JP2004084526A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of restraining knocking in transition from high temperature control to low temperature control, and avoiding delay of response in short-time return from the low temperature control to the high temperature control. <P>SOLUTION: This engine comprises a cooling water temperature control means for maintaining the cooling water temperature high when the internal combustion engine is under a low load condition and maintaining the cooling water temperature low under a high load condition; a first cooling means for cooling the internal combustion engine by controlling the cooling water volume; and a second cooling means as an auxiliary cooling means for cooling the internal combustion engine not by controlling the cooling water volume. When a low temperature transition is instructed to transit the high temperature control for maintaining the cooling water temperature of the internal combustion engine high to the low temperature control for maintaining the cooling water temperature low, only the second cooling means is actuated. At the low temperature control transition time, the internal combustion engine is cooled only by the auxiliary cooling means, so as to prevent overcooling due to cooling responsiveness when returning to the high temperature control in a short time. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal combustion engine, and more particularly to an engine in which high water temperature is controlled.
[0002]
[Prior art]
The internal combustion engine normally circulates cooling water in a predetermined temperature range around the cylinder head, cylinder block, etc. for cooling during warming, especially when the temperature of the cooling water is higher than the predetermined temperature. Cooling water is passed through a radiator to release heat and cool.
[0003]
By the way, what is called a high water temperature control engine is known, which controls the outlet water temperature of the engine to be about 105 ° C., which is higher than that of a normal engine. In this way, there are advantages such as reduction of friction due to reduction of oil clay and improvement of fuel efficiency by reduction of heat loss.
[0004]
However, in the actual running of a vehicle equipped with an internal combustion engine, there is a transition to a high load state, and when shifting to the rapid acceleration from the high water temperature control as described above, the climbing traveling, the cooling water flow control valve is set. In a structure in which the internal combustion engine is cooled by opening the radiator and flowing low-temperature cooling water from the radiator, the cooling is inevitably delayed.
[0005]
Therefore, in a high water temperature control engine, knocking often occurs when the operation state shifts from high temperature control to low temperature control when the operating state becomes a high load state, and how to solve this is to effectively use this engine. This is one of the issues in utilizing.
[0006]
Japanese Patent Laying-Open No. 10-288138 discloses a knocking prevention device in such a case. In this device, ignition retard is performed to increase the amount of cooling water, and knocking is prevented by controlling a cooling fan. are doing.
[0007]
[Problems to be solved by the invention]
However, in the cooling by increasing or decreasing the amount of cooling water described above, as a result of poor cooling responsiveness, when the return from the low-temperature control to the high-temperature control is performed in a short time, if the temperature of the cooling water decreases at the time of this return, Soon it will not be possible to return to high temperature control. In actual running, there are many situations such as acceleration for a very short time, and there are many cases where it is desired to immediately return to the original high-temperature control.
[0008]
The present invention has been made in order to solve the above-described problem. In addition to suppressing knocking when shifting from high-temperature control to low-temperature control, a response delay when returning from low-temperature control to high-temperature control is performed in a short time. It is a technical object to provide an internal combustion engine that can avoid the above problem.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, when a low-temperature control shift command is issued, first, an auxiliary cooling means for cooling the internal combustion engine is operated without depending on the control of the amount of cooling water, and the high-temperature control is started in a short time. This is to avoid a response delay when a return command is issued.
[0010]
Therefore, the present invention has the following configuration. That is, when the internal combustion engine is at a low load, the cooling water temperature is maintained high, and when the internal combustion engine is at a high load, the cooling water temperature control means that maintains the cooling water temperature low, and the internal combustion engine is cooled by controlling the amount of the cooling water. The first cooling means, comprising a second cooling means which is an auxiliary cooling means for cooling the internal combustion engine without controlling the amount of cooling water,
By the cooling water temperature control means, when there is a low temperature control transition command to transition from high temperature control to maintain the cooling water temperature of the internal combustion engine high to low temperature control to maintain the cooling water temperature of the internal combustion engine low, only the second cooling means Is operated.
[0011]
At the time of transition to low-temperature control, cooling of the internal combustion engine is performed only by the auxiliary cooling means. Therefore, even when returning to high-temperature control in a short time, excessive cooling due to cooling responsiveness can be prevented.
[0012]
Further, when the low-temperature control shift command continues for a first predetermined time or more, it is preferable to operate the first cooling unit in addition to the second cooling unit. When low-temperature control is continued for a predetermined time or more, stable low-temperature control can be realized by controlling the amount of cooling water.
[0013]
When the low-temperature control transition command has continued for a second predetermined time longer than the first predetermined time, the operation of the second cooling means can be stopped. If low-temperature control by controlling the original amount of cooling water is performed, it is preferable that the auxiliary cooling means be stopped for the time being to suppress energy consumption.
[0014]
When the low-temperature control shift command continues for a third predetermined time longer than the second predetermined time, the second cooling means can be restarted.
[0015]
Thereafter, when the low-temperature control for a long time is continued, the auxiliary cooling means can be operated again to perform efficient cooling in accordance with the operating condition.
[0016]
The second cooling means may be an oil jet that injects oil to a piston in a cylinder. According to the oil jet for cooling the piston, the oil for cooling is directly injected into the piston for cooling, so that the cooling response of the combustion chamber is improved and knocking can be effectively prevented.
[0017]
In this case, the oil injection is preferably performed by an electric oil jet. If the oil jet is operated by the electric pump, the cooling performance does not decrease due to insufficient pressure in the low rotation speed range, which is advantageous.
[0018]
The low-temperature control shift command can be issued based on at least one of a throttle opening, an engine speed, and a coolant temperature.
[0019]
According to the present invention, even when the return from the low-temperature control to the high-temperature control is performed in a short time, the temperature of the cooling water has not yet dropped at the time of the return, so that the control can be immediately returned to the high-temperature control. Further, when shifting from high-temperature control to low-temperature control, knocking is effectively suppressed by cooling by the auxiliary cooling means, particularly when an oil jet for directly cooling the piston is used.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, specific embodiments of the internal combustion engine of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine according to the present embodiment and an intake and exhaust system thereof. The internal combustion engine 1 shown in FIG. 1 is a four-cycle gasoline engine having four cylinders 2, and a cooling water passage is formed in each of the cylinder head 1a and the cylinder block 1b.
[0022]
FIG. 3 is a cross-sectional view showing the structure around the combustion chamber. A cooling water passage 10 through which cooling water flows to cool the fuel injection valve 13, the intake valve 27a, the exhaust valve 27b, and the like is provided in the cylinder head 1a. Is formed. On the other hand, a cooling water passage 11 is provided in the cylinder block 1b so as to flow on the side surface of the cylinder liner 12 of each cylinder.
[0023]
The cooling system of the internal combustion engine 1 includes a first electronic flow control valve 2 provided on the inlet side of the internal combustion engine 1, a mechanical water pump 3, and a second electronic flow control valve provided on the outlet side of the cylinder block 1b of the internal combustion engine 1. 4, a radiator 5 provided in the middle of the cooling water circulation path, a bypass pipe 9 forming a circulation path 6 bypassing the radiator 5, and the like.
[0024]
In addition, the internal combustion engine 1 has a configuration in which a circulation path provided with the heat storage tank 7 and the electric water pump 8 is formed, and is capable of preheating when the internal combustion engine 1 is started and storing heat when the internal combustion engine 1 is stopped.
[0025]
The radiator 5 has a water channel through which the cooling water flows, and has a fin (not shown) outside a pipe forming the water channel. The heated cooling water is cooled by a cooling fan (not shown) as necessary when passing through the inside of the radiator 5.
[0026]
In the internal combustion engine 1 provided with such a cooling system, at the time of high temperature control in a low load state, the cooling water circulates in a path indicated by an arrow in FIG.
[0027]
That is, the cooling water heated by the engine waste heat or the like from the internal combustion engine 1 passes through the internal combustion engine 1 and passes through the bypass pipe 9 by the operation of the mechanical pump 3, and again the cooling water passages 10 and 11 inside the internal combustion engine 1. Sent to At this time, the flow rate of the cooling water is adjusted by controlling the degree of opening and closing of the first electronic flow rate control valve 2 and the second electronic flow rate control valve 4, and the cooling water temperature is maintained at about 105 ° C. In this state, the opening degree of the second electronic flow control valve 4 is reduced, and the cooling water is adjusted so that most of the cooling water flows through the cooling water passage 10 on the cylinder head 1a side of the internal combustion engine 1.
[0028]
On the other hand, when low-temperature control is performed when the internal combustion engine 1 is under a high load, a circulation path of the cooling water is formed as shown in FIG. Here, the opening degree of the first electronic flow control valve 2 and the second electronic flow control valve 4 becomes almost maximum, and the cooling water from the internal combustion engine 1 is discharged through the cylinder head 1a and the cylinder block 1b, It is cooled via the radiator 5 and sent again to the cooling water passages 10 and 11 of the internal combustion engine 1. At this time, the flow rate of the cooling water increases, and the cooling water is cooled as needed by the radiator 5 and a cooling fan (not shown), so that the temperature of the water decreases and each part of the internal combustion engine 1 is actively cooled. You.
[0029]
On the other hand, in the lubrication system, the oil stored in the oil pan is sucked up by an electric oil pump (not shown), sent to various parts of the internal combustion engine 1 through an oil filter, and smoothly operates the components of the valve train. 1a is also cooled, but a part thereof is pressurized by the electric oil pump 38 and is injected from a nozzle 68 as an oil jet as described later.
[0030]
By the way, various sensors are attached to each part of the internal combustion engine 1, and these output signals relating to the operating state of the engine. First, the accelerator opening sensor 41 is connected to an accelerator pedal (not shown) and outputs a detection signal according to the amount of depression of the accelerator pedal.
[0031]
Further, the crank angle sensor 43 outputs a detection signal (pulse) every time the crankshaft of the internal combustion engine 1 rotates by a certain angle, and can calculate the engine speed based on the time interval of the detection signal. .
[0032]
Further, a temperature sensor 42 is provided in the cooling water passage 10 connected to the outlet of the cylinder head 1a of the internal combustion engine 1 to measure the temperature of the cooling water.
[0033]
Next, an auxiliary cooling device as a second cooling means provided in the internal combustion engine 1 will be described. Here, an electric oil jet including a nozzle 37 for injecting oil to the piston 23 in the cylinder and an electric oil pump 38 is provided as an auxiliary cooling device.
[0034]
As shown in FIG. 3, a cylindrical cylinder liner 22 formed in a cylinder block 1b is fitted into the combustion chamber 20, and a cylinder head 1a is joined to an upper portion of the cylinder liner 22, and a piston 23 is inserted into the cylinder liner 22 from below. It is formed by inserting.
[0035]
The cylinder head 1a is provided with an intake port 27 for sucking air into the combustion chamber 20 and an exhaust port 31 for exhausting fuel after burning in the combustion chamber 20. The intake port 27 and the exhaust port 31 are respectively provided with intake valves. It is opened and closed by 32 and an exhaust valve 33 to perform intake and exhaust in the combustion chamber 20.
[0036]
A piston 23 is fitted into the cylinder liner 22 below the combustion chamber 20. The piston 23 is pin-connected to a connecting rod 35 via a piston pin 34 provided on the pin boss 28, and the connecting rod 35 is connected to a crankshaft 36.
[0037]
Inside the piston 23, there are provided a cooling cavity 26 through which oil serving as a cooling liquid flows, an injection hole 29a for injecting oil into the cooling cavity 26, and a discharge hole 29b for discharging oil used for cooling from the cooling cavity 26, respectively. Is formed.
[0038]
The cooling passage 26 is an annular passage provided in the top of the piston 23. The cooling cavity 26 is partially opened at a position where the pin boss 28 is provided, and a part of the pin boss 28 is cooled. It faces the cavity 26. The injection hole 29a is formed on the lower surface of the crown and communicates with the cooling cavity 26, and the discharge hole 29b communicating with the cooling 26 is formed on the lower surface of the opposite crown.
[0039]
A nozzle 37 for injecting oil as a cooling liquid toward the injection hole 29 a of the piston 23 is provided below the combustion chamber 20, and the injected oil is pressurized by an electric oil pump 38. Therefore, if the electric oil pump 38 is started by a command from the ECU 40, a predetermined oil jet can be operated even when the internal combustion engine 1 is in a low rotation range.
[0040]
In such cooling of the piston or the like by the electric oil jet, the oil of the nozzle 37 is injected and sprayed onto the pin boss surface of the piston. Since the piston 23 reciprocates in the cylinder, the oil is injected into the cooling cavity 26 only while the injection hole 29 a is located at the passage point of the oil injected from the nozzle 37.
[0041]
As shown in FIG. 3, the oil injected from the nozzle 37 flows into the cooling cavity 26 from the injection hole 29 a, and the oil flows through the cooling cavity 26, so that heat exchange between the oil and the piston 23 is performed. Done. Further, cooling around the pin boss 28 through which the piston pin 34 penetrates becomes possible. The oil that has flowed in the cooling cavity 26 is discharged outside through the discharge hole 29b.
[0042]
The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU: Electronic Control Unit) 40 for controlling the internal combustion engine 1. The ECU 40 is a unit that controls the operating state of the internal combustion engine 1 according to the operating conditions of the internal combustion engine 1 and the driver's requirements.
[0043]
Various sensors provided in each part of the internal combustion engine 1, a crank position sensor 41, a water temperature sensor 42, an accelerator opening sensor 43, and other sensors shown in the figure are connected to the ECU 40 via electric wiring. An output signal is input.
[0044]
The ECU 40 includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), a backup RAM in which stored information is not erased even after the operation is stopped, a timer counter, and an A / D converter. An input port and an output port are provided with a logical operation circuit configured by being connected by a bidirectional bus.
[0045]
The ECU 40 inputs detection signals of various sensors through input ports, and based on these signals, the CPU performs basic control on fuel injection and the like of the internal combustion engine 1 from a program stored in the ROM, Various controls according to the operating state of the internal combustion engine 1 are executed.
[0046]
The above-described ECU 40 that controls the cooling system that cools the internal combustion engine 1 and also cools the oil and the lubrication system that supplies the oil serving as the cooling liquid to each cylinder through the nozzles 37 constitute a part of the cooling water temperature control means. It is.
[0047]
The cooling water temperature control is performed through the operation of various members of the cooling system, including the ECU 40 that outputs a command signal related to the control.
[0048]
Next, cooling water temperature control in the internal combustion engine of the present invention will be described.
(Embodiment 1)
The internal combustion engine 1 maintains the cooling water temperature at about 105 ° C. when the load is low, but suppresses knocking by controlling the cooling water temperature low when the load is high, such as when accelerating or climbing a hill.
[0049]
Specifically, the flow rate of the cooling water circulating through the internal combustion engine 1 is controlled by adjusting the opening degrees of the first electronic flow rate control valve 2 and the second electronic flow rate control valve 4, and by opening and closing them. In addition to such cooling means, an auxiliary cooling means that can cool the internal combustion engine without increasing the flow rate of the cooling water cools the piston 23 with oil.
[0050]
In such an internal combustion engine 1, the CPU reads the throttle opening (θ), the engine speed (N), and the outlet water temperature (Tw) of the internal combustion engine 1, and shifts to low-temperature control in order to suppress knocking. Determine if it is a situation.
[0051]
In the present embodiment, whether or not to shift from the high temperature control to the low temperature control is determined based on the throttle opening (θ), the engine speed (N), and the outlet water temperature (Tw) of the internal combustion engine 1. Specifically, when it is determined from the operation determination map as shown in FIG. 4 that the operation state of the internal combustion engine is in the knocking occurrence region, the process shifts to low-temperature control. Such a map is stored in the ROM of the ECU 40 in advance, and a command is issued in accordance with an operation state based on the control parameter to operate the oil jet electric pump 38 or to operate the first flow control valve 2 for the cooling water and the cooling water. The low temperature control is executed by controlling the second flow control valve 4.
[0052]
Here, first, it is determined whether or not a condition for operating the electric oil pump 38 for executing the oil jet as the auxiliary cooling means is satisfied. When the electric oil pump 38 is to be operated, it is operated and only the cooling of the piston 23 by the oil jet is performed.
[0053]
When the operation command of the electric oil pump 38 continues for a predetermined time or more, the first electronic flow control valve 2 and the second electronic flow control valve 4 are opened to operate the main cooling means, and the internal combustion engine 1 is opened. The internal combustion engine 1 is cooled by increasing the flow rate of the amount of cooling water circulating in the internal combustion engine.
[0054]
Next, a flowchart of the present embodiment is shown in the drawings, and the cooling control of the internal combustion engine will be described below according to the flowchart.
[0055]
The routine for executing this flowchart is stored in the ROM in advance, and is repeatedly executed by the CPU every predetermined time (for example, every time the crank position sensor 43 outputs a pulse signal) while the internal combustion engine 1 is operating. It is a routine that is performed.
[0056]
First, in S101, the CPU calculates the throttle opening (θ), the engine speed (N), and the outlet water temperature (Tw) of the internal combustion engine 1 using the accelerator opening sensor 41, the water temperature sensor 42, and the crank angle sensor 43. It is read out based on the signals from the sensors, and it is determined according to the map shown in FIG. 4 whether or not the condition for operating the electric oil pump (EPO) 38 for executing the oil jet is satisfied. Specific conditions include whether the throttle opening (θ) is larger than a predetermined opening (θ1), whether the engine speed (N) is larger than a predetermined engine speed (N1), and It is determined whether the outlet water temperature (Tw) of the internal combustion engine 1 is higher than a predetermined temperature.
[0057]
In S101, when it is determined that the condition for operating the electric oil pump (EPO) 38 is not satisfied, the process proceeds to S105, and the CPU determines whether the electric oil pump (EPO) 38, the first electronic flow control valve 2, The process returns to S101 without opening the second electronic flow control valve 4, and the next determination is made.
[0058]
On the other hand, if it is determined in S101 that the condition for operating the electric oil pump (EOP) 38 is satisfied, the CPU proceeds to S102 and activates it.
[0059]
Next, the process proceeds to S103, and it is determined whether or not the operation command continuation time (t) of the electric oil pump (EOP) 38 is equal to or longer than a first predetermined time (t1). If the operation command duration (t) is equal to or longer than the first predetermined time (t1), the process proceeds to S104, in which the first electronic flow control valve 2 and the second electronic flow control valve 4 are opened, and the flow rate of the cooling water And returns to S101 to make the next determination.
[0060]
Conversely, if the operation command continuation time (t) is not equal to or longer than the first predetermined time (t1), the process returns to S101 without opening the first electronic flow control valve 2 and the second electronic flow control valve 4, and the next time Make a decision.
[0061]
In this embodiment, when the internal combustion engine 1 shifts to the high load state, first, the occurrence of knocking is suppressed by directly cooling the piston 23. Cooling the piston 23 in this manner is effective for lowering the temperature of the combustion chamber and suppressing knocking. When the high-load control returns to the high-temperature control without continuing for a long time, the temperature of the cooling water hardly decreases, so that the control can return to the high-temperature control without delay in response.
[0062]
Conversely, when the high load state continues for a predetermined time or more, the cooling water is increased to lower the water temperature so that stable cooling is possible. Therefore, it is possible to cope with the actual driving situation.
(Embodiment 2)
In this embodiment, only portions different from the first embodiment will be described. In the first embodiment, first, the occurrence of knocking is suppressed by directly cooling the piston 23, and when the state to be controlled at a low temperature continues for a predetermined time (t1) or more, the amount of cooling water is increased. Reduce water temperature. Executing such control is exactly the same in the present embodiment, but after that, when the state to be controlled at low temperature continues for a second predetermined time (t2) longer than the predetermined time (t1) or more. Stops the cooling of the piston 23. This is because it is preferable to stop the operation of the auxiliary cooling means by giving priority to the state in which the cooling is continued due to the temperature drop of the originally stable cooling water from the viewpoint of energy consumption and the overall cooling effect.
[0063]
Furthermore, when the state to be controlled at a low temperature continues for a predetermined time (t3) longer than the second predetermined time (t2), the degree of high load is strong, and the internal combustion engine 1 needs to be further cooled. It is determined that it is in the state, and the cooling of the piston 23 that has been once stopped is restarted. Thus, the occurrence of knocking is effectively suppressed.
[0064]
Next, a description will be given in accordance with the flowchart shown in FIG. 6, but the description of S201 to S205 indicating the control overlapping with the first embodiment will be omitted.
[0065]
After opening the first electronic flow control valve 2 and the second electronic flow control valve 4 in S204, in S206, the operation command duration (t) of the electric oil pump (EOP) 38, in other words, the duration of the low temperature control. It is determined whether or not the time is equal to or longer than a second predetermined time (t2) longer than the first predetermined time (t1). When an affirmative determination is made, the process proceeds to S207, in which the electric oil pump (EPO) 38 is stopped to stop cooling by the oil jet. If the answer is no, the process returns to S201 to make the next determination.
[0066]
Next, the process proceeds to S208, and it is determined whether or not the continuation time of the low-temperature control has continued for a third predetermined time (t3) longer than the second predetermined time (t2). If an affirmative determination is made, the process proceeds to S209, in which the electric oil pump (EPO) 38 is restarted to perform cooling by an oil jet in addition to increasing the amount of cooling water. On the other hand, if the answer is negative, the process returns to S201, and the next determination is made.
[0067]
As described above, when the CPU executes the cooling water temperature control routine, the knocking of the internal combustion engine 1 of the high water temperature control according to the present invention is efficiently suppressed.
(Other embodiments)
Various structures can be used for the oil jet for cooling the piston. For example, an electric oil pump may not be used in addition to an oil injection nozzle provided with a plurality of oil injection nozzles, a piston having no cooling cavity through which oil flows, or the like. However, it is necessary that stop and start of oil injection can be controlled.
[0068]
Further, in the above-described embodiment, the first electronic flow control valve 2 and the second electronic flow control valve 4 are used for controlling the flow rate of the cooling water. The flow rate of the circulating cooling water may be controlled by the thermostat. In this case, a material corresponding to a high water temperature (about 105 ° C.) is used. Furthermore, an electronic thermostat can be used.
[0069]
【The invention's effect】
According to the internal combustion engine according to the present invention, even when the return from the low-temperature control to the high-temperature control is performed in a short time, the temperature of the cooling water hardly decreases at the time of the return, so that it is possible to immediately return to the high-temperature control. .
[0070]
Further, when shifting from high-temperature control to low-temperature control, cooling by the auxiliary cooling means, particularly when an oil jet that directly cools the piston is used, effectively suppresses knocking due to such cooling. In addition, the advantage of the internal combustion engine of high water temperature control can be fully utilized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a cooling system of an internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a diagram showing a schematic configuration of a cooling system of the internal combustion engine according to the embodiment of the present invention and a flow of cooling water under a high load.
FIG. 3 is a diagram showing a configuration around a combustion chamber and a structure of an oil jet.
FIG. 4 is a view showing an operation determination map of an oil jet.
FIG. 5 is a flowchart illustrating an execution flow of cooling water temperature control according to the first embodiment of the present invention.
FIG. 6 is a flowchart showing an execution flow of cooling water temperature control according to Embodiment 2 of the present invention.
[Explanation of symbols]
1 Internal combustion engine 2 First electronic flow control valve 4 Second electronic flow control valve 5 Radiators 10 and 11 Cooling water passage 20 Combustion chamber 23 ..Piston 26 ... Cooling cavity 28 ... Pin boss 32 ... Exhaust valve 33 ... Intake valve 35 ... Connecting rod 36 ... Crank shaft 37 ... Nozzle 38 ... Electric oil pump 41 ... Accelerator opening sensor 42 ... Crank angle sensor

Claims (7)

Cooling water temperature control means for maintaining the cooling water temperature high when the internal combustion engine is in a low load state and maintaining the cooling water temperature low when the internal combustion engine is in a high load state, and cooling the internal combustion engine by controlling the cooling water amount The first cooling means, comprising a second cooling means which is an auxiliary cooling means for cooling the internal combustion engine without controlling the amount of cooling water,
By the cooling water temperature control means, when there is a low temperature control transition command to transition from high temperature control to maintain the cooling water temperature of the internal combustion engine high to low temperature control to maintain the cooling water temperature of the internal combustion engine low, only the second cooling means An internal combustion engine characterized by operating. 2. The internal combustion engine according to claim 1, wherein when the low-temperature control shift command continues for a first predetermined time or more, the first cooling unit is operated in addition to the second cooling unit. 3. 3. The internal combustion engine according to claim 2, wherein the operation of the second cooling unit is stopped when the low-temperature control shift command continues for a second predetermined time longer than the first predetermined time. 4. The internal combustion engine according to claim 3, wherein when the low-temperature control transfer command continues for a third predetermined time longer than a second predetermined time, the second cooling unit is restarted. 5. 4. The internal combustion engine according to claim 1, wherein the second cooling unit is an oil jet that injects oil to a piston in a cylinder. 5. The internal combustion engine according to claim 5, wherein the second cooling means is an electric oil jet that injects oil to a piston in a cylinder. The internal combustion engine according to any one of claims 1 to 6, wherein the low-temperature control shift command is issued based on at least one of a throttle opening, an engine speed, and a coolant temperature.

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