Mechanical variable camshaft timing device
AssigneeFord Global Technologies, LLC
InventorAlvin Henry Berger
Life of this patent
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Abstract
A device for selectively changing phase relationship between first and second rotating shafts in an internal combustion engine where the first shaft is secured for rotation with a worm carrier assembly and the second shaft is secured for rotation with a worm gear includes first and second worms disposed for rotation within the worm carrier assembly and having torsional preloads with opposite hands of rotation and meshing with the worm gear. An actuator turns the first and second worms in a first direction to advance rotation of the second shaft relative to the first shaft and turns the first and second worms in a second direction to retard rotation of the second shaft relative to the first shaft.
Claims20
A device for selectively varying a relative angular position between first and second rotating shafts of an internal combustion engine, the device comprising:
- a first worm assembly coupled to the first and second rotating shafts and torsionally preloaded to provide a first torque tending to increase the relative angular position between the first and second shafts;
- a second worm assembly coupled to the first and second rotating shafts and torsionally preloaded opposite to the first assembly to provide a second torque simultaneously tending to decrease the relative angular position between the first and second shafts such that the relative angular position of the first and second shafts remains substantially constant during rotation of the shafts;
- and
- at least one actuator selectively applying an actuating torque to respective gears of the first and second worm assemblies to rotate the first shaft relative to the second shaft and change the relative angular position between the first and second shafts.
A method for changing relative rotational phase between first and second rotating shafts in an internal combustion engine, the method comprising:
- biasing a first worm assembly to apply a clockwise rotational bias torque between the first and second shafts;
- biasing a second worm assembly to apply a counterclockwise rotational bias torque between the first and second shafts to maintain the rotational phase between the first and second shafts during rotation other than during phase change actuation;
- and
- applying an actuating torque to the first and second worm assemblies during phase change actuation to selectively change the rotational phase between the first and second rotating shafts during rotation.
A device for selectively changing phase relationship between first and second rotating shafts in an internal combustion engine, the first shaft secured for rotation with a worm carrier assembly and the second shaft secured for rotation with a worm gear, the device comprising:
- first and second worms disposed for rotation within the worm carrier assembly and having torsional preloads with opposite hands of rotation, the first and second worms meshing with the worm gear;
- and
- an actuator for turning the first and second worms in a first direction to advance rotation of the second shaft relative to the first shaft and for turning the first and second worms in a second direction to retard rotation of the second shaft relative to the first shaft.
Dependencies are inferred from the claim text.