DE102015220523A1 - Method for operating the brakes of a vehicle - Google Patents

Abstract

The invention relates to a method for operating the brakes in a vehicle, comprising the following steps: detecting a desired braking of the vehicle, calculating desired brake parameters, including brake pressure and pressure distribution, for bringing about the desired braking, activating a brake noise reduction function, in the following BGR function, depending on the desired braking parameters, driving the brakes with the desired braking parameters when the BGR function is not activated, determining alternative braking parameters that result in lower brake noise than the desired braking parameters when the BGR Function and activating the brakes with the alternate brake parameters when the BGR function is activated.

Description

The invention relates to a method for operating the brakes in a vehicle. In particular, this is a two-lane road vehicle. Furthermore, the invention relates to a brake system for a vehicle for carrying out the method.

Brakes in vehicles, especially hydraulic disc brakes, produce unwanted brake noise under certain operating conditions. The brake noise leads to a comfort impairment for the vehicle occupants.

It is an object of the present invention to provide a method for operating the brakes, on the one hand reduces the brake noise and on the other hand enables safe braking of the vehicle.

The object is achieved by the features of the independent claims. The dependent claims relate to advantageous embodiments of the invention.

• (i) Zunächst erfolgt ein Erfassen der Soll-Bremsung des Fahrzeuges. Bei dem Fahrzeug handelt es sich insbesondere um ein zweispuriges Straßenfahrzeug. In dem Fahrzeug sind insbesondere vier Räder mit jeweils einer eigenen Bremse vorgesehen. Die Bremsanlage ist vom Bremspedal entkoppelt. Dies bedeutet, dass der jeweilige Bremsdruck unabhängig von der Pedalstellung eingestellt werden kann. Die Soll-Bremsung gibt an, mit welchen Verzögerungswerten und über welche Zeit das Fahrzeug abgebremst werden soll.
• (ii) Basierend auf der erfassten Soll-Bremsung werden die Soll-Bremsparameter berechnet. Die Soll-Bremsparameter umfassen zumindest den Bremsdruck und die entsprechende Druckverteilung, die zur Herbeiführung der Soll-Bremsung notwendig sind. Je nach Ausgestaltung der Bremsanlage können die Bremsdrücke der einzelnen Bremsen der Räder achsweise, raddiagonal oder radindividuell verändert werden. Bei dem Beispiel der achsweisen Ansteuerung umfassen die Soll-Bremsparameter einen ersten Bremsdruck für die Vorderachse und einen zweiten Bremsdruck für die Hinterachse. Bei dem Beispiel der raddiagonalen Ansteuerung umfassen die Soll-Bremsparameter einen ersten Bremsdruck für vorne rechts/hinten links und einen zweiten Bremsdruck für vorne links/hinten rechts. Bei dem dritten Beispiel, mit der radindividuellen Ansteuerung können die Soll-Bremsparameter bis zu vier unterschiedliche Bremsdrücke umfassen.
• (iii) Im nächsten Schritt wird überprüft, ob eine Bremsgeräuschreduzierung-Funktion aktiviert werden kann. Im Folgenden wird diese Funktion als BGR-Funktion bezeichnet. In erster Linie wird überprüft, ob bei dem berechneten Soll-Bremsparametern ein erhöhtes Bremsgeräusch zu erwarten ist. Diese Überprüfung funktioniert beispielsweise durch Vergleichen der berechneten Soll-Bremsparameter mit hinterlegten Werten. So kann in Abhängigkeit der Soll-Bremsparameter die BGR-Funktion aktiviert werden. Im Rahmen der Erfindung wird auch noch beschrieben, dass unter Umständen ein Aktivieren der BGR-Funktion, beispielsweise aus sicherheitsrelevanten Überlegungen, unterdrückt werden kann.
• (iv) Wenn die BGR-Funktion nicht aktiviert wird, erfolgt ein Ansteuern der Bremsen mit den Soll-Bremsparametern.
• (v) Wenn die BGR-Funktion aktiviert wird, erfolgt im nächsten Schritt eine Ermittlung von alternativen Bremsparametern. Diese alternativen Bremsparameter führen zu geringeren Bremsgeräuschen als die Soll-Bremsparameter. Im Rahmen der Ermittlung der alternativen Bremsparameter werden die Bremsdrücke und/oder die Druckverteilung verändert. Dabei wird insbesondere darauf geachtet, dass mit den alternativen Bremsparametern im Wesentlichen dieselbe Soll-Bremsung möglich ist wie mit den Soll-Bremsparametern. Bevorzugt sind für diese Funktion Werte und/oder Kennfelder und/oder Berechnungsformeln im Fahrzeug hinterlegt, aufgrund derer die Ermittlung der alternativen Bremsparameter basierend auf den Soll-Bremsparametern möglich ist.
• (vi) Im letzten Schritt erfolgt ein Ansteuern der Bremsen mit den alternativen Bremsparametern.

Thus, the invention is solved by the following method:

• (i) First, the target braking of the vehicle is detected. The vehicle is in particular a two-lane road vehicle. In particular, four wheels, each with its own brake, are provided in the vehicle. The brake system is decoupled from the brake pedal. This means that the respective brake pressure can be adjusted independently of the pedal position. The setpoint braking indicates with which deceleration values and over which time the vehicle should be decelerated.
• (ii) Based on the detected desired braking, the desired braking parameters are calculated. The desired braking parameters comprise at least the brake pressure and the corresponding pressure distribution which are necessary for bringing about the desired braking. Depending on the design of the brake system, the brake pressures of the individual brakes of the wheels can be changed by way of axle, wheel-diagonal or wheel-individually. In the example of the axle-wise control, the desired brake parameters comprise a first brake pressure for the front axle and a second brake pressure for the rear axle. In the example of radiodiagnostic control, the desired brake parameters include a first brake pressure for front right / rear left and a second brake pressure for front left / rear right. In the third example, with the wheel-individual control, the desired braking parameters can include up to four different brake pressures.
• (iii) In the next step, it is checked whether a brake noise reduction function can be activated. In the following, this function is called a BGR function. In the first place, it is checked whether an increased brake noise is to be expected in the calculated desired brake parameters. This check works, for example, by comparing the calculated setpoint brake parameters with stored values. Thus, the BGR function can be activated depending on the desired braking parameter. In the context of the invention is also described that under certain circumstances activating the BGR function, for example, for safety-relevant considerations, can be suppressed.
• (iv) If the BGR function is not activated, the brakes are controlled using the desired braking parameters.
• (v) When the BGR function is activated, the next step is to determine alternative brake parameters. These alternative brake parameters result in lower brake noise than the desired brake parameters. As part of the determination of the alternative brake parameters, the brake pressures and / or the pressure distribution are changed. Particular attention is paid to the fact that with the alternative brake parameters essentially the same desired braking is possible as with the desired braking parameters. Values and / or maps and / or calculation formulas are preferably stored in the vehicle for this function, on the basis of which the determination of the alternative brake parameters based on the desired braking parameters is possible.
• (vi) In the last step, the brakes are controlled using the alternative brake parameters.

The invention makes it possible to activate the BGR function under certain conditions. When the BGR function is activated, the required setpoint braking can be achieved with alternative brake parameters that result in a relatively low noise level. At the same time, the safety of the vehicle is ensured because the BGR function is not always activated, but only under certain conditions.

It is preferably provided that the desired braking represents a driver's request. Accordingly, the desired braking is preferably determined on the brake pedal. Additionally or alternatively, the desired braking may also be based on an automatic control of the vehicle. For example, the cruise control or a distance control can specify the required target braking. The control for a fully or partially autonomous driving of the vehicle can also specify a desired braking.

Preferably, at least one critical pressure range is stored in the vehicle, in which an increased brake noise is expected. It is preferably provided that different pressure ranges are determined for different driving situations or operating conditions.

The critical pressure range preferably ranges from 2 bar to 20 bar, in particular from 2 bar to 15 bar. When the calculated brake pressure of a desired brake parameter falls within the critical pressure range, the BGR function is activated. In particular, hydraulic disc brakes have increased noise in certain pressure ranges. With the advantageous embodiment described here, in particular the noises in these specific pressure ranges can be suppressed.

As already described, it is preferably provided that the activation of the BGR function is suppressed in certain situations or states. For this purpose, certain situation parameters are defined in whose dependency an activation of the BGR function can be suppressed:
Depending on the vehicle speed, in particular at very high vehicle speeds, activation of the BGR function is preferably suppressed. Furthermore, there may be steering angles and / or road surface conditions, such as, for example, large steering angles or wet roadways, where, for safety-related reasons, no change in the desired brake parameters takes place. Likewise, it is preferably provided that the vehicle stability control can suppress the activation of the BGR function.

As described, the BGR function is activated in dependence on certain desired braking parameters; for example, when a brake pressure falls within the critical pressure range. In addition, however, it is also preferably provided that certain desired brake parameters suppress the activation of the BGR function. For example, very high brake pressures of the desired brake parameters can indicate that it is a dangerous driving situation. In these situations, it is preferably provided that activation of the BGR function is suppressed.

Furthermore, it is preferably provided to suppress the BGR function as a function of the brake temperature. In particular, too high a temperature of the brake discs indicates a critical condition in which the calculated target braking parameters should not be changed.

When determining the alternative brake parameters, the pressure distribution and the respective brake pressure are preferably changed with respect to the desired brake parameters. This change takes place, in particular, depending on the design of the brake system:
In the case of an axle-by-stage control of the brakes, the brake pressure is increased on one axle and reduced on another axle. This ensures that the brake pressure on both axes is outside the critical pressure range.

If the brake pressure is the same for diagonal wheels, the brake pressure is increased at two diagonally located wheels and reduced at the other two diagonally located wheels, so that in this case, the brake pressure is outside the critical pressure range.

If the brake pressure at each wheel can be adjusted individually, there are various possibilities to change the brake pressures and the corresponding pressure distribution in order to essentially bring about the desired target braking and at the same time keep the brake pressures as far outside the critical pressure ranges as possible.

Preferably, an average brake pressure is defined. For both the desired brake parameters and the alternative brake parameters, the average brake pressure is the average of the individual brake pressures at the wheels. (eg: four wheels with 5 bar brake pressure each lead to an average brake pressure of 5 bar). It is preferably provided that the average brake pressure of the alternative brake parameters is between 70% and 130%, preferably between 80% and 120%, particularly preferably between 90% and 110%, of the average brake pressure of the desired brake parameters. This ensures that the alternative brake parameters essentially lead to the same desired braking as the desired brake parameters.

The calculation of the desired brake parameters and / or the activation of the BGR function and / or the determination of the alternative brake parameters is preferably based on a brake configuration of the vehicle. This brake configuration includes corresponding values and / or characteristic diagrams and / or calculation formulas which match the respectively installed brake.

The invention further comprises a brake system for a vehicle. The brake system comprises at least one control unit in the vehicle. The at least one control device is designed to carry out the method just described. The advantageous embodiments described in the context of the method according to the invention and dependent claims find correspondingly advantageous application to the brake system according to the invention.

Further details, features and advantages of the invention will become apparent from the following description and the figures. Show it:

1 the inventive method for operating the brakes in a vehicle according to an embodiment, and

2 a diagram with brake pressures according to the inventive method according to the embodiment.

1 shows a schematic simplified view of a method 1 to operate the brakes in a vehicle. It is a two-lane motor vehicle with four wheels and four brakes 2 ,

First, a target braking 3 detected. This is done for example by a corresponding sensor on the brake pedal. Alternatively, the vehicle control may also have a desired braking 3 pretend. The target braking 3 essentially indicates, within what time which deceleration of the vehicle should be achieved.

Based on the target braking 3 become target braking parameters 4 calculated. These nominal braking parameters 4 give corresponding brake pressures and the associated pressure distribution for the brakes 2 at.

The next step is to check if there is a BGR function 5 can be activated. If this BGR function 5 is not activated, there is a direct control of the brakes 2 with the calculated setpoint brake parameters 4 ,

If the BGR function 5 is activated, there is a determination of alternative braking parameters 6 , These alternative brake parameters 6 lead to a lower noise level on the brakes 2 as the desired braking parameters 4 , At the same time, the alternative brake parameters lead 6 essentially the same nominal braking 3 of the vehicle.

This is followed by a corresponding activation of the brakes 2 with the alternative brake parameters 6 ,

Enabling the BGR function 5 takes place primarily based on the desired braking parameters 4 , For example, if a brake pressure of the desired braking parameters 4 into a certain critical pressure range 12 (S. 2 ) falls, the BGR function 5 activated.

Certain situation parameters already described 7 can cause an activation of the BGR function 5 is suppressed. The situation parameters 7 refer in particular to safety-related operating conditions and driving situations in which a change in the desired braking parameters 4 should be avoided.

Both the calculation of the desired braking parameters 4 as well as the activation of the BGR function 5 and determining the alternative brake parameters 6 is based on a brake configuration 8th , This brake configuration 8th are values, maps and / or calculation formulas depending on the installed brake 2 again.

2 shows an example in which the BGR function 5 is activated and alternative braking parameters 6 be determined. This shows 2 the course of brake pressures over time. In the example shown, the brake pressure on diagonally located wheels is the same in each case.

Dashed lines show a brake pressure 9 according to nominal braking parameters 4 , This brake pressure 9 of about 13.5 bar was based on the target braking 3 calculated. The desired braking parameters 4 So here's the brake pressure 9 and a uniform pressure distribution, so that the brake pressure 9 from 13.5 bar front right / rear left and front left / rear right would rest. The average brake pressure, as an average over all wheels, is 13.5 bar here.

The brake pressure 9 according to nominal brake parameters 4 lies within the critical pressure range 12 which in the example shown ranges from 12 bar to 15 bar.

Because the situation parameters 7 do not specify any safety-relevant obstacles, the BGR function 5 activated. This leads to the determination of the alternative brake parameters 6 , These alternative brake parameters 6 see here before that front right / rear left the brake pressure 10 increased to 17 bar, and front left / right rear brake pressure 11 is reduced to 10 bar. This leads to an average brake pressure of 13.5 bar and thus to the same target braking 3 like the desired braking parameters 4 ,

2 shows only an example, such as alternative brake parameters 6 can be changed to noise-critical areas, in particular the critical pressure range 12 , to avoid. Depending on the design of the brake system, different strategies can be chosen to adjust brake pressure and pressure distribution.

LIST OF REFERENCE NUMBERS

1

method

2

brakes

3

Target braking

4

Target braking parameters

5

BGR function

6

alternative brake parameters

7

Situations parameters

8th

braking configuration

9

Brake pressure according to setpoint brake parameters

10

first brake pressure according to alternative brake parameters

11

second brake pressure according to alternative brake parameters

12

critical pressure range

Claims (10)

Procedure ( 1 ) for the operation of the brakes ( 2 ) in a vehicle, comprising the following steps: • detecting a desired braking ( 3 ) of the vehicle, • calculation of desired braking parameters ( 4 ), comprising brake pressure ( 9 ) and pressure distribution, to bring about the desired braking ( 3 ), • activating a brake noise reduction function, in the following BGR function ( 5 ), depending on the desired braking parameters ( 4 ), • controlling the brakes ( 2 ) with the desired braking parameters ( 4 ), when the BGR function ( 5 ) is not activated, • determining alternative brake parameters ( 6 ), which lead to lower brake noise than the desired braking parameters ( 4 ), when the BGR function ( 5 ), and • controlling the brakes ( 2 ) with the alternative brake parameters ( 6 ), when the BGR function ( 5 ) is activated. Method according to Claim 1, characterized in that the nominal braking ( 3 ) is detected based on driver input and / or based on automatic control of the vehicle. Method according to one of the preceding claims, characterized in that in the vehicle at least one critical pressure range ( 12 ), which leads to increased brake noise, the BGR function ( 5 ) is activated when at least one brake pressure ( 9 ) the desired braking parameters ( 4 ) into the critical pressure range ( 12 ) falls. Method according to claim 3, characterized in that the critical pressure range ( 12 ) from 2 bar to 20 bar, preferably from 2 bar to 15 bar, is sufficient. Method according to one of the preceding claims, characterized in that depending on the following situation parameters ( 7 ) activation of the BGR function ( 5 ) is suppressed: • vehicle speed, and / or • desired braking parameters ( 4 ), and / or • brake temperature, in particular brake disc temperature, and / or • steering angle, and / or • road condition, and / or • suppression by vehicle stability control and / or • operating speed. Method according to one of the preceding claims, characterized in that when determining the alternative brake parameters ( 6 ) the pressure distribution and the respective brake pressures with respect to the desired brake parameters ( 4 ) to be changed. A method according to claim 6, characterized in that the brake pressure • increased for one axle and reduced for the other axle, or • increased for two diagonal wheels and reduced for the two other diagonal wheels, or • is adjusted wheel individually. Method according to one of the preceding claims, characterized in that an average brake pressure is defined as the average of the brake pressures at all wheels, wherein the average brake pressure of the alternative brake parameters ( 6 ) between 70% and 130%, preferably between 80% and 120%, most preferably between 90% and 110%, of the average brake pressure of the desired braking parameters ( 4 ) lies. Method according to one of the preceding claims, characterized in that the calculation of the desired braking parameters ( 4 ) and / or activating the BGR function ( 5 ) and / or determining the alternative brake parameters ( 6 ) based on the brake configuration ( 8th ) of the vehicle takes place. Brake system for a vehicle comprising a control device in the vehicle for carrying out the method ( 1 ) according to any one of the preceding claims.

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