JPH0410432Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is suitable for performing a so-called high-cut action, which can greatly reduce the damping force generated when the vibration frequency exceeds a certain range. This invention relates to an improvement in the structure of a damping force generating part of a hydraulic shock absorber.

[Conventional technology]

Various proposals have been made in the past to perform a so-called high-cut action, which greatly reduces the damping force generated when the vibration frequency exceeds a certain range, but these conventional proposals have not been able to achieve a stable high-cut action. I had the inconvenience of not being able to do it.

Therefore, the applicant of the present application first proposed a hydraulic shock absorber capable of performing a stable high-cut action (Japanese Patent Application No. 59-229700). The previous proposal is formed as shown in FIG. 4 as an example.

That is, the damping force generating part 4, which enables generation of a predetermined damping force when the piston part 3 fixed to the lower end of the piston rod 2 inserted into the cylinder 1 slides in the cylinder 1, has an annular shape. A predetermined expansion-side damping force can be generated by the deflection of the outer circumferential end of the leaf valve 4a, and the amount of deflection of the outer circumferential end is made variable by the pressing force applied to the inner circumferential end of the annular leaf valve 4a. It is formed like this.
The above-mentioned pressing force is obtained by the internal pressure of the pressure chamber 4c that communicates with the upper chamber A in the cylinder via the orifice 4b formed above the inner peripheral end of the annular leaf valve 4a, and also by the internal pressure of the pressure chamber 4c. is transmitted to the push valve 4f via a coil spring 4e that expands and contracts as the spool 4d slides.
Moreover, the push valve 4f is formed so as to be obtained by coming into contact with the inner peripheral end of the annular leaf valve 4a.

[Problem that the invention attempts to solve]

However, in the above proposal,
A spool 4d that slides due to the internal pressure of the pressure chamber 4c.
is biased upward by the lower coil spring 4e, the damping force generating section having the annular leaf valve 4a is easily enlarged in the vertical direction by the interposition of the coil spring 4e, and the piston If an attempt is made to ensure the effective stroke of the portion 3, there is a problem in that the length of the entire hydraulic shock absorber becomes longer.

Therefore, in view of the above-mentioned circumstances, the present invention has been developed to generate damping force for a hydraulic shock absorber that can perform a stable high-cut action without increasing the overall length of the hydraulic shock absorber designed to perform a so-called high-cut action. The purpose is to provide a new part structure.

[Means for solving problems]

In order to solve the above-mentioned problems, the configuration of the present invention is a push valve in which the amount of deflection of the outer peripheral end of an annular leaf valve that enables generation of a predetermined damping force is varied by the pressing force applied to the inner peripheral end. The internal pressure from the pressure chamber above the spool is transmitted via a leaf spring.

〔Example〕

Hereinafter, the present invention will be explained based on a preferred embodiment shown in the drawings.

As shown in FIG. 1, the hydraulic shock absorber according to the present invention has a piston portion 3 at the tip of a piston rod 2 that is slidably inserted into a cylinder 1, and a damping force is generated at the tip of the piston rod 2. It has part 4. In this embodiment, the hydraulic shock absorber is formed into a double cylinder type, and an outer tube 10 is disposed outside the cylinder 1.

A bearing member 11 is disposed at the upper end of the cylinder 1, that is, inside the upper end of the outer tube 10, and the piston rod 2 is slidably inserted into a through hole in the shaft core of the bearing member 11. Note that a seal 12 is interposed above the bearing member 11.

The interior of the cylinder 1 is divided into an upper chamber A and a lower chamber B by the piston portion 3.
A base valve portion 13 is formed inside the lower end of the cylinder 1, and a reservoir chamber C is formed between the lower chamber B, the cylinder 1, and the outer tube 10 via the base valve portion 13.
It is communicated with. Note that a gas chamber D is located above the reservoir chamber C. Further, the base valve section 13 is provided with a pressure side valve 13a, a check valve 13b, and a relief valve 13c. Additionally, a mounting eye 1 is attached to the lower end of the cylinder 1.
4, and can be connected to the axle side of a vehicle.

Although not shown, the piston rod 2 is formed such that its upper end can be connected to the body of a vehicle.

As shown in FIG. 2, the piston part 3 is disposed in the spigot part 20 of the piston rod 2,
It also has a piston body 31 fixed in a predetermined position by a piston nut 30 screwed onto the threaded end 21 of the piston rod 2, and the piston body 31 allows the inside of the cylinder 1 to be connected to the upper chamber It is divided into A and a lower chamber B. The piston main body 31 is provided with a growth side port 32 on its inner circumference side and a pressure side port 33 on its outer circumference side, so that the upper chamber A and the lower chamber B can communicate with each other. It is formed.
Furthermore, a check valve 34 is disposed on the upper end opening side of the expansion side port 32 and the compression side port 33 so as to close the openings.

Note that the check valve 34 is connected to a stopper 3 that is engaged with the stepped portion 22 of the piston rod 2.
It is biased downward by a spring 36 whose upper end is locked to 5. Further, the check valve 34 and the stopper 35 are respectively formed with notches 34a and 35a through which oil can pass, and a piston ring 37 is interposed on the outer periphery of the piston body 31.

Therefore, the extension port 32 in the piston section 3 allows oil in the upper chamber A to flow into the lower chamber B during the extension stroke when the piston section 3 moves upward within the cylinder 1.
side, that is, the damping force generating section 4 side.

In this embodiment, the damping force generating section 4 is a damping force generating section on the extension side, and is formed within the piston nut 30. and,
The piston nut 30 has a growth side port 30 opposite to the growth side port 32 of the piston main body 31.
a is bored, and the piston nut 30
In other words, the damping force generating section 4 and the upper chamber A within the cylinder are allowed to communicate with each other.

In the damping force generating section 4, the annular leaf valve 40, which is a source of generating the rebound damping force, is housed so as to be sandwiched between a block 41 and a disk 42 disposed within the piston nut 30. A notch 40a is formed at the outer peripheral end, and the outer peripheral end is a free end that can be bent downward. and the annular leaf valve 4
The lower end opening of an extension port 41a bored in the upper block 41 is opposed to the outer circumferential upper surface of the valve 0, and the support point 42a of the lower disk 42 is in contact with the lower surface of the annular leaf valve 40. being touched. The support point 42a is positioned on the lower surface of the inner circumferential side of the annular leaf valve 40, and is positioned closer to the outer circumferential side than the inner circumferential side of the annular leaf valve 40.

An oil passage 42b is provided between the upper surface support point 42a of the disk 42 and its outer peripheral end, and an oil hole 42c is provided in the center thereof. Further, an annular seat 43 having the same wall thickness as the annular leaf valve 40 is disposed on the upper end surface of the outer peripheral side of the disk 42 . The ring seat 43
However, the provision thereof may be omitted and a raised portion having the same thickness as the annular leaf valve 40 may be formed in advance at the upper end of the outer peripheral side of the disk 42.
If the ring seat 43 is provided as in this embodiment, the top surface of the disk 42 can be easily finished.
This has the advantage that machining accuracy can be easily managed.

Inside the block 41 are a push valve 44 that abuts the inner circumferential end of the annular leaf valve 40 from above, a leaf spring 45 disposed on the upper surface of the push valve 44, and a leaf spring 45 disposed on the upper surface of the leaf spring 45. A spool 46 is provided. The upper part of the spool 46 in the block 41 is a pressure chamber 41b, and when there is a high pressure, that is, hydraulic pressure, in the pressure chamber 41b, the spool 46 is blocked by the hydraulic pressure. 41, and the pressing force in the form of hydraulic pressure is transmitted to the push valve 44 via the lower leaf spring 45, so that the push valve 44 pushes down the inner peripheral end of the annular leaf valve 40. .

Therefore, since the annular leaf valve 40 is supported by the support point 42a of the disk 42 at the lower surface of the intermediate portion, the outer peripheral end of the annular leaf valve 40 is lifted up in a so-called lever shape, and as a result, the annular leaf valve 40 The amount of deflection of the outer peripheral end of the damping force is changed to increase the damping force. Then, when the pressing force from the push valve 44, that is, the high oil pressure in the pressure chamber 41b is released, the high damping force is greatly reduced, resulting in a so-called high cut effect.

Therefore, in the present invention, an oil hole 41c is provided in the thick wall part of the block 41 above the pressure chamber 41b so as to allow the oil pressure to change within the pressure chamber 41b, and the oil Opposed to the hole 41c is an orifice 47a of a check valve 47, which is disposed to face the oil hole 41c for releasing the hydraulic pressure in the pressure chamber 41b. In addition, the block 41
The expansion side port 41a and the pressure chamber 41b are connected to the cylinder inner upper chamber A, that is, the piston nut 3
Vertical and horizontal ports 49a, 49b, and 49c are bored in the stopper 49 for the biasing spring 48 of the check valve 47 so that oil from the extension port 30a in the check valve 47 can flow in in a preferable manner.

The operation of the structure of the damping force generating part of the hydraulic shock absorber according to the present invention formed as described above will be briefly described.

During the extension stroke in which the piston part 3 moves up inside the cylinder 1, the inside of the upper chamber A becomes a high pressure side, and the oil in the upper chamber A is transferred to the expansion side port 32 of the piston body 31 and the expansion side port of the piston nut 30. 3
It flows into the piston nut 30 via 0a.
A part of the oil that has flowed into the piston nut 30 is transferred to the orifice 47 of the check valve 47.
At the same time, other oil flows into the pressure chamber 41b through the expansion side port 41a of the block 41 and flows out to the lower chamber B side so as to bend the outer peripheral end of the leaf valve 40.

At this time, when the vibration frequency in the upper chamber A exceeds a certain range, high pressure is no longer generated in the pressure chamber 41b, that is, the inner peripheral end of the annular leaf valve 40 is pressed and the outer peripheral end is blocked. A so-called high-cut phenomenon occurs in which the pushing force that causes the push valve 41 to generate a high damping force is no longer generated, and as a result, the annular leaf valve 40 returns to its initial deflection characteristics and stops generating a high damping force. will be invited.

That is, as shown in FIG. 2, a push valve 44 is arranged in an annular shape between the oil pressure P ₁ above the orifice 47a on the high pressure side and the oil pressure P ₂ in the pressure chamber 41b below the orifice 47a on the low pressure side. The following equation (1) holds true in relation to the force F that presses the inner peripheral end of the leaf valve 40.

Here, t: Time P ₁ : High pressure side pressure P ₂ : Pressure chamber side pressure of primary lag K: Spring constant of leaf spring 45 A ₂ : Pressure receiving area of spool 46 R ₁ : Fluid resistance of oil flowing through orifice 47a R ₂ : Fluid resistance of oil flowing around the outer circumference of the spool 46.

Therefore, for example, if P ₁ changes in a sinusoidal half wave as shown in equation (2) below, then P ₂ changes as shown in equation (1) above.
Solving the equation, the result changes as shown in Figure 3.

P ₁ =P ₁₀ sin2πt (0≦t≦π/2π)…(2) where P ₁₀ : is a constant.

Therefore, as can be seen from Figure 3, if the frequency of P ₁ increases, P ₂ becomes P ₁ in most of the time domain.
become smaller. In other words, the damping force can be reduced. The rate of decrease and the frequency at which the decrease starts are determined by the spring constant K of the leaf spring 45 that urges the spool 46 upward, the pressure receiving area A ₂ of the spool 46, and the fluid resistance of the oil.
By appropriately selecting R ₁ and R ₂ , they can be arbitrarily selected and desired characteristics can be obtained.

In addition, in the case of the present invention, the annular leaf valve 4
Of course, the zero damping force characteristic and the return characteristic of the leaf spring 45 can be set independently.

In the above description, the structure of the present invention is used as the expansion side valve part and is disposed inside the piston nut 30, but the structure of the present invention is used as the compression side valve part to generate compression side damping force and its high cut. possible, and the pressure side valve part is connected to cylinder 1.
Base valve part 13 inside the lower end (see Figure 1)
It is also possible to arrange it in

[Effect of idea]

As described above, according to the present invention, it is possible to obtain a stable damping force lowering effect in a region above a given frequency, that is, a so-called high-cut damping force effect, which can improve the riding comfort of a vehicle, for example. It becomes possible.

Furthermore, according to the present invention, even if a desired damping force generating part is formed below the piston in the cylinder or in the base valve part, the damping force generating part can be formed extremely short, so that the piston stroke can be increased. There is an advantage that there is no need to reduce the width, and there is no need to increase the overall length of the hydraulic shock absorber.

Furthermore, according to the present invention, the structure of the damping force generating part does not require any special machining on the inside or outside of the piston rod, reducing the number of parts and machining processes, which is economically advantageous. There are advantages.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional front view partially showing a hydraulic shock absorber according to an embodiment of the present invention, Fig. 2 is an enlarged view showing the piston part and damping force generating part in Fig. 1, and Fig. 3 is FIG. 4 is a characteristic diagram showing the relationship between frequency change and pressure change. FIG. 4 is a longitudinal sectional front view partially showing a hydraulic shock absorber according to an embodiment of the proposal made earlier by the present application. 1...Cylinder, 2...Piston rod, 3...
... Piston part, 4 ... Damping force generating part, 30 ... Piston body, 40 ... Annular leaf valve, 41 ...
...Block, 41b...Pressure chamber, 42...Disk, 44...Push valve, 45...Leaf spring, 46...Spool, 47...Check valve, 47a...Orifice, A...Upper chamber, B...
...Lower chamber, D...Gas chamber, C...Reservoir chamber.

Claims (1)

[Claims for Utility Model Registration] (1) A predetermined damping force can be generated by bending the outer peripheral end of the annular leaf valve when the piston portion slides, and is applied to the inner peripheral end of the annular leaf valve. In the structure of the damping force generating part of the hydraulic shock absorber, which is formed so that the amount of deflection of the outer peripheral end of the annular leaf valve is made variable by the pressing force, the pressing force is applied to the orifice formed above the inner peripheral end of the annular leaf valve. The inner peripheral end upper surface of the annular leaf valve is obtained by the internal pressure of a pressure chamber that communicates with the upper chamber in the cylinder through a leaf spring that urges the spool upward. A structure for a damping force generating part of a hydraulic shock absorber, characterized in that the damping force is transmitted to a push valve in contact with the damping force. (2) The damping force generating part of the hydraulic shock absorber according to claim 1, wherein the annular leaf valve is housed in a piston nut that fixes the piston part to the tip of a piston rod that is inserted into the cylinder. structure. (3) The damping force generating structure of a hydraulic shock absorber according to claim 1, wherein the annular leaf valve is housed in a base valve portion disposed at the lower end of the cylinder.