JP2543029Y2 - Cylinder cooling sleeve - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder cooling sleeve which is press-fitted into a cylinder outer cylinder such as a gas spring using high-pressure gas to prevent the temperature of the cylinder from rising.

[0002]

2. Description of the Related Art A cylinder operating at a high speed such as a gas spring or an oil damper generates a considerable amount of heat upon operation, and therefore needs to be cooled in order to prevent deterioration of the seal member and the operating oil. . As a cylinder cooling sleeve used for this purpose, for example, as shown in FIG. 3, a cylindrical member 1 having a uniform thickness is formed by projecting a large number of cooling fins 3 along the longitudinal direction on an outer surface thereof by aluminum extrusion. There is one that is integrally formed by molding or the like and has a C-shaped cross-sectional shape in which a slit 2 is provided on a part of the circumference of the cylindrical portion 1 along the entire length in the longitudinal direction. This cylinder cooling sleeve is used by press-fitting the inner surface 1a of the cylindrical portion 1 to a cylinder outer cylinder such as a gas spring or the like, but the slit 2 reduces the rigidity in the direction in which the cylindrical portion 1 opens and closes. There is an advantage that it is not necessary to increase the machining accuracy of the inner surface 1a of the cylindrical portion 1 so much.

[0003]

However, in the prior art described above, the bending moment applied in the direction of opening the cylindrical portion 1 increases in the direction away from the position of the slit 2 along the circumferential direction in FIG. Since the bending rigidity of each part along the circumference of the part 1 is uniform, the bending deformation of each part along the circumference is not uniform, and the cylinder outer cylinder and the cylindrical part 1 to be press-fitted are not uniform. The surface pressure between the inner surfaces 1a also becomes non-uniform. For this reason, the cylinder outer cylinder is deformed unevenly,
The operation of the cylinder may be adversely affected. Actually, the inner surface 1a near the slit 2 locally strongly hits the cylinder outer cylinder, so that galling damage may occur during press-fitting. In addition, since the surface pressure on the opposite side of the slit 2 becomes small and the both sides may be slightly lifted up in some cases, heat transfer between the cylinder 2 and the cylinder becomes incomplete and the cooling effect is reduced. is there. An object of the present invention is to solve the above-mentioned problems by making the surface pressure between the cylinder and the cylinder outer cylinder uniform by devising the shape of the cylindrical portion of the cylinder cooling sleeve.

[0004]

For this purpose, a cylinder cooling sleeve according to the present invention has a cylindrical portion 10 having a cylindrical outer surface 12, as shown in FIGS. A number of cooling fins 15 formed integrally with the tubular portion 10 along the longitudinal direction and protruding outward, and a plurality of cooling fins 15 formed over a part of the circumference of the tubular portion 10 over the entire length to form the tubular portion. In the cylinder cooling sleeve comprising one slit 13 cut into a C-shaped cross section, the cylindrical portion 10
The cylindrical inner surface 11 is eccentric with respect to the outer surface 12 to change the thickness of the cylindrical portion in the circumferential direction, and the slit 1 extends along the thinnest portion of the cylindrical portion 10.
3 is formed.

[0005]

The cylinder cooling sleeve according to the present invention is used by press-fitting the inner surface 11 of the cylindrical portion 10 to a cylinder outer cylinder such as a gas spring. The bending moment applied in the opening direction of the cylindrical portion 10 increases as the position moves in the circumferential direction from the position of the slit 13, but the thickness of each portion on the circumference of the cylindrical portion 10 also increases in the circumferential direction from the position of the slit 13. As the distance increases along the direction, the bending stiffness also increases, so that the bending deformation of each portion on the circumference becomes substantially uniform, and the surface pressure between the outer surface of the cylinder outer cylinder and the inner surface 11 of the cylindrical portion 10 increases. Is also substantially uniform.

[0006]

As described above, according to the present invention, since the surface pressure between the cylinder and the cylinder that is press-fitted into the cylinder cooling sleeve becomes substantially uniform, the cylinder is deformed unevenly. Eliminates the risk of adversely affecting cylinder operation and ensures good heat transfer over the entire surface due to close contact with the cylinder outer cylinder, improving the cooling effect and possibly causing galling damage during press fitting. Disappears.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the accompanying drawings. As shown mainly in FIG. 1, the cylinder cooling sleeve of the present embodiment comprises a cylindrical portion 10 and a number of cooling fins 15 projecting radially from an outer surface 12 thereof, and the sectional shape thereof is as shown in FIG. Is constant over the entire length. The cylindrical portion 10 has an inner surface 11 (center O1, radius R1) and an outer surface 12 (center O1,
2, the radius R2), so that its thickness d varies continuously in the circumferential direction. Thickness d of cylindrical portion 10
The thinnest part of FIG.
As shown in (1), one slit 13 for cutting the cylindrical portion 10 over the entire length is formed, and the cylindrical portion 10 has a C cross-sectional shape.

On the outer surface 12 of the cylindrical portion 10, 18 cooling fins 15 extending in the longitudinal direction project radially at equal angular intervals. In the present embodiment, the tip of each cooling fin 15 is It is on a concentric circumference (radius r). The tubular portion 10 and the cooling fins 15 are integrally formed by aluminum extrusion. The slit 13 may be formed by cutting after extrusion molding, and the inner surface 11 may be subjected to finishing such as turning before cutting of the slit 13 as necessary. This cylinder cooling sleeve has an inner surface 1
1 is a piston rod 2 as shown by a two-dot chain line in FIG.
1 is press-fitted to the outer surface of a cylinder outer cylinder 20 such as a gas spring or an oil damper.

Next, the cross-sectional shape of the cylindrical portion 10 will be described.
As shown in FIG. 1, when using a polar coordinate having the center O1 of the inner surface 11 as a pole and the line L connecting the center O1 of the inner surface 11 and the center of the slit 13 as a base line, the pressure p applied to the inner surface 11 of the cylindrical portion 10 becomes uniform. When the shape of the inner surface 11 after the elastic deformation is also cylindrical, the thickness d of the cylindrical portion 10 is given by the following approximate expression.

(Equation 1) Where E: modulus of longitudinal elasticity δ: variation of radius R1 θ: declination (see FIG. 1)

According to this formula, the thickness of the thinnest portion of the cylindrical portion 10 at the position of the slit 13 is 0, and the outer surface 12 of the cylindrical portion 10 does not have a correct cylindrical shape. However, since this is not practical, the thickest portion of the cylindrical portion 10 (FIG. 1)
The thickness of the thinnest portion is manufacturable by determining the thickness of the uppermost portion at an angle of 180 degrees from the slit 13) with the desired surface pressure p between the inner surface 11 and the cylinder outer cylinder 20 and the allowable stress of the material. The outer surface 12 may have a minimum thickness and a cylindrical shape. As a result, the surface pressure between the inner surface 11 and the cylinder outer cylinder 20 becomes slightly uniform on the slit 13 side, but becomes substantially uniform.

This will be described qualitatively as follows. The bending moment applied in the direction to open the tubular portion 10 by the force applied to the inner surface 11 increases as the position moves away from the position of the slit 13 in the circumferential direction, and the bending moment increases by 1 from the slit 13.
It becomes maximum at an angle position of 80 degrees. On the other hand, in the present embodiment, since the thickness of each portion on the circumference of the cylindrical portion 10 also increases along the circumferential direction from the position of the slit 13, the bending rigidity also increases, and
It is maximum at the angular position of degrees. Accordingly, the bending deformation of each portion on the circumference of the cylindrical portion 10 becomes substantially uniform, and the deformed inner surface 11 is also kept substantially cylindrical, so that the outer surface of the cylinder outer cylinder and the inner surface 11 of the cylindrical portion 10 are maintained. Are also substantially uniform.

As described above, according to the present embodiment, the surface pressure between the inner surface 11 of the cylinder cooling sleeve and the cylinder outer cylinder 20 press-fitted into the inner surface 11 is substantially uniform, so that the cylinder outer cylinder 20 is uneven. This eliminates the risk of adversely affecting the operation of the cylinder due to the deformation of the cylinder, and the risk of galling damage due to a local increase in surface pressure during press-fitting. Further, since the inner surface 11 of the cylinder cooling sleeve and the outer cylinder 20 are in close contact with each other over the entire surface and heat transfer is uniformly performed over the entire surface, the cooling effect is improved.

In the above embodiment, the radial length of each cooling fin 15 is changed so that its tip is on the circumference concentric with the inner surface 11, whereby the inner surface 11 at the time of press-fitting and the outer surface of the cylinder are changed. Although the alignment of the cylinder 20 is facilitated, the present invention is not limited to this, and the cooling fins 15 may be implemented with a fixed length.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of a cylinder cooling sleeve according to the present invention.

FIG. 2 is a longitudinal sectional view of the embodiment of FIG.

FIG. 3 is a front view of a conventional cylinder cooling sleeve.

[Explanation of symbols]

10: cylindrical part, 11: inner surface, 12: outer surface, 13: slit, 15: cooling fin.

Claims (1)

(57) [Scope of request for utility model registration] 1. A tubular part 10 having a cylindrical outer surface 12.
And a number of cooling fins 15 integrally formed with the cylindrical portion 10 along the longitudinal direction of the outer surface 12 and protruding outward.
And a cylinder cooling sleeve formed of a single slit 13 formed over the entire length of a part of the circumference of the cylindrical portion 10 and separating the cylindrical portion into a C-shaped cross section. Eccentric the cylindrical inner surface 11 with respect to the outer surface 12 to change the thickness of the cylindrical portion in the circumferential direction,
A sleeve for cooling a cylinder, wherein the slit 13 is formed along the thinnest portion of the cylindrical portion 10.