JP2006105106A - Engine cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve controllability of the cooling water temperature, by optimizing a conversion factor used for calculating a request radiator flow rate. <P>SOLUTION: This cooling system has cooling water circulating passages 12 and 15 of an engine 1, a radiator 13 in its circulating passages 12 and 15, and a flow control valve 16 for adjusting a cooling water flow rate of the radiator 13. An electronic control device ECU 30 calculates a cooling loss calorific value taken to cooling water from the engine 1 on the basis of an operation state of the engine 1. The ECU 30 controls the flow control valve 16 on the basis of its request radiator flow rate, by calculating the request radiator flow rate in the radiator 13 on the basis of the conversion factor for converting the cooling loss calorific value, the target cooling water temperature, the radiator outlet water temperature and the cooling water temperature into a flow rate for setting the cooling water temperature to the target cooling water temperature. Here, the ECU 30 calculates the conversion factor used for the calculation on the basis of a temperature difference between the engine outlet water temperature and the radiator outlet water temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a cooling device that cools an engine by circulating cooling water through a cooling water circulation path including a radiator, and controls a cooling water temperature to a target cooling water temperature by adjusting a flow rate of the cooling water passing through the radiator. The present invention relates to an engine cooling apparatus.

  Conventionally, as a cooling device for an engine mounted on a vehicle or the like, for example, there is a water-cooling type cooling device described in Patent Document 1 below. The cooling device includes a cooling water circulation path including a water jacket of the engine body, a radiator, a water pump and a flow control valve provided in the cooling water circulation path, and an electronic control unit (ECU) that controls the opening degree of the flow control valve. Is provided. In this cooling device, when the water pump is operated, the cooling water circulates through the cooling water circulation path, and heat is transferred between the cooling water and the engine body. At this time, the heat taken from the engine body to the cooling water is dissipated in the process of the cooling water passing through the radiator. Here, the ECU controls the opening degree of the flow control valve so that the actual cooling water temperature becomes the target cooling water temperature.

Specifically, in this cooling device, when the operating state of the engine changes, even if the amount of heat (cooling loss heat amount) QW taken away from the engine body by the cooling water changes, the cooling water temperature is responsive to the target cooling water temperature. The ECU calculates the cooling loss heat quantity QW based on the operating state of the engine (engine speed and engine load) so as to converge. Further, the ECU sets the required cooling water passage amount (required radiator flow rate) V2 in the radiator for converging the cooling water temperature to the target cooling water temperature, the cooling loss heat quantity QW, the target cooling water temperature (target engine outlet water temperature) Tt, and Based on the cooling water temperature (radiator outlet water temperature) T2 after passing through the radiator, it is calculated according to the following calculation formula (1). In the calculation formula (1), “C” is a conversion coefficient for converting the temperature into the flow rate, and is determined by, for example, the product of the specific heat of the cooling water and the density.
V2 = QW / {C · (Tt−T2)} (1)
And ECU controls the cooling water temperature in a cooling water circulation path | route by controlling the opening degree of a flow control valve based on the calculated required radiator flow V2, and controls the cooling degree of an engine. In this way, by controlling the degree of cooling of the engine according to the operating state of the engine, it is possible to reduce engine friction, improve fuel consumption, improve knocking performance, and the like.

On the other hand, in the cooling device of Patent Document 1, when a heat receiving / radiating circuit (for example, a heater circuit, a throttle body hot water circuit, an EGR cooler circuit, etc.) that bypasses the radiator is provided in the cooling water circulation path, It is necessary to reflect the amount of heat received and radiated heat Qetc in the calculation of the required radiator flow rate V2. Therefore, the ECU determines the amount of received and radiated heat Qetc as a flow rate (merging portion flow rate) V3 at the merging portion where downstream portions of the plurality of receiving and radiating circuits merge, and a cooling water temperature (merging portion water temperature) T3 at the merging portion Based on the cooling water temperature (engine outlet water temperature) TO at the engine outlet, calculation is performed according to the following calculation formula (2). Then, the ECU calculates the required radiator flow rate V2 in accordance with the following calculation formula (3) based on the calculated cooling loss heat quantity QW, the calculated heat receiving and radiating heat quantity Qetc, the target engine outlet water temperature Tt, and the radiator outlet water temperature T2. To do. In formulas (2) and (3), “C” is the same conversion coefficient as in formula (1).
Qetc = C / V3 / (TO-T3) (2)
V2 = (QW−Qetc) / {C · (Tt−T2)} (3)
Then, the ECU controls the degree of cooling of the engine by controlling the cooling water temperature in the cooling water circulation path by controlling the opening degree of the flow rate control valve based on the calculated required radiator flow rate V2.

Japanese Unexamined Patent Publication No. 2003-239742 (pages 5 and 7 and FIGS. 1, 2 and 6)

  However, in the cooling device of Patent Document 1, since the conversion coefficient C used in the above-described calculation formulas (1) to (3) is a constant, the required radiator flow rate when the fluctuation of the cooling water temperature increases in the radiator. An error may occur in the calculation of V2, and the controllability of the cooling water temperature may be deteriorated. In particular, when the vehicle travels at a high speed, the radiator receives a large amount of wind flow, so the amount of heat released from the radiator increases, and the radiator outlet water temperature T2 greatly decreases. Therefore, the calculation error of the required radiator flow rate V2 is correspondingly increased. There was a tendency to grow. This calculation error may reach “15%” at the maximum. For this reason, there is a concern that the controllability of the degree of cooling of the engine is lowered, and the friction reduction, fuel consumption and knocking performance of the engine are deteriorated.

  The present invention has been made in view of the above circumstances, and its object is to improve the controllability of the cooling water temperature by optimizing the conversion coefficient used for calculating the required radiator flow rate. An object of the present invention is to provide a cooling device for an engine.

  In order to achieve the above object, an invention according to claim 1 is directed to a cooling water circulation path through which engine cooling water circulates, a radiator provided in the cooling water circulation path, and a flow rate of cooling water passing through the radiator. An engine cooling device comprising a flow rate adjusting means and controlling the flow rate adjusting means so that the engine cooling water temperature becomes a target cooling water temperature. Cooling loss calorie calculating means for calculating based on the operating state of the engine, and the required radiator flow rate required for the radiator in order to set the engine cooling water temperature to the target cooling water temperature, the calculated cooling loss calorific value , The target cooling water temperature, the cooling water temperature after passing through the radiator after passing through the radiator, and the conversion coefficient for converting the cooling water temperature into the cooling water flow rate In a cooling device for an engine having a required radiator flow rate calculating means for controlling and a control means for controlling the flow rate adjusting means based on the calculated required radiator flow rate, the conversion coefficient is calculated after passing through the engine. It is intended that a conversion coefficient calculating means for calculating based on a temperature difference between the cooling water temperature and the cooling water temperature after passing through the radiator is provided.

According to the configuration of the invention described above, the cooling loss heat amount taken from the engine to the cooling water is calculated by the cooling loss heat amount calculation means based on the operating state of the engine. In addition, in order to set the engine coolant temperature to the target coolant temperature, the required radiator flow rate of the coolant required by the radiator is calculated as the amount of heat loss calculated, the amount of heat received and radiated, the target coolant temperature, the radiator It is calculated by the required radiator flow rate calculation means based on the post-passage cooling water temperature and the conversion coefficient for converting the cooling water temperature into the cooling water flow rate. Then, the flow rate adjusting means is controlled by the control means based on the calculated required radiator flow rate. Thereby, the engine coolant temperature is brought close to the target coolant temperature.
Here, the conversion coefficient used to calculate the required radiator flow rate is calculated by the conversion coefficient calculation means based on the temperature difference between the coolant temperature after passing through the engine and the coolant temperature after passing through the radiator. Therefore, even if the amount of heat released from the radiator changes and the coolant temperature changes after passing the radiator, the conversion coefficient calculated based on the temperature difference between the coolant temperature after passing the engine and the coolant temperature after passing the radiator is the required radiator. Since it is reflected in the calculation of the flow rate, the calculation error of the required radiator flow rate is reduced.

  To achieve the above object, the invention according to claim 2 is provided in the cooling water circulation path through which the cooling water of the engine circulates, the radiator provided in the cooling water circulation path, and the cooling water circulation path so as to bypass the radiator. An engine cooling system comprising a heat receiving and radiating circuit and a flow rate adjusting means for adjusting a flow rate of cooling water passing through the radiator, and controlling the flow rate adjusting means so that the engine cooling water temperature becomes a target cooling water temperature. Cooling loss calorie calculating means for calculating the cooling loss calorie taken from the engine to the cooling water based on the operating state of the engine, and the amount of heat received and radiated between the receiving and radiating circuit and the cooling water The cooling water temperature after passing through the engine after passing through the engine, the cooling water temperature after passing through the circuit after passing through the heat receiving and radiating circuit, the cooling water flow rate after passing through the circuit, and the cooling water The means for calculating the amount of heat received and radiated based on the conversion coefficient for converting the degree of cooling into the cooling water flow rate, and the required radiator flow rate of the cooling water required by the radiator to set the engine cooling water temperature to the target cooling water temperature. A required radiator flow rate calculation means for calculating on the basis of the calculated cooling loss heat amount, the calculated heat receiving and radiating heat amount, the target cooling water temperature, the cooling water temperature after passing through the radiator after passing through the radiator, and the conversion coefficient. In a cooling device for an engine having control means for controlling the flow rate adjusting means based on the required radiator flow rate, the conversion coefficient is calculated based on the temperature difference between the coolant temperature after passing the engine and the coolant temperature after passing the radiator The purpose is to provide conversion coefficient calculation means for this purpose.

According to the configuration of the invention described above, the cooling loss heat amount taken from the engine to the cooling water is calculated by the cooling loss heat amount calculation means based on the operating state of the engine. The amount of heat received and radiated between the heat receiving and radiating circuit and the cooling water is determined based on the cooling water temperature after passing through the engine, the cooling water temperature after passing through the circuit, the cooling water flow after passing through the circuit, and the conversion coefficient. Calculated by the calorie calculation means. In addition, in order to set the engine coolant temperature to the target coolant temperature, the required radiator flow rate of the coolant required by the radiator is calculated as the amount of heat loss calculated, the amount of heat received and radiated, the target coolant temperature, the radiator Based on the post-passage cooling water temperature and the conversion coefficient, it is calculated by the required radiator flow rate calculation means. Then, the flow rate adjusting means is controlled by the control means based on the calculated required radiator flow rate. Thereby, the engine coolant temperature is brought close to the target coolant temperature.
Here, the conversion coefficient used for the calculation of the amount of heat received and radiated and the required radiator flow rate is calculated by the conversion coefficient calculation means based on the temperature difference between the cooling water temperature after passing through the engine and the cooling water temperature after passing through the radiator. Therefore, even if the amount of heat released from the radiator changes and the coolant temperature changes after passing through the radiator, the conversion coefficient calculated based on the temperature difference between the coolant temperature after passing through the engine and the coolant temperature after passing through the radiator is Since it is reflected in the calculation of the heat amount and the calculation of the required radiator flow rate, the calculation error of the received and radiated heat amount and the required radiator flow rate is reduced.

  In order to achieve the above object, according to a third aspect of the present invention, in the first or second aspect of the present invention, the conversion coefficient calculating means becomes relatively small as the temperature difference becomes relatively large. Thus, the purpose is to calculate the conversion coefficient.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 1 or 2, the conversion coefficient is calculated by the conversion coefficient calculation means so that the temperature difference becomes relatively small as the temperature difference becomes relatively large. Therefore, when the temperature difference is relatively large, a relatively small conversion coefficient is reflected in the calculation of the required radiator flow rate, and when the temperature difference is relatively small, a relatively large conversion coefficient is reflected in the required radiator flow rate. It is reflected in the calculation.

  According to the first aspect of the present invention, the conversion coefficient used for calculating the required radiator flow rate can be optimized, the calculation accuracy of the required radiator flow rate can be improved, and the cooling water of the engine can be increased. Temperature controllability can be improved. For this reason, it is possible to reduce engine friction, improve fuel consumption, and knock performance.

  According to the invention described in claim 2, it is possible to optimize the conversion coefficient used for calculating the amount of heat received and radiated and the required radiator flow rate, and to increase the calculation accuracy of the amount of received and radiated heat and the required radiator flow rate. As a result, the controllability of the engine coolant temperature can be improved. For this reason, it is possible to reduce engine friction, improve fuel consumption, and knock performance.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, the conversion coefficient can be set to a value that is more actually adapted. In this sense, the calculation accuracy of the required radiator flow rate Can be increased.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an engine cooling device according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an engine system in this embodiment. A multi-cylinder engine 1 mounted on a vehicle includes an engine body 2 including a cylinder block and a cylinder head. The engine body 2 is provided with a fuel injection valve and an ignition device (both not shown) corresponding to the combustion chamber of each cylinder (cylinder). The engine body 2 is provided with a piston (not shown) for each cylinder and a crankshaft 3 that is linked to each piston. The engine body 2 is provided with an intake passage 4 for taking air into each combustion chamber. The engine body 2 is provided with an exhaust passage 5 for exhausting exhaust gas from each combustion chamber. An air cleaner 6 and a throttle body 7 are provided in the intake passage 4. The air cleaner 6 cleans the air taken into each combustion chamber through the intake passage 4. The throttle body 7 is provided with a throttle valve 8 that is opened and closed to adjust the amount of air flowing through the intake passage 4 (intake amount), and a motor 9 that drives the valve 8 to open and close.

  The fuel injected from the fuel injection valve is supplied to each combustion chamber of the engine body 2. In each combustion chamber, the combustible mixture of fuel and air explodes and burns when the ignition device operates. When the piston operates by receiving this combustion energy, the crankshaft 3 rotates and power is generated in the engine 1. The exhaust gas after combustion generated in each combustion chamber is discharged to the outside through the exhaust passage 5. A part of the combustion energy generated in the engine 1 remains in the engine body 2 as heat. In order to prevent the engine main body 2 from being overheated by this residual heat, the engine 1 is provided with a water-cooled cooling device 10.

  The cooling device 10 includes a water jacket 11 provided in the engine body 2. The inlet 11 a and the outlet 11 b of the water jacket 11 are connected to the radiator 13 through the radiator passage 12. A water pump (W / P) 14 is provided in the vicinity of the inlet 11 a of the water jacket 11. The water pump 14 is drivingly connected to the crankshaft 3 via a pulley, a belt, and the like, and operates in conjunction with the operation of the engine 1. The water pump 14 sucks the cooling water flowing through the radiator passage 12 and discharges it to the water jacket 11. By this cooling water suction / discharge, the cooling water circulates in the clockwise direction indicated by the arrow in FIG. 1 starting from the water pump 14. During this circulation, the cooling water absorbs heat from the engine body 2 and rises in temperature in the process of passing through the water jacket 11. The raised cooling water releases heat in the process of passing through the radiator 13 to lower the temperature. As is well known, the radiator 13 is provided facing the front side of the vehicle, so that it is easy to receive the traveling wind of the vehicle. For this reason, the amount of heat released from the radiator 13 can be changed by the difference in the vehicle speed, that is, the difference in the amount that the radiator 13 receives the traveling wind.

  A bypass passage 15 that bypasses the radiator 13 is connected to the radiator passage 12. One end of the bypass passage 15 (the right end in FIG. 1) is connected between the radiator 13 and the outlet 11 b of the water jacket 11 in the radiator passage 12. The other end (the left end in FIG. 1) of the bypass passage 15 is connected between the radiator 13 and the water pump 14 in the radiator passage 12. The water jacket 11 and the radiator passage 12 described above constitute a cooling water circulation path in the present invention.

  A flow rate control valve 16 is provided at a connection portion between the other end of the bypass passage 15 and the radiator passage 12. The flow rate control valve 16 is configured with a step motor as a drive source, and adjusts the flow rate of the cooling water flowing through the radiator passage 12 and the bypass passage 15 by controlling the valve opening degree ODV. This flow control valve 16 corresponds to the flow rate adjusting means in the present invention. Here, the flow rate control valve 16 is configured such that the flow rate of cooling water passing through the radiator passage 12 increases as the valve opening degree ODV increases.

  The flow rate control valve 16 controls the coolant temperature for cooling the engine body 2 by adjusting the coolant flow rate in the radiator passage 12. That is, by controlling the valve opening degree ODV of the flow control valve 16 to increase the coolant flow rate in the radiator passage 12, the ratio of the coolant water cooled by the radiator 13 out of the coolant water flowing through the engine body 2 is large. Thus, the temperature of the cooling water for cooling the engine body 2 is lowered. Further, by controlling the flow rate control valve 16 to reduce the cooling water flow rate in the radiator passage 12, the ratio of the cooling water cooled by the radiator 13 out of the cooling water flowing through the engine main body 2 is reduced. The temperature of the cooling water for cooling is increased.

  The radiator 13 is provided with a radiator outlet water temperature sensor 21 for detecting a cooling water temperature (radiator outlet water temperature T2) after passing through the radiator 13. Here, the radiator outlet water temperature T2 corresponds to the cooling water temperature after passing through the radiator in the present invention. The engine body 2 is provided with an engine outlet water temperature sensor 22 for detecting the coolant temperature (engine outlet water temperature TO) after passing through the outlet 11 b of the water jacket 11 as the coolant temperature of the engine body 2. Here, the engine outlet water temperature TO corresponds to the post-engine coolant temperature in the present invention.

  In addition to the bypass passage 15, the cooling device 10 further includes a plurality of heat receiving and radiating circuits provided in the radiator passage 12 so as to bypass the radiator 13. As these heat receiving and radiating circuits, a throttle body hot water circuit 31, an EGR cooler circuit 32, a hot water heating type hot air intake circuit 33, a heater circuit 34, and an oil cooler circuit 35 are provided.

  The throttle body warm water circuit 31 is connected to the throttle body 7, and the throttle body 7 is warmed in the process of cooling water (warm water) flowing through the circuit body 31. As a result, the operation of the throttle valve 8 at the time of extreme cold or the like is stabilized.

  The EGR cooler circuit 32 is connected in series downstream of the throttle body warm water circuit 31. A part of the EGR cooler circuit 32 is provided along the EGR device 36. As is well known, the EGR device 36 reduces the maximum combustion temperature of the combustible mixture by recirculating a part of the exhaust gas to the intake passage 4 in order to reduce nitrogen oxide (NOx) in the exhaust gas. It is. The EGR device 36 includes an EGR passage 37, an EGR valve 38, and an EGR chamber 39. The EGR passage 37 is provided between the exhaust passage 5 and the intake passage 4. The EGR valve 38 is provided in the middle of the EGR passage 37 and is configured to adjust the flow rate of EGR gas flowing through the EGR passage 37. The EGR chamber 39 is provided on the downstream side of the EGR passage 37, and is configured to guide EGR gas evenly to each cylinder. The EGR chamber 39, the EGR valve 38, and the intake passage 4 are cooled by the cooling water flowing through the EGR cooler circuit 32.

  The hot air intake circuit 33 is connected to the air cleaner 6. The circuit 33 includes a heater core (not shown) provided in the vicinity of the air cleaner 6, and air sucked into the intake passage 4 is warmed in the process in which cooling water passes through the heater core.

  The heater circuit 34 is connected to the heater core 40 of the vehicle interior heating device. The cooling water flowing through the heater circuit 34 is guided to the heater core 40 as a heat source, so that the vehicle compartment heating device functions.

  The oil cooler circuit 35 is connected to an oil cooler 41 for cooling the lubricating oil in the lubricating device of the engine 1 and the hydraulic oil (automatic transmission fluid: ATF) in the automatic transmission. When the cooling water flows through the oil cooler 41, the lubricating oil and ATF are quickly cooled at high temperatures. The oil cooler 41 also functions as an oil warmer when the temperature of the lubricating oil or ATF is low.

  The upstream portion of each of the above described heat receiving and radiating circuits is connected to the radiator passage 12 between the outlet 11 b of the water jacket 11 and the radiator 13. The downstream portions of these heat receiving and radiating circuits merge with each other and are connected to the water pump 14. A junction water temperature sensor 23 for detecting the cooling water temperature in the junction 42 as a junction water temperature T3 is provided in the vicinity of the junction 42 of each receiving and radiating circuit. Here, the junction water temperature T3 corresponds to the post-circuit cooling water temperature in the present invention.

  The vehicle is provided with various sensors for detecting the operating state of the engine 1. In other words, the accelerator sensor 24 is provided in the accelerator pedal 43 provided in the driver's seat. The accelerator sensor 24 detects the depression amount (accelerator opening) ACCP of the accelerator pedal 43. A throttle sensor 25 provided in the throttle body 7 detects the opening degree (throttle opening degree) TA of the throttle valve 8. An intake pressure sensor 26 provided in the intake passage 4 downstream of the throttle body 7 detects the intake pressure PM in the intake passage 4. A rotational speed sensor 27 provided corresponding to the crankshaft 3 detects a rotational angle (crank angle) and a rotational speed (engine rotational speed) NE of the crankshaft 3.

  The cooling device 10 controls the flow rate control valve 16 based on the operating state of the engine 1 in order to control the degree of cooling of the engine 1 according to the operating state of the engine 1, and the water jacket 11, the radiator passage 12, and the bypass The cooling water circulation flow rate in the passage 15 is adjusted. In order to control this control, the cooling device 10 includes an electronic control unit (ECU) 30. The ECU 30 is connected to a radiator outlet temperature sensor 21, an engine outlet water temperature sensor 22, a junction water temperature sensor 23, and a flow rate control valve 16. In addition, an accelerator sensor 24, a throttle sensor 25, an intake pressure sensor 26, and a rotational speed sensor 27 are connected to the ECU 30 in order to capture the operating state of the engine 1. In addition, an ignition switch (IGSW) 28 is connected to the ECU 30. The ignition switch 28 is operated to start and stop the engine 1.

  In this embodiment, the ECU 30 performs the cooling water temperature control, and corresponds to the cooling loss heat amount calculating means, the received / heated heat radiation calculating means, the required radiator flow rate calculating means, the control means, and the conversion coefficient calculating means in the present invention. As is well known, the ECU 30 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a backup RAM, an external input circuit, an external output circuit, and the like. The ECU 30 configures a logical operation circuit formed by connecting a CPU, a ROM, a RAM, a backup RAM, an external input circuit, an external output circuit, and the like through a bus. The ROM stores in advance a predetermined control program related to cooling water temperature control and the like. The RAM temporarily stores the calculation result of the CPU. The backup RAM stores data stored in advance. The CPU executes cooling water temperature control and the like according to a predetermined control program based on detection signals from various sensors 21 to 28 inputted via the input circuit.

  Next, the content of the coolant temperature control executed by the ECU 30 will be described with reference to the flowchart of FIG.

When the process proceeds to this routine, in step 100, the ECU 30 determines the temperature between the engine outlet water temperature TO obtained from the detected value of the engine outlet water temperature sensor 22 and the radiator outlet water temperature T2 obtained from the detected value of the radiator outlet water temperature sensor 21. Calculate the difference dlthw. That is, the ECU 30 calculates the temperature difference dlthw according to the following calculation formula (4).
dlthw = TO-T2 (4)

  Thereafter, in step 110, the ECU 30 calculates the conversion coefficient C based on the calculated temperature difference dlthw. “C” is a conversion coefficient for converting the cooling water temperature into the cooling water flow rate, and is determined by the product of the specific heat of the cooling water and the density. In calculating the conversion coefficient C, the ECU 30 refers to function data (map) as shown in FIG. This map predetermines the relationship of the conversion coefficient C to the temperature difference dlthw. In this map, the conversion coefficient C is set so as to become relatively small as the temperature difference dlthw becomes relatively large.

  Next, at step 120, the ECU 30 calculates the cooling loss heat quantity QW based on the engine rotation speed NE and the engine load LE obtained from the detection values of the rotation speed sensor 27 and the intake pressure sensor 26. In this calculation, the ECU 30 refers to function data (map) as shown in FIG. This map predetermines the relationship of the cooling loss heat quantity QW to the engine speed NE and the engine load LE. This map is prepared for each value of the engine outlet water temperature TO. In this map, the cooling loss heat quantity QW is small when the engine rotational speed NE is low, and increases as the engine rotational speed NE increases. This is because the higher the engine speed NE is, the more fuel is supplied to the combustion chamber per unit time, and the more heat is generated in the engine body 2, and the more heat is taken away from the engine body 2 by the cooling water. Because it becomes. In this map, the cooling loss heat quantity QW is small when the engine load LE is small, and increases as the engine load LE increases. However, in the region where the engine speed NE is high, the degree of increase in the cooling loss heat quantity QW becomes moderate as the engine load LE increases. This is because, as described above, the amount of fuel supplied per unit time increases due to the increase in the engine rotational speed NE, the temperature of the combustion chamber decreases due to the cooling effect accompanying the increase in the amount of fuel, and the amount of heat taken away from the engine body 2 by the cooling water. This is because of the decrease.

  An engine load factor can be used instead of the engine load LE described above. The engine load factor is a parameter indicating a load ratio with respect to the maximum load. In this case as well, a map according to FIG. 4 can be used.

  The above-described cooling loss heat quantity QW basically depends on the amount of heat generated from the engine body 2, and therefore, the engine load LE is a parameter related to the amount of heat generated from the engine body 2, for example, one combustion cycle. The fuel injection amount, the intake air amount, etc. can be used. The amount of intake air is a parameter indirectly related to the amount of heat generated from the engine body 2 because fuel according to the amount of intake air is injected in fuel injection control separately executed. In addition, as the engine load LE, it is possible to use the intake pressure PM detected by the intake pressure sensor 26, the throttle opening degree TA detected by the throttle sensor 25, etc., but in this case, the correction is made appropriately. It is desirable.

  Next, in step 130, the ECU 30 calculates a coolant flow rate (merging portion flow rate) V3 in the merging portion 42 based on the valve opening degree ODV of the flow control valve 16 and the engine speed NE. In this calculation, the ECU 30 refers to function data (map) as shown in FIG. This map predetermines the relationship of the junction flow rate V3 with respect to the valve opening degree ODV of the flow rate control valve 16 and the engine rotational speed NE. In this map, in the region where the valve opening degree ODV is small, as the valve opening degree ODV increases, the junction flow rate V3 gradually decreases. In the region where the valve opening degree ODV is medium to large, the junction flow rate V3 is substantially constant regardless of the valve opening degree ODV. Further, the merging portion flow rate V3 is small when the engine speed NE is low and increases as the engine speed NE increases. Here, the merging portion flow rate V3 corresponds to the post-circuit passage coolant flow rate in the present invention. As the above-described valve opening degree ODV, for example, the command opening degree ODC used by the ECU 30 for the flow control valve 16 in the previous control cycle can be applied.

Next, in step 140, the ECU 30 calculates the amount of received and radiated heat Qetc based on the various parameters obtained this time, that is, the merging portion flow rate V3, the merging portion water temperature T3, the engine outlet water temperature TO, and the conversion coefficient C. The ECU 30 calculates the amount of received and radiated heat Qetc (total amount of received and radiated heat in each of the circuits 31 to 35) in all the received and radiated circuits according to the following calculation formula (5).
Qetc = C / V3 / (TO-T3) (5)

Next, at step 150, the ECU 30 determines the required radiator flow rate V2 based on the various parameters obtained this time, that is, the cooling loss heat quantity QW, the target engine outlet water temperature Tt, the radiator outlet water temperature T2, the heat receiving / radiating heat quantity Qetc, and the conversion coefficient C. Is calculated. The ECU 30 calculates the flow rate V2 according to the following calculation formula (6).
V2 = (QW−Qetc) / {C · (Tt−T2)} (6)
Here, the target engine outlet water temperature Tt is determined according to the operating state of the engine 1 and corresponds to the target cooling water temperature in the present invention. For example, when the engine 1 is in the idling operation state, the target engine outlet water temperature Tt is set to a slightly lower temperature (for example, “90 ° C.”) for measures against knocking at the time of start. On the other hand, when the engine 1 is in a partial load (partial) operation state, the target engine outlet water temperature Tt is set to a higher temperature (for example, “100 ° C.”) to reduce friction loss. When the engine 1 is in the full load (WOT) operation state, the target engine outlet water temperature Tt is set to a lower temperature (for example, “80 ° C.”) in order to increase the filling rate. Each value (90 ° C., 100 ° C., 80 ° C.) related to the target engine outlet water temperature Tt is merely an example.

  Next, in step 160, the ECU 30 calculates a command opening degree ODC for the flow rate control valve 16 based on the calculated required radiator flow rate V2 and the engine speed NE. In this calculation, the ECU 30 refers to function data (map) as shown in FIG. This map predetermines the relationship of the command opening degree ODC with respect to the required radiator flow rate V2 and the engine speed NE. In this map, the command opening degree ODC is small when the required radiator flow rate V2 is small, and increases as the required radiator flow rate V2 increases. Further, the command opening degree ODC changes greatly even when the required radiator flow rate V2 slightly changes when the engine speed NE is low. On the other hand, the command opening degree ODC does not change much when the engine speed NE is high unless the required radiator flow rate V2 changes much.

  Thereafter, in step 170, the ECU 30 drives and controls the flow rate control valve 16 based on the calculated command opening degree ODC, and then temporarily terminates the subsequent processing. By controlling the opening degree of the flow control valve 16 in this way, the flow rate of the cooling water passing through the radiator 13 is adjusted, and the engine outlet water temperature TO converges to the target engine outlet water temperature Tt.

  According to the engine cooling apparatus in this embodiment described above, the cooling loss heat quantity QW taken from the engine body 2 to the cooling water is calculated by the ECU 30 based on the operating state of the engine 1. Further, the amount of received and radiated heat Qetc received and received between the heat receiving and radiating circuit (each circuit 31 to 35) and the cooling water is based on the engine outlet water temperature TO, the merging portion water temperature T3, the merging portion flow rate V3, and the conversion coefficient C. Calculated by the ECU 30. Further, in order to set the engine outlet water temperature TO to the target engine outlet water temperature Tt, the required radiator flow rate V2 of the cooling water required by the radiator 13 is calculated as the cooling loss heat quantity QW and the received and radiated heat quantity Qetc, respectively calculated as described above. In addition, the ECU 30 calculates the conversion coefficient C, the target engine outlet water temperature Tt, and the radiator outlet water temperature T2. The command opening degree ODC is calculated by the ECU 30 based on the calculated required radiator flow rate V2, and the flow control valve 16 is driven and controlled based on the command opening degree ODC. The degree ODV is controlled. Thereby, the engine outlet water temperature TO is brought close to the target engine outlet water temperature Tt.

  That is, in the cooling device 10 of this embodiment, the cooling water of the engine 1 passes through the radiator 13 while circulating through the water jacket 11 and the radiator passage 12, and the flow rate of the cooling water passing through the radiator 13 is controlled by the flow control valve 16. Adjusted. Then, the degree of cooling of the engine 1 is controlled by controlling the flow rate control valve 16 so that the engine outlet water temperature TO becomes the target engine outlet water temperature Tt.

  Here, since the radiator 13 is provided on the front side of the vehicle, when the vehicle travels at a high speed, the radiator 13 receives a lot of traveling wind, so that the amount of heat released from the radiator 13 increases. Therefore, as shown in FIGS. 7A and 7B, as the vehicle speed increases, the radiator outlet water temperature T2 decreases, and the temperature difference dlthw between the engine outlet water temperature TO and the radiator outlet water temperature T2 increases. For this reason, the calculation error of the required radiator flow rate V2 has become a problem as the temperature difference dlthw increases.

  On the other hand, in this embodiment, the conversion coefficient C used for the calculation of the above-described received and radiated heat quantity Qetc and the required radiator flow rate V2 is determined by the ECU 30 based on the temperature difference dlthw between the engine outlet water temperature TO and the radiator outlet water temperature T2. Calculated. This conversion coefficient C is calculated so as to become relatively small as the temperature difference dlthw becomes relatively large. Therefore, even if the amount of heat released from the radiator 13 changes and the radiator outlet water temperature T2 changes, the conversion coefficient C calculated from the above temperature difference dlthw is reflected in the calculation of the amount of received and radiated heat Qetc and the calculation of the required radiator flow rate V2. As a result, the calculation error of the amount of received and radiated heat Qetc and the required radiator flow rate V2 is reduced. As a result, it is possible to optimize the conversion coefficient C used for calculating the amount of received and radiated heat Qetc and the required radiator flow rate V2, to increase the calculation accuracy of the required radiator flow rate V2, and to cool the engine 1 as a result. The controllability of the water temperature can be improved. For this reason, it is possible to reduce the friction of the engine 1 and improve the fuel consumption and knocking performance.

  In addition, in this embodiment, as shown by a map in FIG. 3, the conversion coefficient C is calculated so that the temperature difference dlthw becomes relatively small as the temperature difference dlthw becomes relatively large. When the temperature difference is relatively large, a relatively small conversion coefficient C is reflected in the calculation of the heat receiving and radiating heat quantity Qetc and the required radiator flow rate V2, and when the temperature difference dlthw is relatively small, the relatively large conversion coefficient C is received and radiated. This is reflected in the calculation of the heat quantity Qetc and the required radiator flow rate V2. For this reason, the conversion coefficient C can be set to a value that is actually more suitable, and in this sense, the calculation accuracy of the required radiator flow rate can be increased.

  In addition, in this embodiment, as described above, the engine rotational speed NE and the engine load LE are reflected in the control of the valve opening degree ODV of the flow control valve 16 as the parameters relating to the operating state of the engine 1. For this reason, unlike the case where the valve opening degree ODV of the flow rate control valve 16 is controlled based solely on the temperature of the cooling water, the actual engine outlet water temperature TO is determined based on the engine rotational speed NE and the engine load LE. The target engine outlet water temperature Tt can be controlled. For example, when the engine 1 has a high output, the engine outlet water temperature TO can be lowered to increase the cooling efficiency of each cylinder. Further, when the engine 1 is operated with low fuel consumption, the engine outlet water temperature TO can be increased to improve the combustion efficiency in each cylinder. For this reason, the engine performance can be improved while satisfying the conflicting performances of high output and low fuel consumption.

  In this embodiment, the engine speed NE and the engine load LE are applied as parameters relating to the operating state of the engine 1 in order to calculate the cooling loss heat quantity QW. Thus, by applying the engine rotation speed NE and the engine load LE that influence the heat generation from the engine body 2 as parameters, the cooling loss heat quantity QW can be calculated with high accuracy. Further, since the cooling loss heat quantity QW is calculated based on both the engine rotation speed NE and the engine load LE, the calculation accuracy of the cooling loss heat quantity QW can be improved compared to the case where the engine rotation speed NE or the engine load LE is applied alone. Improvements can be made.

  In this embodiment, the cooling loss heat quantity QW is calculated based on the engine rotational speed NE indicating the operating state of the engine 1 and the engine load LE, and the calculated cooling loss heat quantity QW is reflected in the calculation of the required radiator flow rate V2. . Then, the valve opening degree ODV of the flow rate control valve 16 is controlled based on the calculated required radiator flow rate V2. For this reason, even if the operating state of the engine 1 changes and the cooling loss heat quantity QW changes, the valve opening degree ODV of the flow control valve 16 can be controlled according to the change in the cooling loss heat quantity QW, and the engine outlet The water temperature TO can be controlled to the target engine outlet water temperature Tt with good responsiveness.

  Here, in the case where the valve opening degree of the flow rate control valve is feedback-controlled based only on the deviation (water temperature difference) between the cooling water temperature and the target cooling water temperature, it corresponds to the change in the cooling loss heat quantity QW in the engine body 2. Since this is not possible, it is difficult to obtain good responsiveness regarding control as in this embodiment. For this reason, in this embodiment, the engine outlet water temperature TO can be quickly decreased during the high-power operation of the engine 1 described above, and the engine outlet water temperature TO can be quickly increased during the low fuel consumption operation of the engine 1. It is possible to reduce the control loss that occurs when realizing both high output and low fuel consumption.

  Here, if the command opening degree ODC of the flow control valve 16 is directly calculated from the operating state of the engine 1 and the valve opening degree ODV of the flow control valve 16 is to be controlled based on the calculated command opening degree ODC. When flow control valves having different flow characteristics are used, it is necessary to calculate the command opening degree ODC again for each flow control valve, and the versatility is lacking. In contrast, in this embodiment, the required radiator flow rate V2 with respect to the radiator outlet water temperature T2 is once calculated, and the command opening degree ODC of the flow control valve 16 is calculated based on the calculated required radiator flow rate V2. . For this reason, even when flow control valves having different flow characteristics are used, it is not necessary to newly calculate the command opening degree ODC corresponding to the flow characteristics for each flow control valve.

  By the way, in this embodiment, since the radiator passage 12 is provided with a plurality of heat receiving and radiating circuits (each circuit 31 to 35) so as to bypass the radiator 13, in the process of cooling water passing through each circuit 31 to 35, each part Heat is received and released (received and radiated) between the cooling water and the cooling water. The cooling water after receiving and radiating heat passes through the radiator passage 12 from the junction 42 through the water pump 14 and again passes through the water jacket 11 of the engine body 2. When the amount of heat received and radiated heat Qetc in each circuit 31 to 35 is large, it is difficult to converge the engine outlet water temperature TO to the target engine outlet water temperature Tt unless the received and radiated heat amount Qetc is taken into consideration, and the cooling water temperature is exceeded. There is concern that shooting and undershooting will occur. Here, “overshoot” is a phenomenon in which the target engine outlet water temperature Tt cannot be maintained after the engine outlet water temperature TO reaches the target engine outlet water temperature Tt, and rises. The “undershoot” is a phenomenon in which, after the engine outlet water temperature TO reaches the target engine outlet water temperature Tt, the target engine outlet water temperature Tt cannot be maintained and falls.

  In this way, when many overshoots and undershoots occur in the cooling water temperature, it is necessary to consider the heat resistance of each component such as the engine body 2 to ensure the normal operation of each component. It is necessary to lower Tt. On the other hand, if the target engine outlet water temperature Tt is simply lowered, the engine outlet water temperature TO is lowered, so that friction increases in the engine 1 or the automatic transmission, which may lead to deterioration in fuel consumption of the engine 1.

  On the other hand, in this embodiment, the amount of received and radiated heat Qetc in all the heat receiving and radiating circuits (all of the circuits 31 to 35) is calculated, and the calculated amount of received and radiated heat Qetc is reflected in the calculation of the required radiator flow rate V2. . Therefore, even if the amount of received and radiated heat Qetc in each circuit 31 to 35 changes, the convergence property of the engine outlet water temperature TO with respect to the target engine outlet water temperature Tt is improved. For this reason, overshoot and undershoot in the cooling water temperature control can be reduced, and it is not necessary to lower the target engine outlet water temperature Tt in consideration of the heat resistance related to the components such as the engine body 2. As a result, it is possible to suppress an increase in friction associated with a decrease in the target engine outlet water temperature Tt, and thus a deterioration in fuel consumption of the engine 1.

  In this embodiment, when the water temperature difference dT between the junction water temperature T3 and the engine outlet water temperature TO is small, the amount of heat received and radiated in each circuit 31 to 35 is small, and conversely, when the water temperature difference dT is large, each circuit The amount of heat received and radiated at 31 to 35 is large. Further, when the junction flow rate V3 is small, the amount of received and radiated heat Qetc in each circuit 31 to 35 is small, and when the junction portion flow rate V3 is large, the amount of received and radiated heat Qetc in each circuit 31 to 35 is large. With this point, in this embodiment, the amount of received and radiated heat Qetc in each of the circuits 31 to 35 is calculated based on the merge portion flow rate V3, the merge portion water temperature T3, and the engine outlet water temperature TO. Therefore, since the merging portion flow rate V3, the merging portion water temperature T3, and the engine outlet water temperature TO as parameters that influence the received and radiated heat quantity Qetc as described above are applied to the calculation, the received and radiated heat quantity Qetc can be accurately calculated. . Therefore, the required radiator flow rate V2 can be calculated with high accuracy, and the flow control valve 16 can be controlled with high accuracy.

  In this embodiment, the merging portion flow rate V3 is calculated based on the valve opening degree ODV and the engine rotational speed NE, which are control amounts of the flow rate control valve 16, and accordingly, according to the cooling water flow rate in the cooling water circulation path such as the radiator passage 12. Thus, the amount of received and radiated heat Qetc is calculated more accurately. As a result, the required radiator flow rate V2 can be calculated more accurately, the command opening degree ODC of the flow control valve 16 can be calculated more accurately, and the flow control valve 16 can be controlled more accurately. Can do. Thereby, the engine outlet water temperature TO can be more suitably converged to the target engine outlet water temperature Tt, and the controllability of the cooling water temperature of the engine 1 can be further improved.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of invention, it can also implement as follows.

  (1) In the embodiment, a plurality of circuits, that is, the throttle body hot water circuit 31, the EGR cooler circuit 32, the hot air intake circuit 33, the heater circuit 34, and the oil cooler circuit 35 are provided as the heat receiving and radiating circuits. On the other hand, all these circuits 31 to 35 may not be used as the heat receiving and radiating circuits, and at least one of the circuits 31 to 35 can be provided as the receiving and radiating circuits. Also in this case, basically, the same effect as that of the above embodiment can be obtained.

  (2) In the above-described embodiment, in a cooling device provided with a plurality of heat receiving / dissipating circuits (all of the circuits 31 to 35), the amount of heat received and radiated heat Qetc in these heat receiving and radiating circuits is calculated, and the amount of received and radiated heat Qetc is calculated as a required radiator. This was reflected in the calculation of the flow rate V2. On the other hand, a cooling device that does not have a heat receiving / dissipating circuit can be embodied in a cooling device that calculates the required radiator flow rate V2 without calculating the amount of heat received and radiated. In this case as well, by calculating the conversion coefficient C used for calculating the required radiator flow rate V2 based on the temperature difference dlthw between the engine outlet water temperature TO and the radiator outlet water temperature T2, the same effects as those of the above embodiment are obtained. be able to.

The schematic block diagram which shows an engine system. The flowchart which shows the content of cooling water temperature control. A map showing the relationship of the conversion coefficient to the temperature difference. The map which shows the relationship between the engine rotation speed and the cooling loss heat quantity with respect to the engine load. The map which shows the relationship of the valve opening degree and the flow volume of a junction part with respect to an engine speed. A map showing the relationship between the required radiator flow rate and the command opening relative to the engine speed. (A), (b) is a time chart which shows the behavior of engine outlet water temperature, radiator outlet water temperature, and vehicle speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 10 ... Cooling device 11 ... Water jacket (cooling water circulation path)
12. Radiator passage (cooling water circulation path)
13 ... Radiator 16 ... Flow rate control valve (flow rate adjusting means)
30 ... ECU (cooling loss calorie calculating means, receiving and radiating calorie calculating means, required radiator flow rate calculating means, control means and conversion coefficient calculating means)
31 ... Throttle body warm water circuit (heat receiving / dissipating circuit)
32 ... EGR cooler circuit (heat receiving / dissipating circuit)
33 ... Hot air intake circuit (heat receiving / dissipating circuit)
34 ... Heater circuit (heat receiving / dissipating circuit)
35 ... Oil cooler circuit (heat receiving / dissipating circuit)
T2 ... Radiator outlet water temperature (cooling water temperature after passing through the radiator)
TO ... Engine outlet water temperature (cooling water temperature after passing through the engine)
T3 ... Junction water temperature (cooling water temperature after passing through the circuit)
QW ... cooling heat loss V3 ... flow rate at the junction (cooling water flow rate after passing through the circuit)
Qetc ... heat received and radiated heat Tt ... target engine outlet water temperature (target cooling water temperature)
C ... Conversion coefficient
dlthw ... temperature difference

Claims (3)

A cooling water circulation path through which engine cooling water circulates; a radiator provided in the cooling water circulation path; and a flow rate adjusting means for adjusting a cooling water flow rate passing through the radiator; An engine cooling apparatus configured to control the flow rate adjusting means so as to have a cooling water temperature,
A cooling loss heat amount calculating means for calculating a cooling loss heat amount taken from the engine to the cooling water based on an operating state of the engine;
In order to set the cooling water temperature of the engine to the target cooling water temperature, the required radiator flow rate of the cooling water required by the radiator has passed through the calculated cooling loss heat quantity, the target cooling water temperature, and the radiator. A required radiator flow rate calculating means for calculating a cooling water temperature after passing through the subsequent radiator and a conversion coefficient for converting the cooling water temperature into a cooling water flow rate;
An engine cooling device comprising: a control means for controlling the flow rate adjusting means based on the calculated required radiator flow rate;
A conversion coefficient calculation means for calculating the conversion coefficient based on a temperature difference between a post-engine coolant temperature after passing through the engine and a post-radiator coolant temperature after passing through the engine is provided. Cooling system. A cooling water circulation path through which engine cooling water circulates, a radiator provided in the cooling water circulation path, a heat receiving / dissipating circuit provided in the cooling water circulation path so as to bypass the radiator, and a cooling water flow rate passing through the radiator. An engine cooling apparatus comprising: a flow rate adjusting means for adjusting; and controlling the flow rate adjusting means such that the engine coolant temperature becomes a target coolant temperature,
A cooling loss heat amount calculating means for calculating a cooling loss heat amount taken from the engine to the cooling water based on an operating state of the engine;
The amount of heat received and radiated and received between the heat receiving and radiating circuit and the cooling water, the cooling water temperature after passing through the engine after passing through the engine, the cooling water temperature after passing through the circuit after passing through the receiving and radiating circuit, and A cooling water flow rate after passing through the circuit, and a heat receiving and radiating heat amount calculating means for calculating based on a conversion coefficient for converting the cooling water temperature into the cooling water flow rate;
In order to set the cooling water temperature of the engine to the target cooling water temperature, the required radiator flow rate of the cooling water required by the radiator is set to the calculated cooling loss heat amount, the calculated heat receiving and radiating heat amount, and the target cooling amount. A required radiator flow rate calculation means for calculating based on the water temperature, the cooling water temperature after passing through the radiator after passing through the radiator, and the conversion coefficient;
An engine cooling device comprising: a control means for controlling the flow rate adjusting means based on the calculated required radiator flow rate;
A cooling apparatus for an engine, comprising: conversion coefficient calculating means for calculating the conversion coefficient based on a temperature difference between the coolant temperature after passing through the engine and the coolant temperature after passing through the radiator. 3. The engine cooling apparatus according to claim 1, wherein the conversion coefficient calculating unit calculates the conversion coefficient so that the conversion coefficient is relatively decreased as the temperature difference is relatively increased. 4.

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