US 6,178,936 B2Granted

Structure of overhead-valve internal combustion engine and manufacturing method for the same

AssigneeMitsubishi Heavy Industries, Ltd.

InventorsHiroyoshi Kouchi, Kazuyuki Kobayashi, Shogo Nakamura, Isao Katayama, Shigeichi Okada

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Abstract

To simplify the assembling process to mount a valve operating mechanism on a cylinder head, one intake valve and one exhaust valve are mounted on the cylinder head symmetrically with respect to the axis of a cylinder shaft. A rocker arm supporting base which supports rocker arms is fixed to the top of the cylinder head. Rocker arm shafts are supported by the base. The central portions of the rocker arms engage with the rocker arm shafts in such a way that the arms are free to swing. Push rods and the intake and exhaust valves are engaged with the ends of the arms. The valve operating mechanism is enclosed in a head cover which is fixed to the top surface of the cylinder head. This engine is distinguished by having the mounting surface for the rocker arm supporting base, on which the rocker shafts are mounted, and the surface on which the head cover sits be virtually coplanar. This makes it possible to machine the two surfaces at the same time. In order to supply a sufficient quantity of lubricating oil to the entire valve operating mechanism, a particularly designed lubrication device is provided.

Claims7

Dependent claims

An overhead-valve internal combustion engine, comprising:

a hemispherical or pent roof cylinder head which has a combustion chamber formed with a curved top portion projecting upward;
an intake valve and an exhaust valve mounted symmetrically with respect to an axis of a cylinder;
a rocker arm supporting base fixed on a mounting surface of said cylinder head;
rocker arm shafts supported by said rocker arm supporting base;
rocker arms engaged with said rocker arm shafts at central portions of said rocker arms in such a way that said rocker arms are free to swing, and engaged with push rods which push said intake and exhaust valves;
and
a head cover to cover a valve operating mechanism formed by said intake and exhaust valves, said rocker arm supporting base, and said rocker arms, said head cover being fixed on a top surface of said cylinder head,
wherein the intake valve and the exhaust valve are inclined when mounted symmetrically with respect to the axis of the cylinder so as to extend out towards the top surface of the cylinder head,
wherein said mounting surface is formed on a central portion of said top surface and is positioned between the intake valve and the exhaust valve,
wherein said mounting surface is virtually coplanar with said top surface on which said head cover is fixed, and
wherein said rocker arm shafts and said rocker arms are first mounted on said rocker arm supporting base, and said rocker arm supporting base is then fixed on said cylinder head.

8 more elements

A manufacturing method for an overhead-valve internal combustion engine, wherein the overhead-valve internal combustion engine comprises a hemispherical or pent roof cylinder head which has a combustion chamber formed with a curved top portion projecting upward, an intake valve and an exhaust valve mounted symmetrically with respect to an axis of a cylinder, a rocker arm supporting base fixed on a mounting surface of said cylinder head, rocker arm shafts supported by said rocker arm supporting base, rocker arms engaged with said rocker arm shafts at central portions of said rocker arms in such a way that said rocker arms are free to swing, and engaged with push rods which push said intake and exhaust valves, and a head cover to cover a valve operating mechanism formed by said intake and exhaust valves, said rocker arm supporting base, and said rocker arms, said head cover being fixed on a top surface of said cylinder head, comprising the steps of:

forming said mounting surface on a central portion of said top surface of said cylinder head so as to be virtually coplanar with said top surface on which said head cover is fixed;
providing an assembly of said rocker arm supporting base on which a rocker arm shaft and a rocker arm are fixed;
fixing said assembly on said mounting surface and said intake valve and said exhaust valve symmetrically with respect to an axis of said cylinder head with the intake and exhaust valves inclining out towards the top surface of said cylinder head;
and
engaging one of the push rods on one end of each said rocker arm and one of said intake valve and said exhaust valve on the other end of each said rocker arm.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/104,395Filed 25 Jun 1998
Priority: JP 9-18439825 Jun 1997
Granted: 30 Jan 2001
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

F02F 1/30
For air cooling: finned cylinder heads
F01L 1/12
Valve-gear or valve arrangements, e.g. lift-valve gear: transmitting gear between valve drive and valve
F01L 1/182
Centre pivot rocking arms: the rocking arm being pivoted about an individual fulcrum, i.e. not about a common shaft
F02B 2275/34
Other engines, components or details, not provided for in other groups of this subclass: lateral camshaft position