EP2112347A1 - Engine cooling circuit - Google Patents

Abstract

The invention relates to a cooling circuit (1) for a motor vehicle engine, comprising: an outlet box (3) for cooling liquid adapted to receive coolant coming from the engine (2); a cooling radiator (7) adapted to receive coolant coming from the outlet housing; a degassing box (18) adapted to receive coolant coming from the radiator; a first valve (5) closing off the flow of coolant between the outlet box and the radiator, the first valve (5) opening when the temperature of the coolant in the outlet box (3) exceeds a first threshold; an opening command of the first valve (5), controlling intermittent openings of the first valve (5) even when the temperature of the coolant in the outlet box (3) is lower than said first threshold.

Description

The invention relates to the cooling circuits of motor vehicle engines, and in particular the structure of coolant outlet housings receiving the heated coolant from the engine and provided with means for measuring a temperature of the liquid located in the engine. The box.

It is known to use valves to completely cut the flow of cooling water to the radiator during the startup phases. Thus, the thermal inertia of the engine is reduced and it reaches as quickly as possible its optimum operating temperature. When the engine reaches a sufficient temperature and exceeds a threshold, the flow of cooling water to the radiator is released.

The document FR 2 903 143 discloses a motor vehicle engine cooling circuit. This circuit comprises a water outlet housing provided with a temperature sensor and a thermostat. The housing comprises an outlet main pipe for transporting water to a radiator whose function is to cool said water, the cooled water being then conveyed by means of a pipe to the inlet of a water pump located upstream of the engine. The pump helps to circulate the cooled water in the engine and the heated water is then recovered in the housing. The housing comprises a first secondary water outlet pipe for supplying a heater with water and whose function is to create heating in the passenger compartment of the motor vehicle. The water recovered at the outlet of the heater is routed to the pump inlet for re-injection into the engine cooling circuit. The circulation of water in this first secondary pipe is controlled by means of a first solenoid valve placed between the housing and the heater. The housing has a second secondary outlet pipe which connects directly to the pipe connecting the radiator to the inlet of the pump, and constituting a bypass portion bypassing the radiator and the heater. Water circulation in the second secondary pipe is controlled by means of a second solenoid valve, more precisely a proportional solenoid valve placed between the housing and the inlet of the pump. This bypass portion directly sends the heated water from the engine to the upstream portion of the cooling circuit positioned before said engine. A 4 mm diameter branch tubing connects the housing part where the temperature sensor is installed to the pump inlet. The tubing has no means of closure and remains permanently open and thus ensures a low flow of water near the probe when the connection to the radiator has been cut. A degassing housing receives coolant through a pipe from the radiator, and another pipe from the outlet housing. The degassing box eliminates bubbles in the coolant. The pipe coming from the outlet housing is in particular a motor protection against breaks in the cylinder head gasket. The water recovered at the outlet of said housing is fed back into the pipe joining the radiator at the inlet of the pump.

Such a cooling circuit has drawbacks. On the one hand, the degassing of the coolant requires several ducts to provide protection in case of rupture of the cylinder head gasket, which further increases the cost and complexity of the cooling circuit. On the other hand, this document does not propose a solution to the cooling of an automatic gearbox, which can reach a critical temperature faster than the engine, particularly in the urban cycle. Solutions envisaged use an additional bypass duct placed upstream of the heater, which increases the cost and complexity of the cooling circuit. In addition, the power supply of the heater during a shutdown of the internal combustion engine is not satisfactory. In addition, known solutions for using the cooling circuit to switch an intake air cooling radiator between a cooling mode and a heating mode are not entirely satisfactory.

The invention aims to solve one or more of these disadvantages. The invention thus relates to a cooling circuit of an engine comprising a coolant outlet housing from the engine; a radiator for cooling the coolant from the outlet housing; a coolant degassing box from the radiator; a first valve for closing off the coolant flow between the outlet housing and the radiator, the first valve opening when the temperature of the coolant in the outlet housing exceeds a first threshold; and an opening command of the first valve, controlling intermittent openings of the first valve even when the temperature of the coolant in the output housing is lower than said first threshold.

According to a variant, no duct directly connects the outlet box to the degassing box.

According to another variant, the circuit includes a diesel engine delivering coolant in the outlet housing.

According to another variant, the circuit further comprises an automatic transmission cooling exchanger equipped with a temperature probe and a pump receiving cooling liquid from the radiator via a conduit in which a circuit withdraws coolant in the conduit, passes through the cooling exchanger and delivers the coolant into the conduit, and wherein the open command controls the opening of the first valve when the temperature measured by the probe temperature exceeds a second threshold.

According to yet another variant, the circuit does not have a bypass between a point upstream of the automatic transmission cooling exchanger and a point of the cooling circuit downstream of the output box.

Alternatively, the circuit includes a coolant temperature probe in the output housing, the opening control controlling the opening of the first valve when the temperature measured by the temperature sensor exceeds the first threshold.

According to another variant, the circuit further comprises a heater adapted to receive cooling liquid from the outlet housing; a second valve closing the flow of coolant between the outlet box and the heater; a pump capable of discharging coolant into the aerator when the internal combustion engine is stopped; and the opening command controlling the opening of the second valve when the internal combustion engine is stopped.

According to another variant, the circuit further comprises a pump driving the cooling liquid into the engine, an output of the heater being connected to this pump; a bypass conduit directly connecting the output box to said pump; and, a third valve closing the coolant flow in the bypass duct, the control selectively controlling the opening of the third valve.

According to another variant, the circuit comprises a secondary radiator; an intake air cooling exchanger, adapted to receive coolant from the engine and to discharge this coolant in the output housing; a pump generating a flow between the intake air exchanger and the secondary radiator in a secondary circuit; the outlet housing being provided with a fourth valve closing the flow of coolant from the intake air cooling exchanger; the command intermittently controlling the stopping of the pump and the opening of the fourth valve.

According to another variant, the output housing further comprises a sliding actuator whose position defines the opening or closing of the first to fourth valves.

The invention also relates to a method for controlling a cooling circuit of an internal combustion engine comprising a valve closing a flow between an outlet housing receiving coolant from the engine and a cooling radiator, the internal combustion engine further comprising a degassing housing adapted to receive coolant from the radiator, comprising the steps of opening the valve when the temperature of the coolant in the outlet housing exceeds a threshold and intermittently opening the valve even when the coolant temperature is below said threshold.

• la figure 1 est une représentation schématique d'un circuit de refroidissement de véhicule automobile ;
• la figure 2 est une représentation schématique du circuit d'eau alimenté par le boîtier de sortie de la figure 1 ;
• la figure 3 représente le circuit d'eau de la figure 2 lors d'une commande de dégazage et de refroidissement d'une boîte de vitesse ;
• la figure 4 représente le circuit d'eau de la figure 2 lors d'une commande d'alimentation de l'aérotherme à l'arrêt du moteur ;
• la figure 5 représente le circuit d'eau de la figure 2 lors d'une commande de réchauffage d'air d'admission.

Other characteristics and advantages of the invention will emerge clearly from the description which is given hereinafter, by way of indication and in no way limitative, with reference to the appended drawings, in which:

• the figure 1 is a schematic representation of a motor vehicle cooling circuit;
• the figure 2 is a schematic representation of the water circuit fed by the output box of the figure 1 ;
• the figure 3 represents the water circuit of the figure 2 during a control of degassing and cooling of a gearbox;
• the figure 4 represents the water circuit of the figure 2 during a power supply control of the heater at the engine stop;
• the figure 5 represents the water circuit of the figure 2 during an intake air heating control.

The invention provides a cooling circuit provided with a coolant outlet housing separated from a cooling radiator by a shut-off valve opening when the coolant temperature in the housing exceeds a threshold. A degassing box receives coolant from the radiator. A valve opening command controls intermittent valve openings even when the temperature of the coolant in the outlet housing is below said threshold.

The invention allows intermittently degassing the coolant in the water box without complicating the cooling circuit, without impairing the warming of the engine. The invention is particularly useful when the engine used is of the diesel type, this type of engine having a slower rise in temperature, and therefore a lower frequency of opening of the valve putting the output box in communication with the radiator.

The figure 1 illustrates a cooling circuit 1 of an internal combustion engine 2. The circuit 1 comprises a casing 3 of coolant outlet. A temperature sensor 4 and a thermostatic valve 5 are arranged in the outlet housing 3. The thermostatic valve 5 selectively releases the flow of liquid between the outlet housing 3 and a radiator 7 above a threshold temperature. The function of the radiator 7 is to cool the coolant, in this case water, flowing in the cooling circuit 1. The thermostatic valve 5 closes one end of a duct 6 joining the outlet housing 3 and the radiator 7. A duct 9 brings the cooling liquid of the radiator 7 to a pump 8. The pump 8 delivers the coolant into the pipes of the engine 2. After passing through these pipes, the coolant is received in the outlet housing 3. A portion of the coolant discharged into these engine lines passes through a water / oil radiator 20. A conduit 19 discharges the coolant from the water / oil radiator 20 into the outlet housing 3.

The cooling circuit 1 further comprises a first secondary pipe 10 connecting the outlet housing 3 to the pump 8. The circuit comprises a peripheral connected in the secondary pipe 10, in this case a heater 11. The cooling circuit 1 comprises a second secondary pipe 13 connecting the outlet housing 3 to the pipe 9 via a valve 14. This secondary pipe 13 allows to directly send water heated from the engine 2 to the pump 8, so that coolant reaches the pump 8 with a lower pressure drop than that generated by the heater 11 in the secondary pipe 10. The solenoid valve 14 is in particular open during the starting phases of the engine 2 to accelerate its speed warming.

A degassing housing 18 is intended to remove bubbles present in the coolant. The housing 18 receives cooling liquid from the radiator 7 via a pipe 17. The degassed cooling liquid is discharged into the pipe 9. According to the invention, an opening command of the valve 5 causes intermittent openings of this valve even when the temperature of the coolant in the outlet housing 3 is below the opening threshold. The intermittent openings of the valve 5 make it possible to degas the coolant from the outlet housing 3 without unduly delaying the heating of the engine 2 and without increasing the complexity of the cooling circuit. Thus, the illustrated cooling circuit has no conduit directly connecting the outlet housing 3 to the degassing housing 18.

The control may control the opening of the valve 5 depending on the ambient temperature, the water temperature and information on the speed or load of the engine. In the starting phase of the engine, if the water temperature is equal to the ambient temperature, the control can open the valve 5 for several seconds. The control can make intermittent openings of the valve 5 with a duty cycle advantageously less than 5%.

In the illustrated example, an automatic gearbox 24 serves as transmission to the engine 2. The gearbox 24 comprises a cooling exchanger 25, typically of water / oil type, as well as a temperature sensor 26. A conduit 22 draws coolant on the line 9 downstream of the radiator 7 and the discharge at the inlet of the exchanger 25. A conduit 23 takes coolant output of the exchanger 25 and discharges it into the pipe 9 downstream of the sewing of the pipe 22 When the valve 5 is open, a cooling water circuit thus feeds the heat exchanger 25. The control opens the valve 5 when the temperature measured by the temperature sensor 26 exceeds a threshold, even when the temperature in the output box 3 is below the opening threshold of the valve 5. Thus, the automatic gearbox 24 can be cooled even during a heating phase of the engine 2, without requiring a complex cooling circuit. In particular, the cooling circuit 1 illustrated does not show a shunt between a point upstream of the cooling exchanger 25 and a point of the cooling circuit downstream of the outlet housing 3. The opening of the valve 5 may also be controlled according to additional information from the gearbox.

The opening of the valve 5 will be electronically controlled. The temperature probe 4 will allow the control to determine when the temperature of the coolant in the outlet housing exceeds the threshold beyond which the engine 2 is to be cooled. The valve 5 will then be open beyond this threshold. The thermostatic valve may of course include a security causing its automatic opening when the coolant reaches a temperature too high. The valve may thus comprise a wax member whose expansion causes it to open.

The outlet housing 3 further comprises a valve closing the flow of the coolant to the heater 11. When the engine 2 is stopped, for example when the vehicle is stopped or when the electric motor is in propulsion mode for a hybrid vehicle, the control can open this valve and close the valve 5, to allow the supply of the heater with coolant that has not been cooled in the radiator 7. Thus, the heating of the passenger can be realized when the engine 2 is stopped. A function of ready conditioning of the passenger compartment in particular to be realized. The flow in the heater 11 may be generated by means of a dedicated pump.

The cooling circuit 1 also comprises an intake air cooling circuit, used, for example, for cooling compressed intake air by a turbine. A pump 27 delivers cooling liquid into a conduit 30 leading to an inlet of an air / water intake air heat exchanger 31. An outlet of the exchanger 31 delivers the cooling liquid to a secondary radiator 21 via a The radiator 21 is typically disposed in the front of the vehicle, close to the radiator 7. An inlet of the exchanger 31 receives coolant from the engine 2. In this case, this inlet receives coolant from the pipe 19. An outlet of the exchanger 31 is connected to the outlet housing 3 via a conduit 29. A valve closes the communication between the exchanger 31 and the housing of 3. Thus, to achieve the cooling of the intake air, this valve will be closed and the pump 27 will be engaged so that the radiator 21 cools the coolant through the exchanger 31. For real episodically a reheating of the intake air, for example for the activation of functions of thermal recovery type exhaust or the regeneration of pollution control organs such as particulate filters or NOx traps, this valve will be open and the pump 27 will be stopped, so that hot coolant will be taken in the pipe 19, through the heat exchanger 31 to heat the intake air, and will be discharged into the outlet housing 3. The order realize the opening of this valve according to information on the need for hot air at the engine inlet, depending on the outside temperature, as a function of the temperature measured by the probe 4 and according to the speed or load of the engine.

The figure 2 schematically represents a coolant outlet box 3 and its valves for supplying different parts of the cooling circuit 1. The valve 34 closes the pipe 10 towards the heater 11. The valve 33 closes the pipe 29 coming from the exchanger 31. The valve 35 closes the pipe 13. The control 32 controls the opening and closing of these valves.

The figure 3 represents the circuit supplied during an intermittent opening of the valve 5. Coolant is discharged through the outlet housing 3 into the radiator 7. Coolant is discharged by the radiator 7 into the degassing housing 18, and in the exchanger 25. The coolant exiting the degassing housing 18 and the exchanger 25 is discharged to the outlet housing 3.

The figure 4 represents the circuit 1 supplied during an opening of the valve 34 when the engine 2 is stopped. Valve 34 is open, while valves 5,33 and 35 are closed. The coolant is discharged through the outlet housing 3 to the heater 11, passes through the motor and is forced into the outlet housing 3.

The figure 5 represents the circuit 1 supplied during a heating of the intake air. The valve 35 is open so that the flow rate discharged by the pump 8 into the engine 2 is increased. Coolant from the engine 2 passes through the exchanger 31. The valve 33 is open, so that the coolant discharged by the exchanger 31 is received by the outlet housing 3.

The outlet housing 3 may comprise a sliding actuator whose position defines the opening or closing of the valves 5, 33, 34 and 35. The valves 5, 33, 34 and 35 may be all or nothing or proportional valves.

Claims (11)

A cooling circuit (1) of an engine comprising an outlet housing (3) of the coolant from the engine (2); a radiator (7) for cooling the coolant from the output housing; a degassing housing (18) of coolant from the radiator; a first valve (5) closing the coolant flow between the outlet box and the radiator, the first valve (5) opening when the coolant temperature in the outlet box (3) exceeds a first threshold characterized in that it further comprises a control (32) for opening the first valve (5), controlling intermittent openings of the first valve (5) even when the temperature of the coolant in the outlet housing (3) is lower than said first threshold. Cooling circuit according to claim 1, wherein no conduit directly connects the outlet housing (3) to the degassing housing (18). Cooling circuit according to claim 2, including a diesel engine delivering coolant to the outlet housing (3). A cooling circuit according to any one of the preceding claims further comprising a cooling exchanger (25) of an automatic transmission (24) provided with a temperature sensor (26); a pump receiving coolant from the radiator (7) via a conduit (9); wherein a circuit (22,23) withdraws cooling liquid in the conduit (9), passes through the cooling exchanger (25) and delivers the coolant into the conduit (23), and wherein the control of opening (32) controls the opening of the first valve (5) when the temperature exceeds a second threshold. A cooling circuit according to claim 4, wherein the circuit (22,23) does not have a bypass between a point upstream of the automatic transmission cooling exchanger and a point of the cooling circuit downstream of the transmission housing. output (3). Cooling circuit according to one of the preceding claims, comprising a temperature sensor (4) of the coolant in the outlet housing (3), the opening control (32) controlling the opening of the first valve (5) when the temperature measured by this temperature sensor (4) exceeds the first threshold. Cooling circuit according to any one of the preceding claims, further comprising a heater (11) adapted to receive coolant from the outlet housing (3); a second valve (34) closing off the coolant flow between the outlet housing (3) and the heater (11); a pump capable of discharging coolant into the aerator when the internal combustion engine is stopped; the opening control (32) controlling the opening of the second valve when the internal combustion engine is stopped. The cooling circuit of claim 7, further comprising a pump (8) delivering coolant to the engine, an output of the heater being connected to that pump; a bypass duct (13) directly connecting the outlet box (3) to said pump (8); a third valve (35) closing the coolant flow in the bypass duct, the control (32) selectively controlling the opening of the third valve. Cooling circuit according to any one of the preceding claims, comprising a secondary radiator (21); an intake air cooling exchanger (31) adapted to receive coolant from the engine (2) and to discharge this coolant into the outlet housing (3); a pump (27) generating a flow between the intake air exchanger (31) and the secondary radiator (21) in a secondary circuit (28, 30); the outlet housing (3) being provided with a fourth valve (33) closing off the flow of coolant from the intake air cooling exchanger (31); the control (32) intermittently controls the stopping of the pump (22) and the opening of the fourth valve (33). Cooling circuit according to claims 1, 7, 8 and 9, wherein the outlet housing (3) comprises a sliding actuator whose position defines the opening or closing of the first to fourth valves. A method of controlling a cooling circuit of an internal combustion engine comprising a valve closing a flow between an outlet housing receiving coolant from the engine and a cooling radiator, the internal combustion engine further comprising a degassing housing adapted to receive coolant from the radiator, comprising the steps of opening the valve when the temperature of the coolant in the outlet housing exceeds a threshold and opening the valve intermittently same when the coolant temperature is below said threshold.

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