METHOD FOR A SPEED CONTROLLER

Abstract

A method for a speed controller for a motor vehicle, wherein a speed prescription is set by the driver and automatic adjustment of the speed to the speed prescription is carried out at least by setting an engine torque prescription, wherein at the start of the speed control the engine torque prescription is set to an initial value, wherein the initial value is determined in accordance with at least one parameter.

Claims

1. A method for a speed controller for a motor vehicle, comprising: setting a speed prescription by a driver; carrying out an automatic adjustment of the speed to the speed prescription at least by setting an engine torque prescription; and at the start of the speed control setting the engine torque prescription to an initial value at the start of the speed control, wherein the initial value is determined in accordance with at least one parameter.

2. The method as claimed in claim 1, wherein activation of a starting aid function is monitored, and wherein, if the starting aid function is activated, a braking torque value is transmitted from the starting aid function to the speed controller and the initial value is determined as a function of the braking torque value.

3. The method as claimed in claim 1, further comprising: acquiring a roadway inclination and/or a quality of the underlying surface, and using the roadway inclination and/or the quality of the underlying surface as parameters for the determination of the initial value.

4. The method as claimed in claim 3, further comprising: determining a first adaptation value in accordance with the roadway inclination, determining a second adaptation value in accordance with the quality (U) of the underlying surface, and wherein using the sum or the product of the first adaptation value and of the second adaptation value for the determination of the initial value.

5. The method as claimed in claim 3, wherein a table with engine torque initial values as a function of the parameters of roadway inclination, quality of the underlying surface and speed prescription is stored in a memory medium and the initial value is determined on the basis of the table.

6. The method as claimed in claim 1, wherein automatic deceleration of the vehicle to the stationary state is carried out by the speed controller if the speed prescription is zero.

7. The method as claimed in claim 1, wherein the speed controller is configured for adjustment to speeds below approximately 30 km/h, in particular for an off-road mode.

8. The method as claimed in claim 7, wherein a transfer to a second speed controller takes place if the speed prescription exceeds a limiting value.

9. The method as claimed in claim 2, further comprising: acquiring a roadway inclination and/or a quality of the underlying surface, and using the roadway inclination and/or the quality of the underlying surface as parameters for the determination of the initial value.

10. The method as claimed in claim 7, wherein a transfer to a second speed controller takes place if the speed prescription exceeds 30 km/h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] An exemplary embodiment of an aspect of the invention will be discussed in more detail on the basis of two drawings. In the drawing, in a highly schematic illustration:

[0022] FIG. 1 shows a schematic diagram of an exemplary speed controller;

[0023] FIG. 2 shows a device for carrying out the exemplary method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] FIG. 1 shows a schematic diagram of an exemplary speed controller.

[0025] In the basic state 1, the speed controller is initially switched off. If the driver actuates a first switch (illustrated by means of arrow 10 in FIG. 1) with the brake pedal depressed, the system changes into a standby mode 2. In the standby mode 2 there is still no request for braking torque or engine torque.

[0026] If the driver activates the system in the stationary state, by releasing the brake (arrow 12) he can change into an active mode 4 and bring about starting, wherein the vehicle accelerates to a previously set target speed (speed prescription). The standard target speed is a preset minimum target speed, but it can be changed by the driver before the starting.

[0027] However, a transfer into the active mode advantageously takes place only if the driver releases the brake within a predefined time period and the vehicle is not in a parking mode.

[0028] The target speed (in the range from the minimum target speed to the maximum target speed) is set with pushbutton keys set+ and set, wherein these can both be pressed briefly in order to change the speed incrementally, and pressed and held down in order to bring about a more rapid change.

[0029] If activation occurs during travel (arrow 11), the system initially changes into a second standby mode 3. The automatic control of the speed can then start in that the driver actuates the set+ switch (arrow 13) and the control therefore goes into the active mode 4.

[0030] The current vehicle speed is initially adapted as the preset target speed. The control advantageously starts only when the current vehicle speed is within a predefined permitted speed range.

[0031] During operation, the speed controller can be switched off again at any time by pressing the first switch.

[0032] If a situation in which the current vehicle speed is higher than the target speed occurs while the speed controller is active, the current vehicle speed can be adapted as the new target speed by pressing set+.

[0033] Conversely, in a situation in which the current vehicle speed is lower than the target speed, said speed can be adapted as the new target speed by pressing set.

[0034] If the driver actuates the accelerator while the speed controller is active, and as a result reduces the actual speed of the vehicle, the target speed follows the actual speed. When the brake is released, adjustment to the new target speed then takes place.

[0035] The actuation of the accelerator pedal while the speed controller is active does not bring about a change in the target speed, but can cause the vehicle to accelerate. If the pedal is released, adjustment to the target speed takes place again.

[0036] When the speed controller is active, the control can be (temporarily) interrupted by means of a cancel pushbutton key, wherein the target speed is not deleted but rather buffered.

[0037] After previous pressing of the cancel pushbutton key, it is possible to return to the previously interrupted control (including the buffered target speed) using a resume pushbutton key.

[0038] If the speed controller is active (mode 4) and the vehicle is moving at the minimum target speed, the driver can stop by keeping the key set pressed (arrow 14). Automatic deceleration of the vehicle to the stationary state (state 5) is carried out by the speed controller. If the driver releases the key set again (arrow 15), the speed controller returns to the active mode 4 and continues the control with the minimum target speed.

[0039] FIG. 2 shows a device for carrying out the exemplary method. A speed controller 24 receives a braking torque value MB from a starting aid 20 (HSA) if the latter is active.

[0040] The driver sets a speed prescription v.sub.soll by means of an operator control element 23. The operator control element can comprise a plurality of pushbutton keys, for example a first switch for activating the function, and switches set+ and set for setting the speed prescription v.sub.soll. The speed prescription v.sub.soll is transferred to the speed controller 24.

[0041] The speed controller 24 also receives information about a roadway inclination S from an inclination sensor 21 and a quality U of an underlying surface 22. The quality of the underlying surface is preferably either determined on the basis of a surroundings sensor system, or set by the driver by means of an operator control element.

[0042] The inclination S is advantageously determined by means of a G sensor while the vehicle is in the stationary state.

[0043] On the basis of the received information about the braking torque value M.sub.M of the starting aid, the roadway inclination S, the quality U of the underlying surface and the speed prescription v.sub.soll, the speed controller 24 determines a suitable initial value for the engine torque prescription M.sub.M and transfers it to an actuator 25 which sets the engine torque in accordance with the engine torque prescription M.sub.M when the speed controller is activated.

[0044] The necessary engine torque for the prevailing condition of the roadway is stored, for example, in a table in which the roadway inclination S, the quality U of the underlying surface, the speed prescription v.sub.soll and the necessary engine torque M.sub.M re stored. These values are run in driving trials on the corresponding roadways and inclinations. The initialization value can then be correspondingly composed, e.g. by adding a first adaptation value which is acquired in accordance with the inclination S and a second adaptation value which is acquired in accordance with the quality U of the underlying surface (e.g. uphill in sand), or only part of the inclination or part of the roadway.

[0045] An initial value, which is used as an engine torque prescription when the speed controller is activated, is preferably determined continuously by means of the speed controller.