Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1993-01-13
1994-11-15
Cross, E. Rollins
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9023, 123 9027, F01L 104, F01L 134
Patent
active
053638182
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a valve operating apparatus comprising a drive rocker arm which is interposed between a cam shaft and at least an intake valve of intake and exhaust valves disposed in a cylinder head of an engine body and spring-biased in closing directions and which is operatively connected to the intake valve, a free rocker arm also interposed between the cam shaft and at least the intake valve and capable of being liberated from the intake valve, a connection switchover mechanism provided in the rocker arms and capable of switching-over the connection and disconnection of the rocker arms, and a lost motion mechanism provided in the engine body for resiliently biasing the free rocker arm toward the cam shaft.
TECHNICAL SUBJECT
Such a valve operating apparatus is conventionally known, for example, from the publication of Japanese Patent Application Laid-open No. 57806/88.
In the above prior art valve operating apparatus, the lost motion mechanism is provided in the cylinder head to resiliently bias the free rocker arm upwardly from a side of the cylinder head. Moreover, disposed in an upper portion of the cylinder head are intake and exhaust ports, cylindrical guides for guidance of intake and exhaust valves, valve springs for biasing the intake and exhaust valves and the like. To insure a space in which the lost motion mechanism is disposed, the variations in design such as the shape of the ports, of the valve springs and the like are reduced, and it is difficult to reduce the cylinder head in size.
SUMMARY OF THE INVENTION
The present invention has been accomplished with the above circumstances in view, and it is an object of the present invention to provide a valve operating apparatus in an internal combustion engine, wherein the variations in design of the upper portion of the cylinder head is increased, and the cylinder head can be reduced in size.
To achieve the above object, according to the present invention, the lost motion mechanism is disposed in a support member disposed above the cylinder head, and the free rocker arm is disposed below the support member.
With such construction, it is possible to insure a space below the rocker arms, which is enough to dispose the intake and exhaust ports, the cylindrical guides for guidance of the intake and exhaust valves, the valve springs for biasing the intake and exhaust valves in closing directions and the like. This makes it possible to increase the variations in design and to reduce, in size, the upper portion of the engine body.
Further, the lost motion mechanism can be disposed without being interfered by the intake and exhaust ports and the like and therefore, the lost motion mechanism can be disposed at a location where its resilient force can be exhibited in a most effective manner. Moreover, the lost motion mechanism can be reduced in size.
BRIEF DESCRIPTION OF THE DRAWINGS
Drawings illustrate one embodiment of the present invention, wherein
FIG. 1 is a plan view of an essential portion;
FIG. 2 is a sectional view taken along a line II--II in FIG. 1; and
FIG. 3 is a sectional view taken along a line III--III in FIG. 2.
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment of the present invention will now be described in connection with the accompanying drawings.
Referring first to FIGS. 1 and 2, an essential portion of an engine body E in an SOHC type multi-cylinder internal combustion engine is comprised of a cylinder block 1 and a cylinder head 2 coupled to an upper surface of the cylinder block 1. A piston 4 is provided in an upper surface thereof with a depression 4a, and is slidably received in each of a plurality of cylinders 3 which are provided in the cylinder block 1 at a distance from one another in an axial direction of a crankshaft which is not shown. A combustion chamber 5 is defined between the upper surface of the piston 4 and the cylinder head 2.
A pair of intake valve bores 6 and a pair of exhaust valve bores 7 are provided in the cylinder head 2 in correspondence to the cylinder
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Aoki Takatoshi
Iwata Takeshi
Cross E. Rollins
Honda Giken Kogyo Kabushiki Kaisha
Lo Weilun
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