Method for the low-emission brake control of a motor vehicle, and a motor vehicle which can be operated according to a method of this kind

Abstract

The invention relates to a method for the low-emission brake control of a motor vehicle (2) which comprises: at least one control unit (4) by means of which vehicle parameters captured by the motor vehicle (2) can be analyzed; at least two axles (6) which are each fixed to a supporting structure of the motor vehicle (2); and at least two braking units (10), wherein each braking unit (10) is assigned to one axle (6), wherein each braking unit (10) comprises at least one brake disc or brake drum non-rotationally fixed to a wheel (8) mounted on the axle (6), and comprises at least one braking means which is assigned to the brake disc or brake drum. The method comprises the following steps: a. measuring the respective actual temperatures of the brake discs or brake drum and braking means of the at least two braking units (10) by analyzing the captured vehicle parameters by means of the control unit (4); and b. reducing the braking pressure at the braking unit (10) having the highest actual temperature measured when at least one of the at least one further braking unit (10) has a measured actual temperature which is lower by at least a delta temperature than the highest actual temperature measured.

Description

[0001] Method for low-emission braking control of a motor vehicle and a motor vehicle operable according to such a method

[0002] The invention relates to a method for low-emission braking control of a motor vehicle and to a motor vehicle that can be operated according to such a method.

[0003] When operating a motor vehicle, particularly during braking, the brake fluid of a brake unit is applied to a brake disc or brake drum of the brake unit. As a result, brake particles can detach from the brake fluid and / or the brake disc or brake drum during braking and enter the environment.

[0004] The number of brake particles emitted depends on the temperature of the brake disc or drum and the brake pad. Above a certain critical temperature, particle emissions increase significantly.

[0005] An object of an embodiment of the invention is to propose a method for low-emission brake control of a motor vehicle and a motor vehicle operable according to such a method, with which a reduction in the amount of brake particles produced is possible.

[0006] This object is achieved by a method for low-emission brake control of a motor vehicle, which comprises at least one control unit by means of which vehicle parameters detected by the motor vehicle can be evaluated, which comprises at least two axles, each of which is fixed to a supporting structure of the motor vehicle, and which comprises at least two brake units, each brake unit being assigned to an axle, each brake unit comprising at least one brake disc or brake drum, which is fixed in a rotationally fixed manner to a wheel mounted on the axle, and at least one braking means assigned to the brake disc or brake drum, and wherein, for braking the motor vehicle, the respective braking means can be transferred from a basic position, in which the braking means with a brake pad is spaced apart from the brake disc or brake drum without contact, into a braking position in which the braking means with the brake pad is acted upon by a braking pressure on the brake disc orBrake drum touching and generating brake particles, comprising the steps of: a. determining the respective actual temperatures of the brake discs or brake drum and braking means of the at least two brake units by evaluating the recorded vehicle parameters by the control unit; and b. reducing the brake pressure at the brake unit with the determined highest actual temperature if at least one of the at least one further brake unit has a determined actual temperature that is at least one delta temperature lower than the determined highest actual temperature.

[0007] By determining the respective actual temperatures of the brake discs or brake drums and brake fluid of at least two brake units, the actual temperature of each brake unit can be recorded. Since the control unit determines the respective actual temperatures by evaluating the recorded vehicle parameters, the installation of additional sensors is eliminated.

[0008] By reducing the brake pressure on the brake unit with the highest actual temperature determined, a further temperature increase of the affected brake unit can be prevented or slowed down and the brake unit can cool down to a lower actual temperature if necessary.

[0009] Because the brake pressure of the brake unit is only reduced when at least one of the at least one additional brake unit has an actual temperature lower than the determined highest actual temperature, sufficient capacity can be maintained to brake the motor vehicle. For example, if the additional brake units each have an actual temperature that deviates from the determined highest actual temperature by less than the delta temperature, the brake pressure at the affected brake unit is not reduced, and the roadworthy operation of the motor vehicle is maintained unhindered.

[0010] The brake unit may comprise a drum brake or a disc brake. If the brake unit comprises a drum brake, the braking medium is applied to a brake drum in the braking position. If the brake unit comprises a disc brake, the braking medium is applied to a disc brake in the braking position.

[0011] Furthermore, in a further development of the method, it proves to be advantageous if it comprises the step of increasing the brake pressure of at least one brake unit which has a determined actual temperature which is at least by the delta temperature lower than the determined highest actual temperature.

[0012] This allows the reduction in brake pressure at the brake unit with the highest determined actual temperature to be compensated for by increasing the brake pressure at a brake unit with a lower determined actual temperature. As a result, the braking behavior of the vehicle remains virtually unchanged, and the brake unit with the highest actual temperature can cool down or at least continue to heat up less.

[0013] In addition, it proves to be advantageous if the reduction of the brake pressure of the brake unit with the determined highest actual temperature only occurs if the determined highest actual temperature also reaches or exceeds a critical temperature of the respective brake unit stored in the control unit.

[0014] This ensures that the motor vehicle is operated without applying the procedure until the critical temperature of the respective brake unit is reached. The procedure is only applied when it is determined that the highest actual temperature determined for one of the brake units reaches or exceeds the critical temperature stored in the control unit for this brake unit. The critical temperature of the respective brake unit stored in the control unit can depend on the material. If the individual brake units are made of different materials, the respective critical temperature of the respective brake unit stored in the control unit can differ from that of another brake unit.

[0015] The materials are primarily the materials of the brake fluid and the brake disc or brake drum, which generate brake particles when the vehicle brakes.

[0016] Furthermore, in a further development of the latter embodiment, it is provided that the increase in the brake pressure of the at least one brake unit, which comprises a determined actual temperature which is at least by the delta temperature lower than the determined highest temperature, only takes place if the determined actual temperature additionally differs from a critical temperature of the respective brake unit stored in the control unit.

[0017] This can prevent a brake unit that has already reached its critical temperature from becoming further heated.

[0018] The critical temperature can be stored as a fixed value for all brake units. In one embodiment of the method, it proves advantageous if the critical temperature comprises a material-dependent temperature of the respective brake unit at which a temperature-dependent emission of brake particles reaches or exceeds a critical number, and in particular comprises at least 150 °C, in particular at least 180 °C.

[0019] The emission of brake particles increases exponentially depending on the temperature of the brake disc or brake drum, or the brake fluid lining. Once the critical temperature is reached, particle emissions increase particularly sharply. Considering the driving characteristics of the motor vehicle, particularly the braking behavior and the potential emission of brake particles, the critical temperature offers a favorable compromise. Preferred embodiments of the method include those in which the delta temperature is at least 5°C, in particular at least 10°C, and in particular at least 20°C.

[0020] By providing a delta temperature, which must differentiate the actual temperature of the brake unit with the lower actual temperature from the brake unit with the highest actual temperature, oversteering is avoided, especially when the two temperatures are very close to each other. By providing the delta temperature, a certain time lag is established until the brake disc or brake drum has absorbed the introduced heat capacity and its actual temperature rises.

[0021] In order to be able to determine the respective actual temperatures of the brake units, it proves to be advantageous if the recorded vehicle parameters include the speed of the motor vehicle, in particular in a specific time interval, the course of the brake pressure at the respective brake unit, in particular in the specific time interval, the number of braking operations, the outside temperature and / or the loading state of the motor vehicle.

[0022] This provides the control unit with sufficient information to calculate the heat generated during braking and absorbed by the brake fluid and brake disc or brake drum, and to determine the actual temperatures. The heating can be calculated based on the brake pressure curve at the respective brake unit, particularly over a specific time interval, the number of braking applications, and, for example, the friction coefficients between the brake fluid and the brake disc or brake drum. Furthermore, by taking the outside temperature into account, the cooling of the respective brake units when the vehicle is not braking can be determined.

[0023] The motor vehicle can, for example, comprise a passenger car with two axles. Furthermore, the motor vehicle can comprise a multi-axle vehicle, in particular a truck or the like. In such a case, it proves advantageous if the motor vehicle comprises at least three axles and at least three brake units, wherein the reduction of the brake pressure includes all brake units whose determined actual temperature is higher by at least the delta temperature than the determined lowest temperature, in particular if the determined actual temperature of at least one brake unit with the determined lowest temperature is lower than its critical temperature.

[0024] This allows at least two brake units to be cooled down if they have a higher actual temperature than a remaining brake unit with a lower actual temperature.

[0025] Analogously, in a further development of the latter embodiment, the increase in the brake pressure includes all the brake units whose determined actual temperature is at least the delta temperature lower than the determined highest temperature, in particular if the determined actual temperature of the brake unit with the determined lowest temperature is lower than its critical temperature.

[0026] Finally, the object is achieved by a motor vehicle which can be operated according to a method having at least one of the features mentioned above, having at least one control unit by means of which vehicle parameters recorded by the motor vehicle can be evaluated, having at least two axles which are each fastened to a supporting structure of the motor vehicle, and having at least two brake units, each brake unit being assigned to an axle, each brake unit comprising at least one brake disc or brake drum which is fastened in a rotationally fixed manner to a wheel mounted on the axle, and at least one braking means assigned to the brake disc or brake drum, and wherein, in order to brake the motor vehicle, the respective braking means is moved from a basic position into which the braking means, with a brake pad, makes contact without contact with the brake disc or brake drum.Brake drum is spaced apart, can be transferred into a braking position in which the braking medium with the brake pad is subjected to a braking pressure and rests against the brake disc or brake drum, generating brake particles.

[0027] Further features, details and advantages of the invention emerge from the appended patent claims, from the drawings and the following description of a preferred embodiment of the motor vehicle and the method.

[0028] The drawing shows: Figure 1 a schematic representation of a motor vehicle according to the invention;

[0029] Figure 2 A schematic flow diagram of the method according to the invention.

[0030] Figure 1 shows a schematic representation of a motor vehicle, designated overall by reference numeral 2. In the exemplary embodiment shown in Figure 1, the motor vehicle 2 comprises a control unit 4, by which vehicle parameters detected by the motor vehicle 2 can be evaluated.

[0031] Furthermore, the motor vehicle 2 comprises at least two axles 6, at the free ends of which wheels 8 are arranged. The axles 6 are each fixed to a supporting structure of the motor vehicle 2.

[0032] In addition, the motor vehicle 2 comprises a plurality of brake units 10, each of which comprises a brake disc that is arranged in a rotationally fixed manner on a wheel 8 and a braking means that can be placed in contact with the brake disc for braking. The brake disc and braking means are not explicitly shown in the figures. The brake units 10 are each assigned to an axle 6. In the exemplary embodiment shown in Figure 1, a brake unit 10 thus comprises two brake discs, one brake disc being assigned to each wheel 8, and two braking means, one braking means being assigned to each brake disc.

[0033] Figure 2 shows a schematic flow diagram of a method according to the invention. The method is described below with the aid of the illustration in Figure 1:

[0034] In a first step 100, the respective actual temperatures of the brake discs and braking means of the at least two brake units 10 are determined by the control unit 4 evaluating the recorded vehicle parameters. In this case, the determination of the respective actual temperatures can include the speed of the motor vehicle 2, the brake pressure curve at the respective brake units 10, the number of braking applications, the outside temperature, and / or the load state of the motor vehicle 2 as vehicle parameters. In a subsequent step 101, the brake pressure at the brake unit 10 that has the highest actual temperature according to step 100 is reduced. This occurs when at least one of the at least one further brake units 10 has an actual temperature that is at least one delta temperature lower than the highest actual temperature determined.

[0035] The delta temperature may be at least 5°C, in particular at least 10°C, in particular at least 20°C.

[0036] In addition, in a step 102, the brake pressure of at least one brake unit 10 can be increased, which has a determined actual temperature that is at least the delta temperature lower than the determined highest actual temperature.

[0037] The features of the invention disclosed in the above description, in the claims and in the drawings may be essential, both individually and in any combination, in the realization of the invention in its various embodiments within the scope of the following claims.

[0038] List of reference symbols

[0039] 2 Motor vehicle 4 Control unit

[0040] 6 axis

[0041] 8 wheel

[0042] 10 Brake unit 100-

[0043] 102 procedural steps

Claims

P a t e n t a n s p r ü c h e 1 . Method for low-emission brake control of a motor vehicle (2), which comprises at least one control unit (4) by means of which vehicle parameters detected by the motor vehicle (2) can be evaluated, which comprises at least two axles (6), which are each fixed to a supporting structure of the motor vehicle (2), and which comprises at least two brake units (10), wherein each brake unit (10) is assigned to an axle (6), wherein each brake unit (10) comprises at least one brake disc or brake drum, which is fixed in a rotationally fixed manner to a wheel (8) mounted on the axle (6), and at least one braking means assigned to the brake disc or brake drum, and wherein, for braking the motor vehicle (2), the respective braking means is moved from a basic position into the braking means with a brake pad in contact-free manner with the brake disc orBrake drum is spaced apart, can be transferred into a braking position in which the braking medium with the brake pad is subjected to a braking pressure and contacts the brake disc or brake drum, generating brake particles, with the steps: a. determining the respective actual temperatures of the brake discs and braking medium or brake drum of the at least two brake units (10) by evaluating the recorded vehicle parameters by the control unit (4); and b. reducing the braking pressure at the brake unit (10) with the determined highest actual temperature if at least one of the at least one further brake unit (10) has a determined actual temperature which is at least one delta temperature lower than the determined highest actual temperature.

2. Method according to claim 1, characterized by increasing the brake pressure of at least one brake unit (10) which has a determined actual temperature which is at least the delta temperature lower than the determined highest actual temperature. Method according to claim 1 or 2, characterized in that the reduction of the brake pressure of the brake unit (10) with the determined highest actual temperature only occurs if the determined highest actual temperature additionally reaches or exceeds a critical temperature of the respective brake unit (10) stored in the control unit (4). Method according to claim 3, characterized in that the increase of the brake pressure of the at least one brake unit (10) that has a determined actual temperature that is at least the delta temperature lower than the determined highest temperature only occurs if the determined actual temperature additionally exceeds a critical temperature of the respective brake unit (10) stored in the control unit (4).Method according to one of the preceding claims, characterized in that the critical temperature comprises a material-dependent temperature of the respective brake unit (10) at which a temperature-dependent emission of brake particles reaches or exceeds a critical number, and in particular comprises at least 150°C, in particular at least 180°C. Method according to one of the preceding claims, characterized in that the delta temperature comprises at least 5°C, in particular at least 10°C, in particular at least 20°C. Method according to one of the preceding claims, characterized in that the recorded vehicle parameters comprise the speed of the motor vehicle (2), in particular in a specific time interval, the course of the brake pressure at the respective brake unit (10), in particular in the specific time interval, the number of braking operations, the outside temperature and / or the loading state of the motor vehicle (2).Method according to one of the preceding claims, characterized in that the motor vehicle (2) comprises at least three axles (6) and at least three brake units (10), wherein the reduction of the brake pressure comprises all the brake units (10) whose determined actual temperature is at least the delta temperature higher than the determined lowest temperature, in particular if the determined actual temperature. at least one brake unit (10) with the determined lowest temperature is lower than its critical temperature. Method according to claim 8, characterized in that increasing the brake pressure includes all brake units (10) whose determined actual temperature is lower by at least the delta temperature than the determined highest temperature, in particular if the determined actual temperature of the brake unit (10) with the determined lowest temperature is lower than its critical temperature.Motor vehicle (2) which can be operated according to a method according to one of claims 1 to 9, with at least one control unit (4) by means of which vehicle parameters detected by the motor vehicle (2) can be evaluated, with at least two axles (6), which are each fastened to a supporting structure of the motor vehicle (2), and with at least two brake units (10), wherein each brake unit (10) is assigned to an axle (6), wherein each brake unit (10) comprises at least one brake disc or brake drum which is fastened in a rotationally fixed manner to a wheel (8) mounted on the axle (6), and at least one braking means assigned to the brake disc or brake drum, and wherein, in order to brake the motor vehicle (2), the respective braking means is moved from a basic position into which the braking means, with a brake pad, makes contact without contact with the brake disc orBrake drum is spaced apart, can be transferred into a braking position in which the braking medium with the brake pad is subjected to a braking pressure and rests against the brake disc or brake drum, generating brake particles.

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