DOHC-type internal combustion engine

Patent metadata

Field	Value
Publication number	US-10309265-B2
Application number	US-201815879858-A
Country	US
Kind code	B2
Filing date	Jan 25, 2018
Priority date	Mar 21, 2017
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

In a DOHC-type internal combustion engine in which a pair of intake valves and a pair of exhaust valves are disposed around a plug hole, and two pairs of rocker arms are respectively interposed between intake-side and exhaust-side camshafts and the intake valves and the exhaust valves, first and second support portions of one pair of the rocker arms are disposed between the intake valves and the exhaust valves in a direction orthogonal to axes of the intake-side and exhaust-side camshafts and around the plug hole, and the third and fourth support portions of an other pair of the rocker arms are disposed outside a region between the intake valves and the exhaust valves in the direction orthogonal to the axes of the intake-side and exhaust-side camshafts.

First claim

What is claimed is:

1. A DOHC-type internal combustion engine, comprising:
an engine body comprising a cylinder head in which an intake-side camshaft and an exhaust-side camshaft are disposed in parallel to each other with a plug hole interposed therebetween,
an ignition plug to be inserted into the plug hole,
a pair of intake valves and a pair of exhaust valves disposed around the plug hole, said intake valves being arrayed in a direction along an axis of the intake-side camshaft, said exhaust valves being arrayed in a direction along an axis of the exhaust-side camshaft,
two pairs of rocker arms respectively interposed between the intake-side and exhaust-side camshafts and said intake valves and said exhaust valves, the two pairs of rocker arms respectively corresponding to said intake valves and said exhaust valves while respectively including support portions and valve connection portions, the support portions being rockably supported by the cylinder head, the valve connection portions being operatively connected respectively with said intake valves and said exhaust valves,
wherein first and second support portions of a first pair of the two pairs of rocker arms out of the support portions are disposed between the pair of intake valves and the pair of exhaust valves in a direction orthogonal to the axes of the intake-side and exhaust-side camshafts and around the plug hole, and
third and fourth support portions of a second pair of the two pairs of rocker arms out of the support portions are disposed outside a region between the pair of intake valves and the pair of exhaust valves in the direction orthogonal to the axes of the intake-side and exhaust-side camshafts,
wherein a distance between first and second valve connection portions of the first pair of the two pairs of rocker arms is set shorter than a distance between the first and second support portions, and wherein a distance between third and fourth valve connection portions of the second pair of the two pairs of rocker arms is set longer than a distance between the third and fourth support portions.

2. The DOHC-type internal combustion engine according to claim 1 , wherein a first rocker arm, on one side along the axes of the intake-side and exhaust-side camshafts out of the first pair of the rocker arms, and a second rocker arm, on the other side along the axes of the intake-side and exhaust-side camshafts out of the second pair of the rocker arms, have a same shape and are substantially identical to one another.

3. The DOHC-type internal combustion engine according to claim 2 , wherein the two pairs of the rocker arms are formed to include two shapes, such that an inside diameter of a support hole, which is formed in the first and fourth support portions of one subset of said rocker arms having a first shape of the two shapes, and an inside diameter of a support hole, which is formed in the second and third support portions of another subset of said rocker arms having a second shape of the two shapes, are different from each other.

4. The DOHC-type internal combustion engine according to claim 3 , wherein:
a tubular portion is arranged integrally in the cylinder head, the tubular portion forming at least a part of the plug hole,
first and second rocker shafts are disposed on opposite sides of the plug hole in a direction along the axes of the intake-side and exhaust-side camshafts, the first and second rocker shafts supporting the first and second support portions individually,
a pair of support recesses are formed in the tubular portion, end portions on the plug hole side of the first and second rocker shafts being fitted to the pair of support recesses respectively, and
axial movement of at least one of the first and second rocker shafts is prevented by an anti-come-off plug and an inner end closing portion of at least one of the pair of support recesses, the anti-come-off plug being attached to the cylinder head so as to abut, from a side opposite to the plug hole, against at least the one of the first and second rocker shafts.

5. The DOHC-type internal combustion engine according to claim 4 , wherein:
a part of a cam chain chamber is formed in the cylinder head, the cam chain chamber being disposed so that another of the first and second rocker shafts is sandwiched between the cam chain chamber and the plug hole, and
an anti-come-off pin is attached to the cylinder head, the anti-come-off pin engaging with an annular locking groove that is formed on an outer surface of an intermediate portion of the other rocker shaft.

6. The DOHC-type internal combustion engine according to claim 3 , wherein a single third rocker shaft is formed to have a step so that a portion of the third rocker shaft which is inserted to the third support portion and a portion of the third rocker shaft which is inserted to the fourth support portion are made different in an outside diameter, the third rocker shaft being common to the third and fourth support portions.

Assignees

• Honda Motor Co Ltd

Inventors

• Okada Nozomi
• Hoi Yosuke
• Azumagakito Isao
• Shinke Tsugumi

Classifications

• F01L2305/00

  Valve arrangements comprising rollers · CPC title

• F01L2001/0537

  Double overhead camshafts [DOHC] · CPC title

• F01L1/185 Primary

  Overhead end-pivot rocking arms · CPC title

• F02D2041/001

  for engines with variable valve actuation · CPC title

• F01L1/022

  Chain drive · CPC title