JP3496514B2 - Internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine mounted on a vehicle such as an automobile.

[0002]

2. Description of the Related Art Some internal combustion engines include, for example, Japanese Patent Laid-Open No. 8-1
As disclosed in Japanese Patent No. 05352, a combustion chamber of an internal combustion engine is configured by a member having a ceramic coating layer containing a lithium element, a titanium coating layer, a magnesium coating layer, a coating layer containing an alkali resistant metal, etc. on the surface. By
It is known to suppress deposit accumulation on the surface of the combustion chamber.

[0003]

However, in the above-mentioned conventional technique, soot generated by the combustion of the air-fuel mixture in the combustion chamber, lubricating oil that has entered the combustion chamber, or unburned fuel is adhering to the inner surface of the combustion chamber. Desorption of the deposits generated by the method depends only on the decrease in the adhesive force of the deposits due to the ceramic coating layer or the like provided on the metal surface of the portion forming the combustion chamber. When a precursor that becomes a nucleus to adhere to is generated, deposit adhesion progresses rapidly, deterioration of combustion due to changes in the volume of the combustion chamber, deterioration of combustion due to mixture ignition before ignition by the spark plug, and deposit There is a possibility that problems such as an increase in exhaust components such as unburned HC generated and discharged from the engine may occur.

Therefore, the present invention is capable of decomposing the organic substances such as lubricating oil and unburned fuel that cause deposits,
An internal combustion engine capable of avoiding the formation of deposits on the surface of a combustion chamber.

[0005]

According to the invention of claim 1, the surface of the component forming the inner surface of the combustion chamber is coated with a titanium oxide layer having a silicon coating as a base,
It is characterized in that the spark plug is made to perform a multi-stage ignition operation of spark ignition for air-fuel mixture ignition in the compression stroke and spark ignition for photocatalytic activity of the titanium oxide layer in the exhaust stroke. There is.

According to a second aspect of the present invention, the ignition operation in the exhaust stroke of the spark plug according to the first aspect is performed by a long-time ignition device for performing a long-time spark discharge. It has a feature.

According to the invention of claim 3, the ignition operation in the exhaust stroke of the spark plug according to claim 1 is performed by a multiple ignition device which repeats a short-time spark discharge in a required ignition period. It is characterized by having done.

The invention of claim 4 is characterized in that the ignition operation in the exhaust stroke of the spark plug according to claim 1 is continued from the expansion stroke.

According to a fifth aspect of the present invention, the ignition operation from the expansion stroke to the exhaust stroke of the spark plug according to the fourth aspect is performed by a multiple ignition device that repeats a short-time spark discharge for a required ignition period. The feature is that it is done.

In the invention of claim 6, claims 1 to 5 are provided.
It is characterized in that the final ignition timing of the spark plug in the exhaust stroke described in (3) is set just before a new air-fuel mixture is formed in the combustion chamber.

According to the invention of claim 7, claims 1 to 6 are provided.
The inner surface of the exhaust port following the combustion chamber described in 1 above is coated with a titanium oxide layer having a silicon film as a base.

The invention of claim 8 is characterized in that the inner surface of the exhaust manifold following the exhaust port of claim 7 is coated with a titanium oxide layer having a silicon film as a base.

[0013]

According to the invention described in claim 1, the light generated by the combustion of the air-fuel mixture in the combustion chamber can obtain the photocatalytic action by the titanium oxide layer provided on the inner surface of the combustion chamber, which causes the deposit. In the exhaust stroke, where organic substances such as lubricating oil and unburned fuel are decomposed and generated on the inner surface of the combustion chamber, or the deposit that is about to be generated can be easily removed, and the combustion light tends to decrease. Also, since the ignition operation of the spark plug is performed and discharge light is generated, the photocatalytic action of the titanium oxide layer is actively performed in this exhaust stroke as well, and it is possible to thoroughly prevent the deposit adhesion on the inner surface of the combustion chamber.

According to the invention of claim 2, claim 1
In addition to the effect of the invention described above, since the ignition operation in the exhaust stroke of the spark plug is made to perform the spark discharge for a long time by the long-time ignition device, the discharge light of the spark plug is maintained for a long time in the exhaust stroke. In particular, when discharge is performed for a long time in the exhaust stroke, the pressure around the spark plug is low in this exhaust stroke and the discharge voltage of the spark plug becomes a function of this cylinder pressure. Since the peak voltage becomes low, a large amount of discharge energy remains after that, and the discharge can be reliably maintained for a long time, and the discharge energy increases as the cylinder pressure decreases due to the progress of the exhaust stroke. Since the light can be intensified, the photocatalytic action of the titanium oxide layer can be surely and more actively performed over the end of the exhaust stroke.

According to the invention of claim 3, claim 1
In addition to the effect of the present invention, since the ignition operation in the exhaust stroke of the spark plug is made to repeatedly perform the short-time spark discharge in the required ignition period by the multiple ignition device, the spark plug of the spark stroke is exhausted in the exhaust stroke. The discharge light is obtained intermittently for the required period, and the discharge energy increases as the cylinder pressure decreases due to the progress of the exhaust stroke, and the discharge light can be intensified, so titanium oxide is used over the end of the exhaust stroke. The photocatalytic action of the layer can be performed reliably and more actively.

According to the invention of claim 4, claim 1
In addition to the effect of the present invention, since the ignition operation in the exhaust stroke of the spark plug is continuously performed from the expansion stroke, the probability of ignition of the air-fuel mixture can be increased and stable combustion can be performed. The light emission necessary for the photocatalysis of the titanium oxide layer can be continuously present from the expansion stroke to the exhaust stroke, and the photocatalysis of the titanium oxide layer can be reliably and actively performed from the expansion stroke to the exhaust stroke. Can be done.

According to the invention of claim 5, claim 4
In addition to the effect of the invention, the ignition operation from the expansion stroke to the exhaust stroke of the spark plug is made to repeat the short-time spark discharge in the required ignition period by the multiple ignition device. Discharge light of the spark plug is obtained intermittently over the exhaust stroke for the required period, and as the cylinder pressure decreases due to the progress from the expansion stroke to the end of the exhaust stroke, the discharge energy increases and discharge light is emitted. Since it is strengthened, the photocatalytic action of the titanium oxide layer can be surely and more actively performed from the expansion stroke to the end of the exhaust stroke.

According to the invention of claim 6, claim 1
In addition to the effects of the inventions of 5 to 5, the ignition final timing of the spark plug in the expansion stroke is set immediately before a new air-fuel mixture is formed in the combustion chamber, so misfire does not occur and engine stability is improved. Can be secured.

According to the invention of claim 7, claim 1
In addition to the effects of the inventions of ~ 6, since the inner surface of the exhaust port continuing to the combustion chamber is coated with a titanium oxide layer having a silicon film as a base, combustion can be performed even in the exhaust port where the late combustion is sustained. The photocatalytic action of the titanium oxide layer is exerted by the generated light, and the effect of suppressing deposit adhesion on the inner surface of the exhaust port due to the adhesion of soot and unburned fuel is obtained.

According to the invention described in claim 8, claim 7
In addition to the effect of the invention, since the inner surface of the exhaust manifold that follows the exhaust port is also coated with a titanium oxide layer having a silicon film as a base, it is generated by combustion even in the exhaust manifold in which the late combustion is sustained. The photocatalytic action of the titanium oxide layer is exhibited by the light, and the effect of suppressing deposit adhesion on the inner surface of the exhaust manifold due to the adhesion of soot and unburned fuel is obtained.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, 1 is a cylinder block, 2
Is a piston, 3 is a cylinder head, and 4 is a combustion chamber formed by these cylinder block 1, piston 2, and cylinder head 3.

As shown in FIG. 2, titanium oxide 2 is formed on the surfaces of the components forming the inner surface of the combustion chamber 4, specifically, the crown surface of the piston 2 and the inner surface of the cylinder head 3.
The silica sol mixed with the fine particles of No. 1 is applied and fired to form the titanium oxide layer 20 with the silicon coating 22 as a base, and the titanium oxide layer is formed by the light generated by the combustion of the air-fuel mixture in the combustion chamber 4. The photocatalytic reaction occurs at 20.

As the titanium oxide 21 used for forming the titanium oxide layer 20, fine particles of anatase type crystal having the highest photoactive ability, more preferably fine particles having a particle diameter of 1 to 20 nm are used.

If the particle size of the titanium oxide 21 particles is smaller than the above range, the titanium oxide 21 particles will agglomerate when agitated with the silica sol, and if the particle size is larger than the above range, the titanium oxide 21 will be dispersed. Photoactivity is extremely reduced.

On the other hand, it is preferable that the filling rate of the silica sol mixed with the fine particles of titanium oxide 21 is 5 to 40%.

In order to obtain the adhesion of the titanium oxide layer 20 to a metal surface such as the crown surface of the piston 2 and the inner surface of the cylinder head 3 and the uniformity and durability of the titanium oxide layer 20 coating, It is necessary that the filling rate is 5% or more, and if the filling rate exceeds 40%, poor photoactivity of the titanium oxide 21 occurs.

Further, the titanium oxide layer 20 is fired at a temperature of 300 ° C. or higher at which the silica sol becomes a resin, but on the high temperature side of 700 ° C. or higher, the crystal of the titanium oxide 21 changes from anatase type to rutile type. It is important to bake at a temperature lower than 700 ° C, and in particular, the titanium oxide layer 2
When 0 is provided on aluminum parts such as the piston 2 and the cylinder head 3 as described above, the upper limit of the firing temperature is 350 ° C to 400 in consideration of the heat resistance of these aluminum parts.
It is desirable to set the temperature to ° C.

In this way, when the titanium oxide layer 20 is formed on the crown surface of the piston 2 and the inner surface of the cylinder head 3, the molecules generated in the combustion process of the air-fuel mixture are identified in the combustion chamber 4 as shown in FIG. There is light emission of a wavelength, and in particular, ultraviolet light emission of a wavelength of about 400 nm or less at which the photocatalytic action of titanium oxide 21 becomes active is generated. Organic substances such as the lubricating oil component are decomposed by the photocatalytic reaction of the titanium oxide 21.

FIG. 8 shows the results of gas chromatograph analysis of the organic substances deposited on the crown surface of the piston 2 with and without the titanium oxide layer 20 when the engine was operated under the same conditions. (B)
As shown in, the detection time is 9.6 minutes, 14.3 minutes, 1
6.4 minutes, 18.1 minutes, 19.6 minutes, 23.2 minutes, 2
Hydrocarbons (HC) with a large number of molecules in each 4.4-minute period
However, hydrocarbons (HC) were not detected in the titanium oxide layer-treated type as shown in (a) of the figure, and the photocatalytic function was exhibited in the titanium oxide layer 20 on the crown surface of the piston 2. I understand.

On the other hand, FIG. 9 shows the analysis results of detecting the metallic components on the treated and untreated titanium crown layers of the respective piston crown surfaces. ) Indicates a titanium oxide layer-treated product, and in any case, calcium (Ca) and phosphorus (P) characteristic of the lubricating oil component are detected on the crown surface of the piston 2 in substantially the same manner.

From these analysis results, at least the lubricating oil is used for both the treated and untreated pistons 2 of the titanium oxide layer 20.
Although it adheres to the crown surface, it can be seen that hydrocarbons (HC) are decomposed and cleaned in the treated product of the titanium oxide layer 20.

The above-mentioned lubricating oil enters the combustion chamber 4 along the sliding surface between the piston 2 and the cylinder block 1. Therefore, this lubricating oil adheres to the crown surface of the piston 2 and its outer peripheral portion, and the cylinder. The annular area portion near the boundary of the head 3 with the cylinder bore tends to increase.

Therefore, it is effective to provide the titanium oxide layer 20 only on the outer peripheral portion of the crown surface of the piston 2 and the annular region portion near the boundary of the cylinder head 3 with the cylinder bore.

Here, in the combustion chamber 4, the respective umbrella portions 5a, 6a of the intake valve 5 and the exhaust valve 6 are arranged in a standing manner, and the ignition plug 7 is arranged in a projecting manner.
6 and the spark plug are also components that form the inner surface of the combustion chamber 4.

Therefore, by providing the titanium oxide layer 20 on the intake / exhaust valves 5, 6 and the ignition plug 7 as described above, the measure against deposits in the combustion chamber 4 becomes more effective.

Regarding the intake valve 5 and the exhaust valve 6, the titanium oxide layer 20 may be only the surface of each umbrella portion 5a, 6a on the side of the combustion chamber 4, but as shown in FIG. It is desirable to provide the titanium oxide layer 20 on the surface and the portions exposed to the intake port 8 and the exhaust port 9 of each of the stems 5b and 6b.

As for the spark plug 7, as shown in FIG. 4, the titanium oxide layer 20 is formed on the metal portion other than the discharge surface of the center electrode 7a and the ground side electrode 7b.

By providing the titanium oxide layer 20 on the intake and exhaust valves 5 and 6 in this manner, organic substances such as soot and unburned fuel are formed on the surfaces of the umbrellas 5a and 6a on the side of the combustion chamber 4 as described above. As described above, the titanium oxide layer 20 is decomposed by a photocatalytic reaction to obtain a deposit adhesion suppressing effect. Similarly, on the surface of the intake valve 5 on the intake port 8 side, the fuel that enters the combustion chamber 4 from the intake port 8 is also removed. The effect of suppressing the adhesion of deposits due to adhesion and the adhesion of deposits due to the adhesion of unburned fuel and soot in the combustion gas flowing from the combustion chamber 4 to the exhaust port 9 on the surface of the exhaust valve 6 on the exhaust port 9 side. Suppressive effect is obtained, and these suctions due to the adhesion of deposit,
The sticking of the exhaust valves 5, 6 can be avoided.

Further, in the spark plug 7, the presence of the titanium oxide layer 20 makes it possible to avoid deposit deposits around the discharge surface of the spark plug 7, as described above.

Since the metal head gasket 10 is interposed between the cylinder block 1 and the cylinder head 3, the thickness of the head gasket 10 is provided between the cylinder block 1 and the cylinder head 3. A quench gap C is created.

Therefore, by forming the titanium oxide layer 20 on the surface of the quench gap C as shown in FIG. 5, it is possible to take a comprehensive measure against deposits in the combustion chamber 4.

That is, when the quench gap C is present in the connecting portion between the cylinder block 1 and the cylinder head 2 as described above, the lubricating oil and the fuel enter and adhere to the gap C, which causes the deposit. However, the organic substance that enters the quench gap C and adheres to the surface is the titanium oxide layer 20.
It is decomposed by the photocatalytic reaction at 1, thereby avoiding deposit accumulation.

In the cylinder injection type spark ignition engine, the fuel injection valve 11 is installed in the combustion chamber 4 as shown by the broken line in FIG.

Therefore, in such a cylinder injection type spark ignition engine, as shown in FIG. 6, the titanium oxide layer 2 is also formed in the portion of the fuel injection valve 11 exposed in the combustion chamber 4 as described above.
0 is formed.

By forming the titanium oxide layer 20 in the exposed portion of the combustion chamber of the fuel injection valve 11 in this way, deposits on the tip of the fuel injection valve due to soot and fuel after injection, or adhesion of lubricating oil. Adhesion suppression effect is obtained,
In addition to being able to thoroughly implement deposit measures for the combustion chamber 4,
It is possible to avoid a change in the fuel injection angle, the fuel injection amount, and the like due to the deposit adhesion to the tip portion of the fuel injection valve, and it is possible to improve the stability and output of combustion.

On the other hand, the combustion gas in the combustion chamber 4 is discharged to the exhaust port 9 in the exhaust stroke, but the combustion is continued in the exhaust port 9 and the exhaust manifold 12 following the exhaust port 9 to cause a photocatalytic reaction of titanium oxide. Effective combustion light is emitted.

Therefore, the titanium oxide layer 20 is formed on the inner surfaces of the exhaust port 9 and the exhaust manifold 12 in the same manner as described above, as shown in FIG. 1, so that the late combustion is continued. Also, the photocatalytic action of the titanium oxide layer 20 is exerted in the exhaust manifold 12 as well, so that the accumulation of deposits due to the attachment of soot and unburned fuel can be prevented, the influence on the cylinder pressure can be avoided, and the stability of combustion and The output can be improved and harmful exhaust components can be reduced.

In the present invention, as described above, the silicon coating 2 is formed on the surface of each of the above-mentioned components forming the inner surface of the combustion chamber 4 and the inner surfaces of the exhaust port 9 and the exhaust manifold 12.
In addition to providing a titanium oxide layer 20 having 2 as a base so as to exhibit a photocatalytic action, the ignition plug 7 is provided with spark ignition for air-fuel mixture ignition in the compression stroke and the combustion in the exhaust stroke. A multi-step ignition operation is performed with spark ignition for photocatalytic activity of the titanium oxide layer 20 on the inner surface of the chamber 4.

The multi-stage ignition operation of the ignition plug 7 is as follows.
It is controlled by the ignition device 23 shown in FIG.

10 to 14 show different examples of ignition timing of the ignition plug 7 by the ignition device 23.

In the first embodiment shown in FIG. 10, the spark plug 7
The ignition timing of is set in multiple stages to a first ignition timing P ₁ in the latter half of the compression stroke and a second ignition timing P ₂ in the latter half of the exhaust stroke, and spark ignition for air-fuel mixture ignition is performed in the latter half of the compression stroke. The spark ignition for the photocatalytic activity of the titanium oxide layer 20 on the inner surface of the combustion chamber 4 is performed in the latter stage of the exhaust stroke.

Therefore, according to the first embodiment, after the air-fuel mixture is spark ignited by the ignition operation of the spark plug 7 in the compression stroke, the combustion is performed by the combustion light generated by the combustion of the air-fuel mixture in the expansion stroke as described above. Titanium oxide layer 20 on the inner surface of chamber 4
On the other hand, when the piston 2 rises and approaches the ignition plug 7 in the exhaust stroke where the combustion light tends to decrease, the ignition plug 7 is ignited again and discharge light is generated. In this exhaust stroke as well, the photocatalytic action of the titanium oxide layer 20 can be actively carried out, so that the deposit adhesion on the inner surface of the combustion chamber 4 can be thoroughly prevented.

Further, in the first embodiment, the ignition operation in the exhaust stroke of the ignition plug 7 is performed in the same manner as the ignition operation in the compression stroke, so that the ignition device 23 can be realized without any special improvement. it can.

FIG. 11 shows a second mode of ignition timing of the spark plug 7. In this second mode, the spark plug 7 is discharged for a long time at the second ignition timing P ₂ in the exhaust stroke. The operation is controlled to be performed.

The long-time spark discharge control of the spark plug 7 can be realized by using, for example, the long-time ignition device as disclosed in Japanese Patent Laid-Open No. 6-66236 as the ignition device 23.

In this way, the ignition operation in the exhaust stroke of the spark plug 7 is performed by the long-time ignition device to perform the spark discharge for a long time, so that the discharge light of the spark plug 7 is maintained for a long time in the exhaust stroke. In particular, when discharge is performed for a long time in the exhaust stroke, the pressure around the spark plug 7 is low in this exhaust stroke, and the discharge voltage of the spark plug 7 becomes a function of this cylinder pressure. Since the initial peak voltage becomes low, a large amount of discharge energy remains after that, and discharge can be reliably maintained for a long time, and the discharge energy becomes high as the cylinder pressure decreases due to the progress of the exhaust stroke. Since the discharge light can be intensified, the photocatalytic action of the titanium oxide layer 20 on the inner surface of the combustion chamber 4 can be reliably and more actively performed over the end of the exhaust stroke.

FIG. 12 shows a third form of the ignition timing of the spark plug 7. In this third form, the ignition period of the second ignition timing P ₂ in the exhaust stroke is set to be substantially the entire exhaust stroke. The spark plug 7 is set and the operation of the spark plug 7 is controlled so that a short-time spark discharge is repeatedly performed during this ignition period.

The multiple discharge control of the ignition plug 7 in the required ignition period is performed by, for example, the ignition device 23 as disclosed in Japanese Patent Laid-Open No. 6-3.
It can be realized by using a multiple ignition device as disclosed in Japanese Patent No. 30836.

As described above, the ignition operation of the spark plug 7 in the exhaust stroke is repeatedly performed by the multiple-type ignition device in a short period of time over the entire exhaust stroke, and the multiple discharges are performed. The discharge light of the spark plug 7 is obtained intermittently, and since the discharge energy increases and the discharge light is intensified as the cylinder pressure decreases due to the progress of the exhaust stroke, the discharge light is increased over almost the entire exhaust stroke. To ensure the photocatalytic action of the titanium oxide layer 20 on the inner surface of the combustion chamber 4,
And, it can be performed more actively.

FIG. 13 shows a fourth mode of the ignition timing of the spark plug 7. In this fourth mode, the ignition operation of the spark plug 7 in the exhaust stroke is continued from the expansion stroke. It was done.

In the fourth embodiment, specifically, the ignition device 2
The discharge type Pa is set as the range from the latter half of the compression stroke to the end of the exhaust stroke by using the above-mentioned multiple ignition device as 3, and the spark plug 7 is caused to repeatedly perform short-time spark discharge in this discharge period Pa. I am trying.

Therefore, according to the fourth embodiment, after the spark ignition of the spark plug 7 in the latter stage of the compression stroke, the mixture is spark ignited, and then the spark discharge of the spark plug 7 is performed in the ignition period Pa over the end of the exhaust stroke. Since multiple discharges are repeated in a short time, the probability of ignition of the air-fuel mixture can be increased and stable combustion can be realized, and, of course, the discharge light of the spark plug 7 is continuously discharged from the expansion stroke to the end of the exhaust stroke. The discharge energy increases and the discharge light is intensified as the cylinder pressure decreases due to the progress from the expansion stroke to the end of the exhaust stroke. The photocatalytic action of the titanium oxide layer 20 on the inner surface of the combustion chamber 4 can be reliably and more actively performed over the final period.

In this multiple discharge control, for example, as shown in FIG.
As shown in (1), the unit discharge time may be increased to shorten the discharge cycle in the discharge period Pa so that the discharge energy on the exhaust stroke side becomes higher and the discharge light on the exhaust stroke side becomes stronger. it can.

Here, regardless of which of the above ignition timings is set, the final ignition timing of the ignition plug 7 is
It is important to set the combustion chamber 4 immediately before a new air-fuel mixture is formed to avoid misfiring and ensure the stability of the engine. In a premixed engine, it is necessary to perform injection immediately before the intake valve 5 is opened and in a cylinder. In the engine, it is set until immediately before the fuel injection of the fuel injection valve 11, and by the way, in the ignition timing shown in FIG. 11, the final ignition timing in the second ignition period P ₂ is shifted to the beginning of the intake stroke. This is based on the assumption that it is compatible with in-cylinder injection engines.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of a titanium oxide layer according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an intake / exhaust valve according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a spark plug according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view of a head gasket interposing portion according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram of a fuel injection valve according to an embodiment of the present invention.

FIG. 7 is an explanatory view showing wavelength characteristics of combustion light in a combustion chamber.

FIG. 8 is an explanatory diagram showing the results of adhesion analysis of organic substances.

FIG. 9 is an explanatory diagram showing an oil adhesion analysis result on the piston crown surface.

FIG. 10 is an explanatory diagram showing a first form of ignition timing of an ignition plug.

FIG. 11 is an explanatory diagram showing a second mode of ignition timing of the spark plug.

FIG. 12 is an explanatory view showing a third mode of ignition timing of an ignition plug.

FIG. 13 is an explanatory view showing a fourth mode of ignition timing of the spark plug.

FIG. 14 is an explanatory view showing a fifth mode of ignition timing of an ignition plug.

[Explanation of symbols]

1 cylinder block 2 pistons 3 cylinder head 4 Combustion chamber 5 intake valve 6 exhaust valve 7 Spark plug 8 intake ports 9 exhaust port 10 head gasket 11 Fuel injection valve 12 Exhaust manifold 20 Titanium oxide layer 21 Titanium oxide 22 Silicon coating

Continuation of front page (51) Int.Cl. ⁷ identification code FI F02F 1/00 F02F 1/00 D 3/12 3/12 (58) Fields investigated (Int.Cl. ⁷ , DB name) F02P 15/00 C23C 28/00 F01N 7/16 F02B 23/00-23/06 F02F 1/00 F02F 3/12

Claims (8)

(57) [Claims] 1. A surface of a component forming an inner surface of a combustion chamber,
While coating a titanium oxide layer with a silicon film as a base, a spark plug is provided with a spark ignition for mixture ignition in the compression stroke and a spark ignition for photocatalytic activity of the titanium oxide layer in the exhaust stroke. An internal combustion engine, characterized in that a stepwise ignition operation is performed. 2. The internal combustion engine according to claim 1, wherein the ignition operation in the exhaust stroke of the spark plug is performed by a long-time ignition device that causes spark discharge for a long time. 3. The internal combustion engine according to claim 1, wherein the ignition operation in the exhaust stroke of the spark plug is performed by a multiple ignition device that repeats a short-time spark discharge for a required ignition period. . 4. The internal combustion engine according to claim 1, wherein the ignition operation in the exhaust stroke of the spark plug is continued from the expansion stroke. 5. The multiple ignition device according to claim 4, wherein the ignition operation from the expansion stroke to the exhaust stroke of the spark plug is performed by a multiple ignition device that repeats a short-time spark discharge in a required ignition period. Internal combustion engine described. 6. The internal combustion engine according to claim 1, wherein the final ignition timing of the spark plug in the exhaust stroke is set immediately before a new air-fuel mixture is formed in the combustion chamber. 7. The internal combustion engine according to claim 1, wherein the inner surface of the exhaust port continuing from the combustion chamber is coated with a titanium oxide layer having a silicon coating as a base. 8. The internal combustion engine according to claim 7, wherein the inner surface of the exhaust manifold following the exhaust port is coated with a titanium oxide layer having a silicon coating as a base.