JPS632009B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a combustion chamber of an internal combustion engine, and the present invention relates to a combustion chamber that suppresses the occurrence of knocking by improving the cooling performance of a valve seat ring in a region where end gas is particularly likely to be generated. This is related to the structure of the port portion.

Internal combustion engines for vehicles such as automobiles are required to have low fuel consumption. In order to achieve low fuel consumption, it is effective to make the air-fuel mixture lean and perform combustion at a high compression ratio. In order to improve the lean limit, it is necessary to stabilize combustion, but in order to generate vortices and turbulence in the mixture within the combustion chamber, it is necessary to provide two intake ports and make one a helical port, or use a piston. It is effective to provide a so-called recess in the cylinder head and to provide a squish area around the recess for pushing out the air-fuel mixture into the recess. Furthermore, in order to achieve a high compression ratio, it is necessary to prevent the occurrence of knocking, and for this purpose it is effective to use a small-bore engine with a small diameter in order to reduce the flame propagation distance. In order to satisfy these conditions, that is, to make a small-bore engine, provide a squeezing area in the combustion chamber, and provide at least two intake ports or exhaust ports, one of the ports of the same type must be will have to be placed in the stock area.

By the way, flame generation sources such as spark plugs or preheating plugs (simply referred to as spark plugs in this specification)
is located in the recess of the combustion chamber, the squeezing area on the opposite side of the spark plug with respect to the virtual plane including the cylinder centerline is located far from the spark plug and when the piston is at the top dead center position. Because the gap between the top surface of the piston and the bottom surface of the cylinder block is small, it is difficult for flame to spread, and as the piston rises, the air-fuel mixture is most compressed and the temperature increases, so the squish area is It is also a part where abnormal combustion, so-called knocking, is likely to occur before the flame propagation from the spark plug reaches the engine.

On the other hand, an intake valve or an exhaust valve is installed in the port so that the port can be opened and closed, but the seat of the valve is usually formed from a ring that is separate from the cylinder head and is fitted into the port. Take structure.
Therefore, the contact heat transfer between the valve seat ring and the cylinder head is poor, and heat does not necessarily escape smoothly from the valve seat ring through the cylinder head to the water jacket in the cylinder head, and the valve seat ring does not move smoothly during engine operation. It gets quite hot. In this case, if the valve seat ring of the port provided in the squeezing area on the opposite side of the spark plug becomes hot, it will further promote abnormal combustion in the area where knocking is likely to occur. This will hinder the achievement and promotion of low fuel consumption that satisfies the following.

In order to solve such problems, the present invention has the following features:
The purpose of this is to improve the cooling performance of the valve seat ring, which is the part where knocking is most likely to occur, in the combustion chamber structure of a 3-valve or 4-valve engine that has at least two intake ports or two exhaust ports. The purpose of this is to suppress the occurrence of knocking and contribute to achieving low fuel consumption.

In order to achieve this object, in the combustion chamber of the internal combustion engine of the present invention, the squish area is disposed at a portion of the squish area that is larger in area than the squish area located far from the spark plug and close to the spark plug. The press-fit length of the valve seat ring for ports located in areas where gas is likely to be generated is longer than the press-fit length of valve seat rings for ports of the same type that are located closer to the spark plug. has been done. In this way, there has never been a device that changes the press-fit length of the valve seat ring between ports of the same type, but by adopting this new structure, the length of the press-fitting valve seat ring can be changed from the valve seat ring in the area where knotting is likely to occur, to the cylinder head, and eventually to the cylinder. Heat transfer to the cooling water flowing through the water jacket in the head is improved, and the surface temperature of the valve seat ring, the port area near it, the valve itself, etc. can be reduced, and the occurrence of knocking can be suppressed. It turns out.

Preferred embodiments of the combustion chamber of the internal combustion engine of the present invention will be described below with reference to the drawings, taking as an example an engine in which each cylinder is provided with two intake ports. 1 to 3 show the structure of a combustion chamber and its vicinity according to an embodiment of the present invention.
In the figure, 1 is a cylinder block, and the cylinder block 1 has a cylinder bore 2 of relatively small diameter. A piston 3 is slidably inserted into the cylinder bore 2. The cylinder bore 2 is covered at its upper part by a cylinder head 4, and a gasket 5 is disposed between the cylinder block 1 and the cylinder head 4 to seal the space between them.

The piston 3 has a so-called recess at its top at a position that is biased to one side, that is, to the right in the figure, with respect to an imaginary plane containing the central axis A of the cylinder bore 2 (an imaginary plane perpendicular to the plane of paper in FIG. 2). It has a combustion chamber recess 6. The top surface 7 of the piston 3 is
It is formed flat over the entire circumference except for the piston combustion chamber recess 6, and constitutes one wall surface of the full circumference skid area 8. Further, the cylinder head 4 has a recess, so-called cylinder head combustion chamber recess 9, at a position corresponding to the piston combustion chamber recess 6 in its lower part. The cylinder head combustion chamber recess 9 has a slightly inclined bottom surface in the vicinity of the port opening, and has a so-called wedge shape. The lower surface 10 of the cylinder head 4 is
The combustion chamber is formed flat except for the recess 9, and forms a squish area 8 in cooperation with the flat top surface 7 of the piston 3, and constitutes a wall surface on the upper side of the squish area 8. ing. With this configuration, the squish area 8 has combustion chamber recesses 6, 9.
is biased to one side with respect to the imaginary plane including the cylinder bore central axis, that is, to the right in FIG. A small squish area 8b extends narrowly along the entire circumference.

The cylinder head 4 includes an intake port consisting of a so-called Siamese port, which is a twin port consisting of a helical main intake port 11 and a straight auxiliary intake port 12 having a smaller cross-sectional area than the main intake port, and an exhaust port 13. A spark plug 14 is also provided. The Siamese port is not equipped with a throttle valve. Among the above ports, the main intake port 11 and the exhaust port 13 open into the cylinder head combustion chamber recess 9, and the sub intake port 12 opens into the large-area squish area 8a.
It is open to Further, the spark plug 14 is provided at a position opposite to a virtual plane including the large squish area 8a and the piston bore center axis. And the ignition part 1 of the spark plug 14
4a is a position in the combustion chamber recess 9 at or slightly above the boundary between the cylinder block 1 and the cylinder head 4 in the height direction, and is located at the inner periphery of the small squish area 8b in plan view. It is arranged at a position close to the stocking area 8b on the side.

Each of the main intake port 11, sub-intake port 12, and exhaust port 13 has a main intake valve 15,
A sub-intake valve 16 and an exhaust valve 17 are installed so as to be able to open and close their respective ports. Further, each of the main intake port 11, sub-intake port 12, and exhaust port 13 is provided with valve seat rings 18, 19, which are formed separately from the cylinder head 4.
20 are press-fitted into the corresponding ports and fixed. Valve seat ring 1
Of the ports 8, 19, and 20, the valve seat rings 18 and 19 fitted to the same type of ports, that is, the main intake port 11 and the auxiliary intake port 12, are located in a large area squish area 8a located far from the spark plug 14. Sub-intake port 12 located in the
The press-fit length l ₁ of the valve seat ring 19 is made larger than the press-fit length l ₂ of the valve seat ring 18 of the port 11 disposed on the side closer to the spark plug 14 . For example, when the press-fit length of the valve seat ring 18 of the main intake port 11 is 6.5 mm, the press-fit length of the valve seat ring 19 of the auxiliary intake port 12 is about 50% longer, or 9.5 mm. In addition,
Valve seat ring 1 for intake ports 11 and 12
The valve seat ring 20 of the exhaust port 13 is made of a sintered alloy since it is exposed to the high temperature of the exhaust gas.

The piston combustion chamber recess 6, the piston top surface 7, the cylinder head combustion chamber recess 9, the cylinder head lower surface 10, the lower surface of the main intake valve 15, the lower surface of the sub-intake valve 16, the lower surface of the exhaust valve 17, and the valve seat rings 18, 19. , 20 lower end surface, cylinder bore 2
A combustion chamber 21 is configured by the inner surface.

In the combustion chamber of the internal combustion engine configured as described above, the air-fuel mixture is mainly introduced from the main intake port 11 in the low speed range, so that a strong circumferential vortex flow is generated in the combustion chamber 21. At high output, the proportion of air-fuel mixture introduced by the sub-intake port 12 increases, ensuring high output. Furthermore, at the end of the compression stroke, the air-fuel mixture in the squish area 8 between the piston top surface 7 and the cylinder head bottom surface 10 is pushed out into the space between the piston combustion chamber recess 6 and the cylinder head combustion chamber recess 9, and is moved in the vertical direction. This creates eddy currents and the flows collide with each other, generating many minute turbulences. Combustion is stabilized by these swirls and turbulence, and the lean limit of the mixture can be improved, so by making the mixture leaner, fuel efficiency can be improved. That is, by simultaneously establishing a wedge-type combustion chamber with a squeeze area and a dual intake system using a Siamese port in a small bore engine, fuel efficiency can be improved through an improvement in lean limit. However, on the other hand, this is
In particular, flame propagation to the squish area 8a, which has a large area on the opposite side of the spark plug 14, is poor and end gas is likely to be generated in this area 8a, and the temperature of the end gas increases due to the large compression ratio. As mentioned above, another problem arises in that knocking is more likely to occur, and this problem is suppressed in the present embodiment as follows.

The surfaces forming the wall surface of the squishing area 8a with a large area where end gas is likely to be generated, namely the flat top surface 7 of the piston 3 on the lower surface, the lower surface 10 of the cylinder head on the upper surface, and the sub-intake valve 16 forming the squishing surface. Among the lower end surfaces of the valve seat ring 19 of the auxiliary intake port, the surfaces that are particularly likely to become hot are the lower end surface of the valve seat ring 19 and the lower surface of the auxiliary intake valve 16. The heat from the valve seat ring 19 is transferred to the cooling water in the water jacket via the cylinder head 4, and some of the heat from the auxiliary intake valve 16 is transferred from the umbrella to the valve seat ring 19, and the rest is transferred from the stem to the cylinder head 4. The heat is transferred to the cooling water in the water jacket through the heat transfer path, but since there is a heat transfer resistance part in the press-fit contact area between the outer surface of the valve seat ring 19 and the cylinder head 4 in the middle of the heat transfer path, the temperature will rise. Become. Valve seat ring 1
If the outer diameter of the valve seat ring 19 is Do and the inner diameter is Di, the area of the heat receiving part is expressed as 1/4π (Do ² - Di ² ), and the heat transfer area of the press-fitting part is expressed as πDol _1. Therefore, the valve seat ring 19 The temperature rise of the auxiliary intake valve 16 increases as the area of the heat receiving part increases, and decreases as the heat transfer area of the press ^{- fitting} part _increases . The ratio of Di is almost constant, and if the parameter related to the diameter is D, it increases according to D/l ₁ . In the device of this embodiment, the auxiliary intake port provided in the squishy area 8a where end gas is likely to be generated has a smaller diameter than the main intake port, so D is small and the press-fit length of the valve seat ring 19 is Since D/l ₁ is larger than the press-fit length l ₂ of the valve seat ring 18 of the main intake port, D/l ₁ is significantly reduced compared to the main intake port side, and therefore the wall surface The temperature rise will be suppressed to a small level. For this reason, the sub-intake valve 1
This prevents the temperature of the lower surface of the valve seat ring 19 and the lower end surface of the valve seat ring 19 from becoming abnormally high and becoming an ignition source, thereby preventing knocking. Suppression of knocking makes it possible to increase the compression ratio and increase the ignition advance angle, and by increasing the compression ratio, it becomes possible to promote lower fuel consumption. That is, in the device of this embodiment, fuel efficiency can be effectively and comprehensively improved through both making the mixture lean through stable combustion and increasing the compression ratio through suppressing knocking.

In the above explanation, the increase in the press-fit length of the valve seat ring was explained using the case of an intake port as an example, but in a case where there are two exhaust ports such as a 4-valve engine, it is far from the spark plug and the ignition port is The press-fit length of the valve seat ring that is fitted into the exhaust port in the area of the squeezing area that is larger than the area of the squeezing area that is closer to the spark plug is the same as the valve seat ring that is fitted on the exhaust port that is closer to the spark plug. Even if the length is longer than the press-fit length of the seat ring, the same effects as described above can be obtained and are included in the present invention.

As described above, when using the combustion chamber of the internal combustion engine of the present invention, it is possible to suppress the abnormal temperature rise of the wall surface near the port, which is the part where end gas is likely to be generated, and therefore the occurrence of knocking. Since it is possible to suppress this, it is possible to achieve the effect of achieving lower fuel consumption and lower emissions of internal combustion engines for vehicles such as automobiles.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the combustion chamber of the internal combustion engine of the present invention;
2 is a cross-sectional view taken along the line --- in FIG. 1, and FIG. 3 is a cross-sectional view taken along the --- line in FIG. 1... Cylinder block, 2... Cylinder bore, 3... Piston, 4... Cylinder head, 6
... Piston combustion chamber recess, 7 ... Piston top surface, 8 ... Squeeze area, 8a ... Large area squish area, 9 ... Cylinder head combustion chamber recess, 10 ... Cylinder head bottom surface, 11
...Main intake port, 12...Sub-intake port, 13
...Exhaust port, 14...Spark plug, 15...
Main intake valve, 16...Sub-intake valve, 17...Exhaust valve,
18... Main intake port valve seat ring, 1
9... Sub-intake port valve seat ring, 20
...Exhaust port valve seat ring, 21...
combustion chamber.

Claims (1)

[Claims] 1 The spark plug is provided offset from the cylinder bore center axis in the cylinder bore radial direction, and the spark plug is ignited in a squish area defined vertically by the flat part of the top surface of the piston and the flat part of the lower surface of the cylinder head in the combustion chamber. It has a squish area at a position far from the spark plug that has a larger area than the squish area near the spark plug, and is provided with at least two intake ports or exhaust ports, one of which is used for ignition. A cylinder of a valve seat ring of a port located in a part of the large-area squeezing area far from the spark plug in a combustion chamber of an internal combustion engine that is disposed in the squeezing area of the large area that is far from the spark plug. A combustion chamber of an internal combustion engine characterized in that the length of the press fit into the cylinder head is greater than the length of the press fit into the cylinder head of a valve seat ring of a port of the same type that is located closer to the spark plug. .