JPS6311401Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a base valve for a hydraulic shock absorber, and more particularly to a structure of a base valve for a hydraulic shock absorber that performs a desired damping action depending on vibration frequency.

The base valve, which exerts a desired damping effect during the pressure stroke of a hydraulic shock absorber, is formed in such a way that it exhibits a large damping force reduction effect, that is, a so-called high-cut effect, when its vibration frequency reaches a high frequency range. This is desirable in driving a vehicle equipped with the hydraulic shock absorber, and the ride comfort thereof is also improved.

Therefore, a base valve having a structure as shown in FIG. 1 has been provided conventionally. That is, this base valve has a disk 3 that is vertically movable in a valve body 2 attached to the lower end of an inner tube 1, and the oil from the upper chamber A is attached to the valve body 2. The inner circumferential end of the leaf valve 4 is pushed down to perform a damping effect when it passes through and flows into the reservoir B, and when the disk 3 housed in the valve body 2 is in a low frequency range, it descends significantly. Then, the opening area due to the deflection of the leaf valve 4 is reduced to generate a large damping force, and in the high frequency range, the lowering of the disk 3 is reduced to keep the opening area due to the deflection of the leaf valve 4 large, resulting in a low damping effect, that is, the so-called so-called. This is intended to provide a high cut effect. and,
The base valve shown in Fig. 1 moves the leaf valve 4 by moving the disk 3 up and down depending on the input frequency.
Since the opening area is adjusted by the deflection of the orifice, the damping force in the orifice area, that is, the area where the piston speed is slow, is not variable depending on the input frequency, and the ride comfort is improved when the vehicle is traveling on a good road. There was a risk that I would not be able to improve my situation. Furthermore, in the high speed range of the piston speed, the damping force decreases, that is, a so-called high-cut effect occurs, so when the vehicle is traveling on rough roads, the sprung mass damping performance decreases, which may adversely affect the steering stability.

Therefore, the present invention makes it possible to obtain a large damping force reduction rate, that is, the so-called high-cut action ratio, in the low-speed piston speed range with high-frequency input, and to reduce the so-called high-cut action ratio at the time of high-frequency input in the high piston speed range. The purpose of this project is to provide a new base valve for hydraulic shock absorbers.

In order to achieve this purpose, the structure of the present invention is
A base valve of a hydraulic shock absorber is formed to cause oil from an upper chamber to pass through a reservoir during a pressure stroke of a piston inserted into an inner tube to provide a desired damping effect. It consists of a valve body whose inner periphery is fixed and a flow rate adjustment section that makes the amount of oil that bypasses the valve body variable, and the flow rate adjustment section is fixed to the valve body and allows communication between the upper chamber and the reservoir. a housing having an oil passage, a spool disposed within the housing so as to be vertically movable and capable of communicating and blocking the oil passage; and a pressure chamber adjacent to the top surface of the spool and communicating with the upper chamber via an orifice. It is characterized by being formed so that the amount of oil that bypasses the valve body can be varied by vertical movement of the spool due to the pressure difference between the pressure chamber and the upper chamber, thereby achieving a desired damping effect. be.

Hereinafter, the present invention will be explained based on the illustrated embodiments.

As shown in Fig. 2, the hydraulic shock absorber equipped with the base valve according to the present invention has an inner tube 1
The interior of the inner tube 11 is divided into two oil chambers A and A' by a piston 12 inserted into the interior of the inner tube 12 and having a rebound damping valve, etc.
A reservoir B is formed between the outer tube 13 and the outer tube 13 disposed on the outside. The upper ends of the inner tube 11 and the outer tube 13 are connected by a bearing 14, and a lid 15 is attached to the upper end of the outer tube 13. A sealing member 16 is disposed within the lid 15 and is held by a support member 17 . and,
The piston 12 passes through the bearing 14, the lid 15, the seal member 16, and the support member 17.
A piston rod 18 connected to the piston rod 18 is disposed. A buffer material 19 whose tip extends toward the lower piston 12 is attached to the lower surface of the bearing 14 . Further, a cover mounting member 20 is interposed near the upper end of the piston rod 18, and a dust cover 21 is attached to this cover mounting member 20. Furthermore, a bottom member 22 is attached to the lower end of the outer tube 13, and a lower bracket 23 is fixed to this bottom member 22. A base valve 24 according to the present invention, whose lower end is supported by a bottom member 22, is attached inside the lower end of the inner tube 11.

As shown in FIG. 3, the base valve 24 is composed of a valve body 30 and a flow rate adjustment section 40.

The valve body 30 has a case 31 that is fitted into the lower end of the inner tube 11 and supported from below by a bottom member 22 attached to the lower end of the outer tube 13. A plurality of oil holes 32a are formed in the thick wall portion of the case 31 near the inner circumference, and a plurality of oil holes 32b are formed near the outer circumference. and,
A damping valve 3 is installed at the lower end opening of the oil hole 32a near the inner circumference.
3 are adjacent to each other by fixing the inner peripheral ends. Also,
A non-return valve 34 is urged downwardly by the lower end of a non-return spring 35 and is adjacent to the upper end opening of the oil hole 32b near the outer periphery. In addition, the oil hole 32 near the inner circumference
A through hole 35' is formed at a corresponding position of the non-return valve 34 facing the upper end opening of a, allowing oil from the upper chamber A to flow into the oil hole 32a near the inner periphery. . Further, the damping valve 33 is positioned at the lower end opening of the oil hole 32a near the inner periphery, but in this embodiment, the flow rate adjustment section 40, which will be described later, is positioned at the lower end opening of the oil hole 32a near the inner periphery. Considering that it is attached to the valve body 30 so as to penetrate therethrough, a tightening member 36 is attached to the lower end of the protrusion.
It is fixed at the desired position by screwing them together. When the tightening member 36 is screwed together, a control plate 37 for controlling the deflection of the damping valve 33 is interposed, and a shim 38 is also interposed between the control plate 37 and the damping valve 33. .

On the other hand, the flow rate adjusting section 40 attached to the valve body 30 has a housing 41 whose lower end protrusion is interposed within the case 31 of the valve body 30. This housing 41 is provided with a vertical oil passage 42a that passes through the lower end protrusion in its axial direction and opens downward, that is, on the upper surface of the bottom member 22 in this embodiment, and in the upper half of the housing 41. A plurality of horizontal oil passages 42b are formed which are bored in the radial direction. Further, a spool 43 is disposed within the housing 41 so as to be movable up and down. This spool 43 has a leaf spring 44 attached to a pin 45 at the upper end.
The outer peripheral end of the leaf spring 44 is supported on the inner periphery of the housing 41, and the housing 41 is fixed by applying pressure from above the leaf spring 44.
The inside of the housing 41 is lowered by releasing the pressure.
It is beginning to rise within. In this spool 43, when the spool 43 is raised, the horizontal oil passage 42 is
An orifice 46 is formed so that the oil in the upper chamber A can flow into the vertical oil passage 42a by communicating with the vertical oil passage 42a, and is formed so that communication with the horizontal oil passage 42b is cut off when the oil is lowered. have. In addition,
When the spool 43 rises, that is, the leaf spring 44
A non-return spring 47 is provided below to prevent the spool 43 from rising more than necessary even when the pressure on the upper surface is released and the pressure becomes negative. This non-returning spring 47 is supported by a plate 48 attached inside the upper end of the housing 41. This plate 48 supports an orifice plate 49 on its upper surface.
Reference numeral 9 is provided inside the upper end of the housing 41 to provide a pressure chamber C above the spool 43. That is, this is to form a primary delayed circuit in which depressurized oil flows into the pressure chamber C through the orifice 49' at the center of the orifice plate 49, and the spool 43 is moved up and down within the housing 41 using the pressure.

Therefore, the base valve 24 according to the present invention configured as described above operates as follows when the hydraulic shock absorber is operated.

That is, during the extension stroke of the piston 12, the upper chamber A becomes negative pressure, and the oil in the reservoir B reaches the oil hole 32b near the outer periphery in the case 31, and the non-return valve 3
4 and flows into the upper chamber A. At this time, the base valve 24 does not generate a damping force on the expansion side.

Also, during the pressure stroke of the piston 12, the upper chamber A
becomes high pressure. Then, the oil in the upper chamber A passes through the through hole 35' of the non-return valve 35, and flows through the oil hole 35' near the inner circumference.
Reaches inside a. The oil in this oil hole 32a pushes down the outer peripheral end of the lower damping valve 33 and reaches the lower side, that is, into the reservoir B, through the gap formed there. The flow of oil pushing down the outer circumferential end of the damping valve 33 provides a desired pressure-side damping effect.

On the other hand, when the spool 43 is raised, the oil in the upper chamber A flows through the horizontal oil passage 4 of the housing 41.
b, the valve body 30 via the orifice 46 of the spool 43 and the vertical oil passage 42a of the housing 41;
It flows downward, that is, into the reservoir B. Therefore, in this case, most of the oil in the upper chamber A will pass through the flow rate adjustment section 40 of the base valve 24, and no large damping effect will occur in the lower valve body 30.

However, when the spool 43 is lowered within the housing 41, the horizontal oil passage 4 of the housing 41
2b and the vertical oil passage 42a will be cut off, and the oil in the upper chamber A will exclusively pass through the damping valve 33 portion of the valve body 30, resulting in a large damping effect.

As described above, the spool 43 is attached to the housing 41
By moving up and down inside, a large damping force may be generated, or only a small damping force may be generated.

Therefore, the vertical movement of the spool 43 will be explained below.

That is, the lower part of the orifice plate 49 and the spool 4
A pressure chamber C is formed between the orifice 49' of the orifice plate 49 and the plate spring 44, and the spool 43 is supported by a leaf spring 44 so as to be able to move up and down. It is composed of a spool 43, and corresponds to a primary delay circuit in a spring mass system with an orifice 49'. In the case of a low frequency input, the rise delay of the pressure Pc in the pressure chamber C with respect to the pressure Pa in the upper chamber A becomes small, and the absolute value also becomes Pa≈Pc, and the amount of descent of the spool 43 becomes large. In addition, when high frequency is input, the rise delay of the pressure Pc in the pressure chamber C becomes large.
The absolute value also becomes Pa>Pc, and the amount of descent of the spool 43 becomes smaller.

Therefore, when a low frequency is input, the amount of descent of the spool 43 becomes large and the opening area of the orifice 46 becomes small. Then, the damping force becomes high in the orifice region where the piston speed is slow. Furthermore, when a high frequency is input, the amount of movement of the spool 43 becomes smaller, and the opening area of the orifice 46 becomes larger. The damping force will be low in the orifice region where the piston speed is slow. However, even during high frequency input, when the piston speed is high, it goes without saying that the damping force of the valve body 30 will be reduced, but the damping force will also be reduced as much as when the piston speed is low. is not caused. That is, the oil passages 42a and 42b bored in the housing 41 are connected to the spool 43.
The oil passages 42a, 42a, 42a, 42a,
Oil does not pass through 42b, but in the high speed region of the piston, oil is inserted even in a so-called constricted state. Therefore, in a region where the piston speed is large, the so-called high-cut ratio at the time of high frequency input becomes small. That is, when the piston speed is high, the reduction in damping force is suppressed to a small extent, so that the damping performance on the spring is improved.

Therefore, according to the present invention, by making the orifice area variable depending on the input frequency, it is possible to generate a so-called high-cut effect that greatly reduces the damping force during high frequency input in the low piston speed range. . Furthermore, in a region where the piston speed is high, the so-called high cut rate can be reduced when high frequency is input. As a result, if the hydraulic shock absorber equipped with the base valve according to the present invention is used in a vehicle, the ride comfort of the vehicle can be improved when driving on a good road or when riding over a joint on the road surface, and the vehicle can be improved. The effect of improving the steering stability of the vehicle can be obtained.

[Brief explanation of drawings]

Fig. 1 is a partial longitudinal cross-sectional view showing a conventional base valve, Fig. 2 is a longitudinal cross-sectional view showing a hydraulic shock absorber equipped with the base valve according to the present invention, and Fig. 3 is an enlarged view of the base valve according to the present invention. FIG. DESCRIPTION OF SYMBOLS 11... Inner tube, 12... Piston, 24... Base valve, 30... Valve body, 40... Flow rate adjustment part, 41... Housing,
42a, 42b...Oil path, 43...Spool, A
...Upper chamber, B...Reservoir.

Claims (1)

[Claims for Utility Model Registration] (1) A base of a hydraulic shock absorber formed to allow oil from the upper chamber to pass through the reservoir during the pressure stroke of the piston inserted into the inner tube to provide a desired damping effect. In the valve, the base valve consists of a valve body with a fixed inner circumference that provides a desired damping effect and a flow rate adjustment section that makes the amount of oil that bypasses the valve body variable, and the flow rate adjustment section is fixedly attached to the valve body. a housing having an oil passage that allows communication between the upper chamber and the reservoir; a spool that is vertically movable within the housing and allows communication and interruption of the oil passage; adjacent to the upper surface of the spool; It consists of an upper chamber and a pressure chamber that communicates through an orifice, and the desired damping effect can be achieved by varying the amount of oil that bypasses the valve body by moving the spool up and down due to the pressure difference between the pressure chamber and the upper chamber. A base valve of a hydraulic shock absorber, characterized in that it is formed as follows. (2) The scope of the utility model registration claim, in which the flow rate adjustment part is formed so that the amount of oil passing through the valve body can be varied by moving a spool disposed inside the housing up and down in accordance with the vibration frequency. The base valve in the hydraulic shock absorber according to item 1.