Suncall Corporation

Toyota Jidosha Kabushiki Kaisha

Denso Corporation

Ryuji Kishihara

Seiji Okamura

Keiichiro Teratoko

Naoya Wada

Akio Kidooka

Yuu Yokoyama

Takao Suzuki

Tadashi Saito

Akira Hori

Futoshi Fujiwara

In the coil spring of the present invention, a helical space defined by a space between coils has a first end region whose space is increased as it extends towards the other side in the axial direction from a first reference point where the space is zero, a reference region whose space is set at a reference value L (L&#x3e;0), and a second end region whose space becomes narrow as it extends toward the other side in the axial direction and zero at a second reference point. The first end region is configured such that the number of turns of the helical space is greater than 1 and the space between coils in a terminal position is greater than the reference value L. The helical space has a first transitional region between the terminal position of the first end region and the reference region, the first transitional region being configured so that the distance of space between coils is reduced from the terminal position of the first end region along the helical shape of the helical space toward the other side in the axial direction and becomes the reference value L.

Coil spring

A coil spring of this invention includes a first end coil part with a first bearing surface facing to the first side in the axial direction, a second end coil part with a second bearing surface facing to the second side in the axial direction and a central coil part connecting the first and second end coil parts. A displacement length in the axial direction from the outer end portion until the inner end portion of the first end coil part is a thickness of a spring wire forming the coil spring so that a space between the outer end portion of the first end coil part and an inner end portion of the central coil part is zero, and a displacement length in the axial direction between the outer end portion of the first end coil part and a point away along the circumferential direction from the outer end portion toward the inner end portion of the first end coil part by a half of turn around the axial line is less than a half of the thickness of the spring wire.

In the coil spring of the present invention, a helical space defined by a space between coils has a first end region whose space is increased as it extends towards the other side in the axial direction from a first reference point where the space is zero, a reference region whose space is set at a reference value L (L&#x3e;0), and a second end region whose space becomes narrow as it extends toward the other side in the axial direction and zero at a second reference point. The first end region has a first end outer part and a first end inner end. In a case where a pitch angle of the space between coils that causes the displacement of the space between coils per turn of the helical space to be L is a reference pitch angle Pa, the pitch angle in the first end outer part is set at Pa while the pitch angle in the first end inner part is set at Pb (Pb&#x3e;Pa).

A method includes a spiral forming step causing a substantially linear elongated member, conveyed toward one side in a longitudinal direction of the elongated member by a pair of conveying rollers, to be engaged at one side in a second direction with a pressing member movable in the second direction so that a spiral body including the fixed coil part, the first movable coil part and the second movable coil part is formed from the linear elongated member. The spiral forming step is configured to control the position of the pressing member with respect to the second direction, based on a signal from a rotational speed sensor detecting the rotational speed of the conveying roller, a relationship between a position in the longitudinal direction of the elongated member that is engaged with the pressing member and the position in the circumferential direction after the spiral body is formed.

Spiral spring manufacturing method

At least a first movable coil part of a plurality of movable coil parts that is in the innermost place in the radial direction does not come into contact with both the fixed coil part, which is radially adjacent inwardly, and a second movable coil part, which is radially adjacent outwardly, at the same place in the circumferential direction while coming into contact with only one of the fixed coil part and the second movable coil part in a plurality of places that are circumferentially displaced, when the spiral spring is in an elasticity retaining state reached from a free length state by elastic deformation in the diameter-reducing direction.

Spiral spring

A sealing region where a valve seat and an outer peripheral surface of a enlarged diameter portion of a flare portion are contacted to each other is configured so that an end on a side opposite a combustion chamber is positioned at a position same as or on a side away from the combustion chamber than an end on a side close to the combustion chamber of a connecting region where a lid member and an inner peripheral surface of the enlarged diameter portion are connected with respect to the axis line direction.

Growing community of inventors

Kyoto, Japan

Ryuji Kishihara