JPS5933848Y2 - exhaust cleaning engine - Google Patents

Description

[Detailed description of the invention] The present invention is an exhaust purification engine, in particular, the N in the combustion chamber.
The present invention relates to an exhaust purification engine that reduces the production of Ox (nitrogen oxides) as much as possible.

As a means for reducing NOx in engine exhaust gas, an exhaust gas recirculation (EGR) device that recirculates a portion of the exhaust gas into intake air is known.

According to this EGR device, as the EGR rate (the volume ratio of the exhaust gas recirculation amount to the amount of intake air) increases, the NOx reduction effect increases, but the stability of combustion of the intake air-fuel mixture decreases and the combustion time increases. There is a problem that causes a decrease in engine output and fuel efficiency.

According to various experiments conducted by the inventors of the present invention, this problem is mainly due to the following three causes.

That is, (1) the presence of a large amount of recirculated exhaust gas reduces the reliability of ignition of the intake air-fuel mixture by the ignition plug;

(2) Due to the presence of a large amount of recirculated exhaust gas, the ignition delay time of the intake air-fuel mixture becomes longer.

(3) Flame propagation velocity is reduced due to the presence of a large amount of recirculated exhaust gas.

It is.

Therefore, in order to improve the causes of (1), (2), and (3) above, it is necessary to cool the electrode part of the ignition plug by preventing the air-fuel mixture immediately after being sucked into the combustion chamber from hitting the electrode part of the spark plug. In addition, it is important to improve the mixing of the air-fuel mixture by providing a swirl to the intake air and, if necessary, a squirt.

By the way, as a means for imparting a swirl to the intake air as described above, conventional methods include, for example, Utility Model Registration No. 33842.
The one described in Specification No. 4 and the like are known.

This has a swirl-generating projection formed integrally with the cylinder head by casting at the opening of the intake port.

However, in this configuration, the sand core that forms the intake port during casting is provided with a notch corresponding to the protrusion, so the core is likely to break, and the inner peripheral surface of the intake port takes into account casting errors. There are drawbacks such as difficulty in machining in subsequent processes, resulting in a step between the valve seat and the inner circumferential surface of the valve seat, and difficulty in obtaining sufficient strength for the protrusions.

The present invention has been developed in view of the above points.The positional relationship between the intake port and the exhaust port is set to a cross-flow structure, and the ignition plug is provided on the intake port side.In addition, the intake valve seat has an intake drift protrusion to generate an intake vortex. By providing a structure that prevents the air-fuel mixture immediately after being sucked into the combustion chamber from hitting the spark plug electrode, it is possible to prevent problems such as a decrease in engine output and fuel efficiency during exhaust gas recirculation, as well as to prevent the above-mentioned problems. The object of the present invention is to eliminate various drawbacks when a swirl generating protrusion is provided integrally with a cylinder head.

Next, one embodiment of the present invention will be described.

In FIGS. 1 to 3, 1 is a cylinder block, 2 is a cylinder block, and 2 is a cylinder block.
is a cylinder head, 3 is a piston, and a combustion chamber 4 defined by the cylinder block 1, cylinder head 2, and piston 3 has an intake port 5 and an exhaust port 6.
is formed with an opening in the cross flow.

A carburetor 8 is attached to the intake port 5 in an intake system 7 shown by phantom lines in FIG.

In order to improve the properties of the air-fuel mixture in the combustion chamber 4, this carburetor 8 makes the air-fuel ratio of the air-fuel mixture close to or richer than the stoichiometric air-fuel ratio in the engine's regular operating range, which corresponds to when a car is running in the city. (For example, A/F=12 to 16).

On the other hand, the exhaust port 6 is connected to the exhaust system 9, and an exhaust port liner 10 is installed inside the exhaust port 6 to suppress the temperature drop of the exhaust gas and promote the purification reaction of the exhaust gas.

In this case, in the case of a multi-cylinder engine, the exhaust port of each adjacent cylinder can be made into a Siamese port to suppress the exhaust temperature drop.

Further, an exhaust gas recirculation device 11 is provided across the exhaust system 9 and the intake system 7.
will be attached.

This exhaust recirculation device 11 is capable of greatly increasing the exhaust recirculation rate by improving the combustion of the air-fuel mixture within the combustion chamber 4, as will be described later.
It is set to be 0 to 40%.

Note that 12 is an intake valve, and 13 is an exhaust valve.

A ring-shaped valve seat 14 made of sintered alloy or the like is press-fitted into the opening of the intake port 5 to the combustion chamber 4, which is a passage for the air-fuel mixture taken into the combustion chamber 4. 14 is integrally provided with a drifting protrusion 15 as an intake vortex generating means.

This drifting protrusion 15 is shown in FIG. 3A. As shown in B, a part of the circumference of the ring-shaped valve seat 14 is formed to protrude toward the center with a thickness t1 and a central angle θ, and the thickness t and central angle θ are determined by the swirl strength, intake resistance, etc. Considering t=2
~4th throat.

It is desirable that θ=90°±30° (the larger θ, the more dog-like the swirl, but also the more dog-like the intake resistance).

Then, when the valve seat 14 is attached to the intake port 5, this flow biasing protrusion 15, as shown in FIG.
The center deflection angle α with respect to the combustion chamber center line L2 in the direction perpendicular to the cylinder row line L1 is α-300±15°, which is the angle at which the most effective swirl can be obtained.

Therefore, due to the deflection protrusion 15, the intake air-fuel mixture is
The swirl occurs in the direction shown by the arrows in Fig. 2 and Fig. 2, respectively, and the mounting position of the ignition plug 16 in the combustion chamber 4 is determined so that the air-fuel mixture immediately after intake does not directly hit the electrode of the ignition plug 16. be.

That is, the ignition plug 16 is provided on the intake port 5 side, that is, on the intake port side with the cylinder row line L1 as a boundary, so as to be located downstream of the air-fuel mixture swirl in the combustion chamber 4.

In this case, intake/exhaust ports 5, 6 within 4° of the combustion chamber
Due to the space for installing the spark plug 16, in order to install the spark plug 16 on the intake port 5 side, the intake/exhaust port 5,
6 will necessarily be arranged in the cross flow as described above.

In an engine having such a configuration, the air-fuel mixture sucked into the combustion chamber 4 is swirled by the drift protrusion 15.
Combined with the air-fuel ratio, the properties of the air-fuel mixture are improved, and since the air-fuel mixture immediately after intake is prevented from directly hitting the electrode of the ignition plug 16, cooling of the electrode portion is prevented and the ignition spark is strengthened.

Therefore, the reliability of combustion ignition 9 prevention of ignition delay,
The flame propagation speed is increased, the combustion characteristics are improved, the engine can be stabilized even with a high rate of exhaust gas recirculation, and NOx can be significantly reduced.

In order to further improve the flame propagation speed, it is preferable to use squish, and a squish region S may be provided as shown in FIG.

In this case, the skin area is 40% relative to the bore cross-sectional area.
An area of less than 100 yen is sufficient.

Furthermore, as a result of forming the drifting protrusion 15 integrally with the valve seat 14 as described above, there is no need to provide a notch in the sand core that forms the intake port 5 when casting the cylinder head 2. Breakage can be prevented, and since the valve seat 14 itself is generally made of a special alloy or the like, sufficient mechanical strength can be ensured for the deflection protrusion 15.

Moreover, the intake port 5 is generally cast with a slightly smaller inner diameter in consideration of casting errors, and then finished by machining to a predetermined dimension. It is possible to smoothly connect the inner periphery of the valve seat 14 and the inner periphery of the intake port 5 without fear of being obstructed by the protrusion 15.

In summary, according to the exhaust purification engine of the present invention, it is possible to generate an intake swirl in the combustion chamber without cooling the spark plug electrode, thereby increasing the strength of the ignition spark and improving the properties of the air-fuel mixture. Therefore, ignition is reliable despite high exhaust recirculation.

By improving the ignition delay and flame propagation speed, it is possible to achieve engine stability and to obtain an exhaust cleaning engine that achieves a significant reduction in NOx, while also preventing breakage of the sand core during cylinder head casting. No problems will occur.

[Brief explanation of drawings]

1 is a partial vertical sectional view of the engine of the present invention, FIG. 2 is a bottom view of the cylinder head, FIG. 3A is a sectional view of the valve seat, and FIG. 3B is a view taken in the direction of arrow A. 2... Cylinder head, 4... Combustion chamber, 5... Intake port, 6... Exhaust port, 8... Carburetor, 10... Port liner, 11... Exhaust recirculation device, 14...
・Valve seat, 15...Difference projection, 16...
...Spark plug, S...Skinsh area.

Claims (1)

[Scope of utility model registration request] The positional relationship between the intake port and the exhaust port is set to a cross 70-structure, and the ignition plug is provided on the intake port side, and an intake drift protrusion is provided on the intake valve seat to generate an intake vortex.
An exhaust purification engine characterized in that the air-fuel mixture is configured so that it does not hit the spark plug electrode immediately after being sucked into the combustion chamber.