| 摘要 |
PURPOSE:To make it possible to detect an operational failure in an electronic expansion valve simply and definitely without separating the electronic expansion valve from a refrigerant circuit. CONSTITUTION:When an excitation pulse current is output from a drive circuit 14, a magnet roller of an electronic expansion valve 1 rotates. A hole device 11 detects the displacement of a magnetic pole of this magnet roller. This detection pulse number is transmitted to an up-down counter 16 by way of an amplifier 13 and a rectifier 15 and counted there. On the other hand, a magnetic pole pulse number is counted by an up-down counter 17. A failure discrimination means 18 discriminates the operation as normal when the count numbers of both counters agree whereas it discriminates the operation as failure when both counters disagree.
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