JP2012076636A - Brake control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize energy and improve brake performance in a brake control device of a vehicle.SOLUTION: The brake control device of a vehicle is provided with a motor device 1 for applying regenerative braking force to a wheel 11 through regenerative power generation, and a brake device 2 for applying friction braking force to the wheel 11, and further provided with a detecting means 7a for detecting the amount of electric power to be charged to a battery 9 to which electric power generated in the motor device 1 is charged, and a blowing means 3 for blowing air on the friction face of the brake device 2 driven with electric power of the battery 9. In addition, the brake control device is provided with: cooling means 4, 5 for cooling the air blown with the blowing means 3 driven with the electric power of the battery 9; and a control means 7c for driving the blowing means 3 and the cooling means 4, 5 in response to the amount of power charged detected by the detecting means 7a.

Description

  The present invention relates to a vehicle braking control apparatus including a regenerative brake and a mechanical brake.

  2. Description of the Related Art Conventionally, in an electric vehicle or a hybrid vehicle that travels by driving a motor with battery power, regenerative control that regenerates power by generating electric power with the motor using kinetic energy of wheels during vehicle deceleration or braking is performed. At the time of regenerative control, the generated electric power is charged in the battery, and a regenerative braking force having a magnitude corresponding to the charged electric energy is applied to the wheels. In addition, a mechanical brake device that applies friction braking force to the wheel, such as a disc brake or a drum brake, is also provided on the wheel. Therefore, the braking force applied to the wheels is controlled to an appropriate magnitude according to the braking request while using both the regenerative brake related to the regenerative braking force and the mechanical brake related to the friction braking force.

  By the way, the magnitude of the regenerative braking force by the regenerative brake depends on the state of charge of the battery. For example, when the battery is less than fully charged, the amount of charge can be increased by increasing the amount of power generated by the motor, and a large regenerative braking force can be obtained. On the other hand, if the battery is in a fully charged state, the battery cannot be charged any further, so the amount of power generated by the motor cannot be increased, and the regenerative braking force decreases. Therefore, there is a problem that when the charge amount of the battery is sufficient, the load on the mechanical brake is relatively increased, the amount of heat generated on the friction surface is increased, and fading is likely to occur.

  In particular, in the case of an electric vehicle, the vehicle weight increases because it is necessary to mount a large amount of a running battery in the vehicle. Therefore, the capacity of the mechanical brake tends to be insufficient, and the amount of heat generated on the friction surface tends to increase. In addition, since the load on the regenerative brake is relatively reduced, an operation in which the driver strongly depresses the brake pedal is likely to occur. This further increases the load on the mechanical brake and may further increase the amount of heat generated.

  In view of this, a technique has been developed that forcibly consumes battery power to electrical components when regenerative power charging overcharges the battery. For example, Patent Document 1 describes a control for reducing the amount of charge of a battery by supplying battery power to an air conditioner or auxiliary equipment when the input / output voltage of the battery is equal to or higher than a specified value. Such control prevents overcharging of the battery, so that a situation where the regenerative braking force is reduced is avoided.

JP 2005-39885 A

However, while deceleration and braking operations are operations that can be input at any time when the vehicle is traveling, the air conditioners and accessories are not always in operation. For this reason, there is a possibility that electric power is not consumed even though the amount of charge of the battery is sufficient, and a decrease in regenerative braking force cannot be avoided. That is, in this case, the load on the mechanical brake is relatively increased, and the amount of heat generated on the friction surface is increased, which may cause fade.
For such a problem, it is also conceivable to reduce battery power by driving an electric actuator included in the air conditioner even when the air conditioner is not operating. However, in this case, battery power is wasted, and energy saving performance and ecology performance are greatly reduced.

  Further, the magnitude of the friction braking force applied to the wheels by the mechanical brake changes according to the traveling state of the vehicle. For example, when the surface temperature rises due to contact friction between the friction engagement member and the brake rotating body, the friction coefficient changes, so even if the pressing force between the friction engaging element and the brake rotating body is the same. The friction braking force decreases. In particular, in an electric vehicle having a large mechanical brake load, the friction braking force of the mechanical brake is likely to decrease, and it is difficult to achieve a good braking feeling.

One of the purposes of the present case has been devised in view of the above-described problems, and relates to a vehicle braking control device that achieves both effective use of energy and improvement of braking performance.
The present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiments for carrying out the invention described later, and other effects of the present invention are to obtain a function and effect that cannot be obtained by conventional techniques. Can be positioned.

  (1) A vehicle braking control device disclosed herein includes a motor device that applies a regenerative braking force to a wheel by regenerative power generation and a brake device that applies a friction braking force to the wheel. It is. First, a detection unit that detects a charge amount of a battery that is a charging destination of power generated by the motor device, and a blower unit that is driven by the power of the battery and blows air to the friction surface of the brake device. . In addition, a cooling unit that is driven by the power of the battery and that cools the air that is blown by the blowing unit, and a control that drives the blowing unit and the cooling unit according to the amount of charge detected by the detection unit. Means.

(2) Moreover, it is preferable that the said control means controls the temperature of the said air cooled by the said cooling means according to the said charge amount detected by the said detection means.
(3) Moreover, it is preferable that the said control means lowers the temperature of the said air to the said cooling means, so that the said charge amount is near full charge amount.
(4) Moreover, it is preferable that the said control means increases the ventilation volume of the said air to the said ventilation means, so that the said charge amount is close to a full charge amount.

(5) In addition, when the charging amount is equal to or greater than a predetermined amount, the control unit sets the blowing unit and the cooling unit so that the blowing amount by the blowing unit and the cooling amount by the cooling unit are maximized. It is preferable to drive.
(6) Furthermore, it is preferable that the cooling means is provided separately from an air conditioner that cools the air supplied to the passenger compartment.

  According to the disclosed vehicle braking control device, it is possible to prevent the occurrence of fading due to frictional heat by driving the blowing unit and the cooling unit according to the amount of charge to cool the brake device. Moreover, the charge amount of a battery can be reduced by driving a ventilation means and a cooling means, and regenerative braking force can be ensured. Thereby, both the friction brake performance and the regenerative brake performance can be ensured at the same time, and the brake performance of the vehicle as a whole can be improved while effectively using energy.

It is a block diagram which illustrates the composition of the brake control device of vehicles concerning an embodiment. (A) is a flowchart which shows the control content implemented with the braking control apparatus of FIG. 1, (b) is a flowchart as the modification. It is the block diagram which illustrated the composition of the brake control device as a modification.

  A vehicle braking control device will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment.

[1. Constitution]
The braking control device of this embodiment is applied to the vehicle 10 shown in FIG. The vehicle 10 is an electric vehicle that travels by driving a motor 1 (motor device) with electric power of a battery 9. The motor 1 is a motor generator that has both a function of rotating the wheels 11 by consuming electric power from the battery 9 and a function of regenerating power by power generation using the torque of the wheels 11 during braking. These two types of functions are appropriately controlled according to the traveling state of the vehicle 10. In FIG. 1, two rear wheels are mechanically connected to the motor 1 via the transmission 14, and the upper side of the drawing in FIG. 1 corresponds to the front of the vehicle. The wheels 11 driven by the motor 1 may be at least two wheels, that is, front wheels or rear wheels, and all the wheels 11 may be drive wheels.

  Each wheel 11 is provided with a mechanical brake 2 (brake device) such as a disc brake or a drum brake. The brake 2 of each wheel 11 is connected to a hydraulic line 17 that transmits the hydraulic pressure corresponding to the depression amount of the brake pedal 15. Further, the brake pedal 15 is provided with a stroke sensor 16 for detecting the amount of depression, and the amount of depression detected here is transmitted to the EV-ECU 7 to set the braking force applied to each wheel 11 from the brake 2. Used.

  The EV-ECU 7 (Electric Vehicle Electronic Control Unit) is a top-level electronic control unit that comprehensively manages various electronic control devices mounted on the vehicle 10. As an electronic control unit below the EV-ECU 7, there are a BMU (Battery Management Unit) that manages the battery 9, an MCU (Motor Control Unit) that manages the operation of the motor 1, an air conditioning ECU 6 that manages the air conditioning state of the vehicle 10, and the like. Can be mentioned. All electronic control units including the EV-ECU 7 are electronic control units configured by a microcomputer, and are configured as, for example, LSI devices or embedded electronic devices in which a known microprocessor, ROM, RAM, and the like are integrated. These electronic control devices are connected to each other via a communication line 18 such as CAN or FlexRay. In FIG. 1, descriptions of electronic control devices other than the air conditioning ECU 6 and the EV-ECU 7 are omitted.

  The air conditioning ECU 6 is a controller that controls the operation of an HVAC 8 (Heater, Ventilator and Air Conditioner) that adjusts the air conditioning environment such as the temperature and humidity inside the vehicle 10. The HVAC 8 includes an air conditioning evaporator 8a, an air conditioning heater 8b, an air conditioning fan 8c, and the like. A compressor 5 that compresses refrigerant is connected to the air conditioning evaporator 8a. The HVAC 8 draws air from the vehicle interior or the outside of the vehicle, adjusts its temperature and humidity, and supplies the air and the vehicle interior via the air conditioning duct 13.

The air conditioning evaporator 8a is an expander that absorbs heat by decompressing and evaporating the refrigerant introduced from the compressor 5 side, and functions as a cooling device that cools the air sucked by the air conditioning fan 8c. The air conditioning evaporator 8a and the compressor 5 are connected by a refrigerant line 20 through which a refrigerant flows. The air conditioning heater 8b functions as a heating device that heats air using the heat of electricity or engine cooling water. The temperature of the air supplied into the passenger compartment is adjusted by the air conditioning evaporator 8a and the air conditioning heater 8b, and the amount of air (air volume) is adjusted by controlling the rotational speed of the air conditioning fan 8c.
The electric power of the battery 9 is supplied not only to the motor 1 but also to various electrical components mounted on the vehicle 10. For example, driving power for the HVAC 8 and the compressor 5 is supplied from the battery 9.

A brake cooling structure for cooling the brake 2 provided on each wheel 11 is applied to the vehicle 10, and as shown in FIG. 1, a fan 3, an evaporator 4 and a brake duct 12 are provided. . One end of the brake duct 12 is opened to the inside or outside of the vehicle, and the other end is extended to the vicinity of the friction surface of each brake 2. The fan 3 and the evaporator 4 are provided in the brake duct 12.
The evaporator 4 is an expander that receives the supply of refrigerant from the compressor 5 and cools the air in the brake duct 12 in the same manner as the air conditioning evaporator 8a. The compressor 5 and the evaporator 4 are connected by a refrigerant line 20 different from that connecting the air conditioning evaporator 8 a and the compressor 5.

The fan 3 sucks air from inside or outside the vehicle and supplies air cooled by the compressor 5 to the friction surface of each brake 2. A power line 19 is connected between the fan 3 and the battery 9, and driving power for the fan 3 is supplied from the battery 9.
The operations of the fan 3 and the compressor 5 are controlled by the air conditioning ECU 6 and the EV-ECU 7. Hereinafter, details of control in the EV-ECU 7 will be described in detail. In FIG. 1, the brake 2 to be cooled is only the front wheel of the vehicle 10, but the brake duct 12 is extended to the vicinity of the brake 2 of the rear wheel, and the rear wheel of the vehicle 10 is to be cooled. It is also possible.

[2. Control configuration]
In the EV-ECU 7, regeneration control and brake cooling control are performed. Regenerative control is control that regenerates electric power by generating power with a motor using the kinetic energy of wheels during vehicle deceleration or braking. The brake cooling control is a control for improving the friction braking force by cooling the friction surface of the brake 2 of each wheel 11. As an element for performing these controls, the EV-ECU 7 is provided with a battery charge amount detection unit 7a, a regeneration control unit 7b, and a brake cooling control unit 7c. These functions of the battery charge amount detection unit 7a, the regeneration control unit 7b, and the brake cooling control unit 7c may be realized by an electronic circuit (hardware), may be programmed as software, or A part of these functions may be provided as hardware and the other part may be software.

The battery charge amount detection unit 7a detects or calculates the charge rate (SOC, State Of Charge) of the battery 9. For example, based on the open circuit voltage V of the battery, a value representing the degree of charging as a percentage (such as a fully discharged state being 0 [%] and a fully charged state being 100 [%]) is calculated. Note that the charging rate may be detected or calculated using a known method based on the internal resistance value of the battery 9, the battery discharge amount, the battery temperature, and the like. The charging rate detected or calculated here is transmitted to the regeneration control unit 7b and the brake cooling control unit 7c.
The regenerative control unit 7b performs regenerative control with the motor 1 during vehicle deceleration or braking. For example, when the stroke sensor 16 detects that the brake pedal 15 is depressed, the regenerative control unit 7 b outputs a signal for operating the motor 1 as a generator, and charges the battery 9 with regenerative power. However, when the charge rate detected by the battery charge amount detection unit 7a is equal to or higher than a predetermined charge rate (for example, 98 [%]) close to full charge, regenerative control is suppressed or prohibited, and overcharge to the battery 9 is prevented. To prevent.

The suppression of regenerative control here refers to control that reduces the generated power as compared to normal regenerative control. For example, when an inverter device that controls the voltage and current applied to the motor 1 is interposed between the battery 9 and the motor 1, the amount of power generation can be increased or decreased by adjusting the voltage and current. Therefore, the power generation amount related to the regenerative control can be suppressed by controlling the power generation amount to decrease as the charging rate increases.
During regenerative control, a regenerative braking force having a magnitude corresponding to the amount of charge to the battery 9 acts on each wheel 11. The wheel 11 is braked by receiving two types of braking forces, a regenerative braking force generated by the regenerative control and a friction braking force applied by the brake 2.

The brake cooling control unit 7 c performs brake cooling control according to the charging rate of the battery 9. In the brake cooling control, the brake cooling control unit 7c outputs a control signal to the air conditioning ECU 6, and the air conditioning ECU 6 receiving the control signal drives the fan 3 and the compressor 5 to cool the friction surface of the brake 2. The start condition of the brake cooling control is, for example, that the charging rate is equal to or higher than the predetermined charging rate. Further, specific control contents of the fan 3 and the compressor 5 can be arbitrarily set. In addition, it is preferable that the predetermined charging rate which concerns on the start condition of brake cooling control is below the predetermined charging rate in which regeneration control is suppressed or prohibited.
As a typical control example, when the charging rate is equal to or higher than the predetermined charging rate, it is conceivable to drive the fan 3 at its maximum rotational speed and drive the compressor 5 at its maximum capacity. In this case, the amount of cooling air supplied to the brake 2 is maximized, and the temperature of the cooling air is the lowest.

[3. flowchart]
The procedure of brake cooling control will be described using the flowchart of FIG. This flowchart is repeatedly executed in the EV-ECU 7 at a predetermined cycle. Note that the regeneration control is performed in parallel with the brake cooling control based on another flowchart independent of this flowchart.
In step A10, the battery charge amount detector 7a of the EV-ECU 7 reads the open voltage V of the battery 9, and the charging rate is calculated in the subsequent step A20. In step A30, the brake cooling control unit 7c determines whether or not the charging rate of the battery 9 is equal to or higher than a predetermined charging rate.

  If the charging rate is less than the predetermined charging rate, the battery 9 is not likely to be overcharged even if regenerative control is performed, so control proceeds to step A40 and brake cooling control is not performed. . On the other hand, when the charging rate is equal to or higher than the predetermined charging rate, the control proceeds to step A50, and brake cooling control is performed. That is, a control signal is output from the brake cooling control unit 7c to the air conditioning ECU 6, and the fan 3 is driven at the maximum rotational speed and the compressor 5 is driven at the maximum capacity. Thereby, the friction surface of the brake 2 is cooled, and the fall of a friction coefficient is suppressed.

  By driving the fan 3 and the compressor 5 in step A50, the charging rate of the battery 9 is lowered. Therefore, even if the regenerative control is performed, the regenerative control is not stopped, and a decrease in the regenerative braking force is avoided. Further, when the charging rate of the battery 9 decreases to less than a predetermined charging rate in the subsequent control cycle, the brake cooling control is not performed, and the fan 3 stops. If the air conditioning ECU 6 is not operating the compressor 5 for indoor air conditioning, the operation of the compressor 5 is stopped.

[4. Action, effect]
According to the braking control device of the present embodiment, execution / non-execution of brake cooling control is selected according to the charge amount of the battery 9, and when the charge amount is equal to or greater than the predetermined charge amount, the fan 3 and the compressor 5 are Brake cooling control is performed so that the air blowing amount and the cooling amount when the maximum capacity is exhibited are obtained. At this time, since the cooling air supplied to the friction surface of the brake 2 is cooled by the evaporator 4, the temperature of the cooling air is lower than the outside air temperature or room temperature.
Therefore, the occurrence of fade due to frictional heat can be prevented by controlling the air blowing to the brake 2 in accordance with the amount of charge. Moreover, by driving the fan 3 and the compressor 5 according to the charge amount, the charge amount of the battery 9 can be reduced, and the regenerative braking force can be ensured.

  For example, if the charge amount of the battery 9 becomes equal to or greater than a predetermined charge amount, the regeneration control unit 7b of the EV-ECU 7 suppresses or prohibits the regeneration control. The braking force will decrease. On the other hand, in the present brake control device, the power of the battery 9 is consumed by driving the fan 3 and the compressor 5, so that the regeneration control is continued. Thereby, both friction brake performance and regenerative brake performance can be ensured simultaneously, and the brake performance of the vehicle 10 as a whole can be improved.

Moreover, since the temperature of the cold air supplied to the brake 2 is controlled according to the charge amount, the charge amount of the battery 9 can be quickly reduced, that is, the regenerative control is prohibited due to overcharge. Can be avoided quickly, and regenerative braking performance can be maintained. Furthermore, the friction surface temperature of the brake 2 can be quickly cooled, and the friction brake performance can be improved.
In particular, in the present braking control device, the fan 3 and the compressor 5 are driven at their maximum capacities, so that the amount of charge of the battery 9 can be consumed efficiently, and the regenerative braking force is ensured by the regenerative driving of the motor 1. Therefore, it is possible to always ensure an appropriate braking force for the vehicle 10.

  Further, in the above braking control device, the fan 3 and the evaporator 4 are provided separately from the HVAC 8, so that the cooling air temperature and air volume management related to the brake cooling control can be managed separately from the air conditioning control in the passenger compartment. It becomes. Thus, both the friction brake performance and the regenerative brake performance can be improved regardless of the air conditioning environment in the passenger compartment or the traveling state of the vehicle 10. For example, even if the heating function of the HVAC 8 is operated by a manual operation of a passenger of the vehicle 10, the brake cooling control can be performed independently of the control.

[5. Modified example]
Regardless of the embodiment described above, various modifications can be made without departing from the spirit of the invention. Each structure of this embodiment can be selected as needed, or may be combined appropriately.
In the above-described brake cooling control, the fan 3 is driven at its maximum rotational speed and the compressor 5 is driven at its maximum capacity. However, the amount of cooling air supplied to the brake 2 and the temperature of the cooling air are charged. It is preferable to set according to. For example, it is conceivable that the blowing temperature decreases as the charging amount increases (closer to full charging). Alternatively, it is conceivable to increase the blowing amount as the charging amount increases.

In this case, it is conceivable to perform the brake cooling control in the procedure as shown in FIG. Steps A10 to A40 are the same as those in the flowchart described above, but the contents of the brake cooling control are different. In step A60, the target rotational speed of the fan 3 having a size corresponding to the charging rate of the battery 9 is set. The relationship between the charging rate and the target rotational speed is such that the higher the charge amount is, the higher the rotation speed is (that is, the greater the charge amount, the greater the amount of blown air).
In the subsequent step A70, the target output of the compressor 5 having a size corresponding to the charging rate of the battery 9 is set. As for the relationship between the charging rate and the target output, the larger the charging amount is, the larger the output is (that is, the larger the charging amount, the lower the blowing temperature).

  As the output of the compressor 5 is increased so as to lower the blowing temperature, the power consumption of the compressor 5 increases and the rate of decrease of the charge amount of the battery 9 increases. Thereby, the amount of charge can be reduced quickly. Therefore, even if the regenerative control is started and the amount of charge suddenly increases, electric power corresponding to the amount of charge can be quickly consumed by the compressor 5 and the regenerative braking force can be reliably applied to the wheels 11. it can. Further, by increasing the output of the compressor, cooler air is supplied to the friction surface of the brake 2, and the friction braking force can be strengthened.

  Similarly, as the rotational speed of the fan 3 is increased to increase the amount of air blown, the power consumption of the fan 3 increases and the rate of decrease in the amount of charge of the battery 9 increases. Therefore, the regenerative braking force can be reliably applied to the wheel 11. Further, by increasing the amount of air blown, the amount of heat released from the friction surface of the brake 2 can be increased, and the friction braking force can be strengthened.

  In the above-described embodiment, the fan 3 and the evaporator 4 are provided separately from the HVAC 8. However, brake cooling control is performed using the air conditioning evaporator 8 a and the air conditioning fan 8 c built in the HVAC 8. It is good also as composition to do. For example, as shown in FIG. 3, a damper 21 for branching a passage from an air conditioning duct 13 that leads from the HVAC 8 to the room and connecting it to the brake duct 12 and changing the air flow direction to a branch position in the air conditioning duct 13. Is provided.

When the brake cooling control is not performed, the brake duct 12 is closed by the damper 21 as shown by a solid line in FIG. On the other hand, when the brake cooling control is performed, the damper 21 closes the passage leading to the room as indicated by the broken line. By such control, at least brake cooling control similar to that described above can be performed. If the air supplied from the HVAC 8 is appropriately distributed to the indoor side and the brake duct 12 side by controlling the opening degree of the damper 21, it is possible to simultaneously perform the brake cooling control and the indoor air conditioning.
The braking control device described above can be applied to all vehicles that brake the wheels 11 using both the regenerative braking force and the friction braking force, and can be applied to, for example, an electric vehicle or a hybrid vehicle equipped with an engine. .

1 Motor (motor device)
2 Brake (brake device)
3 Fan (Blowing means)
4 Evaporator (cooling means)
5 Compressor (cooling means)
6 Air conditioning ECU
7 EV-ECU
7a Battery charge amount detection unit (detection means)
7b Regenerative control unit 7c Brake cooling control unit (control means)
8 HVAC (air conditioner)
8a Air conditioning evaporator 8b Air conditioning heater 8c Air conditioning fan 9 Battery 10 Vehicle 11 Wheel 12 Brake duct 13 Air conditioning duct 14 Transmission 15 Brake pedal 16 Stroke sensor 17 Hydraulic line 18 Communication line 19 Power line 20 Refrigerant line 21 Damper

Claims (6)

A vehicle braking control device provided with a motor device that applies a regenerative braking force to a wheel by regenerative power generation and a brake device that applies a friction braking force to the wheel,
Detecting means for detecting a charge amount of a battery that is a charging destination of the electric power generated by the motor device;
Blower means driven by the power of the battery and blows air to the friction surface of the brake device;
Cooling means driven by the power of the battery and cooling the air blown by the blowing means;
A vehicle braking control apparatus comprising: a control unit that drives the blowing unit and the cooling unit according to the amount of charge detected by the detection unit. The control means is
The vehicle braking control device according to claim 1, wherein the temperature of the air cooled by the cooling means is controlled in accordance with the amount of charge detected by the detecting means. The control means is
The braking control device for a vehicle according to claim 1 or 2, wherein the temperature of the air is reduced in the cooling means as the charge amount is closer to a full charge amount. The control means is
4. The vehicle braking control device according to claim 1, wherein as the charge amount is closer to a full charge amount, the air blowing amount is increased by the air blowing unit. 5. The control means is
The air blowing means and the cooling means are driven so that the amount of air blown by the air blowing means and the amount of cooling by the cooling means are maximized when the charge amount is a predetermined amount or more. The braking control device for a vehicle according to any one of 1 to 4. The cooling means is
The vehicle braking control device according to any one of claims 1 to 5, wherein the vehicle braking control device is provided separately from an air conditioner that cools air supplied to the passenger compartment.

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