Internal combustion engine control device and internal combustion engine control method

Abstract

This internal combustion engine control device is provided with: a correlation index estimation unit that estimates a piston temperature correlation index having a correlation with the temperature of a piston, on the basis of an internal combustion engine operating condition parameter and an oil jet parameter for jetting oil to a rear surface of the piston; a hydraulic pressure setting unit that sets the hydraulic pressure of an oil jet on the basis of the piston temperature correlation index and a vaporization parameter of fuel that attaches to the piston. If the piston temperature correlation index is less than a first prescribed value which is determined, as the vaporization parameter, on the basis of a temperature corresponding to a fuel vaporizable condition, then the hydraulic pressure setting unit sets the hydraulic pressure of the oil jet at a hydraulic pressure at which jetting of the oil jet can be stopped.

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine control device and an internal combustion engine control method for operating various actuators of an internal combustion engine. [Background technology]

[0002] Typically, an internal combustion engine mounted on a vehicle operates according to the operation amounts of various actuators that are adapted to specific environmental conditions such as temperature, humidity, and atmospheric pressure. For example, when driving on an actual road, the vehicle may be driven under conditions that are different from the environmental conditions and the state (operating conditions) of the internal combustion engine assumed at the time of adaptation. These environmental conditions are detected using various sensors, and the operation amounts are corrected according to the detected conditions.

[0003] Furthermore, when driving on an actual road, it is not only the environmental conditions that differ from the adaptation conditions, but also the state of the internal combustion engine itself (for example, the combustion chamber wall temperature, coolant temperature, and parts) that change, causing deviations from the state assumed at the time of adaptation. For this reason, in order to improve various performance aspects of a vehicle when driving on an actual road (fuel economy, exhaust performance), it is important to estimate and detect the state of the internal combustion engine, understand the state of the internal combustion engine while driving, and operate the actuator according to the understood state of the internal combustion engine.

[0004] The temperature of the combustion chamber wall (wall surface temperature) is a condition that affects the performance of an internal combustion engine. Here, the wall surface temperature refers to the temperature of the walls that make up the combustion chamber, such as the head portion of the combustion chamber, the liner portion of the combustion chamber, and the piston.

[0005] Wall temperature is a physical quantity related to the actuator operation amount, which affects fuel economy and exhaust performance. For example, when the wall temperature is high, gases near the wall surface are heated more, making abnormal combustion (knocking) more likely to occur. For this reason, it is necessary to devise actuator operation methods to prevent a deterioration in combustion efficiency. On the other hand, when the wall temperature is low, fuel adhering to the wall surface is more likely to remain liquid, which can lead to the generation of unburned hydrocarbons and soot, which can worsen exhaust performance.

[0006] For example, Patent Document 1 discloses a technique for estimating the piston surface temperature and controlling an actuator provided in an internal combustion engine. Patent Document 1 proposes a method for controlling the piston temperature by activating an oil jet that sprays oil onto the back surface of the piston when the piston surface temperature is equal to or higher than a predetermined threshold temperature based on the 90% distillation temperature of the fuel. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-64374 Summary of the Invention [Problem to be solved by the invention]

[0008] The technology described in Patent Document 1 stops the oil jet when the piston surface temperature is below a predetermined threshold temperature based on the 90% distillation temperature of the fuel, thereby promoting an increase in piston temperature, suppressing the amount of fuel remaining on the piston surface, and reducing particulate matter emissions. Meanwhile, since the 90% distillation temperature of fuel is set at 180°C or lower in the JIS standard, it is considered that the piston surface temperature is typically at least 100°C or higher during operation. Therefore, by defining a predetermined temperature threshold based on the 90% distillation temperature and specifying the operation and stop of the oil jet, it is expected that the oil jet will remain stopped for a long period of time from startup.

[0009] Stopping the oil jet reduces the amount of energy flowing from the piston to the oil. As a result, the engine oil temperature rises more slowly, and it is possible that the potential for improvement in fuel consumption is not being fully realized. In other words, the lower the engine oil temperature, the higher the viscosity of the engine oil, which may result in a loss of fuel efficiency due to friction between the combustion chamber liner and the piston.

[0010] In view of the above circumstances, there has been a demand for a method for controlling the energy transmitted to the piston and engine oil, thereby improving the exhaust performance and fuel economy of an internal combustion engine. [Means for solving the problem]

[0011] In order to solve the above problem, an internal combustion engine device according to one aspect of the present invention comprises: An internal combustion engine control device for controlling a valve via the oil pressure of an oil pump for an internal combustion engine equipped with a variable displacement oil pump, an oil jet for injecting oil discharged from the oil pump onto the back surface of a piston, and a valve provided between the oil pump and the oil jet in response to the oil pressure of the oil pump, Operating condition parameters and oil Pump oil pressure and oil temperature a correlation index estimating unit that estimates a piston temperature correlation index that has a correlation with the temperature of the piston based on the piston temperature correlation index and an evaporation parameter of fuel adhering to the piston; The oil jet injection pressure is the threshold of the oil pressure at which the valve opens and injection is possible. Based on oil pump Hydraulic pressure Target value and a hydraulic pressure setting unit for setting the hydraulic pressure. do. The oil pressure setting unit sets the oil pressure when the piston temperature correlation index is less than a first predetermined value determined based on a temperature corresponding to a fuel evaporation condition as an evaporation parameter. pump Hydraulic pressure Target value Oil jet injection Less than the available pressure Set to hydraulic pressure When the piston temperature correlation index is equal to or greater than a first predetermined value and the oil temperature is less than a second predetermined value at which the engine is considered to be in a warmed-up state, the target oil pressure of the oil pump is set to an oil pressure equal to or greater than the pressure at which oil jet injection is possible. Furthermore, the oil pressure setting unit predicts the piston temperature correlation index when the target value of the oil pump oil pressure is set to an oil pressure equal to or higher than the oil jet injection pressure, and determines the target value of the oil pump oil pressure within a range in which the piston temperature correlation index does not fall below the first predetermined value based on the prediction. do. [Effects of the Invention]

[0012] According to at least one aspect of the present invention, the oil jet injection amount is appropriately controlled by controlling the oil pressure of the oil jet based on the operating conditions that affect the piston wall temperature and the piston temperature, thereby controlling the amount of energy flowing to the piston and engine oil, thereby achieving improvements in the exhaust performance and fuel economy of the internal combustion engine. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing an example of a system configuration of an internal combustion engine equipped with an internal combustion engine control device according to an embodiment of the present invention; [Figure 2]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. [Figure 3] 1 is a block diagram showing an example of the configuration of an internal combustion engine control device to which the present invention is applied; [Figure 4] 1 is a control block diagram showing an overview of control executed by an internal combustion engine control device according to an embodiment of the present invention; [Figure 5] 10 is a map (graph) showing an example of the relationship between oil pressure and oil jet flow rate. [Figure 6] 10 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. [Figure 7] 4 is a flowchart showing an example of the operation of a hydraulic pressure setting unit of the internal combustion engine control device according to one embodiment of the present invention. [Figure 8] 1 is a map (graph) showing an example of the relationship between oil temperature and oil jet injection possible pressure. [Figure 9] FIG. 4 is a diagram showing the correlation between piston temperature and knocking frequency or knocking intensity. [Figure 10] FIG. 10 is a diagram showing conditions for the occurrence of knocking on a map with engine speed and engine torque as axes. [Figure 11] 4 is a timing chart showing an example of the behavior of various parameters due to hydraulic control by the internal combustion engine control device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, examples of embodiments of the present invention will be described with reference to the accompanying drawings. In this specification and the accompanying drawings, components having substantially the same functions or configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0015] <Configuration of an internal combustion engine> First, an example of the configuration of an internal combustion engine will be described. Fig. 1 shows a schematic diagram illustrating the system configuration of an internal combustion engine. The 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.

[0016] 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 a multi-cylinder engine having, for example, four cylinders. The number of cylinders that the internal combustion engine 100 has is not limited to four, and the internal combustion engine 100 may have six, eight, or more cylinders. The number of cycles of the internal combustion engine 100 is not limited to four.

[0017] 1, an internal combustion engine 100 includes an air flow sensor 1, an electronically controlled throttle valve 2, an intake pressure sensor 3, a compressor 4a, an intercooler 7, and a cylinder 14. The air flow sensor 1, the electronically controlled throttle valve 2, the intake pressure sensor 3, the compressor 4a, and the intercooler 7 are arranged in an intake pipe 6 at positions up to the cylinder 14.

[0018] Furthermore, 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 accelerator operation by the driver. This adjusts the volume of intake air and the pressure in the intake pipe 6. The intake pressure sensor 3 measures the pressure in the intake pipe 6.

[0019] The compressor 4a compresses the intake air to be supercharged in the supercharger. Rotational force is transmitted to the compressor 4a by a turbine 4b (described later). The intercooler 7 is disposed upstream of the cylinder 14 and cools the intake air.

[0020] The internal combustion engine 100 is also provided with an ignition device for each cylinder 14, which includes a fuel injector 13 that injects fuel into the cylinder 14, and an ignition device that includes an ignition coil 16 and a spark plug 17 that supply ignition energy. Under the control of an internal combustion engine control device 20, 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 combusts and explodes the air-fuel mixture in the cylinder. For example, an ECU (Engine Control Unit) can be used as the internal combustion engine control device 20.

[0021] 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. Voltage information measured by the voltage sensor is sent to the internal combustion engine control device 20.

[0022] Additionally, variable valves 5a and 5b are provided in the cylinder head of cylinder 14. Variable valve 5a adjusts the air-fuel mixture flowing into cylinder 14, while variable valve 5b adjusts the exhaust gas discharged from cylinder 14. By adjusting variable valves 5a and 5b, the intake air volume and internal EGR (Exhaust Gas Recirculation) volume of all cylinders 14 can be adjusted.

[0023] Furthermore, a piston is slidably disposed within the cylinder 14. The piston compresses the mixture of fuel and gas that flows into the cylinder 14. The piston 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. Crank angle information (rotation information) measured by the crank angle sensor 19 is sent to an internal combustion engine control device 20.

[0024] The fuel injection device 13 is controlled by an internal combustion engine control unit 20 (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 pressurized 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 a fuel pipe connecting the fuel injection device 13 and the high-pressure fuel pump.

[0025] Additionally, a temperature sensor 18 is provided in the cylinder 14. The temperature sensor 18 measures the temperature of the coolant circulating through the cylinder 14. The coolant device includes a water pump (not shown), which adjusts the flow rate of the coolant circulating through the cylinder 14. The water pump may be one that is driven by the output of the internal combustion engine or an electric water pump (electric water pump). Although not shown, in addition to the water pump, other devices that adjust the coolant may include a thermostat that controls the coolant flowing into the cylinder, and a valve that switches the flow direction to each component of the coolant heat exchanger, cylinder, and other components of the internal combustion engine.

[0026] 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 cooling oil (e.g., engine oil) is supplied from the oil pump 54. The oil jet system 101 injects cooling oil onto the back surface of the piston to lower the temperature of the piston. Engine oil is generally used as the cooling oil. Furthermore, the internal combustion engine control device 20 adjusts the output (flow rate, oil pressure) of the oil pump 54, thereby changing the amount of oil injected from the oil jet system 101 toward the piston.

[0027] 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.

[0028] 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 is rotated by 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.

[0029] 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 through an oxidation-reduction reaction. 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.

[0030] Signals detected by the air flow sensor 1, intake pressure sensor 3, voltage sensor, and other sensors are sent to the internal combustion engine control device 20. A signal detected by an accelerator position sensor 12 that detects the amount of depression of the accelerator pedal, i.e., the accelerator position, is also sent to the internal combustion engine control device 20.

[0031] The internal combustion engine control device 20 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 20 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 20 optimally calculates the main operation 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.

[0032] The fuel injection amount calculated by the internal combustion engine control device 20 is converted into a valve-opening pulse signal and output to the fuel injector 13. In addition, the ignition timing calculated by the internal combustion engine control device 20 is output as an ignition signal to the spark plug 17. Furthermore, the throttle opening calculated by the internal combustion engine control device 20 is output as a throttle drive signal to the electronically controlled throttle valve 2.

[0033] In the internal combustion engine 100 configured as described above, fuel is injected from the fuel injector 13 into air that flows into the cylinder 14 from the intake pipe 6 through the intake valve (variable valve 5a), forming an air-fuel mixture in the cylinder. The air-fuel mixture explodes at a predetermined ignition timing due to a spark generated by the spark plug 17, and the resulting combustion pressure pushes the piston down, providing the driving force for the internal combustion engine 100. Furthermore, exhaust gas after the explosion passes through the exhaust pipe 15 and is sent to the three-way catalyst 10, where the exhaust components are purified and discharged to the outside.

[0034] 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. A portion of the exhaust gas passing through the exhaust pipe 15 may be returned to the intake pipe 6 through this EGR pipe.

[0035] [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.

[0036] 2 is a schematic cross-sectional view showing an example configuration of variable displacement oil pump 54. As described above, variable displacement oil pump 54 is capable of variably controlling the pressure (hydraulic pressure) of the oil being discharged. In oil pump 54, an intake port and an exhaust port are provided on both sides of pump housing 161. In addition, a drive shaft 162, to which rotational force is transmitted from the crankshaft of internal combustion engine 100, is disposed and passes through oil pump 54 approximately in the center.

[0037] A rotor 164 and a cam ring 165 are housed and arranged inside the pump housing 161. The rotor 164 is coupled to the drive shaft 162. The rotor 164 holds a plurality of vanes 163 on its outer periphery so that the vanes 163 can move back and forth in the radial direction.

[0038] Cam ring 165 is provided on the outer periphery of rotor 164 so as to be able to swing eccentrically. The tips of each vane 163 are in sliding contact with the inner periphery of cam ring 165. A pair of vane rings 150 are slidably disposed on both side surfaces of the inner periphery of rotor 164.

[0039] Working chambers 167 and 168 are formed on the outer periphery of cam ring 165, separated by seal members 166a and 166b. Cam ring 165 swings around pivot pin 169 in a direction that reduces the amount of eccentricity, depending on the discharge pressure of oil introduced into working chambers 167 and 168. Cam ring 165 also has lever portion 165a formed integrally with the outer periphery of cam ring 165. Lever portion 165a is formed so as to protrude toward the outer periphery of cam ring 165. Cam ring 165 swings in a direction that increases the amount of eccentricity, due to the spring force of coil spring 151 that presses lever portion 165a in a direction approximately perpendicular to the rotational direction of the crankshaft.

[0040] In the initial state, the internal combustion engine control device 20 urges the cam ring 165 in the direction that maximizes the amount of eccentricity by the spring force of the coil spring 151, 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 20 causes the cam ring 165 to swing in the direction that reduces the amount of eccentricity against the spring force of the coil spring 170, thereby reducing the discharge pressure.

[0041] 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 made up 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 and 5b (see FIG. 1) of the internal combustion engine 100, an oil jet mechanism that cools the pistons, and the like.

[0042] The oil control valve 171 has a first opening 172 and a second opening 173 formed in its body. The oil control valve 171 also has a proportional solenoid 171a and a substantially cylindrical valve element (not shown) that moves in response to the thrust generated in the proportional solenoid 171a when energized. 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 substantially cylindrical valve element. The valve element moves in the axial direction of the oil control valve 171 (left-right direction in FIG. 2 ) in response to the thrust generated by the proportional solenoid 171a. Depending on the position of the valve element, the relative positional relationship between the grooves in the valve element and the first and second openings 172 and 173 changes, thereby changing the flow path. When the valve element is in the first position, the working chamber 168 of the oil pump communicates with the oil pan through the first opening 172. When the valve body is in the second position, the working chamber 168 of the oil pump communicates with the main oil gallery 110 through the first opening 172 and the second opening 173 .

[0043] The oil control valve 171 is duty-controlled by a drive signal (PWM (Pulse Width Modulation) signal) from the internal combustion engine control device 20. A proportional solenoid 171a in the oil control valve 171 is excited according to the duty ratio of the drive signal, and the valve element is driven to a target control position.

[0044] The oil pump 54 has a mechanism for manipulating the oil pressure of the discharge oil (hereinafter also referred to as "discharge oil pressure") by controlling the eccentricity of the vane 163 according to the oil pressure difference between the working chamber 167 and the working chamber 168. The oil pump 54 performs the following controls. 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. When the difference in oil pressure between the working chambers 167 and 168 is small, the discharge oil pressure is increased by increasing the eccentricity of the vane 163 (cam ring 165).

[0045] 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 the 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: 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)). This minimizes the eccentricity of the vane 163 (cam ring 165) of the oil pump 54, and the discharge oil pressure becomes minimum. 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 168 increases (= the oil pressure in the working chamber 168 is equal to that in 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.

[0046] 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. Then, by adjusting 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 within a range from maximum to minimum.

[0047] In addition, 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 corresponding 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 20 and is used for feedback control of the discharge oil pressure of the oil pump 54 to a 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 also be used for other control purposes. Hereinafter, when simply referred to as "oil pressure," it means the discharge oil pressure of the oil pump 54.

[0048] 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.

[0049] Note that 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 are unable to reduce the oil pressure sufficiently under low temperature conditions, and the pump alone cannot stop the oil jet. Therefore, a solenoid valve for stopping the oil jet must be provided to stop the oil jet. The variable displacement oil pump 54 is capable of controlling the oil pressure over the entire temperature range, including low temperatures, and therefore does not require a solenoid valve for switching between on and off oil jet injection.

[0050] <Configuration of the internal combustion engine control device> Next, an example of the configuration of an internal combustion engine control device 20 to which the present invention is applied will be described with reference to FIG.

[0051] Fig. 3 is a block diagram showing an example of the configuration of the internal combustion engine control device 20. As shown in Fig. 3, the internal combustion engine control device 20, which is an ECU, has an input circuit 21, an input / output port 22, a RAM (Random Access Memory) 23c, a ROM (Read Only Memory) 23b, and a CPU (Central Processing Unit) 23a. The internal combustion engine control device 20 also has an oil jet control unit 26.

[0052] For example, the input circuit 21 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 21 also receives a crank angle (rotation speed) from the crank angle sensor 19, and oil pressure (oil pressure) and oil temperature (oil temperature) signals from the sensors provided in the oil jet system 101. In addition to this information, the input circuit 21 also receives information measured by various sensors, such as the throttle opening and exhaust air-fuel ratio.

[0053] The input circuit 21 performs signal processing such as noise removal on the input signal and sends the signal to the input / output port 22. The value of the signal input to the input port of the input / output port 22 is temporarily stored in the RAM 23c.

[0054] The ROM 23b stores a control program describing the contents of various arithmetic processes executed by the CPU 23a, as well as maps and data tables used in each process. The control program and the maps and data tables used in each process may be stored in a non-volatile storage (not shown). The RAM 23c has a storage area for storing values ​​input to the input ports of the input / output port 22 and values ​​representing the manipulated variable of each actuator calculated according to the control program. The values ​​representing the manipulated variable of each actuator stored in the RAM 23c are sent to the output ports of the input / output port 22.

[0055] The operation amount of the oil pump 54 set in the output port of the input / output port 22 is sent to the oil jet control unit 26. The oil jet control unit 26 generates a control signal based on the operation amount 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 26 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). Then, by controlling the hydraulic pressure of the oil pump 54, the oil jet control unit 26 adjusts the amount of oil sprayed from the oil jet system 101, thereby controlling the temperature change of the piston.

[0056] Note that the internal combustion engine 100 also uses actuators other than these, and the internal combustion engine control device 20 is equipped with an ignition control unit, a fuel injection control unit, etc. (not shown) that control these actuators, but a description thereof will be omitted here. In the present embodiment, an example has been described in which the internal combustion engine control device 20 is equipped with the oil jet control unit 26, but this is not limited to this. For example, the oil jet control unit 26 may be implemented in a control device different from the internal combustion engine control device 20.

[0057] <Overview of Control in an Internal Combustion Engine Control Device> Next, an overview of the control executed by the internal combustion engine control device 20 will be explained with reference to FIG. 4 is a control block diagram showing an overview of the control executed by the internal combustion engine control device 20 according to one embodiment of the present invention. The internal combustion engine control device 20 includes a piston temperature correlation index estimation unit 41 and an oil pressure setting unit 42. The CPU 23a (see FIG. 3) executes a control program recorded in the ROM 23b or the like, thereby realizing the function of each processing block.

[0058] [Piston temperature correlation index estimation section] The piston temperature correlation index estimation unit 41 (an example of a correlation index estimation unit) is a processing block that estimates a piston temperature correlation index that is correlated with the temperature of the piston 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 in 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. Note that the location where the oil temperature is measured is not limited to the oil pan, and it may be a location closer to the oil pump 54.

[0059] For example, the piston temperature correlation index estimation unit 41 may estimate the piston temperature itself as the piston temperature correlation index. For example, 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.

[0060] [Number 1] Tpis=(Tpis,0) +(Qinp-(Qout,1)-(Qout,oj)-(Qout,res)) ÷(Mpis × Cpis)

[0061] Here, Tpis is the updated (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 piston skirt (the part in contact with the inner wall of the cylinder). (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.

[0062] [Number 2] Qinp=(Mdot,f)×Qf×ηpis×Δτ [Number 3] (Qout,l)=Spl×λpl×((Tpis,0)-Tc)×Δτ [Number 4] (Qout,oj)=Spo×hpis×((Tpis,0)-Toil)×Δτ

[0063] where (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 coolant temperature (℃). 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 (℃).

[0064] Qf can be set in advance assuming gasoline, for example. Spl can be determined by the contact area between the piston ring and the liner, and can be easily set based on geometric information such as the piston ring thickness and bore diameter (for example, piston ring thickness × bore diameter × pi). Spo can be set based on the piston's geometric information (for example, bore diameter × bore diameter × pi ÷ 4). ηpis can be determined using a map based on operating conditions, piston temperature, cooling temperature, and oil temperature; this map must be determined in advance through experiments or simulations. hpis is a parameter that depends on the oil jet shape and oil jet flow rate. Therefore, hpis can be identified in advance through measurements such as experiments or simulations, and a map can be created. For example, the relationship between oil pressure and oil jet flow rate shown in Figure 5 and the relationship between oil jet flow rate and heat transfer coefficient hpis shown in Figure 6 can be used.

[0065] 5 is a map (graph) showing an example of the relationship between oil pressure and oil jet flow rate, where the vertical axis represents the oil jet flow rate and the horizontal axis represents the oil pressure. Fig. 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.

[0066] As shown in FIG. 5, the oil jet flow rate is greater than or equal to 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. Furthermore, when comparing at the same oil pressure, the higher the oil temperature, the lower the oil viscosity and the higher the oil jet flow rate. Furthermore, 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 then be calculated from the calculated oil jet flow rate and the relationship shown in FIG. 6. Furthermore, the fuel flow rate (Mdot,f) can be calculated, for example, using 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, as shown in Equation 5.

[0067] [Number 5] (Mdot,f)=(Mdot,a)÷AbF In this way, the piston temperature correlation index can be calculated.

[0068] (Another calculation method for the piston temperature correlation index) Furthermore, it is clear that there is a qualitative tendency for the piston temperature to rise as the combustion operation of the internal combustion engine continues and to fall when the combustion operation of the internal combustion engine is stopped. 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 temperature correlation index. For example, this can be given by the following formula:

[0069] [Number 6] tcomb=(tcomb,0)+Δτ (during combustion operation) [Number 7] tcomb=(tcomb,0)-Δτstop (when fuel is cut, when the engine is stopped)

[0070] 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 expresses both the state immediately after the internal combustion engine 100 has stopped and the state after the internal combustion engine 100 has 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 (duration of combustion operation) becomes negative, so as a general rule, tcomb≧0.

[0071] Δτstop is a parameter used to express the decrease in piston temperature during fuel cut or engine shutdown as a decrease in the duration of combustion in the internal combustion engine. In other words, "-Δτstop" represents a temperature drop. In its simplest form, Δτstop can be set to the calculation period. Furthermore, because the decrease in piston temperature is affected by fuel cut, engine shutdown, water temperature, and oil temperature, Δτstop can be expressed as a map based on water temperature, oil temperature, and engine speed. The lower the water temperature and oil temperature, the larger Δτstop becomes. On the other hand, the higher the engine speed, the larger Δτstop becomes. This reflects the fact that lower water and oil temperatures increase the amount of energy flowing from the piston to the liner, resulting in improved cooling, and that higher engine speeds increase heat transfer with the air introduced into the cylinder, resulting in improved piston cooling.

[0072] The initial value of the duration of combustion operation, which is necessary for calculating the duration of engine combustion operation, can be set based on the oil temperature and water temperature at 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 equal to or greater than the reference value. On the other hand, if the coolant temperature at the start of engine combustion is equal to or greater 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 the initial value in this manner, it is possible to reproduce a situation in which differences in the initial temperature result in differences in the time it takes to reach a predetermined temperature. Note that the initial value of the duration of combustion operation should also be determined in advance through simulations or engine operation tests.

[0073] (Another calculation method for the piston temperature correlation index) In the process of piston temperature rising, the greater the engine output (e.g., engine torque or engine speed), the greater the amount of heat transferred to the piston, resulting in a tendency for the temperature rise to be greater. Furthermore, because oil jet injection causes energy to flow from the piston to the oil, it would be desirable to incorporate this effect as an index. It is difficult to reflect the operating conditions and oil jet operating state in the combustion operation duration mentioned above. Therefore, the equation for combustion operation duration shown in Equation 6 was improved, and an index correlated with piston temperature was defined as shown in Equation 8 below. While Equation 6 simply accumulated the engine operating time, Equation 8 weights the operating conditions and the presence or absence of an oil jet when accumulating the operating time, thereby reflecting the effects of the operating conditions and the oil jet.

[0074] [Number 8] tcomb=(tcomb,0)+(αout-αoj)Δτ (during combustion operation)

[0075] Here, tcomb is the updated value (s) of the index correlated with piston temperature, (tcomb,0) is the current value (s) of the index correlated with piston 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 is set to 1, and αout is set to a value positively correlated with output. Furthermore, when output is 0, the coefficient is set to a negative value. This also allows for the reduction in piston temperature that occurs when the engine is stopped or fuel is cut off. For example, if αout is set to -1 when output is 0, then Equation 8 is equivalent to Equation 7. αoj is a coefficient for reflecting the influence of the oil jet and is given as an index positively correlated 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 to be proportional to the oil jet flow rate. Furthermore, when the value of αoj is given based on the oil pressure, αoj should be set to 0 when the oil pressure is less than the valve opening pressure of the valve 102, and αoj should be set to have a positive correlation with the oil pressure when the oil pressure is equal to or greater than the valve 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 temperature estimation (Equations 1 to 5).

[0076] [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 when oil jet injection is performed based on the piston temperature correlation index and evaporation parameters of the fuel adhering to the piston (evaporation temperature, saturated vapor pressure, etc.). The oil pressure is determined by the branching process shown in FIG. 7 based on the piston temperature correlation index, and as a result, it becomes possible to control the oil jet injection amount. In this way, in this embodiment, by providing the piston temperature correlation index estimator 41 and the oil pressure setting unit 42, it becomes possible to control the oil jet injection amount based on an index correlated with piston temperature.

[0077] The operation of the oil pressure setting section 42 of the internal combustion engine control device 20 will be described with reference to FIG. FIG. 7 is a flowchart showing an example of the operation of the oil pressure setting unit 42 of the internal combustion engine control device 20.

[0078] First, in step S501, the oil pressure setting unit 42 determines whether piston lubrication has decreased, i.e., whether piston lubrication is low. For example, if the engine combustion operation duration calculated using equations 6 and 7 is shorter than a predetermined value, it can be determined that piston lubrication is low. If the determination in step S501 is YES, the oil pressure setting unit 42 proceeds to step S502, and if the determination is NO, the oil pressure setting unit 42 proceeds to step S503.

[0079] In step S502, the oil pressure setting unit 42 sets the target oil pressure of the oil pump 54 to a pressure that allows oil jet injection. The oil pressure that allows oil jet injection is determined according to the specifications of the oil jet nozzle and valve 102 (see FIG. 1) and the oil temperature. Qualitatively, the lower the oil temperature, the higher the oil pressure that allows oil jet injection. 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.

[0080] Here, the relationship between the oil temperature and the pressure at which the oil jet can be injected will be described with reference to FIG. 8 is a map (graph) showing an example of the relationship between oil temperature and the pressure at which oil jet injection is possible, in which the vertical axis represents the pressure at which oil jet injection is possible, and the horizontal axis represents the oil temperature.

[0081] As shown in FIG. 8, under conditions of high oil temperature, the injection pressure is determined by the valve opening pressure of the valve 102. At low temperatures, the oil viscosity increases, which increases the pressure loss in the oil jet nozzle, and the pressure required to spray 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. 8. 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 possible pressure 61). Hereinafter, the mode in which the processing in step S502 is performed is referred to as the "start-up mode (1)."

[0082] By setting in this way, the oil pressure setting unit 42 can determine when piston lubrication is low and set the oil pressure at which oil jet injection is possible. Therefore, when piston lubrication is low, oil is supplied by the oil jet to improve lubrication, and the deterioration of fuel consumption in situations where piston lubrication is low can be reduced.

[0083] 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 an oil pressure that allows oil jet injection, and to set an oil pressure that allows oil to be impregnated into each part of the internal combustion engine.

[0084] In addition, the oil pressure setting unit 42 sets the target oil pressure value of the oil jet (oil jet system 101) to a oil pressure at which oil jet injection can be stopped or a oil pressure at which the oil jet can be injected, based on the oil pressure at which the valve 102, which responds to the oil pressure and is provided between the oil pump 54 and the oil jet nozzle, opens and closes.

[0085] In step S503 of FIG. 7, the oil pressure setting unit 42 determines whether the piston temperature correlation index is smaller than a first predetermined value. The first predetermined value can be determined based on the fuel evaporation condition. For example, if the piston temperature correlation index is an estimated piston temperature, a value equivalent to a 10% distillation temperature, a 30% distillation temperature, or the like, corresponding to the evaporation start temperature, can be specified as the predetermined value. Furthermore, if the duration of combustion operation of the internal combustion engine 100 is used as the piston temperature correlation index, the value of the index when the piston temperature rises to approximately a 10% distillation temperature or a 30% distillation temperature, corresponding to the distillation start temperature, can be measured in advance through simulation or experimentation and determined as the first predetermined value. This setting method is based on the idea that, since the piston temperature is also heated by heat transfer from the combustion gas and air-fuel mixture in the cylinder if the piston temperature is above the evaporation temperature, the piston temperature should be within a temperature range that does not inhibit fuel evaporation.

[0086] In this way, when the piston temperature correlation index is less than a first predetermined value determined based on the temperature corresponding to the fuel evaporation condition as an evaporation parameter, the oil pressure setting unit 42 sets the oil pressure of the oil jet (oil jet system 101) to a pressure at which oil jet injection can be stopped.

[0087] If the piston temperature correlation index is smaller than the first predetermined value (YES in S503), the oil pressure setting unit 42 proceeds to step S504. If the piston temperature correlation index is equal to or greater than the first predetermined value (NO in S503), the oil pressure setting unit 42 proceeds to step S505.

[0088] In step S504, the oil pressure setting unit 42 sets the target oil pressure of the oil pump 54 to an oil pressure at which the oil jet can be stopped, based on the relationship shown in Fig. 8. Specifically, the target oil pressure can be set to a pressure lower than the valve opening pressure of the valve 102 provided between the oil main gallery 110 and the oil jet nozzle. Hereinafter, the mode in which the processing in step S504 is performed is referred to as "in-cylinder warm-up mode (2)."

[0089] By setting the oil pressure in this manner, it is possible to set the oil pressure to a level that allows oil jet injection to be stopped when the piston temperature is lower than the evaporation start temperature and vaporization of fuel adhering to the piston is suppressed. Therefore, under low conditions where vaporization of fuel adhering to the piston is suppressed, the internal combustion engine control device 20 can accelerate the rise in piston temperature by stopping the oil jet and suppressing the energy flowing from the piston to the oil. As a result, it is possible to shorten the time it takes for the piston temperature to reach the fuel evaporation start temperature. Therefore, it is possible to reduce unburned hydrocarbons and particulate matter, which are harmful exhaust components caused by piston adhesion.

[0090] In step S505, the oil pressure setting unit 42 determines whether the oil temperature is lower than a second predetermined value. The second predetermined value may be a reference value at which the oil temperature is considered to be in a warmed-up state. For example, the second predetermined value may be determined by determining through experiments or simulations the oil temperature at which friction loss becomes sufficiently low. If the determination in step S505 is YES, the process proceeds to step S506, and if the determination is NO, the process proceeds to step S507.

[0091] In step S506, the oil pressure setting unit 42 sets the target oil pressure of the oil pump 54 to a pressure that allows oil jet injection. By setting it in this manner, it is possible to start the oil jet after the piston temperature has increased. Hereafter, the mode in which the processing in step S506 is performed is referred to as "engine warm-up mode (3)."

[0092] This allows some of the energy flowing to the piston to be diverted to the oil after the piston temperature has risen to the temperature required for fuel evaporation. This promotes the rise in oil temperature without impeding the evaporation of fuel adhering to the piston. As a result, the deterioration of fuel economy caused by low oil temperature can be reduced.

[0093] In this way, when the piston temperature correlation index is equal to or greater than a first predetermined value, the oil pressure setting unit 42 sets the target value of the oil pressure of the oil jet to an oil pressure at which the oil jet can be injected when the oil temperature of the oil jet (oil jet system 101) is less than a second predetermined value that is considered to be in a warmed-up state.

[0094] To further achieve the above effect, the oil pressure setting unit 42 may set the oil pressure within a range in which oil jet injection is possible without causing the piston temperature correlation index to fall below the first predetermined value. When the piston temperature is used as the piston temperature correlation index, the piston temperature may be predicted under two levels of oil jet injection conditions using Equations 9 to 11, and an oil jet flow rate within a range that does not fall below the first predetermined value may be determined based on the predicted value.

[0095] [Number 9] Tpis_1 =(Tpis,0) +(Qinp-(Qout,l)-(Qout,oj_1)-(Qout,res)) ÷(Mpis × Cpis) [Number 10] Tpis_2 =(Tpis,0) +(Qinp-(Qout,l)-(Qout,oj_2)-(Qout,res)) ÷(Mpis × Cpis) [Number 11] Moj_tar=(Moj_2-Moj_1) ÷(Tpis_2-Tpis_1) ×(first predetermined value +ΔTpis-Tpis_1) +Moj_1

[0096] Here, Tpis_1 is the estimated value of the piston temperature when the oil pressure is set to level 1, and Tpis_2 is the estimated value of the piston temperature when the oil pressure is set to level 2. Furthermore, Moj_1 is the oil jet flow rate at oil pressure level 1, Moj_2 is the oil jet flow rate at oil pressure level 2, and ΔTpis is the margin from the first predetermined value of the piston temperature correlation index. Here, the estimated values ​​of the piston temperatures at levels 1 and 2 need only be different. The method of providing the numerical values ​​required to calculate equations 9 and 10 is the same as for equation 1. The oil jet flow rate target value Moj_tar is calculated from the calculated Tpis_1 and Tpis_2. After calculating the oil jet flow rate target value Moj_tar, the target oil pressure can be determined from the relationship between the oil pressure and the oil jet flow rate in Figure 5.

[0097] When the combustion operation duration is used as the piston temperature correlation index, the oil jet flow rate target value Moj_tar is calculated so that the operation measurement time has a predetermined margin (for example, Δtcomb) from the first predetermined value. An example is shown in Equation 12. Calpha is the proportionality coefficient between the oil jet flow rate and αoj when αoj is set as being proportional to the oil jet flow rate (αoj = Calpha × oil jet flow rate). After calculating the oil jet flow rate target value Moj_tar, the target oil pressure can be determined from the relationship between the oil oil pressure and the oil jet flow rate in Figure 5.

[0098] [Number 12] Moj_tar=[{(tcomb,0)-first predetermined value-Δtcomb} ÷Δτ+αout] ÷Calpha

[0099] By setting the oil pressure in step S506 in this manner, it is possible to prevent the piston temperature from dropping below the evaporation temperature while promoting an increase in oil temperature, thereby preventing a deterioration in exhaust performance and maximizing the oil temperature increase.

[0100] Furthermore, by providing the engine warm-up mode (3), the oil jet can be injected while the piston temperature is maintained above the evaporation temperature. Therefore, compared to a state in which the oil jet is completely stopped and the piston temperature rise is accelerated, it is possible to minimize the deterioration of exhaust performance while suppressing the rise in oil temperature and the deterioration of fuel economy, and to improve the efficiency of combustion energy utilization.

[0101] As described above, when setting the oil pressure of the oil jet (oil jet system 101) to a pressure at which the oil jet can be injected (engine warm-up mode), the oil pressure setting unit 42 sets the oil pressure of the oil jet to a pressure that achieves an oil jet injection amount within a range that does not cause a drop in piston temperature due to the energy flowing into the oil due to oil jet injection.

[0102] In step S507, it is determined whether the piston temperature correlation index is higher than a third predetermined value or whether the engine output is higher than a fourth predetermined value. If the determination in step S507 is YES, the process proceeds to step S508, and if the determination is NO, the process proceeds to step S504. The third predetermined value can be determined as a condition in which the piston temperature is high and abnormal combustion (knocking) occurs. The fourth predetermined value can be determined based on the engine output range in which knocking occurs. The relationship between piston temperature and knocking is shown in FIG. 9.

[0103] 9 is a diagram showing the correlation between piston temperature and the frequency of knocking or the intensity of knocking, where the vertical axis represents the frequency of knocking (or the intensity of knocking) and the horizontal axis represents piston temperature. The example in Figure 9 shows a correlation that assumes measurements at the same engine output point. Knocking begins to occur as the piston temperature rises. As the piston temperature rises, the frequency and intensity of knocking increase. Therefore, the third predetermined value can be determined so that the frequency and intensity of knocking fall within a sufficiently small range. In the case of piston temperature, the temperature when the frequency or intensity of knocking is low (knocking index Nc) is set. For other indexes, the value of the index when the same piston temperature is reached is set as the third predetermined value.

[0104] 10 is a diagram showing conditions for the occurrence of knocking on a map with the engine speed and engine torque as axes, where the vertical axis represents engine torque and the horizontal axis represents engine speed. Knocking is likely to occur under conditions of low rotation and high load, and high rotation and high load. In consideration of these tendencies, the fourth predetermined value may be set so as to be variable depending on the engine speed. Because the conditions under which knocking occurs depend on the specifications of the internal combustion engine 100, it is desirable to determine the conditions in advance based on an engine operation test.

[0105] In step S508 of FIG. 7, the oil pressure setting unit 42 sets the target oil pressure of the oil pump 54 to a pressure that enables oil jet injection. The oil pressure is preferably set to have a positive correlation with engine output, with the oil pressure being set higher the higher the engine output. In other words, it is preferable to set the oil pressure so that the oil jet flow rate increases the higher the engine output. The mode in which the processing in step S508 is performed is designated "piston cooling mode (4)." This makes it possible to efficiently suppress knocking that occurs due to high piston temperatures and knocking that occurs under high output conditions, thereby improving the thermal efficiency of the engine.

[0106] In this way, when the oil temperature of the oil jet is equal to or higher than the second predetermined value, the oil pressure setting unit 42 sets the target value of the oil pressure of the oil jet (oil jet system 101) so as to be linked to the operating condition parameter (e.g., engine output).

[0107] After the processing of step S502, S504, S506 or S508, the operation of the hydraulic pressure setting unit 42 ends.

[0108] As described above, the internal combustion engine control device 20 (ECU) according to this embodiment appropriately controls the oil jet injection amount by controlling the oil jet hydraulic pressure based on the piston temperature and the operating conditions that affect the piston wall surface temperature. This allows the amount of energy flowing to the piston and engine oil to be controlled. In other words, the internal combustion engine control device 20 controls the oil jet flow rate by controlling the hydraulic pressure based on predetermined values ​​set based on phenomena such as fuel vaporization, oil viscosity, and abnormal combustion. This allows the energy generated by combustion to be efficiently supplied to the required location, increasing the energy utilization efficiency of the engine system and improving exhaust performance and fuel economy.

[0109] [Operation of various parameters] Next, the behavior of various parameters due to the hydraulic control of the internal combustion engine control device 20 according to this embodiment will be described with reference to FIG.

[0110] 11 is a timing chart showing an example of the operation of various parameters when the internal combustion engine control device 20 performs the hydraulic control process shown in FIG. 7. In FIG. 11, the parameters shown are vehicle speed, engine output, hydraulic pressure setting mode, hydraulic pressure, oil jet flow rate, energy flow of this control, energy flow of conventional control, piston temperature, and oil temperature. In the figure, for operations other than energy flow, solid lines indicate control according to this embodiment (this control), and dashed lines indicate conventional control. In conventional control, it is assumed that the hydraulic pressure is set to a level that allows the oil jet to be injected when the piston temperature rises to a level equivalent to the threshold value in conventional control.

[0111] 11 shows the results of the engine starting up in startup mode (1), transitioning to in-cylinder warm-up mode (2) at time t1, engine warm-up mode (3) at time t2, and piston cooling mode (4) at time t3. In the initial state where lubrication performance is insufficient, operating in startup mode (1) supplies oil to the piston, improving lubrication.

[0112] After time t1, when piston lubrication is ensured, operation of the in-cylinder warm-up mode (2) begins, and the oil pressure is reduced below the pressure at which oil jet injection is possible. This maximizes the use of energy transferred from the combustion gas to the piston for heating the piston, increasing the piston temperature rise rate.

[0113] After time t2 when the piston temperature reaches a first predetermined value, which is an index correlated with the evaporation temperature, the engine warm-up mode (3) begins, and the oil pressure is increased to a value greater than the oil jet injection pressure. Furthermore, by varying the oil pressure depending on the operating conditions of the internal combustion engine 100, the amount of heat flowing to the oil can be increased while maintaining the piston temperature near the first predetermined value. As a result, as shown by the change in energy flow, a portion of the energy used to increase the piston temperature in conventional control can be diverted to the oil. As a result, the oil temperature can be increased compared to conventional control. Therefore, the period of low oil temperature can be shortened, and friction loss can be reduced. Furthermore, since the oil temperature can be efficiently increased while maintaining the piston temperature and suppressing deterioration of exhaust performance, both improved exhaust performance and reduced friction loss can be achieved.

[0114] After time t3 when the oil temperature reaches or exceeds the second predetermined value, the system operates in engine warm-up mode (3) or piston cooling mode (4) depending on the piston temperature correlation index. In this example, when the engine output increases, the oil pressure is controlled so that an oil jet flow rate according to the output is blown.

[0115] As described above, by setting the various predetermined values ​​(first to fourth predetermined values) based on phenomena such as fuel vaporization, oil viscosity, and abnormal combustion, it is possible to set the oil pressure that achieves an appropriate oil jet flow rate according to the engine's piston temperature, oil temperature, and output, and efficiently supply the energy generated by combustion to the required location. As a result, it is possible to increase the energy utilization efficiency of the engine system equipped with the internal combustion engine 100, and improve exhaust performance and fuel economy.

[0116] The target oil pressure may be set based on the operational requirements of various components and other requirements, and therefore the present invention does not exclude the possibility that the target oil pressure may ultimately be overwritten with a value determined based on requirements other than those described in the embodiment.

[0117] Furthermore, the present invention is not limited to the above-described embodiment, and various other applications and modifications are possible without departing from the spirit of the present invention as set forth in the claims. For example, the above-described embodiment describes the configuration of an internal combustion engine control device in detail and specifically in order to clearly explain the present invention, and is not necessarily limited to a system including all of the components described. Furthermore, it is also possible to add, replace, or delete other components to or from part of the configuration of one embodiment.

[0118] Furthermore, the above-described configurations, functions, processing units, etc. may be partially or entirely realized in hardware, for example, by designing them as integrated circuits, etc. As the hardware, a broad processor device such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) may be used.

[0119] In addition, in the flowchart showing the time-series processing shown in FIG. 7, multiple processes may be executed in parallel or the processing order may be changed as long as it does not affect the processing results.

[0120] 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. [Explanation of symbols]

[0121] 20...Internal combustion engine control device, 26...Oil jet control unit, 41...Piston temperature correlation index estimation unit, 42...Oil pressure setting unit, 54...Oil pump, 61...Oil jet injection possible pressure, 62...Target oil pressure, 100...Internal combustion engine, 101...Oil jet system, 102...Valve, 110...Oil main gallery, 111...Oil pressure sensor, 171...Oil control valve, Pc...Oil jet cut pressure

Claims

1. An internal combustion engine control device for an internal combustion engine having a variable displacement oil pump, an oil jet for injecting oil discharged from said oil pump onto a back surface of a piston, and a valve provided between said oil pump and said oil jet that responds to the oil pressure of said oil pump, said control device controlling said valve via the oil pressure of said oil pump, a correlation index estimation unit that estimates a piston temperature correlation index that is correlated with the temperature of the piston based on operating condition parameters of the internal combustion engine, the oil pressure of the oil pump, and the oil temperature of the oil; a hydraulic pressure setting unit that sets a target value of hydraulic pressure of the oil pump based on the piston temperature correlation index, an evaporation parameter of fuel adhering to the piston, and an oil jet injection possible pressure that is a hydraulic pressure threshold at which the valve is opened and the injection is possible, The hydraulic pressure setting unit When the piston temperature correlation index is less than a first predetermined value determined based on a temperature corresponding to a fuel evaporation enabling condition as the evaporation parameter, a target value of the oil pressure of the oil pump is set to an oil pressure less than the oil jet injection enabling pressure, When the piston temperature correlation index is equal to or greater than the first predetermined value and the oil temperature is less than a second predetermined value that is regarded as a warmed-up state, a target value of the oil pressure of the oil pump is set to an oil pressure equal to or greater than the oil jet injection pressure, The oil pressure setting unit predicts the piston temperature correlation index when a target value of the oil pressure of the oil pump is set to an oil pressure equal to or higher than the oil jet injection pressure, and determines a target value of the oil pressure of the oil pump within a range in which the piston temperature correlation index does not fall below the first predetermined value based on the prediction. Internal combustion engine control device.

2. When the piston temperature correlation index is equal to or greater than the first predetermined value and the oil temperature is equal to or greater than the second predetermined value, The oil pressure setting unit sets a target value of the oil pressure of the oil pump so as to be linked to the operating condition parameter. The internal combustion engine control device according to claim 1.

3. The oil pressure setting unit determines the oil jet injectable pressure according to the current oil temperature, and sets the oil jet injectable pressure to be higher when the current oil temperature is low and oil viscosity is high than when the current oil temperature is high and oil viscosity is low. The internal combustion engine control device according to claim 1.

4. An internal combustion engine control method for an internal combustion engine equipped with a variable displacement oil pump, an oil jet for injecting oil discharged from the oil pump onto a back surface of a piston, and a valve provided between the oil pump and the oil jet that responds to the oil pressure of the oil pump, the method comprising: a correlation index estimation process for estimating a piston temperature correlation index that is correlated with the temperature of the piston based on operating condition parameters of the internal combustion engine, the oil pressure of the oil pump, and the oil temperature of the oil; a hydraulic pressure setting process for setting a target value of hydraulic pressure of the oil pump based on the piston temperature correlation index, an evaporation parameter of fuel adhering to the piston, and an oil jet injection possible pressure which is a hydraulic pressure threshold at which the valve is opened and the injection is possible, In the hydraulic pressure setting process, When the piston temperature correlation index is less than a first predetermined value determined based on a temperature corresponding to a fuel evaporation enabling condition as the evaporation parameter, a target value of the oil pressure of the oil pump is set to an oil pressure less than the oil jet injection enabling pressure, When the piston temperature correlation index is equal to or greater than the first predetermined value and the oil temperature is less than a second predetermined value that is regarded as a warmed-up state, a target value of the oil pressure of the oil pump is set to an oil pressure equal to or greater than the oil jet injection pressure, The oil pressure setting process predicts the piston temperature correlation index when a target value of the oil pressure of the oil pump is set to an oil pressure equal to or higher than the oil jet injection pressure, and determines a target value of the oil pressure of the oil pump in a range in which the piston temperature correlation index does not fall below the first predetermined value based on the prediction. Internal combustion engine control method.

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