Valve timing controller

Abstract

A valve timing controller has an electric motor, a control circuit which controls the motor, a first rotor that rotates along with a crankshaft, and a second rotor that is rotates along with a camshaft. A phase adjusting mechanism adjusts the rotational phase between the first rotor and the second rotor according to the rotation of the motor. On condition that the rotating speed of the crankshaft exceeds a threshold value, the control circuit stops the energization of the electric motor. Thereby, the phase adjusting mechanism varies the rotational phase to the most retard phase.

1 . A valve timing controller adjusting a valve timing of an intake valve and/or an exhaust valve of an internal combustion engine, comprising:
 an electric motor which rotates by energization;   an energizing control circuit which controls the energization of the electric motor; and   a phase adjusting mechanism including a first rotor which rotates along with one of a crankshaft and a camshaft of the internal combustion engine, and a second rotor which rotates along with the other, the phase adjusting mechanism adjusting a rotational phase between the first rotor and the second rotor according to the rotation of the electric motor, wherein   in a case that a rotating speed of the internal combustion engine exceeds a threshold value, the energizing control circuit stops the energization of the electric motor so that the phase adjusting mechanism varies the rotational phase to an end phase which is one of a most retard phase and a most advance phase.   
   
   
       2 . A valve timing controller according to  claim 1 , wherein
 the phase adjusting mechanism varies the rotational phase to the end phase which permits start up of the internal combustion engine when the energizing control circuit stops the energization of the electric motor.   
   
   
       3 . A valve timing controller according to  claim 1 , wherein
 in a case that the electric motor rotates in the same rotational phase as the first rotor, the phase adjusting mechanism rotates the second rotor in the same rotational phase as the first rotor, and   in a case that the electric motor rotates in a retard direction relative to the first rotor, the phase adjusting mechanism rotates the second rotor to the end phase relative to the first rotor.   
   
   
       4 . A valve timing controller according to  claim 3 , further comprising:
 a stopper means which stops the second rotor to the first rotor in the end phase.   
   
   
       5 . A valve timing controller according to  claim 3 , wherein
 the threshold value is established lower than the rotating speed of the internal combustion engine when assuming that the electric motor rotates in the same rotational phase as the first rotor and in a maximum speed.   
   
   
       6 . A valve timing controller according to  claim 5 , wherein
 in the phase adjusting mechanism which adjusts the rotational phase by reducing the rotation speed of the electric motor and converting the rotation of the electric motor into the rotation of the second rotor, an actual reduction ratio between the electric motor and the second rotor, and a minimum response speed of the rotation variation of the second rotor at the time of the rotational variation of the electric motor are established,   when the rotation speed of the electric motor changes from a rotation in which the electric motor rotates in the same rotational phase as the first rotor to a rotation in which the electric motor rotates in the maximum speed, the actual reduction ratio is less than a reduction ratio for the phase adjusting mechanism to reduce the rotation speed of the electric motor and to vary the rotation of the second rotor at the minimum response speed.   
   
   
       7 . A valve timing controller according to  claim 6 , wherein
 the actual reduction ratio is greater than a reduction ratio required for the phase adjusting mechanism to reduce the rotation speed of the electric motor and to rotate the second rotor against a transmitting torque from the internal combustion engine.   
   
   
       8 . The valve timing controller according to  claim 7 , wherein
 the phase adjusting mechanism includes a planet gear which engages with a gear provided at least one of the first rotor and the second rotor, and lubricant is supplied to an engagement part of the planet gear and the gear.