WO2024095395A1

WO2024095395A1 - Internal combustion engine control device and internal combustion engine control method

Info

Publication number: WO2024095395A1
Application number: PCT/JP2022/040999
Authority: WO
Inventors: 亮草壁; 譲山崎; 圭太郎宍戸; 邦彦鈴木
Original assignee: 日立Astemo株式会社
Priority date: 2022-11-02
Filing date: 2022-11-02
Publication date: 2024-05-10

Abstract

According to one aspect of the present invention, an internal combustion engine control device controls an internal combustion engine comprising an oil pump that discharges lubricating oil at a specified flow rate and an oil jet system that injects the lubricating oil discharged from the oil pump toward a supplied portion of a piston, the internal combustion engine control device comprising a control unit that performs, when the temperature of a piston crown surface is lower than a lower limit temperature of a temperature range in which an amount of deposit accumulation on the piston crown surface is smaller than a threshold value, control for stopping the injection of the lubricating oil from the oil jet system or control for reducing the flow rate of the lubricating oil compared with the flow rate in the previous cycle.

Description

Internal combustion engine control device and internal combustion engine control method

The present invention relates to an internal combustion engine control device and an internal combustion engine control method for controlling an internal combustion engine that injects an oil jet into a piston.

In the control system of an internal combustion engine, it is known that the accumulation of deposits in the combustion chamber can lead to a deterioration in fuel efficiency and exhaust performance. When deposits have accumulated, one method is to operate the internal combustion engine at a higher load, thereby controlling the burning of the deposits and thereby reducing the amount of deposits that have built up in the combustion chamber. However, when the amount of deposits increases, the deposits harden, which can lead to issues such as the deposit accumulation not being able to be suppressed even when control is used to burn the deposits.

Patent Document 1 discloses a method of controlling the ON/OFF of the oil jet to prevent the piston temperature from entering the temperature range where the amount of deposit buildup increases, in order to suppress the buildup of deposits in the cooling channel. In this way, by controlling the piston temperature so that it does not enter the temperature range where the amount of deposit buildup increases, it is possible to suppress the buildup of deposits.

JP 2017-145757 A

However, in the technology described in Patent Document 1, when the oil jet is turned on and the piston temperature is lowered in order to suppress deposit accumulation, the displacement increases. As a result, exhaust gas regulated substances such as THC (Total Hydro Carbon) and PN (Particulate Number) increase. Furthermore, when there are multiple temperature ranges in which deposits increase, it is difficult to maintain the piston temperature at a temperature that suppresses deposit accumulation by only controlling the oil jet on/off, and deposit accumulation can sometimes cause THC and PN to increase.

Given the above situation, there was a demand for a method that could simultaneously suppress deposit accumulation and reduce emissions of substances subject to exhaust gas regulations.

In order to solve the above problem, one embodiment of the present invention is an internal combustion engine control device that controls an internal combustion engine having an oil pump that discharges a specified flow rate of lubricating oil and an oil jet system that injects the lubricating oil discharged from the oil pump toward a supply portion of a piston, and includes a control unit that stops the injection of lubricating oil from the oil jet system or controls the flow rate of lubricating oil to be lower than the flow rate of the previous cycle when the temperature of the piston crown surface is below the lower limit temperature of a temperature range in which the amount of deposits accumulated on the piston crown surface is less than a threshold value.

According to at least one embodiment of the present invention, it is possible to suppress both the accumulation of deposits and the emission of substances regulated in exhaust gases.
Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments.

1 is a schematic diagram showing an example of a system configuration of an internal combustion engine controlled by an internal combustion engine control device according to a first embodiment of the present invention. 1 is a schematic cross-sectional view showing an example of the configuration of a variable displacement oil pump used in an internal combustion engine. 1 is a block diagram showing an example of the configuration of an internal combustion engine control device according to a first embodiment of the present invention; 1 is a control block diagram showing an overview of control executed by an internal combustion engine control device according to a first embodiment of the present invention. 1 is a map (graph) showing an example of the relationship between oil pressure and oil jet flow rate. 11 is a map showing an example of the relationship between the oil jet flow rate and the heat transfer coefficient between the piston and the oil jet. FIG. 4 is a diagram showing an example of the relationship between engine operation time of an internal combustion engine and THC. FIG. 4 is a diagram showing an example of the relationship between piston crown surface temperature and deposit accumulation amount. 5 is a flowchart showing an example of the operation of a hydraulic pressure setting unit of the internal combustion engine control device according to the first embodiment of the present invention. 1 is a map (graph) showing an example of the relationship between oil temperature and oil jet injectable pressure. FIG. 11 is a schematic diagram showing a configuration example of a piston according to a second embodiment of the present invention. FIG. 11 is a diagram showing time series changes in vehicle speed, oil jet flow rate, piston crown surface temperature, and oil temperature at engine start in a second embodiment of the present invention. FIG. 11 is a block diagram showing an example of the configuration of an internal combustion engine control device according to a third embodiment of the present invention. FIG. 11 is a control block diagram showing an overview of control executed by an internal combustion engine control device according to a third embodiment of the present invention. FIG. 11 is a block diagram showing an outline of control by an internal combustion engine control device according to a fourth embodiment of the present invention.

Below, examples of modes for carrying out the present invention (hereinafter referred to as "embodiments") will be described with reference to the accompanying drawings. In this specification and the accompanying drawings, identical components or components having substantially the same functions will be designated by the same reference numerals, and duplicate descriptions will be omitted.

First Embodiment
First, a system configuration of an internal combustion engine controlled by an internal combustion engine control device according to a first embodiment of the present invention will be described with reference to FIG.

[Configuration of the internal combustion engine]
Fig. 1 is a schematic diagram showing an example of a system configuration of an internal combustion engine controlled by an internal combustion engine control device according to this embodiment. An internal combustion engine 100 shown in Fig. 1 shows the system configuration of a spark ignition internal combustion engine used in automobiles, and is equipped with an in-cylinder fuel injection valve that directly injects fuel made of gasoline into a cylinder. Note that the internal combustion engine 100 is not limited to an in-cylinder injection type internal combustion engine (direct injection engine), and a port injection type internal combustion engine that injects fuel into an intake port may also be used.

The internal combustion engine 100 is a four-stroke engine that repeats four strokes: an intake stroke, a compression stroke, a combustion (expansion) stroke, and an exhaust stroke. The internal combustion engine 100 is also a multi-cylinder engine with, for example, four cylinders. The number of cylinders that the internal combustion engine 100 has is not limited to four, and the engine may have six or eight or more cylinders. The number of cycles of the internal combustion engine 100 is also not limited to four.

As shown in FIG. 1, the internal combustion engine 100 includes an airflow sensor 1, an electronically controlled throttle valve 2, an intake pressure sensor 3, a compressor 4a, an intercooler 7, and a cylinder 14. The airflow sensor 1, the electronically controlled throttle valve 2, the intake pressure sensor 3, the compressor 4a, and the intercooler 7 are arranged in the intake pipe 6 up to the cylinder 14.

In addition, the air flow sensor 1 measures the intake air volume and intake air temperature. The electronically controlled throttle valve 2 is driven to be able to open and close by a drive motor (not shown). The opening of the electronically controlled throttle valve 2 is adjusted based on the driver's accelerator operation. This adjusts the amount of air taken in and the pressure in the intake pipe 6. The intake pressure sensor 3 measures the pressure in the intake pipe 6.

The compressor 4a compresses the intake air to be supercharged in the turbocharger. Rotational force is transmitted to the compressor 4a by the turbine 4b, which will be described later. The intercooler 7 is disposed upstream of the cylinder 14 and cools the intake air.

In addition, the internal combustion engine 100 is provided with an ignition device for each cylinder 14, which is composed of a fuel injection device 13 that injects fuel into the cylinder 14, and an ignition coil 16 and a spark plug 17 that supply ignition energy. Under the control of the internal combustion engine control device 30, the ignition coil 16 generates a high voltage and applies it to the spark plug 17. This generates a spark in the spark plug 17. The spark generated in the spark plug 17 then burns the air-fuel mixture in the cylinder, causing an explosion. For example, an ECU (Engine Control Unit) can be used as the internal combustion engine control device 30.

In addition, a voltage sensor (not shown) is attached to the ignition coil 16. The voltage sensor measures the primary side voltage or secondary side voltage of the ignition coil 16. The voltage information measured by the voltage sensor is sent to the internal combustion engine control device 30.

In addition, variable valves 5a and 5b are provided in the cylinder head 20 of the cylinder 14. Variable valve 5a adjusts the mixture flowing into the cylinder 14, and variable valve 5b adjusts the exhaust gas discharged from the cylinder. By adjusting variable valves 5a and 5b, the intake volume and internal EGR (Exhaust Gas Recirculation) volume of all cylinders 14 are adjusted.

Furthermore, a piston 21 is slidably disposed within the cylinder 14. The piston 21 compresses the mixture of fuel and gas that flows into the cylinder 14. The piston 21 reciprocates within the cylinder 14 due to the combustion pressure generated within the cylinder. The internal combustion engine 100 is also equipped with a crank angle sensor 19 for detecting the position of the piston 21. Crank angle information (rotation information) measured by the crank angle sensor 19 is sent to the internal combustion engine control device 30.

The fuel injection device 13 is controlled by an internal combustion engine control device 30 (ECU) and injects fuel into the cylinder 14. As a result, an air-fuel mixture is generated inside the cylinder 14. A high-pressure fuel pump (not shown) is also connected to the fuel injection device 13. Fuel whose pressure has been increased by the high-pressure fuel pump is supplied to the fuel injection device 13. Furthermore, a fuel pressure sensor for measuring the fuel injection pressure is provided in the fuel pipe connecting the fuel injection device 13 and the high-pressure fuel pump.

The cylinder 14 is also provided with a temperature sensor 18. The temperature sensor 18 measures the temperature of the cooling water circulating through the cylinder 14. The cooling water device includes a water pump (not shown), which adjusts the flow rate of the cooling water circulating through the cylinder 14. The water pump may be one that is driven using the output of the internal combustion engine, or an electric water pump (electric water pump). Although not shown, in addition to the water pump, the device for adjusting the cooling water may also include a thermostat that controls the cooling water flowing into the cylinder, and a valve for switching the flow direction to each component such as the cooling water heat exchanger and cylinder provided in the internal combustion engine.

Furthermore, each cylinder 14 of the internal combustion engine 100 is provided with an oil jet system 101 (piston cooling device). The oil jet system 101 is connected to a variable displacement oil pump 54 (see FIG. 2), and oil (lubricating oil) for cooling and lubrication is supplied from the oil pump 54. The oil jet system 101 is provided with a throttle section 103 that increases the flow rate of the lubricating oil. Engine oil is generally used as the lubricating oil.

The oil jet system 101 injects lubricating oil from the throttle section 103 onto the underside of the piston 21 to lower the temperature of the piston 21. The oil jet system 101 allows the lubricating oil to be appropriately applied to the underside (backside) of the piston 21, and the temperature of the piston crown surface can be accurately controlled. In addition, the amount of lubricating oil injected from the oil jet system 101 toward the piston 21 can be changed by the internal combustion engine control device 30 adjusting the output (flow rate, oil pressure) of the oil pump 54.

A valve 102 is provided in the oil flow path of the oil jet system 101. The valve 102 is provided between the oil main gallery 110 and the oil jet nozzle outlet. In this example, the valve 102 is disposed between the oil pump 54 and the oil jet nozzle outlet.

Furthermore, an exhaust pipe 15 is connected to the exhaust port of the cylinder 14. The exhaust pipe 15 is provided with a turbine 4b, an electronically controlled wastegate valve 11, a three-way catalyst 10, and an air-fuel ratio sensor 9. The turbine 4b rotates due to the exhaust gas passing through the exhaust pipe 15, and transmits the rotational force to the compressor 4a. In addition, the electronically controlled wastegate valve 11, which is connected to connect the upstream and downstream sides of the turbine 4b, adjusts the exhaust flow rate that flows to the turbine 4b.

The three-way catalyst 10 is disposed downstream of the turbine 4b. The three-way catalyst 10 purifies harmful substances contained in the exhaust gas by oxidation and reduction reactions. The air-fuel ratio sensor 9 is disposed upstream of the three-way catalyst 10. The air-fuel ratio sensor 9 detects the air-fuel ratio of the exhaust gas passing through the exhaust pipe 15.

In addition, signals detected by each sensor, such as the air flow sensor 1, the intake pressure sensor 3, and the voltage sensor, are sent to the internal combustion engine control device 30. In addition, a signal detected by the accelerator opening sensor 12, which detects the amount of depression of the accelerator pedal, i.e., the accelerator opening, is also sent to the internal combustion engine control device 30.

The internal combustion engine control device 30 calculates the required torque based on the output signal of the accelerator opening sensor 12. That is, the accelerator opening sensor 12 is used as a required torque detection sensor that detects the torque required for the internal combustion engine 100. The internal combustion engine control device 30 also calculates the rotation speed of the internal combustion engine 100 based on the output signal of the crank angle sensor 19. Then, the internal combustion engine control device 30 optimally calculates the main operating variables of the internal combustion engine 100, such as the air flow rate (intake flow rate), fuel injection amount, ignition timing, throttle opening, and fuel pressure, based on the operating state of the internal combustion engine 100 obtained from the output signals of various sensors.

The fuel injection amount calculated by the internal combustion engine control device 30 is converted into a valve opening pulse signal and output to the fuel injection device 13. In addition, the ignition timing calculated by the internal combustion engine control device 30 is output to the spark plug 17 as an ignition signal. Furthermore, the throttle opening calculated by the internal combustion engine control device 30 is output to the electronically controlled throttle valve 2 as a throttle drive signal.

In the internal combustion engine 100 configured in this manner, fuel is injected from the fuel injector 13 into the air that flows into the cylinder 14 from the intake pipe 6 through the intake valve (variable valve 5a), forming an air-fuel mixture inside the cylinder. The air-fuel mixture explodes at a specified ignition timing due to a spark generated by the spark plug 17, and the resulting combustion pressure pushes down the piston 21, providing the driving force for the internal combustion engine 100. Furthermore, the exhaust gas after the explosion is sent through the exhaust pipe 15 to the three-way catalyst 10, where the exhaust components are purified before being discharged to the outside.

The internal combustion engine 100 may be provided with an EGR pipe (not shown) that connects the intake pipe 6 and the exhaust pipe 15. This EGR pipe may return a portion of the exhaust gas passing through the exhaust pipe 15 to the intake pipe 6.

[Oil pump configuration]
Next, the outline of the configuration of the variable displacement oil pump 54 used in the internal combustion engine 100 will be described with reference to FIG.

2 is a schematic cross-sectional view showing an example of the configuration of a variable displacement oil pump 54 used in the internal combustion engine 100. The oil pump section (oil pump 54) is a variable displacement pump that includes a pump housing 161 having a storage section, a rotor 164 arranged in the storage section and connected to the rotating shaft of the internal combustion engine 100 so as to be capable of transmitting driving force, a cam ring 165 in which the amount of eccentricity between the center of rotation of the rotor 164 and its own center changes between a high discharge amount position and a low discharge amount position, and a control valve section (proportional solenoid 171a in an oil control valve 171, a substantially cylindrical valve body not shown) that changes the amount of eccentricity of the cam ring 165 under the control of a control section (oil jet control section 36 of the internal combustion engine control device 30). The configuration of the oil pump 54 will be described in more detail below.

The variable displacement oil pump 54 can variably control the pressure (hydraulic pressure) of the oil it discharges. In the oil pump 54, an intake port and an exhaust port are provided on both sides of the pump housing 161. In addition, a drive shaft 162, which transmits rotational force from the crankshaft of the internal combustion engine 100, is disposed and passes through the oil pump 54 at approximately the center.

A rotor 164 and a cam ring 165 are housed and arranged inside the pump housing 161. The rotor 164 is connected to the drive shaft 162. In other words, the rotor 164 is configured to be able to transmit the driving force of the rotating shaft of the internal combustion engine 100. The rotor 164 holds multiple vanes 163 on its outer periphery so that they can freely move forward and backward in approximately the radial direction.

The cam ring 165 is provided on the outer periphery of the rotor 164 so as to be able to eccentrically swing. The tips of the vanes 163 come into sliding contact with the inner periphery of the cam ring 165. In addition, a pair of vane rings 150 are slidably arranged on both side surfaces on the inner periphery of the rotor 164.

On the outer periphery side of the cam ring 165, working

chambers

167 and 168 are formed so as to be separated by sealing

members

166a and 166b. The cam ring 165 swings around pivot pin 169 in a direction that reduces the amount of eccentricity according to the discharge pressure of the oil introduced into working

chambers

167 and 168. Furthermore, the cam ring 165 has a lever portion 165a formed integrally with its outer periphery. The lever portion 165a is formed so as to protrude toward the outer periphery of the cam ring 165. The spring force of the coil spring 151 that presses against the lever portion 165a causes the cam ring 165 to swing in a direction that increases the amount of eccentricity in a direction that is approximately perpendicular to the rotational direction of the crankshaft.

In the initial state, the internal combustion engine control device 30 uses the spring force of the coil spring 151 to bias the cam ring 165 in the direction that maximizes the amount of eccentricity, thereby increasing the discharge pressure of the oil pump 54. On the other hand, when the oil pressure in the working chamber 167 reaches or exceeds a predetermined value, the internal combustion engine control device 30 swings the cam ring 165 against the spring force of the coil spring 170 in the direction that reduces the amount of eccentricity, thereby reducing the discharge pressure.

Oil (lubricating oil) is supplied to the working chamber 167 of the oil pump 54 from the oil main gallery 110, and oil is supplied to the working chamber 168 via an oil control valve 171 consisting of a proportional solenoid valve. The oil discharged from the oil pump 54 is supplied to a hydraulic VTC (Valve Timing Control) mechanism that controls the above-mentioned variable valves 5a, 5b (see Figure 1) of the internal combustion engine 100, an oil jet mechanism that cools the piston 21, etc.

The oil control valve 171 has a first opening 172 and a second opening 173 formed in the main body. The oil control valve 171 also has a proportional solenoid 171a inside and an approximately cylindrical valve body (not shown) that moves in response to the thrust generated in the proportional solenoid 171a when excited. Grooves designed with the positions of the first opening 172 and the second opening 173 in mind are formed on the circumferential surface of the approximately cylindrical valve body. The valve body moves in the axial direction of the oil control valve 171 (left and right direction in Figure 2) in response to the thrust generated by the proportional solenoid 171a. Depending on the position of the valve body, the relative positional relationship between the groove of the valve body and the first opening 172 and the second opening 173 changes, and the flow path changes. When the valve body is in the first position, the working chamber 168 of the oil pump communicates with the oil pan through the first opening 172. Furthermore, when the valve body is in the second position, the oil pump working chamber 168 communicates with the oil main gallery 110 through the first opening 172 and the second opening 173.

The oil control valve 171 is duty controlled by a drive signal (PWM (Pulse Width Modulation) signal) from the internal combustion engine control device 30. Depending on the duty ratio of the drive signal, the proportional solenoid 171a in the oil control valve 171 is excited and the valve body is driven to the target control position.

The oil pump 54 has a mechanism for manipulating the hydraulic pressure of the discharge oil (hereinafter also referred to as the "discharge hydraulic pressure") by controlling the amount of eccentricity of the vane 163 in accordance with the hydraulic pressure difference between the working chamber 167 and the working chamber 168. The oil pump 54 performs the following controls.
[a] When the difference in oil pressure between the working

chambers

167 and 168 is large, the amount of eccentricity of the vane 163 (cam ring 165) is reduced to reduce the discharge oil pressure.
[b] When the difference in oil pressure between the working

chambers

167 and 168 is small, the amount of eccentricity of the vane 163 (cam ring 165) is increased to increase the discharge oil pressure.

The hydraulic pressure in the working chamber 168 can be controlled by controlling the introduction and discharge of oil into and from the working chamber 168. That is, the hydraulic pressure in the working chamber 168 is controlled by the duty ratio of a drive signal supplied to the oil control valve 171. The relationship between the duty ratio of the drive signal and the discharge hydraulic pressure is as follows.
[a] When the duty ratio is 100%, the valve body in the oil control valve 171 moves to a position where the working chamber 168 communicates with the oil pan, and the oil pressure in the working chamber 168 decreases (= the oil pressure in the working chamber 168 is equivalent to that of the oil pan (1 atmosphere)). As a result, the eccentricity of the vane 163 (cam ring 165) of the oil pump 54 becomes minimum, and the discharge oil pressure becomes minimum.
[b] When the duty ratio is 0%, the valve body in the oil control valve 171 moves to a position where the working chamber 168 communicates with the oil main gallery 110, and the oil pressure in the working chamber 167 increases (= the oil pressure in the working chamber 168 is equal to that of the oil main gallery 110). As a result, the eccentricity of the vane 163 (cam ring 165) of the oil pump 54 becomes maximum, and the discharge oil pressure becomes maximum.

In this way, when the duty ratio of the drive signal is large, the working chamber 168 communicates with the drain (oil pan) via the oil control valve 171. As a result, the oil discharged from the oil pump 54 is in a low-pressure state. On the other hand, when the duty ratio of the drive signal is small, the oil main gallery 110 and the working chamber 168 communicate with each other via the oil control valve 171, and hydraulic pressure is applied to the working chamber 167. As a result, the oil discharged from the oil pump 54 is in a high-pressure state. And by manipulating the duty ratio of the drive signal between 100% and 0%, it is possible to adjust the pressure of the oil discharged from the oil pump 54 in the range from maximum to minimum.

Also, an oil pressure sensor 111 is disposed in the oil main gallery 110. The oil pressure sensor 111 measures the pressure of the oil in the oil main gallery 110 and outputs a signal according to the oil pressure. The oil pressure in the oil main gallery 110 correlates with the pressure of the oil discharged by the oil pump 54 (discharge oil pressure). In this embodiment, the discharge oil pressure of the oil pump 54 is detected by acquiring the output signal of the oil pressure sensor 111. The output signal of this oil pressure sensor 111 is input to the internal combustion engine control device 30 and is used for feedback control of the discharge oil pressure of the oil pump 54 to the target discharge oil pressure. Of course, it goes without saying that the oil pressure obtained from the output signal of the oil pressure sensor 111 can be used for other controls. Hereinafter, when simply described as "oil pressure", it means the discharge oil pressure of the oil pump 54.

The oil supplied and injected to each mechanism, and the oil discharged from the oil control valve 171, is collected in the oil pan and then supplied again to the oil main gallery 110, from where it is supplied and injected to each of the above-mentioned mechanisms.

According to the configuration of the oil jet system 101 using the variable displacement oil pump 54 shown in FIG. 2, the discharge oil pressure of the oil pump 54 can be set arbitrarily, so the amount of oil supplied to the oil jet can be adjusted. Therefore, in this embodiment, as shown in FIG. 8 and FIG. 12 described later, it is easier to maintain the crown surface temperature of the piston 21 in a temperature range 802 (between a lower limit temperature 805 and an upper limit temperature 806) where the amount of deposit accumulation is equal to or less than a threshold value 804, compared to the case where the oil jet is simply switched ON/OFF.

Instead of the variable displacement oil pump 54 described above, an oil pump in which the oil pressure increases in proportion to the rotation speed may be used. Generally, such oil pumps cannot reduce the oil pressure completely under low temperature conditions, and the pump alone cannot create an oil jet stop state. Therefore, in order to create an oil jet stop state, it is necessary to provide a solenoid valve for stopping the oil jet. When a variable displacement oil pump 54 is used, hydraulic control is possible over the entire temperature range, including low temperatures, so there is no need for a solenoid valve for switching between on and off oil jet injection.

If the oil jet system 101 is configured using a variable displacement oil pump 54, it is possible to control the amount of oil supplied to the oil jet even when the ambient temperature is low, making it easier to control the temperature of the piston crown surface, and improving the effect of reducing THC and PN.

[Configuration of the internal combustion engine control device]
Next, a configuration example of an internal combustion engine control device 30 to which the present invention is applied will be described with reference to FIG.

Figure 3 is a block diagram showing an example configuration of the internal combustion engine control device 30. As shown in Figure 3, the internal combustion engine control device 30, which is an ECU, has an input circuit 31, an input/output port 32, a CPU (Central Processing Unit) 33a, a RAM (Random Access Memory) 33c, and a ROM (Read Only Memory) 33b. The internal combustion engine control device 30 also has an oil jet control unit 36.

For example, the input circuit 31 receives an air flow rate signal from the air flow sensor 1 (see FIG. 1), an intake pressure signal from the intake pressure sensor 3, and a coil primary voltage or secondary voltage signal from a voltage sensor. The input circuit 31 also receives the crank angle (rpm) from the crank angle sensor 19, and oil pressure (oil pressure) and oil temperature (oil temperature) signals from the various sensors in the oil jet system 101. In addition to this information, the input circuit 31 also receives information measured by various sensors, such as the throttle opening and exhaust air-fuel ratio.

The input circuit 31 performs signal processing such as noise removal on the input signal and sends it to the input/output port 32. The value of the signal input to the input port of the input/output port 32 is temporarily stored in the RAM 33c.

ROM 33b stores a control program describing the contents of the various arithmetic processes executed by CPU 33a, as well as maps and data tables used for each process. The control program and the maps and data tables used for each process may be stored in non-volatile storage (not shown). RAM 33c is provided with a storage area for storing values input to the input port of input/output port 32 and values representing the amount of operation of each actuator calculated according to the control program. In addition, the values representing the amount of operation of each actuator stored in RAM 33c are sent to the output port of input/output port 32.

The amount of operation of the oil pump 54 set in the output port of the input/output port 32 is sent to the oil jet control unit 36. The oil jet control unit 36 generates a control signal based on the amount of operation of the oil pump 54, and a drive circuit (not shown) supplies a drive signal based on the control signal to the oil pump 54. In this way, the oil jet control unit 36 controls the pressure (hydraulic pressure) of the oil output by the oil pump 54, which supplies oil to the oil jet system 101 (see FIG. 1). The oil jet control unit 36 then controls the hydraulic pressure of the oil pump 54 to adjust the amount of oil sprayed from the oil jet system 101, thereby controlling the temperature change of the piston 21.

Note that actuators other than these are also used in the internal combustion engine 100, and the internal combustion engine control device 30 is equipped with an ignition control unit and a fuel injection control unit (not shown) that control these actuators, but their description will be omitted here. In this embodiment, an example has been described in which the internal combustion engine control device 30 is equipped with an oil jet control unit 36, but this is not limited to this. For example, the oil jet control unit 36 may be implemented in a control device other than the internal combustion engine control device 30.

[Overview of Control in Internal Combustion Engine Control Device]
Next, an overview of the control executed by the internal combustion engine control device 30 will be described with reference to FIG.
4 is a control block diagram showing an overview of the control executed by the internal combustion engine control device 30. In the internal combustion engine control device 30, the oil jet control unit 36 includes a piston crown surface temperature correlation index estimation unit 41 and an oil pressure setting unit 42. The CPU 33a (see FIG. 3) executes a control program recorded in the ROM 33b or the like, thereby realizing the function of each processing block.

[Piston crown surface temperature correlation index estimation unit]
The piston crown surface temperature correlation index estimation unit 41 (an example of a correlation index estimation unit) is a processing block that estimates a piston crown surface temperature correlation index that is correlated with the temperature of the piston 21 based on the operating condition parameters and oil jet parameters of the internal combustion engine 100. In the example of FIG. 4, the air flow rate of the intake pipe 6 and the engine speed (crank angle) are input as the operating condition parameters, and the discharge oil pressure of the oil pump 54 and the oil temperature of the oil jet are input as the oil jet parameters. For example, an oil temperature sensor is provided in an oil pan (not shown), and the oil temperature sensor measures the temperature of the oil flowing into the oil pan. The location where the oil temperature is measured is not limited to the oil pan, and may be a location closer to the oil pump 54.

For example, the piston crown surface temperature correlation index estimation unit 41 may estimate the piston temperature itself as the piston crown surface temperature correlation index. For example, the piston temperature change can be successively estimated from the balance between the energy input to the piston and the energy released. For example, the following equation 1 may be calculated. The energy is assumed to be thermal energy.

[Equation 1]
Tpis = (Tpis, 0)
+ (Qinp-(Qout, 1)-(Qout, oj)-(Qout, res))
÷ (MPIS x CPI)

Here, Tpis is the updated value (estimated value) of the piston temperature, and (Tpis, 0) is the current value of the piston temperature. Qinp is the energy [J] transferred from the combustion gas to the piston, and (Oout, l) is the energy [J] transferred from the piston to the cylinder liner through the piston ring and the piston skirt (the part in contact with the cylinder inner wall). (Qout, oj) is the energy [J] transferred from the piston to the oil jet, and (Qout, res) is the energy [J] flowing from the piston to the outside through the crankshaft, etc. Furthermore, Mpis is the mass of the piston (kg), and Cpis is the specific heat of the piston [J/kg/K]. For example, Qinp, (Qout, l), and (Qout, oj) can be calculated using the following

equations

2, 3, and 5.

[Equation 2]
Qinp = (Mdot, f) x Qf x ηpis x Δτ
[Equation 3]
(Qout, l) = Spl x λpl x ((Tpis, 0) - Tc) x Δτ
[Equation 4]
(Qout, oj) = Spo x hpis x ((Tpis, 0) - Toil) x Δτ

Here, (Mdot, f) is the fuel flow rate [kg/s], Qf is the lower heating value of the fuel [J], ηpis is the rate of energy transferred to the piston (-), and Δτ is the calculation period [s]. Spl is the contact area between the piston and the liner [m2], λpl is the thermal conductivity between the piston and the liner [W/(m K)], and Tc is the cooling water temperature [°C]. Spo is the contact area between the oil jet and the piston [m2], hpis is the heat transfer coefficient of the oil jet, and Toil is the oil temperature of the oil jet [°C].

Qf may be set in advance assuming gasoline, for example. Spl may be given as the contact area between the piston ring and the liner, and can be easily set based on geometric information such as the thickness of the piston ring and the bore diameter (for example, piston ring thickness x bore diameter x pi). Spo may be set based on geometric information of the piston (for example, bore diameter x bore diameter x pi ÷ 4). ηpis may be given as a map based on the operating conditions, piston temperature, cooling temperature, and oil temperature, and this map must be determined in advance by experiments and simulations. hpis is a parameter that depends on the oil jet shape and the oil jet flow rate. For this reason, hpis can be identified in advance by measurements such as experiments and simulations, and a map can be created. For example, the relationship between the oil pressure and the oil jet flow rate shown in Figure 5 and the relationship between the oil jet flow rate and the heat transfer coefficient hpis shown in Figure 6 are used.

5 is a map (graph) showing an example of the relationship between the oil pressure and the oil jet flow rate, in which the vertical axis represents the oil jet flow rate and the horizontal axis represents the oil pressure.
6 is a map showing an example of the relationship between the oil jet flow rate and the heat transfer coefficient hpis between the piston and the oil jet. The vertical axis of Fig. 6 represents the heat transfer coefficient (hpis), and the horizontal axis represents the oil jet flow rate.

As shown in FIG. 5, the oil jet flow rate is equal to or greater than 0 when the oil pressure is equal to or greater than the valve opening pressure of the valve 102, and the flow rate increases as the oil pressure increases. In addition, when compared at the same oil pressure, the higher the oil temperature, the lower the oil viscosity and the higher the oil jet flow rate. In addition, as shown in FIG. 6, the heat transfer coefficient hpis has a positive correlation with the oil jet flow rate. Therefore, the higher the oil jet flow rate, the higher the heat transfer coefficient hpis. The current oil jet flow rate can be calculated from the oil pressure, oil temperature, and the relationship shown in FIG. 5, and the heat transfer coefficient hpis can be calculated from the calculated oil jet flow rate and the relationship shown in FIG. 6. In addition, the fuel flow rate (Mdot, f) can be calculated from the air flow rate (Mdot, a) measured by the air flow sensor 1 and the exhaust air-fuel ratio AbF(-) detected by the air-fuel ratio sensor 9, for example, as shown in Equation 5.

[Equation 5]
(Mdot, f) = (Mdot, a) ÷ AbF
In this manner, the piston crown surface temperature correlation index can be calculated.

(Another calculation method for the piston crown surface temperature correlation index)
In addition, it is clear that the piston temperature has a qualitative tendency to rise as the combustion operation of the internal combustion engine continues and to fall when the combustion operation of the internal combustion engine stops. For this reason, the time during which the combustion operation of the internal combustion engine continues (combustion operation duration) may be used to calculate the piston crown surface temperature correlation index. For example, it can be given by the following formula.

[Equation 6]
tcomb = (tcomb, 0) + Δτ (during combustion operation)
[Equation 7]
tcomb = (tcomb, 0) - Δτstop (when fuel is cut, when the engine is stopped)

Here, tcomb is the updated value [s] of the time that the engine's combustion operation has continued, and (tcomb, 0) is the current value [s] of the time that the internal combustion engine 100's combustion operation has continued. Equation 7 is an equation that represents both the state immediately after the internal combustion engine 100 has stopped and the state after the internal combustion engine 100 has been stopped for a while. In addition, in the case of Equation 7, if the time after the internal combustion engine has stopped is long, the value of tcomb (combustion operation duration) will be negative, so as a general rule, tcomb ≧ 0.

Δτstop is a parameter that expresses the drop in piston temperature when fuel is cut or the engine is stopped as a decrease in the duration of combustion operation of the internal combustion engine. In other words, "-Δτstop" represents a temperature drop. In its simplest form, Δτstop may be set to the calculation period. In addition, since the drop in piston temperature is affected by fuel cut, engine stop, water temperature, and oil temperature, Δτstop can be given in a map with water temperature, oil temperature, and engine speed as its axes. The lower the water temperature and oil temperature, the larger Δτstop becomes, while the higher the engine speed, the larger Δτstop can be. This is to reflect the fact that the lower the water temperature and oil temperature, the more energy flows from the piston to the liner, and the more cooling progresses, and that the higher the engine speed, the more heat is transferred to the air introduced into the cylinder, and the more cooling of the piston.

The initial value of the duration of the combustion operation, which is necessary to calculate the duration of the engine combustion operation, can be set based on the oil temperature and water temperature at the time of engine start. For example, a reference value for the coolant temperature is set, and the initial value is set to 0 if the coolant temperature at the start of engine combustion is at the reference value. On the other hand, if the coolant temperature at the start of engine combustion is equal to or higher than the reference value, the initial value is set to a value greater than 0. Conversely, if the coolant temperature at the start of engine combustion is less than the reference value, the initial value is set to a value less than 0. By setting in this manner, it is possible to reproduce a state in which differences in the initial temperature result in differences in the time it takes to reach a predetermined temperature. The initial value of the duration of the combustion operation should also be determined in advance through simulations and engine operation tests.

(Another method of calculating the piston crown surface temperature correlation index)
In the process of the piston temperature rising, the greater the engine output (for example, engine torque or engine speed), the greater the amount of heat transfer to the piston, and the greater the temperature rise tends to be. In addition, because there is energy flowing from the piston to the oil due to the oil jet injection, it is better to reflect this effect as an index. It is difficult to reflect the operating conditions and the oil jet operating state in the above-mentioned combustion operation duration. Therefore, the formula for the combustion operation duration shown in Equation 6 is improved, and an index correlating with the piston crown surface temperature is defined as shown in the following Equation 8. As a result, while Equation 6 simply integrates the engine operation time, Equation 8 allows the influence of the operating conditions and the oil jet to be reflected by weighting the operating conditions and the presence or absence of the oil jet when integrating the operation time.

[Equation 8]
tcomb = (tcomb, 0) + (αout - αoj) Δτ (during combustion operation)

Here, tcomb is the updated value [s] of the index correlated with the piston crown temperature, (tcomb, 0) is the current value [s] of the index correlated with the piston crown temperature, and αout is a coefficient for reflecting the influence of operating conditions and is an index positively correlated with output. For example, the value of αout at the reference output can be set to 1, and αout can be set to a value positively correlated with output. Also, when the output is 0, the coefficient is set to a negative value. This makes it possible to express the change in the piston temperature that occurs when the engine is stopped or fuel is cut off. For example, if αout is set to -1 when the output is 0, then Equation 8 is equivalent to Equation 7.

Also, αoj is a coefficient for reflecting the influence of the oil jet, and is given as an index that has a positive correlation with the oil jet flow rate or oil pressure. For example, when the oil jet flow rate is 0, αoj is set to 0, and αoj is set in a proportional relationship to the oil jet flow rate. Furthermore, when the value of αoj is given based on the oil pressure, αoj is set to 0 when the oil pressure is less than the opening pressure of valve 102, and αoj is set in a positive correlation with the oil pressure when the oil pressure is equal to or greater than the opening pressure. This makes it possible to apply an index that is closer to the behavior of the piston temperature than the combustion operation duration (Equations 6 to 7), and that can be calculated more easily than the piston crown surface temperature estimation (Equations 1 to 5).

The temperature of the crown surface of the piston 21 may also be measured directly by providing a temperature sensor 105 for temperature measurement near the crown surface of the piston 21. Figure 1 shows an example in which the temperature sensor 105 is provided in a portion of the outer wall of the cylinder 14 that corresponds to the reciprocating motion area of the piston 21.

[Hydraulic pressure setting section]
The oil pressure setting unit 42 (see FIG. 4) is a processing block that sets the oil pressure generated by the variable displacement oil pump 54. The oil pressure setting unit 42 sets the oil pressure (target oil pressure) when oil jet injection is performed, based on the piston crown surface temperature correlation index estimated by the piston crown surface temperature correlation index estimation unit 41. The oil pressure is determined by the branching process shown in FIG. 9 based on the piston crown surface temperature correlation index, and as a result, the oil jet flow rate can be controlled.

In this way, in this embodiment, by providing the piston crown surface temperature correlation index estimation unit 41 and the oil pressure setting unit 42, it becomes possible to control the oil jet flow rate based on an index that is correlated with the piston crown surface temperature. In addition, the oil pressure setting unit 42 may be configured to use the measurement value of the temperature sensor 105 (see FIG. 1) as the piston crown surface temperature instead of the piston crown surface temperature correlation index.

[Engine operating time and THC emissions]
Here, the relationship between the engine operation time of the internal combustion engine and the amount of THC emissions will be described.
FIG. 7 is a diagram showing an example of the relationship between engine operation time [h] of an internal combustion engine and THC emission amount [ppmC]. The PN also shows the same tendency as the THC emission amount. As the engine operation time increases, substances (combustion products) derived from unburned or incomplete combustion of fuel or lubricating oil are deposited as deposits in the engine cylinder. The deposits repeatedly adhere to and peel off the walls of the combustion chamber, and the amount of deposits increases over time. When the deposits absorb the fuel or lubricating oil, partial misfires or incomplete combustion occurs, and the THC and PN emitted from the engine increase. FIG. 7 shows an example in which the THC emission amount increases from the initial value 701 as the engine operation time elapses, and the increase amount exceeds the allowable amount 702 of THC increase.

Deposits accumulate on the walls of the cylinder head 20, piston 21, cylinder 14, intake variable valve 5a, exhaust variable valve 5b, and fuel injector 13. The inner wall of the cylinder 14 is the sliding part with the piston 21, and near the ignition timing, the position of the piston 21 is close to top dead center. For this reason, the surface area of the inner wall of the cylinder 14, which forms the combustion chamber near the ignition timing, is smaller than the crown surface of the piston 21, and deposits are more likely to accumulate on the crown surface of the piston 21 than on the cylinder 14.

[Piston crown temperature and deposit amount]
Next, the relationship between the crown surface temperature of the piston 21, which is the main component on which deposits accumulate, and the amount of deposits will be described.
Fig. 8 is a diagram showing an example of the relationship between piston crown surface temperature [°C] and deposit accumulation amount [mg]. Note that Fig. 8 shows the deposit accumulation amount after the engine has been operated for a certain period of time. Deposits are likely to accumulate when the piston crown surface temperature is in a low temperature range 801 and when the piston crown surface temperature is in a high temperature range 803. Therefore, in order to suppress deposit accumulation, it is preferable to maintain the piston crown surface temperature of the piston 21 in a temperature range 802 between temperature ranges 801 and 803, where the deposit accumulation amount is "small". As a result, it is possible to suppress increases in THC and PN due to deposit accumulation.

In FIG. 8, an example is shown in which the lower limit temperature 805 of the temperature range 802 is set to approximately 150°C and the upper limit temperature 806 is set to approximately 215°C based on the deposit accumulation amount threshold value 804 (tolerance value). The deposit accumulation amount threshold value 804 (tolerance value) may be set in advance by the ECU 30 based on the allowable amount 702 of THC increase from the initial value 701 of the emission amount of exhaust gas regulated substances such as THC shown in FIG. 7.

[Operation of hydraulic pressure setting unit]
Next, the operation of the oil pressure setting section 42 of the internal combustion engine control device 30 will be described with reference to FIG.
FIG. 9 is a flowchart showing an example of the operation of the hydraulic pressure setting unit 42 of the internal combustion engine control device 30.

First, in step S901, the hydraulic pressure setting unit 42 determines whether the lubricity of the piston 21 and cylinder 14 has decreased, i.e., whether the piston lubricity is low. For example, if the duration of combustion operation of the internal combustion engine 100 calculated using

equations

6 and 7 is less than a predetermined value, it can be determined that the piston lubricity is low. If the determination in step S901 is YES, the hydraulic pressure setting unit 42 proceeds to step S902, and if the determination is NO, the hydraulic pressure setting unit 42 proceeds to step S903.

If the duration of the combustion operation of the internal combustion engine 100 is less than a predetermined value (YES judgment in S901), in step S902, the oil pressure setting unit 42 sets the target oil pressure of the oil pump 54 to an oil pressure at which oil jet injection is possible. The oil pressure at which oil jet injection is possible is determined according to the specifications of the oil jet nozzle and the valve 102 (see FIG. 1) and the oil temperature. Qualitatively, the lower the oil temperature, the higher the oil pressure at which oil jet injection is possible. The valve 102 is a check valve (non-return valve) that is configured to open when the oil pressure in the oil main gallery 110 reaches or exceeds a predetermined value. For example, a ball valve can be used as the valve 102.

Here, the relationship between the oil temperature and the oil jet injectable pressure will be described with reference to FIG.
10 is a map (graph) showing an example of the relationship between the oil temperature and the pressure at which the oil jet can be injected, in which the vertical axis represents the pressure at which the oil jet can be injected, and the horizontal axis represents the oil temperature.

As shown in FIG. 10, when the oil temperature is high, the injection pressure is determined by the valve opening pressure of the valve 102. At low temperatures, the oil viscosity increases, causing a large pressure loss in the oil jet nozzle, and the pressure required to eject oil from the nozzle tip may be much greater than the injection pressure (oil jet cut pressure Pc) determined by the valve 102. The oil pressure setting unit 42 determines the oil pressure setting value (target oil pressure 62) based on the current oil temperature and the relationship shown in FIG. 10. The target oil pressure 62 may be set to a value equal to or greater than the pressure at which the oil jet can be injected (oil jet injection pressure 61). Hereinafter, the mode in which the processing in step S902 is performed is referred to as the "lubrication mode".

By setting it in this way, the oil pressure setting unit 42 can determine when the piston lubricity is low and set the oil pressure at which the oil jet can be injected. Therefore, when the piston lubricity is low, the oil jet supplies oil to improve the lubricity, thereby reducing the deterioration of fuel consumption in a situation where the piston lubricity is low.

As described above, the oil pressure setting unit 42 is configured to set the target value of the oil pressure of the oil jet (oil jet system 101) to a pressure that allows oil jet injection, and to set a pressure that allows oil to be impregnated into each part of the internal combustion engine.

In addition, the hydraulic pressure setting unit 42 sets the target hydraulic pressure value of the oil jet (oil jet system 101) to a hydraulic pressure at which the oil jet injection can be stopped or at which the oil jet can be injected, based on the hydraulic pressure at which the hydraulic pressure-responsive valve 102 provided between the oil pump 54 and the oil jet nozzle opens and closes.

If the duration of combustion operation of the internal combustion engine 100 is equal to or longer than the predetermined value (NO in S901), in step S903 in FIG. 9, the oil pressure setting unit 42 determines whether the piston crown surface temperature correlation index is smaller than a first predetermined value. The first predetermined value is set to be the lower limit temperature 805 of the temperature range 802 in FIG. 6 where the amount of deposit accumulation is small.

In this way, when the crown surface temperature of the piston 21 is less than the first predetermined value, the oil pressure setting unit 42 sets the oil pressure of the oil jet (oil jet system 101) to a pressure at which the oil jet injection can be stopped.

If the crown surface temperature of the piston 21 is lower than the first predetermined value (YES in S903), the hydraulic pressure setting unit 42 proceeds to step S904. If the crown surface temperature of the piston 21 is equal to or higher than the first predetermined value (NO in S903), the hydraulic pressure setting unit 42 proceeds to step S905.

In step S904, the oil pressure setting unit 42 sets the target oil pressure of the oil pump 54 to a pressure at which the oil jet can be stopped, based on the relationship shown in FIG. 5. Specifically, the target oil pressure can be set to a pressure lower than the opening pressure of the valve 102 provided between the oil main gallery 110 and the oil jet nozzle. Thereafter, the mode in which the process in step S904 is performed after a YES determination in step S903 is referred to as the "warm-up promotion mode."

In step S905, the oil pressure setting unit 42 determines whether the crown surface temperature of the piston 21 is greater than a second predetermined value. If the crown surface temperature of the piston 21 is greater than the second predetermined value (YES judgment in S905), the oil pressure setting unit 42 proceeds to step S906. Then, in step S906, the oil pressure setting unit 42 sets the target oil pressure of the oil pump 54 to a pressure that allows oil jet injection, and performs control to suppress the crown surface temperature of the piston 21. The second predetermined value is set to be the upper limit temperature 806 of the temperature range 802 in FIG. 8 in which the amount of deposit accumulation is small.

On the other hand, if the crown surface temperature of the piston 21 is equal to or lower than the second predetermined value (NO in S905), the hydraulic pressure setting unit 42 proceeds to step S907 and determines whether the change over time in the crown surface temperature of the piston 21 is increasing. The ECU 30 stores in the RAM 33 the direction and amount of change in the crown surface temperature as the change over time in the crown surface temperature of the piston 21.

In step S907, if the change in the crown surface temperature of the piston 21 over time is increasing (YES in step S907), the hydraulic pressure setting unit 42 proceeds to step S908. Then, in step S908, the hydraulic pressure setting unit 42 controls the amount of oil in the oil jet (oil jet flow rate) to be greater than the amount of oil in the previous cycle, thereby lowering the temperature of the piston crown surface.

On the other hand, if the change over time in the crown surface temperature of the piston 21 is not increasing (is constant or is decreasing) (NO in step S907), the oil pressure setting unit 42 proceeds to step S904. Then, the oil pressure setting unit 42 increases the crown surface temperature of the piston 21 by setting an oil pressure that allows the oil jet to be stopped or by reducing the amount of oil (S904). Thereafter, the mode in which the processes in steps S905, S906, S907, S908, and S904 are performed is referred to as the "deposit suppression mode."

The deposit suppression mode makes it easier for the crown surface temperature of the piston 21 to be maintained between a first predetermined value (e.g., lower limit temperature 805) and a second predetermined value (e.g., upper limit temperature 806). As a result, the crown surface temperature of the piston 21 is maintained in the temperature range 802 where the amount of deposit accumulation is small, so that deposit accumulation is suppressed and an increase in THC and PN can be suppressed.

When the processing of step S902, S904, S906, or S908 is completed, this processing by the hydraulic pressure setting unit 42 ends. As shown in FIG. 12, the hydraulic pressure setting unit 42 can also be said to have a function of selecting one of the "lubrication mode," "warm-up promotion mode," and "deposit suppression mode" based on the piston crown surface temperature correlation index or the measured value of the piston crown surface temperature, and executing the selected mode.

For example, the hydraulic pressure setting unit 42 may select and execute the "warm-up promotion mode" within a first temperature state range that includes a temperature state of the piston crown surface that is identified in advance and in which the deposit accumulation amount on the piston crown surface becomes greater than a threshold value (threshold value 804), as shown by a solid line 1202 in FIG. 12 described later. The first temperature state range is a temperature range (temperature range 801 in FIG. 4) in which the piston crown surface temperature is lower than the lower limit (lower limit temperature 805) of the temperature state of the piston crown surface in which the deposit accumulation amount becomes less than the threshold value. When the piston crown surface temperature is within the first temperature state range in which the deposit accumulation amount becomes greater than the threshold value, the hydraulic pressure setting unit 42 selects the "warm-up promotion mode" and executes oil jet injection (S904). This makes it easier for the piston crown surface temperature to rise, and the residence time in the temperature range 801 in which the deposit accumulation amount becomes greater than the threshold value can be reduced. As a result, it is possible to suppress THC and PN.

The hydraulic pressure setting unit 42 also selects and executes the "deposit suppression mode" in the second temperature state (temperature ranges 802, 803 in FIG. 4) in which the temperature state of the piston crown surface is higher than the first temperature state range, as shown by the solid line 1202 in FIG. 12. In the deposit suppression mode in the second temperature state, when the temperature state of the piston crown surface is lower than the upper limit (upper limit temperature 806) of the temperature state of the piston crown surface at which the deposit accumulation amount on the piston crown surface is less than the threshold value (threshold value 804) that has been identified in advance (NO judgment in S905), the hydraulic pressure setting unit 42 reduces or blocks the oil jet flow rate (S904). However, when the temperature state of the piston crown surface is lower than the upper limit of the temperature state of the piston crown surface at which the deposit accumulation amount is less than the threshold value, and the time change of the piston crown surface temperature is on the rise (YES judgment in S907), the hydraulic pressure setting unit 42 increases the oil jet flow rate (S908).

On the other hand, if the temperature state of the piston crown surface is higher than the upper limit of the temperature state of the piston crown surface at which the amount of deposit accumulation becomes smaller than the threshold value (threshold value 804) (YES judgment in S905), the oil pressure setting unit 42 executes oil jet injection (S906). This control makes it easier to maintain the temperature of the piston crown surface within a temperature range (between the lower limit temperature 805 and the upper limit temperature 806) where the amount of deposit accumulation becomes smaller. This makes it possible to suppress deposit accumulation on the piston crown surface, and as a result, it is possible to reduce THC and PN.

Here, the control of oil jet injection (flow rate) has been explained using the solid line 1202 in Figure 12 as an example, but similar control is also possible using the dashed line 1201 in Figure 12.

As described above, the internal combustion engine control device (internal combustion engine control device 30) according to this embodiment is an internal combustion engine control device that controls an internal combustion engine (internal combustion engine 100) having an oil pump (oil pump 54) that discharges a specified flow rate of lubricating oil, and an oil jet system (oil jet system 101) that sprays the lubricating oil discharged from the oil pump toward the supplied portion (back surface) of the piston (piston 21). The internal combustion engine control device also includes a control unit (CPU 33a, oil jet control unit 36) that stops the injection of lubricating oil from the oil jet system or controls the flow rate of lubricating oil to be lower than the flow rate of the previous cycle when the temperature of the piston crown surface is below the lower limit temperature (lower limit temperature 805) of the temperature range (temperature range 802) in which the amount of deposits accumulated on the piston crown surface becomes less than the threshold value (threshold value 804) (corresponding to the accelerated warm-up mode).

The internal combustion engine control device according to the present embodiment described above executes control to inject lubricating oil from the oil jet or reduce the flow rate when the temperature of the piston crown surface is below the lower limit temperature of the temperature range in which the amount of deposits accumulated on the piston crown surface becomes less than a threshold value. This oil jet control allows the temperature of the piston crown surface to quickly pass through a temperature state in which the amount of deposits accumulated on the piston crown surface becomes greater than the threshold value, and to transition to a temperature range in which the amount of deposits accumulated is small. This makes it possible to suppress deposit accumulation and suppress emissions of exhaust gas regulated substances. In other words, it is possible to achieve both suppression of deposit accumulation and suppression of emissions of exhaust gas regulated substances.

The control unit (oil jet control unit 36) is configured to stop the injection of lubricating oil from the oil jet system or to control the flow rate of lubricating oil to be lower than the flow rate of the previous cycle when the temperature of the piston crown surface is equal to or higher than the lower limit temperature (lower limit temperature 805) and equal to or lower than the upper limit temperature (upper limit temperature 806) of the temperature range (temperature range 802) in which the amount of deposits accumulated on the piston crown surface becomes less than a threshold value (threshold value 804) (corresponding to the deposit suppression mode).

The oil jet control configured as above maintains the temperature of the piston crown surface within a temperature range that reduces the amount of deposit buildup, suppressing deposit buildup and preventing increases in THC and PN.

The control unit (oil jet control unit 36) is configured to increase the flow rate of lubricating oil from that of the previous cycle when the temperature of the piston crown surface is equal to or higher than the lower limit temperature (lower limit temperature 805) and equal to or lower than the upper limit temperature (upper limit temperature 806) of the temperature range (temperature range 802) in which the amount of deposits accumulated on the piston crown surface becomes less than a threshold value (threshold value 804) (corresponding to the deposit suppression mode), and when the temperature of the piston crown surface shows an increasing tendency over time.

The oil jet control configured as above maintains the temperature of the piston crown surface within a temperature range where the amount of deposit buildup is small, suppressing deposit buildup and suppressing increases in THC and PN. In particular, when the temperature of the piston crown surface shows an increasing trend over time, the amount of deposit buildup increases (see Figure 8), but by increasing the flow rate of the lubricating oil injected, the temperature rise of the piston crown surface can be prevented and the increase in the amount of deposit buildup can be suppressed.

The control unit (oil jet control unit 36) is configured to inject lubricating oil from the oil jet system when the temperature of the piston crown surface exceeds the upper limit temperature of the temperature range in which the amount of deposits accumulated on the piston crown surface is less than a threshold value (corresponding to the deposit suppression mode).

The above-described oil jet control quickly reduces the temperature of the piston crown surface, and by keeping the piston crown surface temperature within the temperature range where the amount of deposit buildup is small, deposit buildup is suppressed and an increase in THC and PN is suppressed.

The control unit (oil jet control unit 36) is configured to determine the lubricity between the piston and the cylinder of the internal combustion engine before comparing the temperature of the piston crown surface with the lower limit temperature (lower limit temperature 805) of the temperature range (temperature range 802) in which the amount of deposits accumulated on the piston crown surface becomes smaller than a threshold value (threshold value 804), and to execute the injection of lubricating oil from the oil jet system if it is determined that the lubricity is insufficient (corresponding to the lubrication mode).

The oil jet control configured as above can improve the lubrication between the piston and the cylinder of the internal combustion engine, thereby reducing the deterioration of fuel consumption in situations where the piston lubrication is low.

The temperature of the piston crown surface is a piston crown surface temperature correlation index that is correlated with the temperature of the piston crown surface and is estimated based on the operating condition parameters of the internal combustion engine and the oil jet parameters for injecting lubricating oil onto the back surface of the piston, or is a measurement value of a temperature sensor (temperature sensor 105) that measures the temperature of the piston crown surface.

Second Embodiment
The second embodiment of the present invention is an example in which the controllability of the piston crown surface temperature is enhanced by improving the piston 21 in the internal combustion engine 100 of the first embodiment. Hereinafter, the configuration of a control system in the second embodiment of the present invention will be described with reference to Figs. 11 and 12.

FIG. 11 is a schematic diagram showing an example of the configuration of a piston in this embodiment.
Fig. 12 is a diagram showing time series changes in vehicle speed [km/h], oil jet flow rate ("OJ flow rate" in the figure) [L/min], piston crown surface temperature [°C], and oil temperature [°C] at engine start in this embodiment. In Fig. 12, the oil jet flow rate, piston crown surface temperature, and oil temperature are shown by dashed lines 1201 for the first embodiment and by solid lines 1202 for the second embodiment. In Fig. 12, (1) lubrication mode, (2) warm-up promotion mode, and (3) deposit suppression mode are assumed to be examples applied to the second embodiment.

The piston 21A according to the second embodiment differs from the piston 21 according to the first embodiment in that the piston 21A includes a base material 1101 and a piston crown surface 1102 made of a material having a lower thermal conductivity than the base material 1101 and facing the combustion chamber of the internal combustion engine 100.

11 and 12, the action and effect of using the piston 21A in the second embodiment will be described. By providing the piston crown surface 1102 with a material having a lower thermal conductivity than the base material 1101, it is possible to suppress heat escaping from the combustion chamber to the lubricating oil through the base material 1101 of the piston 21A and the piston rings arranged on the side of the piston 21A. As a result, as shown at time 1203 in FIG. 12, it is possible to increase the rate of temperature rise of the piston crown surface 1102 at engine start more quickly than in the first embodiment. As a result, the time until the lower limit temperature 805 (see FIG. 8) at which the amount of deposit accumulation becomes small can be shortened from time 1204 to time 1205. Since the engine repeatedly stops and starts, according to the configuration of the piston 21A in the second embodiment, the time during which the piston crown surface temperature stays in the temperature range 802 at which the amount of deposit accumulation becomes small can be increased more than in the first embodiment, and as a result, the accumulation of deposits can be suppressed. As a result, the increase in THC and PN can be suppressed.

In addition, the value of the thickness 1104 of the piston crown surface 1102, which is provided with a material having a lower thermal conductivity than the base material 1101, should be set sufficiently smaller than the thickness 1103 of the base material 1101. Since the thermal conductivity is determined by the "heat transfer coefficient" and "heat capacity" of the material, by reducing the value of the thickness 1104 of the piston crown surface 1102, the temperature of the piston crown surface 1102 is more likely to increase. This makes it possible to increase the time that the piston crown surface temperature remains in the temperature range 802 where the amount of deposit accumulation is small, thereby suppressing the accumulation of deposits. In order to reduce the value of the thickness of the piston crown surface 1102, the piston crown surface 1102 may be formed by coating the base material 1101.

In the piston 21A, for example, aluminum is used for the base material 1101 and a ceramic material is used for the piston crown surface 1102, and the thermal conductivity of the base material 1101 is set to 135 [W/mK] and the thermal conductivity of the piston crown surface 1102 is set to 10 [W/mK] or less. In this way, by designing the thermal conductivity of the piston crown surface 1102 to be sufficiently smaller than that of the base material 1101, the temperature rise rate of the piston crown surface 1102 can be increased, and the effect of suppressing deposit accumulation can be improved.

Furthermore, by using the configuration and control in the second embodiment for the oil temperature of the oil jet, the timing for starting oil jet injection or increasing the amount of oil in the oil jet can be advanced after the warm-up promotion mode. By injecting the oil jet onto the underside of the piston 21A, heat is transferred from the piston 21A to the lubricating oil, and the rate at which the oil temperature rises increases. As a result, it is possible to advance the time until the oil jet is stopped or the oil temperature of the oil jet reaches the warm-up judgment temperature Twj from time 1206 to time 1207. The warm-up judgment temperature Twj is a temperature threshold for determining that the internal combustion engine 100 has warmed up to a set temperature. As a result, the fuel injected into the engine cylinder is more likely to vaporize, and the effect of suppressing THC and PN is improved.

<Modification of the second embodiment>
In addition, in the control system according to the second embodiment, the oil pressure setting unit 42, which selects one of the “lubrication mode”, the “warm-up promotion mode”, and the “deposit suppression mode”, may have a function of executing the selected mode by taking into account the thermal conductivity of the piston crown surface to the measured value of the piston crown surface temperature correlation index or the piston crown surface temperature.

For example, after the oil jet is turned on, there is a time delay depending on the thermal conductivity (heat transfer rate and heat capacity) of the piston crown surface 1102 until the temperature of the piston crown surface 1102 drops. For this reason, it is advisable to predict the piston crown surface temperature in advance by taking into account the thermal conductivity in the temperature change of the piston 21A, and select one of the "lubrication mode," "warm-up promotion mode," or "deposit suppression mode" depending on the predicted value of the piston crown surface temperature.

As a result, in this embodiment, it becomes easier to control the crown surface temperature of the piston 21 within a specified range, and the effect of suppressing THC and PN can be improved. In other words, the oil jet is switched earlier or later, taking into account the delay in the effect of increasing or decreasing the oil jet. For example, when the thermal conductivity is greater than a specified value, the temperature change of the piston crown surface is fast, so the oil jet is turned ON/OFF or the flow rate is switched later. Also, when the thermal conductivity is equal to or less than the specified value, the temperature change of the piston crown surface is gradual, so the oil jet is turned ON/OFF or the flow rate is switched earlier.

In one example of the control system in the second embodiment, when the temperature of the piston crown surface 1102 reaches the upper limit temperature 806 at which the amount of deposit accumulation becomes small, the oil jet flow rate is increased to cool the piston 21A. However, there is a delay due to the thermal conductivity between the time when the oil jet flow rate is increased (e.g., time 1208) and the time when the temperature of the piston crown surface of the piston 21A actually starts to decrease (e.g., time 1209).

Therefore, the change in piston crown surface temperature over time is stored in the ECU 30. Then, the oil pressure setting unit 42 takes into account the time delay due to thermal conductivity and increases the oil jet flow rate in advance when it is predicted that the piston crown surface temperature after a certain time period calculated from the change in piston crown surface temperature over time will exceed the upper limit temperature 806 at which the amount of deposit accumulation becomes small. This makes it possible to shorten the time during which the piston crown surface temperature exceeds the upper limit temperature 806 at which the amount of deposit accumulation becomes small, thereby suppressing the accumulation of deposits.

In addition, if it is predicted that the piston crown surface temperature will fall below the lower limit temperature 805 at which the amount of deposit accumulation becomes small, it is advisable to reduce the oil jet flow rate in advance or to stop the oil jet. This makes it possible to shorten the time that the piston crown surface temperature falls below the lower limit temperature 805 at which the amount of deposit accumulation becomes small, thereby suppressing the accumulation of deposits.

Here, the control of the oil jet flow rate has been explained using the second embodiment (solid line 1202 in FIG. 12) as an example, but similar control is also possible in the first embodiment (dashed line 1201).

Third Embodiment
The third embodiment of the present invention is an example of controlling the ignition timing of the mixture in the combustion chamber based on mode information notified from the oil jet control unit 36. Hereinafter, the configuration of the control system in the third embodiment of the present invention will be described with reference to Figures 13 and 14.

FIG. 13 is a block diagram showing an example of the configuration of an internal combustion engine control device according to this embodiment. As shown in FIG. 13, the internal combustion engine control device 30A according to this embodiment has a configuration in which an ignition timing control unit 1300 is added to the internal combustion engine control device 30 according to the first embodiment. The functions of each processing block are realized by the CPU 33a executing a control program recorded in the ROM 33b, etc.

The piston crown surface temperature correlation index estimation unit 41 and the oil pressure setting unit 42 have the same functions as the piston crown surface temperature correlation index estimation unit 41 and the oil pressure setting unit 42 (Figure 4) according to the first embodiment.

The ignition timing control unit 1300 adjusts the timing of sending an ignition signal to the ignition coil 16 based on the mode information (or the state of the piston crown surface temperature) notified by the oil jet control unit 36, and controls the ignition timing of the air-fuel mixture.

FIG. 14 is a control block diagram showing an overview of the control executed by the internal combustion engine control device 30A. When the mode information notified from the hydraulic pressure setting unit 42 is "(2) warm-up promotion mode", the ignition timing control unit 1300 performs control to raise the piston crown surface temperature by advancing or retarding the ignition timing of the air-fuel mixture, which is set based on the load of the internal combustion engine 100. The load information of the internal combustion engine 100 is, for example, the intake flow rate and the engine speed.

If the ignition timing is advanced beyond the time when fuel economy is optimal, i.e., the optimal ignition timing when the combustion speed is faster, the cylinder pressure increases, causing the temperature inside the cylinder to rise, and the amount of heat that moves from inside the cylinder to the piston crown surface increases. This causes the piston crown surface temperature to rise, and the time it takes for the piston crown surface temperature to reach the lower limit temperature 805 can be shortened. As a result, the effect of reducing THC and PN is greater.

In addition, when the piston crown surface temperature exceeds the upper limit temperature 806 in the "(3) deposit suppression mode" and subsequent modes shown in FIG. 12, the amount of heat transferred from inside the cylinder to the piston crown surface can be suppressed by retarding the ignition timing from the optimal ignition timing. This shortens the time it takes for the piston crown surface temperature to fall below the upper limit temperature 806, thereby enhancing the deposit suppression effect.

When the mode information notified from the hydraulic pressure setting unit 42 is "(3) deposit suppression mode", the ignition timing control unit 1300 adjusts the piston crown surface temperature by advancing or retarding the ignition timing of the air-fuel mixture, which is set based on the load of the internal combustion engine 100. The load information of the internal combustion engine 100 is, for example, the intake air flow rate and the engine speed. For example, when a high engine speed is required, the ignition timing is advanced to quickly increase the engine speed. Also, when a high engine speed is not required, the ignition timing is retarded to quickly reduce the engine speed. This makes it easier to change the piston crown surface temperature, and the time during which the piston crown surface temperature is in the temperature range where deposits are small can be extended. This suppresses deposits and enhances the effect of reducing THC and PN.

As described above, the internal combustion engine control device (internal combustion engine control device 30A) according to this embodiment includes an ignition timing control unit (ignition timing control unit 1300) that advances the ignition timing, which is set based on the load of the internal combustion engine, when the temperature of the piston crown surface is below the lower limit temperature (lower limit temperature 805) of the temperature range in which the amount of deposits on the piston crown surface becomes less than the threshold value (threshold value 804). For example, the ignition timing is the optimal ignition timing that increases the combustion speed of the mixture in the combustion chamber.

The internal combustion engine control device (internal combustion engine control device 30A) according to this embodiment also includes an ignition timing control unit (ignition timing control unit 1300) that advances or retards the ignition timing, which is set based on the load of the internal combustion engine, when the temperature of the piston crown surface is equal to or higher than the lower limit temperature (lower limit temperature 805) of the temperature range in which the amount of deposits on the piston crown surface becomes smaller than a threshold value (threshold value 804). For example, the ignition timing control unit advances the ignition timing when the target rotation speed of the internal combustion engine is higher than a first rotation speed, and retards the ignition timing when the target rotation speed of the internal combustion engine is lower than a second rotation speed that is lower than the first rotation speed.

Fourth Embodiment
The fourth embodiment of the present invention is an example in which an oil jet control unit includes a mode selection unit in addition to the oil pressure setting unit 42. Hereinafter, the configuration of a control system in the fourth embodiment of the present invention will be described with reference to FIG.

FIG. 15 is a block diagram showing an overview of the control of the internal combustion engine control device according to this embodiment. As shown in FIG. 15, the oil jet control unit 36A according to this embodiment includes a piston crown surface temperature correlation index estimation unit 41, a mode selection unit 1500, and an oil pressure setting unit 42A. The CPU 33a executes a control program recorded in the ROM 33b or the like to realize the functions of each processing block.

The piston crown surface temperature correlation index estimation unit 41 has the same function as the piston crown surface temperature correlation index estimation unit 41 (FIG. 4) according to the first embodiment. The piston crown surface temperature correlation index estimation unit 41 sends the estimated piston crown surface temperature correlation index to the hydraulic pressure setting unit 42A and the mode selection unit 1500.

The mode selection unit 1500 selects one of the "lubrication mode," "warm-up promotion mode," or "deposit suppression mode" based on the piston crown surface temperature correlation index or the measured value of the piston crown surface temperature, and sends the selection result (mode information) to the hydraulic pressure setting unit 42A. As in the first embodiment, the mode selection unit 1500 may determine that the piston lubricity is low when the duration of combustion operation of the internal combustion engine 100 is less than a predetermined value, and select the "lubrication mode." Furthermore, when the duration of combustion operation is equal to or greater than a predetermined value, the mode selection unit 1500 selects the "warm-up promotion mode" or the "deposit suppression mode" based on the piston crown surface temperature.

The hydraulic pressure setting unit 42A has the functions of the hydraulic pressure setting unit 42 according to the first embodiment, excluding the mode selection function. The hydraulic pressure setting unit 42A sets the hydraulic pressure (target hydraulic pressure) when performing oil jet injection according to the flowchart of FIG. 9, based on the measured value of the piston crown surface temperature correlation index or the piston crown surface temperature, and the mode information notified from the mode selection unit 1500.

<Modification of the Fourth Embodiment>
The mode selection unit 1500 may have a function of selecting a mode by taking into consideration the thermal conductivity to the piston crown surface temperature correlation index or the piston crown surface temperature, similarly to the hydraulic pressure setting unit 42 according to the modified example of the second embodiment. This makes it easier to control the piston crown surface temperature of the piston 21 within a predetermined range, and enhances the effect of suppressing THC and PN, also in this embodiment.

<Examples of vehicles equipped with the control system>
The control system in each of the above-mentioned embodiments is effective for an internal combustion engine equipped with an engine, but may also be used for a series hybrid that uses the engine as a generator, or a PHEV (Plug-in Hybrid Electric Vehicle) that can select the timing of using the engine. Compared to an internal combustion engine equipped with an engine, a series hybrid or a PHEV can secure the power for running the vehicle with an electric motor, so that the start timing of the internal combustion engine can be set arbitrarily by combining it with the present invention. For example, if the piston crown surface temperature rises too much beyond the upper limit temperature 806, in the case of a series hybrid or a PHEV, the engine can be stopped (idling stop) to suppress the amount of deposit accumulation and the increase in THC and PN.

Furthermore, the present invention is not limited to the above-described embodiments, and of course various other applications and modifications are possible without departing from the gist of the present invention as set forth in the claims. For example, the above-described embodiments are described in detail and specifically to clearly explain the present invention, and are not necessarily limited to those including all of the components described. It is also possible to replace part of the configuration of one embodiment with a component of another embodiment. It is also possible to add components of another embodiment to the configuration of one embodiment. It is also possible to add, replace, or delete other components from part of the configuration of each embodiment.

Furthermore, the above-mentioned configurations, functions, processing units, etc. may be realized in part or in whole in hardware, for example by designing them as integrated circuits. As hardware, broad processor devices such as FPGAs (Field Programmable Gate Arrays) and ASICs (Application Specific Integrated Circuits) may be used.

In addition, in the above-described embodiment, the control lines and information lines are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are connected to each other.

The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

21, 21A...piston, 30, 30A...internal combustion engine control unit (ECU), 36, 36A...oil jet control unit, 41...piston crown surface temperature correlation index estimation unit, 42, 42A...oil pressure setting unit, 54...oil pump, 101...oil jet system, 701...initial value, 702...increase amount, 801-803...temperature range, 804...threshold value, 805...lower limit temperature, 806...upper limit temperature, 1101...base material, 1102...piston crown surface, 1300...ignition timing control unit

Claims

An internal combustion engine control device for controlling an internal combustion engine having an oil pump that discharges a specified flow rate of lubricating oil and an oil jet system that injects the lubricating oil discharged from the oil pump toward a portion of a piston that is supplied with the lubricating oil,
An internal combustion engine control device comprising: a control unit that stops injection of the lubricating oil from the oil jet system or controls the flow rate of the lubricating oil to be lower than the flow rate in a previous cycle when the temperature of a piston crown surface is lower than a lower limit temperature of a temperature range in which an amount of deposits accumulated on the piston crown surface becomes smaller than a threshold value.
2. The internal combustion engine control device according to claim 1, wherein the control unit stops injection of the lubricating oil from the oil jet system or controls the flow rate of the lubricating oil to be lower than the flow rate in the previous cycle when the temperature of the piston crown surface is equal to or higher than a lower limit temperature and equal to or lower than an upper limit temperature of a temperature range in which the amount of deposits accumulated on the piston crown surface becomes smaller than the threshold value.
3. The internal combustion engine control device according to claim 2, wherein the control unit increases the flow rate of the lubricating oil to be greater than or equal to a lower limit temperature and less than or equal to an upper limit temperature of a temperature range in which a deposit accumulation amount on the piston crown surface becomes smaller than the threshold value and when a time change in the temperature of the piston crown surface shows an increasing tendency.
The internal combustion engine control device according to claim 3 , wherein the control unit executes injection of the lubricating oil from the oil jet system when the temperature of the piston crown surface exceeds an upper limit temperature of a temperature range in which an amount of deposits accumulated on the piston crown surface becomes smaller than the threshold value.
2. The internal combustion engine control device according to claim 1, wherein the control unit determines a lubrication between the piston and a cylinder of the internal combustion engine before comparing the temperature of the piston crown surface with a lower limit temperature of the temperature range at which the amount of deposit accumulation on the piston crown surface becomes smaller than the threshold value, and when it determines that the lubrication is insufficient, executes injection of the lubricating oil from the oil jet system.
The internal combustion engine control device according to claim 1 , wherein the piston comprises: a base material that forms the supplied portion; and the piston crown surface that faces a combustion chamber of the internal combustion engine and is made of a material having a lower thermal conductivity than the base material.
7. The internal combustion engine control device according to claim 6, wherein the control unit predicts a temperature of the piston crown surface by taking into account a thermal conductivity of the piston crown surface in relation to a temperature change of the piston crown surface, and controls injection of the lubricating oil from the oil jet system based on a predicted value of the temperature of the piston crown surface.
The oil pump is
2. The internal combustion engine control device according to claim 1, wherein the variable displacement pump comprises: a pump housing having an accommodation portion; a rotor that is disposed within the accommodation portion and is connected to a rotating shaft of the internal combustion engine so as to be capable of transmitting driving force; a cam ring whose eccentricity between a center of rotation of the rotor and its own center changes between a high discharge rate position and a low discharge rate position; and a control valve portion that changes the eccentricity of the cam ring under the control of the control portion.
an ignition timing control unit that advances an ignition timing that is set based on a load of the internal combustion engine when the temperature of the piston crown surface is lower than a lower limit temperature of a temperature range in which an amount of deposits accumulated on the piston crown surface becomes smaller than a threshold value,
2. The internal combustion engine control device according to claim 1, wherein the ignition timing is an optimum ignition timing that increases the combustion speed of the air-fuel mixture in the combustion chamber.
an ignition timing control unit that advances or retards an ignition timing that is set based on a load of the internal combustion engine when the temperature of the piston crown surface is equal to or higher than a lower limit temperature of a temperature range in which an amount of deposits on the piston crown surface becomes smaller than the threshold value,
3. The internal combustion engine control device according to claim 2, wherein the ignition timing control unit advances the ignition timing when the target rotation speed of the internal combustion engine is higher than a first rotation speed, and retards the ignition timing when the target rotation speed of the internal combustion engine is lower than a second rotation speed that is lower than the first rotation speed.
The internal combustion engine control device according to claim 1 , wherein the threshold value of the deposit amount is set based on an allowable increase from an initial value of the emission amount of the exhaust gas regulated substance.
2. The internal combustion engine control device according to claim 1, wherein the temperature of the piston crown surface is a piston crown surface temperature correlation index having a correlation with the temperature of the piston crown surface, the correlation index being estimated based on an operating condition parameter of the internal combustion engine and an oil jet parameter for injecting the lubricating oil onto a back surface of the piston, or a measurement value of a temperature sensor that measures the temperature of the piston crown surface.
1. An internal combustion engine control method for an internal combustion engine having an oil pump that discharges a specified flow rate of lubricating oil and an oil jet system that injects the lubricating oil discharged from the oil pump toward a portion of a piston that is supplied with the lubricating oil, comprising:
A process of determining whether a temperature of a piston crown surface is less than a lower limit temperature of a temperature range in which an amount of deposits accumulated on the piston crown surface becomes less than a threshold value;
When the temperature of the piston crown surface is lower than a lower limit temperature of the temperature range in which the deposit accumulation amount becomes smaller than the threshold value, the injection of the lubricating oil from the oil jet system is stopped or the flow rate of the lubricating oil is reduced below the flow rate of the previous cycle.