JPH0443633Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a shot absorber, and in particular,
The present invention relates to an improvement in a shock absorber in which the damping force generated is variable depending on the vibration frequency within the cylinder.

[Conventional technology]

A shock absorber that varies the generated damping force depending on the vibration frequency within the cylinder.In particular, when the vibration frequency exceeds a certain range, the high damping force that was previously generated will be reduced. Various proposals have been made in the past as shock absorbers having a so-called high-cut action, one example of which is a shock absorber having a structure as shown in FIG.

In other words, in this conventional shock absorber, when the vibration frequency in the cylinder 1 exceeds a certain range, the rebound damping force generated in the piston part 2 is reduced from the previously high damping force. It is formed to provide a damping force. The above-mentioned rebound damping force is determined by the upper chamber A in the cylinder 1.
This is made possible by the fact that the hydraulic fluid from the leaf valve 2b deflects the outer peripheral end of the leaf valve 2b energized by the spring 2a and flows into the lower chamber B through the gap formed there. ing. In addition, an orifice 3 is provided on the back side of the leaf valve 2b.
a, free piston 3b and biasing spring 3
It is formed so that the first-order lag pressure P generated by the first-order lag circuit consisting of c acts on the first-order lag pressure P. Furthermore, the first-order lag pressure P becomes smaller as the vibration frequency within the cylinder 1 becomes larger.
Conversely, as the frequency decreases, the relationship increases, so when the vibration frequency exceeds a certain range, the so-called back-up force on the leaf valve 2a decreases, causing the leaf valve 2a to bend significantly, The high damping force of the damping force is reduced, resulting in a so-called high-cut effect.

[Problem that the invention attempts to solve]

However, in the conventionally proposed structure described above, in order to configure a first-order lag pressure circuit, it is necessary to ensure a length for sliding of the free piston 3b and to provide an energizing spring 3c. Therefore, the overall length of the piston portion 2 becomes long, and there is a problem that a sufficient effective stroke in the shock absorber cannot be secured.

In addition, in the above-described structure, when the expansion side changes to the compression side, the pressure oil from the first-order lag circuit passes through the orifice 3a to the upper chamber A.
As a result, the pressure may shift to the expansion side before the primary lag pressure can be sufficiently eliminated, and at this time, residual pressure accumulates in the primary lag circuit, causing the leaf valve 2b to A pressure higher than the set value is introduced to the back surface of the holder, and as a result, the desired so-called high-cut action cannot be obtained.

Therefore, in view of the above-mentioned circumstances, the present invention has developed a new shock absorber that does not increase the basic length of the piston part and also prevents the risk of pressure accumulation due to residual pressure in the primary delay circuit. The purpose is to provide.

[Means for solving problems]

In order to solve the above-mentioned problems, the structure of the shock absorber according to the present invention is such that a piston rod is movably inserted into a cylinder via a piston body, and the piston body partitions an upper chamber and a lower chamber in the cylinder. The piston body is provided with a growth side port that communicates the upper chamber and the lower chamber, and a growth side valve is provided at the lower end opening of the growth side port so that it can be opened and closed freely, and the growth side valve is biased in the upward direction by a lower spring. In the shock absorber, the damping force generated by the expansion valve is variable depending on the vibration frequency in the cylinder, and the shock absorber has a shock absorber that is slidable in the vertical direction on the outer periphery of a piston nut that is screwed onto the lower end of the piston rod. A spool is interposed, the upper surface of the spool supports the lower part of the spring, and a first-order lag pressure chamber is provided within the piston rod, and one end of this pressure chamber is connected to an upper chamber through a non-return valve having an orifice. The pressure chamber is opened and closed, and the other end of the pressure chamber is guided to the lower surface of the spool.

[Effect]

The pressure from the first-order lag pressure chamber in the piston rod can be applied directly to the lower end of the spring that urges the valve element that backs up the leaf valve in the upward direction. No need to set up.

In addition, the pressure of the first-order lag inside the piston rod is
When the non-return valve is opened, the water flows out into the upper chamber within the cylinder, and no residual pressure is generated in the pressure chamber.

〔Example〕

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

As shown in FIG. 1, the shock absorber according to the present invention is formed in a so-called double-tube type, and the inside of a cylinder 1 is divided into an upper chamber A and a lower chamber B by a piston part 2. In addition, an outer tube 10 is provided outside the cylinder 1, and a reservoir chamber C is formed between the outer tube 10 and the cylinder 1. And the reservoir chamber C
is communicated with the lower chamber B via a base valve portion disposed inside the lower end of the cylinder 1, although not shown.

The piston portion 2 is disposed at the lower end spigot portion of the piston rod 3 inserted into the cylinder 1, and is a piston body 20 that divides the inside of the cylinder 1 into an upper chamber A and a lower chamber B. A leaf valve 21 as a growth-side valve is adjacent to the lower end opening of the growth-side port 20a. Further, a pressure side valve 22 is adjacent to the upper end opening of the pressure side port 20b of the piston body 20.

The leaf valve 21 is arranged so that the inner circumferential end is fixed and the outer circumferential end is free.
Upper chamber A in the cylinder 1 via the expansion side port 20a
When the hydraulic oil from inside is to flow into the upper surface side, the outer circumferential end is bent downward, and the hydraulic oil flows into the lower chamber B inside the cylinder 1 through the gap created there. Thus, the desired rebound damping force is generated.

However, in the case of the present invention, the above leaf valve 2
1 is backed up by a valve body 23 that is in contact with the back surface, and the valve body 23 is urged upward by a spring 24 from below.

Therefore, the outer peripheral end of the leaf valve 21 can be bent by lowering the valve body 23 so as to overcome the urging force of the spring 24. If changed, the damping force generated by the leaf valve 21 will also be changed.

A disk member 25 is disposed above the piston body 20, that is, above the pressure side valve 22. As shown in FIG. 2, the disc member 25 is interposed in the lower end spigot part of the piston rod 3 so as to be in line with the piston body 20, and has an annular groove on its inner peripheral surface. 25a, and an annular groove 2 on its upper end surface.
5b and an annular seat portion 25c. The annular grooves 25a and 25b are provided in the thick portion.
A diagonal port 25d is provided to communicate with the.
Further, the annular groove 25 is formed on the upper end surface of the disk member 25, that is, on the upper surface of the annular seat portion 25c.
A non-return valve 26 is disposed to cover b from above.

The non-return valve 26 has a non-return spring 27 applying force to the upper surface of its outer circumferential end, and is formed so that its outer circumferential end is raised during the pressure side stroke in which the piston portion 2 descends within the cylinder 1. At the same time, during the expansion stroke in which the piston part 2 moves up inside the cylinder 1, the hydraulic oil in the upper chamber A inside the cylinder 1 flows into the annular groove 25b through the orifice 26a bored in the non-return valve 26. It is formed in such a way as to allow it to flow into the water.

A vertical hole 30 is bored in the axial center of the lower end spigot part of the piston rod 3, and the upper end side of the vertical hole 30 is connected to the piston rod 3 through a horizontal hole 31 bored in the radial direction of the piston rod 3. Disk member 25
It communicates with an annular groove 25a on the inner circumferential surface of. That is, the vertical hole 30 communicates with the upper chamber A within the cylinder 1 via the orifice 26a of the non-return valve 26.

On the other hand, the lower end threaded portion of the piston rod 3 includes the piston main body 20, the leaf valve 21,
A piston nut 32 is screwed together to fix the pressure side valve 22 and the disk member 25 to the lower end spigot part of the piston rod 3, and the piston nut 32 has an inner chamber 32a and a cap 33, and the piston nut 32 has an inner chamber 32a and a cap 33. The lower end side of 30 is closed. Further, the piston nut 32 has a spool 34 on its outer periphery so as to be slidable in the vertical direction, and the lower surface side of the spool 34 communicates with the vertical hole 30.

That is, an annular groove 32b is formed on the outer peripheral side upper end surface of the piston nut 32.
The lower surface of the spool 34 is adjacent to b. The annular groove 32b is connected to a port 32c formed in a thick wall portion of the piston nut 32.
The inner chamber 32a is communicated with the inner chamber 32a through the inner chamber 32a.

Furthermore, the spool 34 is connected to the valve body 2.
3 in the upward direction.

Therefore, when the piston part 2 is on the extension stroke moving up inside the cylinder 1 and is within a certain range where the vibration frequency in the upper chamber A of the cylinder 1 becomes high, the first-order lag pressure circuit is activated. The pressure chamber that constitutes it, that is, the vertical hole 3 in the piston rod 3
A relatively high internal pressure is generated within the spool 34, and this internal pressure acts on the lower surface of the spool 34 and compresses the spring 24 supported on the upper surface. As a result, the valve body 2 is biased upwardly by the spring 24 so as to back up the leaf valve 23.
4 is that the spring 24 receives a larger repulsive force than the repulsive force of the spring 24 when no external pressure in the compression direction is acting on the spring 24, and the deflection of the outer peripheral end of the leaf valve 23 is suppressed accordingly. . That is, the rebound damping force generated by the leaf valve 23 becomes extremely high.

During the extension stroke, when the vibration frequency exceeds a certain range of increase, the above-mentioned high internal pressure cannot be generated in the vertical hole 30 serving as the pressure chamber, and as a result, the spool 34 rises. is suppressed, and the leaf valve 23
The outer peripheral end of the leaf valve 23 is largely bent, and the rebound damping force generated by the leaf valve 23 is changed to a lower one. That is, a so-called high-cut effect is brought about.

Note that when changing from the expansion side stroke to the compression side stroke, the inside of the upper chamber A in the cylinder 1 becomes negative pressure, so
The non-return valve 26 on the upper surface of the disk 25 is opened by raising its outer peripheral end, and the internal pressure in the vertical hole 30 of the piston rod 3, which is a pressure chamber, is easily released. As a result, no residual pressure is generated in the pressure chamber, and furthermore, even when the expansion stroke is started, a new first-order lag internal pressure is generated in the pressure chamber, which prevents the spool 34 from rising as set. It is expected that the desired high damping force generation and high cut action will be possible.

In addition, the pressure in the upper chamber A inside the cylinder 1
P ₁ , vertical hole 30 in piston rod 3 which is a pressure chamber
Assuming that the pressure inside is P ₂ and the vibration frequency ω in the upper chamber A of the cylinder 1, the above pressure P ₁ ,
Between P ₂ and the vibration frequency ω, the following relationship holds true.

|P ₂ /P ₁ 1=1/√1+() (1) Here, C _e = δ/3π×C ₁ ×P ₂ ×ω, C ₁ =ζ ₁ ×
(a ² /K) ² , and a is the pressure receiving area in the pressure chamber,
K is the spring constant and ζ ₁ is the throttling resistance at the orifice.

Therefore, from (1) above, P ₂ = P ₁ × ¹ /√1 + () ² , and as ω increases, P ₂ decreases, and as ω decreases, P ₂ increases, so the above Of course, by appropriately selecting the orifice 26a, the pressure receiving area a of the pressure chamber, and the spring constant K of the spring 24, a so-called high-cut effect will be brought about when the vibration frequency exceeds a desired frequency range.

[Effect of idea]

According to the present invention, there are the following effects.

One end of the pressure chamber in the piston rod was opened and closed to the upper chamber through a non-return valve equipped with an orifice, and the other end of this pressure chamber was guided to the lower surface of the spool that supported the spring. The internal pressure of the pressure chamber is high within a certain range until the vibration frequency in the upper chamber becomes high, and this internal pressure acts on the expansion valve via the spool to increase the damping force. When the vibration frequency exceeds a certain range, the internal pressure of the pressure chamber is no longer high, and the damping force becomes low.

When the expansion stroke shifts to the compression stroke, the upper chamber becomes negative pressure, the non-return valve is opened, the internal pressure in the pressure chamber is released, and no residual pressure is generated. Therefore, even if the stroke is further shifted to the extension side, a new first-order lag internal pressure is generated in the pressure chamber, making it possible to generate the desired high damping force and high-cut action.

Since there is no free piston or spring in the pressure chamber as in the conventional case, it is possible to reduce the overall length of the piston portion, which has the advantage of preventing a reduction in the so-called effective stroke. Similarly, since the free piston and the spring that biases it can be omitted, the number of parts can be reduced, which, together with the reduction in the number of assembly steps, contributes to lower costs.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of a shock absorber according to an embodiment of the present invention, FIG.
It is a sectional view shown similarly to a figure. 1... Cylinder, 2... Piston part, 3... Piston rod, 21... Leaf valve, 23...
Valve body, 24... Spring, 26... Non-return valve, 26a... Orifice, 32... Piston nut, 34... Spool, A... Upper chamber, B
...Lower chamber.

Claims (1)

[Claims for Utility Model Registration] (1) A piston rod is movably inserted into the cylinder via a piston body, the piston body divides the cylinder into an upper chamber and a lower chamber, and the piston body has an upper chamber and a lower chamber. A growth-side port communicating with the lower chamber is provided, and a growth-side valve is provided at the lower end opening of the growth-side port so that it can be opened and closed freely.The growth-side valve is biased in the upward direction by a lower spring, and In a shock absorber in which the damping force generated is variable depending on the vibration frequency in the cylinder, a spool is installed on the outer periphery of a piston nut that is screwed onto the lower end of the piston rod so as to be slidable in the vertical direction. The upper surface supports the lower part of the spring, and a first-order lag pressure chamber is provided within the piston rod. One end of this pressure chamber is opened and closed to the upper chamber via a non-return valve formed with an orifice, and the other pressure chamber is A shock absorber whose end is guided to the underside of the spool. (2) Claim No. 1 for Utility Model Registration, in which a non-return valve is disposed on the upper surface of a disk member disposed on the outer periphery of the pilot part at the lower end of the piston rod so as to close the upper end side of the pressure chamber within the piston rod. Shock absorber as described in section. (3) Utility model registration claim 1, in which an annular groove communicating with the pressure chamber in the piston rod is formed on the upper end surface of the outer peripheral side of the piston nut, and a spool is adjacent to the annular groove so as to cover the annular groove. Shock absorber as described in section.