JPS6030417A - Stratiform charging engine - Google Patents

Abstract

PURPOSE:To obtain excellent combustibility and improve exhaust gas purifying performance by performing at a light load, a stratiform combustion by the supply of unevenly distributed fuel to the vicinity of the ignition device, at a heavy load range, uniform combustion by the supply of dispersed fuel, and in a deceleration operation by throttling the suction air. CONSTITUTION:In a combustion chamber 1, a sparking plug 8 and a stratifying fuel injection nozzle 9 which supplies fuel to the vicinity of the sparking plug 8 are provided. On the other hand, in a suction passage 3, a dispersing fuel injection nozzle 12 which supplies dispersed fuel and a throttle valve 14 which is opened or closed by an actuator 15 are arranged. When the load is in the range of light or medium below a set value, the supply of the dispersed fuel is stopped and stratified fuel is supplied for stratiform combustion, and when the load exceeds the set value the stratified fuel is decreased and dispersed fuel is increased to proceed to uniform combustion. In a deceleration operation, the throttle valve 14 is closed, which reduces the suction air quantity, decreases the quantity of air flowing through a catalyzer device 7, and prevents the device 7 from being excessively cooled, thus improving the exhaust gas purifying performance.

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, only the fuel necessary for ignition out of 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 Laid-Open No. 49-62807.
No. 49-128109, it is well known.

In the above-mentioned stratified air supply engine, the ignition fuel supplied around the ignition device is constant regardless of the load, and at the same time the ignition fuel is supplied, distributed fuel is supplied in an amount corresponding to the load. During deceleration operation, the fuel supply is reduced or not supplied, and the exhaust temperature is low, causing the catalyst device installed in the exhaust passage to become overcooled, resulting in insufficient exhaust purification performance. be.

In other words, in stratified combustion, fuel efficiency is improved by achieving lean combustion, and the opening of the throttle valve is increased to reduce pumping loss. The exhaust temperature decreases due to the increased cooling performance.

In particular, since there is almost no fuel supply during deceleration, only air passes through the catalyst device in the exhaust passage to supercool the catalyst, and when resuming reaction purification by fuel supply,
Since the temperature of the catalyst device is low and the catalyst is not activated and does not reach the reaction temperature, there is a problem that sufficient purification performance is not obtained and 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. To provide a stratified intake engine which achieves good stratified combustion and uniform combustion by performing homogeneous combustion of the fuel supplied by the engine, prevents overcooling of a catalyst device during deceleration operation, and improves exhaust purification performance. This is the purpose.

(Structure of the Invention) The stratified air supply engine of the present invention includes a fuel supply means for supplying fuel around an ignition device in a combustion chamber, and an intake throttle means for controlling the opening area of an intake passage. This system performs stratified combustion by supplying fuel unevenly distributed around the ignition device from the supply means and igniting it, while at high loads it performs uniform combustion by supplying fuel distributed within the combustion chamber and igniting it. This is characterized in that during deceleration operation, the opening area of the intake passage is reduced by the intake throttle means.

(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, during deceleration operation, the intake passage is throttled by the intake throttle means to reduce the amount of intake air, suppressing supercooling of the catalyst due to a large amount of intake air, and allowing the catalyst to be touched at an early stage when the catalyst reaction starts.
By increasing the temperature and activating the engine, it is possible to ensure good exhaust purification performance, and at the same time, engine braking performance is increased and a good feeling of deceleration can be obtained.

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

Example 1 This example is shown in Figures 1 and 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 . Furthermore, a throttle valve 14 is disposed downstream of this dispersion fuel injection nozzle 12, and an actuator 15 (not linked to accelerator operation) for opening and closing the throttle valve 14 is disposed in the intake passage. An intake throttle means 20 is configured to regulate the amount of intake air by controlling the frontage area of No. 3.

As shown in FIG. 2, the downstream portion of the intake passage 3 is curved to introduce the intake air from the tangential direction of the combustion chamber 1 and generate a swirl S along the circumferential direction within the combustion chamber 1. This swirl causes the ignition fuel supplied from the stratified fuel injection nozzle 9 of the first fuel supply means 11 and ignited by the ignition device 8 to be sufficiently mixed with air, and the flame is transferred to the combustion chamber 1. The injected fuel is propagated throughout the entire body and the entire injected fuel is sufficiently combusted.

Upper i! [l! Fuel injection pump 1 of first fuel supply means 11
0, dispersion fuel injection nozzle 12 of the second fuel supply means 13
The operation of the actuator 15 of the intake throttle means 2o is controlled by the control means 16.

The control means 16 receives a load signal from a load detection means 17 that detects the required load of the engine using, for example, an accelerator sensor, an engine rotation signal from an engine rotation sensor 18, a water temperature signal from a water temperature sensor 19, and the like. , detects the engine load, deceleration state, and cold engine state, and controls the fuel injection amount and fuel injection timing from the stratification fuel injection nozzle 9 and the fuel injection amount from the dispersion fuel injection nozzle 12, and controls the throttle valve 14. The control means 16, which controls the closing timing, includes:
Detection signal of load detection means 17 and engine rotation sensor +
The engine speed signal from 1-18 detects when the engine is running at deceleration, and during this deceleration, the intake throttle means 20 is activated to close the throttle valve 14 and narrow the frontage area of the intake passage 3 to reduce the amount of intake air. This reduces the

In addition, the fuel supply old control corresponding to the load by the control means 16 receives a signal from the load detection means 17, and in the normal operation range in the low/medium load range below the set load, the distributed fuel is distributed by the second fuel supply means 13. 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 stratified fuel by the first fuel supply means 11, and increases the total supply amount as the load increases. This is to increase the supply amount of dispersion fuel so as to shift 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 control by the first fuel supply means 11 and the second fuel supply means 13 corresponding to the load of the engine is performed as shown in FIG. FIG. 3 shows the variation of the fuel supply amount Q with respect to the variation of the load, together with the variation of the excess air ratio λ.The throttle valve 14 is basically fully open and the intake air amount is constant, In response to the increase, the fuel supply amount Q is increased to decrease the excess air ratio λ, that is, to enrich the air-fuel ratio and perform output control.

In the fuel supply amount Q, the fuel for the region is supplied from the first fuel supply means 11, and the fuel for the region is supplied from the second fuel supply means 1.
It is supplied from 3. The supply of stratified fuel by the first fuel supply means 11 increases as the load increases below the set load at point A, but when the set load exceeds point A,
The fuel supply from the first fuel supply means 11 is reduced, and when the load exceeds 8 points, 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 distributed 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, it compensates for the decrease in the supply of stratified fuel by the first fuel supply means 11, and As a result, increased fuel is supplied in response to the increase in load.

The set load at point A above is the excess air ratio λ at that point.
The load condition is set such that the excess air ratio λ is below the ignition limit for ignition even with a homogeneous mixture, and the 8-point load is such that the excess air ratio λ at that point is such that the air utilization rate is low due to stratified combustion. 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, there is a stratified combustion region in which fuel is supplied unevenly around the ignition device 8 of the combustion chamber 1, and above point 8 there is a stratified combustion region in which fuel is distributed and supplied throughout the combustion chamber 1. In the combustion region, the section A-B is the 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 should not be 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 (this point A).
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 distributed fuel supply by the fuel supply means 13 is switched on and off in the load state between the set load points A and B, in addition to gradually decreasing and increasing as described above. Good too.

Next, FIG. 4 shows that the first fuel supply means 11
This indicates the injection timing (injection start timing) and ignition timing of stratified fuel according to The timing is set, and ignition is performed with the injected fuel effectively unevenly distributed around the ignition device 8. As the point A is exceeded and the point B is distributed, the injection timing is advanced and the injection is performed at an earlier stage to reduce uneven distribution of the fuel injected from the first fuel supply means 11. and disperse it throughout the combustion chamber 1. Additionally, during extremely low load conditions such as during idling, the fuel injection timing and ignition timing are slightly advanced to improve stability.

On the other hand, the intake throttle means 20 is controlled by the control means 16.
As shown in Fig. 5, the opening/closing control of No. 4 basically performs non-throttle operation with the throttle valve 14 fully open, and for example, when starting the engine, the opening degree is reduced to reduce the amount of intake air. Also, when starting the engine, the throttle valve opening is set as shown by the chain line, and when decelerating, the throttle valve opening is set to the same degree as the idle state ID when the engine is cold (minimum opening b), and the throttle valve is opened almost fully.

Therefore, according to the stratified air charge engine of the above embodiment, in the normal operating range of low and medium loads below the set load A point plate, stratified combustion is performed to obtain good ignitability, and at the same time, low-N
In this stratified region, the intake air amount is kept constant without closing the comparison valve 14, and the output is controlled by the fuel supply m by the eleventh fuel supply means 11. By doing so, the pumping loss associated with the throttling operation of the comparison valve 14 can be significantly reduced, and fuel efficiency is further improved.

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. Good driving performance and fuel efficiency can be improved by reducing pumping loss.

Further, during deceleration operation, the intake air throttle means 20 closes the throttle valve 14 to reduce the amount of intake air, thereby reducing the amount of air flowing through the catalyst bag [7, thereby preventing overcooling of the catalyst bag H7.

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; Like the stratified fuel injection nozzle 9 of the first fuel supply means 11, it may be arranged to open into the combustion chamber 1, in which case the second fuel supply means 13 directly supplies the fuel to the combustion chamber 1. The injection timing of the dispersed fuel is the same as the first one above.
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. Uniform combustion is achieved through uniform dispersion.

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 installed in the intake passage.

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

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 air is regulated, and the above 2
A swirl control pulp 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 [8] in the combustion chamber 1 when the primary intake valve 28 is opened. The fuel supply means 33 is constituted by the fuel supply means 33.

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

That is, the fuel injection timing is performed as shown in FIG. 8, where S indicates the injection start timing and E indicates the injection start timing. The fuel injection timing in the stratified load region below the set load, which corresponds to point A in FIG. Fuel flows into the combustion chamber 1 through the opening gap of the valve 28 and is supplied so as to be unevenly distributed around the ignition device 8, and even when the piston 2 rises in the compression stroke, the fuel is distributed unevenly in the upper part of the combustion chamber 1. It is designed to perform stratified combustion.

At that time, the fuel injection path is set at a certain time, and the injection start is started early (
However, the injection amount is increased as the load increases.

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 point B, the injection path is kept constant and the start of injection is advanced to respond to the increase in load. By supplying fuel from the beginning of the intake stroke, the fuel that has flowed into the combustion chamber 1 is dispersed throughout the combustion chamber 1 by the flow of intake air, thereby achieving uniform combustion.

Note that the swirl 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, suppresses combustion noise and knocking caused by an abnormal increase in combustion speed, and reduces intake resistance to improve intake efficiency. It is.

The opening degree of the throttle valve 14 in this embodiment is controlled as shown in FIG. In this example, the stratification of fuel in the stratification region is lowered by the fact that the proportion of uneven distribution around the ignition line W18 is smaller than in the previous example, so the throttle valve 14 needs to be throttled to reduce the amount of intake air. However, compared to a conventional carburetor type engine, as shown by the chain line, in which the output is controlled by the amount of air-fuel mixture, the throttle ran is small and the pumping loss can be reduced. Also,
When the engine is cold, the throttle valve opening is as shown by the chain line.

During deceleration operation, the opening of the throttle valve is reduced to about the opening of 10 in the idle state when the engine is cold, as shown by the chain line, to reduce the amount of intake air.

Therefore, in this embodiment as well, at low loads, lean combustion is performed by stratified combustion to improve fuel efficiency, while at high loads, homogeneous combustion allows high output operation without the occurrence of smog. .

゛ Furthermore, during deceleration operation, the amount of intake air is reduced by reducing the opening area of the intake passage to prevent overcooling of the catalyst device 7, and to activate the catalyst by raising the temperature early at the start of the reaction. ing.

[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. Figure 4 is a characteristic diagram showing the control of fuel supply amount with respect to load along with excess air ratio, Figure 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 Figure 5 is Characteristic diagrams showing the opening degree of the throttle valve with respect to load fluctuations. FIGS. 6 to 9 show a second embodiment of the present invention. FIG. 6 is a bottom view showing a partial cross section of a cylinder head in a stratified intake engine. Figure 7 is a sectional view taken along line ■-VI in Figure 6, Figure 8 is a characteristic diagram showing fuel injection timing control with respect to load, and Figure 9 is a characteristic diagram showing throttle valve opening control with respect to load. It is. 1... Combustion chamber 3... Intake passage 7...
... Catalyst device 8 ... Ignition device 9 ...
... Fuel injection nozzle for stratification 10 ... Fuel injection pump 11 ... First fuel supply means 12 ... Fuel injection nozzle for dispersion 13 ...
- Second fuel supply means 14... Throttle valve 15... Actuator 16... Control means 17... Load detection means 18... Engine Rotation sensor 20・
...Intake throttle means 32...Fuel injection nozzle 33...Fuel supply means Fig. 5 Fig. 6 Fig. 9 11!8 Cargo -

Claims (1)

[Claims] (1) A fuel supply means for supplying fuel into the combustion chamber, an ignition device disposed within the combustion chamber, an intake throttle means for controlling the opening area of the intake passage, and a catalyst device disposed in the exhaust passage. At least at low loads, the fuel supply means supplies fuel unevenly around the ignition device and ignites it to achieve stratified combustion, while at high loads it supplies fuel dispersed within the combustion chamber and ignites it uniformly. 1. A stratified air intake engine that performs combustion, characterized in that during deceleration operation, the opening area of an intake passage is reduced by an intake throttle means.