JP3316774B2 - gas spring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas spring, and more particularly to a gas spring suitable for use in opening and closing a door such as a back door of an automobile.

[0002]

2. Description of the Related Art An example of a conventional gas spring will be described with reference to FIG.

[0003] Reference numeral 1 denotes a cylinder, and a cap 2 is fixed to the upper end of the cylinder 1 by welding. A piston rod 3 is inserted into the cylinder 1, and stepped portions 3a and 3b are provided at one end of the piston rod 3. A piston 4 is attached to the stepped portion 3a so as to be movable by a predetermined amount in the axial direction.
The washer 5 is fixed to the stepped portion 3b by caulking the caulked portion 3c of the piston rod 3. The other end of the piston rod 3 protrudes out of the cylinder 1 through a rod guide 8 having a stopper 6 and a seal 7 fixed by the curled portions 1a and 1b of the cylinder 1. The other end of the piston rod 3 is provided with a groove 3d.
The mounting portion 9 is fixed to the other end of the piston rod 3 such that a is fitted into the groove 3d.

A single-diameter coil spring 10 is provided at an upper end in the cylinder 1. The upper end of the spring 10 is fitted and held in the small diameter portion 11a of the spring holding member 11,
The cylinder 1 is held by the interference between the large diameter portion 11b of the holding member 11 and the inner circumference 1c of the cylinder 1. Spring 10
Is in contact with the washer 5 when the piston rod 3 enters the cylinder 1, and the spring 10 is compressed by the penetration of the piston rod 3, giving the urging force in the extension direction to the piston rod 3 and shortened most. Strengthens the stretching force when in the state. At the same time, the spring 10 is
From impacting on the upper end of the cylinder 1.

The cap 2 is provided with a hole 2a,
Pressurized gas is sealed into the internal chamber 12 of the cylinder 1 through the hole 2a. After the sealing, the plug 13 is welded, and the mounting portion 14 is fixed thereon by welding.

The outer periphery of the piston 4 has an O.
A ring 15 is inserted, and an orifice formed in the inner periphery of the piston 4 is formed by a groove 4b extending in the axial direction and a small hole 4c obliquely extending in communication with the groove 4b. The upper chamber and the lower chamber of the internal chamber 12 communicate with each other through the outer circumference of the orifice and the washer 5 and the inner circumference 1c of the cylinder 1.

[0007]

However, in the above conventional gas spring, the spring 10 is connected to the cylinder 1.
Because the holding member 11 is used to hold the inside of the cylinder, various types of holding members 11 must be prepared according to the difference in the inner diameter of the cylinder 1 and the wire diameter and the inner diameter of the spring 10. There was a problem that the score increased. In addition, it is necessary to assemble the spring 10 and the holding member 11, which causes an increase in the number of assembling steps. The present invention has been made in view of the above problems, and has as its object to provide a gas spring that can easily hold a spring on a cylinder by eliminating the spring holding member.

[0008]

According to the present invention, there is provided a cylinder filled with a gas, a piston slidably inserted into the cylinder, and one end attached to the piston and the other end external to the cylinder. A gas spring consisting of a piston rod protruding into the cylinder and a coil spring provided to be extendable and contractible in the cylinder, one end of which is held on the cylinder side, and the other end of which can contact the piston side. A coating made of a material softer than the material of the cylinder is partially provided at one end of the spring, the outer diameter of the coating is larger than the inner diameter of the cylinder, and the coating is fitted to the inner periphery of the cylinder. And

[0009]

According to the above construction, when the coating portion of the coil spring is fitted to the inner circumference of the cylinder, one end of the coil spring is connected to the inner circumference of the cylinder by the interference between the outer circumference of the coating portion and the inner circumference of the cylinder. Can be held around.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. Note that the same members as those in the related art are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, a coil spring 16 having a single diameter is provided at the upper end of the cylinder 1 using only a wire. The spring 16 is covered with a film 17 made of a material softer than the material of the cylinder 1, the wire at the upper end (one end) being partially covered, that is, for about one and a half turns from the upper end. A portion 16a and a non-film portion 16b not covered with the film 17 are formed.
The film 17 can be formed by dip-coating a synthetic resin such as polyvinyl chloride or synthetic rubber or a resin such as natural rubber.

In order for the outer periphery of the coating portion 16a of the spring 16 and the inner periphery 1c of the cylinder 1 to be fitted with a tight fit, the dimensions of the spring 16 are, as shown in FIG. The diameter d ₁ is larger than the single outer diameter d _{2 of the} non-film portion 16 b by the thickness of the film 17. The relationship between the outer diameters d ₁ and d ₂ and the inner diameter d _{3 of the} cylinder 1 (see FIG. 1) is d ₁ > d ₃ > d ₂ .

[0013] This relationship, spring 16, when fitted with the inner periphery 1c of the cylinder 1, since the outer diameter d ₁ of the coating portion 16a is larger than the inner diameter d ₃ of the cylinder 1, among the film portion 16a has a cylinder 1 It is fitted and held on the circumference 1c with a tight allowance. At the same time, the outer diameter d ₂ of the non-film portion 16b
Is smaller than the inner diameter d _{3 of the} cylinder 1,
6b does not always contact the inner circumference 1c of the cylinder 1 and the sliding resistance when the spring 16 expands and contracts does not increase.

The coating 16a of the spring 16
Since a resin of a material softer than the material of the cylinder 1 is used as the film 17 of the spring 16, the film portion 16a of the spring 16 is used.
The inner circumference 1c of the cylinder 1 can be prevented from being damaged at the time of fitting into the inner circumference 1c of the cylinder 1 or at the time of expansion and contraction of the spring 16 due to contact and separation of the washer 5. Also, due to the elasticity of the resin, the upper end of the spring 16 is
Can be surely held on the inner circumference 1c of the head.

With the above-described structure, the outer periphery of the film portion 16a provided partially on the coil spring 16 and the inner periphery 1c of the cylinder 1 are tightened without using a stopper as in the prior art. The upper end (one end) of the spring 16 can be easily held on the inner circumference 1c of the cylinder 1.

In the above-described embodiment, the wire at the upper end of the coil spring 16 is partially covered with the film 17 over about one and a half turns from the upper end, but the film portion 16a covered with the film 17 is approximately one turn. If the number of turns of the spring 16 is large, the number of turns may be two, two and a half, three, or three and a half. However, when the number of the coating portions 16a increases, the sliding resistance at the time of the expansion and contraction of the spring 16 increases. Therefore, the coating portion 16a has a range of 1 to 3 turns, more preferably 1 to 2 turns. It is desirable. In any case, by forming a film partially on one end of the coil spring 16, only the film portion 16a is applied to the cylinder 1
Can be held.

Further, in the above embodiment, the coil spring 16 is a coil spring having a single diameter by using only the wire rod. However, the present invention is not limited to this, and a coil spring having a truncated cone shape may be used. In this case, a coating portion 16a is formed on the large diameter portion of the truncated cone, and the coating portion 16a
Should be fitted to the inner circumference 1c of the cylinder 1.

Further, in the above embodiment, the coil spring 16 is provided at the upper end of the cylinder 1, but may be provided at the lower end of the cylinder 1, that is, on the stopper 6 side. in this case,
The film portion 16a may be located on the side of the coil spring 16 that contacts the stopper 6.

In the above embodiment, the washer 5 is used as the member that contacts the coil spring 16.
May directly contact the coil spring 16.

[0020]

According to the present invention, when the coating portion of the coil spring is fitted to the inner periphery of the cylinder, the above-described configuration allows the outer periphery of the coating portion and the inner periphery of the cylinder to be tightly tightened. One end of a spring can be held on the inner periphery of the cylinder. Therefore, since the spring holding member as in the related art does not have to be used, the number of components can be reduced, and assembling of the spring and the holding member is not required, so that the number of assembling steps can be reduced. Also, since the material of the spring film is softer than the material of the cylinder, the inner surface of the cylinder may be damaged when the spring film is fitted to the inner periphery of the cylinder or when the spring expands and contracts. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a gas spring of the present invention.

FIG. 2 is an enlarged view of a coil spring used for the gas spring of the present invention.

FIG. 3 is a sectional view showing a conventional gas spring.

[Explanation of symbols]

1 Cylinder 3 Piston rod 4 Piston 16 Coil spring 16a Film part d ₁ Outer diameter of film part d ₃ Inner diameter of cylinder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16F 9/00 F16F 1/06 F16F 9/58

Claims (1)

(57) [Claims] 1. A cylinder filled with gas, a piston slidably inserted into the cylinder, a piston rod having one end attached to the piston and the other end protruding outside the cylinder, A gas spring comprising a coil spring which is provided in a cylinder so as to be able to expand and contract and has one end held on the cylinder side and the other end capable of abutting on the piston side; A gas spring, wherein a coating of a softer material is partially provided, an outer diameter of the coating is larger than an inner diameter of the cylinder, and the coating is fitted to an inner periphery of the cylinder.