JP5817329B2 - Vehicle control method and control device - Google Patents

Description

  The present invention includes a regenerative braking device that applies regenerative braking to some of the wheels of the vehicle during vehicle braking, and a hydraulic braking device that applies hydraulic braking to all the wheels during vehicle braking. The present invention belongs to a technical field related to a vehicle control method and a control device.

  In recent years, in an electric vehicle or the like, as a vehicle brake device, a regenerative braking device that applies regenerative braking to a wheel by converting running energy of the vehicle into electricity by a motor, and a brake pad or brake brake by hydraulic pressure There has been known one provided with a hydraulic braking device that applies hydraulic braking to a wheel by being pressed against a disk. The hydraulic braking device converts running energy into heat, whereas the regenerative braking device converts running energy into electricity. Since this electricity can be stored and used for driving the vehicle, the vehicle equipped with the regenerative braking device and the hydraulic braking device as described above has a regenerative braking device that regenerates from the viewpoint of improving fuel efficiency. It is required to use braking as much as possible.

  On the other hand, during vehicle braking, when the slip ratio of the vehicle wheel exceeds a reference value, it is determined that slip has occurred in the wheel, and antilock brake operation by the hydraulic brake device is performed by antilock brake control. It is known to perform this, thereby eliminating wheel slip. When a vehicle equipped with a regenerative braking device and a hydraulic braking device is braked, if the regenerative braking force by the regenerative braking device is large when a slip occurs on a wheel, the controllability of the antilock brake control decreases. End up. Therefore, in Patent Document 1, in order to avoid this, when a slip occurs on a wheel, the regenerative braking force by the regenerative braking device is decreased and the hydraulic braking force by the hydraulic braking device is increased.

JP 2000-62590 A

  However, as described in Patent Document 1, when a slip occurs on a wheel, simply reducing the regenerative braking force and increasing the hydraulic braking force causes the following problems. That is, the regenerative braking force can be quickly reduced by switching control of the inverter or the like, while increasing the hydraulic braking force takes time. For this reason, if the regenerative braking force reduction rate is too high, there is a problem that a so-called G missing feeling occurs in which the vehicle deceleration decreases rapidly. On the other hand, when the decrease speed of the regenerative braking force is slowed, the occurrence of G loss is suppressed, but the regenerative braking force does not decrease immediately, so it becomes difficult to eliminate wheel slip early.

  The present invention has been made in view of such points, and an object of the present invention is to generate slip on a wheel to which regenerative braking is applied in a vehicle including a regenerative braking device and a hydraulic braking device. This is intended to eliminate wheel slip as early as possible while suppressing the occurrence of a feeling of missing G.

In order to achieve the above object, according to the present invention, a regenerative braking device that applies regenerative braking to some of all wheels of a vehicle during vehicle braking, and hydraulic braking to all the wheels during vehicle braking. For a vehicle control method including a hydraulic braking device to be applied, at the time of regenerative braking by the regenerative braking device, the slip ratio of at least one wheel to which the regenerative braking is applied is equal to or greater than a first predetermined value. A step of reducing the regenerative braking force by the regenerative braking device to all wheels to which the regenerative braking is applied at a first speed and increasing the hydraulic braking force by the hydraulic braking device; and the hydraulic braking force After the increase of the engine, the step of executing an anti-lock braking operation by the hydraulic braking device for the wheel having a slip ratio equal to or higher than the first predetermined value; and the regeneration At the time when the regenerative braking force by the braking system is reduced by the first speed, the slip rate of the wheel slip ratio becomes the first predetermined value or more, the first time since become the first predetermined value or more, Changing the reduction speed of the regenerative braking force to a second speed lower than the first speed when a second predetermined value set to a value lower than the first predetermined value is reached. It shall be.

As a result, the slip ratio of the wheel to which the regenerative braking is applied is the first predetermined value (the value for executing the antilock braking operation by the hydraulic braking device on the wheel to which the regenerative braking is not applied or a value close thereto). When this is the case, the regenerative braking force for all the wheels to which regenerative braking is applied decreases at the first speed and the hydraulic braking force increases. By making the first speed as fast as possible, the regenerative braking force is quickly reduced, thereby recovering the wheel speed of the wheel whose slip ratio has exceeded the first predetermined value (decrease in the slip ratio). Can be planned. Here, if the regenerative braking force continues to decrease at the first speed as it is, a feeling of slipping out of the G will occur, but the slip ratio of the wheel with the slip ratio exceeding the first predetermined value will be Only after the first predetermined value or more is reached, when the condition that the second predetermined value set to a value lower than the first predetermined value is reached is satisfied, the regenerative braking force decreasing speed is set to the first By changing to the second speed lower than the speed, it is possible to suppress the occurrence of the feeling of missing G. Further, after the increase of the hydraulic braking force, the anti-lock brake operation is executed when the hydraulic braking force becomes large enough to obtain the effect of executing the anti-lock brake operation, thereby further recovering the wheel speed. be able to. That is, when the above condition is satisfied, the slip ratio of the slipped wheel reaches the second predetermined value and becomes relatively small, and at this point, the hydraulic braking force is effective in executing the antilock brake operation. At this time, the reduction speed of the regenerative braking force is changed to the second speed lower than the first speed, so that the wheel speed of the slipped wheel is surely secured by the antilock brake operation. It is possible to effectively suppress the occurrence of a feeling of loss of G while recovering to. Thus, while suppressing the occurrence of G omission sense, it is possible to eliminate the wheel slip early.

  In the vehicle control method, the step of detecting or estimating the temperature of the hydraulic fluid of the hydraulic brake device, and the lower the first or second speed, the lower the detected or estimated hydraulic fluid temperature. It is preferable that the method further includes a step of setting to.

  That is, when the temperature of the hydraulic fluid of the hydraulic brake device is low, the viscosity of the hydraulic fluid is high and the hydraulic oil pressure increase rate (that is, the hydraulic brake force increase rate) tends to be slow, and the hydraulic brake force increases. When the speed of the regenerative braking force is decreased too much when the speed is low, it may not be possible to sufficiently suppress the occurrence of the feeling of missing G. However, the lower the temperature of the hydraulic oil, the more the first speed. In addition, by setting the second speed to a low speed, it is possible to always achieve both suppression of the feeling of missing G and early elimination of wheel slip regardless of the temperature of the hydraulic oil.

Another aspect of the present invention relates to a regenerative braking device that applies regenerative braking to some of all wheels of a vehicle during vehicle braking, and hydraulic braking that applies hydraulic braking to all the wheels during vehicle braking. In this invention, at the time of regenerative braking by the regenerative braking device, the slip ratio of at least one wheel to which the regenerative braking is applied is equal to or greater than a first predetermined value. The regenerative braking force control means for reducing the regenerative braking force by the regenerative braking device at a first speed for all wheels to which the regenerative braking is applied, and the regenerative braking is performed during the regenerative braking by the regenerative braking device. When the slip ratio of the applied at least one wheel becomes equal to or higher than the first predetermined value, the hydraulic braking force by the hydraulic braking device is applied to all the wheels to which the regenerative braking is applied. And a hydraulic braking force control means for executing an anti-lock braking operation by the hydraulic braking device on the wheel having a slip ratio equal to or higher than the first predetermined value after the hydraulic braking force is increased. The regenerative braking force control means has a slip ratio of the wheel at which the slip ratio is equal to or higher than the first predetermined value when the regenerative braking force by the regenerative braking device is decreased at the first speed . When the second predetermined value set to a value lower than the first predetermined value is reached for the first time after becoming equal to or higher than the first predetermined value , the rate of decrease in the regenerative braking force is lower than the first speed. It is assumed that the speed is changed to the second speed.

  With this configuration, as in the case of the above-described vehicle control method, it is possible to eliminate wheel slip early while suppressing the occurrence of a feeling of missing G.

As described above, according to the vehicle control method and the control device of the present invention, when the slip ratio of at least one wheel to which regenerative braking is applied becomes equal to or higher than the first predetermined value, the regenerative braking is applied. The regenerative braking force by the regenerative braking device for all the wheels is decreased at the first speed and the hydraulic braking force by the hydraulic braking device is increased. After the hydraulic braking force is increased, the slip ratio is greater than or equal to the first predetermined value. When the anti-lock braking operation by the hydraulic braking device is performed on the wheels that have become the above and the regenerative braking force by the regenerative braking device is reduced at the first speed, the slip ratio is the first predetermined value. sometimes the wheel slip ratio became higher value, the first time since become the first predetermined value or more, reaches a second predetermined value which is set to a value lower than the first predetermined value, The rate of decrease of the serial regenerative braking force, by which is adapted to change to a lower second speed than the first speed, while suppressing the occurrence of G omission feeling, it is possible to eliminate the wheel slip early.

It is a figure showing the schematic structure of the whole vehicle carrying the control device concerning the embodiment of the present invention. It is a flowchart which shows the braking control with respect to the front wheel at the time of vehicle braking by a vehicle controller. 5 is a time chart showing changes in vehicle speed and regenerative braking force and hydraulic braking force with respect to the front wheels during vehicle braking.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration of an entire vehicle (in this embodiment, an electric vehicle) on which a control device 1 according to an embodiment of the present invention is mounted. In the present embodiment, the control device 1 includes a vehicle controller 2, an inverter controller 3 that controls the operation of an inverter 12 that will be described later, a battery controller 4 that controls charging and discharging of a battery 13 that will be described later, and a brake unit 31 that will be described later. And a brake controller 5 for controlling the operation. The vehicle controller 2 is a controller that controls the inverter controller 3, the battery controller 4, and the brake controller 5. The vehicle controller 2 can communicate with the three controllers 3 to 5 and transmits and receives various types of information. The control device 1 does not need to be configured by the four controllers 2 to 5 as described above, and can be configured by one or more and three or less controllers.

  Each of the controllers 2 to 5 is based on a well-known microcomputer, and includes a central calculation processing unit (CPU) that executes a program, and a memory that stores a program and data, for example, constituted by a RAM or a ROM. And an input / output (I / O) bus for inputting and outputting various signals.

  A drive motor 11 for driving the vehicle is disposed at the front of the vehicle. The drive motor 11 is a three-phase AC motor, and the U-phase, V-phase, and W-phase coils are wound around the stator of the drive motor 11. The drive motor 11 (each coil) is connected to a direct current battery 13 via an inverter 12. The inverter 12 has a switching element such as an IGBT (Insulated Gate BipolarTransistor), and the inverter controller 3 sets the ON / OFF timing of the switching element so that a current is supplied to each coil at an appropriate timing. Control. At this time, the battery controller 4 controls ON / OFF of a switch of a charging / discharging circuit (not shown) so that a current is supplied from the battery 13 to the inverter 12. Thus, the inverter 12 inputs DC power from the battery 13, converts the DC power to AC power, and then supplies the AC power to the drive motor 11.

  The motor shaft 11 a of the drive motor 11 is connected to left and right front wheels 22 via a reduction gear 16 including a differential gear and left and right drive shafts 17. The front wheels 22 are driven by the drive motor 11. It is a ring. On the other hand, the left and right rear wheels 23 are non-driven wheels (driven wheels). In the present embodiment, when the front wheel 22 and the rear wheel 23 are not distinguished, they are simply referred to as wheels 21. It should be noted that the left and right rear wheels 23 can be auxiliary drive wheels that are driven by the drive motor 11 when necessary according to the traveling state of the vehicle. Alternatively, the left and right front wheels 22 may be non-drive wheels or auxiliary drive wheels, and the left and right rear wheels 23 may be drive wheels.

  The drive motor 11 generates a drive torque corresponding to the electric power supplied from the battery 13 via the inverter 12, drives the left and right front wheels 22 (drive wheels), and causes the vehicle to travel. On the other hand, when the vehicle is braked (when the brake pedal 32 is depressed by the driver of the vehicle), the drive motor 11 can generate electric power by the driving force from the left and right front wheels 22. During this vehicle braking, the inverter controller 3 controls the ON / OFF timing of the switching element so that the drive motor 11 generates power with a power generation amount that can obtain a regenerative braking force determined by the vehicle controller 2 as will be described later. . At this time, the battery controller 4 controls ON / OFF of the switches of the charge / discharge circuit so that the battery 13 is charged with the generated power (regenerative power).

  When the drive motor 11 generates regenerative power, the left and right front wheels 22 are simultaneously given regenerative braking (regenerative braking force) for braking the rotation. The regenerative braking force applied to the left and right front wheels 22 has the same value. The regenerative power is charged to the battery 13 as described above, and the regenerative braking force increases as the amount of charge increases. Therefore, the drive motor 11, the inverter 12, and the battery 13 provide a regenerative braking device that applies regenerative braking to some of the wheels 21 (in this embodiment, the left and right front wheels 22) of all the wheels 21 of the vehicle during vehicle braking. 10 is constituted. The wheel 21 to which regenerative braking is applied is a driving wheel when either one of the front wheel 22 and the rear wheel 23 is a driving wheel and the other is a non-driving wheel. When one of the rear wheels 23 is a drive wheel and the other is an auxiliary drive wheel, one of the drive wheels and the auxiliary drive wheels (that is, the front wheels 22 and the rear wheels 23). Regenerative braking is applied to either one of them.

  Here, the amount of charge of the battery 13 is limited, and the upper limit value of the amount of charge is determined by the state of charge (SOC) of the battery 13, the temperature, and the like. Therefore, the upper limit value of the regenerative braking force is determined by the state of charge (SOC) of the battery 13, the temperature, and the like. The regenerative braking force can be freely changed between 0 and the upper limit value by controlling the ON / OFF timing of the switching element, and the increasing speed and decreasing speed of the regenerative braking force are also 0. And can be changed freely between fairly fast speeds.

  The battery controller 4 receives detection information from a battery voltage sensor (not shown) for detecting the voltage of the battery 13 and a battery current sensor (not shown) for detecting a current value flowing into and out of the battery 13. The battery controller 4 calculates the remaining capacity (SOC) of the battery 13 based on the input information, and transmits the calculation result to the vehicle controller 2. Further, detection information by a battery temperature detection sensor (not shown) that detects the temperature of the battery 13 is input to the battery controller 4, and the battery controller 4 transmits the input information (battery temperature) to the vehicle controller 2. To do.

  In addition to the regenerative braking device 10, the vehicle includes a hydraulic braking device 30 that applies hydraulic braking to all the wheels 21 of the vehicle during vehicle braking. The hydraulic brake device 30 includes a brake unit 31 that includes a pump and a valve and adjusts the hydraulic pressure supplied to each wheel (hydraulic brake 34). The brake unit 31 is supplied with hydraulic pressure from a booster 33 connected to a brake pedal 32. Each wheel 21 is provided with a hydraulic brake 34 that is operated by the hydraulic pressure supplied from the brake unit 31, and each wheel 21 is hydraulically braked by the operation of the hydraulic brake 34.

  Each wheel 21 is provided with a wheel speed sensor 41 that detects the wheel speed of the wheel 21, and information detected by each wheel speed sensor 41 is input to the brake controller 5.

  The brake controller 5 controls the operation of the pump and valve of the brake unit 31 to control the hydraulic pressure (that is, the hydraulic braking force) supplied to each wheel 21. Further, the brake controller 5 calculates the slip ratio of each wheel 21 from the detection information by each wheel speed sensor 41 and transmits information on the slip ratio to the vehicle controller 2. The vehicle controller 2 instructs the brake controller 5 when the received slip ratio is equal to or higher than a preset reference value, and performs anti-lock brake control to cause the wheel 21 (the slip ratio to be higher than the reference value). The anti-lock brake operation (hereinafter referred to as ABS operation) by the hydraulic braking device 30 is executed on the wheel 21), so that the slip of the wheel 21 is eliminated. For example, the slip rate of each wheel 21 is obtained by obtaining the estimated vehicle speed of the vehicle based on the detection signal of the wheel speed sensor 41 of each wheel 21 and then calculating the actual speed of the wheel 21 from the converted wheel speed of the estimated vehicle speed. The value obtained by subtracting the wheel speed is divided by the wheel speed converted value of the estimated vehicle speed. Then, when the slip rate of the wheel 21 becomes equal to or higher than the reference value, the vehicle controller 2 determines that slip has occurred in the wheel 21 and instructs the brake controller 5 to execute antilock brake control. Output. Thereby, the brake controller 5 executes the ABS operation by the pressure braking device 30 of the wheel 21. That is, the brake controller 5 changes the oil pressure to the hydraulic brake 34 of the wheel 21 by repeating the pressure reduction mode, the holding mode, and the pressure increase mode (initially the pressure reduction mode), and the slip rate of the wheel 21 is changed. Decrease. The brake controller 5 itself determines that a slip has occurred in the wheel 21 when the slip rate of the wheel 21 exceeds the reference value, and performs an ABS operation on the wheel 21. May be. Here, the wheels 21 on which the ABS operation is executed when the slip ratio becomes equal to or higher than the reference value as described above are the rear wheels 23 and the front wheels 22 when the regenerative braking is not applied. When there is no braking request (the amount of depression of a brake pedal 32 by a stroke sensor 43 described later becomes zero), the ABS operation is stopped.

  The brake pedal 32 is provided with a stroke sensor 43 for detecting the amount of depression of the brake pedal 32 by the driver of the vehicle, that is, a required braking force requested by the driver. Information detected by the stroke sensor 43 is detected by the vehicle controller. 2 is input.

  When the detection information (required braking force) by the stroke sensor 43 is input, the vehicle controller 2 determines the necessary braking force of each wheel 21 in order to perform braking with the requested braking force. For the front wheels 22, the regenerative braking force by the regenerative braking device 10 and the hydraulic braking force by the hydraulic braking device 30 are determined so that the sum of the regenerative braking force and the hydraulic braking force becomes the necessary braking force. . The regenerative braking force and the hydraulic braking force are determined so that the regenerative braking force is as large as possible. That is, the vehicle controller 2 receives information on the SOC and temperature of the battery 13 transmitted from the battery controller 4, and obtains an upper limit value of the charge amount (that is, an upper limit value of the regenerative braking force) based on the information. . When the required braking force for the front wheel 22 is less than or equal to the upper limit value of the regenerative braking force, regenerative braking is performed on the front wheel 22 with a regenerative braking force that matches the required braking force. On the other hand, when the necessary braking force for the front wheel 22 exceeds the upper limit value of the regenerative braking force, the front wheel 22 is regeneratively braked with the upper limit value of the regenerative braking force, and the regenerative braking is performed from the necessary braking force. Hydraulic braking is performed with a hydraulic braking force that is a value obtained by subtracting the upper limit value of power. The rear wheel 23 is hydraulically braked with a hydraulic braking force that matches the required braking force.

  The vehicle controller 2 instructs the inverter controller 3, the battery controller 4, and the brake controller 5 to brake each wheel 21 with the braking force determined as described above. The charge / discharge circuit and the brake unit 31 are operated.

  Further, when the regenerative braking is performed by the regenerative braking device 10, the vehicle controller 2 has a slip ratio of at least one wheel 21 (in this embodiment, the front wheel 22) to which the regenerative braking is applied becomes equal to or greater than a first predetermined value. The inverter controller 3 and the brake controller 5 are commanded, and the regenerative braking force by the regenerative braking device 10 for all the wheels 21 to which the regenerative braking is applied (in this embodiment, the left and right front wheels 22) is the first speed. And the hydraulic braking force by the hydraulic braking device 30 is increased. The first predetermined value is the same as or close to a value (that is, the reference value) for executing the ABS operation by the hydraulic braking device 30 on the wheel 21 to which regenerative braking is not applied, It is a value that can be determined that slip has occurred. Further, the first speed is as fast as possible, and the regenerative braking force is quickly reduced to quickly recover the wheel speed of the wheel 21 (front wheel 22) whose slip ratio is equal to or higher than the first predetermined value. It is the speed that can be made. Even if the hydraulic braking force is increased as described above, the regenerative braking force is quickly reduced, so that the slip ratio of the front wheel 22 where the slip has occurred can be reduced. The increasing speed of the hydraulic braking force is preferably as fast as possible. However, at present, the increasing speed of the hydraulic braking force is considerably smaller than the first speed.

  In addition, the vehicle controller 2 increases the hydraulic braking force after the increase of the hydraulic braking force when the slip ratio of the front wheels 22 is equal to or higher than the first predetermined value during the regenerative braking by the regenerative braking device 10 as described above. When the ABS is increased to such an extent that the effect of executing the ABS operation can be obtained (in this embodiment, when a predetermined condition described later is satisfied), the brake controller 5 is instructed so that the slip ratio becomes equal to or higher than the first predetermined value. The ABS operation by the hydraulic braking device 30 is executed on the wheel 21 (the front wheel 22 where the slip has occurred). At this time, the maximum hydraulic braking force in the repeated pressure-increasing mode is increased in the subsequent pressure-increasing mode and is increased to the necessary braking force. Regardless of the predetermined conditions described later, when the hydraulic braking force is increased, the slip occurs when the hydraulic braking force becomes equal to or higher than a preset value (a value that can reduce the slip rate by the ABS operation). You may make it perform ABS operation | movement with respect to the wheel 21 in which the rate became more than the said 1st predetermined value.

  Here, if the regenerative braking force for the left and right front wheels 22 continues to decrease at the first speed as it is, the deceleration rapidly decreases and a feeling of missing G occurs. This is because it takes time to increase the hydraulic braking force, and thus the regenerative braking force quickly decreases before the hydraulic braking force increases sufficiently.

  Therefore, in the present embodiment, when the regenerative braking force by the regenerative braking device 10 is decreasing at the first speed and the predetermined condition is satisfied, the vehicle controller 2 instructs the inverter controller 3 to perform the regenerative braking. The decreasing speed of the braking force is changed to a second speed lower than the first speed. This second speed is a speed capable of suppressing the occurrence of the feeling of missing G.

As the predetermined condition, in the present embodiment, the slip ratio of the wheel 21 (the front wheel 22 in which the slip has occurred) whose slip rate is equal to or higher than the first predetermined value is the first time after the slip rate is equal to or higher than the first predetermined value. The condition is that the second predetermined value set to a value lower than the first predetermined value has been reached. That is, when this condition is satisfied, the slip ratio of the slipped front wheel 22 reaches the second predetermined value and becomes relatively small, and at this time, the hydraulic braking force has the effect of executing the ABS operation. At this time, by changing the reduction speed of the regenerative braking force from the first speed to the second speed, the wheel speed of the slipped front wheel 22 is reliably recovered by the ABS operation. while, it is possible to effectively suppress the occurrence of G omission feeling.

  The first and second predetermined values are stored in advance in a memory of at least one of the vehicle controller 2 and the brake controller 5.

  The first and second speeds are stored in advance in the memory of at least one of the vehicle controller 2 and the inverter controller 5. Each of the first and second speeds may be fixed to one value, but may be changed according to the temperature of the hydraulic oil of the hydraulic braking device 30, for example. In this case, the relationship between the first and second speeds and the temperature of the hydraulic oil may be stored in advance in the memory as a table.

  The temperature of the hydraulic oil is detected by, for example, a hydraulic oil temperature detection sensor (not shown) provided in the brake unit 31 or a pipe for supplying hydraulic oil from the brake unit 31 to the hydraulic brake 34, or Estimated based on detection information from an outside temperature sensor (not shown) for detecting a temperature outside the vehicle (outside temperature) and a braking history by the hydraulic braking device 30 after the ignition switch of the vehicle is turned on. do it.

  The first speed and the second speed are set to lower speeds as the temperature of the detected or estimated hydraulic oil is lower. That is, when the temperature of the hydraulic oil is low, the viscosity of the hydraulic oil is high and the hydraulic oil hydraulic pressure increase rate (that is, the hydraulic braking force increase rate) tends to be slow, and the hydraulic braking force increase rate is slow. If the reduction speed of the regenerative braking force is made too fast, it may not be possible to sufficiently suppress the occurrence of the feeling of missing G. However, the lower the temperature of the hydraulic oil, the lower the first speed and the second speed. Is set to a low speed, it is possible to always achieve both suppression of the occurrence of a feeling of missing G and early elimination of slipping of the wheels 21 regardless of the temperature of the hydraulic oil.

  Next, braking control for the front wheels 22 during vehicle braking by the vehicle controller 2 will be described with reference to the flowchart of FIG.

  In the first step S1, various signals are read, and in the next step S2, it is determined whether or not there is a braking request by the stroke sensor 43. If the determination in step S2 is NO, the process returns to step S1. If the determination in step S2 is YES, the process proceeds to step S3, and the necessary control of each wheel 21 is performed based on the required braking force by the stroke sensor 43. The power is determined, and for the front wheel 22, the regenerative braking force and the hydraulic braking force (only the hydraulic braking force in the case of the rear wheel) are determined from the necessary braking force of the front wheel 22 and the upper limit value of the regenerative braking force obtained as described above. ) And the regenerative braking and the hydraulic braking are executed with the braking force.

  In the next step S4, it is determined whether or not the slip ratio of the front wheel 22 is greater than or equal to the first predetermined value. If the determination in step S4 is NO, the process returns as it is, while the determination in step S4 is YES. Sometimes, the process proceeds to step S5.

  In step S5, the regenerative braking force for the left and right front wheels 22 is decreased at the first speed and the hydraulic braking force is increased. In the next step S6, it is determined whether or not the slip ratio of the front wheel 22 in which the slip has occurred has reached the second predetermined value for the first time after reaching the first predetermined value or more. When the determination at step S6 is NO, the operation at step S6 is repeated. When the determination at step S6 is YES, the process proceeds to step S7.

  In step S7, the regenerative braking force decreasing speed is changed from the first speed to the second speed, and in the next step S8, the slip ratio reaches the second predetermined value after the slip ratio becomes equal to or higher than the first predetermined value. An ABS operation is performed on the front wheel 22 (the front wheel 22 where the slip has occurred).

  In the next step S9, it is determined whether or not there is no braking request, that is, whether or not the amount of depression of the brake pedal 32 by the stroke sensor 43 has become zero. If the determination in step S9 is NO, step S8 is performed. On the other hand, if the determination in step S9 is yes, the process proceeds to step S10.

  In step S10, the ABS operation for the front wheel 22 is stopped, and then the process returns.

  Due to the braking control of the vehicle controller 2, during vehicle braking, the vehicle speed, the regenerative braking force and the hydraulic braking force for the front wheels 22 change as shown in FIG.

  That is, assuming that braking starts at time t1, the brake pedal 32 is depressed by the driver of the vehicle, and the regenerative braking force for the left and right front wheels 22 increases according to the amount of depression. In response to this, the vehicle speed gradually decreases.

  Time t2 is a time point when the regenerative braking force for the left and right front wheels 22 reaches an upper limit value determined by the SOC and temperature of the battery 13. Therefore, thereafter, the regenerative braking force does not increase and is set to a constant value (upper limit value of the regenerative braking force), and the deficiency with respect to the necessary braking force is covered by the hydraulic braking force.

  If slip occurs on one of the left and right front wheels 22 during the regenerative braking, the wheel speed of the front wheel 22 changes as indicated by a one-dot chain line. When the slip ratio of the front wheel 22 reaches the first predetermined value at time t3, the regenerative braking force for the left and right front wheels 22 decreases at the first speed, and the hydraulic braking force for the left and right front wheels 22 increases. Due to the decrease in the regenerative braking force, the slip rate of the front wheel 22 where the slip has occurred decreases after becoming higher than the first predetermined value, and eventually reaches the second predetermined value at time t4.

  At time t4, the regenerative braking force decreasing speed is changed to the second speed. Although not shown in FIG. 3, the ABS operation is performed on the front wheel 22 where the slip has occurred at time t4. That is, at time t4, after the hydraulic braking force decreases, the hydraulic braking force is held constant, and then increases and is repeated. At this time, the maximum hydraulic braking force in the repeated pressure-increasing mode increases as the subsequent pressure-increasing mode increases. Here, the hydraulic braking force shown in FIG. 3 is applied to the other front wheel 22 where no slip has occurred, and increases after time t4 at the same speed as the increasing speed from time t3 to t4. The increase stops when power is reached. The increasing speed of the hydraulic braking force in the pressure increasing mode for the front wheel 22 where the ABS operation is performed is also substantially the same as the increasing speed from the time t3 to the time t4. The speed increases to the required braking force. After time t4, when slip occurs in the other front wheel 22 and the slip ratio becomes equal to or higher than the first predetermined value, the ABS operation is also performed on the other front wheel 22 at that time. The When the slip ratio of the left and right front wheels 22 becomes equal to or greater than the first predetermined value at time t3, the ABS operation is performed on the left and right front wheels 22 at time t4.

  At time t5, the regenerative braking force becomes zero. It is preferable that the hydraulic braking force for the other front wheel 22 reaches the required braking force at or near the time t5. In other words, the second speed is preferably set to a speed at which the regenerative braking force becomes zero at or near the time when the hydraulic braking force on the other front wheel 22 reaches the required braking force.

  In the present embodiment, the vehicle controller 2 and the inverter controller 3 constitute regenerative braking force control means of the present invention, and the vehicle controller 2 and brake controller 5 constitute hydraulic braking force control means of the present invention.

  Therefore, in the present embodiment, when the regenerative braking force by the regenerative braking device 10 is decreasing at the first speed, the predetermined condition (in the present embodiment, the front wheel 22 having the slip rate equal to or higher than the first predetermined value). The regenerative braking force decreases only when the slip ratio reaches the second predetermined value set to a value lower than the first predetermined value for the first time after the slip ratio becomes equal to or higher than the first predetermined value. Since the speed is changed to the second speed lower than the first speed, the following effects can be obtained. That is, since the first speed is a relatively high speed, the regenerative braking force is quickly reduced, thereby reducing the slip ratio of the front wheels 22 where the slip has occurred. If the regenerative braking force continues to decrease at the first speed as it is, a feeling of missing G will occur, but when the predetermined condition is satisfied, the regenerative braking force decrease speed is changed to the second speed. By doing so, it is possible to suppress the occurrence of a feeling of missing G. Further, after the time point when the regenerative braking force decrease speed is changed to the second speed, the hydraulic braking force is increased to such an extent that the effect of executing the ABS operation can be obtained. Further reduction can be achieved. Therefore, it becomes possible to eliminate the slip of the front wheel 22 at an early stage while suppressing the occurrence of the feeling of missing G.

  The present invention is not limited to the embodiment described above, and can be substituted without departing from the spirit of the claims.

  The above-described embodiments are merely examples, and the scope of the present invention should not be interpreted in a limited manner. The scope of the present invention is defined by the scope of the claims, and all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  The present invention includes a regenerative braking device that applies regenerative braking to some of the wheels of the vehicle during vehicle braking, and a hydraulic braking device that applies hydraulic braking to all the wheels during vehicle braking. This is useful for a vehicle control method and a control apparatus.

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 Vehicle controller (regenerative braking force control means) (Hydraulic braking force control means)
3 Inverter controller (regenerative braking force control means)
4 Battery controller 5 Brake controller (hydraulic braking force control means)
10 Regenerative braking device 21 Wheel 30 Hydraulic braking device 31 Brake unit

Claims (3)

Control of a vehicle including a regenerative braking device that applies regenerative braking to some of all wheels of the vehicle during vehicle braking, and a hydraulic braking device that applies hydraulic braking to all the wheels during vehicle braking A method,
At the time of regenerative braking by the regenerative braking device, when the slip rate of at least one wheel to which regenerative braking is applied becomes equal to or higher than a first predetermined value, the regenerative operation to all the wheels to which regenerative braking is applied is performed. Reducing the regenerative braking force by the braking device at a first speed and increasing the hydraulic braking force by the hydraulic braking device;
Executing an anti-lock braking operation by the hydraulic braking device on the wheel having a slip ratio equal to or higher than the first predetermined value after the hydraulic braking force is increased;
When the regenerative braking force by the regenerative braking device is decreasing at the first speed, the slip ratio of the wheel at which the slip ratio is equal to or higher than the first predetermined value becomes equal to or higher than the first predetermined value. For the first time, when the second predetermined value set to a value lower than the first predetermined value is reached, the step of changing the reduction speed of the regenerative braking force to a second speed lower than the first speed is provided. A control method for a vehicle, characterized in that: The control method of claim 1 Symbol placement of the vehicle,
Detecting or estimating the temperature of the hydraulic fluid of the hydraulic brake device;
The vehicle control method further comprising a step of setting the first speed and the second speed to a lower speed as the detected or estimated temperature of the hydraulic oil is lower. Control of a vehicle including a regenerative braking device that applies regenerative braking to some of all wheels of the vehicle during vehicle braking, and a hydraulic braking device that applies hydraulic braking to all the wheels during vehicle braking A device,
At the time of regenerative braking by the regenerative braking device, when the slip rate of at least one wheel to which the regenerative braking is applied becomes equal to or higher than a first predetermined value, the regenerative braking to all the wheels to which the regenerative braking is applied. Regenerative braking force control means for reducing the regenerative braking force by the device at the first speed;
At the time of regenerative braking by the regenerative braking device, when the slip ratio of at least one wheel to which the regenerative braking is applied becomes equal to or higher than the first predetermined value, the hydraulic pressure for all the wheels to which the regenerative braking is applied. The hydraulic braking force by the hydraulic braking device is increased and, after the hydraulic braking force is increased, the anti-lock braking operation by the hydraulic braking device is performed on the wheel having the slip ratio equal to or higher than the first predetermined value. Hydraulic braking force control means
The regenerative braking force control means is configured such that when the regenerative braking force by the regenerative braking device is decreased at the first speed, the slip ratio of the wheel at which the slip ratio is equal to or greater than the first predetermined value is When the second predetermined value set to a value lower than the first predetermined value is reached for the first time after becoming equal to or greater than one predetermined value, the reduction speed of the regenerative braking force is reduced to a second value lower than the first speed. A vehicle control device configured to change to a speed.

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