JPS6247749B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a system for reducing the brake pressure of a vehicle by reducing the brake pressure of the rear wheels to a fixed proportion of the brake pressure of the front wheels when the brake pressure of the vehicle exceeds a certain value. Regarding a control device.

Conventionally, this type of valve has been installed in a pipe connecting a master cylinder and a wheel cylinder, and has a valve body biased by a valve spring, and a supply/discharge valve that is slidably fitted into a cylinder. It has a piston that is movable so as to engage with the valve body in order to open and close the supply/discharge valve in response to an acting force, and a spring that urges the piston in a direction in which the supply/discharge valve opens.
It has been proposed that the pressure on the wheel cylinder side is controlled to be reduced compared to the pressure on the master cylinder side within a range exceeding a predetermined pressure based on the spring force of the spring,
It is used to reduce and control the brake pressure on the rear wheels.

However, when the front wheel brake system is out of order and the front wheel brake pressure is less than necessary, reducing the rear wheel brake pressure in this way is dangerous because the total braking force will be insufficient. Therefore, when the master cylinder pressure exceeds the corner pressure, the present invention provides a brake pressure control device that reduces the brake pressure of the rear wheels to a fixed proportion of the master cylinder pressure by the amount that exceeds the break point pressure. The purpose is to make it possible to apply
To achieve this purpose, the valve body can be attracted by magnetic force, and the distance between the maximum amount of movement of the valve body to the side opposite to the piston and the distance between the valve body and the piston when not in operation is The sum of the distances is set to be larger than the maximum amount of movement of the piston toward the valve body, and the valve body is arranged opposite to the piston, and the valve body is moved against the valve spring by magnetic force. an electromagnet that attracts to a side opposite to the piston side;
A failure detection device capable of exciting the electromagnet is provided.

By doing so, the present invention achieves the following effects. In other words, even if a failure causes insufficient braking force, when the electromagnet is energized by the failure detection device, the valve body is attracted by the electromagnet and moves beyond a predetermined amount.
Even if the piston moves under pressure, it will not sit against the valve body and close the supply valve.
The hydraulic pressure supplied from the master cylinder to the wheel cylinders is supplied without being reduced in pressure, thereby preventing insufficient braking force. In addition, the load on the valve spring that biases the valve body is extremely small compared to the spring that biases the piston, so when trying to attract the valve body with an electromagnet, the attraction force of the electromagnet must not be large. The valve body can be sufficiently attracted by a predetermined amount, the electromagnet can be made small, and the operational response can be ensured.

The embodiment shown in FIG. 1 will be described below.

A master cylinder 2 discharges brake pressure fluid of the same pressure from its discharge ports 6 and 8 when the brake pedal 4 is depressed. 10 is a wheel cylinder for the front wheel, and a discharge port 6 of the master cylinder 2
The pressure liquid discharged from the pipes 12 and 14 is received through the pipes 12 and 14. 16 is a rear wheel cylinder,
The pressure liquid discharged from the discharge port 8 of the master cylinder 2 is received through the pipes 18, 20, and 22. 24 is a brake system failure alarm device, which connects pipes 12 and 1.
If the front wheel brake system on the 4th side is malfunctioning, the lamp 2 will turn on.
6 is turned on, and when the rear wheel brake system on the conduits 18, 20, 22 side is out of order, a lamp 27 is turned on to warn the driver of the failure. 28 is a brake pressure control valve, which has an input port 32 in the main body 30 and an output port 36 in the cap 34 screwed into the main body 30, and connects the brake system failure alarm device 24 and the rear wheel via pipes 20 and 22, respectively. It is connected to the wheel cylinder 16. 38 is a rod, and the main body 30
The cylinder 4 in the main body 30 is rotated by a spring 44 stretched between the tip of the pin 40 and a shaft device 42.
6, 48 is pushed to the right. The piston 50 is provided with a through hole 51 and one end thereof is connected to the cylinder 46 , and the cylinder 46 is connected to the output port 36 . This brake pressure control valve 28 is attached to the vehicle body, and as the weight of the vehicle increases, the distance from the shaft device 42 becomes shorter.
The installation length of the rod 38 becomes shorter, its tensile force becomes smaller, and the force with which the rod 38 pushes the piston 5 becomes smaller.
The diameter of the cylinder 48 is made smaller than the diameter of the cylinder 46, so that the through hole 51 of the piston 50
When the supply/discharge valve is closed, the wheel cylinder pressure of the rear wheels decreases at a constant rate with respect to the master cylinder pressure which is higher than the corner pressure. A hole 52 is provided on the right side of the cylinder 48 and connected to the input port 32, and a retaining ring 54 holds a solenoid valve 56, springs 58, 60, and a plate 62 inside. The solenoid valve 56 has a valve body 64 and a solenoid 6.
6, a valve stem 68, a valve spring 70, a valve stem support plate 72, etc. The spring 58 is located between the valve body 64 and the plate 62.
The springs 60 are provided between the valve stem support plate 72 and the plate 62, respectively, and bias the solenoid valve 56 and the plate 62 apart. The left end of the valve stem 68 made of a magnetic material forms a valve seat 76 for the supply/discharge valve 74 at the open portion of the through hole 51 at the right end of the piston 50 . Further, the plate 62 engages with the piston 50 and transmits the biasing force of the springs 58 and 60 to the piston 50. 78 is a rubber boot to protect from dust.

Note that a sufficient margin is formed on the right end side of the valve stem 68, and the distance between the valve seat 76 at the left end of the valve stem 68 and the valve 74 at the right end of the piston 50 when not in operation,
The sum of the amount of movement of the valve stem 68 to the right is the amount of movement of the piston 5
0 (the maximum amount of movement that can be made without being restricted by members such as the main body 30, the valve stem support plate 72, and the rod 38).

In the non-braking state, no brake pressure is generated in either system, and the brake pressure control valve 28 is in the state shown. That is, the plate 62 is biased to the left by the springs 58 and 60, the piston 50 engages with the plate 62, and the supply/discharge valve 74 and valve seat 76 are spaced apart.

Next, the operation of this brake pressure control valve 28 will be explained with reference to FIGS. 1 and 2. In FIG. 2, the horizontal axis shows the master cylinder pressure, and the vertical axis shows the wheel cylinder pressure of the rear wheels. In this state, when you step on the pedal 4 of the master cylinder 2 to apply the brakes, brake pressure is generated in both systems, and the brake pressure control valve 28 has the discharge port 8 of the master cylinder 2, the pipe line 18, and the brake system malfunction. Brake pressure fluid flows into the input port 32 through the alarm device 24 and the conduit 20. The brake pressure fluid then flows through holes 52, 51,
It exits the brake pressure control valve 28 through the cylinder 46 and the output port 36, and flows through the pipe 22 into the wheel cylinder 16 of the rear wheel. As the brake pressure increases, the piston 50 moves toward the cylinder 46.
The force due to the area difference between It hits the seat 76 and closes. The brake pressure at this time is the corner pressure (Fig. 2)
A ₁ , A ₂ , A ₃ points). Until now, the wheel cylinder pressure was equal to the master cylinder pressure (see Figure 2 O-
_A1 , O- _A2 , O- _A3 ). When the master cylinder pressure further increases, the piston 50 moves to the left due to the pressure, opens the supply/discharge valve 74, and the pressure on the wheel cylinder side increases. When the wheel cylinder pressure reaches a pressure determined by the size relationship between the inner diameters of the cylinders 48 and 46, the piston 50 moves to the right again and closes the supply/discharge valve 74. At this time, the wheel cylinder pressure is a certain proportion of the master cylinder pressure (approximately the cylinder 40 and 4
(area ratio of 8) (Fig. 2 A ₁
−B ₁ , A ₂ −B ₂ , A ₃ −B ₃ ). When the weight of the vehicle is large, the force of the rod 38 pushing the piston 50 is weak as described above, and the amount of reduction in the reaction force of the spring 58 and the spring 60 against the piston 50 is small, so the corner pressure becomes large and the weight increases. Accordingly, it changes from A ₁ to A ₂ and A ₃ (Fig. 2).

When the brake system failure alarm device 24 operates to warn of a failure in the front wheel brake system, current flows through the resistors 80 and 82, so that the power transistor 84 becomes conductive and the lamp 26 lights up, thereby controlling the brake pressure. The solenoid 66 of the valve 28 is energized.
Then, the valve rod 68 moves to the right, and in this state, no matter how the piston 50 moves, the supply/discharge valve 74 will not sit on the valve seat 76, and the brake pressure on the rear wheels will not decrease.

According to the above-described embodiment, by energizing the solenoid valve 56, the pressure reduction control is canceled and the pressure generated in the master cylinder 2 is directly transmitted to the rear wheel cylinder 16, thereby resolving the lack of braking force. Since the brake system failure alarm device 24 is activated to notify the failure of the brake system, it is possible to sufficiently confirm safety during driving.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a brake pressure control device according to the present invention, and FIG. 2 is a performance diagram thereof. 56... Solenoid valve, 68... Valve stem, 74... Supply/discharge valve, 76... Valve seat.

Claims (1)

[Claims] 1 A supply/discharge valve is installed in a conduit connecting a master cylinder and a wheel cylinder, and has a valve body biased by a valve spring. a piston movable to engage the valve body to open and close the valve;
and a spring that urges the piston in the direction in which the supply/discharge valve opens, and reduces the wheel cylinder side pressure compared to the master cylinder side pressure within a range exceeding a predetermined pressure based on the spring force of the spring. In the brake pressure control device to be controlled, the valve body can be attracted by magnetic force, and the distance between the maximum movement amount of the valve body to the side opposite to the piston side and the valve body and the piston when not in operation is provided. The sum of the distances is made larger than the maximum movement amount of the piston toward the valve body, and the valve body is arranged opposite to the piston, and the valve body is moved against the valve spring by magnetic force. A brake pressure control device that includes an electromagnet that attracts the piston to a side opposite to the piston side, and a failure detection device that can excite the electromagnet.