Security circuit for a cooling fluid temperature-control device of an internal-combustion engine

Claim 1

A device for cooling an internal combustion engine, comprising at least a motor-fan unit (1) which is associated with the heat-carrying cooling fluid circuit of the engine and which is supplied with power as a function of a temperature-measuring signal delivered by a sensor mounted in said heat-carrying fluid circuit, a first source of reference (8, 9) and a first comparator (11) connected by one of its inputs to this source and by the other of its inputs to a point (12; 39; 55) representing said measuring signal, said comparator being connected by its output to a relay (18) whose moving contact (3) is connected in the motor circuit (1) of the motor fan unit in such manner that it connects this motor directly to the supply source (2) when the temperature of the heat-carrying fluid reaches a predetermined value, this cooling device comprising a second reference source (51) and a second comparator (40) whose output signal is used for piloting regulating means (51) also connected in the supply circuit of the motor fan unit (1) for determining the power supply thereof as a function of the temperature, this device being characterised in that said regulating means (51) is a power semi-conductor adapted to ensure the continuous regulation of the power supply of the motor fan unit within a predetermined temperature range, the contact (3) of said relay (18) being connected in parallel with the power circuit of said semi-conductor, and the set value point of the first reference source is chosen at a value corresponding to the maximum temperature that the internal combustion engine can reach without deterioration.

Claim 2

A device for cooling an internal combustion engine, comprising at least a motor-fan unit (1) which is associated with the heat-carrying cooling fluid circuit of the engine and which is supplied with power as a function of a temperature-measuring signal delivered by a sensor mounted in said heat-carrying fluid circuit, a first source of reference (8, 9) and a first comparator (11) connected by one of its inputs to this source and by the other of its inputs to a point (12; 39; 55) representing said measuring signal, said comparator being connected by its output to a relay (18) whose moving contact (3) is connected in the motor circuit (1) of the motor fan unit in such manner that it connects this motor directly to the supply source (2) when the temperature of the heat-carrying fluid reaches a predetermined value, this cooling device comprising a second reference source (51) and a second comparator (40) whose output signal is used for piloting regulating means (51) also connected in the supply circuit of the motor fan unit (1) for determining the power supply thereof as a function of the temperature, this device being characterised in that said regulating means (51) is a power semi-conductor adapted to ensure the continuous regulation of the power supply of the motor fan unit within a predetermined temperature range, the contact (3) of said relay (18) being connected in parallel with the power circuit of said semi-conductor, and the set value point of the first reference source is chosen at a value corresponding to the maximum temperature that the internal combustion engine can reach without deterioration.