JPS61268560A - Brake booster - Google Patents

Abstract

PURPOSE:To allow excellent brake manipulation matching human sense by increasing effects of a brake from the level of normal time when the stepping speed of the brake is fast. CONSTITUTION:An input sensor 7 detects the axial line direction movement quantity x of an input rod 3 transferred by a brake pedal 4, while an output sensor 8 detects the axial line direction movement quantity y of an output rod 5. A differential circuit 7a inputs the output of the input sensor 7, differentiates it and outputs the transfer speed signal of the input rod 3. The output of these sensors 7, 8 and the differential circuit 7a is entered in the logical circuit 7. The output signal of this logical circuit 9 is supplied to a control valve 10 through a driving circuit 9a, and adjustment of the divergence of the control valve 10 is thereby effected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a brake booster having a power piston that boosts the depression force applied to a brake pedal and transmits the boosted force to a master cylinder.

(Prior art) In a conventional brake system or brake boost system, a booster output, that is, the amount of movement y of the power piston is obtained that is proportional to the pedal force F applied to the pedal, that is, the amount of movement X of the input rond of the power piston. (such as that described in Japanese Patent Publication No. 56-95756).

(Problem to be solved by the invention) However, when you want to decelerate the car smoothly during normal driving, and when you want to stop or decelerate the car immediately, such as when avoiding an accident, there are differences in how you press the pedal. Speed F(
t)/dt or π is different, and the driver's expected value for brake effectiveness is also different. In other words, the relationship shown in the following table is obtained.

Table 1 However, in the conventional brake system or brake multiplication system, the expected brake effectiveness could not be obtained in an emergency because it had nothing to do with F(t)/dt or quality.

(Means for Solving the Problems) Therefore, an object of the present invention is to increase the effectiveness of the brake when F(t)/dt or Ω is large so that an operating sensation close to that of human sensitivity can be obtained. There is a need to obtain a brake booster that further increases the brake booster.

In order to achieve this objective, the brake booster of the present invention includes:
As shown in Figure 4, there is a working fluid source that supplies working fluid to the power piston via a control valve, an input sensor that detects the amount related to the input of the brake pedal, and an input sensor that detects the depression speed input to the brake pedal. and the means to
It is characterized by comprising an output sensor that detects a signal related to the output of the power piston, and a logic circuit that generates an output signal that controls the control valve to a value corresponding to both sensors and the depression speed detection means. shall be.

(Function) According to this configuration of the present invention, the depression speed is detected by the input unit mass sensor, the opening degree of the control valve is optimally controlled by the logic circuit, and the amount of working fluid supplied to the variable pressure chamber that operates the power piston. is adjusted, and the boosted output is applied to the output rond that transmits the movement of the power piston to the master cylinder so that the output increases when the depression speed is high.

(Example) The invention will now be described in detail with reference to the drawings.

The brake booster l has a two-power piston 2 in its shell, which associates a calotrope 8 containing a power piston 20 with a brake pedal 4 and an output lot 5 of a master cylinder 6 for supplying brake fluid to a wheel brake 2o. Relate to pistons.

Generally, the space on the output side of the power piston 2 is a negative pressure chamber 1a, and the space on the input side is a variable pressure chamber 1b. (not shown) through negative pressure chamber 1
A and the variable pressure chamber 1b are communicated, both chambers are maintained at the same negative pressure, and the power piston is biased toward the brake pedal 4 side by a return spring lc provided in the negative pressure chamber lc.

When a pedal force is input to the brake pedal 4, the input rod 8 moves toward the master cylinder 6 side within the boss portion of the power piston while resisting the spring force of the return spring lc. A vacuum pulp (not shown) closes the boat that supplies negative pressure to the variable pressure chamber, and an air pulp (not shown) installed on the single-handed Rondo side opens, opening up the internal space inside the boss of the power piston that communicates with the atmosphere. The atmosphere is introduced into the variable pressure chamber 1b in communication with the variable pressure chamber, the power piston moves based on the differential pressure between the negative pressure chamber 1a and the variable pressure chamber 1b, and this movement is transmitted to the master cylinder via the output iron, A boosted brake pressure is created at the wheel brake 20.

According to the present invention, there is further provided an input sensor for detecting the axial movement amount X of the input lot 8 moved by the brake pedal 4? An output sensor 8 detects the amount of movement of the output lot 5 in the axial direction, that is, the output y, and a differentiation circuit 7a inputs the output of the input sensor 7, differentiates it, and outputs a moving speed signal of the input lot 8. , these sensors 7.8 and the differential circuit? The output of a is input to the logic circuit 9. The output signal of this logic circuit 9 is sent to the control valve 1 via the drive circuit 9a.
0 and adjust the opening degree of this control valve. This control valve 10 is connected to a source 11 of a working fluid (air in the illustrated embodiment) having a pressure higher than the pressure in the negative chamber and a variable pressure chamber 1.
1) installed in the duct that connects the

The logic circuit 9 calculates the relationship between the input speed x in the input lot 8 and the movement amount (output) y in the output lot 5, for example, by the curve shown by the solid line in FIG. ) The control valve 10 is adjusted to an opening degree that satisfies the required functional relationship approximated by K to the output yo (same as the conventional yo) corresponding to the input An output signal shall be supplied to this control valve lO.

In the illustrated embodiment, a logic circuit 9 controls a control valve lO provided in a supply duct from a working fluid source 11 to the variable pressure chamber 1b, which is separate from the working fluid source (atmosphere) in the internal space within the boss portion of the power piston 2. However, it is not limited to this. For example, a configuration may be adopted in which air pulp directly related to the input lot 8 is controlled. In this case, a solenoid valve is installed in the air pulp, and the solenoid valve is controlled by a logic circuit 9.

Furthermore, in the illustrated embodiment, the input speed sensor is a sensor that detects the movement amount of the input lot of the power piston, and the output sensor is a sensor that detects the movement amount y of the output lot. The sensor may detect the fluctuation speed of the output unit, that is, the pedal depression speed, and the sensor may detect the output amount of the output unit, such as the brake fluid pressure generated in the master cylinder or the deceleration of the vehicle. Of course, it is possible to do so. Also, as an input sensor, instead of a sensor that detects the amount of movement of the input rondo, the brake pedal or the pedal force y(t) detected by the input rondo can be used.
Using a sensor that detects F (t), the rate of change in pedal force over time dF (t)/d t may be used as the pedal speed signal. Similarly, the output sensor may be replaced with a sensor that detects the force of the output rond or a sensor that detects the differential pressure acting on the power piston 2.

Note that a microcomputer may be used as the logic circuit, and the control flow in this case may be as shown in FIG. 8, for example.

(Effects) In this way, according to the present invention, when it is desired to quickly stop or decelerate a vehicle, such as when avoiding an accident,
Brake effectiveness is achieved in line with the driver's expectations, and an even better operating feel is achieved that matches human sensibilities.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing the configuration of a brake booster according to the present invention, and FIG. 2 is a multiplication of t for an input speed of 0, which is to be achieved by the logic circuit of the brake booster according to the present invention. A graph in which the relationship between the force output, that is, the amount of movement y is shown by a solid line, and this relationship in a conventional brake booster is shown by a dotted line. FIG. 8 is a diagram showing a control flow when a microcomputer is used for the logic circuit. FIG. 4 is a diagram showing the relationship between constituent elements of the present invention. l...Brake booster 1a...Negative pressure chamber 1b...
- Variable pressure chamber 1c... Retention spring 2... Power piston h... Power piston boss part 8... Input rod 4... Brake pedal 5
...Output lot 6...Master cylinder 7
...input sensor

Claims (1)

[Claims] 1. In a brake booster having a power piston that boosts the pedal force applied to the brake pedal and transmits it to the master cylinder, a working fluid source that supplies working fluid to a variable pressure chamber that operates the power piston via a control valve; an input sensor that detects an amount related to the input of the brake pedal; a depression speed detection means that detects the depression speed input to the brake pedal; an output sensor that detects a signal related to the output of the power piston; and both of the sensors. and logic for generating an output signal for controlling the control valve so that the output is a value corresponding to the depression speed based on a required functional relationship and the amount corresponding to the brake pedal input in response to a signal from the depression speed detection means. A brake booster characterized by comprising a circuit.