JPH03341A - Valve of hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To regularly stabilize the attenuating force generated by a valve by generating a determined attenuating force by the valve and preventing the air inflow to a hollow piston rod by its check function, when an operating oil flows out of the rod. CONSTITUTION:By regulating the lowering quantity of the valve stopper 22 of this hydraulic shock absorber, or the rotating operation quantity of a dial 14 fixed to the upper end of a hollow piston rod 3, the attenuating force generated by a valve 10 can be freely adjusted. At the time of extending and contracting the hollow piston rod, an operating oil is regularly passed through the hollow piston rod 3, and also run into a reservoir chamber C through the valve 10 outside of the hollow piston rod 3. However, as the lip part 10b of the valve 10 is closely adhered to the outer circumference of the hollow piston rod 3, the check function is exhibited, and the air in the reservoir chamber C or an air chamber D is never run into the oil passage 3a of the hollow piston rod 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve for a hydraulic shock absorber that is most suitable for use in front forks and the like.

(Prior art and its problems) In a conventional hydraulic shock absorber 7 such as a front fork, for example, as shown in FIG. 6, when the vehicle body side tube 2 is moved in and out of the wheel side tube l, Vehicle side tube 2
The hydraulic oil passing through the inside of the hollow piston rod 3 disposed at the axial center of the hollow piston rod F3 flows out to the outside of the hollow piston rod F3, and at this time, a predetermined damping force is generated. There is.

That is, this hydraulic shock absorber is inserted in such a manner that the outer circumference of the vehicle body side tube 2 is in sliding contact with the inner circumference of the wheel side tube 1, so that the damper cylinder 4 can protrude and retract from the inside of the lower end of the wheel side tube 1. He stands up.

The upper end of the vehicle body side tube 2 is closed with a cap 5, and a hollow piston rod 3 is suspended from the solid shaft core inside the cap 5.

The tambour cylinder 4 has a piston 6 slidably housed therein, and the piston 6 divides the inside into an upper oil chamber A and a lower oil chamber B. The lower ends of the hollow piston rods 3 are connected to each other.

The piston 6 has a check valve 5 that allows hydraulic oil to flow into the upper oil chamber A from the lower oil chamber B and prevents its reverse flow.
a, and a relief valve 6b for releasing abnormally high pressure in the upper oil chamber A into the lower oil chamber B.

- side, inside the lower end of the damper cylinder 4.

A base valve section 7 is provided, and the base valve section 7 is provided with a check valve 7a and a relief valve 7b.

That is, a reservoir chamber C is formed between the inner circumference of the wheel side tube l and the outer circumference of the damper cylinder 4,
The check valve 7a of the base valve part 7 allows the hydraulic oil to flow into the lower oil chamber B from the reservoir chamber C while preventing its reverse flow, and the relief valve 7b of the base valve part 7 allows the hydraulic oil to flow into the lower oil chamber B. The abnormally high pressure will be released into the reservoir chamber C.

Note that an air chamber is formed above the reservoir chamber C, with the oil level as a boundary.

A suspension link 8 is interposed between the upper end of the damper cylinder 4 and the inner-upper end of the vehicle body side tube 2, and the suspension link 8 is interposed in the direction in which the vehicle body side tube 2 is pushed out from inside the wheel side tube 1, that is, the hydraulic shock absorber. is energized in the direction of extension.

The upper end of the damper cylinder 4 is closed with a bearing member 9, and the hollow piston rod 3 is inserted through the shaft core of the bearing member 9 in a sliding manner.

By the way, in the above conventional example, the cap 5 has an oil passage 5a that communicates with the upper end of an oil passage 3a formed inside the hollow piston rod 3, and
It has a valve 5b consisting of a throttle inside a.

The lower end of the oil passage 3a communicates with the upper oil chamber A.

Therefore, when the hydraulic shock absorber according to the conventional proposal is extended, the piston 6 rises inside the damper cylinder 4, and at this time, the hydraulic oil in the upper oil chamber A flows into the oil path of the hollow piston rod 3. 3a into the oil passage 5a of the cap 5, and through the valve 5b in the oil passage 5a to the outside of the hollow piston rod 3, that is, through the air chamber but into the reservoir chamber C. It will be leaked to.

At this time, as the piston 6 moves up inside the damper cylinder 4, the insufficient hydraulic oil in the lower oil chamber B is transferred to the reservoir chamber C via the check valve 7a of the base valve section 7.
will be replenished from

When the hydraulic shock absorber is compressed, the piston 6 moves down inside the damper cylinder 4, and the hydraulic oil in the lower oil chamber B flows into the upper oil chamber A through the check valve 6a of the piston 6. There will be an influx.

At this time, the hydraulic oil equivalent to the volume of the hollow piston rod 3 that becomes surplus when the piston 6 descends in the lower oil chamber B also flows into the upper oil chamber A through the check valve 6a of the piston 6. At the same time, the oil flows into the oil passage 3a of the hollow piston lock 3 and the oil passage 5a of the cap 5, and flows out into the reservoir chamber C via the valve 5b in the oil passage 5a.

That is, in the conventional hydraulic shock absorber E, during its expansion and contraction operation, hydraulic oil always flows into the oil passage 5a of the cap 5 via the oil passage 3a of the hollow piston rod 3, and the oil passage 5a also flows into the oil passage 5a of the cap 5. It flows out into the reservoir chamber C, which is the outside of the hollow piston rod 3, through the valve 5b inside.

Therefore, when the hydraulic shock absorber expands and contracts, the valve 5b
Therefore, a damping force of a predetermined magnitude is generated, and the generated damping force needs to be stabilized.

However, in order to stabilize the damping force generated by the valve 5b, it is particularly necessary for the air → from the air chamber above the reservoir chamber C to pass through the valve 5b to the oil passage 3a inside the hollow piston rod 3. You must absolutely avoid allowing it to flow back into your body.

This invention has been devised in view of the above-mentioned circumstances, and its purpose is to provide a damping mechanism which is disposed in an oil passage communicating with an oil passage in a hollow piston rod and which exerts a predetermined damping action. Of course, by preventing air outside the hollow piston loft from flowing into the oil passage inside the hollow piston rod,
An object of the present invention is to provide a valve for a hydraulic shock absorber that enables stable generation of damping force.

[Means to solve the problem]

In order to achieve the above-mentioned object, the structure of the valve of the hydraulic shock absorber according to the present invention is such that hydraulic oil passes through a hollow piston rod disposed at the axial center of the vehicle body side tube that is retracted and retracted from the wheel side tube. In a hydraulic shock absorber formed to generate a predetermined damping force when air flows out of the hollow piston rod, there is a hydraulic shock absorber on the outer circumferential side of the hollow piston rod to prevent air from flowing into the hollow piston rod and to prevent air from flowing into the hollow piston rod. , the initial load at the time of opening can be adjusted.

It is assumed that a damper cylinder is erected from inside the lower end of the wheel side tube, and a hollow piston rod is suspended from a cap that closes the upper end of the vehicle body side tube.

Further, the damper cylinder has a piston slidably housed inside the damper cylinder, and the inside is partitioned by the piston into an upper oil chamber and a lower oil chamber, and the piston has a hollow piston loft at the lower end. will be installed in succession.

The piston also includes a check valve that allows hydraulic oil to flow into the upper oil chamber from the lower oil chamber and prevents its reverse flow, and also releases abnormally high pressure in the upper oil chamber into the lower oil chamber. It has a relief valve.

On the other hand, the base valve part disposed inside the lower end of the damper cylinder prevents hydraulic oil from flowing into the lower oil chamber from the reservoir chamber formed between the inner periphery of the wheel side tube and the outer periphery of the damper cylinder. A check valve that permits this, and a relief valve that releases abnormally high pressure in the lower oil chamber to the reservoir chamber are provided.

(Function) Therefore, when the hydraulic shock absorber is extended, the piston moves up inside the damper cylinder, and the hydraulic oil in the upper oil chamber is distributed outside the hollow piston rod via the oil passage inside the hollow piston rod. It flows out into the reservoir chamber, which is the outside of the hollow piston rod, through the hollow piston rod.

On the other hand, when the hydraulic shock absorber is compressed, the piston moves down inside the tambour cylinder, causing the hydraulic oil in the lower oil chamber to flow into the upper oil chamber via the piston, and the hydraulic oil also flows into the hollow piston rod. The oil flows out into the reservoir chamber outside the hollow piston rod through an oil passage and a valve disposed outside the hollow piston rod.

That is, in the hydraulic shock absorber according to the proposal, during its expansion and contraction operations, hydraulic oil is always supplied to the hollow piston rod via an oil path inside the hollow piston rod, and through a valve disposed outside the hollow piston rod. It flows out into the reservoir chamber which is the exterior of the hollow piston loft.

Incidentally, when the hydraulic shock absorber is extended, the insufficient hydraulic oil in the lower oil chamber is replenished from the reservoir chamber, and
During the compression operation of the hydraulic shock absorber, there is also excess hydraulic oil in the lower oil chamber.

It flows into the upper oil chamber via the piston.

〔Example〕

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

As shown in FIG. 1, the hydraulic shock absorber according to the embodiment of the present invention is used as a front fork of a two-wheeled vehicle, and the front fork is basically different from the conventional example (FIG. 6). They are formed to have the same configuration.

Therefore, the same reference numerals are given to the members having the same structure in FIG. 1 and the explanation thereof is omitted, and the following is
I will mainly explain the different points.

That is, as shown in FIG. 2, the valve tO according to the present invention is not only disposed on the outer peripheral side of the hollow piston rod 3, but also disposed inside the cap 5 that closes the upper end of the vehicle body side tube 2. Suppose it is included in the.

To explain briefly, in this embodiment, the cap 5 is formed into a thick-walled cylindrical shape with a head, and the outer periphery of the lower end side is sealed with the seal 11 on the inner periphery of the upper end side of the vehicle body side tube 2.
The upper end of the hollow piston rod 3 is screwed onto the shaft core portion on the upper end thereof.

The L hollow piston rod 3 is formed such that its upper end protrudes upward from the upper end of the cap 5, and the plug 12 is housed with a seal 13 interposed therebetween from the inside of the upper end to the lower inside thereof. It will be done.

The plug 12 has its upper end protruding from the upper end of the hollow piston rod 3, and has a dial 1 attached to the protruding end.
4 are permanently installed.

The dial 14 has a set screw 15 threaded therein, and is fixedly connected to the upper end of the hollow piston rod 3 by screwing the set screw 15.

Further, a detent mechanism 16 is disposed between the lower end surface of the dial 14 and the upper end surface of the cap 5, and is formed so that the rotational state of the dial 14 with respect to the cap 5 is stabilized at an arbitrary position. ing.

The detent mechanism 16 includes a steel ball 16a fitted in a recess 14a formed on the lower end surface of the dial 14 and a hole 5C bored in the upper end of the cap 5. It has a sublink 16b that urges the steel ball 16a in the projecting direction.

Therefore, in this embodiment, the hollow piston rod 3 is rotated around the axis on the upper end side of the cap 5 by rotating the dial 14, and is moved up and down with respect to the cap 5, that is, on the vehicle body side. It is formed so that it can be moved up and down within the tube 2.

On the other hand, the upper part of the inside of the cap 5 has a relatively small diameter recess 5d, while the lower part of the inside thereof has a relatively large diameter recess 5e.

A valve seat 17 is disposed within the concave portion 5d, while a valve 10 according to the present invention is disposed within the concave portion 5C.

The E valve seat 17 is formed into a substantially cylindrical shape and is inserted around the outer periphery of the hollow piston rod 3 in the vicinity of the upper end thereof, and its outer periphery is attached to the inner periphery of the small diameter concave portion 5d.
They are in sliding contact with each other.

The valve seat 17 has an annular notch 17a on the inner periphery of the lower end thereof, and a communication hole 17b facing the annular notch 17a in the thick wall portion of the lower end. .

The annular notch 17a faces a communication hole 3b that is opened near the upper end of the hollow piston rod 3 and communicates with the existing oil passage 3a inside the hollow piston rod 3. is communicated with the outer peripheral side of the valve seat I7.

In this embodiment, the valve seat 17 is interposed on the outer periphery of the hollow piston rod 3 in the vicinity of the upper end, and includes a nut 19 screwed onto the outer periphery of the hollow piston rod 3 in the vicinity of the -E end. It is said that it will be fixed in a predetermined position.

The L nut 19 is fixed to the hollow piston rod 3 by a female screw 20 which is screwed into the L nut 19.

Further, the valve seat 17 has a seal 21 interposed inside its upper end, and the seal 21 ensures the so-called sealing performance of the valve seat 17 against the nut 19 and the hollow piston rod 3.

On the other hand, the lower end of the valve seat 17 is in contact with a valve stopper 22 fixedly fixed to the outer periphery of the hollow piston rod 3.

The valve stopper 22 is fixed to the outer periphery of the hollow piston rod 3 by a snub ring 23 interposed on the outer periphery of the hollow piston rod 3.

Further, the valve stopper 22 is formed into a relatively thin and shallow cylindrical shape with a bottom, and the hollow piston rod 3 is inserted through the center portion of the bottom portion 22a, and the wall thickness of the peripheral portion of the bottom portion 22a is reduced. The communication hole 22b penetrates through the hole 22b.
It has.

The valve stopper 22 has an upright position on its outer circumferential side.
One end of the E portion 22C is formed as an inwardly inclined surface 22d, and the inclined surface 22d is formed in the valve 1, which will be described later.
It is set so that the contact/separation mark is on the outer circumferential surface of 0.

By the way, the above-mentioned bulb 1B is arranged in a lower concave part 5C inside the cap 5, and an annular holder 24 is housed in the concave part 5e. It is said that a valve ring is arranged on the inner circumference.

The valve 11) is formed into an annular shape so as to be fitted into the inner peripheral side of the holder 24, and includes a thick base (Oa) and a lip portion ta connected to the base 10a.
b.

The lip portion 10b is formed so as to be inclined toward the inner circumferential side, and the tip of the lip portion tab on the inner circumferential side is in sliding contact with the outer circumferential surface of the valve seat 17.

On the other hand, the lip portion tab 5 has an inclined surface on its outer circumferential side, and an inclined surface 22d at the upper end of the rising portion 22c of the valve stopper 22 is adjacent to the inclined surface so as to be able to move toward and away from it.

The holder 24 is fixed at a predetermined position by a plurality of stop rings 25 fitted to the inner periphery of the lower end of the concave portion 5e.

Therefore, in this embodiment, as shown in FIG. 3, when the hollow piston rod 3 is lowered within the cap S, the valve string member 22 is also lowered following the lowering of the hollow piston rod 3. Become.

At this time, on the cap 5 side, the valve 10 is held in a so-called fixed state.

Therefore, an appropriate gap is formed between the inclined surface 22d of the rising portion 22c, which is the upper end of the valve stopper 22, and the outer peripheral surface of the lip portion tab of the valve IO.
The so-called initial load of the valve 10 can be changed by the amount that the gap is formed.

However, as mentioned above, Harbus I- for valve IO
Even if the initial load of the valve IO is changed by moving the collar 22 toward or away from the valve 10, the valve 10 will of course still perform the so-called check valve function.

In the front fork, which is a hydraulic shock absorber according to the present invention formed as described above, when the front fork is extended, the piston 6 moves up inside the damper cylinder 4, similar to the conventional example described above. .

Therefore, the hydraulic oil in the upper oil chamber A is transferred to the outer peripheral side of the valve seat 17 via the oil passage 3a and communication hole 3b in the hollow piston rod 3, and the annular notch 17a and communication hole 17b in the valve seat 17. That is, the water flows to the inner circumferential side of the valve IO, and the lip portion tab of the valve 10 is bent to the outer circumferential side, that is, it is opened, and the communication hole 2 of the valve stopper 22 is opened.
It flows out into the reservoir chamber C through the air chamber which is the outside of the hollow piston rod 3 through 2a.

At this time, as the piston 6 moves up inside the damper cylinder 4, the insufficient hydraulic oil in the lower oil chamber B is transferred to the reservoir chamber C via the check valve 7a of the base valve section 7.
will be replenished from

When the front fork is compressed, the piston 6 moves down inside the tambour cylinder 4, and the hydraulic oil in the lower oil chamber B flows into the upper oil chamber A through the check valve 6a of the piston 6. do.

At this time, the hydraulic oil equivalent to the volume of the hollow piston rod 3 that becomes surplus when the piston 6 descends in the lower oil chamber B also flows into the upper oil chamber A through the check valve 6a of the piston 6. do.

The hydraulic oil that has flowed into the upper oil chamber A also flows through the oil passage 3a and communication hole 3b in the hollow piston rod 3, the annular cutout 17a of the valve seat 17, and the communication hole 17b, and passes through the valve seat 17. The liquid flows to the outer circumferential side of the valve 10, that is, to the inner circumferential side of the valve 10, and the lip portion 10b of the valve 10 is bent toward the outer circumferential side, that is, opened, and flows through the communication hole 22a of the valve stopper 22. It flows out into the reservoir chamber C through the air chamber which is the outside of the hollow piston rod 3.

Therefore, in the hydraulic shock absorber according to this invention, by adjusting the amount of descent of the L valve stem 22, that is, the amount of rotation of the dial 14 fixed to the upper end of the hollow piston rod 3, The damping force generated by the valve 10 can be adjusted freely.

In the above-mentioned hydraulic shock absorber, during its expansion and contraction operation, the hydraulic oil always passes through the hollow piston rod 3 and flows out into the reservoir chamber C through the valve 10 outside the hollow piston rod 3. However, since the lip portion 10b of the valve 10 is in close contact with the outer periphery of the hollow piston rod 3, a so-called check valve function is exerted, and the air in the reservoir chamber C1, that is, the air chamber is The oil no longer flows into the oil passage 3a of the hollow piston rod 3.

The characteristic actions and effects of the present invention as described above are also applicable to other embodiments described below.

That is, FIG. 4 shows another embodiment of the present invention, which basically has the same structure as the embodiment described above.

Therefore, the following explanation will focus on the points that are different from the embodiments described above.

First, in this embodiment, the holder 24 is housed in the large diameter concave portion 5e of the cap 5 and holds the bulb 10.
The lower end of the cap 5 is caulked (symbol 5f in the figure).
) is fixed in a predetermined position.

At the upper ends of the holder 24 and the bulb 10,
An annular spacer 26 is housed to prevent the upper end of the base 10a of the valve 10 from being deformed.

Further, the spacer 26 is in sliding contact with the outer circumference of the valve seat 17 with its inner circumferential surface.

The spacer 26 is housed in the concave portion 5C, and the seal 27 fitted on the outer circumferential surface of the spacer 26 is in contact with the inner circumferential surface of the concave portion 5e.

On the other hand, the valve seat 17 is of course fitted with a seal 18 on its outer circumferential surface, but in this embodiment,
Compared to the embodiments described above, it is formed relatively thin.

An annular groove 17c is formed on the inner periphery of the lower end in place of the annular notch 17a in the embodiment described above, and the annular groove L7c communicates with the communication hole 17b.

Further, in this embodiment, the seal 21 which was housed inside the end of the valve seat 17 in the previous embodiment is located at the lower end of the spacer 28 which is disposed adjacent to the upper end of the valve seat 17. It is assumed that the seal 21 is arranged on the inner periphery, and that the so-called sealing property between the spacer 28 and the valve seat 17 is ensured by the seal 21.

It is assumed that the upper end of the spacer 28 is adjacent to the lower end of a nut 19 screwed onto the outer periphery of the hollow piston rod 3 near the upper end.

In addition, a dial 14 is fixed to the upper end of the hollow piston rod 3, as in the above embodiment, and a seal I3 is provided in the center of the dial 14 within the hollow piston rod 3. It is assumed that the upper end of the housed plaque I2 will not be penetrated.

Next, FIG. 5 shows still another embodiment of the present invention, but instead of each of the embodiments described above being configured to be operated by so-called manual operation, this embodiment The device is characterized in that it is configured to be activated by turning on and off a so-called solenoid.

Therefore, for parts whose configuration is basically the same,
The same reference numerals are given and the explanation thereof is omitted, and below 1, the explanation will focus on the points that are different compared to each of the above-mentioned embodiments.

That is, in this embodiment, the cap 5 is formed into a substantially cylindrical shape, and a so-called solenoid is provided above the annular partition wall 5g which is protruded from the inner peripheral surface of the cap 5. - The id portion is formed so as to have a structure in which a so-called valve portion is disposed below the id portion.

First, a coil 29 interposed on the outer periphery of the hollow piston rod 3 near the upper end is housed inside one half of the cap 5, and the coil 29 is stabilized between it and the partition wall 5g. To be.

A washer 30 is arranged inside the upper end of the cap 5.

Then, a nut I9 for fixing the washer 30 is attached to the threaded part on the outer periphery of the upper end of the hollow screw 3.
is screwed on.

In addition, on the outer periphery of the upper end of the hollow piston rod 3,
A rubber cap 31 is attached, and the rubber cap 3
The outer peripheral end of the piston rod 1 is attached to the upper end of the cap 5, and a plug cap 32 is screwed onto the upper end of the hollow piston rod 3.

Similarly to the embodiment shown in FIG. .

Next, inside the lower half of the cap 5, a spacer 33 is installed on the outer periphery of the hollow piston rod 3 in order from above.
A core 34 and a valve case 35 are housed therein.

In this embodiment, the spacer 33 is made of a non-magnetic member formed into an annular shape, and seals 36 and 37 are interposed at the outer upper edge and the inner lower edge, respectively.

The core 34 is made of a magnetic member formed into a cylindrical shape, and its inner periphery is brought into close contact with the outer periphery of the hollow piston rod 3.

The Hartz case 35 holds the valve 10 on its inner peripheral side in place of the holder 24 in each of the embodiments described above, and is disposed between the valve seat 17 and the lower valve seat 17 as a non-exciting member for the core 34. It also plays the role of a spacer.

Incidentally, the valve seat 17 in this embodiment has the following characteristics:
The stone rod 3 is formed into a short cylindrical shape and is hollow and inserted around the outer periphery of the stone rod 3, and a notch 17d communicating with the communication hole +7b is formed on the inner periphery of the upper end thereof.

On the other hand, the inside of the lower half of the cap 5 in this embodiment covers the valve case 35 from its outer peripheral side, and
A ring 38 configured to be movable down is housed here.

That is, the ring 38 is formed of a magnetic member into a cylindrical shape with a head, and has an opening 38b at the center of its upper end 38a, which is a cut surface or an inclined surface.

The opening 38b is capable of moving toward and away from the inclined surface 34a formed at the lower edge of the outer circumferential side of the core 34.
ing.

Further, in the case of the ring 38, the lower end of the spring 39 is brought into contact with the upper end of the ring 38, and the spring 39
The upper end is latched to the lower end surface of the spacer 33 above.

Incidentally, when the ringco 8 is brought into the downward state by the biasing force of the spring 39, the downward pressure is controlled by the upper end 38a of the link 38 coming into contact with the upper end of the lower valve case 35. is set to .

Therefore, in this embodiment, when the so-called solenoid is turned on by energizing the coil 29, the coil 29 is turned on.
The magnetic force from 9 is applied to the hollow piston port, 34
This acts as a suction force on the ring 38 via.

At this time, the ring 38 overcomes the biasing force of the spring 39 and rises inside the lower half of the cap 5, so that it is attracted to the core 34.

When the energization operation to the coil 29 is released and the so-called solenoid is turned off, the magnetic force from the coil 29 is demagnetized, and the ring 38 is pushed inside the lower half of the cap 5 by the force of the spring 39. It will be lowered.

By the way, in this embodiment, an annular valve stopper 22 is fixed to the inner periphery of the lower end of the link 38, and the inner periphery upper edge of the valve stopper 22 is connected to the lip portion tab of the valve 10. It is said that it can be freely attached to and detached from the outer periphery.

In addition, when the valve stopper 22 is fixed to the inner periphery of the lower end of the ring 38, the lower end of the link 38 is caulked (indicated by reference numeral 38c in the figure).

Therefore, this embodiment has the advantage that so-called remote control can be used, and the range of use of the hydraulic shock absorber is widened.

Each of the above-mentioned embodiments has been described as a hydraulic shock absorber or a front fork, but the object, structure, and
Judging from the operation and effect, it goes without saying that the hydraulic shock absorber referred to herein may be replaced by a so-called shock absorber.

(Effects of the Invention) As described above, according to the present invention, the hydraulic oil in the damper cylinder passes through the oil passage in the hollow piston rod and flows out of the hollow piston rod, and the hydraulic oil flows through the hollow piston rod. When the air flows out of the piston rod, not only a predetermined damping force is generated by the valve disposed on the outer periphery of the hollow piston rod, but also the valve exerts a check valve mechanism, and the above-mentioned There is an advantage in that the damping force generated by the valve can always be stabilized by not allowing air to flow into the hollow piston rod.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a front fork as a hydraulic shock absorber according to an embodiment of the present invention, FIG. 2 is a partially enlarged sectional view thereof, and FIG. 3 is a partially enlarged half sectional view showing its operating state. 4 and 5 are partially enlarged half-sectional views showing other embodiments of the present invention, and FIG. 6 is a longitudinal sectional view showing a conventional front hook similar to FIG. 1. (Explanation of symbols) l...Wheel side tube 2...Vehicle side tube 3...Hollow piston rod 4...Dunbar cylinder 5...Cap 6...Piston 6a, 7a...Check Valve 6b, 7b...Relief valve 7...Base valve part 10...Valve 17...Valve seat 1-22...Harbus I, collar A...Upper oil chamber B...Lower oil chamber C...Reservoir room

Claims (1)

[Claims] It is formed so that a predetermined damping force is generated when the hydraulic oil flowing in the hollow piston rod disposed at the axial center of the vehicle body side tube that goes in and out of the wheel side tube flows out of the hollow piston rod. The hydraulic shock absorber is characterized in that the outer peripheral side of the hollow piston rod is formed to prevent air from flowing into the hollow piston rod and to adjust the initial load when the rod is opened. hydraulic shock absorber valve