JPH11218177A - Hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the function of check seal mechanism installed at the protruding end part of a piston rod of a hydraulic shock absorber, only by making simple improvement without making complicated alterations to the check seal mechanism. SOLUTION: Annular recesses 11, 12 are respectively formed on the inner peripheral side and outer peripheral side of a rod guide 6 for guiding a piston rod 5. The inner peripheral side annular recess 11 is communicated with a reservoir chamber R between an outer shell 2 and a cylinder 3 from a communicating port 13 through the outer peripheral side annular recess 12 and a drain port 14, and a check seal 15 opened toward the reservoir chamber R side is interposed inside the outer peripheral side annular recess 12. In a hydraulic shock absorber of such constitution, the relative position relation between the communicating port 13 communicating the inner and outer peripheral side annular recesses 11, 12 with each other, and the drain port 14 communicating the outer peripheral side annular recess 12 with the reservoir chamber R is arranged circumferentially shifted.

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 suspension device for a vehicle such as an automobile which elastically supports a vehicle body with respect to wheels, and more particularly, to a hydraulic shock absorber.
The present invention relates to a function improvement of a check seal in a rod guide portion of the hydraulic shock absorber.

[0002]

2. Description of the Related Art Conventionally, as this kind of hydraulic shock absorber, for example, one disclosed in Japanese Utility Model Registration No. 2540438, which was registered on April 18, 1997, is already known. .

[0003] In other words, in this device, annular recesses are formed on the inner peripheral side and outer peripheral side of a rod guide for guiding a piston rod, respectively, and these inner peripheral side and outer peripheral side annular recesses are sandwiched between a rod guide and an outer shell. The partition is covered with a rod seal holding plate that has been crimped.

The above-mentioned annular recess on the inner peripheral side is formed on the upper surface of the rod guide by being covered with the holding plate of the rod seal, and on the outer surface of the rod guide by being similarly covered by the inner wall surface of the outer shell. The drain port communicates with the reservoir chamber between the cylinder and the outer shell through the annular recess on the outer peripheral side.

[0005] A check seal that opens toward the reservoir chamber side is interposed in an annular concave portion on the outer peripheral side between the communication port and the drain port, and the check seal is pushed open so that the inner peripheral side of the rod guide is opened. The annular recess is intermittently connected to the reservoir chamber in accordance with the flow direction of the hydraulic oil.

Thus, at the time of extension of the hydraulic shock absorber, only a small part of the hydraulic oil is generated from the sliding contact gap between the rod guide and the piston rod by the hydraulic oil pressure generated in the oil chamber on the rod side. The fluid enters the annular recess, and flows from the communication port and the drain port to the reservoir chamber while pushing and opening the check seal through the annular recess on the outer peripheral side.

Thus, the sliding surface between the piston rod and the bearing provided on the rod guide is lubricated with hydraulic oil, and the annular recess on the inner peripheral side is filled with the hydraulic oil, so that the surface of the piston rod becomes an oil film. The lubrication between the rod seal and the sealing function is also maintained to secure the extension side damping characteristics.

On the other hand, when the hydraulic shock absorber performs a compressing operation, the hydraulic oil pressure in the oil chamber on the rod side tends to be a negative pressure, so that the gas in the upper portion of the reservoir chamber passes through the reverse path to that during the extending operation. Attempts to suck into the circumferential recess.

However, in this case, the check seal acts on the closing side to prevent the suction of the gas, so that the holding of the hydraulic oil in the annular concave portion on the inner peripheral side is ensured. The lubrication between the rod seals and the tightness of the rod seals are also maintained to ensure the compression-side damping characteristics.

[0010]

However, even so, the check seal provided on the rod guide must be opened and closed reliably with the expansion and contraction of the hydraulic shock absorber.
As described above, it is possible to secure the sealing function as the hydraulic shock absorber and to stabilize the damping characteristics.

For this purpose, when the hydraulic shock absorber extends, the check seal is easily opened due to an increase in the pressure in the oil chamber on the rod side to flow the hydraulic oil, or the hydraulic oil is easily attached to the check seal. Therefore, it is necessary to reliably prevent the suction of gas from the reservoir chamber in the closed state during the compression operation.

In this regard, in the above-described conventional hydraulic shock absorber, since the communication port and the drain port sandwiching the check seal are arranged side by side in phase, the check seal is extended from the communication port during the extension operation. Most of the hydraulic oil that has flowed by pushing open flows into the reservoir chamber through the drain port without changing its direction.

[0013] Therefore, the operating oil is liable to adhere only to the lip portion of the check seal in the vicinity corresponding to the inflow path of the operating oil, and the other lip portions of the check seal are not sufficiently adhered to the operating oil, and thus the lip portion is insufficient. Becomes

As a result, the operation of the hydraulic shock absorber is reversed and the operation shifts to the compression operation, and the effect of preventing suction of gas from the reservoir chamber when the oil chamber on the rod side becomes slightly negative and the check seal is closed. This is not enough, and the gas is mixed into the oil chamber on the rod side, which delays the rise of the extension side damping characteristic at the time of the next extension operation.

[0015] Further, since the drain port is formed in the vertical direction in parallel with the axis of the rod guide,
It is necessary to take some measures such as enlarging the opening area of the outlet end of the drain port so that the check seal can be easily and surely opened during the extension operation of the hydraulic shock absorber.

Accordingly, an object of the present invention is to provide a hydraulic shock absorber which can improve the function of the check seal by simply making a simple improvement to the check seal mechanism without causing a complicated check seal structure to be modified. It is to be.

[0017]

In order to achieve the above object, according to the present invention, a rod guide for guiding a piston rod is formed with annular recesses on the inner circumference and the outer circumference, respectively. The annular recess on the side communicates with the reservoir chamber between the cylinder and the outer shell through the annular recess and the drain port on the outer peripheral side from the communication port, and the annular recess on the outer peripheral side between the communication port and the drain port on the reservoir chamber side. In a hydraulic shock absorber equipped with a check seal that opens to the right, the relative positional relationship between the communication port that communicates the annular recess on the inner and outer circumferences and the drain port that communicates the annular recess on the outer circumference to the reservoir chamber is defined by the circumference. It was shifted in the direction.

Thus, when the hydraulic shock absorber extends, a part of the hydraulic oil in the oil chamber on the rod side enters the annular recess on the inner peripheral side from the sliding contact gap between the rod guide and the piston rod, and from there the communication port and The check seal is pushed open through the annular recess on the outer peripheral side by the drain port, and flows into the reservoir chamber.

At this time, in the process of pushing the check seal from the communication port to open to the drain port, the flow of the hydraulic oil does not go to the drain port without changing the direction from each of the communication ports. It flows toward the drain port while flowing along the circumferential direction in the annular recess on the outer peripheral side.

Accordingly, the operating oil spreads uniformly over the entire circumference of the lip of the check seal, and the oil chamber on the rod side becomes slightly under negative pressure as the hydraulic shock absorber shifts to the compression operation. The effect of preventing the suction of gas from the reservoir chamber when closed is improved.

In addition to or separately from the above, a drain port communicating the annular recess on the outer peripheral side with the reservoir chamber is formed obliquely with respect to the axis of the rod guide.

With this configuration, the opening area at the outlet end of the drain port can be easily enlarged and increased as compared with the passage area of the communication port without increasing the passage width and / or depth of the drain port. Can be taken.

As a result, the back pressure at the drain port is kept low to facilitate the opening operation of the check seal, and accordingly, the formation of an oil film on the surface of the piston rod is ensured to improve the lubricity between the rod seal and the sealing function. This will ensure that the desired extension side damping characteristics are always stable.

[0024]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a hydraulic shock absorber according to an embodiment of the present invention; Will be illustrated and described.

The hydraulic shock absorber 1 has a double-cylinder-type main body portion 4 consisting of a cylinder 3 arranged concentrically at a predetermined interval inside the outer shell 2.
A reservoir chamber R is formed between the cylinder and the cylinder 3.

A piston (not shown) provided with an extension-side damping valve and a compression-side suction valve is slidably fitted inside the cylinder 3. Further, between the bottom of the cylinder 3 and the reservoir chamber R, A base valve (not shown) having a compression damping valve and an extension suction valve is also provided.

From the piston, a piston rod 5 integrally extends upward, and the piston rod 5
Penetrates the oil chamber A on the rod side above the cylinder 3 defined by the piston, and the main body 4 of the hydraulic shock absorber 1
Extending upward from the outside.

A rod guide 6 for guiding a piston rod 5 from the outer shell 2 to the cylinder 3 and a piston rod extending upward from the main body 4 are provided inside the upper end of the main body 4 of the hydraulic shock absorber 1. Rod seals 7 for sealing the protrusions 5 in an oil-tight manner are provided.

The rod guide 6 is formed as a pressed product by folding the upper and lower ends of the cylindrical member outwardly and inwardly in a U-shape with a press machine, and by forming a reinforcing rib 8 together. The piston rod 5 is slidably guided by a bearing 9 mounted on the inner peripheral surface while being fitted to the upper end of the cylinder 3 and positioned at a predetermined position.

The rod seal 7 is attached to the inner peripheral portion of a perforated disk-shaped holding plate 10 by burning. The holding plate 10 is fitted from the upper end of the outer shell 2 to cover the rod guide 6 from above. The upper end of the outer shell 2 is crimped to fix the holding plate 10 together with the rod guide 6 so as to be positioned at a predetermined location.

In this manner, the annular concave portion 11 on the inner peripheral side is defined by the piston rod 5 and the holding plate 10 having the rod guide 6 and the rod seal 7 at the upper inner end of the main body portion 4. An outer peripheral annular recess 12 is defined between the outer shell 2 and the rod guide 6 by surrounding the annular recess 11.

The inner annular recess 11 and the outer annular recess 12 communicate with each other through a communication port 13 formed by recessing the upper surface of the rod guide 6 into a groove. The annular recess 12 on the outer peripheral side communicates with the reservoir chamber R through a drain port 14 formed by recessing the outer peripheral surface of the rod guide 6 in a groove shape.

In addition, inside the annular recess 12 on the outer peripheral side, a check seal 15 which opens from the communication port 13 toward the drain port 14 is provided with a holding plate 1 for the rod seal 7.
It is baked at 0 and installed.

In the above configuration, as can be seen from the plan view of FIG. 2 in which the rod guide 6 is viewed from above, in this embodiment, the communication port 13 which communicates the annular recesses 11 and 12 on the inner and outer peripheral sides. And the drain port 14 which communicates the annular recess 12 on the outer peripheral side with the reservoir chamber R as a set of four drain ports 14.

The connection port 13 and the drain port 14 do not necessarily have to be formed as a set of four pieces, but may be formed as a set of four or more pieces.
They may be made with a difference in the number of both.

Thus, the relative positional relationship between the communication port 13 and the drain port 14 is shifted in the circumferential direction, and if necessary, the drain port 14 is moved with respect to the axis of the rod guide 6 as shown in FIG. It was formed obliquely.

Thus, when the oil chamber A on the rod side is compressed by the piston in accordance with the extension operation of the hydraulic shock absorber 1, a part of the operating oil inside the piston rod 5 and the rod guide 6
And enters the annular recess 11 on the inner peripheral side through the sliding contact gap.

Then, the fluid flows from the communication port 13 and the drain port 14 to the reservoir chamber R between the outer shell 2 and the cylinder 3 while pushing and opening the check seal 15 through the annular recess 12 on the outer peripheral side.

At this time, in the process of pushing and opening the check seal 15 from the communication port 13 to the drain port 14, the flow of the hydraulic oil should be directed to the drain port 14 without changing the direction from the communication port 13. Instead, the fluid flows toward the drain port 14 while flowing along the circumferential direction in the annular recess 12 on the outer peripheral side.

As a result, the above-mentioned hydraulic oil uniformly adheres to the entire circumference of the lip of the check seal 15 and, along with the shift of the hydraulic shock absorber 1 to the compression operation, the oil chamber A on the rod side.
Has a negative pressure, and the effect of preventing the suction of gas from the reservoir chamber R when the check seal 15 is closed is improved.

In addition to or separately from the above, a drain port 14 for communicating the annular recess 12 on the outer peripheral side and the reservoir chamber R with each other is formed obliquely with respect to the axis of the rod guide 6.

With this configuration, the opening area at the outlet end of the drain port 14 can be easily made larger than the passage area of the communication port 13 without increasing the passage width and / or the depth of the drain port 14. It can be expanded and enlarged.

As a result, the back pressure at the drain port 14 is kept low to facilitate the opening operation of the check seal 15, and accordingly, the formation of an oil film on the surface of the piston rod 5 is ensured and the lubrication between the piston rod 5 and the rod seal 7 is achieved. Thus, it is possible to always maintain a stable expected extension-side damping characteristic while maintaining good performance and sealing function.

In the embodiment of FIG. 1 described above, the check seal 15 is attached to the holding plate 10 for holding the rod seal 7, and the check seal 1 is used.
5, the tip of the lip is brought into contact with the inner peripheral surface of the outer shell 2 for sealing.

However, instead of doing so, as shown in the embodiment of FIG. 4, the check seal 15a is baked against the rod guide 6 with the lip directed obliquely downward, and the tip of the lip of the check seal 15a is The inner shell of the outer shell 2 may be in contact with and sealed.

As shown in the embodiment of FIG. 5, the check seal 1 baked and attached to the rod guide 6 is provided.
It goes without saying that the lip of 5b may be applied to the holding plate 10 obliquely upward and sealed with the holding plate 10.

In particular, according to the embodiment shown in FIG. 5, the lip tip of the check seal 15b is guided by the inner wall surface of the outer shell 2 when the rod guide 6 is assembled. It will be easier.

[0048]

As described above, according to the first aspect of the present invention, the relative positional relationship between the communication port communicating the annular recess on the inner and outer circumferences and the drain port communicating the annular recess on the outer circumference to the reservoir chamber. Is shifted in the circumferential direction,
The check seal is pushed open from the communication port to circulate the flow of hydraulic oil toward the drain port inside the annular recess on the outer peripheral side, and the hydraulic oil spreads uniformly around the entire circumference of the lip of the check seal. The function of preventing the suction of gas from the chamber is improved, and thus the function of the check seal can be improved only by making a simple improvement to the check seal mechanism.

According to the second aspect of the present invention, a simple improvement is provided in which the drain port communicating the annular recess on the outer peripheral side and the reservoir chamber is formed obliquely inclined with respect to the axis of the rod guide. In this case, the drain port passage area is made larger than that of the communication port to keep the back pressure at the drain port low, thereby facilitating the opening operation of the check seal and forming the oil film on the piston rod surface. While ensuring the lubrication and the sealing function between the rod seal and the rod seal, it is possible to always secure a stable desired extension side damping characteristic.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional front view showing an embodiment of a check seal structure in an upper portion of a hydraulic shock absorber according to the present invention.

FIG. 2 is a plan view of only the rod guide taken out of the check seal structure and viewed from above.

FIG. 3 is a front view of the same rod guide as viewed from the front.

FIG. 4 is a partial vertical sectional front view showing another embodiment of the check seal structure according to the present invention.

FIG. 5 is a partial vertical sectional front view showing still another embodiment of the check seal structure according to the present invention.

[Explanation of symbols]

 A Oil chamber on the rod side R Reservoir chamber 1 Hydraulic shock absorber 2 Outer shell 3 Cylinder 5 Piston rod 6 Rod guide 7 Rod seal 9 Bearing 11 Inner circumferential annular recess 12 Outer circumferential annular recess 13 Communication port 14 Drain port 15 , 15a, 15b Check seal

Claims (2)

[Claims] An annular recess is formed on each of an inner peripheral side and an outer peripheral side of a rod guide for guiding a piston rod, and the inner peripheral side annular recess is formed from a communication port through an outer peripheral side annular recess and a drain port. In the hydraulic shock absorber that communicates with the reservoir chamber between the cylinder and the cylinder, and has a check seal that opens toward the reservoir chamber side in the annular recess on the outer peripheral side between the communication port and the drain port, A hydraulic shock absorber, wherein a relative positional relationship between a communication port communicating with the annular recess and a drain port communicating with the outer circumferential annular recess to the reservoir chamber is shifted in a circumferential direction. 2. A rod guide for guiding a piston rod, wherein annular recesses are respectively formed on the inner peripheral side and the outer peripheral side, and the inner peripheral side annular recess is passed from the communication port to the outer peripheral side annular recess and the drain port through the outer shell. In the hydraulic shock absorber that communicates with the reservoir chamber between the cylinder and the cylinder and that has a check seal that opens toward the reservoir chamber side in the annular recess on the outer peripheral side between the communication port and the drain port, A hydraulic shock absorber characterized in that a drain port communicating the recess and the reservoir chamber is formed obliquely with respect to the axis of the rod guide.