KR101937461B1 - Electronic brake system in a vehicle and method thereof - Google Patents

Abstract

The present invention provides an electronic brake system and a control method thereof.
An electronic brake system according to an embodiment of the present invention is an electronic brake system in which a piston is installed so as to move forward and backward so as to be able to press a disk with two friction pads. The electronic brake system includes an input part for acquiring a pedal pressure applied by a driver, When the pedal restraint force is not applied during a predetermined time interval from the point of time when the roll-back is performed, the required amount of increase in the amount of liquid is calculated, and the calculated required amount of increase in liquid amount is added to the required amount of liquid amount based on the required amount- And a drive unit for securing a braking pressure based on the estimated under-estimation control unit and the estimated desired liquid-level hydraulic pressure.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electronic brake system for a vehicle,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to an electronic brake system for a vehicle and a control method thereof, and more particularly, to an electronic brake system for determining a hydraulic pressure amount considering a distance between brake pads and a control method thereof.

The vehicle is essentially equipped with a brake system for braking. Recently, various types of systems have been proposed to obtain a more powerful and stable braking force.

Examples of the brake system include an anti-lock brake system (ABS) that prevents slippage of the wheel during braking, a brake traction control system (BTCS: Brake) that prevents slippage of the drive wheels And an electronic stability control system (ESC) that stably maintains the running state of the vehicle by controlling the brake hydraulic pressure by combining an anti-lock brake system and traction control.

Generally, an electronic brake system includes a hydraulic pressure supply device that receives an electric signal of a driver's braking will from a pedal displacement sensor that senses displacement of a brake pedal when the driver depresses the brake pedal, and supplies pressure to the wheel cylinder.

An electronic brake system equipped with such a hydraulic pressure supply device is disclosed in European Patent EP 2 520 473. According to the disclosed document, the hydraulic pressure supply device is configured to operate the motor in accordance with the power of the brake pedal to generate the braking pressure. At this time, the braking pressure is generated by converting the rotational force of the motor into a linear motion and pressing the piston.

In particular, the braking pressure was estimated by using the required fluid amount curve (pressure table according to the flow rate) determined according to vehicle specifications.

Separately, the brake device of the vehicle's electronic brake system has a parking brake, typically a hand brake or a side brake, which keeps the vehicle stationary. The parking brake is operated when the driver operates the parking lever provided on the driver's seat inside the vehicle.

When the driver pulls the parking lever and pulls the cable connected to it, the rear wheel brake assembly connected to the cable is operated to secure the braking force. On the contrary, if the cable lever is released, the braking force is released.

In addition, in recent years, an electronic parking brake (EPB) system for electronically controlling the driving of the parking brake is used, and is mounted on a normal disk brake to perform a parking brake function.

The electronic parking brake system allows the parking brake to be automatically operated or released in accordance with a simple switch operation or control judgment of the electronic control unit managing the entire control even if the driver does not operate the parking brake manually.

The electronic parking brake system includes an actuator having a motor for generating a braking force and an electronic control unit (ECU) for driving the actuator. The ECU consists of a control unit, several sensor interfaces, a motor drive and a communication module. The electronic control unit ECU drives the actuator according to the operation state of the switch to apply or release the electronic parking brake system.

However, in the case where the parking brake is actuated, depending on the degree of close contact of the brake pads included in the brake assembly, the braking pressure required to determine the braking pressure according to the required fluid volume curve in the electronic brake system actually generates necessary braking pressure and error, There is a problem that accuracy of pressure calculation is lowered.

The embodiment of the present invention attempts to minimize the error caused by the inability to consider the distance between the brake pads when estimating the wheel pressure according to the required fluid amount curve in the electronic brake system.

According to an aspect of the present invention, there is provided an electronic brake system in which a piston is installed so as to be movable forward and backward so as to be able to press a disk with two friction pads, the system comprising: an input part for obtaining a pedal pressure applied by a driver; -back), when the pedal restraint force is not applied during a predetermined time interval, the required amount of increase in the amount of liquid is calculated, and the calculated required amount of increase in the amount of liquid is added to the required amount of liquid amount in accordance with the required amount of liquid curvature, ; And a driving unit for securing a braking pressure based on the estimated desired fluid amount fluid pressure.

In addition, the controller may estimate the desired fluid volume pressure according to the required fluid volume curve when the pedaling force is applied before the predetermined time interval from the time when the piston is moved backward.

Further, the required amount of increase in the liquid amount can be calculated based on the product of the area of the friction pad and the estimated clearance.

Further, the clearance may be estimated on the basis of the elapsed time from the point in time when the piston is retracted.

According to another aspect of the present invention, there is provided an electronic brake system in which a piston is movably installed so as to be able to compress a disc with two friction pads, comprising: obtaining a pedal pressure applied by a driver; Calculating a required amount of increase in the amount of liquid required when the pedal restraint force is not applied for a predetermined time interval from a point in time when the piston rolls back; ; And securing a braking pressure on the basis of the summed desired fluid volume hydraulic pressure.

The method may further include the step of calculating a desired liquid amount fluid pressure according to a required fluid amount curve when the pedaling force is applied before the predetermined time interval from the time when the piston is moved back.

Further, the required amount of increase in the liquid amount can be calculated based on the product of the area of the friction pad and the estimated clearance.

Further, the clearance may be estimated on the basis of the elapsed time from the point in time when the piston is retracted.

The embodiment of the present invention can reduce an error that occurs due to the inability to consider the clearance between the brake pads when estimating the wheel pressure according to the required fluid amount curve in the electronic brake system.

1 is a cross-sectional view of a wheel brake that may be used in accordance with one embodiment.
2 is a hydraulic circuit diagram showing the state of the electromagnetic brake system according to the embodiment at the time of non-braking.
3 is an internal block diagram of an electronic braking system according to an embodiment of the present invention.
4 is a graph showing a required liquid amount curve according to an embodiment.
5 is a flowchart illustrating a method of estimating a hydraulic pressure in an electronic brake system according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to fully convey the spirit of the present invention to a person having ordinary skill in the art to which the present invention belongs. The present invention is not limited to the embodiments shown herein but may be embodied in other forms. For the sake of clarity, the drawings are not drawn to scale, and the size of the elements may be slightly exaggerated to facilitate understanding.

The electronic parking brake system is classified into a cable puller type and a motor-on-caliper type according to its operation mode. Even if the driver does not operate the parking brake manually, If the vehicle is likely to be pushed backward at the start of the hill, it automatically operates to keep the car parked or stopped.

Hereinafter, an electronic parking brake system of a motor-on-caliper type will be described as an example for convenience of explanation.

1 is a schematic configuration diagram of an electronic parking brake apparatus according to an embodiment of the present invention.

1, an EPB actuator 30 for generating braking force by operating disc brakes 10 and 20 provided on a vehicle wheel, an electronic control unit (ECU) 30 for controlling the operation of the EPB actuator 30, ) ≪ / RTI >

The disc brakes 10 and 20 include a carrier 10 coupled to a vehicle body and having a pair of friction pads 11 spaced apart from each other by a predetermined distance, And a caliper housing 20 provided with a cylinder portion 20a in which the piston 21 can be moved forward and backward so as to press the piston 21 against the disk D and a finger 20b on the other side.

In particular, the clearance between the disc brakes 10, 20 and the disc D is called a clearance. Specifically, when the piston 21 moves forward and backward and the clearance changes, when the piston 21 advances within a predetermined time from when the piston 21 is moved backward by the roll back, the clearance (interval = 0 ), And a clearance is generated when a predetermined time elapses.

At this time, when the hydraulic pressure is estimated by the ECU in the electronic brake system 1 without considering the generated clearance, the driver may not be able to deliver the desired braking force.

The electronic control unit 40 of the electronic brake system 1 shown in Fig. 3 estimates the hydraulic pressure delivered to each wheel through the internal circuit diagram of the electronic braking system shown in Fig. 2 when a clearance is generated .

Therefore, an internal circuit diagram for transmitting hydraulic pressure to each wheel will be described in detail.

2 is a hydraulic circuit diagram showing the state of the electromagnetic brake system according to the embodiment at the time of non-braking.

2, the electronic brake system 1 typically includes a master cylinder 20 for generating hydraulic pressure, a reservoir 30 coupled to the top of the master cylinder 20 for storing oil, a brake pedal (not shown) An input rod 12 which pressurizes the master cylinder 20 in accordance with the pressing force of the brake pedal 10 and a wheel cylinder 40 which transmits hydraulic pressure to brake the wheels RR, RL, FR and FL, A pedal displacement sensor 11 for detecting the displacement of the brake pedal 10 and a simulation device 50 for providing a reaction force in response to the power of the brake pedal 10.

The master cylinder 20 may be configured to include at least one chamber to generate hydraulic pressure. In one example, the master cylinder 20 is configured to have two chambers, each chamber being provided with a first piston 21a and a second piston 22a, the first piston 21a being connected to the input rod 12 ).

On the other hand, the master cylinder 20 has two chambers to ensure safety in case of failure. For example, one of the two chambers may be connected to the right front wheel FR and the left rear wheel RL of the vehicle, and the other chamber may be connected to the left front wheel FL and the right rear wheel RR. Alternatively, one of the two chambers may be connected to the two front wheels FR and FL and the other chamber to the two rear wheels RR and RL. Thus, by independently configuring the two chambers, it is possible to braking the vehicle even if one of the chambers fails.

To this end, the master cylinder 20 may be formed with first and second hydraulic ports 24a and 24b, respectively, through which fluid pressure is discharged from the two chambers.

A first spring 21b is provided between the first piston 21a and the second piston 22a of the master cylinder 20 and a second spring 21b is provided between the end of the master cylinder 20 and the second piston 22a. 2 spring 22b may be provided.

The first spring 21b and the second spring 22b are respectively provided in the two chambers and as the displacement of the brake pedal 10 changes, the first piston 21a and the second piston 22a are compressed, The elastic force is stored in the spring 21b and the second spring 22b. When the pushing force of the first piston 21a becomes smaller than the elastic force, the first and second pistons 21a and 22a are returned to the original state by using the elastic force stored in the first spring 21b and the second spring 22b .

On the other hand, the input rod 12 for pressing the first piston 21a of the master cylinder 20 can be brought into contact with the first piston 21a in close contact with each other. That is, a gap between the master cylinder 20 and the input rod 12 may not exist. Therefore, when the brake pedal 10 is depressed, the master cylinder 20 can be directly pressed without a pedal invalid stroke section.

The simulation apparatus 50 may be connected to a first backup passage 251 to be described later to provide a reaction force according to the pressing force of the brake pedal 10. The reaction force is provided as much as the driver's compensation is compensated for, so that the driver can finely adjust the braking force as intended.

2, an electronic brake system 1 according to an embodiment of the present invention receives an electric signal of a driver's braking will from a pedal displacement sensor 1100 that senses displacement of the brake pedal 1000, And a first and second hydraulic circuits 201 and 202 for controlling the flow of hydraulic pressure to the wheel cylinders 40 provided in the two wheels RR, RL, FR and FL, respectively, A first cut valve (not shown) provided in a first backup passage 251 for connecting the first hydraulic pressure port 24a and the first hydraulic circuit 201 and controlling the flow of the hydraulic pressure, A second cut valve 262 provided on a second backup passage 252 for connecting the second hydraulic pressure port 24b and the second hydraulic circuit 202 to control the flow of the hydraulic pressure, And controls the hydraulic pressure supply device 100 and the valves 54, 221, 222, 223, 224, 231, 232, 241, 242, 261, and 262 based on the displacement information And an electronic control unit (ECU, 40 in Fig. 3). At this time, the electronic control unit 40 estimates the hydraulic pressure in consideration of the amount of clearance existing between the brake pads.

The hydraulic pressure supply device 100 includes a pressure providing unit 110 for supplying oil pressure to the wheel cylinder 40, a motor 120 for generating a rotational force by an electrical signal of the pedal displacement sensor 1100, And a power converting unit 130 converting the rotational motion of the motor 120 into a linear motion and transmitting the linear motion to the pressure providing unit 110.

The pressure providing unit 110 includes a pressure chamber 111 in which a predetermined space is formed for storing and storing oil, a hydraulic piston 112 provided in the pressure chamber 111, a hydraulic piston 112 and a pressure chamber 111 And a hydraulic spring 122 for elastically supporting the hydraulic piston 112. As shown in FIG.

The pressure chamber 111 is connected to the reservoir 30 by the oil passage 114 and can receive and store the oil from the reservoir 30. The oil passage 114 may communicate with the first communication hole 111a formed at the inlet side of the pressure chamber 111. [ For example, the first communication hole 111a may be formed at the inlet side of the pressure chamber 111 where pressure is generated when the hydraulic piston 112 advances.

The oil passage 114 may be provided with a check valve 115 for preventing the pressure of the pressure chamber 111 from flowing backward. The check valve 115 prevents the oil in the pressure chamber 111 from being lost to the reservoir 30 through the oil passage 114 when the hydraulic piston 112 is advanced and prevents the oil pressure piston 112 from returning to the reservoir 30 is sucked and stored at the inlet side of the pressure chamber 111. [

The hydraulic pressure supply device 100 can also be configured to prevent the pressure in the pressure chamber 111 from being released to the atmospheric pressure in the process of returning the hydraulic piston 112 and absorbing the hydraulic pressure in the pressure chamber 111 .

A second communication hole 111b is formed in the pressure chamber 111 and a second communication hole 111b and an oil passage 114 are formed between the outlet side of the pressure chamber 111 and the oil passage 114. [ A connecting flow passage 116 is formed. At this time, the second communication hole 111b is located at the initial position of the hydraulic piston 112 (i.e., when the hydraulic piston 112 retracts to the outlet side of the pressure chamber 111 and the pressure in the pressure chamber 111 is released) (I.e., the position of the hydraulic piston 112). Accordingly, the hydraulic piston 112 is returned, and the outlet side of the compression chamber 111 is automatically connected to the reservoir 30 through the connection passage 116, so that the pressure can be returned to the atmospheric pressure.

The motor 120 is a device that generates a rotational force by a signal output from the electronic control unit 40, and can generate a rotational force in a forward direction or a reverse direction. The rotational angular velocity and rotational angle of the motor 120 can be precisely controlled. At this time, the electronic braking system 1 can also be operated without malfunctions by appropriately controlling the motor 120. [

Hereinafter, the electronic control unit 40 will be described to explain a method of estimating the hydraulic pressure when a clearance between brake pads is generated. 3 is an internal block diagram of an electronic brake system according to an embodiment of the present invention, and FIG. 4 is a graph illustrating a required fluid amount curve according to an embodiment of the present invention.

First, an electronic brake system 1 according to an embodiment includes an input unit 41 for receiving a clearance between brake pads, an electronic control unit 40 for estimating a hydraulic pressure increase amount in consideration of a required fluid amount characteristic curve, And a drive unit 45 for providing a hydraulic pressure based on the hydraulic pressure.

The input unit 41 acquires clearance information that is an interval between brake pads in the wheel brake. Specifically, the piston 21 of FIG. 1 performs a forward / backward movement to change the clearance. Since the piston 21 is moved backward by a predetermined amount of time (A [sec] There is no clearance (interval = 0) when the control unit 21 advances, and a clearance is generated when a predetermined time elapses.

That is, when a clearance is generated, the input unit 41 transmits a clearance value to the electronic control unit 40 in order to calculate the braking hydraulic pressure considering the degree of the clearance.

The electronic control unit 40 generally controls the electronic brake system 1. When it is determined that the clearance has occurred in the determination unit 42 and the determination unit 42 that determine whether or not a clearance has occurred, And an estimating unit 43 for estimating.

As shown in the internal circuit diagram of Fig. 2, the electronic brake system 1 is configured such that the hydraulic pressure supply apparatus 100 operates the motor according to the power of the brake pedal 1000 to generate the braking pressure. In this case, the braking pressure is generated by converting the rotational force of the motor 120 into a linear motion and pressing the piston 110. When the hydraulic pressure is generated by the motor, the position of the piston in the chamber mounted on the wheel The braking pressure can be controlled by regulating the liquid amount using the required liquid amount characteristic which is a constant relationship between the braking pressure generated in the caliper and the liquid pressure introduced into the caliper.

Specifically, the required fluid amount curve refers to calculating the change amount of the fluid pressure generated in accordance with the volume change amount of the fluid amount flowing into the caliper, as shown in Fig. 4, and calculating the braking pressure generated in the caliper.

However, when a clearance is generated, the braking fluid must be introduced into the space of the clearance and the area of the brake pad so that the braking pressure as much as the driver intends can be generated.

Thus, the determination unit 42 in the electronic control unit 40 determines whether a clearance has occurred or not. More specifically, when the piston 21 advances within a predetermined time (A [sec]) from the time point when the piston 21 (Fig. 1) in the brake apparatus is rolled back and then moved backward, Interval = 0), and it is determined that a clearance has occurred when a predetermined time elapses.

Therefore, if a certain period of time has elapsed since the piston 21 was retracted, a clearance was estimated to be a clearance. It is possible to calculate the clearance value in consideration of the backward movement of the piston 21 and the elapsed time from the time when the piston 21 is backward.

Next, the estimating unit 43 estimates the required amount of liquid increase. Specifically, as shown in FIG. 4, when the determination unit 42 determines that the clearance has occurred before generating the braking pressure in accordance with the change amount of the hydraulic pressure according to the required fluid amount curve, the estimation unit 43 considers the clearance To determine the required amount of liquid increase.

That is, the estimating section 43 calculates the product of the area of the brake pad 11 provided for each vehicle in the clearance in order to estimate the required amount of liquid increase?. Thereafter, the electronic control unit 40 calculates the required braking pressure by adding the required amount a of increase in the amount of increase? Estimated by the estimating unit 43 to the volume of the amount of liquid flowing into the caliper. That is, as shown in FIG. 4, the fluid pressure P is calculated in the case of the liquid amount a0 flowing into the first caliper. However, when the clearance is generated, the liquid amount flowing into the caliper is added to the required liquid amount increase amount? a1), the same liquid pressure P can be ensured.

Thereafter, the electronic control unit 40 operates the various units included in the internal circuit diagram to calculate the braking pressure corresponding to the braking pressure calculated in the driving unit 45. [

The configuration for determining the increase in hydraulic pressure when the clearance is generated in the electronic brake system 1 and the operation of each configuration have been described above.

Hereinafter, an operation method of the electronic brake system 1 according to the present invention will be described.

First, the electronic brake system 1 according to the present invention senses the driver's brake braking intent (S10). Specifically, the electronic brake system 1 can advance the piston 31 of Fig. 1 and press the brake pad 11 against the disc D upon sensing the brake braking force of the driver.

When the braking force is generated within a predetermined elapsed time A [sec] (NO in S30), the electronic control unit 40 determines that a clearance has occurred, The liquid amount increase amount is calculated (S40). Specifically, the estimating unit 43 in the electronic control unit 40 calculates the product of the area of the brake pad 11 provided for each vehicle in the clearance in order to estimate the required amount of liquid increase?.

Thereafter, the electronic control unit 40 adds the required amount of increase in the amount [alpha] estimated by the estimating unit 43 to the volume change amount of the amount of the liquid introduced into the caliper, and outputs the calculated driving amount to the driving unit 45, As shown in Fig.

If the braking force is generated after the predetermined elapsed time A [sec] (Yes in S30), the electronic control unit 40 determines that no clearance has occurred And generates a hydraulic pressure according to the required liquid amount characteristic curve (S60).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the embodiments set forth herein; It will be understood that various modifications may be made without departing from the spirit and scope of the invention.

1: Electronic Brake System

Claims (8)

1. An electronic brake system in which a piston is movably installed so as to be able to press a disk with two friction pads,
An input unit for acquiring a pedal pressure applied by the driver;
And when the pedal restraint force is not applied during a predetermined time interval from the time point when the piston is back-rolled, calculates a required amount of increase in the amount of liquid increase and adds the calculated amount of increase in required amount of the required amount to the required amount of liquid amount And estimates the required liquid volume liquid pressure,
A controller for estimating a required fluid volume pressure according to the required fluid amount curve when the piston is applied to the pedal pressure force before the predetermined time interval from the time point when the piston is moved backward; And
And a driving unit for securing a braking pressure based on the estimated desired fluid amount fluid pressure.
delete The method according to claim 1,
Wherein the required amount of increase in liquid amount is calculated based on a product of an area of the friction pad and an estimated clearance. The method of claim 3,
Wherein the clearance is estimated based on an elapsed time from a point in time when the piston is retracted. 1. A control method for an electronic brake system in which a piston is movably installed so as to be able to press a disc with two friction pads,
Obtaining a pedal pressure applied by the driver;
Wherein when the pedal restraint force is not applied during a predetermined time interval from the point of time when the piston rolls back, a required amount of increase in the amount of liquid is calculated, and before the preset time interval from the time point when the piston is moved back, Calculating a hydraulic pressure according to a required fluid amount curve when a pressing force is applied;
Adding the calculated required amount of increase in liquid amount to the required liquid amount based on the required liquid amount curve; And
And securing a braking pressure on the basis of the summed desired fluid volume hydraulic pressure.
delete 6. The method of claim 5,
Wherein the required amount of increase in liquid amount is calculated based on a product of an area of the friction pad and an estimated clearance. 8. The method of claim 7,
Wherein the clearance is estimated on the basis of an elapsed time from a time point when the piston is retracted.

Images