KR20150057647A - Initializing method for position of piston in electric booster - Google Patents

Abstract

The present invention relates to a method for initializing a position of a piston of an electric booster rapidly returning a position of a piston pressurizing brake oil to the initial position to always enable a driver to perform a demand braking force. According to the present invention, the method for initializing a position of a piston of an electric booster includes: a pedal operation determination step (S110) determining whether or not a brake pedal (11) operates in an electric booster installed in a braking device of a vehicle; a driver acceleration willingness determination step (S120) confirming acceleration willingness of the driver when it is determined that the brake pedal (11) operates in the pedal operation determination step (S110); and a piston position rapid initialization step (S130) initializing the position of the piston (13) from the current position in the electric booster when it is determined that the driver has willingness to accelerate the vehicle.

Description

[0001] The present invention relates to a method of initializing a piston position of an electric booster,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electric booster for amplifying a driving force of a driver in a braking device of a vehicle and transmitting the same to a brake. More specifically, The present invention relates to a method of initializing a piston position of an electric booster.

The braking device is equipped with a booster which, when the driver depresses the brake pedal and tries to brake, amplifies the driver's driving force to exert the braking force.

The booster pressurizes the hydraulic pressure to be transmitted to each wheel of the vehicle in various manners, and the electric booster presses the brake oil using a motor.

That is, the motor-driven booster is driven by the motor to advance the piston, thereby pressing the brake oil so that the braking force can be exerted.

Here, when moving the piston to press brake oil, one of the main input factors is the position of the piston. In order to know the position of the piston, a sensor capable of sensing the absolute position of the piston can be used. However, in this case, there are disadvantages in terms of cost and actuator configuration.

Therefore, in reality, the position of the origin of the piston is arbitrarily determined, and the position of the piston is grasped by accumulating the amount of change from that position. As described above, the method of determining the position of the piston by a relative method can improve the reliability by accurately knowing the origin position and the position change amount of the piston. The relative origin position of the piston is determined by a mechanical restoring force (reaction force). That is, when the driving of the motor is stopped after the brake oil is pressurized, the pressure generated in the master cylinder of the booster and the return spring are mechanically And is located near the origin. When the electric booster wakes up at this time, the position of the piston is recognized as the relative origin position of the piston.

As shown in FIG. 1, the ECU for controlling the electric booster recognizes that the electric booster is started when the door is opened, the vehicle is started, or the driver presses the brake pedal, (S210).

If it is determined that the booster is operated by the opening or the starting key of the door, the position demand value P of the current piston is increased to a predetermined time t1 by a certain slope DELTA x1 and then the predetermined slope DELTA x2 To a predetermined position (S220). In the normal case of operating in the above-described pattern, the piston advances in the direction to pressurize the brake oil, and then moves backward to reduce the pressure of the brake oil. During the backward movement, the piston contacts the end of the master cylinder, Stop.

Determining a motor normalcy for operating the electric booster, and (S230), if it is determined that the motor is continued for a tripped state a certain period of time and operating normally the piston at the end of the master cylinder (S240), the position (P ₀ ) Is taken as the origin, and the positions of the pistons measured during that time are all ignored, and the positions of the pistons are initialized (S250).

However, if it is not determined that the booster is operated by the opening or starting key of the door, that is, when the driver depresses the brake pedal, the piston initialization does not proceed and the piston initialization logic is stopped.

As described above, if the initialization is not performed in the electric booster, the ECU operates the electric booster with the current position of the piston as a reference point, so that the driver can not accurately generate the desired braking force. That is, the driver's required braking force is determined according to the movement amount of the piston by the operation of the electric booster. Since the initialization of the piston is not performed, the movement amount of the piston can not be accurately controlled.

In addition, since it is difficult for the driver to exert the required braking force, there is a possibility that a risk of malfunction may occur.

In addition, the operation of the braking device is also affected by the environment such as the inclination and the temperature. Since the control is performed based on the current position of the piston in the state where the initialization of the piston is not performed, the driver can feel a different feeling In addition, noise may occur.

On the other hand, the following prior art document relates to a 'master cylinder for a vehicle', and discloses a master cylinder for a vehicle that shortens an initial stroke to improve responsiveness.

KR 10-2008-0023559 A

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a brake control apparatus and a brake control method for a braking system that, when a driver operates a braking device by pressing a brake pedal, The present invention provides a method for initializing a piston position of an electric booster.

According to another aspect of the present invention, there is provided a method of initializing a piston position of an electric booster, the method including: determining whether a brake pedal is operated in an electric booster installed in a braking device of the vehicle; Determining whether the brake pedal is operated; determining whether the driver intends to accelerate the vehicle; determining whether the driver is to accelerate the vehicle; The piston position rapid initialization step.

Wherein the driver acceleration will determination step includes a step of determining that the pressure of the master cylinder is lower than the set pressure of the quick return master cylinder and the brake light switch is in the OFF state and the speed of the vehicle exceeds the set rapid initialization vehicle speed lower limit, When the acceleration of the vehicle exceeds the set rapid initialization vehicle speed increase amount and the operation amount of the accelerator pedal exceeds the set rapid initialization accelerator pedal operation amount, it is determined that the driver has a will to accelerate the vehicle.

And when the driver does not intend to accelerate, the pedal operation is returned to the pedal operation determination step.

In the piston position rapid initialization step, the oil filled inside is discharged at a predetermined speed from the master cylinder of the electric booster at the current position of the piston, thereby reducing the pressure inside the master cylinder.

In the piston position rapid initialization step, when the piston of the electric booster moves backward and is positioned at one end of the master cylinder, the position of the piston is initialized.

When it is determined that the electric booster is started by opening the door or starting the vehicle in the pedal operation determining step, the pressure of the master cylinder of the electric booster is raised to a predetermined pressure with a predetermined slope to advance the piston, The piston is moved back to a predetermined pressure by reducing the pressure determined by another constant slope and then the piston is moved back to one end of the master cylinder and then the piston is initialized to a position where the piston is moved for a predetermined period of time And a position normal initialization step is performed.

According to the method for initializing the piston position of the electric booster according to the present invention, when the driver brakes the brake pedal by pressing the brake pedal, the position of the piston is rapidly initialized, so that the driver's required braking force is generated from the electric booster .

In addition, since the driver's required braking force is generated, the risk of malfunction can be prevented, and the driver can feel the same feeling as usual.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart illustrating a piston position initialization method in accordance with the prior art;
2 is a graph showing a position of a piston according to a conventional piston position initialization method.
3 is a flowchart showing a method of initializing a piston position of an electric booster according to the present invention.
4 is a sectional view showing an electric power booster in which a piston position initializing method of an electric booster according to the present invention is performed.
5 is a flowchart illustrating a method of initializing a piston position of an electric booster according to the present invention.

Hereinafter, a method of initializing a piston position of an electric booster according to the present invention will be described in detail with reference to the accompanying drawings.

The method for initializing a piston position of an electric booster according to the present invention includes a pedal operation judging step (S110) for judging whether the brake pedal (11) operates in an electric booster installed in a braking device of a vehicle, (S120) for determining whether the brake pedal 11 is operated or not; a step S 120 for determining a driver's will to accelerate if it is determined that the brake pedal 11 is operating; and, if it is determined that the driver is willing to accelerate the vehicle, And a piston position rapid initialization step (S130) for initializing the position of the piston 13 from the current position.

First, the configuration of the electric booster in which the piston position initialization method of the electric booster according to the present invention is performed will be described with reference to FIG.

The electric booster includes a brake pedal 11 that is operated by a driver's foot during braking, a motor 12 that operates when power is applied, brake oil that is filled in the brake booster, oil that is to be sent to each wheel, And a master cylinder 14 which pressurizes the master cylinder.

A brake pedal 11 is mechanically connected at one end to the vehicle floor panel of the brake pedal 11 to operate the brake pedal 11 when the driver intends to brake the brake pedal 11, And transmitted to the braking device. A brake pedal angle sensor 11a for detecting the position of the brake pedal 11 is provided at one side of the brake pedal 11 to measure a rotation angle of the brake pedal 11, 11) is measured.

A motor 12 is provided to press each brake oil. The motor 12 is controlled by the ECU 31 and operates when power is applied to pressurize the brake oil.

The master cylinder 14 is filled with brake oil, and when the brake oil is pressurized in the master cylinder 14, the master cylinder 14 is transmitted to each wheel to exert a braking force.

The master cylinder 14 includes a first cylinder 14a and a second cylinder 14b so that brake oil is supplied from the remaining cylinders even if one of the cylinders does not operate.

In addition, a piston 13 is installed inside the master cylinder 14. The piston 13 is connected to the motor 12 to pressurize the brake oil in the master cylinder 14 while advancing when the motor 12 rotates. For example, a ball screw is installed in the motor 12, so that the rotational motion of the motor 12 is converted into a linear motion, thereby pressing the brake oil in the master cylinder 14.

Meanwhile, a restoring spring (not shown) for restoring the piston 13 to its original position is provided in the master cylinder 14.

The master cylinder 14 receives brake oil from the reservoir 14, pressurizes the brake oil, and sends the brake oil to the first cylinder 14a and the second cylinder 14b in a pressed state.

In addition, a configuration for imparting the above-mentioned jitters is added. That is, the brake pedal 11 is charged inside and applies a force to resist the operation of the brake pedal 11, thereby giving the driver a sense of urgency.

To this end, a rear wheel master cylinder 21, a first solenoid valve 22, a second solenoid valve 23 and a pedal simulator 24 are provided.

The rear wheel master cylinder 21 generates a reaction force by generating a reaction force against the operation of the brake pedal 11 by the pressure of the brake fluid filled in the rear wheel master cylinder 21 and the elastic force of the spring. The rear wheel master cylinder 21 is connected to the reservoir 15 and the master cylinder 14 so as to adjust the pressure of the brake oil to be filled in the rear wheel master cylinder 21, thereby controlling the pedal feeling according to the operating force.

A first solenoid valve 22 and a second solenoid valve 23 are provided between the master cylinder 14 and the rear wheel master cylinder 21 and are connected to the rear wheel master cylinder 21 Thereby controlling the supply of the brake oil to be supplied. That is, the first solenoid valve 22 is installed in the 'normal open' state between the master cylinder 14 and the rear wheel master cylinder 21, and the second solenoid valve 23 is installed in the ' Is normally installed between the pedal simulator (22) and the pedal simulator (24). Brake oil of the master cylinder 14 may be supplied to the rear wheel master cylinder 21 through the first solenoid valve 22 but not supplied to the pedal simulator 24 in a normal state. When the brake pedal 11 is operated, the first solenoid valve 22 is in a close state and the second solenoid valve 23 is in an open state. Is transmitted to the brake pedal 11 by the pressure, so that the pedal simulator 24 generates a feeling of braking proportional to the operating force.

The pedal simulator 24 is connected to the rear wheel master cylinder 21 through the second solenoid valve 23 and is connected to the rear wheel master cylinder 21 by the pressure of the brake oil charged therein and the elastic force of the spring. So that the pressure of the oil is regulated so that the damping effect can be controlled.

The method of initializing the piston position of the electric booster according to the present invention is implemented by the electric booster.

The pedal operation determination step (S110) determines whether the brake pedal 11 is operated by the driver.

In initializing the position of the piston 13 in the electric booster, there is a sufficient time to reset the position of the piston 13 when opening or starting the door of the vehicle. However, when the driver directly depresses the brake , It is necessary to generate a driver's required braking force necessary for braking the vehicle in a state in which the time sufficient to initialize the piston 13 is not ensured. Therefore, since the piston can not be initialized in a short time by the conventional method, that is, the initialization method according to the related art, the initialization is performed using the position of the current piston 13 as a mechanical reference point.

Accordingly, in the pedal operation determination step (S110), whether the brake pedal 11 is operated or not can be selectively performed by initializing the position of the piston 13 by a normal method or by rapid initialization .

The driver acceleration will determination step (S120) determines whether the driver has the intention to accelerate the vehicle. When the driver operates the electric booster by operating the brake pedal 11, the driver's braking force must be generated in a state where the position of the piston 13 is not initialized. At this time, when the displacement of the piston 13 is initialized, Temperature, etc., it may be dangerous to initialize the piston displacement during operation. Accordingly, in order to initialize the displacement of the piston 13, rapid initialization must be performed after determining the driver's will to accelerate.

In the driver acceleration will determination step S120, the condition for determining the driver's acceleration will be satisfied when the following conditions are satisfied.

First, the pressure P of the master cylinder 14 must be lower than the preset rapid initial master cylinder pressure Pi (P < P _i ). If the driver does not operate the brake pedal 11, the pressure P of the master cylinder 14 does not rise. Therefore, the preset initial pressure, that is, It is one of the conditions that it can be judged that there is no acceleration will of the driver if it is lower than the cylinder pressure (P _i ).

Second, the brake switch must be off. The brake pedal 11 is not operated if there is an acceleration of the driver, so that the state of the brake such as the brake for turning on the brake or the like is off (OFF) state.

Third, the vehicle speed of the vehicle must be within a certain range. That is, if the speed of the vehicle is too slow, it is ambiguous to judge the acceleration will of the vehicle, and if it is too fast, the risk increases, so that the position of the piston 13 is rapidly initialized only when the vehicle speed is within a certain range. Accordingly, the vehicle speed (V) previously set fast initialization rate lower limit (V _{i _ min)} an with a preset rapid initialization speed upper limit greater than (V _{i _ MAX)} is less than _{(V i _min <V <V} i _ MAX) only piston To be initialized quickly.

Fourth, the acceleration (A) of the vehicle must be greater than the predetermined rapid initial acceleration (A _i ) (A> A _i ). That is, if the acceleration intention of the driver, the vehicle acceleration (A), as compared to larger than the bar, acceleration (A) of the vehicle acceleration a preset rapid initialization (A _i) When traveling while increasing the velocity of the actual vehicle Is initialized to the position of the piston (13) only when the initialization acceleration ( _Ai ) is greater than the rapid initialization acceleration ( _Ai ).

Finally, the operation amount of the accelerator pedal (D) is larger than a preset rapid comparison initialize the accelerator pedal operation amount (D _i). When the driver intends to accelerate the vehicle, the driver must operate the accelerator pedal, so that the operation amount D of the accelerator pedal becomes larger than the predetermined rapid return accelerating pedal operation amount D _i (D> D _i ).

Only when all of the conditions described above are satisfied, the driver determines that there is an acceleration and the displacement of the piston 13 is initialized. That is, when the pressure P of the master cylinder 14 is lower than the rapid initializing master cylinder pressure P _i (P <P _i ), the brake light switch is off, the vehicle speed is lower than the predetermined rapid initialization speed lower limit (V _{i _ min)} and rapid and between the initialized speed upper limit _{(V i _ MAX) (V} i _min <V <V i _ MAX), rapid acceleration (a) is set in the vehicle while greater than the initialization acceleration (a _i) (A > A _i ), the position of the piston 13 is initialized only when the actuation amount D of the accelerator pedal is larger than the preset rapid initialization accelerator pedal actuation amount Di.

If all of the above conditions are not satisfied, the operation is returned to the pedal operation determination step (S110).

The piston position rapid initialization step (S130) is performed when it is determined that the driver is to accelerate in the driver's will determination step (S120), that is, when all of the above five conditions are satisfied. In other words, the initialization of the displacement of the piston 13 during operation is carried out in a state in which the driver does not know what kind of operation is to be performed in the actual vehicle. In the piston position rapid initialization step S130, when the above conditions are all satisfied, the piston 13 is operated to retreat, that is, to operate only in a direction to reduce the pressure inside the master cylinder 14. [ Since the driver has already operated the brake pedal 11 to operate the electric booster, the position of the piston 13 is immediately initialized without further judgment.

In the piston position rapid initialization step (S130), the pressure of the master cylinder (14) is reduced so that the piston (13) is moved backward. Since the piston 13 is provided to raise the pressure of the master cylinder 14 when the piston 13 is advanced and decrease the pressure of the master cylinder 14 when the piston 13 is moved backward, 13) is operated only in a direction to reduce the pressure of the master cylinder (14).

In particular, when the piston 13 is moved backward to reach one end of the master cylinder 14 in the piston position rapid initialization step S130, the position P ₀ is reset to zero.

If it is determined in step S110 that the brake pedal 11 is not operated, that is, when the door is opened or the ignition key is operated to start the vehicle, the piston position normal initialization step S140 .

Since the door is opened or the ignition key is actuated to start the vehicle in the piston position normal initialization step (S140), there is a time to initialize the position of the piston, so that the position of the piston is initialized by a conventional method.

That is, in the normal piston position initialization step S140, the position demand value of the piston 13 is increased to a predetermined slope to advance the piston 13, and then the piston 13 is further reduced to another constant slope, Is positioned at one end of the master cylinder (14). The position of the piston 13 is reset to the initial position when the piston 13 remains in the master cylinder 14 for a predetermined period of time.

11: Brake pedal 11a: Brake pedal angle sensor
12: motor 13: piston
14: master cylinder 14a: first cylinder
14b: second cylinder 15: reservoir
21: rear wheel master cylinder 22: first solenoid valve
23: second solenoid valve 24: pedal simulator
31: ECU
S110: Pedal operation determination step
S120: Driver acceleration will determination step
S130: Piston position rapid initialization step
S140: Piston position normal initialization step

Claims (6)

A pedal operation judging step of judging whether a brake pedal is operated in an electric booster installed in a braking device of the vehicle,
Determining whether the brake pedal is operated in the pedal operation determination step,
A method of initializing a piston position of an electric booster, comprising the step of initializing the position of the piston in the electric booster from the current position if it is determined that the driver is willing to accelerate the vehicle.
The method according to claim 1,
The driver acceleration will determination step may include:
If the master cylinder pressure is lower than the set rapid return master cylinder pressure, the brake light switch is OFF, the vehicle speed is below the set rapid initialization vehicle speed upper limit, Wherein the controller determines that the driver has a will to accelerate the vehicle when the amount of increase in the rapid initialization vehicle speed is exceeded and the amount of operation of the accelerator pedal exceeds the set rapid initialization accelerator pedal operation amount.
The method according to claim 1,
And if the driver does not intend to accelerate, the operation returns to the pedal operation determining step.
The method according to claim 1,
In the piston position rapid initialization step,
And discharging oil filled in the piston at a predetermined speed from a master cylinder of the electric booster at a current position of the piston to reduce a pressure inside the master cylinder.
5. The method of claim 4,
In the piston position rapid initialization step,
Wherein the position of the piston is initialized when the piston of the electric booster is reversed and positioned at one end of the master cylinder.
The method according to claim 1,
When it is determined that the electric booster is started by opening the door or starting the vehicle in the pedal operation determining step, the pressure of the master cylinder of the electric booster is raised to a predetermined pressure with a predetermined slope to advance the piston, The piston is moved back to a predetermined pressure by reducing the pressure determined by another constant slope and then the piston is moved back to one end of the master cylinder and then the piston is initialized to a position where the piston is moved for a predetermined period of time Wherein the position normal initialization step is performed.

Images