JP2003130119A - Friction-applying structure of hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber which applies friction to a piston rod, in which a stable friction is generated by preventing fractuation in pressure of an oil reservoir chamber for preventing running out of a oil film of an oil seal. SOLUTION: A friction-applying structure of a hydraulic shock absorber 10 comprises an oil reservoir chamber 40, formed in between an oil seal 16 and a friction member 20 which applies friction to a piston rob 14, a first communication path 41 which makes an oil chamber 13 communicate to the oil reservoir chamber 40, and a second communication path 42 which communicates reservoir 15 to the oil reservoir chamber 40. The first communication path 41 is provided with a first return check means 31, while a second communication path 42 is provided with a second return check means 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction imparting structure for a hydraulic shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a friction imparting structure of a hydraulic shock absorber, as described in JP-A-10-141415, a piston rod inserted into an oil chamber provided in a cylinder and a rod guide provided in an opening portion of the cylinder. And a friction member that guides the piston rod to the outside through the oil seal and applies friction to the piston rod is arranged between the rod guide and the oil seal, and an oil sump chamber is formed between the oil seal and the friction member. .

The friction member suppresses the movement of the piston rod in the extremely low speed range of the piston speed and the movement of the high frequency small amplitude generated in the piston rod after a large vibration during traveling on a rough road, so that the riding comfort of the vehicle is stable. And secure maneuverability. The oil sump chamber prevents the oil film from running off at the lip portion of the oil seal.

[0004]

In the prior art, the communication passage for communicating the oil reservoir with the reservoir provided in the oil chamber of the cylinder prevents the gas pressure of the reservoir from entering the oil reservoir. Although the check lip is provided as the check means, the check means is not provided in the communication passage that communicates the oil chamber of the cylinder with the oil sump chamber.

Therefore, when the piston rod moves in the extension direction, the oil in the oil chamber to be pressurized enters the oil sump chamber, and when the piston rod moves in the contraction direction, the oil in the oil sump chamber is depressurized. When it goes out to the oil chamber, the pressure fluctuation occurs in the oil sump chamber. The present inventor has found that this pressure fluctuation in the oil sump chamber changes the friction applied to the piston rod by the friction member due to the change in the back pressure acting on the friction member, and cannot provide stable friction. .

SUMMARY OF THE INVENTION An object of the present invention is to prevent pressure fluctuations in an oil sump chamber for preventing oil film breakage of an oil seal in a hydraulic shock absorber for imparting friction to a piston rod and to generate stable friction. .

[0007]

According to a first aspect of the present invention, a piston rod inserted into an oil chamber provided in a cylinder is led out to the outside via a rod guide and an oil seal provided in an opening of the cylinder. A friction member that imparts friction to the piston rod is disposed between the rod guide and the oil seal, an oil sump chamber is formed between the oil seal and the friction member, and the oil chamber of the cylinder communicates with the oil sump chamber. In the friction imparting structure of the hydraulic shock absorber, in which the communication passage and the second communication passage that communicates the oil reservoir with the reservoir additionally provided in the oil chamber of the cylinder are provided, the first check passage is provided in the first communication passage. At the same time, a second check means is provided in the second communication passage.

According to a second aspect of the present invention, in addition to the first aspect of the invention, the friction member is fixed in a state of being fitted in a recess provided in the rod guide, and the friction member is pressed toward the piston rod in a ring shape. It is equipped with a spring.

According to a third aspect of the present invention, in addition to the first or second aspect of the present invention, the friction member is made of a molded product obtained by baking a core metal with rubber.

According to a fourth aspect of the present invention, in addition to any one of the first to third aspects, the first check means is a check lip integrated with a friction member.

[0011]

According to the invention of claim 1, the following effects are obtained. When the piston rod moves in the contracting direction, the depressurized state of the oil chamber is prevented from acting on the oil sump chamber by the first check means, and the oil in the oil sump chamber is prevented from flowing out to the oil chamber. This prevents pressure fluctuations in the oil sump chamber.

According to the invention of claim 2, there is the following effect. The ring-shaped spring can prevent the friction member from being worn out and improve the durability of the friction member.

According to the invention of claim 3, there is the following action. The friction member can be fixed by pressing the core metal of the friction member into the rod guide. Moreover, the first communication passage can be formed by providing a groove in at least one of the rod guide and the cored bar.

According to the invention of claim 4, there is the following action. By forming the first check means by the check lip integrated with the friction member, the first check means can be easily provided.

[0015]

1 is a schematic view showing a hydraulic shock absorber according to a first embodiment, FIG. 2 is a sectional view showing a friction imparting structure, FIG. 3 is a schematic view showing various modes of friction members, and FIG. FIG. 5 is a cross-sectional view showing the rod guide, and FIG. 5 is a cross-sectional view showing the friction imparting structure of the second embodiment.

(First Embodiment) (FIGS. 1 to 4) FIG. 1 is a multi-cylinder hydraulic shock absorber 1 constituting a suspension.
0, and has a double tube structure in which the cylinder 12 is inserted in the outer tube 11.

The hydraulic shock absorber 10 guides the piston rod 14 inserted into the oil chamber 13 provided in the cylinder 12 to the outside through a rod guide 15 and an oil seal 16 provided at the opening of the cylinder 12.

The rod guide 15 has a small outer diameter portion on the lower end side fitted to the inner diameter of the cylinder 12, a large outer diameter portion on the upper end side fitted to the inner diameter of the outer tube 11, and an upper step portion of the small outer diameter portion of the cylinder 12. With the oil seal 16 placed on the upper end and placed on the upper surface thereof, the oil seal 16 and the washer 17 are fixed together with the caulking portion 18 at the upper end of the outer tube 11. The rod guide 15 has a bush 15A press-fitted therein, and slidably supports the piston rod 14.

The oil seal 16 is made of a molded product obtained by baking rubber on a core metal 16A, and has an oil seal lip 16B slidingly contacting the piston rod 14, a check lip 16C contacting the rod guide 15, and an outer peripheral lip contacting the outer tube 11. 16D, a dust seal lip 16E that is in sliding contact with the piston rod 14, and a ring-shaped spring 16F that presses the oil seal lip 16B and the dust seal lip 16E so as to press the lip 16B and 16E toward the piston rod 14.
With 6G.

In the hydraulic shock absorber 10, the lower end portion of the outer tube 11 is connected to the wheel side by a knuckle bracket, and the mounting bracket fixed to the upper end portion of the piston rod 14 is connected to the vehicle body side. A suspension spring is interposed between the provided spring seat and the spring seat provided on the upper end side of the piston rod 14, and the piston valve device and the base valve device are provided with the expansion and contraction vibration of the piston rod 14 due to the absorption of the impact force by the suspension spring. Vibration is suppressed by the generated damping force. The piston valve device is provided on the piston fixed to the insertion end of the piston rod 14 into the oil chamber 13, and along with the stretching vibration of the piston rod 14, the oil chamber 13 on one side of the piston and the oil chamber on the other side (not shown). The damping force is generated by the damping valve that is flexibly deformed by the flow of oil that moves between the two. The base valve device is provided between the oil chamber 13 and the reservoir 19 provided in the annular space between the outer tube 11 and the cylinder 12 so as to be incidental to the oil chamber 13 of the cylinder 12, and the piston rod 14 is provided. Along with the stretching vibration of the piston rod 1
The oil chamber 13 has a volume corresponding to the volume of 4 entering and leaving the cylinder 12.
A damping force is generated by a damping valve that is flexibly deformed by the flow of oil that moves between the reservoir 19 and the reservoir 19.

However, in the hydraulic shock absorber 10, the piston rod 14 in which the piston speed is extremely low and the damping force of the piston valve device and the base valve device is not generated.
Of the piston rod 14 and friction of the piston rod 14 in order to secure the stable riding comfort and maneuverability of the vehicle. A friction member 20 that imparts a resistance force is arranged between the rod guide 15 and the oil seal 16.

The friction member 20, as shown in FIGS. 2 and 3,
A back surface of a friction-applying lip 22A that is made of a cored bar 21 and a rubber 22 that is baked, and that provides friction to the piston rod 14 by slidingly contacting the piston rod 14, a check lip 22B that abuts on the rod guide 15, and a frictional application lip 22A. On the side, an annular space 23 formed between the core metal 21 and the core metal 21 is provided. The friction member 20 is positioned and fixed in a recess 30 provided in the rod guide 15 in a fitted state in which the cored bar 21 is press-fitted. In the present embodiment, the friction imparting lip 22
A has a rounded surface in sliding contact with the piston rod 14 and is not expected to have an oil seal function for the piston rod 14, but has a friction imparting function for the piston rod 14.

The hydraulic shock absorber 10 has an oil sump chamber 40 formed between the oil seal 16 in which the piston rod 14 is inserted and the friction member 20, and the oil chamber 13 of the cylinder 12 inside the rod guide 15 (bush 15A). A first communication passage 41 that communicates with the oil sump chamber 40 via the peripheral portion and a second communication passage 42 that communicates the oil sump chamber 40 with the reservoir 19 are provided. The first communication passage 41 is formed by the grooves 41A and 41B provided in the rod guide 15, and the second communication passage 42 is formed by the grooves 42A and 42B provided in the rod guide 15 (FIG. 4).

Further, the hydraulic shock absorber 10 includes the first communication passage 41.
The first check means 31 is provided on the second communication passage 42.
The second non-return means 32 is provided. In this embodiment, the first check means 31 is formed by the check lip 22B integrated with the friction member 20, and the second check means 32 is formed by the check lip 16C integrated with the oil seal 16. The first non-return means 31 (check lip 22B) allows the flow of oil from the oil chamber 13 to the oil sump chamber 40, and the decompression of the oil chamber 13 when the piston rod 14 contracts affects the oil sump chamber 40. Block. The second check means 32 (check lip 16C) allows the surplus oil in the oil sump chamber 40 to flow out to the reservoir 19, and prevents the gas pressure of the reservoir 19 from reaching the oil sump chamber 40. As a result, the oil chamber 1
The oil of No. 3 enters the oil sump chamber 40 from the first communication passage 41, and
A one-way oil flow is formed from the communication passage 42 to the reservoir 19, and the oil reservoir chamber 40 is constantly filled with oil so that the oil pressure is exerted on the oil seal 16 and the friction member 20. The oil seal lip 16B of the oil seal 16 is constantly wet by the oil with which the oil sump chamber 40 is filled to prevent the oil film from being broken, and the tension of the ring-shaped spring 16F and the oil sump chamber 4
By backing up the hydraulic pressure of 0, the piston rod 14 is pressed against and the oil is sealed. Further, the friction applying lip 22A of the friction member 20 presses against the piston rod 14 due to its own elastic behavior and backup of the hydraulic pressure of the oil reservoir 40 to apply friction to the piston rod 14.

According to this embodiment, there are the following effects. A first check means 31 (check lip 22B) is provided in a first communication passage 41 between the oil storage chamber 40 and the oil chamber 13, and a second check means is provided in a second communication passage 42 between the oil storage chamber 40 and the reservoir 19. 32 (check lip 16C) is provided to form a one-way oil flow in which the oil in the oil chamber 13 enters the oil sump chamber 40 and exits to the reservoir 19. Therefore, when the piston rod 14 moves in the extending direction, the oil in the oil chamber 13 to be pressurized opens the first check means 31 and enters the oil sump chamber 40, and the surplus oil in the oil sump chamber 40 becomes 2 Open the non-return means 32 to flow out to the reservoir 19. Further, when the piston rod 14 moves in the contracting direction, the depressurized state of the oil chamber 13 is changed to the oil sump chamber 4
The action of 0 is blocked by the first check means 31,
It is possible to prevent the oil in the oil sump chamber 40 from flowing out to the oil chamber 13, and prevent the pressure fluctuation in the oil sump chamber 40.

As a result, the change in the back pressure exerted by the oil in the oil reservoir 40 on the friction member 20 is suppressed, and a stable and constant friction is applied to the piston rod 14 by the friction member 20, so that the piston rod 14 in the extremely low speed range is provided. It is possible to suppress the movement and the movement of the piston rod 14 having a high frequency and a small amplitude to secure the stability of riding comfort and maneuverability. Further, the oil in the oil sump chamber 40 always surely immerses the oil seal lip 16B of the oil seal 16 so that the oil film of the oil seal 16 can be stably prevented from running out.

The friction member 20 can be fixed by pressing the core metal 21 of the friction member 20 into the rod guide 15. Further, the first communication passage 41 can be formed by providing the grooves 41A and 41B in at least one of the rod guide 15 and the cored bar 21.

By constructing the first check means 31 by the checklist 22B integrated with the friction member 20, the first check means 31 can be easily provided.

By constructing the second check means 32 by the check lip 16C integrated with the oil seal 16, the second check means 32 can be easily provided.

The friction member 20 has a friction applying lip 22.
Since A is brought into sliding contact with the piston rod 14 on the rounded surface, it has a friction imparting function to the piston rod 14 and can improve durability. However, the friction member 20 has a friction applying lip 22 as shown in FIG.
A may be brought into sliding contact with the piston rod 14 on the V projection surface, and may have both a friction imparting function for the piston rod 14 and an oil seal function. Also,
As shown in FIG. 3 (C), the friction member 20 may be one in which the friction applying lip 22A is in sliding contact with the piston rod 14 on a flat surface.

Further, the friction member 20 includes the friction applying lip 2
Since the annular space 23 is provided on the back side of 2A, the followability of the friction imparting lip 22A with respect to the swing of the piston rod 14 can be improved, the durability can be improved, and friction can be stably generated. However, the friction member 29 may not include the annular space 23 on the back surface side of the friction imparting lip 22A as shown in FIG. 3 (D).

(Second Embodiment) (FIG. 5) The difference between the second embodiment and the first embodiment is that the friction member 2
This is because a ring-shaped spring 25 for pressing the friction imparting lip 22A of 0 toward the piston rod 14 is added. The ring-shaped spring 25 is tightly attached inside the annular space 23 to a ring-shaped groove portion provided on the outer periphery on the back side of the friction imparting lip 22A.

According to the second embodiment, the ring-shaped spring 25 prevents the friction member 20 from being settled, improves the durability of the friction member 20, and secures the friction exerted on the piston rod 14 for a long period of time.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and the design can be changed without departing from the gist of the present invention. Etc. are included in the present invention. For example, the first communication passage of the present invention may be formed on the side of the friction member,
For example, it may be formed by a groove provided in the core metal of the friction member.

Incidentally, in FIG. 2 and FIG. 5, the oil seal 1
The oil seal lip 16B of No. 6 and the friction applying lip 22A of the friction member 20 are in a free state, and are actually in an elastically deformed state in contact with the outer circumference of the piston rod 14.

[0036]

As described above, according to the present invention, in the hydraulic shock absorber for imparting friction to the piston rod,
It is possible to prevent pressure fluctuations in the oil sump chamber for preventing oil film breakage of the oil seal, and to generate stable friction.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a hydraulic shock absorber according to a first embodiment.

FIG. 2 is a cross-sectional view showing a friction imparting structure.

FIG. 3 is a schematic view showing various modes of a friction member.

FIG. 4 is a cross-sectional view showing a rod guide.

FIG. 5 is a cross-sectional view showing a friction imparting structure of a second embodiment.

[Explanation of symbols]

10 hydraulic shock absorber 12 cylinders 13 oil chamber 14 Piston rod 15 Rod guide 16 oil seal 16C check lip (second check means) 19 reservoir 20 Friction member 21 core 22 rubber 22A Friction imparting lip 22B check lip (first non-return means) 24 ring spring 30 recess 31 First check means 32 Second check means 40 oil sump chamber 41 First communication passage 42 Second passage

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Noriaki Maneyama             1-14 Fujiwara-cho, Gyoda-shi, Saitama 1 Stock             Company Showa Saitama Head Office Factory F term (reference) 3J069 AA54 CC18 CC19 DD02 DD07

Claims (4)

[Claims] 1. A friction member for guiding a piston rod inserted into an oil chamber provided in a cylinder to the outside via a rod guide and an oil seal provided in an opening of the cylinder to provide friction to the piston rod,
It is arranged between the rod guide and the oil seal, and forms an oil reservoir between the oil seal and the friction member. The first communication passage that connects the oil chamber of the cylinder to the oil reservoir and the oil chamber of the cylinder are incidental. In a friction imparting structure of a hydraulic shock absorber having a second communication passage for communicating an oil reservoir with a reservoir provided in the first communication passage, a first check means is provided in the first communication passage and a second check passage is provided in the second communication passage. A friction applying structure for a hydraulic shock absorber, characterized in that means is provided. 2. The hydraulic shock absorber according to claim 1, further comprising a ring-shaped spring that fixes the friction member in a state where the friction member is fitted in a recess provided in the rod guide, and presses the friction member toward the piston rod. Friction imparting structure. 3. The friction imparting structure for a hydraulic shock absorber according to claim 1, wherein the friction member is made of a molded product obtained by baking rubber on a core metal. 4. The friction imparting structure for a hydraulic shock absorber according to claim 1, wherein the first check means is a check lip integrated with a friction member.