JPS5838612B2 - internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement mainly aimed at improving combustion and reducing fuel consumption of an internal combustion engine for automobiles, and in particular, improves the combustion efficiency of an internal combustion engine for automobiles, and in particular, improves the combustion efficiency of an internal combustion engine for use in a vehicle, and in particular improves the combustion efficiency of an internal combustion engine for use in automobiles. This is highly effective in reducing drivability deterioration and fuel efficiency deterioration when supply control, ignition timing retard control is performed, or when an exhaust gas recirculation device is installed that recirculates part of the exhaust gas to the intake system. be.

In other words, it is well known that the amount of NOx, in particular, generated among harmful gases contained in the exhaust gas of automobile internal combustion engines, is approximately proportional to the maximum combustion temperature, and in order to reduce this maximum combustion temperature,
Ignition timing retardation, lean burn, exhaust gas recirculation, etc. have been adopted in various combinations, but in general, they result in poor ignition performance and flame propagation speed, resulting in a decrease in output, deterioration in drivability, or loss of fuel. Problems such as an increase in consumption (hereinafter referred to as fuel efficiency) occur.

Incidentally, the driving ranges that are frequently used in urban driving, where harmful gas emissions are particularly problematic, are idling and low-speed, low-load light-load driving, and it is important to reduce harmful gas emissions in these driving ranges. Therefore, it is necessary to make the harmful gas emission regulation value particularly strict in this region, and for this purpose, it is necessary to eliminate the occurrence of the above-mentioned problems especially in the idling or light load operation region.

The prior art shown in Japanese Patent Publication No. 47-24041 and Japanese Patent Publication No. 4743366 inhales a rich mixture and air or a lean mixture into a cylinder through separate routes, and prevents the two from being mixed until the point of ignition. Immediately before, a rich mixture is guided around the spark plug, and air or a lean mixture is guided away from the spark plug to ignite the rich mixture to improve ignition combustibility and improve the overall air-fuel ratio. However, such technology requires complicated equipment and control to always achieve good stratification and lead a rich mixture to the vicinity of the spark plug, regardless of the operating condition. It has the disadvantage of becoming.

The present invention improves ignition combustibility by adding a simple sub-intake system that injects gas into the cylinder, and moreover relates to an improvement in a combustion method that is completely different from the stratified combustion described above.

In other words, the ignitability is improved by scavenging air near the spark plug and the flow of intake air near the plug during ignition, and the combustibility is improved by generating strong turbulence or turbulence given to the intake air-fuel mixture by the injected gas. Improves fuel efficiency by achieving lean burn without deteriorating drivability,
This relates to a combustion method that reduces the amount of harmful gas emissions.

The internal combustion engine of the present invention has been proposed in view of the above, and the air-fuel mixture generated by the air-fuel mixture generating device is supplied to the combustion chamber from an intake port provided in the cylinder head via the main intake passage. In an internal combustion engine, a spark plug is installed such that a spark gap is arranged at a predetermined position in the combustion chamber, and a spark plug is provided in a cylinder head and opens directly into the combustion chamber and in the vicinity of the spark gap. An injection hole oriented near the spark gap, an auxiliary intake passage connected to the injection hole, a gas supply source that supplies gas to the auxiliary intake passage at a sufficient gas supply pressure even under light load, and the auxiliary intake passage. It is characterized by having a sub-intake valve that opens and closes, and an operating mechanism that opens the sub-intake valve during the intake stroke.Especially during idling and light load operation, the amount of intake air from the main intake passage is reduced by the throttling action of the throttle valve. During the intake stroke, there is a high negative pressure inside the combustion chamber, and the pressure difference causes the intake air to be injected from the injection hole toward the set direction inside the combustion chamber.
A strong turbulent flow or turbulent flow occurs in the combustion chamber, increasing the combustion rate and improving fuel efficiency.In addition, when the jet from the injection hole acts around the spark gap of the ignition plug located in the combustion chamber, combustion increases. Gas scavenging is performed to extend the lean burn limit.

Therefore, even if lean mixture combustion is performed in the idling or light load operation range where the air-fuel mixture distribution is poor and the combustion chamber wall temperature is low and combustibility is poor, the decrease in output and increase in fuel consumption can be kept to a minimum. By increasing the air-fuel ratio, the maximum combustion temperature is lowered, and the amount of NOx generated is extremely reduced.

Furthermore, if an exhaust gas recirculation device is used in conjunction with the internal combustion engine of the present invention, the amount of NOx generated can be easily reduced without setting the air-fuel ratio, which is difficult to control, to a high value close to the combustion limit. Deterioration of ignitability and flame propagation velocity due to exhaust gas recirculation is also improved by the jet flow.

Incidentally, even if the gas supplied from the gas supply source is air, mixture, or exhaust gas, the effect of improving combustibility due to the jet flow occurs, but it is necessary to selectively switch and supply these gases according to the operating conditions. By doing so, lean combustion and exhaust gas recirculation can be easily controlled according to the operating conditions, and the generation rate of NOx can be further reduced without deteriorating combustibility.

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

In each figure, the same or equivalent parts are given the same reference numerals.

In the first embodiment of the present invention shown in FIGS. 1 to 3, 1 is a wood for an automobile gasoline internal combustion engine, 2 is a cylinder head, 3 is a cylinder block, 4 is a piston, 5 is a combustion chamber,
6 is a spark plug, 7 is a main intake port, 37 is an exhaust port, 8 is a main intake valve, 9 is an intake manifold, 10 is a carburetor,
11 is an air cleaner.

The cylinder head 2 is provided with an injection hole 12 that opens into the combustion chamber 5, and the injection hole 12 has a set angle with the top surface of the piston in the direction of the piston 4, and has an ignition gap 6' of the spark plug 6.
The injection hole 12 is also connected to a sub-intake passage 14 via a sub-intake valve 13.

Both the main intake valve 8 and the sub-intake valve 13 are mushroom valves driven by the same rocker arm 15.
5 is fitted onto a rocker shaft 16 and swings in contact with a cam 18 provided on a camshaft 17 that is rotated by the engine.
The adjustment screws 19 and 20 are screwed into each branch, respectively.The end surface of the adjustment screw 19 contacts the upper end surface of the valve stem of the main intake valve 8, and the end surface of the adjustment screw 20 contacts the valve stem of the sub-intake valve 13. It is in contact with the rod end surface.

In addition, 21 and 22 are valve springs, 23 and 24 are spring seats, and 25 and 26 are valve guides.

A venturi 28 and a throttle valve 2 are connected to the carburetor 10 portion of the main intake passage 27 that communicates from the air cleaner 11 to the intake port 7 via the carburetor 10 and the intake manifold 9.
An idle port 30 and a slow port 3 are arranged on the inner wall of the intake passage near the fully closed position of the throttle valve 29, and an idle port 30 and a slow port 3 are arranged to supply fuel mainly during idle or light load.
1 is bored, and the idle port 30 is provided with an adjustment screw 32, while the venturi 28 is provided with a main nozzle 33 that mainly supplies fuel during medium to high loads.

One end of the exhaust gas recirculation passage 34 is connected to an exhaust passage (not shown), and the other end thereof is connected to a gathering part of the intake manifold 9 via a control valve 35 that detects various driving states of the engine and controls the flow rate. ing.

Further, the auxiliary intake passage 14 is communicated with the main intake passage 27 upstream of the venturi 28 via a pipe 36.

According to the above configuration, the main intake passage 2 is
Most of the air taken into the combustion chamber 5 is mixed with fuel at a predetermined air-fuel ratio in the carburetor 10, and then flows through the intake port 7 into the combustion chamber 5.
Meanwhile, a part of the intake air is guided to the injection hole 12 through the sub-intake passage 14 via the pipe 36, and is injected from the injection hole 12 into the combustion chamber 5.

The amount of injection from the injection hole 12 and the strength of the jet flow vary depending on the opening degree of the throttle valve 29, that is, the load of the engine.
When idling with a small throttle opening or under light load, the throttle valve 29 throttles the main intake passage 2.
7, the amount of air-fuel mixture supplied from 7 is small, high negative pressure is generated in the combustion chamber 5 during the intake stroke, and the main intake passage 27 upstream of the venturi 28 is at approximately atmospheric pressure, so a large amount of air flows due to the pressure difference. The air-fuel mixture sucked into the combustion chamber 5 is powerfully injected from the injection hole 12, and the jet flow of this air creates a vortex or turbulent flow, and the mixture of air causes the air-fuel mixture sucked in from the main intake passage 27 to become inhomogeneous. dilute in condition.

Furthermore, the air injected from the injection hole 12 strongly scavenges the burnt gas near the ignition gap 6' of the spark plug 6, thereby improving ignition performance.

Therefore, at the time of ignition, it is thought that the rich mixture and lean mixture in the combustion chamber 5 are distributed in spots, creating a vortex or turbulent flow, and according to experiments, compared to conventional engines, It was confirmed that the flame propagation speed is improved, fuel efficiency is improved, and drivability is improved with less loss of output due to air-fuel mixture dilution.

In this embodiment, the inner diameter of the injection hole 12 is set to about 3 mm, and the inner diameter of the auxiliary intake passage 14 is set to about 5 mm, so that the amount of intake air supplied from the auxiliary intake passage 14 in the light load operation region is equal to that of the main intake passage. The overall air-fuel ratio of the intake air supplied from the main intake passage 27 and the auxiliary intake passage 14 is set to about 10 to 20% of the amount of intake air supplied from the main intake passage 27 and the auxiliary intake passage 14. 10 has been adjusted.

In addition, FIG. 4 is an engine output diagram in which the vertical axis is the engine output line and the horizontal axis is the engine speed, where the solid line A is the throttle valve 29 fully open output line, the solid line B is the output line at the idle opening, The solid line C is a flat road running curve, the one-dot chain line is an equal negative pressure line of the intake manifold negative pressure generated in the intake manifold 9, the two-dot chain line is an equal throttle opening line, the broken line is an equal air-fuel ratio line,
The hatched area indicates the light load operation area.

In the light load operation region indicated by the hatched region, the air-fuel ratio is adjusted to about 15 to 17.

Further, the amount of exhaust gas sucked into the intake manifold 9 through the exhaust gas recirculation passage 34 is controlled by the control valve 35, and the amount of exhaust gas recirculation is adjusted so as to suppress the amount of NOx discharged within a set value.

On the other hand, in a high-load operating region where the throttle opening is large, the throttling action by the throttle valve 29 is small and a large amount of air-fuel mixture is drawn into the combustion chamber 5 through the main intake passage 27. Although the injection amount and the injection force are reduced, in this case, the intake efficiency is high, and when the air-fuel mixture flows into the combustion chamber 5 from the intake port 7, a strong vortex or turbulent flow is generated, and the combustion chamber 5 is Since the temperature of the inner wall also rises, the flame propagation speed increases and the combustibility improves even without generating swirl or turbulence, especially by the jet flow from the injection holes 12.

As is clear from the above, according to this embodiment, the combustion chamber 5
In a light load operation region with poor combustion conditions such as relatively low inner wall temperature and poor intake efficiency, air flowing into the combustion chamber 5 from the injection holes 12 is further mixed with the mixture containing part of the exhaust gas. Even though the air-fuel ratio is a lean mixture with a total air-fuel ratio of about 15 to 17, and the mixture is combusted with poor combustibility, the ignition gap 6' of the spark plug 6 becomes effective due to the powerful air injection from the injection hole 12. The scavenged air generates a stronger vortex or turbulent flow, and the injected air is mixed with the air-fuel mixture taken in from the main intake passage 27 in an appropriate clump state, resulting in an increase in the amount of NOx generated. This has the effect of improving ignition performance and combustion speed, shortening the combustion completion time, reducing fuel consumption, improving drivability, and reducing the amount of unburned gas emissions such as HC and CO. .

A second embodiment of the present invention shown in FIG. 5 has a configuration in which an air/exhaust gas switching valve 38 is interposed in the middle of the pipe 36 of the auxiliary intake passage 14 in the first embodiment. The valve body 39 of the valve 38 is connected to the central part of the diaphragm 42 of the diaphragm device 41 via the rod 40, and of the two chambers separated by the diaphragm 42, one chamber 43 is open to the atmosphere and the other chamber 44 is connected to the pipe 45. The chamber 44 is connected to the main intake passage 27 in the intake manifold 9, and the chamber 44 has a built-in spring 46 that presses the diaphragm 42 upward in FIG. The intake passage side of the pipe 36 is opened for communication, and the combustion chamber side of the pipe 36 is opened for communication in the side wall of the chamber 47, and the chamber 47 is communicated with the chamber 49 through a lower wall through hole 48 penetrating the rod 40. A branch pipe 50 of the exhaust gas recirculation passage 34 is opened to communicate with the side wall of the exhaust gas recirculation passage 34 .

The valve body 39 moves up and down by the operation of the diaphragm device 41, and when it rises, it closes the opening of the pipe 36, and when it descends, it closes the through hole 48.

Note that 51 is a check valve that is installed in the pipe 36 and allows air to flow only in the direction of the chamber 47 from the main intake passage 27;
The diaphragm device 41 sets a negative pressure in the chamber 44, e.g.
When a negative pressure of imHg or higher is applied, the diaphragm 42 is sucked downward against the pressing force of the spring 46 and is set to descend.

According to the above configuration, when the intake manifold negative pressure exceeds the set negative pressure during idling or light load operation with a small throttle opening, the diaphragm 42 descends, the valve body 39 closes the through hole 48, and the injection hole 12 is supplied with air from the upstream side of the venturi 28 of the main intake passage 27, and when the intake manifold negative pressure becomes less than the set negative pressure in the high-load operating range of the throttle opening, the diaphragm 4
2 rises, the valve body 39 closes the opening of the pipe 36, and the exhaust gas in the exhaust gas recirculation passage 34 flows into the injection hole 12 through the branch pipe 50.
, the chamber 49 , the through hole 48 , the chamber 47 , the combustion chamber side pipe 36 and the sub-intake passage 14 .

Therefore, in a light load operating region where the jet flow from the injection hole 12 is strong, air is injected to scavenge the ignition gap 6', and the air-fuel mixture is diluted in spots and a vortex or turbulent flow is generated. The same effect as the first embodiment can be obtained, and in a high-load operation region where the jet flow from the injection hole 12 is weak, exhaust gas is also recirculated from the injection hole 12 to increase the amount of exhaust gas recirculation in the high-load region, thereby achieving lean combustion. In this case, the effect of reducing the amount of NOx generated, which is limited, is improved.

A third embodiment of the present invention shown in FIG. 6 differs from the first embodiment in that the pipe connected to the main intake passage 27 on the upstream side of the venturi 28 is evacuated by an air pump 51 for the purpose of re-combusting unburned gas. Passage 5 for secondary air supplied to the system
2, and the injection hole 12 with a small diameter of about 3 is configured as an injection hole 12' with a large diameter that is the same as the cylinder diameter of the valve seat part of the sub-intake valve 13. In the intake stroke, the difference between the discharge pressure of the air pump 51 and the negative pressure of the combustion chamber 5 is large, and since the diameter of the injection hole 12' is small, a large amount of air is injected into the combustion chamber 5, resulting in a large amount of air injection. effective when required.

A fourth embodiment of the present invention shown in FIG. 7 differs from the first embodiment in that the pipe 36 connected to the main intake passage 27 on the upstream side of the venturi 28 is
According to this embodiment, the opening degree of the throttle valve 29 is small and fuel is mainly supplied from the slow system of the idle port 30 and the slow port 31, and the main nozzle 33, a lean mixture containing fuel injected from the main nozzle 33 is injected into the combustion chamber 5 from the injection hole 12, and in a high load operation area, the injection hole 1
The air-fuel mixture similar to the air-fuel mixture taken in from the main intake passage 27 is also injected from the main intake passage 27.

Therefore, when the air-fuel mixture as described above is injected from the injection hole 12, in addition to generating a strong vortex or turbulent flow in the combustion chamber 15 to increase the combustion speed, the injection hole 12 is connected to the spark plug 6. The spark plug 6 is directed toward the vicinity of the spark gap 6', and also serves as a scavenging function for the combustion gas around the spark plug 6, thereby further improving combustibility.

A fifth embodiment of the present invention shown in FIG. 8 eliminates the sub-intake valve 13 and its valve operating mechanism in the first embodiment, and simply opens the sub-intake passage 14 by the negative pressure generated in the combustion chamber 5. The check valve 53 is interposed as an auxiliary intake valve, and the check valve 53 is provided in the mounting screw groove 54 of the pipe 36, 55 is a valve body, and 56 is a spring.
A cooling water passage 57 for cooling the check valve is formed in the peripheral cylinder head 1 .

Also in this embodiment, the injection hole 12 is oriented toward the vicinity of the spark gap 6' of the spark plug 6.

According to this embodiment, when negative pressure is generated in the combustion chamber 5 during the intake stroke, the check valve 53 opens and air is injected into the combustion chamber 5 from the injection hole 12 through the pipe 36 and the auxiliary intake passage 14. , scavenges air around the ignition gap 6' of the spark plug 6, and generates a vortex or turbulence in the air-fuel mixture in the combustion chamber 5.

A sixth embodiment of the present invention shown in FIG.
A cylindrical injection chamber 58 is formed in the upper part of the combustion chamber 5, and the injection chamber 58 is connected to the combustion chamber 5 through an injection hole 12 that opens at the bottom.
A sub-piston 59 is fitted into the injection chamber 58, and the sub-piston 59 is moved up and down within the injection chamber 58 by a valve mechanism driven by rotation of the camshaft 17.
The auxiliary intake passage 14 is opened to the atmosphere through a dedicated air cleaner 60 and is opened to the inner circumferential surface of the injection chamber 58, so that the sliding surface of the auxiliary piston 59 is connected to the auxiliary intake passage 14.
It is configured to open and close the opening.

In addition, 61 is a rocker arm, 62 is a spring seat,
63 is a return spring, and 64 is a cam provided on the camshaft 17. The cam profile of the cam 64 is set so that the sub piston 59 is displaced as shown in FIG.

Note that the X period in FIG. 10 is a period in which the opening of the auxiliary intake passage 14 is open, and the Y period is a period in which the auxiliary piston 59 is in the injection chamber 5.
8, the sub-intake passage 14 and the injection hole 12 are in communication from the intake stroke to the early stage of the compression stroke.

According to this embodiment, air is injected from the injection hole 12 into the combustion chamber 5 by the negative pressure generated in the combustion chamber 5 within the X period, and furthermore, the air is injected into the combustion chamber 5 by compression of the auxiliary piston 59 within the Y period. The jet flow continued and ejected from the injection hole 12 becomes stronger than in each of the above embodiments, and the effect of generating eddy currents and turbulent flows increases.

Furthermore, in this embodiment, since the injection direction of the injection hole 12 is directed toward the vicinity of the spark gap 6' of the spark plug 6, air is strongly scavenged especially by the jet immediately before ignition, further expanding the lean burn limit.

In each of the above embodiments, the overall air-fuel ratio of the intake air supplied from the main intake passage 27 and the auxiliary intake passage 14 is in the range of 15 to 19 in the light load operating region where the injection from the injection holes 12 or 12' is strong. When the fuel injection is in the range of 15 to 17, the effect of improving fuel efficiency etc. by the injection becomes effective, and the effect is particularly remarkable when the injection is in the range of 15 to 17.
The optimum amount of intake air supplied from the main intake passage 27 varies depending on the type of engine, but it is 5 to 50% of the amount of intake air supplied from the main intake passage 27.
It is preferable to set it within the range of 30%, and the effect is particularly remarkable when it is within the range of 10 to 20%.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the first embodiment of the present invention, FIG. 2 is a view taken along the line A-A in FIG. 1, FIG.
The figures are an engine output diagram used to explain the operation of the first embodiment, FIG. 5 is a sectional view showing the second embodiment of the present invention, and FIG.
The figure is a sectional view of a main part showing a third embodiment of the invention, FIG. 7 is a sectional view of a main part showing a fourth embodiment of the invention, and FIG. 8 is a sectional view of a main part showing a fifth embodiment of the invention. 9 are sectional views of essential parts showing a sixth embodiment of the present invention, and FIG. 10 is an explanatory view of the operation of the sixth embodiment. 1... Engine body, 2... Cylinder head, 3... Cylinder block, 4...
Piston, 5... Combustion chamber, 6... Spark plug, 7... Intake port, 8... Main intake valve, 9... Intake manifold, 10...
... Carburetor, 11 ... Air cleaner, 12,1
2'...Injection hole, 13...Sub-intake valve,
14...Sub-intake passage, 15...Rocker arm, 17...Camshaft, 27...
...Main intake passage, 28...Venturi, 29.
... Throttle valve, 34 ... Exhaust gas recirculation passage, 35 ... Control valve, 36 ... Pipe, 38 ... Switching valve, 41 ... ...Diaphragm device, 45...Pipe, 50...
・Branch pipe, 51... Air pump, 52...
...Secondary air passage, 53...Check valve, 57...
... Cooling water passage, 58 ... Injection chamber, 59.
... Sub-piston, 60 ... Air cleaner, 61 ... Rocker arm, 64 ... Cam.

Claims (1)

[Scope of Claims] 1. In an internal combustion engine in which the air-fuel mixture generated by the air-fuel mixture generating device is supplied to the combustion chamber from an intake port provided in the cylinder head via the main intake passage, an ignition plug installed in such a way that a spark gap is disposed therein; and an injection hole drilled in a cylinder head that opens directly into the combustion chamber, opens in the vicinity of the spark gap, and is oriented in the vicinity of the spark gap; a sub-intake passage connected to the injection hole; a gas supply source that supplies air to the sub-intake passage with sufficient gas supply pressure even during light load operation; a sub-intake valve that opens and closes the sub-intake passage; An internal combustion engine comprising: an actuation mechanism that opens a sub-intake valve during an intake stroke. 2. The internal combustion engine according to claim 1, wherein the air-fuel mixture generating device is a carburetor. 3. The internal combustion engine according to claim 1, wherein the auxiliary intake valve and the operating mechanism are spring-loaded check valve mechanisms that open due to negative pressure generated in the combustion chamber during the intake stroke. 4. The internal combustion engine according to claim 1, wherein the operating mechanism is a valve operating mechanism that opens and closes the auxiliary intake valve in conjunction with rotation of an intake valve driving camshaft that opens and closes the intake port. 5. Claim 4, wherein the sub-intake valve is a mushroom valve.
Internal combustion engine as described in section. 6. The internal combustion engine according to claim 2, wherein the gas supply source is an intake passage upstream of the venturi section of the carburetor. 7. The internal combustion engine according to claim 2, wherein the gas supply source is an intake passage between a venturi section of the carburetor and a throttle valve. 8. The internal combustion engine according to claim 1, wherein the gas supply source is an exhaust gas passage. 9. The auxiliary intake valve is a auxiliary piston that reciprocates in a cylindrical hole formed in a cylinder head, the auxiliary intake passage is opened on the inner peripheral surface of the cylindrical hole, and the injection hole is opened on the end surface of the cylindrical hole, The sliding surface of the auxiliary piston opens and closes the opening of the auxiliary intake passage, and the auxiliary piston compresses the gas in the cylindrical hole and injects it from the injection hole during the compression stroke of the combustion chamber. Internal combustion engine according to paragraph 4. 10. The internal combustion engine according to claim 1, wherein the gas supply source is a passage for exhaust gas purifying secondary air discharged by an air pump. 11. The internal combustion engine according to claim 1, wherein the total air-fuel ratio of the intake air supplied from the main intake passage and the auxiliary intake passage is 15 to 19 at least in most of the light load operating region. 12 In the light load operating range, the amount of intake air supplied from the auxiliary intake passage is 5 to 30 times the amount of intake air supplied from the main intake passage.
%. 13 The main gas supply source is a plurality of gas supply sources that supply air, mixture, or exhaust gas, and the switching valve that selectively switches the gas supply from the plurality of gas supply sources according to the operating state of the engine is used as the secondary gas supply source. An internal combustion engine according to claim 1, wherein the internal combustion engine is provided with an intake air.