JP2015226364A - Vehicle brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve braking performance at a low temperature time.SOLUTION: The vehicle brake device includes: a hydraulic brake device 10 for braking a vehicle 1 on the basis of an operation of a brake pedal 17; a motor 4 for driving wheels 3R, 3L; a regenerative brake device 20 for giving the vehicle 1 regenerative brake force by using the motor 4 as a generator; and an oil temperature sensor 15 for detecting the temperature of brake oil in the hydraulic brake device 10. The regenerative brake device 20 is provided with a brake control unit 30 for increasing the regenerative brake force by the regenerative brake device 20 when the temperature of the brake oil detected by the oil sensor 15 becomes low.

Description

  The present invention relates to a vehicle brake device provided with a regenerative brake device.

BACKGROUND ART Many vehicle brake devices employ a hydraulic brake device that performs braking by supplying brake oil from a master cylinder that is operated by operating a brake pedal to a brake caliper of each wheel. The hydraulic pressure supplied to each brake caliper is controlled by a brake pressure control unit.
In addition, in vehicles such as electric vehicles, hybrid vehicles, and plug-in hybrid vehicles, which have a motor for driving, a regenerative brake device is provided to reduce power consumption. It is common to use a brake device to ensure braking force and generate electricity.

  And, as shown in Patent Document 1, in a vehicle equipped with a regenerative brake device, when the rise of hydraulic pressure differs from the specification due to manufacturing variations of the master cylinder or the like, the oil pressure generation point of the master cylinder matches the design value. Further, there is disclosed a technique for reducing a braking delay by changing a hydraulic pressure generation point of a master cylinder with respect to an operation of a brake pedal by a brake pressure control unit.

JP 2012-116425 A

However, even if the oil pressure generation point of the master cylinder is changed as in Patent Document 1 to eliminate the braking delay due to manufacturing variations, in the hydraulic brake device, the kinematic viscosity of the brake oil changes due to the change in the oil temperature. When the temperature is low, there is a problem in that the braking start timing is delayed and a braking delay occurs.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle brake device that improves braking performance at low temperatures.

  In order to achieve the above object, a brake device for a vehicle according to claim 1 is a hydraulic brake device that brakes the vehicle based on an operation of a brake pedal, a motor that drives a traveling wheel of the vehicle, and a motor that generates power from the motor. And a regenerative brake device that applies regenerative braking force to the vehicle and a temperature detector that detects a temperature of brake oil of the hydraulic brake device, and the regenerative brake device is detected by the temperature detector. And a brake control unit for increasing a regenerative braking force by the regenerative brake device as the temperature of the brake oil decreases.

According to a second aspect of the present invention, there is provided the vehicle brake device according to the first aspect, wherein the brake control unit sets the regenerative braking force according to a current vehicle state when the temperature of the brake oil is lower than a predetermined temperature. The regenerative braking device is increased to the maximum amount that can be output.
According to a third aspect of the present invention, there is provided a vehicle brake device according to the second aspect, further comprising a sudden brake detection unit that detects sudden braking when the operation speed of the brake pedal is equal to or higher than a predetermined speed. When the brake detection unit detects the sudden braking, and the brake oil temperature is lower than the predetermined temperature, the regenerative braking force that can be output by the regenerative braking device is maximized according to the current vehicle state. It is characterized by a large increase.

  According to a fourth aspect of the present invention, there is provided a vehicle brake device according to the second aspect, further comprising: an automatic brake control device that automatically stops or decelerates the vehicle, wherein the brake control unit is configured to automatically stop the vehicle by the automatic brake control device. Or, when automatic deceleration is performed and the temperature of the brake oil is lower than the predetermined temperature, the regenerative braking force is increased to the maximum amount that can be output by the regenerative brake device according to the current vehicle state. It is characterized by that.

  According to the vehicle brake device of the first aspect, since the regenerative braking force by the regenerative brake device increases as the temperature of the brake oil of the hydraulic brake device decreases, the braking force of the hydraulic brake device according to the temperature decrease of the brake oil increases. The decrease can be compensated by the regenerative braking force by the regenerative braking device, and the braking force of the entire vehicle can be secured. In addition, since the regenerative braking device enables rapid braking even at low temperatures, braking delay can be effectively eliminated.

Therefore, the braking performance of the vehicle at a low temperature can be improved, and safety can be improved.
According to the vehicle brake device of the second aspect, when the temperature of the brake oil is lower than the predetermined temperature, the regenerative braking force is increased to the maximum amount that can be output by the regenerative brake device according to the current vehicle state. The maximum amount of braking force can be secured when the temperature drops.

According to the vehicle brake device of the third aspect, the regenerative braking force is increased to the maximum amount when the temperature of the brake oil is lower than the predetermined temperature at the time of sudden braking, so that the control is performed when the oil temperature is lowered at the time of sudden braking. Power can be secured and vehicle collision avoidance at low temperatures can be improved.
According to the vehicle brake device of the fourth aspect, the regenerative braking device outputs the regenerative braking force according to the current vehicle state when the temperature of the brake oil is lower than the predetermined temperature when the vehicle is automatically stopped by the vehicle automatic stop device. Since it is increased to the maximum possible amount, the automatic stop performance of the vehicle by the automatic vehicle stop device at low temperatures can be improved.

It is a schematic structure figure of a brake device of vehicles concerning one embodiment of the present invention. It is a high regenerative brake intervention determination control flowchart at the time of low temperature in a brake control unit. It is a control flowchart at the time of sudden braking in a brake control unit. It is a control flowchart at the time of automatic brake control in a brake control unit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The present invention is applied to a vehicle capable of regenerative power generation, such as an electric vehicle, a hybrid vehicle, and a plug-in hybrid vehicle.
The brake device of the vehicle 1 according to the present embodiment includes a hydraulic brake device 10 and a regenerative brake device 20 that applies a braking force to wheels using the motor 4 for driving driving as a generator. Moreover, the vehicle 1 of this embodiment is provided with the anti-lock brake system.

As shown in FIG. 1, the hydraulic brake device 10 includes a master cylinder 11, a brake pressure control unit 12, and calipers 13R, 13R, 14R, and 14L that are brake devices provided on the wheels 2R, 2L, 3R, and 3L. It has.
The master cylinder 11 increases the pressure of the brake oil by operating the brake pedal 17. The brake pressure control unit 12 distributes and controls the brake oil supplied from the master cylinder 11 to the calipers 13R, 13R, 14R, and 14L. The calipers 13R, 13R, 14R, and 14L press the brake pads against the brake rotor that rotates together with the wheels 2R, 2L, 3R, and 3L according to the pressure of the brake oil supplied from the brake pressure control unit 12, and the wheels 2R, A braking force is applied to 2L, 3R, and 3L.

  The brake pressure control unit 12 has a built-in valve for flow rate control and a pump for generating hydraulic pressure when the antilock brake system is operated. The brake pressure control unit 12 includes an oil temperature sensor 15 (temperature detector) that detects the temperature of the brake oil and a hydraulic pressure sensor 16 (rapid brake detection unit) that detects the hydraulic pressure of the brake oil.

Further, the vehicle 1 is provided with a brake pedal switch 18 for detecting depression of the brake pedal 17 (brake on). Each wheel R, 2L, 3R, 3L of the vehicle 1 is provided with wheel speed sensors 19a, 19b, 19c, 19d for detecting the rotational speed of the wheels 2R, 2L, 3R, 3L.
The regenerative braking device 20 supplies the driving power to the motor 4 through the inverter 22, the motor 4 that drives the wheels 3R and 3L via the transmission 21, the inverter 22 that drives and controls the motor 4, A battery 23 that stores electric power generated by the motor 4 and a brake control unit 30 (brake control unit, sudden brake control unit) that outputs a control signal to the inverter 22 are provided.

Moreover, the automatic brake control apparatus 31 is mounted in the vehicle 1 of this embodiment. The automatic brake control device 31 monitors, for example, an obstacle in front of the vehicle with a radar or the like, and automatically activates the brake device when the obstacle approaches to reduce or stop the vehicle speed, thereby causing a collision. It is a device that avoids.
The brake control unit 30 includes a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), a timer, and the like. The vehicle ignition signal, the oil temperature from the oil temperature sensor 15, and the oil pressure sensor The hydraulic pressure from 16, the brake on signal from the brake pedal switch 18, the wheel speed from the wheel speed sensors 19 a, 19 b, 19 c and 19 d, and the automatic brake operation signal from the automatic brake control device 31 are input. The control signal is output to the inverter 22.

  The regenerative brake device 20 is capable of normal brake control in which the regenerative braking force is suppressed to less than the maximum amount and high regenerative brake control in which the maximum amount of regenerative braking force is obtained. In the high regenerative brake control, the regenerative braking force is set to be larger than that in the normal brake control. Therefore, the total braking force of the vehicle 1 is also obtained larger than that in the normal brake control. In the present embodiment, the maximum value is, for example, the capacity limit value of the regenerative brake device 20.

The brake control unit 30 also controls the brake pressure control unit 12 to perform pump operation and brake pressure distribution control to the calipers 13R, 13R, 14R, and 14L when the antilock brake system is operated.
FIG. 2 is a flow chart of the high regenerative brake intervention determination control at a low temperature in the brake control unit 30.

This control is repeatedly executed when the vehicle power is turned on (ignition on).
First, in step S10, the oil temperature T is input from the oil temperature sensor 15, and it is determined whether or not the oil temperature T is lower than the first predetermined temperature Tm. The first predetermined temperature Tm may be set to a temperature (for example, −20 ° C. to −25 ° C.) at which the brake oil has a high viscosity that reduces the response when braking. When the oil temperature T is lower than the first predetermined temperature Tm, the process proceeds to step S20. When the oil temperature T is equal to or higher than the first predetermined temperature Tm, the process proceeds to step S60.

In step S20, the timer is started from zero. Then, the process proceeds to step S30.
In step S30, it is determined whether or not an elapsed time Ti from the start of the timer has exceeded a predetermined time T1. If the elapsed time Ti exceeds the predetermined time T1, the process proceeds to step S40. If the elapsed time Ti is less than or equal to the predetermined time T1, the process returns to step S30. The predetermined time T1 is a time for setting an interval for monitoring the oil temperature T, and may be set to about several seconds, for example.

In step S40, the oil temperature T is input from the oil temperature sensor 15, and it is determined whether or not the oil temperature T is lower than the first predetermined temperature Tm. When the oil temperature T is lower than the first predetermined temperature Tm, the process proceeds to step S50. When the oil temperature T is equal to or higher than the first predetermined temperature Tm, the process proceeds to step S60.
In step S50, it is determined whether to continue the high regenerative brake control. Here, the high regenerative brake flag A is set to 1. Then, the process returns to step S20.

In step S60, it is determined whether to stop the high regenerative brake control. Here, the high regenerative brake flag A is set to zero. Then, this routine ends.
FIG. 3 is a control flowchart at the time of sudden braking in the brake control unit 30.
This control is repeatedly executed when the vehicle power source is turned on (ignition on).

  First, in step S100, it is determined whether or not the vehicle is traveling. Whether or not the vehicle is traveling is determined by inputting wheel speeds from the wheel speed sensors 19a, 19b, 19c, and 19d, and calculating the traveling speed of the entire vehicle 1 by averaging these wheel speeds, for example. May be determined by whether or not is equal to or greater than a predetermined speed greater than zero. Whether or not the vehicle is traveling may be determined by inputting this determination signal when the other control unit or the like of the vehicle 1 determines that the vehicle is traveling. If the vehicle is running, the process proceeds to step S110. If the vehicle is not traveling, the process proceeds to step S150.

  In step 110, it is determined whether or not sudden braking is being performed. Whether or not the brake is suddenly applied may be determined based on whether or not the degree of change in the hydraulic pressure input from the hydraulic sensor 16 (the increase amount θ of the hydraulic pressure per unit time) exceeds a predetermined amount θm. Since the operating speed of the brake pedal of the driver can be known from the increase amount θ of the hydraulic pressure per unit time, it can be determined whether or not the braking is sudden. If the brake is suddenly applied, that is, if the increase amount θ of the hydraulic pressure exceeds the predetermined amount θm, the process proceeds to step S120. If the brake is not suddenly applied, that is, if the increase amount θ of the hydraulic pressure is equal to or less than the predetermined amount θm, the process proceeds to step S150. The control in step S110 and the hydraulic pressure sensor 16 correspond to the sudden brake detection unit of the present invention. Whether or not the brake is suddenly applied may be determined by another method, for example, a change in the operation amount of the brake pedal, instead of a change in the pressure of the brake oil.

In step S120, it is determined whether or not the high regenerative brake flag A is 1. When the high regenerative brake flag A is 1, the process proceeds to step S130. If the high regenerative brake flag A is not 1, that is, 0, the process proceeds to step S140.
In step S130, high regenerative braking control is started to generate the maximum amount of regenerative braking force. Then, this routine ends.

In step S140, the high regenerative brake control is stopped and normal brake control is performed. Then, this routine ends.
In step S150, the routine ends as normal brake control.
FIG. 4 is a brake control flowchart during automatic brake control.
This control starts when the automatic brake control device 31 automatically brakes.

First, in step S200, the brake pressure control unit 12 is controlled to start braking by the hydraulic brake device 10. Then, the process proceeds to step S210.
In step S210, it is determined whether or not the high regenerative brake flag A is 1. When the high regenerative brake flag A is 1, the process proceeds to step S220. If the high regenerative brake flag A is not 1, that is, 0, the process proceeds to step S230.

In step S220, high regenerative brake control is started. Then, this routine ends.
In step S230, high regenerative braking control is stopped, and normal control is performed to return the regenerative braking force during normal braking. Then, this routine ends.
As described above, in the vehicle 1 of the present embodiment, the normal brake control with a small regenerative braking force by the regenerative braking device 20 and the high regenerative brake control for increasing the regenerative braking force to the maximum amount are possible.

As described above, in a vehicle in which the output of the motor 4 is relatively large and the regenerative braking force can be obtained largely by suppressing the regenerative braking force in the normal brake control, the braking effectiveness during the normal brake control is suppressed and the brake fee is reduced. The ring can be made good.
In this embodiment, when the temperature of the brake oil (oil temperature T) is high viscosity lower than the predetermined temperature Tm, high regenerative brake control is performed.

  When the brake oil has a low temperature and a high viscosity, the pressure loss when passing through the flow rate control valve built in the brake pressure control unit 12 in the hydraulic brake device 10 increases, and the calipers 13R, 13R, 14R, and 14L The hydraulic pressure supplied to the vehicle may decrease or the increase in hydraulic pressure may be delayed, resulting in insufficient braking force. Therefore, in the present embodiment, by performing the high regenerative brake control as described above, the shortage of the braking force can be compensated and the total braking force of the vehicle 1 can be ensured.

In particular, since the braking force by the regenerative braking device 20 is not greatly affected by temperature changes, the braking force can be reliably increased. In addition, since the braking by the regenerative braking device 20 enables quick braking with high responsiveness, the braking delay at the start of braking can be effectively eliminated.
Such high regenerative brake control is executed during sudden braking or during automatic brake control by the automatic brake control device 31. Therefore, when the brake oil is at a low temperature during sudden braking, high regenerative braking control can be performed to ensure the maximum amount of regenerative braking force, enabling rapid braking and improving collision avoidance.

Also, during automatic brake control, even if the oil pressure rises by the pump in the brake pressure control unit 12 is delayed when the brake oil is at a low temperature, high-regenerative brake control enables quick braking and avoids collisions. Can be improved.
In addition, this invention is not limited to the said embodiment. For example, in the present embodiment, the high regenerative brake control is performed during sudden braking or automatic brake control, but may be performed during other brake control.

Further, in the above embodiment, the regenerative braking force is set to the maximum amount during the high regenerative braking control, but this is not a limitation, and at least the regenerative braking force is set to be increased compared to during normal braking control. That's fine.
Further, the regenerative braking force may be set to increase continuously or stepwise as the oil temperature T decreases.

Further, in the present embodiment, one traveling drive motor 4 is mounted on the vehicle. However, the present invention can be similarly applied to a vehicle including a plurality of traveling drive motors, and regenerative braking is possible. The present invention can be widely applied to various vehicles.
In the present embodiment, the maximum amount of braking force of the regenerative braking device is the value of the capacity limit of the regenerative braking device. However, the maximum amount of braking force is not limited to this, and the maximum amount of braking force includes battery status, vehicle speed, motor capability, etc. The maximum value of the braking force should be determined at the design stage.

4 Motor 10 Hydraulic brake device 15 Oil temperature sensor (temperature detector)
16 Hydraulic sensor (emergency brake detector)
20 Regenerative brake device 30 Brake control unit (brake control unit, sudden brake detection unit)
31 Automatic brake control device

Claims (4)

A hydraulic brake device for braking the vehicle based on an operation of a brake pedal;
A motor for driving the traveling wheels of the vehicle;
A regenerative braking device that applies regenerative braking force to the vehicle using the motor as a generator;
A temperature detector for detecting the temperature of the brake oil of the hydraulic brake device,
The regenerative brake device includes a brake control unit that increases a regenerative braking force by the regenerative brake device when the temperature of the brake oil detected by the temperature detector decreases.   When the temperature of the brake oil is lower than a predetermined temperature, the brake control unit increases the regenerative braking force to a maximum amount that can be output by the regenerative brake device according to a current vehicle state. The brake device for a vehicle according to claim 1. A sudden brake detection unit that detects sudden braking when the operation speed of the brake pedal is equal to or higher than a predetermined speed;
The brake control unit, when the sudden braking is detected by the sudden brake detection unit, when the temperature of the brake oil is lower than a predetermined temperature, the regenerative braking force is regenerated according to the current vehicle state. The vehicle brake device according to claim 2, wherein the brake device is increased to a maximum amount that can be output. An automatic brake control device for automatically stopping or automatically decelerating the vehicle;
The brake control unit is configured to set the regenerative braking force to a current vehicle state when the brake oil temperature is lower than a predetermined temperature when the vehicle is automatically stopped or decelerated by the automatic brake control device. 3. The vehicle brake device according to claim 2, wherein the regenerative brake device is increased to a maximum amount that can be output in response to the change.

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