Internal-combustion engines – Poppet valve operating mechanism – Plural valve trains – single actuator
Patent
1991-09-03
1994-11-22
Cross, E. Rollins
Internal-combustion engines
Poppet valve operating mechanism
Plural valve trains, single actuator
123 904, F01L 126
Patent
active
053658949
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to internal combustion engines and more particularly to a valve actuation device therefor.
BACKGROUND ART
It is well known that the specific output of an internal combustion engine can be increased by using a plurality of valves for each combustion chamber. For this reason, it is becoming more commonplace to have multiple valves operatively associated with a common combustion chamber, particularly in high performance engines. As a result, methods and devices are described in the prior art for simultaneously operating two or more valves to reduce weight, cost, and parts in the valvetrain.
One prior art reference discloses a four valve design which uses a single rocker arm to operate two of the four valves simultaneously, while the remaining two valves are operated by two separate conventional rocker arms. The single rocker arm operating the two valves simultaneously has a Y-shaped body with ends which seat on the ends of the two valve stems. Therefore, the actuation force is applied directly to the valves. By utilizing this design, three rocker arms are used to operate four valves operatively associated with a common combustion chamber. Normally, four separate rocker arms would be used for the actuation of four valves.
In the same manner, another prior art device utilizes a bridge mechanism to simultaneously operate two valves of an internal combustion engine. The bridge mechanism is guided between the two valves at the center of the forces and is actuated by a rocker arm whose contact point on the bridge is located on an extension of the guiding means for the bridge.
In order to reduce the number of rocker arms even further, a prior art device having five valves operatively associated with a common combustion chamber uses a single rocker arm to operate three valves simultaneously and an additional rocker arm to operate the remaining two valves. The rocker arms have fingers which contact the valve stems, with each of the five fingers requiring an adjustor to position the valves.
It is evident from the prior art described that the simultaneous actuation of multiple valves operatively associated with a common combustion chamber of an internal combustion engine requires the use of an adjustor for each valve or a bridge with a guiding mechanism and adjustor for all but one valve per bridge.
The present invention minimizes the use of valve adjustors and eliminates bridge guiding mechanisms in a simplified device that accomplishes the simultaneous actuation of multiple valves operatively associated with a common combustion chamber.
The present invention also accomplishes simultaneous actuation of multiple valves in a device that provides improved reliability and assembleability over the prior art at substantially the same costs.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention a valve actuation device is provided for an internal combustion engine. The valve actuation device has a valve arrangement with at least three valves operatively associated with a common combustion chamber. The valves each have a stem portion supporting the valves for reciprocation along their respective axis. A free-floating bridge is seated on the stem portions of the valves. Means are provided for applying a force to the free-floating bridge at a contact point sufficient for actuating the valves simultaneously.
The disadvantage of the prior art is that simultaneous actuation of multiple valves is obtained, but more parts, such as, valve adjustors, rocker arms, and bridge guiding mechanisms are needed. The excessive parts necessary for the prior art devices increase the weight of the valvetrain. The present invention simultaneously operates three valves operatively associated with a common combustion chamber through the use of a free-floating bridge which is seated on the ends of the valve stems. The present invention minimizes the use of adjustors while totally eliminating the use of bridge guiding mechanisms. The present invention actuates the three valves simultaneously in
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Caterpillar Inc.
Charlton Diana L.
Cross E. Rollins
Lo Weilun
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