| 摘要 |
PURPOSE: To facilitate detection of a disconnection failure of an energizing current to a coil and to prevent the occurrence of a problem wherein a relation between the opening of a valve and an energizing current forms hysteresis characteristics by alternately repeating a normal direction energization mode and a reverse direction energization mode and detecting the energizing states of an H-shape bridge circuit and a coil. CONSTITUTION: A forward direction energization mode wherein first and third switches T1 and T4 brought into the diagonal line relation of an H-shape bridge circuit 70 are turned ON and second and fourth switches T2 and T3 are turned OFF is executed during an ON duty period of an opening command signal. Further, a reverse direction energization mode wherein the first and third switches T1 and T4 are turned OFF and the second and fourth switches T2 and T3 are turned ON is executed during an OFF duty period of an opening command signal. In this case, since during normal operation, an H-shape bridge circuit 70 and a coil 61 are constantly energized regardless of an opening, when energization is disconnected, it is judged that disconnection of the feed to the H-shape bridge circuit 70 and the coil 61 is caused. |
