EP0670414B1 - Cooling system for an internal combustion engine - Google Patents

Description

The present invention relates to a system of cooling for a combustion engine internal fitted to a motor vehicle. The invention relates more particularly to a cooling system adapted to allow the cooling of the alternator driven by the engine.

Alternators of combustion engines internal are usually fixed on a support mounted on the wall of the engine block so that allow the rotor shaft to be driven by the crankshaft through a simple belt. However, alternators are made up of electrical components that no longer work perfectly reliable when the temperature room becomes too high.

As a result, the release of heat produced by the alternator in operation and by the engine environment, increase in ambient temperature making necessary to provide a device for alternator cooling.

The most common method of ensuring correct cooling of an alternator consists by adding one or more fans internal or external integral with the shaft of the rotor. However, this method does not allow always sufficient cooling in particular for vehicle alternators automobile whose performance is increasing higher in more and more space reduced.

Another method that provides more efficient cooling has been developed in particular in document FR-A-2,658.959. She consists in creating channels in the alternator and to circulate the collecting liquid therein calories used to cool the engine. The document JP-A-83557/1984 thus discloses a system liquid cooling for a motor motor vehicle adapted to allow coolant circulation at inside the alternator.

According to this document of the prior art the alternator cooling system is connected to the liquid inlet manifold engine block cooling. The integration of the alternator in the cooling system at pump outlet and parallel to the block motor (see also US-A-4,864,974) makes balancing flow rates difficult and does not ensure sufficient flow of the coolant through the alternator and therefore ensure satisfactory cooling of the last.

The object of the present invention is further improve the efficiency of a liquid cooling for internal combustion of motor vehicle allowing to carry out in a simple way the alternator cooling.

The liquid cooling system for internal combustion engine fitted to a motor vehicle according to the invention comprises a internal circuit passing through the engine block, a main liquid / air type heat exchanger and a pump driving the liquid.

According to the invention the system of cooling is characterized in that it includes a derivative cooling system serving an alternator driven by the engine by which the coolant introduced in the alternator is taken from the circuit internal of the engine block and is driven back to the inlet of said internal circuit and the circuit bypass cooling has a heat exchanger secondary liquid / air disposed upstream of the alternator.

According to a preferred characteristic of the system cooling object of the invention, the circulation within the circuit derivative cooling is controlled by a thermostat.

According to a preferred characteristic of the system cooling object of the invention, the circuit alternator cooling derivative is connected on the one hand, upstream in the direction of the coolant flow, at the pipe that connects the output of the internal circuit from the engine block to the inlet of the heat exchanger main, and secondly downstream, to the pipe which connects the outlet of the heat exchanger main heat at the input of the internal circuit of the engine block.

According to another preferred characteristic of the system cooling object of the invention, the structural characteristics of the heat exchanger main heat and secondary heat exchanger are adapted according to the respective flow rates of coolant flowing through them.

According to another preferred characteristic of the system cooling object of the invention, the main heat exchanger and the exchanger secondary are arranged in two separate places of the engine compartment.

• la figure 1 représente schématiquement un système de refroidissement selon l'invention.

The objects, aspects and advantages of the present invention will be better understood from the description given below of an embodiment of the invention applied to an internal combustion engine, this embodiment being given by way of non-limiting example, with reference to the appended drawing, in which:

• Figure 1 schematically shows a cooling system according to the invention.

Figure 1 therefore presents a system of cooling, identified by reference 1 on the drawing, by liquid (usually water with antifreeze and anticorrosion product) more particularly intended for cooling of an internal combustion engine 2 for example of the multicylinder type equipping a motor vehicle. Only the necessary elements to the understanding of the invention have been figured.

The liquid cooling system presented conventionally includes an internal circuit 12 (also called water chambers) crossing the engine block 2 to cool the combustion. The coolant is cooled by a sweep of air in a radiator consisting of a main heat exchanger 4 liquid / air. The liquid is driven by a pump 3 placed immediately upstream of the internal circuit 12 of engine 2. Line 10 connecting output of internal circuit 12 at the exchanger main 4 has a thermostat 5 which defines a bypass connection 13 serving an air heater 6 for home heating and a vase expansion 7. A pipe 11 ensures the return liquid from the main exchanger 4 at the inlet of the internal circuit 12.

The cooling system includes plus a branched cooling circuit 14 comprising a secondary liquid / air exchanger 8 and the alternator 9. Following the completion of the invention, the coolant introduced into the alternator is taken at the outlet of the internal circuit 12 of the motor 2 and is driven back to the entrance to the latter.

To this end, circuit 14 of alternator 9 cooling is connected on the one hand, upstream in the direction of flow coolant, to line 10 which connects the output of the internal circuit 12 of the block motor 2 at the inlet of the heat exchanger main 4, the connection can be made before (see figure 1) or after thermostat 5, and on the other hand downstream, to line 11 which connects the outlet of the main heat exchanger 4 at the input of the internal circuit 12 of the engine block 2.

The connection of the branch circuit 14 intended when the alternator 9 cools, at the outlet of the internal circuit 12 of the motor 2, allows to significantly increase the flow of liquid to through the alternator 9 whatever the point of engine operation, and therefore improve eliminating calories compared to known systems in which the derivative circuit is supplied upstream of the internal circuit 12 of the motor 2. The higher temperature of the outgoing liquid of motor 2 is largely attenuated by the exchanger secondary temperature 8 disposed upstream of the alternator 9.

By the way, in art systems previous the amount of additional heat transmitted to the coolant by alternator 9 requires increasing power drainable by the main exchanger 4. The solution adopted in accordance with the present invention to use a secondary exchanger 8 arranged in the derivative circuit in which only one circulates part of the overall flow reduces the necessary exchange surfaces, moreover this secondary exchanger can be geographically separate from the main exchanger, which allows optimize the implementation of the cooling in the engine compartment of the motor vehicle. Separation of exchangers heat 4 and 8 also allows to use for each of them technical solutions offering different heat exchange characteristics (shapes of fins, beams, etc.).

The functioning of such a system is the following. When the engine is cold, thermostat 5 is closed and the liquid does not circulate in the main exchanger 4 but only in the branch circuit 14 and in bypass circuit 13 serving the heater 6. When the engine heats up the thermostat opens allowing the liquid to circulate all at once in the main exchanger 4, in the air heater 6, and in the branch circuit 14 serving the alternator 9.

Of course, the invention is by no means limited to the embodiment described and illustrated which was only given as an example.

Thus, it is possible to order the coolant circulation in the derivative circuit depending on the temperature of the liquid using a specific thermostat or connecting the input of the branch circuit to the liquid outlet pipe that connects the block engine 2 to main heat exchanger 4, or after thermostat 5.

So it is possible instead a specific branch circuit for cooling of the alternator 9 as shown in the figure 1, modify the bypass circuit the air heater to include the water chambers of alternator 9 and heat exchanger secondary 8 which are then arranged in series with the air heater 6.

Claims (5)

1. A fluid cooling system for an internal combustion engine (2) of an automobile vehicle, comprising an internal circuit (12) passing through the engine block (2), a main heat exchanger (4) of the fluid/air type and a pump (3) driving the fluid, characterised in that it comprises a branch cooling circuit (14) serving an alternator (9) driven by the engine (2) via which the cooling fluid introduced into the alternator (9) is taken up at the outlet of the internal circuit (12) of the engine block (2) and is returned to the inlet of this internal circuit (12), this branch cooling circuit (14) comprising a secondary fluid/air exchanger (8) disposed upstream of the alternator (9).
2. A fluid cooling system as claimed in claim 1, characterised in that the circulation within the branch cooling circuit (14) is driven by a thermostat.
3. A fluid cooling system as claimed in any one of claims 1 to 2, characterised in that the branch cooling circuit (14) of the alternator (9) is connected, on the one hand, upstream in the direction of flow of the cooling fluid, to the duct (10) which connects the outlet of the internal circuit (12) of the engine block (2) to the inlet of the main heat exchanger (4), and on the other hand, downstream, to the duct (11) which connects the outlet of the main heat exchanger (4) to the inlet of the internal circuit (12) of the engine block (2).
4. A fluid cooling system as claimed in any one of claims 1 to 3, characterised in that the structural characteristics of the main heat exchanger (4) and the secondary exchanger (8) are adapted as a function of the respective rates of flow of cooling fluid passing through them.
5. A fluid cooling system as claimed in any one of claims 1 to 4, characterised in that the main heat exchanger (4) and the secondary exchanger (8) are disposed at two separate locations of the engine compartment.

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