JPH11198781A - Brake device for car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To freely control a master cylinder pressure for a pedal stroke (output characteristics of master cylinder and reactional characteristics of brake pedal) by regulating the pressure according to an output from a stroke sensor. SOLUTION: A brake device for vehicle is structured so that a normally closed solenoid valve 7 and an electromagnetic proportional pressure control valve 8 are installed in a fluid path extending from the delivery outlet of a master cylinder 3 to a reservoir 4, and a master cylinder pressure is regulated by the electromagnetic proportional pressure control valve 8 to a value according to an output from a stroke sensor 2. Thus a relation between the output from the stroke sensor 2 and a current value flowed through an electromagnet 18 of the electromagnetic proportional pressure control valve 8 (master cylinder pressure to be in proportion to its current value) is set freely so as to obtain a desirable pedal feeling and also provide nonlinear characteristics easily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device for a vehicle which can freely set a pedal feeling (operating feeling of a brake pedal) and an output characteristic of a master cylinder.

[0002]

2. Description of the Related Art As a vehicle brake device, a system has been widely used in which a human pedal force is converted into a hydraulic pressure by a master cylinder, and the brake caliper is directly driven by the hydraulic pressure to produce a braking force. However, in recent years, brake systems such as ABS have been considered and used.
Such a system brings a strange feeling to a brake pedal which is stepped on by a human, which does not occur in normal times. This discomfort is caused by changes in hydraulic pressure which are essential during control and cannot be avoided, but has been tolerated to some extent in such a system working only in an emergency.

[0003] However, in the case where the vehicle yaw control using a brake which has begun to spread in recent years is to be performed, AB
Since the frequency of operation of the system is higher than that of S or the like, improvement in pedal feeling has been desired.

[0004] In the case of a brake device disclosed in Japanese Patent Application Laid-Open No. 9-240465, that is, a brake device in which the drive of a brake caliper is not directly performed by a force applied from a brake pedal, even in the above-described system, The control does not deteriorate the pedal feel during brake operation. This is because the brake pedal and the caliper do not exert any mechanical influence on each other when the system is operated.

[0005] However, in this type of brake device, a device using a spring is generally employed to create a simulated pedal stroke. In such a device, the reaction force characteristic of the brake pedal is constant for each model with respect to the stroke of the brake pedal, and the characteristic is linear. The relationship between the master cylinder pressure and the pedal stroke is fixed, and the master cylinder pressure increases proportionally as the pedal stroke increases. On the other hand, if the setting of the pedal reaction force with respect to the stroke of the brake pedal can be freely changed, the master cylinder pressure (the hydraulic pressure generated by the master cylinder) and the depression reaction force transmitted to the driver via the brake pedal (hereinafter referred to as the pedal). Reaction force) rises smoothly and slowly in accordance with the depression stroke of the brake pedal (hereinafter referred to as the pedal stroke), and as the pedal stroke increases, the rate of increase in pressure and reaction force increases, resulting in sudden braking. By providing a non-linear characteristic that improves responsiveness and operability, smooth braking can be performed and a desired pedal feeling can be obtained. It is also possible to cope with various types of braking by changing the output characteristics of the master cylinder halfway.

[0006]

If the reaction force characteristic of the brake pedal is linear, the pedal reaction force becomes excessive in a region where the pedal stroke is small, and the reaction force becomes insufficient in a region where the pedal stroke is large, and the pedal feeling is reduced. Sometimes the ring does not suit your taste. Since the above-mentioned characteristics are constant and linear in a conventional brake device, these problems cannot be solved, and it is difficult to cope with various types of braking without problems.

For example, it is conceivable to realize a non-linear characteristic by using a configuration in which the load of a spring is added stepwise and added as in a simulated reaction force device disclosed in Japanese Patent Application Laid-Open No. 9-244523. However, in this method, the reaction force generating mechanism becomes complicated.

Further, a damping effect peculiar to hydraulic pressure cannot be expected, and the pedal reaction force changes stepwise, so that a smooth pedal feeling cannot be obtained.

In view of this, the present invention enables the desired pedal feeling to be obtained by freely setting the output characteristics of the master cylinder and the reaction force characteristics of the brake pedal, and further reduces the nonlinear output characteristics of the master cylinder. An object is to make it easy to obtain with a simple structure.

[0010]

In order to solve the above problems, according to the present invention, a brake device includes a master cylinder, a master cylinder pressure adjusting device, a wheel cylinder, a wheel cylinder pressure adjusting device, An electromagnetic switching valve for selectively connecting a wheel cylinder to a master cylinder or a pressure adjusting device of a wheel cylinder, a stroke sensor for detecting a stroke of a brake pedal, another sensor group for detecting a behavior of a vehicle body, a master cylinder pressure, An electronic control unit for issuing a wheel cylinder pressure adjustment command;
It is composed of a master cylinder pressure regulator and a power-driven hydraulic pressure source that supplies hydraulic pressure to the wheel cylinder pressure regulator. The wheel cylinder pressure regulation by the wheel cylinder pressure regulator is based on the stroke sensor and the vehicle body. The master cylinder pressure is adjusted by the master cylinder pressure adjusting device in accordance with the output of the stroke sensor, based on the output of another group of sensors for detecting the behavior.

The pressure adjusting device for the master cylinder preferably comprises an electromagnetic proportional pressure control valve for controlling the master cylinder pressure to a value corresponding to an electric command and a normally closed type solenoid valve.
In this case, the electromagnetic proportional pressure control valve and the normally closed type electromagnetic valve are arranged in series in a liquid passage from the discharge port of the master cylinder to the reservoir.

[0012]

According to the present invention, since the pressure regulating device controlled by the electronic control unit is provided to regulate the master cylinder pressure in accordance with the output of the stroke sensor, the relationship between the output of the stroke sensor and the control target pressure by the pressure regulating device is provided. Can be freely changed by the control software.
The desired pedal feeling can be obtained by freely setting the master cylinder pressure for the pedal stroke. In addition, the non-linear output characteristics of the master cylinder can be realized without complicating the structure.

[0013] In addition, when the pressure is adjusted by the electromagnetic proportional pressure control valve, the master cylinder pressure can be adjusted smoothly and continuously, and better results can be obtained with respect to smooth braking and improved pedal feeling. .

[0014]

FIG. 1 shows an embodiment of a brake device according to the present invention. In the figure, 1 is a brake pedal, 2 is a stroke sensor for detecting a pedal stroke, and 3 is a master cylinder with a reservoir 4. Reference numeral 7 denotes a normally closed solenoid valve, and reference numeral 8 denotes an electromagnetic proportional pressure control valve, both of which constitute a master cylinder pressure adjusting device.
9 is a wheel cylinder for generating a braking force, 10 is an electromagnetic proportional pressure control valve serving as a pressure adjusting device for the wheel cylinder, and 11 is a wheel cylinder 9 which is selectively used as a master cylinder 3 or an electromagnetic proportional pressure control valve for adjusting the wheel cylinder. An electromagnetic switching valve to be connected, 12 a pump driven by a motor (not shown), and 13 an accumulator.

Here, the master cylinder 3 presses the push rod 5 with the brake pedal 1, amplifies the pushing force with the booster 6, and operates the built-in piston (not shown) with the amplified force. ing. The booster 6 is not essential, but if a vacuum booster is used, the master cylinder pressure can be amplified without depending on the pump 12, and the capacity of the pump 12 can be reduced. Further, even when the supply of the hydraulic pressure from the pump 12 becomes impossible, a relatively large braking force can be secured by the function of the booster.

In addition to the above elements, the exemplified brake device includes an electronic control unit and other sensor groups (wheel speed sensors, acceleration sensors, yaw sensors for detecting rotation of the vehicle body, etc.) for detecting the behavior of the vehicle body. (Not shown).

Although the figure shows only one wheel cylinder 9 for simplification, the wheel cylinder 9 is, of course, provided for each wheel. In the case of controlling the four wheels of a car by dividing the two systems into two systems, one system is used for each system.
When the wheels are controlled independently, an electromagnetic switching valve 11 and an electromagnetic proportional pressure control valve 10 are provided for each wheel.

The pressure adjusting device for the master cylinder and the pressure adjusting device for the wheel cylinder are only required to be capable of increasing and decreasing the load hydraulic pressure by electrical control, and may be a combination of a switching valve and the like. Employs an electromagnetic proportional pressure control valve that enables smooth and continuous pressure adjustment. The electromagnetic proportional pressure control valve 8 for master cylinder pressure adjustment and the electromagnetic proportional pressure control valve 10 for wheel cylinder pressure adjustment have the same structure, and therefore, the structure will be described only for the electromagnetic proportional pressure control valve 8.

The electromagnetic proportional pressure control valve 8 includes a casing 14,
The spool 15 includes a reaction force pin 16 inserted into one end of the spool 15, a spring 17 for urging the spool, and an electromagnet 18 for moving the spool 15 upward in the drawing.

The housing 14 makes the spool 15 almost liquid-tight,
A spool guide hole 19 slidably inserted, an input port 20, a load port 21 opened in the middle of the length of the hole,
And a discharge port 22, a first liquid chamber 23 facing one end of the spool 15, and a second liquid chamber 24 facing the other end.

The spool 15 has an internal passage 26 which is always in communication with the surface passage 25 and the load port 21, and a reaction force pin 16 is provided at an opening of the internal passage 26 to the second liquid chamber 24.
Are inserted almost liquid-tight. Thereby, the spool 1
5, the area receiving the hydraulic pressure toward the first liquid chamber 23 side and the second area
The area receiving the hydraulic pressure toward the liquid chamber 24 side has the reaction force pin 16
Of the load port 2
The thrust of the value multiplied by the pressure of 1
Work on.

The discharge port 2 is provided between the land on the outer periphery of the spool 15 and the discharge port 22 in accordance with the displacement of the spool.
A first valve portion 27 for communicating and shutting off the load port 21 with the load port 21 is formed, and between the land portion on the outer periphery of the spool 15 and the input port 20, the load port 21 and the input port 20 are changed according to the displacement of the spool. A second valve portion 28 for communicating and shutting off is formed. The opening degree of the first valve part 27 and the second valve part 28 changes depending on the spool position.

The electromagnetic proportional pressure control valve 8 includes the electromagnet 1
When no current is flowing through the spool 8, the spool 15 is held at the biasing end by the spring 17 and the first valve portion 27
Is open, and the hydraulic pressure from the load port 21 flows to the discharge port 22.

Next, when the electromagnet 18 is energized, the spool 1 is turned on.
5 is moved upward in the figure by the electromagnetic force and moves to the balance point between the force applied downward and the force applied upward.

The balance equation of the force applied to the spool 15 is as follows:
As shown in (1), as the current I flowing through the electromagnet 18 increases, the amount of spool movement increases and the opening of the first valve portion 27 decreases. When the current I further increases after the first valve section 27 closes as shown in the figure, the second
The valve 28 opens and the pressure at the input port 20 flows to the load port 21, and the pressure at the load port 21 increases. _{F pr + F sp = F soL} ...... (1) F sp: spring force 17 F _SOL: driving force F _pr by the electromagnet 18: F _pr thrust above equation by hydraulic pressure, the pressure in the load port 21 P2, reservoir Assuming that the pressure is P3 and the cross-sectional area of the reaction force pin 16 is S, it can be obtained by the formula of (P2-P3) · S. On the other hand, F _SOL is Motomari formula of a-b · I ^2, therefore, (P2-P3) · S + F sp = a-b · I 2 ∴P2 = (a-b · I 2 -F sp) / S + P3 (2) _Fsp , a, b, s, and P3 in equation (2) are all constants, and thus the load port pressure P2 is a function of the current I.

In the brake device shown in FIG. 1, the load port 21 of the above-described electromagnetic proportional pressure control valve 8 is connected to the discharge circuit of the master cylinder 3, and the input port 20 is connected to the discharge circuit of the pump 12, respectively. The discharge port 22 to which the first liquid chamber 23 always communicates and the second liquid chamber 24 are connected to the reservoir 4.

The electromagnetic proportional pressure control valve 10 for adjusting the wheel cylinder pressure also differs from the former in that the load port 21 is connected to the wheel cylinder 9 via the electromagnetic switching valve 11, but the input port 20 is the discharge circuit of the pump 12 like the former. Connect to
The discharge port 22 and the second liquid chamber 24 are connected to the reservoir 4.

In the brake device of FIG. 1 configured as described above, when the brake pedal 1 is not depressed and the brake is not applied, the electromagnetic valve 7 closes, and the electromagnet 18 of the electromagnetic proportional pressure control valve 8 becomes non-energized. I have. Also, the electromagnetic switching valve 11 is not operating, and the master cylinder 3 is
The fluid path from the electromagnetic proportional pressure control valve 10 to the wheel cylinder 9 in communication with is controlled.

Next, when the brake pedal 1 is depressed,
A command is issued from the electronic control unit based on the operation signal of the stroke sensor 2 (a brake switch may be provided and a signal from the brake switch may be used), and the solenoid valve 7 opens as shown in the figure.
Also, under the control of the electronic control device, an exciting current according to the output of the stroke sensor 2 flows through the electromagnet 18 of the electromagnetic proportional pressure control valve 8, and the master cylinder pressure is controlled by the electromagnetic proportional pressure control valve 8 according to the output of the stroke sensor 2. The pressure is adjusted to the specified value.

FIG. 3 shows an example of adjusting the master cylinder pressure by the apparatus of the present invention. By changing the relationship between the output of the stroke sensor 2 and the value of the current flowing to the electromagnet 18 of the electromagnetic proportional pressure control valve 8 (control software for determining the relationship can be freely set), the master cylinder pressure with respect to the pedal stroke is changed by the solid line and the dotted line in the figure. , And can be freely set and controlled as indicated by a chain line.

The wheel cylinder pressure is controlled by the electromagnetic proportional pressure control valve 10 based on the output of a group of other sensors for detecting the behavior of the vehicle body so that locking, slippage, rotation (spin), etc. of the wheels are prevented. Controlled.

For example, if it is detected from the signal of the wheel speed sensor that the wheel is in a sign of locking, a command flows from the electronic control unit to the electromagnetic switching valve 11, and the wheel cylinder 9 is connected to the electromagnetic proportional control valve 10. The pressure in the wheel cylinder 9 is reduced. When the wheel locks tend to recover due to this pressure reduction, a re-pressurization command is issued from the electronic control unit, and a current flows through the electromagnet 18 of the electromagnetic proportional pressure control valve 10, and the pump 1
The hydraulic pressure is introduced into the wheel cylinder 9 from the discharge circuit 2 via the input port 20 and the load port 21 to re-pressurize the wheel cylinder 9. Additionally, in some cases,
The wheel cylinder pressure is also maintained (at this time, the load port 21 is separated from both the input port 20 and the discharge port 22 by the spool 15 as shown in the figure), and the wheel lock is avoided by repeating this operation.

When the system is down due to a failure of the electric system or the like and the electromagnetic proportional pressure control valve 8 does not operate, the master cylinder pressure generated by the pedaling force flows toward the reservoir 4. It is provided for the purpose of preventing this. This electromagnetic valve 7 may be provided in a liquid passage from the electromagnetic proportional pressure control valve to the reservoir 4, as shown in FIG. In this case, the solenoid valve 7 controls the solenoid proportional pressure control valves 8, 10
Can also be used to stop liquid leakage.

The system is provided with a self-abnormality diagnosis function. If any abnormality is detected, the solenoid valves 8 and 10 are deactivated to stop adjusting the master cylinder pressure and the wheel cylinder pressure. It is to be applied to the wheel cylinder 9. Electromagnetic proportional pressure control valve 10
May be directly returned to the reservoir 4 without passing through the electromagnetic valve 7.

[0035]

As described above, in the brake device of the present invention, the master cylinder pressure is regulated in accordance with the output of the stroke sensor. And the reaction force characteristics of the brake pedal).
By adjusting the control software, a desired pedal feeling can be obtained. Further, a non-linear characteristic can be easily obtained with a simple structure, and it is easy to cope with diversification of braking.

Further, since the braking force with respect to the pedal reaction force can be made variable, the ratio of (wheel cylinder pressure) / (master cylinder pressure) can be reduced even when the driver's pedaling force is weak and the initial stepping speed is high. It can also be expected to increase the braking effect by raising it.

Further, in the case of using an electromagnetic proportional pressure control valve as a master cylinder pressure adjusting device, the master cylinder pressure can be adjusted smoothly and continuously, and braking and pedal feeling can be further stabilized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a brake device of the present invention.

FIG. 2 is a circuit diagram of a brake device in which an installation position of a normally closed solenoid valve is changed.

FIG. 3 is a diagram showing an example of master cylinder pressure adjustment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Stroke sensor 3 Master cylinder 4 Reservoir 5 Push rod 6 Booster 7 Normally closed solenoid valve 8 Electromagnetic proportional pressure control valve 9 Wheel cylinder 10 Electromagnetic proportional pressure control valve 11 Electromagnetic switching valve 12 Pump 13 Accumulator 14 Housing 15 Spool 16 Reaction pin 17 Spring 18 Electromagnet 19 Spool guide hole 20 Input port 21 Load port 22 Drain port 23 First liquid chamber 24 Second liquid chamber 25 Surface passage 26 Internal passage 27 First valve portion 28 Second valve portion

Claims (3)

[Claims] An electromagnetic switching valve for selectively connecting a master cylinder, a master cylinder pressure regulator, a wheel cylinder, a wheel cylinder pressure regulator, and a wheel cylinder to a master cylinder or a wheel cylinder pressure regulator. A stroke sensor for detecting a stroke of a brake pedal, another sensor group for detecting a behavior of a vehicle body, an electronic control device for issuing a pressure regulation command for a master cylinder pressure and a wheel cylinder pressure, and a pressure regulation device for a master cylinder. A power-driven hydraulic pressure source for supplying hydraulic pressure to the wheel cylinder pressure control device. The pressure control of the wheel cylinder pressure by the wheel cylinder pressure control device is performed by the stroke sensor and other sensors for detecting the vehicle body behavior. Of the master cylinder pressure by the master cylinder pressure regulator Brake system that is made in accordance with the output of the stroke sensor. 2. A pressure regulating device for a master cylinder, comprising: an electromagnetic proportional pressure control valve for controlling the master cylinder pressure to a value corresponding to an electric command; and a normally closed solenoid valve. 2. The vehicle brake device according to claim 1, wherein a solenoid valve of a type is arranged in series in a fluid path from a discharge port of the master cylinder to the reservoir. 3. The vehicle brake device according to claim 2, wherein the normally closed solenoid valve is provided in a liquid passage from the electromagnetic proportional pressure control valve to the reservoir.