JP2019132197A - Control device of engine cooling system - Google Patents

Abstract

To provide a control device of an engine cooling system which enables a temperature of a refrigerant such as cooling water to be properly changed.SOLUTION: Cooling water circulates between an engine 11 and a radiator 23 when a water pump 22 is operated. The engine 11 is cooled by heat exchange between the engine 11 and the cooling water, and the cooling water is cooled by heat exchange between the radiator 23 and the cooling water. Normally, a temperature of the cooling water is set at a second temperature T2, and the setting is changed from the second temperature according to an operation state of the engine 11. At the low rotation and light loading of the engine 11, the setting of the temperature of the cooling water is raised from the second temperature T2 to a third temperature T3 which is higher than the second temperature, and a flow rate of the cooling water by the water pump 22 is controlled so that the temperature of the cooling water approximates the third temperature T3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine cooling system control apparatus for cooling an engine.

  A vehicle equipped with an engine is provided with an engine cooling system for cooling the engine.

  In the engine cooling system, the cooling water flows through the engine by the operation of the water pump. As the cooling water flows through the engine, heat exchange is performed between the cooling water and the engine, thereby cooling the engine. The cooling water that has passed through the engine flows toward the radiator.

  Part of the cooling water from the engine to the radiator flows through the heater core for air conditioning in the passenger compartment, and merges with the cooling water flowing from the radiator to the water pump by the thermostat valve. The thermostat valve blocks the flow of the cooling water from the radiator to the water pump when the temperature of the cooling water is equal to or lower than a predetermined temperature. Thereby, when the temperature of the cooling water is equal to or lower than the predetermined temperature, the cooling water circulates between the engine and the heater core without passing through the radiator.

  When the temperature of the cooling water exceeds a predetermined temperature, the cooling water flows through the radiator by switching the thermostat valve. While the vehicle is traveling, the traveling wind passes between the fins of the radiator, and the cooling water flowing through the radiator is cooled by the traveling wind. A radiator fan that sends air to the radiator is provided opposite to the radiator. Since there is no running wind while the vehicle is stopped, the radiator fan is driven as necessary, the air blown from the radiator fan passes between the fins of the radiator, and the cooling water flowing through the radiator is cooled by the air blow. Thereby, the water temperature of the cooling water after passing through the engine is kept at a constant water temperature (for example, about 90 ° C.).

Japanese Patent Laid-Open No. 10-238345

  Thus, in the conventional engine cooling system, control for keeping the coolant temperature constant after passing through the engine is performed, and control for actively changing the coolant temperature is not performed.

  The objective of this invention is providing the control apparatus of an engine cooling system which can change the temperature of refrigerant | coolants, such as cooling water, appropriately.

  In order to achieve the above object, a control device for an engine cooling system according to the present invention is used in an engine cooling system for cooling an engine by circulating a refrigerant between an engine and a radiator by operation of a water pump. In order to change the setting of the refrigerant temperature between the normal temperature and the temperature after the change by the setting changing means, the setting changing means for changing the setting of the refrigerant temperature from the normal temperature according to the operating state of the engine And a flow rate control means for controlling the flow rate of the refrigerant by the water pump.

  According to this configuration, when the water pump operates, the refrigerant circulates between the engine and the radiator. The engine is cooled by heat exchange between the engine and the refrigerant, and the refrigerant is cooled by heat exchange between the radiator and the refrigerant. Usually, the temperature of the refrigerant is set to the normal temperature, and the setting is changed from the normal temperature according to the operating state of the engine. When the setting of the refrigerant temperature is changed, the refrigerant flow rate by the water pump is controlled in order to change the refrigerant temperature between the normal temperature and the changed temperature.

  For example, when the engine is running at low speed and light load, the coolant temperature is raised from the normal temperature to a high temperature, and the coolant flow rate is controlled by the water pump so that the coolant temperature approaches that temperature. By reducing the amount of heat that escapes to the engine coolant when rising, that is, by reducing heat loss, the heat generated by combustion can be used effectively. As a result, it is possible to improve the thermal efficiency at low engine speed and light load.

  According to the present invention, the temperature of a coolant such as cooling water can be changed appropriately.

It is a figure showing the composition of the engine cooling system of vehicles concerning one embodiment of the present invention, and shows the flow of cooling water in the state where the temperature of cooling water is low. It is a figure showing the composition of an engine cooling system schematically, and shows the flow of cooling water in the state where the temperature of cooling water is high. It is a block diagram which shows the structure (electrical structure) of the control system of a vehicle. It is a figure which shows the threshold curve used for the temperature setting of a fuel consumption rate contour of an engine, a torque characteristic line, and cooling water.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Engine cooling system configuration>
1 and 2 are diagrams schematically showing the configuration of an engine cooling system 21 of a vehicle 1 according to an embodiment of the present invention.

  The vehicle 1 is an automobile equipped with an engine 11 as a drive source. The engine 11 is, for example, a gasoline engine or a diesel engine.

  The engine 11 employs an EGR (Exhaust Gas Recirculation) system. The EGR system is a system that recirculates a part of exhaust gas discharged from the engine 11 to the engine 11. The EGR system includes an EGR passage for flowing exhaust gas and an EGR valve for adjusting the flow rate of the exhaust gas flowing through the EGR passage. Further, the EGR system includes an EGR cooler 12 for cooling the exhaust gas flowing through the EGR passage.

  An electronic control throttle 13 is provided along with the engine 11. When the engine 11 is a gasoline engine, the electronic control throttle 13 is provided to adjust the amount of intake air into the combustion chamber of the engine 11. When the engine 11 is a diesel engine, the electronic control throttle 13 is provided to adjust the flow rate of the exhaust gas recirculated to the engine 11 in cooperation with the EGR valve.

  The vehicle 1 employs a belt-type CVT (Continuously Variable Transmission) 14 as a transmission. The CVT 14 is housed in the case together with the differential gear to constitute a transaxle. The transaxle is provided with an oil cooler (O / C) 15 for cooling the oil used in the transaxle. The power of the engine 11 is transmitted to the differential gear via the CVT 14, and is distributed and transmitted from the differential gear to the left and right drive wheels.

  The vehicle 1 is provided with an engine cooling system 21 that cools the engine 11.

  The engine cooling system 21 includes a water pump (W / P) 22 and a radiator 23. The water pump 22 is an electric water pump. The radiator 23 has a radiator inlet 24 and a radiator outlet 25. A plurality of in-radiator flow paths are formed in the radiator 23, and the radiator inlet 24 and the radiator outlet 25 communicate with each other through the plurality of in-radiator flow paths.

  The engine 11 is formed with a water jacket (WJ) that is a flow path through which cooling water flows. The water jacket has a WJ inlet 26 at one end and a WJ outlet 27 at the other end.

  One end of a low-temperature channel 28 is connected to the WJ inlet 26. The other end of the low-temperature flow path 28 is connected to the radiator outlet 25. A first thermostat valve 29 is interposed in the middle of the low temperature flow path 28. The water pump 22 is in the middle of the low-temperature channel 28 and is interposed between the WJ inlet 26 of the engine 11 and the first thermostat valve 29.

  One end of the high temperature channel 31 is connected to the WJ outlet 27. An end portion on one end side of the first branch path 32 is branched and connected to the middle portion of the high-temperature channel 31. The first branch passage 32 passes through the EGR cooler 12 and the electronic control throttle 13 in this order from the high temperature passage 31 side. The other end of the first branch path 32 is connected to the first thermostat valve 29.

  In addition, an end portion of one end side of the second branch path 33 is branched and connected to a middle portion of the high temperature flow path 31 between the connection portion of the first branch path 32 and the radiator inlet 24 of the radiator 23. Yes. The other end of the second branch path 33 is connected to the second thermostat valve 34.

  Each end of the third branch path 35 and the fourth branch path 36 is further connected to the second thermostat valve 34. The third branch path 35 passes through a heater core 37 of an air conditioner that air-conditions the vehicle interior. The other end of the third branch path 35 is an intermediate part of the first branch path 32 and is branched and connected between the electronic control throttle 13 and the first thermostat valve 29. The fourth branch path 36 passes through the oil cooler 15. The end portion on the other end side of the fourth branch path 36 is an intermediate portion of the first branch path 32 and is branched and connected between the electronic control throttle 13 and the first thermostat valve 29.

  When the water pump 22 is driven, the cooling water flows into the water jacket of the engine 11 from the low temperature flow path 28 through the WJ inlet 26, and the cooling water flowing through the water jacket flows out from the WJ outlet 27 to the high temperature flow path 31. To do. When the cooling water flows through the water jacket, heat exchange is performed between the cooling water and the engine 11, the engine 11 is cooled, and the cooling water is heated.

  A part of the cooling water flowing through the high temperature channel 31 is diverted from the high temperature channel 31 to the first branch path 32. The cooling water flowing through the first branch path 32 passes through the EGR cooler 12 and the electronic control throttle 13 in this order, and then flows into the low temperature flow path 28 via the first thermostat valve 29, and the low temperature flow path 28 passes through the water pump 22. It flows toward. When the cooling water passes through the EGR cooler 12, heat exchange is performed between the cooling water and the EGR cooler 12 (exhaust gas flowing through the EGR passage), the EGR cooler 12 is cooled, and the cooling water is heated. Further, when the cooling water passes through the electronic control throttle 13, the electronic control throttle 13 receives heat from the cooling water, and the electronic control throttle 13 is heated.

  When the temperature (water temperature) of the cooling water flowing out from the WJ outlet 27 of the engine 11 is equal to or lower than a predetermined first thermoset temperature, the radiator of the first thermostat valve 29 and the low-temperature flow path 28 is operated by the function of the first thermostat valve 29. 23 side is cut off. Therefore, as shown by the white arrow in FIG. 1, the cooling water flowing out from the WJ outlet 27 of the engine 11 to the high-temperature flow path 31 does not flow through the radiator 23, and enters the first branch path 32 and the second branch path 33. Divide and flow.

  When the temperature of the cooling water is equal to or lower than a predetermined second thermoset temperature, the function of the second thermostat valve 34 blocks the second thermostat valve 34 and the fourth branch path 36. Therefore, the cooling water flowing through the second branch path 33 flows from the second thermostat valve 34 into the third branch path 35, and flows through the third branch path 35 toward the first branch path 32. The cooling water flowing through the third branch path 35 passes through the heater core 37 on the way. When the cooling water passes through the heater core 37, heat exchange is performed between the cooling water and the heater core 37, the heater core 37 is heated, and the cooling water is cooled. Then, the cooling water that has passed through the heater core 37 flows into the first branch path 32 and merges with the cooling water that flows through the first branch path 32.

  When the temperature of the cooling water is raised to a temperature higher than the second thermostatic setting temperature, the state of the second thermostat valve 34 is switched, and the second thermostat valve is switched from the second branch path 33 as indicated by a white arrow in FIG. The cooling water flowing into the flow 34 is divided from the second thermostat valve 34 into the third branch path 35 and the fourth branch path 36. When the cooling water flows through the fourth branch path 36, the cooling water passes through the oil cooler 15, heat exchange is performed between the cooling water and the oil cooler 15, the oil cooler 15 is cooled, and the cooling water Rises in temperature. The cooling water flowing through the fourth branch path 36 passes through the oil cooler 15, then flows into the first branch path 32, and merges with the cooling water flowing through the first branch path 32.

  Cooling water flowing through the first branch path 32 flows into the low temperature flow path 28 via the first thermostat valve 29. Thereby, in a state where the temperature of the cooling water is equal to or lower than the first thermo set temperature, the cooling water flows through the engine 11 without flowing through the radiator 23. Therefore, the temperature of the cooling water rises quickly.

  When the temperature of the cooling water rises to a temperature higher than the first thermosetting temperature, the state of the first thermostat valve 29 is switched, and the cooling water flows into the first thermostat valve 29 from the radiator 23 side of the low temperature passage 28. As a result, a part of the cooling water flowing through the high-temperature channel 31 flows from the radiator inlet 24 into the radiator channel. The cooling water that has flowed into the flow path in the radiator passes through the flow path in the radiator, then flows out from the flow path in the radiator to the low temperature flow path 28 via the radiator outlet 25, and flows through the low temperature flow path 28 toward the engine 11. .

  A radiator fan 38 is provided so as to face the radiator 23, and when the vehicle 1 stops, the cooling water flowing through each radiator flow path is cooled by blowing air from the radiator fan 38. When the vehicle 1 travels, even if the radiator fan 38 is not operating, the cooling water flowing through each radiator flow path is cooled by the traveling wind.

  In addition, a reserve tank (R / T) 42 is connected to the radiator 23 via a pressure regulating valve 41. When the pressure in the radiator 23 rises, the main pressure valve of the pressure regulating valve 41 opens, and the cooling water in the radiator 23 flows into the reserve tank 42 and is stored. When the pressure in the radiator 23 decreases, the negative pressure valve of the pressure regulating valve 41 is opened, and the cooling water in the reserve tank 42 is supplied into the radiator 23.

<Vehicle control system>
FIG. 3 is a block diagram showing the configuration (electrical configuration) of the control system of the vehicle 1.

  The vehicle 1 includes an ECU (Electronic Control Unit) having a configuration including a microcomputer. Although only one ECU 51 for controlling the engine 11 and the engine cooling system 21 is shown in FIG. 1, a plurality of ECUs are mounted on the vehicle 1 in order to control each part. A plurality of ECUs including the ECU 51 are connected so as to be capable of bidirectional communication using a CAN (Controller Area Network) communication protocol.

  Various sensors necessary for control are connected to the ECU 51. As an example, the ECU 51 uses an accelerator sensor 52 that outputs a detection signal corresponding to an operation amount of an accelerator pedal (not shown) operated by a driver, and a pulse signal synchronized with the rotation of the engine 11 as a detection signal. An engine rotation sensor 53 for outputting and a temperature sensor 54 for outputting a detection signal corresponding to the temperature of the cooling water flowing out from the WJ outlet 27 of the engine 11 are connected.

  The ECU 51 sets the ratio of the operation amount to the maximum operation amount of the accelerator pedal based on the signal input from the accelerator sensor 52, that is, 0% when the accelerator pedal is not depressed, and when the accelerator pedal is fully depressed. The accelerator opening, which is a percentage with the value 100%, is calculated. Further, the ECU 51 calculates the engine speed from the detection signal of the engine rotation sensor 53. Further, in the ECU 51, the temperature of the cooling water flowing out from the WJ outlet 27 of the engine 11 is acquired from the detection signal of the temperature sensor 54.

  The ECU 51 controls the engine 11, the water pump 22 of the engine cooling system 21, the radiator fan 38, and the like based on information acquired from detection signals from various sensors and / or various information input from other ECUs.

<Cooling water temperature control>
FIG. 4 is a diagram showing a fuel efficiency ratio contour line, a torque characteristic line, and a threshold curve used for temperature setting of cooling water.

  The fuel consumption rate contour is a contour plotting the engine speed and the position of the engine torque at the constant fuel consumption rate. The closer to the center of the contour line, the better the fuel consumption rate (fuel consumption rate).

  The torque characteristic line is a curve showing the relationship between the engine speed and the engine torque when the accelerator opening is fully open.

  The first threshold curve is a curve showing a boundary between a region (high rotation / heavy load region) where the engine 11 is high and heavy load and a region (medium rotation / medium load region) where the engine 11 is medium and medium load. . The second threshold curve is a curve showing a boundary between a medium rotation / medium load region of the engine 11 and a region (low rotation / light load region) where the rotation is low and light.

  The ECU 51 acquires the accelerator opening from the detection signal of the accelerator sensor 52, acquires the engine speed from the detection signal of the engine rotation sensor 53, and estimates the engine torque from the accelerator opening and the engine speed.

  When the engine speed and the engine torque are included in the high rotation / heavy load region of the engine 11, the ECU 51 sets the temperature of the cooling water in the engine cooling system 21 to the first temperature T1 (for example, 90 ° C.) The capacity (flow rate) of the water pump 22 is controlled so that the temperature of the cooling water acquired from the detection signal of the temperature sensor 54 approaches the set temperature (temperature target). Further, when the engine speed and the engine torque are included in the medium rotation / medium load region of the engine 11, the ECU 51 sets the coolant temperature to a second temperature T2 (for example, 95 ° C.) higher than the first temperature T1. Then, the ability of the water pump 22 is controlled so that the temperature of the cooling water acquired from the detection signal of the temperature sensor 54 approaches the set temperature. Furthermore, when the engine speed and the engine torque are included in the low rotation / low load region of the engine 11, the ECU 51 sets the coolant temperature to a third temperature T3 (for example, 100 ° C.) higher than the second temperature T2. And the capacity of the water pump 22 is controlled so that the temperature of the cooling water acquired from the detection signal of the temperature sensor 54 approaches the set temperature.

<Effect>
As described above, when the water pump 22 operates, the cooling water circulates between the engine 11 and the radiator 23. The engine 11 is cooled by heat exchange between the engine 11 and the cooling water, and the cooling water is cooled by heat exchange between the radiator 23 and the cooling water. Normally, the temperature of the cooling water is set to the second temperature T2, and the setting is changed from the second temperature T2 according to the operating state of the engine 11. When the setting of the temperature of the cooling water is changed, the flow rate of the cooling water by the water pump 22 is controlled in order to change the temperature of the cooling water between the normal temperature and the changed temperature.

  When the engine 11 is running at a low speed and a light load, the setting of the temperature of the cooling water is raised from the second temperature T2 to the third temperature T3, which is higher than that, so that the temperature of the cooling water approaches the third temperature T3. The flow rate of the cooling water by the water pump 22 is controlled. As a result, the heat generated by the combustion can be effectively used by reducing the amount of heat escaping to the cylinder of the engine 11 at the time of low rotation and light load of the engine 11, that is, reducing heat loss. As a result, it is possible to improve the thermal efficiency of the engine 11 at low speed and light load.

<Modification>
As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.

  For example, the cooling water is not limited to water, and may be a mixture of water and ethylene glycol, water or a mixture of additives. Further, the refrigerant used in the engine cooling system 21 is not limited to cooling water but may be oil.

  In the above-described embodiment, the vehicle 1 equipped with the engine 11 and the CVT 14 is taken up. However, the control device according to the present invention is not limited to such a vehicle 1, and a stepped automatic transmission (AT: Automatic). Transmission) or a vehicle equipped with a power split type continuously variable transmission. The power split type continuously variable transmission includes, for example, a continuously variable transmission mechanism that continuously changes power by changing a gear ratio, and transmits power divided between two paths between an input shaft and an output shaft. It is a possible transmission. The control device according to the present invention can also be used for a hybrid vehicle equipped with an engine and a drive motor. It does not matter whether the hybrid system is a series system, a parallel system, or a split system (series / parallel system).

  In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

11: Engine 21: Engine cooling system 22: Water pump 23: Radiator 51: ECU (control device, setting change means, flow rate control means)

Claims (1)

A control device used for an engine cooling system for cooling the engine by circulating a refrigerant between the engine and a radiator by operation of a water pump,
Setting changing means for changing the setting of the temperature of the refrigerant from the normal temperature according to the operating state of the engine;
A control device for an engine cooling system, comprising: a flow rate control means for controlling a flow rate of the refrigerant by the water pump in order to change the temperature of the refrigerant between the normal temperature and the temperature after the change by the setting change means. .

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