Windscreen washer with automatic water temp control - uses cold conductor resistance to heat water

摘要

The spray nozzle (11) is clamped to the car bodywork (10) with the insulating washers (15) and nut (14). The washers (15) insulate the nozzle both electrically and thermally. A cold conductor resistance (17) is clamped between the mica washers (16) by the nut (18). The water supply is connected to the inlet (13). The cold conductor resistance is connected by the leads (19, 20) to the battery (21). The characteristic of the cold conductor resistance (17) is such that above a fixed threshold temperature the resistance increases sharply. At low temperatures the cold conductor resistance heats the water but reduces the current sharply if the threshold temperature is exceeded so maintaining a constant temperature.