| 摘要 |
<p>PURPOSE:To perform self-diagnosis of functions of the whole of the unit, by using a thermocouple as a sensor and by constituting the unit so that electricity may be supplied to the thermocouple at an engine start time to diagnose functions of the alarm unit on a basis of generated voltage drop. CONSTITUTION:The unit is constituted by connection part 1 of the thermocouple of a temperature sensor, switching unit 2, and alarm lamp 3. Now, when starter switch 5 is turned on, electricity is supplied from battery 9 to thermocouple strands r110 and r2111 through current limiting resistance Rs 10 simultaneously with operation start of the temperature alarm unit. For example, when r1+r2=3OMEGA, Rs= 500OMEGA, and the battery voltage=8V are true, 50mv is generated at the input terminal of the comparator. The normal operation voltage of the comparator is 40mv and corresponds to approximately 1,000 deg.C for the Chromel.Alumel thermocouple. Transistor 12 is turned on to turn off transistor 7 only when the thermocouple is disconnected. That is, alarm is not issued at a start time unless defects of the unit such as disconnection of the sensor exist, so that self-diagnosis of functions of the whole of the unit can be performed.</p> |
