JP2006112332A - Engine cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve controllability of the cooling water temperature in engine transitional operation, in a cooling system for controlling the cooling water temperature on the basis of a request radiator flow rate provided in response to an engine operation state. <P>SOLUTION: An electronic control device ECU calculates a cooling loss calorific value QW taken from an engine 1 on thee basis of an operation state; calculates a feedback correction calorific value Qfb for correcting the cooling water temperature TO to the target cooling water temperature Tt by making a feedback process on the basis of an updated period Pk calculated from the operation state; and calculates the request radiator flow rate V2 on the basis of the cooling loss calorific value QW, the feedback correction calorific value Qfb, the target cooling water temperature Tt and the radiator outlet water temperature T2. The ECU controls a flow control valve on the basis of its request radiator flow rate V2. The ECU performs moderating control on an operation state detecting value used for calculating the updated period Pk for reflecting a calculation delay in the feedback correction calorific value Qfb in calculation of the request radiator flow rate V2 in the engine transitional operation. <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 are water cooling type cooling devices described in Patent Documents 1 and 2 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. Therefore, 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 engine cooling is controlled.

  Here, in the cooling devices of Patent Documents 1 and 2, when the engine operating state changes, the cooling water temperature is set to the target cooling water temperature even if the amount of heat (cooling loss heat amount) taken away from the engine body by the cooling water changes. In order to converge with high responsiveness, the ECU calculates the cooling loss heat quantity based on the engine operating state (engine 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 In particular, in the cooling device of Patent Document 1, in order to make the required radiator flow follow the engine operating state change, the ECU reflects the feedback correction heat amount as a correction term in the calculation of the required radiator flow. In this case, the ECU calculates the update period of the feedback correction heat quantity based on the detected value (instantaneous value) of the engine speed. Then, the ECU controls the flow rate control valve based on the required radiator flow rate corrected by the feedback correction heat quantity. 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-A-2004-84615 (page 6-13, FIGS. 1 to 9) JP 2003-239742 A (page 4, FIGS. 1 to 5)

  However, in the cooling device of Patent Document 1 described above, during the transient operation of the engine (during deceleration operation and acceleration operation), the calculation of the cooling loss heat amount is delayed with respect to the change in engine rotation speed. As described above, when the update period of the feedback correction calorie is calculated based on the detected value (instantaneous value) of the engine speed, there is a possibility that a response delay occurs in the calculation of the feedback correction calorie. For this reason, a delay occurs in the calculation of the required radiator flow rate, and the controllability of the cooling water temperature is deteriorated, which may cause overshoot or undershoot. 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 required radiator flow rate calculated in accordance with 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 cooling loss calorie lost to the cooling water from the engine based on the detected value of the operating state, and a feedback for feedback correcting the engine cooling water temperature to the target cooling water temperature Feedback correction calorie calculation means for calculating the correction calorific value based on the update cycle calculated from the detected value of the operating state, and engine cooling water In order to achieve the target cooling water temperature, the required radiator flow rate of the cooling water required by the radiator, the calculated cooling loss heat amount, the calculated feedback correction heat amount, the target cooling water temperature and the radiator after passing through the radiator A cooling apparatus for an engine comprising: a required radiator flow rate calculating means for calculating based on a coolant temperature after passing; and a control means for controlling the flow rate adjusting means based on the calculated required radiator flow rate. In order to reflect the delay in calculating the feedback correction calorific value in the calculation of the required radiator flow rate during operation, it is provided with a smoothing processing means for smoothing the detected value of the operating state used for calculating the update cycle And

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. A feedback correction heat quantity for feedback correction of the engine coolant temperature to the target coolant temperature is calculated by the feedback correction heat quantity calculation means based on the update period calculated from the detected value of the operating state. Further, in order to set the engine coolant temperature to the target coolant temperature, the required radiator flow rate required by the radiator includes the calculated cooling loss heat amount, the calculated feedback correction heat amount, the target coolant temperature, and the radiator. The required radiator flow rate calculation means is calculated based on the post-passage cooling water temperature. 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, at least during transient operation of the engine (acceleration operation and deceleration operation), the detection of the operation state used to calculate the update period is used to reflect the delay in calculation of the feedback correction calorific value in the calculation of the required radiator flow rate. The value is processed by the processing unit. Therefore, even if the calculation of feedback correction calorific value is delayed at least during transient operation of the engine, the delay is reflected in the calculation of the required radiator flow rate by processing the detected value of the operating state used for calculating the update cycle. The flow rate adjusting means is accurately controlled.

  To achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the feedback correction amount calculating means updates the detected values of the engine speed and the load as the detected values of the operating state. The purpose is to calculate the cycle, and the smoothing processing means smoothes the detected values of the rotational speed and the load used to calculate the update cycle.

  According to the configuration of the above invention, the operation equivalent to that of the invention described in claim 1 can be obtained by specifying the detected value of the operating state used for calculating the update period to the rotational speed and load of the engine.

  According to the first aspect of the present invention, even if the calculation of the feedback correction calorific value is delayed at least during transient operation of the engine, the detected value of the operating state used for calculating the update period is smoothed. This is reflected in the calculation of the required radiator flow rate, and the flow rate adjusting means is accurately controlled, so that 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 detected value of the operating state used for calculating the update cycle is set as the detected value of the engine speed and the load, and the detected value of the engine speed and the load is subjected to an annealing process. Thus, the same effect as that of the first aspect of the invention can be obtained.

  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.

  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 performs the cooling water temperature control, and corresponds to the cooling loss heat amount calculation means, the feedback correction heat amount calculation means, the required radiator flow rate 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. 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. Also in this case, the smoothed engine load factor corresponding to the engine load factor is calculated, and 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 110, the ECU 30 calculates a feedback correction heat quantity Qfb for feedback correction of the coolant temperature (engine outlet water temperature TO) of the engine 1 to the target coolant temperature (target engine outlet water temperature Tt). The details of this calculation will be described in detail according to the flowchart shown in FIG.

  In step 111, the ECU 30 calculates a smoothing 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 112, 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 LEsm calculated as described above are obtained especially during the transient operation of the engine 1 (acceleration operation and deceleration operation) as shown in FIG. The effect of the smoothing process appears remarkably, and the change of each parameter NEsm, LEsm becomes gradual.

  Next, in step 113, the ECU 30 calculates an update cycle Pk for calculating (updating) the feedback correction heat quantity Qfb based on the calculated smoothed engine rotation 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 of the update cycle Pk to the annealing engine speed NEsm and the annealing engine load LEsm. In this map, the relationship of the update cycle Pk to the annealing engine rotational speed NEsm 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 update period Pk decreases as the annealing engine load LEsm increases. The update period Pk is calculated in this way when the response of the coolant temperature to the change in the cooling loss heat quantity QW varies depending on the coolant flow rate, and the feedback correction heat quantity Qfb is always calculated (updated) in the same update period Pk. This is because the update may be performed excessively or the update may be delayed, and the controllability of the cooling water temperature may decrease accordingly. As described above, the update cycle Pk is calculated based on the smoothed engine rotational speed NEsm and the smoothed engine load LEsm. As shown in FIG. (During time and deceleration operation), the effect of the annealing process appears remarkably, and the update period Pk changes gradually.

  Next, in step 114, the ECU 30 determines whether or not the calculated update period Pk has arrived. If the determination result is negative, the ECU 30 proceeds to step 120 as it is. If this determination result is affirmative, the ECU 30 proceeds to step 115.

  In step 115, the ECU 30 determines whether or not an update prohibition condition is satisfied. As one of the update conditions, for example, the engine outlet water temperature TO may be within a certain temperature range including the target engine outlet water temperature Tt. If this determination result is affirmative, in step 116, the ECU 30 calculates a feedback update amount Qfbad for updating the feedback correction heat amount Qfb. This feedback update amount Qfbad is calculated based on the previously calculated required radiator flow rate V2old for a required radiator flow rate V2 to be described later. On the other hand, if the determination result in step 115 is negative, in step 117, the ECU 30 sets the feedback update amount Qfbad to “0”.

  Then, after shifting from step 116 or step 117, in step 118, the ECU 30 calculates a feedback correction heat quantity Qfb. For example, the ECU 30 calculates the current feedback correction heat quantity Qfb by adding the feedback update quantity Qfbad calculated this time to the previously calculated feedback correction heat quantity Qfbold. Thereafter, the ECU 30 proceeds to step 120.

  Thereafter, returning to the flowchart of FIG. 2, in step 120, 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 130, 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 140, the ECU 30 requests the required radiator flow rate 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 feedback correction heat quantity Qfb, and the received and radiated heat quantity Qetc. V2 is calculated. 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−Qfb−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, in step 150, 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 160, 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 feedback correction heat quantity Qfb for performing feedback correction of the engine outlet water temperature TO to the target engine outlet water temperature Tt is based on the detected value of the operating state, that is, the update cycle Pk calculated from the engine rotational speed NE and the engine load LE. Calculated by the ECU 30. 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, the feedback correction heat quantity Qfb, respectively calculated as described above. The ECU 30 calculates the amount of heat received and radiated heat Qetc, 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 this embodiment, as can be seen from the above calculation formula (4), the cooling loss heat quantity QW is corrected by the feedback correction heat quantity Qfb, and the required radiator flow rate V2 is calculated based on the corrected cooling loss heat quantity QW. The responsiveness and convergence can be suitably improved when the engine outlet water temperature TO is brought close to the target engine outlet water temperature Tt.

  In particular, in this embodiment, during the transient operation of the engine 1, that is, during acceleration operation or deceleration operation, in order to reflect the calculation delay of the feedback correction heat quantity Qfb in the calculation of the required radiator flow rate V2, the update period Pk is calculated. The detected values of the operating state to be used, that is, the engine speed NE and the engine load LE are smoothed by the ECU 30, and the smoothed engine speed NEsm and the smoothed engine load LEsm are calculated. Therefore, even if the calculation of the feedback correction heat quantity Qfb is delayed during the acceleration operation or the deceleration operation of the engine 1, the engine rotation speed NE and the engine load LE used for calculating the update period Pk are smoothed. Thus, the flow rate control valve 16 is accurately controlled so as to be reflected in the calculation of the required radiator flow rate V2 and correspond to the actual change in the required radiator flow rate. As a result, in the cooling device that executes the cooling water temperature control based on the required radiator flow rate V2 calculated according to the operating state of the engine 1, the cooling water temperature may overshoot or undershoot during the acceleration operation and the deceleration operation of the engine 1. Shooting can be prevented and controllability of the cooling water temperature can be improved. 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.

  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.

  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. 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 engine speed and the annealing time constant for the engine load. (A) is a time chart which shows changes, such as an engine speed and an engine load, (b) is a time chart which shows the change of an update period. The map which shows the relationship of the update cycle with respect to annealing engine speed and annealing engine load. A map showing the relationship between the required radiator flow rate and the command opening relative to the engine 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 heat amount calculation means, feedback correction heat amount calculation means, required radiator flow rate 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 t1 ... Annealing time constant TO ... Engine outlet water temperature Tt ... Target engine outlet water temperature QW ... Cooling loss heat quantity Qfb ... Feedback correction heat quantity V2 ... Required radiator flow rate

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;
Feedback correction calorie calculation means for calculating feedback correction calorie for feedback correction of the coolant temperature of the engine to the target coolant temperature based on an update period calculated from the detected value of the operating state;
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 feedback correction heat amount, the target cooling amount. A required radiator flow rate calculation means for calculating based on a water temperature and a cooling water temperature after passing through the radiator after passing through the radiator;
An engine cooling device comprising: a control means for controlling the flow rate adjusting means based on the calculated required radiator flow rate;
In order to reflect the calculation delay of the feedback correction calorific value in the calculation of the required radiator flow rate at least during the transient operation of the engine, the detection value of the operation state used for the calculation of the update period is subjected to a smoothing process. A cooling system for an engine characterized by comprising a better treatment means. The feedback correction amount calculating means calculates the update period using the detected value of the engine speed and load as the detected value of the operating state, and the smoothing processing means is the rotation used for calculating the update period. The engine cooling device according to claim 1, wherein the detected values of speed and load are smoothed.

Images