JPH0247090Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a proportioning valve for controlling the rear wheel brake hydraulic pressure of a vehicle to reduce and increase pressure at a turning point.

[Background of the idea]

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

However, conventional proportioning valves of this type do not have the same characteristics when the oil pressure is rising as when they are falling, and they usually exhibit a certain amount of hysteresis. The occurrence of such hysteresis causes the problem that the rear wheel braking force deviates from the desired characteristic when the brake operation is repeatedly increased and decreased. When used in combination, there is a problem in that anti-skid control of rear wheel brake hydraulic pressure reduction and pressure increase may not be achieved favorably. For example, in a vehicle that has an X-piped brake system as one type of anti-skid control device, in a so-called two-channel system in which one anti-skid control device is applied to one system, it is naturally used to control the rear wheel brake hydraulic pressure. An anti-skid pressure reducing mechanism will be provided upstream of the proportioning valve (on the master cylinder side), but in this case, the oil pressure state that appears on the output side due to the rise and fall of oil pressure fluctuations on the input side of the proportioning valve will be as described above. This is because if the difference is due to hysteresis, it means that the control of pressure reduction and pressure increase by the anti-skid pressure reduction mechanism is not conveniently transmitted to the rear wheel brake device.

[Purpose of the invention] The present invention was made from this perspective,
The purpose is to provide a new proportioning valve that can obtain a constant hydraulic pressure state without hysteresis on the output side, regardless of whether the oil pressure fluctuation on the input side increases or decreases.

[Summary of the idea]

The characteristic of the proportioning valve of the present invention, which was developed to achieve this purpose, is that one end in the axial direction faces the input oil chamber communicating with the master cylinder with a small hydraulic pressure receiving area, and the other end faces the input oil chamber communicating with the master cylinder. A pressure reduction control piston movable in the axial direction facing an output oil chamber communicating with the wheel brake device, a corner spring that presses the pressure reduction control piston toward the output oil chamber, a cylinder fixing part in the output oil chamber and opposing thereto. and a valve piston positioned between the cylinder fixing portion and the opposite end of the pressure reduction control piston and positioned by a pair of balance springs on both sides stretched between the cylinder fixing portion and the opposite end of the pressure reduction control piston. The pressure reduction control piston and the valve piston have a communication path that normally communicates between the input oil chamber and the output oil chamber, and this communication path is shut off when the pressure reduction control piston moves toward the input oil chamber. However, when moving in the direction of the output oil chamber, a cooperative opening/closing valve section is provided that communicates with this communication passage.

[Example of idea]

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

In the figure, reference numerals 1 and 2 are stepped cylinders with concentric and different diameters, and a stepped pressure reduction control piston 3, which is cylindrical with one end open on the large diameter side, is slidably fitted to the stepped cylinders 1 and 2. , the small-diameter end portion fitted into the small-diameter cylinder 2 faces the atmospheric chamber 8 . Reference numeral 4 denotes a corner spring that presses and biases the pressure reduction control piston 3 toward the large diameter end. Further, 5 is a piston cup that oil-tightly seals the sliding surfaces of the small-diameter portions of the small-diameter cylinder 2 and the stepped control piston, and 7 is an oil-tight seal for the sliding surfaces of the large-diameter portions of the large-diameter cylinder 1 and the stepped control piston 3. This is an O-ring.

In addition, a valve seat 6 that cooperates with a valve body 10 of a valve piston 9 (described later) is assembled and fixed in the cylinder of the stepped control piston 3 so as to face the bottom of the inner cylinder. The input oil chamber A of the cylinder stepped portion communicates with the cylinder interior 3a through the radial flow path 3b, and the output oil chamber B faces the large diameter end of the pressure reduction control piston 3. It's summery.

The valve piston 9 is generally housed in the cylinder of the pressure reduction control piston 3 and is connected to a first balance spring 11 stretched between the bottom of the inner cylinder of the pressure reduction control piston 3 and one end of the valve piston, and The valve piston is positioned at a position where the spring forces are balanced by the spring forces of the second balance spring 12 stretched between the end wall and the other end of the valve piston. In addition, the valve piston 9 of this example
When the brake is not applied (the state shown in the figure), one end is engaged with the bottom of the inner cylinder of the pressure reduction control piston 3, and the large diameter valve body 10 facing the valve seat 6 is connected to the valve seat 6 by a certain length δ. They are now separated by _O. Therefore, in this state, the input oil chamber A and the output oil chamber B are in communication with each other.

Next, we will discuss its operation.

When brake oil pressure is transmitted from the master cylinder M/C to the input oil chamber A due to a brake operation, this oil pressure is transferred to the output oil chamber B and then to the rear wheel brake through the open/close valve section (consisting of the valve body 10 and the valve seat 6) which is in an open circuit state. transmitted to the device.

Due to such hydraulic pressure transmission, a hydraulic pressure of P×S ₃ acts on the pressure reduction control piston 3 as a power on the right side in the figure, according to the area relationship shown in the figure. The right power of this pressure reduction control piston 3 is transmitted to the corner spring 4 and the pair of balance springs 11 and 12.
When the leftward biasing force of the pressure reduction control piston 3 given by the spring force relationship is exceeded, the pressure reduction control piston 3 moves to the right, and along with this, the tension length of the pair of balance springs changes. Since the valve piston 9 also becomes longer, the valve piston 9 will also move slightly to the right.
Relatively, the pressure reduction control piston 3 moves to the right with respect to the valve piston 9.

When such relative movement amount reaches the initial separation between the valve seat 6 and the valve body 10 of the above-mentioned constant length δ _O due to an increase in oil pressure, the valve body 10 comes into contact with the valve seat 6, and therefore the input oil The communication between chamber A and output oil chamber B is cut off, which causes the hydraulic pressure break point of the output oil chamber to
This will result in P _C.

After this, when the oil pressure in the input oil chamber A further increases, the force acting on the valve piston 9 in the horizontal direction in the figure is (ΔP _A −ΔP _B )×S ₂ +F ₁ >F ₂ +R ₂ x (where ΔP _A : Hydraulic pressure increase in input oil chamber A ΔP _B : Output ``B ″ ″ ″ F ₁ , F ₂ : Spring force of the first and second balance springs (when a break point occurs) R ₂ : Pressure of the second balance spring By setting the spring constant x: amount of movement after the break point), the state of contact between the valve body 10 and the valve seat 6 is maintained and continued, and therefore the valve piston 9 is substantially integrated. The following forces will act on the reduced pressure control piston in the left and right directions.

_{ΔP A} × (S _{1 −} S _{3 )} − _R (= K _BR ×ΔP _B /S ₁ )) Here, let us assume that the variation in force due to the spring force of the corner spring 4 and the second balance spring 12 is
_{Assuming that F ​ ​ ​ ​ ​} This relationship is given as input oil chamber A.
The same holds true even when the oil pressure drops, so that, as shown in FIG. 2, the change in the output oil pressure P _B in the output oil chamber B after the oil pressure break point is given without any hysteresis.

Therefore, by using such a proportioning valve, control responsiveness of the rear wheel brake hydraulic pressure can be conveniently obtained, and in particular, it is possible to obtain an effect showing favorable adaptability to the above-mentioned two-channel type anti-skid control system.

[Effect of idea]

According to the present invention, in response to oil pressure fluctuations (rise, fall) on the input side, the output side pressure reduction control is always obtained along a constant characteristic line, and hysteresis does not occur, so the rear wheels can be maintained in good condition. The response characteristics of the brake oil pressure can be obtained, and especially when this proportioning valve is applied to a two-channel anti-skid control system, it is possible to obtain pressure reduction and increase that match the anti-skid control of the rear wheel brake oil pressure. Its usefulness is great.

[Brief explanation of the drawing]

The drawings are for illustrating an example of the configuration of the proportioning valve according to the present invention.
The figure is a longitudinal sectional view, and FIG. 2 is a characteristic diagram of the control oil pressure. 1...Large diameter cylinder, 2...Small diameter cylinder, 3
...Decompression control piston, 4...Break point spring,
5...Piston cup, 6...Valve seat, 7
... O-ring, 8 ... Atmospheric chamber, 9 ... Valve piston, 10 ... Valve body portion, 11 ... First balance spring, 12 ... Second balance spring.

Claims (1)

[Scope of utility model registration request] An axially movable pressure reduction control piston whose one axial end faces an input oil chamber that communicates with the master cylinder with a small hydraulic pressure receiving area, and whose other end faces an output oil chamber that communicates with the rear wheel brake system, and this pressure reduction control piston. a corner spring that presses the piston toward the output oil chamber;
A pair of counterbalances on both sides are disposed between the cylinder fixing part in the output oil chamber and the end face of the pressure reduction control piston opposite thereto, and are stretched between the cylinder fixing part and the opposite end of the pressure reduction control piston, respectively. a valve piston positioned by a spring; the pressure reduction control piston and the valve piston normally have a communication passage communicating between the input oil chamber and the output oil chamber; A proportioning valve characterized by being provided with a cooperative opening/closing valve section that blocks this communication passage when moving in the direction of the input oil chamber and communicates with this communication passage when moving in the direction of the output oil chamber.