Engine control unit

Abstract

Suppresses deterioration of combustion conditions due to water temperature drop. [Solution] The electronic control unit 32 includes a calculation processing unit 33 that calculates the engine operation amount, and a storage device 34 that stores a normal map and a transition map as maps that take the outlet water temperature as input and output values ​​used to calculate the engine operation amount. After the flow of water to the first heating water channel 16 equipped with the heater core 23 or the second heating water channel 17 equipped with the water-water heat exchanger 26 is started by the switching valve 18, the calculation processing unit 33 calculates the engine operation amount using the transition map during the transition period when the difference between the outlet water temperature and the heater inlet water temperature is greater than or equal to the transition determination value, and using the normal map during other periods. The normal map and the transition map are configured such that when the same value is output, the outlet water temperature in the transition map is lower than that in the normal map.

Description

[Technical Field]

[0001] The present invention relates to an engine control device. [Background Art]

[0002] Some on-vehicle engines are provided with an engine coolant circulation circuit configured such that after engine coolant, which has recovered heat by passing through the interior of the engine, is cooled by a radiator, the coolant is returned to the interior of the engine. A thermostat is provided in the engine coolant circulation circuit. The thermostat is configured to stop water flow to the radiator by closing a valve while the engine is cold, and start water flow to the radiator by opening the valve when the engine warms up.

[0003] Further, as disclosed in Patent Document 1, there is also known an engine configured to use heat recovered from the engine by engine coolant for heating a vehicle compartment and raising a temperature of a battery. A heater core, a water-water heat exchanger, and a switching valve are provided in a cooling system of this engine. The heater core is a heat exchanger configured to perform heat exchange between air blown into the vehicle compartment and the engine coolant. The water-water heat exchanger is a heat exchanger configured to perform heat exchange between battery coolant circulated through the interior of the battery and the engine coolant. The switching valve is a valve that switches between a state where passage of engine coolant to the heater core and the water-water heat exchanger is prohibited and a state where the passage is permitted. [Prior Art Document] [Patent Document]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2024-113860 [Summary of Invention] [Problem to be Solved by the Invention]

[0005] Incidentally, in engines used in vehicles, during warm-up, engine control parameters such as fuel injection amount and ignition timing are adjusted according to the engine coolant temperature. When water is started flowing to the heater core or water-water heat exchanger during warm-up, the cold engine coolant that had been stagnant in the heater core or water-water heat exchanger flows into the engine. As a result, the engine coolant temperature may temporarily drop, a phenomenon known as a water temperature drop. When engine control parameters during warm-up are adjusted according to the engine coolant temperature, a water temperature drop can cause the values ​​of these parameters to change inappropriately. This can potentially lead to a deterioration in the engine's combustion state. [Means for solving the problem]

[0006] The engine control device for solving the above problems is a device for controlling an engine whose cooling system is equipped with a radiator water channel that passes through a radiator, a heating water channel equipped with a heating heat exchanger for heating other fluids with the heat of the engine coolant, and a bypass water channel that allows the engine coolant to flow around the radiator and the heating heat exchanger, all arranged in parallel as a flow path for engine coolant to return from the outlet to the inlet of the water jacket, and a thermostat that opens and closes the radiator water channel, and a switching valve that switches between a state in which the inflow of engine coolant from the heating water channel to the water jacket is prohibited and a state in which it is permitted, and comprises a calculation processing unit and a memory device. The memory device stores a normal state map and a transition state map as maps that take the outlet water temperature, which is the temperature of the engine coolant flowing out of the water jacket, as input and output values ​​used for calculating engine operation amounts. The processing unit is configured to calculate the engine operation amount using the transition map during the transition period, from when the switching valve switches the flow of engine coolant from the heating water channel to the water jacket from a prohibited state to when it allows it, until the difference between the temperature of the engine coolant flowing out of the heating heat exchanger and the outlet water temperature decreases to below a predetermined value. During periods other than the transition period, it calculates the engine operation amount using the normal state map. The normal state map and the transition state map are configured such that when they output the same value, the outlet water temperature is lower in the transition state map than in the normal state map map. [Effects of the Invention]

[0007] The above-mentioned engine control device has the effect of suppressing the deterioration of combustion conditions due to a drop in water temperature. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing the configuration of one embodiment of an engine control device. [Figure 2]Figure 2 is a flowchart of the engine control amount calculation process performed in the engine control device shown in Figure 1. [Figure 3] Figure 3 is a graph showing the relationship between outlet water temperature and the warm-up fuel enrichment correction coefficient in both the normal operation map and the transition map. [Figure 4] Figure 4 is a graph showing the relationship between outlet water temperature and target EGR rate in both the normal operation map and the transition map. [Figure 5] In the engine control device shown in Figure 1, Figure 5(A) is a time chart showing the transition of the opening and closing state of the heating water passage, Figure 5(B) is a time chart showing the transition of the outlet water temperature and heater inlet water temperature, Figure 5(C) is a time chart showing the transition of the warm-up enrichment correction coefficient, and Figure 5(D) is a time chart showing the transition of the target EGR rate. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the engine control device will be described in detail with reference to Figures 1 to 5. <Configuration of Engine 10 and its Cooling System> First, with reference to Figure 1, the configuration of the engine 10 and its cooling system to which the engine control device of this embodiment is applied will be described. The engine 10 is installed in a hybrid vehicle. In Figure 1, the flow directions of the engine coolant and battery coolant in the engine 10's cooling system are indicated by arrows.

[0010] The engine 10 is equipped with various actuators. The operating state of the engine 10 is controlled through the operation of these actuators. Examples of actuators include an injector 10A that injects fuel to be burned in the engine 10, an ignition device 10B that ignites the fuel by spark discharge, and an exhaust recirculation valve 10C that adjusts the amount of exhaust gas recirculated from the engine 10's exhaust system to the intake system.

[0011] The engine 10 is equipped with a cooling system that cools the engine by circulating engine coolant through a water jacket 11 located inside it. During operation of the engine 10, engine coolant flows through the water jacket 11 from the inlet 12 to the outlet 13 shown in the figure. The cooling system of the engine 10 is equipped with an engine water pump 20 that pressurizes and pumps engine coolant towards the inlet 12 of the water jacket 11. In this embodiment, an electric pump is used for the engine water pump 20. The cooling system of the engine 10 is equipped with four parallel water channels: a bypass water channel 14, a radiator water channel 15, a first heating water channel 16, and a second heating water channel 17, which serve as the flow paths for engine coolant returning from the outlet 13 to the inlet 12 of the water jacket 11. Each water channel (14 to 17) has a portion that is shared with one another.

[0012] The bypass water channel 14 is configured to return to the inlet 12 of the water jacket 11, passing sequentially from the outlet 13 of the water jacket 11 through the thermostat 19 and the engine water pump 20. The radiator water channel 15 is configured to return to the inlet 12 of the water jacket 11, passing sequentially from the outlet 13 of the water jacket 11 through the radiator 21, the reservoir tank 22, the thermostat 19 and the engine water pump 20. The radiator 21 is a heat exchanger for cooling the engine coolant by heat exchange with the outside air. The reservoir tank 22 is a storage container for the engine coolant. The thermostat 19 opens and closes the radiator water channel 15 according to the temperature of the incoming engine coolant. Specifically, the thermostat 19 is configured to close the radiator water channel 15 when the engine coolant temperature is below the set temperature, and to open the radiator water channel 15 when the engine coolant temperature is above the set temperature. In this context, the state where the radiator water passage 15 is open indicates that engine coolant is flowing through the radiator water passage 15. Conversely, the state where the radiator water passage 15 is closed indicates that the flow of engine coolant through the radiator water passage 15 is blocked.

[0013] The first heating water channel 16 is configured to return to the inlet 12 of the water jacket 11, passing sequentially from the outlet 13 of the water jacket 11 through the switching valve 18, heater core 23, heater water pump 24, electric heater 25, and engine water pump 20. The switching valve 18 is a valve for changing the flow rate distribution of engine coolant in each water channel, and its details will be described later. The heater core 23 is a heat exchanger that exchanges heat between the air blown into the passenger compartment and the engine coolant, and is used to warm the air blown in with the heat of the engine coolant when heating the passenger compartment. The heater water pump 24 is an electrically operated pump. The electric heater 25 generates heat in response to the power supply and heats the engine coolant.

[0014] The second heating water channel 17 is configured to return to the inlet 12 of the water jacket 11, passing sequentially from the outlet 13 of the water jacket 11 through the switching valve 18, water-water heat exchanger 26, heater water pump 24, electric heater 25, and engine water pump 20. The water-water heat exchanger 26 is a heat exchanger that performs heat exchange between the battery coolant and the engine coolant. The battery coolant is the coolant that circulates through the battery water channel 28 and is used to regulate the temperature of the battery 27. The water-water heat exchanger 26 is used to warm the battery coolant with the heat of the engine coolant when the battery 27 is heated. In this embodiment, the heater core 23 and the water-water heat exchanger 26 each correspond to heating heat exchangers that use the heat of the engine coolant to heat other fluids. Furthermore, in this embodiment, the bypass waterway 14 is configured as a waterway that allows engine coolant to flow, bypassing the radiator 21 and the heat exchanger for heating (heater core 23, water-water heat exchanger 26).

[0015] The aforementioned switching valve 18 distributes the flow rate of engine coolant from the outlet 13 of the water jacket 11 to the first heating water channel 16 and the second heating water channel 17. This switching valve 18 forms the following four states (A1) to (A4). State (A1) is a state in which the flow of engine coolant from the outlet 13 of the water jacket 11 to both the first heating water channel 16 and the second heating water channel 17 is blocked. State (A2) is a state in which engine coolant flows from the outlet 13 of the water jacket 11 to only the first heating water channel 16 of the two heating water channels 17. State (A3) is a state in which engine coolant flows from the outlet 13 of the water jacket 11 to only the second heating water channel 17 of the two heating water channels 16 and 17. Condition (A4) is a state in which engine coolant flows from the outlet 13 of the water jacket 11 to both the first heating water passage 16 and the second heating water passage 17.

[0016] Furthermore, the cooling system of the engine 10 is equipped with an outlet water temperature sensor 30 and a heater inlet water temperature sensor 31. The outlet water temperature sensor 30 is a sensor that detects the outlet water temperature THW1, which is the temperature of the engine coolant flowing out from the outlet 13 of the water jacket 11. The heater inlet water temperature sensor 31 is a sensor that detects the heater inlet water temperature THW2, which is the temperature of the engine coolant flowing in the portion of the first heating channel 16 and the second heating channel 17 that is downstream of the heater water pump 24 and upstream of the electric heater 25. When engine coolant is flowing in the first heating channel 16 and the second heating channel 17, the heater inlet water temperature THW2 corresponds to the temperature of the engine coolant flowing out from the heater core 23 and the water-water heat exchanger 26.

[0017] Furthermore, the cooling system of the engine 10 is provided with a return water channel 29, which is a water channel connecting the portions of the first heating water channel 16 and the second heating water channel 17 downstream of the electric heater 25 to the switching valve 18. Even in the above state (A1), the switching valve 18 connects the return water channel 29 to at least one of the first heating water channel 16 and the second heating water channel 17, allowing engine coolant to flow through the first heating water channel 16 and the second heating water channel 17. In this state, by operating the heater water pump 24 and the electric heater 25, it is possible to heat the passenger compartment and raise the temperature of the battery 27 even when the engine 10 is stopped. The engine control device of this embodiment is configured to circulate engine coolant through the return water channel 29 to the first heating water channel 16 or the second heating water channel 17 when heating the passenger compartment or raising the temperature of the battery 27 is required during electric driving of the hybrid vehicle.

[0018] <Engine control system configuration> Next, the configuration of the engine control device of the present embodiment will be described with reference to FIG. 1. The engine control device of the present embodiment includes an electronic control unit 32. The electronic control unit 32 includes an arithmetic processing unit 33 and a storage device 34. Programs and data for engine control are stored in advance in the storage device 34. The electronic control unit 32 is configured to execute various processes for engine control when the arithmetic processing unit 33 reads a program from the storage device 34 and executes the program. Detection signals X1 and X2 from an outlet water temperature sensor 30 and a heater inlet water temperature sensor 31 are input to the electronic control unit 32. In addition, detection signals from sensors provided in various parts of the hybrid vehicle are also input to the electronic control unit 32. Examples of the detection signals include a detection signal X3 from an air flow meter 35, a detection signal X4 from an intake air temperature sensor 36, a detection signal X5 from a vehicle speed sensor 37, a detection signal X13 from an accelerator pedal sensor 38, and a detection signal X14 from a crank angle sensor 39. The air flow meter 35 is a sensor that detects an intake air amount GA of the engine 10. The intake air temperature sensor 36 is a sensor that detects an intake air temperature THA of the engine 10. The vehicle speed sensor 37 is a sensor that detects a vehicle speed SPD of the hybrid vehicle. The accelerator pedal sensor 38 is a sensor that detects an accelerator pedal depression amount ACC by a driver of the hybrid vehicle. The crank angle sensor 39 is a sensor that detects a crank angle, which is the rotation angle of a crank shaft that is the output shaft of the engine 10. Note that the arithmetic processing unit 33 calculates an engine rotation speed NE, which is the rotation speed of the crank shaft, based on the detection signal X14 from the crank angle sensor 39. Further, the arithmetic processing unit 33 calculates an engine load factor KL based on the engine rotation speed NE, the detection signal X3 from the air flow meter 35, and the like. The engine load factor KL represents a charging rate of intake air in a combustion chamber of the engine 10.

[0019] <Engine Operation Amount Calculation Process> The arithmetic processing unit 33 calculates the operation amount of the engine 10 based on the detection results of each sensor. Examples of the operation amount of the engine 10 calculated by the arithmetic processing unit 33 include the fuel injection amount of the injector 10A, the fuel ignition timing by the ignition device 10B, and the EGR opening degree which is the opening ratio of the exhaust gas recirculation valve 10C. The arithmetic processing unit 33 also calculates operation amounts for the cooling system such as the switching valve 18, the engine water pump 20, the heater water pump 24, and the electric heater 25. Then, the arithmetic processing unit 33 outputs command signals X6 to X12 corresponding to the operation amounts to the injector 10A, the ignition device 10B, the exhaust gas recirculation valve 10C, the switching valve 18, the engine water pump 20, the heater water pump 24, and the electric heater 25. Thereby, the electronic control unit 32 controls the engine 10 and the cooling system thereof.

[0020] FIG. 2 shows a flowchart of a process executed by the arithmetic processing unit 33 for calculating an engine operation amount. The arithmetic processing unit 33 repeatedly executes the process shown in FIG. 2 at every predetermined control cycle during operation of the engine 10. Note that "S" attached before reference signs in the figure represents a step.

[0021] When the process of FIG. 2 is started, the arithmetic processing unit 33 first acquires, in step 100, an engine rotational speed NE, an engine load factor KL, an accelerator pedal depression amount ACC, an outlet water temperature THW1, and a heater inlet water temperature THW2. Subsequently, in step 102, the arithmetic processing unit 33 subtracts the heater inlet water temperature THW2 from the outlet water temperature THW1, and calculates the subtracted value as the value of the water temperature difference ΔT.

[0022] Next, in step 104, the arithmetic processing unit 33 determines whether or not it is during a transition period. Then, if it is determined that the process is during the transition period (YES), the arithmetic processing unit 33 advances the process to step 106, and if it is determined that the process is not during the transition period (NO), the arithmetic processing unit 33 advances the process to step 112, respectively. As will be described later, in the present process, the arithmetic processing unit 33 determines the start and end of the transition period, and the period from when it is determined that the transition period has started to when it is determined that the transition period has ended is the transition period.

[0023] If the process proceeds to step 112, the arithmetic processing unit 33 determines whether or not water has started flowing through the heater core 23 or the water-water heat exchanger 26. Specifically, the arithmetic processing unit 33 determines that the switch from the following state (A1) to state (A2) is the start of water flowing through the heater core 23 or the water-water heat exchanger 26. State (A1) is a state in which the inflow of engine coolant into the water jacket 11 from both the first heating water channel 16 and the second heating water channel 17 is prohibited. State (A2) is a state in which the inflow of engine coolant into the water jacket 11 from at least one of the first heating water channel 16 and the second heating water channel 17 is permitted. The switch from state (A1) to state (A2) is performed by the switching valve 18. In this embodiment, the arithmetic processing unit 33 makes the determination in step 112 based on the operation amount commanded to the switching valve 18.

[0024] If the arithmetic processing unit 33 determines that water has not started flowing through the heater core 23 or the water-water heat exchanger 26 (NO), it proceeds to step 110. In step 110, the arithmetic processing unit 33 calculates the engine operation amount using the normal operation map pre-stored in the memory device 34, and then terminates the processing shown in Figure 2 for the current control cycle.

[0025] On the other hand, if the arithmetic processing unit 33 determines in step 112 that water has started flowing through the heater core 23 or the water-water heat exchanger 26 (YES), then in step 114, it determines whether the water temperature difference ΔT is greater than or equal to a predetermined transition determination value. If the arithmetic processing unit 33 determines that the water temperature difference ΔT is less than the transition determination value (NO), it proceeds to step 110 described above. On the other hand, if the arithmetic processing unit 33 determines that the water temperature difference ΔT is greater than or equal to the transition determination value (YES), then in step 118, it determines that the transition period has started. Then, in step 120, the arithmetic processing unit 33 calculates the engine operation amount using the transition time map pre-stored in the memory device 34, and then terminates the processing shown in Figure 2 for the current control cycle.

[0026] Furthermore, if the arithmetic processing unit 33 determines in step 104 that it is in the transition period and proceeds to step 106, it determines in step 106 whether the water temperature difference ΔT is less than the transition determination value. If the arithmetic processing unit 33 determines that the water temperature difference ΔT is less than the transition determination value (YES), it proceeds to step 108; if it determines that the water temperature difference ΔT is greater than or equal to the transition determination value (NO), it proceeds to step 120 as described above. If the arithmetic processing unit 33 proceeds to step 108, it determines in step 108 that the transition period has ended, and then proceeds to step 110 as described above.

[0027] In the judgment value setting process described above, the arithmetic processing unit 33 determines that the transition period is the period during which, after switching from state (A1) to state (A2) via the switching valve 18, the water temperature difference ΔT, i.e., the difference between the outlet water temperature THW1 and the heater inlet water temperature THW2, is greater than or equal to the transition judgment value. The arithmetic processing unit 33 then calculates the engine operation amount using the transition map during the transition period and the normal map during periods other than the transition period.

[0028] <Specific examples of engine control calculations> Next, we will explain a specific example of how the engine control amount is calculated in steps 110 and 120 of Figure 2.

[0029] First, the calculation method for the fuel injection amount will be explained. When calculating the fuel injection amount, the arithmetic processing unit 33 first calculates the basic injection amount based on the engine rotational speed NE, engine load ratio KL, etc. Next, the arithmetic processing unit 33 calculates various correction coefficients. These correction coefficients include a warm-up enrichment correction coefficient calculated based on the outlet water temperature THW1. The arithmetic processing unit 33 multiplies each calculated correction coefficient by the basic injection amount and calculates the final fuel injection amount value from the multiplied value. The storage device 34 stores two maps for calculating the warm-up enrichment correction coefficient: a normal map and a transition map. The arithmetic processing unit 33 uses the transition map during the transition period and the normal map during other periods to calculate the warm-up enrichment correction coefficient. The normal map and transition map for calculating the warm-up enrichment correction coefficient are configured to output the warm-up enrichment correction coefficient in response to the input of the outlet water temperature THW1.

[0030] Figure 3 shows the relationship between the outlet water temperature THW1 and the warm-up fuel enrichment correction coefficient in both the normal operation map and the transition map. In both the normal operation map and the transition map, the value of the warm-up fuel enrichment correction coefficient is set to "1" when the outlet water temperature THW1 is above a predetermined value. When the outlet water temperature THW1 is below the predetermined value, the value of the warm-up fuel enrichment correction coefficient is set to increase as the outlet water temperature THW1 decreases. However, the value of the warm-up fuel enrichment correction coefficient in the transition map when the outlet water temperature THW1 is below the predetermined value is set to a smaller value than the value of the warm-up fuel enrichment correction coefficient in the normal operation map for the same outlet water temperature THW1. In other words, the normal operation map and the transition map used to calculate the warm-up fuel enrichment correction coefficient are configured such that when the same value is output, the outlet water temperature THW1 is lower in the transition map than in the normal operation map.

[0031] Next, the calculation method for the EGR opening degree will be explained. When calculating the EGR opening degree, the arithmetic processing unit 33 first calculates the target EGR rate, which is the control target value for the EGR rate, based on the engine rotational speed NE, engine load ratio KL, and outlet water temperature THW1. The EGR rate represents the ratio of recirculated exhaust to the intake air introduced into the combustion chamber of the engine 10. The arithmetic processing unit 33 then calculates the opening ratio of the exhaust recirculation valve 10C required to recirculate an amount of exhaust according to the target EGR rate as the EGR opening degree. The storage device 34 stores two maps for calculating the target EGR rate: a normal map and a transition map. The arithmetic processing unit 33 uses the transition map during the transition period and the normal map during other periods to calculate the target EGR rate. The normal map and transition map for calculating the target EGR rate are configured to output the target EGR rate in response to the inputs of engine rotational speed NE, engine load ratio KL, and outlet water temperature THW1.

[0032] Figure 4 shows the relationship between outlet water temperature THW1 and the target EGR rate under conditions where engine rotational speed NE and engine load ratio KL are constant, for both the normal operation map and the transition map. In both the normal operation map and the transition map, the target EGR rate is set to "0" in the low water temperature range where the outlet water temperature THW1 is below a certain value. Also, in the high water temperature range where the outlet water temperature THW1 is above a certain value, a constant value is set as the target EGR rate. Furthermore, in the water temperature range between the low and high water temperature ranges, the target EGR rate is set to increase from the value in the low water temperature range ("0") to the value in the high water temperature range as the outlet water temperature THW1 increases. However, the target EGR rate value in the transition map for the intermediate water temperature range is set to a larger value than the target EGR rate value in the normal operation map for the same outlet water temperature THW1. The normal operation map and the transition map used to calculate the target EGR rate are also configured such that the outlet water temperature THW1 when outputting the same value is lower in the transition map than in the normal operation map.

[0033] Next, the calculation method for ignition timing will be explained. When calculating ignition timing, the arithmetic processing unit 33 first calculates the basic ignition timing based on the engine rotational speed NE, engine load ratio KL, etc. Then, the arithmetic processing unit 33 calculates various ignition timing correction amounts and calculates the value of the ignition timing by correcting the basic ignition timing with the calculated correction amounts. The ignition timing correction amounts include a warm-up advance angle correction amount calculated based on the outlet water temperature THW1. The warm-up advance angle correction amount is set as a value that corrects the ignition timing to the advance side. The storage device 34 stores two maps for calculating the warm-up advance angle correction amount: a normal map and a transition map. The arithmetic processing unit 33 uses the transition map during the transition period and the normal map during other periods to calculate the warm-up advance angle correction amount. The normal map and the transition map for calculating the warm-up advance angle correction amount are configured to output the warm-up advance angle correction amount in response to the input of the outlet water temperature THW1. In both the normal mode map and the transition mode map, the value of the warm-up ignition timing correction amount is set to "0" when the outlet water temperature THW1 is above a predetermined value. When the outlet water temperature THW1 is below the predetermined value, the value of the warm-up ignition timing correction amount is set to increase as the outlet water temperature THW1 decreases. However, the value of the warm-up ignition timing correction amount in the transition mode map when the outlet water temperature THW1 is below the predetermined value is set to a smaller value than the value in the normal mode map for the same outlet water temperature THW1. In this way, both the normal mode map and the transition mode map used to calculate the warm-up ignition timing correction amount are configured such that when the same value is output, the outlet water temperature THW1 is lower in the transition mode map than in the normal mode map.

[0034] <Effect of the Embodiment> During the warm-up of engine 10, the low temperature of the combustion chamber walls can lead to unstable combustion due to poor vaporization of injected fuel and a decrease in combustion speed. The arithmetic processing unit 33 suppresses the deterioration of combustion during warm-up by adjusting engine control parameters such as fuel injection amount, EGR opening, and ignition timing based on the outlet water temperature THW1. Specifically, the arithmetic processing unit 33 adjusts the fuel injection amount during warm-up to be greater than after warm-up is complete, using a warm-up enrichment correction coefficient calculated based on the outlet water temperature THW1. In addition, the arithmetic processing unit 33 adjusts the recirculated exhaust volume during warm-up to be less than after warm-up is complete, by calculating the target EGR rate based on the outlet water temperature THW1. Furthermore, the arithmetic processing unit 33 adjusts the ignition timing during warm-up to be more advanced than after warm-up is complete, using a warm-up advance angle correction amount calculated based on the outlet water temperature THW1.

[0035] During the warm-up of the engine 10, the engine coolant circulating through the water jacket 11 is heated by the heat absorbed from the engine 10. Therefore, during the warm-up, the combustion chamber wall temperature fluctuates in correlation with the outlet water temperature THW1. Accordingly, the arithmetic processing unit 33 adjusts the engine operation amount to an appropriate value corresponding to the combustion chamber wall temperature based on the outlet water temperature THW1.

[0036] Incidentally, during the warm-up of the engine 10, the flow of water through the first heating water passage 16 or the second heating water passage 17 may be started due to a request for heating the passenger compartment or raising the temperature of the battery 27. When the flow of water is started, the cold engine coolant that had been stagnant in the first heating water passage 16 and the second heating water passage 17 flows into the water jacket 11. As a result, a water temperature drop may occur, causing the outlet water temperature THW1 to temporarily decrease. When a water temperature drip occurs, the correspondence between the outlet water temperature THW1 and the combustion chamber wall temperature is temporarily disrupted. As a result, the engine operation amount adjusted based on the outlet water temperature THW1 may deviate from the appropriate value corresponding to the combustion chamber wall temperature, potentially worsening the combustion state of the engine 10. In contrast, the engine control device of this embodiment suppresses the deterioration of the combustion state due to a water temperature drop by switching the map used to calculate the engine operation amount between when a water temperature drop occurs and when it is normal.

[0037] Figure 5 shows an example of the control mode of the engine control device of this embodiment. Figure 5(A) shows the transition of the open / closed state of the heating water passage, and Figure 5(B) shows the transition of the outlet water temperature THW1 and the heater inlet water temperature THW2. Figure 5(C) shows the transition of the warm-up increase correction coefficient for fuel injection amount, and Figure 5(D) shows the transition of the target EGR rate. Here, the open state of the heating water passage refers to the state in which engine coolant flowing out of the water jacket 11 flows through the switching valve 18 into at least one of the first heating water passage 16 and the second heating water passage 17. Here, the closed state of the heating water passage refers to the state in which the inflow of engine coolant flowing out of the water jacket 11 into both the first heating water passage 16 and the second heating water passage 17 is blocked by the switching valve 18.

[0038] In the case of Figure 5, the heating water channel is closed before time t1. Even during the period before time t1, the engine coolant circulating through the water jacket 11 is heated by heat received from the engine 10. Therefore, the outlet water temperature THW1 rises with the passage of time. In contrast, during the period before time t1, no engine coolant flows through the first heating water channel 16 and the second heating water channel 17, so the heater inlet water temperature THW2 remains low and unchanged.

[0039] When water is started flowing into the heating channel at time t1, the cold engine coolant that had been stagnant in the heating channel flows into the water jacket 11. As a result, a water temperature drop occurs after the start of water flow, causing the outlet water temperature THW1 to temporarily decrease. Immediately after the start of water flow, cold engine coolant remains in the heating channel, so the difference between the outlet water temperature THW1 and the heater inlet water temperature THW2 (water temperature difference ΔT) is large.

[0040] Figures 5(C) and 5(D) show the changes in the warm-up enrichment correction coefficient and target EGR rate when calculations using the normal map are continued after time t1, indicated by dashed lines. In this case, the warm-up enrichment correction coefficient and target EGR rate change in accordance with the decrease in outlet water temperature THW1 due to the water temperature drop. Therefore, the fuel injection amount and exhaust recirculation amount may become inappropriate values ​​that do not correspond to the combustion chamber wall temperature, potentially leading to a deterioration of the combustion state.

[0041] In response, the arithmetic processing unit 33 switches the map used for calculating engine control inputs from the normal map to the transition map when the switching valve 18 starts supplying water to the heating water channel and the water temperature difference ΔT exceeds the transition determination value. The normal map and the transition map are configured such that when the same value is output, the outlet water temperature THW1 is lower in the transition map than in the normal map. Therefore, changes in fuel injection amount and exhaust recirculation amount due to the decrease in outlet water temperature THW1 caused by the water temperature drop are suppressed.

[0042] When water is started to flow into the heating channel, the engine coolant, which has been heated by the heat received from the engine 10 after passing through the water jacket 11, flows into the heating channel, causing the heater inlet water temperature THW2 to start rising. After a certain amount of time has passed since the start of water flow, the engine coolant flowing from the heating channel into the water jacket 11 is replaced by engine coolant heated by the heat received from the engine 10, causing the outlet water temperature THW1 to start rising again. Therefore, when the water temperature drop ends, the difference between the outlet water temperature THW1 and the heater inlet water temperature THW2 (water temperature difference ΔT) decreases. At time t2, when the water temperature difference ΔT decreases to less than the transition judgment value, the arithmetic processing unit 33 determines that the water temperature drop has ended and returns the map used for calculating the engine operation amount from the transition map to the normal map.

[0043] <Effects of the Embodiment> The engine control device of this embodiment, configured as described above, provides the following effects. (1) The processing unit 33 determines that the period from when water is started flowing into the heating water channel by the switching valve 18 until the difference between the heater inlet water temperature THW2 and the outlet water temperature THW1 decreases to less than a predetermined value is the transition period during which a water temperature drop occurs. Therefore, it is possible to accurately determine the period during which a water temperature drop occurs.

[0044] (2) The arithmetic processing unit 33 calculates the engine operation amount using a transition map during the transition period and a normal map during other periods. The normal map and the transition map are maps that take the outlet water temperature THW1 as input and output values ​​such as the warm-up enrichment correction coefficient, target EGR rate, and warm-up advance angle correction amount used in calculating the engine operation amount, and are stored in the storage device 34. The normal map and the transition map are configured such that when the same value is output, the outlet water temperature THW1 is lower in the transition map than in the normal map. By switching between these maps, the reflection of the decrease in outlet water temperature THW1 due to a water temperature drop on the engine operation amount is mitigated. Therefore, the engine control device of this embodiment has the effect of suppressing the deterioration of the combustion state due to a water temperature drop.

[0045] <Other Embodiments> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0046] If calculations are performed using values ​​calculated with a normal map or a transition map, the calculation methods for fuel injection amount, EGR opening degree, and ignition timing in the above embodiment may be changed as appropriate.

[0047] If the engine control quantity is calculated based on the outlet water temperature THW1, the same calculation method for engine control quantities as in the above embodiment may be applied to engine control quantities other than fuel injection quantity, EGR opening, and ignition timing. When such a calculation method is applied to engine control quantities, inappropriate changes in values ​​due to water temperature drop are mitigated.

[0048] In the above embodiment, the cooling system of the engine 10 included a first heating water channel 16 equipped with a heater core 23 and a second heating water channel 17 equipped with a water-water heat exchanger 26, both of which were heating water channels. The cooling system of the engine 10 may be configured to include only one of the first heating water channel 16 and the second heating water channel 17 as the heating water channel. Alternatively, a water channel equipped with a heat exchanger separate from the heater core 23 and the water-water heat exchanger 26 may be provided as the heating water channel, as long as it is a heat exchanger for heating other fluids using the heat of the engine cooling water.

[0049] In the above embodiment, the temperature of the engine coolant flowing out of the heating heat exchanger (heater inlet water temperature) was detected in the first heating water channel 16 and the second heating water channel 17, downstream of the heater water pump 24 and upstream of the electric heater 25. This temperature detection location may be changed as appropriate. For example, the temperature of the engine coolant near the inlet 12 of the water jacket 11 may be detected as the temperature of the engine coolant flowing out of the heating heat exchanger.

[0050] A mechanical pump that operates using power from the engine 10 may be used as the water pump 20 for the engine. The engine control device of the above embodiment may be applied to a conventional engine vehicle that is not a hybrid vehicle.

[0051] <Additional Notes> [Note 1] The cooling system of the engine is provided with a cooling device that includes a radiator water channel that passes through the radiator, a heating water channel equipped with a heating heat exchanger for heating other fluids with the heat of the engine coolant, and a bypass water channel that allows the engine coolant to flow around the radiator and the heating heat exchanger, all arranged in parallel, and a thermostat that opens and closes the radiator water channel, and a switching valve that switches between a state in which the inflow of the engine coolant from the heating water channel to the water jacket is prohibited and a state in which it is permitted, and the device is equipped with a computing device and a memory device, and the memory device takes the outlet water temperature, which is the temperature of the engine coolant flowing out of the water jacket, as input, and the engine An engine control device is configured such that, when the same value is output, the normal map and the transition map are stored as maps for outputting values ​​used in calculating the manipulated variable, and the calculation processing unit is configured such that, after the switching valve switches from a state in which the inflow of engine coolant from the heating water channel to the water jacket is prohibited to a state in which it is permitted, the transition map is used to calculate the engine manipulated variable during the transition period until the difference between the temperature of the engine coolant flowing out of the heating heat exchanger and the outlet water temperature is reduced to less than a predetermined value, while the normal map is used to calculate the engine manipulated variable during periods other than the transition period, and the normal map and the transition map are configured such that when the same value is output, the outlet water temperature is lower in the transition map than in the normal map.

[0052] [Note 2] The engine control device according to Note 1, wherein the engine control quantity is one of the fuel injection amount, ignition timing, and exhaust recirculation valve opening ratio. [Note 3] The engine control device according to Note 1 or Note 2, wherein the heat exchanger for raising the temperature is a heater core that performs heat exchange between the air supplied to the passenger compartment and the engine coolant.

[0053] [Note 4] The engine control device according to Note 1 or Note 2, wherein the heat exchanger for raising the temperature is a water-water heat exchanger that performs heat exchange between battery cooling water used for temperature control of the battery and the engine cooling water. [Explanation of symbols]

[0054] 10...Engine, 10A...Injector, 10B...Ignition system, 10C...Exhaust recirculation valve, 11...Water jacket, 12...Inlet, 13...Outlet, 14...Bypass water channel, 15...Radiator water channel, 16...First heating water channel, 17...Second heating water channel, 18...Switching valve, 19...Thermostat, 20...Engine water pump, 21...Radiator, 22...Reservoir tank, 23...Heater core (heat exchanger for heating), 24...H 25...Water pump for the engine, 26...Electric heater, 27...Water-to-water heat exchanger (heat exchanger for heating), 28...Battery, 29...Recirculation water channel, 30...Outlet water temperature sensor, 31...Heater inlet water temperature sensor, 32...Electronic control unit (diagnostic device), 33...Calculation processing unit, 34...Memory device, 35...Airflow meter, 36...Intake air temperature sensor, 37...Vehicle speed sensor, 38...Accelerator pedal sensor, 39...Crank angle sensor.

Claims

1. An engine control device is provided in a cooling system that includes, as a flow path for engine coolant to return from the outlet of a water jacket to the inlet of the water jacket, a radiator water channel passing through a radiator, a heating water channel equipped with a heating heat exchanger for heating other fluids with the heat of the engine coolant, and a bypass water channel that allows the engine coolant to flow around the radiator and the heating heat exchanger, all arranged in parallel, and a thermostat for opening and closing the radiator water channel, and a switching valve for switching between a state in which the inflow of engine coolant from the heating water channel to the water jacket is prohibited and a state in which it is permitted, It is equipped with a processing unit and a memory device, The storage device stores a normal mode map and a transition mode map as maps that take the outlet water temperature, which is the temperature of the engine coolant flowing out of the water jacket, as input and output values ​​used for calculating engine operation amounts. The processing unit is configured to calculate the engine operation amount using the transition map during the transition period, from when the switching valve switches the flow of engine coolant from the heating water channel to the water jacket from a prohibited state to when it allows it, until the difference between the temperature of the engine coolant flowing out of the heating heat exchanger and the outlet water temperature decreases to less than a predetermined value, while calculating the engine operation amount using the normal state map during periods other than the transition period. The normal-time map and the transition-time map are configured such that when they output the same value, the outlet water temperature in the transition-time map is lower than that in the normal-time map. Engine control device.

2. The engine control device according to claim 1, wherein the engine operation amount is any of the fuel injection amount, ignition timing, and the opening ratio of the exhaust recirculation valve.

3. The engine control device according to claim 1, wherein the heat exchanger for raising the temperature is a heater core that performs heat exchange between the air supplied to the passenger compartment and the engine coolant.

4. The engine control device according to claim 1, wherein the heat exchanger for raising the temperature is a water-water heat exchanger that performs heat exchange between battery cooling water used for temperature control of the battery and the engine cooling water.

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