Internal-combustion engines – Engine speed regulator – Responsive to deceleration mode
Reexamination Certificate
2000-03-21
2001-04-10
Kwon, John (Department: 3747)
Internal-combustion engines
Engine speed regulator
Responsive to deceleration mode
Reexamination Certificate
active
06213091
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an engine compression brake system, and particularly, to an engine compression brake system of the type wherein the pivot center of the exhaust rocker arm is displaced.
Various types of engine compression brake systems are known. In one type of engine compression brake system, a lost motion device is included in an end of the rocker arm or in the links connecting the rocker arm to the cam lobe or valve (push rod or lifter) to allow a control mechanism to react to or ignore a portion of the cam lobe profile. Another type of engine compression brake system is shown in U.S. Pat. No. 5,647,319, issued in 1997 to Uehara et al. and U.S. Pat. No. 3,367,312, issued in 1966 to Jonsson. Both of these systems have engine brake mechanisms wherein the pivot center of the exhaust rocker arm is displaced or shifted by an eccentric which is connected to an hydraulic piston/actuator by a lever arm.
However, these mechanisms require an extra mechanical component between the hydraulic piston/actuator and the rocker arm. Also, the various actuation arms and levers of these systems are subject to tension and bending loads, which increases the probability of stress failures. These additional links, arms and actuators also increase the manufacturing tolerance requirements of many of the components. These systems also require intermediate arms, a second rocker arm eccentric bore, features on the small end of the actuation/pivot arm and features on the mechanical actuation end of the piston. These parts and features all add cost and complexity, and reduce system reliability. Finally, these systems result in an assembly which is not as compact as desired, and could result in increased engine height.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide an engine compression brake mechanism with few components.
A further object of the invention is to provide such an engine compression brake mechanism wherein the parts are not subject to tension and bending loads.
A further object of the invention is to provide such an engine compression brake mechanism which does not increase the manufacturing tolerance requirements of many of the components.
A further object of the invention is to provide such an engine compression brake mechanism with reduced complexity, lower cost and increased system reliability.
A further object of the invention is to provide such an engine compression brake mechanism which avoids increasing engine height.
These and other objects are achieved by the present invention, wherein an engine compression braking system includes an exhaust rocker arm pivotally supported on a rocker shaft. One end of the rocker arm carries a roller which engages a camshaft which has a lost motion bump formed thereon. The other end of the rocker arm engages an exhaust valve stem assembly. A part of the rocker shaft engages a pressure operated piston. Extension of the piston moves the rocker shaft transversely to its axis, so that the rocker arm can selectively react to or ignore the lost motion portion bump. A pressure control system includes a solenoid operated valve controlled by an operator controlled switch, so that the piston selectively applies a light force or a very high force to the rocker arm rocker shaft, thus shifting the pivot point of the rocker arm
REFERENCES:
patent: 3367312 (1968-02-01), Jonsson
patent: 3809033 (1974-05-01), Cartledge
patent: 4572114 (1986-02-01), Sickler
patent: 4643141 (1987-02-01), Bledsoe
patent: 4723516 (1988-02-01), Slagley et al.
patent: 5335636 (1994-08-01), Bilei et al.
patent: 5611308 (1997-03-01), Hackett
patent: 5645031 (1997-07-01), Meneely
patent: 5647319 (1997-07-01), Uehara et al.
patent: 6012424 (2000-01-01), Meistrick
Deere & Company
Kwon John
LandOfFree
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