EP2061959B1 - System for cooling the propulsion unit of a motor vehicle and method for controlling such a system - Google Patents

Abstract

System for cooling the propulsion unit of a motor vehicle comprising a main circuit for cooling a first part of the propulsion unit to a first temperature level, a secondary circuit for cooling a second part of the propulsion unit to a second temperature level, the system comprising a radiator (2) subdivided into at least one main compartment (23) and one secondary compartment (24), the main circuit comprising the main compartment (23), the secondary circuit comprising the secondary compartment (24), the main compartment (23) comprising an inlet orifice (20) and a communication orifice (26) for communicating with the secondary compartment (24), the secondary compartment (24) further comprising an outlet orifice (25), the secondary circuit, in a secondary mode of embodiment, comprising the main compartment (23), characterized in that the main compartment comprises an intermediate connection (21), said intermediate connection (21) and the communication orifice (26) being separated by a cooling zone of the first compartment (23).

Description

The invention relates to a cooling system for a motor vehicle powertrain of the type comprising a main circuit and a secondary circuit for cooling parts of the powertrain at different temperature levels.

A powertrain comprises for example a heat engine requiring to be maintained at a temperature level of the order of 90 ° C to 105 ° C. This powertrain may include accessories requiring cooling to a lower temperature level, between 30 and 70 ° C, or as low as possible. These accessories include, for example, a charge air cooler, a recycled gas exchanger, an electric motor, its electronic power supply system or batteries.

This is done using a water cooling circuit comprising a radiator traversed by a flow of ambient air. However, to ensure two different temperature levels, it has been proposed cooling systems having two cooling circuits, either independent or with common parts.

The document FR-A1-2815402 shows a cooling system of this type. The system is used to cool a heat engine to a first temperature level and an electric motor and its control unit to a second temperature level through a secondary circuit. The system has a radiator subdivided into compartments. The secondary circuit is a branch of the main circuit and has one of the compartments, called secondary.

The secondary compartment of this system is completely dedicated to the secondary circuit. However, in certain situations where the main circuit is not connected to the radiator, for example during the cold start phase, it would be interesting to use a larger part of the radiator to lower the temperature of the secondary circuit.

With these objectives in view, the invention relates to a cooling system of a motor vehicle powertrain, comprising a main circuit for cooling a first part of the powertrain to a first temperature level, a secondary circuit for cooling a second part of the power train at a second temperature level, the system comprising a radiator subdivided into at least one main compartment and a secondary compartment, the main circuit comprising the main compartment, the secondary circuit comprising the secondary compartment. The secondary circuit, in a secondary mode of operation, comprises the main compartment.

The system according to the invention makes it possible to circulate the fluid of the secondary circuit also in the main compartment, which allows a better cooling of the fluid, and therefore operation with a lower temperature than in the prior art.

According to one embodiment, the main compartment has an inlet port, an intermediate connection and a communication port with the secondary compartment, the secondary compartment further comprising an outlet port, the intermediate connection and the communication port being separated by a cooling zone of the main compartment. The fluid flowing in the secondary circuit exits the radiator through the outlet after passing through the communication port and the secondary compartment. But before, it has passed through a cooling zone of the main compartment from the intermediate connection or the inlet port. As a result, its temperature has already dropped since entering the radiator and continues to be lowered through the secondary compartment.

In a particular way, the secondary circuit comprises a secondary branch connected to the outlet port and including a secondary pump and a cooling element of the power train. The element to be cooled receives a fluid having passed through a part of the main compartment and the secondary compartment, and therefore at the lowest possible temperature.

In a complementary manner, a common branch is connected to the main circuit, to the intermediate connection and to the secondary branch. Depending on the mode of operation chosen, the common branch can receive the return fluid of the secondary circuit which enters the main compartment through the intermediate connection, then rejoins the secondary compartment through the main compartment. According to another mode of operation, the main circuit fluid exits the main compartment by the common branch while a part of the fluid flows in the secondary compartment and the secondary branch before joining the flow in the main circuit. Thus, for example, in the case where the element to be cooled is a recycled gas exchanger, the maximum cooling is ensured by the low temperature of the fluid in the secondary circuit. When the engine is operating at full load, the exhaust gases no longer circulate in the recycled gas exchanger and the fluid in the secondary circuit is not reheated. This fluid is injected into the main circuit and contributes to the cooling of the engine at a time when the power to be evacuated is important. All the compartments of the radiator contribute to the cooling of the engine.

According to an improvement, the radiator comprises at least one primary compartment upstream of the main compartment. It is thus certain that the fluid that arrives from the main circuit and goes to the secondary circuit via the communication orifice has passed through the cooling zone of the primary compartment.

According to a particular provision, the secondary compartment is a separate element of the main compartment. This allows give more flexibility to integrate the radiator into the vehicle architecture.

The invention also relates to a control method of a system as described above. According to this method, the system is controlled in a secondary operating mode in which a fluid from the secondary pump and the element to be cooled circulates in the main compartment and then in the secondary compartment, the radiator being disconnected from the main circuit.

In a main mode of operation, the coolant from the main circuit enters the radiator and is subdivided into a flow to the main compartment and a flow to the secondary compartment.

• la figure 1 est une vue schématique d'un système de refroidissement conforme à l'invention ;
• la figure 2 est une vue similaire à la figure 1 du système dans un mode de fonctionnement secondaire ;
• la figure 3 est une vue similaire à la figure 1 du système dans un mode de fonctionnement principal ;
• les figures 4 à 6 sont des vues schématiques de radiateurs selon des variantes du système de la figure 1 ;
• la figure 7 est une vue similaire à la figure 2 avec le radiateur de la figure 5.

The invention will be better understood and other features and advantages will appear on reading the description which follows, the description referring to the appended drawings among which:

• the figure 1 is a schematic view of a cooling system according to the invention;
• the figure 2 is a view similar to the figure 1 the system in a secondary mode of operation;
• the figure 3 is a view similar to the figure 1 the system in a main mode of operation;
• the Figures 4 to 6 are schematic views of radiators according to variants of the system of the figure 1 ;
• the figure 7 is a view similar to the figure 2 with the radiator of the figure 5 .

A cooling system according to the invention, according to a first embodiment as represented on the Figures 1 to 3 , comprises a thermal motor 1, a radiator 2 and a pump main 3 downstream of the engine. The engine 1 is connected to an inlet port 20 of the radiator via a thermostatic valve 4. The radiator 2 is connected to the main pump 3 from an intermediate connection 21 by way of a branch 9. The main pump 3 is able to circulate a heat transfer fluid through the engine 1, the thermostatic valve 4, the radiator 2 and the common branch 9. The system further comprises, in parallel with the engine 1, a storage vessel. expansion 6 and a heater 5 for heating the passenger compartment.

A secondary branch 7 is connected to the radiator 2 at an outlet port 25 and comprises a secondary pump 71 and an element to be cooled 72 such as a recycled gas exchanger. The secondary branch 7 also connects to the common branch 9.

The radiator 2 has three compartments: a primary compartment 22 connected to the inlet port 20, followed by a main compartment 23 connected to the intermediate connection 21, and a secondary compartment 24 connected to the outlet port 25 and the compartment The radiator 2 conventionally comprises a first collector 27 and a second collector 28 parallel to each other, in communication with each other by a plurality of parallel channels, perpendicular to the direction of the collectors 27, 28. The channels 29 form cooling zones through which air can circulate to cool the fluid contained in the channels 29. To establish the compartments, the first collector 27 has a first partition 271 and a second partition 272 separating the first collector 27 in three zones without possible direct circulation of fluid between them. Each zone corresponds respectively to the primary compartment 22, the main compartment 23 and the secondary compartment 24.

In a first mode of operation of the cooling system, when the engine 1 is not yet sufficiently hot, the thermostatic valve 4 closes the circulation of the fluid. The main pump 3 thus circulates the heat transfer fluid through the engine 1, then in parallel through the expansion vessel 6 and the heater 5 before returning to the main pump 3 by the common branch 9. This establishes the main circuit in this mode of operation, said secondary mode of operation, illustrated by the figure 2 . At the same time, the secondary pump 71 circulates the heat transfer fluid through the recycled gas exchanger 72, then to the main compartment 23 via the common branch 9 and the intermediate connection 21, and finally to the secondary compartment 24 through the communication port 26. The fluid returns to the secondary pump 71 by the secondary branch 7 through the outlet port 25. This establishes the secondary circuit in the secondary mode of operation.

In the secondary mode of operation, the maximum cooling in the recycled gas exchanger 72 is ensured, which makes it possible to introduce a large quantity of recycled gases into the engine 1, because these have a high density with a temperature of 100.degree. weaker possible. The cooling is ensured by the passage of the fluid through the main compartment 23 and the secondary compartment 24.

In another mode of operation, said principal and illustrated by the figure 3 , the thermostatic valve 4 opens the circulation of the fluid. The main pump 3 thus circulates the coolant through the engine 1, then in parallel through the expansion vessel 6, the heater 5 and the radiator 2 before returning to the main pump 3 by the common branch 9. This sets the main circuit in the main operating mode. This main mode of operation is implemented when the engine 1 is hot, that is to say when the fluid at the output of the engine 1 has a temperature greater than 90 ° C for example. At the same time, the secondary pump 71 circulates a part of the heat transfer fluid circulating in the radiator 2 through the secondary compartment 24, then through the recycled gas exchanger 72, before the fluid joins the flow of the circuit fluid in the common branch 9 to the main pump 3. This establishes the secondary circuit in the main operating mode. The fluid flowing in the secondary circuit is first cooled in the primary compartment 22, passes into the second manifold 28 and then into the secondary compartment 24.

In a variant of the first embodiment, the radiator 2a may be in two parts, as shown in FIG. figure 4 , where the secondary compartment 24a is a separate element connected to the main compartment 23a through a communication conduit 26a. The communication line 26a plays the same role as the communication port 26.

In a second embodiment of the invention, the radiator 2b has no primary compartment 22, unlike the first embodiment. Referring to Figures 5 and 7 the inlet port 20b is on the second manifold 28b, while the outlet port 25b and the intermediate connection 21b are on the first manifold 27b. The figure 7 represents the secondary mode of operation when the thermostatic valve 4 is closed. The heat transfer fluid from the secondary branch 7 by the common branch 9 to the main compartment 23b then circulates throughout the main compartment 23b, then in the secondary compartment 24b which allows optimum cooling using the entire surface of the radiator 2b.

In a variant of the second embodiment, the radiator 2c may be in two parts, as shown in FIG. figure 6 , where the secondary compartment 24c is a separate element connected to the main compartment 23c via a communication conduit 26c. The communication line 26c plays the same role as the communication port 26.

Claims (7)

1. System for cooling the propulsion unit of a motor vehicle comprising a main circuit for cooling a first part of the propulsion unit down to a first temperature level, a secondary circuit for cooling a second part of the propulsion unit down to a second temperature level, the system comprising a radiator (2) subdivided into at least one main compartment (23) and one secondary compartment (24), the main circuit comprising the main compartment (23), the secondary circuit comprising the secondary compartment (24), the main compartment (23) comprising an inlet orifice (20) and a communication orifice (26) communicating with the secondary compartment (24), the secondary compartment (24) also comprising an outlet orifice (25), the secondary circuit, in a secondary mode of operation, comprising the main compartment (23), characterized in that the main compartment comprises an intermediate connection (21), the said intermediate connection (21) and the communication orifice (26) being separated by a cooling zone of the main compartment (23).
2. System according to Claim 1, in which the secondary circuit comprises a secondary branch (7) connected to the outlet orifice (25) and including a secondary pump (71) and an element (72) that is to be cooled belonging to the propulsion unit.
3. System according to Claim 2, in which a common branch (9) is connected to the main circuit, to the intermediate connection (21) and to the secondary branch (7).
4. System according to Claim 1, in which the radiator (2) comprises at least one primary compartment (22) upstream of the main compartment (23).
5. System according to Claim 1, in which the secondary compartment (24) is an element separate from the main compartment (23).
6. Method of controlling a system according to one of Claims 1 to 5, in which the system is controlled in a secondary mode of operation, characterized in that a fluid from the secondary circuit circulates through the main compartment (23) then through the secondary compartment (24), the radiator (2) being disconnected from the main circuit.
7. Control method according to Claim 6, in which, in a main mode of operation, the coolant from the main circuit enters the radiator (2) and splits into a stream heading for the main compartment (23) and a stream heading for the secondary compartment (24).

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