Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2000-01-04
2001-09-18
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090160, C123S090170, C123S090310, C074S56800M, C464S001000, C464S002000, C464S160000
Reexamination Certificate
active
06289860
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to camshaft timing in internal combustion engines and relates more specifically to the means and methods used for altering the camshaft timing to improve performance and efficiency of the engine through a broad range of engine speeds.
It is known that by altering the camshaft timing or more specifically, altering the rotational phase relationship between the camshaft and the crankshaft in an internal combustion engine, the timing of the opening and closing of the intake and exhaust valves in relationship to the position of the pistons within the cylinders is altered. By altering this phase relationship and thereby advance or retard the camshaft timing conditions as the speed of the engine is adjusted, the engine performance and efficiency can be improved.
Examples of systems for altering the camshaft timing though a range of engine speeds are described in U.S. Pat. Nos. 4,955,330, 5,181,486 and 5,609,127. Each system of these referenced patents utilizes a rotating assembly which is interposed between the crankshaft and the camshaft for rotating about an axis at a rotational speed which corresponds with the speed of rotation of the engine camshaft. In addition, these rotating assemblies employ internal weights whose positions are adapted to change in response to centrifugal forces generated upon rotation of the assemblies. The amount of adjustment of the phase relationship between the camshaft and the crankshaft is dependent upon the position of the internal weights so that the faster the assembly is rotated, the greater the altering of the camshaft timing.
It is an object of the present invention to provide a new and improved assembly of the aforedescribed class for altering the camshaft timing of an internal combustion engine.
Another object of the present invention is to provide such an assembly for altering the phase relationship between the camshaft and the crankshaft of an internal combustion engine through a broad range of engine speeds.
Still another object of the present invention is to provide such an assembly whose construction and operation improves upon camshaft timing assemblies of the prior art.
Yet another object of the present invention is to provide such an assembly whose working components are compact and well-suited for use in a region adjacent an internal combustion engine where little space may be available.
A further object of the present invention is to provide such an assembly which is uncomplicated in construction and effective in operation.
SUMMARY OF THE INVENTION
This invention resides in an assembly for controlling the phase relationship between a crankshaft and a camshaft of an internal combustion engine.
The assembly includes an outer ring member which is connectable to a crankshaft of an internal combustion engine for receiving rotating torque from the crankshaft and a hub which is connectable to the camshaft of the internal combustion engine for transmitting torque from the outer ring member to the camshaft so that the hub and camshaft rotate with the outer ring member about an axis of rotation. The hub is associated with the outer ring member in a manner which accommodates a rotational shift of the hub relative to the outer ring member about the axis of rotation between a first condition at which the hub is in one phase relationship with the outer ring member and a second condition at which the hub is in another phase relationship with the outer ring member. The assembly also includes at least one centrifugally-responsive lever member which is pivotally connected to the ring member or the hub for pivotal movement of the at least one lever member relative thereto between a first position at which the lever member is disposed in a first positional relationship with respect to the rotation axis and a second position at which the lever member is disposed in a second positional relationship with respect to the rotation axis. In addition, the at least one lever member is connected to the other of the ring member or the hub so that movement of the at least one lever member between the first position and the second position effects a rotational shift of the hub relative to the outer ring member about the axis of rotation between the first condition and the second condition to thereby adjust the phase relationship between the crankshaft and the camshaft rotated thereby. Still further, first biasing means are interposed between the outer ring member and the at least one lever member for biasing the at least one lever member from the second position toward the first position in opposition to the centrifugal forces generated by the rotation of the hub about the axis of rotation.
In one embodiment of the assembly, the first biasing means includes leaf spring means which are adapted to act between the outer ring member and the at least one lever member for biasing the at least one lever member from the second position toward the first position in opposition to the centrifugal forces generated by the rotation of the hub about the axis of rotation.
In a further embodiment of the invention, the assembly includes additional, or a second, biasing means interposed between the outer ring member and the hub for biasing the hub from the second condition toward the first condition in opposition to the torque required to drive the valve train and which is exerted upon the hub through the camshaft. This second biasing means helps to relieve the effects of the valve train torque upon the at least one lever member.
REFERENCES:
patent: 1202463 (1916-10-01), Wilkinson
patent: 1388743 (1921-08-01), Moore
patent: 3262435 (1966-07-01), Cribbs
patent: 3455286 (1969-07-01), Reisacher et al.
patent: 4577592 (1986-03-01), Bosch et al.
patent: 4955330 (1990-09-01), Fabi et al.
patent: 5181486 (1993-01-01), Gyurovits
patent: 5609127 (1997-03-01), Noplis
McCracken John C.
Speckhart Frank H.
Corrigan Jaime
Denion Thomas
McKee Michael E.
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