Device for controlling the intake air temperature of a mixture-compressing internal combustion engine

In an air intake system supplying combustion air to an internal combustion engine which compresses and burns a mixture of fuel and combustion air obtained either by means of a carburetor or through the injection of fuel into the air intake system, in such a system, a device for controlling the intake air temperature comprising:

• a raw air duct including a cold air intake duct with an inlet for raw air of ambient temperature, a transversely oriented warm air intake duct connected to a source of preheated raw air and joining the cold air intake duct in a duct junction, and a raw air mixing duct downstream of the duct junction;
• a flow proportioning valve arranged in the area of the duct junction, the flow proportioning valve being movable between two end positions, in a first one of which said valve closes off the warm air intake duct while opening the cold air intake duct, and in the second one of which said valve closes off the cold air intake duct while opening the warm air intake duct, the valve being movable to intermediate positions in which both intake ducts are partially open for the admission to the raw air mixing duct of both cold raw air and preheated raw air, in proportions determined by the valve position;
• a thermostat chamber defined by chamber walls which are solidary with the raw air duct, the thermostat chamber having a calibrated warm air branch inlet for the supply of a branch flow of preheated raw air from the warm air intake duct to the thermostat chamber, a calibrated cold air branch inlet for the supply of a branch flow of ambient raw air from the outside to the thermostat chamber, and an outlet through which said branch flows rejoin the flow of combustion air which is supplied to the internal combustion engine by the air intake system;
• a wax thermostat arranged in the thermostat chamber downstream of the calibrated branch inlets for preheated raw air and ambient raw air and upstream of said outlet, the thermostat and the walls of the thermostat chamber forming a flow gap for the passage of said branch flows, the cross section of said flow gap being a fraction of the smallest flow cross section of the raw air mixing duct;
• and
• drive means for connecting the wax thermostat to the flow proportioning valve in such a way that an expansion of the wax thermostat in response to an increase in its temperature produces a displacement of the flow proportioning valve in the direction of said first valve end position and a contraction of the wax thermostat in response to a decrease in its temperature produces a displacement of the flow proportioning valve in the direction of said second valve end position.