JP2018521905A - Method and apparatus for driving an automobile brake system, brake system - Google Patents

Abstract

The present invention is a method for driving a brake system (3) of an automobile (1), comprising at least one wheel brake device (9) hydraulically controllable and at least one of the automobile (1) Electric machine (4) that is actuated / connectable to the wheel (6) and that can be actuated, and moves against the return force (F _R ) to preset the target brake torque Possible brake pedals (11), in which case the wheel brake device (9) is controlled to generate a friction brake torque depending on the brake pedal position (x) and / or The electric machine (4) is controlled to generate a regenerative brake torque, whereby both the wheel brake device (9) and the electric machine (4) are at the target brake torque. It relates to a method of generating. The return force (F _R ) can be changed depending on the ratio of the friction brake torque to the target brake torque.
[Selection] Figure 3

Description

  The present invention is a method for operating a braking system of a motor vehicle, comprising at least one wheel brake device that is hydraulically controllable and a power generation operatively connected to / at least one wheel of a motor vehicle. It has an electric machine that can be operated mechanically and a brake pedal that can move against the return force for presetting the target brake torque. In this case, the friction brake depends on the brake pedal position. The invention relates to a method in which a friction brake device is controlled to generate torque and / or an electric machine is controlled to generate regenerative brake torque, whereby both the friction brake device and the electric machine generate a target brake torque.

  The invention also relates to a device for carrying out this method, and to a brake system of this type.

  Today's automobiles are increasingly equipped with drives with electric machines in addition to or instead of conventional internal combustion engines. This type of hybrid drive or electric drive can generate electrical energy by so-called regenerative or regenerative braking. For this purpose, the electric machine is operated in a generator manner, which causes the electric machine to exert a negative torque on the drive train of the vehicle and at the same time generate electric energy. In many driving situations, purely electrical braking by a generator-operated electric machine is not sufficient to produce the desired target brake torque, so that regenerative or regenerative braking is also possible. In addition, it is known to hydraulically operate a conventional wheel brake device that generates friction brake torque on at least one wheel of an automobile. Thereby, depending on the vehicle speed and the target brake torque, a hydraulic friction brake torque that satisfies the target brake torque together with the regenerative brake torque is obtained. In this way, the regenerative brake torque is consumed hydraulically together with the friction brake torque generated hydraulically, so that a desired target brake torque in each driving situation can be changed. In particular, the unstable brake torque characteristics or generator characteristics of the electric machine can be corrected by hydraulic consumption.

  In this case, the regenerative potential during the braking operation also depends on the generator characteristics of the electric machine and other peripheral conditions such as the state of charge of the storage battery and the operating temperature of the electric machine. In this case, the generator characteristics depend on the vehicle speed, and thus guarantee the various regenerative braking torques that can be provided, depending on the actual vehicle speed. Due to hydraulic consumption, this dependence is corrected for the target brake torque and the driver is provided with a clear brake torque independent of the vehicle speed, depending on the brake pedal position.

  The method according to the invention having the features of claim 1 provides tactile feedback as to whether the brake system changes the target brake torque mainly regeneratively or hydraulically when the driver operates the brake pedal. Can be obtained. This allows the driver to adapt his driving method or actual braking operation by moving the brake pedal, for example, so as to maximize the regenerative braking torque in order to improve the vehicle energy balance. it can. For this reason, according to the present invention, the return force can be changed depending on the ratio of the friction brake torque to the target brake torque. That is, the return force acting on the brake pedal, which must be overcome in order for the driver to move the brake pedal, can be changed depending on the ratio of the friction brake torque or the regenerative brake torque. As a result, the driver can feel whether or not the target brake torque requested by the driver controls the wheel brake device when operating the brake pedal. This allows the user to adjust the target brake torque in a simple manner and manner so that a pure regenerative brake torque is obtained if external conditions permit. Therefore, the driver can adapt the driving method so that the target friction brake torque is changed mainly by the regenerative torque, for example. Thus, the driver can intentionally avoid the target brake torque that generates the friction brake torque, that is, the brake torque having a hydraulic part. Unlike the brake system, which visually displays to the driver how the requested target brake torque is changed by the regenerative brake torque and the friction brake torque, the method according to the invention allows the driver to It offers the advantage that, for example, it is not necessary to keep an eye on the running process in order to adapt the operation.

  According to a preferred embodiment of the present invention, when the ratio of the friction brake torque exceeds a preset first limit value, the return force is increased. Thus, when the driver feels an increased counter pressure or an increased return force when operating the brake pedal, the preset friction brake torque exceeds the first limit value, in which case the target Sensing that the brake torque is at least partially altered by the friction brake torque. On the other hand, when the driver feels a reduced or slightly increased counter pressure, the driver's target brake torque is braked particularly regeneratively, with the friction brake torque being below the first limit value. It senses that it is in the area to be played. The first limit value is selected in such a way that it is braked mainly hydraulically when the first limit value is exceeded, so that the target brake torque is derived from the dominant proportion of the friction brake torque. Is done.

  According to a preferred embodiment of the present invention, the return force is reduced when the ratio of the friction brake torque falls below a second limit value that can be set in advance. That is, for example, when the actually adjusted percentage of friction brake torque is reduced, the return force is reduced, especially slightly increased, and the user can defeat the brake pedal against the return force to change the target brake torque. It can be moved slightly. This is because, for example, the possible regenerative braking torque of the electric machine provided on the basis of the generator characteristics of the electric machine, as the vehicle speed increases, only the target braking torque or almost the target braking torque, ie hydraulic consumption. It is a case where it gradually increases until it can be changed to none.

  Preferably, the first limit value is greater than or equal to the second limit value. This provides hysteresis control of the return force that avoids an unexpected or unstable switch between increased and reduced return force.

  According to a preferred embodiment of the present invention, the return force increases against the return force as the brake pedal movement increases gradually. This reduces the return force when the brake pedal moves against the return force, causing the driver to further move the brake pedal based on the return force that was unexpectedly omitted, thereby increasing the target higher than intended. Setting the brake torque in advance is avoided. This ensures that the return force is reduced only on the basis of the conventional course of the return force, depending on the proportion of the friction brake torque, and that an unlimited reduction of the return force is not performed. In other words, depending on the ratio of the friction brake torque, the return force increases when the brake pedal is moved against the return force, and thus the return force is reduced with respect to the conventional return force. In particular, the return force of the brake pedal increases continuously, and the gradient of the return force increase is reduced only in the region where the friction brake torque is below the first and / or second limit value.

  In a preferred form, the friction brake torque is adjusted depending on the generator characteristic curve of the electric machine, so that the target brake torque is preferably the target to obtain a suitable energy balance for a vehicle having a brake system. It is changed so that the largest possible proportion of the brake torque can be changed by the regenerative brake torque.

  Particularly preferably, a brake booster, in particular an electromechanical brake booster, is controlled in order to change the return force. This gives the driver a tactile feedback on the ratio of the friction brake torque to the target brake torque or the ratio of the regenerative brake torque, the return force of the brake system or brake pedal as described above in a simple form and Can be changed in a way.

  The device according to the invention with the features of claim 8 features a dedicated control unit for carrying out the method. Other advantages and preferred features are set forth in the foregoing description and in the claims.

  The brake system according to the invention having the features of claim 9 features a device according to the invention and a unit for changing the return force of the brake pedal. In this case, the unit is connected to the device according to the invention, so that the device changes the return force by controlling the unit according to the method of the invention.

  Particularly preferably, the unit for changing the return force is a brake booster, in particular an electromechanical brake booster. Hydraulic brake systems are usually equipped with a brake booster, so that no additional structure is required to change the return force that must be built into the hydraulic brake system. This provides cost and mounting space advantages.

1 is a schematic plan view of an automobile having a suitable brake system. It is a figure which shows the braking behavior of a brake system. It is a figure which shows the return force of the brake pedal of a brake system.

  The present invention will be described in detail below with reference to the drawings.

  FIG. 1 shows a schematic view of a motor vehicle 1 having a drive device 2 and a brake system 3.

  The drive device 2 has an electric machine 4 as a drive machine, and the electric machine 4 is selectively connected to the drive wheels 6 of the automobile 1 by a transmission device 5. The electric machine 4 is operated as a motor type and a generator type, and can be connected to or connected to an energy accumulator 7 for this purpose, and energy for driving is taken out from the energy accumulator 7 or generated during regenerative operation. Energy is supplied to the energy accumulator 7.

  As will be explained in detail below, the electric machine 4 is also a component of the brake system 3 at the same time. The brake system 3 has a hydraulic brake device 8, and this hydraulic brake device 8 is used for hydraulically operating the wheel brake device 9 disposed corresponding to each one wheel of the automobile 1. A plurality of wheel brake devices 9 are connected to adjust a friction brake torque for decelerating the automobile 1. Furthermore, the brake system 3 has a device 10, which is configured as a control unit, and controls the hydraulic brake device 8 and the electric machine 4 depending on the target brake torque.

  The brake system 3 includes a brake pedal 11 that can be operated by the driver of the automobile 1 in order to preset a target brake torque. For this purpose, the brake pedal 11 can be moved by the driver against the return force, as indicated by the arrow. Moreover, in this case, the brake pedal 11 is connected to the hydraulic brake device 8, in particular the device 12 of the hydraulic brake device 8, in particular the brake booster. Is shown correspondingly to the brake pedal 11 and is configured or suitable for changing the return force acting on the brake pedal 11.

  Depending on the target brake torque preset by the brake pedal position, the device 10 changes the target brake torque by the friction brake torque of the wheel brake device 9 and by the regenerative brake torque of the electric machine 4. 4 and the hydraulic brake device 8 are controlled.

  For this purpose, FIG. 2 shows the generator characteristics of the electric machine 4 in a graph relating to the speed v of the vehicle 1. In this case, the generator characteristic is indicated by a characteristic curve 13, which represents the regenerative braking torque that can be provided by the electric machine 4 depending on the vehicle speed. Typically, the characteristic curve 13 has its maximum value in the region of lower velocities v1 to v2. Similarly, in FIG. 2, for example, a target brake torque adjusted by the driver by operating the brake pedal 11 is shown by a characteristic curve 14. In the illustrated embodiment, the target brake torque is below the maximum possible regenerative brake torque, but above the maximum available regenerative brake torque at lower and higher vehicle speeds v. Accordingly, in region I where the regenerative brake torque 13 that can be provided is insufficient to change the target brake torque, the device 10 applies the corresponding friction brake torque by means of one or more wheel brake devices 9 to the target brake torque. In order to adjust the torque to change, the hydraulic brake device 8 is additionally controlled. Within the region II where the target brake torque can only be provided by the electric machine 4, the proportion of the friction brake torque is preferably reduced as much as possible, in particular set to zero, so that the regenerative capacity of the electric machine 4 is braked. Sometimes used at maximum.

In FIG. 3, the return force F _R exerted on the pedal 11, depending on the brake pedal movement or position x is shown graphically. In this case, the dashed line 15 shows the conventional change in the return force depending on the pedal stroke x. In this case, the normal return force continuously increases as the amount of movement of the brake pedal 11 against the return force increases. In particular, straight stroke and force lines are obtained.

The device 10 carries out a preferred method, in which the return force acting on the brake pedal 11 varies under the influence of the brake booster 12. For this purpose, the device 10 first calculates the ratio of the friction brake torque to the target brake torque. In the illustrated embodiment, the proportion of friction brake torque is compared with a first limit value equal to zero. That is, as soon as the friction brake torque is required for changing the target brake torque, the first limit value is exceeded. This is because, in FIG. 2, in the case of the traveling speed v ₀ and up speed v _3, i.e., the target braking torque is the case in the region I and is subject to change at least in part by the friction braking torque. Falls below a first limit value the ratio of the friction brake torque is set in advance or, v as in ₀ to v ₃ in the region below the second presettable limit value below the first limit value When the device 10 controls the brake booster 12, as indicated by the characteristic curve 16 in FIG. 3, as the return force F _R is lowered with respect to the characteristic curve 15, the return force F _R Change. In this case, is dependent on the actual driving speed v regulation region of the brake pedal position x, the return force F _R in the region of the brake pedal position x is reduced relative to the normal of the return force. outside the region between x ₁ and x _2, that is, when the ratio of the friction braking torque is greater than zero, return force according to the characteristic curve 15 is returned to either or initial value is increased.

Thus, the driver feels that the brake system 3 changes the target brake torque depending on the target brake torque preset by the driver. In region x ₁ to x _2, the driver feels a counter pressure or feel less counterpressure, or does not increase almost when moving against the return force F _R of the brake pedal 11. In any case, the driver feels a reduced counter pressure compared to the normal change according to the characteristic curve 15. Only when the driver increases the target brake torque and the hydraulic brake device 8 is additionally controlled to the extent that the target brake torque can no longer be changed by the electric machine 4 alone, the opposing pressure is increased, and the driver Feels as if the hydraulic brake device 8 was additionally switched on to change the brake torque requested by the driver.

In order to influence the return force F _R, the brake booster 12 it is first is configured as a brake booster of electromechanical, of the electromechanical brake booster, the effect on the restoring force F _R The exerting characteristic can be corrected by corresponding control or influence. This means that within the tolerance range of the vehicle subjectively defined for the driver, for example, the distance to the vehicle present in it or the speed change of the preceding vehicle, or the speed change until stopping The possibility of giving the situation to the driver is obtained. The tactile feedback at the brake pedal 11 allows an intuitive change of the adaptation of the braking behavior in relation to the braking effect, in particular in relation to the use of the regenerative potential of the electric machine 4.

  Further optionally, the device 10 may be used to provide other information to more accurately indicate basic conditions, such as actual position data of a satellite-protected navigation system, such as inter-vehicle sensors, radar sensors, video sensors, lidar sensors, etc. Peripheral sensor data or vehicle-to-vehicle communication data can also be calculated.

  Overall, this method provides the driver with the advantage of intuitively allowing the vehicle energy balance to be optimized or fuel consumption reduced by tactile feedback to the driver.

1 automobile third brake system 4 electromechanical 6 wheel 8 brake device 9 wheel braking device 10 device 11 the brake pedal 12 units, the speed of the brake booster F _R restoring force v automobile 1, a vehicle speed x brake pedal

Claims (10)

A method for driving a brake system (3) of a motor vehicle (1), comprising at least one wheel brake device (9) hydraulically controllable and at least one wheel (6) of said motor vehicle (1) An electric machine (4) that can be operated and connected to the generator and that can be actuated, and a brake pedal that can be moved against a return force (F _R ) for presetting a target brake torque In this case, the wheel brake device (9) is controlled to generate the friction brake torque depending on the brake pedal position (x) and / or the regenerative brake torque is generated. For this purpose, the electric machine (4) is controlled so that both the wheel brake device (9) and the electric machine (4) generate the target brake torque. In,
A method for operating a brake system (3) of an automobile (1), characterized in that the return force (F _R ) is varied depending on the ratio of the friction brake torque to the target brake torque. The method according to claim 1, characterized in that the return force (F _R ) is increased when the proportion of the friction brake torque exceeds a preset first limit value. The method according to claim 1 or 2, characterized in that the return force (F _R ) is reduced when the proportion of the friction brake torque falls below a preset second limit value.   4. A method according to any one of claims 1 to 3, characterized in that the first limit value is greater than or equal to the second limit value. 5. The method according to claim 1, wherein the return force (F _R ) is increased as the movement of the brake pedal (11) increases gradually. 6.   6. The method according to claim 1, wherein the friction brake torque is adjusted depending on a generator characteristic curve of the electric machine (4). 7. A method according to any one of the preceding claims, characterized in that the brake booster (12) of the brake system (8) is controlled to change the return force (F _R ). A device (10) for driving a brake system (8) of a motor vehicle (1), wherein it is hydraulically controllable at least one wheel brake device (9) and at least one wheel of said motor vehicle (1) Electric machine (4) that can be actuated / connected to (6) and that can be actuated as a generator, and movable against the return force (F _R ) for presetting the target brake torque A brake pedal (11), in which case the wheel brake device (9) is controlled to generate a friction brake torque depending on the detected brake pedal position (x), and / or Alternatively, the electric machine (4) is controlled to generate a regenerative brake torque, whereby both the wheel brake device (9) and the electric machine (4) are in the target brake. In of the type generating a torque,
A braking system (8) for a motor vehicle (1), characterized in that it is provided with a dedicated control unit for carrying out the method according to any one of claims 1 to 7 when used as specified. ) For driving (10). Brake system (8) for a motor vehicle (1) operatively connected to at least one wheel brake device (9) hydraulically controllable and at least one wheel (6) of said motor vehicle (1) A generator-operable electric machine (4) that can be connected to and actuated, and a brake pedal (11) that can move against a return force (F _R ) for presetting a target brake torque, In this case, the brake device (8) is controlled to generate the friction brake torque and / or to generate the regenerative brake torque depending on the detected brake pedal position (x). In a brake system in which the electric machine (4) is controlled, whereby both the brake device (8) and the electric machine (4) generate the target brake torque. ,
Brake for motor vehicle (1), characterized in that it is provided with a device (10) according to claim 8 connected to a unit (12) for changing the return force of the brake pedal (11) System (8).   10. Brake system according to claim 9, characterized in that the unit (12) for changing the return force is in particular an electromechanical brake booster.

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