JP2013141338A - Braking device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a braking device for a vehicle, capable of improving response in braking with respect to emergency operation of a brake pedal.SOLUTION: For braking of a hybrid car 1, regenerative braking force generated by a motor generator 3 and frictional braking force generated by a friction brake mechanism 4 are used in combination. An operation amount of a brake pedal 5 is detected by a brake pedal stroke sensor 12. On the basis of output of the brake pedal stroke sensor 12, target regenerative braking force of the motor generator 3 is set. Further, the motor generator 3 is controlled on the basis of the target regenerative braking force. If the brake pedal 5 is operated in emergency, the target regenerative braking force of the motor generator 3 is increased at once by a predetermined amount. Consequently, the regenerative braking force by the motor generator 3 is increased, and braking force acted to the hybrid car 1 is increased.

Description

  The present invention relates to a braking device for a vehicle.

  In an electric car or a hybrid car, kinetic energy is regenerated into electric power (electric energy) during deceleration. Then, so-called regenerative braking is performed in which the resistance generated at that time is used as a braking force. Further, when the braking force is insufficient with only the regenerative braking force, friction braking (hydraulic braking) by a hydraulic brake is also performed.

  When the brake pedal is depressed, the force input to the brake pedal is amplified (boosted) by the brake booster, and the amplified force is transmitted to the master cylinder. Then, the force input to the master cylinder is transmitted as hydraulic pressure to a brake cylinder provided on each wheel, and the brake pad is pressed against a brake rotor that rotates integrally with the wheel, thereby controlling the wheel (brake rotor). Power works.

  Further, when the brake pedal is strongly depressed instantly (emergency operation is performed), the brake assist function is activated and the friction braking force is increased. In other words, a hydraulic pressure sensor that detects the hydraulic pressure in the master cylinder is provided, and if it is determined that the brake pedal is strongly depressed instantaneously (emergency operation) based on the output of the hydraulic pressure sensor, for example, a negative pressure is detected. The work of the pressure pump is increased, and the negative pressure from the negative pressure pump is transmitted to the brake booster. As a result, the friction braking force increases.

Japanese Patent Laid-Open No. 2001-8306

  However, from the emergency operation of the brake pedal until the friction braking force increases, the oil pressure in the master cylinder changes, the change in the output of the oil pressure sensor due to the change in oil pressure, the generation of negative pressure by the negative pressure pump, the application to the brake booster It takes time because it passes through the steps of negative pressure transmission and hydraulic pressure transmission from the master cylinder to the brake cylinder.

  Further, due to the oil temperature or the like, the response of increase in friction braking force to emergency operation of the brake pedal varies.

  Furthermore, in order to obtain a large friction braking force (brake assist force), if a large capacity negative pressure pump is adopted, not only the cost and size increase, but also the energy required for driving the negative pressure pump increases, There is also a problem that the fuel consumption of electric cars and hybrid cars is reduced.

  An object of the present invention is to provide a vehicle braking device that can improve a braking response to an emergency operation of a brake pedal.

  In order to achieve the above object, a braking device for a vehicle according to the present invention includes a brake pedal operated by a driver, and friction braking means for generating a friction braking force by a hydraulic pressure corresponding to an operation amount of the brake pedal. And a regenerative braking means for generating a regenerative braking force, a brake pedal stroke sensor for detecting an operation amount of the brake pedal, and a target regenerative amount of the regenerative braking means based on an output of the brake pedal stroke sensor. Based on the target regeneration amount setting means and the output of the brake pedal stroke sensor, it is determined whether or not the brake pedal is urgently operated, and the determination means determines that the brake pedal is urgently operated. The target regeneration amount set by the target regeneration amount setting means is increased by a predetermined amount at a time. And a raw amount increasing means.

  For braking the vehicle, a regenerative braking force generated by the regenerative braking means and a friction braking force generated by the friction braking means are used in combination.

  When the brake pedal is operated, the friction braking means generates a friction braking force with a hydraulic pressure corresponding to the operation amount. Further, the operation amount of the brake pedal is detected by a brake pedal stroke sensor. Based on the output of the brake pedal stroke sensor, the target regeneration amount of the regenerative braking means is set. The regenerative braking means is controlled based on the target regenerative amount, so that the regenerative braking means generates a regenerative braking force corresponding to the target regenerative amount. As a result, the friction braking force by the friction braking means and the regenerative braking force by the regenerative braking means act on the vehicle.

  When the brake pedal is operated urgently, the target regeneration amount of the regenerative braking means is increased at a time by a predetermined amount. As a result, the regenerative braking force increases and the braking force acting on the vehicle increases.

  The regenerative amount of the regenerative braking means changes instantaneously by changing the excitation current supplied to the regenerative braking means. Therefore, the time required from the emergency operation of the brake pedal to the increase of the regenerative braking force is shorter than the time required from the emergency operation of the brake pedal to the increase of the friction braking force.

  Further, based on the output of the brake pedal stroke sensor, it is determined whether or not the brake pedal has been urgently operated. The output of the brake pedal stroke sensor changes without delay with respect to the operation of the brake pedal. Therefore, in this configuration, the time until it is determined that the brake pedal is urgently operated is compared with the configuration in which the presence or absence of an emergency operation of the brake pedal is determined based on the output of the hydraulic pressure sensor that detects the hydraulic pressure in the master cylinder. Is short.

  Furthermore, since the regenerative braking force is independent of the fluid temperature of the friction braking means, the response of the increase of the regenerative braking force to the emergency operation of the brake pedal is not affected by the fluid temperature and is stable.

  Therefore, it is possible to exhibit a good and stable response of braking to the emergency operation of the brake pedal.

  In addition, unlike the configuration in which the friction braking force is increased in response to an emergency operation of the brake pedal, there is no need to increase the capacity of the pump included in the friction braking means, which increases the cost and size of the friction braking means. No. In addition, the fuel consumption is not lowered due to the increase of the driving energy of the pump.

  ADVANTAGE OF THE INVENTION According to this invention, the response of braking with respect to emergency operation of a brake pedal can be improved.

FIG. 1 is a block diagram showing a main part configuration of a hybrid car equipped with a braking device according to an embodiment of the present invention. FIG. 2 is a map that defines the relationship between the brake pedal depression amount and the braking force. FIG. 3 is a flowchart showing the flow of emergency operation determination processing.

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

  FIG. 1 is a block diagram showing a main part configuration of a hybrid car equipped with a braking device according to an embodiment of the present invention.

  The hybrid car 1 is equipped with an engine 2 and a motor generator 3 as drive sources.

  The engine 2 is, for example, a gasoline engine or a diesel engine, and generates a driving force necessary for traveling the hybrid car 1. A driving force (engine output) output from the engine 2 is transmitted to driving wheels of the hybrid car 1, for example, left and right front wheels FL, FR.

  The motor generator 3 is a DC brushless motor, and has a function as a motor and a function as a generator (generator). When the motor generator 3 functions as a motor, the driving force output from the motor generator 3 is transmitted to the driving wheels of the hybrid car 1. When the motor generator 3 functions as a generator, the power transmitted from the drive wheels of the hybrid car 1 or the engine 2 is regenerated (converted) into electric power.

  The hybrid car 1 is provided with a friction brake mechanism 4.

  The friction brake mechanism 4 includes a brake pedal 5, a vacuum booster 6, a master cylinder 7, an electric negative pressure pump 8, a pressure accumulation tank 9, a valve 10, and a negative pressure sensor 13.

  The brake pedal 5 is set in front of the driver's seat in the passenger compartment and is operated with the driver's feet. When the brake pedal 5 is operated (depressed), the force input to the brake pedal 5 is transmitted to the vacuum booster 6. The negative pressure transmitted from the electric negative pressure pump 8 and / or the pressure accumulation tank 9 to the vacuum booster 6 amplifies (boosting) the force input from the brake pedal 5 to the vacuum booster 6, and the amplified force is It is transmitted to the master cylinder 7. The force input to the master cylinder 7 is transmitted as hydraulic pressure to a brake cylinder (not shown) provided on each wheel FL, FR, RL, RR, and a brake pad (not shown) is transmitted to the wheels FL, FR. , RL, RR are pressed against a brake rotor (not shown) that rotates integrally with each other, and friction braking force acts on the wheels FL, FR, RL, RR.

  The valve 10 is for switching transmission / cutoff of the negative pressure from the pressure accumulation tank 9 to the vacuum booster 6.

  The hybrid car 1 is equipped with an ECU (electronic control unit) 11 having a configuration including a microcomputer.

  The ECU 11 is supplied with detection signals from a brake pedal stroke sensor 12 that detects the depression amount (stroke) of the brake pedal 5 and a negative pressure sensor 13 that detects the pressure inside the vacuum booster 6. Instead of the negative pressure sensor 13, a negative pressure switch may be provided.

  The ECU 11 controls the motor generator 3, the electric negative pressure pump 8 and the valve 10 based on the detection signals input from the brake pedal stroke sensor 12 and the negative pressure sensor 13.

  FIG. 2 is a map that defines the relationship between the brake pedal depression amount and the braking force.

  The ECU 11 sets the target braking force according to the depression amount of the brake pedal 5 detected by the brake pedal stroke sensor 12 with reference to the target braking force map M1 shown in FIG. The target braking force map M1 is created, for example, so that the target braking force increases almost in proportion to the depression amount of the brake pedal 5.

  Further, the ECU 11 sets a target friction braking force according to the depression amount of the brake pedal 5 detected by the brake pedal stroke sensor 12 with reference to the target friction braking force map M2 shown in FIG. The target friction braking force map M2 is created, for example, such that the target friction braking force increases substantially in proportion to the depression amount of the brake pedal 5, and the inclination thereof is smaller than the inclination of the target braking force map M1.

  Further, the ECU 11 calculates the target regenerative braking force by subtracting the target friction braking force set based on the target friction braking force map M2 from the target braking force set based on the target braking force map M1.

  The ECU 11 sets a target negative pressure for obtaining the target friction braking force, controls the driving of the electric negative pressure pump 8 so as to obtain the target negative pressure, and, if necessary, the valve 10 Is established. As a result, the hydraulic pressure corresponding to the depression amount of the brake pedal 5 is transmitted from the master cylinder 7 to each brake cylinder, and a friction braking force equal to the target friction braking force is generated from the friction brake mechanism 4. Further, the ECU 11 controls the excitation current supplied to the motor generator 3 so that the target regenerative braking force can be obtained. Thereby, a regenerative braking force equal to the target regenerative braking force is generated from the motor generator 3. As a result, a braking force equal to the target braking force (target friction braking force + target regenerative braking force) acts on the hybrid car 1.

  Further, the ECU 11 determines whether or not the brake pedal 5 is urgently operated based on a detection signal input from the brake pedal stroke sensor 12, and when the urgent operation is performed, the target regenerative braking force is increased by a predetermined amount. Increase (raise). Specifically, as indicated by a two-dot chain line in FIG. 2, the target braking force for the predetermined depression amount Sth of the brake pedal 5 by the emergency operation is the target for the predetermined depression amount Sth of the brake pedal 5 by the normal operation that is not the emergency operation. The braking force is changed to a value increased by a certain additional amount (for example, the target regenerative braking force when the brake pedal 5 is depressed to MAX (maximum amount)), and the depression amount of the brake pedal 5 due to emergency operation is predetermined. In a range exceeding the stepping amount Sth, the target control is performed so that the target frictional braking force increases from the value of the target braking force after the change with respect to the predetermined stepping amount Sth as the stepping amount of the brake pedal 5 increases. The power map M1 is changed.

  FIG. 3 is a flowchart showing the flow of emergency operation determination processing.

  When the brake pedal 5 is operated by the driver, the emergency operation determination process shown in FIG.

  In the emergency operation determination process, first, based on the detection signal of the brake pedal stroke sensor 12, an operation speed that is a time change of the depression amount of the brake pedal 5 is obtained (step S1).

  Next, it is determined whether or not the operation speed of the brake pedal 5 is equal to or higher than a predetermined speed (step S2). That is, it is determined whether or not the brake pedal 5 has been quickly depressed.

  If the operation speed of the brake pedal 5 is equal to or higher than the predetermined speed due to the brake pedal 5 being quickly depressed (YES in Step S2), then the amount of depression of the brake pedal 5 is equal to or greater than the predetermined depression amount Sth. Is determined (step S3). That is, it is determined whether or not the brake pedal 5 has been depressed greatly.

  If the depression amount of the brake pedal 5 is equal to or greater than the predetermined depression amount Sth (YES in step S3), it is determined that the brake pedal 5 has been operated urgently, and the target regenerative braking force is increased by a predetermined amount (step S4). ).

  If the operation speed of the brake pedal 5 is less than the predetermined speed (NO in step S2) or if the depression amount of the brake pedal 5 is less than the predetermined depression amount Sth (NO in step S3), the brake pedal 5 is operated in an emergency Therefore, the target regenerative braking force is not increased.

  As described above, the braking of the hybrid car 1 uses both the regenerative braking force generated by the motor generator 3 and the friction braking force generated by the friction brake mechanism 4.

  When the brake pedal 5 is operated, the friction brake mechanism 4 generates a friction braking force by hydraulic pressure corresponding to the operation amount (depression amount). Further, the operation amount of the brake pedal 5 is detected by the brake pedal stroke sensor 12. Based on the output of the brake pedal stroke sensor 12, the target regenerative braking force of the motor generator 3 is set. The motor generator 3 is controlled based on the target regenerative braking force, so that the motor generator 3 generates a regenerative braking force equal to the target regenerative braking force. As a result, a friction braking force by the friction brake mechanism 4 and a regenerative braking force by the motor generator 3 act on the hybrid car 1.

  When the brake pedal 5 is operated urgently, the target regenerative braking force of the motor generator 3 is increased at a time by a predetermined amount. As a result, the regenerative braking force by the motor generator 3 increases and the braking force acting on the hybrid car 1 increases.

  The regenerative braking force of the motor generator 3 changes instantaneously by changing the excitation current supplied to the motor generator 3. Therefore, the time required from the emergency operation of the brake pedal 5 to the increase of the regenerative braking force is shorter than the time required from the emergency operation of the brake pedal 5 to the increase of the friction braking force.

  Further, based on the output of the brake pedal stroke sensor 12, it is determined whether or not the brake pedal 5 has been urgently operated. The output of the brake pedal stroke sensor 12 changes without delay with respect to the operation of the brake pedal 5. Therefore, the time from when the brake pedal 5 is urgently operated until it is determined that the urgent operation is performed is short.

  It is also possible to provide a hydraulic pressure sensor for detecting the hydraulic pressure in the master cylinder 7 and determine whether or not the brake pedal 5 is in an emergency operation based on the output of the hydraulic pressure sensor. However, in the configuration in which the presence or absence of the emergency operation of the brake pedal 5 is determined based on the output of the hydraulic sensor, there is a time lag between the emergency operation of the brake pedal 5 and the change in the hydraulic pressure in the master cylinder 7, so that the brake It takes time to determine that the pedal 5 has been operated urgently.

  Further, since the regenerative braking force is independent of the oil temperature of the friction brake mechanism 4, the response of the increase of the regenerative braking force to the emergency operation of the brake pedal 5 is not affected by the oil temperature and is stable.

  Therefore, a favorable and stable response of braking to the emergency operation of the brake pedal 5 can be exhibited.

  Unlike the configuration in which the friction braking force is increased in response to an emergency operation of the brake pedal 5, there is no need to increase the capacity of the electric negative pressure pump 8 included in the friction brake mechanism 4, so the friction brake mechanism 4 Increase in cost and size. Further, the fuel consumption is not reduced due to an increase in driving energy of the electric negative pressure pump 8.

  As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.

  For example, in the above-described embodiment, the target regenerative braking force is set, and the excitation current supplied to the motor generator 3 is controlled based on the target regenerative braking force. However, since the regenerative braking force generated by the motor generator 3 corresponds to the regenerative power generated by the motor generator 3, the target regenerative power is set based on the output of the brake pedal stroke sensor 12, and the target regenerative power is set. The excitation current supplied to the motor generator 3 may be controlled so that electric power is generated by the motor generator 3.

  In addition, various design changes can be made within the scope of matters described in the claims.

1 Hybrid car (vehicle)
3 Motor generator (regenerative braking means)
4 Friction brake mechanism (friction braking means)
5 Brake pedal 11 ECU (Target regeneration amount setting means, determination means, regeneration amount increasing means)
12 Brake pedal stroke sensor

Claims (1)

A brake pedal operated by the driver;
Friction braking means for generating a friction braking force by a hydraulic pressure corresponding to an operation amount of the brake pedal;
Regenerative braking means for generating regenerative braking force;
A brake pedal stroke sensor for detecting an operation amount of the brake pedal;
A target regeneration amount setting means for setting a target regeneration amount of the regenerative braking means based on an output of the brake pedal stroke sensor;
Determining means for determining whether or not the brake pedal has been operated urgently based on the output of the brake pedal stroke sensor;
And a regeneration amount increasing means for increasing the target regeneration amount set by the target regeneration amount setting means by a predetermined amount at a time when it is determined by the determination means that the brake pedal is urgently operated. .

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