JPH0615144Y2 - Cylindrical spring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a cylindrical spring.

[Conventional technology]

On the outer peripheral surface of the thin hollow cylindrical body is provided with a slit group consisting of a pair of circumferential slits formed point-symmetrically with respect to the axis of the thin hollow cylindrical body, the slit group in the axial direction of the thin hollow cylindrical body A plurality of slits are formed at equal intervals, and the slits of adjacent slit groups are displaced from each other by 90 degrees in the circumferential direction of the thin hollow cylindrical body. It is known.

However, if the widths of the slits in each slit group are all equal in this way, excessive stress is generated in the thin hollow cylinder portion forming the outermost slit in the axial direction of the thin hollow cylinder body, and the cylindrical spring is damaged. There is a problem of doing. This will be briefly described with reference to FIG. FIG. 7 (A) shows one end of the cylindrical spring, and FIG. 7 (B) shows a case where an axial load P is applied to the cylindrical spring. As shown in FIG. 7 (A), the cylindrical spring comprises a thin hollow cylindrical body a, and a slit group consisting of a pair of slits b and a slit group consisting of a pair of slits c on the outer peripheral surface of the thin hollow cylindrical body a. , A slit group including a pair of slit groups d is formed. Each of these slits b, c, d has the same width. When an axial load P is applied to the cylindrical spring, the upper wall surface and the lower wall surface of each slit b, d are curved inward, and finally, as shown in FIG. Comes into contact with the central portion of the lower wall surface. However, even if the axial load P is applied to the cylindrical spring, the upper wall surface of the slit b located on the outermost side does not curve, but only the lower wall surface curves inward. Therefore, each slit c,
Even if the central portion of the upper wall surface and the central portion of the lower wall surface contact with each other, the central portion of the upper wall surface and the central portion of the lower wall surface of the slit b do not contact each other. Next, when the axial load P further increases, the central portion of the upper wall surface and the central portion of the lower wall surface of the slit b come into contact with each other, but the deformation amount of the thin hollow cylindrical portion a ′ forming the lower wall surface of the slit b is different from that of the other portion. However, there is a problem in that the thin hollow cylindrical body portion a ′ is excessively stressed and damaged.

Therefore, conventionally, a slit group consisting of N circumferential slits formed point-symmetrically with respect to the axis of the thin hollow cylinder is provided on the outer peripheral surface of the thin hollow cylinder, and the slit group is a thin hollow cylinder. A plurality of slits are formed in the axial direction of the thin hollow cylinder at substantially equal intervals, and the slits of the adjacent slit groups are 180 degrees apart from each other in the circumferential direction of the thin hollow cylindrical body.
A cylindrical spring in which the slits of the outermost slit group in the axial direction of the thin hollow cylindrical body are narrower in width than the slits of the other slit groups is known. is there. (Japanese Patent Laid-Open No. 50-11685
7 and JP-A-62-4902).

[Problems to be solved by the device]

By the way, in these cylindrical springs, the thin-walled hollow cylindrical body end portion between each slit of the outermost slit group and the end face of the thin-walled hollow cylindrical body in the axial direction of the thin-walled hollow cylindrical body does not function as a spring, Therefore, in order to make the overall length of the cylindrical spring as short as possible, it is necessary to make the width of the thin hollow cylindrical body portion as short as possible in terms of strength.

However, in the above-mentioned known cylindrical spring, the width of the end portion of the thin hollow cylindrical body is formed to be the same as the width between the slits of the adjacent slit groups or larger than the width between the slits of the adjacent slit groups. Therefore, these cylindrical springs have a problem that the total length of the cylindrical spring becomes long.

[Means for Solving the Problems]

In order to solve the above problems, according to the present invention, N (N is a natural number) circumferential slits are formed on the outer peripheral surface of the thin hollow cylindrical body in point symmetry with respect to the axis of the thin hollow cylindrical body. A plurality of slit groups are formed at substantially equal intervals in the axial direction of the thin-walled hollow cylinder, and the slits of adjacent slit groups are 180 degrees apart from each other in the circumferential direction of the thin-walled hollow cylinder. In the cylindrical spring, the lateral width of each slit of the slit groups located at the outermost side in the axial direction of the thin hollow cylindrical body is narrower than the lateral widths of the slits of the other slit groups. The width between each slit in the outermost slit group in the axial direction and the end surface of the thin hollow cylinder is formed to be narrower than the width between the slits in the adjacent slit group. .

[Action]

The width of the thin hollow cylinder is narrower than the width of the slits between the slits located at the outermost side in the axial direction of the thin hollow cylinder and the end face of the thin hollow cylinder by narrowing the width between the slits. The total length of the spring becomes shorter.

〔Example〕

Referring to FIGS. 1 and 2, the cylindrical spring 1 is composed of a thin-walled hollow cylindrical body 2, and the thin-walled hollow cylindrical body 2 has a substantially uniform wall thickness over its entire length. Therefore, the thin hollow cylinder 2
Has a uniform inner and outer diameter over its entire length. On the outer peripheral surface of the thin hollow cylindrical body 2, a slit group including a pair of circumferential slits 3 extending in the circumferential direction of the thin hollow cylindrical body 2,
A slit group consisting of a pair of circumferential slits 4, a slit group consisting of a pair of circumferential slits 5, a slit group consisting of a pair of circumferential slits 6, a slit group consisting of a pair of circumferential slits 7, Circumferential slit 8
And a slit group consisting of a pair of circumferential slits 9 are formed, and each slit group is formed at substantially equal intervals in the axial direction of the thin hollow cylindrical body 2. Each slit 3, 4, 5, 6, 7, 8, 9 extends through the thin hollow cylindrical body 2 from the outer peripheral surface of the thin hollow cylindrical body 2 to the inner peripheral surface thereof.
Between the slits 5, between the slits 6, between the slits 7, between the slits 8, between the slits 9, 10, 11, 12, 13, 1 respectively.
4,15,16 are formed. Each slit 3, 4, 5, 6,
Reference numerals 7, 8 and 9 are arranged point-symmetrically with respect to the axis of the thin hollow cylindrical body 2. Therefore, the pair of slits 3, the pair of slits 4, the pair of slits 5, the pair of slits 6, the pair of slits 7, the pair of slits 8 and the pair of slits 9 are in the same angular range with respect to the axis of thin hollow cylindrical body 2, respectively. It extends over. Further, in the embodiment shown in FIGS. 1 and 2, all the slits 3, 4, 5, 6, 7, 8, 9 have the same circumferential length, and the slits of the adjacent slit groups are thin hollow cylindrical bodies 2 Angle divided by the number N of slits in each slit group in the circumferential direction of, ie, 180/2 = 90
Deviated from each other by degrees. As shown in FIG. 1, the widths of the other slits 4, 5, 6, 7, and 8 except the slits 3 and 9 located on the outermost side in the axial direction of the thin-walled hollow cylindrical body 2 are substantially equal to each other, and Positioned slit 3,9
Is formed narrower than the widths of the other slits 4, 5, 6, 7, and 8.

That is, as shown in FIG. 6A showing an enlarged view of a part of FIG.
Is formed narrower than the width m of the other slits 4, 5, 6, 7, and 8. Further, the width n between the outermost slits 3 and 9 and the end faces of the thin hollow cylindrical body 2 is formed to be narrower than the width o between the slits 3, 4, 5, 6, 7, 8, and 9. . If the width 1 of the slits 3 and 9 is narrowed,
When an axial load P is applied to the cylindrical spring 1 as shown in FIG. (B), the outermost portion is formed when the central portions of the upper wall surface and the central portion of the lower wall surface of the slits 4, 5, 6, 7, 8 come into contact with each other. The center portion of the upper wall surface and the center portion of the lower wall surface of the slits 3 and 9 located at are in contact with each other. As a result, even if the axial load P is further increased, only the thin-walled hollow cylindrical body portion 2a forming the slits 3 and 9 is not excessively deformed, thus preventing the cylindrical spring 1 from being damaged. be able to. In addition,
Theoretically, the width 1 of the slits 3, 9 should be changed to the slits 4, 5,
Slits 4, 5, when the width m of 6, 7, 8 is halved
Slits 3 and 9 when the upper and lower wall surfaces of 6, 7 and 8 contact each other
Although the upper and lower wall surfaces of the slits 3 and 9 come into contact with each other, even if the width 1 of the slits 3, 9 is made larger than 1/2 of the width m of the slits 4, 5, 6, 7, 8, the thin hollow cylindrical portion 2a It has the effect of suppressing excessive deformation.

Further, as shown in FIG. 6 (B), when the axial load P is applied to the cylindrical spring 1, the slit 3 positioned at the outermost side is formed.
The upper wall surface and the lower wall surface of the slit 9 are not deformed, so that the function between the slits 3 and 9 and the end surface of the cylindrical spring 1 is not fulfilled. Therefore, in order to make the overall length of the cylindrical spring 1 as short as possible, the width n between the slits 3, 9 and the end surface of the cylindrical spring 1 is n.
It is preferable to make the width as narrow as possible in terms of strength. Therefore, as described above, in the embodiment shown in FIGS. 1, 2 and 6, the width n between the slits 3 and 9 and the end face of the cylindrical spring 1 is set to the slit 3. , 4, 5, 6, 7, 8, 9 are formed to be narrower than the width o. Further, from the viewpoint of making the overall length of the cylindrical spring 1 as short as possible, narrowing the lateral width 1 of the slits 3, 9 also contributes to shortening the overall length of the cylindrical spring 1.

3 and 4 show another embodiment of the cylindrical spring. With reference to FIGS. 3 and 4, in this embodiment, a slit group consisting of three circumferential slits 20 extending in the circumferential direction of the thin hollow cylindrical body 2 on the outer peripheral surface of the thin hollow cylindrical body 2,
Slit group consisting of three circumferential slits 21, slit group consisting of three circumferential slits 22, slit group consisting of three circumferential slits 23, slit consisting of three circumferential slits 24 Group, slit group consisting of three circumferential slits 25, slit group consisting of three circumferential slits 26, three circumferential slits 2
A slit group consisting of 7 is formed, and each slit group is formed at substantially equal intervals in the axial direction of the thin hollow cylindrical body 2. In addition, between the slits 20 and the slit 2
1, slit 22, slit 23, slit 24
Bridge portions 28, 29, 30, 31, 32, 33, 34, 35 are formed between the slits 25, the slits 26, and the slits 27, respectively. The slits 20, 21, 22, 23, 24, 25, 26, 27 are arranged point-symmetrically with respect to the axis of the thin hollow cylindrical body 2. Therefore, three slits 20, three slits 21, three slits 22, three slits 23, three slits 2
4, 3 slits 25, 3 slits 26 and 3
Each of the slits 27 extends over an equal angle range with respect to the axis of the thin hollow cylindrical body 2. Further, in the embodiment shown in FIGS. 3 and 4, all slits 20, 21, 22, 23,
The lengths of 24, 25, 26, 27 in the circumferential direction are equal, and the slits of adjacent slit groups are the angles obtained by dividing 180 degrees by the number N of slits in each slit group in the circumferential direction of the thin hollow cylindrical body 2, that is, 180/3 = 60 degrees offset from each other. Third
As shown in the figure, the widths of the other slits 21, 22, 23, 24, 25, 26 are almost the same except for the slits 20, 27 which are located on the outermost side in the axial direction of the thin hollow cylindrical body 2 and are on the outermost side. The width of the slits 20 and 27 located is the other slits 21, 22, 23,
It is formed narrower than the width of 24, 25, 26. Also in this embodiment, it is possible to prevent the cylindrical spring 1 from being damaged because the widths of the slits 20 and 27 located at the outermost sides are narrow.

FIG. 5 shows still another embodiment of the cylindrical spring. The fifth
In the figure, the same components as those in FIG. 1 are indicated by the same reference numerals with dashes. In this embodiment, each slit 3 ',
The horizontal widths of 4 ', 5', 6 ', 7', 8 ', 9'are widest in the center of the slit and gradually become narrower toward both ends of the slit. In this embodiment, compared with the embodiment shown in FIG. 1, each slit 3 ', 4', 5 ', 6', 7 ', 8',
Since the width of the central portion of 9'can be widened, the displacement stroke of the cylindrical spring 1 can be increased.

FIG. 8 shows a case where the cylindrical spring 1 according to the present invention is used in a piezoelectric actuator. Referring to FIG. 8, the piezoelectric actuator 40 includes an actuator housing 42 having a piston hole 41 formed therein and a piston hole 41.
A piston 43 slidably inserted therein, an end plate 44 covering the top of the actuator housing 42, and an end plate 44.
An end plate holder 45 for fixing the actuator to the top of the actuator housing 42, and a synthetic resin cap 46 covering the upper end of the end plate 44.

A piezo-piezoelectric element 47 in which a large number of piezoelectric element plates are laminated is inserted between the piston 43 and the end plate 44, and a variable volume chamber 48 defined by the lower end surface of the piston 43 is formed in the piston hole 41 below the piston 43. To be done. The variable volume chamber 48 is filled with fuel used for an internal combustion engine, for example, and the variable volume chamber 48 is connected to a cylinder chamber (not shown) for controlling fuel injection via a fuel passage 49, for example. A cylindrical spring 1 that constantly urges the piston 43 upward is inserted between the piston 43 and the actuator housing 42, and the cylindrical spring 1 is fitted on the circumferential outer peripheral surface of the piston 43.

When the piezoelectric element 47 is charged with electric charge, the piezoelectric element 47 expands in the axial direction, and as a result, the volume of the variable volume chamber 48 decreases. On the other hand, when the electric charge charged in the piezoelectric element 47 is discharged, the piezoelectric element 47 is discharged.
Contracts axially, resulting in an increase in the volume of variable volume chamber 48.

[Effect of device]

By forming the width between each slit of the slit group located on the outermost side in the axial direction of the thin hollow cylinder and the end face of the thin hollow cylinder narrower than the width between the slits of the adjacent slit groups, The overall length of the cylindrical spring can be shortened without affecting the spring function.

[Brief description of drawings]

1 is a side view of a cylindrical spring, FIG. 2 is a sectional view taken along line II-II of FIG. 1, FIG. 3 is a side view of another embodiment of the cylindrical spring, and FIG. FIG. 5 is a sectional view taken along line IV-IV of FIG. 5, FIG. 5 is a side view of still another embodiment of the cylindrical spring, and FIG.
1 is an enlarged view of a part of the cylindrical spring shown in FIG. 1, FIG. 7 is a side view of a conventional cylindrical spring, and FIG. 8 is a side sectional view of a piezoelectric actuator. 1 ... Cylindrical spring, 2 ... Thin hollow cylinder, 3,4,5,6,7,8,9,20,21,22,23,24,25,26,2
7,3 ', 4', 5 ', 6', 7 ', 8', 9 '... slits, 10,11,12,13,14,15,16,28,29,30,31,32,33 , 34,35 ... Bridge section.

Claims (1)

[Scope of utility model registration request] 1. A slit group comprising N (N is a natural number) circumferential slits formed point-symmetrically with respect to the axis of the thin hollow cylinder on the outer peripheral surface of the thin hollow cylinder,
A plurality of the slit groups are formed at substantially equal intervals in the axial direction of the thin hollow cylinder, and the slits of adjacent slit groups are displaced from each other by 180 / N degrees in the circumferential direction of the thin hollow cylinder. In a cylindrical spring in which the width of each slit of the slit group located on the outermost side in the axial direction of the hollow cylindrical body is narrower than the width of the slits of the other slit groups, the outermost position is formed in the axial direction of the thin hollow cylindrical body. A cylindrical spring in which the width between each slit of the slit group and the end surface of the thin hollow cylinder is formed to be narrower than the width between the slits of the adjacent slit group.