JPS5947134B2 - Gas-injected multi-cylinder engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of a lean-rich engine, particularly for automobiles, constructed for the purpose of purifying exhaust gas.

That is, the above lean rich engine, for example,
To explain the four-cylinder engine shown in the figure, a rich mixture with an air-fuel ratio of about 10 to 14 and a lean mixture with an air-fuel ratio of about 16 to 20 are supplied to each two cylinders separately.
A rich mixture supply device 05 is connected to the cylinders 03 and 02, a lean mixture supply device 06 is connected to the cylinders 03 and 04, and an exhaust passage (not shown) is connected to each of the cylinders 01 to 0.
This configuration is equipped with an exhaust gas re-combustion device that mixes and re-combusts the exhaust gas led from No. By supplying a sufficiently lean mixture to each cylinder, the NOx concentration in the exhaust gas is reduced, and a large amount of unburned gas HC is discharged from the rich mixture combustion gas m01,02.
CO is caused by the large amount of residual oxygen emitted from the lean mixture combustion gas m03,0.4, and the exhaust gas is regenerated, especially without supplying a large amount of secondary air to the exhaust system, or without supplying any secondary air at all. The CO and HC concentrations in the exhaust gas are reduced by re-burning in the combustion device, and the decrease in output or instability that occurs in the lean mixture combustion cylinders 03 and 04 occurs in the rich mixture combustion cylinders 01 and 02. The effect is that a relatively stable output can be obtained, which is compensated for by the stable high output that is generated.

However, in the above-mentioned conventional lean-rich engine, due to the lean combustion limit, the air-fuel mixture supplied to the lean-burn cylinders 03 and 04 is extremely lean due to a misfire, for example, when the air-fuel ratio is 20 or more. This results in a decrease in output and cannot be made too thin. Therefore, the amount of oxygen in the reaction chamber of the exhaust gas re-combustion device installed in the exhaust system is likely to be insufficient, and in order to achieve complete combustion of unburned gas, Secondary air is required to compensate for this, and a secondary air supply such as an air pump, etc.
In addition, the lean mixture combustion cylinders 03 and 04 require a high-energy ignition device such as a transistor 4 igniter with high ignition performance to prevent a drop in output and obtain stable output. However, the disadvantage is that the special provision of these devices makes them expensive, and furthermore, the mixture supplied to the lean mixture combustion cylinders 03 and 04 cannot be made sufficiently lean as described above, so it is difficult to reduce NOx and improve fuel efficiency. The disadvantage is that there are limits to

The present invention was proposed in order to solve the above-mentioned drawbacks of the conventional lean-rich engine. The combustion chamber forming wall of the lean mixture combustion cylinder is provided with an injection hole that opens toward the vicinity of the spark gap of the ignition plug placed in the combustion chamber. It is arranged close to the spark gap and connected to a gas supply source via a gas passage, and the gas passage is interposed with an auxiliary intake valve that opens and closes the passage. The gist of this invention is a gas injection multi-cylinder engine characterized by injecting gas into a combustion chamber using the generated negative pressure.

According to the present invention, gas is powerfully injected from the injection hole as a jet stream due to the high negative pressure generated in the combustion chamber of the lean-mix combustion cylinder during the intake stroke, and this jet stream is generated around the spark gap. In addition to scavenging the fuel gas and improving ignitability, it also generates strong swirl and turbulence within the combustion chamber, and these swirls and turbulence moderately mix the jet gas and the air-fuel mixture taken in from the intake port to form an air-fuel mixture. In addition to being diluted, it is thought to remain even when ignited by the spark plug, helping flame propagation after ignition, and as a result, the combustion speed of the lean mixture supplied to the lean combustion cylinder increases, resulting in lean combustion. The limits are extended,
Fuel efficiency is improved.

Therefore, it becomes possible to supply a sufficiently lean mixture to the lean mixture combustion cylinder, which increases the effect of reducing NOx and improving fuel efficiency, and also increases the amount of residual oxygen in the exhaust gas discharged from the lean mixture combustion cylinder. The unburned gas discharged from the rich mixture combustion cylinder can be sufficiently purified without providing a secondary air supply device, and the improved ignition performance eliminates the need for a particularly expensive high-energy single ignition device.

The gas ejected from the injection hole is preferably air, but may be a mixture of fuel and air, or may be exhaust gas from the engine itself.

When the gas is air, the gas source is the atmosphere; in the case of a mixture, a vaporizer is suitable; and in the case of exhaust gas, an exhaust manifold is a suitable gas source.

Next, the present invention will be explained in detail with reference to an embodiment shown in the drawings.

In the four-cylinder four-stroke spark ignition engine shown in FIGS. 2 and 3, the firing order of each cylinder of the engine body 5 is cylinder 1 - cylinder 3 - cylinder 4 - cylinder 2.

Of the four cylinders, cylinder 1 and cylinder 4 are configured as rich mixture combustion cylinders, and cylinder 1.4 is connected to a rich mixture supply device 8 via an intake port 6 and an intake pipe 7, Cylinder 2 and cylinder 3 are configured as lean mixture combustion cylinders, and cylinders 2 and 3 have an intake port 6 and an intake pipe 9.
It is connected to the mixture supply device 10 for lean mixture via.

The exhaust port 11 of each cylinder is connected to a thermal reactor 13 via an exhaust pipe 12, and the thermal reactor 1
3 communicates with an exhaust manifold pipe 14 which is open to the atmosphere via a muffler (not shown).

In addition, an intake port 6 is provided on the wall surface of each hemispherical combustion chamber of the cylinder head 16 forming the cylinder head 15 of each cylinder 1 to 4.
The opening 6ζ of the exhaust port 11 and the spark plug 17 are arranged, and the cylinders 2 and 3 are provided with an opening near the spark gap 18 of the spark plug and an injection valve directed near the spark gap 18. A hole 19 is formed, and the injection hole 19 is connected to an air passage 21 formed in the cylinder head 16 via an auxiliary intake valve 20 that is a mushroom valve.

The cylinder head 16 is press-fitted into the valve guide 22 into which the auxiliary intake valve 20 is slidably fitted, and the communication between the injection hole 19 and the air passage 21 is established through the auxiliary valve seat 23 formed at the tip of the pulp guide 22. The air is shut off when the umbrella portion of the intake valve 20 comes into contact with it.

The air passage 21 is connected to an air pipe 24.
4 is connected to the clean side of an air cleaner (not shown).

In this embodiment, both the air-fuel mixture supply devices 8 and 1 are conventional carburetors, and each of the two vaporizers produces a custom-made air-fuel mixture.

The main intake valve 26 that opens and closes the opening 6' of the intake port 6 is a rocker arm 28 that is fitted onto a rocker shirt 27 and swings.
The auxiliary intake valve 20 is driven by the cylinder head 1.
The rocker arm 28 is driven by a rocker arm 30 that swings around a ball stud 29 protruding from the
The rocker arm 30 contacts the cam 31 provided on the camshaft 33 and swings in response to the rotation of the cam 310, and the rocker arm 30 contacts the cam 32 provided on the camshaft 33 and swings in response to the rotation of the cam 320. oscillate.

Note that the valve opening period 1 of the auxiliary intake valve 20 is set to be the same as or within the same period as the valve opening period of the main intake valve 26.

In addition, in FIG. 3, 25 is a piston, 34 is a cylinder block, 35 is a valve guide of the main intake valve 26, and 36 is a cylinder block.
, 37 are valve springs, 38° and 39 are spring seats, and 40 is an adjustment screw.

In addition, in this embodiment, especially in a medium-high load operation region where the amount of NOxΩ generation is large, the air-fuel ratio of the air-fuel mixture generated by the air-fuel mixture supply device 8 becomes a rich air-fuel mixture within the range of 10 to 14. The air-fuel ratio of the air-fuel mixture generated by the air-fuel mixture supply device 10 tL after being mixed with the air supplied from the injection holes 12 is a lean air-fuel mixture with an overall air-fuel ratio within the range of 18 to 24. During idling operation, where the amount of NOx generated is relatively low, and in the low-load operation range, air-fuel mixture adjusted to the stoichiometric mixture ratio or richer is supplied to all cylinders 1 to 4. In the operating state where the throttle valve is fully open or close to it, that is, in the full load operating range, the conventional enrichment mechanism attached to the air-fuel mixture supply device 8 j 10 operates to supply a rich air-fuel mixture to all cylinders.

According to the above configuration, when the main intake valve 26 and the auxiliary intake valve 20 open during medium to high load operation, the air-fuel ratio generated by the air-fuel mixture supply device 8 is supplied to the cylinders 1 and 4 to a richness of about 10 to 14. The air-fuel mixture is supplied via the intake pipe 7 and the intake port 6, while the air-fuel mixture generated by the air-fuel mixture supply device 10 is supplied to the cylinders 2 and 3 via the intake pipe 9 and the intake port 6. The high negative pressure generated in the combustion chamber 15 causes the injection hole 1 to flow through the air passage 21 and the air pipe 24.
Spark plug 1T has a more directional and powerful jet of air than 9.
This jet is injected toward the vicinity of the spark gap 18, and this jet gives a strong swirl or turbulence to the air-fuel mixture taken into the combustion chamber 15, and is well mixed with the air-fuel mixture, resulting in an air-fuel ratio of about 18 to 24. This results in a lean mixture.

Since the air-fuel mixture supplied to the cylinders 1 and 4 is a rich air-fuel mixture with an air-fuel ratio of about 10 to 14, the ignition combustibility is good, stable high output is obtained, and the amount of NOx generated is small.

On the other hand, the air-fuel mixture supplied to the cylinders 2 and 3 is mixed with the air from the injection hole 19 and becomes a flame-retardant lean air-fuel mixture with an air-fuel ratio of about 18 to 24. The burnt gas that remains in the air is scavenged, improving ignitability, and strong swirl and turbulence are imparted to the air-fuel mixture, increasing the combustion rate, resulting in good combustibility and relatively stable output. is obtained, fuel consumption is reduced, and the amount of NOx generated is also reduced due to lean combustion.

By improving the combustion speed and ignitability of the lean burn in the cylinders 2 and 3, the lean burn limit is extended, especially in the cylinders 12 and 3.
! If a lean mixture with an air-fuel ratio of 20 or more is combusted in a cylinder, fuel consumption will be greatly reduced, and the amount of excess oxygen will increase, resulting in a large amount of residual oxygen in the exhaust gas. , 4, the amount is such that a large amount of unburned gases HC and CO discharged from the gases HC and CO can be completely burned by reburning.

Therefore, without supplying secondary air to the exhaust system, the unburned gas discharged from each cylinder 1 to 4 in the thermal reactor 13 is almost completely combusted by the residual oxygen in the exhaust gas, and the amount of HC and CO emissions is reduced. reduced.

In this case, due to the exhaust gas containing a large amount of unburned gas discharged from the cylinders 1 and 4, the temperature of the thermal reactor 13 becomes higher than the operating temperature immediately after starting, and the temperature of the thermal reactor 13 is prevented from decreasing, making it relatively This allows for sufficient re-combustion without the need for expensive catalytic converters that operate at low temperatures.

All cylinders 1 to 4 during idle link and low load operation
The air-fuel mixture with the best combustibility, which is at or slightly enriched at the stoichiometric air-fuel ratio, is supplied to the engine, which improves combustibility that would otherwise deteriorate due to deterioration of intake efficiency or a decrease in combustion chamber wall temperature, resulting in stable output. obtained, drivability is improved, and
During full-load operation, the enrich mechanism operates to supply rich air-fuel mixture to all cylinders, preventing a drop in maximum output and ensuring good acceleration performance.

As is clear from the above, according to the present invention, the output decreases,
While minimizing the deterioration of drivability and fuel efficiency, the emissions of harmful gases such as NOx, HC, and Co are effectively reduced. This eliminates the need for other devices, resulting in lower costs.

In the above embodiment, a carburetor was used as the air-fuel mixture supply device, but the present invention applies to either the so-called premixing type in which fuel is injected into the intake passage or the so-called direct injection type in which fuel is injected directly into the cylinder. It goes without saying that inventions can be adopted.

Further, the internal combustion engine to which the present invention can be applied is not limited to the above-mentioned 4-cylinder 4-cycle engine,
The present invention can also be applied to other engines such as multi-cylinder engines other than 4-cylinder engines and 2-stroke engines.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a conventional lean rich engine;
The figure is a plan view schematically showing an embodiment of the present invention, and FIG. 3 is a longitudinal sectional view of the embodiment. 1. 2, 3, 4...Cylinder, 5...Engine body, 6...Intake boat? , 9...
...Intake pipe, 8,10...Mixture supply device, 1
1...Exhaust port, 12...Exhaust pipe,
13... Thermal reactor, 15...
Combustion chamber, 16...Cylinder head, 17...
... Spark plug, 18 ... Spark gap, 19 ... Injection hole, 20 ... Sub-intake valve, 21 ... Air passage, 24 ... ... air pipe,
26... Main intake valve.

Claims (1)

[Claims] 1. Multiple cylinders with intake ports, exhaust ports, and spark plugs are divided into lean mixture combustion cylinders and rich mixture/snoring cylinders, and the combustion chamber forming wall of the lean mixture combustion cylinder is arranged within the same combustion chamber. An injection hole is provided that opens toward the vicinity of the spark gap of the ignition plug, and the injection hole is disposed close to the spark gap of the ignition plug and is connected to a gas supply source via a gas passage. The gas injection type multi-cylinder is characterized in that the gas passage is provided with an auxiliary intake valve for opening and closing the passage, and gas is injected from the injection hole into the combustion chamber by negative pressure generated in the combustion chamber during the intake stroke. engine.