 with which the in 1 and 2 shown operating states of the motor vehicle 10 can be handled safely.

According to 3 includes a motor vehicle 10 at least one drive unit 13 , a gearbox 14 , a parking brake 15 and a service brake 16 that on an output 17 Act. With the service brake 16 acts on a brake pedal actuated by a driver 18 together. An also operated by the driver accelerator pedal 19 serves the driver's influence of the drive unit 13 delivered power. In the transmission 14 it is an automatic transmission or a double clutch.

In the operation of the motor vehicle 10 is either metrologically or mathematically the inclination of the motor vehicle 10 and thus the inclination of the roadway 11 on which the motor vehicle 10 operated, based on the determined inclination of the motor vehicle 10 the operation of the motor vehicle 10 to control and / or regulate.

When the inclination of the motor vehicle is less than an inclination limit value, for example less than 5%, and if further the speed of the motor vehicle 10 in the desired direction of travel is less than or equal to a defined speed limit, for example less than or equal to 2 km / h, or of the motor vehicle 10 according to 1 and 2 especially at an obstacle 12 comes to a standstill, first for a defined first period of time, for example for 90 seconds, for the motor vehicle 10 provided a defined, maximum creep.

Then, if during this defined first period of time the motor vehicle 10 despite the provided, defined creeping torque does not creep in the desired direction of travel, or if then the motor vehicle 10 despite the defined creep torque rolls opposite to the desired direction of travel, the motor vehicle 10 over the service brake 16 the same automatically held by automatically building and / or holding brake pressure for a defined second period of time, for example, for 5 minutes, at a standstill.

Then, if there is no start-up request during this defined second period of time, after the defined second period of time by the service brake 16 provided braking torque degraded and the motor vehicle 10 through the parking brake 15 automatically held at a standstill.

The defined maximum creep torque is then provided when the speed of the motor vehicle operated in the relatively small tilt 10 in the desired direction of travel without brake pedal actuation and without accelerator pedal actuation by the driver, becomes less than or equal to the defined speed limit value.

It is therefore within the meaning of the present invention that when a motor vehicle on a road 11 is operated, the inclination is smaller than a defined slope limit, and the motor vehicle comes to a standstill, in particular without brake operation and without accelerator pedal operation of the driver or its speed is less than a defined speed limit or the same, first to provide an applicable, maximum creep torque for the motor vehicle so as to check whether the motor vehicle can crawl again in the desired direction of travel. The applicable, maximum creep torque is provided for a defined first period of time. Then, if during the defined first period of time the motor vehicle does not creep, in spite of the existing maximum creeping torque, a holding function for the motor vehicle is triggered by first the motor vehicle 10 over the service brake 16 is held for a defined second period of time at a standstill, and after the defined second period of time holding the motor vehicle 10 at standstill by the parking brake 15 is accepted, and that is when there is no start-up during the second period.

As already stated, the motor vehicle 10 then over the service brake 16 maintained by building and / or holding brake pressure at a standstill, if during the defined first time period, the motor vehicle 10 despite the defined creep torque does not roll in the desired direction of travel with a defined crawl speed. This creep speed is greater by a defined offset value than the speed limit value below which the defined creep torque is provided. By this hysteresis-like offset value between these two speed values is achieved that the motor vehicle 10 not between the operating state in which the maximum creep torque is provided and the operating state in which the same via the service brake 16 is held, jumping back and forth.

Then, if the motor vehicle 10 during the defined second period of time via the service brake 16 is maintained at standstill by building and / or holding brake pressure, the previously built creep torque is reduced to zero. Likewise, if after the expiration of the second time period, the motor vehicle 10 over the parking brake 15 is held at a standstill, the creep torque kept at zero. This ensures that neither when the motor vehicle 10 through the service brake 16 is held at a standstill, even if the motor vehicle 10 through the parking brake 15 is held at a standstill, the creep torque provided against the respective brake 15 respectively. 16 is working.

The creep torque is thereby from the transmission 14 provided, namely as transmission output torque.

Further details of the method according to the invention, with which a motor vehicle 10 is operated in a relatively small inclination and in the relatively small inclination, for example, due to the in 1 and 2 shown obstacle 12 along the roadway 11 comes to a standstill, are described below with reference to the diagram of 4 described, in 4 over the time t several curves are shown.

This is illustrated by a curve 20 a speed of the motor vehicle 10 , which preferably consists of a speed of the transmission input shaft of the transmission 14 is determined.

A curve 21 Visualizes a speed of the drive unit or an engine speed. A curve 22 visualizes a creep torque provided by the method according to the invention. A curve 23 illustrates one in the context of the method according to the invention via the service brake 16 built-up brake pressure.

Temporally before a time t1 fall the course of the speed determined by the transmission input speed 20 of the motor vehicle and the course of the drive unit speed 21 together, wherein at time t1, with which the motor vehicle 10 goes into a regular creep operation, these two courses 20 and 21 separate each other. At time t1, in which the regular creep operation of the motor vehicle 10 starts, becomes a transmission status signal 24 set to a status X1, the regular creep operation of the motor vehicle 10 equivalent.

Between times t1 and t2, the motor vehicle slows down 10 like the speed 20 can be removed, in the regular creep operation increasingly, up to the time t2, the speed of the motor vehicle 10 a defined speed limit 25 below. Already before reaching the speed limit 25 becomes according to the curve 22 increasingly provided creep torque, so if at time t2 the speed 20 of the motor vehicle 10 the limit 25 reaches or falls below a defined, maximum creep torque is provided.

In the example of the diagram of 4 is this provided, maximum creep torque starting at the time t2 sufficiently large to the motor vehicle 10 to keep at a standstill. So can 4 be taken that according to the speed course 20 after reaching the standstill of the motor vehicle the same lingers at a standstill. At time t2, the transmission status signal becomes 24 set to a status X2, which provides the maximum creep torque through the transmission 14 and thus corresponds to a creep operation modified according to the invention.

The maximum creep torque is held starting with the time t2 for a defined first time period, this defined first time period being defined by the times t2 and t3.

Then, if during the defined time period between the times t2 and t3 despite providing the maximum creep torque as in the embodiment shown the 4 the car 10 remains at a standstill, is started at the end of the first period, ie at time t3, according to the curve 23 over the service brake 16 Build up and / or maintain a brake pressure, so that at time t4 of the service brake 16 automatically provided brake pressure is sufficiently coarse to the motor vehicle 10 to hold at a standstill, so starting from the time t4 the creep 22 is reduced and reduced to zero until time t5. At time t5, the transmission status signal becomes 24 set to a status X3 that corresponds to the degraded creep torque.

The time interval between the times t3 and t4 therefore visualizes a time offset between the first time duration, which ends at the time t3 and serves to provide the applicable maximum creep torque, and the second time period beginning at the time t4, in which the motor vehicle 10 over the service brake 16 by building up the brake pressure 23 is held at a standstill.

Accordingly, at time t4, the second time period in which the motor vehicle starts 10 over the service brake 16 is held at a standstill.

As already stated, if there is no start-up request during the second period of time, after expiry of this defined second time period the motor vehicle is no longer able to pass through the service brake 16 but rather by the parking brake 15 automatically held at a standstill, in which case at the end of the second time period, the brake pressure provided by the service brake 16 is reduced. This is in 4 no longer shown.

Rather shows 4 with the waveform 26 in that a further transmission status signal is set to a status Y1 between the times t3 and t5, which indicates that the first time period in which the motor vehicle is stopped above the applicable maximum creep torque has expired. At time t5, the creep torque is zero and the transmission status signal 26 is reset.

Another status signal 27 At time t4, a status Z1 is set, which is a holding of the motor vehicle 10 at standstill by the service brake 16 equivalent. This state of the motor vehicle is preferably displayed to a driver via a display in the vehicle cockpit.

In addition to the already mentioned curves 20 . 21 . 22 and 23 as well as status signals 24 . 26 and 27 is in 4 furthermore, the status of a timer signal 28 shown, wherein the timer according to the timer signal 28 begins to run at time t2, and therefore the first time duration in which the transmission 14 the applicable maximum creep torque is provided monitored.

Further shows 4 for the speed signal 20 of the motor vehicle a hysteresis range 29 , The lower limit of this hysteresis range 29 is determined by the speed limit 25 formed when falling below or reaching the transmission 14 the applicable creep torque is provided. An upper limit 30 of the hysteresis area 29 is defined by the already mentioned, defined offset value, that is by a creeping speed, beyond which the provision of the applicable maximum creep torque would be terminated.

5 shows a development of the method according to the invention, for the case of which via the transmission 14 provided, applicable, maximum creeping torque is insufficient to relatively small inclination of the motor vehicle 10 to keep the same at a standstill. So shows 5 with the area 31 that the motor vehicle 10 in spite of the maximum creep torque provided beginning at time t2, rolls back in the opposite direction to the desired direction of travel, in which case a limit value is established at time t6 32 is reached or overshadow for a roll-back, so then holding the motor vehicle 10 over the transmission 14 aborted using the applied, applied maximum creep torque and at time t6 with building up the brake pressure via the service brake 16 is started, so that the rolling back of the motor vehicle 10 is prevented. So shows 5 that the motor vehicle 10 At time t7 almost completely was brought to a standstill again. Upon detection of unwanted rollback of the motor vehicle 10 becomes the status signal at time t6 24 set to a status X4, which is maintained until the time t7 rollback was prevented.

A suppression of the rolling back of the motor vehicle 10 is then detected when the speed of the same again a limit 33 reaches or exceeds, with the two limits 32 and 33 are spaced apart by an offset value to form a hysteresis range, to jump back and forth between the status through which of the transmission 14 the maximum creep torque is provided, and the status via which via the service brake 16 Brake pressure is built up to avoid.

Then, if a motor vehicle 10 is operated at an inclination that is greater than the inclination limit, and if further the speed of the motor vehicle 10 in the desired direction of travel is less than a defined speed limit or reaches the same, is without first providing a maximum creeping torque immediately the motor vehicle 10 first via the service brake 16 by holding and / or holding brake pressure automatically held for a defined third period of time at a standstill, wherein if there is no start-up during this defined third time period, after the defined third time period, the motor vehicle 10 through the parking brake 15 automatically held at a standstill. The third time period preferably corresponds in terms of their length of the first time period.

According to the invention, therefore, the provision of the maximum creeping torque after reaching or falling below a speed limit is made dependent on the inclination of the motor vehicle 10 is operated. At a relatively small incline, the maximum creep torque is provided, whereas at a relatively large incline it is not provided, but directly the motor vehicle via the service brake 16 and subsequently via the parking brake 15 is held.

The car 10 is then over the service brake 16 held at a standstill when, in the relatively large inclination, the speed of the motor vehicle 10 in the desired direction of travel without or with brake pedal operation and / or without or with accelerator pedal operation by the driver is less than the aforementioned, defined speed limit value or reaches the same.

During the entire process according to the invention, according to an advantageous development of the invention, the presence of the driver in the motor vehicle is monitored. Then, when it is determined that the driver is in the vehicle, the vehicle becomes 10 held at a standstill, via the service brake 16 and subsequently via the parking brake 15 , If, on the other hand, it is determined that the driver is no longer in the motor vehicle, the holding of the motor vehicle is via the service brake 16 automatically canceled and the motor vehicle 10 directly through the parking brake 15 automatically held at a standstill.

For monitoring the presence of the driver in the motor vehicle 10 Is checked if a driver's door of the motor vehicle 10 is closed, or whether a driver's belt of the motor vehicle is closed, or whether the accelerator pedal 19 of the motor vehicle is actuated or whether the brake pedal 18 of the motor vehicle 10 is pressed. Then, if one or more of these conditions are not met, it is concluded that the driver is not in the motor vehicle and as a result the motor vehicle is kept at a standstill via the parking brake.

Then, if during the already mentioned first time period and / or second time duration and / or third time duration, a driver request is present, for example by pressing the accelerator pedal 19 or by operating a selector lever of the gearbox 14 , is holding the motor vehicle 10 by providing the creep torque or by building and holding brake pressure of the service brake 16 automatically canceled to allow a start of the motor vehicle.

Claims (14)

Method for operating a motor vehicle, wherein the motor vehicle comprises at least one drive unit, a transmission, a service brake and a parking brake, wherein a tendency of the motor vehicle determined by measurement or computation and the operation of the motor vehicle is controlled and / or regulated so that in an inclination located motor vehicle can be kept at a standstill, characterized in that when the inclination of the motor vehicle is less than a slope limit and a speed of the motor vehicle in the desired direction of travel is less than or reaches a defined speed limit, initially for a defined first period of time defined, maximum creep torque is provided, in which case, if during this defined first time period, the motor vehicle, despite the defined creeping torque does not creep in the desired direction of travel or if the motor vehicle despite the defined Creep torque opposite to the desired direction of travel rolls, the motor vehicle on the service brake by building and / or Holding brake pressure is automatically held for a defined second period of time at a standstill, and wherein, if there is no start-up during this defined second time period, after the defined second time period, the motor vehicle is automatically held by the parking brake at a standstill. A method according to claim 1, characterized in that the defined, maximum creep torque is provided when, in the inclination, which is less than a slope limit, the speed of the motor vehicle in the desired direction without brake pedal operation and without accelerator operation by the driver is smaller than the defined Speed limit is reached or the same. A method according to claim 1 or 2, characterized in that the defined maximum creep torque is provided by the transmission as a transmission output torque. Method according to one of claims 1 to 3, characterized in that the speed of the motor vehicle is determined on the basis of a rotational speed of a transmission shaft. Method according to one of claims 1 to 4, characterized in that the motor vehicle is then held on the service brake by building and / or holding brake pressure at a standstill, if during the defined first period of time the motor vehicle not despite the defined creep in the desired direction with crawls at a defined creeping speed which is greater than the speed limit value by a defined offset value, below which the defined creep torque is provided when it is fallen below or reached. Method according to one of claims 1 to 5, characterized in that when the motor vehicle is held by the service brake by building and / or holding brake pressure at a standstill, the creep torque is reduced to zero. A method according to claim 6, characterized in that when the motor vehicle is subsequently held in the standstill via the parking brake, the creep torque is kept at zero. Method according to one of claims 1 to 7, characterized in that when the inclination of the motor vehicle is greater than the inclination limit and a speed of the motor vehicle in the desired direction of travel is less than the defined speed limit or reaches the same, first the motor vehicle via the service brake is maintained at standstill automatically by building and / or holding brake pressure for a defined third period of time, wherein when there is no start-up during this defined third time period, after the defined third time period, the motor vehicle is automatically held by the parking brake at a standstill. A method according to claim 8, characterized in that the motor vehicle is then held on the service brake at a standstill, if at an incline greater than the slope limit, the speed of the motor vehicle in the desired direction without or with brake pedal operation and / or without or with accelerator pedal operation by the driver is less than or equal to the defined speed limit. Method according to one of claims 1 to 9, characterized in that the presence of the driver is monitored in the motor vehicle, wherein when it is determined that the driver is not in the motor vehicle, holding the motor vehicle stopped at standstill by the service brake and the motor vehicle is automatically held by the parking brake automatically at a standstill. A method according to claim 10, characterized in that it is then closed to the presence of the driver in the motor vehicle when a driver's door of the motor vehicle is closed or when a driver's belt is closed or when an accelerator pedal is actuated or when a brake pedal is actuated, and then, if one or more of these conditions is not fulfilled, it is concluded that the driver is not in the vehicle. Method according to one of claims 1 to 11, characterized in that when there is a start-up request during the first time period, the creep torque is replaced by a starting torque dependent on the driver's request. Method according to one of claims 1 to 12, characterized in that when there is a start-up request during the second time period, the brake pressure of the service brake is automatically reduced to allow a start with a dependent on the driver's request starting torque. Method according to one of claims 8 to 13, characterized in that when there is a start-up request during the third time period, the brake pressure of the service brake is automatically reduced to allow a start with a dependent on the driver's request starting torque.

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