JPH11236677A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of avoiding the generation of deposit on the inner surface of a combustion chamber by attaining decomposition action to an organic material such as a lubricant or an unburned fuel causing the deposit. SOLUTION: The organic material such as soot, the unburned fuel and the lubricant is decomposed and the deposit stuck on the inner surface of the combustion chamber is avoided by applying a silica sol incorporating the fine particle of a titanium oxide on the surface of parts constituting the inner surface of the combustion chamber such as the crown surface of a piston 2, the inner surface of a cylinder head and firing to form a titanium oxide layer 20 so that photocatalytic reaction of titanium oxide 21 is derived by the combustion light generated in the combustion chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 are disclosed in, for example,
As disclosed in Japanese Patent No. 05352, a combustion chamber of an internal combustion engine is constituted 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, and the like on the surface. By
There has been known an apparatus which suppresses deposit accumulation on the surface of the combustion chamber.

[0003]

However, in the above-mentioned prior art, soot generated by combustion of the air-fuel mixture in the combustion chamber, lubricating oil entering the combustion chamber, or unburned fuel remains on the combustion chamber. Deposition of the deposit generated by the above-mentioned method depends only on a decrease in the adhesion of the deposit due to a ceramic coating layer or the like provided on the metal surface of the portion constituting the combustion chamber. When a precursor which becomes a nucleus to which the gas adheres is generated, the deposition of the deposit proceeds rapidly, and the deterioration of the combustion due to the change in the volume of the combustion chamber, the deterioration of the combustion due to the mixture ignition before ignition by the spark plug, and the deposit There is a possibility that a problem such as an increase in exhaust components such as unburned HC generated and discharged from the fuel tank may occur.

Therefore, the present invention provides an effect of decomposing organic substances such as lubricating oil and unburned fuel which cause deposits.
An object of the present invention is to provide an internal combustion engine capable of avoiding generation of deposits on the surface of a combustion chamber or the like.

[0005]

According to the first aspect of the present invention, a silica sol mixed with titanium oxide fine particles is applied to the surface of a component constituting an inner surface of a combustion chamber, and the resultant is baked to be oxidized. It is characterized by forming a titanium layer.

According to a second aspect of the present invention, the portion of the combustion chamber in which the titanium oxide layer is formed according to the first aspect has at least a portion near the boundary between the outer peripheral portion of the piston crown surface and the cylinder bore of the cylinder head. It is characterized by including an annular region portion.

[0007] In the invention of claim 3, claims 1 and 2
Wherein the portion of the combustion chamber in which the titanium oxide layer is formed includes umbrella portions of the intake valve and the exhaust valve.

[0008] In the invention of claim 4, claims 1 to 3 are provided.
Wherein the portion of the combustion chamber in which the titanium oxide layer is formed includes a surface of a gap formed by a cylinder head, a cylinder block, and a head gasket interposed therebetween.

In the invention of claim 5, claims 1 to 4 are provided.
Wherein the portion of the combustion chamber in which the titanium oxide layer is formed includes a metal portion other than the discharge surface of the ignition plug.

According to the invention of claim 6, claims 1 to 5 are provided.
Wherein the portion of the combustion chamber where the titanium oxide layer is formed includes an exposed portion of the combustion chamber of the fuel injection valve provided in the combustion chamber.

According to the invention of claim 7, claims 1 to 6 are provided.
The present invention is characterized in that a silica sol mixed with titanium oxide fine particles is applied to the inner surface of an exhaust port following the combustion chamber described in (1) above, and this is baked to form a titanium oxide layer.

According to an eighth aspect of the present invention, a silica sol mixed with fine particles of titanium oxide is applied to the inner surface of the exhaust manifold following the exhaust port according to the seventh aspect, and the silica sol is fired to form a titanium oxide layer. Is formed.

According to the ninth aspect of the present invention, the first to eighth aspects are provided.
Is characterized by being fine particles of anatase crystal.

[0014]

According to the first aspect of the present invention, the photocatalytic action of the titanium oxide fine particles of the titanium oxide layer provided on the inner surface of the combustion chamber can be obtained by the light generated by the combustion of the air-fuel mixture in the combustion chamber. Organic substances such as lubricating oil and unburned fuel that cause deposits are decomposed and generated on the surface of the combustion chamber, or the deposits that are being generated are easily separated and adhere to the surface of the combustion chamber. Can be avoided.

In particular, since the titanium oxide layer is formed by applying silica sol mixed with fine particles of titanium oxide to the surface of the components of the combustion chamber and firing it, the adhesion to the metal surface, the electrical insulation,
And it is excellent in photoactivity and can enhance the photocatalytic effect.

According to the invention described in claim 2, according to claim 1
In addition to the effect of the invention, the outer peripheral portion of the piston crown surface where the lubricating oil entering the combustion chamber from the sliding contact surface between the piston and the cylinder block is likely to adhere, Since the head includes the annular region near the boundary with the cylinder bore of the head, it is possible to avoid the generation of deposits due to the adhesion of the lubricating oil at these portions where the lubricating oil is most likely to adhere.

According to the third aspect of the present invention, in addition to the effects of the first and second aspects, the portion of the combustion chamber where the titanium oxide layer is formed includes the head portions of the intake valve and the exhaust valve. Therefore, the effect of suppressing the adhesion of deposits caused by soot and unburned fuel is obtained on the surface of the umbrella portion of the intake valve and the exhaust valve on the combustion chamber side, and the surface of the intake valve on the intake port side is close to the intake port. The effect of suppressing deposit adhesion caused by the adhesion of fuel entering the combustion chamber, and the suppression of deposit adhesion caused by the adhesion of unburned fuel and soot flowing from the combustion chamber to the exhaust port on the surface of the exhaust valve on the exhaust port side The effect is obtained.

According to the invention of claim 4, according to claim 1,
In addition to the effects of the inventions of (1) to (3), since the portion of the combustion chamber where the titanium oxide layer is formed includes the surface of the gap formed by the cylinder head, the cylinder block, and the head gasket interposed therebetween. Thus, an effect of suppressing deposit adhesion due to adhesion of lubricating oil or fuel entering the quenching (extinguishing) gap between the cylinder head and the cylinder block can be obtained.

According to the invention of claim 5, according to claim 1,
In addition to the effects of the inventions of (1) to (4), since the portion of the combustion chamber where the titanium oxide layer is formed includes a metal portion other than the discharge surface of the ignition plug, the ignition plug is caused by soot and unburned fuel. The effect of suppressing the adhesion of the deposit around the discharge surface can be obtained.

According to the invention of claim 6, according to claim 1,
In addition to the effects of the inventions of (1) to (5), in the case of the direct injection type spark ignition engine, the portion of the combustion chamber where the titanium oxide layer is formed includes the exposed portion of the combustion chamber of the fuel injection valve provided in the combustion chamber. Therefore, an effect of suppressing the adhesion of the deposit to the tip portion of the fuel injection valve due to the adhesion of the soot and the injected fuel or the lubricating oil can be obtained.

According to the invention of claim 7, according to claim 1,
In addition to the effects of the inventions of (1) to (6), a titanium oxide layer is formed on the inner surface of the exhaust port following the combustion chamber by applying a silica sol mixed with titanium oxide fine particles and firing the silica sol. The photocatalytic action of the titanium oxide layer is exerted by the light generated by the combustion even in the exhaust port in which the latter combustion is continued, and an effect of suppressing the deposit 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, according to claim 7,
In addition to the effect of the invention, the titanium oxide layer is formed also by applying a silica sol mixed with titanium oxide fine particles to the inner surface of the exhaust manifold following the exhaust port and firing it, so that the latter combustion Even in the exhaust manifold where the temperature is maintained, the photocatalytic action of the titanium oxide layer is exerted by the light generated by the combustion, and the effect of suppressing the deposit adhesion on the inner surface of the exhaust manifold due to the adhesion of soot and unburned fuel is obtained.

According to the invention of claim 9, according to claim 1,
In addition to the effects of the present invention, since the fine particles of anatase type crystal having the highest photoactivity are used as titanium oxide, the organic substance such as the soot and unburned fuel is used as a photocatalyst of titanium oxide fine particles of anatase type crystal. It is decomposed by the function, and the effect of suppressing the adhesion of the deposit can be further enhanced.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In FIG. 1, 1 is a cylinder block, 2
Represents a piston, 3 represents a cylinder head, and 4 represents a combustion chamber formed by the cylinder block 1, the piston 2, and the cylinder head 3.

As shown in FIG. 2, titanium oxide 2 is provided on the surface of the components constituting the inner surface of the combustion chamber 4, specifically, on the crown surface of the piston 2 and the inner surface of the cylinder head 3.
A titanium oxide layer 20 is formed by applying a silica sol 22 mixed with the fine particles of 1 and firing the silica sol 22, and a photocatalytic reaction occurs in the titanium oxide layer 20 by light generated by combustion of the air-fuel mixture in the combustion chamber 4. It is like that.

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 size of 1 to 20 nm are preferably used.

If the particle diameter of the fine particles of titanium oxide 21 is smaller than the above range, the fine particles of titanium oxide 21 will aggregate when stirred with the silica sol 22, and if the particle diameter is larger than the above range, the fine particles of titanium oxide 21 will agglomerate. 21 has an extremely low photoactivity.

On the other hand, the filling ratio of the silica sol 22 containing the fine particles of the titanium oxide 21 is preferably 5 to 40%.

In order to obtain the adhesion between the titanium oxide layer 20 and the 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 coating of the titanium oxide layer 20, It is necessary that the filling ratio is 5% or more, and if the filling ratio exceeds 40%, poor photoactivity of the titanium oxide 21 occurs.

The titanium oxide layer 20 is made of silica sol 22
Is baked at a temperature of 300 ° C. or more at which
Since the crystal of titanium oxide 21 changes from the anatase type to the rutile type on the high temperature side of not less than 0 ° C., it is important to bake it on the lower temperature side of 700 ° C. In particular, the titanium oxide layer 20 is formed as described above. When provided on aluminum parts such as the piston 2 and the cylinder head 3, the upper limit of the firing temperature is set to 350 ° C. to 4 in consideration of the heat resistance of these aluminum parts.
Desirably, the temperature is set to 00 ° C.

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 in this manner, the molecules generated in the combustion process of the air-fuel mixture are specified 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 action of the photocatalyst of titanium oxide 21 becomes active, so that soot or unburned HC adhering to the crown surface of the piston 2 or the inner surface of the cylinder head 3 is generated. Organic substances such as lubricating oil components are decomposed by the photocatalytic reaction of the titanium oxide 21.

FIG. 8 shows the results of gas chromatographic analysis of the adhesion of organic substances 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 figure, the detection time was 9.6 minutes, 14.3 minutes, 1
6.4 minutes, 18.1 minutes, 19.6 minutes, 23.2 minutes, 2
Hydrocarbon (HC) with a large number of molecules in each time zone of 4.4 minutes
However, in the case of the titanium oxide layer treatment, hydrocarbon (HC) was not detected as shown in (a) of the figure, and the photocatalytic function in the titanium oxide layer 20 on the piston 2 crown surface was exhibited. You can see that.

On the other hand, FIG. 9 shows the analysis results of detecting metal components on the piston crown surfaces of the treated and untreated titanium oxide layer 20. FIG. ) Indicates a titanium oxide layer-treated product. In each case, calcium (Ca) and phosphorus (P) characteristic of a lubricating oil component are detected on the crown surface of the piston 2 in substantially the same manner.

From these analysis results, it is found that at least the lubricating oil is treated with or without the treated 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, and therefore, the adhesion of the lubricating oil also occurs on the outer peripheral portion of the crown surface of the piston 2 and the cylinder. There is a tendency that the annular region near the boundary between the head 3 and the cylinder bore increases.

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 near the boundary of the cylinder head 3 with the cylinder bore.

Here, in the combustion chamber 4, umbrella portions 5a and 6a of intake valves 5 and exhaust valves 6 are arranged so as to face each other, and spark plugs are arranged so as to protrude.
The ignition plug is also a component that forms the inner surface of the combustion chamber 4.

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

With respect to the intake valve 5 and the exhaust valve 6, the titanium oxide layer 20 may be formed only on 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 a 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, a titanium oxide layer 20 is formed on a metal portion other than the discharge surface of the center electrode 7a and the ground electrode 7b.

As described above, by providing the titanium oxide layer 20 on the intake and exhaust valves 5 and 6, on the surfaces of the umbrella portions 5a and 6a on the side of the combustion chamber 4, organic substances such as soot and unburned fuel are removed. As described above, it is decomposed by the photocatalytic reaction in the titanium oxide layer 20 to obtain the effect of suppressing the adhesion of the deposit. Similarly, the surface of the intake valve 5 on the intake port 8 side of the fuel that enters the combustion chamber 4 from the intake port 8. The effect of suppressing the adhesion of the deposit due to the adhesion, and the adhesion of the deposit due to the adhesion of unburned fuel and soot in the combustion gas flowing out from the combustion chamber 4 to the exhaust port 9 on the surface of the exhaust valve 6 on the exhaust port 9 side. An inhibitory effect is obtained, and these absorptions,
The stick of the exhaust valves 5 and 6 can be avoided.

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

Since a metal head gasket 10 is interposed between the cylinder block 1 and the cylinder head 3, a gap corresponding to the thickness of the head gasket 10 is provided between the cylinder block 1 and the cylinder head 3. A quench (extinguishment) gap C is generated.

Therefore, by forming the titanium oxide layer 20 also 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, as described above, if the quench gap C exists at the joint between the cylinder block 1 and the cylinder head 2, lubricating oil or fuel enters the gap C and causes a deposit. However, the organic substance that enters the quench gap C and adheres to the surface is the titanium oxide layer 20.
Is decomposed by the photocatalytic reaction in the, and the accumulation of deposits is avoided.

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

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

By forming the titanium oxide layer 20 on the exposed portion of the combustion chamber of the fuel injection valve 11 as described above, the deposit on the tip of the fuel injection valve caused by the adhesion of soot and fuel after injection or lubricating oil is obtained. Adhesion control effect is obtained,
In addition to ensuring thorough measures against deposits in the combustion chamber 4,
It is possible to avoid a change in the fuel injection angle, the fuel injection amount, and the like caused by the deposit attached to the tip portion of the fuel injection valve, thereby improving the stability of combustion and the output.

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

Therefore, a titanium oxide layer 20 is also 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. In the exhaust manifold 12, the photocatalytic action of the titanium oxide layer 20 is exerted, deposits due to the adhesion of soot and unburned fuel can be prevented, and the influence on the in-cylinder pressure can be avoided to improve combustion stability and Output can be improved and harmful exhaust components can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of a titanium oxide layer in one embodiment of the present invention.

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

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

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

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

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

FIG. 8 is an explanatory view showing an analysis result of adhesion of an organic substance.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Piston 3 Cylinder head 4 Combustion chamber 5 Intake valve 6 Exhaust valve 7 Spark plug 8 Intake port 9 Exhaust port 10 Head gasket 11 Fuel injection valve 12 Exhaust manifold 20 Titanium oxide layer 21 Titanium oxide 22 Silica sol

Claims (9)

[Claims] 1. The surface of a component constituting an inner surface of a combustion chamber,
An internal combustion engine wherein a silica sol mixed with titanium oxide fine particles is applied and baked to form a titanium oxide layer. 2. The combustion chamber according to claim 1, wherein the portion of the combustion chamber on which the titanium oxide layer is formed includes at least an outer peripheral portion of the piston crown surface and an annular region near a boundary between the cylinder bore of the cylinder head and the cylinder head. An internal combustion engine as described. 3. The internal combustion engine according to claim 1, wherein the portion of the combustion chamber where the titanium oxide layer is formed includes umbrella portions of an intake valve and an exhaust valve. 4. The combustion chamber in which the titanium oxide layer is formed includes a surface of a gap formed by a cylinder head, a cylinder block, and a head gasket interposed therebetween. An internal combustion engine according to any one of claims 1 to 3. 5. The internal combustion engine according to claim 1, wherein the portion of the combustion chamber where the titanium oxide layer is formed includes a metal portion other than the discharge surface of the spark plug. 6. The internal combustion engine according to claim 1, wherein the portion of the combustion chamber where the titanium oxide layer is formed includes an exposed portion of the combustion chamber of the fuel injection valve provided in the combustion chamber. organ. 7. The titanium oxide layer according to claim 1, wherein a silica sol mixed with fine particles of titanium oxide is applied to an inner surface of an exhaust port connected to the combustion chamber, and baked to form a titanium oxide layer. The internal combustion engine according to any one of the above. 8. The titanium oxide layer according to claim 7, wherein a silica sol mixed with fine particles of titanium oxide is applied to the inner surface of the exhaust manifold following the exhaust port, and is baked to form a titanium oxide layer. Internal combustion engine. 9. The internal combustion engine according to claim 1, wherein the titanium oxide is fine particles of anatase type crystals.