JP6197459B2 - Engine cooling system - Google Patents

Description

  The present invention relates to an engine cooling system, and more particularly to an engine cooling system capable of improving engine cooling performance and vehicle fuel efficiency.

  When the vehicle is accelerated while climbing up or under a high load capacity, the engine will be in a heavy load state. In order to cool the engine, heat is released into the atmosphere using the vehicle's wind speed from the radiator and the cooling air from the cooling fan. (For example, refer to Patent Document 1). Current vehicles are equipped with many components that absorb the heat energy generated by combustion in the engine with cooling water, such as the EGR system for reducing exhaust gas. The low water temperature sub-radiator for the flow rate radiator and the intercooler is difficult to increase in size due to restrictions on the in-vehicle layout. Therefore, when the engine is under a high load, the engine output is limited by overheat protection (OHP) and the amount of heat generated thereby is limited. Therefore, improvement in engine cooling performance is required.

  In addition, despite the fact that the thermal energy generated in each part of the vehicle is recovered with cooling water, it is in the situation that it is released into the atmosphere as described above, so by effectively using the recovered thermal energy There is also a need to improve the fuel efficiency of vehicles.

JP 2012-188988 A

  An object of the present invention is to provide an engine cooling system capable of improving engine cooling performance and vehicle fuel efficiency.

  An engine cooling system of the present invention that achieves the above object includes a sub-radiator through which cooling water for an intercooler flows, a radiator through which cooling water for an engine main body and cooling water for an EGR cooler, and a cooling fan are connected to the front surface of the vehicle. In the engine cooling system arranged in order, a Rankine cycle in which refrigerant is circulated in order through a refrigerant pump, an evaporator, an expander and a condenser connected to the generator is provided, and one of the cooling water on the inlet side of the radiator is provided. The Rankine cycle is operated to cause the generator to generate electric power by using a part for the heating source of the evaporator and a part of the cooling water for the outlet side of the sub-radiator as a cooling source for the condenser. The cooling water that has passed through the evaporator and the cooling water that has passed through the condenser are merged with the cooling water on the outlet side of the radiator. It is an.

  According to the engine cooling system of the present invention, since the Rankine cycle operated by utilizing the temperature difference between the high-temperature cooling water circulating through the radiator and the low-temperature cooling water circulating through the sub-radiator is installed, And since some cooling water for EGR coolers is cooled by the Rankine cycle whose heat efficiency is higher than air cooling, the cooling performance of an engine improves.

  Further, the heat recovered from the cooling water in the Rankine cycle is converted into electric power to effectively use the heat energy and reduce the load on the cooling fan and the water pump, so that the fuel efficiency of the vehicle can be improved.

1 is a configuration diagram of an engine cooling system according to a first embodiment of the present invention. It is a block diagram of the engine cooling system which consists of a 2nd Embodiment of this invention. It is a flowchart explaining the control content in the 2nd Embodiment of this invention. It is a block diagram of the engine cooling system which consists of the 3rd Embodiment of this invention. It is a flowchart explaining the control content in the 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an engine cooling system according to a first embodiment of the present invention.

  The engine cooling system 1A includes a sub-radiator 2, a radiator 3, and a cooling fan 4 that are arranged in order from the front of the vehicle. The sub-radiator 2 and the radiator 3 cool the cooling water by air cooling using vehicle speed air or cooling air from a cooling fan.

  In the diesel engine 5 to be cooled by the engine cooling system 1A, the air A drawn into the intake passage 6 becomes the intake air 7 and is compressed by the compressor 9 of the turbocharger 8 after passing through an air cleaner (not shown). After being cooled by the water-cooled intercooler 10, it is supplied to the engine body 12 through the intake manifold 11.

  The intercooler cooling water 13 used for cooling in the intercooler 10 is forcibly circulated with the sub-radiator 2 by the water pump 15 while the temperature is adjusted by the intercooler thermostat 14.

  The intake air 7 supplied to the engine body 12 is mixed with fuel and combusted to generate thermal energy, and then becomes combustion gas 16 and is exhausted from the exhaust manifold 17 to the exhaust passage 18. Is diverted as EGR gas 20 to the EGR passage 19 connected to the intake passage 6 on the downstream side of the intercooler 10. In the EGR passage 19, a water-cooled EGR cooler 21 and an EGR valve 22 that adjusts the flow rate of the EGR gas 20 are arranged in this order from the exhaust passage 18 side.

  The engine main body cooling water 23 that cools the engine main body 12 and the EGR cooler cooling water 24 that is used for cooling in the EGR cooler 21 are adjusted in water flow by the thermostat 25 and the water pump 15 between the radiator 3 and the radiator 3. Each is forced to circulate. On the other hand, the cooling water 26 diverted from the thermostat 25 circulates without passing through the radiator 3. Note that a part of the engine main body cooling water 23 is usually used for the EGR cooler cooling water 24.

  The combustion gas 16 that has not been split into the EGR passage 19 is rotated into the turbine 27 of the turbocharger 8 and then discharged into the atmosphere as exhaust gas G.

  In such an engine cooling system 1A, the Rankine cycle 34, in which the refrigerant 33 circulates in order through the refrigerant pump 28, the evaporator 29, the expander 31 (turbine) connected to the generator 30, and the condenser 32, is a sub-radiator. 2 and a radiator 3 provided in parallel with a conventional engine cooling system.

  Specifically, on the heating side of the evaporator 29 in the Rankine cycle 34, a part of the inlet side cooling water 35 (heated engine main body cooling water 23 and EGR cooler cooling water 24 after heating) of the radiator 3 is part of the thermostat 25. The cooling water 36 after passing through the evaporator 29 joins to the outlet side cooling water 37 of the radiator 3 (cooled engine body cooling water 23 and EGR cooler cooling water 24).

  Further, on the cooling side of the condenser 32, a part of the outlet side cooling water 38 (cooling water for intercooler 13 after cooling) of the sub radiator 2 is diverted from the vicinity of the inlet of the intercooler 10 and passes through the condenser 32. The subsequent cooling water 39 joins the outlet side cooling water 37 of the radiator 3.

  The refrigerant 33 circulating in the Rankine cycle 34 is compressed by the refrigerant pump 28, is heated at a constant pressure by the inlet side cooling water 35 of the radiator 3 in the evaporator 29, becomes high-pressure superheated steam, and is adiabatically expanded by the expander 31. After the generator 30 is rotationally driven to generate power, the condenser 32 is cooled at a constant pressure by the outlet side cooling water 38 of the sub-radiator 2 and returns to the liquid.

  As described above, the Rankine cycle 34 that is operated using the temperature difference between the high-temperature cooling water circulating through the radiator 3 and the low-temperature cooling water circulating through the sub-radiator 2 is installed. A part of the cooling water 23 and the cooling water 24 for the EGR cooler is cooled by the Rankine cycle 34 having higher thermal efficiency than the air cooling, so that the cooling performance is improved. Further, the heat recovered from the cooling water in the Rankine cycle 34 is converted into electric power, so that heat energy is effectively used by reducing power generation by the alternator and the load on the cooling fan 4 and the water pump 15 is reduced. Therefore, the fuel consumption of the vehicle can be improved.

  FIG. 2 shows an engine cooling system according to a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part as FIG. 1, and description is abbreviate | omitted.

  In the engine cooling system 1B, the cooling water 36 after passing through the evaporator 29 and the cooling water 39 after passing through the condenser 32 in the Rankine cycle 34 are sent to the outlet side cooling water 37 of the radiator 3 via the electromagnetic valve 40. I try to merge. Further, a water temperature meter 41 for measuring the temperature of the inlet side cooling water 35 of the radiator 3 is installed. The solenoid valve 40 and the water temperature gauge 41 are connected to the ECU 42 as control means through a signal line (indicated by a one-dot chain line) together with the refrigerant pump 28.

  The contents of control by the ECU 42 will be described below with reference to FIG.

  The ECU 42 inputs the measured value of the water temperature gauge 41 (S10), and determines whether the measured value is equal to or higher than the temperature T1 at which the thermostat 25 is opened (S11). The temperature T1 is set in advance according to the specification of the vehicle, and for example, a value of about 80 ° C. is exemplified.

  When the measured value is equal to or higher than the temperature T1, it is determined that the cooling water 35 needs to be cooled, the solenoid valve 40 is opened (S12), and the refrigerant pump 28 is started (S13), thereby Rankine. The operation of the cycle 34 is started (S14).

  By such control, the cooling water 35 can be cooled by the Rankine cycle 34 at an appropriate timing, so that the cooling performance of the engine cooling system 1B can be made efficient.

  On the other hand, when the measured value of the water temperature gauge 41 is lower than the temperature T1, it is determined that the engine body 12 is in the warm-up operation, and the electromagnetic valve 41 is closed until the measured value becomes equal to or higher than the temperature T1. Then, the operation of the Rankine cycle 34 is stopped (S17) by stopping the refrigerant pump 28 (S16).

  By such control, warming-up operation of the engine body 12 is not hindered by the Rankine cycle 34, so that warming-up of the engine body 12 can be completed early.

  FIG. 4 shows an engine cooling system according to a third embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part as FIGS. 1, 2, and description is abbreviate | omitted.

  In the engine cooling system 1 </ b> C, a part of the inlet side cooling water 35 of the radiator 3 is diverted from the downstream side of the thermostat 25 to the heating side of the evaporator 29 in the Rankine cycle 34. In addition, an electromagnetic valve 43 is provided at the outlet of the radiator 3 and is connected to an ECU 42 as control means through a signal line (indicated by a one-dot chain line).

  The contents of control by the ECU 42 will be described below with reference to FIG.

  The ECU 42 inputs the measured value of the water temperature gauge 41 (S20), and determines whether the measured value is equal to or higher than the temperature T1 at which the thermostat 25 is opened (S21). When the measured value is equal to or higher than the temperature T1, the refrigerant pump 28 is activated (S22), and the operation of the Rankine cycle 34 is started (S23).

  On the other hand, when the measured value of the water temperature gauge 41 is lower than the temperature T1, the electromagnetic valve 43 is closed (S24), and the process returns to the start of control.

  Next, it is determined whether the measured value of the water thermometer 41 is equal to or higher than the temperature T2 at which the thermostat 25 is fully opened (S25). The temperature T2 is set in advance according to the specification of the vehicle. For example, a value of about 100 ° C. is exemplified.

  If the measured value is equal to or higher than the temperature T2, the electromagnetic valve 43 is opened (S26), and a part of the cooling water 35 is diverted to the radiator 3 (S27).

  On the other hand, when the measured value of the water temperature gauge 41 is equal to or higher than the temperature T1 and lower than the temperature T2, the electromagnetic valve 43 is closed (S24), and the process returns to the start of control.

  With such control, when the heat load of the engine body 12 is relatively low, the cooling water 35 is cooled only by the Rankine cycle 34 having high thermal efficiency, while the heat load of the engine body 12 becomes relatively high. Since the cooling water 35 is cooled even by air cooling by the radiator 3, the cooling performance of the engine cooling system 1C can be further improved.

1A, 1B, 1C Engine cooling system 2 Sub-radiator 3 Radiator 4 Cooling fan 10 Intercooler 12 Engine main body 13 Intercooler cooling water 21 EGR cooler 23 Engine main body cooling water 24 EGR cooler cooling water 25 Thermostat 28 Refrigerant pump 29 Evaporator 30 Generator 31 Expander 32 Condenser 33 Refrigerant 34 Rankine cycle 35 (radiator) inlet side cooling water 37 (radiator) outlet side cooling water 38 (sub-radiator) outlet side cooling water 40, 43 Electromagnetic valve 41 Water temperature gauge 42 ECU

Claims (3)

In an engine cooling system in which a sub-radiator through which cooling water for an intercooler flows, a radiator through which cooling water for an engine main body and cooling water for an EGR cooler flows, and a cooling fan are arranged in order from the front of the vehicle,
A Rankine cycle in which refrigerant is circulated in order through a refrigerant pump, an evaporator, an expander and a condenser connected to a generator,
The Rankine cycle is operated by using a part of the cooling water on the inlet side of the radiator as a heating source for the evaporator and a part of the cooling water on the outlet side of the sub-radiator as a cooling source for the condenser. While causing the generator to generate electric power,
An engine cooling system characterized in that the cooling water that has passed through the evaporator and the cooling water that has passed through the condenser are merged with the outlet side cooling water of the radiator. A thermostat that adjusts the flow rate of cooling water flowing into the radiator, a water temperature meter that measures the temperature of cooling water that passes through the thermostat, cooling water that passes through the evaporator, and cooling water that passes through the condenser are A solenoid valve that adjusts the flow rate that merges with the outlet side cooling water of the radiator, and a control means;
The control means opens the solenoid valve when the measured value of the water thermometer is equal to or higher than the temperature T1 at which the thermostat is opened, while the measured value of the water thermometer is less than the temperature T1. 2. The engine cooling system according to claim 1, wherein the electromagnetic valve is closed until the measured value becomes equal to or higher than the temperature T <b> 1. A thermostat for adjusting the flow rate of the cooling water flowing into the radiator, a thermometer for measuring the temperature of the cooling water passing through the thermostat, an electromagnetic valve for adjusting the flow rate of the cooling water flowing out from the radiator, and a control means; With
The control means closes the electromagnetic valve when the measured value of the water thermometer is equal to or higher than a temperature T1 at which the thermostat is opened and is lower than a temperature T2 at which the thermostat is fully opened. The engine cooling system according to claim 1, wherein when the measured value of the meter is equal to or higher than the temperature T2, the electromagnetic valve is opened.