JPH0510536B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic shock absorber, and particularly to a hydraulic shock absorber capable of performing a so-called high-cut action that reduces damping force in a region above a given frequency.

[Conventional technology]

Various proposals have been made in the past for devices that perform a so-called high-cut effect that reduces the damping force in a region above a given frequency.

According to these proposals, it is theoretically disclosed that a high-cut effect is exhibited in a frequency range equal to or higher than a predetermined frequency.

[Problem that the invention seeks to solve]

However, when using the above-mentioned conventional proposals, there are disadvantages such as not being able to obtain the desired stable high-cut action, increasing the number of processing steps to obtain the desired configuration, and increasing the number of parts.

In other words, the reality is that no hydraulic shock absorber has yet been proposed that can provide a stable damping force reduction effect in a frequency range above a given frequency and is economically advantageous.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hydraulic shock absorber having a new configuration that is capable of performing a stable so-called high-cut action in a frequency range above a given frequency range and is economically advantageous.

[Means for Solving the Problems] In order to solve the above problems, the structure of the present invention is such that the damping force generated in the damping force generating part when the piston part slides is reduced in a region above a given frequency. In a hydraulic shock absorber formed to be able to and the amount of deflection of the outer circumferential end is made variable by a pressing force applied to the inner circumferential end of the leaf valve, and the pressing force is applied above the inner circumferential end of the leaf valve. The inner peripheral end of the leaf valve is obtained by the internal pressure of a pressure chamber that is formed and communicates with the oil chamber in the cylinder through an orifice, and the internal pressure of the pressure chamber is applied to the inner peripheral end of the leaf valve through a spring that expands and contracts as the push valve slides. It is characterized by being formed so that the transmission is transmitted to a spool that is in contact with the upper surface.

〔Example〕

The present invention will be described below based on illustrated embodiments.

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 the piston portion 3 is attached to the tip of the piston rod 2. A damping force generating section 5 is provided within the fixed piston nut 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 located inside the upper end of the cylinder 1, that is, the upper end of the outer tube 10.
is disposed, and the piston rod 2 is slidably inserted into the shaft core through hole of the bearing member 11. A packing case 13 fixed with a ring nut 12 is disposed above the bearing member 11, and the packing case 13 has a packing 15 held by a packing plate 14. A packing spring 16 is interposed between the packing plate 14 and the lower bearing member 11, and an O-ring 17 is interposed between the upper edge of the outer peripheral end of the bearing member 11 and the lower outer peripheral surface of the packing case 13. equipped.

The inside of the cylinder 1 is divided into a rod side oil chamber A and a piston side oil chamber B by the piston portion 3. Although not shown, a base valve part is formed inside the lower end of the cylinder 1, and the piston side oil chamber B, the cylinder 1, and the outer tube 1 are connected through the base valve part.
0 and is in communication with a reservoir chamber C formed between the two. Note that the gas chamber D is located above the reservoir chamber C.
It is said that Furthermore, leaked oil accumulated on the upper surface of the bearing member 11 flows into the gas chamber D, that is, the reservoir chamber C, through a port 11a formed in the bearing member 11.

Further, the lower end of the cylinder 1 has an attachment eye (not shown) so that it can be connected to the axle side of a vehicle.

Although the piston rod 2 is not shown,
Its upper end is formed so as to enable connection to the vehicle body side or the like. An oil passage 20 is formed inside the piston rod 2 from the lower end to the vicinity of the lower end, and is bored so as to penetrate the axial center of the piston rod 2, and the lower end of the oil passage 20 is It opens on the piston side oil chamber B side, that is, inside the piston nut 4, and the oil passage 20
The upper end thereof communicates with the rod side oil chamber A through a communication hole 21.

Therefore, the hydraulic pressure in the rod-side oil chamber A reaches into the piston nut 4 via the communication hole 21 and the oil passage 20.

The piston part 3 has a piston body 30 that is disposed in the spigot part 22 of the piston rod 2 and fixed by the piston nut 4.
The interior is divided into the rod side oil chamber A and the piston side oil chamber B. An oil passage 31 is bored in the piston body 30, allowing communication between the rod side oil chamber A and the piston side oil chamber B. Furthermore, a check valve 32 made of a leaf valve is disposed on the upper end opening side of the oil passage 31 so as to close the opening.

The check valve 32 is connected to a stopper 3 that is engaged with the stepped portion 23 of the piston rod 2.
It is biased downward by a spring 34 whose upper end is locked to 3. Further, the stopper 33 is formed with a notch 33a through which oil can pass, and a piston ring 35 is interposed on the outer periphery of the piston body 30.

Therefore, the oil passage 31 in the piston portion 3
is a pressure-side oil passage that allows oil in the piston-side oil chamber B to flow into the rod-side oil chamber A only during the pressure stroke in which the piston portion 3 moves downward within the cylinder 1.

The damping force generating section 5 inside the piston nut 4 is
In this embodiment, an annular leaf valve 50 is used as a rebound damping force generating section and is arranged adjacent to the lower end opening of the oil passage 41 of the block 40 disposed inside the piston nut 4. The annular leaf valve 50 is supported such that a support point 52 of a disk 51 screwed inside the lower end of the piston nut 4 comes into contact with the lower surface.

The support point 52 is positioned so as to come into contact with the lower surface of the intermediate portion of the upper annular leaf valve 50, and the leaf is placed on the upper end surface of the outer peripheral side of the disk 51 having the support point 52. A ring seat 53 having the same wall thickness as the valve 50 is provided. The annular seat 53 may be omitted and a raised portion having the same thickness as the leaf valve 50 may be formed in advance at the upper end of the outer peripheral side of the disk 51; however, as in this embodiment, , ring seat 5
3 is advantageous in that the upper surface of the disk 51 can be easily finished and the machining accuracy can be easily managed.

The outer peripheral end of the annular leaf valve 50 is a free end, and the oil in the piston nut 4, that is, in the rod side oil chamber A, passes through the oil passage 41 of the upper block 40.
The outer peripheral end of the leaf valve 50 is bent to allow the oil to flow into the piston side oil chamber B through the oil passage 54 of the disk 51, and a desired rebound damping force is generated when the outer peripheral end of the leaf valve 50 is bent. It's becoming like that. The rebound damping force is determined by the annular leaf valve 5.
It is made variable by applying a pressing force from above to the inner circumferential end of 0.

That is, the push valve 55 is in contact with the upper surface of the inner peripheral end of the annular leaf valve 50, the lower end of the spring 56 is in contact with the upper surface of the push valve 55, and the spring 56 is in contact with the upper surface of the push valve 55.
A spool 57 is in contact with the upper end of the spool 6 . Then, the push valve 55 and the spring 56
The spool 57 is housed in the block 40 within the piston nut 4, and a pressure chamber 58 is formed in the upper surface of the spool 57.
The pressure chamber 58 is defined by a disc-shaped check valve 42 arranged to close the central opening at the upper end of the block 40 in the piston nut 4. Then, the check valve 42
An orifice 43 is bored in the center of the pressure chamber 5.
8 and the inside of the rod side oil chamber A are communicated with each other.

Therefore, when the inside of the rod side oil chamber A becomes a high pressure side, the orifice 43 is placed in the pressure chamber 58.
The reduced hydraulic pressure acts through the
That is, the pressure chamber 58 acts as a pressure reduction chamber, and this reduced hydraulic pressure acts on the push valve 55 via the spool 57 and spring 56, causing the inner peripheral end of the annular leaf valve 50 to move downward. It will be pushed towards the target. Then, by pressing the inner peripheral end from above, the outer peripheral end of the leaf valve 50 is urged to be pressed against the lower surface of the upper block 40, that is, the outer peripheral end of the leaf valve 50 The deflection characteristics of the ends will be changed. Furthermore, by changing the pressure in the pressure chamber 58, the outer peripheral end deflection characteristics of the leaf valve 50 are changed.

The disk-shaped check valve 42 has a spring 44 whose upper end is locked to the piston nut 4.
It is energized downward, that is, toward the top surface of the block 40. Therefore, when the inside of the rod side oil chamber A is on the low pressure side, the check valve 42
is opened, and the pressure within the pressure chamber 58 is eliminated without being accumulated.

The operation of the hydraulic shock absorber according to the present invention formed as described above will be briefly explained.

During the extension stroke in which the piston part 3 moves up inside the cylinder 1, the inside of the rod side oil chamber A becomes a high pressure side, and the oil in the rod side oil chamber A flows through the communication hole 21,
It flows into the piston nut 4 via the oil passage 20. A part of the oil that has flowed into the piston nut 4 is then transferred to the orifice 4 of the check valve 42.
3 into the pressure chamber 58, and other oil flows into the piston-side oil chamber B through the oil passage 41 of the block 40 so as to bend the outer peripheral end of the leaf valve 40. .

At this time, when the vibration frequency in the rod side oil chamber A exceeds a certain range, high pressure is no longer generated in the pressure chamber 58, and the inner peripheral end of the leaf valve 50 is pressed and its outer peripheral end is The pressing force that presses against the block 40 to generate a high damping force is no longer generated, and as a result, the leaf valve 50 returns to its initial deflection characteristics, resulting in a so-called high-cut phenomenon in which the leaf valve 50 stops generating a high damping force. The Rukoto.

That is, as shown in FIG. 2, a push valve 55 is connected to the leaf valve 50 between the hydraulic pressure P ₁ above the check valve 42 on the high pressure side and the pressure P ₂ in the pressure chamber 58 below the check valve 42. The following equation (1) holds true in relation to the force F ₁ that presses the inner peripheral end.

Here, t: Time P ₁ : High pressure side pressure P ₂ : Pressure chamber side pressure of primary lag K: Spring constant of spring 56 A ₂ : Pressure receiving area of spool 57 R ₁ : Fluid resistance of oil flowing through orifice 43 R ₂ : This is the fluid resistance of the oil flowing around the outer circumference of the spool 57.

Therefore, for example, if P ₁ changes in a sinusoidal half wave as shown in equation (2) below, P ₂ changes as shown in FIG. 3 by solving equation (1).

P ₁ =P ₁₀ sin2πt (0≦t≦π/22π) (2) where P ₁₀ is a constant.

Therefore, as can be seen from FIG. 3, as the frequency of P ₁ increases, P ₂ becomes smaller than P ₁ in most of the time domain. In other words, the damping force can be reduced. The rate of decrease and the frequency at which this starts are determined by appropriately selecting the spring constant K of the spool 57, the pressure receiving area A of the spool 57, and the fluid resistances _R1 and _R2 of the oil.
It can be arbitrarily selected and desired characteristics can be obtained.

FIG. 4 shows a hydraulic shock absorber according to another embodiment of the present invention, and the operation of this embodiment is the same as that of the embodiment shown in FIG. 1. However, in its composition,
There are some deformations, and the deformed parts will be explained below.

The piston body 30 in the piston portion 3 includes:
In addition to the oil passage 31 on the compression side, an oil passage 36 on the expansion side is bored. The check valve 32 has a notch 32 at a portion opposite to the upper end opening of the oil passage 36.
It has a. Then, the oil passage 3
The upper end opening of an oil passage 45 bored in the piston nut 4 is opposed to the lower end opening of the piston nut 6 . Furthermore, the lower end of the oil passage 45 opens into the inside of the piston nut 4.

That is, in place of the communication hole 21 and the oil passage 20 in the piston rod 2 in the embodiment shown in FIG. 1, the oil passages 36 and 45 are provided in the piston body 30 and the piston nut 4, respectively.

In this embodiment, the disk 51 is fixed to the lower end of the piston nut 4 by caulking.

FIG. 5 shows an embodiment in which a base valve part 6 is used as the expansion side valve part in the piston part 3 part of FIG. 1.

That is, the lower end of the cylinder 1 has a base valve case 60 between it and the cap member 18 that seals the lower end of the outer tube 10, and the compression side damping force generating section and the base valve are located inside the base valve case 60. The case 60 has a check valve section 7 at the upper end. Note that an eye 19 is fixed to the cap member 18.

Inside the base valve case 60 is a block 6.
1. A leaf valve 62, a disk 63, a ring seat 64, a check valve 65, and a spring 66 are arranged, and a push valve 67, a spring 68, and a spool 69 are provided in the block 61.
is installed. And the base valve 6
The structure inside the piston nut 4 and the structure inside the block 40 are the same as those in the piston nut 4 and the structure inside the block 40 in FIG. The oil in the piston side oil chamber B flows through the center hole 71 of the set bolt 70 into the base valve case 60.
When the oil flows in, a desired compression damping force is generated and a so-called high-cut effect is exerted in a region above a given frequency.

Note that a notch 60a is formed at the lower end of the base valve case 60, allowing communication between the inside of the base valve case 60 and the reservoir chamber C through the notch 60a. Further, a push valve 67, a spring 68, and a spool 69 are housed within the block 61.

In addition, the base valve case 60 has a communication hole 72 in the thick part at the upper end that allows communication between the inside of the piston side oil chamber B and the inside of the reservoir chamber C, and the upper end opening of the communication hole 72 is closed. A leaf valve 73 is provided as a check valve. The leaf valve 73 serving as the check valve is biased downward by a spring 75 whose upper end is brought into contact with a stopper 74 which is secured to the set bolt 70. Further, the stopper 74 has a notch 74a formed therein.

The function of the check valve 73 is as follows:
It is similar to the check valve 32 in FIG. 1, and only allows oil to pass from the lower oil chamber to the upper oil chamber.

FIG. 6 shows a modification of the base valve section 6 and check valve 7 shown in FIG. 5, and is similar to the modification shown in FIG. 4 with respect to FIG. 1.

That is, the compression side damping force generating section in the base valve case 60 is constructed in the same manner as in the case shown in FIG. , instead of this, an oil passage 76 parallel to the communication hole 72 is provided in the thick upper end portion of the base valve case 60.
A lower end of the oil passage 76 is opened into the base valve case 60, and a notch 73a of the leaf valve 73 faces the upper end opening of the oil passage 76. As a result, the oil in the piston side oil chamber B flows into the base valve case 60 via the notch 73a of the leaf valve 73 and the oil passage 76, and the pressure side damping force inside the base valve case 60 is generated. flow into the department. and,
A desired compression damping force is generated and a so-called high-cut action is performed in a region above a given frequency.

〔Effect of the invention〕

As described above, according to the present invention, a stable damping force lowering effect, that is, a high-cut effect can be obtained in a region above a given frequency, and, for example, the riding comfort in a vehicle can be improved.

Further, according to the present invention, the structure of the damping force generating section does not require any special processing inside or outside the piston rod, and especially when the damping force generating section is disposed inside the piston nut, it is possible to make the damping force generating section compact. This results in a reduction in the number of parts and the number of machining steps, which is economically advantageous.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view partially showing a hydraulic shock absorber according to an embodiment of the present invention, Fig. 2 is an enlarged mechanical diagram showing a damping force generating section according to the present invention, and Fig. 3 is a frequency change Characteristic diagram showing the relationship between and pressure change, 4th
The figure is a longitudinal sectional front view showing an embodiment of a hydraulic shock absorber according to a modification of Fig. 1, FIG. 5 is a longitudinal sectional front view partially showing a hydraulic shock absorber according to another embodiment, and FIG.
It is a vertical front view which shows the Example of the hydraulic shock absorber based on the modification of a figure. 1...Cylinder, 2...Piston rod, 3...
... Piston part, 4 ... Piston nut, 5 ... Damping force generating part, 40, 61 ... Block, 42, 6
5...Check valve, 50,62...Leaf valve, 51,63...Disc, 53,64...
Ring seat, 55, 67...button valve, 56, 6
8... Spring, 57, 69... Spool, 5
8...Pressure chamber, A...Rod side oil chamber, B...Piston side oil chamber, C...Reservoir chamber, D...Gas chamber.

Claims (1)

[Scope of Claims] 1. In a hydraulic shock absorber formed to be able to reduce the damping force generated by the damping force generating part when the piston part slides in a region above a given frequency, the damping force generating part is The leaf valve has an annular leaf valve, and is capable of generating a predetermined amount of damping force by bending the outer peripheral end of the leaf valve, and by a pressing force applied to the inner peripheral end of the leaf valve. and is formed so that the amount of deflection of the outer peripheral end is variable, and the pressing force is applied to the internal pressure of a pressure chamber formed above the inner peripheral end of the leaf valve and communicating with the oil chamber in the cylinder via an orifice. and is formed so that the internal pressure of the pressure chamber is transmitted to the spool that is in contact with the upper surface of the inner peripheral end of the leaf valve via a spring that expands and contracts as the push valve slides. A hydraulic shock absorber featuring: 2. Claim 1, in which the damping force generating section is housed in a piston nut that fixes the piston section to the tip of the piston rod inserted into the cylinder.
Hydraulic shock absorber as described in section. 3. The hydraulic shock absorber according to claim 1, wherein the damping force generating section is housed in a base valve section disposed at the lower end of the cylinder.