Internal combustion engine

Patent metadata

Field	Value
Publication number	US-2024209824-A1
Application number	US-202318390440-A
Country	US
Kind code	A1
Filing date	Dec 20, 2023
Priority date	Dec 21, 2022
Publication date	Jun 27, 2024
Grant date	—

Abstract

There is provided an internal combustion engine including: a crankshaft; a first cylinder and a second cylinder; and a decompression device configured to depressurize the first cylinder and the second cylinder at a time when the internal combustion engine starts to rotationally derive relative to the first cylinder and the second cylinder at a time after the internal combustion engine starts to rotationally drive. The decompression device is configured such that, at the time when the internal combustion engine starts to rotationally derive, a decompression amount in the second cylinder is greater than a decompression amount in the first cylinder.

First claim

What is claimed is:

1 . An internal combustion engine comprising:
a crankshaft: a first cylinder and a second cylinder; and a decompression device configured to depressurize the first cylinder and the second cylinder at a time when the internal combustion engine starts to rotationally derive relative to the first cylinder and the second cylinder at a time after the internal combustion engine starts to rotationally drive, wherein the decompression device is configured such that, at the time when the internal combustion engine starts to rotationally derive, a decompression amount in the second cylinder is greater than a decompression amount in the first cylinder.

2 . The internal combustion engine according to claim 1 , further comprising:
a plurality of valves configured to open and shut off combustion chambers of the first cylinder and the second cylinder to an outside of the combustion chambers, wherein the decompression device drives the plurality of valves in a compression stroke of the internal combustion engine such that an opening period of the second cylinder is longer than an opening period of the first cylinder.

3 . The internal combustion engine according to claim 1 , further comprising:
a plurality of valves configured to open and shut off combustion chambers of the first cylinder and the second cylinder to an outside of the combustion chambers; and a plurality of cams configured to rotate about a predetermined axis to apply a drive force to the plurality of valves, wherein the decompression device includes:
a plurality of decompression bodies disposed corresponding to each of the first cylinder and the second cylinder, and configured to be shifted between a reference position inward of the plurality of cams and a protruding position protruding outward from outer peripheral surfaces of the plurality of cams, and
a shifter configured to shift the plurality of decompression bodies between the reference position and the protruding position in accordance with a rotation speed of the crankshaft.

4 . The internal combustion engine according to claim 3 , wherein
among the plurality of decompression bodies, the number of the decompression bodies disposed corresponding to the second cylinder is larger than the number of the decompression bodies disposed corresponding to the first cylinder.

5 . The internal combustion engine according to claim 4 , wherein
the plurality of cams include a pair of cams disposed corresponding to the second cylinder, and the plurality of decompression bodies include a pair of decompression bodies disposed corresponding to the pair of cams.

6 . The internal combustion engine according to claim 5 , wherein
the pair of decompression bodies are each disposed at a different position on outer peripheral surfaces of the pair of cams to be retractable inward of the pair of cams from the outer peripheral surfaces of the pair of cams.

7 . The internal combustion engine according to claim 3 , wherein
the plurality of decompression bodies have the same structure.

8 . The internal combustion engine according to claim 3 , further comprising:
a single camshaft to which all the decompression bodies and all the plurality of cams corresponding to all the decompression bodies are attached.

9 . The internal combustion engine according to claim 1 , further comprising:
a control device configured to control a combustion state in the second cylinder such that the combustion state is different between at the time when the internal combustion engine starts to rotationally drive and at the time after the internal combustion engine starts to rotationally drive.

10 . The internal combustion engine according to claim 3 , wherein
the decompression device includes:
a cylindrical camshaft to which the plurality of cams are attached, and
a decompression shaft inserted into the camshaft, rotatably supported about an axis of the camshaft independently of the camshaft, and configured to apply a predetermined external force to the plurality of decompression bodies, and
the camshaft has a shaft support portion that is positioned between two adjacent cams among the plurality of cams, the shaft support portion rotatably supporting the decompression shaft.

11 . An internal combustion engine comprising:
a crankshaft: a cylinder: a plurality of valves configured to open and shut off a combustion chamber of the cylinder to an outside of the combustion chamber: a decompression device configured to depressurize the cylinder at a time when the internal combustion engine starts to rotationally drive relative to the cylinder at a time after the internal combustion engine starts to rotationally drive; and a pair of cams configured to rotate about a predetermined axis to apply a drive force to the plurality of valves, wherein the decompression device includes a plurality of decompression bodies disposed corresponding to the cylinder, and configured to be shifted between a reference position inward of the pair of cams and a protruding position protruding outward from outer peripheral surfaces of the pair of cams, and the plurality of decompression bodies are each disposed at a different position on the outer peripheral surfaces of the pair of cams to be retractable inward of the pair of cams from the outer peripheral surfaces of the pair of cams.

12 . The internal combustion engine according to claim 11 , wherein
the decompression device includes:
a cylindrical camshaft to which the pair of cams are attached, and
a decompression shaft inserted into the camshaft, rotatably supported about an axis of the camshaft independently of the camshaft, and configured to apply a predetermined external force to the plurality of decompression bodies, and
the camshaft has a shaft support portion that is positioned between the pair of cams, the shaft support portion rotatably supporting the decompression shaft.

Assignees

• Kawasaki Motors Ltd

Inventors

• Noami Takuya
• Yamamoto Tetsuji

Classifications

• F02N19/004 Primary

  Aiding engine start by using decompression means or variable valve actuation · CPC title

• F02N11/04

  the motors being associated with current generators · CPC title

• F01L2013/108

  Centrifugal force · CPC title

• F01L2760/001

  for starting four stroke engines · CPC title

• F01L2800/01

  Starting · CPC title