JPH0932559A - Cylinder head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance an air utilization factor, and prevent generation of soot by forming a base in the shape of covering the tip of a fuel injection valve by projecting it to the combustion chamber side by forming a central part in a projecting shape, and boring connecting holes of the same number with the nozzle port number in the base so that its inside diameter does not hinder fuel spray in the same direction with the injecting direction of fuel. SOLUTION: An air chamber 1a is arranged around a fuel injection valve 4. A base 5 having connecting holes 5a is provided on the tip of the fuel injection valve 4. These connecting holes 5a are constituted in the same number in the same direction with fuel spray 4a injected from the fuel injection valve 4, and the connecting holes 5a are formed in an inside diameter of not hindering fuel spray. High pressure fuel is injected into a combustion chamber 2a through the connecting holes 5a from the fuel injection valve 4, and ignition combustion is performed, and pressure of the inside of the combustion chamber 2a and the air chamber 1a increases, and when a piston 2 is further lowered, air is injected into the combustion chamber 2a from the air chamber 1a. Therefore, turbulence is cuased in the combustion chamber 2a, and combustion is promoted, and generation of soot can be prevented.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cylinder head applied to a diesel engine.

[0002]

2. Description of the Related Art FIG. 3 shows a sectional view of a combustion chamber including a conventional cylinder head. In the figure, 1 is a cylinder head,
Reference numeral 2 is a piston provided with a combustion chamber 2a. 3 is a cylinder, 4 is a fuel injection valve, and 4a is a fuel spray. As the engine rotates and the piston 2 rises from the bottom dead center, the air in the combustion chamber 2a composed of the cylinder head 1, the piston 2 and the cylinder liner 3 is compressed, and when the piston 2 comes to the top dead center position, compression occurs. Maximum pressure.

On the other hand, high-pressure fuel is sent from a fuel injection pump (not shown) to the fuel injection valve 4 in synchronism with the rotation of the engine, and the fuel is injected into the combustion chamber 2a from the injection port at the tip.
The injected fuel self-ignites and burns after the ignition delay period, and the pressure in the combustion chamber 2a rises and pushes down the piston 2, and at the same time, the pressure in the combustion chamber 2a also falls.

[0004]

The fuel spray 4a injected into the combustion chamber 2a at the top dead center is mixed with the air in the combustion chamber 2a and self-ignited to burn. At this time, if the mixture of fuel and air is poor, combustion will deteriorate and soot will occur.
It is necessary to mix the fuel spray and the air in the combustion chamber 2a well. An object of the present invention is to provide a cylinder head having a good air utilization rate.

[0005]

The cylinder head of the present invention is a diesel engine having one fuel injection valve at the center of the cylinder head on the cylinder side, and an air chamber 1a is provided around the lower portion of the fuel injection valve of the cylinder head. The mouthpiece 5 is attached so as to form the shape of the mouthpiece, and the mouthpiece has a convex shape at the center thereof so as to project toward the combustion chamber to cover the tip of the fuel injection valve, and the mouthpiece has the same number as the number of the nozzles. The communication hole 5a is characterized in that it is formed in the same direction as the fuel injection direction and the inner diameter thereof is thick enough not to hinder the fuel spray.

In the engine, compressed air in the combustion chamber during the compression stroke is introduced into the air chamber 1a provided in the cylinder head through the communication hole 5a. On the other hand, the fuel spray injected into the combustion chamber self-ignites and begins to burn. Even when the piston begins to descend, air flows into the air chamber 1a while the pressure in the combustion chamber 2a is higher than the pressure in the air chamber 1a, but when the pressure in the combustion chamber 2a falls below the pressure in the air chamber 1a. Air and gas flow out from the communication hole 5a of the air chamber, and this flow promotes mixing of unburned gas and air, and good combustion is obtained.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The main point of the present invention is that in a diesel engine having a fuel injection valve 4 at the center of the cylinder head 1 on the cylinder side, an air chamber 1a is formed around the fuel injection valve, and the injection valve is formed. Is fitted with a base 5 having a communication hole 5a having an inner diameter which does not hinder the fuel spray, and the pressure of the combustion chamber is higher than that of the air chamber 1a during the compression stroke and at the beginning of ignition and combustion. At high pressure, the air in the combustion chamber flows back into the air chamber 1a,
In the subsequent expansion stroke, a gas containing fresh air as a main component is jetted from the air chamber 1a into the combustion chamber, and the turbulence in the combustion chamber due to the jetted air provides a diesel engine which is particularly improved in combustion in the latter stage of combustion. .

FIG. 1 is a sectional view of a combustion chamber according to a first embodiment of the present invention. In the figure, reference numeral 1 is a cylinder head in which an air chamber 1a is provided around the fuel injection valve, and a base 5 having a communication hole 5a is provided at the tip of the fuel injection valve 4.
The communication hole 5a is provided with the fuel spray 4 injected from the fuel injection valve 4.
The same number as a is formed in the same direction. The communication hole has an inner diameter that does not hinder the fuel spray.

Next, the operation of this embodiment will be described. As the piston 2 rises in the compression stroke, the air in the combustion chamber 2a composed of the cylinder head 1, the piston 2 and the cylinder liner 3 rises as shown by the solid line P _2a in FIG.
Along with this, the pressure in the air chamber 1a also gradually rises as indicated by the broken line P _1a due to the compressed air flowing in through the communication hole 5a. At this time, since the diameter of the communication hole 5a is much smaller than the inner diameter of the piston 2, a throttling action occurs.

As described above, the pressure in the air chamber 1a is lower than the pressure in the combustion chamber 2a during the compression stroke, but when the piston passes the top dead center and enters the expansion stroke and the piston 2 descends, the pressure in both chambers is reduced. Since the rotation is reversed as shown in FIG. 2, the air from the air chamber 1a is ejected into the combustion chamber 2a through the communication hole 5a.

On the other hand, in synchronization with the rotation of the diesel engine, high-pressure fuel from a fuel injection pump (not shown) is injected from the fuel injection valve 4 into the combustion chamber 2a through the communication hole 5a during the fuel injection period b shown in FIG.

The injected fuel has an ignition delay period (see FIG. 2).
Ignition and combustion after C), the pressure P _2a of the combustion chamber 2a rises, which as it rises as the pressure P _1a of the air chamber 1a is also shown in FIG. However, when the piston 2 further descends, air is jetted from the air chamber 1a to the combustion chamber 2a as described above. This jet of air causes turbulence in the combustion chamber to promote combustion, and particularly improves combustion in the latter stage of combustion.

[0013]

Since the diesel engine of the present invention is constructed as described above, the fresh air in the air chamber, which has mainly flown in when the piston rises, is jetted into the combustion chamber from the connecting hole as the piston descends, and the unremoved air in the combustion chamber remains. It is possible to provide a low-pollution engine that sufficiently mixes with combustion gas to improve the combustion state, promotes combustion due to turbulence generated in the combustion chamber particularly in the latter stage of combustion, and causes less soot and the like.

[Brief description of drawings]

FIG. 1 is a sectional view of a combustion chamber according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a pressure change state of a combustion chamber and an air chamber with respect to a crank angle.

FIG. 3 is a diagram corresponding to FIG. 1 of a conventional example.

[Explanation of symbols]

1 ... Cylinder head, 1a ... Air chamber, 2 ... Piston, 2
a ... Combustion chamber, 3 ... Cylinder liner, 4 ... Fuel injection valve, 4
a ... Fuel spray, 5 ... Clasp, 5a ... Communication hole.

Claims (1)

[Claims] 1. A central portion of a cylinder head on the cylinder side
In a diesel engine with individual fuel injection valves,
A base (5) is mounted around the lower portion of the fuel injection valve of the cylinder head so as to form an air chamber (1a). The base of the base has a convex shape and protrudes toward the combustion chamber to form a fuel injection valve. In addition to having a shape to cover the tip, the mouthpiece was provided with the same number of communication holes (5a) as the number of the nozzles in the same direction as the fuel injection direction and the inner diameter of which was so large as not to hinder the fuel spraying. Cylinder head characterized by that.