Shift-drum speed change mechanism

Patent metadata

Field	Value
Publication number	US-9556958-B2
Application number	US-201514950977-A
Country	US
Kind code	B2
Filing date	Nov 24, 2015
Priority date	Nov 26, 2014
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

A shift-drum speed change mechanism includes a first drum spring biasing a first drum toward a first side in an axial direction, which is a side on which a first slider comes into contact with a first speed change member, a first fork spring biasing a first shift fork toward a second side in the axial direction, which is a side opposite to the first side in the axial direction, with a weaker biasing force than the first drum spring, and a first stopper member for the first drum, defining an end of movement of the first drum toward the first side in the axial direction.

First claim

What is claimed is:

1. A shift-drum speed change mechanism comprising: a first slider that is supported by a power transmission rotating shaft so as to be incapable of relative rotation and movable in an axial direction between first and second speed change members relatively rotatable relative to the power transmission rotating shaft, and is capable of selectively taking a first speed change position where the first slider is engaged with the first speed change member, a neutral position where the first slider is not engaged with any of the first and second speed change members, and a second speed change position where the first slider is engaged with the second speed change member; a first shift fork that is supported so as to be movable in the axial direction, and causes the first slider to move in the axial direction in accordance with its own movement in the axial direction; a first drum provided with a first guide groove into which a first engagement pin of the first shift fork is inserted; and an operation shaft supporting the first drum so as to be incapable of relative rotation and movable in the axial direction, wherein the operation shaft is operable around an axis so as to be capable of taking a neutral position as well as first and second speed change positions when rotated from the neutral position toward one side and the other side around the axis, respectively, and the first slider is placed at the neutral position, the first speed change position, and the second speed change position in accordance with operation of the operation shaft to the neutral position, the first speed change position, and the second speed change position, respectively,
the shift-drum speed change mechanism further comprising: a first drum spring biasing the first drum toward a first side in the axial direction, which is a side on which the first slider comes close to the first speed change member; a first fork spring biasing the first shift fork toward a second side in the axial direction, which is a side opposite to the first side in the axial direction, with a weaker biasing force than the first drum spring; a first stopper member for the first drum, defining an end of movement of the first drum toward the first side in the axial direction; and
the first guide groove having a neutral engagement part, a first-speed-change engagement part and a second-speed-change engagement part with which the first engagement pin is respectively engaged when the operation shaft is placed at the neutral position, the first speed change position and the second speed change position, and
the first guide groove having such a groove shape as to press the first engagement pin toward the first side in the axial direction by the rotational operation of the operation shaft from the neutral position to the first speed change position, not to press the first engagement pin along the axial direction by the rotational operation of the operation shaft from the neutral position to the second speed change position, and to allow the first shift fork to relatively move to the first drum between a reference position and a displaced position displaced from the reference position toward the second side in the axial direction when the operation shaft is placed at the second speed change position.

2. The shift-drum speed change mechanism according to claim 1 , further comprising a second stopper member for the first drum that defines an end of movement of the first drum toward the second side in the axial direction, and is disposed so as to provide a gap between the second stopper member for the first drum and the first drum in contact with the first stopper member for the first drum.

3. The shift-drum speed change mechanism according to claim 1 , further comprising: third and fourth speed change members supported so as to be relatively rotatable around the axis relative to the power transmission rotating shaft; a second slider that is supported by the power transmission rotating shaft so as to be incapable of relative rotation around the axis and movable in the axial direction between the third and fourth speed change members, and is capable of selectively taking a third speed change position where the second slider is engaged with the third speed change member, a neutral position where the second slider is not engaged with any of the third and fourth speed change members, and a fourth speed change position where the second slider is engaged with the fourth speed change member; a second shift fork that is supported so as to be movable in the axial direction, and causes the second slider to move in the axial direction in accordance with its own movement in the axial direction; a second drum that is supported by the operation shaft so as to be incapable of relative rotation around the axis and movable in the axial direction, and is provided with a second guide groove into which a second engagement pin of the second shift fork is inserted; a second drum spring biasing the second drum toward the first side in the axial direction; a second fork spring biasing the second shift fork toward the second side in the axial direction with a weaker biasing force than the second drum spring; and a first stopper member for the second drum, defining an end of movement of the second drum spring toward the first side in the axial direction, wherein
the operation shaft takes a third speed change position when rotated from the first speed change position toward one side around the axis and a fourth speed change position when rotated from the second speed change position toward the other side around the axis, in addition to the neutral position, the first speed change position, and the second speed change position;
the first guide groove has, in addition to the neutral engagement part, the first-speed-change engagement part and the second-speed-change engagement part, a third-speed-change engagement part, and a fourth-speed-change engagement part with which the first engagement pin is engaged when the operation shaft is placed at the third speed change position and the fourth speed change position, respectively;
the second guide groove has a neutral engagement part, a first-speed-change engagement part, a second-speed-change engagement part, a third-speed-change engagement part, and a fourth-speed-change engagement part with which the second engagement pin is engaged when the operation shaft is placed at the neutral position, the first speed change position, the second speed change position, the third speed change position, and the fourth speed change position, respectively;
the third-speed-change engagement part of the first guide groove is disposed adjacent to the first-speed-change engagement part on an opposite side of the first-speed-change engagement part from the neutral engagement part, and is engaged with the first engagement pin such that the first shift fork is retained at a central reference position with respect to the axial direction relative to the first drum;
the fourth-speed-change engagement part of the first guide groove is disposed adjacent to the second-speed-change engagement part on an opposite side of the second-speed-change engagement part from the neutral engagement part, and is engaged with the first engagement pin such that the first shift fork is retained at the central reference position with respect to the axial direction relative to the first drum;
the first-speed-change engagement part, the neutral engagement part, and the second-speed-change engagement part of the second guide groove are engaged with the second engagement pin such that the second shift fork is retained at a central reference position with respect to the axial direction relative to the second drum;
the third-speed-change engagement part of the second guide groove is disposed adjacent to the first-speed-change engagement part on an opposite si

Assignees

• Kanzaki Kokyukoki Mfg Co Ltd

Inventors

• Tsukamoto Michio
• Nishimoto Shuji
• Murashima Daisuke

Classifications

• F16H61/26

  Generation or transmission of movements for final actuating mechanisms · CPC title

• F16H63/18 Primary

  the final actuating mechanism comprising cams · CPC title

• F16H2306/00

  Shifting · CPC title

• F16H57/0018 Primary

  Shaft assemblies for gearings (camshafts with single track cams F16H53/02) · CPC title

• F16H63/38

  Detents · CPC title