Tapered roller drive for electric VCT phaser
AssigneeBorgWarner Inc.
InventorChad McCloy
Life of this patent
Estimating the term…
Abstract
An electric phaser for dynamically adjusting a rotational relationship of a camshaft with respect to an engine crankshaft of an internal combustion engine includes an electric motor and a tapered roller drive. The tapered roller drive includes a sun, rollers, a carrier, at least one ring, and at least one load generator providing an axial load. The rollers are maintained in rolling engagement with the sun and the ring without the use of teeth. In some embodiments, the tapered roller drive is based on a fixed-sun design. In other embodiments, the tapered roller drive is based on a split ring design.
Claims9
An electric phaser for dynamically adjusting a rotational relationship of a camshaft with respect to a crankshaft of an internal combustion engine, the electric phaser comprising:
- an electric motor;
- and
- a split ring tapered roller drive comprising:
- a sun driven to rotate around a sun axis by the electric motor, the sun having a sun contact surface having a circular cross section without teeth and tapering with respect to the sun axis;
- a carrier rotatable around the sun axis;
- a plurality of rollers arranged around the sun, each roller rotatable on a roller axis at a roller angle with respect to the sun axis, each roller having a roller contact surface without teeth in rolling engagement with the sun contact surface, wherein the rollers are rotatably mounted on the carrier to rotate on the roller axes;
- a sprocket ring driven by the crankshaft, the sprocket ring having a sprocket ring contact surface without teeth in rolling engagement with the roller contact surfaces and defining a first circular cross sectional interior space;
- a camshaft ring rotatable with the camshaft, the camshaft ring having a camshaft ring contact surface without teeth in rolling engagement with the roller contact surfaces and defining a second circular cross sectional interior space;
- and
- a load generator applying an axial load to maintain the plurality of rollers in rolling engagement with the sun and the ring;
- wherein the electric motor is driven at a motor speed to dynamically maintain or adjust the rotational relationship of the camshaft with respect to the crankshaft.
A method of dynamically adjusting a rotational relationship of a camshaft with respect to a crankshaft of an internal combustion engine using an electric phaser comprising an electric motor;
- and a split ring tapered roller drive comprising a sun driven to rotate around a sun axis by the electric motor, the sun having a sun contact surface having a circular cross section without teeth and tapering with respect to the sun axis;
- a carrier rotatable around the sun axis;
- a plurality of rollers arranged around the sun, each roller rotatable on a roller axis at a roller angle with respect to the sun axis, each roller having a roller contact surface without teeth in rolling engagement with the sun contact surface, wherein the rollers are rotatably mounted on the carrier to rotate on the roller axes;
- a sprocket ring driven by the crankshaft, the sprocket ring having a sprocket ring contact surface without teeth in rolling engagement with the roller contact surfaces and defining a first circular cross sectional interior space and a camshaft ring rotatable with the camshaft, the camshaft ring having a camshaft ring contact surface without teeth in rolling engagement with the roller contact surfaces and defining a second circular cross sectional interior space, the method comprising:
- applying an axial load to maintain the sun, the plurality of rollers, and the ring in rolling engagement;
- and
- dynamically selecting a motor speed of the electric motor and adjusting the electric motor to the motor speed to dynamically adjust the rotational relationship of the camshaft with respect to the crankshaft.
Dependencies are inferred from the claim text.