JP2003156093A - Friction applying structure for hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the air venting performance from an oil sump for preventing the loss of an oil film of an oil seal in a hydraulic shock absorber applying friction to a piston rod for generating a stable friction and stable damping force. SOLUTION: In the friction applying structure of this hydraulic shock absorber 10 provided with the oil sump 40 formed between a friction member 20 for applying friction to the piston rod 14 and the oil seal 16, an inflow passage 50 communicating an oil chamber 13 with the oil sump 40, and an outflow passage 60 communicating the oil reservoir chamber 40 with a reservoir 19, the inflow passage 50 comprises a first flow passage 51, a circular flow passage 52 and a second flow passage 53. The first flow passage 51 and the second flow passage 53 are disposed alternately against the circular flow passage 52.

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]

[Prior Art] Conventionally, as a hydraulic shock absorber, actual Kaihei 1-7874
As described in No. 3, the piston rod inserted into the oil chamber provided in the cylinder is led out to the outside via the rod guide and oil seal provided in the opening of the cylinder, and the sub seal is placed between the rod guide and the oil seal. There is an oil reservoir formed between the oil seal and the sub seal.

The sub-seal protects the oil seal and has a structure that generates a certain amount of frictional resistance. Further, the oil sump chamber prevents the oil film from running off at the lip portion of the oil seal.

[0004]

The prior art has the following problems. There is no way to let air easily escape to the inflow passage that connects the oil chamber of the cylinder to the oil sump chamber, and there is no outflow passage that connects the oil reservoir chamber to the reservoir at the top of the oil sump chamber. May remain.

When air remains in the oil sump chamber, the pressure of the oil sump chamber is likely to change due to the expansion of air due to heat, and the back pressure acting on the sub-seal changes, so that the friction given to the piston rod by the sub-seal is generated. It fluctuates and the damping force also changes.

When air remains in the oil sump chamber, the residual air in the oil sump chamber is crushed when the oil chamber of the cylinder is pressurized, which affects the operation of the damping force generator and cannot generate a stable damping force.

When air remains in the oil sump chamber, the expansion of the air pushes the oil into the reservoir, reducing the amount of oil in the oil sump chamber and causing the oil seal to run out of oil.

An object of the present invention is to improve the air bleeding property from 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. And to generate a stable damping force.

[0009]

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 gives friction to the piston rod is arranged between the rod guide and the oil seal, an oil sump chamber is formed between the oil seal and the friction member, and an inflow passage that connects the oil chamber of the cylinder to the oil sump chamber. In the friction imparting structure of the hydraulic shock absorber in which the reservoir provided additionally to the oil chamber of the cylinder is provided with the outflow passage communicating with the oil reservoir, the inflow passage is provided in the lower portion of the oil reservoir, and A first flow passage provided on the oil chamber side, a second flow passage provided on the oil reservoir chamber side, and an annular flow passage connecting the first flow passage and the second flow passage. The second channel is different from the annular channel Disposed, the outlet channel is obtained by the so provided above the oil reservoir.

According to a second aspect of the present invention, in addition to the first aspect, the first flow path is provided at two positions forming 180 degrees along the annular flow path, and the second flow path is also an annular flow path. Along 18
The first flow path and the second flow path, which are provided at two positions that form 0 degree and are adjacent to each other along the annular flow path, are arranged alternately at 90 degrees apart from each other along the annular flow path.

According to a third aspect of the present invention, in addition to the first or second aspect of the invention, inflow check means is provided in the inflow path, and outflow check means is provided in the outflow path.

According to a fourth aspect of the invention, in addition to the third aspect of the invention, the inflow check means comprises a check lip integrated with a friction member, and the check lip is arranged in the annular flow path. .

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, at least one of the first flow passage and the second flow passage is an orifice, and the orifice is a gap between the rod guide and the piston rod. This is an orifice having a smaller flow passage cross-sectional area.

[0014]

According to the invention of claim 1, the following effects are obtained. An inflow passage that connects the oil chamber of the cylinder to the oil reservoir is provided in the lower portion of the oil reservoir, and the oil and air that have passed through the rod guide from the oil chamber of the cylinder flow from the first passage to the annular passage,
It flows into the oil sump chamber via the second flow path. At this time, since the first flow path and the second flow path are alternately arranged with respect to the annular flow path, the oil that has entered the annular flow path from the first flow path is along the annular circumferential direction of the annular flow path. The flow splits in both directions and the second
The air flows out of the flow passage into the oil sump chamber, and the air that has entered the annular flow passage is pushed into the oil sump chamber by the flow of the oil without being accumulated in the middle of the annular flow passage.

Further, since the outflow passage that connects the oil sump chamber to the reservoir is provided in the upper part of the oil sump chamber, the air flowing into the reservoir through the outflow passage from the oil sump chamber And discharge it to the reservoir.

Therefore, the air bleeding property from the oil sump chamber is improved, and air is not left in the oil sump chamber.

Since no air remains in the oil sump chamber, pressure fluctuations in the oil sump chamber due to expansion of air due to heat are suppressed,
By making the back pressure acting on the friction member constant, it is possible to stabilize the friction applied to the piston rod by the friction member.

Since no air remains in the oil sump chamber, when the oil chamber of the cylinder is pressurized, it is not affected by the residual air in the oil sump chamber, and the operation of the damping force generator is stabilized and stabilized. A damping force can be generated.

Therefore, the vibration is damped by friction in the extremely low speed range, and the damping force is surely generated from the very low speed range, whereby the shock absorbing function of the hydraulic shock absorber can be stabilized and ensured.

Since no air remains in the oil sump chamber, the oil is not pushed out to the reservoir by the expansion of the air, the amount of oil in the oil sump chamber is maintained, and the oil causes the oil film to run out of the lip portion of the oil seal. There is no.

According to the second aspect of the present invention, there are the following effects. Since each of the first flow path and the second flow path forming the inflow path are provided in twos, the efficiency of air bleeding can be improved.

According to the invention of claim 3, there is the following action. When the piston rod moves in the contracting direction, the inflow check means prevents the depressurized state of the oil chamber of the cylinder from acting on the oil reservoir, and the oil in the oil reservoir goes out to the oil chamber of the cylinder. Can be prevented, and pressure fluctuations in the oil sump chamber can be prevented.

Therefore, the back pressure acting on the friction member can be made constant, and the friction applied to the piston rod by the friction member can be stabilized.

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

According to the invention of claim 5, there is the following action. When the rod guide is molded with a sintered material, for example, it has relatively high accuracy, but there are manufacturing tolerances, guide bushes have tolerances, and piston rods have tolerances, so the maximum tolerance between the guide bush and piston rod is And there is a case where the tolerance becomes maximum, and when the tolerance is maximum and minimum, there is a change in the pressure increase in the oil chamber on the rod side of the cylinder,
Especially when the piston speed is slow, the generation of damping force is affected. At this time, at least one of the first flow path and the second flow path is used as an orifice, and the orifice has a flow path cross-sectional area smaller than the gap between the rod guide and the piston rod. It is possible to suppress the variation of the damping force due to the manufacturing tolerance of the rod guide and the piston rod. For example, manufacturing tolerance of rod guide and piston rod is 1.4m
m ² 0.4 mm ² when the equivalent, by setting an orifice 0.4 mm ^2, it is possible to suppress the variation of damping force due to manufacturing tolerances.

[0026]

1 is a schematic view showing a hydraulic shock absorber,
2 is a sectional view showing the friction imparting structure, FIG. 3 is a plan view showing the rod guide, FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, FIG. 5 is a perspective view showing the rod guide, and FIG. 6 is friction. It is a schematic diagram which shows various aspects of a member.

FIG. 1 shows a double-cylinder type hydraulic shock absorber 10 which constitutes a suspension, and has a double pipe structure in which a cylinder 12 is inserted in an 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 stepped 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 is press-fitted with a guide bush 15A, 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 of the outer tube 11 is connected to the wheel side by a knuckle bracket, and the mounting bracket fixed to the upper end 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 expansion and contraction vibration of the piston rod 14, the piston rod side oil chamber 13 on one side of the piston and the piston side on the other side. A damping force is generated by a damping valve that is flexibly deformed by the flow of oil moving between oil chambers (not shown). The base valve device is an oil chamber 13 of the cylinder 12.
2 is provided between the oil chamber 13 and a reservoir 19 provided in the annular space between the outer tube 11 and the cylinder 12, and the piston rod 14 is expanded and contracted by the piston rod 14 due to the expansion and contraction vibration of the piston rod 14. A damping force is generated by a damping valve that is flexibly deformed by the flow of oil that moves between the oil chamber 13 and the reservoir 19 by the volume that enters and leaves 12.

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 6,
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.

Incidentally, in this embodiment, a ring-shaped spring 25 for pressing the friction imparting lip 22A of the friction member 20 toward the piston rod 14 is added. The ring-shaped spring 25 is provided inside the annular space 23 so that the friction imparting lip 2
2A is tightly attached to a ring-shaped groove provided on the outer periphery on the back side. The ring-shaped spring 25 prevents the friction member 20 from being worn out, improves the durability of the friction member 20, and ensures the long-term stability of the friction exerted on the piston rod 14. However, the friction member 20 is the ring-shaped spring 2
It is not essential to have 5.

The hydraulic shock absorber 10 forms an oil sump chamber 40 between the oil seal 16 in which the piston rod 14 is inserted and the friction member 20, and connects the oil chamber 13 of the cylinder 12 to the piston of the rod guide 15 (bush 15A). The inflow path 5 communicating with the oil sump chamber 40 via the inner peripheral portion with which the rod 14 slides
0 and the outflow passage 6 that connects the oil reservoir chamber 40 to the reservoir 19
0 is set. The oil sump chamber 40 is formed between the friction member 20 press-fitted into the recess 30 of the rod guide 15 and the oil seal 16 provided on the upper surface of the rod guide 15, and has an upward tapered inner circumference that is continuous with the recess 30 of the rod guide 15. Face 31
(In the present specification, the vertical direction of the taper and the gradient refers to the vertical direction as viewed in the oil flow direction), and the vertical inner peripheral surface 32 is formed so as to surround the piston rod 14.

The inflow passage 50 is formed in the recess 30 of the rod guide 15 as shown in FIGS.
Is provided at the bottom of the. The outflow passage 60 is connected to the rod guide 15
Is engraved on the upper surface side of the oil reservoir and is provided on the upper portion of the oil sump chamber 40.

The inflow passage 50 is provided on the oil chamber 13 side of the cylinder 12, and has a groove-like first flow passage 51 that opens above the inner peripheral portion of the rod guide 15 (bush 15A) with which the piston rod 14 is in sliding contact. And is provided on the oil sump chamber 40 side,
It is composed of a groove-shaped second flow path 53 that opens into the oil sump chamber 40, and an annular flow path 52 that connects the first flow path 51 and the second flow path 53 and that is continuous over the entire circumference of the rod guide 15 in the circumferential direction. . The first flow path 51 and the second flow path 52 are engraved on the bottom surface of the recess 30 of the rod guide 15, and the second flow path 53 is a vertical surface of the recess 30 of the rod guide 15 (the core metal 21 of the friction member 20 is press-fitted). Vertical surface). The annular flow path 52 includes a downward slope surface 52A on the inner circumference where the first flow path 51 communicates.

The inflow path 50 includes a first flow path 51 and a second flow path 5.
3 are staggered in the circumferential direction of the annular flow path 52. In the present embodiment, the first flow path 51 is provided at two positions forming 180 degrees along the circumferential direction of the annular flow path 52, and the second flow path 53 is also set at 180 degrees along the circumferential direction of the annular flow path 52. Eggplant 2
The first flow path 51 and the second flow path 53, which are provided at positions and are adjacent to each other along the circumferential direction of the annular flow path 52, are arranged alternately with each other at 90 degrees apart along the circumferential direction of the annular flow path 52. .

The outflow passage 60 is formed in the upper surface on the inner peripheral side of the rod guide 15 and communicates with the uppermost space of the oil sump chamber 40 (located above the oil seal lip 16B of the oil seal 16). 61, a grooved channel 62 having a downward slope formed in the upper end surface of the rod guide 15 on which the core metal 16A of the oil seal 16 is mounted, and an outer peripheral side upper surface of the rod guide 15 surrounded by the outer tube 11. The formed annular flow passage 63 and the outer tube 1 of the rod guide 15
1 and a cutout-shaped flow path 64 that is formed in a cutout on the outer peripheral surface and opens to the reservoir 19. The oil reservoir chamber 40 is formed into an annular flow path 61, a groove-shaped flow path 62, an annular flow path 63, and a cutout shape. It communicates with the reservoir 19 via the flow path 64. The annular flow path 61 has an upslope surface 61A on the inner circumference facing the oil sump chamber 40, and an upslope surface 61B on the outer circumference to which the groove-like flow path 62 is connected.
Equipped with. The annular flow passage 63 is provided with a descending slope surface 63A on the inner circumference to which the groove-like flow passage 62 is connected.

In the outflow passage 60, the groove-like flow passages 62 and the notch-like flow passages 64 are arranged alternately in the circumferential direction of the annular flow passage 63. In this embodiment, the groove-shaped channel 62 is the annular channel 63.
Are provided at two positions that make 180 degrees along the circumferential direction of the annular flow path 63, and the notched flow channels 64 are also provided at two positions that make 180 degrees along the circumferential direction of the annular flow path 63. The groove-shaped flow passages 62 and the notch-shaped flow passages 64 that are adjacent to each other along the circumferential direction of the annular flow passage 63 are arranged at 90 degrees apart from each other.

Further, in this embodiment, the second passage 53 and the outflow passage 60 of the inflow passage 50 which are adjacent to each other along the circumferential direction of the annular flow passage 61 with the oil sump chamber 40 and the annular flow passage 61 sandwiched therebetween. The groove-shaped flow paths 62 are arranged alternately along the circumferential direction of the annular flow path 61 and are spaced apart by 90 degrees.

Further, in the hydraulic shock absorber 10, the inflow passage 50 is provided with the inflow check means 71, and the outflow passage 60 is provided with the outflow check means 72. In the present embodiment, the check lip 2 in which the inflow check means 71 is integrated with the friction member 20.
2B, and the outflow check means 72 is formed by the check lip 16C integrated with the oil seal 16. The inflow check means 71 (check lip 22B) is arranged so as to contact the entire circumference of the annular flow path 52 of the inflow passage 50, and allows the oil in the oil chamber 13 to enter the oil reservoir chamber 40 from the inflow passage 50. However, the pressure reduction of the oil chamber 13 when the piston rod 14 is contracted is prevented from reaching the oil sump chamber 40. The outflow check means 72 (check lip 16C) is the outflow passage 6
0 is arranged so as to come into contact with the entire circumference of the annular flow passage 61, and an excess amount of oil in the oil sump chamber 40 is discharged from the outflow passage 60 to the reservoir 19.
To prevent the gas pressure of the reservoir 19 from reaching the oil sump chamber 40.

Therefore, the flow of oil from the oil chamber 13 of the cylinder 12 to the reservoir 19 is as follows.

(1) The oil in the oil chamber 13 passes through the gap between the bush 15A of the rod guide 15 and the piston rod 14,
Through the first flow path 51 on the lower side of the friction member 20, the inflow check means 71 (check lip 22B) is pushed open to pass through the annular flow path 52, and through the second flow path 53 on the outer circumference of the friction member 20. It flows into the lower part of the oil sump chamber 40. At this time, since the first flow path 51 and the second flow path 53 are alternately arranged in the circumferential direction of the annular flow path 52, the first flow path 51 to the annular flow path 52
The oil that has entered becomes a flow that branches in both directions along the circumferential direction of the annular flow path 52 and escapes from the second flow path 53 to the oil sump chamber 40.

(2) Excess oil in the oil sump chamber 40 is stored in the oil sump chamber 4
0 at the top of 0, the annular flow path 61 below the oil seal 16
Checking means 72 (check lip 16C) for outflow
To open from the groove-shaped channel 62 to the annular channel 63,
Further, from the annular flow path 63 through the cutout flow path 64, the reservoir 1
It is discharged to 9.

As a result, the oil in the oil chamber 13 enters the oil sump chamber 40 from the inflow path 50 and forms a one-way oil flow that exits from the outflow path 60 to the reservoir 19, and the oil sump chamber 40 is constantly filled with oil. The oil pressure is filled and the hydraulic pressure is applied to the oil seal 16 and the friction member 2.
Affect 0. Oil seal lip 1 of oil seal 16
6B is constantly wetted by the oil filled in the oil sump chamber 40 to prevent the oil film from being broken, and is pressed against the piston rod 14 by the tightening force of the ring-shaped spring 16F and the hydraulic pressure of the oil sump chamber 40 to make an oil seal. To do. Also,
The friction applying lip 22 </ b> A of the friction member 20 presses against the piston rod 14 due to its own elastic behavior and the backup of the oil pressure in the oil reservoir 40 to apply friction to the piston rod 14.

Further, in the hydraulic shock absorber 10, at least one of the first flow path 51 and the second flow path 53 (the second flow path 53 in the present embodiment) of the inflow path 50 is the orifice 80, and the orifice 80 The bush 15 of the rod guide 15
Smaller flow passage cross-sectional area than the gap between A and piston rod 14 (2
The orifice of the total flow passage cross-sectional area of each second flow passage 53 is used. As a result, variations in the clearance between the piston rod 14 and the rod guide 15 (bush 15A) due to manufacturing tolerances are suppressed, and the generation of damping force by the piston valve device and the base valve device described above is stabilized.

According to this embodiment, there are the following effects. An inflow path 50 that connects the oil chamber 13 of the cylinder 12 to the oil sump chamber 40 is provided in the lower portion of the oil sump chamber 40, and the oil and air that have passed through the rod guide 15 from the oil chamber 13 of the cylinder 12 are the first Channel 51 to annular channel 52, second channel 5
After passing through 3, the oil flows into the oil sump chamber 40. At this time, since the first flow channel 51 and the second flow channel 53 are arranged alternately with respect to the annular flow channel 52, the oil that has entered the annular flow channel 52 from the first flow channel 51 is stored in the annular flow channel 52. A flow that branches in both directions along the annular circumferential direction and comes out of the second flow path 53 into the oil sump chamber 40, and retains the air that has entered the annular flow path 52 in the middle of the annular flow path 52. Instead, it is pushed into the oil sump chamber 40 by the flow of the oil.

Further, since the outflow passage 60 that connects the oil sump chamber 40 to the reservoir 19 is provided above the oil sump chamber 40, the air that has entered the oil sump chamber 40 flows out from the oil sump chamber 40 into the outflow passage 6.
After passing through 0, the oil is discharged to the reservoir 19 along with the flow of oil flowing out to the reservoir 19.

Therefore, the air bleeding property from the oil sump chamber 40 is improved, and air is not left in the oil sump chamber 40.

Since no air remains in the oil sump chamber 40, the pressure fluctuation in the oil sump chamber 40 due to the expansion of the air due to heat is suppressed, the back pressure acting on the friction member 20 is made constant, and the friction member 20 causes the piston to move. It is possible to stabilize the friction applied to the rod 14.

Since no air remains in the oil sump chamber 40, when the oil chamber 13 of the cylinder 12 is pressurized, it is not affected by the residual air in the oil sump chamber 40, and the damping force generator (piston valve device, It is possible to stabilize the operation of the base valve device) and generate a stable damping force.

Therefore, the vibration is damped by friction in the extremely low speed range, and the damping force is surely generated from the very low speed range, whereby the shock absorbing function of the hydraulic shock absorber 10 can be stabilized and ensured.

Since no air remains in the oil sump chamber 40, the oil is not pushed out to the reservoir 19 by the expansion of the air, the amount of oil in the oil sump chamber 40 is maintained, and the oil seal lip 16B of the oil seal 16 is filled with oil. It does not cause the oil film to run out.

Since each of the first flow path 51 and the second flow path 53 forming the inflow path 50 is provided, the efficiency of air bleeding can be improved.

When the piston rod 14 moves in the contracting direction, the depressurized state of the oil chamber 13 of the cylinder 12 is prevented from acting on the oil sump chamber 40 by the inflow check means 71, and the oil in the oil sump chamber 40 is removed. It is possible to prevent the cylinder 12 from going out to the oil chamber 13 and prevent the pressure fluctuation in the oil reservoir chamber 40.

Therefore, the back pressure acting on the friction member 20 can be made constant, and the friction applied to the piston rod 14 by the friction member 20 can be stabilized.

The check lip 22B integrated with the friction member 20 constitutes the inflow check means 71, so that the inflow check means 71 can be easily provided.

The rod guide 15 is made of, for example, a sintered material.
Since it is shaped, it has relatively high accuracy, but there are manufacturing tolerances
The bush 15A also has a tolerance, and the piston rod 14
Since there is a tolerance, the guide bush 15A and the piston rod
There are cases where the tolerance of the pad 14 is maximum and minimum.
Cylinder 1 is present when the tolerance is maximum and minimum.
Change in the pressure increase in the rod side oil chamber 13
If the stone speed is slow, the damping force will be affected.
It At this time, at least the first flow path 51 and the second flow path 53
One of them is the orifice 80, and the orifice 80 is locked.
Smaller flow path than the gap between guide guide 15 and piston rod 14
By using the orifice 80 with a cross-sectional area, the damping force is generated.
Raw is defined by this orifice 80, rod guide
15 due to manufacturing tolerances of piston rod 14 and piston rod 14
It is possible to suppress wobble. For example, rod guide 1
5 and piston rod 14 manufacturing tolerance is 1.4mm^Two~ 0.4m
m ^TwoOrifice 80 0.4mm in case of equivalent^TwoSet to
By doing so, it is possible to suppress variations in damping force due to manufacturing tolerances.
You can

In the present embodiment, a groove is formed in the recess 30 of the rod guide 15, and the second flow path 53 (or the first flow path 51) is formed between the groove and the cored bar 21 of the friction member 20 press-fitted into the recess 30. The second channel 53 that forms the orifice 80
(Or the 1st flow path 51) can be created easily with high precision.

The friction member 20 includes the 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. 6 (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 imparting 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. 6 (D).

Although the embodiment of the present invention has been described in detail with reference to the drawings, 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, in the practice of the present invention, the first flow path and the second flow path forming the inflow path
Each of the flow passages is provided at a single position along the annular flow passage, and the first flow passage and the second flow passage which are adjacent to each other along the annular flow passage are alternately arranged 180 degrees apart from each other along the annular flow passage. Is also good. Each of the first flow path and the second flow path may be provided at three circumferential positions along the annular flow path.

Further, the inflow passage of the present invention may be formed on the friction member side, for example, may be formed by a groove provided on the core metal of the friction member. Further, the outflow passage of the present invention may be formed on the oil seal side, for example, may be formed by a groove provided in the core metal of the oil seal.

In FIG. 2, the oil seal lip 16B of the oil seal 16 and the friction imparting 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.

[0066]

As described above, according to the present invention, in the hydraulic shock absorber for imparting friction to the piston rod,
It is possible to improve the air bleeding property from the oil sump chamber for preventing the oil film of the oil seal from being broken, to generate a stable friction, and to generate a stable damping force.

[Brief description of drawings]

FIG. 1 is a schematic view showing a hydraulic shock absorber.

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

FIG. 3 is a plan view showing a rod guide.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a perspective view showing a rod guide.

FIG. 6 is a schematic view showing various modes of a friction member.

[Explanation of symbols]

10 hydraulic shock absorber 12 cylinders 13 oil chamber 14 Piston rod 15 Rod guide 16 oil seal 16C check lip (outflow check means) 19 reservoir 20 Friction member 22A Friction imparting lip 22B check lip (return means for inflow) 40 oil sump chamber 50 inflow path 51 First flow path 52 annular flow path 53 Second channel 60 Outflow 71 Inverse means for inflow 72 Check means for outflow 80 orifice

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 CC13 CC15 CC18 CC19                       DD33

Claims (5)

[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 placed between the rod guide and the oil seal to form an oil sump chamber between the oil seal and the friction member, and an inflow path that connects the oil chamber of the cylinder to the oil sump chamber and the oil chamber of the cylinder are additionally provided. In a friction imparting structure of a hydraulic shock absorber having an outflow passage communicating with an oil sump chamber in a reservoir, the inflow passage is provided in a lower portion of the oil sump chamber, and a first flow path is provided on the oil chamber side of the cylinder. And a second flow path provided on the oil reservoir side, and an annular flow path connecting the first flow path and the second flow path, and the first flow path and the second flow path alternate with respect to the annular flow path. And the outflow passage is provided in an upper portion of the oil sump chamber. 2. The first flow path is provided at two positions forming 180 degrees along the annular flow path, and the second flow path is also provided at two positions forming 180 degrees along the annular flow path. The friction imparting structure for a hydraulic shock absorber according to claim 1, wherein the first flow path and the second flow path which are adjacent to each other along the flow path are arranged alternately along the annular flow path with a space of 90 degrees therebetween. 3. The friction imparting structure for a hydraulic shock absorber according to claim 1, wherein the inflow check means is provided in the inflow path, and the outflow check means is provided in the outflow path. 4. The friction imparting structure for a hydraulic shock absorber according to claim 3, wherein the inflow check means comprises a check lip integrated with a friction member, and the check lip is arranged in the annular flow path. 5. The method according to claim 1, wherein at least one of the first flow path and the second flow path is an orifice, and the orifice has a flow path cross-sectional area smaller than a gap between the rod guide and the piston rod. The friction imparting structure for a hydraulic shock absorber according to claim 1.