Patent ID: 12253134

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of a coil spring device according to the present invention is described with reference toFIGS.1toFIG.3.

A coil spring device1includes a main body spring11in which a wire rod W extends vertically in a spiral shape around a coil axis O and an insulator12which supports a lower end portion of the main body spring11from below the main body spring11. That is, the vertical direction is the direction of the coil axis O. The coil spring device1is used by being mounted on, for example, a shock absorber inserted into the main body spring11and a suspension device having a strut mount mounted on the upper end of the shock absorber or the like.

The main body spring11is an open-end coil spring in which an end portion w1of the wire rod W is vertically separated from the wire rod W adjacent to the end portion w1on the inside of the direction of the coil axis O. The cross-sectional shape of the wire rod W is the same over the entire length including the end portion w1. In the example shown in the drawings, the cross-sectional shape of the wire rod W is a circular shape.

Additionally, a closed-end coil spring in which the end portion w1of the wire rod W contacts and overlaps the wire rod W adjacent to the end portion w1on the inside of the direction of the coil axis O may be adopted as the main body spring11. In this configuration, the end portion w1of the wire rod W may be subjected to, for example, grinding to form a flat surface extending in the horizontal direction orthogonal to the vertical direction and facing outward in the vertical direction. The cross-sectional shape of the wire rod W may be, for example, a rectangular shape or the like.

The insulator12is made of an elastic material such as rubber. As shown inFIG.2, the insulator12has an arc shape extending around the coil axis O when viewed from the vertical direction. The insulator12extends over an angle range of 180° or more and 360° or less with respect to the coil axis O.

The insulator12is provided with a support groove13which extends around the coil axis O and into which the lower end portion of the main body spring11is fitted. The support groove13extends over an angle range of 180° or more and 360° or less with respect to the coil axis O. As shown inFIG.3, an adhesive layer16is provided between an inner surface13aof the support groove13and the lower end portion of the main body spring11, where the lower end portion of the main body spring11adheres to the inner surface13aof the support groove13.

The inner surface13aof the support groove13is formed in a concave curved shape curved along the outer peripheral surface of the wire rod W. The support groove13integrally opens toward one side in the circumferential direction around the coil axis O, upward, and outward in the radial direction (direction orthogonal to the direction of the coil axis O).

Additionally, as the support groove13, for example, a configuration in which the support groove opens toward both circumferential sides, a configuration in which the radial outside of the support groove is closed, or the like may be adopted.

The inner surface13aof the support groove13is provided with a plurality of spacer protrusions14which support the outer peripheral surface of the wire rod W.

The ratio of the volume of the spacer protrusion14occupying the gap between the inner surface13aof the support groove13and the outer peripheral surface of the wire rod W exceeds 10% and the ratio of the volume of the adhesive layer16occupying the gap is less than 90%. The volume of the spacer protrusion14also includes the volume of the internal space of the spacer protrusion14when the spacer protrusion14has a tubular shape.

The ratio of the volume of the spacer protrusion14occupying the gap between the inner surface13aof the support groove13and the outer peripheral surface of the wire rod W at the center portion in the gap in the circumferential direction around the coil axis O is larger than the ratio of the volume of the spacer protrusion14at the other portions in the gap in the circumferential direction. That is, the ratio of the volume of the adhesive layer16occupying the gap at the center portion in the gap in the circumferential direction is smaller rather than the ratio of the volume of the adhesive layer16occupying the gap at the other portions in the gap in the circumferential direction.

The center portion in the gap in the circumferential direction is a portion circumferentially sandwiched by the respective portions that are located on both circumferential sides of the circumferential center in the gap and separated by 5% or more and 45% or less of the entire circumferential length of the gap from the circumferential center in the gap (the circumferential center in the gap is a portion located at an equal distance from one end and the other end in the circumferential direction in the gap).

In the example shown in the drawings, the ratio of the volume of the spacer protrusion14occupying the gap gradually decreases as the distance in the circumferential direction from the center in the circumferential direction increases, and the ratio of the volume of the adhesive layer16occupying the gap gradually increases as the distance in the circumferential direction from the center in the circumferential direction increases. At the end portion in the circumferential direction in the gap, the ratio of the volume occupied by the spacer protrusion14is 10% or less and the ratio of the volume occupied by the adhesive layer16is 90% or more.

Additionally, the ratio of the volume of the spacer protrusion14occupying the gap may be the same in the entire area excluding the center portion in the circumferential direction in the gap or the entire area excluding the end portion in the circumferential direction in the gap. The ratio of the volume of the spacer protrusion14occupying the gap may exceed 10% in the entire area.

The difference between the ratio of the volume of the spacer protrusion14occupying the center portion in the circumferential direction in the gap and the ratio of the volume of the spacer protrusion14occupying the end portion in the circumferential direction in the gap is 80% or less.

If this difference exceeds 80%, the difference in the strength of the adhesive layer16between the center portion and the end portion in the circumferential direction becomes large, and the durability of the adhesive layer16may decrease.

The plurality of spacer protrusions14are formed to have the same size and shape. That is, the number of the spacer protrusions14per unit volume of the gap at the center portion in the circumferential direction is larger than that at the other portions in the gap in the circumferential direction. The plurality of spacer protrusions14are provided in the inner surface13aof the support groove13at intervals in the circumferential direction and at intervals in the radial direction. The plurality of spacer protrusions14are provided over the entire area in the inner surface13aof the support groove13.

Additionally, the number of the spacer protrusions14per unit volume of the gap may be equal over the entire area of the gap and the size of the spacer protrusion14located at the center portion in the circumferential direction may be larger than the size of the spacer protrusion14located at the other portions in the gap. Further, the plurality of spacer protrusions14may have different shapes.

As described above, according to the coil spring device1of this embodiment, the ratio of the volume of the spacer protrusion14occupying the gap between the inner surface13aof the support groove13and the outer peripheral surface of the wire rod W at the center portion in the gap in the circumferential direction is larger than that at the other portions in the gap in the circumferential direction. Thus, when a compression force in the vertical direction is applied to the main body spring11, the volume of the adhesive layer16between the lower end portion of the main body spring11and the inner surface13aof the support groove13at the center portion in the circumferential direction having a relatively low applied load becomes smaller. On the other hand, for example, the volume of the adhesive layer at the end portion in the circumferential direction having a relatively high applied load becomes larger and hence it is possible to ensure the strength at the end portion in the circumferential direction. Accordingly, it is possible to reduce the used adhesive amount and the cost while ensuring the adhesive strength between the lower end portion of the main body spring11and the inner surface13aof the support groove13.

Since the plurality of spacer protrusions14are formed to have the same size and shape, the plurality of spacer protrusions14can be easily formed and the outer peripheral surface of the wire rod W can be easily supported by the plurality of spacer protrusions14with little bias.

Additionally, the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the objective of the present invention.

In addition, the constituent elements in the above-described embodiment can be appropriately replaced with well-known constituent elements without departing from the objective of the present invention and the above-described embodiment and modified example may be appropriately combined.

Industrial Applicability

The present invention can be used in a coil spring device including a main body spring and an insulator having a support groove provided with a plurality of spacer protrusions.