Air conditioning control service water warm detection device

摘要

PURPOSE: To accurately detect the water temperature detection signal for controlling an air conditioner by using a water temperature sensor for displaying the water temperature of the engine cooling water in common even when the DC power voltage has a fluctuation. ;CONSTITUTION: A water temperature sensor 1 is connected to the output terminal V1 of an on-vehicle battery in series to a water temperature display meter 2. A control circuit 3 detects the terminal voltage VIG from the output terminal V1 and the terminal voltage VB from the water temperature sensor 1. The terminal voltage VIG is divided by voltage dividing resistors 4, 5 to obtain the detection voltage VC. The detection voltage VC is outputted by a correcting circuit 6 as the correction detection voltage VC. When the fluctuation of the terminal voltage VB of the water temperature sensor 1 due to the fluctuation of the terminal voltage VIG becomes the change point voltage VD or above of the characteristic approximated with a polygonal line, the correcting circuit 6 feeds a current via a shunt resistor 8 to obtain the correction detection voltage VC. The detection signal in response to the cooling water temperature is obtained based on the terminal voltage VB of the water temperature sensor 1 and the correction detection voltage VC.;COPYRIGHT: (C)1995,JPO