KR101937469B1 - Damping force controlling shock absorber - Google Patents

Abstract

A damping force variable shock absorber according to the present invention is a damping force variable shock absorber comprising a cylinder filled with a fluid, a piston rod compressing and tensioning the cylinder in the cylinder, and a cylinder connected to a lower end of the piston rod to divide the cylinder into a compression chamber and a tension chamber A solenoid coupled between the piston rod and the piston valve for opening and closing the operating chamber by raising and lowering the spool by a magnetic force, and a solenoid for opening and closing the operating chamber, wherein the solenoid is disposed between the operating chamber and the piston valve A back pressure chamber in which the main valve is divided and formed in a communicated state and in which a main valve is installed so as to be able to ascend and descend; a piston connected to an upper portion of the piston valve and the tension chamber, A main flow path for reciprocally moving the compression chamber and the fluid in the tension chamber through the main chamber, A first auxiliary flow path connecting the burrs to the compression chamber and opening only during a compression stroke of the piston rod to allow the fluid in the compression chamber to move to the tension chamber through the piston valve and the back pressure chamber, And a pair of second auxiliary flow paths connecting the first auxiliary flow path and the piston valve and being opened only during a tensile stroke of the piston rod to move the fluid introduced into the first auxiliary flow path to the compression chamber do.

Description

DAMPING FORCE CONTROLLING SHOCK ABSORBER

The present invention relates to a damping force variable shock absorber, and more particularly, to a damping force variable shock absorber capable of selectively applying a hard damping force and a soft damping force by selectively opening and closing auxiliary flow paths using check valves during compression and tensioning, To an absorber.

Generally, a shock absorber is mounted on a moving means such as an automobile, and absorbs and buffers vibrations and shocks received from the road surface during traveling, thereby improving ride comfort.

The shock absorber is constituted by a piston rod provided inside the cylinder so as to be capable of being compressed and tensioned, and a piston valve which is located inside the cylinder in a state of being coupled to the piston rod and generates a damping force.

On the other hand, when the damping force is set to a low value, the shock absorber absorbs the vibration caused by the unevenness of the road surface to improve the ride quality. On the other hand, when the damping force is set high, the attitude of the vehicle body is suppressed.

Therefore, a damping force variable shock absorber having different damping force characteristics according to the purpose of use of a vehicle is applied to a conventional vehicle.

In such a conventional damping force variable shock absorber, the spool of the solenoid closes the auxiliary flow path to generate a high damping force (Hard Mode), and conversely, the spool opens the auxiliary flow path to generate a low damping force (Soft Mode) Lt; / RTI >

However, in the conventional damping force variable shock absorber, when the solenoid fails, the spool is not moved to the set position, so that it is difficult to secure stability of damping force control.

A conventional damping force variable shock absorber forms a hard damping force at a low current (0.3 A) and a soft damping force at a fixed current (1.6 A) in order to realize a hard damping force when a fail safe occurs, Since the soft mode, which always operates in the vehicle, occurs at a high current, a lot of power consumption and high frequency are generated in the pulse width modulation (PWM) process of the solenoid.

A prior art related to the present invention is Korea Unexamined Patent Publication No. 1998-0002962 (Mar. 30, 1998), which discloses a damping force variable valve.

It is an object of the present invention to simultaneously control hardness damping force and soft damping force by controlling the pressure of the back pressure chamber by using a solenoid and selectively opening and closing the auxiliary flow paths by using check valves during compression and tension stroke, And to provide a damping force variable shock absorber capable of ensuring linearity of damping force.

It is a further object of the present invention to provide a safety device capable of securing safety even when the driving force of the solenoid is lost by returning the spool to the shutoff position by using the elastic member when a fail safe occurs and reducing power consumption and operation noise during solenoid control Which is a damping force variable shock absorber.

A damping force variable shock absorber according to the present invention is a damping force variable shock absorber comprising a cylinder filled with a fluid, a piston rod compressing and tensioning the cylinder in the cylinder, and a cylinder connected to a lower end of the piston rod to divide the cylinder into a compression chamber and a tension chamber A solenoid coupled between the piston rod and the piston valve for opening and closing the operating chamber by raising and lowering the spool by a magnetic force, and a solenoid for opening and closing the operating chamber, wherein the solenoid is disposed between the operating chamber and the piston valve A back pressure chamber in which the main valve is divided and formed in a communicated state and in which a main valve is installed so as to be able to ascend and descend; a piston connected to an upper portion of the piston valve and the tension chamber, A main flow path for reciprocally moving the compression chamber and the fluid in the tension chamber through the main chamber, A first auxiliary flow path connecting the burrs to the compression chamber and opening only during a compression stroke of the piston rod to allow the fluid in the compression chamber to move to the tension chamber through the piston valve and the back pressure chamber, And a pair of second auxiliary flow paths connecting the first auxiliary flow path and the piston valve and being opened only during a tensile stroke of the piston rod to move the fluid introduced into the first auxiliary flow path to the compression chamber .

The main valve is installed in the back pressure chamber so as to be able to move up and down. A valve body is formed in the back pressure chamber so that the first passage hole is vertically communicated with the upper portion of the piston valve and the back pressure chamber. And a first elastic member elastically supporting the valve body downward.

The valve body is preferably raised to the open position by the pressure of the fluid flowing into the main passage or the upper portion of the piston valve during the compression stroke and the tensile stroke of the piston rod.

The first auxiliary passage and the first passage hole are respectively provided with first check valves which are opened during a compression stroke of the piston rod and closed during a tension stroke of the piston rod, And a second check valve which is opened during a tensile stroke of the piston rod and which is closed during a compression stroke of the piston rod.

In addition, the first check valves and the second check valves may be switched to a closed state when the spool closes a connection portion between the operation chamber and the first auxiliary flow path so that the fluid is moved only through the main flow path desirable.

In addition, a guide groove is formed in the outer thickness of the back pressure chamber so as to be connected to the main flow passage, and an insertion end is protruded from the upper side of the valve body so as to be able to slide up and down in the guide groove.

In addition, the first auxiliary flow path is horizontally connected to the upper portion of the operation chamber, and an opening / closing projection for opening / closing the connection portion between the operation chamber and the first auxiliary flow path is protruded laterally from the lower end of the spool .

Preferably, the side surface of the opening / closing protrusion is formed with an inclined surface whose diameter gradually decreases toward the bottom.

In addition, the inner circumferential surface of the operating chamber is vertically spaced apart from the upper and lower jaws so that the opening / closing protrusions are located between the upper jaw and the lower jaw, And close the upper end of the lower stopping jaw to close the operation chamber when moving downward.

It is preferable that the opening / closing projection is brought into close contact with the lower end of the upper stopping jaw by the rise of the solenoid due to the elastic force when the driving force is lost, thereby closing the operating chamber and the first auxiliary flow path.

In addition, a second elastic member for elastically supporting the lower end of the spool upwardly and acting on the returning elastic force of the spool, and a second elastic member disposed in the second elastic member so as to overlap with a smaller diameter, And a third elastic member for limiting the lowering position of the spool by operating the second elastic member.

Further, a plug is further provided at a lower portion of the operation chamber, the upper end supporting the upper end of the first elastic member and the lower end supporting the second elastic member and the third elastic member, And a second passage hole communicating with the operation chamber.

The present invention can control the pressure of the back pressure chamber by using a solenoid and selectively open and close the auxiliary flow paths by using check valves during compression and tension strokes to simultaneously realize hard damping force and soft damping force, Can be secured.

Further, by returning the spool to the cutoff position by using the elastic member when a fail safe occurs, safety can be ensured even when the driving force of the solenoid is lost, and power consumption and operation noise can be reduced when the solenoid is controlled.

1 is a front sectional view for showing a damping force variable shock absorber according to the present invention.
FIG. 2 is an enlarged view of a part of FIG. 1 showing part A in detail.
3 is a front sectional view showing a compression stroke state of a damping force variable shock absorber according to the present invention.
4 is a front sectional view showing a tension stroke state of a damping force variable shock absorber according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

FIG. 1 is a front sectional view for showing a damping force variable shock absorber according to the present invention, and FIG. 2 is an enlarged view showing a part of FIG. 1 in detail.

1 and 2, a damping force variable shock absorber according to the present invention includes a cylinder 10, a piston rod 20, a solenoid 30, And a piston valve (40).

In particular, the damping force variable shock absorber according to the present invention includes a back pressure chamber 100, a main valve 200, a main passage 300, a first auxiliary passage 400, a second auxiliary passage 500-1 , 500-2).

In the above-described configurations, the cylinder 10 may have a cylindrical shape that forms a space therein, and the operating fluid (oil or the like) is filled in the cylinder 10.

The interior of the cylinder 10 may be divided into a compression chamber 10a and a tension chamber 10b by a piston valve 20 to be described later.

One end of the cylinder 10 and one end of the piston rod 20, which will be described later, can perform compression and tensile strokes while being connected to the vehicle body side or the wheel side, respectively.

The lower end of the cylinder 10 may be provided with a separate coupling portion (not shown) for connection to the vehicle body side or the wheel side.

Alternatively, the damping force variable shock absorber according to the present invention may be applied to the abdominal shock absorber structure.

In this case, the cylinder 10 may have an inner tube (not shown) forming a space therein, and an outer tube (not shown) may be provided outside the inner tube. The inner tube may be a piston valve And can be divided into a compression chamber 10a and a tension chamber 10b.

A body valve (not shown) may be provided to separate the storage chamber between the inner tube and the outer tube from the compression chamber 10a.

The solenoid 30 is coupled between the piston rod 20 and the piston valve 40 and moves the spool 31 up and down by the magnetic force of the coil 33 to open and close the operating chamber 32.

More specifically, the solenoid 30 may open / close the operating chamber 32 by an external power source to reduce the magnitude of the main damping force.

An opening / closing projection 31a for opening / closing a connection portion between the operation chamber 32 and a first auxiliary flow path 400, which will be described later, is formed laterally protruding from the lower end of the spool 31.

The opening / closing protrusion 31a is horizontally formed on an upper surface of the opening / closing protrusion 31a, and a slope may be formed on the side surface of the opening / closing protrusion 31a so that the diameter gradually decreases toward the bottom.

The inclined surface 31b can guide the fluid introduced from the lower portion of the lower stopping jaw 32b to be smoothly moved upward.

The operation chamber 32 is formed in a lower space of the solenoid 30 and the lower end of the spool 31 is positioned in the operation chamber 32 so as to be able to move up and down.

The upper stopping protrusion 32a and the lower stopping protrusion 32b are vertically spaced apart from each other so that the opening and closing protrusion 31a of the spool 31 is positioned on the inner circumferential surface of the operation chamber 32. [

A moving region is formed between the upper stopping protrusion 32a and the lower stopping stop 32b so that the opening and closing protrusion 31a can move up and down.

That is, the open / close protrusion 31a can be selectively switched between the soft mode and the hard mode while moving upward or downward in the movement area.

When the opening / closing projection 31a is spaced apart from the upper stopping protrusion 32a and the lower stopping stopper 32b, the opening area of the operation chamber 32 can be increased to form soft damping force.

The upper and lower surfaces of the opening and closing projection 31a are spaced apart from the upper stopping protrusion 32a and the lower stopping stopper 32b so that the first and second auxiliary flow paths 400, Fluid can move.

On the contrary, when the opening / closing projection 31a is positioned close to the upper end of the lower stopping protrusion 32b when moving downward, the operating chamber 32 and the first auxiliary channel 400 to be described later are blocked to form a hard damping force .

The opening / closing protrusion 31a can be moved upward by the compressive force of the second elastic member S2, which will be described later, when the driving force of the solenoid 30 is lost due to a fail-safe accident or the like.

At this time, the opening / closing projection 31a can close the connection between the operation chamber 32 and the first auxiliary flow path 400, which will be described later, in a state in which the opening / closing projection 31a is in close contact with the lower end of the upper stopping step 32a.

In particular, a second elastic member S2 and a third elastic member S3 for applying a compressive force in the up-and-down direction may be installed in the operation chamber 32.

The second resilient member (S2) resiliently supports the lower end of the spool (31) upward to exert a returning elastic force of the spool (31).

The third elastic member (S3) is arranged inside the second elastic member (S2) with a smaller diameter, and acts to apply a compressive force to restrict the lowering position of the spool (31).

It is preferable that the second elastic member S2 and the third elastic member S3 use a coil spring for applying a compressive force in the vertical direction.

The lower end of the operation chamber 32 supports the upper end of the first elastic member S1 and the lower end of the plug supports the second elastic member S2 and the third elastic member S3, 800 may be further installed.

The plug 800 may be formed with a second through hole 810 through which the back pressure chamber 100 and the operation chamber 32 communicate with each other.

The back pressure chamber 100 is divided and formed between the operating chamber 32 and the piston valve 40 so that a main valve 200 for generating a damping force can be raised and lowered inside the back pressure chamber 100 Respectively.

The main valve 200 may include a valve body 210 and a first elastic member S1.

The valve body 210 is installed so as to be able to move up and down within the back pressure chamber 100. The valve body 210 has a first through hole 212 formed to pass through the upper portion of the piston valve 40 and the back pressure chamber 100, do.

The valve body 210 is lifted to the open position by the pressure of the fluid flowing into the upper portion of the main passage 300 or the piston valve 40 to be described later when the piston rod 20 is compressed and tensioned.

To this end, a guide groove 110 may be formed in the outer thickness of the back pressure chamber 100 to be connected to the main flow path 300.

An insertion end 211 inserted into the guide groove 110 may be protruded from the upper side of the valve body 210.

The insertion end 211 slides and moves along the guide groove 110 by the pressure of the fluid acting on the lower portion of the valve body 210.

The first elastic member (S1) is provided in the back pressure chamber (100) and elastically supports the valve body (210) downward.

Here, the first elastic member S1 may be a coil spring for applying a compressive force to the first and second elastic members S1 and S2.

The first passage hole 212 is provided with a first check valve 600-1 which is opened during the compression stroke of the piston rod 20 and is closed during the tension stroke of the piston rod 20.

The first check valve 600-1 opens the first passage hole 212 during a compression stroke of the piston rod 20 in a state in which the solenoid 30 operates in the soft mode.

As described above, the first check valves 600-1 and 600-2 and the second check valves 700-1 and 700-2 are arranged such that the spool 31 is connected to the operation chamber 32 and the first auxiliary channel When the connection portion of the main flow path 400 is closed, the fluid is moved only through the main flow path 300 by switching to the closed state.

The main passage 300 connects the upper portion of the piston valve 40 and the tension chamber 10b and is connected to the compression chamber 10a and the compression chamber 10a through the lifting and lowering of the main valve when the piston rod 20 is compressed and tensioned. Thereby moving the fluids in the tension chamber 10b.

The first auxiliary flow path 400 connects the working chamber 32 and the tension chamber 10b and is opened only during the compression stroke of the piston rod 20 so that the fluid in the compression chamber 10a flows through the piston valve 40, And the back pressure chamber 1000 to the tension chamber 10b.

The first check valve 600-1 and the second check valve 600-2, which are opened when the piston rod 20 is in the compression stroke and closed when the piston rod 20 is pulled, Respectively.

3, the first check valves 600-1 and 600-2 are opened during the compression stroke of the piston rod 20 to form soft damping force as described above.

The second auxiliary flow paths 500-1 and 500-2 connect the back pressure chamber, the tension chamber 10b, the first auxiliary flow path 400, and the piston valve 40 to each other.

That is, the second auxiliary flow paths 500-1 and 500-2 are opened only during the tension stroke of the piston rod 20 so that the fluid flowing into the first auxiliary flow path 400 is moved to the compression chamber 10a .

The second auxiliary flow paths 500-1 and 500-2 are provided with second check valves 700-1 and 700-2 which are opened during a tensile stroke of the piston rod 20 and are closed during a compression stroke of the piston rod 20, , And 700-2, respectively.

The second check valves 700-1 and 700-2 are opened during a tensile stroke of the piston rod 20 as shown in FIG. 4 to form a soft damping force.

The first check valves 600-1 and 600-2 and the second check valves 700-1 and 700-2 are closed when the spool 31 blocks the operation chamber 32 So that the fluid can be moved only through the main flow path 300 to form a hard damping force.

Hereinafter, the operation of the damping force variable shock absorber according to the present invention will be described with reference to FIGS. 3 to 4. FIG.

First, when the solenoid 30 is operated in the soft mode, the opening / closing projections 31a of the spool 31 are spaced apart from the upper stopping jaw 32a and the lower stopping jaw 32b.

3, the fluid in the compression chamber 10a moves to the tension chamber 10b through the compression passage of the piston valve 40 and the main passage 300, as shown in Fig. 3, during the compression stroke of the piston rod 20. [

At this time, the compression fluid of the piston valve 40 and the fluid moving to the tension chamber 10b through the main fluid channel 300 push up the valve body 210 upward, ).

At the same time, the fluid in the compression chamber 10a moves to the back pressure chamber 100 through the compression passage of the piston valve 40 and the first passage hole 212 by opening the first check valve 600-1 .

The fluid in the back pressure chamber 100 moves to the first auxiliary flow path 400 through the second passage hole 810 and the operation chamber 32 by opening the first check valve 600-1.

Finally, the fluid flowing into the first auxiliary flow path 400 moves to the tension chamber 10b by opening the first check valve 600-2.

That is, the cross-sectional area of the flow path can be increased through the movement of the auxiliary fluid through the opening of the first auxiliary flow path 400, thereby forming soft damping force.

On the other hand, when the piston rod 20 is tensioned, as shown in Fig. 4, the fluid in the tension chamber 10b is discharged to the compression flow path of the main flow channel 300 and the piston valve 40 by opening the second check valve 700-1. To the tension chamber 10b.

At this time, the fluid moving to the compression chamber 10a through the compression oil path of the main oil path 300 and the piston valve 40 pushes the valve body 210 upward, As shown in Fig.

At the same time, the fluid in the tension chamber 10b is operated through the second auxiliary passage 500-1, the back pressure chamber 100 and the second passage hole 810 by opening the second check valve 700-1 And moves to the chamber 32.

Further, the fluid in the working chamber 32 moves to the second auxiliary flow path 500-2 by opening the second check valve 700-2.

Finally, the fluid flowing into the first auxiliary flow path 400 moves to the compression chamber 10a by opening the second check valve 700-2.

That is, through the opening of the second auxiliary flow paths 500-1 and 500-2, the sectional area of the flow path can be increased through the movement of the auxiliary fluid, thereby forming soft damping force.

As a result, the present invention adjusts the pressure of the back pressure chamber 100 by using the solenoid 30, and selectively opens and closes the auxiliary flow paths by using the check valves during the compression and tension strokes, thereby achieving hard damping force and soft damping force Can be implemented simultaneously, and linearity of damping force per current can be ensured.

Further, by returning the spool 31 to the shutoff position by using the elastic member when the fail safe occurs, safety can be ensured even in the case of loss of the driving force of the solenoid 30, and power consumption and operation noise during the solenoid control can be reduced have.

Although the embodiments of the damping force variable shock absorber according to the present invention have been described above, it is apparent that various modifications can be made without departing from the scope of the present invention.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

It is to be understood that the foregoing embodiments are illustrative and not restrictive in all respects and that the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

10: cylinder 10a: compression chamber
10b: Tension chamber 20: Piston rod
30: Solenoid 31: Spool
31a: opening / closing projection 32: working chamber
32a: upper stopping jaw 32b: lower stopping jaw
33: coil 40: piston valve
100: back pressure chamber 110: guide groove
200: main valve 210: valve body
211: insertion end 212: first through hole
300: Main flow path 400: First auxiliary flow path
500-1, 500-2: second auxiliary flow path 600-1, 600-2: first check valve
700-1, 700-2: second check valve 800: plug
810: second through hole S1: first elastic member
S2: second elastic member S3: third elastic member

Claims (12)

A damping force variable shock absorber comprising a cylinder filled with a fluid, a piston rod for compressing and tensioning the cylinder in the cylinder, and a piston valve coupled to a lower end of the piston rod to divide the cylinder into a compression chamber and a tension chamber. In this case,
A solenoid coupled between the piston rod and the piston valve for opening and closing the working chamber by moving the spool up and down by a magnetic force;
A back pressure chamber divided and formed in a communicative state between the operating chamber and the piston valve and having a main valve movably installed therein;
A main flow passage connecting the upper portion of the piston valve to the tension chamber and moving the compression chamber and the tension chamber fluid through the lifting and lowering of the main valve during compression and tensioning of the piston rod;
A first auxiliary flow path connecting the working chamber and the tension chamber and opened only during a compression stroke of the piston rod so that fluid in the compression chamber is moved to the tension chamber through the piston valve and the back pressure chamber; And
And a pair of pairs of the first and second auxiliary flow paths, which are connected to the back pressure chamber, the tension chamber, the first auxiliary flow path, and the piston valve, and which are opened only during a tensile stroke of the piston rod, And a second auxiliary flow path
Wherein the main valve includes:
A valve body that is installed in the back pressure chamber so as to be able to move up and down and has a first passage hole formed in an upper portion and a lower portion so as to communicate with an upper portion of the piston valve and the back pressure chamber,
And a first elastic member provided in the back pressure chamber and elastically supporting the valve body downward,
Within the outer thickness of the back pressure chamber,
A guide groove connected to the main flow path is further formed,
On the upper edge side of the valve body,
And an insertion end is protruded to be able to slide up and down in the guide groove. delete The method according to claim 1,
Wherein the valve body comprises:
Wherein the piston is raised to an open position by a pressure of a fluid flowing into the main passage or the piston valve when the piston rod is compressed and tensioned. The method according to claim 1,
In the first auxiliary passage and the first passage hole,
A first check valve that is opened during a compression stroke of the piston rod and is closed during a tensile stroke of the piston rod,
In the second auxiliary flow paths,
And a second check valve that is opened when the piston rod is subjected to a tensile stroke and is closed when the piston rod is compressed. The method of claim 4,
Wherein the first check valves and the second check valves,
Wherein when the spool closes a connection portion between the operating chamber and the first auxiliary passage, the spool is switched to a closed state so that the fluid is moved only through the main passage. delete The method according to claim 1,
In the upper portion of the operating chamber,
The first auxiliary flow path is horizontally connected,
At the lower end of the spool,
And an opening / closing projection for opening / closing a connecting portion between the operating chamber and the first auxiliary flow path through the lifting and lowering is formed to protrude laterally. A damping force variable shock absorber comprising a cylinder filled with a fluid, a piston rod for compressing and tensioning the cylinder in the cylinder, and a piston valve coupled to a lower end of the piston rod to divide the cylinder into a compression chamber and a tension chamber. In this case,
A solenoid coupled between the piston rod and the piston valve for opening and closing the working chamber by moving the spool up and down by a magnetic force;
A back pressure chamber divided and formed in a communicative state between the operating chamber and the piston valve and having a main valve movably installed therein;
A main flow passage connecting the upper portion of the piston valve to the tension chamber and moving the compression chamber and the tension chamber fluid through the lifting and lowering of the main valve during compression and tensioning of the piston rod;
A first auxiliary flow path connecting the working chamber and the tension chamber and opened only during a compression stroke of the piston rod so that fluid in the compression chamber is moved to the tension chamber through the piston valve and the back pressure chamber; And
And a pair of pairs of the first and second auxiliary flow paths, which are connected to the back pressure chamber, the tension chamber, the first auxiliary flow path, and the piston valve, and which are opened only during a tensile stroke of the piston rod, And a second auxiliary flow path
The first auxiliary flow path is horizontally connected to an upper portion of the operation chamber,
Closing projections for opening and closing the connecting portion between the operating chamber and the first auxiliary flow path through the lifting and lowering are protruded laterally from the lower end of the spool,
On the side surface of the opening / closing projection,
Wherein the inclined surface has a gradually decreasing diameter as it goes downward. A damping force variable shock absorber comprising a cylinder filled with a fluid, a piston rod for compressing and tensioning the cylinder in the cylinder, and a piston valve coupled to a lower end of the piston rod to divide the cylinder into a compression chamber and a tension chamber. In this case,
A solenoid coupled between the piston rod and the piston valve for opening and closing the working chamber by moving the spool up and down by a magnetic force;
A back pressure chamber divided and formed in a communicative state between the operating chamber and the piston valve and having a main valve movably installed therein;
A main flow passage connecting the upper portion of the piston valve to the tension chamber and moving the compression chamber and the tension chamber fluid through the lifting and lowering of the main valve during compression and tensioning of the piston rod;
A first auxiliary flow path connecting the working chamber and the tension chamber and opened only during a compression stroke of the piston rod so that fluid in the compression chamber is moved to the tension chamber through the piston valve and the back pressure chamber; And
And a pair of pairs of the first and second auxiliary flow paths, which are connected to the back pressure chamber, the tension chamber, the first auxiliary flow path, and the piston valve, and which are opened only during a tensile stroke of the piston rod, And a second auxiliary flow path
The first auxiliary flow path is horizontally connected to an upper portion of the operation chamber,
Closing projections for opening and closing the connecting portion between the operating chamber and the first auxiliary flow path through the lifting and lowering are protruded laterally from the lower end of the spool,
On the inner peripheral surface of the operating chamber,
The upper and lower engaging jaws are vertically spaced such that the opening and closing protrusions are located between the upper and lower engaging jaws,
Wherein the opening /
Wherein the operation chamber is opened when the upper latching jaw and the lower latching jaw are spaced apart from each other, and is brought into close contact with the upper end of the lower latching jaw when the lower portion is moved downward to close the operation chamber. The method of claim 7,
Wherein the opening /
And the second solenoid valve is brought into close contact with the lower end of the upper engaging jaw by the rise of the solenoid due to the elastic force when the driving force is lost, thereby closing the operating chamber and the first auxiliary passage. The method according to claim 1,
Inside the working chamber,
A second elastic member elastically supporting the lower end of the spool upward to exert a returning elastic force of the spool,
Further comprising a third resilient member disposed inside the second resilient member with a smaller diameter and restricting a lowering position of the spool by applying a compressive force to the resilient member. A damping force variable shock absorber comprising a cylinder filled with a fluid, a piston rod for compressing and tensioning the cylinder in the cylinder, and a piston valve coupled to a lower end of the piston rod to divide the cylinder into a compression chamber and a tension chamber. In this case,
A solenoid coupled between the piston rod and the piston valve for opening and closing the working chamber by moving the spool up and down by a magnetic force;
A back pressure chamber divided and formed in a communicative state between the operating chamber and the piston valve and having a main valve movably installed therein;
A main flow passage connecting the upper portion of the piston valve to the tension chamber and moving the compression chamber and the tension chamber fluid through the lifting and lowering of the main valve during compression and tensioning of the piston rod;
A first auxiliary flow path connecting the working chamber and the tension chamber and opened only during a compression stroke of the piston rod so that fluid in the compression chamber is moved to the tension chamber through the piston valve and the back pressure chamber; And
And a pair of pairs of the first and second auxiliary flow paths, which are connected to the back pressure chamber, the tension chamber, the first auxiliary flow path, and the piston valve, and which are opened only during a tensile stroke of the piston rod, And a second auxiliary flow path
Inside the working chamber,
A second elastic member elastically supporting the lower end of the spool upward to exert a returning elastic force of the spool,
Further comprising a third resilient member disposed inside the second resilient member with a smaller diameter and restricting a lowering position of the spool by applying a compressive force,
In the lower portion of the operating chamber,
And a plug having an upper end supporting the upper end of the first elastic member and a lower end supporting the second elastic member and the third elastic member,
In the plug,
And a second passage hole communicating with the back pressure chamber and the operation chamber is formed so as to pass through the upper and lower portions of the shock absorber.

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