Internal combustion engine control device and internal combustion engine control method

Abstract

The invention provides an internal combustion engine control device and an internal combustion engine control method. An internal combustion engine control device according to one embodiment of the present invention controls an internal combustion engine provided with an oil pump for discharging a predetermined flow rate of lubricating oil, and an oil injection system for injecting the lubricating oil discharged from the oil pump to a portion to which a piston is supplied, the internal combustion engine control device being provided with a control unit, when the temperature of the piston crown surface is lower than a lower limit temperature of a temperature range in which the amount of deposits deposited on the piston crown surface is less than a threshold value, control is performed such that the injection of the lubricating oil from the oil injection system is stopped or the flow rate of the lubricating oil is reduced compared to the flow rate of the previous cycle.

Description

Technical Field

[0001] The present invention relates to an internal combustion engine control device and an internal combustion engine control method for controlling an internal combustion engine for spraying an oil jet flow to a piston. Background Art

[0002] In the control system of the known internal combustion engine, the fuel consumption performance and exhaust performance are deteriorated due to the accumulation of deposits in the combustion chamber. When the deposits are accumulated, there is a method of reducing the deposits accumulated in the combustion chamber by controlling the combustion of the deposits by increasing the load of the internal combustion engine. However, when the amount of deposits accumulated is large, the deposits solidify, and thus there is a problem that the accumulation of deposits cannot be suppressed even when the control to burn the deposits is performed.

[0003] Patent Document 1 discloses a method of controlling the on / off of the oil jet flow so that the piston temperature does not enter the temperature range where the amount of deposit accumulation increases in order to suppress the accumulation of deposits in the cooling passage. In this way, the accumulation of deposits can be suppressed by controlling the piston temperature so that the piston temperature does not enter the temperature range where the amount of deposit accumulation increases.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-145757 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in the technology described in Patent Document 1, in order to suppress the accumulation of deposits, when the oil jet is turned on to reduce the temperature of the piston, the exhaust volume increases. As a result, exhaust restricting substances such as THC (Total Hydro Carbon) and PN (Particulate Number) increase. In addition, if there are multiple temperature ranges in which deposits increase, it is difficult to maintain the piston temperature at a temperature that can suppress the accumulation of deposits only by controlling the oil jet on / off, and there are cases where THC and PN increase due to the accumulation of deposits.

[0009] In view of the above circumstances, a method of achieving both suppression of the accumulation of deposits and suppression of the emission of exhaust gas regulated substances is required.

[0010] Means for solving problems

[0011] In order to solve the above-mentioned problems, an internal combustion engine control device of one embodiment of the present invention controls an internal combustion engine having an oil pump that discharges lubricating oil at a specified flow rate, and an oil injection system that injects the lubricating oil discharged from the oil pump toward a supplied part of a piston. The internal combustion engine control device has a control unit that stops the injection of lubricating oil from the oil injection system or reduces the flow rate of the lubricating oil compared to the flow rate in the previous cycle when the temperature of the piston crown surface is lower than the lower limit temperature of a temperature range in which the amount of deposit accumulation on the piston crown surface is less than a threshold value.

[0012] Effects of the Invention

[0013] According to at least one aspect of the present invention, it is possible to achieve both suppression of accumulation of deposits and suppression of emission of exhaust gas regulating substances.

[0014] Other problems, structures, and effects than those described above will become clear through the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram showing an example of a system configuration of an internal combustion engine controlled by the internal combustion engine control device according to the first embodiment of the present invention.

[0016] Figure 2 This is a schematic cross-sectional view showing a structural example of a variable displacement oil pump used in an internal combustion engine.

[0017] Figure 3 It is a block diagram showing a configuration example of an internal combustion engine control device according to the first embodiment of the present invention.

[0018] Figure 4 This is a control block diagram showing an outline of control executed by the internal combustion engine control device according to the first embodiment of the present invention.

[0019] Figure 5 It is a map (graph) showing an example of the relationship between the oil pressure and the oil injection flow rate.

[0020] Figure 6 This is a map showing an example of the relationship between the oil injection flow rate and the heat transfer coefficient between the piston and the oil injection flow.

[0021] Figure 7 This is a diagram showing an example of the relationship between the engine operation time of the internal combustion engine and THC.

[0022] Figure 8 This is a diagram showing an example of the relationship between the piston crown surface temperature and the amount of deposit accumulation.

[0023] Fig. 9 This is a flowchart showing an operation example of the oil pressure setting unit of the internal combustion engine control device according to the first embodiment of the present invention.

[0024] Fig.10 It is a map (graph) showing an example of the relationship between the oil temperature and the injectable pressure of the oil jet.

[0025] Fig.11 It is a schematic diagram showing a structural example of a piston in a second embodiment of the present invention.

[0026] Fig.12 This is a diagram showing time-series changes in vehicle speed, oil injection flow rate, piston crown surface temperature, and oil temperature during engine startup in the second embodiment of the present invention.

[0027] Fig.13 It is a block diagram showing a configuration example of an internal combustion engine control device according to a third embodiment of the present invention.

[0028] Fig.14 This is a control block diagram schematically showing control executed by an internal combustion engine control device according to a third embodiment of the present invention.

[0029] Fig.15 This is a block diagram showing an outline of control of an internal combustion engine control device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0030] Hereinafter, examples of modes for implementing the present invention (hereinafter referred to as "embodiments") will be described with reference to the drawings. In this specification and the drawings, the same components or components having substantially the same functions are denoted by the same reference numerals and repeated descriptions are omitted.

[0031] <First embodiment>

[0032] First, the system configuration of the internal combustion engine controlled by the internal combustion engine control device according to the first embodiment of the present invention is referred to. Figure 1 Provide explanation.

[0033] [Structure of internal combustion engine]

[0034] Figure 1 It is a schematic diagram showing an example of a system configuration of an internal combustion engine controlled by the internal combustion engine control device according to the present embodiment. Figure 1 The internal combustion engine 100 shown shows the system structure of a spark ignition type internal combustion engine used in an automobile, and has an in-cylinder fuel injection valve that directly injects fuel composed of gasoline into the cylinder. In addition, the internal combustion engine 100 is not limited to an in-cylinder injection type internal combustion engine (direct injection engine), and an intake port injection type internal combustion engine that injects fuel into the intake port can also be applied.

[0035] The internal combustion engine 100 is a four-stroke engine that repeatedly performs four strokes, namely, an intake stroke, a compression stroke, a combustion (expansion) stroke, and an exhaust stroke. In addition, the internal combustion engine 100 is, for example, a multi-cylinder engine having four cylinders. In addition, the number of cylinders of the internal combustion engine 100 is not limited to four, and may also have six or eight cylinders or more. In addition, the number of strokes of the internal combustion engine 100 is not limited to four strokes.

[0036] like Figure 1 As shown, the internal combustion engine 100 has 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 the intake pipe 6 before the cylinder 14.

[0037] In addition, the air flow sensor 1 measures the intake air amount and the intake air temperature. The electronically controlled throttle valve 2 is driven 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 acceleration operation. As a result, the intake air amount is adjusted, and the pressure of the intake pipe 6 is adjusted. The intake pressure sensor 3 measures the pressure of the intake pipe 6.

[0038] The compressor 4a compresses the intake air supercharged by the supercharger. The compressor 4a receives a rotational force from a turbine 4b described later. The intercooler 7 is disposed on the upstream side of the cylinder 14 to cool the intake air.

[0039] In addition, the internal combustion engine 100 is provided with a fuel injection device 13 for injecting fuel into the cylinder 14, and an ignition device composed of an ignition coil 16 and a spark plug 17 for supplying ignition energy for each cylinder 14. The ignition coil 16 generates a high voltage under the control of the internal combustion engine control device 30 and applies it to the spark plug 17. As a result, a spark is generated at the spark plug 17. Then, the mixed gas in the cylinder is burned and exploded by the spark generated at the spark plug 17. For example, an ECU (Engine Control Unit) can be used as the internal combustion engine control device 30.

[0040] In addition, a voltage sensor (not shown) is attached to the ignition coil 16. The voltage sensor measures the primary side voltage or the secondary side voltage of the ignition coil 16. Voltage information measured by the voltage sensor is sent to the internal combustion engine control device 30.

[0041] In addition, a variable valve 5a and a variable valve 5b are provided in the cylinder head 20 of the cylinder 14. The variable valve 5a adjusts the mixed gas flowing into the cylinder 14, and the variable valve 5b adjusts the exhaust gas discharged from the cylinder. By adjusting the variable valves 5a and 5b, the intake amount and the internal EGR (Exhaust Gas Recirculation) amount of all cylinders 14 can be adjusted.

[0042] Furthermore, a piston 21 is slidably arranged in the cylinder 14. The piston 21 compresses the mixed gas of fuel and gas flowing into the cylinder 14. The piston 21 reciprocates in the cylinder 14 due to the combustion pressure generated in the cylinder. In addition, a crank angle sensor 19 for detecting the position of the piston 21 is installed in the internal combustion engine 100. The crank angle information (rotation information) measured by the crank angle sensor 19 is sent to the internal combustion engine control device 30.

[0043] The fuel injection device 13 is controlled by the internal combustion engine control device 30 (ECU) to inject fuel into the cylinder 14. As a result, a mixed gas obtained by mixing air and fuel is generated in the cylinder 14. In addition, a high-pressure fuel pump (not shown) is connected to the fuel injection device 13. The fuel with a pressure 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.

[0044] In addition, a temperature sensor 18 is provided in the cylinder 14. The temperature sensor 18 measures the temperature of the cooling water circulating in the cylinder 14. As a cooling water device, there is a water pump not shown in the figure, and the flow rate of the cooling water circulating in the cylinder 14 is adjusted by the water pump. The water pump can be a water pump driven by the output of the internal combustion engine, or an electric water pump (electric water pump), etc. In addition, although not shown in the figure, there is also a case where a thermostat for controlling the cooling water flowing into the cylinder, a heat exchanger for the cooling water in the internal combustion engine, a valve for switching the flow direction in each component such as the cylinder, etc. is provided as a device for regulating cooling water in addition to the water pump.

[0045] Furthermore, an oil injection system 101 (piston cooling device) is provided in each cylinder 14 of the internal combustion engine 100. The oil injection system 101 and the variable displacement oil pump 54 (see Figure 2 ) is connected to the oil pump 54, and oil (lubricating oil) for cooling and lubrication is supplied. A throttle portion 103 for increasing the flow rate of the lubricating oil is provided in the oil injection system 101. As the lubricating oil, engine oil is generally used.

[0046] The oil injection system 101 injects lubricating oil from the throttle portion 103 to the lower surface of the piston 21 to reduce the temperature of the piston 21. The oil injection system 101 allows the lubricating oil to properly contact the lower surface (back surface) of the piston 21, and the temperature of the piston crown surface can be accurately controlled. In addition, the output (flow rate, oil pressure) of the oil pump 54 is adjusted by the internal combustion engine control device 30, and the amount of lubricating oil injected from the oil injection system 101 to the piston 21 is changed.

[0047] A valve 102 is provided in the oil flow path of the oil injection system 101. The valve 102 is provided between the main oil gallery 110 and the oil injection nozzle outlet. In this example, the valve 102 is arranged between the oil pump 54 and the oil injection nozzle outlet.

[0048] 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 waste gate 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 a rotational force to the compressor 4a. In addition, the electronically controlled waste gate valve 11 connected in a manner connecting the upstream side and the downstream side of the turbine 4b adjusts the exhaust flow rate flowing through the turbine 4b.

[0049] The three-way catalyst 10 is arranged on the downstream side of the turbine 4b. The three-way catalyst 10 purifies harmful substances contained in the exhaust gas by oxidation-reduction reaction. In addition, the air-fuel ratio sensor 9 is arranged on the upstream side 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.

[0050] In addition, the signals detected by 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, the signal detected by the accelerator opening sensor 12 for detecting the accelerator opening, that is, the amount of the accelerator pedal being depressed, is also sent to the internal combustion engine control device 30.

[0051] 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 for detecting the required torque of the internal combustion engine 100. In addition, the internal combustion engine control device 30 calculates the rotation speed of the internal combustion engine 100 based on the output signal of the crank angle sensor 19. The internal combustion engine control device 30 optimally calculates the main operation quantities of the internal combustion engine 100, such as the air flow rate (intake flow rate), the fuel injection amount, the ignition timing, the throttle valve opening, and the fuel pressure, based on the operating state of the internal combustion engine 100 obtained from the output signals of various sensors.

[0052] 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 as an ignition signal to the spark plug 17. Furthermore, the throttle valve opening calculated by the internal combustion engine control device 30 is output as a throttle valve drive signal to the electronically controlled throttle valve 2.

[0053] The internal combustion engine 100 configured in this way injects fuel from the fuel injection device 13 to the air flowing into the cylinder 14 from the intake pipe 6 via the intake valve (variable valve 5a), thereby forming a mixed gas in the cylinder. The mixed gas explodes due to the spark generated by the spark plug 17 at a predetermined ignition timing, and the piston 21 is pushed down by the combustion pressure to become the driving force of the internal combustion engine 100. Furthermore, the exhaust gas after the explosion is sent to the three-way catalyst 10 through the exhaust pipe 15, and the exhaust gas components are purified in the three-way catalyst 10 and discharged to the outside.

[0054] The internal combustion engine 100 may also be provided with an EGR pipe (not shown) connecting the intake pipe 6 and the exhaust pipe 15. A part of the exhaust gas passing through the exhaust pipe 15 can be returned to the intake pipe 6 by the EGR pipe.

[0055] [Structure of the oil pump]

[0056] Next, for an overview of the structure of the variable displacement oil pump 54 used in the internal combustion engine 100, refer to Figure 2 Provide explanation.

[0057] Figure 2 : is a schematic cross-sectional view showing a structural example of a variable displacement oil pump 54 used in the internal combustion engine 100. The oil pump unit (oil pump 54) is a variable displacement pump, which includes: a pump housing 161 having a storage unit; a rotor 164 arranged in the storage unit and connected to the rotating shaft of the internal combustion engine 100 so as to transmit driving force; a cam ring 165 in which the eccentricity between the rotation center of the rotor 164 and its own center changes between a high discharge position and a low discharge position; and a control valve unit (proportional solenoid 171a in the oil control valve 171, a substantially cylindrical valve body not shown) that changes the eccentricity of the cam ring 165 under the control of a control unit (oil injection control unit 36 ​​of the internal combustion engine control device 30). The structure of the oil pump 54 is described in further detail below.

[0058] The variable capacity oil pump 54 can variably control the pressure (oil pressure) of the discharged oil. In the oil pump 54, a suction port and a discharge port are provided on both sides of the pump housing 161. In addition, in the oil pump 54, a drive shaft 162 that transmits the rotational force from the crankshaft of the internal combustion engine 100 is arranged to penetrate substantially in the center.

[0059] 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. That is, the rotor 164 is configured to be able to transmit the driving force of the rotating shaft of the internal combustion engine 100. In addition, the rotor 164 holds a plurality of blades 163 on the outer peripheral side so that they can move forward and backward in a substantially radial direction.

[0060] The cam ring 165 is eccentrically swingably provided on the outer peripheral side of the rotor 164. The tip of each blade 163 is in sliding contact with the inner peripheral surface of the cam ring 165. In addition, a pair of blade rings 150 are slidably provided on both side surfaces of the inner peripheral portion of the rotor 164.

[0061] On the outer peripheral side of the cam ring 165, a working chamber 167 and a working chamber 168 are formed by being separated by sealing members 166a and 166b. The cam ring 165 swings in a direction in which the eccentricity is reduced, with the pivot pin 169 as the center, in accordance with the discharge pressure of the oil introduced into the working chambers 167 and 168. Furthermore, the cam ring 165 has a rod portion 165a integrally formed on its outer periphery. The rod portion 165a is formed in a manner protruding in the outer peripheral direction of the cam ring 165. The cam ring 165 swings in a direction in which the eccentricity is increased due to the elastic force of the coil spring 151 that pushes the rod portion 165a in a direction substantially perpendicular to the rotation direction of the crankshaft.

[0062] In the initial state, the internal combustion engine control device 30 applies force to the cam ring 165 in the direction of maximum eccentricity by the elastic 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 becomes equal to or higher than a predetermined value, the internal combustion engine control device 30 causes the cam ring 165 to swing in the direction of decreasing eccentricity against the elastic force of the coil spring 170, thereby reducing the discharge pressure.

[0063] The working chamber 167 of the oil pump 54 is supplied with oil (lubricating oil) from the main oil gallery 110, and the working chamber 168 is supplied with oil via an oil control valve 171 including a proportional solenoid valve. The oil discharged from the oil pump 54 is supplied to the variable valves 5a and 5b (see FIG. 1 ) for controlling the internal combustion engine 100. Figure 1 )'s hydraulic VTC (Valve Timing Control) mechanism, an oil injection mechanism for cooling the piston 21, and the like.

[0064] 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 has a proportional solenoid 171a and a substantially cylindrical valve body (not shown) that moves due to the thrust generated by the proportional solenoid 171a when the proportional solenoid 171a is excited. A groove designed in consideration of the positions of the first opening 172 and the second opening 173 is formed on the circumferential surface of the substantially cylindrical valve body. The valve body moves in the axial direction ( Figure 2 The valve body moves in the left and right directions. According to 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 is connected to the oil pan through the first opening 172. In addition, when the valve body is in the second position, the working chamber 168 of the oil pump is connected to the main oil gallery 110 through the first opening 172 and the second opening 173.

[0065] 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. In accordance with the duty ratio of the drive signal, a proportional solenoid 171a in the oil control valve 171 is energized, and the valve body is driven to a target control position.

[0066] The oil pump 54 is a mechanism that operates the oil pressure of the discharged 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 control.

[0067] [a] When the difference in oil pressure between the working chamber 167 and the working chamber 168 is large, the discharge oil pressure is reduced by reducing the eccentricity of the vane 163 (cam ring 165).

[0068] [b] When the difference in oil pressure between the working chamber 167 and the working chamber 168 is small, the discharge oil pressure is increased by increasing the eccentricity of the vane 163 (cam ring 165).

[0069] The operation of the oil pressure in the working chamber 168 is achieved by controlling the introduction and discharge of oil to the working chamber 168. That is, the oil pressure in the working chamber 168 is operated 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 oil pressure is as follows.

[0070] [a] When the duty ratio is 100%, the valve body in the oil control valve 171 moves to the position where the working chamber 168 is connected to the oil pan, and the oil pressure in the working chamber 168 decreases (= the oil pressure in the working chamber 168 is equal to 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.

[0071] [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 is connected to the main oil gallery 110, and the oil pressure in the working chamber 167 increases (= the oil pressure in the working chamber 168 is equal to the main oil 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.

[0072] As described above, when the duty ratio of the drive signal is large, the working chamber 168 is connected to the oil discharge portion (oil pan) via the oil control valve 171. As a result, the discharged oil of the oil pump 54 becomes a low-pressure state. On the other hand, when the duty ratio of the drive signal is small, the main oil gallery 110 is connected to the working chamber 168 via the oil control valve 171, so that the oil pressure acts on the working chamber 167. As a result, the discharged oil of the oil pump 54 becomes a high-pressure state. By operating the duty ratio of the drive signal between 100% and 0%, the pressure of the discharged oil of the oil pump 54 can be adjusted in a range from maximum to minimum.

[0073] In addition, an oil pressure sensor 111 is disposed in the main oil passage 110. The oil pressure sensor 111 measures the pressure of the oil in the main oil passage 110 and outputs a signal corresponding to the oil pressure. The oil pressure in the main oil passage 110 is correlated with the pressure of the oil discharged by the oil pump 54 (discharge oil pressure). In the present 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 the oil pressure sensor 111 is input to the internal combustion engine control device 30 for feedback control of the discharge oil pressure of the oil pump 54 to the target discharge oil pressure. Of course, the oil pressure obtained based on the output signal of the oil pressure sensor 111 can be used for other controls. In the following, when only "oil pressure" is recorded, it refers to the discharge oil pressure of the oil pump 54.

[0074] The oil supplied / injected to each mechanism and the oil discharged from the oil control valve 171 are recovered in the oil pan, and then supplied again to the main oil gallery 110 to be supplied / injected to the above-mentioned each mechanism.

[0075] According to use Figure 2 The structure of the oil injection system 101 of the variable capacity oil pump 54 shown in the figure can arbitrarily set the discharge oil pressure of the oil pump 54, so that the amount of oil supplied to the oil injection flow can be adjusted. Therefore, compared with the case where only the on / off of the oil injection flow is switched, in this embodiment, as described later, Figure 8 and Fig.12As shown, it is easy 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 deposit accumulation amount is below a threshold value 804.

[0076] In addition, an oil pump whose oil pressure increases in proportion to the rotational speed may be used instead of the above-mentioned variable capacity oil pump 54. Generally speaking, such an oil pump cannot reduce the oil pressure to a sufficiently low level under low temperature conditions, and the oil injection stop state cannot be achieved using a single pump. Therefore, in order to achieve the oil injection stop state, a solenoid valve for stopping the oil injection needs to be provided. When a variable capacity oil pump 54 is used, the oil pressure can be controlled in all temperature ranges including low temperatures, so there is no need to switch the solenoid valve for implementing / not implementing the oil injection.

[0077] If the structure of the oil injection system 101 uses a variable capacity oil pump 54, the amount of oil supplied to the oil injection flow can be controlled from a low ambient temperature state, so the temperature control of the piston crown surface is easy to perform, and the effect of reducing THC and PN is improved.

[0078] [Structure of internal combustion engine control device]

[0079] Next, a configuration example of the internal combustion engine control device 30 to which the present invention is applied will be referred to. Figure 3 Provide explanation.

[0080] Figure 3 is a block diagram showing a configuration example of the internal combustion engine control device 30. Figure 3 As shown, the internal combustion engine control device 30 as 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. In addition, the internal combustion engine control device 30 has an oil injection control unit 36.

[0081] For example, the input circuit 31 receives an input from the air flow sensor 1 (reference Figure 1 ), the signal of air flow rate from the intake pressure sensor 3, the signal of intake pressure from the intake pressure sensor 3, and the signal of primary voltage or secondary voltage of the coil from the voltage sensor. In addition, the crank angle (rotation speed) from the crank angle sensor 19, the oil pressure (oil pressure) and the oil temperature (oil temperature) from the sensors of the oil injection system 101 are input to the input circuit 31. Not only these information but also the information measured by various sensors such as the throttle valve opening and the exhaust air-fuel ratio are input to the input circuit 31.

[0082] The input circuit 31 performs signal processing such as noise removal on the input signal, and transmits the signal 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.

[0083] In the ROM 33b, a control program that records the contents of various calculation processes executed by the CPU 33a, a mapping table and a data table used in each process, etc. are stored. The control program, the mapping table and the data table used in each process, etc. can be stored in a non-volatile memory not shown. In the RAM 33c, a storage area is provided for storing the value input to the input port of the input / output port 32 and the value representing the operation amount of each actuator calculated according to the control program. In addition, the value representing the operation amount of each actuator stored in the RAM 33c is sent to the output port of the input / output port 32.

[0084] The operation amount of the oil pump 54 provided at the output port of the input / output port 32 is sent to the oil injection control unit 36. The oil injection control unit 36 ​​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 injection control unit 36 ​​controls the oil injection system 101 (refer to Figure 1 ) The oil pressure (oil pressure) of the oil pump 54 that supplies oil. Then, the oil injection control unit 36 ​​controls the oil pressure of the oil pump 54 to adjust the amount of oil injected from the oil injection system 101, thereby controlling the temperature change of the piston 21.

[0085] In addition, the internal combustion engine 100 also uses actuators other than these, and the internal combustion engine control device 30 has an ignition control unit, a fuel injection control unit, etc., which are not shown in the figure, for controlling these actuators, and the description thereof is omitted here. In the present embodiment, an example in which the internal combustion engine control device 30 has an oil injection control unit 36 ​​is described, but the present invention is not limited thereto. For example, the oil injection control unit 36 ​​may also be installed in a control device different from the internal combustion engine control device 30.

[0086] [Overview of Control by Internal Combustion Engine Control Device]

[0087] Next, for an overview of the control performed by the internal combustion engine control device 30, refer to Figure 4 Provide explanation.

[0088] Figure 4 1 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 injection control unit 36 ​​includes a piston crown temperature related index estimation unit 41 and an oil pressure setting unit 42. The CPU 33a (refer to Figure 3 ) executes the control program recorded in ROM33b, etc., thereby realizing the functions of each processing module.

[0089] [Piston crown surface temperature related index estimation department]

[0090] The piston crown surface temperature correlation index estimation unit 41 (an example of a correlation index estimation unit) is a processing module that estimates a piston crown surface temperature correlation index having a correlation with the temperature of the piston 21 based on the operating condition parameters of the internal combustion engine 100 and the oil injection parameters. Figure 4 In the example of FIG. 5 , the air flow rate of the intake pipe 6 and the engine speed (crank angle) are input as operating condition parameters, and the discharge oil pressure of the oil pump 54 and the oil temperature of the oil jet flow are input as oil jet parameters. For example, an oil temperature sensor is provided in the oil pan (not shown), and the oil temperature sensor measures the temperature of the oil flowing in the oil pan. In addition, the place for measuring the oil temperature is not limited to the oil pan, and may be a place closer to the oil pump 54.

[0091] For example, the piston crown surface temperature related index estimation unit 41 can estimate the piston temperature itself as the piston crown surface temperature related index. For example, based on the balance between the energy input to the piston and the energy released, the piston temperature change is estimated successively. For example, the following formula 1 can be calculated. The energy is assumed to be thermal energy.

[0092] [Formula 1]

[0093] Tpis=(Tpis,0)+(Qinp-(Qout,1)-(Qout,oj)-(Qout,res))÷(Mpis×Cpis)

[0094] 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 flowing to the piston to the piston, and (Oout, 1) 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 inner wall of the cylinder). (Q0ut, oj) is the energy [J] transferred from the piston to the oil jet, and (Qout, res) is the energy flowing from the piston to the outside through the crankshaft, etc. [J]. Furthermore, Mpis is the mass of the piston (kg), and Cpis is the specific heat capacity of the piston [J / kg / K]. For example, Qinp, (Qiut, 1), and (Qout, oj) can be calculated using the following formulas 2, 3, and 5.

[0095] [Formula 2]

[0096] Qinp=(Mdot,f)×Qf×ηpis×Δτ

[0097] [Formula 3]

[0098] (Qout,I)=Spl×λpl×((Tpis,0)-Tc)×Δτ

[0099] [Formula 4]

[0100] (Qout, oj)=Spo×hpis×((Tpis, 0)-Toil)×△τ

[0101] Here, (Mdot, f) is the fuel flow rate [kg / s], Qf is the low calorific value of the fuel [J], ηpis is the ratio of energy transferred to the piston (one), △τ is the calculation period [s]. Spl is the contact area between the piston and the cylinder liner [m2], λpl is the thermal conductivity between the piston and the cylinder liner [W / (m·K)], Tc is the cooling water 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 [℃].

[0102] Qf can be pre-set as a value assuming gasoline, for example. Spl can be obtained by the contact area between the piston ring and the cylinder liner, and can be easily set based on geometric information such as the thickness and bore diameter of the piston ring (for example, the thickness of the piston ring × the bore diameter × the pi). Spo can be set based on the geometric information of the piston (for example, the bore diameter × the bore diameter × the pi ÷ 4). In addition, ηpis can be obtained by a mapping based on the operating conditions, piston temperature, cooling temperature, and oil temperature, and the mapping needs to be predetermined by experiments or simulations. In addition, hpis is a parameter that depends on the shape of the oil injection flow and the oil injection flow rate. Therefore, regarding hpis, it can be predetermined by measurements such as experiments or simulations to generate a mapping. For example, using Figure 5 The relationship between oil pressure and oil injection flow rate is shown in the figure. Figure 6 The relationship between oil injection flow rate and heat transfer coefficient hpis is shown.

[0103] Figure 5 It is a map (graph) showing an example of the relationship between the oil pressure and the oil injection flow rate. Figure 5 The vertical axis represents the oil injection flow rate, and the horizontal axis represents the oil pressure.

[0104] Figure 6 This is a map showing an example of the relationship between the oil injection flow rate and the heat transfer coefficient hpis between the piston and the oil injection flow. Figure 6 The vertical axis represents the heat transfer coefficient (hpis), and the horizontal axis represents the oil injection flow rate.

[0105] like Figure 5 As shown in FIG. 1 , the oil injection flow rate is a value greater than 0 when the oil pressure is greater than the valve opening pressure of the valve 102, and the flow rate increases as the oil pressure increases. In addition, when the oil pressure is the same, the higher the oil temperature, the lower the oil viscosity, and the greater the oil injection flow rate. Figure 6As shown in Figure 1, the heat transfer coefficient hpis has a positive correlation with the oil injection flow rate. Therefore, the larger the oil injection flow rate, the larger the heat transfer coefficient hpis. Figure 5 The current oil injection flow is calculated based on the relationship shown in the figure. Figure 6 The heat transfer coefficient hpis can be calculated from the relationship shown in FIG. 5. In addition, 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 FIG.

[0106] [Formula 5]

[0107] (Mdot, f) = (Mdot, a) ÷ AbF

[0108] Based on the above content, the relevant indicators of piston crown surface temperature can be calculated.

[0109] (Other calculation methods for indicators related to piston crown surface temperature)

[0110] In addition, it is clear that the piston temperature has a qualitative tendency to rise as the combustion operation in the internal combustion engine continues and to fall when the combustion operation of the internal combustion engine stops. Therefore, the duration of the combustion operation of the internal combustion engine (combustion operation duration) can also be used in the calculation of the piston crown surface temperature related index. For example, it can be calculated using the following formula.

[0111] [Formula 6]

[0112] tcomb=(tcomb,0)+△τ(during combustion operation)

[0113] [Formula 7]

[0114] tcomb = (tcomb, 0) - Δτstop (when fuel is cut off, when the engine is stopped)

[0115] Here, tcomb is an updated value [s] of the duration of the combustion operation of the engine, and (tcomb, 0) is a current value [s] of the duration of the combustion operation of the internal combustion engine 100. Formula 7 represents both the state immediately after the internal combustion engine 100 stops and the state after the internal combustion engine 100 stops for a period of time. In the case of Formula 7, the value of tcomb (combustion operation duration) is negative when the time after the internal combustion engine stops is long, so tcomb ≥ 0 is set in principle.

[0116] △τstop is a parameter used to express the reduction in piston temperature when the fuel is cut off or the engine is stopped by reducing the duration of the combustion operation of the internal combustion engine. That is, "-△τstop" means a temperature reduction. In the simplest form, △τstop can be set as a calculation cycle. In addition, the reduction in piston temperature is affected by combustion cut-off, engine stop, water temperature, and oil temperature, so △τstop can be calculated using a mapping with water temperature, oil temperature, and engine speed as axes. The lower the water temperature and oil temperature, the larger the △τstop. On the other hand, the higher the engine speed, the more △τstop can be increased. This is to reflect that the lower the water temperature and oil temperature, the greater the energy flowing from the piston to the cylinder liner and the more advanced the cooling. In addition, under the condition of higher engine speed, the more heat transfer with the air introduced into the cylinder is carried out and the more advanced the cooling of the piston is.

[0117] The initial value of the duration of the combustion operation, which is required to calculate the duration of the engine's combustion operation, can be set based on the oil temperature and water temperature when the engine is started. For example, a reference value of the cooling water temperature is determined, and the initial value is set to 0 when the cooling water temperature at the start of engine combustion is the reference value. On the other hand, when the cooling water temperature at the start of engine combustion is above the reference value, the initial value is set to a value greater than 0. Conversely, when the cooling water temperature at the start of engine combustion is lower than the reference value, the initial value is set to a value less than 0. By setting in this way, it is possible to reproduce a state in which the time to reach a specified temperature differs due to differences in the initial temperature. In addition, the initial value of the duration of the combustion operation is also required to be determined in advance through simulation or engine operation test.

[0118] (Other calculation methods for indicators related to piston crown surface temperature)

[0119] During the process of the temperature rising of the piston, the greater the engine output (such as engine torque or engine speed), the greater the amount of heat transferred to the piston, so there is a tendency for the temperature rise to increase. In addition, there is energy flowing from the piston to the oil due to oil injection, so it is better to reflect this influence as an indicator. The above-mentioned combustion operation duration is difficult to reflect the operating conditions and the oil injection action state. Therefore, the formula for the combustion operation duration shown in Formula 6 is improved, and an indicator that is correlated with the piston crown surface temperature is defined as shown in the following Formula 8. Therefore, in Formula 6, only the operating time of the engine is accumulated, but in Formula 8, by weighting according to the operating conditions and the presence or absence of oil injection when accumulating the operating time, the operating conditions and the influence of oil injection can be reflected.

[0120] [Formula 8]

[0121] tcomb=(tcomb,0)+(αout-αoj)△τ(during combustion operation)

[0122] Here, tcomb is the updated value [s] of the index related to the piston crown surface temperature, (tcomb, 0) is the current value [s] of the index related to the piston crown surface temperature, and αout is a coefficient used to reflect the influence of the operating conditions, which is an index positively correlated with the output. For example, the value of αout at the baseline output is set to 1, and αout is set to a value positively correlated with the output. In addition, when the output is 0, the coefficient is set to a negative value. In this way, it is also possible to express the change in the piston temperature drop that occurs when the engine is stopped or the fuel is cut off. For example, when αout is set to -1 when the output is 0, Formula 8 is equivalent to Formula 7.

[0123] In addition, αoj is a coefficient for reflecting the influence of oil injection, and is given as an index that is positively correlated with the oil injection flow rate or the oil pressure. For example, when the oil injection flow rate is 0, αoj is set to 0, and αoj is set in direct proportion to the oil injection flow rate. In addition, when the value of αoj is given based on the oil pressure, αoj is set to 0 when the oil pressure is lower than the valve opening pressure of the valve 102, and αoj is set in a positive correlation with the oil pressure in the range where the oil pressure is above the valve opening pressure. As a result, an index that is closer to the change in piston temperature than the combustion operation duration (Formula 6 to Formula 7) and can be easily calculated compared to the piston crown surface temperature estimation (Formula 1 to Formula 5) can be applied.

[0124] In addition, the crown surface (top surface) temperature of the piston 21 may be directly measured by providing a temperature sensor 105 for temperature measurement near the crown surface of the piston 21 . Figure 1 2 shows an example in which the temperature sensor 105 is provided at a portion of the outer wall of the cylinder 14 corresponding to the reciprocating motion region of the piston 21 .

[0125] [Hydraulic pressure setting unit]

[0126] The oil pressure setting unit 42 (refer to Figure 4 ) is a processing module for setting 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 the oil injection is performed based on the piston crown temperature related index estimated by the piston crown temperature related index estimation unit 41. The oil pressure is based on the piston crown temperature related index. Fig. 9 The branch processing shown is determined, and as a result, the oil injection flow rate can be controlled.

[0127] Thus, in this embodiment, by providing the piston crown temperature related index estimation unit 41 and the oil pressure setting unit 42, the oil injection flow rate can be controlled based on the index related to the piston crown temperature. In addition, the oil pressure setting unit 42 may also use a temperature sensor 105 (see Figure 1) is used as the measured value of the piston crown surface temperature.

[0128] [Engine operating time and THC emission]

[0129] Here, the relationship between the engine operation time of the internal combustion engine and the emission amount of THC will be described.

[0130] Figure 7 This is a graph showing an example of the relationship between the engine operating time [h] of an internal combustion engine and the THC emission [ppmC]. PN also has the same tendency as the THC emission. When the engine is running for a long time, substances (combustion products) produced by unburned or incomplete combustion of fuel or lubricating oil accumulate in the engine cylinder as deposits. The deposits repeatedly adhere to and peel off the wall of the combustion chamber, and the amount of accumulation increases over time. The deposits absorb fuel or lubricating oil, thereby causing partial misfire or incomplete combustion, and the THC and PN emitted from the engine increase. Figure 7 , an example is shown in which the amount of THC emission increases from an initial value 701 as the engine operation time elapses, and the increase exceeds an allowable amount 702 of THC increase.

[0131] Deposits are accumulated on the wall surfaces of the cylinder head 20, the piston 21, the cylinder 14, the variable valve 5a for intake, the variable valve 5b for exhaust, and the fuel injection device 13. The inner wall of the cylinder 14 is a sliding part with the piston 21, and the position of the piston 21 is close to the top dead center near the ignition time. Therefore, the surface area of ​​the inner wall of the cylinder 14 forming the combustion chamber near the ignition time 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.

[0132] [Piston crown surface temperature and deposit accumulation]

[0133] Next, the relationship between the crown surface temperature of the piston 21, which is the main component for deposit accumulation, and the amount of deposit accumulation will be described.

[0134] Figure 8 This is a graph showing an example of the relationship between the piston crown surface temperature [°C] and the deposit accumulation amount [mg]. Figure 8 8 is the amount of deposit accumulation after a certain period of engine operation. Deposits are easily accumulated in the temperature range 801 when the piston crown surface temperature is low, and in the temperature range 803 when the piston crown surface temperature is high. Therefore, in order to suppress the accumulation of deposits, the crown surface temperature of the piston 21 should be maintained in the temperature range 802 where the amount of deposit accumulation is "small" between the temperature range 801 and the temperature range 803. As a result, the increase of THC and PN caused by the accumulation of deposits can be suppressed.

[0135] Figure 8 , an example is shown in which the lower limit temperature 805 of the temperature range 802 is set to about 150 [°C] and the upper limit temperature 806 is set to about 215 [°C] based on the threshold value 804 (permissible value) of the deposit accumulation amount. Figure 7 The allowable amount 702 of THC increase compared to the initial value 701 of the emission amount of the emission-regulated substance such as THC shown may be set in advance by the ECU 30 .

[0136] [Operation of the hydraulic pressure setting unit]

[0137] Next, the operation of the oil pressure setting unit 42 of the internal combustion engine control device 30 will be described with reference to Fig. 9 Provide explanation.

[0138] Fig. 9 1 is a flowchart showing an example of the operation of the oil pressure setting unit 42 of the internal combustion engine control device 30 .

[0139] First, in step S901, the oil pressure setting unit 42 determines whether the lubricity of the piston 21 and the cylinder 14 is reduced, that is, whether the piston lubricity is low. For example, when the combustion operation duration of the internal combustion engine 100 calculated by equations 6 and 7 is less than a predetermined value, it can be determined that the piston lubricity is low. When the oil pressure setting unit 42 determines in step S901 that it is YES, it proceeds to step S902, and when it determines that it is NO, it proceeds to step S903.

[0140] When the combustion operation duration of the internal combustion engine 100 is less than a predetermined value (S901 is determined to be YES), in step S902, the oil pressure setting unit 42 sets the target oil pressure of the oil pump 54 to the oil pressure at which the oil jet can be injected. Figure 1 ) and the oil temperature determine the oil pressure at which the oil jet can be injected. Qualitatively, the lower the oil temperature, the higher the oil pressure at which the oil jet can be injected. Valve 102 is a one-way valve (check valve) configured to open when the oil pressure of the main oil passage 110 becomes greater than a specified value. For example, a ball valve can be used as valve 102.

[0141] Here, the relationship between oil temperature and the sprayable pressure of oil jet is shown in Fig.10 Provide explanation.

[0142] Fig.10 It is a map (graph) showing an example of the relationship between the oil temperature and the injectable pressure of the oil jet. Fig.10 The vertical axis represents the injectable pressure of the oil jet, and the horizontal axis represents the oil temperature.

[0143] like Fig.10As shown in FIG. 1 , under the condition of high oil temperature, the injection pressure is determined by the valve opening pressure of valve 102. At low temperatures, the oil viscosity is high, so the pressure loss at the oil injection nozzle is large. Therefore, there is a case where the pressure required to eject the oil from the front end of the nozzle is much larger than the injection pressure (oil injection cutoff pressure Pc) determined by valve 102. The oil pressure setting unit 42 sets the oil pressure based on the current oil temperature and the oil pressure at the current time. Fig.10 The relationship shown in FIG. 6 determines the set value of the oil pressure (target oil pressure 62). The target oil pressure 62 may be set to a value above the pressure at which the oil jet can be ejected (the oil jet ejectable pressure 61). Hereinafter, the mode in which the process of step S902 is performed is referred to as the "lubrication mode".

[0144] By setting in this way, the oil pressure setting unit 42 can judge the situation of low lubricity of the piston and set the oil pressure at which the oil jet can be injected. Therefore, under the condition of low lubricity of the piston, the lubricity can be improved by supplying oil through oil injection, and the deterioration of fuel consumption under the condition of low lubricity of the piston can be reduced.

[0145] 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 injection system 101) to the oil pressure at which the oil jet can be injected, and to set the oil pressure at which the oil penetrates into each part of the internal combustion engine.

[0146] In addition, the oil pressure setting unit 42 sets the target value of the oil pressure of the oil jet stream (oil injection system 101) to the oil pressure at which the oil jet stream can be stopped or the oil pressure at which the oil jet stream can be injected based on the oil pressure of the opening and closing of the oil pressure-responsive valve 102 set between the oil pump 54 and the oil injection nozzle.

[0147] When the combustion operation duration of the internal combustion engine 100 is equal to or longer than a predetermined value (S901 is determined as NO), Fig. 9 In step S903, the oil pressure setting unit 42 determines whether the piston crown surface temperature related index is less than a first specified value. The first specified value is specified as Figure 6 The lower limit temperature 805 of the temperature range 802 where the amount of sediment accumulation is small.

[0148] In this way, when the crown surface temperature of the piston 21 is lower than the first predetermined value, the oil pressure setting unit 42 sets the oil pressure of the oil jet flow (oil jet system 101) to an oil pressure at which the oil jet can be stopped.

[0149] The oil pressure setting unit 42 proceeds to step S904 when the crown surface temperature of the piston 21 is less than the first predetermined value (S903 is determined as YES). Otherwise, the oil pressure setting unit 42 proceeds to step S905 when the crown surface temperature of the piston 21 is greater than the first predetermined value (S903 is determined as NO).

[0150] In step S904, the oil pressure setting unit 42 sets the oil pressure according to Figure 5 The target oil pressure of the oil pump 54 is set to the oil pressure at which the oil injection can be stopped, based on the relationship shown in FIG. Specifically, it is set to a pressure lower than the valve opening pressure of the valve 102 provided between the main oil gallery 110 and the oil injection nozzle. Hereinafter, the mode in which the processing of step S904 is performed after the judgment of YES in step S903 is referred to as the "preheating promotion mode".

[0151] In step S905, the oil pressure setting unit 42 determines whether the crown temperature of the piston 21 is greater than the second specified value. If the crown temperature of the piston 21 is greater than the second specified value (S905 determines that it is (YES)), the oil pressure setting unit 42 proceeds to step S906. In step S906, the oil pressure setting unit 42 sets the target oil pressure of the oil pump 54 to the oil pressure at which the oil jet can be ejected, and performs control to suppress the crown temperature of the piston 21. The second specified value is determined as Figure 8 The upper limit temperature 806 of the temperature range 802 where the amount of deposit accumulation is small.

[0152] On the other hand, when the crown surface temperature of the piston 21 is below the second predetermined value (S905 is determined as NO), the oil pressure setting unit 42 proceeds to step S907 to determine whether the time-dependent change in the crown surface temperature of the piston 21 is increasing. In the ECU 30, the change direction and amount of the crown surface temperature are stored in the RAM 33 as the time-dependent change in the crown surface temperature of the piston 21.

[0153] In step S907, when the time-dependent change in the crown surface temperature of the piston 21 increases (step S907 determines that it is YES), the oil pressure setting unit 42 proceeds to step S908. In step S908, the oil pressure setting unit 42 reduces the temperature of the piston crown surface by increasing the oil amount (oil injection flow rate) of the oil jet flow compared to the oil amount in the previous cycle.

[0154] On the other hand, if the time-dependent change in the crown surface temperature of the piston 21 does not increase (remains constant or decreases) (step S907 is determined to be NO), 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 the oil pressure at which the oil injection can be stopped or reducing the oil amount (S904). Hereinafter, the mode in which the processing of steps S905, S906, S907, S908, and S904 is performed is referred to as a "deposit suppression mode".

[0155] By the deposit suppression mode, it is easy to maintain the crown surface temperature of the piston 21 between the first predetermined value (e.g., the lower limit temperature 805) and the second predetermined value (e.g., the 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 the accumulation of deposits can be suppressed, and the increase of THC and PN can be suppressed.

[0156] After the processing of step S902, S904, S906 or S908 is completed, the processing performed by the oil pressure setting unit 42 ends. Fig.12 As shown, it can be considered that the oil pressure setting unit 42 has a function of selecting any one of the "lubrication mode", "warm-up promotion mode" and "deposit suppression mode" based on the piston crown surface temperature related index or the measured value of the piston crown surface temperature and executing the selected mode.

[0157] For example, the oil pressure setting unit 42 is as described below. Fig.12 As shown by the solid line 1202, the "promotion preheating mode" can be selected and executed within the first temperature state range that is predetermined and includes the temperature state of the piston crown surface where the amount of deposit accumulation on the piston crown surface is greater than the threshold value (threshold value 804). The first temperature state range is a temperature range ( 805 ) where the piston crown surface temperature is lower than the lower limit (lower limit temperature 805) of the temperature state of the piston crown surface where the amount of deposit accumulation is less than the threshold value. Figure 4 The oil pressure setting unit 42 selects the "promoting warm-up mode" when the temperature of the piston crown surface is within the first temperature state range where the amount of deposit accumulation is greater than the threshold value, and performs oil injection (S904). As a result, the piston crown surface temperature is easy to rise, and the residence time in the temperature range 801 where the amount of deposit accumulation is greater than the threshold value can be reduced. As a result, THC and PN can be suppressed.

[0158] In addition, the oil pressure setting unit 42 is as follows Fig.12 As shown by the solid line 1202, the temperature state of the piston crown surface is a high temperature state, that is, a second temperature state ( Figure 4 In the temperature range 802, 803 of the second temperature state, the "deposit suppression mode" is selected and executed. In the deposit suppression mode under 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 where the amount of deposit accumulation on the piston crown surface is less than the threshold value (threshold value 804) (S905 is judged as No (NO)), the oil pressure setting unit 42 reduces or cuts off the oil injection 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 where the amount of deposit accumulation is less than the threshold value, and the time-dependent change of the piston crown surface temperature has an increasing tendency (S907 is judged as Yes (YES)), the oil pressure setting unit 42 increases the oil injection flow rate (S908).

[0159] On the other hand, when the temperature state of the piston crown surface is higher than the upper limit of the temperature state of the piston crown surface where the amount of deposit accumulation is less than the threshold value (threshold value 804) (S905 is determined to be YES), the oil pressure setting unit 42 performs oil injection (S906). Through this control, it is easy to maintain the temperature of the piston crown surface in the temperature range where the amount of deposit accumulation is small (between the lower limit temperature 805 and the upper limit temperature 806). As a result, the accumulation of deposits on the piston crown surface can be suppressed, and as a result, THC and PN can be reduced.

[0160] Here, the oil injection (flow rate) is controlled by Fig.12 The solid line 1202 is used as an example to illustrate, but Fig.12 The dotted line 1201 can also perform the same control.

[0161] As described above, the internal combustion engine control device (internal combustion engine control device 30) of the present embodiment is an internal combustion engine control device of an internal combustion engine (internal combustion engine) 100 that controls an oil pump (oil pump 54) that discharges lubricating oil at a specified flow rate, and an oil injection system (oil injection system 101) that injects lubricating oil discharged from the oil pump to a supplied portion (back surface) of a piston (piston 21). The internal combustion engine control device includes a control unit (CPU 33a, oil injection control unit 36) that performs control to stop injection of lubricating oil from the oil injection system or to reduce the flow rate of lubricating oil compared to the flow rate of the previous cycle when the temperature of the piston crown surface is lower than the lower limit temperature (lower limit temperature 805) of the temperature range (temperature range 802) in which the amount of deposit accumulation on the piston crown surface is less than the threshold value (threshold value 804) (equivalent to the promotion warm-up mode).

[0162] According to the internal combustion engine control device of the present embodiment, when the temperature of the piston crown surface is lower than the lower limit temperature of the temperature range in which the amount of deposit accumulation on the piston crown surface is less than the threshold value, control is performed to reduce the lubricating oil injection or flow rate from the oil jet. Through such oil injection control, the temperature of the piston crown surface can quickly pass through the temperature state in which the amount of deposit accumulation on the piston crown surface is more than the threshold value, and transfer to the temperature range in which the amount of deposit accumulation decreases. As a result, the accumulation of deposits can be suppressed, and the emission of emission-restricted substances can be suppressed. That is, it is possible to take into account both the suppression of the accumulation of deposits and the suppression of the emission of emission-restricted substances.

[0163] The above-mentioned control unit (oil injection control unit 36) is configured to stop the injection of lubricating oil from the oil injection system or reduce the flow rate of the lubricating oil compared with the flow rate in the previous cycle when the temperature of the piston crown surface is above the lower limit temperature (lower limit temperature 805) and below the upper limit temperature (upper limit temperature 806) of the temperature range (temperature range 802) in which the amount of deposit accumulation on the piston crown surface is less than a threshold value (threshold value 804) (equivalent to the deposit suppression mode).

[0164] By controlling the oil injection with the above structure, the temperature of the piston crown surface is maintained in a temperature range where the amount of deposit accumulation is small, thereby suppressing the accumulation of deposits and suppressing the increase of THC and PN.

[0165] The above-mentioned control unit (oil injection control unit 36) is configured to increase the flow rate of lubricating oil compared with the flow rate of the previous cycle when the temperature of the piston crown surface is above the lower limit temperature (lower limit temperature 805) and below the upper limit temperature (upper limit temperature 806) of the temperature range (temperature range 802) in which the amount of deposit accumulation on the piston crown surface is less than the threshold value (threshold value 804) (equivalent to the deposit suppression mode), and the time-dependent change in the temperature of the piston crown surface tends to increase.

[0166] By controlling the oil injection of the above structure, the temperature of the piston crown surface is maintained in a temperature range where the amount of deposit accumulation is small, thereby suppressing the accumulation of deposits and suppressing the increase of THC and PN. In particular, when the temperature of the piston crown surface tends to increase over time, although the amount of deposit accumulation increases (refer to Figure 8 ), but by increasing the flow rate of the injected lubricating oil, it is possible to prevent the temperature of the piston crown surface from rising and suppress the increase in the amount of deposit accumulation.

[0167] The control unit (oil injection control unit 36) is configured to execute lubricating oil injection from the oil injection system when the temperature of the piston crown surface exceeds the upper limit temperature of the temperature range in which the amount of deposit accumulation on the piston crown surface is less than a threshold value (corresponding to the deposit suppression mode).

[0168] By the oil injection control of the above structure, the temperature of the piston crown surface is rapidly reduced and the piston crown surface temperature is included in the temperature range where the accumulation amount of deposits is small, thereby suppressing the accumulation of deposits and suppressing the increase of THC and PN.

[0169] The above-mentioned control unit (oil injection control unit 36) is configured to judge 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 deposit accumulation on the piston crown surface is less than the threshold value (threshold value 804), and when it is judged that the lubricity is insufficient (equivalent to the lubrication mode), execute the injection of lubricating oil from the oil injection system.

[0170] The oil injection control with the above configuration can improve the lubricity between the piston and the cylinder of the internal combustion engine, and can reduce the deterioration of fuel consumption in a situation where the lubricity of the piston is low.

[0171] The temperature of the above-mentioned piston crown surface is a piston crown surface temperature-related indicator correlated with the temperature of the piston crown surface, which is estimated based on the operating condition parameters of the internal combustion engine and the oil injection parameters used to inject lubricating oil onto the back of the piston, or a measurement value of a temperature sensor (temperature sensor 105) that measures the temperature of the piston crown surface.

[0172] <Second embodiment>

[0173] The second embodiment of the present invention is an example in which the piston 21 is improved in the internal combustion engine 100 of the first embodiment to improve the controllability of the piston crown surface temperature. Fig.11 and Fig.12 Provide explanation.

[0174] Fig.11 It is a schematic diagram showing a structural example of the piston according to the present embodiment.

[0175] Fig.12 This is a diagram showing the time-series changes in vehicle speed [km / h], oil injection flow rate ("OJ flow rate" in the diagram) [L / min], piston crown surface temperature [°C], and oil temperature [°C] during engine startup in this embodiment. Fig.12 In FIG. 1 , regarding the oil injection flow rate, the piston crown temperature, and the oil temperature, the dashed line 1201 represents the first embodiment, and the solid line 1202 represents the second embodiment. Fig.12 Among them, (1) lubrication mode, (2) warm-up promotion mode, and (3) deposit suppression mode are assumed as examples applied to the second embodiment.

[0176] The piston 21A of the second embodiment is different from the piston 21 of the first embodiment in that the piston 21A has 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 .

[0177] use Fig.11 and Fig.12 The function and effect of the case where the piston 21A of the second embodiment is used 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 the heat dissipated 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. Fig.12 As shown in the moment 1203, the temperature rise rate of the piston crown surface 1102 when the engine is started can be faster than that of the first embodiment. As a result, the lower limit temperature 805 (reference Figure 8) is shortened from time 1204 to time 1205. Since the engine is repeatedly stopped and started, the structure of the piston 21A of the second embodiment can increase the residence time of the temperature range 802 in which the amount of deposit accumulation of the piston crown surface temperature decreases compared to the first embodiment, and as a result, the accumulation of deposits can be suppressed. As a result, the increase of THC and PN can be suppressed.

[0178] In addition, 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, can be set to a value that is sufficiently smaller than the thickness 1103 of the base material 1101. Thermal conductivity is determined by the "heat transfer coefficient" and "heat capacity" of the material, so by reducing the thickness 1104 of the piston crown surface 1102, the temperature of the piston crown surface 1102 is likely to rise. As a result, for the piston crown surface temperature, the residence time in the temperature range 802 where the amount of deposit accumulation decreases can be increased, and the accumulation of deposits can be suppressed. In order to reduce the thickness of the piston crown surface 1102, the piston crown surface 1102 can be formed by coating the base material 1101.

[0179] 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. 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 the thermal conductivity of the base material 1101, the temperature rise rate of the piston crown surface 1102 can be increased, and the effect of suppressing the accumulation of deposits can be improved.

[0180] In addition, regarding the oil temperature of the oil jet, by using the structure and control of the second embodiment, the timing of starting the oil jet after the preheating mode is promoted or the oil amount of the oil jet can be advanced. By spraying the oil jet to the bottom surface of the piston 21A, heat is transferred from the piston 21A to the lubricating oil, and the rate of increase in the oil temperature is increased. As a result, the time to stop the oil jet or the time when the oil temperature of the oil jet reaches the preheating judgment temperature Twj can be advanced from time 1206 to time 1207. The preheating judgment temperature Twj is a temperature threshold for judging that the internal combustion engine 100 has been heated to a set temperature. As a result, the fuel injected into the engine cylinder is easily vaporized, and the suppression effect of THC and PN is improved.

[0181] <Modification of Second Embodiment>

[0182] In addition, in the control system of the second embodiment, the oil pressure setting unit 42 that selects one of the "lubrication mode", "preheating promotion mode", and "deposit suppression mode" may also have the function of executing the selected mode in addition to the piston crown surface temperature-related indicators or the measured value of the piston crown surface temperature, while also considering the thermal conductivity of the piston crown surface.

[0183] For example, there is a delay corresponding to the thermal conductivity (corresponding to the heat transfer coefficient and the heat capacity) of the piston crown surface 1102 from when the oil jet is turned on until the temperature of the piston crown surface 1102 decreases. Therefore, the piston crown surface temperature is predicted in advance by taking the thermal conductivity into consideration in addition to the temperature change of the piston 21A, and one of the "lubrication mode", "preheating promotion mode" and "deposit suppression mode" can be selected according to the predicted value of the piston crown surface temperature.

[0184] Therefore, in this embodiment, it is easy to control the crown temperature of the piston 21 within the specified range, which can improve the effect of suppressing THC and PN. That is, considering the delay in the effect of the increase or decrease of the oil injection flow, the oil injection is switched to be advanced or delayed. For example, when the thermal conductivity is greater than the specified value, the temperature of the piston crown changes rapidly, so the on / off (ON / OFF) or flow rate switching of the oil injection is delayed. In addition, when the thermal conductivity is below the specified value, the temperature of the piston crown changes slowly, so the on / off (ON / OFF) or flow rate switching of the oil injection is performed in advance.

[0185] In an example of the control system of 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 is small, the oil injection flow rate is increased to cool the piston 21A. However, there is a delay corresponding to the thermal conductivity from the time when the oil injection flow rate is increased (for example, time 1208) to the time when the crown surface temperature of the piston 21A actually starts to decrease (for example, time 1209).

[0186] Therefore, the time variation of the piston crown surface temperature is stored in advance in the ECU 30. Then, the oil pressure setting unit 42 considers the time delay corresponding to the thermal conductivity, and when it is predicted that the piston crown surface temperature after a certain time obtained from the time variation of the piston crown surface temperature exceeds the upper limit temperature 806 with a small amount of deposit accumulation, the oil injection flow rate can be increased in advance. In this way, the time for the piston crown surface temperature to exceed the upper limit temperature 806 with a small amount of deposit accumulation can be shortened, and the accumulation of deposits can be suppressed.

[0187] In addition, when it is predicted that the piston crown temperature is lower than the lower limit temperature 805 with less deposit accumulation, the oil injection flow rate can be reduced or the oil injection can be stopped in advance. This can shorten the time for the piston crown temperature to be lower than the lower limit temperature 805 with less deposit accumulation, and can suppress the accumulation of deposits.

[0188] Here, regarding the control of the oil injection flow rate, the second embodiment ( Fig.12 The solid line 1202) is used as an example, but the same control can be performed in the first embodiment (dashed line 1201).

[0189] <Third Embodiment>

[0190] The third embodiment of the present invention is an example of controlling the ignition timing of the air-fuel mixture in the combustion chamber based on the pattern information notified from the oil injection control unit 36. Fig.13 and Fig.14 Provide explanation.

[0191] Fig.13 1 is a block diagram showing a configuration example of an internal combustion engine control device according to the present embodiment. Fig.13 As shown, the internal combustion engine control device 30A of the present embodiment is a configuration in which an ignition timing control unit 1300 is added to the internal combustion engine control device 30 of the first embodiment. The CPU 33a executes a control program recorded in the ROM 33b or the like, thereby realizing the functions of each processing block.

[0192] The piston crown surface temperature-related index estimation unit 41 and the oil pressure setting unit 42 have the same functions as those of the piston crown surface temperature-related index estimation unit 41 and the oil pressure setting unit 42 of the first embodiment. Figure 4 ) has the same function.

[0193] The ignition timing control unit 1300 adjusts the timing of sending the ignition signal to the ignition coil 16 based on the mode information (or the state of the piston crown surface temperature) notified from the oil injection control unit 36, thereby controlling the ignition timing of the air-fuel mixture.

[0194] Fig.14 1 is a control block diagram showing an overview of control performed by the internal combustion engine control device 30A. When the mode information notified from the oil pressure setting unit 42 is "(2) warm-up promotion mode", the ignition timing control unit 1300 controls the piston crown surface temperature by advancing or retarding the ignition timing of the air-fuel mixture 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.

[0195] When the ignition timing is advanced compared to the optimal ignition timing with the best fuel consumption, that is, the optimal combustion speed, the cylinder pressure increases, thereby increasing the cylinder temperature, and increasing the amount of heat transferred from the cylinder to the piston crown surface. As a result, the piston crown surface temperature increases, and the time until the piston crown surface temperature reaches the lower limit temperature 805 can be shortened. As a result, the reduction effect of THC and PN is increased.

[0196] In addition, Fig.12 In the "(3) deposit suppression mode" shown, when the piston crown temperature exceeds the upper limit temperature 806, the heat transferred from the cylinder to the piston crown can be suppressed by delaying the ignition timing compared to the optimal ignition timing. As a result, the time until the piston crown temperature reaches below the upper limit temperature 806 can be shortened, and the deposit suppression effect can be improved.

[0197] In addition, when the mode information notified from the oil 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 mixed gas 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. For example, when a high engine speed is required, the ignition timing is advanced to rapidly increase the engine speed. In addition, when a high engine speed is not required, the ignition timing is retarded to reduce the engine speed early. As a result, it is easy to change the piston crown surface temperature, and the time that the piston crown surface temperature exists in the temperature range with less deposits can be prolonged. As a result, deposits can be suppressed and the effect of reducing THC and PN can be improved.

[0198] As described above, the internal combustion engine control device (internal combustion engine control device 30A) of the present embodiment has an ignition timing control unit (ignition timing control unit 1300) that advances the ignition timing set based on the load of the internal combustion engine when the temperature of the piston crown surface is lower than the lower limit temperature (lower limit temperature 805) of the temperature range in which the amount of deposit accumulation on the piston crown surface is less than the threshold value (threshold value 804). For example, the ignition timing is the optimal ignition period at which the combustion speed of the mixed gas in the combustion chamber is fast.

[0199] In addition, the internal combustion engine control device (internal combustion engine control device 30A) of the present embodiment has an ignition timing control unit (ignition timing control unit 1300) that advances or retards the ignition timing set based on the load of the internal combustion engine when the temperature of the piston crown surface is above the lower limit temperature (lower limit temperature 805) of the temperature range in which the amount of deposit accumulation on the piston crown surface is less than the threshold value (threshold value 804). For example, the ignition timing control unit advances the ignition timing when the target speed of the internal combustion engine is higher than the first speed, and retards the ignition timing when the target speed of the internal combustion engine is lower than the second speed that is lower than the first speed.

[0200] <Fourth embodiment>

[0201] The fourth embodiment of the present invention is an example in which the oil injection control unit has a mode selection unit in addition to the oil pressure setting unit 42. Fig.15 Provide explanation.

[0202] Fig.15 1 is a block diagram showing an overview of control of the internal combustion engine control device of this embodiment. Fig.15 As shown, the oil injection control unit 36A of this embodiment includes a piston crown temperature related 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, etc., thereby realizing the functions of each processing module.

[0203] The piston crown surface temperature related index estimation unit 41 has the same functions as the piston crown surface temperature related index estimation unit 41 ( Figure 4 The piston crown surface temperature related index estimation unit 41 sends the estimated piston crown surface temperature related index to the oil pressure setting unit 42A and the mode selection unit 1500.

[0204] The mode selection unit 1500 selects one of the "lubrication mode", "warm-up promotion mode" and "deposit suppression mode" based on the piston crown surface temperature related index or the measured value of the piston crown surface temperature, and sends the selection result (mode information) to the oil pressure setting unit 42A. In addition, the mode selection unit 1500 can determine that the piston lubricity is low and select the "lubrication mode" in the same manner as the first embodiment when the combustion operation duration of the internal combustion engine 100 is less than a specified value. In addition, the mode selection unit 1500 selects the "warm-up promotion mode" or the "deposit suppression mode" based on the piston crown surface temperature when the combustion operation duration is greater than a specified value.

[0205] The oil pressure setting unit 42A has the function of removing the mode selection function from the oil pressure setting unit 42 of the first embodiment. The oil pressure setting unit 42A sets the oil pressure according to the piston crown surface temperature based on the piston crown surface temperature related index or the measured value of the piston crown surface temperature and the mode information notified from the mode selection unit 1500. Fig. 9 The flow chart of FIG. 1 sets the oil pressure (target oil pressure) when implementing oil injection.

[0206] <Modification of the Fourth Embodiment>

[0207] In addition, the mode selection unit 1500 can have a function of selecting a mode by considering the thermal conductivity in addition to the piston crown surface temperature related index or the piston crown surface temperature, similar to the oil pressure setting unit 42 of the modified example of the second embodiment. Therefore, in this embodiment, it is also easy to control the crown surface temperature of the piston 21 within a specified range, which can improve the effect of suppressing THC and PN.

[0208] <Examples of vehicles equipped with control systems>

[0209] The control system in each of the above-mentioned embodiments is effective for an internal combustion engine equipped with an engine, but can also be used for a series hybrid vehicle that uses an engine as a generator, or a PHEV (Plug-in Hybrid Electric Vehicle) that can select the time to use the engine. Compared with an internal combustion engine equipped with an engine, a series hybrid vehicle and a PHEV can use an electric motor to ensure the power for driving the vehicle, so the start timing of the internal combustion engine can be arbitrarily set by combining with the present invention. For example, in the case where the piston crown temperature rises excessively to exceed the upper limit temperature 806, in the case of a series hybrid vehicle or a PHEV, by stopping the engine (idling stop), the amount of deposit accumulation and the increase in THC and PN can be suppressed.

[0210] Furthermore, the present invention is not limited to the above-mentioned embodiments, and various other application examples and modified examples can be adopted as long as they do not deviate from the main purpose of the present invention. For example, the above-mentioned embodiments describe their structures in detail and specifically in order to explain the present invention in an easy-to-understand manner, and are not limited to all the constituent elements that must be described. In addition, a part of the structure of a certain embodiment can be replaced with constituent elements of other embodiments. In addition, constituent elements of other embodiments can also be added to the structure of a certain embodiment. In addition, for a part of the structure of each embodiment, other constituent elements can also be added, replaced, or deleted.

[0211] In addition, for each of the above structures, functions, processing units, etc., part or all of them can be implemented in hardware, for example, by integrated circuit design, etc. As hardware, a broad processor device such as FPGA (Field Programmable Gate Array) and ASIC (Application Specific Integrated Circuit) can be used.

[0212] In the above-mentioned embodiment, the control lines and information lines are shown as necessary for explanation, and not all the control lines and information lines on the product are necessarily shown. In fact, it can be considered that almost all the components are connected to each other.

[0213] In order to make the invention easier to understand, the positions, sizes, shapes, ranges, etc. of the components shown in the drawings and the like sometimes do not represent the actual positions, sizes, shapes, ranges, etc. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings and the like.

[0214] Description of Reference Numerals

[0215] 21, 21A...Piston, 30, 30A...Internal combustion engine control unit (ECU), 36, 36A...Oil injection control unit, 41...Piston crown surface temperature related index estimation unit, 42, 42A...Oil pressure setting unit, 54...Oil pump, 101...Oil injection 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

1. An internal combustion engine control device for controlling an internal combustion engine having an oil pump for discharging lubricating oil at a specified flow rate and an oil injection system for injecting the lubricating oil discharged from the oil pump into a supplied portion of a piston, the internal combustion engine control device being characterized by: A control unit is provided for stopping the injection of the lubricating oil from the oil injection system or reducing the flow rate of the lubricating oil compared with the flow rate in the previous cycle when the temperature of the piston crown surface is lower than the lower limit temperature of the temperature range in which the amount of deposit accumulation on the piston crown surface is less than a threshold value.

2. The internal combustion engine control device according to claim 1, characterized in that: The control unit stops the injection of the lubricating oil from the oil injection system or reduces the flow rate of the lubricating oil compared to the flow rate in the previous cycle when the temperature of the piston crown surface and the amount of deposit accumulation on the piston crown surface are less than the lower limit temperature and below the upper limit temperature of the temperature range of the threshold.

3. The internal combustion engine control device according to claim 2, characterized in that: The control unit increases the flow rate of the lubricating oil compared with the flow rate of the previous cycle when the temperature of the piston crown surface is above the lower limit temperature and below the upper limit temperature of the temperature range of the threshold, and when the time variation of the temperature of the piston crown surface has an increasing tendency.

4. The internal combustion engine control device according to claim 3, characterized in that: The control unit executes injection of the lubricating oil from the oil injection system when the temperature of the piston crown surface exceeds an upper limit temperature of a temperature range in which the amount of deposit accumulation on the piston crown surface is less than the threshold value.

5. The internal combustion engine control device according to claim 1, characterized in that: The control unit determines 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 of the temperature range in which the amount of deposit accumulation on the piston crown surface is less than the threshold value, and executes the injection of the lubricating oil from the oil injection system when it is determined that the lubricity is insufficient.

6. The internal combustion engine control device according to claim 1, characterized in that: The piston includes: a base material forming the supplied portion; and a piston crown surface which is provided with a material having a lower thermal conductivity than the base material and faces the combustion chamber of the internal combustion engine.

7. The internal combustion engine control device according to claim 6, characterized in that: The control unit predicts the temperature of the piston crown surface in consideration of the thermal conductivity of the piston crown surface in addition to the temperature change of the piston crown surface, and controls injection of the lubricating oil from the oil injection system based on the predicted value of the temperature of the piston crown surface.

8. The internal combustion engine control device according to claim 1, characterized in that: The oil pump is a variable capacity pump, which includes: a pump housing having a storage portion; a rotor arranged in the storage portion and connected to the rotating shaft of the internal combustion engine in a manner that can transmit driving force; a cam ring in which the eccentricity between the rotation center of the rotor and its own center changes between a high discharge position and a low discharge position; and a control valve portion that changes the eccentricity of the cam ring under the control of the control portion.

9. The internal combustion engine control device according to claim 1, characterized in that: An ignition timing control unit is provided for advancing the ignition timing set based on the 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 the amount of deposit accumulation on the piston crown surface is less than a threshold value, The ignition timing is an optimal ignition period when the combustion speed of the mixed gas in the combustion chamber is fast.

10. The internal combustion engine control device according to claim 2, characterized in that: An ignition timing control unit is provided for advancing or retarding an ignition timing set based on a load of the internal combustion engine when the temperature of the piston crown surface is less than a lower limit temperature of a temperature range of the threshold value and the amount of deposit accumulation on the piston crown surface is less than or equal to a lower limit temperature of the temperature range of the threshold value, The ignition timing control unit advances the ignition timing when a target speed of the internal combustion engine is higher than a first speed, and retards the ignition timing when the target speed of the internal combustion engine is lower than a second speed that is lower than the first speed.

11. The internal combustion engine control device according to claim 1, characterized in that: The threshold value of the deposit accumulation amount is set based on a permissible amount of increase in the discharge amount of the emission-restricted substance from an initial value.

12. The internal combustion engine control device according to claim 1, characterized in that: The temperature of the piston crown surface is a piston crown surface temperature-related index correlated with the temperature of the piston crown surface, which is estimated based on the operating condition parameters of the internal combustion engine and the oil injection parameters used to inject the lubricating oil onto the back side of the piston, or a measurement value of a temperature sensor that measures the temperature of the piston crown surface.

13. An internal combustion engine control method of an internal combustion engine control device, the internal combustion engine control device controlling an internal combustion engine having an oil pump for discharging lubricating oil at a specified flow rate and an oil injection system for injecting the lubricating oil discharged from the oil pump to a supplied portion of a piston, the internal combustion engine control method comprising: Processing of judging whether the temperature of the piston crown surface is lower than the lower limit temperature of the temperature range in which the amount of deposit accumulation on the piston crown surface is less than a threshold value; and When the temperature of the piston crown surface is lower than the lower limit temperature of the temperature range in which the deposit accumulation amount is less than the threshold value, the injection of the lubricating oil from the oil injection system is stopped or the flow rate of the lubricating oil is reduced compared with the flow rate in the previous cycle.

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