JPH0799105B2 - Stratified combustion control system for engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stratified combustion control device for an engine that stratifies the combustion chamber so that the combustible mixture is unevenly distributed around a spark plug in the combustion chamber and burns the mixture. Regarding the improvement of.

(Prior Art) Conventionally, as a stratified charge combustion control device for this type of engine, for example, as disclosed in JP-A-60-36721, the operating state of the engine is detected, and at the time of low load operation,
By reducing the amount of fuel supplied to the combustion chamber and supplying this fuel to the combustion chamber at the set timing in the latter half of the compression stroke, the combustible mixture is unevenly distributed around the spark plug in the combustion chamber.
Performs stratified combustion of the air-fuel mixture to increase the air-fuel ratio of the air-fuel mixture as a whole (lean) to improve fuel economy and stop the above-mentioned stratified combustion when the engine is operating under high load, and adjust it according to the operating conditions. By supplying a certain amount of fuel to the combustion chamber at the set time in the first half of the intake stroke and evenly dispersing the combustible mixture in the combustion chamber, uniform combustion of the mixture is performed,
It is known to ensure an increase in the output.

(Problems to be Solved by the Invention) However, as described above, in the case of performing stratified combustion and uniform combustion of the air-fuel mixture according to the operating state of the engine, in particular, the combustion switching between these two combustions is closely examined. In addition, the fuel supply timing is in the latter half of the compression stroke during stratified combustion, and is in the first half of the intake stroke during uniform combustion, and there is a time difference between the two. Due to this relationship, when the engine operating state shifts from a high load state (uniform combustion region) to a low load state (stratified combustion region) during the time lag between the two, fuel for uniform combustion is given to a predetermined cylinder. Is supplied, the fuel is switched to the stratified charge combustion, the fuel for the stratified charge combustion is supplied to the predetermined cylinder, and the air-fuel ratio of the air-fuel mixture becomes overrich. On the other hand, on the contrary, when the low load state (stratified combustion region) shifts to the high load state (uniform combustion region), the supply of the stratified combustion fuel is stopped as soon as the uniform combustion fuel is not supplied, This leads to over leaning of the air-fuel ratio, and as a result, torque fluctuations occur, and the engine performance deteriorates accordingly.

The present invention has been made in view of these points, and an object thereof is to set fuel supply for uniform combustion (for example, the first half of the intake stroke) when performing stratified combustion and uniform combustion of a mixture as described above. By delaying the execution of the fuel supply switching between the homogeneous combustion fuel and the stratified combustion fuel when the operating range is changed during the set supply time of the stratified combustion fuel (the latter half of the compression stroke). Effectively preventing the occurrence of air-fuel ratio overrich and over lean, and when changing this operating range,
The purpose is to effectively suppress torque shock and improve engine performance.

(Means for Solving Problems) In order to achieve the above object, the solution means of the present invention is an engine that performs stratified combustion and uniform combustion of an air-fuel mixture according to the operating state of the engine, that is, in FIG. As shown, when the engine operating state is in the first operating range such as the low load operating range, the fuel is taken in when receiving the operating state detecting means 34 for detecting the operating state of the engine and the output of the operating state detecting means 34. Stratified combustion means 41 for performing stratified combustion of the air-fuel mixture by supplying around the ignition plug of the combustion chamber at the set fuel supply timing for stratified combustion set between the latter half of the stroke and the latter half of the compression stroke, and the operating state detecting means.
When the engine operating state is in the second operating range such as the high load operating range by receiving the output of 34, the fuel is supplied at the uniform combustion fuel supply timing (for example, the first half of the intake stroke) earlier than the set stratified combustion fuel supply timing. It is premised on a stratified combustion control system for an engine, which is provided with a uniform combustion means (41) for supplying the entire mixture to the combustion chamber and performing uniform combustion of the mixture. Then, the operating state detection means 34
When the operating range between the first operating range and the second operating range is changed, the set uniform combustion fuel supply timing (the first half of the intake stroke) to the set stratified combustion fuel supply timing (the second half of the compression stroke) Driving range change detection means to detect when
42 and the output of the operating range change detecting means 42, and switching of the fuel supply between the supply of the fuel for stratified combustion by the stratified combustion means 40 and the supply of the fuel for uniform combustion by the uniform combustion means 41. The configuration includes a switching delay unit 43 that delays execution.

(Operation) According to the present invention, in the present invention, in the first operating region such as the low load operating region of the engine, the fuel is set by the stratified combustion means 40 between the latter half of the intake stroke and the latter half of the compression stroke. Since the combustible mixture is unevenly distributed around the ignition plug of the combustion chamber when it is supplied at the supply timing, and stratified combustion of the mixture is performed in this state, the air-fuel ratio of the mixture becomes large as a whole and fuel consumption is improved. In the second operating region such as the high load operating region of the engine, the uniform combustion means 41 causes the fuel to be set earlier than the set stratified combustion fuel supply period (for example, the first half of the intake stroke). ), The fuel is uniformly dispersed and supplied to the entire combustion chamber, and the air-fuel mixture is uniformly burned in this state, so that an increase in engine output is ensured.

Then, at the time of transition from the first operation range (for example, low load operation range) to the second operation range (for example, high load operation range), basically, stratified combustion of the air-fuel mixture is switched to uniform combustion, but this second operation range is used. During the transition to the operating range, particularly during the period from the above-mentioned set uniform combustion fuel supply timing (for example, the first half of the intake stroke) to the set stratified combustion fuel supply timing (for example, the latter half of the compression stroke), the stratified combustion fuel is uniformly burned. The execution of the switching of the fuel supply to the fuel for use is controlled by the switching delay means 43 so that the supply of the fuel for the stratified charge combustion is appropriately continued, so that the over lean of the air-fuel ratio is prevented.

Similarly, at the time of transition from the second operation range (for example, high load operation range) to the first operation range (for example, low load operation range), basically, homogeneous combustion of the air-fuel mixture is switched to stratified combustion, but this first operation range is used. During the transition to the operating range, particularly during the period from the above-mentioned set uniform combustion fuel supply timing (the first half of the intake stroke) to the set area stratified combustion fuel supply timing (the latter half of the compression stroke), the combustion fuel is uniformly stratified combustion. The execution of the fuel switching to the commercial fuel is delayed and controlled by the switching delay means 43, and the overlap of the fuel supply is prevented, so that the overrich of the air-fuel ratio is prevented. As a result, even when the operating range is changed between the first operating range and the second operating range, the occurrence of torque shock due to air-fuel ratio overrich or over lean is prevented, and engine performance is improved.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows the overall structure of a stratified charge combustion control system for an engine according to the present invention, where 1 is an engine, 2 is a piston 3 which is slidably inserted in a cylinder 3 of the engine 1, and a recess 2a is formed on the top, Reference numeral 4 denotes a combustion chamber formed by the piston 2 so that the volume thereof is variable. One end of the combustion chamber 5 communicates with the atmosphere through an air cleaner 6, and the other end opens into the combustion chamber 4 to intake air from the engine 1
An intake passage 7 for supplying the exhaust gas to the combustion chamber 4, one end of which is open to the combustion chamber 4 and the other end of which is an exhaust passage for discharging exhaust gas to the atmosphere. Is provided with a throttle valve 9 for controlling the amount of intake air, and the throttle valve 9 and the downstream side of the surge tank 8 are for uniformly distributing and injecting fuel into the combustion chamber 4 for injection and supply. A fuel injection valve 10 for uniform combustion is provided. Further, at the top of the combustion chamber 4, the recess 2a of the piston 2 is provided.
A spark plug 11 that ignites the air-fuel mixture in the combustion chamber 4 facing the
And a fuel injection valve 12 for stratified combustion in which fuel is injected and supplied toward the recess 2a of the piston 2.
The fuel injected from 12 is reflected by the recess 2a of the piston 2 so that the fuel is unevenly distributed only around the spark plug 11 in the combustion chamber 4. In the figure, 15 is an intake valve disposed at the opening of the intake passage 5 to the combustion chamber 4, and 16 is the exhaust passage 7.
An exhaust valve disposed at the opening of the combustion chamber 4 and a catalyst device 17 disposed in the exhaust passage 7 for purifying exhaust gas.

A stepper motor 20 for adjusting the opening of the throttle valve 9 is connected to the throttle valve 9, and the fuel injection valve 10 for uniform combustion is connected to the fuel injection valve 10 for uniform combustion. Regulator to regulate fuel pressure to 21
A fuel pump 22 is connected via the fuel injection valve 12 for stratified charge combustion, and an injection pump 23 for supplying fuel to the fuel injection valve 12 for stratified charge combustion is connected to the fuel injection valve 12 for stratified charge combustion. An ignition coil 24 is connected to the ignition plug 11.

Further, 28 is a load sensor that detects the load state of the engine 1, 29 is a rotation speed sensor that detects the engine speed, and 30 is a predetermined angular position of the crankshaft of the engine 1 (for example, the piston top dead center position of a predetermined cylinder). TD that detects the reference position
C sensor, 31 is a water temperature sensor that detects the engine cooling water temperature, 32 is an intake air temperature sensor that detects the temperature of intake air, and 33 is an accelerator pedal opening sensor that detects the opening of an accelerator pedal (not shown). The load sensor 28 and the rotation speed sensor 29 constitute an operating state detecting means 34 for detecting the operating state of the engine 1.

The detection signals of the above six sensors 28 to 33 are CP
It is input to the controller 35 that contains U, RAM, etc.
The controller 35 controls the stepper motor 20, the fuel injection valve 10 for uniform combustion, the injection pump 23, and the ignition coil 24, respectively, and controls the throttle valve opening, the fuel amount during uniform combustion, the injection timing, and the stratified combustion time. The fuel amount, the injection timing, and the ignition timing of the air-fuel mixture are adjusted.

Next, the operation of the controller 35 will be described based on the control flow of FIGS. 3 to 5. First, starting from the control flow of FIG. 3, the injection quantity correction coefficient k in step S ₁ in the "1" value, also after were each reset stratified zone flag to OFF, the six sensors 28 in step S ₂ .. 33 (load, engine speed Ne, crank angle, cooling water temperature, intake air temperature and accelerator pedal opening β) and the opening α of the throttle valve 9 are input, and in step S ₃ a uniform combustion is performed. The start timing Ch of the fuel injection from the fuel injection valve 10 is calculated, for example, in the first half of the intake stroke based on the injection timing map for uniform combustion, and the injection period τh of the fuel for uniform combustion is calculated.
(Injection amount) is calculated to an amount corresponding to the accelerator pedal opening β based on the injection amount map for uniform combustion, and the start timing Cs of fuel injection from the fuel injection valve 12 for stratified charge combustion is calculated for the stratified charge combustion. Based on the injection timing map, calculation and setting are performed during the latter half of the intake stroke and the latter half of the compression stroke (for example, the latter half of the compression stroke), and the injection period τs (injection quantity) of the stratified charge fuel is injected into the stratified charge injection quantity map. Based on the above, the amount is calculated according to the accelerator pedal opening β.

Thereafter, stratified area flag to determine whether ON in step S _4, when in the stratified zone ON, in order to determine whether or not the engine operating region is changed, at step S _5, 6 As shown in the figure, whether the engine is in the uniform combustion range as the second operation range or not is determined by the engine speed Ne and the accelerator pedal opening β.
It determined based on the bets, when not in the homogeneous combustion zone, it is determined to be in the stratified combustion region as a first operating range of the engine, setting the injection start timing of the stratified combustion fuel in step S ₆ C
Wait for s (fuel supply time for set stratified combustion),
In step S ₇ , the fuel amount τs for stratified combustion is injected and supplied from the fuel injection valve 12 in the combustion chamber 4, and the process returns to step s ₂ .

On the other hand, when in the homogeneous combustion zone in step S _5, it is determined that the time of transition to the homogeneous combustion zone from the stratified combustion region, first, the injection start timing of the homogeneous combustion fuel Ch (set uniformly at Step S ₈ (Fuel supply timing for combustion), and if YES, which is the set injection start timing Ch for uniform combustion fuel, it is determined that the air-fuel ratio will not change even if the fuel is switched immediately. the homogeneous combustion fuel quantity τh at step S ₉ and injected and supplied from the fuel injection valve 10 of the intake passage 5, then, in order to understand that it is in the homogeneous combustion zone in step S _10, the stratified zone flag oF
Set to F and return to step S ₂ above.

On the other hand, if NO at step S ₈ that is not the injection start timing Ch of the uniform combustion fuel, then at step S ₁₁ , it is further determined whether or not it is the set injection start timing Cs of the stratified charge fuel,
When the injection timing Cs of the stratified combustion fuel is YES, the setting of the uniform combustion fuel is performed when the stratified combustion region is changed to the uniform combustion region. The stratified combustion fuel is set from the injection start timing (the first half of the intake stroke) Ch. it is determined that came time to injection start timing (the latter half of the compression stroke) Cs, in order to prevent over-lean air-fuel ratio, still injecting fuel quantity τs for the stratified combustion from the fuel injection valve 12 of the combustion chamber 4 at step S ₁₂ supplied, then waiting to become injection timing Ch homogeneous combustion fuel in step S _13, the uniform combustion fuel quantity τh from the fuel injection valve 10 of the intake passage 5 and injected and supplied in step S _14, step stratified area flag to OFF in S _10, the flow returns to step S _2.

On the other hand, when the stratified area flag in step S ₄ is in the homogeneous combustion zone of OFF, the process proceeds to step S _15, the step S ₁₅
In as shown in FIG. 6, it is determined whether the homogeneous combustion zone, in the case of YES in the homogeneous combustion region, it is determined that no situations change operation range, the injection amount at step S ₁₆ Correction coefficient K
After setting (described later) to "1" value, waiting to be injection start timing Ch homogeneous combustion fuel in step S _17, fuel homogeneous combustion from the fuel injection valve 10 of the intake passage 5 at step S ₁₈ The amount τh is injected into the combustion chamber 4, and the process returns to step S ₂ .

In the case of N0 is not in homogeneous combustion zone in step S _15, it is determined that the time of transition to the stratified combustion region from the homogeneous combustion zone,
Both injection valves for stratified combustion and uniform combustion during this transition 1
In order to appropriately set the injection amounts τh and τs from 0 and 12, the routine proceeds to the uniform → stratification transition routine of FIG.

That is, in the uniform-to-stratified transition routine of FIG. 4, the uniform combustion and the stratified combustion are gradually switched to gradually decrease the uniform fuel amount τh and simultaneously increase the stratified combustion fuel amount τs. First, in step S _T1 , the uniform combustion fuel amount τh and the stratified combustion fuel amount τs are set to the injection amount correction coefficient k.
Based on the equations τh = τh × k, τs = τs × (1-
k), and the injection amount correction coefficient k is initially "1", so the corrected uniform combustion fuel amount τh is the same value as before correction, and the stratified charge fuel amount τs is zero. .

Then, in step S _T2 , it is determined whether or not the set injection start timing Ch of the uniform combustion fuel is in the first half of the intake stroke, and in step S _T3 the set injection start timing Cs of the fuel for stratified combustion is in the second half of the compression stroke.
If the set injection timing Ch of the fuel for uniform combustion comes first, the fuel amount τh for uniform combustion is injected from the injection valve 10 of the intake passage 5 in step S _T4 , and then the step After waiting for the injection start timing Cs of the fuel for stratified combustion at S _T5 , the fuel amount τs for stratified combustion is set to the combustion chamber 4 at step S _T6.
It is injected from the fuel injection valve 12 of.

On the other hand, in the case where the injection start timing Cs of the fuel for stratified charge combustion first comes in step S _T3 , contrary to the above, step S
_The fuel amount τs for stratified charge combustion is injected from the injection valve 12 of the combustion chamber 4 at _T7 , and thereafter, at step S _T8 , until the injection start timing Ch of the fuel for uniform combustion is _reached , at step S _T9 for uniform combustion The fuel amount τh is injected from the injection valve 10 in the intake passage 5.

After the fuel for uniform combustion and the fuel for stratified combustion are continuously injected in this way, the fuel amount for uniform combustion for the next time τh
So that the fuel quantity for stratified charge combustion τs is increased, the value of the injection quantity correction coefficient k is compared with a small value γ in step _ST10. If YES when k ≧ γ, the injection quantity correction coefficient k returning to step S _T1 by subtracting a value by a small value gamma, the homogeneous combustion fuel quantity τh is correspondingly reduced, the amount of fuel τs for the stratified combustion repeated to correspondingly increase. On the other hand, in the case of k <gamma is almost zero value uniform combustion fuel quantity .tau.h, it is determined that Tsu completely switched to stratified combustion, ON the stratified area flag in step S _T12, returns .

At the same time as the above fuel amount correction, the opening of the throttle valve 9 is appropriately corrected based on the throttle valve opening correction routine of FIG. 5, and in step S _S1 , the target throttle valve opening during stratified combustion is set. (Fully open) αs and target throttle valve opening αh according to accelerator pedal opening β during uniform combustion
After calculating based on the bets to the target throttle valve opening degree map of FIG. 7, based on the target throttle valve opening TVO during the fuel amount correction the target opening .alpha.s, the αh and injection quantity correction coefficient k in step S _s2 In accordance with the equation TVO = αs-k (αs-αh), the target throttle valve opening TVO is gradually increased in accordance with the decrease of the injection amount correction coefficient k, that is, the increase of the stratified combustion amount τs.
When the value of the throttle valve opening α is sampled in step S _S3 and the deviation | TVO−α | between the target throttle valve opening TVO and the actual value α falls within the range of the minute value a in step S _S4 , the return is made. To do.

Therefore, in the control flow of FIG. 3, steps S _{3 to} S ₇
Thus, when the engine operating condition is in the stratified charge combustion region, the set injection start timing Cs of the fuel for stratified charge combustion (the latter half of the compression process)
The injection pump 23 is controlled by the set injection start timing Cs.
The stratified charge combustion means 40 is configured to supply the fuel for stratified charge combustion of the combustion amount τs from the injection valve 12 in the combustion chamber 4 so as to be unevenly distributed around the ignition plug 11 of the combustion chamber 4 to perform the stratified charge combustion of the air-fuel mixture. is doing. Also, by steps S ₃ , S ₄ , S _{15 to} S ₁₈ ,
When the engine operating condition is in the uniform combustion region, the set injection start timing Ch (first half of the intake stroke) of the fuel for uniform combustion earlier than the preset injection start timing Cs (second half of the compression stroke) of the fuel for stratified combustion is set. A uniform combustion means 41 is configured to control the injection valve 10 and supply fuel so as to be uniformly dispersed in the entire combustion chamber 4 at the set injection timing Ch so as to perform uniform combustion of the air-fuel mixture.

Furthermore, steps S ₄ , S ₅ , S ₈ , S of the control flow of FIG.
₁₁ and S ₁₅ and steps S _T2 and S _T3 of the uniform-to-stratification transition routine of FIG. 4 are performed during the transition from the stratified combustion region to the uniform combustion region of FIG. 6 and in the opposite direction, that is, stratified combustion. At the time of changing the operating range between the region and the uniform combustion region, from the set injection start timing Ch of the uniform combustion fuel (first half of the intake stroke) to the set injection start timing Cs of the stratified charge fuel (second half of the compression stroke). The operation range change time detection means 42 is configured to detect the time when the time comes. In addition, by the steps S _{11 to} S ₁₄ of the control flow of FIG. 3 and the steps S _T7 and S _T11 of the uniform → stratification transition routine of FIG. At the time of transition from the region to the uniform combustion region, at the subsequent set injection start timing Cs of the fuel for stratified combustion (second half of the compression process), the fuel amount τs for stratified combustion is still output from the injection valve 12 (stratified combustion means 40) of the combustion chamber 4. After injection, the next set injection start timing Ch for the fuel for uniform combustion
In the first half of the intake stroke, the fuel for uniform combustion having the fuel amount τh is injected at this time into the injection valve 10 (uniform combustion means 4) in the intake passage 5.
From 1), the fuel supply switching from stratified charge fuel to homogeneous burn fuel is delayed by the injection of the fuel for stratified charge combustion, while conversely from homogeneous burn region to stratified burn region. At the time of transition, while the uniform combustion fuel and the stratified charge fuel are both injected and supplied, the uniform combustion fuel amount τh is gradually reduced, and at the same time, the stratified charge fuel amount τs is gradually increased from the uniform combustion fuel. The switching delay means 43 is configured to delay the execution of the injection switching to the stratified combustion fuel.

Although not shown, when the stratified combustion fuel amount τs from the fuel injection valve 12 in the combustion chamber 4 is small, the valve opening pressure of the injection valve 12 is lowered to perform the stratified combustion in the combustion chamber 4. When the knocking of the engine 1 is detected in the stratified combustion region, the injection start timing Cs of the stratified combustion fuel is slightly advanced to form stratification. By lowering the degree of knocking, the occurrence of knocking is effectively suppressed.

Therefore, in the above-described embodiment, in the stratified combustion region of the engine operating state, as shown in FIG.
At the set injection start timing Cs of the fuel for stratified combustion in the latter half of the compression stroke where the pressure inside the fuel injection valve 12 in the combustion chamber 4 increases.
The fuel for the stratified charge combustion of the fuel amount τs is injected from around the ignition plug 11 of the combustion humidity 4 and combustible mixing is unevenly distributed around the ignition plug 11 by the stratified charge combustion means 40 in the state of a large air-fuel ratio. Since the stratified combustion of the air is performed, the fuel consumption amount is reduced and the fuel economy is improved.

Further, in the uniform combustion region of the engine, as shown in FIG. 6B, the uniform combustion fuel having the fuel amount τh at the set injection start timing Ch of the uniform combustion fuel in the first half of the intake stroke is the fuel injection valve of the intake passage 5. Since the combustible air-fuel mixture is injected from 10 into the combustion chamber 4 and the combustible air-fuel mixture is uniformly dispersed in the entire combustion chamber 4, uniform combustion of the air-fuel mixture is performed, so that an increase in engine output is ensured.

When the engine operating region is changed from the stratified combustion region to the uniform combustion region and vice versa, the transition time is as shown in FIGS. 9 and 10, respectively, as shown in FIG. 9 and FIG. When the period from Cs to the next homogeneous combustion fuel injection start timing Ch comes, the fuel for stratified charge combustion is immediately switched to the fuel for uniform combustion in FIG.
In Fig. 10, the fuel for uniform combustion is gradually switched to the fuel for stratified combustion, but in this case, the uniform combustion fuel amount τh and the stratified combustion fuel amount for the cylinder that is the first compression process in the uniform combustion region. The situation in which the total amount of τs does not overlap or neither fuel is supplied together does not occur, and the air-fuel ratio of the air-fuel mixture is favorably maintained at the set air-fuel ratio.

On the other hand, during the transition from the stratified combustion zone to the uniform combustion zone,
As shown in FIG. 11, when the period from the set injection start timing Ch of the uniform combustion fuel (first half of the intake stroke) to the set injection timing Cs of the fuel for stratified combustion (second half of the compression stroke) comes, The switching delay means 43 delays and adjusts the switching of the fuel supply until the injection of the stratified combustion amount τs is continued at the set fuel injection start timing Cso, and then the fuel is burned from the next set injection start timing Cho of the uniform combustion fuel. Since the supply is switched to the fuel for the uniform fuel, a combustible mixture is formed with the fuel amount τs for the stratified charge combustion even in the cylinder that is first in the compression stroke in the uniform combustion region, and the air-fuel ratio becomes over lean. Will be prevented.

Contrary to the above, the transition from the uniform combustion zone to the stratified charge combustion zone is performed from the set injection start timing Ch of the uniform combustion fuel to the set injection start timing Cs of the stratified charge fuel as shown in FIG.
When the fuel switching is executed immediately (in the conventional case), the uniform combustion fuel amount τh is injected from the set injection start timing Cho of the uniform combustion fuel immediately before the transition. The set injection start timing Cso of the fuel for stratified charge combustion immediately after the transition or the fuel amount τs for stratified charge combustion is injected, and both of these fuel amounts τh, τs are supplied to the cylinder that is the first compression process in the stratified charge combustion region, Although the air-fuel ratio of the air-fuel mixture becomes overrich, at this time, as shown in the figure, the fuel amount τh for uniform combustion and the fuel amount τs for stratified charge combustion are gradually switched to supply fuel to the fuel for stratified charge combustion. Since the execution of the switching is adjusted to be delayed, the air-fuel ratio does not become overrich, and the set air-fuel ratio is favorably maintained. Therefore, even when the operating range between the uniform combustion range and the stratified combustion range is changed, it is possible to prevent the occurrence of torque shock by preventing the air-fuel ratio overrich or over lean due to the overlap or complete cut of the fuel supply. It is possible to improve engine performance.

In the above embodiment, the fuel injection valve 12 for stratified charge combustion is arranged in the combustion chamber 4 as desired, but the fuel injection valve 12 for stratified charge combustion is arranged immediately upstream of the intake valve 15 in the intake passage 5. Of course, the fuel injection valve 12 for stratified combustion or the fuel injection valve 10 for uniform combustion may be used as the other injection valve. In this case, the uniform combustion of the air-fuel mixture can be performed by advancing the fuel injection timing, and the stratified combustion of the air-fuel mixture can be performed by delaying the fuel injection timing.

(Effects of the Invention) As described above, according to the stratified charge combustion control system for an engine of the present invention, the first stratified charge combustion of the engine is performed.
When changing the operating range between the operating range and the second operating range in which uniform combustion is performed, the fuel due to the time lag between the set supply timing of the stratified combustion fuel and the set supply timing of the uniform combustion fuel Since the torque shock is effectively suppressed by preventing the duplicated supply and the complete cut of the supply, it is possible to improve the engine performance.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 12 show an embodiment of the present invention, FIG. 2 is an overall configuration diagram, FIGS. 3 to 5 are flow charts showing the operation of the controller, respectively, and FIG. 6 is a stratified combustion region and uniform FIG. 7 is an explanatory view showing a combustion region, FIG. 7 is a view showing a target throttle valve opening characteristic with respect to an accelerator pedal opening, and FIGS.
FIG. 12 is a diagram for explaining the operation. 1 ... Engine, 10 ... Fuel injection valve for uniform combustion, 11 ...
… Spark plug, 12 …… Fuel injection valve for stratified combustion, 22 ……
Fuel pump, 23 …… Injection pump, 28 …… Load sensor, 29
...... Rotation speed sensor, 34 …… Operating state detecting means, 35 …… Controller, 40 …… Strategic combustion means, 41 …… Uniform combustion means, 42 …… Operating range change detection means, 43 …… Switching delay means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02D 41/04 335 C 41/34 C 9247-3G

Claims (1)

[Claims] 1. An operating state detecting means for detecting an operating state of an engine, and an output of the operating state detecting means. When the engine operating state is in a first operating range, fuel is fed from the latter half of the intake stroke to the latter half of the compression stroke. A stratified combustion means for performing stratified combustion of the air-fuel mixture by supplying around the ignition plug of the combustion chamber at a set fuel supply timing for stratified combustion, and an output of the operating state detection means, and the engine operating state is the second When in the operating range, the fuel is supplied to the entire combustion chamber at a uniform combustion fuel supply timing earlier than the set stratified combustion fuel supply timing to perform uniform combustion of the air-fuel mixture, and the operation is performed. When the output of the state detection means is received, the time when the operating range between the first operating range and the second operating range changes is between the set uniform combustion fuel supply timing and the set stratified combustion fuel supply timing. Driving to detect The fuel supply is switched between the supply of the fuel for stratified combustion by the stratified combustion means and the supply of the fuel for uniform combustion by the uniform combustion means in response to the output of the change detection means and the output of the operating range change detection means. A stratified combustion control system for an engine, comprising: a switching delay means for delaying execution.