JPH064403B2 - Proportioning valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a proportioning valve for controlling a rear wheel brake hydraulic pressure of a vehicle at a break point pressure reduction.

[Conventional technology]

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.

[Problems to be Solved by the Invention]

The occurrence of such hysteresis causes a problem of deviating from the target characteristic of the rear wheel braking force when the braking operation is repeatedly increased and decreased.
Particularly recently, there is a problem that when the anti-skid control device is used in combination with the anti-skid control device, the anti-skid control of the rear wheel brake hydraulic pressure cannot be preferably obtained. For example, in a vehicle having an X pipe 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 of the pipe systems, of course, it is for controlling the rear wheel brake hydraulic pressure. An anti-skid pressure reducing mechanism will be provided upstream of the proportioning valve (master cylinder side) that is used as an oil pressure control valve. If the state changes depending on the hysteresis, decompression by the anti-skid decompression mechanism,
This is because it means that the control of pressurization cannot be conveniently transmitted to the rear wheel brake device.

The present invention has been made from such a viewpoint, and an object thereof is to provide a new 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.

[Means for Solving the Problems]

Thus, the proportioning valve according to the present invention made to realize such an object is characterized in that the inside of the cylinder is divided into an output oil chamber communicating with the rear wheel braking device and an input oil chamber communicating with the master cylinder. A control piston having a seat and a valve body that faces the output oil chamber with a large hydraulic pressure receiving area, faces the input oil chamber with a small hydraulic pressure receiving area, and can engage / separate from the bab seat. And a break point spring that presses the piston toward the output oil chamber, and increases the oil pressure in the output oil chamber with respect to the oil pressure in the input oil chamber by the cooperation of the valve seat and the valve element when the control piston moves. In a proportioning valve, the valve seat is slid on the cylinder,
The break point spring is supported by a pressure reducing control piston that is provided so as to be movable in the same axial direction as the control piston, and the break point spring includes a first spring stretched between the pressure reducing control piston and the pressure reducing control piston. It is composed of a combination of a second spring stretched between the cylinder walls.

[Action]

According to the above configuration, the hydraulic pressures of the input oil chamber and the output oil chamber are controlled to be reduced regardless of the operating states of the valve seat and the valve body that cooperate to perform the hydraulic pressure increase control between the input oil chamber and the output oil chamber. Will be given by the piston.

〔Example〕

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

In the figure, 1 is a large diameter cylinder formed in the body, and 2 is a concentric small diameter cylinder. Reference numeral 3 denotes a sleeve type pressure reducing control piston (hereinafter referred to as a sleeve piston) which is slidably fitted in the large diameter cylinder 1 so as to be movable in the axial direction. In the output oil chamber B facing the end face on the one end side by the valve seat 5 mounted on the end face on the one end side in the direction
And the input oil chamber A facing the other end surface on the opposite side. Reference numeral 4 denotes an inner cylinder passage formed as an inner cylinder of the sleeve piston 3 for communicating the input / output oil chambers A and B. Further, the sleeve piston 3 includes a first break point spring 7 stretched between the one end surface and a large-diameter head portion of a control piston 9, which will be described later, and between the other end surface and a stepped wall surface of the cylinder. The second bending point spring 8 which is stretched is balanced by the spring force and positioned as shown in the figure.

The control piston 9 has a large-diameter head on one end side located in the output oil chamber B, and the valve element formed on this large-diameter head is
The valve body 10 is opposed to the valve seat 5 so that the valve body 10 engages with the valve seat 5 to shut off between the input / output oil chambers A and B when the valve seat 5 moves. The other end of the control piston 9 is connected to the sleeve piston 3
The inner cylinder passage 4 and the input oil chamber A are inserted into the small-diameter cylinder 2 so as to be slidably fitted therein and to face the atmosphere chamber 11. Reference numeral 12 is a piston cup that oil-tightly seals the sliding surfaces of the control piston 9 and the small diameter cylinder 2.

The input oil chamber A in this example is a master cylinder (not shown).
The output oil chamber B is also in communication with the wheel cylinder W / C of the rear wheel brake device (not shown).

Next, the operation will be described.

The state shown in the drawing shows the state when the brake is not applied, and the control piston 9
The valve body 10 is separated from the valve seat 5 by the first break point spring 7, so that the input / output oil chambers A and B are maintained in a communicating state. The sleeve piston 3 is stationary at a position shown in the figure in which the spring forces of the first and second break point springs 7 and 8 are balanced.

When the brake operation is performed, hydraulic pressure is transmitted to the input oil chamber A, and this hydraulic pressure is transmitted to the rear wheel brake device through the output oil chamber B through the gap between the valve element 10 and the valve seat 5 in the open circuit state.

And In conjunction to the hydraulic pressure rise during this, oil pressure area in the right direction in the figure shown in the control piston (A ₃ -A ₁₎ acts,
When this overcomes the combined spring force of the first and second break point springs 7 and 8, the control piston 9 will move to the right. At this time, the sleeve piston 3 also moves to the right so as to balance the spring forces of the compressed first and second break point springs 7 and 8, but in the relative relationship between the sleeve piston 3 and the control piston 9. The valve body 10 approaches the valve seat 5 by the amount of compression of the first break point spring 7.

After this, the transmitted hydraulic pressure further increases, and the first break point spring 7
When the compression of the valve seat 10 becomes sufficiently large, the valve body 10 moves the valve seat 5
And the communication between the input / output oil chambers A and B is cut off.
The breaking point hydraulic pressure value Pc at this time is the initial spring forces F ₁ and F _{2 of} the first and second breaking point springs 7 and 8 and the spring constant k.
₁ and k ₂ , the respective compression amounts x ₁ and x _2, and the cross-sectional area A ₁ of the small diameter cylinder 2, Given as.

Thereafter, when the hydraulic pressure in the input oil chamber A is further increased, the control piston 9 and the sleeve piston 3 are linked to each other as a whole.
The following forces act in the left-right direction in the figure, and the control piston 9 and the sleeve piston 3 cause left movement so as to maintain these balances.

→ ΔP _B × A ₂ ← ΔP _A × (A ₂ −A ₁ ) k _{2 2} Therefore, the oil pressure rise in the output oil chamber B (However After the breaking point, the reduced pressure rise of tan θ <1 can be obtained with the valve body 10 and the valve seat 5 kept in contact with each other.

Since such control of the output oil pressure break point depressurization increase is maintained in exactly the same relationship both when the oil pressure in the input oil chamber rises and when it falls, the obtained output oil pressure The point depressurization control characteristic line does not draw a hysteresis, a preferable control characteristic is secured, and a preferable control response of the rear wheel braking force is realized.

〔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, especially when this proportioning valve is applied to a 2-channel anti-skid control system, it is possible to obtain pressure reduction and pressurization that match the anti-skid control of rear wheel brake oil pressure. , Its usefulness is great.

[Brief description of drawings]

The drawing is a diagram showing an example of a schematic configuration of a proportioning valve according to the present invention. 1, 2: Cylinder, 3: Sleeve piston 4: Inner cylinder passage, 5: Valve seat 6: Piston cup, 7: First break point spring 8: Second break point spring 9: Control piston 10: Valve body, 11: Atmosphere chamber 12: Piston cup

Claims (1)

[Claims] 1. A valve seat for partitioning the inside of a cylinder into an output oil chamber communicating with a rear wheel brake device and an input oil chamber communicating with a master cylinder, and a large hydraulic pressure receiving area facing the output oil chamber and inputting the same. A control piston having a valve body that faces the oil chamber with a small hydraulic pressure receiving area and can be fitted / separated from the valve seat; and a break point spring that presses the control piston toward the output oil chamber, In a proportioning valve, which cooperates with the valve seat and the valve element when the control piston moves to raise and lower the hydraulic pressure of the output oil chamber to the hydraulic pressure of the input oil chamber at a break point, the valve seat is slidably engaged with the cylinder. While being supported by a decompression control piston provided so as to be movable in the same axial direction as the control piston, the break point spring is
A proportioning valve comprising a combination of a first spring stretched between the pressure reducing control piston and the control piston and a second spring stretched between the pressure reducing control piston and the cylinder wall.