Patent ID: 9273790
Filing Date: 2016-03-01
CPC Classification: F02B,F02D,F16K,Y02T

Claim Text:
1. An electric driving apparatus comprising: an electric motor generating a driving force while receiving an electric current; an electric current detecting means for detecting the electric current supplied to the electric motor, and a control means for controlling an energization to the electric motor so that the driving force is transmitted to a driven member in order to vary a displacement magnitude which represents at least one of a variation in position of the driven member and a variation in posture of the driven member, wherein the displacement magnitude includes a hold value at which the driven member is mechanically held and the displacement magnitude does not vary even though the driving force is continued to be transmitted from the electric motor to the driven member so as to vary the displacement magnitude in one direction, the electric current supplied to the electric motor is stepwise increased when the displacement magnitude reaches the hold value after the displacement magnitude has been varied in one direction, the control means stores a threshold regarding the electric current supplied to the electric motor for determining whether the displacement magnitude normally reaches the hold value in a case that the electric motor is controlled in such a manner that the displacement magnitude reaches the hold value after the displacement magnitude has been varied in one direction, after the electric motor is energized, the electric current exceeds the threshold temporarily due to the inrush current, then the electric current is lowered than the threshold, and when the electric current excesses the threshold again, the control means determines that the displacement magnitude has normally reached the hold value, the electric motor includes a rotor having a plurality of coils and a plurality of commutators, a stator having a plurality of magnets, and two brushes being in contact with the commutators to supply the electric current to the coils, the electric motor generates a rotational torque, the control means includes a lock-current estimating means for estimating a lock-current which is supplied to the electric motor after the displacement magnitude has reached the hold value, when the displacement magnitude reaches the hold value, the rotor stops and each of the brushes is in contact with the single commutator, the lock-current is denoted by “Ia”, when at least one of brushes is in contact with the multiple commutators, the lock-current is denoted by “Ib”, the control means stores a lock-current ratio “Ia/Ib”, and the threshold is defined in such a manner as not to exceed an upper value which is obtained by multiplying the estimated lock-current and the lock-current ratio “Ia/Ib”.