JPS6344584B2 - - Google Patents

Description

[Detailed Description of the Invention] In recent years, braking systems that divide the rear wheel brakes of automobiles into two systems (for example, what is usually called cross piping or diagonal piping) have come into widespread use, and The development of brake pressure control valves has progressed, and various forms such as parallel type and skewer type have already been proposed. However, since it is easy to create a so-called load-responsive control valve that automatically adjusts the actuation start point control force according to the load condition of the vehicle via a link mechanism, a type with one actuating spring at one end is preferred. There is.

On the other hand, as a two-system controlled dynamic pressure control valve, it is desired that when one system fails, the remaining one system will reduce the rear wheel pressure reduction effect compared to when it is normal, that is, the activation start point will rise, the pressure reduction ratio will rise, and it will become inoperable. has been done.

The present invention provides a two-system braking pressure control valve that has a skewer-shaped structure that applies an operation starting point control force from one end, and that when one system fails, the remaining one system reduces the rear wheel pressure reducing effect compared to when it is normal. It is something.

FIG. 1 shows a diagram of the principle of the present invention.

Under _{normal conditions , the} first system pressure is determined by the first piston 10 in the left _{half of} FIG. 1-A ₁ /A ₂ )・P _1M +F/A ₂ ...(1) [The operation starting point Ps is Ps=F/A ₁ ] It shows the pressure reduction characteristic.

On the other hand, the second system is the second piston 20 on the right half of the diagram.
If A ₃ = A ₅ , the opposing annular areas on both sides are canceled by P _1M ; P _2M , so
Follow up so that P _2R = P _1R .

That is, by setting A ₃ =A ₅ , the left end operation start point control force F provides the same pressure reducing effect on both systems.

When the first system fails, there is no hydraulic pressure acting on the first piston, so the force F is directly applied to the second piston, and P _2R・A ₅ =P _2M・(A ₅ −A ₄ )+F ∴P _2R =(1- _A4 / _A5 )・_P2M +F/ _A5 ...(2) [The operation starting point Ps is Ps=F/ _A4 ] It shows the pressure reduction characteristic.

Here, if A ₄ <A ₁ is set, the start point of the second system decompression operation when the first system fails can be increased compared to the normal state, and furthermore, A ₄ /A ₅ <A ₁ /A _2. If set, the decompression ratio at the time of failure can also be increased compared to normal.

On the other hand, Figure 2 shows the behavior when the second system fails.

Initially, the second piston is pushed to the right in the diagram because the first system output pressure operating area is larger than the first system input pressure operating area, and only the first piston acts to reduce pressure from the same operation starting point as in normal times. Start.
However, the decompression effect further progresses, and P _1R・A ₃ = P _1M (A _3
-A4 ), the second piston moves to the left and opens the first valve part, so the first system output pressure increases,
Push the second piston back to the right again to return the valve to the closed state. Therefore, the first system output increases along the line P _1R = (1-A ₄ /A ₃ )P _1M (3). The follower valve is A ₃ according to the condition.
= A ₅ , so compared to the behavior when the first system fails, this is a form in which the term F/A ₅ is omitted, that is, Ps = 0 and the decompression ratio is the same as when the first system failed. It takes shape. It is desirable to set A ₄ ≪ _{A 3} from the viewpoint of reducing the decompression effect at the time of failure.

Next, a specific example is shown in FIG.

A stepped first piston 10 is arranged between the first system input port 1 and the first system output port 2.

The first piston 10 is provided with a first valve part 11, and depending on the relative distance between the first piston 10 and the second piston 20 on the right, the valve is opened if the distance between them is less than a certain value, and the valve is opened at a certain value. If the value exceeds the value, the valve closes. Spring 12 is the first piston 1
0 is pressed in the valve opening direction. This spring 1
The valve 2 may be built into the control valve as shown in the figure, or it may be one whose operating force is automatically adjusted from the outside depending on the relative distance between the sprung and unsprung portions of the vehicle.

It goes without saying that the above configuration provides the well-known pressure reducing valve function.

Due to manufacturing considerations, the second piston 20 is divided into two halves 21 and 22, which are connected by a connecting pin 23 so that they can move as one. Although this configuration is for convenience in assembly, it also has the effect of removing constraints on concentricity tolerance between the two parts 21 and 22.

The pressure medium entering from the second system input port 4 passes through the passage provided in the second piston 20 to the second valve part 2.
4, it communicates with the second system output port 5. Although it is possible to provide this passage in either half piece 21 or 22, if the space between the two is used as a passage as in this embodiment, the number of parts to be processed can be reduced.

The second piston 20 has the same area at both ends, and the left side is exposed to the first system output and the right side is exposed to the second system output. There is a seal 25 in the central small diameter part of the second piston 20, so that the second piston 20
0 is configured with an inwardly opposed annular portion. One of the annular parts communicates with the first system input through a passage 3, and the other side is exposed to the second system input.

Since the inputs of both the first and second systems are substantially equal, the forces acting on both the annular parts are canceled out, and the second piston 20
If the first system output is larger than the second system output, it moves to the right to open the second valve part 24, and if it is smaller, it moves to the left to close the valve. That is, the second system output pressure follows the first system output pressure.

The behavior when one of the systems fails is the same as described in the explanation of FIG. 1, so it will not be described again.

As described above, the present invention is a two-system braking pressure control valve that has the function of reducing the pressure reducing effect of the remaining system when one system fails, and by pressing from one end with a single operation start point control force, It is possible to control the start point of the decompression operation during normal operation. Therefore, it can be easily applied as either a fixed operation starting point type control valve or a load responsive type control valve that utilizes the displacement between the sprung and unsprung parts of a vehicle.

Further, the parts related to the first system and the parts related to the second system are concentrated at each end, and the only point of contact between the two is the seal 25. (The seals that serve as the points of contact for both systems need to be configured to have both effects, and if you want to be sure, you can use two cup seals to butt each other. This increases production costs, so it is desirable to minimize the number of seals as much as possible.) ) Furthermore, in the configuration of the second piston 20, a radial hole is formed in the two parts 21 and 22, and a connecting pin 23 is formed.
By inserting them in the radial direction, they are connected in the axial direction, which solves assembly problems and facilitates machining.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is a behavior characteristic diagram when the second system fails, and FIG. 3 is an embodiment of the present invention. 1...First system input port, 2...First system output port, 3...Passway, 4...Second system input port, 5...
Second system output port, 10...First piston, 11...
...First valve part, 12...Spring, 20...Second
Piston, 21... Second piston member, 22...
Second piston member, 23... Connection pin, 24...
Second valve part, 25...Seal.

Claims (1)

[Claims] 1. Defines an annular portion having a first piston and a first valve portion associated therewith, and a second piston and a second valve portion associated therewith, and on which a first system input pressure acts. The area of the small diameter part is the second on the second piston.
The area of the first valve part is larger than the area of the small diameter part that defines the annular part on which the system input pressure acts, and the first valve part is connected to the first piston and the second valve part.
The second valve portion is arranged so that the valve closes when the relative distance between the piston and the piston is large, and opens when the relative distance between the second piston and the casing is opposite to the first piston. The valve is arranged so that the valve closes when the relative distance between them is large and opens when it is small, and the first piston has the operation start point control force and the first system input pressure on the valve opening side, and the first system output pressure on the first piston. It acts on the valve closing side, and the second piston has the first
The system output pressure and the second system input pressure act on the valve opening side, the first system input pressure and the second system output pressure act on the valve closing side, and the first system output pressure acting area faces each other on the second piston. The output pressure acting area of the second system is equal, and the first system input pressure acting area and the second system input pressure acting area are set equal, so that when the first system fails, the operation starting point control force is applied to the first system through the first piston. A two-system controlled dynamic pressure control valve characterized by pushing two pistons toward the valve opening side. 2. Claim 1 is characterized in that the second piston has a structure in which the _second piston is connected by a connecting pin at the _A4 diameter portion, which is the intermediate diameter between the A3 diameter portion and the _A5 diameter portion. Two-system controlled dynamic pressure control valve. 3 It has a first piston and a first valve part associated with it, and a second piston and a second valve part associated with it, and the area of the annular part on the first piston on which the first system input pressure acts is the area of the first system output The quotient divided by the area of the end on which the pressure acts is smaller than the quotient of the area of the annular part on the second piston, on which the second system input pressure acts, divided by the area of the end, on which the second system output pressure acts. The first valve part is arranged so as to close when the relative distance between the first piston and the second piston is large, and open when the relative distance between the first piston and the second piston is small, and the second valve part is arranged so that the relative distance between the second piston and the second piston is The valve is arranged so that the valve closes when the relative distance between the first piston and the end wall on the opposite side of the body is large, and opens when the relative distance is small, and the first piston is provided with an operation starting point control force and a first system. The input pressure acts on the valve opening side, the first system output pressure acts on the valve closing side, the first system output pressure and the second system input pressure act on the valve opening side, and the first system input pressure and the second system input pressure act on the second piston. Two system output pressures act on the valve closing side, and on the second piston, the opposing first system output pressure action area and second system output pressure action area are equal, and the first system input pressure action area and the second system input pressure action area are equal. The system input pressure action area is set equal, and the first
A two-system controlled dynamic pressure control valve characterized in that when a system failure occurs, the operation start point control force presses the second piston toward the valve opening side via the first piston. 4. Claim ₃ is characterized in that the second piston has a structure in which the second piston is connected by a connecting pin at the _A4 diameter portion which is the intermediate diameter between the A3 diameter portion and the _A5 diameter portion. Two-system controlled dynamic pressure control valve.