JPH09310632A - Stratified gas intake engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stratified gas intake engine capable of reducing fuel consumption under low load by means of lean combustion based on stratified combustion, while outputting high power under high load by means of uniform combustion, also securing exhaust gas cleaning performance in the case of deceleration. SOLUTION: This engine is provided with fuel supplying means 11, 13, an ignition device 8, and an intake amount controlling mean 14, wherein fuel is supplied in such a manner that in the case of low load, combustible gas mixture being deviated around an ignition device will cause stratified combustion, while in the case of high load, the combustible gas being dispersed in a whole combustion chamber will cause uniform combustion. Further, a controlling means 16 for controlling an intake amount controlling means 14 is provided wherein in the case of low load, the amount of intake air supplied into the combustion chamber is set to have the air exess ratio greater than 1 under low load, the amount of the intake air to be supplied into the combustion chamber is reduced at least in the case of deceleration wherein fuel supply is stopped.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a stratified charge engine.

[0002]

2. Description of the Related Art Conventionally, for the purpose of improving fuel efficiency and emission of an engine, only fuel necessary for ignition among fuels supplied to a combustion chamber according to a load is unevenly distributed near an ignition device. A stratified charge engine capable of realizing a lean burn as a whole by performing a stratified combustion with an improved ignitability by enriching the air-fuel ratio of only a portion thereof is disclosed in
It is known as seen in JP-A No. 9-62807, JP-A-49-128109 and JP-A-51-1816.

[0003]

However, in the above stratified charge engine, stratified combustion is performed at a low load, and the opening area of the intake passage is made large during deceleration operation as in the case of low load. If so, there is a problem that the catalyst device provided in the exhaust passage is overcooled and exhaust purification performance becomes insufficient.

That is, in a high load state, the fuel is dispersed and supplied to the entire combustion chamber in order to improve the output, and uniform combustion is performed. In a low load state, the fuel is supplied unevenly around the ignition device in order to improve the fuel efficiency. In addition, the stratified combustion that realizes the lean combustion by increasing the opening area of the intake passage is performed.However, if the same control as that at the time of the low load is performed during the deceleration operation, the fuel supply is stopped during the deceleration operation. Frequently, only air passes through the catalyst device in the exhaust passage, and the catalyst device is supercooled to a reaction temperature or lower, and a problem arises in that sufficient purification performance cannot be obtained.

In view of the above circumstances, the present invention achieves good fuel economy and output performance by performing stratified combustion at low load and performing uniform combustion at high load.
It is an object of the present invention to provide a stratified intake engine with improved exhaust purification performance by preventing supercooling of a catalyst device during deceleration operation.

[0006]

The stratified charge engine of the present invention is provided with an open chamber-shaped combustion chamber having no auxiliary chamber, a fuel supply means for supplying fuel into the combustion chamber, and a combustion chamber. An ignition device and intake air amount adjusting means for adjusting the amount of intake air supplied into the combustion chamber by an actuator are provided, and when the load is low, fuel is supplied from the fuel supply means so that the combustible mixture is unevenly distributed around the ignition device. In this way, stratified combustion is carried out, and at the time of high load, uniform combustion is carried out by supplying fuel so that the combustible air-fuel mixture is dispersed throughout the combustion chamber and igniting. The amount of intake air supplied is set so that the excess air ratio λ is greater than 1, and at least during deceleration when the fuel supply is stopped, the amount of intake air supplied into the combustion chamber. It is characterized in further comprising control means for controlling the intake air quantity adjusting means so that less.

It is preferable that the control means controls the intake air amount adjusting means so that the intake air amount decreases when the accelerator is returned. Further, the control means controls the intake air amount adjusting means such that the intake air amount at the time of deceleration is smaller than the intake air amount at the time of idling when the accelerator is returned as in the deceleration. preferable. Further, it is preferable that the control unit controls the intake air amount adjusting unit so that the intake air amount is reduced when the engine is cold and the load is low as in the deceleration.

At a normal low load, stratified combustion is performed and the opening area of the intake passage is increased so that the excess air ratio is λ = 1.
On the other hand, lean combustion is performed so as to be larger than that, and at the time of high load, the output is increased by performing uniform combustion with an increased fuel injection amount. Further, at least at the time of deceleration when the fuel supply is stopped, the amount of intake air is reduced to suppress a decrease in the temperature of the catalyst device.

[0009]

According to the present invention, in the low load range,
While performing stratified combustion with fuel supplied so that the combustible air-fuel mixture is unevenly distributed around the ignition device in the combustion chamber, the intake air amount is increased to dilute the air-fuel ratio, and fuel economy is improved by lean combustion, while high load operation is performed. In the region, the fuel is supplied so that the combustible air-fuel mixture is dispersed throughout the combustion chamber, and uniform combustion is performed, so that good high-power operation can be ensured without generation of smoke.

Further, even in the low load state where the intake air amount is increased as described above, the intake air amount is reduced at least at the time of deceleration when the fuel supply is stopped, and the air amount passing through the catalyst device of the exhaust system is reduced. This prevents the catalyst device from being supercooled below the reaction temperature by cooling with air without fuel, and ensures good purification performance.

Further, in the case where the intake air amount is reduced when the accelerator is returned, the fuel is supplied to the extent that the engine speed can be self-excited in a no-load state at the time of idling. Therefore, even in the low load range, the catalyst heating effect is low due to the small amount of fuel supplied and the small amount of heat generation, and it will rather cool when the air-fuel ratio is lean, but the amount of intake air must be reduced. By shifting the air-fuel ratio to the rich side, the combustion temperature rises and it is possible to prevent cooling of the catalyst device.

Further, in the case where the amount of intake air during deceleration is smaller than that during idling, the fuel supply is stopped more frequently during deceleration, and overcooling of the catalyst becomes more problematic than during idling. The amount of intake air can be reduced to ensure the purification performance.

On the other hand, when the engine is cold, the intake air amount is made small even in the low load state as in the case of the deceleration. If the intake air amount is reduced, the air-fuel ratio is made rich and a large amount of intake air is generated. It is possible to suppress the cooling and raise the catalyst temperature to activate the catalyst, and obtain good exhaust gas purification performance.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. This embodiment is shown in FIGS. 1 to 5 and shows an example in which the fuel supply means is constituted by a first fuel supply means for stratification and a second fuel supply means for dispersion.

In the engine shown in FIG. 1, reference numeral 1 denotes a general open-chamber combustion chamber having no sub-chamber formed above a piston 2. Reference numeral 3 denotes an intake passage for introducing intake air into the combustion chamber 1. Denotes an exhaust passage for discharging exhaust gas from the combustion chamber 1, 5 denotes an intake valve, 6 denotes an exhaust valve, and 7 denotes a catalyst device provided in the exhaust passage 4.

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

On the other hand, a second fuel supply means 13 is provided in the intake passage 3 by a dispersion fuel injection nozzle 12 for dispersing and supplying fuel into the combustion chamber 1. Further, a throttle valve 14 is provided downstream of the dispersion fuel injection nozzle 12, and an actuator 15 for electrically opening and closing the throttle valve 14 (not linked to the accelerator operation).
Is provided to form an intake air amount adjusting means 20 for controlling the opening area of the intake passage 3 to regulate the amount of intake air.

As shown in FIG. 2, the downstream side portion of the intake passage 3 is formed to be curved so that intake air is introduced from a tangential direction of the combustion chamber 1 and a swirl S along the circumferential direction is introduced into the combustion chamber 1. The swirl port is formed, and the swirl causes the ignition fuel supplied from the stratification fuel injection nozzle 9 of the first fuel supply means 11 and ignited by the ignition device 8 to be sufficiently mixed with the air, and the flame is burned. The fuel is propagated to the entire chamber 1 to sufficiently burn the entire injected fuel.

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

The control means 16 receives a load signal from a load detecting means 17 for detecting a required load of the engine by, for example, an accelerator sensor, and a detection signal from a water temperature sensor 18 for detecting when the engine is cold, for example, by a cooling water temperature. At the same time, it receives the engine rotation signal from the engine rotation sensor 19 and controls the fuel injection amount and the fuel injection timing from the stratification fuel injection nozzle 9 and the fuel injection amount from the dispersion fuel injection nozzle 12, respectively. 14 to control the closing operation timing.

The control means 16 operates the intake air amount adjusting means 20 to close the throttle valve 14 and reduce the intake air amount when the cooling water temperature is equal to or lower than the set value and the engine is cold in response to the detection signal of the water temperature sensor 18. At the same time, the second fuel supply means 13 supplies a predetermined amount of dispersed fuel.

The fuel supply amount control corresponding to the load by the control means 16 receives the signal of the load detection means 17 and uses the second fuel supply means 13 in a normal operation range in a low / medium load range below a set load. The supply of the dispersed fuel is stopped, the stratified fuel is supplied by the first fuel supply means 11 to perform stratified combustion, and the supply amount is increased in accordance with the increase in the load. When the load exceeds the set load, the supply amount of the stratified fuel is reduced. It is to decrease. On the other hand, the dispersed fuel by the second fuel supply means 13 starts to be supplied at a load equal to or higher than the load in the vicinity of the set load, compensates for the decrease in the amount of the stratified fuel by the first fuel supply means 11, and provides a total supply according to the increase in the load. The amount of the dispersing fuel is increased so that the amount increases, and the stratified combustion shifts to uniform combustion. At this time, the injection amount and the number of injections for each injection are set in accordance with the engine speed.

In other words, the first corresponding to the engine load
The fuel supply amount control by the fuel supply means 11 and the second fuel supply means 13 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 in the fully opened state, the intake air amount is constant, and the load increases. However, the fuel supply amount Q is increased to reduce the excess air ratio λ, that is, the air-fuel ratio is increased to perform output control. In the fuel supply amount Q, the fuel in the region I is supplied from the first fuel supply means 11, and the fuel in the region II is supplied from the second fuel supply means 13. First fuel supply means 1
The supply of the stratified fuel according to 1 increases with an increase in the load below the set load at the point A, whereas when the load exceeds the set load A, the fuel supply from the first fuel supply means 11 decreases,
At the time of a high load exceeding the point B, a small amount of injection is continued to prevent the stratification fuel injection nozzle 9 from being clogged with carbon and from being heated.

On the other hand, the supply of the 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 further, the decrease in the supply of the stratified fuel by the first fuel supply means 11 is compensated for. At the same time, it supplies the increased fuel in response to the increase in the load as a whole.

The load set at the point A is set so that the excess air ratio λ at that time is equal to or less than the ignition limit excess air ratio λ at which even a homogeneous mixture can be ignited. Is set to a load state in which the excess air ratio λ at that time becomes equal to or higher than the excess air ratio λ at which the air utilization rate decreases due to the stratified combustion and smoke starts to be generated.

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

The start timing of the supply of the dispersed fuel by the second fuel supply means 13 does not coincide with the set load A point at which the supply of the stratified fuel by the first fuel supply means 11 is reduced. The supply may be started under the changed load state.

The switching between the stratified fuel supply by the first fuel supply means 11 and the dispersed fuel supply by the second fuel supply means 13 is made to gradually decrease and increase as described above. In a load state between the points, it may be switched on and off.

Next, FIG. 4 shows the injection timing (injection start timing) of the stratified fuel by the first fuel supply means 11 with respect to the load fluctuation.
In the region where stratification is performed below the set load at the point A, the injection timing is set to a timing earlier than the ignition timing near the compression top dead center by a predetermined amount, and the injected fuel is set to the ignition device 8. Ignition is performed in a state where it is effectively unevenly distributed around. The injection timing is advanced and the injection is performed at an earlier timing as the transition to the area where the dispersion of the point B is performed beyond the point A is performed.
The uneven distribution of the fuel injected from the fuel supply means 11 is reduced so that the fuel is dispersed throughout the combustion chamber 1. In addition, when the load is extremely low such as during idling, the fuel injection timing and the ignition timing are slightly advanced from those in the stratified combustion to improve the stability.

When the engine is cold, the second
Instead of supplying the dispersed fuel by the fuel supply means 13,
By advancing the fuel injection timing by the first fuel supply means 11 in the same manner as at the time of the high load, the injection is completed at an early timing from the intake stroke to the early stage of the compression stroke, and the intake air in the combustion chamber 1 thereafter is completed. The fuel may be dispersed by the flow of the air to obtain uniform combustion.

In FIG. 4, the ignition timing is set to be substantially constant with respect to the load fluctuation. However, the ignition timing may be changed so that the ignition timing is advanced in accordance with an increase in the load.

On the other hand, the opening / closing control of the throttle valve 14 of the intake air amount adjusting means 20 by the control means 16 is basically a non-throttle operation with the throttle valve 14 fully opened, as shown in FIG. Alternatively, when the load is extremely low such as during idling, the opening degree is reduced to reduce the amount of intake air.

When the engine is cold, as shown by the dashed line in FIG. 5, the throttle is narrowed over a wide range in a low / medium load region. As the load decreases, the opening degree is reduced to reduce the intake air amount. Thus, the excess air ratio is reduced and the air-fuel ratio is made rich.

In addition to the above control, the control means 16 closes the throttle valve 14 during deceleration when the fuel supply is stopped in order to prevent the catalyst temperature from decreasing and to improve the engine braking performance. Is controlled as follows.

Therefore, according to the stratified charge engine of the above embodiment, in the normal operation region at a low / medium load equal to or less than the set load A point, stratified combustion is performed to obtain good ignitability, and the excess air ratio λ In the stratified region, the intake air amount is kept constant without closing the throttle valve 14, and the output control is performed by the fuel supply amount by the first fuel supply means 11 at the same time. Is performed, the pumping loss accompanying the throttle operation of the throttle valve 14 can be significantly reduced, and the fuel efficiency is further improved.

In the high-load operation range exceeding the set load A point, the stratified combustion shifts to the uniform combustion, the air utilization is increased, and the high-output operation is performed without generating smoke. Good driving performance can be achieved in all areas, and fuel efficiency can be improved by reducing pumping loss.

Further, when the engine is cold, the fuel is supplied by the second fuel supply means 13 for dispersing and supplying the fuel to the entire combustion chamber, or the fuel injection timing by the first fuel supply means 11 is advanced to make the fuel chamber 1 In addition, uniform combustion is performed so that the fuel supplied to the fuel is dispersed, and the throttle valve 14 is closed by the intake air amount adjusting means 20 to reduce the amount of intake air, thereby enriching the air-fuel ratio of the dispersed fuel. Is secured.

In the above embodiment, the dispersing fuel injection nozzle 12 is interposed in the middle of the intake passage 3, but may be disposed so as to open into the combustion chamber 1. The injection timing of the dispersed fuel directly supplied to the combustion chamber 1 is
The injection is set to be completed between the intake stroke and the initial stage of the compression stroke.
The uniform combustion is achieved by uniformly dispersing the particles in the inside.

Further, in the above-described embodiment, the amount of reduction in the amount of intake air by the intake air amount adjusting means 20 or the degree of equalization tendency due to advance of the injection timing is changed and adjusted according to the cooling water temperature, that is, the degree of the engine cold state. The intake air amount may be increased as the temperature rises, and the stratified combustion may be returned.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a stratified charge engine according to one embodiment of the present invention.

FIG. 2 is a plan view schematically showing a combustion chamber in the example of FIG.

FIG. 3 is a characteristic diagram showing control of a fuel supply amount with respect to a load in the example of FIG. 1 together with an excess air ratio.

FIG. 4 is a characteristic diagram showing stratified fuel injection timing and ignition timing by a first fuel supply unit with respect to a load change in the example of FIG. 1;

FIG. 5 is a characteristic diagram showing an opening degree of a throttle valve with respect to a load change in the example of FIG. 1;

[Explanation of symbols]

 1 Combustion Chamber 3 Intake Passage 8 Ignition Device 9 Stratified Fuel Injection Nozzle 10 Fuel Injection Pump 11 First Fuel Supply Means 12 Dispersion Fuel 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 amount adjustment means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Haruo Okimoto 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. In the company

Claims (4)

[Claims] 1. A combustion chamber in the form of an open chamber having no sub chamber, and fuel supply means for supplying fuel into the combustion chamber,
An ignition device arranged in the combustion chamber and an intake air amount adjusting means for adjusting the intake air amount supplied to the combustion chamber by an actuator are provided, and the combustible air-fuel mixture is unevenly distributed around the ignition device from the fuel supply means when the load is low. A stratified charge engine that performs uniform combustion by supplying and igniting fuel so that the combustible mixture is dispersed throughout the combustion chamber at high load Therefore, when the load is low, the amount of intake air supplied into the combustion chamber is set so that the excess air ratio λ is greater than 1, and
A stratified charge engine comprising control means for controlling the intake air amount adjusting means so that the amount of intake air supplied to the combustion chamber is reduced at least during deceleration when fuel supply is stopped. 2. The stratified charge engine according to claim 1, wherein the control unit controls the intake air amount adjusting unit so that the intake air amount decreases when the accelerator is returned. 3. The control means controls the intake air amount adjusting means such that the intake air amount during the deceleration is smaller than the intake air amount during the idle time when the accelerator is returned as in the deceleration. The stratified charge engine according to claim 1, wherein 4. The control means, when the engine is cold,
The stratified charge engine according to claim 1, wherein the intake air amount adjusting means is controlled so that the intake air amount is reduced even when the load is low as in the deceleration.