JP6124123B2 - Regenerative brake control system - Google Patents

Description

  The present invention relates to a regenerative cooperative brake control system that controls the distribution of regenerative braking force and friction braking force of a vehicle such as an electric vehicle or a hybrid vehicle.

  In general, an electric vehicle that travels by driving an electric motor or a hybrid vehicle equipped with an electric motor for driving a vehicle generates regenerative power by using the motor as a generator, and uses the load related to this power generation as a braking force (regenerative braking). It can be generated. In an electric vehicle, when a driver turns off an accelerator pedal, a braking force equivalent to an engine brake in a vehicle driven by an engine is applied by regenerative braking to improve driving feeling and to generate electric power by regeneration. It is collected to improve the energy efficiency of the vehicle.

  In recent years, not only the braking force equivalent to the engine brake described above is applied by regenerative braking, but also energy is recovered by regenerative power generation by using both friction braking and regenerative braking when the brake pedal is operated. Regenerative cooperative braking systems that improve energy efficiency have been put into practical use. In Patent Document 1, in order to ensure a good brake feeling at the time of regenerative cooperative brake braking, a braking target value calculated using a map is added to a basic hydraulic pressure component and an additional braking component (regenerative component and pressurized component). A brake control device that performs braking control of regenerative cooperation that is achieved as a sum is disclosed.

JP 2012-116425 A

  In the conventional regenerative cooperative brake system, in order to improve the fuel cost or the electric power cost, the clearance between the brake pad and the disc rotor is secured in order to reduce the brake drag torque. Also, during regenerative coordination braking control, energy is recovered to the maximum by prioritizing the operation of the regenerative brake over the friction brake.

  For this reason, when the braking force required by the driver is supplemented by the friction braking force, which is not enough for the regenerative braking force, the brake pad is relied on when there is a clearance between the brake pad and the disc rotor. The brake pads are likely to be accompanied by a braking shock caused by being pressed against the disc rotor during braking, and the deterioration of the brake feeling has been a problem. In particular, when the regenerative braking force decreases at the time of deceleration just before stopping, and the decrease is compensated by a friction brake, a problem that brake shock occurs and brake feeling deteriorates remarkably appears. Patent Document 1 mentions to eliminate the influence of mechanical variation at the time of regenerative cooperative brake control and ensure a good brake feeling, but in the case where the decrease in the regenerative braking force is compensated with a friction brake. There is no mention of braking shock mitigation.

  The present invention has been made in view of the above problems, and provides a new and improved regenerative cooperative brake control system capable of alleviating a braking shock during regenerative cooperative brake control after the start of braking and just before stopping. The purpose is to do.

In order to achieve the above object, the present invention provides a regenerative cooperative brake control system for controlling distribution of a regenerative braking force and a friction braking force of a vehicle, the regenerative braking device for applying the regenerative braking force to a wheel, and the friction A friction braking device that applies braking force to the wheels; a brake input detection unit that detects a brake input by a brake operation of a driver of the vehicle; a target braking force calculation unit that calculates a target braking force from the brake input; A braking force determination unit that determines the distribution of the regenerative braking force and the friction braking force so as to satisfy the target braking force, and a maximum regenerative system that calculates a maximum regenerative braking force determined according to the running state of the vehicle. A power calculation unit, and a braking force determination unit that compares the target braking force and the maximum regenerative braking force .
When the brake input is detected by the brake input detection unit and the target braking force increases, the friction braking force is first increased to a first predetermined amount by the friction braking device, and then the regenerative braking force by the regenerative braking device is increased. On the other hand, even if the braking force determination unit determines that the maximum regenerative braking force is greater than or equal to the target braking force, the friction braking device leaves the friction braking force and maintains a second predetermined amount of friction. While the braking force is continuously applied to the wheel, the regenerative braking device applies the regenerative braking force to the wheel by subtracting the second predetermined amount of friction braking force from the target braking force.

According to the present invention, since the friction brake is applied to the wheel in conjunction with the driver's braking operation at the start of braking, the braking shock due to the application of the friction brake during braking can be eliminated.
In addition, since at least the second predetermined amount of friction braking force is continuously applied from the start of braking to the stop of the vehicle, the braking shock due to the application of the friction brake during braking can be eliminated, and the maximum regenerative braking force can be achieved. By setting the friction braking force that is continuously applied when the braking force is greater than or equal to the braking force to the second predetermined amount, the friction braking force can be reduced and the regenerative braking force can be increased, thereby preventing a reduction in the energy efficiency of the vehicle.

  In the present invention, it is preferable that the first predetermined amount of friction braking force is equal to the second predetermined amount of friction braking force.

  Thus, by making the first predetermined amount equal to the second predetermined amount, the friction braking force that is continuously applied during braking can be reduced and the regenerative braking force can be increased, so that the energy efficiency of the vehicle is reduced. Can be prevented.

  In the present invention, preferably, the regenerative braking device may apply the regenerative braking force to the wheel before the brake input detection unit detects the brake input.

  In this way, since the regenerative braking force can be effectively utilized before the vehicle starts to decelerate, the energy efficiency of the vehicle can be improved.

  In the present invention, it is preferable that the regenerative braking device continues to apply the regenerative braking force to the wheels until the vehicle stops.

  In this way, since the regenerative braking force can be effectively utilized to the maximum extent until the vehicle stops, the energy efficiency of the vehicle can be improved.

  As described above, according to the present invention, it is possible to alleviate a braking shock during regenerative cooperative brake control after the start of braking and just before stopping.

It is a schematic block diagram which shows the regeneration cooperation brake control system which concerns on one Embodiment of this invention. It is a flowchart which shows the operation | movement of the braking control by the regenerative cooperative brake control system which concerns on one Embodiment of this invention. It is operation | movement explanatory drawing of the braking control by the regenerative cooperative brake control system which concerns on one Embodiment of this invention, (a) is a figure which shows the relationship between a vehicle speed and time, (b) is braking force, time, It is a figure which shows the relationship. It is a flowchart which shows the operation | movement of the braking control by the conventional regenerative cooperative brake control system used as a comparative example. It is operation | movement explanatory drawing of the braking control by the conventional regenerative cooperative brake control system used as a comparative example, (a) is a figure which shows the relationship between a vehicle speed and time, (b) is the relationship between braking force and time. FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are essential as means for solving the present invention. Not necessarily.

  First, the configuration of a regenerative cooperative brake control system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a regenerative cooperative brake control system according to an embodiment of the present invention.

  The vehicle 10 including the regenerative cooperative brake control system 100 according to the present embodiment is supplied with electric power from a driving battery 12 as a traveling device of the vehicle 10 and is equipped with motors 18 and 19 controlled by inverters 14 and 16. It is. As shown in FIG. 1, the vehicle 10 of the present embodiment is a four-wheel drive type in which motors 18 and 19 that serve as drive sources for the front wheels 22 (22R and 22L) and the rear wheels 24 (24R and 24L) are provided separately. It is an electric car. Note that the regenerative cooperative brake control system 100 of the present embodiment is applied to a four-wheel drive type electric vehicle, but also includes an automobile that drives only the front wheels or the rear wheels by a motor, and a drive source by the motor. It can also be applied to hybrid vehicles.

  The regenerative cooperative brake control system 100 of the present embodiment controls the distribution of the regenerative braking force and the friction braking force of the vehicle 10. That is, as a braking device of the vehicle 10, a regenerative braking device 20 that applies a regenerative braking force according to the power generation amount of the motors 18 and 19 to the wheels 22 and 24 and brakes with the regenerative force of the motors 18 and 19, and friction And a friction braking device 30 that mechanically brakes the wheels 22 and 24 by applying a friction braking force corresponding to the force to the wheels 22 and 24. The regenerative cooperative brake control system 100 includes a brake pedal 32, a brake switch 33, and a brake pedal stroke sensor 34.

  The regenerative braking device 20 includes a battery 12, inverters 14 and 16, motors 18 and 19, various sensors, and an ECU 102. The regenerative braking device 20 drives the motors 18 and 19 via the transaxles 26 and 28 serving as transmissions from the front wheels 22 and the rear wheels 24 serving as wheels, and uses the motors 18 and 19 as a generator to generate a braking force. Is generated.

  The friction braking device 30 includes disk rotors 40 and 46, brake pads 44 and 49, electric calipers 42 and 48, various sensors, an ECU 102, a parking brake system (not shown), and the like. The friction braking device 30 applies to the wheels 22 and 24 a friction braking force corresponding to the friction force generated between the disc rotors 40 and 46 and the brake pads 44 and 49 via the electric calipers 42 and 48. , Mechanically brake.

  The brake switch 33 detects whether or not the brake pedal 32 is operated, and outputs an ON or OFF electric signal. The brake pedal stroke sensor 34 converts the brake pedal stroke amount, which is the degree of operation of the brake pedal 32 operated by the driver, into an electrical signal and outputs it.

  The driving battery 12 supplies electricity for driving the motors 18 and 19, and stores electricity generated by the motors 18 and 19 during regenerative braking. The inverters 14 and 16 are for controlling the motors 18 and 19 by a control signal from the ECU 102. The motors 18 and 19 are controlled by the inverters 14 and 16 and generate driving force for driving the vehicle 10. Further, at the time of regenerative braking, it is driven from the front wheels 22R, 22L and the rear wheels 24R, 24L via the transaxles 26, 28 and functions as a generator. The transaxles 26 and 28 are disposed between the motors 18 and 19 and the front wheels 22 and the rear wheels 24 to decelerate the driving force from the motors 18 and 19 and transmit them to the front wheels 22R and 22L and the rear wheels 24R and 24L, respectively. To do.

  The ECU 102 is a control device for performing comprehensive control of the vehicle 10 and includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), a timer, and the like. Is done. In the present embodiment, the ECU 102 includes a brake input detection unit 104, a target braking force calculation unit 106, a maximum regenerative braking force calculation unit 108, a braking force determination unit 110, and a braking force determination unit 112, as shown in FIG. .

  The brake input detection unit 104 detects a brake input by the driver. Specifically, when the driver operates the brake pedal 32, the brake input is detected based on the output of an ON or OFF electric signal indicating the presence or absence of the operation of the brake pedal 32 detected by the brake switch 33.

  The target braking force calculation unit 106 calculates a target braking force from the brake input. Specifically, when the driver operates the brake pedal 32, the target braking force requested by the driver is calculated based on the brake pedal stroke amount detected by the brake pedal stroke sensor 34.

  The maximum regenerative braking force calculation unit 108 calculates the maximum amount of regenerative braking force (maximum regenerative braking force) applied to the wheels 22 and 24 by the regenerative braking device 20. The maximum regenerative braking force is determined according to the vehicle speed, the road surface condition, and the like. The braking force determination unit 110 compares the target braking force calculated by the target braking force calculation unit 106 with the maximum regenerative braking force detected by the maximum regenerative braking force calculation unit 108. The braking force determination unit 112 determines the distribution of the regenerative braking force and the friction braking force so as to satisfy the target braking force according to the determination result of the braking force determination unit 110.

  In the regenerative cooperative brake control system 100 of the present embodiment, when the brake input detection unit 104 detects a brake input and the target braking force increases, the friction braking device 30 increases the friction braking force to a first predetermined amount. The regenerative braking force by the regenerative braking device 20 is increased. In other words, in order to eliminate the braking shock caused by applying the friction brake during regenerative cooperative braking, the friction brake is applied in conjunction with the operation of the driver at the start of braking, and the state where the friction brake is applied during braking is maintained. Features.

  Next, the operation of regenerative braking control by the regenerative cooperative brake control system 100 of the present embodiment will be described with reference to the drawings. FIG. 2 is a flowchart showing the operation of the regenerative braking control by the regenerative cooperative brake control system according to the embodiment of the present invention, and FIG. 3 shows the regenerative braking control by the regenerative cooperative brake control system according to the embodiment of the present invention. (A) is a figure which shows the relationship between vehicle speed and time, (b) is a figure which shows the relationship between braking force and time.

  When the regenerative braking control system 100 of the present embodiment performs the regenerative braking control operation, first, it is detected whether or not braking has been started (braking start detection step S10). In the present embodiment, the brake input detection unit 104 detects a brake input.

  Next, when it is detected that braking is started in the braking start detection step S10, the target braking force calculation unit 106 starts calculating the target braking force requested by the driver from the brake input and is provided in the friction braking device 30. The brake pads 44 and 49 are brought into contact with the disk rotors 40 and 46 (friction brake application step S12). In the present embodiment, as shown in FIGS. 3A and 3B, braking by friction brake is started (time t1), and the first place that is smaller than the regenerative braking force P1es applied to the wheels before the braking is started. The friction braking force is applied up to a fixed amount A1 (A1 ≦ P1es, FIG. 3B) (time t4). That is, a slight frictional braking force is applied by slightly bringing the brake pads 44 and 49 into contact with the disc rotors 40 and 46 in conjunction with the operation of the driver at the start of braking.

  Thereafter, the target braking force calculated by the target braking force calculator 106 and the maximum regenerative braking force calculated by the maximum regenerative braking force calculator 108 are compared (braking force determination step S14). When it is determined that the maximum regenerative braking force is greater than the target braking force (FIG. 3B, t5 to t6), the braking force determination unit 112 uses the second predetermined amount A2 of friction braking force as the friction braking force. The regenerative braking force is determined by subtracting the second predetermined amount of friction braking force from the target braking force as the regenerative braking force, and the target braking force is satisfied by the sum of the friction braking force and the regenerative braking force. The distribution between the regenerative braking force and the friction braking force is determined (braking force determination step S16). Then, according to the distribution of the determined regenerative braking force and friction braking force, regenerative braking is performed by applying the regenerative braking force by the regenerative braking device 20 and the friction braking force by the friction braking device 30 to the wheels 22 and 24. .

  On the other hand, when it is determined in the braking force determination step S14 that the maximum regenerative braking force is smaller than the target braking force (FIG. 3 (b), t4 to t5, t6 to t3), the braking force determination unit 112 determines the regenerative braking force. Determine the maximum regenerative braking force, determine the friction braking force as the friction braking force by subtracting the maximum regenerative braking force from the target braking force, and satisfy the target braking force by the sum of the friction braking force and the regenerative braking force. Next, the distribution of the regenerative braking force and the friction braking force is determined (braking force determination step S17).

  Then, after continuing the brake operation, it is determined whether or not to end the brake operation (braking release determination step S18). When releasing the brake, the operation of regenerative cooperative braking is ended, and when braking is continued, Returning to the braking force determination step S14, the steps S14 to S18 are repeated. In the present embodiment, as shown in FIG. 3B, the regenerative braking device 20 continues to apply the regenerative braking force to the wheels 22 and 24 until the vehicle 10 stops (until time t2). Until now, the regenerative braking force is effectively utilized to the maximum to improve the energy efficiency of the vehicle.

  The regenerative cooperative brake control system 100 according to the present embodiment eliminates a braking shock generated by applying a friction brake from the start of braking until the vehicle 10 stops, and allows the regenerative braking force to be used effectively. Control system.

  That is, in this embodiment, when the brake input is detected by the brake input detection unit 104 and the target braking force is increased, the regenerative braking device 20 is increased after the friction braking force is increased to the first predetermined amount A1 by the friction braking device 30. The regenerative braking force by is increased. Specifically, as shown in FIG. 3B, the brake pads 44 and 49 are brought into contact with the disk rotors 40 and 46 to start braking by friction braking (time t1), and then slightly delayed from the start of braking. (Time t4), the braking force is increased in accordance with the distribution of the regenerative braking force and the friction braking force determined by the braking force determination unit 112. By doing so, the friction brake can be applied to the wheels 22 and 24 in conjunction with the driver's brake operation at the start of braking, so that the braking shock caused by the application of the friction brake can be interlocked with the driver's brake operation. The deterioration of the ring can be prevented.

  In the present embodiment, as shown in FIG. 3B, the friction braking device 30 applies a friction braking force of at least the second predetermined amount A2 or more to the wheel between the braking start t1 and the vehicle stop t2. Keep doing. By doing so, the brake pads 44, 49 are always in contact with the disk rotors 40, 46, so that the braking shock generated by pressing the brake pads 44, 49 against the disk rotors 40, 46 during braking is eliminated. be able to. Further, the friction braking force of the second predetermined amount A2 is made equal to the friction braking force of the first predetermined amount A1 that is applied immediately after the brake is detected, thereby reducing the friction braking force applied during braking and the regenerative braking force. Therefore, it is possible to prevent a decrease in energy efficiency of the vehicle 10.

  Conventionally, for example, in a regenerative cooperative brake control system using an electric caliper that drives a piston with a motor, the brake pad and the disc rotor are set to have a clearance to prevent dragging of the brake during acceleration traveling. ing. On the other hand, at the time of deceleration, as shown in FIG. 4, when braking is started (step S22), the target braking force is calculated, and allocation of regenerative brake and friction brake is determined and regenerative cooperative control is performed (step S22). S24).

  At that time, the distribution of the regenerative braking force and the friction braking force is determined by the driver's accelerator pedal and brake pedal position. At this time, when the friction braking force is increased from 0%, the brake pad is applied from the state where there is a clearance between the brake pad and the disc rotor, so that the friction braking force shown in FIG. It is likely to be accompanied by a braking shock at the start point Q1. Similarly, at the time points Q2 and Q3 when the friction brake is turned on or off, a braking shock is likely to occur.

  For this reason, in this embodiment, in order to eliminate the braking shock due to the application of the friction brake, the brake pads 44 and 49 are slightly brought into contact with the disc rotors 40 and 46 in conjunction with the operation of the driver at the start of braking, and the friction is caused. A slight brake is applied. During braking, while maintaining the state where the friction brake is applied, the friction brake is increased or decreased with respect to the shortage of the regeneration amount with reference to the position. In this way, by applying a friction brake to the wheels 22 and 24 in conjunction with the driver's braking operation at the start of braking, the friction brake is applied from the state where the regenerative braking force is 100% and the friction braking force is 0% after the braking is started. The braking shock due to can be eliminated.

  Although one embodiment of the present invention has been described in detail as described above, it is easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. It will be possible. Therefore, all such modifications are included in the scope of the present invention.

  For example, a term described with a different term having a broader meaning or the same meaning at least once in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. Further, the configuration and operation of the regenerative cooperative brake control system are not limited to those described in the embodiments of the present invention, and various modifications can be made.

DESCRIPTION OF SYMBOLS 10 Vehicle 12 Battery 14, 16 Inverter 18, 19 Motor 20 Regenerative braking device 22, 24 Wheel 26, 28 Transaxle 30 Friction braking device 32 Brake pedal 33 Brake switch 34 Brake pedal stroke sensor 36 Brake booster 38 Master cylinder 40, 46 Disc Rotors 42, 48 Electric calipers 44, 49 Brake pads 100 Regenerative cooperative brake control system 102 ECU
104 Brake input detection unit 106 Target braking force calculation unit 108 Regenerative braking force detection unit 110 Braking force determination unit 112 Braking force determination unit

Claims (4)

A regenerative cooperative brake control system that controls the distribution of regenerative braking force and friction braking force of a vehicle,
A regenerative braking device that applies the regenerative braking force to the wheels;
A friction braking device for applying the friction braking force to the wheel;
A brake input detector for detecting a brake input by a brake operation of the driver of the vehicle;
A target braking force calculation unit for calculating a target braking force from the brake input;
A braking force determination unit that determines the distribution of the regenerative braking force and the friction braking force so as to satisfy the target braking force;
A maximum regenerative braking force calculation unit for calculating a maximum regenerative braking force determined according to the traveling state of the vehicle;
A braking force determination unit that compares the target braking force and the maximum regenerative braking force;
With
When the brake input is detected by the brake input detection unit and the target braking force increases, the friction braking force is first increased to a first predetermined amount by the friction braking device, and then the regenerative braking force by the regenerative braking device is increased. while the increase,
Even if the braking force determination unit determines that the maximum regenerative braking force is greater than or equal to the target braking force, the friction braking device leaves the friction braking force and applies a second predetermined amount of friction braking force to the wheel. And the regenerative braking device applies regenerative braking force to the wheels by subtracting the second predetermined amount of friction braking force from the target braking force. Control system. 2. The regenerative cooperative brake control system for a vehicle according to claim 1 , wherein the first predetermined amount of friction braking force is equal to the second predetermined amount of friction braking force. 3. The regenerative braking control system for a vehicle according to claim 1, wherein the regenerative braking device applies the regenerative braking force to the wheel before the brake input detection unit detects the brake input. 4. . The regenerative braking control system for a vehicle according to any one of claims 1 to 3 , wherein the regenerative braking device continues to apply the regenerative braking force to the wheels until the vehicle stops.

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