EP3374613B1 - Cooling circuit for a motor vehicle - Google Patents

Description

The present invention relates to a cooling device and a cooling method for motor vehicles.

New technologies implemented to reduce fuel consumption and pollutant emissions from motor vehicles often require multiple circuits or temperature control loops.

By thermal regulation loop is meant a circuit in which circulates a heat transfer fluid which regulates the temperature of a mechanical member by conveying the thermal energy produced by the operation of this member.

On a vehicle of the hybrid type, for example, one can thus find two, three or four control loops which are each dedicated to the cooling of a particular component which has its own requirements in terms of thermal management.

• une boucle de régulation à haute température pour la régulation de la température du moteur thermique,
• une boucle de régulation à basse température pour la régulation de la température des organes électroniques de puissance de la chaine de propulsion électrique,
• une boucle de régulation très basse température pour la régulation de la température de la batterie de propulsion.

By way of example, a vehicle of this type may have:

• a high-temperature regulation loop for regulating the temperature of the heat engine,
• a low-temperature regulation loop for regulating the temperature of the electronic power components of the electric propulsion chain,
• a very low temperature regulation loop for regulating the temperature of the propulsion battery.

For reasons of compactness and cost limitation, certain equipment, such as the degassing box, may be common to several control loops.

Degassing is an important function during which air or gas bubbles that are present in the coolant are purged.

Degassing is an important function because the presence of air bubbles in the coolant has a deleterious effect on the quality of the cooling, and therefore does not allow the engine to operate under optimal conditions, which can lead to non-thermal conditions. Controlled with consequences in terms of reliability or durability of the components and nuisance for the environment.

In practice, it should be noted that the pooling of a degassing box with several cooling loops is not without its problems.

Indeed, the use of a single degassing box for several cooling loops which are at different temperatures, 90/110 ° C for a high temperature loop and 60 ° C and 30 ° C for low or very low temperature loops, has the direct consequence of disturbing the temperature regulation which is carried out in the low temperature regulation loops. In fact, the high temperature regulation loop will make a continuous supply of high temperature liquid in the lower temperature loop (s).

Furthermore, when operating at their respective nominal temperatures, the high temperature control loop has a constant need for degassing because the coolant which is in contact with hot spots of the engine - cylinder head cooling - can occasionally vaporize and therefore generate gas bubbles while the low or very low temperature control loops need degassing when they are started up but do not generate gas bubbles during their operation. In other words, once the temperature has been raised to the nominal operating temperature, a degassing box common to a high-temperature cooling loop and to one or more lower-temperature cooling loops is found. have a deleterious effect on the cooling operation at lower temperature.

We certainly know for example from the document FR 2 949 509 - A1 degassing loop closure devices which, however, are unsuitable for the management of multiple cooling loops and their degassing problem.

The document WO2007 / 031670 A1 discloses the characteristics of the preamble of claim 1.

In this technical context, an aim of the invention is to provide a cooling circuit with several cooling loops pooling the degassing box without compromising the operation of each cooling loop.

To this end, the invention relates to a cooling circuit for a motor vehicle according to claim 1.

The isolation valve can be integrated with a thermostatic box which regulates the temperature of the at least a second cooling loop.

According to one possible embodiment, the thermostatic box comprises a tap in communication with the degassing box.

The thermostatic housing may include a cavity in which are arranged one or more bimetallic elements, the triggering of which causes a shutter such as a ball to pass from a position in which the shutter allows the cooling fluid to pass to a position in which the shutter blocks the passage of coolant.

The isolation valve trigger temperature may be equal to or greater than the nominal operating temperature of the at least one second cooling loop.

According to one possible embodiment, the cooling circuit comprises a first high temperature cooling loop, a second low temperature cooling loop and a third very low temperature cooling loop.

Each cooling loop can comprise at least one element of the group comprising an exchanger, a radiator, a pump, a thermostatic unit.

• Figure 1 montre de façon schématique une forme de réalisation d'un circuit de refroidissement selon l'invention,
• Figures 2 et 3 montrent schématiquement le principe d'une vanne d'isolation,
• Figure 4 montre une forme d'exécution d'un boitier thermostatique selon l'invention.

For its proper understanding, the invention is described with reference to the appended figures in which:

• Figure 1 schematically shows an embodiment of a cooling circuit according to the invention,
• Figures 2 and 3 schematically show the principle of an isolation valve,
• Figure 4 shows an embodiment of a thermostatic box according to the invention.

The invention proposes a cooling circuit 1 for a vehicle comprising several cooling loops. In the example shown in the drawing, the cooling circuit 1 comprises three cooling loops, namely: a high temperature cooling loop I, a low temperature cooling loop II and a very low temperature cooling loop III.

The high temperature cooling loop I comprises a high temperature exchanger 2 formed by the heat engine of the vehicle, a high temperature radiator 3. A pump 4 circulates a cooling fluid of glycol type. We also note the presence of a thermostatic control unit 5 which makes it possible to control the circuit of the cooling fluid as a function of the temperature.

A connection is provided on the thermostatic box 5 to make a connection with a degassing box 6.

The low temperature cooling loop II comprises a low temperature exchanger 20 with, for example, the power electronics (inverter, charger, etc.) of the electric propulsion chain, a low temperature radiator 30. A pump 40 ensures the circulation of the fluid cooling. The low temperature cooling loop II is also provided with a thermostatic control unit 50 which makes it possible to control the cooling fluid circuit as a function of the temperature.

A tap is provided on the thermostatic box 50 to make a connection with the degassing box 6.

Note the presence of an isolation valve 70 controlled in temperature on the return branch which ensures the return of the cooling fluid downstream of the degassing box 6. The function of this isolation valve 70 will be described in more detail. far.

The very low temperature cooling loop III comprises a very low temperature exchanger 200 with, for example, the battery of the electric propulsion chain and a very low temperature radiator. A pump 400 circulates the cooling fluid. The very low temperature cooling loop III is also provided with a thermostatic control unit 500 which makes it possible to control the cooling fluid circuit as a function of the temperature.

A tap is provided on the very low temperature thermostatic box 500 to make a connection with the degassing box 6.

Note the presence of an isolation valve 700 on the return branch which ensures the return of the cooling fluid downstream of the degassing box 6. The function of this isolation valve will be described in detail below.

It can therefore be noted that the cooling device which comprises three cooling loops has a single degassing box 6 which is therefore common to the three degassing loops.

The operation of the cooling device is as follows.

When the vehicle is put into operation, the three cooling loops I, II, III come into action to regulate the temperature of each of the components assigned to them.

Each of the three cooling loops I, II, III presents a need for degassing which is satisfied by the connection of each of the cooling loops to the degassing box 6.

During the rise in temperature towards their respective nominal operating temperatures typically 90 ° C-110 ° C for the high temperature loop I, 55 ° C-65 ° C for the loop the low temperature coolant II and 30 ° C -40 ° C for the very low temperature temperature loop III, the cooling fluid of each of the high cooling loops temperature, low temperature and very low temperature is purged of its gas bubbles which contributes to optimal operation of the vehicle.

When the temperatures of the coolant of the low temperature loop II and of the very low temperature loop III reach their nominal operating values, the temperature controlled isolation valves 70 and 700 go into the closed position because the temperature of tripping of the isolation valve 70 of the low temperature loop II corresponds to the nominal operating temperature of this loop and the tripping temperature of the isolation valve 700 of the very low temperature loop III corresponds to the nominal temperature operation of this loop.

Thus, the degassing box 6 which is unique and which is common to the three cooling loops I, II, III is isolated from the low temperature loop II and from the very low temperature loop III. In this configuration, the degassing box is therefore only linked to the high temperature cooling loop I.

The insulation of the very low temperature loop III with respect to the degassing box 6 is generally done before the isolation of the low temperature loop II with respect to the degassing box 6 because the cooling fluid in the loop has very low temperature III reaches its nominal operating temperature before the coolant in the low temperature loop II reaches its nominal operating temperature.

In nominal operation, the low temperature II and very low temperature III cooling loops do not generate any gas bubbles in their cooling fluid because, unlike the high temperature cooling loop I, no boiling of the liquid occurs. cooling.

In one embodiment (not shown), the control of the isolation valves can be done by solenoid valves controlled by temperature probes.

In another embodiment which is less expensive than the previous one, the control of the isolation valves can be done mechanically by a temperature sensitive element (wax capsule, shape memory material or bimetal).

In practice, the isolation valve 70,700 can be incorporated into the thermostatic box 50,500 as shown in figure 4 .

The thermostatic unit has, in a conventional manner, an inlet and an outlet for the circulation of the fluid to be regulated.

In addition and in a manner specific to the invention, the thermostatic box 50, 500 is then equipped with a flow and a return 51 from the degassing box 6.

The control of the return flow of the water box is effected by a shutter such as a valve or a ball 52 which rests on one or more bimetallic elements 53 as can be seen on the figure. figure 2 . The ball 52 is optionally held against the bimetallic element (s) 53 by a spring. The stack of bimetallic elements 53 and possibly the spring are calibrated for tripping at a tripping temperature which corresponds to the nominal temperature of the cooling loop in question. The valve, the bimetallic elements and the possible return spring are housed in a cavity made in the thermostatic unit.

In other words, the isolation valve 50, 500 is on when the temperature is lower than the nominal operating temperature of the coolant and turns off when the temperature of the coolant reaches a trigger value which corresponds to a temperature determined according to the nominal operating temperature of the low temperature cooling loop II or of the very low temperature loop III.

When the temperature rises, as shown in the figure 2 , the isolation valve allows the cooling fluid to pass back from the degassing box 6 which joins the cooling fluid for the low II or very low temperature III loop.

Indeed, during this phase, the cooling fluid of the low temperature cooling loop II and / or of the very low temperature cooling loop III can be loaded with gas bubbles which should be removed for optimal operation. of the various components of the vehicle.

Taking into account the releases of thermal energy by the various components, for example inverter, battery, etc., the temperature of the coolant has reached its nominal temperature after a variable operating time.

The figure 3 thus shows the isolation valve 50 in a configuration in which the valve blocks the return of the degassing box 6.

The coolant having reached a nominal operating temperature, the ball 52 is pushed against its seat 54 under the action bimetallic elements and blocks the flow coming from the degassing box 6. The cooling fluid is thus used as pilot of the isolation valve.

The valve is reset when the coolant temperature drops.

Another advantage of the bimetallic element arises from the hysteresis of these elements. In fact, the hysteresis of the bimetallic elements is, depending on the mounting and preload conditions, about 20 ° C. If the difference between the nominal cut-out temperatures and the control temperature of the cold coolant is less than 20 ° C, the temperature of the cold coolant can be used as the reset condition.

This may be advantageous in the case of devices operating at low temperature (example less than 40 ° C.), the operation of which may be disturbed by the ambient temperature, which may be higher. Indeed, if the bimetallic elements are no longer irrigated by the “pilot” fluid, an increase in the ambient temperature may prevent the valve from being reset. This may be the case, for example, if the vehicle is parked in the summer in the sun. In addition, the temperature under the hood commonly rises to 80 ° C in current use, in this case during a hot start degassing will not take place, even if the low temperature loop is below its regulation temperature.

Depending on the architecture of the vehicle, the low or very low temperature isolation valve may be integrated into the thermostatic unit or may be an independent element which is placed on the cooling loop.

Of course, the invention is not limited to the embodiments described above by way of nonlimiting example, but it encompasses all the variant embodiments covered by the claims. Thus, the triggering of the isolation valve could be achieved by an element made of heat-sensitive wax or of a shape memory alloy.

Claims (7)

1. A cooling circuit (1) for a motor vehicle comprising a first cooling loop (I) designed to ensure the thermoregulation of a first member and at least one second cooling loop (II, III) designed to ensure the thermoregulation of a second member, the cooling circuit (1) comprising a single degassing case (6) which is fluidly connected to the first loop and to said at least one second cooling loop (II, III) and an isolation valve (70, 700) which is interposed between the degassing case (6) and said at least one second cooling loop (II, III) on a return branch which ensures the return of the coolant downstream of the degassing case (6), characterized in that said isolation valve (70, 700) is designed to selectively seal the flow between the degassing case (6) and said at least one second cooling loop (II, III), the isolation valve (70, 700) comprising at least one heat-sensitive bimetal element designed to act on a shutter to pass the isolation valve (70, 700)) from a passing position to a non-passing position when the coolant passing through the isolation valve reaches a trigger temperature.
2. The cooling circuit (1) according to claim 1, characterized in that the isolation valve (70, 700) is integrated into a thermostatic housing (50, 500) which regulates the temperature of the, at least one, second cooling loop (II, III).
3. The cooling circuit (1) according to claim 2, characterized in that the thermostatic housing comprises a tap (51) in communication with the degassing case (6).
4. The cooling circuit (1) according to claim 3, characterized in that the thermostatic housing (50) comprises a cavity in which one or several bimetal element(s) (53) are disposed whose triggering passes a shutter such as a ball (52) from a position in which the shutter passes the coolant to a position in which the shutter blocks the passage of the coolant.
5. The cooling circuit (1) according to any of claims 1 to 4 in combination with claim 2, characterized in that the trigger temperature of the isolation valve (70, 700) is equal to or greater than the nominal operating temperature of the, at least one, second cooling loop.
6. The cooling circuit (1) according to any of claims 1 to 5, characterized in that the cooling circuit (1) comprises a first high temperature cooling loop (I), a second low temperature cooling loop (II) and a third very low temperature cooling loop (III).
7. The cooling circuit (1) according to any of claims 1 to 6, characterized in that each cooling loop (I, II, III) comprises at least one element of the group comprising an exchanger (2, 20, 200), a radiator (3, 30, 300), a pump (4, 40, 400), a thermostatic housing (5, 50, 500).

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