JPH063730Y2 - Pressure reducing valve for two-system braking circuit with failure compensation function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a two-system pressure reducing valve for approximating a braking force distribution of a vehicle having two systems of braking circuits to an ideal state.

[Conventional technology and its problems]

2. Description of the Related Art There is widely known a so-called antilock device that controls a slip state of a wheel by detecting a rotational speed of a wheel during braking and automatically adjusting a braking force separately from a braking force generated by a driver. On the other hand, from a safety point of view, it is common to use two independent braking circuits for the vehicle, and II piping that divides the front wheel system and the rear wheel system, and one of the left and right wheels of the front wheel system and the rear wheel system as an independent circuit. X piping, JJ
Various piping types such as piping are applied. Further, in order to approximate the braking force distribution of the front and rear wheels of the vehicle to an ideal state, a pressure reducing valve that reduces the input pressure above a certain pressure (break point) and outputs it is provided between the pressure generation source and the rear wheel brake. In particular, when there are two systems for connecting the pressure generation source and the rear wheel brake, such as the X pipe and the JJ pipe, a pressure reducing valve is provided for each of them. In addition, when one of the two systems fails due to liquid leakage or the like and pressure does not increase, the output pressure of the pressure reducing valve of the surviving system can be made higher than that in the normal state to increase the reached deceleration. Common, in which case 2
The pressure reducing valve of the system is arranged in one casing and the input pressures introduced into each system are compared to increase the output pressure of the pressure reducing valve on the survival side when one system fails, so-called failure compensation function A two-system pressure reducing valve with an attached valve is widely known, and a number of methods have been proposed, including Japanese Utility Model Publication No. 57-36521.

On the other hand, when the antilock device is applied to a vehicle having X pipes or JJ pipes in which there are two systems of pipes connecting the pressure generation source and the rear wheel brakes, the four wheels of the antilock device modulator that adjusts and outputs the input pressure are output. There is a 4-channel system that is installed immediately before each brake, and a rear-wheel brake is a 2-channel system that aims at economic effects, in addition to the 3-channel system that connects the brakes of the left and right wheels by one modulator and adjusts them at the same time. .

As one example, a so-called two-channel system in which a modulator of an antilock device that connects left and right wheels of front wheels and rear wheels is provided as a front wheel system and a rear wheel system for a vehicle with X piping and the braking wheels are divided into front and rear The method is known.

In this case, the braking pressures of the left and right rear wheels are controlled by one modulator at the same time. Therefore, if a pressure reducing valve with a failure compensation function is provided between the pressure source and the rear wheel control modulator, this modulator and rear Even if it is installed between the wheel brakes, the input pressure of the pressure reducing valves for the left and right wheels is controlled by the same modulator, so the failure compensating function of the pressure reducing valve is exerted during normal antilock activity. There is no problem with this.

However, in such a two-channel type anti-lock device that simultaneously controls the front and rear left and right wheels, when the left and right wheels are controlled on the road surface having different friction coefficients, one of the wheels is controlled. Since the braking pressures of both the left and right wheels are controlled simultaneously by paying attention to it, optimal control is not performed on the non-focused side.
There are problems in the direction stability of the vehicle body, maneuverability, stopping distance, etc. Therefore, as a two-channel anti-lock control for the X pipe, after the hydraulic pressure generated in one hydraulic chamber of the pressure generation source passes through the modulator of the anti-lock device, it is branched to the front wheel system and the rear wheel system, one of which is on one side. It has been proposed to directly guide the front wheel brake to the other side through the pressure reducing valve to the rear wheel brake on the other side and configure the other system in exactly the same manner. In this case, since the front wheels, which have a large share of the braking force, can be controlled independently on the left and right sides, the above problem is solved.

However, in the case of this method, the hydraulic pressures of the two systems are independently controlled after passing through the modulator, so that the hydraulic pressures of the two systems generated in the two hydraulic chambers of the pressure generation source are substantially equal under normal conditions. Even when the antilock control is started by at least one of the modulators of the two systems, the input pressures of the pressure reducing valves of the respective systems have different values, and the antilock control is maintained while the antilock control is maintained. The difference between the two systems of the input pressure of the pressure reducing valve of the system will vary greatly. Therefore, if the pressure reducing valve of each system is the two-system pressure reducing valve with the failure compensating function described above, the failure compensating function works intermittently during the antilocking operation even during normal operation, and the braking pressure of the rear wheels is extremely high. There is a problem that the value becomes irregular and antilock control becomes extremely difficult. This problem is not limited to the case of the X pipe, but is a problem common to the case of having two braking circuits in which the output pressure from the modulator of the antilock device is introduced into the brake through the pressure reducing valve like the JJ pipe. In this case, in order to avoid the above-mentioned problem, it is possible to remove the failure compensating function from the pressure reducing valve so that even if one system fails, the pressure reducing valve on the survival side outputs the same pressure as in the normal state. However, this causes a problem that the braking force distribution is largely separated from the ideal distribution when one system fails, and the arrival deceleration is low.

The present invention is intended to solve such a problem, and in the normal state, the irregularity of the braking pressure due to the operation of the antilock device does not occur, and the surviving side is not affected when one system fails. Provided is a pressure reducing valve for a two-system braking circuit having a failure compensation function, which is suitable for increasing a braking pressure of a brake connected to the pressure reducing valve to a higher deceleration than in a normal state to obtain a higher deceleration.

[Means for solving problems]

In order to achieve such an object, in the present invention, in the two-channel antilock control having two braking circuits, the front wheel system is directly controlled from the pressure generation source through the modulator of the antilock device, and the rear wheel system is the output of the modulator. The control pressure of the pressure reducing valve is led to the brake via the pressure, and the failure state is not detected only by the differential pressure of the rear wheel system, and the differential pressure piston means for detecting the differential pressure between the pressure source and the modulator is provided. It was As a result, it is possible to detect the 1-system failure state regardless of the operation of the modulator of the anti-lock device, and the false detection of the 1-system failure state due to the differential pressure between the 2 systems accompanying the operation of the modulator can be detected regardless of the normal state. It has become possible to prevent it. Next, the pressure of the two systems adjusted by the modulator of the anti-lock device is introduced from the first inlet of the pressure reducing valve for the two-system braking circuit, and a pressure reducing valve for reducing and outputting both of them is independently provided. By providing bypass paths in parallel to the two systems of pressure reducing valves, and when both systems are normal by the failure detection means, the two systems of bypass paths are both closed, and only when one system fails, there is a survival side. The bypass route of the system was opened.

As a result, the braking pressure of the brake that leads the output pressure to the rear wheel system of the pressure reducing valve of the surviving system can be made much higher than that in the normal state only when one system fails, and the above object can be achieved. .

〔Example〕

FIG. 1 shows a normal state. According to the configuration of the present invention, the pipe of one system of the pressure generation source 1 is connected to the second pressure reducing valve 2 for two systems.
Of the inlet PM _1, connect the other to PM _2, together with the action to face the hydraulic differential pressure piston 3, the rear output hydraulic pressure modulators 4 and 5 of the anti-lock device between the front wheel system 6 wheels system
Branched to 10 and 11, the first inlet on one side of the two-system pressure reducing valve 2.
The purpose is to introduce the other into PI ₁ and the other into PI ₂ , reduce the pressure with pressure reducing valves 8 and 9, and supply the pressure to rear wheel brakes 10 and 11.

The differential pressure piston 3 is stationary at a neutral position in a normal state, and the bypass passages 12 and 13 provided in parallel with the pressure reducing valves 8 and 9 are shut off by 0-rings 14a, 14b, 14c, 14d and 14e which are sealing means. ing. The cross-sectional area of the differential pressure piston 3 has a relation of A>B> C, and the neutral position is maintained by the balance of PM ₁ · C <PM ₂ · B and PM ₁ · A> PM ₂ · B across the sleeve 15. , Modulator 4.
Even if the first inlet pressures PI ₁ and PI ₂ from 5 become unbalanced, this state is maintained because PI ₁ and PI ₂ are never higher than PM ₁ and PM ₂ .

When the right system fails, the differential pressure piston 3 moves to the right as shown in FIG. 2, the left bypass passage 12 is opened, and the first inlet pressure PI ₁ is reduced by the pressure reducing valve 8. Instead, it will be supplied to the rear wheel brake 10.

When the left system fails, the differential pressure piston 3 moves to the left as shown in FIG. 3, the right bypass passage 13 is opened, and the first inlet pressure PI ₂ is reduced by the pressure reducing valve 9. Instead, it is supplied to the rear wheel brake 11.

In any of the above cases, the differential pressure piston 3 is in the state of FIG. 2 or FIG. 3 until the failure is repaired, but after the failure is repaired, the sectional area ratio A <B <C of the differential pressure piston 3 is raised by the first pressurization. The function of the sleeve 15 and the sleeve 15 restores the neutral position as shown in FIG.

FIG. 4 shows that the pressure reducing operation starting pressure control spring 16 of the pressure reducing valves 8 and 9 of the two systems is common, the cam surface 17 is provided on the differential pressure piston 3, and the tip of the warning switch 18 is brought into contact with this.
The failure information is detected as an electric signal. In this case, since the differential pressure piston 3 maintains the position at the time of the failure until the first pressurization after the failure is repaired, the failure information can be intermittently monitored.

In addition, if the pressure reducing valve 2 for the two-system braking circuit of the present invention is provided integrally with the modulators 5 and 6 of the antilock device, there is an advantage that the entire device can be made smaller and lighter.

[Brief description of drawings]

1 shows a normal state, FIG. 2 shows a right side system failure, and FIG. 3 shows a left side system failure. FIG. 4 is a schematic sectional view of another embodiment in which a cam surface is provided on the differential pressure piston and a warning switch is provided. 1 ... Pressure source 2 ... Pressure reducing valve for 2-system braking circuit 3 ... Differential pressure piston 4, 5 ... Modulator of antilock device 6, 7 ... Front wheel brake 10, 11 ... Rear wheel brake 12, 13 ...... Bypass 15 ...... Sleeve 18 ...... Warning switch

Claims (1)

[Scope of utility model registration request] 1. A pressure reducing valve for a two-system braking circuit having two pressure reducing valves for reducing an input pressure introduced from a first inlet and outputting the pressure from an outlet to a rear wheel system, wherein: A differential pressure piston slidable in the receiving axial direction so that the pressures of the respective systems introduced from the second inlet are opposed to each other in the axial direction; A modulator of an antilock device that adjusts the pressure from a pressure generation source and outputs the pressure to the front wheel system of each system, and the pressure reduction between the first inlet and the outlet that communicate with the output of the modulator. A bypass passage provided in each system communicating in parallel with the valve; and a seal means provided in the differential pressure piston that opens and closes each bypass passage; and each system introduced from the second inlet To the pressure of When pressure is generated differential pressure piston is moved to the failure side, failure compensation function with dual brake circuit pressure reducing valve, characterized in that so as to open the bypass passage survival side.