JPH09303465A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To show effective shock absorbing characteristics and eliminate the difficulty in adjustment of the characteristics. SOLUTION: A cylinder 2 has a part 21 having a large inner diameter 21 and a part 22 having a small inner diameter. A cylindrical piston 3 has an end wall 31 at its one end, and an outer diameter so as to enable sliding with the small inner diameter part 22. A plurality of orifices 32a are formed on a peripheral wall 32, while a through-hole 31a for a piston rod 4 and at least one through-hole 31b for viscous fluid are formed on the end wall 31. The piston rod 4 has a strokelarger than thickness of the end wall 31 of the piston 3, and is provided with flanges 43, 44 sandwiching the end wall 31 therebetween. When the piston 3 is moved in the direction of absorbing shock, the through-hole 31b on the end wall 31 is blocked by means of the flange 43. The viscous fluid is moved only by the orifices 32a. On resetting the piston 3, the through-hole 31b is released, and a large amount of viscous fluid is moved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber.

[0002]

2. Description of the Related Art Conventionally, various shock absorbers have been known, but if classified according to the structure of a cylinder, they are roughly classified into a single-tube structure composed of one cylinder.
There is a double tube structure having an outer cylinder and an inner cylinder formed at a constant distance from the outer cylinder.

The single tube structure further includes a groove-orifice type having a groove-shaped orifice in the peripheral wall of the cylinder, and an outer diameter of the piston smaller than the inner diameter of the cylinder.
There is a dashpot type that uses the gap between the two as an orifice. As a double-tube structure, a structure in which a plurality of holes are formed in an inner cylinder is generally popular.

[0004]

The above-mentioned conventional shock absorbers are selected and used according to the cost and application, but in general, the single-tube structure has a dual structure because of its simple structure. The manufacturing cost is lower than that of a tube structure. However, the dashpot type theoretically has the drawback that the characteristics are not stable and the characteristics vary greatly between products. The groove-orifice type does not have such a problem, but the groove is usually formed by cutting or molding with a mold, so the groove should be formed so as to exhibit the characteristics suitable for the application. Takes a lot of time and labor as compared with the work of adjusting the characteristics by the size and number of holes formed in the double tube structure.

On the other hand, in the case of the double tube structure, in addition to the manufacturing cost, since the piston is arranged in the inner cylinder, when the outer dimensions of the single tube structure and the cylinder are the same, The piston diameter will necessarily be smaller than that of the single tube construction. Since there are restrictions on where to install it, it is not possible to increase the outer dimensions of the cylinder.
Not only the piston diameter but also the thickness of the inner cylinder is usually limited. Therefore, if the outer dimensions are the same as those of the single tube structure, the inner cylinder may be damaged during use unless the shock absorption characteristics are smaller than those of the single tube structure. There is.

The present invention has been made in order to solve the above-mentioned problems, and while adopting a single tube structure which is low in manufacturing cost and capable of exhibiting a large shock absorbing characteristic even in a small size, An object of the present invention is to provide a shock absorber that solves the difficulty of matching the characteristics, which is a problem of the single tube structure.

[0007]

In order to achieve the above object, the shock absorber of the present invention has a piston movable in the cylinder, and the movement of the piston causes the viscous liquid filled in the cylinder to become an orifice. In the shock absorber that absorbs the shock by moving through, the cylinder has a portion having a large inner diameter and a portion having a small inner diameter, and the piston is formed in a tubular shape having an end wall at one end, and a portion having a small inner diameter in the cylinder. It is characterized by having an outer diameter of such a size that it can slide over and having a plurality of orifices in the peripheral wall.

In this case, the end wall of the piston has at least one through-flow hole for the viscous liquid, while the piston rod is arranged in the insertion hole of the piston rod provided in the end wall and the end wall. Of two flanges that are arranged with a distance wider than the thickness of the end wall and that are sandwiched between the end walls, and that flow through the end wall when the piston moves in the direction that exerts shock absorbing characteristics. One flange portion provided outside the end wall, which is formed in a size capable of closing the hole,
The other flange portion provided inside the end wall, which is formed in a structure that does not close the flow-through hole even if it abuts against the end wall, can be adopted.

The end wall of the piston has through holes for at least one viscous liquid, each of which has a small diameter hole portion and a large diameter hole portion, and in the large diameter hole portion,
A ball valve that closes the small-diameter hole portion when the piston moves in the direction that exhibits the shock absorption characteristics and that is separated from the small-diameter hole portion when the piston moves in the return direction may be provided. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings. In the figure, 1
Is a shock absorber according to the present embodiment, which includes a cylinder 2, a piston 3, and a piston rod 4.

The cylinder 2 is formed to have a large inner diameter portion (large diameter portion) 21 and a small inner diameter portion (small diameter portion) 22. Specifically, the large diameter portion 21 is provided on the return position side (upper end 24 side) of the piston 3 and the other side (bottom wall 23
The small diameter portion 22 is formed on the side. The diameter of the large diameter portion 21 is larger than the outer diameter of the piston 3, and the diameter of the small diameter portion 22 is such that the piston 3 can slide, that is, substantially the same as the outer diameter of the piston 3. Conversely speaking, the outer diameter of the piston 3 is smaller than the diameter of the large diameter portion 21, and the small diameter portion 22
It is almost the same size as the inner diameter of. Then, the large diameter portion 21 and the small diameter portion 22 function as a liquid chamber in which the viscous liquid is filled. The cylinder 2 is formed by closing the bottom wall 23 and has an upper end 2
A lid member 25 having a piston rod insertion hole for allowing a piston rod 4 to be described later to protrude to the outside of the cylinder 2 is arranged in a liquid-tight manner at 4. Further, an accumulator 26 is arranged between the large diameter portion 21 and the lid member 25 so as to surround the piston rod 4.

The piston 3 has a cylindrical shape having an end wall 31 on one end side (upper end 24 side) and an open other end side (bottom wall 23 side), and a peripheral wall 32 having the outer diameter as described above. have. The end wall 31 has an insertion hole 31a for a piston rod, which is formed at a substantially central portion with a diameter such that a tip portion of a piston rod 4 described later can be loosely inserted, and at least one viscous liquid throughflow hole is provided around the insertion hole 31a. A through hole 31b is formed. In addition, the peripheral wall 32 is formed with a plurality of orifices 32a. Of course, the formation position of the orifice 32a is formed so as to be located inside the large diameter portion 21 at the return position of the piston 3.

The rear end 41 side of the piston rod 4 projects outward from the piston rod insertion hole of the lid member 25 described above, and the piston rod 4 is mounted on the front end 42 side where the piston 3 is mounted.
Two flange portions 43 and 44 are provided. The two flange portions 43, 44 are provided at a predetermined interval, and the piston 3 is arranged such that the end wall 31 is located between the two flange portions 43, 44.
Attached to. More specifically, first, one flange portion 43 is attached to the piston 3 at an appropriate position of the piston rod 4.
Is formed to have a diameter larger than that of the insertion hole 31a formed in the end wall 31 of the front end 4
A portion (tip portion) 42a closer to 2 is formed to have a diameter smaller than that of the insertion hole 31a, and the piston 3 is loosely inserted into the insertion hole 31a.
It faces the inside of the peripheral wall 32. The other flange portion 44 is formed with a larger diameter than the insertion hole 31a in the fitting member 45 that is formed as a separate body and has a hole 45a that fits into the tip portion 42a. Rod 4
The distal end portion 42a of the piston 3 is inserted into the insertion hole 31a and then fitted and fixed, so that a distance wider than the thickness of the end wall 31 of the piston 3 with respect to the one flange portion 43 is provided.
It will be arranged with sandwiching between.

The one flange portion 43 is thus arranged outside the end wall 31 of the piston 3, and when the rear end 41 of the piston rod 4 is pressed to move the piston 3 in the shock absorbing direction, that is, When the cylinder 2 is moved to the bottom wall 23 side, the insertion hole 31 may be used as long as it can abut the end wall 31 of the piston 3 to close the through-flow hole 31b.
The shape is not limited as long as it has a diameter larger than a. For example, it may be partially projected so as to correspond to the through hole 31b. However, it is generally formed in a substantially circular shape having a radius capable of closing the flow-through hole 31b for ease of manufacturing. Further, in the present embodiment, one flange portion 43 is a portion of the piston rod 4 closer to the rear end 41 than the flange portion 43 (rear end portion).
Although it is formed with a diameter larger than 41a, the rear end portion 41a
The diameter may be the same in all, including the portion functioning as the flange portion 43. Further, one flange portion 43
Alternatively, it can be formed by fitting and mounting a separate ring member (not shown).

The other flange portion 44 is provided inside the end wall 31 of the piston 3 as described above, and when the load on the rear end 41 of the piston rod 4 is released and the return operation is performed, the through hole 31b is formed. Any shape may be used as long as it is in contact with the inner surface of the end wall 31 so as not to be blocked. Generally, if it is formed in a substantially circular shape having an outer diameter of a length shorter than the distance from the axial center to the position where the through-flow hole 31b is provided, manufacturing is easy. However, it is also possible to adopt a configuration in which the groove or hole (not shown) is formed in a portion corresponding to the flow-through hole 31b by forming it with a larger diameter. Alternatively, a separate ring member (not shown) may be attached.

Here, reference numeral 5 is a return spring for the piston 3. In the present embodiment, it is arranged between the other flange portion 44 and the bottom surface of the cylinder 2 in the liquid chamber constituted by the large diameter portion 21 and the small diameter portion 22, but the invention is not limited to this. Not something. For example, it may be provided around the piston rod 4 protruding from the lid member 25.

According to the shock absorber 1 of the present embodiment having such a configuration, the rear end 41 of the piston rod 4 is
When the piston rod 4 is pressed by contacting the object to be controlled, the piston 3 moves toward the bottom wall 23 of the cylinder 2. At this time, the one flange portion 43 of the piston rod 4 contacts the end wall 31 of the piston 3 and the through hole 3
Since 1b is closed, the viscous liquid moves from the inside of the peripheral wall 32 of the piston 3 to the gap formed by the piston 3 and the large diameter portion 21 of the cylinder 2 via only the orifice 32a. Then, the dynamic pressure resistance and the viscous resistance when the viscous liquid passes through the orifice 32a make the movement of the piston 3 and the piston rod 4 slow, and the impact of the controlled object is alleviated. As the piston 3 further slides in the small diameter portion 22 of the cylinder 2, a plurality of orifices 32 a are provided by the inner surface of the small diameter portion 22 to cause the piston 3 to move.
The blocks are closed in order from the one provided near the open end. Therefore, the acting resistance gradually increases. When all the orifices 32a are moved from the large diameter portion 21 to the small diameter portion 22, the viscous liquid is not moved, and the orifices are locked.

When the load of the object to be controlled is removed from the piston rod 4, the return spring 5 first momentarily causes only the piston rod 4 until the other flange portion 44 contacts the inner surface of the end wall 31 of the piston 3. Return to. When the other flange portion 44 comes into contact with the end wall 31, the one flange portion 43 is separated from the outer surface of the end wall 31, so that a gap is formed between them and the flow-through hole 31b is opened. As a result, the viscous liquid accumulated in the gap formed by the outer surface of the piston 3 and the large-diameter portion 21 flows through the through hole 31b,
With the return operation, a large amount moves into the piston 3 via the orifice 32a positioned in the large-diameter portion 21, so that the piston 3 and the piston rod 4 quickly return to the original position.

When it is desired to change the shock absorption characteristics according to the object to be controlled without changing the outer dimensions, in the present embodiment, the orifice 32a formed in the piston 3 is used.
It is only necessary to adjust the number of holes and the hole diameter.

In the above embodiment, the two flange portions 4
3 and 44 are provided on the piston rod 4, and thereby the function as a valve for opening and closing the through-flow hole 31b of the piston 3 is exerted, but various conventionally known valve mechanisms can be provided without providing the flange portions 43 and 44. Of course, it is possible to adopt it. For example, the through hole 31b can be formed to have a small diameter hole portion and a large diameter hole portion, and a ball valve (not shown) can be arranged in the large diameter hole portion. In this case, when the piston 3 moves in the direction in which the shock absorbing characteristic is exerted, the small diameter hole portion is closed by the ball valve and the orifice 32a is closed.
The viscous liquid is moved only by the piston 3
Is moved away from the small diameter hole portion when moving in the returning direction, and a large amount of viscous liquid is moved through the through hole 31b.

[0021]

Since the shock absorber of the present invention employs a so-called single tube structure in which the cylinder has a single wall, the manufacturing cost is lower than that of the double tube structure. Further, when compared with a double tube structure having the same outer dimensions, the diameter of the piston can be increased and the thickness of the wall portion of the cylinder can be increased, so that the shock absorption characteristics can be further increased. . Moreover, since the orifice is in the shape of a hole, the work is easier and the shock absorbing characteristic adjusting work suitable for the object to be controlled is easier than the case of forming the groove.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a shock absorber according to the present invention.

FIG. 2 is a partially enlarged view of the same embodiment.

[Explanation of symbols]

 1 Shock Absorber 2 Cylinder 3 Piston 31 End Wall 31b Through Hole 32 Peripheral Wall 32a Orifice 4 Piston Rod 43 One Flange Part 44 The Other Flange Part 5 Return Spring

Claims (3)

[Claims] 1. A shock absorber having a piston movable in a cylinder, wherein the movement of the piston absorbs shock by viscous liquid filled in the cylinder moving through an orifice. The piston has a large portion and a small portion, and the piston is formed in a tubular shape having an end wall at one end, has an outer diameter such that it can slide on a portion having a small inner diameter in a cylinder, and has a plurality of orifices on its peripheral wall. A shock absorber characterized by having. 2. An end wall of the piston has at least one through-flow hole for the viscous liquid, while a piston rod is arranged in an insertion hole of the piston rod provided in the end wall and the end wall of the end wall is formed. Two flange portions having a spacing wider than the thickness and arranged with the end wall sandwiched therebetween, and a through-flow hole of the end wall when the piston moves in a direction exhibiting shock absorbing characteristics. One flange portion formed on the outside of the end wall, which is formed in a size capable of closing the end wall, and the inside of the end wall formed in a structure that does not close the through hole even if it abuts on the end wall. The shock absorber according to claim 1, which has the other flange portion provided. 3. The end wall of the piston is a through-flow hole for at least one viscous liquid, each of which has a through-flow hole having a small diameter hole portion and a large diameter hole portion, and in the large diameter hole portion, A ball valve is provided which closes the small-diameter hole portion when the piston moves in the direction exhibiting the shock absorbing characteristic and separates from the small-diameter hole portion when the piston moves in the returning direction.
The shock absorber as described.