JP2023151989A - Control device of internal combustion engine - Google Patents

Abstract

To improve the fuel consumption performance of an internal combustion engine having an oil jet mechanism.SOLUTION: A control device of an internal combustion engine including an oil jet mechanism having a piston oil jet nozzle for injecting oil toward a piston comprises: a piston temperature calculation part for calculating a piston temperature after the rotational speed deceleration at which the rotational speed of the internal combustion engine lowers; and a piston oil jet execution part for executing a piston oil jet by the oil jet mechanism when the piston temperature calculated by the piston temperature calculation part is higher than a preset threshold.SELECTED DRAWING: Figure 4

Description

The present invention relates to a control device for an internal combustion engine.

BACKGROUND ART Conventionally, there has been known a cooling device for an internal combustion engine that includes an oil jet mechanism that injects oil toward a piston from a piston oil jet nozzle to cool the piston (see, for example, Patent Document 1). In an internal combustion engine, when an air-fuel mixture is combusted in a combustion chamber, the temperature of the piston increases due to the heat of combustion. Therefore, it may be determined whether or not the oil jet mechanism should perform oil injection (piston oil jet) based on the temperature of the piston.

Japanese Patent Application Publication No. 2014-55549

By the way, in an internal combustion engine, the amount of intake air and the amount of fuel injection change depending on how the accelerator is depressed. Along with this, the combustion state of the air-fuel mixture in the combustion chamber changes, and the temperature of the piston also changes. As described above, although the temperature of the piston changes from moment to moment, it may be inconvenient to determine whether or not to implement piston oil jetting based on the piston temperature obtained at a certain point in time. For example, if the piston temperature is obtained and it is determined that a piston oil jet is to be performed based on that temperature, then the accelerator is turned off and the fuel supply is cut after the piston temperature is obtained. Assume that In this case, the air-fuel mixture in the combustion chamber is not combusted, and piston oil jetting is performed even though the temperature of the piston is reduced. In such a case, when the accelerator is pressed again to return from the fuel cut state, the piston temperature will have fallen below the temperature required for proper combustion, and as a result, fuel efficiency is expected to deteriorate. Ru. Conventionally, no countermeasures have been taken against such a phenomenon, and this point is also the same in Patent Document 1, and there is room for improvement.

Therefore, an object of the internal combustion engine control device disclosed in this specification is to improve fuel efficiency in an internal combustion engine equipped with an oil jet mechanism.

A control device for an internal combustion engine disclosed herein is a control device for an internal combustion engine equipped with an oil jet mechanism having a piston oil jet nozzle that injects oil toward a piston, and the control device is a control device for an internal combustion engine that includes an oil jet mechanism having a piston oil jet nozzle that injects oil toward a piston. a piston temperature calculation section that calculates the piston temperature after the rotation speed deceleration in which the rotation speed decreases; and when the piston temperature calculated by the piston temperature calculation section is higher than a preset threshold, the oil jet mechanism and a piston oil jet execution unit that executes a piston oil jet.

In the control device for an internal combustion engine configured as described above, the control device further includes a warm-up determination section that determines whether warming up of the internal combustion engine is completed, and the piston oil jet execution section is configured to perform the warm-up determination section. The number of executions of the piston oil jet before the warm-up completion determination by the warm-up determination section may be set to be greater than the number of executions of the piston oil jet after the warm-up completion determination by the warm-up determination section.

Furthermore, in the control device for an internal combustion engine configured as described above, the piston temperature calculation section may reduce the rotation speed based on the temperature of oil injected by the oil jet mechanism and the temperature of cooling water circulating within the internal combustion engine. It may be possible to calculate the subsequent piston temperature.

In the control device for an internal combustion engine configured as described above, the temperature of the cooling water may be a cooling water outlet temperature at an outlet from which the cooling water flows out from an engine main body included in the internal combustion engine.

An objective of the internal combustion engine control device disclosed in this specification is to improve fuel efficiency in an internal combustion engine equipped with an oil jet mechanism.

FIG. 1 is a schematic diagram showing an engine system including a control device for an internal combustion engine according to an embodiment. FIG. 2 is a block diagram showing a control device for an internal combustion engine according to an embodiment. FIG. 3 is a diagram showing a drive system of a vehicle equipped with an internal combustion engine according to an embodiment. FIG. 4 is a flowchart showing an example of piston oil jet control executed by the ECU included in the engine system of the embodiment. FIG. 5 is a diagram showing an example of a thermal circuit model for simulating heat transfer in the internal combustion engine of the embodiment. FIG. 6 is a time chart showing an example of temporal changes in accelerator ON/OFF states, assumed piston temperature at FC return, cooling water temperature, and oil temperature in an engine system equipped with the internal combustion engine control device of the embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings. However, in the drawings, the dimensions, proportions, etc. of each part may not be shown to completely match the actual ones. Furthermore, some drawings may be drawn with details omitted.

(Embodiment)
[Engine system configuration]
First, with reference to FIG. 1, a schematic configuration of an engine system 50 according to an embodiment will be described. The engine system 50 includes an engine 1, which is an example of an internal combustion engine, and a control device for the engine 1. The control device includes an ECU (Electronic Control Unit), a water temperature sensor 101, an oil temperature sensor 102, an accelerator opening sensor 103, a vehicle speed sensor 104 (see FIG. 2), and the like. The control device will be explained in detail later.

The engine 1 uses gasoline as fuel, and includes a cylinder block 11 and a cylinder head 20, which serve as an engine body 10. A cylinder is formed in the cylinder block 11 by a cylinder bore wall 11a. An open deck type water jacket 12 is provided within the cylinder bore wall 11a. The water jacket 12 is connected to a cooling water circulation path 13 of the engine 1. A water pump 14 is disposed in the cooling water circulation path 13 . The water pump 14 is electric, electrically connected to the ECU 100, and driven at an arbitrary rotation speed based on commands from the ECU 100. Note that the water jacket 12 may be of a closed deck type. Although the cooling water circulation path 13 is equipped with a radiator, it is omitted in FIG. 1 .

Although one cylinder is shown in FIG. 1, the engine 1 of this embodiment is an in-line four-cylinder internal combustion engine, and four cylinders are provided along the direction perpendicular to the page. A piston 15 is housed in each cylinder so as to be slidable along the axial direction of the cylinder. The piston 15 is connected to a crankshaft 17 via a connecting rod 16. The number of cylinders of an internal combustion engine to which this embodiment can be applied is not limited to four cylinders, and may be any other number of cylinders. Furthermore, the arrangement method is not limited to series, but may be a conventionally known arrangement method such as a V-shape.

The cylinder head 20 is mounted above the cylinder block 11. The cylinder head 20 is provided with an intake port 22a equipped with an intake valve 21a and an exhaust port 22b equipped with an exhaust valve 21b. Furthermore, the cylinder head 20 is provided with a combustion chamber 23 . A spark plug 24 is provided in the combustion chamber 23 . Note that a water jacket is also formed in the cylinder head 20, but it is omitted in FIG. 1.

An oil pan 25 is provided below the cylinder block 11. Oil used for lubricating and cooling various parts of the engine 1 is stored in the oil pan 25 . An oil strainer 26 is disposed within the oil pan 25. The oil strainer 26 includes an oil suction port 26a and is connected to an oil gallery 27 via a connecting pipe 26b. An oil pump 28 is provided in the oil gallery 27, and an oil filter 29 is provided downstream of the oil pump 28. The oil pump 28 is electric, electrically connected to the ECU 100, and driven at an arbitrary rotation speed based on commands from the ECU 100. When the rotation speed of the oil pump 28 increases, the oil pressure within the oil gallery 27 increases. Note that the oil pump 28 may be a mechanical oil pump that can change the discharge amount and discharge pressure (hydraulic pressure). Examples of such mechanical oil pumps include oil pumps using trochoid gears and oil pumps using vanes. In short, any pump that can control the oil discharge amount and discharge pressure can be used.

The oil gallery 27 circulates within the engine 1 and branches toward locations within the engine 1 where oil needs to be supplied as a lubricant or where oil needs to be supplied as a coolant.

The engine 1 includes an oil jet mechanism 30 that is branched from an oil gallery 27 and supplied with oil. The oil jet mechanism 30 includes a piston oil jet nozzle 31 that injects oil toward the lower surface of each piston 15. A check valve 32 is built into the base end of the piston oil jet nozzle 31 . When the rotation speed of the oil pump 28 increases and the oil pressure in the oil gallery 27 increases to a predetermined value, the check valve 32 opens, and oil is injected from the piston oil jet nozzle 31 toward the lower surface of the piston 15. is cooled. Note that the oil jet mechanism 30 not only cools the piston 15, but also distributes the heat taken from the piston 15 to each part of the engine 1 by using the oil injected toward the piston 15 as a heat medium. can. That is, the oil jet mechanism 30 also has a function of promoting warm-up of the engine 1.

The engine 1 can use a conventionally known gasoline alternative fuel such as ethanol or natural gas instead of gasoline. Further, the internal combustion engine may be a diesel engine. Further, instead of the oil pan 25, a dry sump system may be adopted in which oil is stored in an oil tank.

Next, with reference to FIG. 2, functions of various sensors and ECU 100 included in the control device will be described. The control device includes various sensors installed in the engine 1 and various sensors installed in various parts of the vehicle in which the engine 1 is mounted. Specifically, the various sensors include a water temperature sensor 101, an oil temperature sensor 102, an accelerator opening sensor 103, and a vehicle speed sensor 104. The water temperature sensor 101 is mounted near the outlet 12a of the water jacket 12, as shown in FIG. 1, and detects the outlet temperature of the cooling water. The outlet temperature is detected because the detection accuracy of the water temperature, which reflects the temperature state of the bore wall, is high. The oil temperature sensor 102 is attached to the oil pan 25 and detects the temperature of oil stored in the oil pan 25. The water temperature value detected by the water temperature sensor 101 and the oil temperature detected by the oil temperature sensor 102 are used to calculate the piston temperature, which will be described later. The accelerator opening sensor 103 detects the amount of depression of the accelerator pedal by the driver. Vehicle speed sensor 104 detects the traveling speed of a vehicle equipped with engine 1.

Note that although the engine 1 includes various sensors other than these, a description of these various sensors will be omitted here.

The ECU 100 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a backup RAM, and other storage devices. Arithmetic processing is executed based on programs and maps stored in the CPU, ROM, and other storage devices. The RAM is a memory that temporarily stores calculation results by the CPU, data input from various sensors, etc., and the backup RAM is a nonvolatile memory that stores data that should be saved when the engine 1 is stopped, etc. .

The ECU 100 functions as a clock section 100a, a first piston temperature calculation section 100b, an oil temperature acquisition section 100c, a second piston temperature calculation section 100d, and a drive state determination section 100e shown in FIG. The ECU 100 also functions as a warm-up determination section 100f, a piston oil jet execution section 100g, and an oil pump control section 100h.

The timer 100a measures a control execution interval s1 for implementing piston oil jet control, which will be described later, and measures an injection execution interval s2 from the piston oil jet executed last time. The control execution interval s1 and the injection execution interval s2 will be described in detail later.

The first piston temperature calculation unit 100b calculates an estimated piston temperature Tp for performing piston oil jet control. The oil temperature acquisition unit 100c acquires the oil temperature value detected by the oil temperature sensor 102. The second piston temperature calculation unit 100d calculates an estimated piston at the time of FC (Fuel Cut) return based on the estimated piston temperature Tp calculated by the first piston temperature calculation unit 100b and the oil temperature Toil acquired by the oil temperature acquisition unit 100c. Calculate temperature Tpx. The first piston temperature calculation section 100b and the second piston temperature calculation section 100d work together as a piston temperature calculation section that calculates the piston temperature after the rotation speed deceleration in which the rotation speed of the engine 1 decreases. Here, the rotational speed deceleration refers to a phenomenon in which when the accelerator is turned off and fuel is cut, the air-fuel mixture is not burned in the combustion chamber of the engine 1, and the rotational speed of the engine 1 decreases. Therefore, for example, a state in which a vehicle equipped with the engine 1 is running on an uphill road and the rotational speed of the engine 1 decreases due to an increase in load is not included. The calculation of the piston temperature after the rotational speed of the engine 1 is reduced will be described in detail later.

The drive state determination unit 100e determines the state of the drive system of the vehicle in which the engine 1 is mounted. That is, it is determined whether the vehicle is in a driving state (power running state) or a driven state. Referring to FIG. 3 , in the drive system of a vehicle equipped with the engine 1 , a crankshaft 17 included in the engine 1 is connected to wheels 43 via a transmission 41 and a drive shaft 42 . Therefore, the rotational output of the crankshaft 17 is transmitted to the wheels 43 via the transmission 41 and the drive shaft 42. The crankshaft 17 is also connected to an alternator 51 via a drive belt. The alternator 51 is rotated by the rotational output of the crankshaft 17 and generates electricity. The alternator 51 is electrically connected to a battery 52, and the electric power generated by the alternator 51 is stored in the battery 52. The battery 52 is connected to various parts of the vehicle that require electric power, and the electric oil pump 28 is also connected to the battery 52 and receives electric power. Note that a clutch device may be included in the drive system, but its explanation will be omitted here.

For example, when the drive system is in a driven state with the accelerator turned off, the inertial drive force is recovered from the wheels 43 toward the crankshaft 17 as shown by the arrow in FIG. form. When the vehicle is running and the wheels 43 are rotating, if the accelerator is turned off and the rotational output of the crankshaft 17 is not exerted, the inertial driving force of the wheels 43 is transferred to the crankshaft 17. transmitted to. In other words, the crankshaft 17 rotates without consuming new fuel. Even when the crankshaft 17 is rotating due to inertial driving force, the alternator 51 generates electricity, and the electric power is collected and stored in the battery 52. Operating the oil pump 28 using the electric power stored in the battery 52 in this manner is advantageous in terms of fuel efficiency. When the oil pump is mechanical, the oil pump is driven by the inertial driving force of the crankshaft 17, which is also advantageous in terms of fuel efficiency. In this way, when the vehicle is in a driven state, the energy used to operate the drive system is used to drive the oil pump 28, thereby increasing the efficiency of energy use and improving the fuel efficiency of the vehicle. I can do it.

Warm-up determination section 100f determines whether or not warm-up of engine 1 is completed. The piston oil jet execution unit 100g executes a piston oil jet by the oil jet mechanism 30 when a predetermined condition is satisfied.

When the oil jet execution unit 100g executes the piston oil jet, the oil pump control unit 100h drives the oil pump 28 and increases the oil pressure to a state where the piston oil jet is executed. Specifically, the rotation speed of the oil pump 28 is increased. If the oil pump is mechanical, switch the discharge pressure from the low pressure side to the high pressure side.

[Piston oil jet control]
Next, piston oil jet control will be explained with reference to FIGS. 4 to 6. ECU 100 performs piston oil jet control illustrated in the flowchart shown in FIG. Piston oil jet control is repeatedly executed at control execution intervals s1 after the engine 1 is started.

In step S1, the ECU 100 obtains the estimated piston temperature Tp and the oil temperature Toil. The estimated piston temperature Tp is the piston temperature at the time of performing the process of step S1, and is calculated by the first piston temperature calculation unit 100b. The oil temperature Toil is obtained by the oil temperature acquisition unit 100c acquiring the detected value of the oil temperature sensor 102.

Here, the estimated piston temperature Tp can be expressed as in the following equation (1).

Equation (1) includes the piston convergence temperature Tp∞. That is, the estimated piston temperature Tp expressed by equation (1) is expressed in the form of a transfer function using Laplace transform as a first-order lag value of the piston convergence temperature Tp∞.

The piston convergence destination temperature Tp∞ is the temperature at which the piston 15 converges based on the heat balance between each element included in the engine 1, and is expressed by the equation derived using the thermal circuit model illustrated in FIG. It can be calculated based on The thermal circuit model is a model for simulating heat transfer in the engine 1. Here, the meanings of the capital letters used in the thermal circuit model will be explained. The capital letter T in FIG. 5 indicates the temperature (K) in each element, and the capital letter Q indicates the amount of heat transfer (W) in each element. Moreover, the capital letter R indicates the thermal resistance (K/W) of each element, and the capital letter C indicates the heat capacity (J/K) of each element. Next, the meanings of the subscripts used in the thermal circuit model will be explained. Each subscript in FIG. 5 indicates the type of element included in the thermal circuit model, where g is the combustion gas, p is the piston 15, b is the cylinder bore wall 11a, w is the cooling water, and pj is the piston oil jet (oil ) is shown. Therefore, Tg indicates the combustion gas temperature. Further, Qp indicates the amount of heat transfer in the piston 15, Rp indicates the thermal resistance of the piston 15, Tp indicates the temperature of the piston 15, and Cp indicates the heat capacity of the piston 15. Furthermore, Qb represents the amount of heat transfer in the cylinder bore wall 11a, Rb represents the thermal resistance of the cylinder bore wall 11a, Tb represents the temperature of the cylinder bore wall 11a, and Cb represents the heat capacity of the cylinder bore wall 11a. Further, Qw represents the amount of heat transfer in the cooling water, Rw represents the thermal resistance of the cooling water, and Tw represents the temperature of the cooling water. Further, Qpj indicates the amount of heat transfer due to the oil injected by the piston oil jet, Rpj indicates the thermal resistance of the oil injected by the piston oil jet, and Tpj indicates the temperature of the oil injected by the piston oil jet. Formula (1) is expressed using these characters. Note that temperature Tpj=temperature Toil.

The piston convergence temperature Tp∞ is expressed by different formulas depending on whether the piston oil jet is executed or not. Specifically, the piston convergence temperature Tp∞ when the piston oil jet is executed is expressed by the following equation (2-1), and the piston convergence temperature Tp∞ when the piston oil jet is not executed is as follows. It is expressed by the equation (2-2).

In the piston oil jet control in this embodiment, the piston oil jet is executed within a range in which the piston temperature when the piston oil jet is executed does not fall below a temperature required for proper combustion in the engine 1. For this reason, equation (2-1) representing the piston convergence temperature Tp∞ when the piston oil jet is executed will be considered. In equation (2-1), Qp∞ indicates the amount of heat transfer in the piston 15 when combustion occurs in the combustion chamber, and is expressed as the value obtained by multiplying the combustion heat Qburn by the first coefficient K1. The first coefficient K1 can be obtained in advance through simulation or a suitability experiment using an actual machine.

Here, assume that the accelerator is turned off and the fuel supply is cut. When the fuel supply is cut, the air-fuel mixture is not combusted in the combustion chamber, and the temperature of the piston decreases. If piston oil jet is executed in such a state, the piston temperature may become too low. Therefore, assume that the fuel supply is cut. When the fuel supply is cut, there is no heat input and it can be considered that Qp∞=0. Therefore, in equation (2-1), if Qp∞=0, equation (2-1) can be rearranged as shown in equation (3) below.

By substituting this equation (3) for the piston convergence destination temperature Tp∞ in equation (1), the estimated piston temperature Tp at that point can be obtained.

In step S2, which is executed subsequent to step S1, the second piston temperature calculating section 100d calculates the assumed piston temperature Tpx at the time of FC return. The assumed piston temperature Tpx at the time of FC return corresponds to the piston temperature after the rotation speed is reduced. Here, the policy for calculating the assumed piston temperature Tpx at the time of FC return will be explained. When the accelerator is turned off and the fuel supply is cut, the piston temperature converges to the coolant temperature. The cooling water temperature also decreases, but it converges at least to the oil temperature. That is, the cooling water temperature Tw is expressed as in the following equation (4).

Therefore, the assumed piston temperature Tpx at the time of FC return exists between the estimated piston temperature Tp and the oil temperature Tpj (=Toil), which change sequentially from the time when the fuel cut is executed. Therefore, due to the fuel supply cut (FC), the expected piston temperature drop width ≦ (Tp - Tpj), and if this is calculated using the second coefficient K2, which is a number greater than or equal to 0 and less than 1, the assumed piston temperature drop width is K2 ( Tp−Tpj). Therefore, the assumed piston temperature Tpx at the time of FC return can be expressed by the following equation (5).

In this manner, in step S2, the assumed piston temperature Tpx at the time of FC return is calculated using equation (5).

In step S3, which is executed following step S2, the ECU 100 determines whether the engine 1 is in a driven state and the assumed piston temperature Tpx at the time of FC return is equal to or higher than the allowable piston temperature, which is a preset threshold. Determine.

The reason why the engine 1 is required to be in the driven state is that the oil pump 28 is driven by energy recovered by the inertial driving force of the crankshaft 17. Whether or not the vehicle is in the driven state is determined, for example, by whether the vehicle speed measured by the vehicle speed sensor 104 is equal to or higher than a predetermined vehicle speed (for example, equal to or higher than 20 km/h), and the condition that the accelerator is off is met. The determination can be made based on whether or not. When these conditions are met, the ECU 100 determines that the vehicle is in the driven state. Whether or not the accelerator is off is determined based on the detected value of the accelerator opening sensor 103. Executing the piston oil jet when the engine 1 is in the driven state is advantageous in terms of fuel consumption.

The allowable piston temperature is a threshold value used to determine whether or not to execute piston oil jetting, and is set as the lower limit of the piston temperature at which proper combustion can be performed in the engine 1.

Here, referring to FIG. 6, for example, between time t1 and time t2, between time t3 and time t4, and at timings after time t5, the assumed piston temperature Tpx at the time of FC return becomes equal to or higher than the allowable piston temperature. There is. Therefore, at these timings, the ECU 100 determines that the assumed piston temperature Tpx at the time of FC return is equal to or higher than the allowable piston temperature, which is a preset threshold. As shown in Equation (5), the assumed piston temperature Tpx at the time of FC return is the piston temperature after the rotational speed is reduced in consideration of the assumed piston temperature drop width K2 (Tp-Tpj). For this reason, if the temperature of the piston decreases due to a cut in the fuel supply, the piston oil jet is not executed, so that the temperature of the piston 15 at which appropriate fuel can be supplied is maintained. As a result, the fuel efficiency of the engine 1 can be improved. In addition, referring to FIG. 6, the assumed piston temperature Tpx at the time of FC return decreases at the timing when the accelerator is turned off (OFF), and there is a correlation between the degree of depression of the accelerator and the assumed piston temperature Tpx at the time of FC return. It can be seen that it has.

If the ECU 100 makes a positive determination (Yes) in step S3, the process proceeds to step S4, and if it makes a negative determination (no) in step S3, it repeats the process from step S2.

ECU 100 determines whether warm-up of engine 1 is completed in step S4. Specifically, ECU 100 determines whether warm-up of engine 1 is completed based on whether the coolant temperature is equal to or higher than a predetermined warm-up determination threshold. If warming up has been completed, the ECU 100 makes an affirmative determination in step S4 and proceeds to step S5. On the other hand, if warm-up has not been completed, the ECU 100 makes a negative determination in step S4 and proceeds to step S6.

In step S5, the ECU 100 determines whether or not the previously executed injection execution interval s2 from the piston oil jet has elapsed. Here, control execution interval s1<injection execution interval s2. If the ECU 100 makes a positive determination in step S5, the process proceeds to step S6, and if the ECU 100 makes a negative determination in step S5, it repeats the process from step S2.

In step S6, the piston oil jet execution unit 100g increases the discharge pressure of the oil pump 28 and issues a signal to the oil pump control unit 100h to execute the piston oil jet. After step S6, the process returns. The timer 100a starts measuring the control execution interval s1 from the time of this return.

Here, the relationship between the control execution interval s1 and the injection execution interval s2 will be explained in detail. As described above, the control execution interval s1 and the injection execution interval s2 have the relationship of control execution interval s1<injection execution interval s2. Therefore, the number of times the piston oil jet is executed before the warm-up completion determination is set to be greater than the number of times the piston oil jet is executed after the warm-up completion determination.

The reason why the number of times the piston oil jet is executed before the warm-up completion determination is set to be larger in this way is to promote warm-up of the engine 1. In the engine 1, the temperature of the piston 15 tends to rise more easily than the temperature of other parts. Therefore, in order to utilize oil as a heat medium, the piston oil jet is actively executed to transfer the heat of the piston 15 to other locations, such as the crank journal, thereby promoting warm-up of the engine 1. Note that this causes the piston 15 itself to be cooled, and acts in a direction in which the diameter of the piston 15 is reduced. As a result, the clearance with the inner periphery of the cylinder bore can be optimized, which is also advantageous in terms of fuel efficiency. On the other hand, after the completion of warm-up is determined, oil consumption can be suppressed by reducing the frequency of piston oil jetting. In other words, the more frequently the piston oil jet is executed, the more chance of oil draining increases, but by controlling the frequency of the piston oil jet, it is possible to suppress the oil draining and, by extension, the amount of oil consumed. can.

[effect]
According to the present embodiment, since it is determined whether or not to execute piston pill jetting based on the piston temperature after the rotation speed has been reduced, when the piston temperature decreases due to the fuel supply being cut, The piston oil jet is not executed and the temperature of the piston 15 is maintained to allow for proper fueling. As a result, the fuel efficiency of the engine 1 can be improved.

Further, according to the present embodiment, the number of times the piston jet is executed before the warm-up completion determination is set to be greater than the number of times the piston jet is executed after the warm-up completion determination. It is possible to achieve both increased engine speed and reduced oil consumption.

According to this embodiment, since the cooling water outlet temperature is used when calculating the estimated piston temperature, the estimated piston temperature and, by extension, the assumed piston temperature at the time of FC return can be calculated with high accuracy.

The above-mentioned embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications to these embodiments are within the scope of the present invention, and furthermore, it is within the scope of the present invention. It is obvious from the above description that various other embodiments are possible within the scope.

1 Engine 11 Cylinder block 11a Cylinder bore wall 12 Water jacket 13 Cooling water circulation path 14 Water pump 15 Piston 17 Crankshaft 28 Oil pump 30 Oil jet mechanism 31 Piston oil jet nozzle 32 Check valve 50 Engine system 100 ECU

Claims (4)

A control device for an internal combustion engine equipped with an oil jet mechanism having a piston oil jet nozzle that injects oil toward a piston,
The control device includes a piston temperature calculation section that calculates a piston temperature after the rotation speed deceleration at which the rotation speed of the internal combustion engine decreases, and a piston temperature calculation section that calculates a piston temperature that is higher than a preset threshold value. a piston oil jet execution unit that executes a piston oil jet by the oil jet mechanism when the oil jet mechanism is high;
control equipment for internal combustion engines, including The control device further includes a warm-up determination unit that determines whether or not warm-up of the internal combustion engine is completed;
The piston oil jet execution section determines the number of times the piston oil jet is executed before the warm-up completion determination by the warm-up determination section is greater than the number of times the piston oil jet is executed after the warm-up completion determination is made by the warm-up determination section. set to a high number of times,
A control device for an internal combustion engine according to claim 1. The piston temperature calculation unit calculates the piston temperature after the rotation speed is reduced based on the temperature of oil injected by the oil jet mechanism and the temperature of cooling water circulating within the internal combustion engine.
A control device for an internal combustion engine according to claim 1 or 2. The temperature of the cooling water is a cooling water outlet temperature at an outlet from which the cooling water flows out from an engine main body included in the internal combustion engine.
The control device for an internal combustion engine according to claim 3.

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