ENGINE COOLING FAN OPERATING CONDITION SETTING CIRCUIT ON THE BASIS OF COOLING-WATER TEMPERATURE

摘要

PURPOSE:To properly control the revolution and stop of a cooling fan by driving the fan so that a relatively high inlet-side temperature can be obtained when the temperature difference between the inlet side and the outlet side of a radiator is large and a relatively low inlet-side temperature can be obtained when said difference is small. CONSTITUTION:Each detected output of the temperature detection elements RX1 and RX2 such as thermistors for detecting the outlet-side cooling-water temperature and the inlet-side cooling-water temperature of a radiator is amplified and input into the respective reversal input and non-reversal input of a comparator CMP1. Said comparator CMP1 outputs the temperature difference between the inlet side and the outlet side into the reversal input of a comparator CMP2, and the temperature on the inlet side is input into the non-reversal input of the comparator CMP2. Therefore, when the temperature difference is large between the inlet side and the outlet side, the set value of the comparator CMP2 is increased, and the inlet-side temperature at which a cooling fan is driven is increased.