Heating of intake air (Renault 19)

Control device for heating the intake air in the air pipe (snorkel) on the "C" type engine, as well as the 1.7-liter "F" type engine.



The valve of the intake air preheating distributor, controlled by a thermoelement in the mixing chamber of the air filter housing, is designed to maintain the optimum temperature of the air sucked in by the engine. This is necessary for the following reasons.

• In cool weather, the quality of the working mixture is better if the intake air is supplied to the engine already warmed up. Of course, at a higher ambient temperature, the engine should not receive warm intake air, since warm air has a larger volume than an equal amount of cold air.
• Preventing freezing. Freezing occurs due to a drop in pressure in the injection system when the engine is running, and part of the fuel evaporates and cools down significantly. Because of this, the injection system housing cools down, and at a temperature of +3°C to +8°C and high air humidity, a thin layer of ice can form in the injection system, which interferes with high-quality mixture formation.

Air filter for single-point injection system Bendix. For monitoring the performance of the wax thermostat (shown by the arrow in the left figure) direct a stream of hot air from a hair dryer at the sensor - the valve flap should move relatively quickly inward (arrow on the right picture).




Elements of the intake air heating device:

• The main element of the intake air heating device is the mixing chamber.
• The mixing chamber contains a snorkel (pipe) for intake air, which has two inlet openings. Cold air enters through one opening, and heated air from the intake manifold preheating container enters through the other.
• A valve in the air filter housing snorkel mixes cold air from one intake port with heated air from a preheater container on the exhaust manifold of the muffler, so that the air entering the injection system has the optimum temperature for creating the working mixture.
• The mixing chamber contains a wax thermostat connected to a spring-loaded valve.
• If the temperature of the air sucked in with the preheating container valve open is above +26°C, the wax in the casing begins to melt. In doing so, it expands and slowly closes the valve.
• When the temperature reaches +36°C, the valve completely closes the access of heated air and opens the passage in the intake snorkel for cold air.