| 摘要 |
PURPOSE:To reduce the size by thermally coupling a PTC thermistor composed of such material as having the switching temperature in the range of 90 deg.C-120 deg.C, partially or entirely, with a solenoid and connecting electrically in series. CONSTITUTION:A doughnut type PTC thermister 3 is fitted in a hollow casing 5 forming a solenoid so that the PTC thermistor 3 is thermally coupled, partially or entirely, with the solenoid (The drawing shows the case of entire coupling). Then the thermistor 3 is electrically coupled in series with a solenoid 2, and current is fed from a power source 1 through a switch 4. The thermistor 3 is composed of barium titanate(BaTiO3) series ceramic which is available easily with low cost. By such arrangement, small overheat preventer can be formed and overcurrent can be limited repeatedly. It is preferably employed in the trunk latch or door latch of automobile. |
