JPH064402B2 - Proportioning valve - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proportioning valve for controlling a rear wheel brake hydraulic pressure of a vehicle at a breaking point pressure increase.

[Background of the Invention]

Conventionally, various proportioning valves have been provided for controlling the rear wheel brake hydraulic pressure of a vehicle with respect to the front wheel brake hydraulic pressure to increase the pressure at the break point.

However, this type of conventional proportioning valve
The characteristic when the oil pressure rises is not the same as the characteristic when the oil pressure rises, and it usually exhibits a predetermined hysteresis.

The occurrence of such hysteresis causes a problem that the target rear wheel braking force characteristic deviates from the target characteristic of the rear wheel braking force when the braking operation is repeatedly increased and decreased. There is a problem in that the anti-skid control of the brake hydraulic pressure reduction and pressurization of the rear wheels cannot be obtained favorably when used in combination with For example, in a vehicle having an X piping brake system as one of the anti-skid control devices, in a so-called two-channel system in which one anti-skid control device is applied to one system, of course, it is used for controlling the rear wheel brake hydraulic pressure. An antiskid pressure reducing mechanism will be provided upstream of the proportioning valve used (on the master cylinder side), but in this case, the hydraulic pressure state that appears on the output side when the hydraulic pressure fluctuation on the input side of the proportioning valve rises or falls, This is because if it is different depending on the hysteresis, it means that the control of pressure reduction and pressurization by the antiskid pressure reduction mechanism cannot be conveniently transmitted to the rear wheel brake device.

[Object of the Invention]

The present invention has been made from such a viewpoint, and an object thereof is to provide a novel proportion that can obtain a constant hydraulic pressure state without hysteresis on the output side regardless of whether the hydraulic pressure fluctuation on the input side rises or falls. It is in the area of providing a training valve.

[Outline of Invention]

Thus, the proportioning valve according to the present invention made to realize such an object is characterized by the normally open communication passage between the input oil chamber communicating with the master cylinder and the output oil chamber communicating with the rear wheel brake device. And a hydraulic pressure balance mechanism that balances the hydraulic pressures of the input oil chamber and the output oil chamber at a predetermined ratio after closing the normally open communication passage. , A hydraulic pressure from the output oil chamber to move against the spring biasing force of the breaking spring to generate a break point generating piston, and the break point generating piston is moved by a fixed length, and is constituted by a valve seat, The hydraulic pressure balance mechanism includes a pressure reducing control piston which faces the output oil chamber with a large hydraulic pressure receiving area and a pressure reducing pressure piston which faces the input oil chamber with a small hydraulic pressure receiving area, and the pressure reducing control piston when the brake is not applied to the output chamber side. Constituted by a control spring for pressing biased, the pressure reduction control piston is provided with a hydraulic passage, said hydraulic passage is in place which is provided to form part of the normal Hirakiren passage.

Example of Invention

 The present invention will be described below based on embodiments shown in the drawings.

1 to 3 show a proportioning valve according to an embodiment of the present invention, and FIG. 1 shows a normal state (when not braking).
, FIG. 2 shows the state at the time of the occurrence of the break point, and FIG. 3 shows the state after the occurrence of the break point.

In these drawings, reference numerals 1 and 2 denote stepped large-diameter and small-diameter cylinders formed in the body, and the stepped cylinders 1 and 2 have stepped pressure reducing control pistons 3 each having a through inner cylinder. Are slidably engaged with each other, and are normally biasedly locked by a control spring 4 to a stationary position of the large diameter end. Reference numerals 5 and 6 denote piston cups for sealing the sliding surfaces of the pressure reducing control piston 3 and the cylinders 1 and 2.

The pressure reducing control piston 3 has a large-diameter end portion facing the output oil chamber B and a stepped portion facing the input oil chamber A, and these input oil chamber A and the output oil chamber B are hydraulic passages. They are connected to each other through the hole 3a and the radial passage 3b.

Reference numeral 7 denotes a break point generating piston, one end of which is slid into an inner cylinder cylinder 3c formed in the inner cylinder of the pressure reducing control piston 3, and the other end of the break point generating piston 7 is located inside the output oil chamber B. It has been extended. Reference numeral 7a denotes a valve body portion of a large-diameter flange formed on the other end portion of the folding point generating piston, and cooperates with the valve seat 8 fixed to the inner cylinder of the pressure reducing control piston 3 to communicate with the input oil chamber A. It constitutes a valve portion that shuts off (closes) communication between the output oil chambers B. Reference numeral 9 is a break point spring for pressing the break point generating piston 7 toward the output oil chamber B,
Reference numeral 10 denotes a stopper ring which is the limit position of the break point generating piston 7 pressed by the break point spring 9. 1
Reference numeral 1 is a piston cup for sealing the sliding surface between the break point generating piston 7 and the cylindrical cylinder 3c. It should be noted that one ends of the break point generation piston 7 and the pressure reducing control piston face the atmosphere chamber 12, respectively. The input oil chamber A communicates with a master cylinder (not shown), and the output oil chamber B also communicates with a wheel cylinder W / C of a rear wheel brake device (not shown).

Next, the operation of the proportioning valve configured as described above will be described. Each piston in the state of FIG. 1 when not braking is first transmitted to the pressure reducing control piston 3 to the right in the figure by transmission of brake hydraulic pressure. Power will act. That is, assuming that the large-diameter section cross-sectional area of the pressure reducing control piston 3 is A ₃ , the small-diameter section cross-sectional area is A ₂ , and the spring force of the control spring 4 is F, A ₃ × P → (A ₃ −A ₂ ) The force of P + F ₁ ← acts, and eventually the pressure reducing control piston 3 moves to the right while satisfying the relationship of A ₂ × P = F ₁ + R ₁ x (where R ₁ is a spring constant and x is a distance).

On the other hand, a force of A ₁ × P → F ₂ ← acts on the folding point generating piston 7 in both left and right directions in the figure, and A ₁ × P = F ₂ + R ₂ due to the relationship between the valve body 7a and the valve seat 8. (However, R ₂ is a spring constant) until the bending point generating piston 7 moves to the right relative to the pressure reducing control piston 3, and the valve body 7 a abuts on the valve seat 8 so that the input oil chamber A and the output oil chamber The communication with the chamber B is cut off (see FIG. 2).

Since the hydraulic pressure at this time becomes the breaking point hydraulic pressure value, this breaking point hydraulic pressure value is set to a desired value by appropriately determining the sectional area A _{1 of} the breaking point generating piston and the spring force of the breaking point spring 9. You can

After the communication between the input oil chamber A and the output oil chamber B is cut off by the above, the oil pressure increase ΔPb of the output oil chamber is different from the oil pressure increase ΔPa of the input oil chamber A while maintaining the cutoff relationship. Thus, the pressure reducing control piston 3 moves to the left at this time (see FIG. 3).

Considering the case where the oil pressure in the input oil chamber A is decreased in this state, the oil pressure in the output oil chamber is decreased (decompressed) by the movement of the pressure reduction control piston 3 according to the ratio. Therefore, there is no hysteresis between the output oil pressure and the input oil pressure, and as shown in FIG. 4, it changes along the same characteristic line when rising and when falling.

As described above, the proportioning valve of this example has the hydraulic balance mechanism (the pressure-reducing control piston 3 and the control spring 4) for balancing the change in the input and output hydraulic pressures after the occurrence of the break point at a predetermined ratio, and the break point generating mechanism (the break point generation mechanism). The combination with the point generation piston 7 and the break point spring 9) has an effect that it is possible to obtain a suitable break point pressure reduction control of the rear wheel brake hydraulic pressure without hysteresis.

〔The invention's effect〕

According to the present invention, the output-side pressure-reduced oil pressure is always obtained along a constant characteristic line with respect to the input-side oil pressure fluctuation (increase or decrease), and no hysteresis occurs. Brake oil pressure response characteristics can be obtained, and in particular, when this proportioning valve is applied to a two-channel antiskid control system, pressure reduction and pressurization that match the antiskid control of rear wheel brake oil pressure can be obtained. In addition, the combination of a pressure reducing control piston that faces the output oil chamber with a large hydraulic pressure receiving area and a small hydraulic pressure receiving area with the input oil chamber, and a control spring that biases this to the output oil chamber side Since the oil pressure balance mechanism is configured, the input oil chamber and the output oil chamber can be shared with the hydraulic pressure breaking mechanism, and it is not necessary to provide another oil chamber separately. In addition, the hydraulic pressure balance after the breaking point is determined only by the hydraulic pressure receiving area facing the input oil chamber and the output oil chamber of the control piston and not by the spring force of the control spring. There is also an effect that the setting of can be given stably.

[Brief description of drawings]

The drawings show an example of the outline of the configuration of the proportioning valve according to the present invention, and FIG.
FIG. 2 shows a break point and FIG. 3 shows a pressure reduction control. FIG. 4 is a diagram for explaining hydraulic control characteristics. 1, 2: Cylinder, 3: Decompression control piston, 4: Control spring, 5, 6, 11: Piston cup, 7: Break point generating piston, 8: Valve seat, 9: Break point spring, 10: Stopper ring, 12 : Atmosphere chamber.

Claims (1)

[Claims] 1. A hydraulic break point generating mechanism for closing a normally open communication passage between an input oil chamber communicating with the master cylinder and an output oil chamber communicating with the rear wheel brake device, and a closing point of the normally open communication passage. A hydraulic balance mechanism for balancing the hydraulic pressures of the input oil chamber and the output oil chamber at a predetermined ratio, wherein the hydraulic pressure breaking mechanism resists the spring biasing force of the breaking point spring by the hydraulic action from the output oil chamber. And a valve seat that is engaged by a fixed length movement of the folding point generating piston, and the hydraulic balance mechanism faces the output oil chamber with a large hydraulic pressure receiving area. A pressure reducing control piston that faces the input oil chamber with a small hydraulic pressure receiving area, and a control spring that biases the pressure reducing control piston toward the output oil chamber when the brake is not applied, and the pressure reducing control piston includes a hydraulic passage. Proportioning valve the hydraulic passage, characterized in that the form part of the normal Hirakiren passage.