JP2001082229A - Compression self-ignition gasoline internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To spread an operable range as improvement of suction filling efficiency and fuel consumption is achieved, in a compression self-ignition gasoline internal combustion engine. SOLUTION: A valve timing being minus overlap at which the closing timing of an exhaust valve is the middle of an exhaust stroke and the opening timing of a suction valve is the middle of a suction stroke and an exhaust valve and a suction valve are both closed is provided. During a time (a setting range S1 of a fuel injection timing) starting from an exhaust valve closing timing during a minus overlap period and ending to an exhaust top dead center, first fuel injection by a fuel injection valve is effected in a small injection amount T1, and during a suction stroke right after a suction valve opening timing (a setting range S2 of a fuel injection timing), second fuel injection by a fuel injection valve is effected as a remaining injection amount T2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression self-ignition gasoline internal combustion engine having a fuel injection valve for directly injecting fuel into a combustion chamber, and self-igniting and burning an air-fuel mixture in the combustion chamber by a compression action of a piston.

[0002]

2. Description of the Related Art In a general gasoline internal combustion engine, there is a limit in leaning an air-fuel mixture to reduce fuel consumption because spark ignition by a spark plug and combustion by flame propagation become unstable. At the time of combustion, the catalyst for purifying exhaust gas has a purifying action as the combustion at the so-called stoichiometric ratio,
In particular, there is a problem that the reducing action of NOx cannot be exhibited.

As a solution to this problem, there has been known a compressed self-ignition gasoline internal combustion engine having a high compression ratio which achieves lean combustion and low emission by performing self-ignition combustion by the compression action of a piston (for example, Japanese Patent Application Laid-Open No. HEI 9-103572). 7-
332141).

[0004] As such a compression self-ignition gasoline internal combustion engine, a so-called direct injection type gasoline internal combustion engine in which fuel is directly injected into a combustion chamber has been proposed. If the injection timing is simply set to the intake stroke so as to mix the fuel uniformly, there is a problem in combustion stability and a problem that the operable range is narrowed.

[0005]

In a normal gasoline internal combustion engine, as shown in FIG. 10 (a), both the closing timing EVC of the exhaust valve and the opening timing IVO of the intake valve are both close to the piston top dead center TDC. Thus, a predetermined valve overlap (O / L) is set.

On the other hand, in FIG. 10B, the valve timing of the intake valve and the exhaust valve is determined by changing the valve closing timing EVC during the exhaust stroke and the valve opening timing IV.
O is in the middle of the intake stroke, and the exhaust valve and the intake valve are both closed.
/ L).

That is, the exhaust valve closing timing EVC is advanced with respect to the valve timing shown in FIG. 10A, and the exhaust stroke is in the middle of the exhaust stroke. At the same time, the exhaust valve opening timing EVO is retarded and the piston lowering timing is reduced. It is near the dead center BDC. The opening timing IVO of the intake valve is set so that the period from the closing timing EVC of the exhaust valve to the piston top dead center TDC is substantially equal to the period from the piston top dead center TDC to the opening timing IVO of the intake valve. It has been retarded. The closing timing IVC of the intake valve is advanced at the same time and is close to the piston bottom dead center BDC. At this time, there is no valve overlap near the piston top dead center TDC, and minus O / L exists.

[0008] When such a period of minus O / L is provided, the combustion gas that has not been exhausted into the cylinder is sealed and compressed, so that the originally high-temperature combustion gas becomes even higher due to this compression action. It is considered that by injecting fuel during this minus O / L period, the injected fuel is promoted to vaporize by residual combustion gas, so that the combustibility is improved as compared with the case where fuel is simply injected during the intake stroke.

However, simply injecting the total required fuel injection amount during the minus O / L period increases the in-cylinder temperature, so that there is a problem that the intake charging efficiency is reduced and the fuel efficiency is also deteriorated. .

Accordingly, an object of the present invention is to expand the operable range of a compression self-ignition gasoline internal combustion engine while improving the intake charging efficiency and fuel efficiency.

[0011]

According to a first aspect of the present invention, a fuel injection valve for directly injecting fuel into a combustion chamber is provided. In a compression self-ignition gasoline internal combustion engine that ignites and burns, the exhaust valve closes during the exhaust stroke, the intake valve opens during the intake stroke, and the exhaust valve and the intake valve are both closed. The fuel injection valve has a valve timing, and performs the first fuel injection by the fuel injection valve during the minus overlap period, and performs the second fuel injection by the fuel injection valve during the intake stroke.

According to the compressed self-ignition gasoline internal combustion engine having such a configuration, during the minus overlap period, the high-temperature combustion gas that has not been exhausted into the combustion chamber is sealed, and this combustion gas is compressed by the piston. It is even hotter. By performing the first fuel injection in such an atmosphere, the injected fuel is exposed to a high temperature and reforming proceeds. At this time, the fuel breaks the molecular chains to form radicals, or combines with a small amount of oxygen remaining in the combustion gas, and the reaction proceeds to the extent of aldehyde. Such reforming of the fuel improves the ignitability even with gasoline fuel having poor ignitability, and realizes a stable compression self-ignition operation. By performing the second fuel injection during the intake stroke after the piston reaches the exhaust top dead center, a sufficient load can be obtained.

[0013] If all the fuel is injected during the minus overlap period, the reforming of the fuel may proceed too much, and furthermore, heat may be generated at this time. As a result, the efficiency with which the fuel can be taken out of the work becomes poor, which leads to a deterioration in fuel efficiency and a decrease in intake charge efficiency.

According to a second aspect of the present invention, in the configuration of the first aspect, the first fuel injection timing is set immediately after the closing timing of the exhaust valve under the low load operation condition.

According to the above configuration, immediately after the exhaust valve is closed,
That is, by performing the first fuel injection at the beginning of the period when both the intake valve and the exhaust valve are closed, the fuel reforming time at the time of low load operation can be lengthened and the fuel reforming can be performed at a higher level.

According to a third aspect of the present invention, in the configuration of the first or second aspect of the present invention, the first fuel injection timing of the exhaust valve is set under an operating condition on a high load side where a compression auto-ignition operation from a medium load is possible. It is set between immediately after the closing timing and the top dead center of the exhaust stroke.

[0017] Under operating conditions on the high load side where compression auto-ignition operation from a medium load is possible, the effect of reforming the fuel is not as required as in the low load operating condition. It does not need to be performed immediately, and may be set anywhere from immediately after the exhaust valve closing timing to the exhaust top dead center. After the top dead center of the exhaust gas, the reforming effect is lost, and the combustion stability and the fuel consumption deteriorate.

According to a fourth aspect of the present invention, in the configuration of any one of the first to third aspects of the present invention, the fuel injection during the second intake stroke is not performed under the high load operation condition without performing the first fuel injection. At the time of injection, the total amount of fuel required is injected in the total amount.

At the time of high load operation, since the required total fuel injection amount is large and the ignitability is high, there is no need to inject fuel during the minus overlap period, and all the necessary fuel amount is injected during the intake stroke. .

According to a fifth aspect of the present invention, in the configuration of any one of the first to fourth aspects, the fuel injection timing during the intake stroke is set immediately after the intake valve opening timing.

By injecting the fuel early in the intake stroke, the injected fuel cools the intake air and improves the charging efficiency of the intake air.

The invention of claim 6 is the invention of claims 1, 2, 3, 5
In any one of the aspects of the invention, the fuel injection amount during the intake stroke is at least half of the total injection amount obtained by combining the first and second injection amounts.

By increasing the second fuel injection amount in the intake stroke, the injected fuel cools the intake air and improves the intake charge efficiency.

According to a seventh aspect of the present invention, there is provided the first, second, third and third aspects.
In the configuration of the invention according to any one of the fifth and sixth aspects, the first injection amount ratio is set to 15 to 45% of the total injection amount combined with the second injection amount under the low load operation condition. is there.

As shown in FIG. 4, when the first injection amount ratio is less than 15%, the combustion stability and fuel consumption are both deteriorated. When the injection amount ratio is more than 45%, the combustion stability is improved.
Fuel economy deteriorates.

According to an eighth aspect of the present invention, in the configuration of the seventh aspect of the present invention, the first injection amount ratio is increased along with the load increase under a high load side operating condition under which the compression self-ignition operation can be performed from a low load. It is set to decrease.

[0027] As the load increases, the required total injection amount of fuel increases and the ignitability improves. Therefore, the first injection amount is reduced as the load increases. If the first injection amount is increased with an increase in the load, the ignitability is excessively improved, the knocking intensity is increased, or the second injection amount during the intake stroke is reduced, and the intake charging efficiency is deteriorated. , The fuel economy will deteriorate.

[0028] The ninth aspect of the present invention relates to the first, second, third and third aspects.
In the configuration of any one of the inventions of 5, 6, 7, and 8, a stability detecting means for detecting the combustion stability is provided. When the stability detecting means detects that the combustion becomes unstable, The setting is made so as to increase the first injection amount ratio.

According to the above configuration, when the combustion becomes unstable, the ignitability is improved and the combustion is stabilized by increasing the first injection amount ratio.

[0030] The invention of claim 10 is the invention of claims 1, 2, 3,
In the configuration of any of the inventions of 5, 6, 7, 8, and 9,
Knocking strength detecting means for detecting the knocking strength is provided, and when the knocking strength detecting means detects that the knocking strength exceeds a predetermined value, the setting is made so as to increase the second injection amount ratio. .

According to the above configuration, when the knocking intensity exceeds a predetermined value, the in-cylinder temperature is reduced and the knocking intensity is reduced by increasing the second injection amount ratio.

[0032] The invention of claim 11 is the invention of claims 1, 2, 3,
In the configuration of any one of the fifth, sixth, seventh, eighth, ninth and tenth aspects, a knocking intensity detecting means for detecting the knocking intensity is provided, and the knocking intensity detecting means detects that the knocking intensity exceeds a predetermined value. When it is detected, the first injection timing is set to be retarded.

According to the above configuration, by delaying the first injection timing, the calorific value decreases, the in-cylinder temperature decreases, and the knocking strength decreases.

[0034]

According to the first aspect of the present invention, the first fuel injection is performed during the minus overlap period in which the exhaust valve and the intake valve are both closed to reform the fuel.
The ignition performance is improved, stable operation is obtained, and the operable range can be expanded. Further, by performing the second fuel injection in the intake stroke, the intake air is cooled by the fuel injected this second time, the intake filling efficiency is improved, and the fuel consumption is also improved.

According to the second aspect of the invention, the first fuel injection timing is set immediately after the closing timing of the exhaust valve under low load operation conditions, so that the reforming of the fuel proceeds reliably and the ignitability is further improved. Can be done.

According to the third aspect of the present invention, the fuel reforming effect is not as required as the low load operation condition under the high load operation condition where the compression self-ignition can be performed from the medium load.
It is not necessary to perform the second fuel injection immediately after the exhaust valve close timing, and by setting the first fuel injection timing from immediately after the exhaust valve close timing to the top dead center of the exhaust stroke, the ignitability is improved. Can be planned.

According to the fourth aspect of the present invention, under high load operation conditions, the first fuel injection is not performed, and the total fuel injection required during the second fuel injection in the intake stroke is performed. Since the entire amount is injected, the required total fuel injection amount is large, and the fuel injection control is optimal for high-load operation with high ignitability.

According to the fifth aspect of the present invention, since the fuel injection timing in the intake stroke is set immediately after the intake valve opening timing, the injected fuel cools the intake air, and the intake charge efficiency can be improved.

According to the sixth aspect of the present invention, the fuel injection amount in the intake stroke is made at least half of the total injection amount of the first and second injection amounts. The effect of cooling the intake air by the injected fuel is enhanced, and the intake air charging efficiency can be improved.

According to the invention of claim 7, the ratio of the first injection amount is set to 15 to 45% of the total injection amount combined with the second injection amount under the low load operation condition. Both combustion stability and fuel economy can be maintained well.

According to the eighth aspect of the present invention, the first injection amount ratio is set so as to decrease as the load increases under the high load side operating condition where the compression ignition can be performed from the low load operating condition. This is optimal for fuel injection control under the above-mentioned operating conditions in which the required total injection amount increases with an increase in the load and the ignitability improves.

According to the ninth aspect of the present invention, when the stability detecting means for detecting the combustion stability detects that the combustion becomes unstable, the first injection amount ratio is set to be increased. As a result, the ignitability is improved, and the combustion can be stabilized.

According to the tenth aspect of the present invention, when the knocking intensity detecting means for detecting the knocking intensity detects that the knocking intensity exceeds a predetermined allowable range, the second injection amount ratio is set. Is set to increase, the in-cylinder temperature is reduced by the increased injected fuel, and the knocking strength can be reduced.

According to the eleventh aspect of the present invention, when the knocking intensity detecting means for detecting the knocking intensity detects that the knocking intensity exceeds a predetermined value, the first injection timing is retarded. Because of the setting, the calorific value decreases accordingly, the temperature in the cylinder decreases, and the knocking strength can be reduced.

[0045]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of a compression self-ignition gasoline internal combustion engine showing a first embodiment of the present invention. A piston 3 is housed in a cylinder block 1 so as to be vertically movable. An intake valve 11 that opens and closes the intake port 7 with an intake cam 9 and an exhaust valve 17 that opens and closes an exhaust port 13 with an exhaust cam 15 are provided.

Near the intake port 7 of the cylinder head 5, a fuel injection valve 2 for injecting gasoline fuel into the combustion chamber 19 is provided.
1 is attached. The fuel injection operation of the fuel injection valve 21 is controlled by a control unit 25 including a microcomputer or the like that receives the input / output timing signals V of the intake valve 11 and the exhaust valve 17 and the load signal L of the engine. Is done.

The intake cam 9 and the exhaust cam 15 determine the valve timing at which the intake valve 11 and the exhaust valve 17 generate a minus overlap (minus O / L) period as shown in FIG. Operate to have. That is, the closing timing of the exhaust valve 17 is changed during the exhaust stroke.
The opening timing of 1 is in the middle of the intake stroke, and the exhaust valve 17 and the intake valve 11 are operated so as to have a valve timing in which both are closed. Further, the gasoline internal combustion engine is set to a relatively high compression ratio of 12 or more in order to enable the compression self-ignition operation, and the load is performed by the fuel injection amount while keeping the intake air amount substantially constant. It has become.

FIG. 2 shows the relationship between the opening / closing timing of the intake valve 11 and the exhaust valve 17, the relationship between the load and the settable ranges S ₁ and S ₂ of the fuel injection timing, and the relationship between the load and the fuel injection amounts T ₁ and T _2. Each is shown. The exhaust valve 17 is opened by EVO and
, The intake valve 11 is opened by IVO, closed by IVC, and E
A period between VC and IVO is a minus O / L period in which both the intake valve 11 and the exhaust valve 17 are closed. The fuel injection into the combustion chamber 19 by the fuel injection valve 21, in the minus O / L period, carried out at different settable range by the load indicated by S ₁ as the first, the intake valve 11 starts to open doing a configurable range shown by S ₂ as the second beginning of the intake stroke.

By setting the minus O / L period,
The post-combustion gas that has not been exhausted is sealed in the combustion chamber 19, and in this state, the piston 3 rises and the combustion gas is compressed. The combustion gas, which was originally high in temperature, becomes even higher due to this compression action, and the injected fuel is injected into such a high-temperature atmosphere for the first time, so that the injected fuel is reformed. At this time, the reaction of the fuel proceeds to the extent of the aldehyde by breaking the chains of the molecules to form radicals or combining with the slight oxygen remaining in the combustion gas. Such fuel reforming improves the ignitability even for gasoline fuel with poor ignitability, and realizes a stable compression self-ignition operation.

By the way, when realizing gasoline self-ignition combustion under low load operation conditions, if the fuel injection amount during the minus O / L period is too small, the reforming of the fuel does not proceed, the ignitability deteriorates, and the combustion becomes poor. It becomes stable and fuel efficiency deteriorates. Conversely, if the injection amount is too large, the reforming of the fuel will be sufficient and the combustion will be stable, but the reforming of the combustion will proceed too much, and furthermore, heat will be generated at this time. Efficiency of taking out work becomes poor, leading to poor fuel economy.

Thus, when fuel is injected during the minus O / L period, there are optimum values for both the injection timing and the injection amount in consideration of the stability of the combustion and the fuel consumption.

FIG. 3 shows the relationship between the first fuel injection timing under low load operation conditions, combustion stability, and fuel efficiency. According to this, by injecting the fuel into the range indicated by A at the beginning of the closing timing (EVC) of the exhaust valve 17, combustion stability,
It can be seen that both fuel economy is good.

FIG. 4 shows the relationship between the ratio of the first injection amount to the total injection amount of the first and second injections, combustion stability, and fuel efficiency under low load operation conditions.
According to this, by injecting 15 to 45% of the total injection amount for the first time, it is possible to improve both combustion stability and fuel efficiency. If it is less than 15%, both the combustion stability and the fuel efficiency deteriorate, and if it exceeds 45%, the combustion stability is improved but the fuel efficiency is deteriorated.

By performing the fuel injection during the intake stroke as the second time under the low load operation condition, a sufficient load for the low load operation can be obtained. This fuel injection is performed in the early stage of the intake stroke, so that the injected fuel cools the intake air, and the intake charge efficiency is improved. The second injection amount is increased as the load increases, as shown in FIG.

On the other hand, under the operating conditions on the high load side where the compression self-ignition operation is possible from the medium load, the total injection amount including the first and second injections increases and the ignitability is originally high.
An extremely small amount of fuel is optimally injected during the minus O / L period. FIG. 5 shows the relationship between the ratio of the first injection amount to the total injection amount of the first and second injections and the combustion stability and fuel efficiency. According to this, both the combustion stability and the fuel efficiency are good when the first injection amount ratio is about 5 to 20%. If it is less than 5%, both the combustion stability and the fuel efficiency deteriorate. If it exceeds 15%, the combustion stability is improved but the fuel efficiency is deteriorated.

Then, as shown in FIG. 2, the injection amount is reduced as the load increases, so that the total injection amount increases as the load increases and the ignitability is improved. This is optimal for the first injection amount control. If the injection amount at this time is zero, the ignitability will not be stable and the fuel efficiency will deteriorate. By slightly injecting as the load becomes higher, the ignitability is stabilized and the fuel efficiency is improved. Conversely, if the injection amount at this time is increased, the ignitability will be excessively improved,
The knocking intensity is increased, and the second injection amount during the intake stroke is reduced correspondingly, so that the intake charging efficiency is reduced and the fuel consumption is deteriorated.

Further, under the above-mentioned operating conditions on the high load side where the compression self-ignition operation can be performed from the medium load, the fuel reforming effect is not required as much as the low load, so that the injection timing is the same as the initial timing of the exhaust valve closing timing. No need to perform, exhaust valve closing timing (EVC)
The position may be set at any position from to the top dead center (TDC) of the exhaust gas. After the top dead center of the exhaust gas, the reforming effect becomes insufficient, and the combustion stability and fuel efficiency deteriorate.

FIG. 6 shows the relationship between the first fuel injection timing, the combustion stability, and the fuel efficiency under the high load side operating conditions that enable the compression self-ignition operation from the medium load. According to this, even if fuel is injected at any position in the range indicated by B from the initial closing timing (EVC) of the exhaust valve 17 to the exhaust top dead center (TDC), both combustion stability and fuel efficiency are good, and exhaust It can be seen that after the top dead center, both combustion stability and fuel efficiency have deteriorated.

Under the high load operation condition, the total fuel injection amount is large and the ignitability is high, so that it is not necessary to inject fuel during the minus O / L period, and all the necessary fuel amount is injected during the intake stroke.

The second fuel injection amount under the low load operation condition and the high load operation condition under which the compression self-ignition operation can be performed from the medium load is set to half or more of the total injection amount. Thus, the effect of cooling the intake air by the fuel injected at the second time is enhanced, and the intake charge efficiency is improved.

As described above, during the minus O / L period, after the first small amount of fuel is injected without injecting the total amount of fuel, the second time is injected during the intake stroke, or By controlling the fuel injection timing and injection amount optimally as a single injection only during the middle, the intake filling efficiency and fuel efficiency can be improved without adding any special parts or control, and stable operation is achieved in all operations Can be obtained over a range.

FIG. 7 is an overall configuration diagram of a compression self-ignition gasoline internal combustion engine showing a second embodiment of the present invention.
In this embodiment, the cylinder block 1 shown in FIG.
A stability sensor 27 as a stability detecting means for detecting combustion stability and a knocking strength sensor 29 as a knocking strength detecting means for detecting knocking strength are mounted. The fuel injection timing and injection amount according to the load are basically the same as those in the first embodiment. The stability sensor 27 may be a rotation speed sensor that detects the engine rotation speed, a combustion pressure sensor that detects the pressure in the combustion chamber, or a vibration sensor that detects vibration of the engine.

FIG. 8 is a flowchart showing the fuel injection control operation by the stability sensor 27. First, the combustion stability is detected by the stability sensor 27 (step 80).
1) If the detected combustion stability becomes worse than the set value, that is, if the combustion becomes unstable (step 803), the first fuel injection amount during the minus O / L period Is increased (step 805), and the second fuel injection amount during the intake stroke is decreased accordingly (step 807). By increasing the injection amount during the minus O / L period, the degree of fuel reforming is increased, the ignitability is improved, and stable combustion is obtained.

FIG. 9 is a flowchart showing the fuel injection control operation by knocking intensity sensor 29. First,
Knocking intensity sensor 29 detects the knocking intensity (step 901), and when the detected knocking intensity exceeds the limit of the knocking intensity, the injection is performed in the first fuel injection operation during the minus O / L period. The amount is decreased (step 905), and the injection timing is retarded up to the exhaust top dead center at the maximum (step 907). First
With the decrease in the second injection amount, the second fuel injection amount during the intake stroke is increased (step 909). As a result, the temperature in the combustion chamber 19 decreases, and the knocking strength decreases.

As described above, in the second embodiment,
Since the combustion stability and the knocking intensity can be controlled by the stability sensor 27 and the knocking intensity sensor 29, respectively, it is possible to quickly respond to a transient load change of the engine and to achieve a responsive operation. In addition, the combustion stability and the knocking intensity are sequentially controlled even when the operation state is minutely changed due to deterioration of the fuel injection valve 21 or carbon adhesion in the combustion chamber 19, that is, even if the internal combustion engine changes over time. Accordingly, stable compression self-ignition operation can be performed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a compression self-ignition gasoline internal combustion engine showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the opening / closing timing of an intake valve and an exhaust valve, the relationship between a load and a settable range of a fuel injection timing, and the relationship between a load and a fuel injection amount in the compression self-ignition gasoline internal combustion engine of FIG. 1; It is.

FIG. 3 is an explanatory diagram showing a relationship between a first fuel injection timing, combustion stability and fuel efficiency under a low load operation condition in the compression self-ignition gasoline internal combustion engine of FIG. 1;

FIG. 4 shows the ratio of the first injection amount to the total injection amount of the first and second injections, the combustion stability, and the fuel efficiency under the low-load operation condition in the compression self-ignition gasoline internal combustion engine of FIG. It is explanatory drawing which shows the relationship.

FIG. 5 is a graph showing a second relationship with respect to the total injection amount of the first and second injections under the operating conditions on the high load side capable of performing the compression self-ignition operation from the medium load in the compression self-ignition gasoline internal combustion engine of FIG. FIG. 9 is an explanatory diagram showing a relationship between a second injection amount ratio, combustion stability, and fuel efficiency.

FIG. 6 shows the relationship between the first fuel injection timing, combustion stability, and fuel efficiency under high load operating conditions under which compression auto-ignition operation is possible from a medium load in the compression self-ignition gasoline internal combustion engine of FIG. FIG.

FIG. 7 is an overall configuration diagram of a compression self-ignition gasoline internal combustion engine showing a second embodiment of the present invention.

FIG. 8 is a flowchart showing a fuel injection control operation using a stability sensor in the compression self-ignition gasoline internal combustion engine of FIG. 7;

FIG. 9 is a flowchart showing a fuel injection control operation using a knocking intensity sensor in the compressed self-ignition gasoline internal combustion engine of FIG. 7;

FIG. 10 is a valve timing chart showing the opening / closing timing of the exhaust valve and the intake valve. FIG. 10 (a) shows a state in which both the closing timing of the exhaust valve and the opening timing of the intake valve are near the piston top dead center, and a predetermined valve overlap ( O / L) is set, and (b) shows a case where a minus overlap (minus O / L) period in which both the exhaust valve and the intake valve are closed is set.

[Explanation of symbols]

Reference Signs List 3 piston 11 intake valve 17 exhaust valve 19 combustion chamber 21 fuel injection valve 27 stability sensor (stability detection means) 29 knocking intensity sensor (knocking intensity detection means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/04 330 F02D 41/04 330E 335 335D 335E 41/22 330 41/22 330B 335 335B 45/00 345 45/00 345B 368 368D F02M 45/02 F02M 45/02 (72) Inventor Tomonori Urushihara 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Kazuya Hasegawa Takaracho, Kanagawa-ku, Yokohama, Kanagawa No. 2 F-term in Nissan Motor Co., Ltd. (reference) 3G023 AA02 AA05 AA06 AA18 AB05 AC04 AD03 AG05 3G066 AA02 AB02 AD12 BA01 BA14 BA17 CC01 CD25 CD26 CD28 DA01 DA04 DB08 DB09 DC00 DC09 DC17 3G084 BA13 BA15 CA03 CA04 DA11 EC10 EC03 EA FA18 FA21 FA25 FA33 FA38 3G301 HA04 JA02 JA22 JA25 KA08 KA09 LB04 MA11 MA19 MA26 NA08 NE04 NE08 NE12 PA17Z PC01Z PC06Z PC08Z PE01Z PE03Z PE04Z PE10Z

Claims (11)

[Claims] In a compression self-ignition gasoline internal combustion engine having a fuel injection valve for directly injecting fuel into a combustion chamber and self-igniting and burning an air-fuel mixture in the combustion chamber by a compression action of a piston, an exhaust valve close timing is set. During the exhaust stroke, the opening timing of the intake valve is in the middle of the intake stroke, and the exhaust valve and the intake valve are both closed. A compressed self-ignition gasoline internal combustion engine which performs a first fuel injection and performs a second fuel injection by the fuel injection valve during an intake stroke. 2. The compression self-ignition gasoline internal combustion engine according to claim 1, wherein the first fuel injection timing is set immediately after the exhaust valve closes under low load operation conditions. 3. The method according to claim 1, wherein the first fuel injection timing is set immediately after the closing timing of the exhaust valve to the top dead center of the exhaust stroke under the operating conditions on the high load side where the compression self-ignition operation is possible from the medium load. 3. The compressed self-ignition gasoline internal combustion engine according to claim 1 or 2, wherein: 4. In a high load operation condition, the first fuel injection is not performed, and the required total fuel injection amount is injected at the time of the second fuel injection during the intake stroke. A compression self-ignition gasoline internal combustion engine according to any one of claims 1 to 3. 5. The compression self-ignition gasoline internal combustion engine according to claim 1, wherein the fuel injection timing during the intake stroke is set immediately after the intake valve opening timing. 6. The fuel injection amount during the intake stroke is at least half of the total injection amount of the first and second injection amounts. A compressed self-ignition gasoline internal combustion engine according to any one of claims 3 and 5. 7. A low-load operation condition, wherein the first injection amount ratio is set to 15 to 45% of the total injection amount combined with the second injection amount. , 2, 3, 5, 6. 8. Under an operating condition on a high load side where a compression auto-ignition operation from a low load is possible, a first injection amount ratio is defined as
8. A compression self-ignition gasoline internal combustion engine according to claim 7, wherein the internal combustion engine is set so as to decrease as the load increases. 9. A stability detecting means for detecting a combustion stability, wherein when the stability detecting means detects that combustion becomes unstable, the first injection amount ratio is increased. Claim 1, 2, 3, 3, characterized in that it is set
9. The compressed self-ignition gasoline internal combustion engine according to any one of 5, 6, 7, and 8. 10. A knocking intensity detecting means for detecting a knocking intensity, wherein the knocking intensity detecting means increases the second injection amount ratio when the knocking intensity exceeds a predetermined value. Claims 1, 2, 3, 5, 6, 7, 8,
10. A compression self-ignition gasoline internal combustion engine according to any of 9. 11. A knocking intensity detecting means for detecting knocking intensity is provided, and when the knocking intensity detecting means detects that the knocking intensity exceeds a predetermined value, the first injection timing is retarded. Claims 1, 2, 3, 5, 6, 7, 8,
A compression self-ignition gasoline internal combustion engine according to any one of claims 9 and 10.