JPH09264365A - Hydraulic buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the increase of the pressure side damping force load of a piston when the pressure side damping force is hard, and to prevent the defective circulation of the working fluid into a piston upper chamber from a piston lower chamber. SOLUTION: A hydraulic buffer is provided with a first bypass B to connect a piston upper chamber 4 to a piston lower chamber 5 detouring a first expansion side valve 12, and a second bypass C to connect the piston lower chamber 5 to a reservoir chamber 6 detouring a first pressure side valve 15, a second expansion side valve 35 is provided in the first bypass B in an opening/closing manner, a second pressure side valve 36 is provided in the second bypass C in an opening/closing manner, and the first bypass B and the second bypass C are continuously variably adjusted in the opening area by one common switching valve 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber suitable for use in suspension devices such as automobiles, two-wheeled vehicles, and industrial vehicles.

[0002]

2. Description of the Related Art As a conventional damping adjustment type hydraulic shock absorber, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 4-54339. This is slidably fitted to the cylinder,
It has a piston that divides the cylinder into two chambers.

In addition, a valve means for opening and closing the communicating passage is provided by providing a communicating passage for communicating the two chambers with each other in an axial center portion of a piston rod having a base end portion fitted and fixed to the piston. It is provided in the communication passage.

Another conventional damping force adjusting type hydraulic shock absorber is disclosed in Japanese Patent Application Laid-Open No. 62-220728. This is called a triple pipe uniflow adjustable damper, and is configured to share one bypass (soft) valve for both the extension stroke and the pressure stroke.

[0005]

However, in the hydraulic shock absorber disclosed in the above-mentioned Japanese Patent Laid-Open No. 4-54339, since the piston is provided with the pressure side variable mechanism, the piston lower chamber during the pressure stroke. In order to prevent hydraulic oil from sneaking into the piston upper chamber, the variable range of the pressure side damping force is controlled by the piston rod diameter, cylinder diameter, pressure side throttle arranged in series with the damping force varying mechanism and the enclosed gas pressure. There was a problem that there was a limit.

Further, since the extension side and compression side damping force varying mechanisms are installed on the piston, there is a problem that the piston valve length is increased and the working stroke of the piston rod is decreased.

Further, when the hydraulic shock absorber is applied to an electronically controlled suspension, the mounting position of the control actuator or the mounting mechanism is axially in series with the main body of the hydraulic shock absorber, so that mounting work or mounting space is required. There is a case in which there is a restriction in securing the above, and in this case, there is a problem that the working stroke of the piston rod is reduced.

On the other hand, in the hydraulic shock absorber disclosed in JP-A-62-220728, since the variable range of damping force on the extension side and the compression side is influenced by the piston rod diameter and the cylinder diameter, they are independent of each other. There was a problem that the variable operation could not be performed.

The present invention is to solve the above-mentioned conventional problems, and it is possible to obtain a large damping force variable range for both the extension stroke and the compression stroke by one adjusting means, and at the same time, a damping force adjusting mechanism can be obtained. It is an object of the present invention to provide a hydraulic shock absorber that is compact and that can secure a sufficient working stroke of a piston rod.

[0010]

In order to achieve the above object, in the hydraulic shock absorber according to the invention of claim 1, a piston rod is movably inserted into a cylinder via a piston, and the piston is in the cylinder. To define a piston upper chamber and a piston lower chamber, and these piston upper chamber and piston lower chamber are opened and closed via a first extension side valve provided in the piston, and the piston lower chamber is further a base valve below the cylinder. In a hydraulic shock absorber that is opened and closed by a reservoir chamber outside the cylinder via a first pressure side valve provided in the member, a first shock absorber that bypasses the first extension side valve and connects the piston upper chamber and the piston lower chamber And a second bypass that bypasses the first pressure side valve and connects the piston lower chamber and the reservoir chamber, and the second expansion side valve is openable and closable during the first bypass. , During the second bypass is provided to freely open and close the second pressure side valve further first bypass and a second
The bypass is configured so that the opening area can be adjusted steplessly by one shared switching valve.

Further, in the hydraulic shock absorber according to the invention of claim 2, the switching valve has a first position in which the first bypass and the second bypass are simultaneously closed, and a second position in which the first bypass and the second bypass are simultaneously opened. The opening areas of the bypass and the second bypass are configured to be increased or decreased at the same time.

Further, in the hydraulic shock absorber according to a third aspect of the present invention, the switching valve has the first position in which the second bypass is opened and the first bypass is closed, and the first bypass is opened and the second bypass is opened. The second position and the first position
And a third position in which the second bypass and the second bypass are simultaneously opened, and when the opening area of one bypass increases, the opening area of the other bypass decreases.

Further, in the hydraulic shock absorber according to the invention of claim 4, the opening areas of the first bypass and the second bypass are divided into soft side, medium side and hard side, respectively. It can be adjusted in three steps to replace it.

In the hydraulic shock absorber according to the invention of claim 5, the switching valve is a solenoid switching valve controlled by current or voltage.

Further, in the hydraulic shock absorber according to the invention of claim 6, the switching valve is structured such that the stroke is controlled by hydraulic pressure or pneumatic pressure.

In the hydraulic shock absorber according to the invention of claim 7, the stroke of the switching valve is controlled by a screwing operation.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram showing the basic structure of a hydraulic shock absorber, and FIG. FIG. 1 is a vertical cross-sectional view showing a dynamic structure, 1 is a piston rod, 11
Is a piston attached to the lower end of the piston rod 1 and sliding in the cylinder 2. 2a and 2b are oil holes formed in the upper and lower portions of the cylinder 2, respectively.

Reference numerals 7 and 14 denote an upper plate and a base valve member for closing the upper and lower ends of the cylinder 2, and the piston 11 inside the cylinder 2 closed by the upper plate 7 and the base valve member 14. Partition into a piston upper chamber 4 and a piston lower chamber 5. The piston rod 1 passes through the upper plate 7, the seal member 10 and a center hole at the outer shell end described later.

Reference numeral 3 denotes an outer shell which separates a reservoir chamber 6 for hydraulic oil from the outer circumference of an inner tube 21 suspended from an upper plate 7. A gap 8 between the outer shell 3 and the base valve member 14 and a reservoir. It communicates with the chamber 6 via an oil passage 9.

Reference numeral 12 denotes an expansion side hard valve as a first expansion side valve provided on the piston 11, and 1
A check valve 3 is provided in the piston 11 and permits the flow of the hydraulic oil from the piston lower chamber 5 to the piston upper chamber 4.

Further, 15 is a pressure side hard valve as a first pressure side valve provided in the base valve member 14, and 16 is provided in the base valve member 14 from the reservoir chamber 6 to the piston lower chamber 5. A check valve that allows the flow of hydraulic oil.

Reference numeral 21 is an inner tube of a predetermined length attached to the upper plate 7 via a seal ring 7a, which is interposed between the cylinder 2 and the outer shell 3. 22 is this inner tube 21
Is a substantially cylindrical joint that is oil-tightly fitted between the lower end of the base valve member 16 and the base valve member 16.
An oil hole 22a is formed in the upper part of the No. 2.

On the inner peripheral side of the joint 22, there is provided a compartment projection 22b which is in close contact with the outer periphery of the cylinder 2, and which forms an oil hole 2 between the cylinder 2 and the joint 22.
It is divided into an upper gap 22c communicating with a and a lower gap 22d communicating with the oil hole 2b.

Reference numeral 32 denotes a cylindrical inner disk member, which comprises a small diameter portion 32d and a large diameter portion 32e, of which the small diameter portion 32d is mounted at a position communicating with the lower gap 22d of the joint 22.

The inner disk member 32 has an oil hole 32a at the center and an oil passage 32b penetrating from the annular vertical surface portion to the ring-shaped valve seat surface portion 32f within the thickness of the large diameter portion 32e.

Further, the large diameter portion 32 of the disc member 32.
A ring-shaped flange portion 32g is vertically projectingly provided on the outer periphery of e, and an oil hole 32c is bored through the ring-shaped flange portion 32g. The small diameter portion 3 is located at a position (valve seat portion) facing the annular vertical end surface of the oil hole 32b.
A compression-side soft valve 36 as a ring-shaped second compression-side valve fitted in the outer peripheral base of 2d is in contact.

Reference numeral 33 denotes a housing in which a disc portion 33c is tightly fitted on the outer circumference of the small diameter portion 32d between an outer disc member 31 and an inner disc member 32, which will be described later. The outer circumference of the diameter portion 31c is oil-tightly held, and the inner circumference ring portion 33e holds the outer circumference of the large diameter portion 32e of the inner disk member 32 oil-tightly.

Reference numeral 31 denotes the outer disc member mounted on the outer periphery of the small-diameter portion 32d of the inner disc member 32. The outer periphery of the end of the small-diameter portion 31b and the joint 2 are provided.
A joint 23 is oil-tightly mounted between the first and second parts.

The oil hole 22 is provided between the outer disc member 31 and the joint 23 and the small diameter portion 32d of the inner disc member 32 and the joint 22.
An oil passage 23a communicating with a is formed.

Further, the outer disk member 31 has an oil hole 31a communicating with the oil passage 23a from the inner peripheral surface to the large diameter portion 31.
It is provided so as to penetrate toward the vertical end surface of c, and is fitted and inserted into the outer periphery of the small diameter portion 32d of the inner disk member 32 at the end (valve seat portion) of the oil hole 31a facing the large diameter portion 31c. Further, the expansion side soft valve 35 as the second expansion side valve is in contact.

The housing 33 is formed with oil holes 33a whose both ends open to the oil holes 32c of the expansion side soft valve 35 and the inner disk member 32,
Further, an oil hole 33b having both ends opened is formed on the side of the reservoir chamber 6 and the pressure side soft valve 36.

A spool valve 34 is axially slidable along the annular valve seat surface portion 32f of the inner disk member 32, and has an oil hole 34a penetrating inward and outward.

On the other hand, 37 is a cylindrical case that covers the opening formed in a part of the outer circumference of the outer shell 3 in an oil-tight manner, and the case 37 is orthogonal to the axial direction of the outer shell 3. In the direction of the inner peripheral surface of the inner disk member 32 and the outer periphery of the flange portion 32g of the inner disk member 32 and the housing 33.
It supports the outer circumference of.

Reference numeral 38 denotes a cover which is screwed into the opening end of the case 37 and closes the opening end.
A ring-shaped exciting coil 39 is arranged on the inner opening side so as to cover the spool valve 34. A normal oil-tight (seal) treatment is applied between the exciting coil 39 and the case 37 and the cover 38.

Reference numeral 40 denotes a spring interposed between the cover 38 and the spool valve 34. The spring 40
Has a preset magnitude of elastic force corresponding to an electrode attraction force of a coil 39, which will be described later, and normally urges the spool valve 34 in a direction in which the cylinder 2 is located.

The upper plate 7 has an oil hole 4 for collecting the working oil leaking between the upper plate 7 and the seal member 10 due to the expansion of the piston rod 1 into the reservoir chamber 6.
1 is provided. Reference numeral 42 is a spring that biases the seal member 10 so as to come into close contact with the outer circumference of the piston rod 1 via the spring receivers 43 and 44.

Then, in the spool valve 34, the coil 39 is energized and deenergized to move the oil hole 32a to the oil hole 32b or the oil hole 32c through the oil hole 34a.
One of the common switching valves is selectively connected to any of the above.

The spool valve 34 shown in FIG.
As shown in, there are two types of switching positions, a first position P1 and a second position P2. In FIG. 2, the same reference numerals are omitted for the parts corresponding to those in FIG.

Therefore, according to the above configuration, the piston lower chamber 5-the oil hole 2b of the cylinder 2-the oil hole 32a of the inner disk member 32-the oil hole 34a of the spool valve 34 are communicated.
The oil passage A as shown in FIG. 1 is formed.

Further, the piston upper chamber 4-the oil hole 2a of the cylinder 2-the inner tube 21-the oil hole 22a above the joint 22-the oil passage 23a-the oil hole 31a of the outer disc member 31-the extension side soft valve 35-the housing A first bypass oil passage B as shown in FIG. 1 is formed through the oil hole 33a of 33, the oil hole 32c of the inner disk member 32, and the oil passage 37a of the outer peripheral portion of the spool valve 34.

Further, the second chamber as shown in FIG. 1 passes through the reservoir chamber 6-the oil hole 33b of the housing 33-the pressure side soft valve 36-the oil hole 32b of the inner disk member 32-the other outer peripheral portion of the spool valve 34. The bypass oil passage C is formed.

Next, the operation will be described. First, in the extension stroke, the spool valve 3 as a switching valve is used.
4, the oil holes 34a of the inner disk member 3
When the second valve seat surface portion 32f is in the closed state, the spool valve 34 moves to the first position as shown in FIG.
Since it is in the position of
And the oil passage C does not communicate.

Therefore, the working oil does not flow to the expansion side soft valve 35, but the working oil of the piston upper chamber 4 flows to the piston lower chamber 5 via the expansion side hard valve 12 and a large flow resistance is generated here. The piston upper chamber 4 has a high pressure and a high damping force is generated (the damping force during the extension side stroke is hard).

On the other hand, when a small current of a predetermined value is passed through the coil 39, the spool valve 34 moves slightly to the right and the oil hole 34a is slightly oiled on the oil hole 32c side of the inner disk member 32. It opens to the path 37a.

Therefore, the working oil in the piston upper chamber 4 is composed of the oil hole 2a of the cylinder 2, the upper clearance 22c, the oil hole 22a, the oil passage 23a, the oil hole 31a, the extension side soft valve 35, and the oil hole 3.
3a-oil hole 32c-oil passage 37a-oil hole 34a-oil hole 32
a-lower gap 22d-the oil hole 2b of the cylinder 2 flows into the piston lower chamber 5.

At the same time, the expansion side hard valve 12 is slightly opened by the flow resistance, and the hydraulic oil flows from the piston upper chamber 4 to the piston lower chamber 5 through these, so that the flow resistance of the hydraulic oil as a whole is lowered, and the piston The pressure in the upper chamber 4 and the extension side damping force will be lower than in the case of the extension side damping force hard (the damping force during the extension side stroke is medium).

Next, when a larger current is applied to the coil 39, the spool valve 34 moves to the right greatly, that is, in FIG. 1, the spool valve 34 moves from the first position P1 to the second position P2. The oil hole 34a is thereby moved to the oil passage 37a on the oil hole 32c side.
Therefore, the flow resistance of the hydraulic oil in the oil passage 37a becomes so small that it becomes almost zero.

Therefore, the flow of the hydraulic oil through the expansion side soft valve 35 increases, and the oil passage B, which is the first bypass, is increased.
Flow resistance in the expansion side stroke becomes smaller than that of the above-mentioned medium, and the pressure in the piston upper chamber 4 and the expansion side damping force further decrease (the damping force during the expansion side stroke is soft).

On the other hand, in the pressure stroke, when the oil hole 34a of the spool valve 34 as the switching valve is blocked by the valve seat surface portion 32f of the inner disc member 32 as shown in FIG. Is in the first position as shown in FIG. 1, the oil passage C does not communicate with the oil chamber A.

Therefore, the hydraulic oil does not flow to the pressure side soft valve 36, and the hydraulic oil in the piston lower chamber 5 serves as the first pressure side valve of the base valve member 14 for the pressure side hard valve 1.
5 flows to the reservoir 6 through the flow path 5, a large flow resistance is generated there, the piston lower chamber 5 has a high pressure, and a high compression side damping force is generated (the damping force during the compression side stroke is hard).

On the other hand, by passing a small current of a predetermined value through the coil 39, the spool valve 34 moves slightly to the right and the oil hole 34a is slightly oiled on the oil hole 32c side of the inner disk member 32. It opens to the path 37a.

Therefore, the hydraulic oil in the piston lower chamber 5 flows into the reservoir chamber 6 via the pressure side hard valve 15 of the base valve member 14, and separately from this, the hydraulic oil in the piston lower chamber 5 becomes Oil hole 2b at the bottom of cylinder 2
Lower clearance 22d-Oil hole 32a-Left end side of spool valve 34-Oil hole 32b of inner disk member 32-Pressure side soft valve 36-Oil hole 33b of housing 33-Outer peripheral side of housing 33 It flows into the reservoir chamber 6.

Therefore, the flow resistance of the hydraulic oil as a whole is lowered, and the pressure in the piston lower chamber 5 and the pressure side damping force are
The damping force will be lower than in the case of hard (the damping force during the compression side stroke is medium).

Next, when a larger current is applied to the coil 39 during the pressure stroke, the spool valve 34 greatly moves rightward. As a result, the opening end of the oil hole 32b of the inner disk member 32 is largely opened to the oil hole 32a, the flow resistance of the hydraulic oil in the oil hole 32b is almost eliminated, and the flow of the hydraulic oil to the pressure side soft valve 36 is increased. To do.

Therefore, the flow resistance of the hydraulic oil in this path is further reduced, and the pressure in the piston lower chamber 5 and the compression side damping force are greatly reduced (the damping force during the compression side stroke is soft).

As described above, since the expansion side soft valve 35 and the compression side soft valve 36 are connected in parallel to the expansion side hard valve 12 and the compression side hard valve 15 via the spool valve 34, respectively, the piston 11 is operated when the compression side damping force is hard. It is possible to avoid increasing the load of the compression side damping force on the pressure side, which prevents the hydraulic oil from sneaking in from the piston lower chamber 5 to the piston upper chamber 4 during the pressure stroke, and to reduce the variable range of the pressure side damping force. The constraint can be removed.

Further, by arranging the expansion side soft valve 35 and the compression side soft valve 36 coaxially with the spool valve 34 as a switching valve, the soft valve portion can be made compact, and the piston 11 can be adjusted from the damping force adjusting mechanism. By adopting an independent structure, the structure of the piston 11 can be used as it is, and the damping force can be adjusted while allowing the piston rod to reciprocate with the same stroke as a normal hydraulic shock absorber without changing the piston valve length. The degree of freedom of the mounting location of the mechanism can be increased. further,
Since the oil passages B and C as bypasses are independently set in the extension stroke and the pressure stroke, and the extension side soft valve 35 and the compression side soft valve 36 are coaxially installed in the valve unit, the respective soft valves are extended side and pressure side. Can be adjusted separately,
Moreover, the variable range of the damping force on the extension side and the compression side can be set freely.

FIG. 3 is a sectional view showing another embodiment of the valve unit V according to the present invention. Here, unlike the structure shown in FIG. 2, the spool valve 34A has a structure in which the oil hole 32b of the inner disk member 32 is connected to the spool valve. 34A oil hole 34A
It is provided at a position overlapping with a.

That is, as shown in FIG. 4, the spool valve 34A has a first position P3 in which the oil passage C is opened and the oil passage B is closed, and a second position P4 in which the oil passage B is opened and the oil passage C is closed. And a third position P5 in which the oil passages B and C are opened at the same time.

In addition to this, by adjusting each position so that the opening area of one of the oil passages B and C is decreased when the opening area of the other is decreased, the semi-accumulation by an arbitrary damping force is performed. It is available as a damper for active control.

FIG. 5 is a sectional view showing another valve unit V according to the present invention. In FIG. 1, the position of the spool valve 34 is shown in the relationship between the electrode attraction force of the coil 39 and the elastic force of the spring 40. On the other hand, in this embodiment, the fluid pressure such as air pressure or hydraulic pressure that is press-fitted from the hub-shaped center hole 38a formed in the cover 38 is adjusted in this embodiment.
The position of the spool valve 34B is adjusted according to the movement of the operating plate 47 by contacting the side surface of the operating plate 47 that slides in an oil tight manner against the spring 46 on the inner circumference.

Therefore, when the fluid pressure to be press-fitted into the center hole 38a is, for example, air pressure, the pressure of the air suspension (hydropneumatic) is fed back to the center hole 38a, so that the spool valve can respond to the air pressure. By adjusting the sliding position of 34B,
Damping force adjustment can be performed, and as a result, mechanical damping force adjustment linked to the load and the like can be realized.

FIG. 6 is a sectional view showing a valve unit V according to still another embodiment of the present invention, in which a screw hole portion 48 is formed in the center of the cover 38, and the screw hole portion 48 has a screw shape. The spool valve 34C is screwed so that the axial movement amount can be adjusted.

In such a valve unit V, by manually rotating the spool valve 34C using a jig, the opening amount of the oil hole 34a with respect to the oil hole 32b and the oil passage 37a is adjusted to obtain the attenuation amount. Can be arbitrarily adjusted, and this can be realized with a simple and inexpensive structure.

The other operations in FIGS. 5 and 6 are the same as those described with reference to FIGS. 1 and 2, and a duplicate description thereof will be omitted here.

[0066]

As described above, according to the first aspect of the present invention, the piston rod is movably inserted into the cylinder via the piston, and the piston defines the upper piston chamber and the lower piston chamber in the cylinder. , The piston upper chamber and the piston lower chamber are opened and closed via a first expansion side valve provided on the piston, and the piston lower chamber is further opened via a first pressure side valve provided on a base valve member below the cylinder. In a hydraulic shock absorber that is opened and closed in a reservoir chamber outside the cylinder, a first bypass that bypasses the first extension side valve to connect the piston upper chamber and the piston lower chamber and a first pressure side valve is bypassed. A second bypass connecting the lower piston chamber and the reservoir chamber is provided, a second expansion valve is provided openably and closably during the first bypass, and a second bypass valve is provided during the second bypass.
Since the pressure side valve is provided so as to be openable and closable, and the opening area of the first bypass and the second bypass is adjusted steplessly by one common switching valve, the compression side damping force of the piston can be adjusted when it is hard. It is possible to suppress an increase in the load on the compression side damping force, which prevents the hydraulic oil from sneaking in from the lower chamber of the piston to the upper chamber of the piston, and limits the adjustment range of the compression side damping force. The effect of disappearing is obtained.

According to the invention of claim 2, the switching valve has the first bypass and the second bypass simultaneously closed.
With a second position that opens at the same time as
Since the opening areas of the first bypass and the second bypass are increased / decreased at the same time, the height of the extension side and the pressure side can be reduced.
The effect that two damping force adjustments can be performed simultaneously is obtained.

According to the third aspect of the present invention, in the switching valve, the second bypass is opened and the first bypass is closed.
Position, the first bypass is opened, the second bypass is closed, the second position is closed, the first bypass is closed, and the second bypass is closed.
With a bypass and a third position that opens at the same time,
When the opening area of one bypass increases, the opening area of the other bypass decreases so that the compression side damping force is soft when the extension side damping force is hard, and the compression side damping force is when the extension side damping force is soft. The damping force can be set such that the force is hardened, and the application as a damper for semiactive control can be achieved.

According to the invention of claim 4, the opening areas of the first bypass and the second bypass are set so that the expansion side damping force and the compression side damping force are switched to soft, medium and hard respectively. Since it is configured to be adjusted in stages, it is possible to obtain the effect that it is possible to freely select the optimal extension side damping force and compression side damping force having a magnitude corresponding to the operation amount of the switching valve.

Further, according to the invention of claim 5, since the switching valve is constituted by a solenoid switching valve which is controlled by current or voltage, the damping force can be accurately adjusted by a current command value calculated in advance from a remote location. The effect of stepless adjustment is obtained.

Further, according to the invention of claim 6, since the stroke of the switching valve is controlled by hydraulic pressure or pneumatic pressure, for example, the pressure of the air suspension is fed back and used, and the mechanical method is used. The effect that the damping force can be easily adjusted steplessly is obtained.

Further, according to the invention of claim 7, since the stroke of the switching valve is controlled by the screwing operation, the stepless adjustment of the damping force can be easily realized by the manual operation, which is extremely simple. An effect that it can be realized at a low cost with the configuration is obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing details of the hydraulic shock absorber shown in FIG.

FIG. 3 is a cross-sectional view of a main part showing another form of the valve unit in FIG.

FIG. 4 is a conceptual diagram showing a hydraulic shock absorber according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing another form of the valve unit in FIG.

FIG. 6 is a cross-sectional view showing another form of the valve unit in FIG.

[Explanation of symbols]

 1 Piston Rod 2 Cylinder 4 Piston Upper Chamber 5 Piston Lower Chamber 6 Reservoir Chamber 11 Piston 12 Extension Side Hard Valve (First Extension Side Valve) 14 Base Valve Member 15 Pressure Side Hard Valve (First Pressure Side Valve) 34 Spool Valve ( Switching valve) 35 Expansion side soft valve (second expansion side valve) 36 Pressure side soft valve (second pressure side valve) A oil passage B oil passage (first bypass) C oil passage (second bypass)

Claims (7)

[Claims] 1. A piston rod is movably inserted into a cylinder via a piston, the piston defines a piston upper chamber and a piston lower chamber in the cylinder, and these piston upper chamber and piston lower chamber are pistons. A hydraulic shock absorber that is opened and closed via a first expansion side valve provided in the cylinder, and the piston lower chamber is opened and closed to a reservoir chamber outside the cylinder via a first pressure side valve provided in a base valve member below the cylinder. In, a first bypass that bypasses the first extension side valve and connects the piston upper chamber and the piston lower chamber,
A second bypass, which bypasses the first pressure side valve and connects the piston lower chamber and the reservoir chamber, is provided, and a second expansion side valve is provided openably and closably during the first bypass, and the second bypass is provided. A hydraulic shock absorber, characterized in that a second pressure side valve is provided therein so as to be openable and closable, and the opening area of the first bypass and the second bypass is adjusted steplessly by a common switching valve. 2. The switching valve has a second position that opens simultaneously with a first position in which the first bypass and the second bypass simultaneously close, and the opening areas of the first bypass and the second bypass simultaneously increase and decrease. The hydraulic shock absorber according to claim 1, wherein the hydraulic shock absorber is provided. 3. The switching valve has a first position in which the second bypass is open and the first bypass is closed, and a second position in which the first bypass is open and the second bypass is closed, and the first bypass. The third position in which the first bypass and the second bypass are simultaneously opened is provided, and when the opening area of one bypass increases, the opening area of the other bypass decreases. Hydraulic shock absorber. 4. The opening areas of the first bypass and the second bypass have soft extension damping force and compression side damping force, respectively,
The hydraulic shock absorber according to claim 1, wherein the hydraulic shock absorber is adjusted in three steps so as to switch between medium and hard. 5. The hydraulic shock absorber according to claim 1, 2, 3 or 4, wherein the switching valve is a solenoid switching valve controlled by current or voltage. 6. The hydraulic shock absorber according to claim 1, 2, 3 or 4, wherein the stroke of the switching valve is controlled by hydraulic pressure or pneumatic pressure. 7. The stroke of the switching valve is controlled by a screwing operation, and the stroke is controlled.
Alternatively, the hydraulic shock absorber described in 4.