KR20200027194A - Braking apparatus and braking control method of vehicle - Google Patents

Abstract

According to the present invention, disclosed are a braking device of a vehicle and a braking control method. The braking device of the vehicle of the present invention comprises: a first master cylinder that forms hydraulic pressure as a brake pedal is pressed; a second master cylinder that forms braking hydraulic pressure through a piston pressed by a nut moving according to the rotation of a motor and the hydraulic pressure formed by the first master cylinder; and a control unit that calculates the required movement position of the nut based on the pedal stroke of the brake pedal to control the motor, wherein the invalid stroke section of the first master cylinder is divided into a first half section and a second half section and the slope of the required movement position of the nut to the pedal stroke is differently set in the first half section and the second half section to control the motor.

Description

Vehicle braking system and braking control method {BRAKING APPARATUS AND BRAKING CONTROL METHOD OF VEHICLE}

The present invention relates to a braking device and a braking control method for a vehicle. More specifically, in an electric booster braking system that is not equipped with a pedal simulator, a vehicle braking device and braking system to secure an emotional quality by providing an appropriate pedal feeling to a driver It relates to a control method.

Recently, the electric-powered brake system has been expanded to implement a vacuum-free brake system for improving fuel efficiency, and to implement active braking actuators such as an emergency braking system (AEB) and regenerative braking cooperative control of electric vehicles. to be.

In general, the electric booster braking system maintains most of the braking mechanism of the existing vacuum booster, but instead of boosting the braking hydraulic pressure with a differential pressure between air pressure and vacuum pressure like vacuum booster, electric booster using electric energy (that is, There is a difference between a vacuum booster and its boosting mechanism in that the braking hydraulic pressure is boosted by the power of the motor).

The electric booster braking system can be divided into two types depending on whether a pedal simulator is installed. In the case of the electric booster braking system equipped with a pedal simulator, the driver cuts off the pedal force of the driver generated by putting in the brake pedal and performs braking with only the power of the electric booster.For the pedal feeling of the driver, the rubber damper of the pedal simulator or The reaction force by the spring allows the driver to feel the pedal feeling similar to that of the existing vacuum booster braking system.

On the other hand, in the case of the electric booster braking system not equipped with a pedal simulator, a part of the braking force is formed by the driver's pedal effort to form the driver's pedal feeling. For example, if the booster ratio of the electric booster is 10: 1, 10% of the total braking force is the braking force of the driver's pedal effort, and 90% is the braking force of the electric booster. That is, in the case of the electric booster braking system without the pedal simulator, a portion of the entire braking force is applied to the pedal pedal force of the driver to form a pedal feeling of the driver.

Background art of the present invention is disclosed in Republic of Korea Patent Publication No. 10-2008-0044300 (2008.05.20 published, automotive braking system).

In the case of an electric booster braking system equipped with a pedal simulator, there are disadvantages in terms of cost and size because additional parts such as a solenoid valve are required, but have an advantage of easily forming a pedal feeling of the driver.

On the other hand, in the case of an electric booster braking system without a pedal simulator, there is a problem that it is not easy to form an appropriate pedal feeling of the driver. An appropriate pedal feeling here may mean a pedal feeling provided by a conventional vacuum booster braking system. That is, the driver is accustomed to the braking feeling and pedal feeling provided by the conventional vacuum booster type braking system, but as described above, the vacuum booster has a different power boosting mechanism from the electric booster, so a pedal simulator is not installed. For the electric booster braking system, there is a problem in that it is difficult to implement the pedal feeling provided by the conventional vacuum booster braking system.

The present invention has been devised to improve the above problems, and an object of the present invention according to an aspect is a vehicle for securing an emotional quality by providing an appropriate pedal feeling to a driver in an electric booster braking system without a pedal simulator. It is to provide a braking device and a braking control method.

A braking device for a vehicle according to an aspect of the present invention includes a first master cylinder that forms a hydraulic pressure when a brake pedal is pressed; A second master cylinder forming a braking hydraulic pressure through a hydraulic pressure formed by the first master cylinder and a piston pressed by a nut moving according to the rotation of the motor; And controlling the motor by calculating the required movement position of the nut based on the pedal stroke of the brake pedal, but classifying the invalid stroke section of the first master cylinder into a first half section and a second half section, and pedal stroking in the first half section and the second half section. It characterized in that it comprises a control unit for controlling the motor by setting the inclination of the required movement position of the nut differently.

In the present invention, the first half section is characterized by setting the invalid stroke section in the system including the invalid stroke section of the second master cylinder and the invalid stroke section of the caliper.

In the present invention, the inclination of the first half and the second half is characterized in that the slope of the first half is set to steep slope and the slope of the second half is set to slow slope according to the change speed of the pedal stroke.

In the present invention, the slope of the first half and the second half is characterized in that the sign of the slope of the first half and the second half is opposite in case of sudden braking.

In the present invention, the control unit is characterized in that the required moving position is updated based on the moving position of the nut at the end of the invalid stroke, which is the time when the pedal stroke leaves the invalid stroke section of the first master cylinder.

In the present invention, the control unit updates the requested movement position when the nut movement position at the end of the invalid stroke does not reach the reference requested movement position, but the reference requested movement position is a requested movement position at the end of the invalid stroke Is done.

In the present invention, the control unit is characterized by updating the requested moving position based on the difference value between the moving position of the nut and the reference requested moving position at the end of the invalid stroke.

In the present invention, the control unit is characterized in that when the difference value is less than or equal to a preset threshold, the requested movement position is updated by subtracting the difference value from the requested movement position.

In the present invention, the control unit is characterized in that when the difference value exceeds a preset threshold, the requested movement position is updated by subtracting the threshold from the requested movement position.

A braking control method for a vehicle according to another aspect of the present invention includes the steps of: determining whether a pedal stroke of a brake pedal is equal to or greater than a preset threshold stroke; When it is determined that the pedal stroke is equal to or greater than the critical stroke, the control unit determining a change speed of the pedal stroke; The control unit divides the invalid stroke section of the first master cylinder into a first half section and a second half section according to the speed of change of the pedal stroke, and sets differently the slope of the required movement position of the pedal stoke and the nut in the first half section and the second half section. step; And controlling the motor based on the required movement position of the nut with respect to the pedal stroke.

In the present invention, the first half section is characterized by setting the invalid stroke section in the system including the invalid stroke section of the second master cylinder and the invalid stroke section of the caliper.

In the present invention, the inclination of the first half and the second half is characterized in that the slope of the first half is set to steep slope and the slope of the second half is set to slow slope according to the change speed of the pedal stroke.

In the present invention, the slope of the first half and the second half is characterized in that the sign of the slope of the first half and the second half is opposite in case of sudden braking.

In the present invention, the control unit determines whether the pedal stroke has reached an invalid stroke end point, which is a point at which the invalid stroke of the first master cylinder ends; And when it is determined that the pedal stroke has reached the end of the invalid stroke, the control unit updates the requested movement position based on the movement position of the nut at the end of the invalid stroke, which is the time when the pedal stroke has reached the end of the invalid stroke. Characterized in that it further comprises a.

In the step of updating the requested movement position in the present invention, the control unit updates the requested movement position when the movement position of the nut at the end of the invalid stroke does not reach the reference requested movement position, but the reference requested movement position ends the invalid stroke It is characterized in that it is the required moving position at the time point.

In the present invention, the step of updating the requested moving position is characterized in that the control unit updates the requested moving position based on the difference value between the nut moving position and the reference requested moving position at the end of the invalid stroke.

In the step of updating the requested movement position in the present invention, when the difference value is equal to or less than a preset threshold, the control unit updates the requested movement position by subtracting the difference value from the requested movement position.

In the step of updating the requested movement position in the present invention, when the difference value exceeds a preset threshold, the control unit updates the requested movement position by subtracting the threshold from the requested movement position.

The braking device and braking control method of a vehicle according to an aspect of the present invention can improve cost competitiveness by improving a driver's pedal feeling without additional components such as a pedal simulator, and braking by applying a position control method rather than a motor current control The problem that the pedal feeling of the driver is lowered due to the friction between the internal members of the device can be solved, and the emotional quality can be secured by optimizing the pedal feeling of the driver.

1 is a configuration diagram for explaining a braking device for a vehicle according to an embodiment of the present invention.
2 is an exemplary view showing a relationship between a pedal stroke and a required movement position of a nut in a braking device of a vehicle according to an embodiment of the present invention.
3 is an exemplary view comparing a moving position of a nut and a required moving position of a nut when a driver's pedal feeling is not felt in a braking device of a vehicle according to an embodiment of the present invention.
4 and 5 is an exemplary view showing the behavior in the absolute reference and the actual behavior, respectively, when the nut does not reach the reference required movement position at the end of the invalid stroke in the braking device of the vehicle according to an embodiment of the present invention to be.
6 is an exemplary view showing a required moving position for a pedal stroke in an invalid stroke section according to a change speed of a pedal stroke in a braking apparatus for a vehicle according to an embodiment of the present invention.
7 and 8 are exemplary views illustrating a process in which a requested movement position is updated in a braking device of a vehicle according to an embodiment of the present invention.
9 is a view illustrating a process in which the requested moving position is updated when the difference between the moving position of the nut and the reference requested moving position at the end of the invalid stroke exceeds the threshold in the braking device of the vehicle according to an embodiment of the present invention This is an example.
10 is a flowchart illustrating a braking control method of a vehicle according to an embodiment of the present invention.
11 is a flowchart for specifically explaining a step of updating a required moving position in a braking control method of a vehicle according to an embodiment of the present invention.

Hereinafter, a braking device and a braking control method of a vehicle according to the present invention will be described with reference to the accompanying drawings. In this process, the thickness of the lines or the size of components shown in the drawings may be exaggerated for clarity and convenience. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to a user's or operator's intention or practice. Therefore, the definition of these terms should be made based on the contents throughout the present specification.

1 is a configuration diagram for explaining a braking device for a vehicle according to an embodiment of the present invention, and FIG. 2 shows a relationship between a pedal stroke and a required moving position of a nut in a braking device for a vehicle according to an embodiment of the present invention 3 is an exemplary view comparing the moving position of the nut and the required moving position of the nut when the driver's pedal feeling is not felt in the braking device of the vehicle according to an embodiment of the present invention, 4 and 5 is an exemplary view showing the behavior in the absolute reference and the actual behavior, respectively, when the nut does not reach the reference required movement position at the end of the invalid stroke in the braking device of the vehicle according to an embodiment of the present invention 6 is a required movement position of a pedal stroke in an invalid stroke section according to a change speed of a pedal stroke in a vehicle braking device according to an embodiment of the present invention. 7 and 8 are exemplary views showing a process in which a requested movement position is updated in a braking apparatus of a vehicle according to an embodiment of the present invention, and FIG. 9 is a view according to an embodiment of the present invention It is an exemplary view showing a process in which the requested moving position is updated when the difference value between the moving position of the nut and the reference requested moving position exceeds the threshold value at the end of the invalid stroke in the braking device of the vehicle.

As shown in Figure 1, the braking device of the vehicle according to an embodiment of the present invention, the first master cylinder 20 and the first master cylinder 20 to form a hydraulic pressure as the brake pedal 10 is pressed The hydraulic power and the rotational motion of the motor 30 are converted to linear motion, and the braking force transmission unit 40 and the push rod 45 transmit braking force to the second master cylinder 50 through the push rod 45 that is pressurized. Request of the nut 43 based on the pedal stroke of the brake pedal 10 input from the second master cylinder 50 and the pedal sensor (not shown), which forms the braking hydraulic pressure through the internal piston 51 that is pressed by It may include a control unit 60 for controlling the motor 30 by calculating the movement position.

In this embodiment, the piston is defined as a meaning including the push rod 45 of the braking force transmission unit 40 and the inner piston 51 of the second master cylinder 50. In addition, the inner piston 51 includes a first inner piston and a second inner piston that are movably inserted inside a cylinder body (not shown), and the first inner piston and the second inner piston are spaced apart from each other, thereby providing a cylinder body. A plurality of hydraulic chambers 53 may be formed therein.

The hydraulic pressure of the first master cylinder 20 generated when the driver presses the brake pedal 10 presses the push rod 45 of the braking force transmission unit 40, and according to the movement of the pressurized push rod 45 The inner piston 51 of the second master cylinder 50 is pressurized. The hydraulic pressure of the first master cylinder 20 acting on the push rod 45 means the braking force that is applied by the pedal pedal force of the driver among the total braking force (ie, braking hydraulic pressure) formed by the second master cylinder 50.

The push rod 45, which is pressurized by the hydraulic pressure of the first master cylinder 20, converts the rotational motion of the motor 30 into a linear motion by a screw 41 and a nut 43 (gear or belt (not shown). ) The motor 30 and the screw 41 are connected through a power transmission member such as) to convert the rotational motion of the motor 30 into a linear motion) Nut 43 moving in the axial direction of the screw 41 It is also pressurized by, and the inner piston 51 of the second master cylinder 50 is pressurized according to the movement of the push rod 45 pressed. The pressing force of the nut 43 against the push rod 45 means the braking force that the motor 30 bears among the total braking force formed by the second master cylinder 50.

Therefore, the braking force formed by the second master cylinder 50 may be determined as the sum of the force of the motor 30 and the pedal effort of the driver according to Equation (1).

When an electric booster braking system having a power ratio of 10: 1 is described as an example, when it is assumed that the total braking force calculated by the controller 60 based on the pedal stroke received from the pedal sensor is 100%, the controller 60 If the current applied to the motor 30 is controlled such that the pressing force of the nut 43 against the push rod 45 is 90% of the total braking force, the pedal effort of the driver becomes 10% of the total braking force, so in this embodiment The resulting braking device can be considered to behave like a vacuum booster with a power ratio of 10: 1.

However, in the actual behavior of the electric booster braking system, since the influence of internal friction of the braking system, such as friction between the piston and the sealing member sealing the piston, etc., must be taken into account, Equation 1 is more accurately expressed by Equation 2. Do.

At this time, the frictional force of Equation 2 does not have a constant value or a value proportional to the pedal stroke, but has a value that varies from time to time according to the stick-slip behavior.

For example, even if the controller 60 controls the current applied to the motor 30 so that the motor 30 bears 90% of the total braking force 100%, the driver does not always bear the braking force of 10%, but the friction force Depending on the size of the vehicle, a situation may occur in which a greater braking force is applied (for example, if the friction force is 5%, the driver must bear 15% of the force). That is, in the current control method of the motor 30, the pedal pedal force of the driver has a variable value depending on the magnitude of the frictional force, so that the pedal feeling of the driver decreases.

Therefore, in this embodiment, the controller 60 applies the position control method, not the current control of the motor 30, to perform braking. That is, the control unit 60 calculates the requested movement position of the nut 43 provided in the second master cylinder 50 based on the pedal stroke of the brake pedal 10, and the nut 43 calculates the calculated requested movement position. The motor 30 is controlled to follow.

The process in which the control unit 60 calculates the required movement position of the nut 43 will be described in detail as follows.

The rigidity of the braking system refers to the relationship between the amount of movement of the piston of the master cylinder and the hydraulic pressure generated by the movement of the piston, and its rigidity characteristics are predefined according to the system specifications. When the target braking hydraulic pressure is determined by the control unit 60 based on the pedal stroke input from the pedal sensor, the rigidity characteristic of the braking system is secured in advance, so the control unit 60 can calculate the movement amount of the piston of the master cylinder.

The hydraulic pressure of the first master cylinder 20 formed by the pedal effort of the driver, and the rigidity also exist in the transmission system between the push rods 45 (such as the rigidity of the sealing material), of the first master cylinder 20 When the ratio of the hydraulic pressure and the movement amount of the push rod 45 is defined as the primary rigidity, it can be derived as in Equation 3 for controlling the position of the internal piston 51.

In Equation 3, it can be seen that the pedal effort of the driver decreases when the amount of movement of the nut 43 is large and increases when the amount of movement of the nut 43 is small.

In Equation 3, the value of 'driver's pedal effort / primary stiffness' is the same as the value obtained by dividing the pedal ratio in the pedal stroke, and the pedal ratio has a specific value depending on the vehicle, so the value of 'driver's pedal effort / primary stiffness' Is a value proportional to the pedal stroke received from the pedal sensor. Accordingly, Equation 3 may be expressed by Equation 4.

In Equation 4, the 'movement amount' is the same concept as the 'movement position', and the required movement amount (movement position) of the internal piston 51 is controlled by the control unit 60 to the pedal stroke to form the final braking force (ie, braking hydraulic pressure). Since it is a parameter calculated based on this, Equation 4 eventually becomes a function of the required movement position of the nut 43 relative to the pedal stroke.

Accordingly, the control unit 60 may calculate the required movement position of the nut 43 based on the pedal stroke received from the pedal sensor, that is, the required movement position of the nut 43 based on the pedal stroke of the brake pedal 10. By calculating and controlling the motor 30, it is possible to perform position control such that a braking hydraulic pressure is formed through the second master cylinder 50.

In the above, the process of controlling the position of the control unit 60, that is, calculating the required moving position of the nut 43 to control the motor 30, has been described below. In the following, the nut is determined according to the invalid stroke of the second master cylinder 50. The process of updating the requested moving position in 43) will be described.

First, when the invalid stroke section is described, the invalid stroke section is the same as the seal cup from the initial sealing position of the piston of the first master cylinder 20 (that is, when the driver does not press the brake pedal 10). It means the section until passing through the sealing member. While the pedal stroke is present in the invalid stroke section, the driver's pedal effort cannot move the push rod 45, so that no braking hydraulic pressure is formed, and only after the pedal stroke leaves the invalid stroke section, braking hydraulic pressure is formed.

That is, the point in time when the pedal feeling due to the position control according to Equation 4 occurs is after the pedal stroke is out of the invalid stroke section, and in the invalid stroke section only by the sliding friction force or the restoring force of the return spring of the first master cylinder 20. Pedal feeling is generated.

When the pedal stroke and the requested movement position of the nut 43 calculated according to Equation 4 have the same relationship as the graph shown in FIG. 2, the pedal stroke is out of the invalid stroke section (defined as an invalid stroke end point) ), The position of the nut 43 should be at d1 shown in FIG. 2.

However, due to a problem of insufficient responsiveness of the motor 30 during sudden braking, a case where the pedal stroke reaches the end point of the invalid stroke, while the nut 43 is located at d0 that is less than d1 may occur. Therefore, the driver instantly feels a heavy pedal feeling, and the motor 30 operates quickly after leaving the invalid stroke section to recover the position difference of the nut 43 formed in the invalid stroke section, that is, d1-d0, Accordingly, the pedal feeling of the driver is very light, which may cause the pedal discomfort of the driver.

For a detailed understanding of the above with reference to FIG. 3 for a visual understanding of the pedal feeling of the driver, the moving position of the nut 43 when the pedal feeling of the driver by the position control is not felt is shown in FIG. 3. When expressed by the graph No. 1 and the requested movement position of the nut 43 calculated according to Equation 4 is expressed by the graph No. 2, the difference between the graph No. 1 and the graph No. 2 becomes a pedal feeling felt by the driver.

The requested movement position of the nut 43 at the end of the invalid stroke (i.e., d1 in Fig. 2) is defined as the reference requested movement position. Assuming that the movement position of the nut 43 at the end of the invalid stroke does not reach the reference required movement position, in contrast to the behavior at the absolute reference, such as graph 1 in FIG. 4 (that is, FIG. 4) Graph ① is a graph showing the case where the nut 43 located at d0 behaves according to the same slope as graph ② in FIG. 3 at the end of the invalid stroke), and the actual behavior of the nut 43 is As shown in the graph of ② in 5, to move d1 to d0 from the end of the invalid stroke, after moving out of the invalid stroke section, the moving position is rapidly increased by the motor 30 that is operated quickly, so that the driver's pedal feeling becomes much lighter. .

In a typical vacuum booster type braking system, the driver's pedal feels heavy due to a time delay occurring in the process of introducing atmospheric pressure through a mechanical valve during sudden braking. However, according to the above-described embodiment, the driver feels a heavy pedal feeling at the beginning of braking, but after leaving the invalid stroke section, the driver feels a light pedal feeling through a longer section, and this pedal feeling is a vacuum booster to which a BAS (Brake Assist System) is applied. It can occur more frequently than the braking system of the way.

Therefore, in this embodiment, the control unit 60 controls the motor 30 by calculating the required movement position of the nut 43 based on the pedal stroke of the brake pedal 10, but the invalid stroke section of the first master cylinder 20 It is possible to control the motor 30 by differentiating the change speed determination section, the first half section and the second half section, and differently setting the slope of the required movement position of the pedal stoke and the nut 43 in the first half section and the second half section.

That is, as shown in FIG. 6, the first stroke section is divided into the change speed determination section, the first half section and the second half section of the invalid stroke section of the first master cylinder 20, and according to the change speed of the pedal stroke determined in the change speed determination section. The slope of can be set to steep slope, and the slope of the second half can be set to steep slope.

Here, the first half section is set as an invalid stroke section in the system including the invalid stroke section of the second master cylinder 50 and the invalid stroke section of the caliper mounted on each wheel, so that the driver can be operated even if the required movement position changes rapidly. It is desirable to set it to a section that does not feel sympathetic.

The invalid stroke section in the system is independent of the invalid stoke of the first master cylinder 20 and the braking pressure reflecting the invalid stroke section of the second master cylinder 50 and the invalid stroke of the caliper (not shown) mounted on each wheel. It means the invalid stroke section.

Therefore, in the case of sudden braking according to the speed of change of the pedal stroke, the first section is set to a larger slope, and the latter section is set more gently to have a negative value, so that the sign of the slope of the first section and the second section is reversed. Can be set.

For example, referring to the graph of FIG. 6, in the case of sudden braking, the slope of the required movement position of the nut 43 with respect to the pedal stoke forms a steep slope in the first half, and in the latter half, the slope is gradually reduced as shown in the A graph. Is done.

In addition, the B graph shows the case of a slightly faster braking, and the C graph shows the case of a normal braking.

Therefore, in the invalid stroke section of the first master cylinder 20, if the requested movement position of the nut 43 with respect to the pedal stroke is applied as in the embodiment of the present invention, the actual value is rather similar to the original required movement position. You can expect behavior. In addition, the difference between the required moving position and the actual behavior at the end point of the invalid stroke section is also minimized.

In the required slope in the first section, the difference between the required moving position and the actual behavior is increased, so that it can respond and operate as quickly as possible. In the required slope in the second section, even in the case of sudden braking, the slope itself is gentle and it is similar to complete braking. You can expect the effect that makes you lose.

In addition, in this embodiment, the control unit 60 controls the motor 30 by calculating the required movement position of the nut 43 based on the pedal stroke of the brake pedal 10 according to Equation 4, but the pedal stroke is the first The requested movement position can be updated based on the movement position of the nut 43 at the end of the invalid stroke, which is the time beyond the invalid stroke section of the master cylinder 20, specifically, the nut 43 at the end of the invalid stroke When the moving position of) has not reached the reference requested moving position, the requested moving position can be updated.

In this way, the control unit 60 may update the requested moving position based on the difference value between the moving position of the nut 43 and the reference requested moving position at the end of the invalid stroke. That is, the requested moving position can be updated by parallelly moving the requested moving position by the difference between the moving position of the nut 43 and the reference requested moving position.

Referring to FIG. 7, the moving position of the nut 43 when the driver's feeling of pedaling is not felt by the position control is represented by the graph ① in FIG. 7, and of the nut 43 calculated according to Equation (4). When the requested movement position is represented by the graph ②, the requested movement position of the nut 43 updated according to the present embodiment is represented by the graph ③ (solid line) moved parallel to the difference value in the graph ②.

Therefore, the difference between the moving position of the nut 43 and the moving position of the nut 43 following the required moving position when the driver's feeling of pedaling by the position control is not felt is formed as shown in FIG. 8. Thus, it is possible to provide the driver with a pedal feeling originally intended as shown in FIG. 2.

That is, even if there is a difference of d1-d0 between the moving position of the nut 43 and the reference requested moving position at the end of the invalid stroke, the difference from the requested moving position is subtracted to give the same slope as the original requested moving position. By updating the required movement position to have d1-d0, it is possible to remove the pedal discomfort that causes the driver's pedal feeling to become lighter due to the motor 30 operating quickly after leaving the invalid stroke section to recover d1-d0.

On the other hand, in this embodiment, the control unit 60 subtracts the difference value from the requested moving position as above only when the difference value between the moving position of the nut 43 and the reference requested moving position at the end of the invalid stroke is equal to or less than a preset threshold. By doing so, the requested moving position can be updated.

Then, when the difference value between the moving position of the nut 43 and the reference requested moving position at the end of the invalid stroke exceeds a preset threshold, the control unit 60 does not update the requested moving position or the threshold at the requested moving position. The requested movement position can also be updated by subtracting.

Referring to FIG. 9, d1 shown in FIG. 9 is a reference request movement position, d2 is a movement position of the nut 43 where d1-d2 are the above-mentioned threshold values, and d3 is a nut at the end of the invalid stroke In the case of the actual moving position of (43), since the difference value (d1-d3) between the moving position of the nut 43 and the reference requested moving position at the end of the invalid stroke exceeds the threshold values d1-d2, the control unit 60 ) Can update the requested moving position with the graph of ③ which subtracts the threshold from the requested moving position.

This means that the amount of subtraction for updating the requested moving position is limited to a threshold, and the operation of the control unit 60 may change the braking performance of the vehicle according to frequent updating of the requested moving position, thereby reducing braking stability. It is based on the point, and the conventional view that the pedal feeling may be different from the normal case during sudden braking in the general braking system. The threshold may be variously designed according to the specifications of the braking system and the designer's intention, and may be preset in the control unit 60.

As described above, according to the braking device of the vehicle according to the embodiment of the present invention, the cost competitiveness can be improved by improving the feeling of the pedal of the driver without additional parts such as a pedal simulator, and a method of controlling a position rather than controlling the current of the motor By applying, it is possible to solve the problem that the pedal feeling of the driver decreases due to the friction between the internal members of the braking device, and to ensure the emotional quality by optimizing the pedal feeling of the driver.

10 is a flowchart illustrating a method for controlling braking of a vehicle according to an embodiment of the present invention, and FIG. 11 specifically illustrates a step of updating a required moving position in a method for controlling braking of a vehicle according to an embodiment of the present invention It is a flowchart for explanation.

As illustrated in FIG. 9, when a vehicle braking control method according to an embodiment of the present invention is described, first, the controller 60 determines whether the pedal stroke of the brake pedal 10 is greater than or equal to a preset threshold stroke (S10). . The critical stroke means a lower limit value of the pedal stroke for starting braking control of the vehicle, and may be variously designed and preset in the control unit 60 according to the specifications of the braking system and the designer's intention.

Subsequently, when it is determined that the pedal stroke is equal to or greater than the critical stroke, the control unit 60 determines the speed of change of the pedal stroke (S20).

After determining the change speed of the pedal stroke in step S20, the control unit 60 changes the invalid stroke section of the first master cylinder 20 into a change speed determination section, a first half section and a second half section as shown in FIG. The slope of the first half is set to steep slope and the slope of the second half is set to slow slope according to the change speed of the pedal stroke determined in the speed judgment section (S30).

Here, the first half section is set as an invalid stroke section in the system including the invalid stroke section of the second master cylinder 50 and the invalid stroke section of the caliper mounted on each wheel, so that the driver can be operated even if the required movement position changes rapidly. It is desirable to set it to a section that does not feel sympathetic.

The invalid stroke section in the system is independent of the invalid stoke of the first master cylinder 20 and the braking pressure reflecting the invalid stroke section of the second master cylinder 50 and the invalid stroke of the caliper (not shown) mounted on each wheel. It means the invalid stroke section.

Therefore, in the case of sudden braking according to the speed of change of the pedal stroke, the first section is set to a larger slope, and the latter section is set more gently to have a negative value, so that the sign of the slope of the first section and the second section is reversed. Can be set.

Thereafter, the control unit calculates the required movement position of the nut 43 based on the pedal stroking in the first half and second half of the invalid stroke section of the first master cylinder 20 according to the slope set in step S30 to calculate the motor 30. It is controlled (S40).

After controlling the motor 30 in step S40, the control unit 60 determines whether the pedal stroke has reached the end point of the invalid stroke, which is the end point of the invalid stroke of the first master cylinder 20 (S50).

If it is determined in step S50 that the pedal stroke has reached the end point of the invalid stroke, the control unit 60 is based on the moving position of the nut 43 at the end of the invalid stroke, which is the time when the pedal stroke has reached the end point of the invalid stroke. Then, the requested moving position is updated (S60).

At this time, the control unit 60 may update the requested movement position when the movement position of the nut 43 at the end of the invalid stroke does not reach the reference requested movement position, specifically, the nut at the end of the invalid stroke The requested moving position can be updated based on the difference value between the moving position of (43) and the reference requested moving position.

Referring to FIG. 11, step S60 will be described in detail. When the difference between the moving position of the nut 43 and the reference requested moving position at the end of the invalid stroke is less than or equal to a preset threshold (S61), The requested moving position is updated by subtracting the difference value from the moving position (S63). When the difference value between the moving position of the nut 43 at the end of the invalid stroke and the reference requested moving position exceeds the threshold (S61), the threshold is subtracted from the requested moving position to update the requested moving position (S65).

After the step S60 is performed, or when the pedal stroke has not reached the end point of the invalid stroke in step S40, the control unit 60 determines whether the pedal stroke is less than the critical stroke (S70), and the pedal stroke is reduced to less than the critical stroke. If it is determined that the braking control is terminated, and the state where the pedal stroke is equal to or greater than the critical stroke, it is performed again from step S20.

As described above, according to the braking method of a vehicle according to an embodiment of the present invention, the cost competitiveness can be improved by improving the feeling of the pedal of the driver without additional parts such as a pedal simulator, and a method of controlling a position rather than controlling the current of the motor By applying, it is possible to solve the problem that the pedal feeling of the driver decreases due to the friction between the internal members of the braking device, and to ensure the emotional quality by optimizing the pedal feeling of the driver.

The present invention has been described with reference to the embodiment shown in the drawings, but this is merely exemplary, and those skilled in the art to which the art belongs can various modifications and equivalent other embodiments from this. Will understand.

Therefore, the true technical protection scope of the present invention should be defined by the following claims.

10: brake pedal 20: first master cylinder
30: motor 40: braking force transmission
41: screw 43: nut
45: push rod 50: second master cylinder
51: internal piston 53: hydraulic chamber
60: control unit

Claims (18)

A first master cylinder that forms hydraulic pressure as the brake pedal is pressed;
A second master cylinder forming a braking hydraulic pressure through a hydraulic pressure formed by the first master cylinder and a piston pressed by a nut moving according to the rotation of the motor; And
Based on the pedal stroke of the brake pedal, the required movement position of the nut is calculated to control the motor, but the invalid stroke section of the first master cylinder is divided into a first half section and a second half section, and in the first half section and the second half section. And a control unit for controlling the motor by setting the inclinations of the pedal stoke and the nut to different positions.
The braking device for a vehicle according to claim 1, wherein the first half section is set to an invalid stroke section in a system including an invalid stroke section of the second master cylinder and an invalid stroke section of the caliper.
According to claim 1, The slope of the first half and the second half is characterized in that the slope of the first half is set to steep slope according to the change speed of the pedal stroke, and the slope of the second half is set to full slope. Vehicle braking system.
The braking device of a vehicle according to claim 1, wherein a slope of the first half section and the second half section has opposite signs of a slope of the first half section and a slope of the second half section in case of sudden braking.
The method according to claim 1, wherein the control unit updates the requested movement position based on the movement position of the nut at the end of the invalid stroke, which is the time when the pedal stroke leaves the invalid stroke section of the first master cylinder. Vehicle braking system.
The method according to claim 5, wherein the control unit updates the requested movement position when the movement position of the nut at the end of the invalid stroke does not reach the reference requested movement position, wherein the reference requested movement position is the invalid stroke A braking device for a vehicle, characterized in that it is a required moving position at the end point.
7. The braking device for a vehicle according to claim 6, wherein the control unit updates the requested moving position based on a difference value between the moving position of the nut and the reference requested moving position at the end of the invalid stroke.
The braking apparatus according to claim 7, wherein the control unit updates the requested movement position by subtracting the difference value from the requested movement position when the difference value is equal to or less than a preset threshold.
The braking apparatus according to claim 7, wherein the control unit updates the requested movement position by subtracting the threshold from the requested movement position when the difference value exceeds a preset threshold.
A first master cylinder that forms hydraulic pressure as the brake pedal is pressed; And a second master cylinder that forms a braking hydraulic pressure through a piston that is pressurized by a nut that moves in accordance with the rotation of the motor and the hydraulic pressure formed by the first master cylinder. ,
Determining, by the controller, whether a pedal stroke of the brake pedal is equal to or greater than a preset threshold stroke;
When it is determined that the pedal stroke is equal to or greater than the threshold stroke, the control unit determining a change speed of the pedal stroke;
The control unit divides the invalid stroke section of the first master cylinder into a first half section and a second half section according to the change speed of the pedal stroke, and the required movement position of the pedal stoke and the nut in the first half section and the second half section. Setting each of the slopes differently; And
And controlling, by the controller, the motor based on a required movement position of the nut with respect to the pedal stroke.
The method of claim 10, wherein the first half section is set to an invalid stroke section in a system including an invalid stroke section of the second master cylinder and an invalid stroke section of the caliper.
11. The method of claim 10, wherein the slope of the first half and the second half is set according to the change speed of the pedal stroke, the slope of the first half is set to steep slope, and the slope of the second half is set to full slope. Vehicle braking control method.
11. The method of claim 10, wherein the slope of the first half and the second half is a braking control method of the vehicle, characterized in that when the sudden braking, the sign of the slope of the first half and the slope of the second half are reversed.
11. The method of claim 10, The control unit, The step of determining whether the pedal stroke has reached the end point of the invalid stroke that is the end point of the invalid stroke of the first master cylinder; And
When it is determined that the pedal stroke has reached the end point of the invalid stroke, the control unit determines whether the pedal stroke has reached the end point of the invalid stroke, based on the moving position of the nut at the end of the invalid stroke. And updating the requested moving position.
15. The method of claim 14, In the step of updating the requested movement position, The control unit updates the requested movement position when the movement position of the nut at the end of the invalid stroke does not reach the reference request movement position, The reference request movement position is a braking control method of a vehicle, characterized in that the requested movement position at the end of the invalid stroke.
16. The method according to claim 15, wherein in the step of updating the requested movement position, the control unit updates the requested movement position based on a difference value between the movement position of the nut and the reference requested movement position at the end of the invalid stroke. The braking control method of the vehicle, characterized in that.
The method according to claim 16, wherein in the step of updating the requested movement position, the control unit updates the requested movement position by subtracting the difference value from the requested movement position when the difference value is equal to or less than a preset threshold. Vehicle braking control method.
17. The method of claim 16, wherein in the updating of the requested movement position, the control unit updates the requested movement position by subtracting the threshold from the requested movement position when the difference value exceeds a preset threshold value. A method for controlling braking of a vehicle.

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