JPH05296282A - Hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To perform variable control of the damping force characteristics of both the expansion and compression strokes of a cylinder by disposing a back valve in a passage, and communicating the passage with a bypass line from lower to upper operating oil rooms through a compression side variable orifice which operates in conjunction with a variable orifice, the bypass line having a check valve interposed therein. CONSTITUTION:During the compression stroke in which a piston 2 moves toward a lower operating oil room B, the operating oil in the lower operating oil room B pushes a back valve 5 open from the compression side port 2a of the piston 2 irrespective of vibrational frequency and flows into an upper operating oil room A. Also the oil pushes a check valve 6 open from the through hole 4f of a piston nut 4 and passes through a compression side variable orifice 15d and flows into the upper operating oil room A while pushing a check valve 24 open through a check port from an inner passage 15f. Simultaneously, the oil flows into a reservoir room through a base valve. A compression-side damping force is generated by the combined action of the back valve 5 and the compression side variable orifice 15d and by the base valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention intends to improve the riding comfort of a vehicle by automatically keeping the extension side damping force low when the unsprung vibration frequency of a traveling vehicle enters a high frequency range above a set value. At the same time, the present invention relates to an improvement of a dependent frequency variable hydraulic shock absorber capable of appropriately adjusting the set high frequency range of the unsprung vibration frequency for keeping the extension side damping force low.

[0002]

2. Description of the Related Art When the vibration frequency enters a high frequency range above a set value, a phase difference is given to the hydraulic pressure transmitted from the upper working oil chamber to the pressure chamber for adjusting the extension side damping force, that is, in the upper working oil chamber. The generated hydraulic pressure is transmitted as a first-order lag to the pressure chamber for adjusting the extension-side damping force (hereinafter referred to as the first-order lag pressure chamber) to keep the extension-side damping force low, and the set high-frequency range for keeping the extension-side damping force low. As a dependent frequency variable hydraulic shock absorber that can be appropriately adjusted, for example, there is one shown in Japanese Patent Application Publication No. 168435.

In this device, a variable orifice is provided in a passage connecting the upper hydraulic oil chamber and the first-order lag pressure chamber, and when the vibration frequency enters a high frequency range above a set value, the upper hydraulic oil is made to flow through the variable orifice. The generated hydraulic pressure in the chamber is transmitted to the first-order lag pressure chamber with a phase difference, and the rise-side damping force is kept low by suppressing an increase in the hydraulic pressure in the first-order lag pressure chamber, and the extension-side damping force is kept low by adjusting the variable orifice. The set high frequency range can be adjusted appropriately.

[0004]

As described above, the above hydraulic shock absorber has a structure capable of controlling the damping force frequency dependency from hard to soft by controlling the damping force frequency dependence by selecting the variable orifice diameter. However, it is said that this is not sufficient in terms of ride comfort and steering stability of the vehicle because it cannot be variably controlled even during the expansion stroke of the piston and the damping force characteristic during the compression stroke cannot be variably controlled. Have problems.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a damping force frequency dependent variable type hydraulic shock absorber of this type dependent frequency variable type capable of variably controlling the damping force characteristics of both the expansion stroke and compression stroke of the piston. The purpose is to provide a hydraulic shock absorber.

[0006]

In order to achieve the above object, according to the present invention, there is provided a passage leading from the upper working oil chamber to the lower working oil chamber through the extension side damping force generating valve, and the upper working oil chamber. Is connected to the primary lag pressure chamber of the extension side damping force generation valve, and a variable orifice is inserted in the latter passage to reduce the extension side damping force with the adjustment operation of this variable orifice. In a variable frequency variable type hydraulic shock absorber capable of appropriately adjusting the above, a passage for communicating the lower working oil chamber with the upper working oil chamber and a pressure side variable orifice interlocking the lower working oil chamber with the variable orifice are also provided. A bypass valve communicating with the upper hydraulic oil chamber is formed, and a rear valve that opens toward the upper hydraulic oil chamber side is provided in the former passage, and the upper hydraulic oil chamber is also provided in the latter passage. We are taking a structure in which interposed a check valve that opens toward the side.

[0007]

According to the present invention, therefore, the damping force frequency dependency during the expansion stroke of the piston is controlled by selecting the variable orifice diameter, and at the same time, the damping force during the compression stroke of the piston is linked with the control of this variable orifice. The pressure side variable orifice diameter interposed in the pressure side bypass passage of the rear valve which is a force generating valve will also be controlled,
The damping force characteristics of both the extension stroke and compression stroke of the piston are simultaneously variable.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

As shown in FIG. 1, a hydraulic shock absorber according to an embodiment of the present invention includes a cylinder 1 having a closed cylindrical body, a piston 2 slidably inserted into the cylinder 1, and a piston 2 to a cylinder. 1 and a piston rod 3 extending outwardly through the upper end sealed portion.

The piston 2 is fitted into the lower spigot portion 3e of the piston rod 3, and a gasket 18 made of a seal member such as metal rubber is applied to the lower surface of the piston 2 and the gasket 18 serves to connect the piston 2 and the piston rod 3. While sealing the joint surfaces of the lower spigot portion 3e and the piston nut 4, the piston rod 3 is fixed to the piston rod 3 with a piston nut 4 screwed to the lower end spiral portion 3a of the piston rod 3 from below. It is divided into an upper hydraulic oil chamber A on the rod side and a lower hydraulic oil chamber B on the head side, and the hydraulic oil in the upper hydraulic oil chamber A is generated from the piston 2 in the expansion side damping force during the expansion stroke of the hydraulic shock absorber. By flowing through the mechanism to the lower hydraulic oil chamber B, the extension side damping force generating mechanism portion generates the damping force during the extension stroke, and the compression stroke At times, hydraulic oil in the lower hydraulic oil chamber B is caused to flow from the piston 2 and a known base valve (not shown) to the upper hydraulic oil chamber A and the reservoir chamber through the respective pressure side damping force generating mechanisms, so that these pressure side damping force generating mechanisms are generated. A damping force is generated during the compression stroke in the area.

For this purpose, the piston 2 is provided with two sets of port groups, an outer peripheral side pressure side port 2a and an inner peripheral side extension side port 2b, which communicates the upper working oil chamber A and the lower working oil chamber B. In the pressure side port 2a group, the lower end opens directly to the lower hydraulic oil chamber B, and the upper end communicates with the upper hydraulic oil chamber A through the back valve 5 which is a pressure side damping force generating mechanism. The lower end of the 2b group is the hole 1 of the gasket 18.
8b communicates with the extension side damping force generating mechanism side through a passage 4b formed in the piston nut 4, and an upper end communicates with an upper hydraulic oil chamber A through an annular groove 2e formed on the upper surface of the piston 2 through a passage 2f.

On the other hand, the extension side damping force generating mechanism extending from the piston nut 4 to the piston rod 3 and the damping force characteristic of the extension side damping force generating mechanism together with the damping force of the rear valve 5 which is the compression side damping force generating mechanism. It contains a control mechanism that also controls the characteristics.

The extension side damping force generating mechanism is composed of a piston nut 4
Annular rib 8 of the supporting member 8 which is crimped to the inside of the lower end of the
e and the annular rib 9e of the valve seat 9 arranged so as to face the upper surface of the support member 8 and is configured as a fixed outer peripheral leaf valve 10, and the control mechanism will be described later in detail. As will be described, a push member 11 vertically movably fitted into the inner peripheral surface of the valve seat 9, a leaf spring 13 crimped to the push member 11 by a pin 12, and a block member 14 arranged above them. , And an expansion side control mechanism including a control valve 15 having an expansion side variable orifice 15c rotatably accommodated in a through hole 3c penetrating the piston rod 3 and a compression side variable mechanism formed in the control valve 15 as well. The pressure side control mechanism includes an orifice 15d and a check port 15e.

The valve seat 9 of the extension side damping force generating mechanism is
A plurality of through holes 9b arranged side by side on a concentric circle, and an annular groove 9d formed on the lower surface in communication with these through holes 9b,
Push member 11 on the control mechanism side, leaf spring 13
Also, together with the block member 14, the upper end of the cap-shaped member 16 having the opening 16b is hooked on the block member 14, and the lower end of the cap-shaped member 16 is press-fitted into the valve seat 9 to be assembled in advance as a subassembly. ..

Then, the stepped portion 14e of the sub-assembled block member 14 and the shoulder portion 4e of the piston nut 4 are provided.
By inserting the guide portion 14f of the block member 14 into the through hole 4c of the piston nut 4 with the elastic body 17 having a sealing function interposed between the piston nut 4 and the block member 14 The joint surface is sealed oil-tight and the entire sub-assembled component is always pressed downward.

Thus, the leaf valve 10 has the elastic body 1.
The outer peripheral portion is sandwiched by the annular rib 8e of the support member 8 and the annular rib 9e of the valve seat 9 from above and below by the restoring force of 7, and the inner peripheral upper surface of the leaf valve 10 is the seat on the inner peripheral lower surface of the valve seat 9. Normally, the annular groove 9d formed between the annular rib 9e of the valve seat 9 and the seat portion 9f is closed by pressing against the portion 9f, and the upper hydraulic oil chamber A moves from the passage 2f on the upper surface of the piston 2 to the extension side port. 2b-passage 4b of piston nut 4-opening 16b of cap-shaped member 16
-And through hole 9b of valve seat 9-like annular groove 9d
Through the lower hydraulic oil chamber B through the leaf valve 10
Is blocked by.

The leaf valve 10 is clamped by utilizing the restoring force of the elastic body 17 because the leaf valve 10 is clamped by the dimension error of the support member 8, the valve seat 9, the cap-shaped member 16 and the like. This is to prevent backlash.

The extension side control mechanism for controlling the extension side damping force generating mechanism is composed of a push member 11 fitted on the inner peripheral surface of the valve seat 9 so as to be vertically movable, and a pin 12 caulked at the center of the push member 11. It has a stopped leaf spring 13.

The leaf spring 13 is clamped at its outer peripheral portion between the valve seat 9 and the block member 14 at the time of the previous subassembly, and the spring force of the leaf spring 13 normally keeps the push member 11 in the upper position.

Further, in this state, the valve seat 9
The lower surface sheet portion 11e of the push member 11, which is formed to have the same thickness as the above, is close to the upper surface on the inner peripheral side of the leaf valve 10 and faces or contacts the upper surface.

A first-order lag pressure chamber R for adjusting the extension side damping force is formed between the leaf spring 13 connected to the push member 11 with the pin 12 and the lower surface of the block member 14, and the first-order lag pressure chamber R is formed. R is a through hole 14c of the block member 14 through a through hole 4c of the piston nut 4 and a through hole 3c for adjustment formed in the piston rod 3, and a control valve 15 rotatably fitted in the through hole 3c. The internal passage 15f leads to the expansion side variable orifice 15c, a compression side variable orifice 15d, which will be described later, and a check port 15e.

On the other hand, the inner peripheral surface of the piston 2 is provided with an annular groove 2c which is located on the same plane as the expansion side variable orifice 15c. On the one hand, the annular groove 2c is provided at the lower end inlay of the piston rod 3. Through the through hole 3d formed in the portion 3e, the expansion side variable orifice 15c of the control valve 15 is communicated, and on the other hand, through the through hole 2d formed in the piston 2, the annular groove 2e on the upper surface of the piston 2 and the passage 2f are passed through the upper hydraulic oil. It communicates with room A.

Thus, the upper hydraulic oil chamber A has the piston 2
From the passage 2f on the upper surface of the same-an annular groove 2e-a through hole 2d of the piston 2-an annular groove 2c-a through hole 3d of the lower end spigot portion 3e of the piston rod 3-a variable side expansion orifice 15c of the control valve 15-an internal passage thereof. 15f-
Through hole 3 of lower end spigot portion 3e of piston rod 3
The hydraulic pressure in the upper working oil chamber A is guided to the primary lag pressure chamber R through the variable orifice 15c, and communicates with the primary lag pressure chamber R through the through hole 14c of the c-block member 14.

The pressure side control mechanism for controlling the damping force characteristic of the back valve 5 which is the compression side damping force generating mechanism includes a pressure side variable orifice 15d formed above and below the control valve 15 with the variable orifice 15c of the expansion side control mechanism interposed therebetween. The check port 15e is provided, and the pressure side variable orifice 15d and the check port 15e are provided in the internal passage 15 of the control valve 15.
They communicate with each other through f.

The pressure side variable orifice 15d includes an annular recess 4d formed in the piston nut 4 through a through hole 3f formed in the lower end fitting portion 3e of the piston rod 3 and a passage 4b.
Is communicated with the lower hydraulic oil chamber B through a through hole 4f (see FIG. 2) formed in the piston nut 4 so as not to interfere with the through hole 4f. A check valve 6 that opens toward the annular recess 4d is provided.

A disc 23 is provided on the outer peripheral surface of the spigot portion 3e of the piston rod 3 which is located on the same plane as the check port 15e.
An annular groove 23c is formed on the inner peripheral surface of the control valve 15. On the other hand, the annular groove 23c is formed on the outer peripheral surface of the control valve 15 from a through hole 3g formed in the lower end inlay portion 3e of the piston rod 3. Check port 15e through 15g
On the other hand, on the other hand, a check valve 24 that opens toward the upper hydraulic oil chamber A side is opened on the upper side of the disk 23 through a through hole 23d formed in the disc 23. A check spring 26 and a valve stopper 27 are provided above the check valve 24 with the spacer 25 interposed therebetween.

The valve stopper 27, check spring 26, spacer 25, check valve 24,
The disc 23, the valve stopper 7, the rear valve 5 of the compression side damping force generating mechanism 5, the piston 2 and the gasket 18 are sequentially stacked to form the lower end spigot portion 3e of the piston rod 3.
The lower end spiral portion 3a of the piston rod 3 by screwing the piston nut 4 from below into the upper end of the piston nut 4 and the piston rod 3
They are fixed between the stepped portion 3b and the stepped portion 3b.

Thus, the lower hydraulic oil chamber B has the piston 2
From the pressure side port 2a through the rear valve 5 to the upper hydraulic oil chamber A, and the through hole 4f of the piston nut 4-check valve 6-annular groove 4d-through hole 3f-pressure side variable orifice 15d-internal passage 15f-check port 15e.
-Annular groove 15g-Through hole 3g-Annular groove 23c-Through hole 23d
To the upper hydraulic fluid chamber A through the bypass passage and the check valve 24.

From the control valve 15, the piston rod 3
The control rod 20 extends to the outside through the through hole 3c, and the expansion side variable orifice 15c is rotated by operating the control valve 15 from the outside via the control rod 20.
The opening area of each of the pressure side variable orifice 15d and the pressure side variable orifice 15d can be controlled at the same time.

At this time, the check port 15e is always kept in communication with the through hole 3g by the action of the annular groove 15g regardless of the rotation operation of the control valve 15.

Further, the control rod 20 and the piston rod 3
A seal 21 is kept oil-tight from the through hole 3c of
In addition, below the control valve 15, a cylindrical stopper 22 for preventing the control valve 15 from slipping out of the control rod 20 is provided.
It is located and fitted in c.

According to the hydraulic shock absorber constructed as described above, during the compression stroke in which the piston 2 moves toward the lower working oil chamber B, the lower working oil chamber B is irrespective of the vibration frequency. The hydraulic oil inside pushes the rear valve 5 from the pressure side port 2a of the piston 2 and flows into the upper working oil chamber A, and at the same time pushes the check valve 6 from the through hole 4f of the piston nut 4 to open the pressure side variable orifice 15d. Pass through, and from the internal passage 15f to the check port 15e
Through the check valve 24 to the upper hydraulic oil chamber A while opening the check valve 24, and also through the well-known base valve (not shown) to the reservoir chamber. To occur.

On the contrary, during the extension stroke in which the piston 2 moves toward the upper working oil chamber A side, the working oil in the upper working oil chamber A flows from the passage 2f of the piston 2 into the annular groove 2e-. Expansion side port 2b-through hole 18 of gasket 18
b-passage 4 of piston nut 4 b-cap member 16
16b-through the through hole 9b of the valve seat 9, the inner peripheral side of the leaf valve 10 is bent downward to generate an extension side damping force and flows to the lower hydraulic oil chamber B, while the extension side damping force itself is generated. The generated hydraulic pressure in the upper hydraulic oil chamber A is from the annular groove 2e of the piston 2 to the through hole 2d-the annular groove 2c-the through hole 3d of the lower spigot portion 3e of the piston rod 3-the expansion side variable orifice 15c- of the control valve 15. Internal passage 15f
-Through hole 3c of piston rod 3-Through hole 4c of piston nut 4-Through hole 14c of block member 14 is guided to the primary delay pressure chamber R, and push member 11 is pushed downward against leaf spring 13 by this hydraulic pressure. It works like pushing down.

Therefore, if the vibration frequency during the expansion stroke is equal to or lower than the vibration frequency set by the expansion side variable orifice 15c at that time, the generated hydraulic pressure in the upper hydraulic chamber A (as described above = expansion side damping force). Acts on the primary lag pressure chamber R through the expansion side variable orifice 15c, pushes down the push member 11 to bend the inner peripheral end side of the leaf valve 10 downward, and increases the initial load of the leaf valve 10 to provide a predetermined damping force. When the vibration frequency in the expansion stroke exceeds the vibration frequency set by the expansion side variable orifice 15c, the generated hydraulic pressure in the upper hydraulic oil chamber A is transmitted to the primary lag pressure chamber R through the expansion side variable orifice 15c. 2 moves to the compression stroke, so-called expansion side variable orifice 1
5c performs a primary delay action, the hydraulic pressure in the primary delay pressure chamber R does not rise and is kept at a low value, and the push member 11 is kept in the raised position by the spring force of the leaf spring 13 while the leaf valve is being held. Since the inner peripheral end side of 10 is not bent downward, the generated damping force becomes lower than a predetermined value,
It acts as a frequency-dependent hydraulic shock absorber with a high-cut effect.

FIG. 3 is a hydraulic circuit diagram showing the flow of hydraulic oil during the expansion / contraction stroke of the hydraulic shock absorber described above. During the expansion stroke, the hydraulic oil flows as indicated by the solid line arrow. In addition, during the compression stroke, a flow of hydraulic oil occurs as indicated by the broken line arrow.

From the above, by operating the control valve 15 from the outside through the control rod 20 to increase the opening area of the expansion side variable orifice 15c, the upper hydraulic oil chamber A
Since the phase delay of the hydraulic pressure transmitted from the primary delay pressure chamber R is small and the gain is high, the extension side damping force characteristic becomes a high damping force, and the frequency dependency becomes large if the extension side variable orifice 15c opening area is reduced to be small. The extension side damping force characteristic becomes a high cut characteristic, and the high cut characteristic with respect to the input frequency can be freely selected by appropriately selecting the size of this opening area. Further, the opening area of the extension side variable orifice 15c is made zero. By doing so, the hydraulic pressure in the first-order lag pressure chamber R does not rise and is always kept low, so that the extension side damping force characteristic becomes a low damping force, and thus this hydraulic shock absorber is also a variable frequency dependent hydraulic shock absorber. To work.

Further, as the control valve 15 is operated, the opening area of the expansion side variable orifice 15c changes in parallel with the opening area of the compression side variable orifice 15d in a predetermined combination. Will be adjusted.

Therefore, if the combination of the opening areas of the expansion side variable orifice 15c and the compression side variable orifice 15d is selected in advance for the check port 15e which is always open, for example, as shown in FIG. Fig. 5 shows the extension side damping force and the compression side damping force as the hydraulic shock absorber expands and contracts.
As shown in the conceptual diagram of the damping force characteristic of, it is possible to adjust in three stages of hard, soft and medium.

On the other hand, when the opening area of the expansion-side variable orifice 15c is switched from a large state to a small state or a closed state, or regardless of the opening area of the variable orifice 15c, the expansion stroke has a low frequency and the compression stroke has a small compression stroke. Is oscillated at a high frequency, the hydraulic pressure in the primary hydraulic pressure chamber R hardly decreases even at the end of the compression stroke in which the hydraulic pressure generated in the upper hydraulic fluid chamber A decreases, and A state in which the hydraulic pressure in the first-order lag pressure chamber R is higher than that occurs, and in any case, the damping force generated in the extension stroke always becomes a high damping force, and the damping force frequency characteristic (damping force mode) can be switched. Although there is a possibility that it may not be possible, even in such a case, the provision of the check port 15e as a part of the pressure side bypass passage helps prevent this. .

That is, even in the above case, if the hydraulic pressure in the upper working oil chamber A decreases during the compression stroke and a pressure difference occurs with the hydraulic pressure in the first-order lag pressure chamber R, it is immediately checked. When the valve 24 opens and the extension stroke occurs, the primary delay pressure chamber R
The amount of hydraulic oil flowing into the valve is quickly returned from the check port 15e to the upper hydraulic oil chamber A through the annular groove 15g-the through hole 3g-the annular groove 23c-the through hole 23d, and the primary lag pressure chamber R is reached by the end of the compression stroke. The hydraulic pressure inside is made equal to the hydraulic pressure inside the upper hydraulic chamber A.

Therefore, even in the continuous vibration state, the frequency characteristic of the extension side damping force can be reliably switched by adjusting the opening area of the variable orifice 15c.

In the above embodiments, the case where the present invention is applied to the hydraulic shock absorber in which only the extension side damping force is frequency dependent has been described as an example, but both the extension side and compression side damping forces are described. It goes without saying that the present invention can also be applied to a frequency-dependent hydraulic shock absorber.

FIG. 6 shows an embodiment in that case, and the extension side in the embodiment of FIG. 1 is also applied to the base valve 40 which is a compression side damping force generating mechanism arranged at the lower end of the cylinder 1. A frequency-dependent compression-side damping force generation mechanism similar to the damping force generation mechanism is provided.

That is, the base valve 40, which is the compression side damping force generating mechanism, has the support member 41 fitted to the lower end of the cylinder 1.
Has an outer peripheral fixed leaf valve 43 whose upper and lower outer peripheral surfaces are sandwiched by an annular rib 41e of the base member 41 and an annular rib 42e of a valve seat 42 arranged so as to face the upper surface of the support member 41. A compression damping force is generated at the valve 40.

Leaf valve 4 for generating the compression side damping force
In order to give the frequency-dependent characteristic to 3, the base valve 40 further includes a push member 44 that is vertically movably housed on the inner peripheral surface of the valve seat 42.
A leaf spring 46, which is caulked by a pin 45, a disc 47 arranged above the leaf spring 46, and an orifice plate 48 which is provided so as to overlap with the disc 47.

The valve seat 42 is provided with a plurality of through holes 42b which are bored side by side on a concentric circle and an annular groove 42d which is formed on the lower surface and communicates with the through holes 42b. The push member 44, the leaf spring 46 and Together with the disc 47, the upper end of the cap member 49 having the opening 49b is hooked on the disc 47, and the lower end of the cap member 49 is press-fitted into the valve seat 42 to be preassembled as a sub-assembly.

The leaf spring 46 and the disc 4
7 is a primary lag pressure chamber R1. This primary lag pressure chamber R1 communicates with the lower hydraulic oil chamber B in the cylinder 1 from the hole 47c formed in the disk 47 through the orifice hole 48c of the orifice plate 48. There is.

Then, the sub-assembled members are vertically movably housed in a case member 50 having an opening 50b in which the lower end is press-fitted and attached to a support member 41, and between the disc 47 and the case member 50. The base valve 40 is configured by pressing the annular rib 42e of the valve seat 42, which is sub-assembled with the spring 51 interposed therebetween, against the leaf valve 43.

Thus, the leaf valve 43 of the base valve 40 has its outer peripheral portion clamped from above and below by the supporting member 41 and the annular ribs 41e, 42e of the valve seat 42 by the restoring force of the spring 51, and the leaf valve 43
The inner peripheral upper surface of the valve seat 42 is pressed against the seat portion 42f of the inner peripheral lower surface of the valve seat 42 to close the annular groove 42d of the normal valve seat 42.

On the other hand, each mechanism provided on the piston 2 side is functionally the same as that of the embodiment of FIG. 1 described above, and only a part of the structure is different. Therefore, since the same structural parts and the same functional parts as those of the embodiment of FIG. 1 can be easily understood based on the above description, the description thereof will be omitted as much as possible by giving the same reference numerals in order to prevent the description from being complicated. However, only structurally different portions will be described below.

In this embodiment, the pressure side port 2a group and the extension side port 2b group provided in the piston 2 are formed as oblique holes, and the pressure side port 2a group has its lower end directly opened to the lower working chamber B. The upper end communicates with the recess 2g formed on the upper surface of the piston 2 through the check valve 6 pressed by the spring 53.

On the other hand, the recessed portion 2g covers the recessed portion 2g from the hole 54a of the valve seat 54 provided on the upper surface of the piston 2 through the rear valve 5 which is the compression side damping force generating mechanism and the upper hydraulic oil chamber A. On the other hand, from the through hole 3f formed in the lower spigot portion 3e of the piston rod 3 to the pressure side variable orifice 15d of the control valve 15-the internal passage 15f thereof-also the check port 15e-the annular groove 15g.
-Through hole 3g-An annular groove 23c of the disk 23-Similarly through hole 23d-Check valve 24 communicates with the upper hydraulic oil chamber A.

The extension side port 2b group has its upper end directly opened to the upper hydraulic oil chamber A, and its lower end communicates with an annular groove 3h formed on the lower surface of the piston 2, and this annular groove 3h has a through hole on one side. 2d from the annular groove 2c-the through hole 3d formed in the lower spigot portion 3e of the piston rod 3-the expansion side variable orifice 15c of the control valve 15-the internal passage 15f to the primary delay pressure chamber R, and at the same time the piston nut The lower hydraulic oil chamber B is also communicated from the passage 4b of No. 4 through the leaf valve 10 which is the expansion side damping force generating mechanism.

In the case of the embodiment of FIG. 6, the disk 23 is formed in a disk shape, and the lower surface thereof also serves as a valve stopper for the rear valve 5.

Further, the block member 14 of the extension side damping force generating mechanism seals between the shoulder portion 4e of the piston nut 4 and the stepped portion 14e of the block member 14 in the case of the embodiment shown in FIG. The elastic body 17 having the function is interposed to seal the portion and to apply the pressing force to the block member 14. However, in the embodiment of FIG. The disc spring 19 is interposed between the portion 4e and the stepped portion 14e of the block member 14, and
A seal 5 is provided on the outer peripheral surface of the guide portion 14f of the block member 14.
By providing 2, the portion is sealed and a pressing force is applied to the block member 14.

From this, if the embodiment of FIG. 6 is shown in a hydraulic circuit diagram like FIG. 3 in the previous embodiment, it becomes like FIG. 7. From the comparison of these FIG. 3 and FIG. It will be readily appreciated that each mechanism performs the same function as in the previous embodiment of FIG.

Further, in the embodiment of FIG. 6, the base valve 40 itself is also constructed as a frequency-dependent type based on the hole diameter of the orifice hole 48c, so that by operating the control rod 20, the extension side damping force and It is clear that the compression side damping force can be adjusted in three stages of hard, medium and soft as shown in the conceptual diagram of damping force characteristics of FIG.

[0058]

As described above, according to the present invention, in the hydraulic shock absorber of the damping force frequency dependent variable system, the damping force characteristics of both the extension stroke and the compression stroke of the piston are variably controlled based on a preferable combination. This makes it possible to contribute to improving the riding comfort of the vehicle and improving the steering stability.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of a hydraulic shock absorber according to an embodiment of the present invention in a cut-away manner.

FIG. 2 is a cross-sectional view taken along line XX in FIG.

FIG. 3 is a hydraulic circuit diagram of the embodiment of FIG.

FIG. 4 is a table showing the relationship between the control valve and the generated damping force.

5 is a graph conceptually showing damping force control characteristics in the embodiment of FIG.

FIG. 6 is a view showing a main part of a hydraulic shock absorber according to another embodiment of the present invention in a cut-away manner.

FIG. 7 is a hydraulic circuit diagram of the embodiment of FIG.

8 is a graph conceptually showing damping force control characteristics in the embodiment of FIG.

[Explanation of symbols]

 A Upper hydraulic oil chamber B Lower hydraulic oil chamber R, R1 Primary lag pressure chamber 2 Piston 2a Pressure side port 2b Extension side port 3 Piston rod 3e Lower end inlay part 4 Piston nut 5 Rear valve 9 which is a pressure side damping force generating mechanism 9 Valve seat 10 Leaf valve which is extension side damping force generating mechanism 11 Push member 15 Control valve 15c Extension side variable orifice 15d Pressure side variable orifice 15e Check port 18 Gasket 20 Control rod 24 Check valve 40 Base valve 43 Leaf valve which is pressure side damping force generating mechanism 48c Orifice hole

Claims (1)

[Claims] 1. A passage, which leads from the upper hydraulic oil chamber to the lower hydraulic oil chamber through the expansion side damping force generating valve, and a passage which connects the upper hydraulic oil chamber to the primary lag pressure chamber of the expansion side damping force generating valve, the latter. In the hydraulic damper of the dependent frequency variable type in which the variable orifice is interposed in the passage of the variable orifice, it is possible to appropriately adjust the high frequency range in which the expansion side damping force is reduced in accordance with the adjustment operation of the variable orifice. A passage for communicating the hydraulic oil chamber with the upper hydraulic oil chamber and a bypass passage for communicating the lower hydraulic oil chamber with the upper hydraulic oil chamber through the pressure side variable orifice interlocking with the variable orifice are formed respectively, and the upper passage is connected to the upper passage. A rear valve that opens toward the hydraulic oil chamber side is provided, and a check valve that opens toward the upper hydraulic oil chamber side is also installed in the latter passage, which is a hydraulic pressure relief feature. Impulse device.