JPS5930893B2 - Air-injected multi-cylinder internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a multi-cylinder internal combustion engine for automobiles constructed for the purpose of purifying exhaust gas.

In general, automobile internal combustion engines are designed so that the mixture ratio of the amount of air and fuel supplied to each cylinder (hereinafter referred to as the air-fuel ratio) is as uniform as possible, but at partial load, the fuel consumption is at its minimum. The NO in the exhaust gas is
x concentration increases.

Furthermore, at high loads when the throttle valve opening is close to fully open, it is necessary to supply a rich air-fuel mixture with a low air-fuel ratio in order to maintain high output, which increases the concentration of CO and HC, which are unburned gases, in the exhaust gas.

Furthermore, even when the engine is running at low speeds, the air-fuel mixture may undergo incomplete combustion within the cylinder due to other reasons such as the temperature of the inner wall of the cylinder being low.
Harmful exhaust gas containing large amounts of unburned components such as CO and HC is generated.

As is well known, the concentrations of CO and HC in the exhaust gas can be reduced by supplying sufficient air and burning them efficiently at high temperatures, but as for NOx,
The higher the combustion temperature, the higher the NOx concentration.

Therefore, in order to reduce this NOx, it is necessary to lower the combustion temperature.

That is, a typical internal combustion engine has the following three characteristics.

(1) NOx concentration is low at rich air-fuel ratios and lean air-fuel ratios (2) CO and HC concentrations are high at rich air-fuel ratios (3) CO and HC concentrations are high at lean air-fuel ratios if there is no misfire. Focusing on the three points mentioned above, where the oxygen concentration is low and the oxygen concentration is high, there is a rich mixture combustion cylinder (hereinafter referred to as R cylinder) that is supplied with a rich mixture with an air-fuel ratio of 11 to 13, and a lean mixture with an air-fuel ratio of 17 to 20. Internal combustion engines have already been proposed that have lean-burn cylinders (hereinafter referred to as lean cylinders) that are fed with a mixture.

In this type of internal combustion engine, the rich air-fuel mixture is incompletely combusted in the R cylinder, so the NOx concentration is low, while the CO and HC concentrations are high.

Also, in the L cylinder, the lean mixture can be completely combusted, so CO
and HC concentration is low, NOx concentration is also low, and oxygen concentration in exhaust gas is high.

When the combustion gases discharged from the solid cylinder are mixed, the high concentration CO and HC discharged from the R cylinder are oxidized by the combustion gas having a high oxygen concentration discharged from the L cylinder, and the CO and HC concentrations are reduced. It is something that decreases.

Therefore, the combustion gas discharged from the engine contains Co, HC,
and NOx will all be reduced.

However, this type of internal combustion engine uses a mixture with an air-fuel ratio that deviates to the rich side and the lean side, respectively, compared to the air-fuel ratio that produces maximum output, so the output is insufficient especially during high-load operation This has the drawback of deteriorating performance and also deteriorating fuel efficiency during high-speed cruising.

Particularly during the above-mentioned high-load operation, if the output is not sufficient, avoidance operations to prevent accidents cannot be performed, which is even dangerous.

In addition, due to the lean burn limit, the air-fuel mixture supplied to the L cylinder cannot be made too lean, for example, if the air-fuel ratio is over 20, it will cause an extreme drop in output due to misfire, and therefore the exhaust system The amount of oxygen in the reaction chamber of the exhaust gas re-combustion device installed in the An air supply device must be provided,
In addition, the L cylinder requires a high-energy ignition device such as a transistor eveninger with high ignition performance in order to prevent a drop in output and obtain a stable output, and the disadvantage is that the special provision of these devices makes them expensive. Furthermore, since the air-fuel mixture supplied to the L cylinder cannot be made sufficiently thin as described above, there is a drawback that there is a limit to the reduction of NoX and the improvement of fuel efficiency.

The present invention has been proposed in view of the above, and includes a spark gap of an ignition plug facing into each combustion chamber of a plurality of cylinders into which intake air is introduced and distributed via an intake passage.
An injection hole for injecting air in a set direction within the combustion chamber is provided near the spark gap, and an air passage connected to the injection hole via an air valve is provided, and the air passage is connected to the combustion chamber of a specific cylinder. The gist of the present invention is an air injection multi-cylinder internal combustion engine characterized in that an air passage communicating with the injection holes provided therein is interposed with a control valve for opening and closing the air passage.

According to the present invention, air is powerfully injected from the injection hole due to the high negative pressure generated in the combustion chamber during the intake stroke, and this jet stream scavenges the burnt gas around the spark gap and improves ignition performance. At the same time, strong swirl and turbulence are generated in the combustion chamber, and these swirls and turbulence moderately mix the jet air and the air-fuel mixture taken in from the intake port, diluting the air-fuel mixture, and also reduce the amount of water after ignition by the spark plug. It helps flame propagation, and as a result, the combustion speed of the lean air-fuel mixture supplied to the L cylinder in particular increases, extending the lean combustion field of view and improving fuel efficiency.

Therefore, it is possible to supply a sufficiently lean air-fuel mixture to the L cylinder, which increases the effect of reducing NOx and improving fuel efficiency, and increases the amount of residual oxygen in the exhaust gas discharged from the same cylinder.
In particular, the unburned gas discharged from the R cylinder can be sufficiently purified without providing a secondary air supply device, and since the ignitability is improved, there is no need for a particularly expensive high-energy ignition device.

Furthermore, the effects of swirl and turbulence increase the combustion rate and improve output.

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

The ignition order of each cylinder of the four cylinder four thermostat 10 shown in FIGS. 1 to 3 is cylinder 11→cylinder 13→cylinder 14→cylinder 12.

The four cylinders 11 to 14 are each connected to a carburetor 20 via an intake port 16 and an intake pipe 18.
Cylinder 14 is configured as a rich mixture combustion cylinder (hereinafter referred to as R cylinder), and cylinders 12 and 13 are configured as lean mixture combustion cylinders (hereinafter referred to as R cylinder).

The exhaust ports 22 of each cylinder 11 to 14 are connected to a thermal reactor 26 via an exhaust passage 24, respectively.
The Marrif '7ta 26 communicates with an exhaust pipe 28.

Each of the cylinders 11 to 14 formed in the cylinder head 30
A spark gap 36 of a spark plug 34 is arranged in the combustion chamber 32 of the spark plug 34, and an injection hole 38 directed toward the spark gap 36 is bored near the spark gap 36, and the injection hole 38 is a mushroom valve. It is connected to an air passage 42 bored through the cylinder head 30 via an air valve 40 .

Among the air passages 42, the combustion chambers 1 of the L cylinders 12 and 13
The air passage 42 communicating with the injection hole 38 provided in the
It is directly connected to the clean side of an air cleaner (not shown) via an air pipe 44.

The air passage 42 communicating with the injection hole 38 provided in the combustion chamber 14 of the R cylinders 11, 14 is connected to an air cleaner (not shown) via an air pipe 48 in which a control valve 46 (described later) is interposed in the middle. Connected to the clean side.

The main intake valve 50 that opens and closes the intake port 16 is driven by a rocker arm 54 that is fitted onto a rocker shaft 52 and swings, and the sub-intake valve 40 swings around a pole stud 56 that is stuck to the cylinder head 30. The rocker arm 54 contacts a cam 62 provided on a camshaft 60 and is driven by a rocker arm 58 that is
The rocker arm 58 comes into contact with a cam 64 provided on the camshaft 52, and swings in response to the rotation of the cam 64.

The opening period of the sub-intake valve 40 is set to be the same as or within the same period as the opening period of the main intake valve 50.

Further, as shown in FIG. 3, the control valve 46 is operated by a diaphragm device 72 having two chambers 68° 70 separated by a diaphragm 66, and is interposed in the air pipe 48. It is composed of an on-off valve 74.

The chamber 68 is open to the atmosphere through a hole 76, and the chamber 70 is connected to a port formed in the wall of the intake passage slightly upstream of the fully closed position of the throttle valve 78 provided in the carburetor 20. A spring 82 is internally connected to the valve 80 and always biases the on-off valve 74 in the opening direction.

In FIG. 2, 84 is a piston, 86 is a cylinder block, 88 is a valve guide for the air valve 40, 90 is a valve guide for the main intake valve 50, 92.94 is a valve spring, 96.98 is a spring seat, 100 is an adjustment screw.

In addition, in this embodiment, the air-fuel ratio of the air-fuel mixture generated in the carburetor 20 is 18 when the air injected from the injection hole 38 provided in the combustion chamber 32 is mixed in the low to medium load operation region. The fuel-air mixture is set to be a lean air-fuel mixture of .about.24, and in a full-load operating range, a well-known enrichment mechanism (not shown) attached to the carburetor 20 operates to supply a rich air-fuel mixture to all cylinders.

Next, to explain the operation of the control valve 40, the diaphragm device 72 sets a negative pressure in the chamber 70 (for example, a negative pressure of 100
When a negative pressure of #Hg) or more is conducted, the spring 82
The diaphragm 66 descends against the urging force of the on-off valve 74.
closes the air pipe 48.

Therefore, in the idling and nearby operating ranges, the throttle opening is small and the negative pressure generated in the port 80 is small, so the on-off valve 74 is opened by the biasing force of the spring 82.

In addition, in the medium load operating region where the throttle opening is somewhat large, the flow rate of intake air flowing near the port 80 is very fast, and the negative pressure generated in the port 80 exceeds the set negative pressure, so the on-off valve 74 is activated by a spring. It descends against the biasing force of 82, and the air pipe 48 is closed.

Further, in a high-load operation region where the throttle opening is large, the negative pressure generated in the port 80 becomes small again, so the on-off valve 74 is opened.

According to the above configuration, in the idling and operating ranges around idling, the control valve 40 is open, the throttle opening is small, and the throttling action of the throttle valve 78 is large, so that the combustion chamber 32 is not affected by the intake stroke. At times, high negative pressure is generated, and since the clean side of the air cleaner to which each air pipe 42, 4B is connected is at approximately atmospheric pressure, a large amount of air is injected into the combustion chamber 32 of each cylinder 11 to 14 due to the pressure difference. A powerful jet is ejected from the hole 38.

This jet gives a strong swirl or turbulence to the air-fuel mixture taken into the combustion chamber 32, and also mixes well with the air-fuel mixture to produce a lean air-fuel mixture with an air-fuel ratio of about 18 to 24.

This lean air-fuel mixture with an air-fuel ratio of about 18 to 24 is flame retardant, but the jet air scavenges the burnt gas that has accumulated around the spark gap 36, improving ignitability and improving the air-fuel mixture. Strong swirl or turbulence is provided to extend the misfire limit and improve the combustion rate, resulting in lower fuel consumption and less NOx generation due to lean combustion.

Further, since the air-fuel mixture having substantially the same air-fuel ratio is supplied to all cylinders 11 to 14, the output is balanced and the operating state of the engine is stabilized.

In addition, in the medium load operation region, the control valve 40 is closed, air injection into the combustion chambers 32 of the R cylinders 11 and 14 is cut off, and air injection is performed only into the combustion chambers 32 of the L cylinders 12 and 13. It can be done.

As a result, the air-fuel mixture supplied to the R cylinders 11 and 14 becomes a rich air-fuel mixture with a small air-fuel ratio, so that good ignition thermal sintering properties are achieved, stable high output is obtained, and the amount of NOx generated is small.

On the other hand, the air-fuel mixture supplied to the L cylinders 12 and 13 is a lean mixture with a high air-fuel ratio, but the effect of the air injection improves the combustion speed and ignitability of lean burn, extending the lean burn limit. , especially when the air-fuel ratio is 2 in the L cylinder 12.13
If a lean mixture of 0 or more is combusted, fuel consumption will be greatly reduced, and the amount of excess oxygen will increase, resulting in more residual oxygen in the exhaust gas, which will be discharged from the R cylinders 11 and 14. A large amount of unburned gas HC.

CO can be completely combusted by re-combustion.

Therefore, without supplying secondary air to the exhaust system, unburned gas in the exhaust gas discharged from the R cylinders 11 and 14 in the thermal reactor 26 is substantially converted into residual oxygen in the exhaust gas discharged from the L cylinders 12 and 13. After complete combustion, HC
, CO emissions are reduced.

In this case, high output can be obtained by supplying a rich mixture to the R cylinders 11 and 14.
This covers the lack of output in 3, prevents a decrease in engine output, and ensures good acceleration performance.

Furthermore, in the high-load operation region, the control valve 40 is open, but the throttle opening is large, so the throttling action by the throttle valve 78 is small, and the amount of air-fuel mixture supplied from the carburetor 20 is increased. Since the negative pressure within the combustion chamber 32 during the intake stroke approaches atmospheric pressure, the amount of air guided to the injection holes 38, that is, the amount of air injected into the combustion chamber 32 decreases.

Moreover, since the enrich mechanism of the carburetor 20 operates,
A rich air-fuel mixture with a low air-fuel ratio is supplied to each cylinder 11-14.

Therefore, the maximum output is increased, an output suitable for high-load operation can be obtained, and drivability is improved.

As is clear from the above, according to the present invention, emissions of harmful gases such as NOx, HC, and CO can be effectively reduced while minimizing output reduction, deterioration of drivability, and deterioration of fuel efficiency. Furthermore, there is no need for devices such as expensive air pumps, high-energy ignition devices, or catalytic converters, resulting in lower costs.

In the above embodiment, the opening and closing of the control valve 40 was controlled by the negative pressure generated in the port 80, which was formed slightly upstream of the fully closed position of the throttle valve 78, but the opening and closing control method of the control valve 40 was It is not limited to this,
Opening/closing operations similar to those of the above embodiment can also be performed using signals representative of other engine operating conditions such as engine speed, manifold negative pressure, and throttle valve opening.

Further, as an internal combustion engine to which the present invention can be applied, none of the above four
The present invention is not limited to four-cylinder, four-stroke engines, and is fully applicable to other spark-ignition internal combustion engines, such as multi-cylinder engines other than four-cylinder engines, two-stroke engines, and the like.

[Brief explanation of the drawing]

The accompanying drawings show one embodiment of the present invention, and FIG. 1 is a schematic plan view, FIG. 2 is an enlarged view, and FIG. 3 is an enlarged sectional view of the main part. 10...Engine body, 11, 12, 13゜1
4...Cylinder, 16...Intake port, 1
8... Intake pipe, 20... Carburetor, 22
...Exhaust port, 26...Thermal reactor, 30...Cylinder head, 32...
... Combustion chamber, 34... Spark plug, 36...
...Spark gap, 38...Injection hole,
40...Air valve, 42...Air passage,
44.48...Air pipe, 46...Control valve.

Claims (1)

[Claims] 1 The spark gap of the ignition plug faces into each combustion chamber of a plurality of cylinders into which intake air is introduced and distributed via an intake passage, and an injection hole is provided near the spark gap to inject air in a set direction within the combustion chamber. , an air passage connected to the injection hole via an air valve is provided, and control is performed to open and close the air passage connected to the injection hole provided in the combustion chamber of a specific cylinder among the air passages. An air-injection multi-cylinder internal combustion engine characterized by an intervening valve.