JP2006112233A - Engine cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve controllability of the cooling water temperature in engine transition operation, in a cooling system for controlling the cooling water temperature on the basis of a cooling loss calorific value calculated in response to an operation state of an engine. <P>SOLUTION: An electronic control device ECU 30 controls a flow control valve 16 for setting the engine outlet water temperature TO to the target engine outlet water temperature Tt on the basis of the cooling loss calorific value QW of an engine body 2 calculated from the operation state of the engine 1. Here, ECU 30 sets a moderated engine speed NEsm and a moderated engine load LEsm by performing moderating control on an engine speed NE and an engine load LE used for calculating the cooling loss calorific value QW for reflecting a changing delay in an actual cooling loss calorific value to a change in the calculated cooling loss calorific value QW in control of the flow control valve 16 in the transition operation of the engine 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cooling device that cools an engine by circulating cooling water through a cooling water circulation path including a radiator, and adjusts a cooling water flow rate that passes through the radiator by a flow rate adjusting means to target cooling water temperature. The present invention relates to a cooling device for an engine which is controlled to a water temperature.

  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 operates, the cooling water circulates through the cooling water circulation path, and heat is transferred between the engine body and the cooling water. 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 flow rate control valve so that the actual cooling water temperature becomes the target cooling water temperature, thereby adjusting the cooling water flow rate passing through the radiator and controlling the cooling water temperature in the cooling water circulation path. The degree of cooling of the engine is controlled.

  Here, in the cooling device of Patent Document 1, when the operating state of the engine changes, the cooling water temperature responds to the target cooling water temperature even if the amount of heat (cooling loss heat amount) taken from the engine body by the cooling water changes. In order to converge well, the ECU calculates the cooling loss heat quantity based on the operating state of the engine (engine rotational speed and engine load). In addition, the ECU calculates the cooling water required passage amount (required radiator flow rate) in the radiator for converging the cooling water temperature to the target cooling water temperature, to the cooling loss heat amount, the target cooling water temperature, and the cooling water temperature after passing the radiator. Calculate based on Then, the ECU controls the flow rate control valve based on the calculated required radiator flow rate. 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.

JP 2003-239742 A (page 4, FIGS. 1 to 5)

  However, in the cooling device of Patent Document 1, the cooling loss heat amount used for calculating the required radiator flow rate is calculated at every predetermined calculation timing. This calculation is performed during an engine operation transient (acceleration operation or deceleration operation). ). That is, as shown in FIGS. 11 (a) and 11 (b), during acceleration and deceleration when the engine speed and the engine load change, the actual value of the cooling loss heat quantity is calculated as “acceleration delay time, deceleration It will be delayed by the “delay time”. For this reason, an error occurs between the calculated value of the cooling heat loss and the actual value, an error occurs in the calculation of the required radiator flow rate, and the controllability of the cooling water temperature may be deteriorated. As a result, there is a concern that engine friction reduction, fuel consumption and knocking performance deteriorate.

  The present invention has been made in view of the above circumstances, and an object of the present invention is a cooling device that performs cooling water temperature control based on a cooling loss heat amount calculated according to an operating state of an engine, An object of the present invention is to provide an engine cooling device that can improve the controllability of the coolant temperature during operation.

  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 coolant temperature becomes a target coolant temperature, and detecting an operating state for detecting an operating state of the engine Means, a cooling loss calorie calculating means for calculating the amount of heat lost from the engine to the cooling water based on the detected value of the operating state, and a calculation for calculating the engine cooling water temperature to the target cooling water temperature. And a control means for controlling the flow rate adjusting means based on the amount of heat of cooling loss calculated at least during transient operation of the engine. An annealing process for smoothing the detected value of the operating state used to calculate the cooling loss calorific value in order to reflect the delay in the actual cooling loss calorific value change with the change in the cooling loss calorific value in the control of the flow rate adjustment means. The purpose is to provide means.

According to the configuration of the invention, 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 detected value of the operation state by the operation state detection means. Then, the flow rate adjusting means is controlled by the control means based on the calculated heat loss of cooling loss. Thereby, the engine coolant temperature is brought close to the target coolant temperature.
Here, at least during transient operation of the engine, in order to reflect the delay of the actual change in the cooling loss heat amount with respect to the calculated change in the cooling loss heat amount in the control of the flow rate adjusting means, the operating state used for calculating the cooling loss heat amount The detected value is subjected to an annealing process by the annealing processing means. Therefore, at least during transient operation of the engine, even if the actual change in cooling loss heat is delayed with respect to the calculated change in cooling loss heat, the delay is processed by smoothing the detected value of the operating state. Reflected in the control of the adjusting means, the flow rate adjusting means is accurately controlled.

  In order to achieve the above object, a second aspect of the present invention 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. And a flow rate adjusting means, wherein the flow rate adjusting means is controlled so that the engine cooling water temperature becomes the target cooling water temperature. Cooling loss heat amount calculating means for calculating based on the operating state of the engine, and control means for controlling the flow rate adjusting means based on the calculated cooling loss heat amount so that the engine cooling water temperature becomes the target cooling water temperature. In the engine cooling apparatus comprising: the control means, in order to lower the engine coolant temperature to a predetermined reference temperature during engine deceleration operation, And purpose to control the flow rate adjusting means so that the cooling water flow rate through the mediator will increase gradually.

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. Then, the flow rate adjusting means is controlled by the control means based on the calculated heat loss of cooling loss. Thereby, the engine coolant temperature is brought close to the target coolant temperature.
Here, when the engine is decelerating, the flow rate adjusting means is controlled by the control means so that the flow rate of the cooling water passing through the radiator gradually increases in order to reduce the cooling water temperature of the engine to a predetermined reference temperature. Therefore, during engine deceleration operation, the flow rate adjusting means is controlled so that the flow rate of the cooling water passing through the radiator gradually increases even if the actual change in the cooling loss heat amount is delayed with respect to the calculated change in the cooling loss heat amount. As a result, the calculated change in the cooling loss heat quantity is brought close to the actual change in the cooling loss heat quantity.

  According to the first aspect of the present invention, even if the change in the actual cooling loss heat quantity is delayed at least during the transient operation of the engine with respect to the calculated change in the cooling loss heat quantity, the delay is the detected value of the operating state. Since the annealing process is reflected in the control of the flow rate adjusting means and the flow rate adjusting means is accurately controlled, the controllability of the coolant temperature can be improved during the transient operation of the engine. As a result, engine friction can be reduced and engine fuel efficiency can be improved.

  According to the second aspect of the present invention, the flow rate of the cooling water passing through the radiator gradually increases even when the actual change in the cooling loss heat quantity is delayed with respect to the calculated change in the cooling loss heat quantity during the deceleration operation of the engine. By controlling the flow rate adjusting means, the calculated change in the cooling loss heat amount can be brought close to the actual change in the cooling loss heat amount, so that the controllability of the cooling water temperature can be improved during engine deceleration operation. it can. As a result, engine friction can be reduced and engine fuel efficiency can be improved.

[First Embodiment]
Hereinafter, a first 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.

  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. 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 coolant temperature after passing through the engine.

  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.

  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. These sensors 24 to 27 correspond to the operating state detecting means in the present invention.

  In order to control the degree of cooling of the engine 1 in accordance with the operating state of the engine 1, the cooling device 10 controls the flow rate control valve 16 based on the operating state of the engine 1 to circulate the cooling water circulation flow rate in the cooling water circulation path. Adjust. 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. Further, 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 executes the cooling water temperature control, and corresponds to the cooling loss heat amount calculation means, the control means, and the annealing processing 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 through the input circuit.

  Next, the content of the coolant temperature control executed by the ECU 30 will be described with reference to the flowcharts shown in FIGS. The ECU 30 periodically executes the routine shown in FIG. 2 at predetermined intervals.

  When the process proceeds to this routine, in step 100, the ECU 30 calculates the cooling loss heat quantity QW based on the engine rotational speed NE and the engine load LE obtained from the detected values of the rotational speed sensor 27 and the intake pressure sensor 26. The details of this calculation will be described in detail according to the flowchart shown in FIG.

  In step 101, the ECU 30 calculates a smoothing process time constant t1 based on the engine speed NE and the engine load LE. In this calculation, the ECU 30 refers to function data (map) as shown in FIG. This map predetermines the relationship of the annealing time constant t1 to the engine speed NE and the engine load LE. In this map, the relationship of the annealing time constant t1 to the engine rotational speed NE is relatively large in the low speed region, relatively small in the high speed region, and changes greatly in the medium speed region. In this map, the annealing time constant t1 decreases as the engine load LE increases.

Next, in step 102, the ECU 30 performs an annealing process on the engine speed NE and the engine load LE based on the annealing time constant t1 calculated as described above, so that the engine speed NEsm and the engine speed are smoothed. The load LEsm is calculated. The ECU 30 calculates the smoothed engine rotation speed NEsm and the smoothed engine load LEsm according to the following calculation formulas (1) and (2).
NEsm = {(NEsmold−NE) / t1} + NEsmold (1)
LEsm = {(LEsmold−LE) / t1} + LEsmold (2)
Here, “NEsmold” means the annealing engine speed NEsm calculated last time. “LEsmold” means the previously calculated annealing engine load LEsm. In this calculation, the change in the annealing engine speed NEsm and the annealing engine load LEsm decreases as the annealing time constant t1 increases, and increases as the annealing time constant t1 decreases. The smoothed engine rotational speed NEsm and the smoothed engine load NEsm calculated as described above are shown in FIG. 5, particularly during the transient operation of the engine 1 (acceleration operation and deceleration operation). The effect appears remarkably, and the change of each parameter NEsm, LEsm becomes gradual.

  Next, in step 103, the ECU 30 calculates a cooling loss heat quantity QW based on the calculated smoothed engine rotational speed NEsm and the smoothed engine load LEsm. In this calculation, the ECU 30 refers to function data (map) as shown in FIG. This map predetermines the relationship between the cooling engine heat speed NEsm and the cooling loss heat quantity QW with respect to the annealing engine load LEsm. 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 annealing engine speed NEsm is low, and increases as the annealing engine speed NEsm 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. Further, in this map, the cooling loss heat quantity QW is small when the annealing engine load LEsm is small, and increases as the annealing engine load LEsm increases. However, in the region where the annealing engine speed NEsm is high, the degree of increase in the cooling loss heat quantity QW becomes moderate as the annealing engine load LEsm 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. Also in this case, the smoothed engine load factor corresponding to the engine load factor is calculated, and a map according to FIG. 6 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.

  Then, returning to the flowchart of FIG. 2, in step 110, the ECU 30 calculates the 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 120, 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, and the engine outlet water temperature TO. The ECU 30 calculates the amount of received and radiated heat Qetc (the total sum of the amounts of received and radiated heat in each of the circuits 31 to 35) according to the following calculation formula (3). In the following calculation formula (3), “C” is a coefficient for converting the temperature into the flow rate, and is determined, for example, by the product of the specific heat of the cooling water and the density.
Qetc = C · V3 · (TOold−T3) (3)

Next, in step 130, the ECU 30 calculates 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, and the received and radiated heat quantity Qetc. The ECU 30 calculates the flow rate V2 according to the following calculation formula (4). In the following calculation formula (4), “C” means the same coefficient as described above.
V2 = (QW−Qetc) / {C · (Tt−T2)} (4)
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, at step 140, 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 150, 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. In addition, the amount of received and radiated heat Qetc received and received between the receiving and radiating circuit (each circuit 31 to 35) and the cooling water is calculated by the ECU 30 based on the engine outlet water temperature TO, the merging portion water temperature T3, and the merging portion flow rate V3. The 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 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.

  Here, 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 conventional technique in which 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, when the target engine outlet water temperature Tt is lowered, the engine outlet water temperature TO is lowered, so that friction may increase in the engine 1 or the automatic transmission, resulting in deterioration of fuel consumption.

  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 between the merging portion water temperature T3 and the engine outlet water temperature TO is small, the amount of received and radiated heat Qetc in each circuit 31 to 35 is small, and conversely, when the water temperature difference is large, each circuit 31 to The amount of heat received and radiated at Q35 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 respect to 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 merging portion flow rate V3, the merging 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 particular, in this embodiment, during the transient operation of the engine 1, that is, during the acceleration operation and the deceleration operation, the flow control valve 16 indicates the delay in the actual cooling loss heat amount with respect to the cooling loss heat amount QW calculated by the ECU 30. In order to reflect this in the control, the detected value of the operating state used for calculating the cooling loss heat quantity QW, that is, the engine rotational speed NE and the engine load LE are subjected to a smoothing process by the ECU 30, and the smoothed engine rotational speed NEsm and An annealing engine load LEsm is calculated. Therefore, even if the actual change in the cooling loss heat amount is delayed with respect to the calculated change in the cooling loss heat amount QW during the acceleration operation and the deceleration operation of the engine 1, the delay is caused by the engine rotation speed NE and the engine load LE. The detected value is reflected in the control of the flow rate control valve 16 so that the flow rate control valve 16 is accurately controlled in accordance with the actual cooling loss heat amount delay. As a result, in the cooling device that executes the cooling water temperature control based on the cooling heat loss QW calculated according to the operating state of the engine 1, the controllability of the cooling water temperature is improved during the acceleration operation and the deceleration operation of the engine 1. Can be made. As a result, the friction of the engine 1 can be reduced, and the fuel efficiency of the engine 1 can be improved.

  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.

[Second Embodiment]
Next, a second embodiment of the engine cooling device according to the present invention will be described in detail with reference to the drawings.

  In each embodiment described below, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described below. In this embodiment, the ECU 30 executes cooling water temperature control, and corresponds to the cooling loss heat amount calculation means and the control means in the present invention.

  In this embodiment, the configuration is different from that of the first embodiment in terms of the processing content of the cooling water temperature control. The processing contents are shown in the flowcharts of FIGS. In this embodiment, the processing contents of steps 200 and 250 in the flowchart of FIG. 9 are different from the processing contents of steps 100 and 150 in the flowchart of FIG. 2 of the first embodiment.

  That is, in step 200, the ECU 30 calculates the cooling loss heat quantity QW based on the engine rotational speed NE and the engine load LE without performing the smoothing process on the engine rotational speed NE and the engine load LE, respectively.

  Thereafter, the ECU 30 executes the processing of steps 110 to 140, and drives and controls the flow rate control valve 16 based on the calculated command opening degree ODC in step 250. The contents of this control will be described in detail according to the flowchart shown in FIG.

  In step 251, the ECU 30 determines whether or not the engine 1 is decelerating. The ECU 30 makes this determination based on the accelerator opening ACCP obtained from the detection value of the accelerator sensor 24. If this determination result is negative, that is, if the vehicle is not decelerating, in step 258, the ECU 30 drives and controls the flow control valve 16 based on the command opening degree ODC calculated this time. 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.

  On the other hand, if the determination result in step 251 is affirmative, the ECU 30 turns on a deceleration flag XFDS indicating that the vehicle is decelerating in step 252.

  Next, in step 253, the ECU 30 determines whether or not the idle determination flag XFID is on. The ECU 30 makes this determination based on the throttle opening degree TA obtained from the detection value of the throttle sensor 25. If the determination result is affirmative, the ECU 30 sets the opening degree increase timer TOD to ON in step 254, assuming that the throttle valve 8 is in a deceleration operation in which the throttle valve 8 is fully closed. The timer TOD counts the time for gradually increasing the opening degree of the flow control valve 16 as will be described later.

  Thereafter, in step 255, the ECU 30 determines whether the engine outlet water temperature TO is “88 ° C.” or less, or whether the opening degree increase timer TOD has been counted up. This count-up time is about 2 seconds. If this determination result is negative, the ECU 30 increases the command opening degree ODC by a predetermined change amount α in step 256.

  In step 258, the ECU 30 drives and controls the flow control valve 16 based on the command opening degree ODC set in step 256. That is, in this embodiment, the ECU 30 reduces the coolant temperature of the engine 1 to “88 ° C.” as a predetermined reference temperature during the deceleration operation of the engine 1 in which the throttle valve 8 is fully closed. The opening degree of the flow control valve 16 is gradually increased so that the flow rate of the cooling water passing through the valve gradually increases.

  On the other hand, if the determination result in step 253 is negative, the ECU 30 turns off the opening degree increase timer TOD and sets the deceleration flag XFDS in step 257 on the assumption that the throttle valve 8 is not in the fully-decelerated driving. Turn off and proceed to step 258.

  If the determination result in step 255 is affirmative, it is assumed that the cooling water temperature has dropped to the reference temperature “88 ° C.” during the deceleration operation of the engine 1, and the opening degree increase timer TOD is turned off in the same manner as described above. At the same time, the deceleration flag XFDS is turned off, and the process proceeds to step 258.

  Therefore, in this embodiment, during the deceleration operation of the engine 1, the cooling water flow rate passing through the radiator 13 is gradually increased in order to reduce the cooling water temperature of the engine 1 to “88 ° C.” which is a predetermined reference temperature. Further, the opening degree of the flow control valve 16 is controlled by the ECU 30 so as to gradually increase. Therefore, when the engine 1 is decelerated, the flow rate control is performed so that the flow rate of the cooling water passing through the radiator 13 gradually increases even if the actual change in the cooling loss heat amount is delayed with respect to the calculated change in the cooling loss heat amount QW. By controlling the valve 16, the calculated change in the cooling loss heat quantity QW is brought close to the actual change in the cooling loss heat quantity. As a result, in the cooling device that executes the cooling water temperature control based on the cooling heat loss QW calculated according to the operating state of the engine 1, the controllability of the cooling water temperature can be improved during the deceleration operation of the engine 1. . As a result, the friction of the engine 1 can be reduced, and the fuel efficiency of the engine 1 can be improved.

  Other functions and effects obtained in this embodiment are the same as those in the first embodiment.

  The present invention is not limited to the above-described embodiments, and can be carried out as follows without departing from the spirit of the invention.

  For example, in each of the above embodiments, 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 first embodiment can be obtained.

The schematic block diagram which shows an engine system. The flowchart which shows the content of cooling water temperature control. The flowchart which shows a part of content of cooling water temperature control in detail. A map showing the relationship between the engine speed and the annealing time constant for the engine load. The time chart which shows changes, such as engine speed and engine load. The map which shows the relationship of the amount of cooling loss heat with respect to annealing engine speed and annealing 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. The flowchart which shows the content of cooling water temperature control. The flowchart which shows a part of content of cooling water temperature control in detail. (A) is a time chart which shows the change of an engine speed and an engine load, (b) is a time chart which compares the calculated value of a cooling loss calorie | heat amount, and the change of an actual value.

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 heat amount calculation means, control means, annealing processing means)
24 ... Accelerator sensor (operating state detection means)
25. Throttle sensor (operating state detection means)
26 ... Intake pressure sensor (operating state detection means)
27: Rotational speed sensor (operating state detection means)
NE ... Engine rotation speed NEsm ... Annealing engine rotation speed LE ... Engine load LEsm ... Annealing engine load TO ... Engine outlet water temperature Tt ... Target engine outlet water temperature QW ... Cooling loss heat amount t1 ... Annealing time constant

Claims (2)

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,
An operating state detecting means for detecting the operating state of the engine;
Cooling loss heat amount calculating means for calculating the cooling loss heat amount taken from the engine to the cooling water based on the detected value of the operating state;
In the engine cooling apparatus, comprising: a control means for controlling the flow rate adjusting means based on the calculated amount of heat of cooling loss in order to set the engine coolant temperature to the target coolant temperature.
At least during the transient operation of the engine, in order to reflect the delay in the actual cooling loss heat amount change with respect to the calculated cooling loss heat amount change in the control of the flow rate adjusting means, the cooling loss heat amount is used. An engine cooling apparatus comprising an annealing processing means for smoothing a detected value of an operating state. 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 the engine cooling apparatus, comprising: a control means for controlling the flow rate adjusting means based on the calculated amount of heat of cooling loss in order to set the engine coolant temperature to the target coolant temperature.
The control means controls the flow rate adjusting means so that the flow rate of cooling water passing through the radiator gradually increases in order to reduce the cooling water temperature of the engine to a predetermined reference temperature during the deceleration operation of the engine. An engine cooling system characterized by that.

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