Internal combustion engine

Patent metadata

Field	Value
Publication number	US-10920630-B2
Application number	US-201916502192-A
Country	US
Kind code	B2
Filing date	Jul 3, 2019
Priority date	Jul 6, 2018
Publication date	Feb 16, 2021
Grant date	Feb 16, 2021

Abstract

An internal combustion engine includes: an engine main body demarcating a breather chamber that is partitioned from a crank chamber, disposed above the crank chamber, and has an inlet opening opened toward the crank chamber; a multistage transmission housed in the crank chamber and having speed change gear trains that are respectively supported by a pair of transmission shafts and mesh with each other; and a breather passage disposed above the transmission shafts and extending in an up-down direction from the crank chamber to the inlet opening of the breather chamber, the inlet opening being disposed above a half in a height direction of the breather chamber. Accordingly, the internal combustion engine can suppress the entry of splashed oil into the breather chamber more than ever before.

First claim

What is claimed is:

1. An internal combustion engine comprising:
an engine main body demarcating a crank chamber and a breather chamber, the crank chamber housing a crankshaft and the breather chamber being partitioned from the crank chamber, disposed above the crank chamber and having an inlet opening opening toward the crank chamber;
a multistage transmission housed in the crank chamber and having speed change gear trains that are respectively supported by a pair of transmission shafts and mesh with each other; and
a breather passage disposed above the transmission shaft and extending in an up-down direction from the crank chamber to the inlet opening of the breather chamber,
the inlet opening being disposed above a lower half, in a height direction, of the breather chamber,
wherein a reduction gear of a starter motor is disposed in the breather chamber.

2. The internal combustion engine according to claim 1 , wherein the breather chamber extends frontward, along a plane orthogonal to a rotation axis of the crankshaft, from a connecting end connected to the breather passage toward a cylinder head disposed below an air cleaner, and is connected to the air cleaner by a breather hose coupled to an outlet end located forwardly of the connecting end.

3. The internal combustion engine according to claim 1 , wherein the engine main body includes:
a ceiling surface that is faced to an outer edge of the speed change gear trains and extends along a horizontal plane, the breather passage being disposed on an outside of one end of the ceiling surface;
and a curved surface that is continuous from another end of the ceiling surface and extends downward while curved along the outer edge of the speed change gear trains.

4. The internal combustion engine according to claim 3 , wherein the engine main body includes a projecting piece projecting downward from a downstream end of the ceiling surface in a rotational direction of the speed change gear trains.

5. The internal combustion engine according to claim 1 , further comprising:
a shift spindle extending in parallel with a rotation axis of a shift drum and faced to the breather passage.

6. The internal combustion engine according to claim 1 , further comprising:
an oil passage pipe extending in parallel with axes of the transmission shafts and faced to the breather passage.

7. The internal combustion engine according to claim 1 , wherein a gear chamber and a labyrinth chamber are demarcated in the breather chamber, the gear chamber housing the reduction gear, and the labyrinth chamber partitioning, in a form of a labyrinth by a rib, a passage of breathing air reaching the gear chamber from the breather passage.

8. The internal combustion engine according to claim 7 , wherein the engine main body includes a crankcase having:
a first partition wall extending along a horizontal plane in a position faced to the outer edge of the speed change gear trains, the first partition wall separating the labyrinth chamber from the crank chamber; and
a second partition wall continuous from the first partition wall and extending downward while curved along the outer edge of the speed change gear trains, the second partition wall separating the gear chamber from the crank chamber.

9. The internal combustion engine according to claim 8 , wherein a lid member covering the gear chamber and the labyrinth chamber from above is coupled to the crankcase.

10. The internal combustion engine according to claim 8 , wherein a rotational speed sensor that detects rotational speed of the transmission shaft is attached to the crankcase at a position separated from the labyrinth chamber in an axial direction of the transmission shaft.

11. The internal combustion engine according to claim 1 , wherein the breather passage is formed by a side wall of the breather chamber.

Assignees

• Honda Motor Co Ltd

Inventors

• Mori Kensuke
• Takahashi Masako
• Tsukagoshi Hiroyuki

Classifications

• F01M13/0033 Primary

  Breather inlet-air filters · CPC title

• F02B61/06

  Combinations of engines with mechanical gearing (F02B61/02, F02B61/04 take precedence) · CPC title

• B62M11/04

  of changeable ratio · CPC title

• F01M2013/0038

  Layout of crankcase breathing systems · CPC title

• B62K11/04

  characterised by the engine being between front and rear wheels · CPC title