DE102022123479A1 - Method for operating a friction brake device, computer program and/or computer-readable medium, control device, friction brake device and vehicle, in particular commercial vehicle - Google Patents

Abstract

Method (100) for operating a friction brake device (40) for a vehicle (300a), in particular commercial vehicle (300b), having an electric drive (21) set up for regenerative braking (NB), the method (100) comprising: detecting (110) a Braking request (55) for braking the vehicle (300a), in particular commercial vehicle (300b), with a target braking torque (56); Determining (120) a maximum braking torque (57) taking into account a threshold condition (59); Determining (130) a friction braking torque (41) for operating (140) the friction braking device (40), the friction braking torque (41) being determined as a function of the maximum braking torque (57) in such a way that a generator braking torque (25) of the electric drive (21) has a positive control reserve (22) and a negative control reserve (23); and operating (140) the friction brake device (40) according to the friction brake torque (41).

Description

The invention relates to a method for operating a friction brake device for a vehicle, in particular a commercial vehicle, having an electric drive set up for regenerative braking. The invention also relates to a computer program and/or computer-readable medium, a control device for a friction brake device, a friction brake device, and a vehicle, in particular a commercial vehicle.

The invention relates in particular to the field of vehicles, in particular commercial vehicles, including trailers, with an electronically controlled braking system (electronic brake system, EBS, or trailer electronic brake system, TEBS) and at least one powered by an electric drive (eDrive) via a central drive and/ or a wheel-specific drive that can be driven electrically, the electric drive being set up for regenerative braking. In other words, the electric drive can be operated as a wear-free continuous brake and enables braking energy to be recovered in the form of electrical energy (recuperation) during deceleration. A generator braking torque has a decelerating effect on one or more wheels of the vehicle.

On a driven axle, the electric drive and the friction brake can be operated separately or together during braking and deceleration processes. The blocking of a wheel on this axle due to the currently controlled (sum) braking torque or total braking torque must be prevented. To do this, the active braking torque must be reduced in order to keep wheel slip at or below a permissible value. The braking torque is reduced, for example, when the wheel deceleration exceeds a limit value and/or a given slip value is exceeded. For this purpose, in current systems the electric drive is shed in the same way as a continuous brake or a conventional retarder, i.e. the contribution of the electric drive to deceleration is reduced to zero. It is known from the prior art to then build up pneumatic brake pressure when continuous brake integration is active and to start a pneumatic ABS control cycle with the friction brake. Braking is done purely with the friction brake. In stability-critical driving situations, only the friction brake is used.

In braking systems according to the state of the art, the continuous brakes (retarder and electric drive set up for regenerative braking) are released when a stability-critical driving event (e.g. ABS/DTC) is detected or limited to 0% of their available torque by the braking system. The reason for the complete abandonment of the continuous brake is that conventional retarders cannot be regulated in terms of precision and dynamics. If the continuous brake was requested by the braking system, the friction brake needs a certain amount of time after the retarder has been released until the necessary brake pressure is built up and braking can be carried out by the friction brake. This creates a so-called “hole” for the braking torque - especially after braking with the retarder alone. If the driver has activated the continuous brake using a retarder lever, for example, the deceleration is initially completely eliminated and the driver has to apply the brakes using the brake pedal. When the friction brakes respond (automatically or through additional braking), the desired deceleration is distributed across all axles with optimal adhesion, instead of typically only braking the rear axle with the continuous brake. In an ABS cycle, pressure is cyclically reduced and increased. The bike is braked in phases and runs freely. The average braking torque is reduced and driving stability, cornering and steerability are ensured.

DE 10 2019 135 087 A1 discloses a method for slip control of a vehicle wheel driven via an electric drive, with at least the following steps: control of the electric drive of the vehicle wheel with an actual drive torque in a torque control in a torque control step, determination of a wheel speed and a wheel slip of the vehicle wheel and evaluation the wheel slip by an instability criterion, whether instability is present, when instability is detected, direct or indirect transition to a slip control of the wheel slip to a target slip by controlling the electric drive, determining whether a final criterion for terminating the slip control is met, if the final criterion is satisfied, feedback to the torque control in the torque control step.

DE 10 2012 217 679 A1 discloses a slip-controlled braking system for an electrically driven motor vehicle, the friction brakes on the wheels of at least one axle, which are controlled by a friction brake control device, at least one electric machine which is connected to at least one wheel and is controlled by an electric drive control device, means for detecting a deceleration request , in particular a brake pedal with a pedal angle sensor, a wheel slip control device and a torque distribution device. This is the means or means for detecting a delay requirement is connected to the wheel slip control device, which specifies target braking torques for each wheel in accordance with the deceleration request, the wheel slip control device being connected to a torque distribution device, which is connected to the friction brake control device and the electric drive control device and, in accordance with the target braking torques, specifies friction brake requirements to the friction brake control device and generator brake requirements to the electric drive control device . Further information relating to driving dynamics is transmitted to the wheel slip control device by a condition observer. The electric drive control device sends the currently applied generator braking torque(s) and/or the maximum generator braking torque(s) that can be generated to the torque distribution device and the division between friction braking requests and generator braking request(s) takes place taking into account the currently applied and/or maximum generator braking torque/s that can be generated.

It is the object of the invention to enrich the prior art and to enable improved control for braking a vehicle, in particular a commercial vehicle. An embodiment of the invention can solve the problem of providing a braking control system in which recuperation can be maintained to increase efficiency and a continuous braking torque can be generated in order to avoid a “hole”.

The task is solved by a method according to claim 1 and the subjects according to the further independent claims. The subclaims indicate preferred developments of the invention.

According to the invention, a method for operating a friction brake device for a vehicle having an electric drive set up for regenerative braking, in particular a commercial vehicle, is provided. The method comprises: detecting a braking request for braking the vehicle, in particular a commercial vehicle, with a target braking torque; Determining a maximum braking torque taking into account a threshold condition; Determining a friction braking torque for operating the friction braking device, wherein the friction braking torque is determined as a function of the maximum braking torque such that a generator braking torque of the electric drive has a positive control reserve and a negative control reserve; and operating the friction brake device according to the friction brake torque.

The vehicle, in particular a commercial vehicle, is referred to below as a vehicle. The vehicle includes wheels that can be braked by regenerative braking with the generator braking torque by the electric drive and by the friction brake device with the friction braking torque. A driver and/or an automated driving function can provide or trigger a braking request, which causes the electric drive and/or the friction brake device to brake the vehicle and/or one of the wheels with the target braking torque. The generator braking torque and the friction braking torque result in a total braking torque that has a braking effect on one or more wheels of the vehicle.

A maximum braking torque is determined based on a threshold value condition relating, for example, to the dynamics of the wheels. The maximum braking torque is the greatest total braking torque with which the vehicle's wheels can be braked safely and reliably, whereby the threshold condition is met. In other words, the maximum braking torque is the largest total braking torque that can be transmitted from a wheel to the ground while maintaining the slip and wheel deceleration limits that define the threshold condition. Such a transfer of the total braking torque from the wheel to the ground or the road takes place via contact between a tire of the wheel and the road. The threshold condition is fulfilled, for example, when slip falls below the slip limit and/or wheel deceleration falls below the wheel deceleration limit.

According to the method, the friction braking torque is determined as a function of the maximum braking torque such that the generator braking torque of the electric drive has a positive control reserve and a negative control reserve. A control reserve of the electric drive is the ability of the electric drive to change the generator braking torque. The positive control reserve allows the electric drive to increase the generator braking torque. A negative control reserve allows the electric drive to reduce the generator braking torque. Since the total braking torque is the sum of the generator braking torque and the friction braking torque, the generator braking torque and thus the control reserve are also determined by determining the friction braking torque, particularly when the target braking torque is set as the total braking torque. The control reserve or control capacity can be determined taking thermal aspects into account in order to avoid overheating of the electric drive.

It was recognized that in electrically driven vehicles a combined use of the highly dynamically controllable electric drive and the braking system can achieve advantages in terms of braking distance, performance and recuperation, since in current systems even short ABS controls lead to longer switch-off times for the continuous brakes and/or the electric Drive can lead. The advantageous dynamics of the electric drive can be used to continuously adjust the slip to a target value, while the high braking force of the braking system continues to be available in parallel. Recuperation can be maintained, which increases braking efficiency.

Preferably, the friction braking torque is determined such that the sum of the friction braking torque and a generator braking torque corresponding to the positive control reserve exceeds the maximum braking torque. This ensures that the electric drive can generate enough generator braking torque to achieve the maximum braking torque in combination with the friction braking torque. Furthermore, the electric drive does not have to be fully utilized, which can be advantageous from a thermal point of view.

The friction braking torque is preferably determined in such a way that the negative control reserve enables the generator braking torque to be reduced by 40% to 60% of a maximum generator braking torque of the electric drive. This means that the electric drive can be operated in such a way that the generator braking torque can be substantially increased or decreased at any time. The friction braking torque can also be determined in such a way that the negative control reserve enables the generator braking torque to be reduced by 80% of the maximum generator braking torque of the electric drive. This makes it possible to substantially reduce the generator braking torque, for example in order to be able to quickly adjust an appropriately lower generator braking torque when changing from a road with a comparatively high coefficient of friction to a road with a comparatively low coefficient of friction.

For the same reasons, the friction braking torque is preferably determined in such a way that the positive control reserve enables the generator braking torque to be increased by 40% to 60% of a maximum generator braking torque of the electric drive.

Preferably, the determination of the friction brake torque takes place taking into account a vehicle condition and/or a road surface characteristic. The positive control reserve and the negative control reserve of the electric drive are therefore also dependent on the vehicle condition and/or the road surface characteristics. The vehicle condition can in particular relate to the dynamics of the vehicle and/or the mass of the vehicle. The roadway property can in particular relate to a coefficient of friction between a wheel of the vehicle and a roadway or a surface on which the wheel is arranged.

Preferably, the friction brake torque is determined taking into account a state of charge of an energy storage device for storing electrical energy. For example, a friction braking torque that tends to be lower can be determined when the energy storage device has a comparatively low state of charge in order to charge the energy storage device through regenerative braking; A tendentially higher friction braking torque can be determined if the energy storage device has a comparatively high state of charge in order to reduce regenerative braking.

The friction brake torque is preferably determined in such a way that a smaller friction brake torque is determined with a comparatively large wheel deceleration than with a small wheel deceleration. In other words, a first wheel deceleration and a second wheel deceleration can be compared with one another. If the first wheel deceleration is greater than the second wheel deceleration, a smaller friction braking torque is determined for the first wheel deceleration than for the second wheel deceleration. It was recognized that a comparatively large wheel deceleration tends to lead to a higher tendency to stall than a small wheel deceleration. If a small friction braking torque is now determined, a comparatively large negative control reserve is retained in order to relax the generator braking torque if necessary using the quickly responding electric drive and thus reduce the risk of the wheel locking.

Preferably, the method comprises: detecting a change in a road surface and/or a coefficient of friction between the road surface and a wheel, and determining a change in friction brake torque taking the change into account. It was recognized that a change in the road surface causes a change in the maximum braking torque. Taking into account the change in the road surface and in particular a coefficient of friction between the road surface and the wheel of the vehicle when determining the change in friction brake torque to change the friction brake torque means that the control reserves of the electric drive are also taken into account depending on the road surface.

Preferably, in accordance with the change in friction brake torque, there is a gradual and/or continuous change in the friction brake torque. A gradual change in the friction braking torque comes into consideration, for example in the event of a sudden change in road surface properties and/or a coefficient of friction. A constant change in the friction braking torque can avoid unwanted vibration excitations and minimize the need to readjust the friction braking torque.

The friction braking torque can preferably be determined with a value of zero. For example, on a particularly slippery road surface, such as ice, the friction braking torque can be reduced to zero. This means that the vehicle is braked solely by the electric drive, which advantageously takes over the braking of the vehicle in such situations due to its high dynamics and control quality.

According to a further aspect of the invention, a computer program and/or computer-readable medium is provided. The computer program and/or computer-readable medium comprises instructions which, when the program or instructions are executed by a computer, cause the computer to carry out the method described here and/or the steps of the method described here. The computer program and/or computer-readable medium may include instructions to carry out steps of the method described as optional and/or advantageous in order to achieve a corresponding technical effect.

According to a further aspect of the invention, a control device for a friction brake device of a vehicle, in particular a commercial vehicle, is provided. The control unit is set up to carry out the procedure described here. The control device can be set up to carry out steps of the method described as optional and/or advantageous in order to achieve a corresponding technical effect.

According to a further aspect of the invention, a friction brake device for a vehicle, in particular a commercial vehicle, is provided. The friction brake device has the control unit described here. Alternatively, the control device can be a separate control device and/or a control device for the electric drive.

According to a further aspect of the invention, a vehicle, in particular a commercial vehicle, is provided. The vehicle has the control unit described here. The vehicle and/or the control unit can be set up to carry out steps of the method described as optional and/or advantageous in order to achieve a corresponding technical effect.

• 1 eine schematische Darstellung einer Übersicht eines Fahrzeugs, insbesondere Nutzfahrzeugs, gemäß einer Ausführungsform der Erfindung;
• 2 eine schematische Darstellung eines Ablaufschemas eines Verfahrens gemäß einer Ausführungsform der Erfindung; und
• 3 drei schematische Darstellungen von Bremsmomentkurven mit einem Bremsmoment als Funktion der Zeit.

Further advantages and features of the invention as well as their technical effects result from the figures and the description of the preferred embodiments shown in the figures. Show it

• 1 a schematic representation of an overview of a vehicle, in particular a commercial vehicle, according to an embodiment of the invention;
• 2 a schematic representation of a flowchart of a method according to an embodiment of the invention; and
• 3 three schematic representations of braking torque curves with braking torque as a function of time.

The vehicle 300a, in particular commercial vehicle 300b, is referred to below as vehicle 300a, 300b. The vehicle 300a, 300b is a land vehicle and, for example, a truck, a bus, a trailer and/or a multi-unit vehicle.

The vehicle 300a, 300b is set up to do this with reference to 2 and 3 to carry out the procedure 100 described. For this purpose, the vehicle 300a, 300b in the in 1 Embodiment shown has an electric drive 21, a control device 250, a friction brake device 40 and an energy storage device 260.

The control unit 250 is set up to receive and evaluate a braking request 55 for braking the vehicle 300a, 300b with a target braking torque 56. The braking request 55 can include a signal triggered by, for example, a pedal actuation and/or an actuation of a retarder lever by a driver of the vehicle 300a, 300b and/or by an automated driving function, which is sent to the control unit, for example via a vehicle bus (not shown). 250 is transferred.

The control unit 250 is set up to receive and evaluate information relating to a vehicle condition 350 and/or to calculate the vehicle condition 350. The vehicle state 350 can include information relating in particular to the dynamics of the vehicle 300a, 300b and/or a wheel 210 of the vehicle 300a, 300b. For example, the vehicle state 350 may include information about a mass of the vehicle 300a, 300b, an ambient temperature, a speed of the vehicle 300a, 300b, a charge state 261 of an energy storage device 260 and/or an acceleration of the vehicle 300a, 300b.

The controller 250 includes a processor 251 and a memory 252 to process and store information. The control unit 250 is thus set up to handle the in 2 and 3 carry out the steps of procedure 100 described. In particular, a threshold condition 59 is stored in the memory 252.

The control unit 250 is in the in 1 shown embodiment connected to the electric drive 21 and the friction brake device 40 in order to exchange control information 150 with the electric drive 21 and the friction brake device 40, in particular to receive measured values and send control signals.

The electric drive 21 is set up for regenerative braking NB. The electric drive 21 can generate a generator braking torque 25, which can lead to a deceleration of the vehicle 300a, 300b. The electric drive 21 can change, in particular reduce and increase, the generator braking torque 25.

The friction brake device 40 is an electrical brake system 43 or an electronically controlled brake system and can apply a friction brake torque 41. In an embodiment not shown, the friction brake device 40 is a pneumatic and/or hydraulic brake system.

The vehicle 300a, 300b according to 1 has several wheels 210. The wheels 210 are arranged on a roadway 215. A total braking torque 320 mediated by the roadway 215 and caused by the electric drive 21 and the friction brake device 40 can act on the wheels 210. The total braking torque 320 is the sum of generator braking torque 25 and friction braking torque 41. The road surface 215 can in particular be subject to local changes 216, as illustrated by the dashed line. The roadway 215 can, for example, have different surfaces at different locations and thus lead to different coefficients of friction μ.

The electric drive 21 can be set up as a so-called central drive to apply the generator braking torque 320 to several wheels 210 of an axle (not shown). The electric drive 21 is in the in 1 Embodiment shown is set up to apply the generator braking torque 320 individually to each wheel, whereby 1 only schematically illustrates the braking of a wheel 210.

The dynamics of each of the wheels 210 can be characterized by a measurable wheel acceleration or wheel deceleration 310 and/or a change in the wheel acceleration over time. The wheel deceleration 310 and/or the temporal change in the wheel acceleration can be detected by measured values of a wheel speed sensor (not shown) and/or by control information 150 of the electric drive 21. The effective total braking torque 320 causes slip between the wheel 210 and the road 215. The slip can be determined, for example, by wheel speeds.

The electric drive 21 is set up in the German patent application, which was not yet published at the time of registration 10 2022 114 084.9 to carry out the friction value estimation procedure described on June 3, 2022. For this purpose, the electric drive is set up to apply a predetermined excitation torque to the wheel 210, the excitation torque being applied to the wheel 210 periodically at a frequency; and from this to determine a change in slip depending on the excitation torque, the determination of the change in slip taking the frequency into account. The coefficient of friction μ is a road property 351.

The energy storage device 260 is set up to store and provide electrical energy 262. For this purpose, the energy storage device 260 is connected to the electric drive 21. The energy storage device 260 includes a plurality of battery cells and a battery controller (not shown). The energy storage device 260 has a charge state 261, which can be increased by regenerative braking NB and decreased by a drive.

2 shows a schematic representation of a flowchart of a method 100 according to an embodiment of the invention. The method 100 is a method 100 for operating a friction brake device 40 for a vehicle 300a, 300b having an electric drive 21 set up for regenerative braking NB. Such a vehicle 300a, 300b is in 2 shown. 3 is made with reference to 2 described.

The procedure 100 according to 2 has a detection 110 of a braking request 55 for braking the vehicle 300a, in particular commercial vehicle 300b, with a target braking torque 56. The target braking torque 56 is a target value for the total braking torque 320. However, the total braking torque 320 that can be applied can be limited, for example, due to a high slip and / or a low coefficient of friction μ, which can lead to braking the target braking torque 56 is not possible. Braking then takes place with a total braking torque 320 that is smaller than the target braking torque 56. Braking with the total braking torque 320 then takes place via a control of the slip and/or a wheel deceleration 310. For this purpose, a maximum braking torque 57 is determined and results indirectly from the control of the slip and/or a wheel deceleration 310 and is therefore a type of “manipulating variable”. Regulation.

A maximum braking torque 57 is determined 120 taking into account a threshold condition 59. The threshold condition 59 can in particular relate to the tendency of the wheel to lock. The threshold condition 59 can therefore be a condition for wheel deceleration 310 and/or slip. The maximum braking torque 57 can delay a wheel 210 without the wheel 210 blocking, a maximum permissible slip limit being exceeded and/or driving safety being endangered.

A friction brake torque 41 is determined 130 for operating 140 the friction brake device 40, the friction brake torque 41 being determined as a function of the maximum braking torque 57 in such a way that a generator braking torque 25 of the electric drive 21 has a positive control reserve 22 and a negative control reserve 23. For this purpose, the electric drive 21 is set up to transmit information relating to the positive control reserve 22 and the negative control reserve 23 to the control unit 250. The information can be dependent on the generator braking torque 25 and a maximum generator braking torque 26 that can be provided by the electric drive 21. The control reserves 22, 23 result from the generator braking torque 26, which is the difference between the target braking torque 56 or the maximum braking torque 57 and the friction braking torque 41 is.

The friction braking torque 41 is determined such that a sum of the friction braking torque 41 and a generator braking torque 25 corresponding to the positive control reserve 22 exceeds the maximum braking torque 57. For example, the friction braking torque 41 can be determined under the assumption that the sum of the generator braking torque 25 and the positive control reserve 22 exceeds the maximum braking torque 57 by a certain percentage of, for example, 10%. The friction brake torque 41 is determined in such a way that the negative control reserve 23 enables the generator brake torque 25 to be reduced by 40% to 60% of a maximum generator brake torque 26 of the electric drive 21. The friction brake torque 41 is determined accordingly such that the positive control reserve 22 enables the generator brake torque 25 to be increased by 40% to 60% of a maximum generator brake torque 26 of the electric drive 21. For example, the friction braking torque 41 is determined such that both an increase and a reduction in the generator braking torque 25 by 50% is possible.

The positive control reserve 22 and the negative control reserve 23 are also related to 3 described.

Determining 130 the friction brake torque 41 according to in 2 The method 100 shown takes place taking into account a vehicle state 350 and/or a road property 351. The determination 130 of the friction brake torque 41 takes place in particular taking into account a charge state 261 of an energy storage device 260 for storing electrical energy 262. The determination 130 of the friction brake torque 41 takes place in such a way that With a comparatively large wheel deceleration 310, a smaller friction braking torque 41 is determined than with a small wheel deceleration 310.

This is followed by detection 131 of the change 216 in the roadway 215 and/or the coefficient of friction µ between the roadway 215 and one of the wheels 210. The detection 131 of the change 216 can take place, for example, via a vehicle-side sensor, the information relating to the roadway 215, for example, for evaluation detected by the control unit 250. The coefficient of friction µ can be as in the German patent application, which was not yet published at the time of registration 10 2022 114 084.9 from June 3rd, 2022 can be determined. A determination 132 of a change in friction brake torque 44 takes place, taking into account the change 216. According to the change in friction brake torque 44, a gradual and/or continuous change in the friction brake torque 41 takes place.

The friction brake device 40 is operated 140 in accordance with the friction brake torque 41. The friction brake torque 41 can be determined with a value of zero. In other words, the friction brake device 40 is thrown off. Braking then occurs solely through the electric drive 21. The total braking torque 320 is then equal to the generator braking torque 25.

3 shows three schematic representations ( 3 (A) , 3 (B) and 3 (C) ) each of braking torque curves 400 with a braking torque M as a function of time t. A curve 401 shown with a dotted line shows the dependence of the friction brake torque 41 on the time t. Each curve 402 shown with a solid line shows the total braking torque 320 as the sum of the friction braking torque 41 and the generator braking torque 25 depending on the time t. The generator braking torque 25 as such is in the 3 not shown. Each curve 403 shown with a dashed line shows a maximum total braking torque 322 as the sum of the friction braking torque 41 and the maximum generator braking torque 26 that can be provided. 3 serves to further describe the method 100 according to 2 .

The curves 400 are each characterized by a time t1. Initially and until time t1, regulation of the generator braking torque 25 is passive. The generator braking torque 25 is constant and the friction braking torque 41 follows the braking request 55 or the target braking torque 56.

From time t2 onwards, regulation of the generator braking torque 25 is active. The generator braking torque 25 is regulated so that the threshold condition 59 remains as fulfilled as possible.

In the in 3 (A) In the scenario shown, the brake pressure or the friction brake torque is maintained.

In the in 3 (B) In the scenario shown, at the beginning of the control at time t1, the electric drive 21 is fully or almost fully utilized. The friction brake torque 41 is therefore adjusted in order to relieve the load on the electric drive 21. The friction brake torque 41 is thus increased. The friction brake torque 41 is increased in such a way that the electric drive 21 can increase the generator braking torque by 50% and also reduce it by 50%. The electric drive 21 is therefore relieved and receives a balanced control reserve 22, 23 in both directions, i.e. a negative control reserve 23 balanced with the positive control reserve 22.

In the in 3 (C) In the scenario shown, at the beginning of the control at time t1, the electric drive 21 is only used comparatively little. The friction brake torque 41 is therefore adjusted in order to load the electric drive 21. The friction brake torque 41 is thus reduced. The friction brake torque 41 is reduced in such a way that the electric drive 21 can increase the generator braking torque by 50% and also reduce it by 50%. The electric drive 21 is therefore loaded and receives a balanced control reserve 22, 23 in both directions, i.e. a negative control reserve 23 balanced with the positive control reserve 22.

Reference symbols (part of the description):

21

electric drive

22

positive control reserve

23

negative control reserve

25

Generator braking torque

26

maximum generator braking torque

40

Friction brake device

41

Friction braking torque

43

electric braking system

44

Friction brake torque change

55

Braking request

56

Target braking torque

57

Maximum braking torque

59

Threshold condition

100

Proceedings

110

Detecting a braking request

120

Determine

130

Determine

131

Capture a change

132

Determining a friction brake torque change

140

Operate

150

Rules information

210

wheel

215

roadway

216

the change

250

Control unit

251

processor

252

Storage

260

Energy storage device

261

charging status

262

electrical power

300a

vehicle

300b

Commercial vehicle

310

Wheel deceleration

320

Total braking torque

322

maximum total braking torque

350

Vehicle condition

351

Road characteristics

400

Braking torque curve

401

Curve

402

Curve

403

Curve

M

Braking torque

µ

Friction coefficient

NB

Regenerative braking

t

Time

t1

time

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102019135087 A1 [0005]
• DE 102012217679 A1 [0006]
• DE 102022114084 [0039, 0048]

Claims (14)

Method (100) for operating a friction brake device (40) for a vehicle (300a), in particular commercial vehicle (300b), having an electric drive (21) set up for regenerative braking (NB), the method (100) comprising: - Detecting (110) a braking request (55) for braking the vehicle (300a), in particular commercial vehicle (300b), with a target braking torque (56); - Determining (120) a maximum braking torque (57) taking into account a threshold condition (59); - Determining (130) a friction braking torque (41) for operating (140) the friction braking device (40), the friction braking torque (41) being determined as a function of the maximum braking torque (57) in such a way that a generator braking torque (25) of the electric drive (21 ) has a positive control reserve (22) and a negative control reserve (23); and - Operate (140) the friction brake device (40) according to the friction brake torque (41). Procedure according to Claim 1 , wherein the friction braking torque (41) is determined such that a sum of the friction braking torque (41) and a generator braking torque (25) corresponding to the positive control reserve (22) exceeds the maximum braking torque (57). Procedure according to Claim 1 or 2 , wherein the friction braking torque (41) is determined such that the negative control reserve (23) enables a reduction in the generator braking torque (25) by 40% to 60% of a maximum generator braking torque (26) of the electric drive (21). Method according to one of the preceding claims, wherein the friction braking torque (41) is determined such that the positive control reserve (22) enables an increase in the generator braking torque (25) by 40% to 60% of a maximum generator braking torque (26) of the electric drive (21). . Method according to one of the preceding claims, wherein the determination (130) of the friction brake torque (41) takes place taking into account a vehicle condition (350) and/or a road surface characteristic (351). Method according to one of the preceding claims, wherein the determination (130) of the friction braking torque (41) takes place taking into account a state of charge (261) of an energy storage device (260) for storing electrical energy (262). Procedure according to Claim 5 , wherein the determination (130) of the friction brake torque (41) is carried out in such a way that a smaller friction brake torque (41) is determined with a comparatively large wheel deceleration (310) than with a small wheel deceleration (310). Method according to one of the preceding claims, wherein the method (100) comprises: - Detecting (131) a change (216) in a road surface (215) and/or a coefficient of friction (p) between the road surface (215) and a wheel (210), and - Determine (132) a change in friction brake torque (44) taking the change (216) into account. Procedure according to Claim 8 , wherein according to the change in friction brake torque (44), a gradual and / or constant change in the friction brake torque (41) takes place. Method according to one of the preceding claims, wherein the friction braking torque (41) can be determined with a value of zero. Computer program and/or computer-readable medium, comprising commands which, when the program or commands are executed by a computer, cause the computer to carry out the method (100) and/or the steps of the method (100) according to one of Claims 1 until 10 to carry out Control device (250) for a friction brake device for a vehicle (300a), in particular commercial vehicle (300b), the control device (250) being set up to carry out the method (100) according to one of Claims 1 until 10 to carry out. Friction brake device for a vehicle (300a), in particular commercial vehicle (300b), comprising the control device Claim 12 . Vehicle (300a), in particular commercial vehicle (300b), comprising the control unit (250). Claim 12 and/or the friction brake device Claim 13 .

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