FR3050233B1 - COOLING SYSTEM OF A THERMAL ENGINE - Google Patents

Abstract

The invention relates to a cooling system (2) in particular of the double-cooling type, of a motor (1) of a motor vehicle comprising first and second heat transfer fluid circuits (7a, 7b) respectively arranged in a housing of cylinders (6) and a cylinder head housing (5) of said engine (1), the first circuit (7a) being provided with first and second fluid flow control elements (15a, 15b) respectively arranged at a input (10a) and an output (10b) of said first circuit (7a).

Description

COOLING SYSTEM OF A THERMAL ENGINE

The present invention relates to a cooling system of a heat engine and a method of operating such a system. The invention also relates to a heat engine comprising such a cooling system and a vehicle including a motor vehicle comprising such a motor.

In the state of the art, a heat engine usually comprises a cylinder block closed by a cylinder head cover. For proper operation of the engine, these housings must be cooled. To do this, the engine is provided with a cooling system in which a coolant is circulated by means of a feed pump and which, in turn, is cooled through a radiator.

However, the operating temperature of an engine is normally much higher than the outside temperature, especially in cold weather. Any startup of the latter is therefore accompanied by a preheating phase during which the performance is not optimal, especially during which the emissions of pollutants of carbon monoxide and unburnt hydrocarbons are much larger than nominal .

To reduce this preheating time, with reference to FIG. 1, in the state of the art, a motor 100 is known which is provided with a so-called double cooling cooling system 101, otherwise known as "split-shear". cooling ", wherein the heat transfer fluid flows independently in first and second fluid circuits 104a, 104b respectively of the cylinder housing 103a and the cylinder head housing 103b, the circulation in the first fluid circuit 104a being established that once the preheating phase is completed from an activation of a valve 108 arranged at the output of this first circuit 104a.

Such a system 101 makes it possible to minimize the heating time of the engine 100 or of a part thereof, by accelerating the rise in temperature of the coolant at the start of the vehicle, in order to reduce piston friction. and segments in engine drums 100, fuel consumption and pollutant emissions.

However, one of the disadvantages of such a cooling system 101 is related to a double cooling operation which is not optimal. Indeed, the engine 100 generally comprises a cylinder head gasket 105 provided with orifices for the circulation of heat transfer fluid between the first and second circuits 104a, 104b and this, in order to facilitate degassing mechanisms in this system. The presence of such holes in the cylinder head gasket 105 then impedes the proper functioning and effectiveness of the double cooling, since a residual parasitic flow rate 106a of heat transfer fluid is present between these two circuits 104a, 104b.

In this configuration, the passage of the heat transfer fluid from the first circuit 104a to the second circuit 104b through these orifices results from a pressure difference of the fluid in the first and second circuits 104a, 104b, and to a thermosiphon effect between the circuits 104a and 104b, because the fluids in these two circuits are at different temperatures. Indeed, the pressure of the fluid in the first circuit 104a is greater than the pressure of this fluid in the second circuit 104b due to the introduction of fluid by the feed pump 107 at the inlet of this first circuit 104a and the presence of the valve 108 which is closed at the output of this first circuit 104a. With reference to FIG. 3, the parasitic flow rate 106a has the consequence that a temperature T2 of the fluid in the first circuit 104a evolves more rapidly than a temperature T3 of the fluid in the same circuit of a system in which there is no There is no double cooling and more slowly than a temperature T1 of the fluid in a first circuit of a double cooling system in which such a parasitic flow rate 106a is non-existent. Therefore, the first circuit 104a defined in the cylinder housing 103a therefore no longer operates completely in "zero flow", which reduces the temperature T2 of the cylinder block at the expense of fuel consumption and pollutant emissions.

To overcome this drawback, the prior art discloses a cooling system 100 illustrated in FIG. 2, in which the first circuit 104a defined in the cylinder casing 103a comprises a valve 108 arranged at the inlet of this first circuit 104a and this, after the feed pump 107 of this system 101.

However, such an arrangement of this valve 108 at the entrance of the first circuit 104a does not completely eliminate the parasitic flow 106a. In addition, this arrangement also generates a parasitic circulation 106b of coolant fluid loop between these two circuits 104a, 104b in a direction illustrated by the arrow F shown in Figure 2, thus not allowing the cooling system to perform a functioning according to a double cooling that is fully effective.

The present invention aims to overcome these disadvantages related to the state of the art.

With this aim, the invention relates to a cooling system, in particular of the double-cooling type, of a combustion engine of a motor vehicle comprising first and second heat transfer fluid circuits respectively arranged in a cylinder block and a crankcase. the cylinder head of said engine, the first circuit being provided with first and second fluid flow control elements respectively arranged at an input and an output of said first circuit.

In other embodiments: the first regulating element is defined to allow / prohibit a circulation of the coolant at the inlet of the first circuit as a function of a temperature of said fluid present in said first circuit of said housing; cylinders; - The second regulating element is defined to allow a circulation of the heat transfer fluid at an output of the first circuit in a single direction of circulation of said fluid from a first connection zone to a second connection zone of said system; the first regulating element is a thermostat or a pilot valve; the second regulating element is a non-return valve, a pilot valve or a thermostat; the first connection zone connects inputs of the first and second circuits together, and the second connection zone connects outputs of the first and second circuits to each other. The invention also relates to a method of operating a cooling system of a thermal engine of a motor vehicle comprising first and second heat transfer fluid circuits respectively arranged in a cylinder head housing and a crankcase of said engine, the method comprising a step of controlling the flow of the coolant in the first circuit from first and second fluid flow control elements.

Advantageously, the control step comprises the following substeps: - prohibition of circulation of the heat transfer fluid in the first circuit by the first and / or the second fluid flow control element when a measured temperature of the fluid present in the first circuit of the cylinder block is substantially lower than a reference temperature, and - authorization of circulation of the coolant in the first circuit by the first and second fluid flow control elements when a measured temperature of the fluid present in the first Cylinder housing circuit is substantially greater than or equal to the reference temperature. The invention also relates to a heat engine comprising such a cooling system. The invention also relates to a motor vehicle comprising this heat engine. Other advantages and features of the invention will appear better on reading the description of a preferred embodiment which will follow, with reference to the figures, made by way of indicative and nonlimiting example: FIG. a view of a cooling system according to the state of the art; - Figure 2 shows a view of another cooling system according to the state of the art; FIG. 3 shows temperature versus time curves relating to a fluid present in a circuit defined in a cylinder casing for several configurations of the cooling system of the state of the art; FIG. 4 represents a schematic view of a cooling system according to the embodiment of the invention, and FIG. 5 is a view of a logic diagram relating to a method of operating the system according to the embodiment of the invention. 'invention.

Figure 4 is a schematic representation of a cooling system 2 of a heat engine 1 of a motor vehicle. This engine 1 may be a gasoline engine or a diesel engine including supercharged or an engine operating according to a technology called "Flex Fuel" and whose fuel system and carburetion allows it to use indifferently fuels as varied as the gasoline, bioethanol or a mixture of both. For example, in the present embodiment, the cooling system 2 is implemented in a diesel engine 1 comprising a main circuit 3 provided with components of the engine 1 such as a degassing jar 18, a supercharging module engine 1 comprising a turbocharger 20, a heat exchanger 21 such as a heater or a motor oil exchanger 19 better known by the acronym "EMO" for evacuating heat generated at the oil sump engine.

Such a motor 1 comprises a cylinder casing 6 provided with a plurality of cylinders can be arranged in line. Above the cylinder block 6, along an axis substantially parallel to the vertical axis of the cylinders, is fixed a second housing, said cylinder head cover 5. This cylinder head cover 5 comprises a lower face which is intended to be fixed on an upper face of this cylinder casing 6, which being disposed below this cylinder head housing 5. This cylinder head housing 5 contains in particular the distribution composed mainly of valves and camshafts. This engine 1 also comprises a cylinder head gasket 16 placed between the cylinder head housing 5 and the cylinder casing 6 and in particular between the above-mentioned upper and lower faces.

This cooling system 2 may be of the double cooling type, often known as the Anglo-Saxon "split-cooling" mode and in which the coolant circulates independently in a first circuit 7a defined in the cylinder casing 6 and a second circuit 7b included in the cylinder head housing 5, the circulation in the first circuit 7a being established only once a preheating phase of the cylinder block 6 is completed.

The main circuit 3 of this cooling system 2 comprises an internal cooling circuit 4 inside the engine 1 which is provided with: a feed pump 9, first and second circuits 7a, 7b of fluid as well as first and second connection areas 8a, 8b.

The feed pump 9 is intended to circulate the heat transfer fluid still called cooling fluid in the internal cooling circuit 4 of the engine 1. As we have seen, the first and second circuits 7a, 7b are respectively included in the cylinder block 6 and the cylinder head housing 5. These first and second circuits 7a, 7b, otherwise called the core or fluid chamber, each comprise a hollow space or a recess consisting of circulation channels which is defined in the cylinder block 6 or the cylinder head 5 of the engine 1 and in which is intended to circulate the cooling fluid, here water or ethylene glycol with or without adjuvants.

The first circuit 7a is substantially isolated from the second fluid circuit 7b, so the cylinder block 6 and the cylinder head housing 5 are cooled separately with a heat transfer fluid which circulates independently in these first and second circuits 7a, 7b . As mentioned above, the engine 1 comprises a cylinder head gasket 16 arranged between the cylinder block 6 and the cylinder head housing 5. This cylinder head gasket 16 may comprise orifices made only in a part 14 of this gasket. 16, for circulation of the coolant between the first and second circuits 7a, 7b. Such a cylinder head gasket 16 provided with these orifices contributes to degassing the first circuit 7a defined in the cylinder casing 6. In effect, gas bubbles formed in the first circuit 7a must be able to pass from this first circuit 7a towards the second circuit 7b to be discharged out of the internal circuit 4, to the degassing jar 18. Such degassing can take place immediately after the filling of the cooling system 2 in heat transfer fluid, but also during operation of the engine 1 by the creation of bubbles of gas in the coolant under the effect of the thermal generated by the combustion in the first circuit 7a.

These first and second circuits 7a, 7b each comprise an inlet 10a, 11a through which the coolant is introduced in the flow direction F1 in said circuit and an outlet 10b, 11b through which this fluid is discharged in the direction of circulation F3 . The inputs 10a, 11a of these first and second circuits 7a, 7b are interconnected in the first connection zone 8a of the internal cooling circuit 4. Similarly, the outputs 10b, 11b of these two circuits 7a, 7b are also interconnected in the second connection zone 8b of this internal cooling circuit 4.

The first connection zone 8a is also connected to a fluid inlet duct 12a of the internal circuit 4 connected in particular to an output of a radiator 17 but also to component outputs of the motor 1 mentioned above. This inlet duct 12a comprises the supply pump 9 provided with an outlet connected directly to the first connection zone 8a. Thus, the feed pump 9 contributes to circulating the heat transfer fluid that it receives in particular from this radiator 17 and / or the components of the engine 1, in the first and second circuits 7a, 7b via this first zone. connection 8a. The second connection zone 8b is connected to a fluid discharge conduit 12b of the internal circuit 4. This exhaust duct 12b is in particular connected to the inputs of the radiator 17 and the other components of the engine 1 so that the Heat transfer fluid is transmitted to them according to the activation / deactivation of valves 19 and / or thermostats 19 arranged in the main cooling circuit 3.

This radiator 17 included in the main circuit 3 constitutes a heat exchanger for cooling the coolant at the outlet of the internal circuit 4 at the exhaust duct 12b. The radiator 17 is then able to return the cooled heat transfer fluid to the internal circuit 4 via the inlet conduit 12a provided with the feed pump 9.

The first circuit 7a of the internal circuit 4 comprises first and second regulating elements 15a, 15b of the flow of the fluid. These first and second regulating elements 15a, 15b are respectively arranged at the input 10a and the output 10b of said first circuit 7a. Moreover, these regulation elements 15a, 15b are located between the first and second connection zones. 8a, 8b. More precisely, these first and second regulating elements 15a, 15b are located in close proximity to these first and second connection zones 8a, 8b, respectively.

In this configuration, the first regulation element 15a is defined to allow / prohibit a circulation of the coolant at the inlet 10a of the first circuit 7a as a function of a temperature Tm of said fluid present in the first circuit 7a of said housing. cylinders 6. This first regulating element 15a may be a thermostat provided with a temperature sensor immersed in the heat transfer fluid present in this first circuit 7a or watered by this fluid. It may be a temperature sensor included in the body of the thermostat or a remote sensor arranged in this first circuit 7a. This thermostat may for example be a wax thermostat comprising two flaps arranged at both ends of a wax bulb and whose operation is well known in the state of the art. In a variant, this first regulation element 15a may be a valve controlled for example by a cooling system processing unit 2 which is connected to a temperature sensor located in the first circuit 7a.

The second regulating element 15b is defined to allow a circulation of the coolant at the outlet 10b of the first circuit 7a in a single flow direction F2 of said fluid from the first connection zone 8a to the second connection zone 8b of said system 2 or from the input 10a to the output 10b of this first circuit 7a. This second regulating element 15b may be a non-return valve. Several types of check valve known from the state of the art can be implemented in this first circuit 7a. For example, such a non-return valve may comprise a hollow cylindrical body enclosing a movable member which here takes the form of a ball, and a spring which constantly urges the ball against a seat. The spring is able to compress under the action of a compressive force exerted by the heat transfer fluid flow on the ball so that the latter moves from an initial rest position where the output 10b of the first circuit 7a is closed. at a position where this output 10b is open and the fluid can then be removed from the first circuit 7a. As soon as the fluid no longer exerts such a force, the ball returns to its rest position under the action of a restoring force of the spring.

In a variant, the second regulating element 15b may be a thermostat that may have the same characteristics as the thermostat described for the first regulation element 15b. In another variant, this second element 15b may be a valve controlled for example by the cooling system processing unit 2 which is connected to a temperature sensor located in the first circuit 7a and / or the first regulation element 15a . Thus, the second regulating element 15b can then be connected synchronously with the first regulating element 15a so as to allow / prohibit the circulation of the heat transfer fluid at the outlet 10b of the first circuit 7a substantially simultaneously with said first regulating element 15a.

With reference to FIG. 5, the invention also relates to a method of operating the cooling system 2. This method comprises a step of starting the engine 1.

Subsequently, this method provides a step 22 for circulating the heat transfer fluid in the internal circuit 4. During this step 22, the supply pump 9 whose output is connected to the first connection zone 8a is then capable of to supply the fluid supply of the first and second circuits 7a, 7b.

The method then comprises a step 23 for controlling the flow rate of the coolant in the first circuit 7a from the first and second fluid flow regulating elements 15a, 15b. Such a step 23 allows to implement a preheating process of the engine 1 to improve the performance of the latter and thus reduce pollutant emissions and fuel consumption. To do this, this step 23 comprises a sub-step of prohibiting the circulation of the coolant in the first circuit 7a by the first and / or the second fluid flow regulating element 15a, 15b when a measured temperature Tm fluid present in the first circuit 7a of the cylinder housing 6 is substantially lower than a reference temperature Tf. This reference temperature Tf is defined according to the characteristics of the engine 1 and preferably corresponds to a preheating end temperature of the cylinder casing 6.

During this substep 24, the natural movement of the heat transfer fluid to make a residual parasitic circulation loop is then eliminated due to the arrangement of the first and second regulating elements 15a, 15b respectively at the entrance and the output of this first circuit 7a. More specifically, this arrangement of these regulating elements 15a, 15b limits or eliminates the effects that may result from the fluid pressure difference in the first and second circuits 7a, 7b and / or the difference in fluid temperature in the latter. is likely to be at the origin of a phenomenon called "thermosiphon". Under these conditions, the heat transfer fluid flow rate in the first circuit 7a is then zero. In addition, the feed pump 9 supplies only the second circuit 7b which is defined in the breech housing 5.

This step 23 also comprises a sub-step 25 of authorization of circulation of the coolant in the first circuit 7a by the first and second fluid flow control elements 15a, 15b when a measured temperature Tm of the fluid present in the first circuit 7a of the cylinder casing 6 is substantially greater than or equal to the reference temperature Tf. Under these conditions, the heat transfer fluid circulated by the feed pump 9 flows in both the first and second circuits 7a, 7b. This heat transfer fluid travels in particular the first circuit 7a through the first and second regulating elements 15a, 15b until being discharged from the internal circuit 4 after passing through the second connection zone 8b.

Thus, the invention accelerates the rise in temperature of the cylinder block 6 and helps reduce vehicle consumption and pollutant emissions.

Claims (5)

Cooling system (2) in particular of the double cooling type, of a motor (1) of a motor vehicle comprising first and second heat transfer fluid circuits (7a, 7b) respectively arranged in a cylinder block ( 6) and a cylinder head housing (5) of said engine (1), the first circuit (7a) being provided with first and second fluid flow control elements (15a, 15b) respectively arranged at an inlet (10a). ) and an output (10b) of said first circuit (7a), the first regulating element (15a) being defined to allow / prohibit circulation of the coolant at the inlet (10a) of the first circuit (7a) as a function of a temperature (Tm) of said fluid present in said first circuit (7a) of said cylinder casing (6), and / or the second regulating element (15b) being defined to allow circulation of the coolant at the level of the exit (10b) of the first cir fired (7a) in a single direction (F2) for circulating said fluid from a first connection zone (8a) to a second connection zone (8b) of said system (2). 2. System (2) according to the preceding claim, characterized in that the first control element (15a) is a thermostat or a pilot valve. 3. System (2) according to any one of the preceding claims, characterized in that the second control element (15b) is a non-return valve, a controlled valve or a thermostat. 4. System (2) according to any one of the preceding claims, characterized in that: - a first connection zone (8a) connects inputs (10a, 11a) of the first and second circuits (7a, 7b) between them, and / or - a second connection zone (8b) connects outputs (10b, 11b) of the first and second circuits (7a, 7b) to each other. 5. A method of operating a cooling system (2) of a thermal engine (1) of a motor vehicle according to any one of the preceding claims, comprising first and second circuits (7a, 7b) of heat transfer fluid respectively arranged in a cylinder head housing (5) and a cylinder block (6) of said engine (1), the method comprising a step (23) of controlling the flow of the coolant in the first circuit (7a) from the first and second regulating elements (15a, 15b) of the fluid flow. 6. Method according to the preceding claim, characterized in that the control step (23) comprises the following substeps: - prohibition (24) circulation of the heat transfer fluid in the first circuit (7a) by the first and / or the second fluid flow regulating element (15a, 15b) when a measured temperature (Tm) of the fluid present in the first circuit (7a) of the cylinder housing (6) is substantially lower than a reference temperature (Tf) and - authorization (25) for circulation of the coolant in the first circuit (7a) by the first and second fluid flow control elements (15a, 15b) when a measured temperature (Tm) of the fluid present in the first fluid circuit (7a) of the cylinder block (6) is substantially greater than or equal to the reference temperature (Tf). 7. Heat engine (1) comprising a cooling system (2) according to any one of claims 1 to 4. 8. Motor vehicle comprising a heat engine (1) according to the preceding claim.