EP3555457B1 - Duct for the passage of liquid coolant for an internal combustion engine of a motor vehicle - Google Patents

Description

The present invention relates to the field of cooling circuits for internal combustion engines, in particular for motor vehicles.

Conventionally, a motor vehicle comprising an internal combustion engine is equipped with a cooling circuit intended to regulate the temperature of the engine. The temperature is lowered by the passage of a cooling liquid whose circulation is generated by a pump. The liquid is conventionally called water but most of the time corresponds to a glycol water type coolant.

Motor vehicles equipped with an internal combustion engine are faced with ever-increasing demands aimed at limiting fuel consumption and pollutant emissions. For this purpose, such vehicles generally include an exhaust gas recirculation conduit, also known by the Anglo-Saxon name “Exhaust Gas Recirculation” or by the abbreviation “EGR”. The function of such a conduit is to take exhaust gases at the outlet of the internal combustion engine to reinject them into an intake conduit of the engine. In this way, the recirculation duct makes it possible to limit fuel consumption and pollutant emissions.

However, this solution is not entirely satisfactory. In particular, during a vehicle start-up phase, the internal combustion engine is generally cold, so that the recirculation conduit cannot be opened immediately. Under these conditions, the vehicle consumes more fuel and emits more pollutants.

To overcome this drawback, housings can be used comprising means for heating the coolant of the engine cooling circuit. The box is connected to a first point of the cooling circuit via a first hose and to a second point of the cooling circuit via a second hose. In this way, the coolant circulating in the cooling circuit passes through the first hose, is heated as it passes through the housing, then rejoins the cooling circuit through the second hose. Due to heating of the coolant, exhaust gas recirculation is activated more quickly.

We know of FR2722839-A1 , WO9851927-A1 Or EP1008472-A1 a rigid tubular part for an engine comprising an electric heating means, in particular at least one heating candle.

Although such a solution is generally considered satisfactory, it continues to present certain disadvantages. In particular, the bulk generated by the housing and the two hoses makes it practically impossible to install such a housing in a motor vehicle engine compartment.

In view of the above, the invention aims to provide a cooling circuit component of an internal combustion engine overcoming the aforementioned drawbacks.

More particularly, the invention aims to allow the heating of the coolant while optimizing the heat exchange efficiency caused during heating, in order to limit fuel consumption and emissions of pollutants, and by limiting the size generated within the engine compartment.

For this purpose, there is proposed a coolant passage conduit for an internal combustion engine of a motor vehicle comprising a tubular portion to allow the passage of a coolant from an engine cooling circuit, said tubular portion comprising an upstream end intended to be connected to a first functional member of the engine, and a downstream end opposite the upstream end and intended to be connected to a second functional member of the engine.

According to a general characteristic of this conduit, the tubular portion comprises at least one receiving orifice capable of receiving at least one element for heating the cooling liquid.

Furthermore, the passage conduit comprises a branch intended to be connected to a unit heater of the cooling circuit. Such a branching makes it possible to directly bring the coolant having passed through the air heater to circulate through the second functional member of the engine.

Such a passage conduit makes it possible to heat the coolant while limiting the space generated within the engine compartment. In addition, the coolant is heated near the engine so as to allow the engine to heat up more quickly. This improves the cold starting conditions to enable faster activation of the exhaust gas recirculation. The heated passage duct further provides an additional heat source that helps warm a charge air cooler with anticipation. These effects notably result in better treatment of pollutants and lower fuel consumption.

According to one embodiment, the first functional member of the engine is an oil cooler and/or the second functional member of the engine is an engine cylinder block or a coolant pump.

Arranging the passage conduit fitted with a heating element between the oil cooler and the coolant pump, and in particular just upstream of the coolant pump, makes it possible in particular to circulate the liquid hot cooling in the water pump, which is close to the engine. This further heats the exhaust gases to open the exhaust gas recirculation valve even earlier and further heat the charge air cooler.

Advantageously, the passage conduit consists of a single piece made by molding, preferably in aluminum.

By producing the passage conduit in this manner, the costs of manufacturing the conduit and the costs of integrating the cooling circuit within the internal combustion engine are reduced, and the thermal conductivity of the passage conduit is increased.

According to another embodiment, the passage conduit comprises at least four receiving orifices each capable of receiving a preheating plug.

As will be explained subsequently, the use of four glow plugs is particularly advantageous in that it makes it possible to sufficiently increase the engine load during regeneration of the particle filter. Glow plugs are also known as immersion heaters.

Preferably, said at least four receiving orifices are arranged in a staggered manner.

In an advantageous embodiment, said at least one receiving orifice comprises a cylindrical bore of small diameter extending outwards from an internal wall of the tubular portion, and a cylindrical bore of large diameter extending towards the interior from a wall located outside the tubular portion, the two cylindrical bores being coaxial, the two cylindrical bores being connected by a frustoconical bore whose generators form an angle of between 58° and 66° with the common axial direction of said two cylindrical bores.

Such a design of said at least one receiving orifice allows easy installation of a preheating plug, while maintaining a reinforced seal of the coolant passage conduit.

In a particular embodiment, the passage duct comprises an ear for fixing to a cylinder block of the engine.

Such an ear makes it possible to prevent the transmission of vibrations from the cylinder block to the passage duct.

According to another aspect, an internal combustion engine for a motor vehicle is proposed comprising a cylinder block, a cooling circuit, a first functional member, a second functional member and a coolant passage conduit as defined above.

In one embodiment, the engine comprises a coolant pump delimited by a pump housing, said pump housing being at least partially formed by a portion of the cylinder housing.

Such an embodiment is particularly advantageous in that the coolant heated by said at least one heating element is directly in contact with the cylinder block. As a result, thermal losses are minimized during the transfer of energy from the heated coolant to the internal combustion engine. In this way, by providing a minimum of energy, the temperature rise of the internal combustion engine is further increased so as to further limit fuel consumption and pollutant emissions.

• la figure 1 représente schématiquement un circuit de refroidissement d'un moteur à combustion interne selon un exemple de réalisation de l'invention,
• la figure 2 est une vue isométrique d'un conduit de passage du circuit de refroidissement la figure 1, et
• la figure 3 est une vue en coupe d'un orifice de réception du conduit de passage de la figure 2.

Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

• there figure 1 schematically represents a cooling circuit of an internal combustion engine according to an exemplary embodiment of the invention,
• there figure 2 is an isometric view of a passage duct of the cooling circuit figure 1 , And
• there Figure 3 is a sectional view of a receiving orifice of the passage conduit of the figure 2 .

We represented on the figure 1 an internal combustion engine 2. The engine 2 is intended to be incorporated into a motor vehicle. The engine 2 can be a spark ignition engine or a compression ignition engine. The engine 2 notably comprises at least one cylinder (not shown) inside which combustion takes place. The cylinder is delimited by a cylinder block 4 schematically represented on the figure 1 by the rectangular frame surrounding the combustion engine 2.

The engine 2 is associated with a cooling circuit 6. The function of the cooling circuit 6 is to regulate the temperature of the engine 2.

As will be detailed below, the cooling circuit 6 comprises a plurality of members, some of which cooperate directly with the engine 2. These members are designated in the present application as being functional members of the engine.

The cooling circuit 6 includes a coolant pump 8, also known as a water pump. The function of pump 8 is to activate the circulation of the coolant in circuit 6 passing through engine 2 before cooling the latter. The pump 8 is delimited by a pump casing 10, schematically represented on the figure 1 by the rectangular frame surrounding the pump 8. In a manner known per se, the pump 8 is driven directly by the internal combustion engine 2. The pump 8 is thus a functional member of the engine 2.

As is schematically represented on the figure 1 , the compression chamber of the pump 8 is only partially delimited by the pump casing 10. To delimit the compression chamber of the pump 8, the pump casing 10 is fixed on the cylinder block 4. In addition in other words, the compression chamber of the pump 8 is delimited partially by the pump casing 10 and partially by the cylinder casing 4.

The cooling circuit 6 further comprises an air heater 12. The function of the air heater 12 is to allow heating of the passenger compartment of the motor vehicle while cooling the coolant of the circuit 6.

Circuit 6 further comprises a radiator 14. Radiator 14 is provided to cool the cooling liquid by convection. For this purpose, the radiator 14 can be placed just behind the grille of the motor vehicle, so as to be able to effectively cool the coolant circulating in circuit 6.

The circuit 6 further comprises an oil cooler 16. The oil cooler 16 is used to regulate the temperature of the oil of the engine 2. The cooler 16 is then a member functional of engine 2. Furthermore, the oil cooler 16 is directly fixed on the cylinder block 4 of engine 2.

The cooling circuit 6 comprises a plurality of conduits for passing the coolant between the members 8, 12, 14 and 16. In particular, the circuit 6 comprises a first common conduit 18 connecting a water outlet housing 17 to a bifurcation point (not referenced). At this bifurcation point, the pipe 18 is divided into a first sub-pipe 20 and a second sub-pipe 22. The sub-pipe 20 connects the bifurcation point to the unit heater 12. The sub-pipe 22 connects the bifurcation point at radiator 14.

The water outlet box 17 comprises an inlet opening communicating with the water circuit of a cylinder head 5 and an outlet placed in fluid communication with the first common pipe 18.

The cooling circuit further comprises a second pipe 24 connecting the radiator 14 to the oil cooler 16. The cooling circuit 6 also comprises a third pipe 26 connected to the air heater 12.

The direction of circulation of the coolant in the lines 18 to 26 is schematically represented by the figure 1 by arrows. The water pump 8 is arranged upstream of the engine 2, according to the direction of flow of the coolant in the cooling circuit 6. The pump 8 allows water to flow through the cylinder block 4 and the cylinder head 5 of engine 2. After having circulated through the cylinder head 5 of engine 2, the coolant leaves the cylinder head 5 through the outlet box 17 to which the pipe 18 is connected. In other words, the cooling liquid cooling passing through the air heater 12 leaves the water outlet box 17 via line 18, passes the bifurcation point, takes line 20, crosses the air heater 12 then takes line 26. The cooling liquid passing through the radiator 14 and the cooler 16 leaves the water outlet box 17 via line 18, passes the bifurcation point, takes line 22, crosses the radiator 14, takes line 24 and reaches the cooler 16.

The cooling circuit 6 further comprises a passage conduit 28, schematically represented on the figure 1 and represented in isometric view on the figure 2 . One function of the passage conduit 28 is to connect the oil cooler 16, the coolant pump 8 and the pipe 26 coming from the air heater 12.

In a variant embodiment not shown, the passage conduit 28 allows connection only of the oil cooler 16 to the coolant pump 8, in particular via an interface of the cylinder block 4 intended to receive the coolant pump 8. The cooling circuit then includes another tapping point for line 26.

In reference to the figure 2 , the passage conduit 28 comprises a tubular portion 30. In the illustrated embodiment, the portion 30 is of bent shape to better adapt to the environment of the engine compartment. However, we do not depart from the scope of the invention by considering a different shape of the tubular portion 30. Furthermore, in the example illustrated, the tubular portion 30 has a substantially constant circular section.

The tubular portion 30 comprises a first upstream end 32 and a second downstream end 34. Each end 32, 34 is provided with a stop flange 36 and an annular groove 38.

The upstream end 32 is configured to be able to be directly connected to an outlet (not shown) of the oil cooler 16. More particularly, the end 32 is inserted into a cylindrical opening provided in the oil cooler 16, such so that the flange 36 abuts against a wall of the oil cooler 16. An annular seal can be inserted into the groove 38, so as to provide sufficient sealing of the connection of the passage conduit 28 to the oil cooler 16 .

Likewise, the downstream end 34 is configured to be able to be directly connected to an inlet (not shown) of the cylinder block 4 which can partly define the body of the coolant pump 8. The end 34 is in l species inserted in a cylindrical opening provided the cylinder block 4, the flange 36 abutting against a wall of the pump 8, an annular seal being inserted in the groove 38.

The conduit 28 may also include a branch 40. The branch 40 is stitched directly onto the tubular portion 30 of the passage conduit 28. The branch 40 has an end 42 forming a cylindrical sleeve 44 for connection with the conduit 26. Like the ends 32 and 34, the end 42 includes a stop flange 46.

Thanks to the ends 32, 34 and 42, the passage conduit 28 is directly connected to the oil cooler 16 and to the cylinder block 4, and indirectly connected to the air heater 12 via the conduit 26. By these three connections, the passage conduit 28 is fixed isostatically relative to the cylinder block 4.

In the illustrated embodiment, the passage conduit 28 further comprises a fixing ear 48. Although, in the example illustrated in the figure 2 , the ear 48 extends from the branch 40, the ear 48 can extend from a different portion of the passage conduit 28, for example the tubular portion 30.

The fixing ear 48 is provided to allow fixing of the passage conduit 28 on the cylinder block 4. The fixing ear 48 makes it possible to fix the conduit 28 in a simple manner, for example by means of a screw cooperating with a corresponding threaded bore made in the cylinder block 4. The fixing ear 48 makes it possible to prevent the transmission of vibrations from the cylinder block 4 to the passage conduit 28. However, we do not depart from the scope of the invention in considering a passage conduit 28 devoid of such a fixing ear.

As shown on the figure 2 , the passage conduit 28 further comprises four local protuberances 50 extending from the tubular portion 30. Each protuberance extends substantially radially projecting out of the tubular portion 30. A sectional view of a local protuberance 50 is shown on the Figure 3 . Each protuberance 50 is intended to receive an element for heating the coolant circulating in the passage conduit 28. In this case, the heating means is an electric preheating plug (not shown). In other words, four electric preheating plugs are intended to be respectively mounted in the four local protuberances 50.

In order to efficiently heat the coolant while limiting the space required, we prefer glow plugs powered by electrical power as needed. For example, the electrical power is between 250 W and 350 W for each candle, and even more preferably substantially 300 W each. By using four glow plugs of this type, energy of the order of 1,200 W must be supplied to the plugs to heat the coolant. The presence of an electrical consumer requiring 1,200 W makes it possible to increase the engine load during particle filter regenerations. This results in greater operating efficiency of this filter and therefore a reduction in pollutant emissions.

The four protuberances 50 extend from the tubular portion 30 substantially in the same direction. Each protuberance 50 comprises a front wall 49 opposite the tubular portion 30.

In reference to the Figure 3 , a local protuberance 50 includes a receiving orifice 52 capable of receiving a preheating plug. More particularly, the receiving orifice 52 is through. In other words, the receiving orifice 52 extends from an internal wall 51 of the tubular portion 30, crosses the tubular portion 30 over its entire thickness, crosses the local protuberance 50 and opens outside the portion tubular 30 and the protuberance 50, at the level of the wall 49. The receiving orifice 52 has a generally axisymmetric shape around an axis of cylindricity 53 and is made up of several successive cylindrical and/or frustoconical bores around the axis 53. In the example illustrated, axis 53 coincides with the direction in which the corresponding protrusion 50 extends.

More particularly, the receiving orifice 52 comprises a first cylindrical bore 54 adjacent to the lower wall 51. The axis of cylindricity of the bore 54 coincides with the axis 53. Opposite the interior wall 51, the The bore 54 is extended by a first frustoconical bore 56. The axis of cylindricity of the bore 56 also coincides with the axis 53. The frustoconical bore 56 has the shape of a truncated cylinder whose generators form an angle α relative to axis 53. In the example illustrated, the angle α is between 58° and 66°, preferably between 60° and 64° and even more preferably is substantially equal to 60°.

Opposite the first cylindrical bore 54, the frustoconical bore 56 is extended by a second cylindrical bore 58. The axis of cylindricity of the bore 58 coincides with the axis 53. The bore 58 has a diameter greater than that of the bore 54. In addition, the bore 58 comprises a tapping 59 capable of cooperating with a corresponding thread made on a complementary cylindrical wall of the preheating plug. Opposite the first frustoconical bore 56, the cylindrical bore 58 is extended by a second frustoconical bore 60. The frustoconical bore 60 forms a truncated cylinder whose generators form an angle β with the axis 53. In the example illustrated, the angle β is substantially equal to 45°.

Thanks to this arrangement of the receiving port 52, a glow plug (not shown) can be introduced into the bores 60, 58, 56 and 54. The bore 60 provides an entry chamfer of the port 52 in order to to facilitate the insertion of the glow plug. Preferably, the glow plug has a shoulder of design complementary to that of the frustoconical bore 56. In this way, the shoulder of the glow plug abuts against the frustoconical bore 56. This strengthens the seal supplied at the receiving orifice 52 and the preheating plug with respect to the coolant circulating in the passage conduit 28. In particular, the seal is reinforced thanks to the optimal shape of the bore 56 and the value of the angle α formed by its generators. In addition, thanks to the thread made on the bore 58, the preheating plug is simply and reliably fixed in the receiving orifice 52.

Thus, in the example illustrated, the reception orifices 52 extend between the internal wall 51 of the conduit 28 and the front wall 49 of the protuberances 50. This arrangement is particularly advantageous in that it allows reliable and watertight installation of the glow plugs. However, we do not depart from the scope of the invention by considering different receiving orifices, for example extending between the internal wall 51 and an external wall (not referenced) of the tubular portion 30. In such a variant, the thickness of the tubular portion 30 must be greater if we wish to obtain a reliable and waterproof installation. The embodiment illustrated in the figures, including in particular the orifices 52 partially located in the local protuberances 50, thus makes it possible to save material and limit the size and mass of the passage conduit 28.

Again with reference to the figure 2 , the four local protuberances 50 and the four receiving orifices 52 are arranged approximately staggered relative to each other. Such an arrangement is particularly advantageous because it allows the preheating plugs to be supplied with an electric cable (not shown) allowing the circulation of a power current, limiting the bulk caused by the presence of the electric cable.

Furthermore, the design of the passage conduit 28 in a single piece produced by molding is advantageous in that it facilitates the production of the passage conduit 28, so as to limit costs, in that it reduces the risk of leakage of the cooling circuit and in that it increases the thermal conductivity through the conduit 28. In this way, when the coolant of the circuit 6 is heated during the temperature rise phase of the engine 2, the losses are minimized thermal damage caused during transfer of heat from the cooling liquid to the engine 2. In the example illustrated, this effect is further accentuated by choosing a suitable material to mold the passage conduit 28, that is to say a material with high thermal conductivity such as for example aluminum.

In view of the above, the passage conduit 28 makes it possible to pass the coolant from the cooling circuit 6 in a simple and economical manner, so as to improve the operation of the engine during the temperature rise and regeneration phases. particle filter, while optimizing the energy consumption of electronic components such as glow plugs and limiting the space taken up in the engine compartment.

In particular, the invention makes it possible to implement exhaust gas recirculation earlier, to activate an engine charge air cooler more quickly and to increase the engine load in an optimal manner during particle filter regeneration phases.

Claims (7)

1. Cooling circuit (6) for an engine (2), comprising functional members, with in particular a first functional member of the engine being an oil cooler (16) and a second functional member of the engine being a liquid coolant pump (8), the liquid coolant pump (8) being arranged upstream of the engine (2) in the direction of flow of the liquid coolant in the cooling circuit (6), the cooling circuit comprising in particular a unit heater (12), a radiator (14) and also a plurality of ducts (18, 20, 22, 24, 26) for passage of the liquid coolant between functional members, one of the ducts being a liquid coolant passage duct (28) for a motor vehicle internal combustion engine (2), which connects the oil cooler (16) to the liquid coolant pump (8), the duct (28) comprising a tubular portion (30), said tubular portion (30) having an upstream end (32) intended to be connected to a first functional member of the engine (2), in particular the oil cooler (16), and a downstream end (34) opposite the upstream end (32) and intended to be connected to a second functional member of the engine (2), in particular the liquid coolant pump (8), the tubular portion (30) comprising at least one receiving orifice (52) capable of receiving at least one element for heating the liquid coolant, and said passage duct (28) comprising a branch (40) connected to the duct (26) emanating from the unit heater (12).
2. Cooling circuit (6) according to Claim 1, characterized in that it is formed in one piece produced by casting, preferably being made of aluminium.
3. Cooling circuit (6) according to Claim 1 or 2, wherein the passage duct (28) comprises at least four receiving orifices (52) each capable of receiving a preheating plug.
4. Cooling circuit (6) according to Claim 3, wherein said at least four receiving orifices (52) are arranged in staggered fashion.
5. Cooling circuit (6) according to any one of Claims 1 to 4, wherein said at least one receiving orifice (52) comprises a small-diameter cylindrical bore (54) extending outwardly from an inner wall (51) of the tubular portion (30), and a large-diameter cylindrical bore (58) extending inwardly from a wall (49) situated outside the tubular portion (30), the two cylindrical bores (54, 58) being coaxial, the two cylindrical bores (54, 58) being connected by a frustoconical bore (56) whose generatrices form an angle (α) of between 58° and 66° with the axial direction (53) of said two cylindrical bores (54, 58).
6. Cooling circuit (6) according to any one of Claims 1 to 5, wherein the passage duct (28) comprises a fastening lug (48) for fastening to a crankcase (4) of the engine, the fastening lug extending in particular from the branch (40).
7. Cooling circuit (6) according to any one of the preceding claims, characterized in that the liquid coolant pump (8) is delimited by a pump casing (10), said pump casing (10) being at least partially formed by a portion of a crankcase (4) of the engine (2).

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