Speed change apparatus for power unit

Patent metadata

Field	Value
Publication number	US-2016281822-A1
Application number	US-201615079051-A
Country	US
Kind code	A1
Filing date	Mar 24, 2016
Priority date	Mar 27, 2015
Publication date	Sep 29, 2016
Grant date	—

Abstract

A cylindrical shift drum is rotatable around a third rotational axis. The cylindrical shift drum includes at least one lead groove in an outer circumferential surface of the cylindrical shift drum. A shift fork shaft extending in parallel to the third rotational axis is disposed opposite to the outer circumferential surface. At least one shift fork includes a main portion slidably supported by the shift fork shaft and a pin portion rotatably supported by the main body portion. The main body portion includes a fork portion to be engaged with at least one shifter gear. The pin portion is inserted in one of the at least one lead groove. The cylindrical shift drum is to be rotated to guide the pin portion along the one of the at least one lead groove to move the at least one shift fork to shift the at least one shifter gear.

First claim

What is claimed is:

1 . A speed change apparatus for a power unit, comprising:
a main shaft on which a plurality of driving gears are supported; a counter shaft on which a plurality of driven gears are supported; shifter gears included in the driving gears and the driven gears; a cylindrical shift drum formed with lead grooves in an outer circumferential surface thereof; a plurality of shift forks each provided with a fork portion and a pin portion, the fork portion being engaged with the shifter gears, and the pin portion being locked in the lead groove of the shift drum; and a shift fork shaft disposed in parallel to an axial direction of the shift drum and supporting the shift forks in an axially movable manner, gear shift being established by a process in which the shift forks guided by the lead groove of the shift drum and moved in the axial direction moves the shifter gears in the axial direction, wherein the shift forks each includes a main body portion which is provided with the fork portion, and the pin portion of each of the shift forks is provided as a separate body from the main body portion and is rotatably supported by the main body portion.

2 . The speed change apparatus for a power unit according to claim 1 , wherein the pin portion is rotatably supported by the main body portion through a bearing member.

3 . The speed change apparatus for a power unit according to claim 2 ,
wherein the main body portion includes a shaft insertion hole through which the shift fork shaft is passed; and an axial center line of the pin portion is positionally deviated from and not overlapping with a line interconnecting a center of the shaft insertion hole and an axial center of the shift drum, as viewed along the axial direction of the shift drum.

4 . The speed change apparatus for a power unit according to claim 2 ,
wherein the main body portion includes a pin insertion hole through which the pin portion is passed; the pin insertion hole includes
a bearing mounting portion to which to mount the bearing member, an enlarged diameter portion which is provided at one end of the pin insertion hole and is enlarged in inside diameter as compared with the bearing mounting portion, and a step portion connecting the bearing mounting portion and the enlarged diameter portion;
the pin portion includes
a shaft portion, and a flange portion which is provided at a part of the shaft portion and is enlarged in diameter as compared with an outside diameter of the shaft portion; and
the pin portion passed through the pin insertion hole is mounted to the main body portion by a structure in which the flange portion is put in contact with the step portion and in which a retaining ring is provided on an opposite side of the flange portion from the step portion.

5 . The speed change apparatus for a power unit according to claim 3 , wherein the main body portion of the shift fork is formed with a substantially cylindrical extension portion where an opening end portion of the shaft insertion hole extends along the shift fork shaft in the axial direction of the shift fork shaft.

6 . A speed change apparatus for a power unit, comprising:
a main shaft rotatable around a first rotational axis to be driven by an engine; at least one driving gear supported on the main shaft to be rotated with the main shaft; a counter shaft rotatable around a second rotational axis substantially parallel to the first rotational axis; at least one driven gear supported on the counter shaft to be rotated with the counter shaft, each of the at least one driven gear to be engaged with one of the at least one driving gear; at least one of the at least one driving gear and the at least one driven gear including at least one shifter gear movable along the first rotational axis or the second rotational axis; a cylindrical shift drum rotatable around a third rotational axis substantially parallel to the second rotational axis to be driven, the cylindrical shift drum including at least one lead groove in an outer circumferential surface of the cylindrical shift drum; a shift fork shaft disposed opposite to the outer circumferential surface of the cylindrical shift drum not to be rotated with the cylindrical shift drum, the shift fork shaft extending in parallel to the third rotational axis; at least one shift fork, each of the at least one shift fork comprising:
a main body portion slidably supported by the shift fork shaft, the main body portion including a fork portion to be engaged with the at least one shifter gear; and
a pin portion rotatably supported by the main body portion, the pin portion being inserted in one of the at least one lead groove of the cylindrical shift drum; and
the cylindrical shift drum to be rotated to guide the pin portion of the at least one shift fork along the one of the at least one lead groove to move the at least one shift fork in a direction parallel to the third rotational axis to shift the at least one shifter gear along the first rotational axis or the second rotational axis.

7 . The speed change apparatus for a power unit according to claim 6 , wherein the pin portion is rotatably supported by the main body portion through a bearing member.

8 . The speed change apparatus for a power unit according to claim 7 ,
wherein the main body portion includes a shaft insertion hole through which the shift fork shaft is passed; and an axial center line of the pin portion is positionally deviated from and not overlapping with a line interconnecting a center of the shaft insertion hole and the third rotational axis, as viewed along the third rotational axis.

9 . The speed change apparatus for a power unit according to claim 7 ,
wherein the main body portion includes a pin insertion hole through which the pin portion is passed, the pin insertion hole includes:
a bearing mounting portion to which to mount a bearing member;
an enlarged diameter portion which is provided at one end of the pin insertion hole and is enlarged in inside diameter as compared with the bearing mounting portion; and
a step portion connecting the bearing mounting portion and the enlarged diameter portion, and

the pin portion includes:
a shaft portion; and
a flange portion which is provided at a part of the shaft portion and is enlarged in diameter as compared with an outside diameter of the shaft portion, and
the pin portion passed through the pin insertion hole is mounted to the main body portion by a structure in which the flange portion is put in contact with the step portion and in which a retaining ring is provided on an opposite side of the flange portion from the step portion.

10 . The speed change apparatus for a power unit according to claim 8 , wherein the main body portion of the at least one shift fork is formed with a substantially cylindrical extension portion where an opening end portion of the shaft insertion hole extends along the shift fork shaft.

Assignees

• Honda Motor Co Ltd

Inventors

• Adachi Jun
• Ozeki Takashi
• Tsukada Yoshiaki

Classifications

• F16H3/006

  power being selectively transmitted by parallel flow paths, e.g. dual clutch transmissions · CPC title

• F16H2063/322

  characterised by catches or notches for moving the fork · CPC title

• F16H3/089

  all of the meshing gears being supported by a pair of parallel shafts, one being the input shaft and the other the output shaft, there being no countershaft involved · CPC title

• F16H63/18 Primary

  the final actuating mechanism comprising cams · CPC title

• F16H3/22 Primary

  with gears shiftable only axially · CPC title