Systems and methods for controlling rollback in continuously variable transmissions
AssigneeFallbrook Intellectual Property Company LLC
InventorsFernand A. Thomassy, Charles B. Lohr, Brad P. Pohl, David Brian Jackson
Life of this patent
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Abstract
A continuously variable transmission capable of operating in a forward direction or reverse direction may be controlled in the reverse direction by providing an initial skew angle in a first skew direction, followed by a set or sequence of skew angle adjustments in an opposite direction to prevent runaway or other unintended consequences. A continuously variable transmission may include a timing plate to maintain all planets at an angle or within a range of an angle in forward and reverse operations.
Claims14
A method for controlling tilt angle in a ball planetary continuously variable transmission (CVT) comprising a first carrier comprising a plurality of first slots and a second carrier comprising a plurality of second slots and at least one planet axle extending from a first particular slot of the plurality of first slots to a second particular slot of the plurality of second slots, the method comprising:
- operating the CVT in a design direction of rotation, including rotating the first carrier of the CVT in a first direction to a first skew angle of the planet axle associated with a desired tilt angle of the planet axle;
- and
- operating the CVT in a reverse direction of rotation, including
- rotating the first carrier of the CVT in a second direction opposite the first direction to a second skew angle of the planet axle;
- monitoring the CVT to determine a change in a tilt angle of the planet axle;
- and
- rotating the first carrier in the first direction to a third skew angle of the planet axle, the third skew angle resulting in the CVT having the desired tilt angle of the planet axle.
A continuously variable transmission (CVT), comprising:
- a variator, comprising an array of planets orbital about a longitudinal axis, each planet having a planet axle defining a planet axis of rotation, a first ring in contact with the array of planets and orbital about the longitudinal axis, the first ring being on a first side of the array of planets, a second ring in contact with the array of planets and orbital about the longitudinal axis, the second ring being on a second side of the array of planets, a sun located radially inward of and in contact with the array of planets, a first carrier comprising a plurality of first slots, each first slot configured for receiving a first end of a planet axle, and a second carrier opposite the first carrier and comprising a plurality of second slots, each second slot configured for receiving a second end of the planet axle;
- an actuator coupled to at least one of the first carrier and the second carrier;
- and
- a controller communicatively coupled to the actuator, the controller comprising a processor and memory storing a set of instructions executable by the processor to perform determining if the variator is operating in a design direction or a reverse direction;
- the controller being configured to, when the variator is operating in a design direction, determine a desired tilt angle for the array of planets and send a signal to the actuator to rotate the first carrier in a first direction to a first skew angle;
- and the controller being configured to, when the variator is operating in a reverse direction, determine the desired tilt angle for the array of planets, send a first signal to the actuator to rotate the first carrier in a second direction opposite the first direction to a second skew angle, monitor the CVT to determine a change in the tilt angle, and send a second signal to rotate the first carrier in the first direction to a third skew angle that adjusts the CVT to the desired tilt angle.
Dependencies are inferred from the claim text.