JPH10317936A - Internal combustion engine provided with means of suppressing oil dilution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means of reliably suppressing engine oil dilution by fuel for use in a cylinder-direct fuel injection type internal combustion engine. SOLUTION: A dilution detector means detects the dilution of engine oil by fuel including gasoline on the basis of the concentration of hydrocarbon in blowby gas, the pressure, sonic velocity and infrared ray absorptance in the crankcase, and the viscosity, pH value, electric resistance and capacitance of engine oil-among others. If the detection value exceeds predetermined allowable dilution, a dilution suppressor means is started up to temporarily vary the fuel injection timing, injection pressure, cooling water temperature, oil temperature, ignition timing, and intake valve closing timing among others and thus to lower the dilution. That control prevents the sliding parts of the engine from seizing up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an internal combustion engine in which fuel is directly injected into a cylinder, such as a direct fuel injection type gasoline engine, and further suppresses dilution of engine oil by the fuel. The invention relates to an internal combustion engine comprising the means.

[0002]

2. Description of the Related Art As shown in FIG.
So-called "intake-pipe-injection engine" 1 in which fuel such as gasoline supplied from a fuel injection pump 102 is pressurized by a fuel injection pump 102 and injected from a fuel injection valve 103 into an intake pipe 104.
05 has been around for quite some time. On the other hand, in recent years, as shown in FIG. 23, an internal combustion engine in which fuel such as gasoline pressurized to a relatively high pressure by a fuel injection pump 106 is directly injected into a cylinder 108 by a fuel injection valve 107, So-called "in-cylinder direct fuel injection gasoline engine"
The mass production of the 109 has begun, but it is believed that this type of internal combustion engine will become more widespread in the future.

[0003] Although a direct injection gasoline engine (in short, a direct injection gasoline engine) has many features, the injected fuel spray tends to adhere to the surface of the cylinder liner 110 as compared with an intake pipe injection engine. for,
Since fuel such as gasoline dissolves in the engine oil forming an oil film on the cylinder liner 110, the amount of unburned fuel flowing out to the crankcase 111 with the engine oil increases, thereby diluting the engine oil. Thus, a new problem, such as a decrease in viscosity and lubrication performance, which has not been seen before, has come to the surface.

The direct injection gasoline engine 109 sets the fuel injection timing in the middle stage of the intake stroke to improve the charging efficiency in order to improve the engine performance under a high load. This condition will be described later. For this reason, the fuel spray adheres more to the inner surface of the cylinder liner 110, and the engine oil dilution (oil dilution) proceeds. In general, when the engine oil is diluted with fuel, the lubricating performance is reduced due to the decrease in the viscosity of the oil, which may cause seizure on the sliding surface between the cylinder liner 110 and the piston 112. In the case of an injection gasoline engine, there is an urgent need to develop a means for suppressing oil dilution.

[0005]

SUMMARY OF THE INVENTION The present invention addresses the above-mentioned problems in the prior art and provides means for reliably suppressing the dilution of engine oil with fuel, and starting or stopping the operation of the suppression means. It is an object of the present invention to provide an improved in-cylinder direct fuel injection type internal combustion engine provided with an oil dilution degree determining means for accurately determining the timing of the operation.

[0006]

According to the present invention, there is provided, as a means for solving the above-mentioned problems, an internal combustion engine provided with means for suppressing oil dilution as set forth in the claims. I do.

According to the first aspect of the present invention, in an internal combustion engine for directly injecting fuel into a cylinder, a dilution degree detecting means and a dilution degree suppressing means are provided. The dilution degree detecting means detects when the dilution degree of the engine oil by the fuel increases. The dilution degree suppression means is activated when the dilution degree detection means detects an increase in the dilution degree of the engine oil, and prevents the dilution from proceeding further. Therefore, if the dilution degree is prevented from increasing by the dilution degree suppression means, the dilution degree gradually decreases after the engine is warmed up, so that the operation of the dilution degree suppression means can be stopped. . In this manner, the dilution degree of the engine oil can be suppressed to a low level, so that it is possible to avoid a trouble that the sliding portion of the engine is seized due to a decrease in the viscosity of the engine oil.

According to the second aspect of the present invention, since some sort of separating means for positively separating the fuel from the engine oil diluted by the fuel is provided as the dilution degree suppressing means, the dilution degree suppressing means is provided. When activated, not only wait for the dilution to drop naturally,
Actively separate fuel from engine oil to reduce dilution. Therefore, since the time during which the dilution degree suppressing means operates is relatively short, the operation of the dilution degree suppressing means can be stopped, and the engine can be quickly returned to the optimum operating state.

According to the third aspect of the present invention, since the dilution degree detecting means numerically measures the dilution degree, the measured dilution degree is compared with the allowable dilution degree, and the dilution degree measurement value is calculated. Can be controlled completely automatically and accurately so that the dilution degree suppression means is automatically activated when the value exceeds the allowable dilution degree.

According to the fourth aspect of the present invention, when the dilution degree detecting means activates the dilution degree suppressing means, the dilution degree suppressing means sets the fuel injection timing, injection pressure, engine cooling water temperature. By temporarily changing at least one of the set values of the engine oil temperature, the engine ignition timing, and the intake valve closing timing, it is possible to reliably prevent the degree of dilution from increasing.

According to the means described in claim 7, the dilution degree detecting means determines the concentration of the hydrocarbon contained in the blow-by gas, the pressure in the crankcase, the sound velocity, the infrared absorption rate, and the viscosity of the engine oil. , PH value, electrical resistance, or at least one of the capacitance can be measured to output an accurate dilution measurement, whereby when the dilution measurement exceeds the allowable dilution, It is possible to prevent the progress of dilution by properly activating the dilution suppression means.

According to the means described in claim 8, when the increase of the dilution degree cannot be stopped by the activation of the suppressing means, the driver or the like can recognize the state by operating the warning means. Therefore, it is possible to take countermeasures such as changing the oil, and to avoid a worst case such as engine damage.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The details of the contents of the first embodiment will be separately described for each of a plurality of means constituting the first embodiment, but first, the entire first embodiment will be described.
This operation will be generally described with reference to the flowchart of FIG.

When the engine is started, control of the suppression means is also started in step 201, and
In 02, an oil dilution degree indicating the degree of oil dilution is detected (measured) by a method described later. And
Proceeding to step 203 for determining the oil dilution degree, the measured dilution degree is compared with a predetermined allowable dilution degree to determine whether it is higher than the allowable dilution degree. If the measured dilution degree is equal to or less than the allowable dilution degree, the flow returns to step 202 to repeat the detection and determination of the measured dilution degree, but if the measured dilution degree exceeds the allowable dilution degree, the processing proceeds to step 204 and the fuel Is changed to a time when the degree of dilution becomes low as described later. This suppresses the progress of oil dilution and waits for fuel (gasoline) to separate from the oil. In some cases,
During this time, means for positively promoting the separation can be activated.

After the fuel injection timing is changed, the measured value of the dilution is detected in step 205, and it is determined in step 206 whether the measured value of the dilution is lower than the value of the allowable dilution. . As long as the measured value of the dilution degree does not become smaller than the allowable dilution degree, the process returns to step 205 and repeats the detection of the measurement value of the dilution degree and the determination of step 206. In the meantime, the measurement value of the dilution degree becomes a predetermined warning value in step 208. It is determined whether not reached. If the warning value has been exceeded, the routine proceeds to step 209, in which a warning means such as turning on a warning lamp is operated to inform the driver or the like of the situation and take measures such as oil change. If it is determined in step 206 that the measured value of dilution becomes smaller than the allowable dilution, the process proceeds to step 207 to return the fuel injection timing to the optimal timing, and then returns to step 202 again to measure the dilution. Repeat the detection and judgment of the value.

Hereinafter, a specific method of determining the oil dilution degree which can be used for the oil dilution suppression means of the first embodiment and the first embodiment which is executed when the measured dilution degree is higher than the allowable dilution degree will be described. The control method of the fuel injection timing as the oil dilution suppression method of the embodiment will be described in detail. As a method for determining the degree of oil dilution, for example, various methods as shown in FIGS. 2, 3, 4 and the like can be appropriately selected and adopted according to the target.

In these figures, reference numeral 1 denotes an in-cylinder direct fuel injection gasoline engine provided with an oil dilution suppressing means according to an embodiment of the present invention, and may be referred to as a direct injection gasoline engine 1 for short. . 2 denotes a cylinder block, 2a denotes its cylinder liner, 2b denotes a combustion chamber, and 2c denotes a water jacket through which cooling water flows. Also, 3
Is a piston inserted into the cylinder liner 2a, 4 is an intake pipe, 5 is an exhaust pipe, 6 is an intake valve, 7 is an exhaust valve, 8 is a spark plug, 9 is a fuel (gasoline) tank, 10 is a high pressure fuel. A fuel injection pump 11 for pressurizing, a fuel injection valve 11 attached to the combustion chamber 2b and capable of directly injecting fuel into a cylinder, 12 a crankcase, 13 an oil pan, 1
Reference numeral 4 denotes the engine oil stored therein.

First, the oil dilution degree determination method shown in FIG. 2 measures the hydrocarbon concentration (HC concentration) contained in the blow-by gas 15 in the gas phase in the crankcase 12 to determine the oil dilution. For determining the degree of dilution, the HC concentration detecting means 16 is connected to the crankcase 12 for that purpose. The gasoline injected from the fuel injection valve 11 and dissolved in the oil film of the engine oil formed on the surface of the cylinder liner 2 a flows into the crankcase 12 together with the oil film being scraped off by the piston ring of the piston 3. , Mixed into the liquid phase of the engine oil 14. Since gasoline has a lower distillation temperature than engine oil and evaporates faster, the HC concentration of the blow-by gas 15 which is a gaseous phase in the crankcase 12 increases due to evaporation of the gasoline. It will be an indication of Therefore, in the method of determining the degree of oil dilution shown in FIG. 2, the blow-by gas 1 is detected by the HC concentration detecting means 16 attached to the gas phase of the crankcase 12.
5 is measured to detect the degree of dilution of the engine oil 14.

As described above, gasoline flowing out of the cylinder into the crankcase 12 together with the engine oil has a lower distillation temperature than the engine oil and evaporates faster.
In addition to increasing the HC concentration of the blow-by gas 15, the pressure (steam pressure) is also increased. Accordingly, the pressure of the gas phase portion in the crankcase 12 is a measure of the dilution degree of the engine oil 14 which is the liquid phase portion. Therefore, according to the oil dilution degree determination method shown in FIG. The pressure is measured by a pressure detecting means 17 attached to the portion, and the degree of dilution of the engine oil 14 is detected. In some cases, the pressure detecting means 17 may be attached to the liquid portion (the engine oil 14 itself) to measure the pressure.

Further, when gasoline is mixed and diluted with the engine oil 14 in the crankcase 12, the viscosity of the engine oil 14 is reduced, which causes a decrease in lubrication performance. Is also a reliable guide for detecting the degree of dilution of the engine oil 14. Therefore, in the oil dilution degree determination method shown in FIG. 4, the viscosity measurement unit 18 is attached to the liquid phase portion of the crankcase 12 to accurately measure the viscosity. The value is calculated. Note that the measured value of the viscosity can be used as it is as the measured value of the dilution degree. However, since the dilution degree becomes higher as the viscosity of the engine oil becomes lower, the steps 203 and 206 in the flowchart shown in FIG. In the determination, it goes without saying that the inequality sign between the measured value and the set allowable value is reversed.

Referring now to FIG. 5, the relationship between control of the injection timing of a direct injection gasoline engine and engine performance will be described. In a conventional intake pipe injection type engine, it is possible to perform fuel injection at any time during the entire stroke from the intake stroke to the exhaust stroke, and there is no fuel injection timing that particularly increases the degree of oil dilution. On the other hand, a direct injection gasoline engine injects fuel (gasoline) directly into a cylinder. Therefore, if fuel is injected during an expansion stroke or an exhaust stroke, the injected fuel is discharged into the atmosphere together with the exhaust gas. Will be released to Therefore, in a direct injection gasoline engine, the time at which fuel injection is possible is greatly limited, and is limited to only the intake stroke or the compression stroke.

Since lean combustion is performed by compression stroke injection at light load or medium load, the injection timing is controlled so that fuel gathers around the spark plug 8. In order to collect a mixture having a good ignitability around the spark plug 8, a time interval from fuel injection to ignition becomes important.
If the time interval is long, the fuel diffuses and the concentration of the air-fuel mixture around the spark plug 8 decreases. Conversely, if the time interval is short, the fuel does not reach the vicinity of the spark plug 8, so that any combustion occurs. The condition worsens.

At the time of high load, the air-fuel mixture in the cylinder can be homogenized by performing the intake stroke injection shown as the range of the arrow in FIG. Even in the case of a direct injection gasoline engine, it is possible to perform injection in the whole range during the intake stroke, but at high load, the output is emphasized, and therefore, as shown in FIG. The crank angle (CA) in the intake stroke
Is controlled from around 90 °. At this injection timing, the air taken into the cylinder is cooled by evaporation of the fuel (gasoline), so that the charging efficiency can be improved and the output can be increased.

However, in this case, since the injection is performed after the piston 3 is considerably lowered as shown in FIG.
The injected gasoline mixes into the oil film of the engine oil formed on the surface of the cylinder liner 2a and is easily dissolved. As a result, the gasoline dissolved in the engine oil flows out into the crankcase in a later process to increase the dilution degree. Invite.

The change of the dilution degree of the direct injection gasoline engine is shown by a solid line in FIG. Also, for comparison, the change in the dilution degree in the case of the conventional intake pipe injection type engine is indicated by a broken line. As described above, in the direct injection gasoline engine 1, the injection timing from the middle to late stages of the intake stroke advances the dilution of oil. On the other hand, in the case of the initial injection also in the compression stroke injection and the intake stroke, as shown in FIG. 8, the fuel is injected into the cavity 3 a formed as a depression on the top surface of the piston 3, The amount of fuel spray adhering to the cylinder liner 2a is extremely small, and substantially no oil dilution occurs.

If it is determined in the above-described determination of the oil dilution degree that the measured value of the dilution degree is higher than the allowable dilution degree, as shown in FIG. The control at the injection timing after the crank angle (CA) around 90 ° is stopped, and the dilution of the oil is suppressed by switching the injection timing to the initial stage of the intake stroke in which the degree of dilution is low or to the compression stroke. Since oil dilution does not proceed during the period in which the injection timing is controlled in this manner, gasoline evaporates from the diluted engine oil after warm-up, and the degree of dilution gradually decreases. In a normal vehicle, the cooling water temperature is controlled to be 80 ° C.
By increasing the set temperature during the period in which the injection timing is controlled, it is possible to promote the vaporization of gasoline in the engine oil and to positively decrease the degree of dilution. If the degree of dilution decreases in this way, in the case of the first embodiment, the control is returned to the normal injection timing control.

Next, a second embodiment of the present invention will be described. In the first embodiment, the injection timing of a direct injection gasoline engine is controlled to suppress the progress of oil dilution and to promote the separation of gasoline from diluted engine oil. Instead of controlling the injection timing, the atomization of the fuel spray is promoted, and the penetration of the fuel spray (Penetra
, the fuel spray is prevented from adhering to the cylinder liner 2a, and the dilution of oil by the fuel is suppressed.

While the pressure (fuel pressure) of fuel injected in a conventional intake pipe injection type engine is usually 2-3 kgf / cm ² , the fuel pressure of a direct injection gasoline engine is, for example, 50-120 kgf / cm ^2. Thus, a direct injection gasoline engine injects fuel at a pressure that is 30 to 40 times higher than that of an intake pipe injection type engine. Here, as shown in FIG. 9, as the pressure of the injected fuel is increased, the atomization of the fuel spray is promoted, and the particle size of the spray is reduced. However, the high pressure injection increases the penetration, which causes fuel to adhere to the cylinder liner.

There are two methods for lowering the penetration: a method for lowering the fuel pressure and a method for further increasing the fuel pressure. However, when the fuel pressure is lowered, the atomization of the fuel becomes worse, so that an appropriate mixture is formed. On the other hand, when the fuel pressure is increased, atomization of the fuel is promoted and the mass of each fuel particle is reduced, so that the penetration can be reduced. Therefore, in the second embodiment of the present invention, when the measured value of the dilution degree increases, the fuel pressure is increased to promote the atomization of the fuel spray, thereby reducing the penetration of the fuel spray and suppressing the oil dilution. I do.

As another method for promoting the atomization of the fuel spray, a fuel injection valve 11 is supplied from a fuel tank 9 and pressurized to a high pressure by a fuel injection pump 10 as shown in a modification shown in FIG. The fuel before injection (gasoline) sent to the fuel pipe is supplied to a fuel heating device 19 provided in the middle of the fuel pipe.
It is also possible to reduce the penetration of the fuel spray by promoting the vaporization after injection by heating. Needless to say, the fuel heating device 19 is energized and heats the fuel only when the measured dilution value is high.

As another modified example of the second embodiment,
As shown in FIG. 11, two fuel pipes from the fuel tank 9 to the fuel injection pump 10 are provided in parallel, and the first valve 20 is provided in the middle of one pipe. The other pipe allows the fuel to be heated by passing through the water jacket 2c of the engine body, and a second valve 21 is provided on the way. When it is determined that the measured dilution value is high, the fuel is heated in the water jacket 2c and then supplied to the fuel injection valve 11 by closing the first valve 20 and opening the second valve 21. This promotes atomization of the fuel spray, reduces the penetration of the fuel spray, and suppresses oil dilution.

As a method for detecting the degree of oil dilution in the present invention, in addition to the method described above, various methods utilizing the following various physical or chemical phenomena may be employed depending on the object and conditions. As a result, the measured value of the dilution degree of the engine oil 14 can be obtained.

As shown in FIG. 12, it is recognized that when the dilution degree of the engine oil increases due to the dissolution of the fuel (gasoline), the chemical property changes such that the PH value of the engine oil increases correspondingly. Can be Therefore, if the value of the PH of the engine oil 14 at that time is measured by a means known per se, a target dilution degree measurement value can be calculated. Since the PH value changes in proportion to the degree of dilution, in this case, the measured value of PH may be used directly as the measured value of dilution.

Similarly, as shown in FIG. 13, when the degree of dilution of the engine oil with the fuel increases, the two electrodes supported so as to maintain a fixed interval with the engine oil interposed therebetween correspondingly. It is recognized that a change in physical properties occurs, such as a decrease in the value of the electrical resistance. Therefore, the crankcase 1 is known by itself.
By measuring the value of the electric resistance between the electrodes fixedly supported in the second engine oil at that time, the target dilution degree measured value can be easily calculated.

Similarly, as shown in FIG. 14, when the dilution degree of the engine oil with the fuel increases, the physical property changes such that the infrared absorption of the blow-by gas in the crankcase 12 increases correspondingly. It is recognized that. Therefore, if the value of the infrared absorptivity of the blow-by gas is calculated by a method known per se, such as measuring the infrared transmittance of the blow-by gas in the crankcase 12 at that time, the desired dilution can be obtained. You can know the measured value.

Similarly, as shown in FIG. 15, when the dilution degree of the engine oil with the fuel increases, it is recognized that a change in the physical property that the sound speed in the crankcase 12 decreases correspondingly occurs. Therefore, if the value of the sound velocity in the crankcase 12 at that time is measured by a means known per se, a target dilution degree measurement value can be calculated.

Similarly, as shown in FIG. 16, when the degree of dilution of the engine oil with the fuel increases, the distance between the two electrode plates supported at a fixed interval with the engine oil interposed therebetween correspondingly increases. It is recognized that a change in the physical property occurs such that the capacitance of the semiconductor device increases. Therefore, if the value of the capacitance between the two electrode plates attached at a constant interval so as to be always immersed in the engine oil is measured in the crankcase 12 by a means known per se, The desired dilution measurement can be obtained.

As described above, the degree of oil dilution changes according to the fuel injection timing and the degree of atomization.
In the embodiments, the oil dilution is suppressed by changing the fuel injection timing, and in the second embodiment, the oil dilution is suppressed by changing the pressure of the injected fuel. Since such factors also change, it is also possible to take advantage of these phenomena and take measures to suppress oil dilution that is triggered when the dilution value exceeds a predetermined allowable dilution.

First, as shown in FIG. 17, when the cooling water temperature of the direct-injection gasoline engine 1 increases, the temperature of the engine oil 14 in the oil pan 13 also increases. Since the amount of gasoline is reduced and gasoline is discharged into the blow-by gas 15, the degree of oil dilution is reduced. Since this is also the relationship between the oil temperature (the temperature of the engine oil 14) and the degree of oil dilution as shown in FIG. 18, the shapes of the diagrams of FIGS. 17 and 18 are similar. Therefore, oil dilution can be suppressed by performing water temperature control or oil temperature control.

Similarly, as shown in FIG. 19, when the ignition timing of the spark plug 8 changes in the advance direction, the oil dilution increases, and when the ignition timing changes in the retard direction, the oil dilution decreases. A phenomenon is observed. This is because the maximum combustion pressure increases when the ignition timing is advanced, and the maximum combustion pressure decreases when the ignition timing is retarded.Therefore, the combustion pressure is reduced by retarding the ignition timing, and the fuel from the cylinder to the crankcase is reduced. Is to reduce the amount of blow-through. Therefore, oil dilution can also be suppressed by retarding the ignition timing.

Further, as shown in FIG. 20, a phenomenon is observed in which the degree of oil dilution also changes due to a change in the closing timing of the intake valve 6. That is, when the valve closing timing changes in the advance direction, the oil dilution degree decreases, and conversely, increases in the retard direction. This phenomenon is caused by the fact that when the closing timing of the intake valve 6 is delayed, the amount of valve overlap increases, exhaust gas blows back from the combustion chamber 2b to the intake pipe 4 increases, and the temperature in the cylinder rises, and adheres to the cylinder. This is because the fuel that has been evaporated evaporates and the amount of adhesion decreases. Therefore, the dilution of the oil can be suppressed by controlling the advance timing of the closing timing of the intake valve 6.

Finally, as shown in FIG. 21, a phenomenon is observed in which the oil dilution degree decreases as the particle size of the spray injected from the fuel injection valve decreases. As means for reducing the particle size, there are a method of changing the nozzle diameter of the injection valve and a method of providing a vibrator at the tip of the injection valve. Is reduced, and the degree of dilution can be reduced by suppressing the penetration, the wet range, or the thickness of the attached fuel.

[Brief description of the drawings]

FIG. 1 is a flowchart showing the operation of the first embodiment of the present invention.

FIG. 2 is a conceptual sectional view illustrating an example of an oil dilution degree determination method.

FIG. 3 is a conceptual cross-sectional view showing another example of the oil dilution degree determination method.

FIG. 4 is a conceptual cross-sectional view showing still another example of the oil dilution degree determination method.

FIG. 5 is a time chart showing a fuel injection timing in a direct injection engine.

FIGS. 6A and 6B are diagrams showing a change in performance with respect to a fuel injection timing of a direct injection engine, wherein FIG. 6A shows a change in charging efficiency and FIG.
Indicates a change in dilution.

FIG. 7 is a sectional view showing a problem of intake stroke injection after a crank angle of 90 °.

FIG. 8 is a cross-sectional view showing an advantage of fuel injection at an early stage of an intake stroke.

FIG. 9 is a diagram illustrating a relationship between a change in the pressure of the injected fuel and a change in the particle size of the spray, for explaining the second embodiment;

FIG. 10 is a sectional view showing a modification of the second embodiment.

FIG. 11 is a sectional view showing another modification of the second embodiment.

FIG. 12 is a diagram showing a phenomenon that can be used for the means for determining the degree of oil dilution.

FIG. 13 is a diagram showing another phenomenon.

FIG. 14 is a diagram showing still another phenomenon.

FIG. 15 is a diagram showing still another phenomenon.

FIG. 16 is a diagram showing still another phenomenon.

FIG. 17 is a diagram showing a phenomenon that can be used for a means for suppressing oil dilution.

FIG. 18 is a diagram showing another phenomenon.

FIG. 19 is a diagram showing still another phenomenon.

FIG. 20 is a diagram showing still another phenomenon.

FIG. 21 is a diagram showing still another phenomenon.

FIG. 22 is a cross-sectional view showing a conventional intake pipe injection engine.

FIG. 23 is a cross-sectional view showing a problem of a conventional direct injection engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... In-cylinder direct fuel injection type gasoline engine (direct injection gasoline engine) 2 ... Cylinder block 2a ... Linder liner 2b ... Combustion chamber 2c ... Water jacket 3 ... Piston 3a ... Cavity 10 ... Fuel injection pump 11 ... Fuel injection valve 12 ... Crank Case 13 Oil pan 14 Engine oil 15 Blow-by gas 16 HC concentration detecting means 17 Pressure detecting means 18 Engine oil viscosity detecting means 19 Fuel heating device 20 First valve 21 Second valve

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 41/04 345 F02D 41/04 345Z F02M 25/08 F02M 25/08 Z F02P 5/15 G01N 27/00 L G01N 27/00 33/30 33/30 F02P 5/15 B (72) Inventor Masao Kano 14 Iwatani, Shimowasumi-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute

Claims (8)

[Claims] 1. An internal combustion engine for directly injecting fuel into a cylinder, comprising: a dilution detecting means for detecting a degree of dilution of engine oil by fuel; and a diluent activated in accordance with the detected degree of dilution. An internal combustion engine having means for suppressing oil dilution, comprising: means for suppressing an increase in the degree of dilution. 2. The internal combustion engine according to claim 1, wherein said suppressing means includes a separating means for positively separating fuel from engine oil diluted by fuel. 3. The dilution degree detecting means for numerically measuring the dilution degree, wherein the dilution degree measurement value measured by the dilution degree detection means is compared with an allowable dilution degree, and the dilution degree measurement value is calculated. 3. The internal combustion engine according to claim 1, wherein the internal combustion engine is configured to activate the suppression means when the allowable dilution degree is exceeded. 4. The operation of the suppression means for preventing an increase in the degree of dilution includes controlling fuel injection timing, controlling fuel injection pressure, controlling engine coolant temperature, controlling engine oil temperature, and controlling engine ignition timing. The control according to any one of claims 1 to 3, wherein the control is performed by at least one of the following control: control of the closing timing of the intake valve of the engine, or control of the spray particle size. Internal combustion engine. 5. The fuel injection system according to claim 1, wherein when the suppression means is activated, the fuel injection timing is changed to one of an initial stage of an intake stroke or a compression stroke. An internal combustion engine according to any of the above. 6. The fuel injection system according to claim 1, wherein when the suppression means is activated, the set value of the injection pressure is changed in a direction in which the fuel injection pressure increases. Or an internal combustion engine. 7. The dilution degree detecting means detects the concentration of hydrocarbon contained in the blow-by gas, the pressure in the crankcase, the speed of sound, the infrared absorption, the viscosity of engine oil,
7. The apparatus according to claim 1, wherein the apparatus is configured to measure at least one of an H value, an electric resistance, and a capacitance and output a dilution measurement value. Internal combustion engine. 8. When the dilution exceeds a predetermined warning value without being able to prevent the increase of the dilution even by the suppression means for preventing the increase of the dilution, it is activated to notify the driver or the like of the condition. The internal combustion engine according to claim 1, further comprising a warning unit.