CN116588054A - Method for operating a motor vehicle, control device, and motor vehicle - Google Patents

Method for operating a motor vehicle, control device, and motor vehicle Download PDF

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Publication number
CN116588054A
CN116588054A CN202310132799.9A CN202310132799A CN116588054A CN 116588054 A CN116588054 A CN 116588054A CN 202310132799 A CN202310132799 A CN 202310132799A CN 116588054 A CN116588054 A CN 116588054A
Authority
CN
China
Prior art keywords
pedal
deceleration
brake
deceleration torque
torque
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310132799.9A
Other languages
Chinese (zh)
Inventor
M·古比
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of CN116588054A publication Critical patent/CN116588054A/en
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T1/00—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles
    • B60T1/02—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels
    • B60T1/10—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels by utilising wheel movement for accumulating energy, e.g. driving air compressors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B60L15/2009—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed for braking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L7/00—Electrodynamic brake systems for vehicles in general
    • B60L7/24—Electrodynamic brake systems for vehicles in general with additional mechanical or electromagnetic braking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L7/00—Electrodynamic brake systems for vehicles in general
    • B60L7/24—Electrodynamic brake systems for vehicles in general with additional mechanical or electromagnetic braking
    • B60L7/26—Controlling the braking effect
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/74—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive
    • B60T13/745—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive acting on a hydraulic system, e.g. a master cylinder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T7/00—Brake-action initiating means
    • B60T7/02—Brake-action initiating means for personal initiation
    • B60T7/04—Brake-action initiating means for personal initiation foot actuated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/12—Speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2250/00—Driver interactions
    • B60L2250/26—Driver interactions by pedal actuation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2270/00—Problem solutions or means not otherwise provided for
    • B60L2270/10—Emission reduction
    • B60L2270/14—Emission reduction of noise
    • B60L2270/142—Emission reduction of noise acoustic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T2270/00—Further aspects of brake control systems not otherwise provided for
    • B60T2270/60—Regenerative braking
    • B60T2270/604—Merging friction therewith; Adjusting their repartition
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

Landscapes

  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)
  • Regulating Braking Force (AREA)

Abstract

The invention relates to a method for operating a motor vehicle, comprising a brake system having a hydraulic brake system with a controllable pressure generator and a friction brake hydraulically connectable to the pressure generator and an electric motor, which can be operated in the manner of a generator in order to decelerate the motor vehicle; and has a running pedal and a brake pedal, and a deceleration moment of the brake system can be requested by manipulating the brake pedal and by releasing the running pedal; the braking system is controlled as a function of the first deceleration torque requested by the driving pedal and the second deceleration torque requested by the braking pedal in such a way that, of the rotational speeds above a predefinable limit rotational speed of the electric motor, the requested total deceleration torque is only achieved by the electric motor, below which the requested total deceleration torque is transmitted from the electric motor to the braking device by means of the control pressure generator. Above the limit rotational speed, the first deceleration torque required by the running pedal is reduced in accordance with the second deceleration torque required by the brake pedal.

Description

Method for operating a motor vehicle, control device, and motor vehicle
Technical Field
The invention relates to a method for operating a motor vehicle having a brake system which has, on the one hand, a hydraulic brake system with a controllable pressure generator and a friction brake hydraulically connectable to the pressure generator and, on the other hand, an electric motor, wherein the electric motor can be operated in the manner of a generator in order to reduce the speed of the motor vehicle; and having a driving pedal and a braking pedal, wherein by actuating the braking pedal and at least by releasing the driving pedal, i.e. by not actuating the driving pedal or by bringing the driving pedal into an unactuated initial position, a deceleration torque of the braking system can each be requested, and wherein the braking device is controlled as a function of a first deceleration torque requested by the driving pedal and a second deceleration torque requested by the braking pedal, such that, in a driving speed above a predefinable limit rotational speed of the motor, a requested total deceleration torque, which in particular corresponds to the sum of the first and second deceleration torques, is achieved only by the motor, and in the case of a rotational speed below the limit rotational speed, i.e. by a deceleration process, the rotational speed falls below the limit rotational speed, the requested total deceleration torque is transmitted from the motor to the braking device by the control pressure generator.
Furthermore, the invention relates to a computer program, a machine-readable data carrier and a control device.
Background
Methods of the type mentioned at the outset are already known from the prior art. For decelerating a motor vehicle, braking devices are generally used which have hydraulically actuated friction brakes which generate a braking torque or a braking force at the wheels of the motor vehicle, respectively, in order to decelerate the motor vehicle. In newer motor vehicles, braking devices are increasingly used in which braking forces can also be generated independently of the actuation of the brake pedal by controlling a pressure generator in the hydraulic circuit. The pressure generator is, for example, an electrically driven hydraulic pump which can interact in particular with a safety system of the motor vehicle, such as, for example, an ESP system (esp=electronic stability program), and which performs a separate braking intervention independently of the actuation of the brake pedal. With the increasing electrification of motor vehicles and the improvement of drives with electric machines, the possibility of regenerative braking is also perceived and optimized, i.e. the deceleration of the motor vehicle caused by the running of the electric generator of one or more electric machines in the drive train, in order to improve in particular the energy distribution of the motor vehicle and reduce the wear of the mechanical friction brakes. With the development of electric vehicles, so-called single pedal solutions have also been developed, in which the user can request not only an acceleration torque but also a deceleration torque by actuating a single running pedal. For this purpose, systems are known in which the driver can set a predetermined deceleration torque for the motor vehicle by completely releasing the driving pedal in order to decelerate the vehicle until the vehicle is stopped, without using a hydraulic brake system which is present in parallel with it or without having to actuate the brake pedal.
However, since the electric machine loses efficiency in the low rotational speed range and in particular in generator-mode operation the adjustable deceleration torque likewise decreases with a decrease in rotational speed, it is known to transmit or transfer the deceleration torque previously provided by the electric machine to the hydraulic brake system before a stop is reached. In order to eliminate the driver having to actuate the brake pedal for this purpose, the brake device is activated by a pressure generator, so that hydraulic pressure acting on one or more friction brakes of the motor vehicle is automatically generated. The deceleration torque subsequently generated by the friction brake replaces the deceleration torque reduced from the motor. In particular, the motor and the braking device are controlled such that they compensate each other, i.e. increase the friction braking torque and decrease the motor braking torque, in particular in correspondence to an increase in the friction braking torque.
The method can also be easily performed and is comfortable if the driver uses only the running pedal during the deceleration process. However, at the moment when the driver requests a higher second deceleration torque by actuating the brake pedal, which should therefore cause a higher deceleration than the first deceleration torque, hydraulic pressure is already generated in the hydraulic components of the brake system or in the brake device by moving the brake pedal, which hydraulic pressure is then increased further by the control pressure generator when the deceleration torque is transmitted from the electric motor to the brake device. Since the driver has already operated the brake pedal with his foot at this point in time, he gets a haptic feedback from the hydraulic brake circuit, which is uncomfortable and furthermore also leads to acoustic disturbance events. Just in the low rotational speed range, where the driving noise and the ambient noise are reduced, the acoustic events in the brake device or the brake system can be perceived more clearly. It may furthermore happen that the pressure generator extracts hydraulic medium from the master brake cylinder of the brake system for transfer in order to supply it to the friction brake, whereby the reaction force acting on the brake pedal is reduced and the driver therefore unintentionally depresses the brake pedal further. Further depression is detected by the brake system as an increased deceleration requirement if necessary, as a result of which a self-amplification of the required deceleration torque takes place, which results in a deceleration torque which is higher than the deceleration torque actually desired by the driver.
Disclosure of Invention
The method according to the invention with the features of claim 1 has the advantage that the above-mentioned disadvantages are overcome. In a simple manner, the method according to the invention makes it possible to avoid not only undesired acoustic events but also the elimination of reaction forces acting on the brake pedal when the driver presets the deceleration moment using not only a single pedal function but also the actuation of the brake pedal.
The method according to the invention is characterized in that above the limit rotational speed, the first deceleration torque required by the driving pedal is reduced in accordance with the second deceleration torque required by the brake pedal. The invention therefore provides that, in the event of a braking torque of the brake system being requested not only by the brake pedal but also by the travel pedal, a first deceleration torque preset by the travel pedal, which is in particular completely released, is actively reduced. It is thereby achieved that an overlap of the braking torque in the brake device and the motor is reduced and in particular completely avoided. Once the limit speed is undershot and the transmission of the total deceleration torque from the electric machine to the brake device begins, only or at least substantially the deceleration torque required for actuating the brake pedal is acted upon at this point in time. It is thereby achieved that, at the point in time of transmission, by moving the brake pedal, hydraulic medium is already stored in the hydraulic circuit and in particular in the hydraulic pressure accumulator, and that the deceleration torque is furthermore achieved only by the electric motor. When the transmission is now taking place, hydraulic medium is not fed from the master brake cylinder, but from the hydraulic reservoir by the pressure generator of at least one of the friction brakes. As a result, the position of the brake pedal is not affected by the generation of the hydraulic pressure in the hydraulic circuit, and the reaction force acting on the brake pedal is not reduced, so that the driver does not unintentionally further step on or depress the brake pedal. On the one hand, a self-amplification of the required deceleration torque is thus prevented, and on the other hand, no additional hydraulic volume has to be transferred to achieve the deceleration required by the running pedal. Thus avoiding acoustic and tactile events generated by driving the pressure generator in the presence of already existing hydraulic pressure. Thus, by actuating the brake pedal, the hydraulic volume that has been introduced into the brake circuit serves to transfer the deceleration torque of the electric motor to the brake device and thus ensures a comfortable transition to deceleration to the vehicle stop. In particular, the limit speed is preset as a function of the machine characteristics of the electric machine, so that the electric machine can achieve the required deceleration torque if the limit speed is exceeded. Preferably, when determining the total deceleration torque due to the braking request by releasing the running pedal and operating the brake pedal, the two requested deceleration torques are taken into account such that they are added to the total deceleration torque.
Preferably, the first deceleration torque is reduced by a predefinable offset value. The deceleration torque demand of the travel pedal is thus not itself changed, but is compensated by the offset value, so that the total deceleration demand of the travel pedal is transmitted incompletely, i.e. with a predefinable offset value, to the motor and/or the brake system. This ensures an advantageous reduction without interfering with the actual driving pedal control.
It is furthermore preferably provided that the first deceleration torque is continuously reduced, in particular in the form of a ramp, so that the reduction of the first deceleration torque is not noticeable to the driver and a smooth transition is ensured.
It is furthermore preferably provided that the first deceleration torque is reduced in response to an increase in the second deceleration torque. It is thus ensured that, when the driver actuates the brake pedal, the required second deceleration torque compensates at least for the reduction of the first deceleration torque, so that the driver does not feel or hardly feel the compensation or the reduction of the first deceleration torque.
It is particularly preferred that the first deceleration torque is reduced only when the vacuum brake booster of the system is activated by actuating the brake pedal. The reduction of the first deceleration torque therefore does not take place immediately as the brake pedal is actuated, but only when the brake pedal has been actuated so far that the vacuum brake booster of the brake device begins its operation. In this case, a Jump-In-Level of the vacuum brake booster is discussed. This level of jump is achieved when the brake pedal actuation not only moves the hydraulic piston in the master brake cylinder, but also uses the function of the vacuum brake booster that normally begins only after the brake pedal has been moved a short distance. As soon as this function is activated, the hydraulic volume in the hydraulic circuit increases more significantly, or more hydraulic volume is displaced out of the master brake cylinder, so that in particular then the reduction of the first deceleration torque has the desired result. By activating the vacuum brake booster, the control of the pressure generator for transferring the total deceleration torque to the brake system or the hydraulic brake device is less obvious to the driver and is considered acceptable.
It is furthermore preferably provided that the first deceleration torque decreases until zero, so that the single pedal function is finally deactivated. The total deceleration torque thus corresponds to the second deceleration torque required by the brake pedal. The above-mentioned advantages of the method according to the invention are achieved to a certain extent by reducing the first deceleration torque until zero.
In the event that the driver releases the brake pedal again before the limit speed is undershot, and the second deceleration torque is therefore reduced or set to zero, and the driving pedal remains in the released position, it is preferably provided that the first deceleration torque is increased again, in particular by reducing the above-described offset value. If the driver moves his foot away from the brake pedal before the mentioned limit speed is reached, so that the brake pedal is again shifted back to its initial position and thus released, and the second deceleration moment is set to zero as a result, the total deceleration moment is set to zero without taking further measures by previously reducing the first deceleration moment. However, since the driver desires to further slow down the motor vehicle by means of the previously described single pedal function, according to a preferred development, when the brake pedal is released, the reduction of the first deceleration moment is undone in order to further slow down the motor vehicle and the single pedal function is fulfilled. In this development, the first deceleration torque and the second deceleration torque are, in particular, not added to each other but are preferably taken into account parallel to each other when increasing the first deceleration torque, so that only the corresponding higher deceleration torque determines the total deceleration torque or so that the total deceleration torque corresponds to the higher of the two required deceleration torques.
In this case, the first deceleration torque preferably increases up to an initial value at which the reduction has already been initiated, in particular up to a preset maximum value of the first deceleration torque. In this way, a single pedal function is again established, and the motor vehicle is decelerated in accordance with the actuation of the driving pedal. The maximum value is set in particular as a function of the performance of the electric machine in generator mode operation and as desired by the vehicle manufacturer, so that a comfortable and safe deceleration can be achieved for the driver with the single pedal function only with the electric machine. The maximum value can be adjusted and varied in this case, for example, as a function of a driving mode, such as a sporty driving mode or an efficiency mode.
Preferably, the first deceleration torque is initially only increased such that it corresponds at maximum to the second deceleration torque, as a function of the release of the brake pedal.
Preferably, the first retarding torque increases beyond the second retarding torque only when the second retarding torque is below the maximum of the first retarding torque. This is advantageous to a certain extent, since only then can a deceleration moment be achieved by the running pedal.
Preferably, the first deceleration torque is increased in accordance with a maximum possible deceleration torque increase of the electric machine, so that a partial or proportional realization of the deceleration torque by the hydraulic brake system is avoided. Thereby further avoiding the acoustic and tactile events described above. The total deceleration torque corresponds to the first deceleration torque as soon as the first deceleration torque exceeds the second deceleration torque, wherein the total deceleration torque corresponds to the first deceleration torque as soon as the brake pedal is completely released. Then, the total deceleration torque increases up to the maximum value of the first deceleration torque, and the driver regains the single pedal function.
The computer program according to the invention having the features of claim 12 is characterized by machine-readable instructions which, when executed on one or more computers, cause said one or more computers to perform the method according to the invention. Thereby yielding the advantages already mentioned above.
The machine-readable data carrier according to the invention having the features of claim 13 is characterized by a computer program according to the invention.
The control device according to the invention having the features of claim 14 is characterized in that it is equipped with a computer program according to the invention and/or a machine-readable data carrier according to the invention.
Drawings
Further advantages and preferred features and feature combinations result from the foregoing description and the claims, in particular. Hereinafter, the present invention should be described in detail with reference to the accompanying drawings. To this end:
figure 1 shows an advantageous motor vehicle in a simplified top view,
figure 2 shows a diagram for elucidating an advantageous method of operation of a motor vehicle,
fig. 3 shows a further diagram for illustrating an advantageous further development of the operating method.
Detailed Description
Fig. 1 shows a motor vehicle 1 with an advantageous braking system 2 in a simplified top view. The motor vehicle 1 has at least one electric machine 3 as a drive system according to the present exemplary embodiment, which can be coupled to a drive wheel of the motor vehicle 1. The electric machine 3 can be operated in the manner of an electric motor and a generator, wherein the electric machine applies a braking torque or a deceleration torque to the drive wheels in the generator mode of operation, so that the electric machine 3 in the generator mode of operation belongs to the brake system 2, in order to, for example, achieve or jointly achieve a braking or deceleration requirement of the driver of the motor vehicle 1. Optionally, the motor vehicle 1 has an internal combustion engine as a drive (not shown in the drawing) in addition to the electric motor 3.
The brake system 2 further comprises a brake pedal 4 as a braking force demand element or a retarding torque demand element, which can be actuated by the driver. The brake pedal 4 can be displaced between an unactuated or released initial position and a maximally actuated or depressed end position. The brake pedal 4 is mechanically coupled to the master brake cylinder 5 or to a hydraulic piston thereof. The master brake cylinder 5 generates a hydraulic brake pressure as a function of a brake pedal actuation, which is distributed according to the present embodiment via a pressure distributor 6, for example of an ESP system, having a plurality of controllable valves to friction brakes 7, which are each connected to a wheel of the motor vehicle. In this case, a vacuum brake booster 9 is connected between the brake pedal 4 and the master brake cylinder 5, which increases the force acting on the hydraulic piston as a function of the brake pedal position in order to support the driver when actuating the brake system. Furthermore, a sensor device 10 with a pedal travel sensor 11 is assigned to the brake pedal 4, by means of which the current actuating position of the brake pedal 4 or the current distance of the brake pedal 4 from the initial position is monitored. The sensor device 10 is connected to a control device 12 for this purpose, which operates the brake system 2.
The brake system 2 also has a controllable pressure generator 13, which has in particular an electrically driven or electrically drivable hydraulic pump. By controlling the pressure generator 13 to increase the hydraulic pressure in the brake device with the pressure distributor 6 and the friction brake 7, a deceleration of the motor vehicle 1 can be caused even without driver assistance, in particular without actuation of the brake pedal 4. For this purpose, the pressure generator 13 is also connected to the control device 12.
The motor vehicle 1 further has a travel pedal 14, to which a travel pedal sensor 15 for monitoring the travel pedal position is assigned, wherein the travel pedal sensor 15 is also connected to the control device 12. The travel pedal 14 can be moved by the driver from the released initial position into the fully depressed end position.
The control device 12 is designed to control the motor 3 in dependence on the travel pedal position in order to generate an acceleration torque. Furthermore, the control device 12 is designed to request a deceleration torque of the brake system 2 as a function of the driving pedal position 14. For this purpose, the travel pedal 14 operates with a so-called single pedal function. It is provided here that a predetermined first deceleration torque is required at least when the driving pedal 14 is in the initial position of release. Preferably, starting from a preset intermediate position of the driving pedal 14 between the end position and the release position, instead of the acceleration torque, a deceleration torque is requested which increases with a gradual approach of the driving pedal 14 to the release position until it reaches the maximum permissible deceleration torque.
It is thus possible for the driver of the motor vehicle 1 to decelerate the motor vehicle 1 in the following manner: the driver actuates the brake pedal 4 in order to perform a hydraulic braking process by means of the friction brake 7 and also decelerates the motor vehicle by releasing the travel pedal 14. The control device 12 is designed to implement the first deceleration torque required by the driving pedal 14 at least by means of a generator-mode operation of the electric machine 3. If the current driving speed and/or the deceleration torque achievable by the motor 3 is permitted, the control device 12 is furthermore also designed to generate the second deceleration torque required by the brake pedal 4 solely by the motor 3. For this purpose, the electric machine 3 is controlled in dependence on the brake pedal position detected by means of the sensor 11 in order to slow down the motor vehicle 1. However, since the driver, when actuating the brake pedal 4, in any case transports the hydraulic medium into the brake circuit, the hydraulic medium is preferably accommodated in the hydraulic reservoir 16 of the hydraulic brake device in this case without actuating the friction brake 7.
According to fig. 2, an advantageous method for operating the motor vehicle 1, which is executed in particular by a computer program stored in the control device 12, should now be described in detail.
Fig. 2 shows the braking force F applied at time t B This braking force results in a deceleration moment of the motor vehicle 1, which can be achieved by actuating the driving pedal and the brake pedal. Here, a traveling state is taken as a starting point, and the vehicle is travelingThe motor vehicle has a speed greater than zero in the state. In this diagram, a first characteristic curve K1 is plotted, which represents a first deceleration torque requested by the driving pedal 14. Furthermore, a characteristic curve K2 is plotted which represents the second deceleration torque required by the brake pedal 4. The third characteristic curve K3 shows the total deceleration torque of the motor vehicle 1 produced by the electric machine 3 as a function of the pedal actuation.
In the case of an operation in which the driver first activates or uses the single pedal function of the driving pedal 14 by releasing the driving pedal 14 and then actuates the brake pedal 4, the following scenario illustrated in fig. 2 occurs:
first, the driver at time t 1 The running pedal 14 (characteristic curve K1) is released, so that the first deceleration torque is required. This deceleration torque is achieved only by the motor 3 (characteristic curve K3). The deceleration torque adjustable by the single pedal function is limited in particular to a maximum value K1 max The maximum value is smaller than the maximum available deceleration torque of the motor 3. If the driver releases only the driving pedal 14, the maximum achievable deceleration torque K1 is thus used max The motor vehicle 1 is decelerated to a stop.
If now the driver, because he wants for example the motor vehicle to stop faster, is at a later point in time t 2 The brake pedal 4 (characteristic curve K2) is additionally actuated, so that the total deceleration torque increases, in particular exceeds the maximum value, as a function of a second deceleration torque required by actuation of the brake pedal, wherein the second deceleration torque is in particular added to the first deceleration torque in order to determine the total deceleration torque.
As soon as the brake pedal 4 is actuated so far that the vacuum brake booster 9 begins to support the braking force generation (level jump), the first deceleration torque requested by the driving pedal 14 is continuously reduced by adding the offset value until it is at the point in time t 3 Is fully compensated. The total deceleration torque (characteristic curve K3) is thus also determined only by the second deceleration torque required by the actuation of the brake pedal (characteristic curve K2).
As the driving speed of the motor vehicle 1 decreases, the rotational speed of the motor 3 decreases due to the required total deceleration. At time point t 4 The generator-mode torque can no longer be or can no longer be effectively maintained by the electric machine 3. The limit speed at which this point in time is determined is derived from the machine characteristics of the motor 3 itself and is therefore dependent on the 3 motor used. Once at the current point in time t 4 When the limit rotational speed is reached, the control device 12 controls the brake system 2 such that the total deceleration torque provided by the motor 3 is now completely transferred to the hydraulic service brake or brake system. For this purpose, the deceleration torque of the motor 3 is reduced at a predetermined speed, and the deceleration torque which can be generated by the friction brake 7 is increased, in particular, at the same speed. For this purpose, fig. 2 shows a fourth characteristic curve K4, which shows the deceleration torque generated by the hydraulic brake system, from time t 4 The increase starts until the required total deceleration torque is reached. At the same time, the generator-mode deceleration torque (characteristic curve K3) decreases, so that the total deceleration torque remains constant until the motor vehicle 1 is stopped.
Since the previous first deceleration moment was returned to zero by a decrease in the offset value (point in time t 3 ) So at time point t 4 The total deceleration torque corresponds to the second deceleration torque required by the brake pedal 4. Since in this state the brake pedal 4 has been actuated and the hydraulic medium has been transferred or moved into the hydraulic circuit by the actuation of the user, the pressure generator 13 is now controlled for the purpose of generating a friction braking force (characteristic curve K4), for the purpose of transferring a deceleration torque to the braking device, for the purpose of sucking up the hydraulic volume already present in the hydraulic circuit, in particular from the hydraulic pressure accumulator 16, and for this purpose, for the purpose of applying the friction brake 7 by means of the pressure distributor 6 in a targeted manner in order to achieve the desired deceleration torque by friction braking. Since it is thus not necessary to extract additional hydraulic volume from the master brake cylinder, the brake pedal remains in the pedal position preset by the driver and haptic feedback on the brake pedal and undesired interference noise caused by operation of the hydraulic pump are avoided, otherwise the hydraulic pump has to extract additional hydraulic volume from the master brake cylinder and/or the hydraulic medium reservoir in order to be able to compensate for the first deceleration which is not reduced in additionMoment.
Fig. 3 shows an advantageous development of the above-described method, which involves a subsequent operation in which the driver is at time t before a stop is reached, and in particular before the limit speed of the electric machine 3 is reached 5 Removing its foot from the brake pedal 4 or releasing the brake pedal 4. At a subsequent point in time t 6 The second deceleration torque is reduced to zero. Thus, by the above method, no deceleration torque is now required anymore, and the motor vehicle 1 will slowly coast to a stop (ausrollen).
However, in order to provide the driver with the single pedal function he desires in driving operation, it is therefore preferable to cancel the reduction of the first deceleration torque by releasing the brake pedal 4. In particular, as the brake pedal 4 is released, the determination of the total deceleration torque is changed in such a way that the two required deceleration torques are compared with one another and the respectively higher one of the first and second deceleration torques is used or determined as the total deceleration torque. From time point t 5 Initially, the reduction of the first deceleration torque is first rapidly cancelled, as shown by the characteristic curve I, so that it compensates for the cancelled deceleration torque of the brake pedal without the need to transport additional hydraulic medium into the hydraulic circuit. It is considered how quickly the deceleration torque that can be provided by the motor 3 can be increased. As long as this deceleration moment is not exceeded, no additional hydraulic medium has to be transported in the brake circuit. Correspondingly, the first deceleration torque is further guided to a maximum value K1 according to characteristic curve II max So that the total deceleration torque is furthermore only provided by the motor 3, depending on the braking requirement of the single pedal function. The motor vehicle 1 is thus subsequently decelerated for the driver according to the desired single pedal function, if necessary until a stop.

Claims (14)

1. A method for operating a motor vehicle (1) having a brake system (2) with a hydraulic brake system having a controllable pressure generator (13) and at least one friction brake (7) hydraulically connectable to the pressure generator (13), and an electric motor (3), wherein the electric motor (3) can be operated in the manner of a generator in order to decelerate the motor vehicle (1); and having a travel pedal (14) and a brake pedal (4), wherein a deceleration torque of the brake system (2) can be requested by actuating the brake pedal (4) and by releasing the travel pedal (14); and wherein the brake system (1) is controlled in dependence on a first deceleration torque required by the driving pedal (14) and a second deceleration torque required by the brake pedal (4) such that, in case the rotational speed is higher than a presettable limit rotational speed of the motor (3), the required total deceleration torque is achieved by the motor (3) only and, in case the rotational speed is lower than the limit rotational speed, the required total deceleration torque is transmitted from the motor (3) to the brake device by controlling the pressure generator (13), characterized in that, in case the rotational speed is higher than the limit rotational speed, the first deceleration torque required by the driving pedal (14) is reduced in dependence on the second deceleration torque required by the brake pedal (4).
2. The method of claim 1, wherein the first retarding torque is reduced by a presettable bias value.
3. A method according to any one of the preceding claims, wherein the first retarding torque is continuously reduced.
4. A method according to any one of the preceding claims, characterized in that the first retarding torque is reduced in correspondence with an increase of the second retarding torque.
5. Method according to any of the preceding claims, characterized in that the first deceleration moment is reduced only when the vacuum brake booster (9) of the brake system (2) is activated by operating the brake pedal.
6. A method according to any one of the preceding claims, wherein the first retarding torque is reduced until zero.
7. Method according to any one of the preceding claims, characterized in that the first deceleration moment is increased for the case of releasing the brake pedal (4) and holding the travel pedal (14) in the released travel pedal position before the limit speed is lower, in particular by reducing the offset value.
8. Method according to claim 7, characterized in that the first deceleration torque is increased up to an initial value, at which the reduction has been initiated, in particular up to a preset maximum value of the first deceleration torque.
9. Method according to any one of the preceding claims, characterized in that, upon release of the brake pedal (4), the first deceleration moment is first only increased such that it corresponds at maximum to the second deceleration moment.
10. A method according to any one of the preceding claims, characterized in that the first retarding torque increases beyond the second retarding torque only when the second retarding torque is below a limit value.
11. A method according to claim 10, characterized in that the first deceleration moment is increased in accordance with the largest possible deceleration moment increase of the motor (3).
12. A computer program comprising machine-readable instructions which, when executed on one or more computers, cause the one or more computers to perform the method of any one of claims 1 to 11.
13. A machine-readable data carrier having a computer program according to claim 12.
14. Computer, in particular control device, provided with a computer program according to claim 12 and/or with a machine-readable data carrier according to claim 13.
CN202310132799.9A 2022-02-11 2023-02-09 Method for operating a motor vehicle, control device, and motor vehicle Pending CN116588054A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102022201455.3A DE102022201455A1 (en) 2022-02-11 2022-02-11 Method for operating a motor vehicle, control device, motor vehicle
DE102022201455.3 2022-02-11

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CN116588054A true CN116588054A (en) 2023-08-15

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