JP2002161939A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a damping force regulating device for shock absorbers. SOLUTION: A needle valve 500 is provided with a needle section 501 at the lower end. The needle section 501 tapers downward and inward for putting into a needle inserting passage 304 in order to increase/decrease the sectional area of the needle inserting passage 304 of a needle holder 300. A support section 503 which is formed above the needle section 501 makes a space with the internal surface of an enlarged passage 306 above the needle holder 300, and has a male screw 504 which is engaged with a female screw 312 of the needle holder 300. The needle valve 500 is sealed against the internal passage of a piston rod 102 above a through hole 102A in the needle holder 300 and piston rod 102, and rotated from external of the piston rod 102 so that the position of the needle valve 500 relative to the needle holder 300 is changed. In such a manner, an operating mechanism for the needle valve is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a vehicle shock absorber having wheels, and more particularly to a damping force adjusting mechanism for an automobile shock absorber.

[0002]

2. Description of the Related Art As a component of a vehicle suspension, a shock absorber for attenuating vibration of a vehicle has been conventionally known. FIG. 1 shows an oil-filled type shock absorber as a typical example of such a conventional shock absorber.

Referring to FIG. 1, a shock absorber is indicated generally by the reference numeral 1. The shock absorber 1 has a piston rod 2 and a tube or cylinder 3 slidably attached to the piston rod 2.

A lower spring bracket or seat 4 is attached to the cylinder 3 and the piston rod 2
Upper spring bracket or seat 5 on top of
A coil spring 6 is arranged between the spring seats 4 and 5 so as to surround the piston rod 2. The upper end of the piston rod 2 is attached to the frame or body 9 via the rubber bush 7 and the upper attaching member 8, while the lower end of the cylinder 3 is attached to a suspension arm (not shown).
It is attached via a suitable connecting means, for example, a ring member (not shown) having a rubber bush inside, a ball joint (not shown), or the like.

[0005] A piston 10 that slides along the inner wall of the cylinder 3 is attached to a lower portion of the piston rod 2. With this piston 10, the cylinder 3 is divided into a first chamber, that is, an upper chamber 11, and a second chamber, that is, a lower chamber 12, and oil is injected into each of the chambers 11 and 12. The piston 10 has a plurality of holes for communicating the upper chamber 11 and the lower chamber 12, that is, a first orifice 20.

When the upward force is applied to the tire due to the convexity of the road surface or the like, the first orifice 20 moves the cylinder 3 upward with respect to the piston 10 of the piston rod 2 via the suspension arm ( When the cylinder contracts), a downward force is applied to the tire due to a contraction-side orifice 20A that allows the oil in the lower chamber 12 to flow into the upper chamber 11 and a depression in the road surface, so that the cylinder 3 When moved down against
And an expansion orifice 20B that allows the oil in the upper chamber 11 to flow into the lower chamber 12 (when the cylinder is extended). In this example shown in FIG. 1, the one-way valve 20C for preventing the oil in the upper chamber 11 from flowing into the lower chamber 12 through the contraction-side orifice is provided in the contraction-side orifice. The oil in the lower chamber 12 is supplied to the orifice through the extending orifice.
There is provided a one-way valve 20D for preventing the gas from flowing into the valve 1.

Thus, when the tire moves up and down, the shock absorber 1 moves up and down and / or down due to the resistance when the oil passes through the first orifice 20 and / or the resistance when the one-way valve is opened. Alternatively, it provides a first damping force for the expansion and contraction movement of the coil spring 6.

[0008] As described above, the shock absorber 1
Is primarily determined or set by the diameter of the first orifice 20 formed in the piston 10 (and the opening resistance when a one-way valve is provided).

However, the first orifice 20 or the like preliminarily adjusts according to driving conditions or a user's preference.
There has been a demand to (substantially) change or adjust such a (roughly) set initial damping force.

Therefore, some conventional shock absorbers have a damping force adjusting device that can manually adjust the damping force of the shock absorber, as shown in FIGS.

In this damping force adjusting device, the piston rod 2 is formed to be hollow, and a hollow needle holder 31 is inserted into the lower end of the hollow piston rod 2. It is attached to the lower end of the rod 2.

2, the internal passage of the hollow needle holder 31 includes an upper reduced diameter portion 31A, an enlarged diameter portion 31B located below the reduced diameter portion 31A, and an increased diameter reduced portion 31A. And a tapered portion 31C extending between the tapered portion 31B and the diameter portion 31B. The hollow needle holder 31 is provided with a pin 32 that penetrates the enlarged diameter portion 31B in the diameter direction,
Above the pin 32, a ball having a larger diameter than the upper reduced diameter portion 31A, that is, a check valve 33, is disposed in the enlarged diameter portion 31B.

Above the needle holder 31, a needle valve 40 is slidably disposed in the internal passage of the hollow piston rod 2. The needle valve 40 includes a needle portion 41A tapered downward and inward at a lower portion thereof, and an upper end of the needle portion 41A is provided on an abutting shoulder portion 41B having a larger diameter than the upper reduced diameter portion 31A of the needle holder 31. linked. Needle part 41A is needle holder 3
1, the needle valve 40 is moved in the hollow piston rod 2 toward the upper reduced diameter portion 31A of the needle holder 31, and the needle portion 41A is moved to the upper reduced diameter portion 31A of the needle holder 31. As the inner diameter of the hollow piston rod 2 decreases, the cross-sectional area of the upper reduced diameter portion 31A of the needle holder 31 with respect to the internal passage of the hollow piston rod 2 is reduced. Becomes zero when the needle valve 40 is moved downward until the needle valve abuts on the upper end surface of the needle holder 31. An O-ring 42 is provided on the upper part of the needle valve 40 and forms a seal against the internal passage of the hollow piston rod 2.

Above the needle valve 40, an intermediate rod 5
0 is movably arranged in the internal passage of the hollow piston rod 2. Further, an adjusting member 60 is disposed above the intermediate rod 50. The lower end of the adjusting member 60 is screw-engaged with the upper end of the piston rod 2 so that it can be displaced vertically with respect to the piston rod 2. To facilitate the displacement of the adjustment member 60, the upper end is machined to facilitate rotation of the adjustment member 60, for example, machined into a hexagonal shape to accept a hexagon wrench.

Therefore, the adjusting member 6 is fixed by a hexagon wrench or the like.
When, for example, 0 is displaced downward with respect to the piston rod 2, the adjusting member 60 displaces the needle valve 40 downward in the internal passage of the piston rod 2 via the intermediate rod 50. Thus, the downward movement of the needle valve 40 reduces the cross-sectional area of the upper reduced diameter portion 31A of the needle holder 31 according to the amount of downward movement of the needle valve 40, as described above.

Further, at a position above the upper end surface of the needle holder 31 and not blocked by the needle valve 40 located at the lowermost point, the upper chamber 11 and the piston rod 2 A hole for communicating with the internal passage, that is, the second orifice 70 is formed.

Thus, when the needle valve 40 is adjusted so as to reduce the cross-sectional area of the flow path of the upper reduced diameter portion 31A, when the cylinder 3 is extended, the oil in the upper chamber 11 flows from the first orifice 20B to the lower chamber 12 In addition to the inflow, the second orifice 70, the adjusted gap between the needle portion 41A of the needle valve 40 and the upper reduced diameter portion 31A of the needle holder 31, the enlarged diameter portion 3 of the needle holder 31
1B, the damping force of the shock absorber 1 when the cylinder 3 is extended is
It can be changed or adjusted as compared with the case where only the first orifice 20 is used.

When the cylinder 3 contracts, the oil in the lower chamber 12 flows into the upper chamber 11 from the first orifice 20A, but the oil entering from the enlarged diameter portion 31B of the needle holder 31 is blocked by the check valve 33 and Since it does not flow into the chamber 11, the damping force of the shock absorber 1 when the cylinder 3 contracts does not change. However, the check valve 33 and the upper reduced diameter portion 3 of the needle holder 31
1A, a biasing means for biasing the check valve 33 downward (in a direction to open the upper reduced diameter portion 31A) with a constant force, for example, when a coil spring is installed, the biasing means is set. According to the urging force, the damping force of the shock absorber 1 when the cylinder 3 contracts can also be adjusted.

[0019]

However, in the shock absorber provided with the damping force adjusting device having the above structure, the needle valve 40 is set at a desired position with respect to the needle holder 31 in order to adjust the damping force manually. However, the needle valve 40 cannot maintain a desired position with respect to the needle holder 31 due to the viscosity of oil moving between the upper chamber 11 and the lower chamber 12, and as a result, a conventional damping force adjusting device is provided. However, there is a problem in that the shock absorber cannot provide a desired damping force stably or continuously.

That is, the oil flowing or moving from the upper chamber 11 to the lower chamber 12 through the second orifice 70 when the cylinder 3 is extended, the viscosity of the oil acts on the needle valve 40 and the needle valve 40 is set in advance. It is displaced downward from the desired position or toward the needle holder 31. The needle valve 40 displaced downward is moved upward again to a desired position by the flow of oil from the lower chamber 12 to the upper chamber 11 that occurs when the cylinder contracts, and as a result, the needle valve 40 moves Up-and-down movement is repeated according to expansion and contraction. Thus,
The damping force of the shock absorber is
Depending on the position of the needle valve 40 with respect to 1, the needle valve 40 becomes stronger or weaker, and the initially set desired damping force cannot be supplied stably.

Accordingly, the present invention provides a damper for a shock absorber for preventing displacement of a position of a needle valve with respect to a needle holder by a fluid moving between chambers of a cylinder separated by a piston attached to a piston rod. It is an object to provide a force adjustment device.

[0022]

According to the present invention, there is provided a damping force adjusting device for a shock absorber having an upper portion connected to a vehicle body, a piston rod slidably attached to the piston rod, and a lower portion connected to wheels. Having a cylinder and a piston attached to the piston rod, which divides the cylinder into an upper chamber and a lower chamber, and injects into each of the chambers when the cylinder is moved relative to the piston rod. A damping force adjusting device for a shock absorber, wherein the fluid moves between the two chambers through a first orifice formed in the piston to provide damping force. A rod having an internal passage extending through the rod in a longitudinal direction thereof, and a communication hole communicating the internal passage with the upper chamber of the cylinder; A needle holder having an internal passage extending therethrough, the needle holder being at least partially disposed in the internal passage of the piston rod, the outer surface of the needle holder being substantially relative to the internal passage of the piston rod. Attached to the piston rod, the internal passage of the needle holder, a needle insertion passage communicated with the lower chamber of the cylinder,
An upwardly extending passage formed above the needle insertion path and having a larger cross-sectional area than the needle insertion path; a side wall of the needle holder above the needle insertion path and the seal; A second orifice penetrating the needle holder; and a female screw formed on the inner surface of the upper enlarged passage above the second orifice. A needle valve provided at a lower end thereof with a downwardly tapered inwardly needle portion adapted to be inserted into the needle insertion path, and the needle valve has a support portion formed above the needle portion. And
The support portion forms a space between the needle holder and the inner surface of the upwardly enlarged passage, has a male screw threadedly engaged with the female screw of the needle holder, and the needle valve has the needle holder and Above the communication hole of the piston rod, sealed against the internal passage of the piston rod, to change the position of the needle valve with respect to the needle holder, to rotate the needle valve from outside the piston rod The needle valve has the needle valve operating mechanism described above.

According to the shock absorber damping force adjusting device having the above structure, when it is desired to adjust the damping force of the shock absorber, the needle valve is operated from outside the piston rod by operating the needle valve operating mechanism. Then, the position of the needle valve with respect to the needle holder is changed in a state where the male screw is screwed with the female screw of the needle holder. This position change causes the tapered needle portion of the needle valve to increase or decrease the flow path cross-sectional area of the needle insertion path of the needle holder.

When the cylinder is moved relative to the piston rod in this state, the fluid injected into the upper chamber and the lower chamber not only has a first orifice of the piston but also a cross-sectional area of the needle insertion passage. In accordance with the amount, it moves between the upper chamber and the lower chamber through the second orifice of the needle holder and the communication hole of the piston rod, thus changing the damping force of the shock absorber.

In the present invention, a third orifice is formed in the needle holder above the seal of the needle holder with respect to the piston rod, penetrating an outer wall and communicating with the needle insertion path. Is preferred.

Further, in the present invention, the needle valve operating mechanism of the needle valve includes a concave portion or a convex portion formed at the top of the needle valve, and a convex portion formed complementary to the concave portion or the convex portion. Or an operating rod having a concave portion at a lower portion, and the operating rod preferably extends upward beyond an upper edge of the piston rod.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. In this embodiment, the present invention is applied to a monotube gas-filled shock absorber.

Referring to FIG. 3, a monotube gas filled shock absorber is indicated generally by the reference numeral 100.

The shock absorber 100 has substantially the same structure as the conventional shock absorber 1 described with reference to FIGS. 1 and 2 except that it is a monotube type gas-filled structure.

The structure of the shock absorber main body will be briefly described.
Is a piston rod 102 and the piston rod 10
2, a lower spring bracket 104 is mounted on the cylinder 103, and an upper spring bracket 105 is mounted on the upper part of the piston rod 102. These spring seats 104, 105 A coil spring 106 is arranged between them.

The upper end of the piston rod 102 is attached to a vehicle body 109 via a rubber bush 107 and an upper attaching member 108, and the lower end of the cylinder 103 is attached to a suspension arm via a suitable connecting means. ing.

A piston 110 that slides along the inner wall of the cylinder 3 is attached to a lower portion of the piston rod 102, and the piston 110
Is divided into a first chamber, that is, an upper chamber 111, and a second chamber, that is, a middle chamber 112.
Is filled with oil. The piston 110 has a plurality of holes for communicating the upper chamber 111 and the middle chamber 112, that is, a first orifice.

The first orifice is used when the cylinder shrinks.
The constriction-side orifice 120 (see FIGS. 4 and 5) that allows the oil in the middle chamber 112 to flow into the upper chamber 111, and the oil in the upper chamber 111 when the cylinder extends.
And an expansion orifice 121 (see FIGS. 4 and 5) that allows the inflow into the upper chamber 111 through the compression orifice 120.
A one-way valve 122 for preventing oil from flowing into the middle chamber 112 is provided, and an extension-side orifice 121 is provided.
Through the extension side orifice 121 to the middle chamber 11
A one-way valve 123 for preventing the second oil from flowing into the upper chamber 111 is provided.

The shock absorber 100, which is a monotube gas-filled structure, also has a free piston 200 slidably disposed along the inner wall of the cylinder 103 below the piston 110. The free piston 200 forms a third chamber, that is, a lower chamber 201, between the free piston 200 and the bottom of the cylinder 103. In this lower chamber 201, for example, nitrogen gas is added, if necessary, generally at 5 kg / cm.
² to be filled at a pressure in the range of 30kg / cm ^2.

Although not shown and described, the piston 110 and the free piston 200 are sealed to the cylinder 103 using a suitable sealing means such as an O-ring.

The shock absorber 100 has a damping force adjusting device for adjusting the damping force determined or set by the diameter of the first orifice or the like.

In this damping force adjusting device, as can be clearly understood from FIGS. 4 and 5, the piston rod 102 is hollow. The hollow piston rod 102 is located above a piston 110 attached thereto.
A plurality of communication holes 102A penetrating the side wall or the peripheral wall of the piston rod 102 are formed. The communication hole 102A is
In this embodiment, four are formed at equal intervals in the circumferential direction on the same horizontal plane. By these communication holes 102A, the internal passage of the hollow piston rod 102 and the upper chamber 11 are formed.
1 is always communicated. The hollow piston rod 102 is also internally threaded on the inner surface at the lower end.

As shown in FIG. 4, the internal thread of the hollow piston rod 102 has a male thread 3 cut at the bottom.
The hollow needle holder 300 is attached by screwing or screwing the 01. A bolt head 302 is formed below the needle holder 300 to facilitate screwing the needle holder 300 to the piston rod 102.

An internal passage is formed in the hollow needle holder 300, and this internal passage has a lower enlarged portion 303 as can be clearly seen in FIG. A needle insertion path 304 having a diameter smaller than that of the enlarged diameter portion 303 is provided above the enlarged diameter portion 303.
Is formed, and a tapered portion 305 extends between the enlarged diameter portion 303 and the needle insertion path 304. Needle insertion path 304
An upper enlarged portion 306 having a diameter larger than that of the needle insertion passage 304 is formed above the needle insertion passage 304, and an abutting shoulder portion 307 is formed between the needle insertion passage 304 and the upper enlarged diameter portion 306. A female screw 312 is cut at an upper portion of the upper enlarged portion 306, that is, at an upper portion of an internal passage of the hollow needle holder 300. A plurality of holes or second orifices 308 are formed on the outer wall or peripheral wall of the needle holder 300 between the female screw forming portion and the abutting shoulder 307, and the second orifice 308 allows the needle holder 3
The internal passage of No. 00 communicates with the internal passage of the hollow piston rod 102 at the upper enlarged portion 306 above the needle insertion path 304. In this embodiment, the second orifices 308 are arranged at equal intervals in the circumferential direction on the same horizontal plane.
One is formed.

In this embodiment, the lower enlarged diameter portion 303 is used.
A pin 309 extending in the diametrical direction is provided. A check valve or ball 310 is disposed above the pin 309 in the lower enlarged portion 303, and a needle is provided between the pin 309 and the ball 310. An urging means or a coil spring 311 for urging the ball 310 upward so as to close the lower end of the insertion path 304 is arranged.

The outer wall or the peripheral wall of the needle holder 300 is also provided with a needle insertion path 30 by a coil spring 311.
Below the ball 310 that closes the lower end of 4,
A plurality of holes or third orifices 400 are formed.
Due to the third orifice 400, the internal passage of the needle holder 300 is moved to the hollow piston rod 1 at the lower enlarged portion 303 below the needle insertion passage 304.
02 is communicated with the internal passage. In this embodiment,
Two third orifices 400 are formed at equal intervals in the circumferential direction on the same horizontal plane.

The damping force adjusting device also has a needle valve 500 for changing or adjusting the flow cross-sectional area of the needle insertion path 304 of the needle holder 300.

The needle valve 500 is connected to the needle holder 3
The needle portion 501 is disposed in the internal passage of the needle holder 300 and inserted into the needle insertion passage 304 of the needle holder 300 at the lower portion. The needle portion 501 is similar to that of a conventional needle valve, and tapers downward and inward.
In this embodiment, the diameter of the upper end of the needle part 501 is slightly smaller than the needle insertion path 304 of the needle holder 300, but is connected to the abutting shoulder 502 having a larger diameter than the needle insertion path 304.

Above the needle portion 501, a support portion 503 having an abutting shoulder portion 502 at a lower portion is formed. Of course, the diameter of the support portion 503 is smaller than that of the upper enlarged portion 306 of the needle holder 300. The support 503 is located above the second orifice 308 of the needle holder 300 even when the abutting shoulder 502 of the needle valve 500 abuts against the abutting shoulder 307 of the hollow needle holder 300. In the region, an external thread 504 is formed,
The male screw 504 is screwed to the female screw 312 of the hollow needle holder 300.

An engaging portion 505 is formed above the support portion 503, that is, above the needle valve 500.
05 has a convex portion 506 extending in the diametrical direction on the top.

Above the needle valve 500, an operation rod 600 for adjusting the position of the needle valve 500 with respect to the needle holder 300 is arranged.

The operating rod 600 is provided at its lower part with a yoke portion 601 which engages with the convex portion 506 of the needle valve 500 and is formed complementary to the convex portion 506 so as to sandwich the convex portion 506. The control rod 600 also includes a knurled grip portion 602 at the top to facilitate rotation of the control rod 600. Bolt-shaped member 603 having a longitudinal through bore is provided on grip portion 6.
02, below the operating rod 600 so as to be freely rotatable,
The operation rod 600 is attached so as to be slightly movable in the vertical (longitudinal) direction. Further, the operating rod 600 is provided above the yoke portion 601 with O-rings 604, 6 forming a seal for the internal passage of the hollow piston rod 2.
05.

The operating rod 600 is disposed in the internal passage of the hollow piston rod 102 so that the yoke portion 601 is engaged with the projection 506 of the needle valve 500, and the male screw 603A of the bolt-shaped member 603 is hollow. Grip portion 602 is screwed into a female screw formed on the inner surface of the top of piston rod 102 so that grip portion 602 is hollow.
Projecting upward from

Next, the operation of the above embodiment will be described.

The first orifice 120 of the piston 110,
In order to change the damping force determined or set by 121 and the one-way valves 122, 123, the grip portion 602 that projects upward from the hollow piston rod 102, ie, is accessible from the outside, is gripped and Rotate.

Then, the operating rod 600 is rotatably supported by the bolt-shaped member 603, and is engaged with the yoke portion 6 so as to sandwich the projection 506 of the needle valve 500.
The needle valve 500 is rotated via 01. The needle valve 500 thus rotated is moved in accordance with the rotation direction thereof through the external thread 504 screwed into the internal thread 312 of the hollow needle holder 300 and the needle holder 30.
Moved up or down relative to zero. As a result of the movement of the needle valve 500 with respect to the needle holder 300, the degree of the needle portion 501 of the needle valve 500 inserted into the needle insertion path 304 of the needle holder 300, that is, the flow path cross-sectional area of the needle insertion path 304 of the needle holder 300 Can be changed.

For example, as shown in FIG.
The entire needle portion 501 of the needle 00 is the needle holder 300
Of the needle valve 500
By rotating the grip portion 602 from a state in which the abutting shoulder portion 502 abuts against the abutting shoulder portion 307 of the hollow needle holder 300, that is, from a state in which the cross-sectional area of the needle insertion path 304 is zero, As shown in FIG.
The abutment shoulder 502 of the needle valve 500 separates from the abutment shoulder 307 of the hollow needle holder 300, and the needle valve 50
The state where the zero needle portion 501 is partially inserted into the needle insertion path 304 of the needle holder 300 can be adjusted, that is, the flow path cross-sectional area of the needle insertion path 304 can be increased.

When the flow path cross-sectional area of the needle insertion path 304 is increased from zero in this manner, the shock absorber 100 changes the direction in which the damping force when the cylinder extends is weakened in accordance with the rate of the increase. Will be done.

That is, when the cylinder 103 is moved downward with respect to the piston 110 due to a depression on the road surface or the like, the needle insertion path 304 is completely closed.
5 (see FIG. 5), the oil in the upper chamber 110 flows into the middle chamber 112 through only the extension-side orifice 121, while when the needle insertion path 304 is open as shown in FIG. The amount of oil in the upper chamber 110 is increased in accordance with the cross-sectional area of the open needle insertion passage 304 in addition to the extension-side orifice 121 (first orifice). 3
08, needle insertion path 304, lower enlarged diameter portion 3 (by pushing down ball 310 against the urging force of coil spring 311)
It flows into the middle chamber 112 through 03, thus reducing the damping force during extension of the cylinder.

In other words, under the condition that the wheel moves up and down at a high speed, simply passing the oil through the first orifice 121 cannot make the cylinder 103 follow the wheel 103 with good response in response to the movement of the wheel. This is remarkable when the vertical movement is repeated at a high speed.) In such a case, the oil is also passed through the second oil circulation path, the needle insertion path 304, the second orifice 308, and the like. The cylinder 103 can be moved smoothly in response to the movement of the wheels.

In the shock absorber 100,
As the cylinder 103 moves up and down with respect to the piston 100 of the piston rod 102, the oil moves,
Although the moving oil acts on the needle valve 500 to move the position of the needle valve 500 with respect to the needle holder 300 due to its viscosity or the like,
The needle valve 500 is stably locked to the hollow needle holder 300 by the male screw 504 formed therein being screw-engaged with the female screw 312 of the hollow needle holder 300. The needle valve 500 is not moved with respect to the needle holder 300.

In this embodiment, since the third orifice 400 of the needle holder 300 is provided,
Even when the needle insertion path 304 is completely closed (see FIG. 5), the upper chamber 110 and the middle chamber 111 are in communication.

According to this configuration, the rise of the damping force with respect to the magnitude of the input to the tire can be made smooth. For example, in the absence of the third orifice 400, when the needle insertion path 304 is completely closed, when a force smaller than that required to open the one-way valves 122, 123 is applied to the tire, theoretically, The damping force is zero. Then, the force applied to the tire gradually increases, and when the force reaches a level large enough to open the one-way valves 122 and 123, the damping force suddenly rises. On the other hand, the third orifice 4
00 is provided, the needle insertion path 304
When the tire is fully closed and there is an input to the tire, even if this force is less than the force required to open the one-way valves 122, 123, the oil will
Through the upper chamber 110 and the middle chamber 111,
As a result, a damping force is generated, and as the force applied to the tire gradually increases, the damping force of the third orifice 400 also gradually increases, and finally, the input causes the one-way valves 122 and 123 to open. The third orifice 400 just before it is large enough
Since the magnitude of the damping force is not zero, the sudden rise of the damping force can be avoided. That is, by providing the third orifice 400, the rise of the damping force with respect to the magnitude of the input to the tire can be made smooth.

The present invention is not limited to the above-described embodiment, but allows various modifications as described below.

For example, in the above embodiment, although the damping force adjusting device of the present invention is applied to a monotube type gas-filled shock absorber, the cylinder is formed by a piston of a piston rod slidably attached thereto. The chamber is divided into two chambers, and the fluid is injected into each chamber, and when the cylinder and the piston are moved relative to each other, the fluid moves between the two chambers through the orifice formed in the piston, so that the damping force is generated. Can be applied to all shock absorbers based on the principle of providing.

In the above embodiment, when the pressure of the oil moving from the upper chamber 110 to the middle chamber 111 through the needle insertion path 304 is equal to or lower than a predetermined value, the oil passes through the needle insertion path 304 and moves to the upper chamber. Central room 1 from 110
Check valve mechanism 309, 31 for preventing movement to
Although 0 and 311 are provided, only the coil spring 311 may be eliminated, or the entire check valve mechanism may be eliminated. As can be easily understood, in the structure in which only the coil spring 311 is eliminated, the damping force of the shock absorber 100 when the cylinder 103 is contracted does not change. However, in the structure in which the entire check valve mechanism is eliminated, the needle insertion path 304 is not provided. From the middle room 111 to the upper room 1
Since the oil can also move to the shock absorber 10, not only the damping force of the shock absorber 100 when extended, but also the shock absorber 100 when contracted, according to the flow path cross-sectional area of the needle insertion path 304 by the needle part 501. The damping force can also be changed.

Further, in the above embodiment, the needle valve 50
Although the 0 and the operating rod 600 are formed as separate members, these members may be formed integrally. In this configuration, the needle valve / operating rod will move up and down relative to the piston rod 102 when rotated. Therefore, in this modification, for example, the grip portion 602 is connected to the bolt-shaped member 603 so that the grip portion 602 does not interfere with the bolt-shaped member 603 serving as the guide support member for the operation rod 600 in the above embodiment. 603 needs to be positioned sufficiently above. Also, the top of the operating rod is
(Below the upper edge of the piston rod 102),
The operating rod may be rotated by a suitable tool such as a screwdriver.

It should be noted that the terms “up”, “down” used in this specification
It should be noted that the direction with respect to is the concept relative to the axis of the vertically arranged cylinder, unless otherwise specified.

[0064]

As described above, the present invention is intended to prevent displacement of the position of the needle valve with respect to the needle holder by the fluid moving between the chambers of the cylinder separated by the piston mounted on the piston rod. A shock absorber damping force adjusting device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic partial enlarged sectional view of a conventional shock absorber.

FIG. 2 is an exploded view of a damping force adjusting device used in a conventional shock absorber.

FIG. 3 is a schematic sectional view of a shock absorber to which one embodiment of the damping force adjusting device of the present invention is applied.

FIG. 4 is a schematic partial enlarged sectional view of the shock absorber of FIG. 3;

FIG. 5 is a schematic partial enlarged sectional view of the shock absorber of FIG. 3, showing the needle valve in a fully closed state.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Shock absorber 102 Piston rod 103 Cylinder 110 Piston 111 Upper chamber 112 Lower chamber (middle chamber) 120, 121 First orifice 102A Communication hole 300 Needle holder 304 Needle insertion path 306 Upper enlarged part (upward enlarged path) 308 Second orifice 312 Female thread 500 Needle valve 501 Needle part 503 Support part 504 Male thread

Claims (3)

[Claims] 1. A piston rod having an upper portion connected to a vehicle body, a cylinder slidably attached to the piston rod, and a lower portion connected to wheels, and the cylinder is divided into an upper chamber and a lower chamber. A piston attached to the piston rod, and when the cylinder is moved relative to the piston rod, fluid injected into each of the chambers passes through a first orifice formed in the piston. A damping force adjustment device for a shock absorber adapted to provide a damping force by moving between said two chambers, wherein said piston rod extends through a longitudinal direction thereof; A needle holder having an internal passage communicating with the upper chamber of the cylinder and having a communication hole, and having an internal passage extending through in the longitudinal direction; A needle holder mounted at least partially on the piston rod with at least a portion disposed in the internal passage of the piston rod and having an outer surface substantially sealed against the internal passage of the piston rod; The passage has a needle insertion passage communicating with the lower chamber of the cylinder, and an upper enlarged passage formed above the needle insertion passage and having a larger cross-sectional area than the needle insertion passage. A second orifice penetrating the side wall of the needle holder above the needle insertion path and the seal, and a female screw formed on an inner surface of the upper enlarged passage above the second orifice; In order to increase or decrease the flow path cross-sectional area of the needle insertion path, A needle portion having a lower inwardly tapered needle portion at the lower end thereof, which is adapted to be inserted into the needle insertion passage, the needle valve having a support portion formed above the needle portion, The support portion forms a space between the needle holder and the inner surface of the upper enlarged passage, and has a male screw threadedly engaged with the female screw of the needle holder. Above the communication hole of the piston rod, sealed against the internal passage of the piston rod, for changing the position of the needle valve with respect to the needle holder, for rotating the needle valve from outside the piston rod The said needle valve has the needle valve operation mechanism of said, The said damping force adjustment apparatus characterized by the above-mentioned. 2. The needle holder has a third orifice formed above the seal of the needle holder with respect to the piston rod, penetrating an outer wall and communicating with the needle insertion path. ,
The damping force adjusting device according to claim 1. 3. The needle valve operating mechanism of the needle valve includes a concave portion or a convex portion formed at a top portion of the needle valve and a convex portion or a concave portion formed complementarily to the concave portion or the convex portion at a lower portion. 3. The damping force adjusting device according to claim 1, wherein the operating rod has an operating rod, and the operating rod extends upward beyond an upper edge of the piston rod.