JP6894828B2 - Buffer - Google Patents

Description

The present invention relates to a shock absorber.

Generally, in a double-cylinder type shock absorber, a cylinder, an outer cylinder provided outside the cylinder and forming a reservoir between the cylinders, and a rod side chamber that is movably inserted into the cylinder and is inserted into the cylinder. A piston that divides the piston into two chambers, a rod that is movably inserted into the cylinder and connected to the piston, and a rod guide that is fitted to the upper ends of the cylinder and outer cylinder to movably support the rod. And have. The cylinder is filled with hydraulic oil, and the reservoir is filled with hydraulic oil and an inert gas.

Generally, in a shock absorber, the cylinder diameter is predetermined, and the rod guide corresponds only to a cylinder having a predetermined diameter. If it is desired to increase the damping force without changing the outer diameter of the shock absorber due to the mounting space on the vehicle, the pressure receiving area of the piston may be increased, but then the cylinder diameter must be increased. On the other hand, when it is not necessary to increase the damping force, it is not necessary to increase the piston diameter and the cylinder diameter. In this way, if the rod guide must also be changed when changing the cylinder diameter according to the demand for high or low damping force, it is necessary to manage multiple types of rod guides, and measures against incorrect assembly etc. are also taken. It will be necessary.

Therefore, in the above-mentioned shock absorber, an annular groove is provided at the cylinder side end of the rod guide so that cylinders having different diameters can be accommodated. When using a large-diameter cylinder, the outer peripheral surface of the cylinder is fitted to the outer side surface of the annular groove, and when using a small-diameter cylinder, the inner circumference of the cylinder is fitted to the inner side surface of the annular groove. Fit the faces. As described above, in the conventional shock absorber, the rod guide is provided with an annular groove that allows fitting of two types of cylinders having different diameters so that the rod guide can handle two types of cylinders having different diameters (see, for example, Patent Document 1). ).

Japanese Patent No. 6080257

By the way, in the double-cylinder type shock absorber, the hydraulic oil that has passed between the rod and the rod guide and moved above the rod guide is passed through the rod guide up and down in order to return it to the reservoir. A communication hole is provided. Since the communication hole is required to communicate with the reservoir, the communication hole is opened from the upper end of the rod guide to a portion facing the reservoir on the outer peripheral side of the annular groove at the lower end.

When the communication hole is provided in the rod guide in this way, the wall thickness between the annular groove of the rod guide and the communication hole becomes thin, and the strength of the outer peripheral side fitted to the cylinder of the rod guide decreases. When the shock absorber is incorporated into the suspension of the vehicle, an external force (lateral force) acts on the shock absorber from the lateral direction, but there is a problem that the durability against such a lateral force is poor.

Therefore, the present invention has been devised to improve the above-mentioned problems, and an object of the present invention is to provide a shock absorber capable of sufficiently withstanding an external force from a lateral direction.

The shock absorber of the present invention has an annular portion in which the rod guide projects toward the cylinder side, and a return passage that opens from the anti-cylinder side end to the inner circumference of the annular portion and the cylinder side end to lead to the reservoir. .. According to the shock absorber configured in this way, the return passage opens from the anti-cylinder side end to the inner circumference of the annular portion and the cylinder side end, so that even if the return passage is provided in the annular portion, the annular portion The wall thickness can be secured, and the strength of the rod guide does not decrease.

Further, the rod guide may have a fitting portion having a diameter smaller than that of the annular portion capable of fitting the small diameter cylinder on the inner peripheral side of the annular portion capable of fitting the large diameter cylinder. With the shock absorber configured in this way, a single rod guide can handle two types of cylinders with different diameters, so parts management is not complicated, misassembly does not occur in the manufacturing process, and manufacturing costs are increased. Is also cheaper.

Further, when the annular portion is provided at a position where the annular portion overlaps the fitting portion in the axial direction of the rod guide and the outer circumference of the rod guide and the lower end of the annular portion are flush with each other, the fitting length of the rod guide to the outer cylinder Can be secured for a long time, which is advantageous in terms of strength against the input of lateral force.

Further, when the annular portion is provided at a position retracted to the anti-cylinder side from the fitting portion in the axial direction of the rod guide, the material cost of the rod guide becomes low and the manufacturing cost of the shock absorber is reduced.

When the return passage is formed by a hole penetrating along the axial direction of the rod guide, the return passage can also be formed by a mold when the rod guide is sintered, so that the rod guide can be easily processed. The manufacturing cost of the shock absorber can be reduced.

Further, if the central angle at the opening to the inner circumference of the annular portion in the return passage is θ1 and the central angle behind the opening in the return passage is θ2, then θ1 ≧ θ2. , The central angle θ2 may be located within the range of the central angle θ1. When the return passage is formed in this way, fragile portions are not formed on both sides of the opening to the inner circumference of the annular portion of the return passage, and even if a lateral force acts on the shock absorber, the deformation of the annular portion is prevented and the return passage is formed. The cross-sectional shape of can be maintained.

According to the shock absorber of the present invention, it can sufficiently withstand an external force from the lateral direction.

It is a vertical sectional view of the shock absorber in one embodiment. It is an enlarged plan view of the rod guide of the shock absorber in one Embodiment. It is a partial half-cut enlarged sectional view of the shock absorber in one embodiment. It is an enlarged perspective view of the rod guide of the shock absorber in one Embodiment. It is a partially enlarged rear view of the rod guide of the shock absorber in one embodiment. It is a partially enlarged rear view of the rod guide of the shock absorber in the 1st modification of one Embodiment. It is an enlarged rear view of the rod guide of the shock absorber in the 2nd modification of one Embodiment.

Hereinafter, the shock absorber of the present invention will be described with reference to the drawings. As shown in FIG. 1, the shock absorber 1 of the embodiment is an outer cylinder 3 which is provided so as to cover the cylinder 2 on the outer peripheral side of the cylinder 2 and forms a reservoir R between the cylinder 2 and the cylinder 2. The piston 5 is movably inserted into the cylinder 2 to partition the inside of the cylinder 2 into the rod side chamber R1 and the piston side chamber R2, and the lower end is connected to the piston 5 while being movably inserted into the cylinder 2. The rod 4, the rod guide 8 that is fitted into the openings of the cylinder 2 and the outer cylinder 3 to movably support the rod 4, and the seal member 22 that is laminated above the rod guide 8 and seals the inside of the shock absorber 1. And have.

The cylinder 2 has a tubular shape, the upper end of the opening is closed by the rod guide 8, and the lower end of the opening is closed by a valve case (not shown).

The rod side chamber R1 and the piston side chamber R2 of the cylinder 2 are filled with a liquid such as hydraulic oil, and the reservoir R between the cylinder 2 and the outer cylinder 3 is inert to the liquid such as hydraulic oil. It is filled with gas such as gas. Although the liquid is used as hydraulic oil in this example, it may be used as another liquid such as water or an aqueous solution. Further, in this example, the gas is preferably an inert gas such as nitrogen that does not cause deterioration of the hydraulic oil, but other gases such as the atmosphere can also be used.

The piston 5 is provided with two passages 5a and 5b that communicate the rod side chamber R1 and the piston side chamber R2. One passage 5a is provided with a check valve 6 that allows only the flow of liquid from the piston side chamber R2 to the rod side chamber R1. Further, the other passage 5b is provided with an extension side damping valve 7 that allows only the flow of liquid from the rod side chamber R1 to the piston side chamber R2 and gives resistance to the flow of the passing liquid.

The outer cylinder 3 has a tubular shape and the lower end (not shown) is closed, and the upper end is closed by the rod guide 8 in FIG. A reservoir R is formed between the outer cylinder 3 and the cylinder 2.

The upper end of the reservoir R is closed by the rod guide 8, and the lower end is closed by the valve case described above. Although not shown, the valve case is provided with two passages communicating the piston side chamber R2 and the reservoir R. Further, one of the passages is provided with a check valve that allows only the flow of liquid from the reservoir R to the piston side chamber R2. Further, the other passage is provided with a compression side damping valve that allows only the flow of the liquid from the piston side chamber R2 to the reservoir R and resists the flow of the passing liquid.

As shown in FIGS. 1 to 4, the rod guide 8 has an annular shape and is fitted to the opening ends of the cylinder 2 and the outer cylinder 3 to close the upper end openings of the cylinder 2 and the outer cylinder 3. .. The rod guide 8 is provided with a small diameter portion 9 and a large diameter portion 10 having a diameter larger than the small diameter portion 9 from the lower end side on the inner circumference, and the large diameter portion 10 is used to move the tubular rod 4 in the axial direction. The guiding bearing 21 is fitted.

Further, an annular recess 11 having a diameter larger than the outer diameter of the large diameter portion 10 is provided on the upper end side of the rod guide 8, and an annular step portion 12 and a step portion 12 are provided on the outer peripheral side of the annular recess 11. An annular convex portion 13 is provided so as to project upward in FIG. 1 from the outer peripheral side.

The upper surface 13a of the convex portion 13 is a horizontal plane, and the inner peripheral surface 13b of the convex portion 13 is formed as a tapered surface that inclines diagonally downward from the inner peripheral end of the upper surface 13a toward the outer peripheral end of the step portion 12. ing. Further, an annular recess 14 formed over the entire circumference is provided on the outer periphery of the convex portion 13 at the upper end of the rod guide 8.

As shown in FIGS. 2 to 4, notches 13c notched at predetermined widths and depths are provided at two locations of the convex portions 13. The cutout portion 13c has a shape notched from the inner circumference of the convex portion 13 to the outer circumference of the upper surface 13a, and is an inclined surface that inclines downward at a predetermined angle from the outer circumference of the upper surface 13a toward the inner circumference of the convex portion 13. It has become.

Further, as shown in FIGS. 1 and 3, an annular portion 17 projecting downward in the drawing is provided on the outer periphery of the lower end of the rod guide 8, and the inner circumference of the annular portion 17 faces the annular portion 17. At the same time, a fitting portion 19 having an outer diameter smaller than the inner diameter of the annular portion 17 is provided. That is, the annular portion 17 is provided at a position overlapping the fitting portion 19 in the axial direction of the rod guide 8. Further, the outer circumference of the rod guide 8 and the outer circumference of the annular portion 17 are flush with each other. An annular groove 18 is formed between the inner circumference of the annular portion 17 and the fitting portion 19, and the width of the groove 18 is set to be wider than the wall thickness of the cylinder 2. 18 is designed to allow the insertion of the cylinder 2. When the rod guide 8 is viewed from the axial direction, the inner peripheral surface of the annular portion 17 is located between the inner circumference and the outer circumference of the notch 13c, and the rod guide 8 is located between the notch 13c. It is provided with a return passage 20 that opens from and leads to the groove 18. Further, the outer circumference of the rod guide 8 and the outer circumference of the annular portion 17 are flush with each other, and the lower end of the annular recess 14 of the rod guide 8 to the lower end of the annular portion 17 abut on the inner circumference of the outer cylinder 3.

As shown in FIGS. 2 and 3, the return passage 20 penetrates the rod guide 8 in the vertical direction, opens from the anti-cylinder side end of the rod guide 8, and reaches the inner circumference of the annular portion 17 and the cylinder side end. It is formed by a hole that leads to it. Return passage 20, the rod guide 8 a as viewed in the axial direction notch 13c side opening is provided at a position according to a circular inner periphery of the annular portion 17. Therefore, the return passage 20 opens from the notch 13c, opens to the bottom surface of the groove 18, and cuts the inner peripheral portion of the annular portion 17 to reach the lower end of the annular portion 17. That is, the return passage 20 is open to the inner circumference of the annular portion 17 and the end on the cylinder side, and as shown in FIG. 5, the opening on the lower end side of the annular portion 17 in the return passage 20 is circular on the notch 13c side. It has a crescent-shaped shape in which the opening of the ring portion 17 is cut off at the inner peripheral edge of the annular portion 17. The return passage 20 may be opened to the inner circumference of the annular portion 17 and lead to the lower end, and may not be opened to the bottom of the groove 18. Therefore, even if the opening of the notch 13c in the return passage 20 has a crescent shape in which a circular shape is cut off at the inner peripheral edge of the annular portion 17, the return passage 20 is formed by penetrating the lower end of the annular portion 17 in the same shape as it is. Good. The cross section of the return passage 20 is a line connecting the center O of the rod guide 8 and both ends of the opening H to the inner circumference of the annular portion 17 in the circumferential direction, taking the return passage 20 shown in FIG. 5 as an example. It is preferable that the angle to be surrounded is equal to or greater than the angle surrounded by the line connecting the center O and both ends in the circumferential direction on the back side, and the latter angle is within the range of the former angle. .. That is, assuming that the center angle of the opening H of the annular portion 17 to the inner circumference of the annular portion 17 in the return passage 20 is set to θ1 and the central angle of the return passage 20 behind the opening H is set to θ2. It is preferable that θ1 ≧ θ2 and the central angle θ2 is located within the range of the central angle θ1 at all the locations on the back side of the opening H.

When the central angle θ2 is larger than the central angle θ1, as shown in FIG. 6, the wall thickness of the portion facing both ends in the circumferential direction of the opening H to the inner circumference of the annular portion 17 of the return passage 20 in the annular portion 17 is very thick. A fragile portion J that becomes thinner and has lower strength is formed. When the cylinder 2 is fitted to the inner circumference of the annular portion 17, when an external force (lateral force) in the lateral direction from the rod 4 acts on the rod guide 8, a load is applied to the contact portion between the annular portion 17 and the cylinder 2. Therefore, the above-mentioned fragile portion J is exposed to the load. For this reason, the central angle of the opening H to the inner circumference of the annular portion 17 in the return passage 20 is set to θ1 with the center O of the rod guide 8 as the center, and the central angle behind the opening H in the return passage 20. If is θ2, then θ1 ≧ θ2, and if the central angle θ2 is located within the range of the central angle θ1, the formation of the fragile portion J is prevented. If the cross-sectional shape of the return passage 20 is bent when viewed from the center O of the rod guide 8, the central angle θ2 comes out from the range of the central angle θ1, so that the strength becomes weak against the lateral force. Vulnerable part J is formed.

Further, when the return passage 20 is formed so as to avoid the groove 18 and communicate with the inner circumference and the lower end of the annular portion 17, the return passage 20 may be formed like the rod guide 8 of the shock absorber of the first modification shown in FIG. The cross-sectional shape may be arcuate. In this case, in order to avoid the bottom of the groove 18, the inner circumference of the arc-shaped return passage 20 when the rod guide 8 is viewed in the axial direction may have a curvature that matches the inner circumference of the annular portion 17. The return passage 20 may be formed at least along the axial direction of the rod guide 8 and communicate with the inner circumference and the lower end of the annular portion 17, and the cross-sectional shape of the return passage 20 is arbitrary. Therefore, for example, the opening on the notch 13c side may have a rectangular shape or other shape.

The cylinder 2 is inserted into the groove 18 of the rod guide 8 to close the upper end opening. Cylinders 2 having different diameters can be fitted to the rod guide 8. Specifically, the outer circumference of the cylinder 2 is fitted to the inner circumference of the annular portion 17 of the rod guide 8, or the side wall on the inner peripheral side of the groove 18 is used as the fitting portion 19 and inside the fitting portion 19. The circumference can be fitted to fit the rod guide 8. That is, when the large diameter cylinder 2 shown by the solid line in the figure is adopted, the outer diameter of the cylinder 2 may be a diameter that can be fitted to the inner circumference of the annular portion 17, and the small diameter cylinder shown by the broken line in the figure. When 2 is adopted, the inner diameter of the cylinder 2 may be set to a diameter that can be fitted to the fitting portion 19 which is the side wall on the inner peripheral side of the groove 18. As described above, the rod guide 8 of this example allows fitting of two cylinders 2 having different diameters. Even if the large-diameter cylinder 2 is inserted into the groove 18 and fitted to the inner circumference of the annular portion 17, the return passage 20 leads to the inner circumference of the annular portion 17 and the cylinder side end which is the lower end. , It is not blocked by the cylinder 2. Even if the small-diameter cylinder 2 is fitted into the groove 18, the return passage 20 is not blocked in the same manner. When the cylinder 2 is fitted to the rod guide 8 in this way, a reservoir R is formed between the outer cylinder 3 and the cylinder 2, the upper end of the reservoir R is closed by the rod guide 8 and communicates with the return passage 20. Will be done.

Subsequently, the seal member 22 is an annular plate-shaped insert metal 23, an annular inner peripheral seal 24 integrally provided on the inner peripheral side of the insert metal 23, and an annular seal 24 integrally provided on the outer peripheral side of the insert metal 23. An outer peripheral seal 25 and an annular check seal 26 integrally provided at the lower end of the insert metal 23 are provided.

The inner peripheral seal 24, the outer peripheral seal 25, and the check seal 26 are formed of an elastic body such as rubber, and are integrally provided on the insert metal 23 by means such as welding or adhesion.

The inner peripheral seal 24 is in contact with the outer circumference of the rod 4 while allowing the rod 4 to move in the axial direction, and seals the outer circumference of the rod 4. The outer peripheral seal 25 is housed in an annular recess 14 formed on the outer periphery of the rod guide 8 and is in close contact with the rod guide 8 and the inner peripheral surface of the outer cylinder 3. The seal member 22 is fixed in a state of being laminated upward in FIG. 1 of the rod guide 8 by crimping the upper end of the opening of the outer cylinder 3, and seals the upper end of the opening of the cylinder 2 and the outer cylinder 3.

The tip of the check seal 26 is in contact with the step portion 12 of the rod guide 8 in a bent state, and when the check seal 26 is in contact with the rod guide 8, the upper side of the rod guide 8 is on the back side of the inner peripheral seal 24. It is divided into a space A and a space B leading to the return passage 20. Then, when the rod 4 exits the cylinder 2, the inner peripheral seal 24 scrapes off the hydraulic oil adhering to the outer periphery of the rod 4. Therefore, when the shock absorber 1 repeats expansion and contraction, the hydraulic oil is accumulated in the space A. To. When the pressure in the space A increases, the check seal 26 bends and separates from the step portion 12 of the rod guide 8 to communicate the space A with the space B, so that the hydraulic oil accumulated in the space A is stored through the return passage 20. Can be discharged to R.

In the shock absorber 1 of the present embodiment configured as described above, the annular portion 17 in which the rod guide 8 projects toward the cylinder side, and the inner circumference and the cylinder side end of the annular portion 17 from the opposite end to the cylinder side end. It has a return passage 20 that opens to and leads to the reservoir R. According to the shock absorber 1 configured in this way, since the return passage 20 opens from the anti-cylinder side end to the inner circumference of the annular portion 17 and the cylinder side end, the return passage 20 is provided to the annular portion 17. Even if it is provided, the wall thickness of the annular portion 17 can be secured, and the strength of the rod guide 8 is not lowered.

In the shock absorber 1 configured in this way, the strength of the rod guide 8 can be ensured, so that the problem that the durability of the shock absorber 1 against the lateral force becomes poor is solved. Therefore, according to the shock absorber 1 of the present invention, it can sufficiently withstand an external force from the lateral direction.

Further, in the shock absorber 1 of this example, the annular portion 17 is provided at a position where the annular portion 17 overlaps the fitting portion 19 in the axial direction of the rod guide 8, and the outer periphery of the rod guide 8 and the outer periphery of the annular portion 17 are flush with each other. Therefore, it is possible to secure a long fitting length of the rod guide 8 to the outer cylinder 3. When the shock absorber 1 is configured in this way, the surface pressure of the rod guide 8 that comes into contact with the outer cylinder 3 when a lateral force acts on the shock absorber 1 can be lowered, which is advantageous in terms of strength with respect to the input of the lateral force. Become.

Further, since the return passage 20 is formed by a hole that penetrates the rod guide 8 straight along the axial direction of the rod guide 8, the return passage 20 is also formed by a mold when the rod guide 8 is sintered. Therefore, the rod guide 8 can be easily processed and the manufacturing cost of the shock absorber 1 can be reduced.

Further, when the shock absorber 1 exerts a high damping force, it is advantageous to have a large pressure receiving area of the piston 5, and it is preferable to use a cylinder 2 having a large diameter. On the other hand, when the damping force required for the shock absorber 1 is not so high, it is preferable to use the piston 5 having a small diameter and the cylinder 2 having a small diameter from the viewpoint of cost. In the shock absorber 1 of this example, as described above, a fitting portion 19 capable of fitting the small diameter cylinder 2 is provided on the inner peripheral side of the annular portion 17 capable of fitting the large diameter cylinder 2. A single rod guide 8 can handle two types of cylinders 2 having different diameters. In this way, it is necessary to select the diameters of the cylinder 2 and the piston 5 according to the specifications required for the shock absorber 1, but since it is not necessary to change the rod guide 8, parts management is not complicated and in the manufacturing process. No misassembly occurs, and the manufacturing cost is low.

Further, in this example, the central angle at the opening H to the inner circumference of the annular portion 17 in the return passage 20 is set to θ1 with the center of the rod guide 8 as the center, and the central angle behind the opening H in the return passage 20 is set. Assuming θ2, θ1 ≧ θ2, and the central angle θ2 is located within the range of the central angle θ1. When the return passage 20 is formed in this way, the fragile portions J are not formed on both sides of the opening H to the inner circumference of the annular portion 17 of the return passage 20, and even if a lateral force acts on the shock absorber 1, the annular portion 17 is formed. The deformation of the return passage 20 can be prevented and the cross-sectional shape of the return passage 20 can be maintained.

Further, like the shock absorber of the second modification shown in FIG. 7, the annular portion 17 provided in the rod guide 8 is positioned so as to recede toward the anti-cylinder side in the axial direction of the rod guide 8 with respect to the fitting portion 19. It may be provided in.

By doing so, the length of the annular portion 17 can be shortened, so that the volume of the rod guide 8 is shown in FIG. 1 while allowing fitting of cylinders 2 having different large and small diameters shown by the broken line and the alternate long and short dash line in FIG. It can be smaller than the volume of the rod guide 8. Therefore, in the shock absorber of this first modification, the material cost of the rod guide 8 can be reduced, and the manufacturing cost of the shock absorber can be reduced.

Although the preferred embodiments of the present invention have been described in detail above, modifications, modifications, and changes can be made as long as they do not deviate from the claims.

1 ... shock absorber, 2 ... cylinder, 3 ... outer cylinder, 4 ... rod, 5 ... piston, 8 ... rod guide, 17 ... annular part, 20 ... Return passage, R ... Reservoir

Claims (5)

Cylinder and
An outer cylinder provided on the outer peripheral side of the cylinder and forming a reservoir between the cylinder and the cylinder.
A piston movably provided in the cylinder and
A rod that is movably inserted into the cylinder and connected to the piston,
A rod guide that is fitted to the open end of the cylinder and the outer cylinder to movably support the rod is provided.
The rod guide includes an annular portion projecting toward the cylinder side, a fitting portion provided on the inner peripheral side of the annular portion having an outer diameter smaller than the inner diameter of the annular portion, and the rod guide from the anti-cylinder side end. open to the inner periphery and the cylinder side end of the annular portion possess a return passage communicating with the reservoir,
When the cylinder has a large diameter, the cylinder is fitted to the inner circumference of the annular portion of the rod guide.
When the cylinder has a small diameter, the cylinder is fitted to the outer periphery of the fitting portion of the rod guide . The annular portion is provided at a position overlapping the fitting portion in the axial direction of the rod guide.
The shock absorber according to claim 1 , wherein the outer circumference of the rod guide and the outer circumference of the annular portion are flush with each other. The shock absorber according to claim 1 , wherein the annular portion is provided at a position retracted toward the cylinder opposite to the fitting portion in the axial direction of the rod guide. The shock absorber according to any one of claims 1 to 3 , wherein the return passage is formed of a hole penetrating along the axial direction of the rod guide. If the central angle of the opening of the annular portion to the inner circumference of the annular portion in the return passage is θ1 and the central angle of the return passage behind the opening is θ2, then θ1 ≧ θ2. The shock absorber according to any one of claims 1 to 4 , wherein the central angle θ2 is located within the range of the central angle θ1.

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