JP7444101B2 - Cooling systems and cooling system control methods - Google Patents

Description

This disclosure relates to a cooling system and a method of controlling the cooling system, and particularly relates to a cooling system of an internal combustion engine and a method of controlling the cooling system.

Conventionally, in order to purify the exhaust gas of an internal combustion engine, an additive valve for injecting fuel or an additive such as urea water has been provided in the exhaust passage of the internal combustion engine. Since such an addition valve reaches an extremely high temperature due to the heat of the exhaust gas, there is a risk that the internal components of the addition valve may deteriorate due to the heat. Therefore, there has been a cooling method in which the addition valve is cooled by circulating cooling water using a cooling pump (for example, see Patent Document 1). In the cooling method of Patent Document 1, in addition to preventing thermal deterioration of the addition valve, the temperature of the cooling pump is adjusted based on the temperature near the addition valve after the engine is stopped in order to prevent a decrease in the amount of stored electricity in the battery after the engine is stopped. Determining drive request. Furthermore, the cooling effect of the latent heat of vaporization of the cooling water is utilized to shorten the driving period of the cooling pump.

Japanese Patent Application Publication No. 2018-9456

In the cooling method of Patent Document 1, the addition valve is cooled after the engine is stopped, but since the addition valve may reach a high temperature even while the engine is running, a cooling pump is used to cool the addition valve. drive is required. In this case, in consideration of ease of installation in the engine room and cost, it is desirable to use an existing cooling pump, if any, to cool a plurality of objects to be cooled with one cooling pump.

For example, it is conceivable to cool the addition valve in addition to the intercooler using a cooling pump for water-cooling an intercooler provided for the purpose of controlling the temperature of intake air in the intake path of the engine. In this case, the engine may misfire or the exhaust performance may deteriorate due to overcooling of the intake air passing through the intercooler. In order to avoid this, it is necessary to shorten the driving period of the cooling pump due to the demand for cooling the addition valve. For this reason, it is conceivable to drive the cooling pump using the temperature associated with the addition valve. However, when a new sensor is installed to detect the temperature related to the addition valve, problems arise regarding the ease of mounting the sensor in the engine room and the cost.

This disclosure was made in order to solve the above-mentioned problems, and the purpose is to circulate a coolant for cooling an addition valve that adds an additive to the exhaust gas for purifying the exhaust gas of an internal combustion engine. It is an object of the present invention to provide a cooling system and a cooling system control method capable of estimating the temperature related to an addition valve without newly installing a sensor for detecting the temperature of the cooling liquid in a path for cooling.

The cooling system for an internal combustion engine according to this disclosure includes an addition valve that is installed in the exhaust path of the internal combustion engine and adds an additive to the exhaust gas for purifying the exhaust gas, and a first addition valve that circulates coolant to a cooling target different from the addition valve. In addition to the circulation path, a second circulation path that circulates the coolant to the addition valve includes a pump that circulates the coolant, and a plurality of pumps that each detect the values of a plurality of indexes that are different from the temperature of the coolant in the second circulation path. sensor and a control device that controls the pump. The controller estimates the associated temperature of the addition valve using the values of the plurality of indicators detected by the plurality of sensors.

The plurality of first indicators are indicators related to exhaust gas, which is an element that gives heat to the addition valve, among the plurality of indicators, and the plurality of second indicators are indicators, which are elements that take heat away from the addition valve, among the plurality of indicators. The index may be related to a cooling liquid. The control device uses the values of the plurality of first indicators to determine a first amount, which is a degree to which the exhaust gas contributes to an increase in the related temperature, converted into a temperature at which the temperature of the coolant increases per unit time. , using the values of the plurality of second indicators, specifying a second amount in which the degree to which the coolant contributes to the reduction of the related temperature is converted into a temperature at which the temperature of the coolant decreases per unit time, and The current related temperature may be estimated by adding to the estimated related temperature a value obtained by subtracting the second amount from the first amount multiplied by the elapsed period from the previous time to the present.

The plurality of sensors may include an air flow meter that detects the amount of air taken into the internal combustion engine, and an exhaust temperature sensor that detects the temperature of exhaust gas from the internal combustion engine. The control device may specify the first amount using the intake air amount detected by the air flow meter and the exhaust temperature detected by the exhaust temperature sensor.

The plurality of sensors may include a liquid temperature sensor that detects the temperature of the coolant in the first circulation path, and a related amount sensor that detects an amount related to the flow rate of the coolant. The control device may specify the second amount using the temperature detected by the liquid temperature sensor and the related amount detected by the related amount sensor.

The method may further include a holder accommodating the addition valve, the holder having a coolant inlet and an outlet, the associated temperature being the temperature of the coolant at the outlet.

According to another aspect of this disclosure, the cooling system in the method for controlling a cooling system of an internal combustion engine includes an additive valve that is provided in an exhaust path of the internal combustion engine and adds an additive to the exhaust gas for purifying the exhaust gas; In addition to the first circulation path that circulates the coolant to different objects to be cooled, a second circulation path that circulates the coolant to the addition valve includes a pump that circulates the coolant, and a temperature of the coolant in the second circulation path. It includes a plurality of sensors that respectively detect the values of a plurality of different indicators, and a control device that controls the pump. The control method includes the steps of a control device estimating a relevant temperature of the addition valve using values of a plurality of indicators detected by a plurality of sensors, and a step of controlling a pump using the estimated relevant temperature.

According to this disclosure, the additive for purifying the exhaust gas of an internal combustion engine is added to the exhaust gas without installing a new sensor to detect the temperature of the coolant in the path that circulates the coolant for cooling the addition valve that adds the additive to the exhaust gas. It is possible to provide a cooling system and a method of controlling a cooling system in which the relative temperature of a valve can be estimated.

1 is a diagram schematically showing the configuration of an internal combustion engine system according to this embodiment. FIG. 2 is a diagram schematically showing the configuration around the fuel addition valve of this embodiment. It is a flowchart which shows the flow of electric pump control processing in this embodiment. FIG. 7 is a diagram showing the relationship between each parameter in a map for determining the amount of increase in the temperature of the coolant in the fuel addition valve holder of this embodiment. FIG. 3 is a diagram showing the relationship between the rotational speed and the discharge amount of the electric pump of this embodiment. FIG. 3 is a diagram for explaining flow rate distribution between an intercooler system and a fuel addition valve system in this embodiment. FIG. 6 is a diagram showing the relationship between each parameter in a map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder of this embodiment. FIG. 3 is a first diagram for explaining the relationship between each parameter in a map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder of this embodiment. FIG. 7 is a second diagram for explaining the relationship between each parameter in the map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder of this embodiment. FIG. 7 is a third diagram for explaining the relationship between each parameter in the map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder of this embodiment. FIG. 7 is a fourth diagram for explaining the relationship between each parameter in the map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder of this embodiment. It is a figure which shows the relationship of each parameter in the map for calculating|requiring the temperature of the coolant in a fuel addition valve holder of 2nd Embodiment. 7 is a diagram showing the relationship between the intake air amount, the temperature of the exhaust gas around the fuel addition valve, and the energy of the exhaust gas around the fuel addition valve 61 in the second embodiment. FIG. It is a figure which shows the relationship between the rotational speed of the electric pump of 2nd Embodiment, and the amount of water inflow into a fuel addition valve holder. It is a figure showing an outline of composition of an internal combustion engine system concerning a 3rd embodiment. It is a figure showing the outline of composition of an internal combustion engine system concerning a 4th embodiment.

Embodiments of this disclosure will be described below with reference to the drawings. In the following description, the same parts are given the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[First embodiment]
FIG. 1 is a diagram schematically showing the configuration of an internal combustion engine system 1 according to this embodiment. Referring to FIG. 1, an internal combustion engine system 1 is mounted on a vehicle. The internal combustion engine system 1 includes an engine 10, a supercharger 22, a first oxidation catalyst (hereinafter referred to as "DOC (Diesel Oxidation Catalyst)") 41, and a particulate matter collection filter (hereinafter referred to as "DPF (Diesel Particulate Filter)"). ) 42, a selective reduction catalyst (hereinafter referred to as "SCR (Selective Catalytic Reduction)") 43, a second oxidation catalyst 44, a control device (hereinafter referred to as "ECU (Electronic Control Unit)") 50, and a cooling system. 70.

The ECU 50 is a known ECU including a CPU (Central Processing Unit) 51, a ROM (Read-Only Memory) 52, a RAM (Random Access Memory) 53, a timer 54, an EEPROM (Electrically Erasable Programmable Read-Only Memory) 55, and the like. It is something. ECU 50 controls each part of the vehicle, such as engine 10. The CPU 51 executes various calculation processes based on various programs and maps stored in the ROM 52. The RAM 53 temporarily stores calculation results by the CPU 51, data input from each detection device, and the like. The EEPROM 55 stores, for example, data that is saved when the main switch of the vehicle is turned off.

The supercharger 22 includes a turbine 22A that is rotationally driven by exhaust gas flowing from an exhaust inlet to an exhaust outlet, and a compressor 22B that compresses intake air from the intake inlet using the driving force from the turbine 22A and discharges it from the intake outlet. including.

An air cleaner (not shown) removes foreign matter such as dust contained in the intake air. One end of the intake pipe 11A is connected to the air cleaner. The other end of the intake pipe 11A is connected to the intake inlet of the compressor 22B.

The air flow meter 21 is provided in the middle of the intake pipe 11A, detects the flow rate of intake air passing therethrough, and outputs a detection signal indicating the detected flow rate to the ECU 50.

One end of the intake pipe 11B is connected to the intake outlet of the compressor 22B. The other end of the intake pipe 11B is connected to the intake inlet of the intake manifold 11C.

The intercooler 71 is provided in the middle of the intake pipe 11B, and cools the intake air passing through the intake flow path inside the intercooler 71, which forms part of the intake pipe 11B, by the coolant flowing through the internal coolant flow path. . Intake air temperature sensor 23A is provided upstream of intercooler 71 in intake pipe 11B, detects the temperature of intake air before it flows into intercooler 71, and outputs a detection signal indicating the detected temperature to ECU 50. The intake air temperature sensor 23B is provided downstream of the intercooler 71 in the intake pipe 11B, detects the temperature of the intake air cooled by the intercooler 71, and outputs a detection signal indicating the detected temperature to the ECU 50.

The intake manifold 11C divides intake air from the intake pipe 11B and guides it to each cylinder of the engine 10. Engine 10 is a diesel engine, and includes injectors 14A to 14D that inject fuel supplied from a fuel tank (not shown) into each cylinder in response to a control signal from ECU 50. The engine 10 compresses intake air from the intake manifold 11C, injects fuel into the compressed intake air to generate rotational driving force, and discharges exhaust gas from the combustion from each cylinder to the exhaust manifold 12A. Exhaust from engine 10 includes carbon monoxide (CO), hydrocarbons (HC), particulate matter (PM), and nitrogen oxides (NOx).

The crank angle sensor 27 is provided in the engine 10, detects the rotation angle of the crankshaft of the engine 10, and outputs a detection signal indicating the detected rotation angle to the ECU 50. The cam angle sensor 28 is provided in the engine 10, detects the compression top dead center of a predetermined cylinder of the engine 10, and outputs a detection signal to the ECU 50 at the detected timing. The accelerator opening sensor 25 detects the amount of depression of the accelerator pedal by the driver, and outputs a detection signal indicating the detected amount of depression to the ECU 50.

The ECU 50 calculates the rotational speed of the engine 10 from the rotational angle of the crankshaft indicated by the detection signal from the crank angle sensor 27, and the rotational speed is indicated by the calculated rotational speed of the engine 10 and the detection signal from the accelerator opening sensor 25. The required load is calculated using the amount of depression of the accelerator pedal, and the fuel injection amount is calculated using the required load and the intake air temperature indicated by the detection signal from the intake air temperature sensor 23B. The ECU 50 uses the rotation angle of the crankshaft indicated by the detection signal from the crank angle sensor 27 and the compression top dead center timing of a predetermined cylinder indicated by the detection signal from the cam angle sensor 28 to control the fuel injection for each cylinder. The timing is calculated, and the injectors 14A to 14D are controlled to inject the calculated fuel injection amount at the calculated timing.

The exhaust manifold 12A merges exhaust gas from each cylinder of the engine 10 and guides it to the exhaust pipe 12B. One end of an exhaust pipe 12B is connected to an exhaust outlet of the exhaust manifold 12A. The other end of the exhaust pipe 12B is connected to the exhaust inlet of the turbine 22A of the supercharger 22.

One end of an exhaust pipe 12C is connected to an exhaust outlet of a turbine 22A of the supercharger 22. The other end of the exhaust pipe 12C is connected to the exhaust inlet of the DOC 41. DOC41 purifies exhaust gas by oxidizing carbon monoxide (CO) and hydrocarbons (HC) contained in the exhaust gas. The exhaust gas temperature sensor 36A is provided in the middle of the exhaust pipe 12C, detects the temperature of the exhaust gas before it flows into the DOC 41, and outputs a detection signal indicating the detected temperature to the ECU 50.

The fuel addition valve 61 is provided in the exhaust pipe 12C between the turbine 22A of the supercharger 22 and the exhaust temperature sensor 36A, and adds (injects) fuel supplied from a fuel tank (not shown) to the exhaust gas as an additive. do.

A DPF 42 is provided on the side of the DOC 41 from which exhaust gas flows out. The DPF 42 collects particulate matter (PM) contained in the exhaust gas. The exhaust gas temperature sensor 36B is provided between the DCO 41 and the DPF 42, detects the temperature of the exhaust gas flowing out from the DOC 41, and outputs a detection signal indicating the detected temperature to the ECU 50. The differential pressure sensor 35 detects the differential pressure between the upstream side and the downstream side of the DPF 42 and outputs a detection signal indicating the detected differential pressure to the ECU 50.

The ECU 50 uses the differential pressure indicated by the detection signal from the differential pressure sensor 35 to estimate the amount of particulate matter (PM) collected in the DPF 42 . The ECU 50 controls the fuel addition valve 61 to add fuel when the amount of accumulation exceeds a predetermined threshold. When fuel is added, the fuel undergoes an oxidation reaction in the DOC 41, and the heat of the reaction increases the temperature of the exhaust gas flowing into the DPF 42. The ECU 50 controls the amount of fuel added by the fuel addition valve 61 so that the exhaust temperature indicated by the detection signal from the exhaust temperature sensor 36B becomes a temperature suitable for burning particulate matter (PM). As a result, the particulate matter (PM) deposited on the DPF 42 is burned and removed, and the collection function of the DPF 42 is restored (regenerated).

One end of the exhaust pipe 12D is connected to the exhaust outlet of the DPF 42. The other end of the exhaust pipe 12D is connected to the exhaust inlet of the SCR 43. The SCR 43 uses ammonia generated from the heat of the exhaust gas from the urea water added by the urea water addition valve 62 to reduce and purify nitrogen oxides (NOx) contained in the exhaust gas.

The exhaust gas temperature sensor 36C and the NOx sensor 37A are provided in the exhaust pipe 12D between the DPF 42 and the SCR 43. The exhaust gas temperature sensor 36C detects the temperature of the exhaust gas flowing out from the DFP 42, and outputs a detection signal indicating the detected temperature to the ECU 50. The NOx sensor 37A detects the concentration of NOx contained in the exhaust gas flowing out from the DPF 42, and outputs a detection signal indicating the detected concentration to the ECU 50.

The urea water addition valve 62 is provided in the exhaust pipe 12D between the NOx sensor 37A and the SCR 43, and adds (injects) urea water supplied from a urea water tank (not shown) to the exhaust gas as an additive.

One end of the exhaust pipe 12E is connected to the exhaust outlet of the SCR 43. The other end of the exhaust pipe 12E is connected to the exhaust gas inlet of the second oxidation catalyst 44. The exhaust gas temperature sensor 36D and the NOx sensor 37B are provided in the middle of the exhaust pipe 12E. The exhaust temperature sensor 36D detects the temperature of the exhaust gas flowing out from the SCR 43, and outputs a detection signal indicating the detected temperature to the ECU 50. The NOx sensor 37B detects the concentration of NOx contained in the exhaust gas flowing out from the SCR 43, and outputs a detection signal indicating the detected concentration to the ECU 50.

The ECU 50 calculates the degree of NOx purification by the SCR 43 using the concentration of NOx indicated by the detection signals from the NOx sensors 37A and 37B and the temperature of the exhaust gas indicated by the detection signal from the exhaust temperature sensor 36D. The urea water addition valve 62 is controlled to add urea water according to the degree. As a result, NOx contained in the exhaust gas is reduced and purified by the SCR 43.

The second oxidation catalyst 44 oxidizes and removes surplus ammonia that is not used in the SCR 43. The exhaust gas flowing out from the exhaust outlet of the second oxidation catalyst 44 passes through a muffler (not shown) and is discharged into the atmosphere.

The cooling system 70 of this embodiment has a coolant circulation system for the fuel addition valve 61 (hereinafter referred to as the "additional system") added to the existing coolant circulation system for the intercooler 71 (hereinafter referred to as the "existing system"). It consists of: The cooling system 70 includes the above-mentioned intercooler 71, an intercooler radiator 72, an electric pump 73, the above-mentioned fuel addition valve 61, a fuel addition valve holder 74, and a coolant circulation passage 75. The ECU 50 constitutes a part of the cooling system 70 by controlling the electric pump 73 of the cooling system 70.

Coolant circulation passage 75 includes a radiator outlet pipe 75AA, a pump outlet pipe 75BA, an intercooler-bound pipe 75BB, a fuel addition valve-bound pipe 75BC, an intercooler return pipe 75CA, and a fuel addition valve return pipe 75CB.

The electric pump 73 has a motor that is driven in response to a control signal from the ECU 50, and pumps the coolant circulating through the coolant circulation passage 75 by the driving force of the motor. Electric pump 73 includes a motor rotation speed sensor 73A. The rotational speed sensor 73A detects the rotational speed of the motor and outputs a detection signal indicating the detected rotational speed to the ECU 50. Coolant flows into the electric pump 73 from the radiator outlet pipe 75AA. The coolant pumped from the electric pump 73 flows through the pump outlet pipe 75BA, and then is divided into the intercooler-bound pipe 75BB and the fuel addition valve-bound pipe 75BC.

The coolant diverted to the intercooler-bound pipe 75BB flows into the intercooler 71. The intercooler 71 has been described above, so a redundant explanation will not be repeated. The coolant flowing through the coolant flow path inside the intercooler 71 is heated by exchanging heat with the intake air passing through the intake flow path connected to the intake pipe 11B. Coolant temperature sensor 71A is provided on the upstream side of the coolant flow path of intercooler 71, detects the temperature of the coolant on the inlet side of intercooler 71, and outputs a detection signal indicating the detected temperature to ECU 50. Coolant temperature sensor 71B is provided on the downstream side of the coolant flow path of intercooler 71, detects the temperature of the coolant on the outlet side of intercooler 71, and outputs a detection signal indicating the detected temperature to ECU 50. The coolant flowing out from the intercooler 71 flows into the intercooler radiator 72 after flowing through the intercooler return pipe 75CA.

The coolant branched into the fuel addition valve-bound pipe 75BC flows into the fuel addition valve holder 74.

FIG. 2 is a diagram schematically showing the configuration around the fuel addition valve 61 of this embodiment. Referring to FIG. 2, fuel addition valve holder 74 includes a housing 74C that encloses fuel addition valve 61. As shown in FIG. The housing 74C is provided with a coolant inlet 74A and a coolant outlet 74B. The space between the housing 74C and the fuel addition valve 61 is filled with coolant flowing from the fuel addition valve-bound pipe 75BC through the coolant inlet 74A. The coolant filling the space flows out from the coolant outlet 74B.

Since the fuel addition valve 61 is provided in the exhaust pipe 12C through which high-temperature exhaust gas flows, it is heated by the exhaust gas flowing through the exhaust pipe 12C and the exhaust pipe 12C. Inside the fuel addition valve 61, there is a resin material for the purpose of maintaining the posture of a solenoid for injecting fuel. When this resin material deteriorates and melts due to heat, a space is created around the coil portion of the solenoid. For this reason, the coil is in an air-insulated state, and the coil burns out due to self-heating of the coil. The fuel addition valve 61 is cooled by coolant filled in the fuel addition valve holder 74. This can prevent the coil of the fuel addition valve 61 from burning out.

The coolant flowing out from the coolant outlet 74B of the fuel addition valve holder 74 flows through the fuel addition valve return pipe 75CB, joins the intercooler return pipe 75CA, and flows into the intercooler radiator 72.

The intercooler radiator 72 is provided separately from the engine radiator 15 that cools the engine coolant that circulates inside the engine 10 to cool it. The intercooler radiator 72 cools the coolant by heat exchange between the outside air flowing in contact with the outer surface of the intercooler radiator 72 and the coolant flowing inside the intercooler radiator 72 . The coolant flowing out from the intercooler radiator 72 returns to the electric pump 73 after flowing through the radiator outlet pipe 75AA.

As explained above, in the existing system, the coolant is supplied to the radiator outlet pipe 75AA, the electric pump 73, the pump outlet pipe 75BA, the intercooler going pipe 75BB, the intercooler 71, the intercooler return pipe 75CA, and the intercooler radiator 72. cycle in this order. In the additional system, the coolant branches off at the pump outlet piping 75BA of the existing system and circulates in the order of the fuel addition valve-bound piping 75BC, the fuel addition valve holder 74 (fuel addition valve 61), and the fuel addition valve return piping 75CB, It joins the intercooler return pipe 75CA. The additional system is parallel to the intercooler-bound piping 75BB, intercooler 71, and intercooler return piping 75CA of the existing system.

In the cooling system 70 described above, an electric pump 73 is used to cool the intercooler 71, which is provided for the purpose of controlling the temperature of intake air in the intake path of the engine 10, and the fuel addition valve 61 is installed in addition to the intercooler 71. cooled down. In this case, the engine 10 may misfire or the exhaust performance may deteriorate due to supercooling of the intake air passing through the intercooler 71. In order to avoid this, it is necessary to shorten the driving period of the electric pump 73 due to the request for cooling the fuel addition valve 61. For this reason, it is conceivable to drive the electric pump 73 using the temperature related to the fuel addition valve 61. However, when a new temperature sensor is installed to detect the temperature related to the fuel addition valve 61, problems arise in terms of mountability and cost in the engine room regarding the temperature sensor.

Therefore, the cooling system 70 includes a fuel addition valve 61 that is provided in the exhaust path of the engine 10 and adds fuel, which is an additive for purifying the exhaust gas, to the exhaust gas, and an intercooler 71 that is a cooling object different from the fuel addition valve 61. In addition to the existing system that circulates coolant to the fuel addition valve 61, an electric pump 73 that circulates coolant and an ECU 50 that controls the electric pump 73 are added to the additional system that circulates coolant to the fuel addition valve 61. The ECU 50 includes a plurality of sensors (for example, an air flow meter 21, an exhaust temperature sensor 36A, a coolant temperature sensor 71A, and a rotational speed sensor 73A) that detect values of a plurality of indexes different from temperature. The related temperature of the fuel addition valve 61 is estimated using the values of the plurality of indexes.

This eliminates the need to newly install a sensor to detect the temperature of the coolant in the path that circulates the coolant for cooling the fuel addition valve 61 that adds fuel, which is an additive for purifying the exhaust gas of the engine 10, to the exhaust gas. The relevant temperature of the fuel addition valve 61 can be estimated.

FIG. 3 is a flowchart showing the flow of electric pump control processing in this embodiment. This electric pump control process is called and executed by the CPU 51 of the ECU 50 from a higher level process at every predetermined control cycle.

Referring to FIG. 3, first, CPU 51 of ECU 50 estimates the temperature Tc of the coolant at the outlet of fuel addition valve holder 74 (step S111). A method for estimating this temperature Tc will be described later.

Next, the CPU 51 specifies the temperature Ta indicated by the detection signal from the intake air temperature sensor 23B that detects the temperature Ta of the intake air at the outlet of the intercooler 71 (step S112).

The CPU 51 outputs a control signal to the electric pump 73 and determines whether the electric pump 73 is in operation (step S113). When determining that the electric pump 73 is not in operation (NO in step S113), the CPU 51 determines whether the coolant temperature Tc estimated in step S111 exceeds the predetermined temperature T1 (Tc>T1) (step S114). ). The predetermined temperature T1 is a reference temperature of the coolant at the outlet of the fuel addition valve holder 74 for determining that the thermal deterioration of the resin material of the fuel addition valve 61 is progressing. When the temperature Tc of the coolant exceeds the predetermined temperature T1, the degree of thermal deterioration progresses faster than the predetermined degree at which thermal deterioration is a concern.

If it is determined that Tc>T1 is not (NO in step S114), the CPU 51 determines whether the temperature Ta of the intake air at the outlet of the intercooler 71 specified in step S112 exceeds a predetermined temperature T3 (Ta>T3). (Step S115). The predetermined temperature T3 is a reference temperature of the intake air at the outlet of the intercooler 71 for determining that the efficiency of the engine 10 becomes lower than a predetermined value due to the low intake air temperature. When the intake air temperature Ta at the outlet of the intercooler 71 exceeds this predetermined temperature T3, the efficiency of the engine 10 becomes worse than the predetermined value. If it is determined that Ta>T3 is not satisfied (NO in step S115), the CPU 51 returns the process to be executed to the higher level process that called the electric pump control process.

On the other hand, if it is determined that Tc>T1 (YES in step S114) or Ta>T3 (YES in step S115), the CPU 51 calculates the required flow rate of the discharge flow rate of the electric pump 73. (Step S116).

When Tc>T1, the required flow rate of the discharge flow rate of the electric pump 73 is calculated from a required flow rate calculation map having the cooling efficiency η of the intercooler 71 and the flow rate of intake air flowing into the intercooler 71 as axes. The cooling efficiency η can be calculated using the following formula: η=(intercooler inlet intake air temperature−intercooler outlet intake temperature)×100/(intercooler inlet intake air temperature−intercooler inlet water temperature). This required flow rate calculation map is set such that the higher the cooling efficiency η or the greater the inflow intake air flow rate, the larger the required flow rate.

If Ta > T3, based on the idea that the amount of water is sent to replace the entire volume of coolant entering the space of the fuel addition valve holder 74, the required flow rate and drive are adjusted so that the following relationship holds: required flow rate x driving period = volume. Calculate the period. When Tc>T1 and Ta>T3, the required flow rate is set to be the larger of the required flow rate when Tc>T1 and the required flow rate when Ta>T3.

Next, the CPU 51 controls the electric pump 73 to discharge the required flow rate calculated in step S116 (step S117). After step S117, the CPU 51 returns the process to be executed to the higher level process that called the electric pump control process.

If it is determined that the electric pump 73 is in operation (YES in step S113), the CPU 51 determines whether the coolant temperature Tc estimated in step S111 is less than the predetermined temperature T2 (Tc<T2). (Step S121). The predetermined temperature T2 is a reference temperature of the coolant at the outlet of the fuel addition valve holder 74 for determining that thermal deterioration of the resin material of the fuel addition valve 61 does not proceed. When the coolant temperature Tc falls below this predetermined temperature T2, the degree of progress of thermal deterioration becomes slower than the predetermined degree at which thermal deterioration is a concern.

If it is determined that Tc<T2 is not satisfied (NO in step S121), the CPU 51 shifts the process to step S116 described above.

When determining that Tc<T2 (YES in step S121), the CPU 51 determines whether the temperature Ta of the intake air at the outlet of the intercooler 71 specified in step S112 has become less than the predetermined temperature T4 (Ta<T4). is determined (step S122). The predetermined temperature T4 is a reference temperature of the intake air at the outlet of the intercooler 71 for determining that the engine 10 will misfire or the exhaust performance will deteriorate due to the intake air temperature being too low. If the intake air temperature Ta at the outlet of the intercooler 71 falls below this predetermined temperature T4, the engine 10 may misfire or the exhaust performance may become worse than regulatory standards. If it is determined that Ta<T4 is not satisfied (NO in step S122), the CPU 51 moves the processing to be executed to step S116 described above.

If it is determined that Ta<T4 (YES in step S122), the CPU 51 controls the electric pump 73 to stop (step S123). After step S123, the CPU 51 returns the process to be executed to the higher level process that called the electric pump control process.

Next, a method for estimating the temperature Tc of the coolant at the outlet of the fuel addition valve holder 74 in step S111 will be described. Temperature Tc (°C) is calculated as follows: Tc (°C) = Tc (°C) of previous control cycle + (amount of rise in temperature of coolant in fuel addition valve holder 74 per unit time (°C/sec) - fuel per unit time) It can be estimated using the calculation formula: amount of decrease in temperature of the coolant in the addition valve holder 74 (° C./sec) x control period (sec).

The amount of increase in the temperature of the coolant in the fuel addition valve holder 74 per unit time can be calculated based on the state of the exhaust gas around the fuel addition valve holder 74.

FIG. 4 is a diagram showing the relationship between each parameter in a map for determining the amount of increase in temperature of the coolant in the fuel addition valve holder 74 of this embodiment. Referring to FIG. 4, there is a relationship such that the greater the intake air flow rate (intake air amount) detected by air flow meter 21, the greater the amount of increase in coolant temperature. Further, there is a relationship such that the higher the temperature of the exhaust gas around the fuel addition valve 61, the greater the amount of increase in the coolant temperature. The temperature of the exhaust gas around the fuel addition valve 61 can be considered to be the same as the temperature of the exhaust gas detected by the exhaust temperature sensor 36A. Therefore, a map shown in FIG. 4 in which the relationship between the intake air amount, the exhaust temperature around the fuel addition valve 61, and the amount of increase in the temperature of the coolant in the fuel addition valve holder 74 is set is used. The amount of increase in the temperature of the coolant within the addition valve holder 74 per unit time is determined.

FIG. 5 is a diagram showing the relationship between the rotational speed and the discharge amount of the electric pump 73 of this embodiment. Referring to FIG. 5, as the rotation speed of electric pump 73 increases, the discharge amount increases exponentially. When the temperature of the coolant is high, the kinematic viscosity of the coolant decreases, so the discharge amount increases at the same rotation speed. When the temperature of the coolant is low, the kinematic viscosity of the coolant increases, so the discharge amount at the same rotation speed decreases. In this embodiment, as shown in step S116 in FIG. 3, the ECU 50 calculates the required flow rate of the coolant. The ECU 50 determines the rotational speed of the electric pump 73 for discharging this required flow rate using the relationship shown in FIG. In step S117, the ECU 50 controls the motor of the electric pump 73 to rotate at the determined rotational speed.

FIG. 6 is a diagram for explaining the flow rate distribution between the intercooler 71 system and the fuel addition valve 61 system in this embodiment. Referring to FIG. 6, the distribution ratio of the discharge flow rate of electric pump 73 between the intercooler 71 system and the fuel addition valve 61 system is constant regardless of the discharge flow rate of electric pump 73.

FIG. 7 is a diagram showing the relationship between each parameter in a map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder 74 of this embodiment. Referring to FIG. 7, there is a relationship such that the higher the temperature of the coolant at the inlet of the fuel addition valve holder 74, the greater the amount of decrease in the temperature of the coolant inside the fuel addition valve holder 74. The temperature of the coolant at the inlet of the fuel addition valve holder 74 is considered to be the same as the temperature of the coolant at the inlet of the intercooler 71 detected by the coolant temperature sensor 71A. For this reason, there is a relationship such that the higher the temperature of the coolant on the inlet side of the intercooler 71 detected by the coolant temperature sensor 71A, the greater the amount of decrease in the coolant temperature.

Further, there is a relationship such that the higher the rotational speed of the motor of the electric pump 73 determined in FIG. 5, the greater the amount of decrease in coolant temperature. Using the map in which the relationship shown in FIG. 7 is set, the amount of decrease in coolant temperature per unit time is determined.

FIG. 8 is a first diagram for explaining the relationship between each parameter in the map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder 74 of this embodiment. Referring to FIG. 8, when the temperature of the coolant in the fuel addition valve holder 74 is 100° C., when 25° C. coolant flows into the fuel addition valve holder 74 by 20% of the capacity, the fuel addition valve holder 74 It is thought that the temperature of the coolant inside is about 85°C.

FIG. 9 is a second diagram for explaining the relationship between each parameter in the map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder 74 of this embodiment. Referring to FIG. 9, when the temperature of the coolant in the fuel addition valve holder 74 is 100° C., the coolant at 25° C., the same as in FIG. 8, is 80% of the capacity of the fuel addition valve holder 74, which is different from FIG. It is thought that when the coolant flows in for 20 minutes, the temperature of the coolant inside the fuel addition valve holder 74 becomes about 40°C.

Based on FIGS. 8 and 9, when the temperature of the coolant flowing into the fuel addition valve holder 74 is constant, the amount of decrease in the temperature of the coolant inside the fuel addition valve holder 74 per unit time increases as the flow rate increases. You can think of it as getting bigger. From this, as shown in FIG. 7, a relationship can be derived that the higher the rotational speed of the motor of the electric pump 73, the greater the amount of decrease in coolant temperature.

FIG. 10 is a third diagram for explaining the relationship between each parameter in the map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder 74 of this embodiment. Referring to FIG. 10, when the temperature of the coolant in the fuel addition valve holder 74 is 100° C., when 25° C. coolant flows into the fuel addition valve holder 74 by 20% of the capacity, the fuel addition valve holder 74 It is thought that the temperature of the coolant inside is about 85°C.

FIG. 11 is a fourth diagram for explaining the relationship between each parameter in the map for determining the amount of decrease in the temperature of the coolant in the fuel addition valve holder 74 of this embodiment. Referring to FIG. 11, when the temperature of the coolant in the fuel addition valve holder 74 is 100°C, the coolant at 50°C, which is different from that in FIG. It is thought that when the coolant flows in for 1 minute, the temperature of the coolant inside the fuel addition valve holder 74 becomes about 90°C.

Based on FIGS. 10 and 11, when the flow rate of the coolant flowing into the fuel addition valve holder 74 is constant, the lower the temperature of the coolant flowing into the fuel addition valve holder 74, the lower the temperature of the coolant inside the fuel addition valve holder 74 per unit time. It can be assumed that the amount increases. From this, as shown in FIG. 7, a relationship can be derived that the higher the temperature of the coolant on the inlet side of the intercooler 71, the greater the amount of decrease in the coolant temperature.

[Second embodiment]
In the first embodiment, the amount of increase in coolant temperature in the fuel addition valve holder 74 is calculated using the intake air amount and the exhaust temperature around the fuel addition valve 61, and the amount of increase in the coolant temperature on the inlet side of the intercooler 71 is Using the temperature and the discharge flow rate of the electric pump (rotational speed of the electric pump 73), the amount of decrease in the coolant temperature in the fuel addition valve holder 74 is calculated, and the amount of increase in the coolant temperature in the fuel addition valve holder 74 is calculated. The coolant temperature Tc inside the fuel addition valve holder 74 is estimated using the amount of decrease.

In the second embodiment, the coolant temperature Tc inside the fuel addition valve holder 74 is estimated using a method different from the first embodiment. In the second embodiment, the calculation formula is: temperature Tc = Tc of the previous control cycle (°C) + amount of increase in temperature of the coolant in the fuel addition valve holder 74 per unit time (°C/sec) x control cycle (sec). , estimate the temperature Tc. Note that when the amount of increase exceeds 0, the temperature Tc increases. If the amount of increase is less than 0, the temperature Tc decreases.

FIG. 12 is a diagram showing the relationship between each parameter in a map for determining the temperature of the coolant in the fuel addition valve holder 74 of the second embodiment. Referring to FIG. 12, the temperature of the coolant flowing into the fuel addition valve holder 74 and the temperature of the coolant flowing into the fuel addition valve holder 74 for each amount of water flowing into the fuel addition valve holder 74 Vn (n=1, 2, 3...) The relationship between the temperature of the coolant inside the fuel addition valve holder 74 and the amount of increase in the temperature of the coolant inside the fuel addition valve holder 74 per unit time with respect to the energy of the exhaust gas near the fuel addition valve 61 is specified in advance by simulation or experiment.

The temperature of the coolant flowing into the fuel addition valve holder 74 is considered to be the same as the temperature of the coolant on the inlet side of the intercooler 71 detected by the coolant temperature sensor 71A. The temperature of the coolant in the fuel addition valve holder 74 is the coolant temperature in the fuel addition valve holder 74 in the previous control cycle.

The energy of the exhaust gas near the fuel addition valve 61 is determined as follows. FIG. 13 is a diagram showing the relationship between the intake air amount, the temperature of the exhaust gas around the fuel addition valve 61, and the energy of the exhaust gas around the fuel addition valve 61 (gas energy near the addition valve) in the second embodiment. Referring to FIG. 13, there is a relationship such that the greater the flow rate of intake air (intake air amount) detected by air flow meter 21, the greater the gas energy near the addition valve. Further, there is a relationship such that the higher the temperature of the exhaust gas around the fuel addition valve 61, the greater the gas energy near the addition valve. The temperature of the exhaust gas around the fuel addition valve 61 can be considered to be the same as the temperature of the exhaust gas detected by the exhaust temperature sensor 36A. Therefore, the map shown in FIG. 13 in which the relationship between the intake air amount, the exhaust temperature around the fuel addition valve 61, and the gas energy near the addition valve is set is used, and the gas energy near the addition valve shown in FIG. Desired.

The amount of water Vn flowing into the fuel addition valve holder 74 is determined as follows. FIG. 14 is a diagram showing the relationship between the rotational speed of the electric pump 73 and the amount of water flowing into the fuel addition valve holder 74 in the second embodiment. Referring to FIG. 14, when the rotational speed of electric pump 73 increases, the amount of inflow water increases exponentially. When the temperature of the coolant is high, the kinematic viscosity of the coolant decreases, so the amount of water flowing in at the same rotation speed increases. When the temperature of the coolant is low, the kinematic viscosity of the coolant increases, so the amount of water flowing in at the same rotation speed decreases. Therefore, using FIG. 14, the amount of water Vn flowing into the fuel addition valve holder 74 is determined using the rotational speed of the electric pump 73 and the temperature of the coolant flowing into the fuel addition valve holder 74.

[Third embodiment]
In the first embodiment, the cooling system 70 of the internal combustion engine system 1 cools the fuel addition valve 61 in addition to the intercooler 71. In the second embodiment, in addition to the intercooler 71, the cooling system 70A of the internal combustion engine system 1A cools the fuel addition valve 61 and the urea water addition valve 62.

FIG. 15 is a diagram schematically showing the configuration of an internal combustion engine system 1A according to the third embodiment. Referring to FIG. 15, an internal combustion engine system 1A of the third embodiment is obtained by changing the cooling system 70 of the internal combustion engine system 1 of the first embodiment to a cooling system 70A shown in FIG.

In addition to the configuration of the cooling system 70 of the first embodiment, the cooling system 70A of the third embodiment includes a urea water addition valve holder 76 and a coolant circulation passage 75A that is a modification of the coolant circulation passage 75 of the first embodiment. include.

In addition to the coolant circulation passage 75 of the first embodiment, the coolant circulation passage 75A of the third embodiment includes a urea water addition valve-bound pipe 75BD, a urea water addition valve return pipe 75CC, and a fuel addition valve return pipe 75CB. Does not include.

The coolant flowing out from the coolant outlet 74B of the fuel addition valve holder 74 flows through the urea water addition valve-bound pipe 75BD, and then flows into the urea water addition valve holder 76. The structure of the urea water addition valve holder 76 is similar to the structure of the fuel addition valve holder 74 described in FIG. 2.

Since the urea water addition valve 62 is provided in the exhaust pipe 12D through which high-temperature exhaust gas flows, it is heated by the exhaust gas flowing through the exhaust pipe 12D and the exhaust pipe 12D. Inside the urea water addition valve 62, there is a resin material for the purpose of maintaining the posture of a solenoid for injecting urea water. When this resin material deteriorates and melts due to heat, a space is created around the coil portion of the solenoid. For this reason, the coil is in an air-insulated state, and the coil burns out due to self-heating of the coil. The urea water addition valve 62 is cooled by the coolant filled in the urea water addition valve holder 76 . This can prevent the coil of the urea water addition valve 62 from burning out.

The coolant flowing out from the urea water addition valve holder 76 flows through the urea water addition valve return pipe 75CC, joins the intercooler return pipe 75CA, and flows into the intercooler radiator 72.

As explained above, in the existing system, the coolant is supplied to the radiator outlet pipe 75AA, the electric pump 73, the pump outlet pipe 75BA, the intercooler going pipe 75BB, the intercooler 71, the intercooler return pipe 75CA, and the intercooler radiator 72. cycle in this order. In the additional system, the coolant is branched off at the pump outlet piping 75BA of the existing system, to a piping 75BC for the fuel addition valve, a fuel addition valve holder 74 (fuel addition valve 61), a piping 75BD for the urea water addition valve, and a piping 75BD for the urea water addition valve. It circulates in this order through the valve holder 76 (urea water addition valve 62), urea water addition valve return pipe 75CC, and joins the intercooler return pipe 75CA. The additional system is parallel to the intercooler-bound piping 75BB, intercooler 71, and intercooler return piping 75CA of the existing system.

Also in such a cooling system 70A, the related temperature of the urea water addition valve 62 can be estimated in the same manner as in the first embodiment or the second embodiment.

[Fourth embodiment]
In the third embodiment, the fuel addition valve holder 74 and the urea water addition valve holder 76 are connected in series in the additional system. In the fourth embodiment, in the additional system, the fuel addition valve holder 74 and the urea water addition valve holder 76 are connected in parallel.

FIG. 16 is a diagram schematically showing the configuration of an internal combustion engine system 1B according to the fourth embodiment. Referring to FIG. 16, an internal combustion engine system 1B of the fourth embodiment is obtained by changing the cooling system 70 of the internal combustion engine system 1 of the first embodiment to a cooling system 70B shown in FIG. 16.

In addition to the configuration of the cooling system 70 of the first embodiment, the cooling system 70B of the fourth embodiment includes a urea water addition valve holder 76 and a coolant circulation passage 75B that is a modification of the coolant circulation passage 75 of the first embodiment. include.

The coolant circulation passage 75B of the fourth embodiment includes, in addition to the coolant circulation passage 75 of the first embodiment, a urea water addition valve-bound pipe 75BE and a urea water addition valve return pipe 75CD.

After flowing through the pump outlet pipe 75BA, the coolant pumped from the electric pump 73 is sent to the intercooler-bound pipe 75BB and the fuel addition valve-bound pipe 75BC in the first embodiment, as well as to the urea water addition valve-bound pipe 75BE. Diverted.

The coolant branched to the urea water addition valve-bound pipe 75BE flows into the fuel addition valve holder 74. The structure of the urea water addition valve holder 76 is similar to that of the fuel addition valve holder 74 described in FIG. 2, as in FIG. 15 of the third embodiment.

The coolant flowing out from the urea water addition valve holder 76 flows through the urea water addition valve return pipe 75CD, joins the fuel addition valve return pipe 75CB, then joins the intercooler return pipe 75CA, and flows into the intercooler radiator 72. Inflow.

As explained above, in the existing system, the coolant is supplied to the radiator outlet pipe 75AA, the electric pump 73, the pump outlet pipe 75BA, the intercooler going pipe 75BB, the intercooler 71, the intercooler return pipe 75CA, and the intercooler radiator 72. cycle in this order. In the additional system, the coolant is branched into two routes at the pump outlet piping 75BA of the existing system, and in the first route, the pipe 75BC goes to the fuel addition valve, the fuel addition valve holder 74 (fuel addition valve 61), It circulates in the order of the fuel addition valve return pipe 75CB and joins the intercooler return pipe 75CA, and in the second route, the urea water addition valve goes to the pipe 75BD, the urea water addition valve holder 76 (urea water addition valve 62), and the urea water addition valve holder 76 (urea water addition valve 62). It circulates in the order of water addition valve return pipe 75CC and joins fuel addition valve return pipe 75CB. The two routes of the additional system are parallel to the intercooler-bound pipe 75BB, intercooler 71, and intercooler return pipe 75CA of the existing system.

Also in such a cooling system 70B, the related temperature of the urea water addition valve 62 can be estimated in the same manner as in the first embodiment or the second embodiment.

[Other variations]
(1) In the embodiment described above, as shown in steps S111 and S113 in FIG. 3, when the temperature at the outlet of the fuel addition valve holder 74 exceeds the predetermined temperature T1, the fuel addition valve 61 is not deteriorated I decided to proceed. However, the present invention is not limited to this, and other related temperatures of the addition valve may be used as long as the temperature allows determining the deterioration of the addition valve such as the fuel addition valve 61 or the urea water addition valve 62. The temperature may be the temperature of a predetermined part (for example, a coil part, a resin material) inside the addition valve 61 or the urea water addition valve 62.

(2) In the embodiment described above, temperature sensors such as coolant temperature sensors 71A, 71B, intake air temperature sensors 23A, 23B, and exhaust temperature sensors 36A, 36C, and rotational speed sensor 73A of electric pump 73 detect The value may be a value estimated from a value detected by another sensor.

(3) In the embodiment described above, the coolant outlet temperature of the fuel addition valve holder 74 or the urea water addition valve holder 76 is taken as the related temperature of the addition valve such as the fuel addition valve 61 or the urea water addition valve 62, respectively. Cooling of the addition valve is now judged. However, the related temperature of the addition valve is not limited to this, and may be the temperature inside the fuel addition valve holder 74 or the urea water addition valve holder 76, or the temperature inside the fuel addition valve 61 or the urea water addition valve 62 itself. It may also be the temperature of a predetermined portion.

(4) In the third and fourth embodiments described above, in the cooling systems 70A and 70B, both the fuel addition valve 61 and the urea water addition valve 62 are cooled by the coolant for cooling the intercooler 71. It was to so. However, the present invention is not limited to this, and only the urea water addition valve 62 may be cooled by the coolant for cooling the intercooler 71.

(5) The above-mentioned disclosure can be regarded as disclosure of the cooling systems 70, 70A, 70B, and can be regarded as disclosure of the control device (for example, ECU 50) of the cooling systems 70, 70A, 70B. This can be regarded as a disclosure of a control method or a control program by the control device 70A, 70B, and can be regarded as a disclosure of a method of estimating the temperature related to the addition valves (fuel addition valve 61, urea water addition valve 62).

[summary]
(1) As shown in FIGS. 1, 15, and 16, the cooling system (for example, cooling system 70, 70A, 70B) of the internal combustion engine (for example, internal combustion engine system 1, 1A, 1B) is For example, an addition valve (for example, a fuel addition valve 61, a urea water addition valve 62) that is provided in the exhaust path of the engine 10) and adds an additive (for example, fuel, urea water) to the exhaust gas for purifying the exhaust gas; In addition to the first circulation path (e.g., existing system) that circulates the coolant (e.g., coolant) to a cooling target different from the addition valve, the second circulation path (e.g., an additional system) that circulates the coolant to the addition valve. , a pump that circulates the coolant (for example, electric pump 73), and a plurality of indicators (for example, intake air amount, exhaust temperature, coolant temperature, rotational speed of electric pump 73) that are different from the temperature of the coolant in the second circulation path. ), and a control device (eg, ECU 50) that controls the pump. As shown in step S111 of FIG. 3, FIGS. 4 to 7 and 12 to 14, the controller uses the values of the plurality of indicators detected by the plurality of sensors to determine the relative temperature of the addition valve (e.g. It may be the temperature of the coolant on the outlet side of the fuel addition valve holder 74 or the urea water addition valve holder 76, or it may be the temperature of the coolant inside the fuel addition valve holder 74 or the urea water addition valve holder 76. , or the temperature of a predetermined portion of the fuel addition valve 61 or the urea water addition valve 62 itself.

This eliminates the need to install a new sensor to detect the temperature of the coolant in the path that circulates the coolant for cooling the additive valve that adds additives to the exhaust gas for purifying the exhaust gas of the engine 10. Temperature can be estimated.

(2) As shown in FIGS. 4 to 7, the plurality of first indicators are indicators related to exhaust gas, which is the element that gives heat to the addition valve (for example, intake air amount, exhaust temperature ), and the plurality of second indicators are indicators (for example, coolant temperature, rotation speed of the electric pump 73) related to the coolant, which is an element that takes heat from the addition valve, among the plurality of indicators. Good too. As shown in step S111 of FIG. 3 and FIGS. 4 to 7, the control device uses the values of the plurality of first indicators to determine the degree to which the exhaust gas contributes to the increase in the related temperature per unit time. A first amount in terms of the temperature at which the temperature of the liquid increases is determined, and the degree to which the cooling liquid contributes to a decrease in the relevant temperature is determined by using the values of the plurality of second indicators. Determine a second quantity converted to the temperature at which the temperature decreases, and add the value obtained by subtracting the second quantity from the first quantity to the previously estimated related temperature multiplied by the elapsed period from the previous time to the present. By doing so, the current relevant temperature may be estimated.

(3) As shown in FIGS. 1, 15, and 16, the plurality of sensors include an air flow meter (for example, air flow meter 21) that detects the intake air amount to the internal combustion engine, and an air flow meter that measures the exhaust temperature from the internal combustion engine. It may also include an exhaust gas temperature sensor (for example, exhaust gas temperature sensor 36A) for detection. As shown in step S111 in FIG. 3 and FIG. 4, the control device specifies the first amount using the intake air amount detected by the air flow meter and the exhaust temperature detected by the exhaust temperature sensor. You can also do this.

(4) As shown in FIGS. 1, 15, and 16, the plurality of sensors include a liquid temperature sensor (for example, coolant temperature sensor 71A) that detects the temperature of the coolant in the first circulation path, and a coolant temperature sensor that detects the temperature of the coolant in the first circulation path. It may also include a related quantity sensor (for example, rotational speed sensor 73A) that detects a quantity related to the flow rate. As shown in step S111 in FIG. 3 and FIGS. 5 to 7, the control device specifies the second quantity using the temperature detected by the liquid temperature sensor and the related quantity detected by the related quantity sensor. You may also do so.

(5) As shown in FIG. 1, FIG. 2, FIG. 15, and FIG. It may have a liquid inlet (eg, coolant inlet 74A) and an outlet (eg, coolant outlet 75B), and the associated temperature may be the temperature of the coolant at the outlet.

It is also planned that the embodiments disclosed herein will be implemented in appropriate combinations. The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the description of the embodiments described above, and it is intended that all changes within the meaning and scope equivalent to the claims are included.

1, 1A, 1B internal combustion engine system, 10 engine, 11A, 11B intake pipe, 11C intake manifold, 12A exhaust manifold, 12B to 12E exhaust pipe, 14A to 14D injector, 15 engine radiator, 21 air flow meter, 22 supercharger , 22A turbine, 22B compressor, 23A, 23B intake air temperature sensor, 25 accelerator opening sensor, 27 crank angle sensor, 28 cam angle sensor, 35 differential pressure sensor, 36A to 36D exhaust temperature sensor, 37A, 37B NOx sensor, 41 DOC , 42 DPF, 43 SCR, 44 second oxidation catalyst, 50 ECU, 51 CPU, 52 ROM, 53 RAM, 54 timer, 55 EEPROM, 61 fuel addition valve, 62 urea water addition valve, 70, 70A, 70B cooling system, 71 Intercooler, 71A, 71B Coolant temperature sensor, 72 Intercooler radiator, 73 Electric pump, 73A Rotational speed sensor, 74 Fuel addition valve holder, 74A Coolant inlet, 74B Coolant outlet, 74C Housing, 75, 75A, 75B coolant circulation passage, 75AA radiator outlet piping, 75BA pump outlet piping, 75BB piping to intercooler, 75BC piping to fuel addition valve, 75BD, 75BE piping to urea water addition valve, 75CA intercooler return piping, 75CB fuel addition valve return piping , 75CD Urea water addition valve return piping, 76 Urea water addition valve holder.

Claims (5)

A cooling system for an internal combustion engine,
an addition valve that is installed in the exhaust path of the internal combustion engine and adds an additive to the exhaust gas for purifying the exhaust gas;
a pump that circulates the coolant through a second circulation path that circulates the coolant to the addition valve in addition to a first circulation path that circulates the coolant to a cooling target different from the addition valve;
a plurality of sensors each detecting values of a plurality of indicators different from the temperature of the coolant in the second circulation path;
and a control device that controls the pump,
The plurality of first indicators are indicators related to exhaust gas, which is an element that provides heat to the addition valve, among the plurality of indicators,
The plurality of second indicators are indicators related to the cooling liquid, which is an element that removes heat from the addition valve, among the plurality of indicators,
The control device includes:
estimating the associated temperature of the addition valve using the values of the plurality of indicators detected by the plurality of sensors;
Using the values of the plurality of first indicators, specifying a first amount in which the degree to which the exhaust gas contributes to the increase in the related temperature is converted into a temperature at which the temperature of the coolant increases per unit time;
Using the values of the plurality of second indicators, specifying a second amount in which the degree to which the coolant contributes to the decrease in the related temperature is converted into a temperature at which the temperature of the coolant decreases per unit time;
Estimating the current related temperature by adding to the previously estimated related temperature a value obtained by subtracting the second amount from the first amount multiplied by the elapsed period from the previous time to the present. cooling system. The plurality of sensors include:
an air flow meter that detects the amount of air intake into the internal combustion engine;
an exhaust temperature sensor that detects exhaust temperature from the internal combustion engine,
The control device includes:
The cooling system according to claim 1 , wherein the first amount is determined using an intake air amount detected by the air flow meter and an exhaust temperature detected by the exhaust temperature sensor. The plurality of sensors include:
a liquid temperature sensor that detects the temperature of the coolant in the first circulation path;
a related quantity sensor that detects a quantity related to the flow rate of the coolant;
The control device includes:
The cooling system according to claim 1 , wherein the second quantity is determined using the temperature detected by the liquid temperature sensor and the related quantity detected by the related quantity sensor. further comprising a holder accommodating the addition valve,
The holder has a coolant inlet and an outlet,
4. A cooling system according to any of claims 1 to 3 , wherein the relevant temperature is the temperature of the cooling liquid at the outlet. A method for controlling a cooling system of an internal combustion engine, the method comprising:
The cooling system includes:
an addition valve that is installed in the exhaust path of the internal combustion engine and adds an additive to the exhaust gas for purifying the exhaust gas;
a pump that circulates the coolant through a second circulation path that circulates the coolant to the addition valve in addition to a first circulation path that circulates the coolant to a cooling target different from the addition valve;
a plurality of sensors each detecting values of a plurality of indicators different from the temperature of the coolant in the second circulation path;
and a control device that controls the pump,
The plurality of first indicators are indicators related to exhaust gas, which is an element that provides heat to the addition valve, among the plurality of indicators,
The plurality of second indicators are indicators related to the cooling liquid, which is an element that removes heat from the addition valve, among the plurality of indicators,
In the control method, the control device:
estimating the associated temperature of the addition valve using the values of the plurality of indicators detected by the plurality of sensors;
using the values of the plurality of first indicators to identify a first amount in which the degree to which the exhaust gas contributes to the increase in the related temperature is converted into a temperature at which the temperature of the coolant increases per unit time; ,
Using the values of the plurality of second indicators, specifying a second amount, which is the degree to which the coolant contributes to the decrease in the related temperature, converted into a temperature at which the temperature of the coolant decreases per unit time. and,
Estimating the current related temperature by adding to the previously estimated related temperature a value obtained by subtracting the second amount from the first amount multiplied by the elapsed period from the previous time to the present. and,
controlling the pump using the estimated relevant temperature.

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