JP7260332B2 - Cylinder head with auxiliary combustion chamber - Google Patents

Description

The present invention relates to a cylinder head with an auxiliary combustion chamber.

Exhaust gas regulations have been strengthened for gasoline engines and gas engines, starting with internal combustion engines for automobiles. As one means of complying with this regulation, there is a lean-burn method in which the fuel ratio of the air-fuel mixture is lowered (and the air ratio is increased) for combustion. Regarding this point, conventionally, it has been proposed to ignite the fuel (air-fuel mixture) by providing an auxiliary combustion chamber in the cylinder head and ejecting the flame generated in the auxiliary combustion chamber from the torch portion into the main combustion chamber. ing.

In general, the sub-combustion chamber and the torch section are manufactured as a unit separately from the cylinder head, and this unit is often mounted on the cylinder head. It is disclosed to form the torch part integrally with the cylinder head.

JP-A-53-127928

As described above, the sub-combustion chamber and the torch are generally manufactured as a unit separately from the cylinder head. This is because the sub-combustion chamber and the torch portion reach high temperatures, and the sub-combustion chamber unit is made of a highly heat-resistant material to prevent thermal deformation and erosion. In particular, recent automobile internal combustion engines use aluminum to reduce the weight of the cylinder head, so it is common knowledge that the auxiliary combustion chamber unit is made of special steel or other materials different from the cylinder head. be done.

However, manufacturing the sub-combustion chamber unit separately from the cylinder head raises the problem of increased cost. Moreover, if the cylinder head and the sub-combustion chamber unit are made of different materials, there is a possibility that problems such as thermal strain due to the difference in coefficient of thermal expansion and poor sealing may occur. In addition, variations in quality due to processing errors and assembly errors are unavoidable.

On the other hand, if the sub-combustion chamber and the torch portion are formed integrally with the cylinder head as in Patent Document 1, the cost can be reduced and the problems of seal failure and quality variation can be reduced, but the problem of heat resistance is increased. appear large. Regarding this point, it is conceivable, for example, to make the cylinder head made of cast iron made of special steel. There is also a possibility that the cost will increase compared to the case where is manufactured with a separate member.

The invention of the present application was made in response to such a situation, and aims to provide a technology that allows the auxiliary combustion chamber to be integrated with the cylinder head while the cylinder head is made of a light metal such as aluminum.

The present invention relates to a light metal cylinder head fixed to the upper surface of a cylinder block having cylinder bores formed therein.
"A tubular portion surrounded by a water jacket is integrally formed at a portion concentric with the cylinder bore, and the tubular portion has an auxiliary combustion chamber with an exposed spark plug and a flame ejection hole opening toward the cylinder bore. The torch part having is formed in a vertically continuous state,
The torch portion is formed to have a diameter smaller than that of the sub-combustion chamber and is entirely covered with the water jacket,
The torch portion is surrounded by the outlet portion of the intake port and the inlet portion of the exhaust port, the intake port and the exhaust port are separated from the water jacket by a partition, and the lower end of the water jacket is It's located near the vent ."
It is configured.

Since the torch portion has a smaller diameter than the sub-combustion chamber, the cylindrical portion can be formed to have a different diameter so that the portion where the torch portion is provided has a smaller outer diameter. That is, the torch portion of the tubular portion can be formed as a constricted portion having a diameter smaller than that of the sub-combustion chamber portion.

In the invention of the present application, since the cylindrical portion provided with the sub-combustion chamber and the torch portion is surrounded by a water jacket, high heat resistance can be ensured even if the cylinder head is made of light metal such as aluminum. Further, since the cylindrical portion is formed concentrically with the cylinder bore, the heat generated in the sub-combustion chamber and the main combustion chamber acts evenly on the entire cylindrical portion, thereby preventing or remarkably suppressing the occurrence of thermal strain.

In addition, since the cylindrical portion is formed concentrically with the cylinder bore, the external force (compressive force) caused by the explosion in the main combustion chamber also acts uniformly on the entire circumference of the cylindrical portion. Therefore, it has a structure that is difficult to buckle.

Thus, in the present invention, the cylindrical portion can be cooled by the cooling water of the water jacket, and the strain due to heat and the strain due to explosive force can be suppressed to maintain high strength. Even so, the sub-combustion chamber and the torch portion can be formed in a state of being excellent in durability. In addition, since the sub-combustion chamber and the torch portion are formed integrally with the cylinder head, there is no problem of quality variation due to member processing errors or assembly errors, and quality can be stabilized. Naturally, the problem of seal failure does not occur either.

Therefore, it is possible to reduce the cost by integrating the sub-combustion chamber and the torch portion while reducing the weight by making the cylinder head made of light metal such as aluminum. As a result, it is possible to contribute to cost reduction and fuel efficiency improvement of a lean-burn internal combustion engine with excellent ignition performance and low environmental load.

The torch receives heat from the passage of the flame generated in the sub-combustion chamber and from the combustion in the main combustion chamber, so it is exposed to a severe thermal environment. Since the volume of the water jacket surrounding the torch portion can be increased as much as possible, there is an advantage that the cooling performance of the torch portion can be improved.
In addition, the tip of the torch is exposed to a severe heat environment. The part is well cooled all the way to its tip.

In addition, the cylindrical portion swells and deforms due to the pressing force associated with the explosion in the main combustion chamber. , it is possible to absorb the pressing force due to the explosion in the main combustion chamber while reducing the amount of deformation per unit area. Therefore, the occurrence of strain can be further suppressed.

It is a longitudinal front view of the first embodiment, and is a cross-sectional view taken along the line I-I of FIG. 2(A). (A) is a schematic sectional view taken along line IIA-IIA of FIG. 1, and (B) is a sectional view taken along line BB of (A). It is a vertical front view of 2nd Embodiment. 4 is a sectional view taken along line IV-IV of FIG. 3; FIG.

Next, embodiments of the present invention will be described based on the drawings. This embodiment is applied to an internal combustion engine for automobiles. In the following description, terms such as front-rear and left-right are used to specify directions, and the front-rear direction is the crankshaft center direction, and the left-right direction is the direction perpendicular to the crankshaft center and the cylinder bore centerline. The vertical direction is the axial direction of the cylinder bore. The front view is a state seen from the front and rear directions.

(1) Structure of the First Embodiment As shown in FIG. 3. A piston 4 is slidably disposed in the cylinder bore 1, and a circular main combustion chamber 4a is formed on the top surface of the piston 4. As shown in FIG. Both the cylinder block 2 and the cylinder head 3 are aluminum castings.

In the cylinder head 3, a pair of front and rear intake ports 6 that are opened and closed by an intake valve 5 and a pair of front and rear exhaust ports 8 that are opened and closed by an exhaust valve 7 are formed on the left and right. The valves 5 and 7 are slidably held by a guide cylinder 9 and biased by a spring 10 in the closing direction.

In this embodiment, the main combustion chamber is not formed in the cylinder head 3, but the lower surface facing the cylinder bore 1 is formed flat. However, it is also possible to form a chevron-shaped main combustion chamber on the lower surface of the cylinder head 3 and to incline the intake valves 5 and the exhaust valves 7 with respect to the cylinder bore axis O.

The cylinder head 3 is integrally formed with a cylindrical portion (cylindrical portion) 11 that is concentric with the cylinder bore axis O, and the cylindrical portion 11 is integrally formed with an auxiliary combustion chamber 12 and a torch portion 13 that continues downward. is formed in The torch portion 13 is formed in a constricted portion having a diameter smaller than that of the sub-combustion chamber 12 and has a flame ejection hole 14 opening toward the cylinder bore 1 at its lower end. The flame vent holes 14 are drilled after casting.

As can be understood from FIG. 2(A), the flame ejection holes 14 are formed at four locations facing the valves 5 and 7, but are also formed at four locations facing the front-rear direction and the left-right direction. Alternatively, it may be formed at two locations facing the front-rear direction or the left-right direction. That is, the number and arrangement positions of the flame ejection holes 14 can be set arbitrarily. Moreover, it is also possible to provide an opening in the axial direction (downward).

The circumference of the cylindrical portion 11 is surrounded by a water jacket 15 extending inside the cylinder head 3, and the cylindrical portion 11 is arranged inside the water jacket 15 in a column-like state. Also, the stems of the valves 5 and 7 are arranged inside a columnar boss portion 16 arranged inside the water jacket 15 . Note that the cooling water flows through the water jacket 15 generally in the front-rear direction.

An upward opening hole 17 that is concentric with the cylindrical portion 11 is continuous with the cylindrical portion 11 , and a spark plug 18 is mounted in the upward opening hole 17 so that a spark terminal 18 a faces the auxiliary combustion chamber 12 . A cylindrical portion 19 for forming an upward opening hole 17 is formed in the cylinder head 3 .

As shown in FIG. 2, the tip of a fuel injection injector 20 that injects an air-fuel mixture is exposed in the sub-combustion chamber 12 . The fuel injection injector 20 is arranged on the intake side and at a position higher than the intake port 6, and arranged in an inclined posture that becomes lower toward the tip (it may be arranged in a posture perpendicular to the cylindrical portion 11). ).

Since the pressure of the combustion gas generated in the auxiliary combustion chamber 12 is applied to the tip of the fuel injection injector 20, the fuel injection injector 20 is like a fuel injection injector used in a direct injection type internal combustion engine. A method that does not enter is used.

A holder portion 21 for mounting the fuel injection injector 20 is integrally formed on the cylinder head 3 so as to be continuous with the cylindrical portion 11 . Since the nozzle portion 20a of the fuel injection injector 20 has a small diameter, the holder portion 21 also has a small diameter portion 21a. The cylinder head 3 is also formed with a plate-like holder strut 22 for supporting the holder 21 .

The holder portion 21 may be formed only at the location where the fuel injection injector 20 is arranged. However, dummy strut portions 23 having the same size as the holder strut portion 22 are provided at two front and rear portions and at a portion opposite to the holder strut portion 22 across the cylinder bore axis O. - 特許庁It is preferable to connect each dummy support|pillar part 23 and the cylinder part 11 with a dummy holder part.

(2) Summary In the above configuration, when the mixture is injected from the fuel injection injector 20 into the auxiliary combustion chamber 12 at the beginning of the combustion stroke and ignited by the spark plug 18, the flame is emitted from the flame ejection hole 14 for the main combustion. It jets out into the chamber 4a and ignites the air-fuel mixture that fills the main combustion chamber 4a. As a result, the air-fuel mixture is combusted in the main combustion chamber 4a, and the piston 4 is pushed down by the combustion gas.

The cylindrical portion 11 receives the heat generated in the sub-combustion chamber 12 and the heat generated in the main combustion chamber 4a. There is no accumulation of , and high heat resistance can be secured. Therefore, even if the cylindrical portion 11 is molded integrally with the cylinder head 3 made of aluminum, the cylindrical portion 11 will not be eroded. In other words, the auxiliary combustion chamber 12 and the torch portion 13 can be integrally formed in the cylinder head 3 while ensuring the heat resistance of the tubular portion 11 . Therefore, the cost can be reduced without impairing the functions of the internal combustion engine.

Further, since the cylindrical portion 11 is formed concentrically with the cylinder bore axis O, thermal expansion and contraction can be made uniform over the entire circumference. Therefore, the occurrence of thermal strain can be prevented or significantly suppressed. Although the tip of the torch part 13 is exposed to a severe heat environment, in this embodiment, the water jacket 15 can reach the tip of the torch part 13 because the part of the torch part 13 has a small diameter. Therefore, the torch part 13 is thoroughly cooled down to its tip part.
Since the lower end of the water jacket 15 reaches the tip of the torch portion 13 in this way, the flame ejection hole 14 is close to the lower end of the water jacket 15 . Since the water jacket 15 extends to the tip of the torch portion 13, the water jacket 15 is partitioned from the outlet of the intake port 6 and the inlet of the exhaust port 8 by a partition wall, as shown in FIG.

Further, the explosive force generated in the main combustion chamber 4a acts on the cylindrical portion 11 as an axial compressive force. It exhibits strong resistance to compression without deformation. In addition, although the cylindrical portion 11 receives compressive force and expands and deforms, the torch portion 13, which has a small diameter, hardly expands and deforms greatly at the sub-combustion chamber 12, which has a large outer diameter. Therefore, the amount of deformation per unit area can be suppressed, and high durability can be ensured.

In this way, the auxiliary combustion chamber 12 and the torch portion 13 can be integrated with the aluminum cylinder head 3 while ensuring heat resistance and strength, so that a lean-burn internal combustion engine with a reduced environmental load can be made lighter. It is excellent in fuel efficiency and can be manufactured in a state where costs are suppressed. In addition, since there are no assembly or processing errors, there is also the advantage that quality can be stabilized. The provision of the dummy struts 23 as in the embodiment has the advantage that the fuel injection injectors 20 can be arranged while the deformation of the cylindrical portion 11 is made uniform as much as possible, as described above.

(3). Second Embodiment FIGS. 3 and 4 show a second embodiment. This embodiment has the same basic structure as the first embodiment, but differs from the first embodiment in the arrangement of the spark plug 18 and the manner in which the air-fuel mixture is supplied to the auxiliary combustion chamber 12. there is

That is, in this embodiment, the cylinder head 3 is integrally provided with an upper boss portion 25 that is continuous with the cylindrical portion 11 , and the upper boss portion 25 is provided with a spark plug arrangement hole 26 and a fuel supply hole 27 . A spark plug 18 is mounted in the spark plug arrangement hole 26 and a fuel injection cylinder 29 having an auxiliary valve 28 is mounted in the fuel supply hole 27 . The auxiliary valve 28 has a head portion (valve body) formed at its lower end and is urged in the closing direction by a spring (not shown). Further, the auxiliary valve 28 is driven by an auxiliary cam provided on the intake camshaft.

In this embodiment, since the auxiliary valve 28 is built in the fuel injection cylinder 29, the sub-combustion chamber 12 and the torch portion 13 are formed integrally with the cylinder head 3, and the auxiliary valve 28 driven by the camshaft is installed. can be placed. Therefore, the fuel injection injector 20 of the first embodiment is not required, and distortion of the cylindrical portion 11 can be suppressed accordingly.

As shown in FIG. 4, while the upper boss portion 25 is circular, the spark plug placement hole 26 and the spark plug 18 are formed on the left and right sides, so front and rear dummy holes 30 are formed to reduce distortion. It is designed to prevent occurrence and reduce weight. Note that the spark plug arrangement hole 26 and the spark plug 18 may be arranged back and forth.

Although the embodiments of the present invention have been described above, the present invention can be embodied in various other ways. For example, the shape of the cylindrical portion and the shape of the water jacket can be variously embodied in consideration of the strength, the flow of cooling water, and the like. For example, it is possible to arrange the fuel injection cylinder 29 of the second embodiment concentrically with the cylinder part 11 and arrange the spark plug 18 in a sideways posture like the fuel injection injector 20 of the first embodiment. The cylinder head can also be manufactured from an aluminum alloy, a magnesium alloy, or the like.

The present invention can be embodied in a cylinder head of an internal combustion engine with a secondary combustion chamber. Therefore, it can be used industrially.

1 Cylinder Bore 3 Cylinder Head 4 Piston 4a Main Combustion Chamber 5 Intake Valve 6 Intake Port 7 Exhaust Valve 8 Exhaust Port 11 Cylindrical Portion 12 Sub-Combustion Chamber 13 Torch Portion 14 Flame Ejection Hole 15 Water Jacket 18 Ignition Plug 20 Fuel Injector O Cylinder Bore Axis heart

Claims (1)

A light metal cylinder head fixed to the upper surface of a cylinder block in which cylinder bores are formed,
A cylindrical portion surrounded by a water jacket is integrally formed at a portion concentric with the cylinder bore, and the cylindrical portion has an auxiliary combustion chamber with an exposed spark plug and a flame ejection hole opening toward the cylinder bore. The torch part is formed in a continuous state vertically,
The torch portion is formed to have a diameter smaller than that of the sub-combustion chamber and is entirely covered with the water jacket,
The torch portion is surrounded by the outlet portion of the intake port and the inlet portion of the exhaust port, the intake port and the exhaust port are separated from the water jacket by a partition, and the lower end of the water jacket is located near the vent,
Cylinder head with auxiliary combustion chamber.

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