JPH1182595A - Strut damper of double cylinder type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten the rigidity of a double cylinder type strut damper and to lessen the amount of deflection. SOLUTION: An outer tube 1 is formed from an angular pipe through a plastic processing of part of the pipe, and a great majority thereof is formed as an angular part 1a while the top is formed as a cylindrical part 1b, and a rod guide 12 and oil seal 13 are furnished on the inside of the cylindrical part 1b, and a cap 14 is furnished at the top on the outside. That, is, the rod guide 12, oil seal 13, and cap 14 are of ring form as similar to the conventional arrangement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a double-cylinder strut damper.

[0002]

2. Description of the Related Art A double-cylinder strut damper in which an inner tube is disposed inside an outer tube is disclosed in
Japanese Unexamined Patent Publication No. 21639 or Japanese Utility Model Laid-Open Publication No. 4-13835 is known. In each of these publications, a rib or a concave groove is formed on the outer circumference of the outer tube to position and prevent the rotation of the spring seat.

On the other hand, as shown in FIG. 6, a double-cylinder strut damper 100 has an outer tube 101 attached to a wheel side via a bracket 102, and a piston rod 103 attached to a vehicle body side via a bracket 104.

[0004]

When an input (F) from a wheel acts on the double-cylinder strut damper 100,
Deflection occurs in the double-cylinder strut damper 100. The greater this deflection, the greater the change in geometric configuration, especially camber.

However, the above-mentioned Japanese Utility Model Application Laid-Open No. 56-21
When a rib or the like is locally formed as in a double-cylinder strut damper disclosed in Japanese Patent No. 639 or Japanese Utility Model Application Laid-Open No. 4-13835, the strength of the portion where the rib or the like is formed is improved, Although the amount of deflection of the damper as a whole is reduced, its manufacturing cost is increased.

[0006]

According to the present invention, there is provided a double-cylinder strut damper according to the present invention, wherein an outer tube for accommodating a cylindrical inner tube has a square tubular shape excluding an upper end portion. The upper end was formed into a cylindrical shape by plastically processing a rectangular tube.

Here, when a part of the rectangular tube is plastically worked, the weight per unit length of the rectangular tube and the cylindrical portion of the outer tube becomes substantially equal. Then, when the weight per unit length is equalized, the second moment of area and the section modulus of the rectangular cylindrical portion are greatly improved as compared with the cylindrical portion.

Since the upper end of the outer tube has a cylindrical shape, a rod guide or an oil seal provided inside can be selected to have a conventional shape.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is an overall view of a multi-cylinder strut damper according to the present invention, FIG. 2 is a view showing the shape of an outer tube of the multi-cylinder strut damper, FIG.
1 is a cross-sectional view taken along the line AA in FIG. 1, FIG. 4 is a cross-sectional view taken along the line BB in FIG.
FIG. 5 is a sectional view taken along line CC of FIG.

In the double-cylinder strut damper, an inner tube 2 is disposed inside an outer tube (bottom tube) 1, and the outer tube 1 is attached to a wheel by a bracket 3, and a piston rod 4 is inserted into the inner tube 2. The upper end of the piston rod 4 is attached to the vehicle body by a bracket 5, and the lower end of the piston rod 4 is fixed with a piston 6 defining an oil chamber S1 in the inner tube 2 as upper and lower oil chambers.

An upper spring seat 7 is supported below the bracket 5, and a lower spring seat 8 is supported at an intermediate portion of the outer tube 1. A suspension spring is provided between the upper spring seat 7 and the lower spring seat 8. 9 are provided.

A bump rubber 10 is provided below the upper spring seat 7.
A dust boot 11 is arranged outside the piston rod 4.

On the other hand, a rod guide 12 is provided at the upper end of the inner tube 2, and an oil seal 13 is further provided thereon, and these are held by caulking the upper end of the outer tube. The rod guide 12 forms an oil reservoir S2 at a constant interval between the inner surface of the outer tube 1 and the outer surface of the inner tube 2. In the figure, reference numeral 14 denotes a cap press-fitted from the upper end of the outer tube.

Thus, in the compression stroke, the operating oil corresponding to the intrusion volume of the piston rod 4 flows into the oil storage chamber S2 via the bottom valve, and in the extension stroke, the piston rod 4
Of hydraulic oil corresponding to the retreat volume is returned from the oil reservoir S2 to the oil chamber S1.

By the way, the outer tube 1 is formed by plastically processing a part of a rectangular tubular pipe so that a large part is a rectangular tubular part 1a and an upper end part is a cylindrical part 1b. The rod guide 12 and the oil seal 13 are provided inside the cylindrical portion 1b, and a cap 14 is provided on the upper outside. That is, the rod guide 12, the oil seal 13
As for the cap 14, an annular one similar to the conventional one is used.

[0016]

The following Table 1 shows the outer tube according to the present invention (sample 1) and the conventional outer tube (sample 2).
4) the moment of inertia (I), the section modulus (Z),
The cross-sectional area (A) and the weight per unit length (kg / m) are compared.

[0017]

[Table 1]

In this table, from the comparison between sample 1 and sample 2, when the diameter and the thickness are almost the same, the square tubular outer tube of the present invention has a secondary cross section which is smaller than that of the conventional cylindrical outer tube. It can be seen that the moment is improved by about 62% and the section modulus is improved by about 61%. From the comparison between Sample 1 and Sample 3, if the outer tube has the same rigidity, the weight of the square tubular outer tube of the present invention is about 30% lighter than that of the conventional cylindrical tube. You can see that it works. In addition, from the comparison between Sample 1 and Sample 4, when the outer tube having the same weight is used, the square tubular outer tube of the present invention has a cross-section of 2 times compared to the conventional cylindrical tube.
Next moment is improved by about 33.6%, and section modulus is about 3
It can be seen that the amount of deflection is reduced by 2.6%.

Furthermore, according to the present invention, since the upper end of the outer tube is formed in a conventional cylindrical shape, parts such as a rod guide, an oil seal or a cap incorporated in the outer tube can be used as they are. Can be.

[Brief description of the drawings]

FIG. 1 is an overall view of a double-cylinder strut damper according to the present invention.

FIG. 2 is a view showing the shape of an outer tube of the double-cylinder strut damper.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is a sectional view taken along line CC of FIG. 1;

FIG. 6 is a diagram illustrating a use state of a double-cylinder strut damper.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer tube, 1a ... Square cylindrical part, 1b ... Cylindrical part, 2 ... Inner tube, 3, 5 ... Bracket, 4 ...
Piston rod, 6: piston, 7, 8: spring seat, 9: suspension spring, 12: rod guide, 13
... oil seal, 14 ... cap, S1 ... oil chamber, S2 ...
Oil reservoir.

Claims (3)

[Claims] 1. A double-cylinder strut damper in which an inner tube is disposed in an outer tube, wherein the inner tube has a cylindrical shape, and the outer tube has a rectangular cylindrical shape except for an upper end portion, and an upper end portion has a square cylindrical shape. A double-cylinder strut damper characterized by forming a cylindrical tube into a cylindrical shape by plastic working. 2. The strut damper according to claim 1, wherein the outer tube has substantially the same weight per unit length as the square tubular portion and the cylindrical portion of the outer tube. . 3. The strut damper according to claim 1, wherein a rod guide or an oil seal is provided inside the cylindrical portion of the outer tube. damper.