JP3398467B2 - Hydraulic shock absorber - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber used for a front fork or the like of a motorcycle.

[0002]

2. Description of the Related Art As a hydraulic shock absorber used in a vehicle or the like, a single cylinder type damper consisting of a damper cylinder and a piston rod is internally provided in an outer tube and an inner tube which are slidably fitted, and a damper is provided on the outer periphery of the damper cylinder. It is known that an oil reservoir is provided which communicates with the oil chamber in the cylinder.

By the way, in such a type of hydraulic shock absorber, as a single-cylinder damper, a hollow rod 102 is inserted into a cylinder 101 as shown in FIG. Piston 1 slidingly contacts piston holder 103 with the inner peripheral surface of cylinder 101
04, the oil passage 105 is formed in the piston 104, and the valve 106 for opening and closing the oil passage 105 is provided on the upper surface.
Disc 1 having oil passage 107a on the upper surface of valve 106
07 is slidably arranged, and the spring 107 interposed between the disk 107 and the holder 108 having the notch 108a urges the disk 107 toward the valve 106 side. The hollow piston holder 1 is formed by forming a communication hole 110 that connects S1 and the internal passage 102a.
It is known that a cylindrical slide valve 111 is slidably fitted in the housing 03.

In this single-cylinder damper, the hydraulic oil in the cylinder lower chamber S2 is compressed by the hollow piston holder 103 during compression when the piston 104 moves downward, as shown in FIG.
Flow into the inner lower passage 103a of the slide valve 11
1 is pushed up, the communication hole 110 is closed by the slide valve 111, and the valve 106 and the disk 107 are pushed up against the urging force of the spring 109 by the pressure of the hydraulic oil flowing into the oil passage 105 of the piston 104. Is opened, and the hydraulic oil flows into the cylinder upper chamber S1.

Further, as the piston 104 moves upward and extends, the slide valve 111 lowers as shown in FIG. 2B, so that the hydraulic oil in the cylinder upper chamber S1 flows from the communication hole 110 to the internal upper passage of the hollow piston holder 103. 103b and the internal passage 102a of the hollow rod 102 are discharged to the outside of the cylinder 101, and when the piston speed is in the medium and high speed range, the disc 1 is discharged from the notch 108a of the holder 108.
The inside of the valve 106 is bent downward through the oil passage 107a of 07 and flows into the in-cylinder lower chamber S2 through the oil passage 105 of the piston 104.

[0006]

As described above, in the conventional hydraulic shock absorber, the slide valve opens the communication hole at the time of expansion to secure the flow passage for the hydraulic oil in the upper chamber of the cylinder. At times, the slide valve completely closes the communication hole, so that the compression side damping force becomes large in a low piston speed region, and the initial compression operability is poor.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, an outer peripheral surface of a slide valve or an inner peripheral surface of a hollow rod communicates an upper chamber in a cylinder with a lower chamber in a cylinder at the time of compression, and a cylinder at the time of extension. Inner upper chamber and cylinder lower chamber
An orifice groove was formed in the axial direction to stop the communication.

[0008]

With the orifice groove formed in the outer peripheral surface of the slide valve or the inner peripheral surface of the hollow rod in the axial direction, the upper chamber and the lower chamber in the cylinder are communicated with each other at the time of compression. The initial compression operability is improved.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a half sectional view of a hydraulic shock absorber to which the present invention is applied, FIG. 2 is an enlarged sectional view of a portion A of FIG. 1 in a stationary state, and FIGS. 3 and 4 are compression sides of the portion A of FIG. 1, respectively. 1 and 2 are enlarged cross-sectional views showing different states in FIG.
FIG. 7 is an enlarged cross-sectional view showing a different state of the portion A on the extension side, FIG. 7 is a top view of the slide valve, and FIGS.
1 is an enlarged cross-sectional view showing a state on the compression side and the extension side of the B portion of FIG .
Reference numeral 0 is a sectional view of a main part of another embodiment, and FIG. 11 is a perspective view of the valve guide of FIG.

As shown in FIGS. 1 and 2, a damper 1 has a hollow rod 4 which is a piston rod inserted into a cylinder 2 from above via a rod guide 3 and the like, and a hollow piston is provided at the tip of the hollow rod 4. A holder 5 is attached, and a piston 6, a collar 7 and a holder 8 which are in sliding contact with the inner peripheral surface of the cylinder 2 are sandwiched and fixed between a retainer 9 and a nut 10 on the lower end side of the hollow piston holder 5. Piston 6
An oil passage 11 is formed in the
Also, the disk 13 is slidably fitted around the outer periphery of the collar 7, an oil passage 14 is formed in the disk 13, and the valve 12 and the disk 13 are springs interposed between the holder 8 and the upper surface of the disk 13. The piston 8 is urged by 15 and the holder 8 is formed with a notch 16.
Further, the piston 6 has a square hole 6 that bypasses the valve 12.
a is formed.

The hollow piston holder 5 is formed with a first communication hole 18 for communicating the cylinder upper chamber S1 defined by the piston 6 with the internal passage 4a of the hollow rod 4.
Internal upper passage 1 communicating with internal passage 4a of hollow rod 4
9 and an inner lower passage 20 having a diameter smaller than that of the inner upper passage 19
And the inner lower passage 20 is formed in the inner upper passage 19.
The stepped surface with the valve seat surface 21 is used as the first communication passage 18
A cylindrical slide valve 22 that opens and closes the valve is slidably inserted, and the valve seat 23 is provided above the slide valve 22.
Is fitted.

The slide valve 22 is a cylindrical poppet valve. As shown in FIG. 7, an outer peripheral surface of the slide valve 22 is formed with an orifice groove 22a axially connecting the cylinder upper chamber S1 and the lower chamber S2 during compression. The orifice groove 22a is formed outside the small diameter portion of the valve seat surface 21 (the inner peripheral surface of the inner lower passage 20). Further, the valve seat 23 fitted in the inner diameter hole of the hollow piston holder 5 has an upper part having a large diameter and a lower part having a small diameter, and the lower end part is a seat surface with which the upper end of the slide valve 22 abuts during compression.

Further, in FIG. 8, a hollow bottom piston holder 25 is fixed to the lower portion inside the cylinder 2, and a bottom piston 26 is provided at the upper end of the hollow bottom piston holder 25.
The collar 27 and the holder 28 are sandwiched and fixed between the step portion of the hollow bottom piston holder 25 and the retainer 29 and the nut 30. An oil passage 31 is provided in the bottom piston 26.
And the valve 32 and the disk 33 are slidably fitted on the upper surface of the bottom piston 26 on the outer periphery of the collar 27,
An oil passage 34 is formed in the disc 33, and these valves 3
2 and the disk 33 are attached to the bottom piston 26 by a spring 35 interposed between the holder 28 and the upper surface of the disk 33.
The holder 28 is formed with a notch 36.

A communication hole 37 is formed in the hollow bottom piston holder 25 so as to communicate with the internal passage 25a. The adjuster rod 38 is provided in the internal passage 25a to adjust the opening amount of the bypass passage formed by the internal passage 25a and the communication hole 37.
The needle 39 mounted so as to be able to move forward and backward is faced to the tip of the.

In FIG . 1, an outer case (outer tube) 40 is arranged on the outer circumference of a cylinder 2 of the damper 1, and a slide pipe (inner tube) 41 is slidably inserted into the outer case 40 from above. , A joint bolt 42 is attached to the upper end of the slide pipe 41 to attach the base end (upper end) of the hollow rod 4, and an oil lock piece 43 is attached to the outer peripheral surface of the cylinder 2.
On the inner peripheral surface of the lower end portion of the slide pipe 41, an oil lock collar 44 that fits into the oil lock piece 43 is fitted,
Further, a spring seat member 45 is attached to the upper end portion of the cylinder 2, and a suspension spring 46 is provided between the spring seat member 45 and the joint bolt 42.
Is installed.

A second communication hole 50 is formed in the upper part of the hollow rod 4 of the damper 1 so as to connect the upper air chamber 48 formed on the outer periphery of the cylinder 2 with the internal passage 4a. Second third for connecting the lower oil reservoir chamber 49 formed on the outer circumference with the lower chamber S2 in the cylinder
A communication hole 51 (see FIG. 8) is formed, and a communication hole 52 is formed in the spring seat 45.

[0017] To describe operation of the hydraulic shock absorber configured as above, when the downward piston 6 is shifted to the compression stroke from the quiescent state shown in FIG. 2, in the low speed range in the cylinder, as shown in FIG. 3 Since the hydraulic oil in the lower chamber S2 flows into the inner lower passage 20 of the hollow piston holder 5 and pushes up the slide valve 22, the first communication hole 18 and the hollow rod 4
The inner lower passage S2 of the hollow piston holder 5 and the outer peripheral surface of the slide valve 22 are closed because the lower end surface of the slide valve 22 is separated from the valve seat surface 21. Since it communicates with the in-cylinder upper chamber S1 via the orifice groove 22a and the first communication hole 18, the working oil in the in-cylinder lower chamber S2 flows into the in-cylinder upper chamber S1 through this flow path.

At this time, the oil passage 11 of the piston 6 does not resist the urging force of the spring 15 by the working hydraulic pressure, and therefore remains closed by the valve 12. Also, the piston 6
Since a square hole 6a that bypasses the valve 22 is formed in the cylinder, part of the hydraulic oil that has flowed into the oil passage 11 also flows into the cylinder upper chamber S1 through the square hole 6a, and the slide valve 22 With respect to the flow path of the orifice groove 22a, the square holes 6a are provided in parallel.

In the medium and high speed range, the working oil in the cylinder lower chamber S2 flows into the oil passage 11 of the piston 6 as shown in FIG. Since it is lifted against the force, the hydraulic oil that has flowed into the flow path 11 flows into the cylinder upper chamber S1 via the notch 16 of the holder 8.

Further, in the compression stroke, as shown in FIG. 8, the working oil corresponding to the entering volume of the hollow rod 4 (see FIG. 3) is
In the low speed region, the oil reservoir chamber 4 is passed through the communication hole 37 and the third communication hole 51 of the cylinder 2 from the internal passage 25a of the hollow bottom piston holder 25 according to the opening amount determined by the needle 39.
9 and in the medium and high speed range, it flows into the notch 36 of the holder 28 and bends the inner peripheral side of the valve 32 downward through the oil passage 34 of the disc 33 to open, and the oil of the bottom piston 26 is opened. The oil flows from the passage 31 into the oil reservoir 49 through the third communication hole 51.

On the other hand, when the piston 6 moves upward after shifting from the stationary state shown in FIG. 2 to the extension stroke, the lower end surface of the slide valve 22 becomes the valve seat surface 21 in the low speed range as shown in FIG. The first contact hole 18 and the inner passage 4a of the hollow rod 4 are communicated with each other by the contact with the orifice groove 22a and the first communication hole 18 and the hollow piston holder 5 inside the first communication hole 18. The air chamber 4 passes through the upper passage 19 and the inner passage 4a of the hollow rod 4, and further through the second communication hole 50 (see FIG. 1) of the hollow rod 4 .
8 into the oil reservoir 49 (see FIG. 1) .

At this time, the valve 12 is not opened by the working hydraulic pressure flowing into the oil passage 14 of the disk 13 from the cutout portion 16 of the holder 8. In addition, since the piston 6 is formed with a square hole 6a that bypasses the valve 22, a part of the hydraulic oil in the cylinder upper chamber S1 is part of the square hole 6a.
It flows into the cylinder lower chamber S2 from a through the oil passage 11.

Then, in the medium and high speed range, as shown in FIG. 6, the hydraulic oil in the cylinder upper chamber S1 is transferred to the cutout portion 16 of the holder 8.
To the oil passage 14 of the disk 13, the inner circumferential side of the valve 12 is bent downward to open, and then flows from the oil passage 11 of the piston 6 into the in-cylinder lower chamber S2.

Further, in the extension stroke, as shown in FIG. 9, the hydraulic oil corresponding to the withdrawal volume of the hollow rod 4 (see FIG. 5) is
In the low speed range, the oil flows from the oil reservoir 49 through the third communication hole 51 into the cylinder lower chamber S2 through the internal passage 25a of the hollow bottom piston holder 25 in accordance with the opening amount determined by the communication hole 37 and the needle 39. , In the medium and high speed range, the third
The fluid flows from the communication hole 51 into the oil passage 31 of the bottom piston 26 to push up the valve 32 and the disc 33 , and the holder 2
It flows into the in-cylinder lower chamber S2 via the notch portion 36 of 8.

The second communicating hole 50 of the hollow rod 4 in the above embodiment serves as a low speed orifice at the time of extension (first
The communication hole 18 may be a low-speed orifice) and serves to discharge the operating oil mixed with air bubbles in the cylinder. Further, a needle valve or the like is made to face the upper end opening of the valve seat 23 to form an extension side damping force adjusting mechanism. It can also be provided.

Next, in another embodiment shown in FIGS. 10 and 11 , the orifice groove 2 is formed on the outer periphery of the slide valve 22 of the above embodiment.
Instead of forming 2a, the upper and lower ring-shaped parts 5 as shown in FIG.
By inserting and inserting the valve guide 55 in which several column parts 55c are formed between 5a and 55b, and the slide valve 22 is slidably inserted into this valve guide 55, the internal upper passage 19 of the hollow piston holder 5 is formed. The orifice groove 22a is formed between the inner peripheral surface and the outer peripheral surface of the slide valve 22, and the same effect as the above embodiment can be obtained.

The present invention is not limited to the above-mentioned embodiment, and the hollow rod 4 and the hollow piston holder 5 are separate members in the above-mentioned embodiment, but it goes without saying that they may be one member. is there.

[0028]

As described above, according to the present invention,
Together when communicating the upper chamber and the cylinder lower chamber in the cylinder at the outer peripheral surface or compressed in the hollow rod peripheral surface of the slide valve
When extending, the communication between the upper chamber inside the cylinder and the lower chamber inside the cylinder
Since the orifice groove that stops is formed in the axial direction, the compression side damping force in the low speed range is reduced and the initial compression operability is improved.
Absorption of small uneven road surface improves and running performance improves,
When driving downhill on gravel roads, etc., the steering wheel will not be taken even if the front wheels hit the pebbles, improving steering stability,
When approaching a corner, the front wheel sinks slightly and cornering becomes easier.

[Brief description of drawings]

FIG. 1 is a half sectional view of a hydraulic shock absorber to which the present invention is applied.

FIG. 2 is an enlarged cross-sectional view of part A of FIG. 1 in a stationary state.

FIG. 3 is an enlarged cross-sectional view showing a state in the low speed region on the pressure side of the portion A in FIG.

FIG. 4 is an enlarged cross-sectional view showing a state in the medium and high speed region on the pressure side of part A in FIG.

FIG. 5 is an enlarged cross-sectional view showing a state in the low speed range on the extension side of the portion A in FIG.

FIG. 6 is an enlarged cross-sectional view showing a state in the medium-high speed region on the extension side of the portion A in FIG.

FIG. 7 is a top view of a slide valve.

8 is an enlarged cross-sectional view showing a state of the portion B in FIG. 1 on the pressure side.

FIG. 9 is an enlarged cross-sectional view showing a state of the portion B of FIG. 1 on the extension side.

FIG. 10 is a cross-sectional view of an essential part of another embodiment of the present invention.

Figure 11 is a perspective view of the valve guide of FIG. 10

FIG. 12 is an enlarged sectional view of a main part of a conventional hydraulic shock absorber in a different state.

[Explanation of symbols]

1 ... Damper, 2 ... Cylinder, 4 ... Hollow rod, 5 ... Hollow piston holder, 6 ... Piston, 7 ... Collar, 8 ... Holder, 11 ... Oil passage, 12 ... Valve, 13 ... Disc, 1
8 ... 1st communicating hole, 21 ... Valve seat surface, 22 ... Slide valve, 22a ... Orifice groove, 40 ... Outer case, 41 ... Slide pipe, 46 ... Suspension spring, 48 ... Air chamber, 49 ... Oil reservoir chamber, 50 … Second communication hole.

Claims (4)

(57) [Claims] 1. A slide pipe is slidably fitted in an outer case, and a single-cylinder damper is built in the outer case and the slide pipe, and an oil reservoir is provided outside a cylinder constituting the single-cylinder damper. And a piston attached to the tip of the hollow rod is slidably fitted to the inner peripheral surface of the cylinder, and this piston is used as an oil chamber above and below the piston.
The oil passage that connects the upper chamber in the cylinder and the lower chamber in the cylinder.
A damping force is generated in this oil passage as the piston slides.
A valve is provided, and the inside of the hollow rod serves as an internal passage that communicates the upper chamber in the cylinder and the oil reservoir chamber.The internal passage and the upper chamber in the cylinder communicate with each other through a communication hole. slidably opened during expansion between the inner passage and the communication hole bottom surface that is fitted is the cylindrical slide valve facing the chamber below the cylinder, during compression Te hydraulic shock absorber smell which to close, before Symbol slide When communicating the upper cylinder chamber and the cylinder lower chamber at the outer peripheral surface or compressed in the hollow rod peripheral surface of the valve
Both of them are connected to the upper chamber in the cylinder and the lower chamber in the cylinder during extension.
A hydraulic shock absorber characterized in that an orifice groove for stopping the passage is formed in the axial direction. 2. The hydraulic shock absorber according to claim 1,
A hydraulic shock absorber, wherein the tubular slide valve is a poppet valve. 3. The hydraulic shock absorber according to claim 1, wherein the lower end surface of the tubular slide valve is provided so as to be able to abut against a valve seat surface formed on the inner peripheral surface of the hollow rod, and -Shaped slide valve, the lower end surface of which separates from the valve seat surface to connect the upper chamber and the lower chamber in the cylinder to each other. 4. The hydraulic shock absorber according to claim 2 or 3, wherein the orifice groove formed on the outer circumference of the slide valve is formed outside a small diameter portion of a valve seat surface formed inside the hollow rod. And a hydraulic shock absorber.