Mode-switching cam follower
AssigneeFord Global Technologies, LLC
InventorsWilliam Riley, Mark Zagata, Michael Schrader, Gregory McConville
Life of this patent
Estimating the term…
Abstract
A mode-switching cam follower is disclosed, wherein the follower includes a body, a cam contact movably coupled to the body, and a latch member movably coupled to the body. A shape-memory alloy in communication with the latch member couples and decouples the latch member with the cam.
Claims16
A cam follower, comprising:
- a cam contact movably coupled to a body;
- a latch member movably coupled to the body and movable between a coupled position with the latch member holding the cam contact fixed to the body and a decoupled position with the cam contact decoupled from the latch member and movable relative to the body;
- and
- a shape-memory alloy wire coupled around an outer latch member circumference and along a body underside.
An apparatus comprising an internal combustion engine, the internal combustion engine comprising a mode-switching roller finger follower, the roller finger follower comprising:
- rocker arm;
- a drop member disposed within the rocker arm;
- a roller coupled to the drop member;
- a latch member pivotally coupled to the drop member and configured to pivot between a coupled position in which the roller is held in a fixed relation to the rocker arm by the latch member and a decoupled position in which the roller is decoupled from the latch member and movable relative to the rocker arm;
- and
- a shape-memory alloy wire extending around the latch member and coupled to the drop member at a location intermediate a length of the drop member and the rocker arm cause the latch member to move between the coupled position and the decoupled position when the shape-memory alloy wire undergoes a phase transition.
In an apparatus having an internal combustion engine, wherein the engine comprises a controller, at least one cylinder comprising a valve, and a cam follower for operating the valve, the cam follower comprising a body, a cam contact movably coupled to the body, a latch member movably coupled to the body and selectively movable to hold the cam contact in a fixed relation to the body, and a latch member actuator comprising a shape-memory alloy, a method of operating the engine, comprising:
- detecting an engine operating condition corresponding to a change in a valve operating mode;
- and
- applying a higher initial voltage to the shape-memory alloy, the shape-memory alloy extending substantially around an outer circumference of the latch member, during initial heating of the shape-memory alloy to rapidly increase temperature and cause the shape-memory alloy to pull the latch member to hold the cam contact in a fixed relation to the body, and then maintaining the temperature at an increased level by applying a smaller voltage to the shape-memory alloy;
- and
- ceasing application of the smaller voltage to cool the shape-memory alloy.
Dependencies are inferred from the claim text.