Compression coil spring device having discontinuous support structure

Abstract

In a compression coil spring device, suitable for use in a strut wheel suspension system, including a coil wire wound into a coil having an end turn, the end turn is adapted to be supported by a spring seat at one or a plurality of discrete points. This can be accomplished either by providing a plurality of projections on the coil wire along the length of the coil wire of the end turn or by providing a plurality of projections for supporting the end turn at one or a plurality of discrete points of the spring seat. Thus, the spring demonstrates a same property with regard to the centroid of contact pressure or line of action of the spring force, and the spring constant without regard to the spring load as long as the spring end is supported by the same discrete contact point or points. In other words, the changes in the number of effective turns depending on the magnitude of the load can be minimized so that the relationship between the load and compression stroke can be made substantially linear, and the change in the angle of the axis of the spring force can be minimized. Also, in the above structure, the end turn contacts the spring seat only at the predetermined projections, and this minimizes the variation in the spring property, frictional resistance between the contacting members and bending moment relating to individual coil springs.

Description

TECHNICAL FIELD [0001] The present invention relates to a compression coil spring device, and in particular to a compression coil spring device suitable for use in a strut wheel suspension system for motor vehicles. BACKGROUND OF THE INVENTION [0002] Helical compression springs or compression coil springs are used in a wide range of applications owing to the favorable spring properties of the springs of this type. A coil end often includes a closely wound turn so that the coil end provides a uniform contact surface. Grinding the end surface of a coil spring is also known as a means for providing a uniform contact surface. However, the entire contact surface of the closely wound turn and ground end may not contact an opposing member, such as a spring seat, but instead, they tend to contact the opposing member partially at unpredictable points, which can result in a varying spring property or varying relationship between the load and the compression stroke. Also the closely wound turn...

AI Technical Summary

Benefits of technology

[0014] Thus, the spring demonstrates a same property, with reference to the centroid of contact pressure or line of action of the spring force and the spring constant, without regard to the spring load as long as the spring end is supported by the same discrete contact point or points. In other words, the changes in the number of effective turns depending on the magnitude of the load can be minimized over a certain range so that the relationship between the load and compression stroke can be made substantially linear over this range, and the change in the angle of the axis of the spring force can be minimized. Also, in the above structure, the end turn contacts the spring seat only at the predetermined projections, and this minimizes the variation in the spring property, frictional resistance between the contacting members and bending moment relating to individual coil

Problems solved by technology

However, the entire contact surface of the closely wound turn and ground end may not contact an opposing member, such as a spring seat, but instead, they tend to contact the opposing member partially at unpredictable points, which can result in a varying spring property or varying relationship between the load and the compression stroke.

Also the closely wound turn and ground end are not effective in producing the spring force.

Also, because the part of the coil wire which is in contact with the spring seat is not capable of any further deflection and is therefore ineffective in increasing the spring force, an increase in the contacting part between the coil wire and the spring seat resulting from an increase in the spring load means a decrease in the number of effective turns of the coil spring.

In many applications, such changes in the spring property with the change in the spring load are not desirable.

For instance, in a strut wheel suspension system for motor vehicles, because the point of input of the force which pushes up the tire does not agree with the axial line of the linear

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