JPH0293136A - Hydraulic buffer - Google Patents

Abstract

PURPOSE:To prevent the intrusion of the gas in a reservoir chamber into a cylinder tube and obtain a normal damping force immediately after the extension and contraction after stillness by forming the disc valve of a base in a structure which has not a constant orifice and installing a check seal in a guide member communication passage passing through a liquid chamber and the reservoir chamber. CONSTITUTION:As for the first communication passage 502, the upper edge opened port is closed by a check plate 5b, permitting the flow of working liquid only from the lower liquid chamber 1b to the upper liquid chamber 1c. A disc valve 5d in the first stage contacts a boss part sheet surface and the first sheet surface, and the second communication passage 503 can be opened and closed by the disc valve 5d in the first stage. The flow of the working liquid from a reservoir chamber 7 to the lower liquid chamber 1b through the first communication passage 402 is permitted by attaching a check plate 4g onto the upper surface of a base body 4f. Further, a check part 3c which permits the flow of the working liquid only from a liquid storage chamber 10 to the reservoir chamber 7 and regulates the flow of the sealing gas and the working liquid in the reservoir 7 in the reverse direction is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic shock absorber provided in an automobile suspension or the like.

(Prior art) As a conventional hydraulic shock absorber, for example,
The one described in No. 035 is known.

This hydraulic shock absorber includes a cylinder tube, a piston, a base, an outer cylinder, a piston rod, a guide member, and a seal member. A reservoir chamber was formed around the outer periphery.

On the reservoir chamber side, the lower liquid chamber is partitioned by a base, and the upper liquid chamber is partitioned by a guide.
Furthermore, the piston was formed with an orifice that communicated with the upper liquid chamber and the lower liquid chamber, and the base was formed with an orifice that communicated with the lower liquid chamber and the reservoir chamber.

Further, a liquid reservoir chamber is provided between the guide member and the seal member to collect hydraulic fluid leaked from between the piston rod and the guide member, and this liquid reservoir chamber and the reservoir chamber are communicated with each other through a guide member communication passage. Ta.

Further, a disc valve was provided in the orifice of the piston as a damping force generating means, and furthermore, a constant orifice was provided between the disc valve and the piston to generate damping force in a low speed range.

(Problem to be Solved by the Invention) In the hydraulic shock absorber as described above, the upper liquid chamber, the lower liquid chamber, and the reservoir chamber are connected to each other by the constant orifice of the piston, the orifice of the base, and the guide member communication passage of the guide member. Because the structure was such that the liquid storage chamber and the liquid storage chamber were always in communication, there were the following problems.

That is, in order for the hydraulic shock absorber to generate normal damping performance, the cylinder tube must be filled with hydraulic fluid. However, if left in a stationary state for a long time,
(For example, when applied to the suspension of a car, when the car is parked for a long time, etc.) As mentioned above,
Since each chamber is in communication, the gas in the reservoir chamber enters the cylinder tube, and normal damping performance cannot be obtained immediately after the cylinder tube starts expanding and contracting after being left alone.

Figure 9(a) shows the damping force immediately after the above-mentioned conventional hydraulic shock absorber starts expanding and contracting after being left for a long time.As shown in this figure, the first cycle stroke of the hydraulic shock absorber So,
Almost no damping force is generated, and it takes time to recover to a normal state.

In addition, when the gas that has entered the cylinder tube is excited with a large stroke, it is discharged to the reservoir chamber through the liquid reservoir chamber and the guide member communication passage, but when it is excited with a minute stroke (for example, In an automobile, when the vehicle is traveling on a good road, etc., gas that has entered the cylinder tube is difficult to be discharged, and in such a case, there is a delay in the rise of the damping force.

The present invention has been made by focusing on the above-mentioned conventional problems, and aims to provide a hydraulic shock absorber that can obtain a normal damping force immediately after the start of the expansion/contraction stroke after being left unused for a long time. The purpose is

(Means for Solving the Problems) In order to achieve such an object, in the hydraulic shock absorber of the present invention, one end is sealed by a guide member and the other end is sealed by a base to form a liquid chamber. a cylinder tube that forms a cylinder; an outer cylinder that forms a reservoir chamber filled with hydraulic fluid under the pressure of an enclosed gas on the outer periphery of the cylinder tube; a piston whose interior is partitioned into two liquid chambers; a guide member communication passage formed in the guide member so as to cause hydraulic fluid leaked to the outside of the liquid chamber from between the guide member and the piston rod to flow back to the reservoir chamber; a disc valve that is provided in a base communication passage formed in the base to communicate one of the liquid chambers and the reservoir chamber, and that opens to generate a damping force when the hydraulic fluid flows; The valve is formed to open in a low speed range and has a structure that does not have a constant orifice, and allows the working fluid and the sealed gas to flow to the reservoir chamber side and in the opposite direction through the guide member communication path. A check seal has been installed to regulate the distribution of

(Function) In the hydraulic shock absorber of the present invention, when the hydraulic shock absorber is at rest, the base communication passage between the liquid chamber and the reservoir chamber is closed by the disc valve, and since it does not have a constant orifice, the compartment is completely closed. will be cut off.

Furthermore, a check seal is provided between the fluid chamber and the reservoir chamber, which communicates with the fluid chamber via the piston rod and the guide member, to block the flow of gas and hydraulic fluid from the reservoir chamber.

Therefore, in this stationary state, the gas in the reservoir chamber does not enter the cylinder tube.

That is, normally, in a stationary state, the wave crest position of the hydraulic fluid in the cylinder tube is higher than the wave crest position of the hydraulic fluid in the reservoir chamber. For this reason, a difference in hydraulic pressure occurs due to the difference in wave crest position, and if the base communication path is not completely blocked,
Working fluid flows between the fluid chamber and the reservoir chamber. and,
If the guide member communication passage is not blocked, gas in the reservoir chamber will intrude into the liquid chamber from the guide member communication passage as the hydraulic fluid flows. is prevented.

Furthermore, if gas enters the cylinder tube and the liquid level in the liquid chamber drops, when vibration is applied with a large stroke, the gas will of course be discharged to the reservoir chamber via the guide member communication path.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be explained.

FIG. 1 is a sectional view showing a hydraulic shock absorber according to a first embodiment of the present invention, and numeral 1 in the figure indicates a cylinder tube. This cylinder tube 1 has an upper end closed by a guide member 2 and a seal member 3, a lower end closed by a base 4, and is filled with hydraulic fluid, and inside this cylinder tube 1 is a piston. 5 is slidably loaded and is divided into an upper liquid chamber 1a and a lower liquid chamber 1b.

Further, a bottomed cylindrical outer cylinder 6 is provided on the outside of the cylinder tube l, and a liquid chamber 1a inside the cylinder tube l,
A reservoir chamber 7 is defined by the guide member 2 and the base 4 with respect to the reservoir chamber 1b, and is filled with a desired amount of hydraulic fluid under the pressure of the enclosed gas.

The piston 5 is attached to the lower end of the piston rod 8. That is, the lower end of the piston rod 8 has a mounting portion 8b having a smaller diameter than the upper portion and having a thread 8a formed on the outer periphery.
are provided, and a retainer 5a,
Check plate 5b, piston body 5c, first stage disc valve 5d, washer 5e, stopper plate 1-
5f, 2nd stage disc valve 5g, washer 5h,
The assist spring 5m is sequentially inserted into the collar 5j and the spring seat 5, and finally fastened with a tightening nut 5n.

To explain further, the piston body 5c is provided with a large-diameter mounting hole 501 in the axial direction in the center thereof, and
At the outer position, a first communicating passage 502 with a large cross-sectional area and a second communicating passage 50 (corresponding to the piston communicating passage) with a small cross-sectional area are provided.
3 is formed.

The first communicating path 502 is connected to the check plate 5.
b closes the opening at the upper end, and is formed to allow only the flow of the working fluid from the lower fluid chamber 1b to the upper fluid chamber 1c.

On the other hand, as shown in Fig. 2, which is a detailed view of part A in Fig. 1,
On the lower surface side of the piston body 5c, a boss seat surface 504 is formed closer to the center than the second communication path 503, and a first seat surface 505 is formed on the outside of the second communication path 503, and further, A second sheet surface 506 is formed on the outside thereof.

The second seat surface 506 is formed with a step at a lower position than the first seat surface 505, and the space between the two seat surfaces 506 and 506 is annular and has a half-section. A circular shape 507 is formed.

The boss portion seat surface 504 and the first seat surface 50
The first stage disc valve 5d is brought into contact with the first stage disc valve 5d, and the second communication passage 503 can be opened and closed by this first stage disc valve 5d.

Note that this first stage disc valve 5d is
The outer periphery of the washer 5e, which has a smaller diameter, provides a support point for bending, and when the washer 5e bends by the thickness thereof, it comes into contact with the stopper plate 5f, changing the valve opening force.

O Further, a second stage disc valve 5g is brought into contact with the second seat surface 506 by being biased by an assist spring 5m. A constant orifice 508 is formed in the piston body 5C at the second seat surface 506, which communicates the inside and outside of the contact surface between the second stage disc valve 5g and the second seat surface 506.

The first-stage disc valve 5d is elastically formed to open even when the piston speed is extremely low, and this is made possible by the two-stage valve structure.

Next, the base 4 is also provided with a valve structure,
Its structure will be explained.

As shown in FIG. 1, the base 4 includes a port 4a, a washer 4b, a second stage disc valve 4c, a washer 4d, a first stage disc valve 4e, and a base body 4f.
, check plate 4g.

The retainer 4h and collar 4j are sequentially inserted and finally fastened with a tightening nut 4k.

In addition, the base body 4f is formed with a through hole 401 in the center through which the bolt 4a is passed, and a first communicating passage 402 with a large cross-sectional area and a second communicating passage with a small cross-sectional area (corresponding to the base communicating passage). ) 403 is formed.

Then, a check plate 4 is placed on the top surface of the base body 4f.
By making contact with g, the first communication path 402 allows only the flow of the working fluid from the reservoir chamber 7 to the lower fluid chamber 1b.

Furthermore, FIG. 3 is a detailed view of part B in FIG.
3, a boss portion seat surface 404 is formed at the center side of the base, a first seat surface 405 is formed at an outer position of the second communication path 403, and a second seat surface 406 is formed on the outer side of the first seat surface 405. has been done.

The second seat surface 406 is formed with a step at a lower position than the first seat surface 405, and the space between the two seat surfaces 405 and 406 is annular and has a half-section. A circular groove 407 is formed. Further, constant orifices 408 are formed at several locations on this second sheet surface 406.

The boss side seat surface 404 and the first seat surface 40
The first stage disc valve 4e is brought into contact with the first stage disc valve 4e, and the second communication passage 403 can be opened and closed by the first stage disc valve 4e.

Note that this first stage disc valve 4e is
A support point for bending is provided by the outer circumference of the washer plate 4d, which has a smaller diameter than the washer plate 4d, and when the washer plate 4d bends by the thickness, it comes into contact with the second stage disc valve 4c, and the valve opening force changes. It has become.

Further, the second stage disc valve 4c is in contact with the second seat surface 406.

Next, the upper end of the hydraulic shock absorber according to the embodiment will be explained with reference to FIG.
a is formed. Further, a guide bush 9 is provided on the inner periphery of this through hole 2a.

The seal member 3 provided above the guide member 2 is provided with a lip 3a that contacts and seals the piston rod 8, and a through hole 9 is provided between the seal member 3 and the guide member 2. A liquid reservoir chamber 10 is provided for storing hydraulic fluid leaked from between the piston rod 8 and the piston rod 8. Furthermore, this liquid reservoir chamber 10 is connected to a communication groove (corresponding to a guide member communication path) formed in the guide member 2. ) 2c communicates with the reservoir chamber 7.

Moreover, the lip 3a of the seal member 3 is in contact with the piston rod 8 and seals between the liquid reservoir chamber 10 and the outside, a seal portion 3b, and between the liquid reservoir chamber 10 and the communication groove 2c.
A check portion (corresponding to a check seal) 3c is provided which allows only the flow of the working fluid from the liquid storage chamber IO to the reservoir chamber 7, and in the opposite direction restricts the flow of the sealed gas and the working fluid from the reservoir chamber 7. It is formed.

As described above, the upper liquid chamber 1a and the lower liquid chamber 1b are partitioned by the piston 5, the lower liquid chamber 1b and the reservoir chamber 7 are partitioned by the base 4, and the reservoir chamber 7 and the upper liquid chamber 1a are partitioned by the base 4.
are separated by the guide member 2 and the check portion 3C of the lip 3a of the seal member 3. In this embodiment, in order to improve the sealing performance between the respective chambers 1a, lb, and 7, the piston body 5c is A piston ring 11 is provided on the outer periphery, and a seal ring 12 is provided between the guide member 2 and the piston rod 8.

The piston ring 11 is formed of polychlorotrifluoroethylene (commonly known as Teflon) into a ring shape with no seam in the middle, and as shown in FIG. 4, which is a detailed view of section C in FIG. A convex portion is provided in a fitting groove 5p formed on the outer periphery of the piston body 5c in a fitted state in which movement in the sliding direction of the piston body 5C is restricted, and is formed in the center of the fitting groove 5p. As shown in the figure, the outer periphery of the upper end portion is brought into contact with the inner surface of the cylinder tube 1, and the inner periphery of the lower end portion is brought into contact with the piston body 5C side, thereby providing a seal.

Polychlorotrifluoroethylene, which is the material of the piston ring 11, has high lubricity, low sliding resistance, and excellent operability.

Further, the seal ring 12 is connected to the piston ring 1.
1, it is formed of polychlorotrifluoroethylene into a ring shape with no seam in the middle, and the inner periphery is in contact with the piston rod 8. As shown in FIG. 5, which is a detailed view of section D in FIG. The piston rod 8 is housed in the housing groove 13a formed by the tightly fitted cover 13, and the forward and backward movement of the piston rod 8 is restricted. By forming the piston rod 8 to be large, a movement remaining portion 13b that can follow the eccentricity of the piston rod 8 is provided.

Next, the operation of the embodiment will be explained.

First, the operation when the damping force is generated in this embodiment will be briefly explained.

(I) During the extension stroke, when the piston 5 slides in the extension direction (in the direction of narrowing the upper liquid chamber 1a), based on the hydraulic pressure difference between the upper and lower liquid chambers 1a and lb,
The hydraulic fluid flows from the upper fluid chamber 1a to the lower fluid chamber 1b via the second communication passage 503 of the piston 5, and an amount of hydraulic fluid corresponding to the volume of the piston rod 8 withdrawn from the cylinder tube 1, The liquid flows from the reservoir chamber 7 into the lower liquid chamber 1b via the first communicating path 402 of the base 4.

At this time, in the piston 5, a damping force is generated in the first stage disc valve 5d, the second stage disc valve 5g, and the second communication passage 503 according to the piston speed.

Figure 6 shows the damping force characteristics of each of them.
FIG. 6(a) shows the damping force characteristics of the first stage disc valve 5d. That is, this first stage disc valve 5d
After the valve is opened, the characteristic is that of the speed 2/3, and a large damping force can be obtained even at extremely low speeds.

When the amount of deflection of the first stage disc valve 5d increases and it comes into contact with the stopper plate 5f, the elastic force increases and the slope of the characteristic becomes steeper. Incidentally, the inflection point a indicates the time when the first stage disc valve 5d contacts the stopper plate 5f.

Next, FIG. 6(b) shows the damping force characteristics of the second stage disc pulp 5g, and this valve 5g is in a closed state while the piston speed is low, and the characteristics of the constant orifice 508 are shown. The damping force is low at low speeds.

Then, when the piston speed becomes high and the second stage disc pulp 5g is opened, the speed becomes a 2/3 power characteristic. Incidentally, the inflection point S indicates the time when the second stage disc pulp 5g is opened.

Next, FIG. 6(C) shows the damping force characteristics of the second communication passage 503, and this second communication passage 503 has a speed squared characteristic in which almost no damping force is generated while the piston speed is low. It becomes.

In this way, in the stretching process, the above-mentioned characteristics are obtained in each part, and especially in the first stage disc pulp 5d,
Since a speed 2/3 power characteristic with a good rise from extremely low speeds can be obtained, the combined characteristics are as shown in Figure 7.
It has an excellent rise and almost linear damping force characteristics.

If such characteristics are obtained, when applied to an automobile suspension, it will be possible to respond with good response to changes in vehicle body posture with low piston speed, such as when turning the steering wheel, thereby improving handling. It also has an excellent distribution effect for bouncing at low piston speeds, such as when driving at high speeds. moreover,
Since the characteristics are almost linear and do not have any inflection points along the way, the characteristics may suddenly change at piston speeds near the inflection points, causing problems such as reduced steering stability. Nor.

(II) When the piston 5 slides in the positive direction (in the direction of narrowing the lower liquid chamber 1b) during the pressure stroke, the difference in liquid pressure between the upper and lower liquid chambers 1a and 1b should be equalized (the first communication passage of the piston 5 502, and an amount of hydraulic fluid corresponding to the volume of the piston 0 that enters the cylinder tube 1 flows from the lower fluid chamber ib through the second communication passage 403 of the base 4. It flows into the reservoir chamber 7.

At this time, in the base 4, a damping force is generated in the first-stage disc valve 4e, the second-stage disc valve 4c, and the second communication passage 403 in accordance with the piston speed.

The generation of this damping force is similar to the case described above. When the first stage disc valve 4e opens, first a damping characteristic of the speed 2/3 is obtained in the low speed range, and then this first stage disc valve 4e 4e comes into contact with the second stage disc valve 4c, the generated damping force increases and the slope of its characteristics becomes steeper.

On the other hand, the second stage disc valve 4c does not open in the low speed range, and obtains a speed square characteristic due to the constant orifice 4.08, and changes to a speed 2/3 characteristic from the time of opening.

Further, in the second communication path 403, in a low speed range, the speed square characteristic is such that almost no damping force is generated.

Even during this pressure stroke, the seal ring 12 prevents leakage, resulting in high responsiveness.

(III) At rest When the hydraulic shock absorber of the embodiment is at rest, the upper liquid chamber 1a
The first communication passage 50 of the piston 5 is connected between the lower liquid chamber 1b and the lower liquid chamber 1b.
2 is closed by the check plate 1-5b, and the second communication path 503 is blocked by the first stage disc valve 5d. Furthermore, since the first stage disc valve 5d does not have a constant orifice, it is completely shut off.

Furthermore, between the lower liquid chamber 1b and the reservoir chamber 7, the first communication path 402 is blocked by the check plate 4g, and the second communication path 403 is also blocked by the first stage disc valve 4e. Since the disc valve 4e also does not have a constant orifice, both chambers 1b and 7 are completely shut off.

Furthermore, a liquid reservoir chamber 10 communicating with the upper liquid chamber 1a,
A check portion 3C of the lip 3a of the check seal member 3 restricts the flow of gas and hydraulic fluid from the reservoir chamber 7 into the liquid reservoir chamber IO.

Therefore, even if a hydraulic pressure difference occurs due to a wave front difference between the hydraulic fluid in the sealing tube 1 and the reservoir chamber 7, it is difficult for the hydraulic fluid to flow. 3C, and will not enter the upper liquid chamber 1a.

(1v) At the time of starting FIG. 8 shows the damping force characteristics immediately after starting when the hydraulic shock absorber of this embodiment is left stationary for a long time and then started (expanded and contracted). In this example, since there is no gas intrusion into the upper liquid chamber la as described above, the
Normal damping force can be obtained from the 1st cycle. In addition, the amplitude is 5
The stroke is minute, about mm.

In contrast, Fig. 9 (a), (b), and (c) show the case of a conventional hydraulic shock absorber that has a constant orifice in the piston and does not have a check seal structure between the upper liquid chamber and the reservoir chamber. , and (a) shows the characteristics of the 1st cycle.As shown above, due to the long period of standing still, gas has entered the cylinder tube, causing almost no damping force in the 1st cycle. can't get it.

Further, FIG. 9(b) shows the characteristics after being vibrated for 30 seconds, which is still not in a normal state. Further, FIG. 9(c) shows the characteristics after being vibrated for one minute, and the damping force characteristics have returned to normal.

Furthermore, FIG. 10 shows another conventional example of a hydraulic shock absorber for comparison with this example (a constant orifice is provided in the disc valve, and a check seal similar to that in the example is provided in the guide member communication passage). The graphs show the characteristics of (a) the first cycle (b) of the hydraulic shock absorber after 30 seconds of vibration, and (c) 1 minute of vibration, and in this case, the return to normal is better than that shown in Figure 9. Although this is quick, normal characteristics cannot be obtained in the first cycle, and even after 30 seconds of vibration, there is still a deviation from the normal state. In addition, in FIGS. 9 and 10, the excitation stroke is fixed at 5 mm.

Furthermore, if gas were to enter the cylinder tube l of the hydraulic shock absorber of this embodiment and the liquid level in the upper liquid chamber 1a would drop, this hydraulic shock absorber would not be able to vibrate with a large stroke. At times, gas is of course discharged from between the piston rod 8 and the guide bush 2b to the reservoir chamber 7 via the liquid reservoir chamber 10 and the communication groove 2c of the guide member 2, as in the conventional case.

Furthermore, even when vibrating with a minute stroke, the first stage disc valve 5d of the piston 5 does not have a constant orifice, so the damping force rises well in the extension stroke, so the gas is It has a high excretion effect,
The gas is quickly expelled. Furthermore, in this example,
Regarding the gas evacuation performance during this minute stroke, the piston ring 11 is provided on the piston 5, so even in the extremely low speed range, leakage is unlikely to occur between the piston 5 and the cylinder tube 1, which reduces the damping force. The rise is even better, and therefore the gas discharge performance is further improved.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the example, only the first stage disc valve had a structure without a constant orifice, but the first and second stage disc valves did not have a constant orifice.
Either of the two stage disc valves may have a structure without a constant orifice, or both may have this structure.

Further, in this embodiment, the disc valve has a two-stage valve structure, but it may have a one-stage disc valve structure.

In addition, although the example shows an example in which a piston ring and a seal ring are provided to improve gas discharge performance, the material of both rings is not limited to polychlorotrifluoroethylene, and the material of both rings is not limited to polychlorotrifluoroethylene. It is not necessarily necessary to provide.

Further, in the embodiment, an example was shown in which the check seal provided in the guide member communicating path was formed integrally with the lip of the seal member, but it may be provided independently from this lip, or this check seal may be provided. The position may be in the middle of the guide member communication path or may be located on the side of the reservoir chamber.

(Effects of the Invention) As explained above, in the hydraulic shock absorber of the present invention, the base disc valve has a structure without a constant orifice, and the guide member communicates the liquid chamber and the reservoir chamber. A check seal is installed in the communication passage, so even if the hydraulic shock absorber is left stationary for a long time, gas from the reservoir chamber is prevented from entering the cylinder tube, and normal damping force is maintained immediately after expansion and contraction after stationary. It has the effect of being able to obtain the following.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a hydraulic shock absorber according to an embodiment of the present invention;
The figure is a detailed view of part A in Figure 1, Figure 3 is a detailed view of part B in Figure 1, Figure 4 is a detailed view of part C in Figure 1, and Figure 5 is a detailed view of part 1,
FIG. 6 is a graph showing the damping force characteristics on the piston side of the first embodiment, where (a) shows the characteristics of the first stage disc valve;
(1) shows the characteristics of the second stage disc valve, (c) shows the characteristics of the second communication path, Fig. 7 is a graph showing the damping force characteristics of the hydraulic shock absorber of the first embodiment, and Fig. 8 shows the characteristics of the second stage disc valve. A characteristic diagram showing the damping force of the first cycle after the example hydraulic shock absorber was left in a stationary state for a long time, FIG. 9 is a characteristic diagram showing the damping force characteristics of the conventional hydraulic shock absorber, and FIG. 10 is a characteristic diagram showing the damping force characteristics of the conventional hydraulic shock absorber. FIG. 7 is a characteristic diagram showing damping force characteristics of another conventional example. ■... - Schilling tube 1a - - Upper liquid chamber ib... Lower liquid chamber 2... Guide member 2c... Communication groove (guide member communication path) 3... Seal member 3cm... Check part Check seal) 4--Base 4e...-1st stage disc valve 403...2nd communication path (base communication path) 5...Piston 5d...-1st stage disc valve (piston communication path) 503 ...Second communicating passage 6...Outer cylinder 7...Reservoir chamber 8-...Piston rod 10...Liquid chamber (guide section communicating passage) Patent application Hitotatsugi Auto Parts Co., Ltd. 0 .1 Piston movement port

Claims (1)

[Scope of Claims] 1) A cylinder tube whose one end is sealed by a guide member and the other end by a base to form a liquid chamber; an outer cylinder forming a reservoir chamber filled with hydraulic fluid; a piston provided at the tip of a piston rod guided by a guide member and dividing the inside of the cylinder into two liquid chambers; a guide member communication path formed in the guide member to allow hydraulic fluid leaked to the outside of the liquid chamber to flow back to the reservoir chamber; and a base communication path formed in the base to communicate one of the liquid chambers with the reservoir chamber. A disc valve is provided in the passage and opens to generate a damping force when hydraulic fluid flows, and the disc valve is formed to open in a low speed range and does not have a constant orifice. A hydraulic shock absorber, characterized in that the guide member communication passage is provided with a check seal that allows the flow of the working fluid and the sealed gas toward the reservoir chamber side, and restricts the flow in the opposite direction.