Rocker arm and rocker arm assembly for engines

Details Rocker arm and rocker arm assembly for engines Rocker arm and rocker arm assembly for engines

1999-04-07

2001-09-25

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

C123S090400, C123S090440, C123S321000

Reexamination Certificate

active

06293238

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to engine components, and more particularly to a rocker arm assembly for an engine.
BACKGROUND ART
Rocker arm assemblies for internal combustion engines and the like pivot about a fixed point, thereby displacing a valve of the internal combustion engine.
A rocker arm is ordinarily considered part of a valve train of an internal combustion engine, which is disposed within a cylinder head of the engine and also includes valves, springs and camshafts.
A rocker arm for an internal combustion engine is pivotably disposed on a rocker arm shaft and is pivoted either by a cam directly or by a pushrod in contact with the cam to open and close one or more engine valves. Often, an engine brake actuator is supplied to pivot the rocker arm one or more times during an engine cycle to cause the engine to apply braking torque to wheels of the vehicle in which the engine is used. Conventionally, the cam contacts the rocker arm on a first side of the rocker arm shaft, below the rocker arm, and the brake actuator contacts the rocker arm on a second side of the rocker arm shaft, above the rocker arm. In this arrangement, the brake actuator is located above the engine, substantially in-line with the valve, and pushes down on the rocker arm. This arrangement, however, results in an undesirable increased height and overall size of the engine assembly.
SUMMARY OF THE INVENTION
The present invention is directed to a rocker arm assembly disposed within an engine assembly and actuated in a manner which reduces the height and size of the engine assembly. Reduced engine assembly height and size means less space is required for installation and may help to reduce installation costs.
More particularly, in accordance with one aspect of the present invention, a rocker arm assembly comprises a rocker shaft and a rocker arm pivotably disposed on the rocker shaft. The rocker arm includes a first portion disposed on a first side of the rocker shaft for receiving a force in a first direction from a brake actuator. The rocker arm further includes a second portion on a second side of the rocker shaft opposite the first portion for engaging a valve in a second direction opposite the first direction.
Preferably, such a rocker arm assembly may be combined with a brake actuator in contact with the first portion of the rocker arm. The rocker arm assembly may also be combined with a first exhaust valve and a second exhaust valve in contact with the second portion of the rocker arm. When a braking mode of operation is desired, the brake actuator contacts the first portion of the rocker arm and forces the arm in a first direction, thereby causing the rocker arm to transfer motion from the brake actuator to the exhaust valve or valves of the engine.
The rocker arm may further include a central bore for receiving the rocker shaft and a second bore for receiving a roller that contacts a cam, causing the rocker arm to pivot about a pivot point, intermediate the first and second portions of the rocker arm, during normal operation of the engine.
Preferably, the rocker arm of the rocker arm assembly also includes a first section disposed on the first side of the rocker shaft for receiving the brake actuator, a second section disposed on the second side of the rocker shaft for engaging the first valve and a third section disposed on the second side of the rocker shaft for engaging the second exhaust valve.
The invention itself, together with further objects and advantages, will best be understood by reference to the following detailed description and accompanying drawings.


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