JPS6030440A - Stratified charging engine - Google Patents

Abstract

PURPOSE:To ensure the condition of an engine to be early warmed so as to obtain good performance of purifying its exhaust, by performing lean state stratified combustion in a range when the engine is low loaded while uniform combustion in a range when it is high loaded while decreasing an intake air amount so as to generate rich air-fuel ratio when the engine is cooled in a cold state. CONSTITUTION:A control device 16, when it is in low and intermediate loaded ranges by a load detecting means 17, stops supply of dispersed fuel by a fuel supply means 13, fully opens a throttle valve 14 by a means 21 to hold an intake air amount to a fixed level and supplies stratified fuel around an ignition device 8 from a fuel supply means 11, performing lean state stratified combustion. Next, the control device 16, if it advances to the range above a preset load, transfers the combustion to uniform combustion first by starting the supply of the dispersed fuel from the fuel supply means 13 next by decreasing supply of the stratified fuel. While the control device 16, in its low and intermediate loaded ranges when an engine is cooled in a cold state, decreases an opening of the throttle valve 14 smaller as a load decreases so as to reduce an intake air amount and generate a rich mixture, promoting the engine to be warmed. In this way, good stratified combustion is performed while a warming characteristic of the engine and purifying performance of its exhaust can be improved.

Description

[Detailed description of the invention] (Industrial application field) BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stratified air charge engine.

(Prior art) Conventionally, for the purpose of improving the fuel efficiency and emission performance of an engine, fuel necessary for ignition among the fuel supplied to the combustion chamber according to the load is unevenly distributed in the vicinity of the ignition device. A stratified air charge engine that can realize lean combustion as a whole by enriching the air-fuel ratio only in this part to perform stratified combustion with improved ignitability has been proposed, for example, in Japanese Patent Application Laid-Open No. 49-6280.
No. 7, JP-A-49-128109.

In the above-mentioned stratified air supply engine, the ignition fuel supplied around the ignition device is kept constant regardless of the load, and at the same time the ignition fuel is supplied, an amount of dispersed fuel corresponding to the load is supplied. However, when the engine is cold, if stratified combustion based on the fuel unevenly distributed around the ignition device is performed in the same way as when the engine is warm, the exhaust temperature will be low, so [! l! There are problems with the functionality and exhaust purification performance.

However, in stratified combustion, fuel efficiency is improved by achieving lean combustion, and the opening of the throttle valve is increased to reduce pumping loss. As a result, the cooling performance increases and the exhaust temperature decreases.

If this stratified combustion is performed even when the engine is cold, it will take a long time for the engine temperature to rise to @machine humidity, and the temperature of the catalyst device d installed in the exhaust system will be low enough to activate the catalyst. Since the reaction temperature is not reached, sufficient purification performance cannot be obtained and there is a problem that emission performance is reduced.

(Object of the Invention) Therefore, in view of the above circumstances, the present invention performs stratified combustion in which fuel is unevenly distributed and supplied around the ignition device at least at low load times, and at the same time, in high load regions, the fuel is distributed throughout the combustion chamber. The uniform combustion supplied by
The purpose of this invention is to provide a stratified intake engine that achieves stratified combustion and uniform combustion, and also improves warm-up performance and exhaust purification performance when the engine is cold.

(Structure of the Invention) The stratified air supply engine of the present invention includes a fuel supply means for supplying fuel around the ignition device in the combustion chamber, and an intake throttle means for controlling the opening area of the intake passage, and at least at low load. Stratified combustion is achieved by supplying fuel from the fuel supply means unevenly distributed around the stone ignition device and igniting it, while at times of high load, uniform combustion is achieved by supplying fuel distributed within the combustion chamber and igniting it. When the engine is cold, the opening area of the intake passage is reduced by the intake throttle means compared to when the engine is warmed up, while the fuel is distributed and supplied into the combustion chamber by the fuel supply means.
It is characterized by increasing the air-fuel ratio to the ridge and achieving uniform combustion.

(Effect of the invention) In a low load range, the fuel supply means supplies fuel unevenly around the ignition device in the combustion chamber to perform stratified combustion, improving fuel efficiency through lean combustion, while in a high load operating range The fuel supplied by the fuel supply means is dispersed to perform uniform combustion, and it is possible to ensure good high-output operation without generating smoke.

In addition, when the engine is cold, the intake air throttle means reduces the amount of intake air compared to when the engine is running, making the air-fuel ratio richer, suppressing excessive cooling due to intake air, and supplying dispersed fuel into the combustion chamber using the fuel supply means. It is possible to achieve uniform combustion by raising the exhaust temperature, ensuring early warm-up by raising the temperature of the catalyst, and activating the catalyst by raising the temperature of the catalyst, thereby achieving good exhaust purification performance.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

Embodiment 1 This embodiment is shown in FIGS. 1 to 5, and shows an example in which the fuel supply means is composed of a first fuel supply means for stratification and a second fuel supply means for dispersion.

In the engine shown in FIG. 1, 1 is a combustion chamber formed above a piston 2, 3 is an intake passage that introduces intake air into the combustion chamber 1, 4 is an exhaust passage that leads out exhaust gas from the combustion chamber 1; Reference numeral 5 indicates an intake valve, 6 an exhaust valve, and 7 a catalyst device installed in the exhaust passage 4, respectively.

The combustion chamber 1 is provided with an ignition device 8 using a spark plug, and a stratified fuel injection nozzle 9 for supplying fuel around the ignition device 8. A fuel injection pump 10 is connected to constitute a first fuel supply means 11 .

On the other hand, a second fuel supply means 13 is interposed in the intake passage 3 and includes a dispersion fuel injection nozzle 12 for distributing fuel into the combustion chamber 1 . Further, a throttle valve 14 is disposed downstream of the dispersion fuel injection nozzle 12, and an actuator 15 (not linked to accelerator operation) is disposed on the throttle valve 14 to open and close the throttle valve 14. An intake throttle means 20 is configured to regulate the amount of intake air by controlling the U1 opening area of the intake passage 3.

As shown in FIG. 2, the downstream portion of the intake passage 3 is curved to direct the intake air from the tangential direction of the combustion chamber 1, and to direct the intake air into the combustion chamber 1 along its circumferential direction. This swirl causes the ignited fuel ignited in the device 8 comprising the stratified fuel injection nozzle 9 of the first fuel supply means 11 to be sufficiently mixed with air, and also causes a flame to be generated. is propagated throughout the combustion chamber 1, and the entire injected fuel is sufficiently burned.

The fuel injection pump 10 of the first fuel supply means 11, the second
The operation of the dispersing fuel injection nozzle 12 of the fuel supply means 13 and the actuator 15 of the intake throttle means 20 is controlled by the control means 16.

, the second control l+ means 16 includes a load detection means 17 for detecting the required load of the engine by, for example, an accelerator sensor.
and a detection signal from a water temperature sensor 18 that detects when one engine is cold by, for example, the cooling water temperature, as well as an engine rotation signal from an engine rotation sensor 19, Controls the fuel injection amount, fuel injection timing, and fuel injection amount from the dispersion fuel clear nozzle 12, and
It controls the closing timing of the throttle valve 14.

The control means 16 operates the intake throttle means 20 to close the throttle valve 14 in response to the detection signal of the water temperature sensor 18 when the engine is cold and the concentration of the cooling water is below a set value.
6), and a predetermined amount of dispersed fuel is supplied by the second fuel supply means 13.

Further, the control means 16 performs fuel supply amount control corresponding to the load by receiving a signal from the load detection means 17, and in the normal operating range in the low/medium load range below the set load, the second fuel supply means 13 controls the amount of distributed fuel. The supply is stopped, stratified fuel is supplied by the first fuel supply means 11 to perform stratified combustion, and the supply amount is increased as the load increases, and when the set load is exceeded, the supply amount of the stratified fuel is decreased. It is. on the other hand,
The distributed fuel by the second fuel supply means 13 starts to be supplied at a load equal to or higher than the above-mentioned set load, compensates for the decrease in the amount of stratified fuel by the first fuel supply means 11, and increases the total supply amount according to the increase in load. The amount of dispersion fuel supplied is increased so that the amount of fuel increases, thereby shifting from stratified combustion to uniform combustion. At this time, the injection amount and number of injections for each injection are set in accordance with the engine rotation speed.

That is, the fuel supply amount control by the first fuel supply means 11 and the second fuel supply means 13 corresponding to the load of the engine is as follows.
This is done as shown in Figure 3. This figure 3 shows the fluctuation of fuel supply mQ with respect to the fluctuation of the load, together with the fluctuation of the excess air ratio λ. 144, the fuel v1 supply mo is increased to reduce the excess air ratio λ, that is, the air-fuel ratio is enriched to perform output horn control. In the fuel supply f21Q, the fuel in the area is supplied to the first
The fuel stone is supplied from the fuel stone supply means 11, and the fuel of the area 12 is supplied from the second fuel supply means 13. The supply of stratified fuel by the first fuel supply means 11 increases as the load increases below the set load at point A, while when the set load exceeds point A, the supply of fuel from the first fuel supply means 11 decreases. However, when the load is high beyond point B, a small amount of fuel injection is continued in order to prevent the stratification fuel injection nozzle 9 from clogging with carbon and to prevent heating.

On the other hand, the supply of dispersed fuel by the second fuel supply means 13 starts at a load equal to or higher than the set load at point A, and when the load increases from this point on, it compensates for the decrease in the supply of stratified fuel by the first fuel supply means 11, and Overall, increased fuel is supplied in response to an increase in load.

The set load at point A above is the excess air ratio λ at that point.
The load condition at point B is such that the excess air ratio λ is below the ignition limit at which even a homogeneous mixture can be ignited. The load condition is set such that the excess air ratio λ is lowered and smoke starts to occur.

Therefore, below the above point A, fuel is supplied in a stratified combustion region unevenly distributed around the ignition device 8 of the combustion chamber 1, and above point B, fuel is distributed and supplied throughout the combustion chamber 1. In the uniform combustion region, the area between A-8 is a transition region from the stratified combustion region to the uniform combustion region.

Note that the timing at which the second fuel supply means 13 starts supplying the distributed fuel is not made to coincide with the set load point A at which the supply of stratified fuel by the first fuel supply means 11 is reduced.
The supply may be started at successive load conditions near the point.

Moreover, the stratified fuel supply by the first fuel supply means 11 and the second
The switching of the distributed fuel II supply by the fuel supply means 13 is performed so that it gradually decreases and increases as described above, and also is switched on and off in the load state between the set load points A and B. You can also do this.

Next, FIG. 4 shows that the first fuel supply means 11
This indicates the injection timing (injection Q (start timing) and ignition timing) of stratified fuel according to The injected fuel is set a predetermined amount earlier, and the injected fuel reaches the ignition position H8.
Ignition is performed while being effectively unevenly distributed around the area. As we move beyond point A to the area where point B is decentralized,
The injection timing is advanced to perform injection at an earlier stage, thereby reducing uneven distribution of the fuel injected from the first fuel supply means 11 and dispersing it throughout the combustion chamber 1. Additionally, at extremely low loads such as during idling, the fuel injection timing and ignition timing are slightly advanced to improve stability.

Note that when the engine is cold, instead of supplying dispersed fuel by the second fuel supply means 13, the fuel injection timing by the first fuel supply means 11 may be advanced in the same way as when the load is high. As a result, injection is completed at JIIJ early from the intake stroke to the beginning of the compression stroke, and the subsequent combustion chamber 1
The fuel may be dispersed by the flow of intake air within the fuel tank to achieve uniform combustion.

Further, in FIG. 4, the ignition timing is set to be substantially constant with respect to load fluctuations, but this may be changed to advance the ignition timing in accordance with an increase in the load.

On the other hand, the throttle valve 1 of the intake throttle means 20 by the control means 16
As shown in Fig. 5, the opening/closing control in step 4 basically performs non-throttle operation with the throttle valve 14 fully open.
When the load is extremely low, such as when starting the engine or idling, the opening degree is reduced to reduce the amount of intake air.

In addition, when the engine is cold, as shown by the chain line in Figure 5, the valve is narrowed over a wide range in the low and medium load ranges, and as the load decreases, the opening is made smaller and the amount of intake air is reduced. This reduces the excess air ratio and makes the air-fuel ratio rich.

In addition, during deceleration when fuel supply is stopped, the throttle valve 14 is controlled to be closed in order to prevent a drop in the engine temperature and improve engine braking performance.

Therefore, if the stratified air charge engine of the above embodiment is used, in the normal operation range at low and medium loads below the set load point A, stratified combustion is performed to obtain good ignitability and lean combustion is possible. At the same time as improving fuel efficiency, in this stratified region, the intake air amount is kept constant without closing the throttle valve 14, and the output is controlled by the fuel supply amount by the first fuel supply means 11. Bumping loss associated with the throttling operation of No. 14 can be significantly reduced, further improving fuel efficiency.

In addition, in the high-load operation range exceeding the set load point A mentioned above, the system shifts from stratified combustion to uniform combustion to increase the air utilization rate and perform high-output operation without smoke generation. It provides good driving performance and improves fuel efficiency by reducing pumping loss.

Furthermore, when the engine is cold, fuel is supplied by the second fuel supply means 13 which distributes the fuel throughout the combustion chamber, or by advancing the fuel injection timing to the first fuel supply means 11 to supply fuel to the combustion chamber. The fuel supplied into the fuel tank 1 is dispersed for uniform combustion, and the intake throttle means 20 closes the throttle valve 14 to reduce the amount of intake air and enrich the air-fuel ratio of the dispersed fuel, thereby achieving good heating. We ensure availability.

Note that the second fuel supply means 13 may supply dispersed fuel to the intake passage 3 using a carburetor instead of the fuel injection method using the dispersion fuel injection nozzle 12.

Further, in the above embodiment, the dispersion fuel injection nozzle 12 of the second fuel supply means 13 is interposed in the middle of the intake passage 3; Similarly to the stratified fuel injection nozzle 9 of the first fuel supply means 11, the stratified fuel injection nozzle 9 may be arranged to open into the combustion chamber 1. In that case, the second fuel supply means 13 may directly supply the distributed fuel to the combustion chamber 1. The fuel injection timing is determined by the first
The injection is set to be completed between the intake stroke and the early stage of the compression stroke, earlier than the fuel injection timing by the fuel supply means 11, and the fuel supplied by the second fuel supply means 13 is mixed with the intake air and flows into the combustion chamber 1. When the engine is cold, the fuel is supplied by the second fuel supply means 13, or the fuel injection timing by the first fuel supply means 11 is adjusted by the second fuel supply means 13.
This is to advance the angle in the same way as in the previous example to obtain uniform combustion.

Embodiment 2 This embodiment is shown in FIGS. 6 to 9, and is an example in which the fuel supply means is constituted by one fuel injection nozzle provided in the intake passage.

In the engine shown in FIGS. 6 and 7, 22 is a primary intake passage opening into the primary intake boat 23 of the combustion chamber 1;
24 is a secondary intake passage that opens to the secondary intake boat 25, 26 is an exhaust passage that opens to the exhaust port 1-27, and 28
29 is a primary intake valve, 29 is a secondary intake valve, 30 is an exhaust valve, and 8 is an ignition device using a spark plug.

The downstream portion of the primary intake passage 22 is provided in a swirl boat that forms a swirl in the combustion chamber 1, and the upstream side merges with the secondary intake passage 24. The amount of intake air is regulated, and the above 2
A swirl control valve 31 is interposed in the secondary intake passage 24 .

Further, a fuel injection nozzle 32 is disposed in the primary intake passage 22, which injects fuel from the valve gap toward the vicinity of the ignition device M8 in the combustion chamber 1 when the primary intake valve 28 is opened. A fuel supply means 33 is configured.

The fuel supply means 33 and the intake throttle means 20 control the amount of fuel injection from the fuel injection nozzle 32, the injection timing, and the comparison valve 14 by the same control means (not shown) as in the previous example.
The vn degree of is controlled. The fuel supply means 33 performs output control by increasing the amount of fuel supplied according to the load, and switches between stratified combustion and uniform combustion by controlling the injection timing.

However, for fuel Illll, it is performed as shown in Fig. 8, where S indicates the injection start time and E indicates 11711.
Each shows the end of JJ. In the R period of fuel injection in the stratified region below the set load, which corresponds to point A in FIG. and the fuel is 1
Fuel flows into the combustion chamber 1 through the opening gap of the secondary intake valve 28 and is supplied unevenly around the ignition device 8, so that even when the piston 2 rises during the compression stroke, fuel is supplied to the upper part of the combustion chamber 1. It is designed to cause stratified combustion by unevenly distributing the fuel.

At this time, the fuel injection path is set at a fixed time, the injection start is made early, and the injection amount is increased in accordance with the increase in load.

In addition, when the set load at point A is exceeded, the injection timing is greatly advanced to make it earlier, and when the load exceeds 8 points, the injection path is kept constant and the start of injection is advanced to respond to the increase in load. The injection time is increased by increasing the injection time, and by supplying fuel from the beginning of the intake stroke, the fuel that flows into the combustion chamber 1 is dispersed throughout the combustion chamber 1 by the flow of intake air, resulting in uniform combustion. be.

Furthermore, when the engine is cold, the injection timing (start timing) is greatly advanced even under low load, as shown by the chain line in Fig. 8, to advance it, and the fuel is dispersed as fuel is supplied from the beginning of the intake stroke. The injection amount is increased by keeping the injection start constant and delaying the injection path as the load increases.

Note that the swell control valve 31 installed in the secondary intake passage 24 opens from the set point A to supply intake air from the secondary intake passage 24 as well.
This prevents the swirl strength of the intake air supplied by the engine from becoming excessive, suppressing combustion noise and knocking caused by an abnormal increase in combustion speed, and reducing intake resistance to improve intake efficiency. It is something.

The opening degree of the throttle valve 14 in this embodiment is controlled as shown in FIG. In this example, the stratification of the fuel that falls into the stratification region is reduced because the proportion of uneven distribution around the ignition device 8 is lower than in the previous example, so the throttle valve 14 needs to be throttled to reduce the amount of intake air. However, like the conventional carburetor engine as shown by the chain line, the mixture is filled with 5 units.
The aperture opening is smaller than that in which the output is controlled by the control, and the pumping effect can be reduced.

When the engine is cold, the opening degree of the throttle valve is reduced to about 4 degrees as indicated by the chain line, thereby reducing the amount of intake air and enriching the air-fuel ratio.

Therefore, in this embodiment as well, at low loads, lean combustion is performed by stratified combustion to improve fuel efficiency, while at high angle WJ, uniform combustion allows high output operation without smoke generation.

In addition, when the engine is cold, the air-fuel ratio is enriched by reducing the amount of intake air, and the fuel is dispersed by advancing the injection timing, thereby achieving good warm-up performance and raising the temperature quickly. Activate the catalyst.

In addition, the injection timing control of IIJ Kishu in this example,
As shown in Fig. 8, instead of keeping the injection path constant (standard) and advancing the injection start to increase the injection amount according to the load, the injection path is kept constant (standard) and the injection amount is increased according to the load. The injection path may be advanced in accordance with changes in load.

Furthermore, in both of the above embodiments, 1 water thirst' for C1 cold? Depending on the degree of coldness of the engine, the intake throttle means 20
It is also possible to change and adjust the amount of decrease in the amount of intake air due to C, or the degree of uniformity tendency by advancing the injection timing. This is the first thing to return to.

[Brief explanation of the drawing]

1 to 5 show a first embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a stratified air charge engine, FIG. 2 is a plan view schematically showing a combustion chamber, and FIG. 4 is a characteristic diagram showing the injection timing and ignition timing of stratified fuel by the first fuel supply means in response to load fluctuations, and FIG. Figures 6 to 9 show a second embodiment of the present invention, and Figure 6 is a partial cross-section of a cylinder head in a stratified intake engine. Figure 7 is a sectional view taken along the line Vl-Vl in Figure 6, Figure 8 is a characteristic diagram showing fuel injection timing control with respect to load, and Figure 9 is a diagram showing the opening of the throttle valve with respect to load. It is a characteristic diagram that does not show control. 1... Combustion chamber 3... Intake passage 8...
..... Ignition device 9 ..... Fuel injection nozzle for stratification 10 ..... Fuel injection pump 11 ..... First fuel supply means 12 ..... Fuel for dispersion Injection nozzle 13...
・Second fuel supply means 14... Throttle valve 15... Actuator 16... Control means 17... Load detection means 18... Water temperature Sensor 20...
...Intake throttle means 32...Fuel injection nozzle 33...Fuel supply means L- Figure 6 9 Figure 7

Claims (1)

[Claims] (1) It is equipped with a fuel supply means for supplying fuel into the combustion chamber, an ignition device disposed inside the combustion chamber, and an intake throttle means for controlling the opening area of the intake passage, and at least when the load is low, the fuel supply means ignites the fuel. Stratified combustion is performed by supplying fuel unevenly around the device and igniting it, while at high loads, stratified air supply is distributed within the combustion chamber to supply fuel and ignite it to achieve uniform combustion. In the engine, when the engine is cold, the opening area of the intake passage is reduced by the intake throttle means compared to when the engine is warm, while the fuel is distributedly supplied into the combustion chamber by the fuel supply means.
A stratified air supply engine characterized by uniform combustion.