JP3839242B2 - Internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to reducing deposit adhesion in an injector of an internal combustion engine.
[0002]
[Prior art]
The deposit that adheres to and accumulates in the injection hole of the injector of the internal combustion engine evaporates a part of the fuel remaining in the injection hole after the fuel injection stops, and then the remaining liquid phase component is heated and solidified. It is known that The solidification of the fuel proceeds by causing the deposit precursor contained in the liquid phase component to undergo a dehydrogenation reaction or a polymerization reaction. As a result, the cross-sectional area of the injection hole is reduced as the deposit accumulates, and the fuel injection flow rate is reduced.
[0003]
In particular, in an in-cylinder injection type internal combustion engine, the injector is exposed to a high temperature by the combustion heat of the fuel in the combustion chamber, and in order to suppress the adhesion of the deposit, a material with high heat dissipation and a high thermal conductivity is used. It is desirable to use it. However, since the valve body constituting the valve mechanism is required to have a considerable degree of durability at the tip, the selection range of the material is narrow and it is difficult to achieve both thermal conductivity. Therefore, as in the technique described in Japanese Patent Application Laid-Open No. 9-287525, the temperature of the engine body is detected, and when the detected temperature is high, the operation parameters for controlling the engine body are set so that combustion in the combustion chamber becomes slow. In some cases, the temperature at the tip of the injector is reduced so that the temperature at the tip of the injector is prevented from rising by retarding the ignition timing, and deposit accumulation is suppressed. I am trying. Japanese Patent Application Laid-Open No. 9-264232 discloses that deposit accumulation can be well suppressed by keeping the temperature of the nozzle hole lower than the 90% distillation temperature of the fuel used.
[0004]
[Problems to be solved by the invention]
However, if the operating parameters of the internal combustion engine are determined only for the purpose of reducing deposits, there is a risk that the operating performance of the internal combustion engine, such as fuel efficiency, may be reduced.
[0005]
The present invention has been made in view of the above circumstances, and an object thereof is to provide an internal combustion engine capable of reducing deposits while maintaining the operation performance of the internal combustion engine.
[0006]
[Means for Solving the Problems]
  The present invention relates to an operating state detecting means for detecting an operating state of an engine body in an engine body that generates power by burning fuel spray injected from a nozzle hole formed at a tip portion of the injector in a combustion chamber. In the internal combustion engine provided with operation parameter setting means for setting an operation parameter for controlling the engine body based on the detected operation state,A plurality of injectors are provided in a one-to-one correspondence with a plurality of cylinders,
  Time interval detection means for detecting a time interval from the injection of the injector to the next injection of the injector as the operating state detection meansAnd a cooling water temperature detecting means for detecting the temperature of the cooling water for cooling the engine body, and the temperature of the tip portion of the injector having the highest temperature tendency among the plurality of injectors is substantially increased. Equipped with temperature detecting means to detect,
  The operation parameter setting means, the longer the detected time interval,The higher the detected coolant temperature and the higher the detected tip temperature of the injector, the more likely it is that the deposit is likely to increase.The operating parameter is a value for lowering the temperature in the combustion chamber;Slow combustion and suppress the increase of depositSet as follows.
[0007]
  When it is necessary to prevent deposits from being deposited for a long time until the next injectionIn other words, when there is a high probability of an increase in depositsThe value in which the operating parameter increases the temperature in the combustion chamber is allowed as the temperature in the combustion chamber decreases and the time until the next injection is shorter. Therefore, the operation efficiency is high and the deposit can be suppressed.
[0008]
  For example,The time interval detection means is composed of engine rotation detection means so that the time interval can be determined based on the engine rotation.
[0009]
Since the fuel injection is performed substantially synchronously with the engine rotation, the time interval from the injection of the injector to the next injection of the injector is shorter as the engine speed is higher. That is, the length of the time interval is known from the engine speed. The engine speed indicates a basic operation state in the internal combustion engine, and is a basic operation parameter in the control of the engine body. Therefore, it is not necessary to newly provide time interval detection means.
[0010]
  Also,The engine body is provided with cooling water temperature adjusting means for adjusting the temperature of cooling water for cooling the engine body,
And a control means for controlling the cooling water temperature adjusting means.
  When the detected time interval is longer than a preset time threshold, the control means is configured such that the cooling water temperature is set to a preset target temperature.And slow combustion that suppresses the increase in deposit
Set as follows.
[0011]
  As the coolant temperature increases, the operating parameter changes in a direction to lower the temperature in the combustion chamber. Depending on the operating conditions, etc., the temperature state of the engine body differs.For example, if the engine body is in a `` cold '' state like a cold start, its heat removal capability is sufficient,The probability of an increase in deposits is low,Rapid combustion which raises the temperature of the combustion chamber is allowed, the operation efficiency is good, and the deposit can be suppressed.
[0012]
  Also,Comprising temperature detecting means for detecting the temperature of the tip of the injector;
  The operating parameter setting means has a value that decreases the temperature in the combustion chamber as the detected tip temperature of the injector is higher.And slow combustion that suppresses the increase in depositSet as follows.
[0013]
As the injector tip temperature increases, the operating parameter changes in a direction to lower the temperature in the combustion chamber. Therefore, even if the propensity for the injector tip temperature to rise due to changes over time, etc. appears, the operating parameters will follow up to give an appropriate temperature in the combustion chamber, and the operation efficiency will be good. , The deposit can be suppressed.
[0014]
  At this timeA plurality of injectors are provided so as to correspond to the plurality of cylinders on a one-to-one basis;
  The temperature detecting means is configured to substantially detect the temperature of the tip portion of the injector having the highest tendency to increase in temperature among the plurality of injectors.
[0015]
Since the operating parameters are set based on the temperature at the tip of the injector having the highest temperature trend, it is possible to obtain a good deposit adhesion suppressing action for all cylinders without providing temperature detection means for all cylinders. it can.
[0016]
  Claim2In the described invention, in the configuration of the invention of claim 1, the engine body is provided with cooling water temperature adjusting means for adjusting the temperature of the cooling water,
  And a control means for controlling the cooling water temperature adjusting means.
  When the detected time interval is longer than a preset time threshold, the control means is configured such that the cooling water temperature is set to a preset target temperature.And slow combustion that suppresses the increase in depositSet as follows.
[0017]
For example, if the engine body is heated and the time interval from the injection of the injector to the next injection of the injector is long, it can be said that deposits are likely to adhere, but in this case the cooling water is adjusted to the target temperature Therefore, the temperature of the engine body including the injector tip also moves in the suppression direction, and deposit adhesion is suppressed. Since the engine body temperature is not lowered naturally, the operation efficiency is not lowered.
[0018]
  Claim3In the described invention, the claims1 or 2In the configuration of the invention, the engine main body is a cylinder injection type in which a tip end portion of the injector projects into the combustion chamber and fuel is directly injected into the combustion chamber from the injection hole.
[0019]
In the cylinder injection type internal combustion engine, the tip of the injector is exposed to high-temperature combustion gas, and thus the present invention is particularly suitable.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
  (Basic configuration)
  1 and 2 show the internal combustion engine of the present invention.Basic configurationIndicates. The internal combustion engine will be described as power for a vehicle in the following description. The engine body 1 of the internal combustion engine is a four-cylinder in-cylinder injection type. Although not shown, each cylinder has a four-valve structure including two intake valves and two exhaust valves, and each cylinder has an injector 11A. , 11B, 11C, and 11D.
[0021]
FIG. 2 shows the state of attachment of the injector. Although only the injector 11B is illustrated, the injectors 11A, 11C, and 11D have the same structure as the injector 11B. The injector 11 </ b> B is provided through a cylinder head 101 that covers a cylinder block (not shown), and a distal end portion 111 faces the combustion chamber 102. The injector 11B has a general solenoid type configuration, and a needle is disposed in a nozzle into which fuel is introduced, and a needle that sits behind the needle is seated on a seat formed in the valve body, and the needle And a solenoid for separating the head. By energizing the solenoid, the armature integrated with the needle is sucked and the needle is separated, and the fuel is injected from the injection hole 112 formed at the tip of the nozzle portion to form an air-fuel mixture with the intake air.
[0022]
The air-fuel mixture is ignited by energizing ignition coils 12A, 12B, 12C, and 12D provided in a one-to-one correspondence for each cylinder.
[0023]
The engine body 1 is also provided with a fuel pressure control actuator 13, a valve timing actuator 14, and a swirl actuator 15. The fuel pressure control actuator 13 is constituted by a pump configured to be capable of adjusting the discharge amount by duty control, and pressurizes and supplies the fuel in the fuel tank to the injectors 11A to 11D. The valve timing actuator 14 is attached to the valve operating mechanism of the intake / exhaust valve, and can adjust the opening / closing valve timing of the intake / exhaust valve. The swirl actuator 15 drives a butterfly valve provided in the intake passage, and generates a swirling flow in a plane direction perpendicular to the cylinder axis by unbalancing the amount of air flowing into the combustion chamber 102 in the intake valve. The swirling flow strength is adjusted according to the angle of the butterfly valve.
[0024]
Further, the engine body 1 is provided with an exhaust gas recirculation device, and is provided with an EGR valve 16 for adjusting an exhaust gas recirculation amount (hereinafter referred to as an EGR amount).
[0025]
The cooling system for cooling the cylinder block and the cylinder head 101 is configured such that cooling water circulates with the power of the water pump, and includes a cooling water relief control valve 17 serving as cooling water temperature adjusting means. The cooling water relief control valve 17 has the same function as a conventional thermostat for switching whether or not to bypass the radiator 18, but includes an electromagnetic solenoid and is switched by control of the ECU 2 described later.
[0026]
Moreover, the cooling water directly cools the injectors 11A to 11D. That is, in FIG. 2 described above, the attachment hole 103 for attaching the injector 11B has a lower portion having a larger diameter than the injector 11B, and an annular space 1001 is formed on the outer periphery of the injector 11B. The annular space 1001 is liquid-tightly closed by the seal members 104 and 105 at two places, upper and lower. The annular space 1001 communicates with a cooling water passage 1002 for cooling the cylinder head 101 formed inside the cylinder head 101, and cooling water is introduced. The injector tip 111 exposed to the combustion gas in the combustion chamber 102 is directly cooled by the cooling water.
[0027]
The engine body 1 is also provided with a basic configuration of the internal combustion engine, for example, a throttle valve that opens according to the amount of depression of the accelerator pedal.
[0028]
The ECU 2 that performs fuel injection control, intake control, ignition control, and the like of the engine body 1 drives a general microcomputer 21 including a CPU 211, a RAM 212, a ROM 213, an input / output circuit 214, and the like, and the injectors 11A to 11D. The microcomputer 21 is used for controlling the injectors 11A to 11D and the like based on the operation state known from the detection signals of the sensors 301, 302, 303, 304, 305, 306, 307, 308, and 309. The driving circuit 22 and the like output control signals to the injectors 11A to 11D and the like based on the operating parameters. Only the driving circuit 22 for operating the cooling water relief control valve 17 is shown.
[0029]
As the sensors 301 to 309, an engine speed sensor 301 which is a time interval detecting means for detecting the engine speed, a crank angle sensor 302 for detecting a crank angle, a coolant temperature sensor 303 for detecting a coolant temperature, an accelerator opening An accelerator opening sensor 304 for detecting the degree of intake, an intake air temperature sensor 305 for detecting the intake air temperature, an intake air amount sensor 306 for detecting the intake air amount, an intake pipe pressure sensor 307 for detecting the intake pipe pressure, and an O in exhaust gas₂Exhaust gas to detect concentration₂A concentration sensor 308 and a fuel pressure sensor 309 for detecting the fuel pressure of the fuel supplied to the injectors 11A to 11D are provided.
[0030]
In addition, signals are input to the microcomputer 21 from general sensors for controlling the internal combustion engine.
[0031]
Of the drive circuits for driving the injectors 11A to 11D and the like, the drive circuit 22 for the cooling water relief control valve 17 will be described. The drive circuit 22 has a thermostat function for opening the cooling water relief control valve and allowing the cooling water to flow through the radiator when the detected cooling water temperature exceeds a preset temperature threshold value, and is controlled from the microcomputer 21. When the signal is input, the cooling water relief control valve 17 is opened and closed so that the detected cooling water temperature becomes a target temperature set in advance lower than the temperature threshold value. The control signal is issued when the detected engine speed is lower than a preset engine speed threshold value.
[0032]
A control procedure in the microcomputer 21 will be described with reference to FIG. First, the engine speed, the accelerator opening, the intake pipe pressure, the coolant temperature, the injector temperature, and the like are taken in (step S01), and based on these, operating parameters such as fuel injection amount, injection timing, and ignition timing are stored in the ROM 213. The setting is made based on the operation parameter setting map thus set (step S02).
[0033]
Here, the operation parameter setting maps for the valve timing, the swirl ratio, the EGR amount, the fuel pressure, and the ignition timing are maps each having the engine speed and the coolant temperature as inputs.
[0034]
As for the valve timing, for example, the exhaust valve is given a value on the advance side as the engine speed is lower and the coolant temperature is higher. This acts in a direction to shorten the time during which the combustion chamber holds the high-temperature combustion gas, and serves to lower the combustion chamber temperature.
[0035]
The swirl ratio is given a larger value as the engine speed is higher and the coolant temperature is lower. This acts in a direction in which the gas flow in the cylinder is strengthened to make combustion quicker, and thus in a direction in which the temperature in the combustion chamber rises.
[0036]
The EGR amount is given a larger value as the engine speed is lower and the coolant temperature is higher. This increases the ratio of exhaust gas taken into the combustion chamber and increases the specific heat ratio, and thus acts in the direction of decreasing the temperature in the combustion chamber.
[0037]
The higher the engine speed and the lower the injector temperature, the higher the fuel pressure is given. This acts in the direction of atomizing the fuel spray injected from the injector to make the combustion rapid, and thus in the direction of increasing the temperature in the combustion chamber.
[0038]
The ignition timing is given a retarded value as the engine speed is lower and the coolant temperature is higher. This shortens the time during which the hot gas stays in the combustion chamber, and thus acts to suppress the temperature in the combustion chamber.
[0039]
In step S03, a control signal is output to the drive circuit 22 and the like according to the operation parameters set in step S02, and the operation is performed at a predetermined timing. Thereby, it will be in the operation state according to the said operation parameter. That is, if the engine speed is low and the injector tip temperature is high, each operation parameter is corrected so that the combustion becomes slow or the combustion chamber temperature decreases.
[0040]
Thereby, there exists the following effect | action. FIG. 4 illustrates the knowledge obtained as a result of repeated experiments conducted by the inventors on deposits adhering to the injector nozzle hole, from the previous fuel injection to the current fuel injection in the same injector. This is the relationship between the time interval (hereinafter referred to as the injection interval) and the fuel flow rate reduction rate. In the experiment, a test injector was placed in the heating chamber, the same thermal environment as that of the engine in operation appeared in the heating chamber, and the flow rate of fuel injected from the injector was measured in this state. .
[0041]
As can be seen from the figure, the flow rate decrease rate increases as the injection interval increases. This is because part of the fuel remaining on the inner surface of the nozzle hole after the vaporization is vaporized, so that the longer the injection interval, the more the degree of adhesion of the liquid phase fuel to the inner surface of the nozzle hole proceeds. That is, if the injection interval is short, the remaining fuel is easily washed away together with the injected fuel by the fuel flow that flows through the nozzle hole at the time of the next fuel injection, whereas if the injection interval is long, the degree of adhesion progresses. Even if the fuel flow flows through the nozzle hole at the time of fuel injection, part or all of the remaining fuel remains adhered, and deposit accumulation increases. Thereby, the cross-sectional area of the injection hole is reduced, and the injection flow rate is reduced.
[0042]
  Low engine speedTherefore, if the injection interval is long, the operating state shifts in a direction in which the combustion becomes slow, and an increase in deposit accumulation is suppressed.
  On the other hand, if the engine speed is high and the injection interval is short, the fuel is washed away in the next injection before the fuel sticks. Therefore, even if the adhering fuel is exposed to a high temperature, deposit accumulation does not increase. Therefore, if the engine speed is high, the driving state shifts in a direction in which the combustion becomes rapid, so that it is possible to realize an efficient driving, that is, a fuel efficient driving.
[0043]
Further, when the engine speed is low and therefore the injection interval is long and the increase in deposits should be watched, the drive circuit 22 controls the coolant relief control valve 17 so that the coolant temperature becomes the target temperature. Thus, rapid combustion with good fuel efficiency is performed in a state where the injector tip 111 is sufficiently cooled.
[0044]
  And in the state where the cooling water temperature rises above the target temperature and the cooling capacity of the injector tip is insufficient,Detected by operating state detection meansDepending on the parameters indicating the high probability of deposit increase (engine speed and coolant temperature that define the injection interval), slow combustion such as a decrease in fuel pressure to avoid an increase in depositSet operation parametersMeasures are taken.
[0045]
If the engine speed is high and the injection interval is short, the control for adjusting the cooling water temperature to the low target temperature is not performed, and it is possible to avoid the engine from being cooled due to a decrease in the cooling water temperature.
[0046]
  in this way,simplyRather than controlling the injector tip temperature to be low, the injector tip temperature is prevented from excessively rising only when it is really necessary, so that high fuel efficiency can be achieved.
[0047]
  AlsoThe present invention can also be applied to an internal combustion engine that can select an injection mode in which fuel is injected twice in the compression stroke. In this case, by performing the two-time injection, the injection interval is shorter than that in the case of the single-injection mode at the same engine speed. For example, based on a correction that increases the detected engine speed. The operation parameter setting map is read so that a value that causes relatively rapid combustion is given.
[0048]
  This embodimentBasic configurationIn the above, a new sensor is provided as a driving state detecting means for detecting the driving state, and the operating parameter is set under the condition that the new sensor is added in the microcomputer. The basic configuration isBasic configurationAnd the parts that operate substantially the sameBasic configurationThe same numbers are used for explanation.
[0049]
In FIG. 5 which shows the attachment state of the injector 1B, the injector 11B is provided with an injector temperature sensor 310 which is a temperature detecting means. Injector temperature sensor 310 is formed of a thermocouple and is provided along the outer surface of injector 11B. Then, the warm contact point is close to the opening position of the injection hole 112, and the temperature at the injection hole 112 position of the injector 11B can be substantially detected. The injector temperature sensor 310 is provided only in one of the injectors 11A to 11D. The cylinder in which the injector temperature sensor 310 is provided is a cylinder in which the combustion chamber is most likely to be heated, and varies depending on the structure and layout of the internal combustion engine, individual differences, and the like.
[0050]
  Similarly to the first embodiment, the microcomputer 21 sets operation parameters based on the detection signals of the sensors 301 to 309. AndInjector tip temperature detecting means 310The injector tip temperature detected by the above is compared with a preset temperature threshold, and if the temperature threshold is exceeded, the valve timing, swirl ratio, EGR amount, fuel pressure, ignition timing among the set operating parameters Make corrections. Correction is performed by adding a correction value to the operating parameter or multiplying by a coefficient, and the valve timing is adjusted so that the exhaust valve is advanced so that the operating parameter shifts in a direction in which the combustion chamber temperature is suppressed. The correction value is given so that the ignition timing is advanced so that the fuel pressure decreases so that the EGR amount increases so that the swirl ratio becomes a large value. The correction value is stored in the ROM 213 similarly to the operation parameter setting map.
[0051]
And the actuators 13-16 etc. act | operate with this operation parameter.
[0052]
According to the present embodiment, for example, even if the injector tip temperature tends to appear on the high temperature side due to, for example, the secular change of the engine, the difference in the fuel property supplied, the load of the internal combustion engine, or the operation time, this will cause the injector tip temperature to change. By detecting, the driving parameter is reflected in the driving parameter so that the driving parameter becomes a slow combustion. Therefore, it is possible to further suppress the deposit while realizing the driving with good fuel efficiency.
[0053]
Further, the temperature detecting means for detecting the injector tip temperature is not limited to the thermocouple, and a thermistor may be used. In addition, it is not always necessary to provide the valve body at the tip end face of the injector, and a thin film thermocouple or the like can be attached to a gasket provided in close contact between the injector and the cylinder head. In this case, the temperature detection position is slightly separated from the injection hole formation position of the injector, but since there is a high correlation between the detection temperature and the temperature of the injection hole formation position of the injector, by converting both, practically, This is equivalent to providing it on the tip of the valve body of the injector.
[0054]
In addition, as a method of indirectly detecting the injector nozzle position temperature in this way, the solenoid of the injector is regarded as one resistor, and a Wheatstone bridge circuit including four resistors including the solenoid is configured, and adjacent to each other. The resistance value of the solenoid is obtained from the voltage between the two opposing terminals by applying a voltage from the two opposing terminals among the terminals to which the resistor is connected, and this is converted into resistance / temperature stored in the ROM of the ECU It is also possible to convert to temperature using a map.
[0055]
Also, the exhaust O under the same idling conditions₂Detect how much the concentration has changed from the reference value such as the initial value, and determine the insufficient amount of the injection flow rate from the degree of leaning, and if this increases, the deposit begins to adhere, that is, the injector It is also possible to shift the operating parameters in a direction in which the combustion becomes slow when it is determined that the tendency to increase the temperature at the tip is progressing. This case is also substantially equivalent to detecting the injector tip temperature and setting the operating parameters.
[0056]
  In addition, the injector temperature sensor is installed in the cylinder with the strongest tendency to increase the temperature, and the operation parameters of all cylinders are set based on the detected temperature and a single operation parameter setting map. It is good to prepare for each cylinder.
[0057]
Further, whether or not the operation parameter is corrected is switched depending on whether the injector tip temperature is higher or lower than the temperature threshold value, but it is also possible to give correction values in multiple steps or continuously according to the value of the injector tip temperature. . In this case, the operation parameter setting map may be a map that receives the engine speed, the coolant temperature, and the injector tip temperature as inputs.
[0058]
  In addition,The embodimentHowever, the operation parameter setting map does not have to change with the engine speed and the coolant temperature for all items of valve timing, swirl ratio, EGR amount, fuel pressure, and ignition timing, and the required deposit suppression effect One or more of the items whose contents change depending on the engine speed and the coolant temperature depending on the above may be selected.
[0059]
In addition, the valve timing, swirl ratio, EGR amount, fuel pressure, and ignition timing are desirable because the combustion chamber temperature can be changed depending on the amount, advance or retard, regardless of the values of other operating parameters. The operating parameters that change the temperature in the combustion chamber depending on the value are not only these.For example, in the injection timing, depending on the set timing, the propagating flame becomes the strongest in the vicinity of the injector tip, and in this case, the combustion chamber is in the vicinity of the injector. Since the temperature becomes high, the injection timing is set to avoid this.
[0060]
Further, depending on the required deposit suppressing effect, it is not necessary to configure the cooling water temperature to be lowered when the engine speed is low, and a conventional thermostat valve may control the cooling system.
[0062]
The present invention can also be applied to an internal combustion engine in which an injector is provided in an intake passage immediately upstream of an intake valve.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an internal combustion engine of the present invention.
FIG. 2 is a cross-sectional view of a part of the internal combustion engine showing a state where an injector is attached.
FIG. 3 is a flowchart showing control contents of a computer constituting the internal combustion engine.
FIG. 4 is a graph illustrating the operation of the internal combustion engine.
FIG. 5 is a cross-sectional view of a part of the internal combustion engine showing a state of attachment of an injector of another internal combustion engine of the present invention.
[Explanation of symbols]
1 Engine body
11A, 11B, 11C, 11D injector
111 Tip
112 nozzle hole
102 Combustion chamber
17 Cooling water relief control valve (cooling water temperature adjusting means)
2 ECU
21 Microcomputer (Operation parameter setting means)
22 Drive circuit (control means)
301 engine speed sensor (operating state detection means, time interval detection means)
302, 304, 305, 306, 307, 308, 309 Sensors (operating state detection means)
303 Cooling water temperature sensor (operating state detection means, cooling water temperature detection means)
310 Injector temperature sensor (operating state detection means, injector temperature detection means)

Claims (3)

An operating state detecting means for detecting the operating state of the engine body is detected in the engine body that generates power by burning the fuel spray injected from the nozzle hole formed at the tip of the injector in the combustion chamber. In an internal combustion engine provided with operation parameter setting means for setting an operation parameter for controlling the engine body based on the operation state, a plurality of injectors are provided so as to correspond to a plurality of cylinders on a one-to-one basis .
As the operating state detection means, a time interval detection means for detecting a time interval from the injection of the injector to the next injection of the injector, and a cooling water temperature detection means for detecting the temperature of the cooling water for cooling the engine body, And a temperature detecting means for substantially detecting the temperature of the tip of the injector having the highest temperature tendency among the plurality of injectors,
The operation parameter setting means has a higher probability of deposit increase as the detected time interval is longer, the detected tip temperature of the injector is higher, and the detected coolant temperature is higher. judge, the internal combustion engine in which the operating parameters, the value becomes lower the temperature of the combustion chamber, characterized in that set to be slow combustion suppressing an increase in deposits. The internal combustion engine according to claim 1, wherein the engine body is provided with a cooling water temperature adjusting means for adjusting a temperature of cooling water for cooling the engine body,
And a control means for controlling the cooling water temperature adjusting means.
When the detected time interval is longer than a preset time threshold, the control means is set so that the cooling water temperature becomes a preset target temperature and slow combustion is suppressed in which an increase in deposit is suppressed. internal combustion engine was. 3. The internal combustion engine according to claim 1, wherein the engine body is an in-cylinder injection type in which a tip portion of the injector projects into the combustion chamber and fuel is directly injected into the combustion chamber from the injection hole .

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