Patent ID: 7997317

Claim:
A tire inflation device comprising: a pump assembly configured to be housed within a hub of a wheel, the pump assembly including: a piston capable of engaging in reciprocating motion, wherein the piston has a cammed surface and is configured such that the motion of the piston as it reciprocates is axial with respect to the axis of rotation of the wheel; a hub actuator that is rotationally fixed relative to the axle of the wheel when the pump is operating, the hub actuator being configured to ride the cammed surface of the piston, thereby driving the reciprocating motion of the piston as the wheel is rotated; and a switch assembly housed within the wheel's hub configured to unlock the actuator from the axle when the terminal tire pressure is reached, the switch assembly comprising: a switch release ball operably engaged with a switch release pin; a switchpin housed within a switchpin channel; a switchball operably engaged with the switchpin, a switchspring, and the switch release ball; and a switch release sleeve configured to move in concert with the switch release pin and operably engaged with the piston; wherein when the pump is operating and tire has not yet reached the terminal tire pressure, the switchspring urges the switchball against the switchpin such that the switch release ball is in contact with and balanced against the switchball, thereby locking the switch release sleeve against the piston, the piston against the actuator, and the actuator to the axle; and when the terminal tire pressure is met, air that is being forced out of the air chamber by movement of the piston places sufficient pressure on the switchpin to cause movement of the switchpin, thereby allowing the switch release ball to move relative to the switch release pin, thereby releasing the switch release sleeve from the piston, the piston from the actuator, and the actuator from the axle.