Method for adjusting the applied pressure of a vehicle brake, and vehicle brake in question

Abstract

The invention relates to a method for adjusting the applied pressure pa of a vehicle brake (2) of a motor vehicle (1), in particular a utility vehicle (3), comprising a utility vehicle disc brake (4). In the event of an increased brake pressure p in a first pressure range (16), the vehicle brake (2) advances a brake pad (10) in the direction of the brake disc (22) by a brake advancing distance d, thereby overcoming an air gap L, while increasing the friction torque Mr, and in the event of a further increased brake pressure p in a second pressure range (18), the brake disc (22) is completely advanced and an additionally increased friction torque Mr is set on the vehicle brake (2). According to the invention, the following steps are proposed: detecting (104) the brake advancing distance d on the basis of the brake pressure p, identifying (106) the first pressure range (16) on the basis of the detected brake advancing distance d according to the brake pressure p, and setting (108) the application pressure pa of the vehicle brake (2) to a pressure pa which lies within the first pressure range (16). The invention additionally relates to a related controller (202), to a computer program product (302), to a vehicle brake (2), and to a vehicle (1).

Description

[0001] Method for adjusting an application pressure of a vehicle brake and relevant vehicle brake

[0002] The invention relates to a method for adjusting the application pressure of a vehicle brake of a motor vehicle, in particular of a commercial vehicle with a commercial vehicle disc brake. As the brake pressure increases in a first pressure range, the vehicle brake applies a brake pad by a brake application path toward the brake discs, overcoming a clearance, thereby increasing the frictional torque. As the brake pressure further increases in a second pressure range, the brake disc is fully applied, and a further increase in the frictional torque at the vehicle brake occurs. The increase in the frictional torque also results in an increase in the braking force.

[0003] The application pressure is the brake pressure applied to the braking system when the brake is to be kept ready for operation, but there is no desire to decelerate. It is typically selected so that it is just large enough to overcome the mechanical friction of the brake caliper and reduce the distance between the brake disc and brake pad, the so-called air gap, to almost zero, while at the same time causing minimal friction losses. The application pressure is thus subject to the tension between providing the shortest possible braking response times on the one hand and generating the lowest possible friction torque on the other.

[0004] Methods for adjusting the application pressure of a vehicle brake are known from the prior art and are based, for example, on parameterizing the application pressure and storing it in a brake control unit. Although such methods have proven effective in ensuring favorable response behavior of the vehicle brake by applying the application pressure, it has been observed that in reality, applying the application pressure can lead to significant friction torques and thus braking forces even when deceleration is neither required nor desired. This results in the loss of kinetic energy, which is then no longer available for recuperation. At the same time, wear on the vehicle brake increases.

[0005] Against this background, the object of the invention was to further develop a method of the type described above in such a way that the disadvantages found in the prior art are eliminated as far as possible. In particular, a method was to be provided that optimizes the setting of the application pressure in a vehicle brake in order to reduce undesirable friction torques on the brake.

[0006] According to the invention, the object is achieved in a method of the type mentioned at the outset by the steps of: detecting the brake application path as a function of the brake pressure, identifying the first pressure range on the basis of the detected brake application path as a function of the brake pressure, setting an application pressure of the vehicle brake to a pressure which lies within the first pressure range.

[0007] The invention makes use of the knowledge that, during braking carried out during vehicle operation, a relationship between brake application distance and brake pressure can be detected, in particular for each of the wheel brakes individually. From this, a first pressure range is identified and the application pressure is set in the determined first pressure range. In the first pressure range, the brake pad is applied by a brake application distance in the direction of the brake discs, overcoming the air gap and increasing the friction torque. In other words, in the first pressure range, the air gap is overcome and the brake pad comes into at least partial contact with the brake disc. In the second pressure range, the brake disc is fully applied, with increasing brake pressure resulting in a further increase in the friction torque on the vehicle brake.

[0008] By adjusting the application pressure within the first pressure range, the vehicle brake ensures rapid provision of braking force while causing minimal friction losses. In contrast to prior art methods, in which the application pressure is merely parameterized and stored, the method according to the invention enables a much more precise adjustment of the application pressure, taking into account the actual brake condition, such as pad wear and other properties. The overall efficiency of the vehicle brake is thus improved.

[0009] The invention is further developed in that the brake application travel is detected as a function of the brake pressure by means of a continuous pad wear sensor arranged on the vehicle brake. The vehicle brake preferably has two brake pads, with a pad wear sensor preferably arranged on each vehicle brake.

[0010] According to a preferred embodiment, the application pressure is set to a pressure that lies in a lower third relative to the overall range of the first pressure range. Selecting the application pressure in the lower third of the first pressure range has proven particularly suitable for ensuring a rapid braking response on the one hand and minimizing friction losses on the other.

[0011] According to a preferred development, the application pressure is set to a pressure that lies in the middle third of the overall range of the first pressure range. For some brake types and applications, it has proven useful to increase the application pressure compared to the previous embodiment. While this tends to result in greater pad wear, it can reduce braking response times.

[0012] According to an alternative embodiment, the application pressure is set to a pressure that lies in the upper third of the total range of the first pressure range. This setting has also proven preferable for some applications and brake types. In principle, this can further reduce the brake's response time, but this potentially results in increased brake wear.

[0013] The invention is further developed in that the set application pressure is checked during vehicle operation, in particular by means of at least one test braking. In this respect, for example, in a suitable driving situation, such as during coasting or rolling, the application pressure can be applied, with knowledge of all other force-applying actuators in operation, and the vehicle's reaction can be observed. This allows it to be determined whether the application pressure provides the desired deceleration or wear behavior.

[0014] The invention is further developed in that the application pressure is checked using an electric vehicle drive, in particular by determining a change in the drive power or drive torque during a test braking. In other words, the electric drive can be precisely controlled so that the vehicle's movement can be maintained, for example, without changing the topology. Based on the required drive power or drive torque of the electric drive, the actual deceleration can be monitored by the application pressure, and the level of the application pressure can be further optimized.

[0015] The invention has been described above with reference to a method. In a further aspect, the invention relates to a control unit for a vehicle brake of a commercial vehicle. The invention achieves the object described above with regard to the control unit in that the control unit is configured to carry out the method according to one of the above embodiments.

[0016] The control unit is preferably designed as a dedicated control unit or as a central control unit. A dedicated control unit is understood to be a control unit that is directly assigned to or arranged on at least one of the vehicle brakes. The control unit utilizes the same advantages and preferred embodiments as the method according to the invention, and vice versa. In this regard, reference is made to the above explanations, and their content is incorporated herein.

[0017] In a third aspect, the invention relates to a computer program product. The invention achieves the object identified above with respect to the computer program product in that it contains instructions which, when executed on a computer, cause the computer to form a control unit according to one of the preceding embodiments and / or to execute the method according to one of the preceding embodiments. The computer program product also utilizes the same advantages and preferred embodiments as the method and control unit according to the invention, and vice versa. In this regard, reference is made to the above statements, and their content is incorporated herein.

[0018] In a fourth aspect, the invention relates to a vehicle brake, in particular a commercial vehicle disc brake, having a brake carrier with at least one brake pad holder, at least one brake pad which is guided and supported in the brake pad holder so as to be axially displaceable, a brake caliper which is axially movable relative to the brake carrier, and a measuring arrangement which is designed to detect a brake application path of the vehicle brake as a function of the brake pressure, wherein, with increasing brake pressure in a first pressure range, the vehicle brake applies a brake pad by a brake application path in the direction of the brake disc, overcoming the air gap, with an increase in a friction torque, and with further increasing brake pressure in a second pressure range, the brake disc is fully applied and a further increase in the friction torque on the vehicle brake occurs.

[0019] The invention achieves the aforementioned problem with respect to the vehicle brake in that the vehicle brake is configured to adjust an application pressure to a pressure that lies within the first pressure range. The vehicle brake according to the invention is also based on the finding that, from the relationship between the brake application travel and the brake pressure, an application pressure can be determined and adjusted that allows for minimizing friction losses while simultaneously providing rapid braking force from the vehicle brake.

[0020] The invention is further developed in that the measuring arrangement has a pad wear sensor which is designed to detect the brake application path of the vehicle brake as a function of the brake pressure.

[0021] Preferably, the application pressure is set to a pressure that lies in a lower third relative to the total width of the first printing area. According to an alternatively preferred embodiment, the application pressure is set to a pressure that lies in a middle third relative to the total width of the first printing area. According to another alternatively preferred embodiment, the application pressure is set to a range that lies in an upper third relative to the total width of the first printing area.

[0022] The vehicle brake utilizes the same advantages and preferred embodiments as the method according to the invention, the control unit according to the invention, and the computer program product according to the invention, and vice versa. In this regard, reference is made to the above statements, and their content is incorporated herein.

[0023] In a further aspect, the invention relates to a motor vehicle, in particular a commercial vehicle. The invention achieves the object defined above with respect to the motor vehicle in that the motor vehicle has at least one vehicle brake, wherein the at least one vehicle brake is designed according to one of the preceding exemplary embodiments. The invention is further developed in that the motor vehicle has a control unit according to one of the preceding claims.

[0024] The motor vehicle utilizes the same advantages and preferred embodiments as the method according to the invention, the control unit according to the invention, the computer program product according to the invention, and the vehicle brake according to the invention, and vice versa. In this regard, reference is made to the above statements, and their content is incorporated herein.

[0025] Embodiments of the invention will now be described below with reference to the drawings. These are not necessarily intended to represent the embodiments to scale; rather, where useful for explanation, the drawings are schematic and / or slightly distorted. With regard to additions to the teachings immediately apparent from the drawings, reference is made to the relevant prior art. It should be noted that numerous modifications and changes to the form and detail of an embodiment can be made without deviating from the general idea of ​​the invention. The features of the invention disclosed in the description, in the drawings and in the claims can be essential for the further development of the invention, both individually and in any combination.Furthermore, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of ​​the invention is not limited to the exact form or detail of the preferred embodiment shown and described below, nor is it restricted to an object that would be more limited than the object claimed in the claims. For specified dimensioning ranges, values ​​within the stated limits are also intended to be disclosed as limit values ​​and can be used and claimed as desired. For the sake of simplicity, identical parts or parts with identical or similar functions are provided with the same reference numerals below.

[0026] In detail:

[0027] Fig. 1 shows an embodiment of a motor vehicle according to the invention with a vehicle brake according to the invention in a schematic view;

[0028] Fig. 2 is a diagram showing an exemplary relationship between brake pressure and brake delivery path in a vehicle brake according to the invention;

[0029] Fig. 3 is a block diagram of a method for adjusting an application pressure of a vehicle brake;

[0030] Fig.4 is a schematic representation of a control device according to the invention; and

[0031] Fig. 5 is a schematic representation of a computer program product according to the invention.

[0032] Fig. 1 shows a motor vehicle 1, which is only shown schematically here and is designed in particular as a commercial vehicle 3. The motor vehicle 1 has a vehicle brake 2. The vehicle brake 2 is designed here as a commercial vehicle disc brake 4. The vehicle brake 2 has a brake carrier 6. The brake carrier 6 has a brake pad holder 8. Arranged in the brake pad holder 8 are two brake pads 10, which are guided and supported in the brake pad holder 8 so as to be axially displaceable. The vehicle brake 2 also has a brake caliper 12 which is axially movable relative to the brake carrier 6.

[0033] The vehicle brake 2 further comprises a measuring arrangement 14. The measuring arrangement 14 is configured to detect a brake application distance d of the vehicle brake 2 as a function of the brake pressure p. In the state shown in Fig. 1, the vehicle brake 2 has a clearance L, which describes the distance between the brake disc 22 and the brake pad 10. The measuring arrangement 14 comprises a pad wear sensor 20. The pad wear sensor 20 is configured to detect the brake application distance d of the vehicle brake 2 as a function of the brake pressure p.

[0034] This relationship is illustrated in Fig. 2. Fig. 2 shows an example diagram in which the brake pressure p is plotted on the abscissa. In Fig. 2, a pressure range for the brake pressure p from 0 bar to approximately 2.5 bar is plotted. The brake application distance d is plotted on the ordinate, which is given here in millimeters as an example. Three pressure ranges can be seen from the diagram. As the brake pressure p increases, a static range 19 is initially reached. In the static range 19, an increase in the brake pressure p does not lead to a change in the brake application distance d. In other words, a pressure increase in this range does not yet result in the brake pad 10 being advanced in the direction of the brake disc 22. In the example shown in Fig. 2, this static range 19 extends approximately up to a brake pressure p of 0.3 bar.

[0035] As the brake pressure p increases further, a first pressure range 16 is reached. In this range, the vehicle brake 2 is applied by a brake application distance d in the direction of the brake disc 22 with increasing brake pressure p, overcoming the air gap L, while increasing a friction torque Mr. At the end of the first pressure range 16, which in the example shown is reached at approximately 0.8 bar, the brake disc 22 is fully applied. As the brake pressure p increases further, a further increase in the friction torque Mr on the vehicle brake 2 is achieved in the second pressure range 18. The first pressure range 16 has a total range width b in this case. This total range width b is divided into a lower third 24, a middle third 26, and an upper third 28.

[0036] The vehicle brake 2 is designed to apply an application pressure p a which lies within the first pressure range 16. Preferably, the application pressure pa to a pressure p a which lies in the lower third 24 relative to the total area width b of the first pressure area 16. This is shown schematically in Fig. 2 by the application pressure p a Here, for example, it is set to a pressure value of 0.4 bar, whereby this application pressure p a in the lower third 24 of the first pressure range 16. Setting the application pressure p a in this area ensures that the vehicle brake 2 can quickly provide a braking force from the respective standby state, and at the same time minimal friction losses occur in this standby state.

[0037] Fig. 3 shows a block diagram of a method according to the invention for setting an application pressure p aa vehicle brake 2 of a motor vehicle 1, in particular a commercial vehicle disc brake 4, wherein the vehicle brake 2, with increasing brake pressure p in a first pressure range 16, delivers a brake pad 10 by a brake delivery path d in the direction of the brake disc 22 while overcoming a clearance L, with an increase in a friction torque Mr, and with further increasing brake pressure p in a second pressure range 18, the brake disc 22 is completely delivered and a further increase in the friction torque Mr occurs at the vehicle brake 2.

[0038] The method comprises a step 104, after which the brake application distance d is detected as a function of the brake pressure p. According to step 106, the first pressure range 16 is identified on the basis of the detected brake application distance d as a function of the brake pressure p. Finally, according to step 108, an application pressure p is set. ato a pressure which lies within the first pressure range 16.

[0039] Preferably, the method further comprises the step: checking 110 the set application pressure p a during operation of the vehicle, in particular by means of at least one test braking.

[0040] Fig. 4 schematically shows a control unit 202 for a vehicle brake 2 of a motor vehicle 1. The control unit 202 is configured to execute the method 100 according to Fig. 3. The control unit 202 can be designed as a dedicated control unit 202 or as a central control unit 202.

[0041] Fig. 5 schematically shows a computer program 203. The computer program product 203 contains instructions 304. The instructions 304 cause a computer (not shown), when executed thereon, to form a control device 202 according to Fig. 4 and / or to execute the method 102 according to Fig. 3.

[0042] List of reference symbols (part of the description):

[0043] 1 motor vehicle

[0044] 2 vehicle brake

[0045] 3 commercial vehicles

[0046] 4 commercial vehicle disc brakes

[0047] 6 brake carriers

[0048] 8 Brake pad holder

[0049] 10 brake pad

[0050] 12 brake caliper

[0051] 14 Measuring arrangement

[0052] 16 first printing area

[0053] 18 second printing area

[0054] 19 static area

[0055] 20 Pad wear sensor

[0056] 22 brake disc

[0057] 24 lower third

[0058] 26 middle third

[0059] 28 upper third

[0060] 102 Setting procedures

[0061] 104 Recording the brake application distance as a function of the brake pressure

[0062] 106 Identifying the first print area

[0063] 108 Setting an application pressure to a pressure value within the first pressure range

[0064] 110 Checking the set application pressure by means of test braking

[0065] 202 control unit

[0066] 302 Computer program product

[0067] 304 Commands b Total range width of the first pressure range d Brake travel

[0068] L clearance

[0069] Mr Friction torque p Brake pressure p a Contact pressure

Claims

Patent claims: 1 . Method (102) for setting an application pressure (p a ) of a vehicle brake (2) of a motor vehicle (1), in particular of a commercial vehicle (3), with a commercial vehicle disc brake (4), wherein the vehicle brake (2) with increasing brake pressure (p) in a first pressure range (16) delivers a brake pad (10) by a brake delivery path (d) in the direction of the brake disc (22) while overcoming a clearance (L) with an increase in a frictional torque (Mr), and with further increasing brake pressure (p) in a second pressure range (18) the brake disc (22) is fully delivered and a further increase in the frictional torque (Mr) occurs at the vehicle brake (2), with the steps: - detecting (104) the brake travel (d) as a function of the brake pressure (P), - identifying (106) the first pressure range (16) on the basis of the detected brake application path (d) as a function of the brake pressure (p), - Setting (108) an application pressure (p a ) of the vehicle brake (2) to a pressure (p a ), which lies within the first pressure range (16).

2. Method (102) according to claim 1, wherein the detection of the brake application travel (d) as a function of the brake pressure (p) is carried out by means of a continuous lining wear sensor (20) arranged on the vehicle brake (2).

3. Method (102) according to claim 1, wherein the application pressure (p a ) to a pressure (p a ) which lies in a lower third (24) relative to a total area width (b) of the first printing area (16).

4. Method (102) according to claim 1 or 2, where the application pressure (p a ) to a pressure (p a ) which lies in a middle third (26) relative to a total area width (b) of the first printing area (16).

5. Method (102) according to claim 1 or 2, wherein the application pressure (p a ) to a pressure (p a ) which lies in an upper third (28) relative to a total area width (b) of the first printing area (16).

6. The method (102) according to any preceding claim, further comprising the step: - Check (110) the set application pressure (p a ) during operation of the vehicle (1 ), in particular by means of at least one test braking.

7. The method (102) according to claim 6, wherein the checking (110) of the application pressure (p a ) using an electric vehicle drive, in particular by determining a change in the drive power or drive torque when carrying out the test braking.

8. Control unit (202) for a vehicle brake (2) of a commercial vehicle, characterized in that the control unit (202) is configured to carry out the method (100) according to one of claims 1 to 7.

9. Control unit (202) according to claim 8, wherein the control unit (202) is designed as a dedicated control unit (202) or as a central control unit (202).

10. A computer program product (302) containing instructions (304) which, when executed on a computer, cause the computer to form a control device (202) according to claim 8 or 9 and / or to carry out the method (102) according to any one of claims 1 to 7. 11 . Vehicle brake (2), in particular commercial vehicle disc brake (4), with - a brake carrier (6) with at least one brake pad holder (8), - at least one brake pad (10) which is guided and supported in the brake pad holder (8) in an axially displaceable manner, - a brake calliper (12) movable axially relative to the brake carrier (6), and - a measuring arrangement (14) which is designed to detect a brake application path (d) of the vehicle brake (2) as a function of the brake pressure (p), wherein, with increasing brake pressure (p) in a first pressure range (16), the vehicle brake (2) applies a brake pad (10) by a brake application path (d) in the direction of the brake disc (22) while overcoming a clearance (L) and increasing a friction torque (Mr), and with further increasing brake pressure (p) in a second pressure range (18), the brake disc (22) is completely applied and a further increase in the friction torque (Mr) occurs at the vehicle brake (2), characterized in that the vehicle brake (2) is designed to apply an application pressure (p a ) to a pressure (p a ) which lies within the first pressure range (16).

12. Vehicle brake (2) according to claim 10, wherein the measuring arrangement (14) has a lining wear sensor (20) which is designed to detect the brake application path (d) of the vehicle brake (2) as a function of the brake pressure (p).

13. Vehicle brake (2) according to claim 11 or 12, wherein the application pressure (p a ) to a pressure (p a ) which lies in a lower third (24) relative to a total area width (b) of the first printing area (16).

14. Vehicle brake (2) according to claim 11 or 12, where the application pressure (p a ) to a pressure (p a ) which lies in a middle third (26) relative to a total area width (b) of the first printing area (16).

15. Vehicle brake (2) according to claim 1 1 or 12, wherein the application pressure (p a ) to a pressure (p a) which lies in an upper third (28) relative to the total width (b) of the first printing area (16).

16. Motor vehicle (1 ), in particular commercial vehicle (3), comprising - at least one vehicle brake (2), wherein the at least one vehicle brake (2) is designed according to one of claims 11-15.

17. Motor vehicle (1) according to claim 16, characterized by a control device (202) according to claim 8 or 9.

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