A one-piece balance spring including a single strip wound on itself between an inner coil and an outer coil, the strip having a geometry such that when the angle of contraction of the balance spring has a value of 360 degrees, there is a substantially constant distance between each coil from the inner coil to the penultimate coil.

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>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.

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>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.

The present disclosure provides apparatus and methods for coupling an item to another item. The apparatus comprises a coupler mounted on the item and comprising a mating face having a plurality of catches thereon, the plurality of catches comprising at least one complementary pair of catches positioned and shaped to be engaged with corresponding catches of another coupler having an identical mating face when mating faces of two couplers are facewise engaged with and rotated relative to each other to align with each other. The coupler may be implemented as a floor plate of a magazine, as a clip, or in other forms.

Filtering pulleys have a hub adapted to be fixed to a rotating shaft, a ring assembled coaxial and rotationally free on the hub, and an elastic assembly arranged circumferentially with respect to the hub and the ring and interposed between a pair of first elements integral with the hub and between a pair of second elements integral with the ring. The elastic assembly includes an elastic element having a progressive rigidity increasing starting from a predetermined threshold value of the angle of relative rotation between the hub and the ring.

Torsional vibration damper for a drivetrain of a motor vehicle, having a primary element rotatable around a rotational axis and a secondary element rotatable relative to the primary element against an energy storage. The energy storage includes a helical compression spring unit. The helical compression spring unit is provided in a spring channel, and the helical compression spring unit includes an outer spring. The outer spring is formed as an arc spring and an inner spring is provided inside of the outer spring and virtually coaxial to the outer spring. The inner spring when disassembled from the helical compression spring unit is formed as a straight helical compression spring. The inner spring has a winding direction that is opposed to a winding direction of the outer spring and the inner spring when installed in the torsional vibration damper, is shorter than the outer spring by a value of x.

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>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.

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>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>Pa).

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>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.

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.