METHOD FOR THE AUTOMATIC PARAMETERIZATION OF A BRAKING SYSTEM

Abstract

In a method for the automatic parameterization of a braking system in a vehicle, a brake pressure profile is predefined as a test run during a test drive operation, and the wheel slip which thereafter arises is ascertained. If the wheel slip is outside a permissible value range, the brake pressure is modified and a new test run is carried out.

Claims

1-13. (canceled)

14. A method for automatic parameterization of a braking system in a vehicle, the method comprising the following steps: predefining a brake pressure profile as a test run during a test drive operation; ascertaining a wheel slip which arises from the brake pressure profile at at least one wheel of the vehicle; determining, when a wheel slip value or a gradient of the wheel slip is outside a permissible value range, a point in time in the brake pressure profile at which a brake pressure or a gradient of the brake pressure is a cause of the impermissible wheel slip value or the impermissible gradient of the wheel slip; and redefining a modified brake pressure profile as a new test run, parameters at the ascertained point in time of the modified brake pressure profile being stored and used to parameterize the braking system when the wheel slip value or the gradient of the wheel slip of a wheel slip profile which arises from the modified brake pressure profile, is within the permissible value range.

15. The method as recited in claim 14, wherein the point in time in the brake pressure profile, at which the brake pressure or the gradient of the brake pressure is the cause of the impermissible wheel slip value or the gradient of the wheel slip, is determined directly from the brake pressure profile.

16. The method as recited in claim 14, wherein the point in time in the brake pressure profile, at which the brake pressure or the gradient of the brake pressure is the cause of the impermissible wheel slip value or the gradient of the wheel slip, is determined from a system variable other than the brake pressure profile.

17. The method as recited in claim 16, point is time is determined from an activation/deactivation profile of the brake pressure.

18. The method as recited in claim 14, wherein the brake pressure and/or the gradient of the brake pressure is/are increased or decreased as parameters during a change of the brake pressure profile.

19. The method as recited in claim 14, wherein at least one parameter characterizing the brake pressure profile is changed by an established absolute amount during a change of the brake pressure profile.

20. The method as recited in claim 14, wherein the predefined brake pressure profile is assigned to a particular wheel rotational speed change/wheel slip combination.

21. The method as recited in claim 20, wherein the predefined brake pressure profile depends on further characteristic values or system variables, including a wheel slip change or an abrupt change in wheel rotational speed.

22. The method as recited in claim 14, wherein the method is perform during real vehicle operation on a road.

23. The method as recited in claim 14, wherein the method is perform on a roller dynamometer.

24. A control unit for activating settable components of a braking system in a vehicle, the control unit configured to automatically parameterize the braking system, the control unit configured to: predefine a brake pressure profile as a test run during a test drive operation; ascertain a wheel slip which arises from the brake pressure profile at at least one wheel of the vehicle; determine, when a wheel slip value or a gradient of the wheel slip is outside a permissible value range, a point in time in the brake pressure profile at which a brake pressure or a gradient of the brake pressure is a cause of the impermissible wheel slip value or the impermissible gradient of the wheel slip; and redefine a modified brake pressure profile as a new test run, parameters at the ascertained point in time of the modified brake pressure profile being stored and used to parameterize the braking system when the wheel slip value or the gradient of the wheel slip of a wheel slip profile which arises from the modified brake pressure profile, is within the permissible value range.

25. A braking system in a vehicle, comprising: a control unit for activating settable components of the braking system, the control unit configured to automatically parameterize the braking system, the control unit configured to: predefine a brake pressure profile as a test run during a test drive operation; ascertain a wheel slip which arises from the brake pressure profile at at least one wheel of the vehicle; determine, when a wheel slip value or a gradient of the wheel slip is outside a permissible value range, a point in time in the brake pressure profile at which a brake pressure or a gradient of the brake pressure is a cause of the impermissible wheel slip value or the impermissible gradient of the wheel slip; and redefine a modified brake pressure profile as a new test run, parameters at the ascertained point in time of the modified brake pressure profile being stored and used to parameterize the braking system when the wheel slip value or the gradient of the wheel slip of a wheel slip profile which arises from the modified brake pressure profile, is within the permissible value range.

26. A vehicle, comprising: a braking system including a control unit for activating settable components of the braking system, the control unit configured to automatically parameterize the braking system, the control unit configured to: predefine a brake pressure profile as a test run during a test drive operation; ascertain a wheel slip which arises from the brake pressure profile at at least one wheel of the vehicle; determine, when a wheel slip value or a gradient of the wheel slip is outside a permissible value range, a point in time in the brake pressure profile at which a brake pressure or a gradient of the brake pressure is a cause of the impermissible wheel slip value or the impermissible gradient of the wheel slip; and redefine a modified brake pressure profile as a new test run, parameters at the ascertained point in time of the modified brake pressure profile being stored and used to parameterize the braking system when the wheel slip value or the gradient of the wheel slip of a wheel slip profile which arises from the modified brake pressure profile, is within the permissible value range.

27. A non-transitory machine-readable storage on which is stored a computer program for automatic parameterization of a braking system in a vehicle, the computer program, when executed by a control unit, causing the control unit to perform the following steps: predefining a brake pressure profile as a test run during a test drive operation; ascertaining a wheel slip which arises from the brake pressure profile at at least one wheel of the vehicle; determining, when a wheel slip value or a gradient of the wheel slip is outside a permissible value range, a point in time in the brake pressure profile at which a brake pressure or a gradient of the brake pressure is a cause of the impermissible wheel slip value or the impermissible gradient of the wheel slip; and redefining a modified brake pressure profile as a new test run, parameters at the ascertained point in time of the modified brake pressure profile being stored and used to parameterize the braking system when the wheel slip value or the gradient of the wheel slip of a wheel slip profile which arises from the modified brake pressure profile, is within the permissible value range.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 shows a schematic representation of a hydraulic braking system.

[0023] FIG. 2 shows an assignment chart for different brake pressure profiles as a function of the wheel rotational speed change of the wheel slip.

[0024] FIG. 3 shows a diagram including the activation/deactivation profile of the brake pressure, including the wheel slip profile, including the profile according to the assignment chart according to FIG. 1, and including the brake pressure profile, FIG. 3 illustrating the case of an excessively high wheel slip.

[0025] FIG. 4 shows a representation corresponding to FIG. 3, illustrated for too low a brake pressure.

[0026] FIG. 5 shows a further representation according to FIGS. 3 and 4 (without activation/deactivation profile of the brake pressure), illustrated for too steep an increase of the wheel slip.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0027] In the figures, identical objects are provided with identical reference numerals.

[0028] Hydraulic braking system 1 illustrated in FIG. 1 is designed as a vehicle brake for a vehicle and includes a front axle brake circuit 2 and a rear axle brake circuit 3 for supplying and activating wheel brake devices 9 at each wheel of the vehicle with the aid of a brake fluid under hydraulic pressure. The two brake circuits 2, 3 are connected to a shared main brake cylinder 4, which is supplied with brake fluid via a brake fluid reservoir 5. The main brake cylinder piston within main brake cylinder 4 is actuated by the driver via brake pedal 6, which is measured by the pedal travel effectuated by the driver with the aid of a pedal travel sensor 7. A brake booster 10 is situated between brake pedal 6 and main brake cylinder 4, which includes, for example, an electric motor, which actuates main brake cylinder 4 preferably via a gearing (iBooster).

[0029] The actuation of brake pedal 6 measured by pedal travel sensor 7 is transferred as a sensor signal to a control unit 11, in which control signals are generated for activating brake booster 10. The supply of brake fluid to wheel brake devices 9 takes place in each brake circuit 2, 3 via different switching valves, which, together with further assemblies, are part of a brake hydraulic system 8.

[0030] The braking system must be adapted to the particular vehicle for completion. For this purpose, the braking system must be parameterized, i.e., different parameters of the braking system are established specific to the vehicle. To keep the complexity for the parameterization as low as possible, and to carry out the parameterization as fast as possible, an automated method is used, in which different brake pressure profiles are predefined as test runs during a test drive operation, and the wheel slip, which thereafter arises at one or multiple wheels of the vehicle, is ascertained and compared with a permissible value range. If the wheel slip is outside the permissible value range, the point in time in the brake pressure profile is determined, at which the brake pressure or the gradient of the brake pressure is the cause of the impermissible wheel slip value. The brake pressure profile is modified, the modified brake pressure profile being predefined as a new test run. The change of the brake pressure profile takes place by modifying at least one parameter, the parameters of the modified brake pressure profile being stored and used permanently for parameterizing the braking system, if the wheel slip value which arises during the modified brake pressure profile is within the permissible value range. The gradient of the wheel slip may also be considered additionally or alternatively to the wheel slip value.

[0031] All method steps run automatically in a control unit of the braking system, i.e., the selection of a brake pressure profile, the execution of a test run and the ascertainment of the wheel slip or the gradient of the wheel slip which arises, the determination of the point in time in the brake pressure profile, at which the brake pressure or the gradient of the brake pressure is the cause of the impermissible wheel slip value or the impermissible gradient of the wheel slip, the modification of the brake pressure profile by modifying at least one parameter of the braking system, the execution of a new test run based on the modified brake pressure profile, the determination of the wheel slip value or the gradient of the wheel slip which thereafter arises, and the storage of the parameters of the modified brake pressure profile for the case that the wheel slip value or the gradient of the wheel slip is within the permissible value range.

[0032] An assignment chart for a multiplicity of value pairs of wheel rotational speed changes a.sub.W (Y axis) and wheel slip s.sub.L (X axis) is illustrated in FIG. 2. A total of 72 different combinations are defined in the exemplary embodiment, each value combination of wheel rotational speed change or wheel acceleration a.sub.W and wheel slip s.sub.L additionally being associated with further system variables or characteristic values, which are assigned to the particular combination. The further system variables or characteristic values are, for example, the derivation of the wheel slip.

[0033] The time-dependent profile of different characteristic values and system variables of the braking system when specifying a brake pressure profile p is illustrated in FIG. 3. The activation and deactivation of the brake pressure are illustrated by activation/deactivation profile EA.sub.P. As a result of brake pressure profile p, a wheel slip s.sub.L arises, to which the profile of assignment chart a.sub.W/s.sub.L according to FIG. 2 is assigned. In the encircled area, wheel slip s.sub.L takes on a maximum, which is above a permissible value range. Consequently, wheel slip s.sub.L is too great at this point.

[0034] The cause of the too high wheel slip is found in too high brake pressure p, which is achieved at an earlier point in time, as is also apparent from the encircled positions during the course of activation/deactivation profile EA.sub.P of brake pressure p as well as assignment chart a.sub.W/s.sub.L. Brake pressure p reaches too high a maximum. To reduce this maximum and, associated therewith, to also limit maximum wheel slip s.sub.L to a lower value, for example the deactivation point in time of the brake pressure according to profile EA.sub.P may be brought forward, so that the brake pressure is built up only over a shorter period of time. A lower brake pressure p and consequently also a lower wheel slip s.sub.L, subsequently arises.

[0035] The shortening of the brake pressure buildup represents a parameter, which may be automatically modified according to the method. A changed brake pressure profile may thereafter be predefined as a new test run, on the basis of which wheel slip s.sub.L is ascertained. If maximum wheel slip s.sub.L is now within a permissible magnitude, the corresponding parameters may be permanently stored. The storage takes place under value pair a.sub.W/s.sub.L, which is encircled.

[0036] A further exemplary embodiment is illustrated in FIG. 4, in which longitudinal slip s.sub.L of the vehicle wheel takes on a minimum within the encircled area, which is attributable to an excessively low brake pressure p occurring at an earlier time in the area which is also encircled. In the method, brake pressure p may be automatically increased in the brake pressure profile, for example by an earlier activation in activation/deactivation profile EA.sub.P of the brake pressure, after which a higher wheel slip s.sub.L arises. If this higher wheel slip s.sub.L is now within a permissible value range, the parameterization may be permanently stored in the corresponding field in assignment chart a.sub.W/s.sub.L.

[0037] In the further exemplary embodiment according to FIG. 5, the gradient of wheel slip s.sub.L in the encircled area is too high and is thus outside the permissible value range. This is attributable to a corresponding pressure increase in brake pressure profile p in the encircled area, to which the encircled value pair in assignment chart a.sub.W/s.sub.L corresponds. Due to a corresponding reduction of the pressure increase, a reduction of the wheel slip gradient may also be reached, and a lowering of the wheel slip gradient into the permissible value range may be achieved. The corresponding parameterization may be permanently stored in the value pair of assignment chart a.sub.W/s.sub.L.