KR20050077052A - Break controlling system of 4wd electric vehicle - Google Patents

Abstract

The present invention relates to a brake control system of a four-wheel drive electric vehicle. In particular, the brake control system combining the electric regenerative braking system and the mechanical hydraulic braking device of the conventional four-wheel drive electric vehicle determines the deceleration of the driver to determine the target braking force and By comparing the set regenerative braking force and selectively controlling the friction braking force by hydraulic pressure, it is possible to efficiently design the driving motor of the four-wheel drive electric vehicle, and to improve the braking force and braking characteristics according to the driver's deceleration will. A brake control system for an electric vehicle.

Description

Brake control system for four-wheel drive electric vehicles {BREAK CONTROLLING SYSTEM OF 4WD ELECTRIC VEHICLE}

The present invention relates to a brake control system of a four-wheel drive electric vehicle. In particular, in the brake control system combining the electric regenerative braking system and the mechanical hydraulic braking system of the existing four-wheel drive electric vehicle, the deceleration will of the driver is determined to determine the target braking force and By comparing the set regenerative braking force and selectively controlling the friction braking force by hydraulic pressure, it is possible to efficiently design the driving motor of the four-wheel drive electric vehicle, and to improve the braking force and braking characteristics according to the driver's deceleration will. A brake control system for an electric vehicle.

In general, a 4WD electric vehicle (EV), unlike an internal combustion engine, drives a drive motor with electric energy stored in a battery and rotates both front and rear wheels through a power transmission device. As a pollution-free automobile that runs, the development of low pollution-free automobiles is required, as the exhaustion of petroleum resources and serious environmental pollution problems appear as problems for all of humanity.

When the driving motor is stopped in the four-wheel drive electric vehicle (particularly, when the brake pedal is pressed), the driving motor stops the battery supplied to the driving motor and generates back electromotive force generated by the driving motor rotating by inertial force. The braking force is executed by applying to the drive motor to rotate in the reverse direction to the traveling direction.

That is, when the four-wheel drive electric vehicle depresses the brake pedal while the vehicle is in progress, the power supplied to the driving motor is cut off, and the reverse electromotive force generated from the power supply terminal of the driving motor rotated by the driving inertia force of the vehicle is returned to the driving motor again. The braking force is generated by applying the drive motor to rotate in reverse with respect to the traveling direction. This braking force is called 'regenerative braking'.

However, according to the regenerative braking device applied to the conventional four-wheel drive electric vehicle as described above, the regenerative braking amount is fixed within the proper range of the maximum output torque of the driving motor regardless of the driver's deceleration intention. There was a limit to the efficient use of energy due to the lack of active regenerative braking. In addition, since only a braking force corresponding to the predetermined regenerative braking amount is generated, a considerable time is required to brake the four-wheel drive electric vehicle.

Accordingly, in order to solve the above problems, a new brake system has been recently proposed by adding general hydraulic brake devices used in gasoline and diesel vehicles to the regenerative braking device of a four-wheel drive electric vehicle.

1 is a configuration diagram showing a brake control system of a conventional four-wheel drive electric vehicle.

As shown in Fig. 1, a conventional brake control system for a four-wheel drive electric vehicle includes a brake pedal 1; A brake booster 2 for boosting the pedaling force of the brake pedal 1; A master cylinder (3) for generating hydraulic pressure by the back force of the brake booster (2); A hydraulic line 4 which transmits the hydraulic force generated in the master cylinder 3 to each wheel FR, FL, RR, and RL; Wheel cylinders 5 installed on each of the wheels FR, FL, RR, and RL to convert hydraulic action forces supplied through the hydraulic lines 4 into mechanical forces; A hydraulic modulator 6 for adjusting the pressure by increasing or reducing the braking hydraulic pressure supplied to the wheel cylinder 5; A brake pedal detecting unit 7 detecting a pressurized state of the brake pedal 1; A drive motor (not shown) installed at each of the front wheels FR and FL and the rear wheels RR and RL of the four-wheel drive electric vehicle to supply driving power, and the drive is controlled by a control signal of a controller 9 to be described later. A regenerative braking module unit 8 for driving and regenerative braking by rotating the motor forward / reversely; It includes a control unit 9 for controlling the operation of the regenerative braking module unit 8 and the hydraulic modulator 6 in accordance with the brake detection signal provided from the brake pedal detection unit (7).

The brake system of the conventional four-wheel drive electric vehicle configured as described above, when the driver presses the brake pedal 1, doubles the pedal stepping force in the brake booster 2, and according to the action force of the brake booster 2, the master cylinder 3 To generate the hydraulic pressure, and the generated hydraulic pressure is supplied to the wheel cylinders 5 installed on the wheels FR, FL, RR, and RL along the hydraulic line 4 and the hydraulic modulator 6, Perform friction braking force.

At the same time, the brake pedal detection unit 7 detects the stroke of the brake pedal 1 and applies the signal to the control unit 9, which controls the front wheels FR and FL and the rear wheels RR and RL. Sends a predetermined control signal to the regenerative braking module unit 8 installed in each to perform the regenerative braking action and the energy regeneration action.

However, according to the brake control system of the conventional four-wheel drive electric vehicle configured as described above, since the electric regenerative braking force of the drive motor and the friction braking force by hydraulic pressure are combined and braked as they are, the braking force more than the target braking force intended by the driver There is a problem in that the deceleration faster than the deceleration of the four-wheel drive electric vehicle according to the driver's deceleration will impact the driving safety of the vehicle, such as a shock to the driver.

The present invention has been made to solve the above problems, an object of the present invention is to determine the deceleration of the driver in the brake control system that combines the electric regenerative braking device and the mechanical hydraulic braking device of the conventional four-wheel drive electric vehicle target By comparing the braking force with the preset regenerative braking force and selectively controlling the friction braking force by hydraulic pressure, the driving motor of the four-wheel drive electric vehicle can be efficiently designed, and the braking force and braking characteristics can be further improved according to the driver's deceleration will. To provide a brake control system for a four-wheel drive electric vehicle.

In order to achieve the above object, the brake control system of the four-wheel drive electric vehicle of the present invention includes an electric brake system including a brake pedal, a brake booster, a master cylinder, a front wheel / rear hydraulic line, and a front wheel / rear wheel cylinder. A brake control system for a four-wheel drive electric vehicle formed by combining a regenerative braking device for performing regenerative braking by a drive motor for supplying driving power of a vehicle, the brake control system comprising: a brake pedal detecting unit configured to sense a pressurized state of the brake pedal; An oil pressure sensing unit sensing oil pressure generated by the master cylinder; A normally open solenoid valve disposed between the master cylinder and the front wheel / rear wheel cylinders, respectively; A normal closed solenoid valve provided in communication with the front / rear side hydraulic line connecting the master cylinder and the normal open solenoid valve; Relief valves connected to the normal closed solenoid valves in parallel; It is installed between the normally open solenoid valve installed on the rear wheel side and the rear wheel cylinder, the hydraulic modulator for adjusting the braking hydraulic pressure supplied to the rear wheel cylinder and the brake detection signal provided from the brake pedal detection unit Controls the operation of the regenerative braking device, compares the target braking force detected by the hydraulic sensing unit with a predetermined regenerative braking force, and operates the normal open solenoid valve and the normal closed solenoid valve according to the result, and the hydraulic modulator. Characterized in that further comprises a control unit for controlling the operation of.

In the above-described configuration, it is preferable that the normal closed solenoid valve and the low pressure accumulator respectively provided on the downstream side of the relief valve.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. This embodiment is not intended to limit the scope of the invention, but is presented by way of example only.

2 is a functional block diagram schematically illustrating a brake control system of a four-wheel drive electric vehicle according to an embodiment of the present invention, and FIG. 3 is a brake control system of a four-wheel drive electric vehicle according to an embodiment of the present invention. It is a hydraulic system diagram for explanation.

As shown in Figures 1 and 2, the brake control system of a four-wheel drive electric vehicle according to the present invention, the brake pedal 100; A brake booster 150 for boosting the pedaling force of the brake pedal 100; A master cylinder 200 generating hydraulic pressure by the back force of the brake booster 150; A hydraulic pressure sensing unit 250 for detecting the hydraulic pressure generated in the master cylinder 200; Front / rear wheel side hydraulic lines 300a and 300b for transmitting hydraulic force generated in the master cylinder 200 to each wheel FR, FL, RR, and RL; Front wheel / rear wheel cylinders 350a and 350b installed in each of the wheels FR, FL, RR, and RL, and convert hydraulic pressure applied through the front / rear hydraulic line 300a and 300b into mechanical forces. Wow; Normally-opened (NO) solenoid valves 400a and 400b disposed between the master cylinder 200 and the front / rear wheel cylinders 350a and 350b, respectively, and are normally opened; Normally closed type (Normal-Closed, NC) which is provided in communication with each of the front / rear side hydraulic lines 300a and 300b connecting the master cylinder 200 and the normal-open solenoid valves 400a and 400b, respectively. Solenoid valves 450a and 450b; A solenoid driving unit 500 for driving the normally open solenoid valves 400a and 400b and the normal closed solenoid valves 450a and 450b; Relief valves 550a and 550b connected to the normal closed solenoid valves 450a and 450b in parallel to protect circuits due to excessive hydraulic pressure; Low-pressure accumulators (600a) (600b) installed at downstream sides of normal closed solenoid valves (450a) (450b) and relief valves (550a) (550b), respectively, for storing the inflow of brake fluid for a while; A hydraulic modulator 650 installed between the normal-open solenoid valve 400b and the rear wheel cylinder 350b to control the pressure by increasing or reducing the braking pressure supplied to the rear wheel cylinder 350b; An accelerator pedal detecting unit 700 for sensing a pressurized state of the accelerator pedal (not shown); A brake pedal detecting unit 750 detecting a pressurized state of the brake pedal 100; Regenerative braking module including a drive motor (not shown) for supplying driving power of a four-wheel drive electric vehicle, and performs driving and regenerative braking by forward / reversing the drive motor by a control signal of a controller 850 to be described later. Section 800; Controls the operation of the regenerative braking module unit 800 according to the respective detection signals provided from the accelerator pedal detection unit 700 and the brake pedal detection unit 750, and the target braking force and the target braking force detected by the hydraulic detection unit 250. The control unit 850 which controls the operation of the hydraulic modulator 650 and compares the regenerative braking force to operate the normal open solenoid valves 400a and 400b and the normal closed solenoid valves 450a and 450b according to the result. )Wow; It includes a power supply unit 900 for supplying operating power to each unit.

In the above configuration, in the brake system of the four-wheel drive electric vehicle according to the present invention, the brake pedal 100, the brake booster 150, the master cylinder 200, the hydraulic pressure sensing unit 250, the front / rear side hydraulic line 300a 300b, the front / rear wheel cylinders 350a, 350b, and the hydraulic modulator 650 are generally well known, and thus detailed description thereof will be omitted (for example, Korean Patent Publication No. 2002-0073792, Korean Patent Publication No. 2002-0044334, etc.).

Normally open solenoid valves 400a and 400b are not shown but are generally configured so that the plunger opens the orifice by the elastic force of the spring when electricity is not applied to the solenoid. The open state is maintained, and when a current is applied to the solenoid, the plunger is advanced to close the orifice flow path. The normal closed solenoid valves 450a and 450b operate in the opposite direction.

The normal open solenoid valves 400a and 400b and the normal closed solenoid valves 450a and 450b are electrically connected to the control unit 850 through the solenoid driving unit 500 and are output from the control unit 850. It is operated by the control signal of.

Although not shown, relief valves 550a and 550b are generally used when the valve body closes the opening of the valve seat due to the elastic bearing force of the coil spring, while the upstream side becomes very high pressure compared to the downstream side. The valve body is displaced in the valve opening direction in response to the elastic bearing force of the coil spring, and the opening of the valve seat is opened to flow the fluid.

Although not shown, the low pressure accumulators 600a and 600b generally include a chamber, a piston installed in the chamber so as to reciprocate, and a spring for elastically biasing the piston. do.

The low pressure accumulators 600a and 600b configured as described above are relief valves 550a and 550b as they temporarily store brake fluid discharged from normal-closed solenoid valves 450a and 450b and relief valves 550a and 550b. It is to relieve excessive hydraulic burden of).

Although not shown, the hydraulic modulator 650 is generally configured to include an oil pump, a suction valve, a discharge valve, an accumulator, a damper, and the like to increase pressure, reduce pressure, and maintain pressure of the rear wheel cylinder 350b of the brake. Each state is controlled.

The accelerator pedal detecting unit 700 and the brake pedal detecting unit 750 may be respectively formed in position of the accelerator pedal and the brake pedal 100 and formed of a position sensor for detecting a stroke. The position sensor may include a variable resistor ( It is preferably made of a potentiometer, and converts the change of the electrical resistance value into a voltage according to the stroke of the accelerator pedal and the brake pedal 100, and transmits the electrical signal to the controller 850.

Although not shown, the regenerative braking module unit 800 generally drives a four-wheel drive electric vehicle according to a predetermined control signal, that is, a control signal of the controller 850, and generates a back EMF when braking. ; A driving battery which supplies power to the driving motor by a control signal of a controller 850; It comprises a motor control unit for controlling the operation of the drive motor and the drive battery by a control signal of the control unit 850.

The regenerative braking module unit 800 configured as described above performs the regenerative braking by generating a rotational resistance while performing energy regeneration with rotational force according to the control signal of the controller 850.

Here, the regenerative braking refers to braking while absorbing the inertial force of the vehicle to go straight to the drive motor in the four-wheel drive electric vehicle, the drive motor is stored in the drive battery because the counter electromotive force is generated Can be.

The controller 850 may be provided separately from the electronic control unit (ECU) or the electronic control unit (ECU) that is responsible for the overall control of the four-wheel drive electric vehicle.

In addition, the controller 850 receives the brake detection signal output from the brake pedal detection unit 750 during braking of the four-wheel drive electric vehicle, converts it into a predetermined regenerative braking force, and converts the regenerative braking signal corresponding thereto into the regenerative braking module unit. It passes to the motor control unit of (800).

The power supply unit 900 is provided inside the four-wheel drive electric vehicle, it is preferable to use a conventional battery power to operate the electric, electronic components, but is not limited to this, driving the battery or regenerative control module unit 800 provided separately. You can also use battery power.

Hereinafter, the operation of the brake control system of the four-wheel drive electric vehicle of the present invention having the above-described configuration will be described in detail.

4A and 4B are diagrams illustrating an operating state of a brake control system of a four-wheel drive electric vehicle according to an exemplary embodiment of the present invention. First, the controller 850 performs the main operation.

4A is a hydraulic flow chart for explaining a case in which the target braking force detected by the hydraulic pressure sensing unit of the present invention is smaller than the predetermined regenerative braking force.

As shown in FIG. 4A, first, when the driver presses the brake pedal 100 to decelerate or stop the vehicle, the controller 850 receives a brake detection signal from the brake pedal detection unit 750 and sets a predetermined regenerative braking force. The regenerative braking signal corresponding thereto is transferred to the motor control unit of the regenerative braking module unit 800.

At the same time, receiving the hydraulic pressure detection signal from the hydraulic pressure sensing unit 250 calculates the target braking force, and compares the calculated target braking force with the regenerative braking force, when the target braking force is smaller than the regenerative braking force, the regenerative of the drive motor is performed. It is judged that the braking force alone can adequately brake the brakes of the four-wheel drive electric vehicle, so that friction braking by hydraulic pressure is not performed.

At this time, the control unit 850 transmits a driving control signal to the solenoid driving unit 500 to operate the normal open solenoid valves 400a and 400b and the normal closed solenoid valves 450a and 450b.

That is, when the normally open solenoid valves 400a and 400b are blocked by the drive control signal of the controller 850, the hydraulic pressure generated in the master cylinder 200 does not flow into the front / rear wheel cylinders 350a and 350b. At the same time, the friction braking force is not generated by the hydraulic pressure, and at the same time, the normal closed solenoid valves 450a and 450b are opened, and the hydraulic pressure generated in the master cylinder 200 passes through the normal closed solenoid valves 450a and 450b. It is delivered to the relief valves 550a and 550b to protect the circuit due to excessive hydraulic pressure rise, and temporarily discharges the brake fluid discharged from the normal closed solenoid valves 450a and 450b and the relief valves 550a and 550b. Relieving excessive hydraulic burden of the relief valves 550a and 550b as they are stored.

4B is a hydraulic flow chart for explaining a case in which the target braking force detected by the hydraulic pressure sensing unit of the present invention is larger than the predetermined regenerative braking force.

As shown in FIG. 4B, when the driver presses the brake pedal 100 to decelerate or stop the vehicle, the control unit 850 receives the brake detection signal from the brake pedal detection unit 750 and converts it into a predetermined regenerative braking force. The regenerative braking signal corresponding thereto is transmitted to the motor control unit of the regenerative braking module unit 800.

At the same time, receiving the hydraulic pressure detection signal from the hydraulic pressure sensing unit 250 calculates the target braking force, and compares the calculated target braking force with the regenerative braking force, when the target braking force is greater than the regenerative braking force, the regenerative of the drive motor is performed. It is judged that the braking force alone cannot sufficiently handle the brake braking of the electric vehicle, so that the friction braking force by hydraulic pressure is performed together.

At this time, the control unit 850 does not transmit a drive control signal to the solenoid driving unit 500, so that the normal open solenoid valves 400a and 400b and the normal closed solenoid valves 450a and 450b do not operate. That is, the normally open solenoid valves 400a and 400b remain open, and the normally closed solenoid valves 450a and 450b remain blocked.

Accordingly, the hydraulic pressure generated in the master cylinder 200 is passed through the front / rear side hydraulic lines 300a and 300b through the normally open solenoid valves 400a and 400b to the front / rear wheel cylinders 350a and 350b. The friction braking force is generated by the hydraulic pressure.

Here, the friction braking force refers to the target braking force remaining after subtracting the regenerative braking force from the target braking force.

On the other hand, in general, various electric power to the front wheel (FR, FL) side of a four-wheel drive electric vehicle. Since the electronic parts and mechanical parts are provided so that the load is more concentrated than the rear wheels (RR, RL), the braking force should be adjusted in consideration of the loads of the front wheels (FR, FL) and the lower wheels (RR, RL).

Therefore, the control unit 850 transmits a predetermined control signal to the hydraulic modulator 650, so that the hydraulic pressure generated in the master cylinder 200 is adjusted by the hydraulic modulator 650 through the rear wheel side hydraulic line 300b, and thus the rear wheel. It is provided to the side wheel cylinder 350b.

While a preferred embodiment of the brake control system for a four-wheel drive electric vehicle according to the present invention has been described above, the present invention is not limited thereto, but the scope of the claims and the detailed description of the invention and the accompanying drawings are various. It is possible to carry out modifications and this also belongs to the present invention.

According to the brake control system of the four-wheel drive electric vehicle according to the present invention as described above, the deceleration of the driver in the brake control system that combines the electric regenerative braking system and the mechanical hydraulic braking system of the conventional four-wheel drive electric vehicle to determine the target By comparing the braking force with the preset regenerative braking force and selectively controlling the friction braking force by hydraulic pressure, the driving motor of the four-wheel drive electric vehicle can be efficiently designed, and the braking force and braking characteristics can be further improved according to the driver's deceleration will. There is an advantage to that.

1 is a configuration diagram showing a brake control system of a conventional four-wheel drive electric vehicle,

2 is a functional block diagram schematically illustrating a brake control system of a four-wheel drive electric vehicle according to an embodiment of the present invention;

3 is a hydraulic system diagram for explaining a brake control system of a four-wheel drive electric vehicle according to an embodiment of the present invention;

4A and 4B are views showing an operating state of a brake control system of a four-wheel drive electric vehicle according to an embodiment of the present invention, and FIG. 4A is a target braking force detected by a hydraulic sensing unit of the present invention than a predetermined regenerative braking force. 4B is a hydraulic flow chart for explaining a small case, and FIG. 4B is a hydraulic flow chart for explaining a case in which the target braking force detected by the hydraulic sensing unit of the present invention is larger than a predetermined regenerative braking force.

      *** Explanation of symbols on main parts of drawing ***

100: brake pedal, 150: brake booster,

200: master cylinder, 250: hydraulic pressure sensing unit,

300a, 300b: front / rear hydraulic line,

350a, 350b: front / rear wheel cylinders,

400a, 400b: Normally open solenoid valve,

450a, 450b: Normally closed solenoid valve,

500: solenoid drive unit, 550a, 550b: relief valve,

600a, 600b: Low pressure accumulator, 650: Hydraulic modulator

700: accelerator pedal detection unit, 750: brake pedal detection unit,

800: regenerative braking module unit, 850: control unit,

900 power supply unit

Claims (2)

A regenerative braking device that performs regenerative braking by a hydraulic braking device including a brake pedal, a brake booster, a master cylinder, a front / rear hydraulic line and a front / rear wheel cylinder, and a driving motor that supplies driving power for an electric vehicle. In the brake control system of the four-wheel drive electric vehicle made by combining, A brake pedal detecting unit detecting a pressurized state of the brake pedal; An oil pressure sensing unit sensing oil pressure generated by the master cylinder; A normally open solenoid valve disposed between the master cylinder and the front wheel / rear wheel cylinders, respectively; A normal closed solenoid valve provided in communication with the front / rear side hydraulic line connecting the master cylinder and the normal open solenoid valve; Relief valves connected to the normal closed solenoid valves in parallel; A hydraulic modulator installed between the normally-open solenoid valve installed on the rear wheel side and the rear wheel cylinder, for adjusting the braking hydraulic pressure supplied to the rear wheel cylinder; Controlling the operation of the regenerative braking device according to the brake detection signal provided from the brake pedal detecting unit, comparing the target braking force detected by the hydraulic sensing unit with a predetermined regenerative braking force, and according to the result, the normal-open solenoid valve and And a control unit for operating the normal closed solenoid valve and controlling the operation of the hydraulic modulator. The brake control system according to claim 1, further comprising a low pressure accumulator disposed on the downstream side of the normal closed solenoid valve and the relief valve.