JP2006183667A - Cylinder injection type internal combustion engine and combustion control method in starting cylinder injection type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method for a cylinder injection type internal combustion engine capable of reducing an activation time for a catalyst while reducing the exhaust amount of unburned HC in starting the cylinder injection type internal combustion engine and less exhausting unburned HC even in an operating period ranging from a cranking to a combustion control for activating the catalyst. <P>SOLUTION: This cylinder injection type internal combustion engine comprises a fuel injection valve injecting a fuel directly into a cylinder and the catalyst for purifying exhaust gases in an exhaust pipe. The internal combustion engine comprises at least two types of combustion control patterns for earlier activating the catalyst and switches the combustion control pattern based on the temperature of the catalyst. Also, stratified combustion can be realized from the start of the engine by optimizing the structure of the cylinder injection internal combustion engine. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for early activation of a catalyst in a cylinder injection internal combustion engine in which fuel is directly injected into a combustion chamber, particularly at the time of starting.

  So far, with the strengthening of exhaust gas and fuel efficiency regulations, a technique for early activation of the catalyst at the time of starting has been proposed. In particular, the following technologies have been proposed for technologies related to the cylinder injection internal combustion engine.

  The technology relating to the early activation of the catalyst in the conventional in-cylinder injection type internal combustion engine is that the additional fuel injection is performed from the initial stage to the middle stage of the expansion stroke disclosed in Japanese Patent Application Laid-Open No. 8-100368, and this additional fuel is used as the main combustion flame. There has been proposed a method of warming up the catalyst by raising the exhaust temperature by igniting by propagation.

  In addition, Japanese Patent Application Laid-Open No. 11-294157 discloses that additional fuel is injected during the expansion stroke, the exhaust is retained in a volume provided in the exhaust manifold, and the remaining fuel remaining is reburned in the volume. Thus, a method for warming up the catalyst by increasing the exhaust temperature while reducing unburned HC has been proposed.

JP-A-8-1000063 Japanese Patent Laid-Open No. 11-294157

  By the way, when the additional fuel is injected from the initial stage to the middle stage of the expansion stroke, the additionally injected fuel is discharged while burning from the combustion chamber. If additional fuel injection is performed near TDC, that is, at the beginning of the expansion stroke, unburned HC discharged from the combustion chamber tends to decrease. Therefore, the exhaust temperature becomes high. However, in this case, the additional fuel is ignited immediately after being injected from the fuel injection valve, and burns while taking in oxygen, so that a large amount of smoke is generated. In addition, when the additional fuel is injected in the middle of the expansion stroke, it is difficult to reliably ignite and burn the additional fuel because no flame remains due to the main combustion, resulting in an increase in unburned HC and exhaust gas. Since the temperature does not rise sufficiently, it takes time until the catalyst is activated. On the other hand, the method of performing additional fuel injection during the expansion stroke and recombusting the unburned HC in the volume provided in the exhaust manifold can supply high temperature exhaust gas to the catalyst while reducing the unburned HC. However, in this method, if the temperature of the volume part does not reach a predetermined temperature, even if sufficient residual oxygen and unburned HC exist, recombustion does not occur in the volume part. That is, over time until the volume reaches a predetermined temperature, unburned HC discharged from the combustion chamber is discharged into the atmosphere as it is.

  The present invention has been made in view of the above points, and its object is to further reduce the activation time of the catalyst while reducing unburned HC until the catalyst is activated. It is in.

  In order to achieve the above object, a cylinder injection internal combustion engine according to the present invention and a combustion control method at the time of start-up are essentially a fuel injection valve for directly injecting fuel into a cylinder, and exhaust gas in an exhaust pipe. It is activated by the HC component of and has a soot G medium. And it has at least 2 types of combustion control patterns for activating the said catalyst at an early stage, It is characterized by switching the said combustion control pattern based on catalyst temperature.

  In addition, it is proposed that combustion control is also performed based on the cooling water temperature. Preferably, there is a means for selecting a combustion control method based on the water temperature, and if the water temperature is lower than the predetermined temperature and is not in the stratified startable region, the fuel Injecting is performed in the intake stroke, homogeneous combustion is performed, and when the water temperature is higher than a predetermined temperature, fuel injection is performed in the compression stroke and stratified combustion is performed in a region where stratified combustion is possible.

  Preferably, fuel is injected from the start to the compression stroke, that is, stratified combustion is performed.

  As a specific aspect of the present invention, in a cylinder injection internal combustion engine including a fuel injection valve that directly injects fuel into a cylinder and a catalyst that is activated by an HC component in exhaust gas, the catalyst is activated early. The second combustion control pattern is executed when the catalyst temperature reaches a predetermined value, and the second combustion control pattern injects fuel in the compression stroke and the expansion stroke. It is characterized by the double injection control.

  In the above aspect, preferably, the first fuel injection is performed in the compression stroke and the second fuel injection is performed in the initial stage of the expansion stroke according to the operating conditions, and the second fuel injection is expanded when the catalyst temperature reaches a predetermined value. This is a method of switching after the middle of the process.

  In the above aspect, preferably, a fuel injection valve capable of independently controlling and injecting air and fuel is applied.

  In the above aspect, preferably, a fuel injection valve capable of forming a spray with little change in shape with respect to a change in in-cylinder pressure is applied.

  In the above aspect, the second fuel injection is preferably divided into a plurality of times and injected into the cylinder in two injections until the catalyst temperature reaches a predetermined value.

  In the above aspect, it is preferable that the amount of additional fuel is changed in accordance with the oxygen concentration in the exhaust gas in the two-time injection control until the catalyst temperature reaches a predetermined value.

  With such a configuration and the combustion control method, it is possible to further reduce the activation time of the catalyst while reducing the discharge of unburned HC at the time of starting.

  In the present invention, the activation time of the catalyst can be greatly shortened by switching between the first combustion control and the second combustion control based on the temperature of the catalyst and the temperature of the cooling water at the start of the engine. As a result, unburned HC discharged during the combustion control period for catalyst activation can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective sectional view of a cylinder injection internal combustion engine according to an embodiment of the present invention. Each cylinder of the internal combustion engine body 1 includes a cylinder block 2 at a lower portion and a cylinder at an upper portion of the cylinder block 2. A head 3 is arranged.

  Inside the cylinder block 2, a piston 4 is slidably arranged, and a space between the cylinder block 2 and the piston 4 is formed as a combustion chamber 5. The cylinder head 3 is a pent roof, and two intake pipes 6 and two exhaust pipes 7 that open to the combustion chamber 5 are connected to the cylinder head 3. An intake valve 8 is disposed in each exhaust pipe 7, and an exhaust valve 9 is disposed at a connection portion with the cylinder head 3. In addition, about the crown surface shape of piston 4, although the flat thing is shown as a typical example, there is no restriction | limiting in particular.

  A fuel injection valve 10 for injecting fuel directly into the cylinder of the engine is disposed on the side surface of the combustion chamber in the vicinity of the intake valve 8, and its injection port is located toward the combustion chamber 5. The fuel injection valve 10 is a high-pressure swirl fuel injection valve having a nozzle shape that gives a swirl force to the sprayed fuel to form a conical shape with a predetermined spray angle. A spark plug 11 is disposed at the center position of the ceiling of the cylinder head 3.

The intake valve 8 and the exhaust valve 9 are moved up and down by a camshaft (not shown) disposed at the upper part of the cylinder head 3, and an intake pipe 6 and an exhaust pipe 7 formed on the cylinder head 3. Open and close the communication valve hole. The piston 4 is connected to a crankshaft (not shown) rotatably supported at the lower portion of the cylinder block 2 via a connecting rod 12, and the piston 4 moves up and down in the cylinder block 2 by the operation of the engine. Accordingly, the crankshaft is rotationally driven.

  FIG. 2 shows a system configuration diagram of the direct injection internal combustion engine in the embodiment of the present invention. In the cylinder injection internal combustion engine having the configuration described with reference to FIG. 1, an exhaust purification device 13 is provided on the downstream side of the exhaust pipe 7, and oxygen in the exhaust is provided in the exhaust pipe 7 on the upstream side of the exhaust purification device. An oxygen concentration sensor 14 for detecting the concentration is provided, and a catalyst temperature sensor 15 is provided in the exhaust purification device 13. The exhaust purification device 13 includes a three-way catalyst 13a and a NOx catalyst 13b. In the case where the three-way catalyst 13a and the NOx catalyst 13b are provided independently, for example, exhaust temperature sensors are provided in the exhaust pipes 7 on the upstream side and the downstream side of the three-way catalyst 13a and the NOx catalyst 13b, respectively. The catalyst temperature may be estimated from the front and rear exhaust temperatures.

  The ECU 16 receives signals such as the engine speed, the air amount, the water temperature, and the accelerator position, and the like. The catalyst temperature estimating means and the starting combustion control means, specifically the fuel injection control part and the ignition timing control part. It has. The fuel injection control unit includes a main fuel injection control unit for obtaining engine output and an additional fuel injection control unit for activating the catalysts 13a and 13b. The fuel injection timing and the fuel are determined according to operating conditions. An injection amount is set.

  FIG. 3 illustrates an outline of the combustion control method at the start in the embodiment of the present invention. When the engine is started and the catalyst reaches a predetermined temperature Ts, the first combustion control for activating the catalyst is performed. While the first combustion control is being performed, since the catalyst is not in a sufficiently active state, combustion must be performed so that unburned HC is not discharged as much as possible from the combustion chamber. When the catalyst temperature further rises and reaches the lower limit value Tc (about 250 ° C. to 300 ° C.) of the activation region of the catalyst, switching to the second combustion control is performed. When the catalyst temperature becomes equal to or higher than Tc, unburned HC discharged from the combustion chamber starts to react in the catalyst. As a matter of course, residual oxygen that is commensurate with burning unburned HC is indispensable in the exhaust, but this can be dealt with by inhaling sufficient air into the cylinder by using stratified combustion as the main combustion. Can do. The second combustion control ends when the catalyst temperature reaches the upper limit value Te of the activation region of the catalyst. The relationship between the catalyst temperature and the purification rate is as shown in FIG. When the catalyst temperature is about 200 ° C. to 250 ° C., the purification rate is close to 0, and it is difficult to purify unburned HC. That is, how quickly the catalyst temperature is set to 200 ° C. to 250 ° C. or more while reducing the unburned HC discharged from the engine is an important point in shortening the catalyst activation time. Further, the reason why the purification rate approaches 100% is that the catalyst temperature is about 500 ° C., therefore, it is desirable to set Te to around 500 ° C. Note that the start of the first combustion control means may be performed based on a timer after starting instead of the catalyst temperature.

  FIG. 5 shows a control flowchart in the embodiment of the present invention. First, in step 101, the catalyst temperature Ct is set by the catalyst temperature sensor 15 provided in the exhaust pipe. If Ct <Ts in S102, the first combustion control is not performed, and the catalyst temperature Ct is measured again in step 101. After the above operation is repeated, the first combustion control is started in step 103 when the catalyst temperature Ct ≧ Ts. Next, the first combustion control is performed until the catalyst temperature Ct ≧ Ts in step 104. When the catalyst temperature Ct ≧ Ts is established at step 104, the second combustion control is started at step 105. Then, the second combustion control is performed until the catalyst temperature Ct ≧ Te in step 105, and when the catalyst temperature Ct ≧ Te is satisfied in step 106, the combustion control of the present invention is terminated.

  By the way, at the time of stratified combustion of an in-cylinder internal combustion engine, it is common to inject fuel into a cavity provided on the piston crown surface, guide fuel spray through the cavity, and convey it to a spark plug. In such a concept, in order to cause the fuel to collide with the piston, the liquid film adheres to the piston crown surface. Particularly at the time of start-up, since the piston and the combustion chamber wall surface are cooled, there is a problem that the fuel adhering to the wall surface is insufficiently vaporized and the stable region of combustion is reduced. With respect to these problems, in the present invention, as shown in FIG. 6, the first combustion control means is selected according to the water temperature at the start. When the water temperature at start-up is equal to or higher than Tw (stratified combustion feasible region), as the first combustion control pattern, the first fuel injection is performed in the compression stroke, and the second fuel injection, which is additional fuel, is performed in the expansion stroke. The exhaust temperature is raised by afterburning, and the catalyst temperature is raised. On the other hand, when the water temperature at the start is equal to or lower than Tw, the first fuel injection is performed in the intake stroke as shown in FIG. 15, and the ignition timing is retarded to near TDC in addition to the homogeneous lean combustion, thereby obtaining the same effect as described above. .

  Next, the case where the water temperature at the time of starting is equal to or higher than Tw will be specifically described.

  FIG. 7 shows a fuel injection control method in a representative embodiment of the present invention. In this embodiment, when the catalyst temperature is around Tc, the first fuel injection timing is performed in the compression stroke, and the subsequent second fuel injection is at the beginning of the expansion stroke until the catalyst temperature reaches Tc, and the catalyst temperature reaches Tc. After that, the control method is switched after the middle stage of the expansion stroke. As the first combustion control, a combustion mechanism for performing the first fuel injection in the compression stroke and performing the second fuel injection in the initial stage of the expansion stroke will be described with reference to FIG. The first fuel injected in the compression stroke is combusted by subsequent ignition. The second fuel injected at the beginning of the expansion stroke is ignited by the flame propagation of the first combustion. Therefore, when the second fuel injection is performed, the combustion chamber is very hot, and the second injected fuel is burned while taking in oxygen immediately after injection without being sufficiently mixed with the residual oxygen in the combustion chamber. This is called diffusion combustion. In the case of such a combustion mode, a large amount of smoke is generated due to insufficient oxidation. FIG. 9 shows the exhaust temperature, unburned HC, and smoke characteristics when the second fuel injection timing is changed. The exhaust gas temperature decreases as it is delayed from 40 degATDC, while the unburned HC increases. In the vicinity of 70 degATDC, since the main combustion flame does not remain, it is considered that the second injected fuel does not ignite. Smoke increases rapidly before 40 degATDC.

  Therefore, in this embodiment, a specific improvement plan for raising the exhaust temperature while reducing the unburned HC and smoke, which are the above-mentioned problems, is also proposed. This improvement plan is shown in FIGS. 11 will be used for explanation.

  FIG. 10 shows an optimum spray form of the second injected fuel injected in the initial stage of the expansion stroke. In the figure, (a) shows a case where a fuel injection valve capable of independently controlling air and fuel is applied. The first fuel is injected in the compression stroke, and the air-fuel mixture formed around the spark plug is ignited by the spark plug. There is no particular problem whether the first fuel here is fuel alone or a mixture of air and fuel. The adaptation of the fuel injection valve is effective during the second fuel injection. Since the second injected fuel injected at the beginning of the expansion stroke can be supplied to the combustion chamber in a state where air and fuel are mixed in advance, the combustion mode by the second injected fuel is set to premixed combustion. Can do. That is, smoke that is a problem can be significantly reduced, and unburned HC discharged from the combustion chamber can be reduced by optimizing the second injection timing. Therefore, even if the second fuel injection is performed at the initial stage of the expansion stroke, the catalyst can be activated by increasing the temperature of the exhaust gas while reducing unburned HC and smoke. FIG. 16 shows an essential part of an example of the fuel injection valve 160. The injection valve 160 has an injection hole 163 downstream of the valve body 161 and the valve seat 162, and an air mixing chamber 164 downstream of the injection hole 163. Air is introduced into the mixing chamber 164 through the air introduction hole 165, mixed with the metered fuel in the mixing chamber 164, and supplied into the cylinder from the injection hole 166. Further, (b) shows a case where a fuel injection valve capable of injecting a fuel spray with little shape change due to a pressure change is used. The combustion chamber when the second fuel is injected is at a high pressure due to the first combustion. Therefore, when the fuel injection valve is used, the second fuel spray is less likely to be affected by the pressure in the combustion chamber, so that a spray similar to the spray shape of the first injected fuel can be formed. Therefore, since the utilization rate of the residual oxygen in the combustion chamber can be improved without reducing the fuel spray and the unburned HC can be reduced, the exhaust gas can be reduced while reducing the unburned HC and smoke as in (a). It is possible to activate the catalyst by raising the temperature.

  An example of the injection valve 170 is shown in FIG. The injection valve 170 is attached so that the tip end of the injection hole 171 is cut into a stepped shape 172 at the center of the injection hole 171 and the cut side 173 faces the plug. FIG. 17A shows an engine to which the thus configured injection valve 170 is attached. In this engine, as shown in the figure, the fuel spray is deflected to the plug side, the piston side penetration is short, and the amount of fuel is small. When the fuel spray is sectioned along the line AA, it looks as shown in FIG. The center line is a line indicating a cut surface cut into a stepped shape 172.

  Such spray has the advantage that the pressure inside and outside the spray is the same, so that the shape of the spray is not easily deformed even when the pressure in the combustion chamber increases.

  Further, a description will be given of a method capable of activating the catalyst by raising the temperature of the exhaust gas while reducing the unburned HC and smoke even when the second fuel injection is performed at the initial stage of the expansion stroke by controlling the second fuel injection. . FIG. 11 shows an optimum combustion injection method in the case where the second fuel injection is performed at the initial stage of the expansion stroke. Specifically, it is a method in which the second injected fuel of the first combustion control until the catalyst temperature reaches Tc is divided and injected twice or more. By dividing and injecting the second injected fuel into two or more times, the utilization rate of the remaining oxygen is improved as described in FIG. 10B, so that the unburned HC and smoke are reduced while the exhaust gas is reduced. The catalyst is activated by raising the temperature.

  Next, the optimum second combustion control method will be described. The second combustion control here is a method of performing the second fuel injection after the middle stage of the expansion stroke in FIG. As described in FIG. 3, the catalyst temperature when starting the second combustion control has reached 250 ° C. to 300 ° C. Thereafter, unburned HC begins to react in the catalyst, but the amount of generated heat is greatly influenced by the amount of residual oxygen. If the amount of residual oxygen in the exhaust gas does not include the amount of unburned HC discharged from the combustion chamber, the unburned HC cannot be burned in the catalyst and is discharged to the exhaust pipe downstream of the catalyst. . Therefore, in this embodiment, the second fuel injection pulse width is set based on the oxygen concentration in the exhaust gas. Specifically, as shown in FIG. 12, when the oxygen concentration in the exhaust gas is high, the second fuel injection pulse width is lengthened. As a result, fuel suitable for the amount of residual oxygen can be supplied to the catalyst, and unburned HC can be reliably burned in the catalyst. Assuming that the water temperature is low and the main combustion setting A / F must be made rich, it is preferable to apply a fuel injection valve capable of independently controlling air and fuel as described in FIG. During the exhaust stroke, only air is supplied to the combustion chamber to ensure the amount of oxygen in the exhaust suitable for the amount of fuel required to activate the catalyst.

  With the above-described configuration and combustion control method, it is possible to significantly reduce the activation time of the catalyst as compared with the conventional case.

  However, in the operation period from the cranking to the start of the first combustion control, the catalyst is not activated, so the unburned HC discharged from the combustion chamber is released to the atmosphere without being purified.

  Therefore, the present invention is not only a combustion control method for shortening the activation time of the catalyst in the direct injection internal combustion engine, but also the unburned HC discharged in the operation period from the cranking to the start of the first combustion control. The present invention proposes an in-cylinder injection internal combustion engine that is optimal for realizing reduction.

  FIG. 13 is a perspective conceptual cross-sectional view of an optimal direct injection internal combustion engine in the embodiment of the present invention. Basically, the configuration shown in FIG. 1 is provided. In the intake pipe 6 on the upstream side of the intake valve 8, a rectifying plate 17 that divides the intake flow path of the intake pipe 6 into two parts is arranged. A flow dividing valve 18 is disposed upstream of the flow straightening plate 17. The diversion valve 18 is arranged so that the valve body moves in an angle range of 90 degrees from right below to right next as the valve shaft rotates. The speed of the tumble flow 19 generated in the combustion chamber 5 is adjusted by opening and closing the diversion valve 18. Further, a curved groove is formed on the crown surface of the piston 4 to improve the rectification and storage stability of the tumble flow 19.

  By using the in-cylinder injection type internal combustion engine having such a configuration, the fuel injected from the fuel injection valve 10 is formed in the combustion chamber in advance and is transported around the spark plug by the tumble flow 19, and stratified combustion is performed from cranking. Can be realized. As a result, as shown in FIG. 14, the amount of unburned HC exhaust can be greatly reduced compared to the homogeneous combustion. Note that during the period until the engine speed increases, the amount of air taken into the combustion chamber is small, and therefore a fuel injection valve that injects a spray in which part of the fuel spray is injected in the direction of the spark plug is used. Is desirable.

  As understood from the above description, in this embodiment, the first combustion control for increasing the exhaust temperature while reducing the unburned HC and smoke, and supplying the unburned HC to the catalyst and burning it in the catalyst. By switching the second combustion control at an optimum timing based on the catalyst temperature, the activation time of the catalyst can be greatly shortened.

  Further, in this embodiment, since it is possible to realize stratified combustion from start-up, it is possible to reduce unburned HC discharged during the operation period from cranking to performing catalyst control for catalyst activation. .

1 is a perspective conceptual sectional view of a direct injection internal combustion engine in an embodiment of the present invention. 1 is a system configuration of a direct injection internal combustion engine according to an embodiment of the present invention. The outline | summary of the combustion control method at the time of start in embodiment of this invention. Relationship between catalyst temperature and purification rate. The control flowchart in embodiment of this invention is shown. The outline of the combustion control method in consideration of the water temperature at the time of starting in the embodiment of the present invention. The fuel-injection control method in representative embodiment of this invention. Combustion mechanism at the time of two injections in the initial stage of the compression stroke and the expansion stroke. The exhaust gas temperature, unburned HC, and smoke characteristics when the second fuel injection timing is changed in the embodiment of the present invention. The optimal form of the 2nd injection fuel injected in the expansion stroke initial stage in embodiment of this invention. The combustion injection method as an example in the case of performing 2nd fuel injection in the expansion stroke initial stage in embodiment of this invention. The relationship between the oxygen concentration in exhaust_gas | exhaustion and the 2nd fuel injection pulse width in embodiment of this invention. 1 is a perspective conceptual cross-sectional view of an optimal in-cylinder injection internal combustion engine in an embodiment of the present invention. Unburned HC emissions discharged from the combustion chamber during homogeneous combustion and stratified combustion at start-up. The time chart which shows the other Example of this invention. Drawing which shows an example of an air assist type fuel injection valve. (A) Drawing which shows a system at the time of using the injection valve which is hard to receive to the influence of a pressure change. (B) Sectional drawing which shows the shape of spraying. (C) Main part sectional drawing of an injection valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine main body, 2 ... Cylinder block, 3 ... Cylinder head, 4 ... Piston, 5 ... Combustion chamber, 6 ... Intake pipe, 7 ... Exhaust pipe, 8 ... Intake valve, 9 ... Exhaust valve, 10 ... Fuel injection valve 11 ... Spark plug, 12 ... Connecting rod, 13 ... Exhaust gas purification device, 13a ... Three-way catalyst, 13b ... NOx catalyst, 14 ... Oxygen concentration sensor, 15 ... Catalyst temperature sensor, 16 ... ECU, 17 ... Rectifying plate, 18 ... Split valve, 19 ... Tumble flow.

Claims (12)

  In a cylinder injection internal combustion engine having a fuel injection valve that directly injects fuel into a cylinder and a catalyst that is activated by HC in exhaust gas, the temperature of the catalyst is such that the catalyst can be activated by HC in exhaust gas. An in-cylinder internal combustion engine characterized in that a combustion control pattern of the engine is different from a combustion control pattern of the engine thereafter.   In a combustion control method for an internal combustion engine having a catalyst that is activated by unburned HC, until the catalyst reaches a temperature at which the unburned HC in the exhaust gas can be purified, there is little emission of unburned HC and the exhaust temperature After a high combustion control pattern is executed and the catalyst reaches a temperature at which the unburned HC in the exhaust gas can be purified, another combustion control for discharging the exhaust gas containing unburned HC to be supplied to the catalyst is executed. Combustion control method at start-up in an in-cylinder injection internal combustion engine.   In order to activate the catalyst early in a combustion control method at start-up in a cylinder injection internal combustion engine having a fuel injection valve for directly injecting fuel into a cylinder and a catalyst activated by HC in exhaust gas A combustion control method at the time of start-up in a direct injection internal combustion engine, characterized by having at least two types of combustion control patterns and switching the combustion control patterns based on a catalyst temperature.   A fuel injection valve that directly injects fuel into the cylinder, a catalyst that is activated by HC in the exhaust gas, and a function that injects fuel twice during the combustion stroke, and a combustion control pattern based on the cooling water temperature of the engine In the case where the water temperature is lower than the predetermined temperature until the temperature of the catalyst reaches a predetermined value, the fuel is injected only once in the intake stroke, and the ignition timing is retarded to near the top dead center. A combustion control method at the start of a direct injection internal combustion engine, characterized in that when the temperature is higher than a predetermined temperature, the fuel is injected first in the compression stroke and the next injection is executed in the expansion stroke.   In a fuel injection valve that directly injects fuel into a cylinder and a catalyst that is activated by HC in exhaust gas, until the temperature of the catalyst reaches a predetermined value, the injection valve The fuel is injected twice in the first half of the expansion stroke, and after the temperature of the catalyst reaches a predetermined temperature, the fuel is injected in two steps in the second half of the compression stroke and the expansion stroke. A combustion control method at the time of start-up in a cylinder injection internal combustion engine which is characterized.   6. The fuel according to claim 5, wherein fuel is injected in two parts in the first half of the compression stroke and the expansion stroke until the temperature of the catalyst reaches a predetermined value, and in the first half of the expansion stroke. A combustion control method at the time of start-up in a direct injection internal combustion engine, characterized in that the injection is performed in two portions.   7. The combustion control method at the start of a direct injection internal combustion engine according to any one of claims 1 to 6, wherein fuel is injected in a compression stroke at the time of cranking and stratified combustion operation is performed.   An in-cylinder injection internal combustion engine having a fuel injection valve that directly injects fuel into a cylinder and a catalyst for purifying exhaust gas in an exhaust pipe has two types of combustion control patterns for early activation of the catalyst. When the catalyst temperature reaches a predetermined value, combustion control is performed with a combustion control pattern for activating the catalyst, and in the combustion control, fuel is injected in two steps in a compression stroke and an expansion stroke. Combustion control method at start-up in the internal combustion engine.   A fuel injection valve that directly injects fuel into the cylinder and a catalyst that purifies unburned HC in the exhaust in the exhaust pipe. Combustion control at start-up in a direct injection internal combustion engine characterized in that the second fuel injection is performed in the initial stage of the expansion stroke, and the second fuel injection is switched after the middle stage of the expansion stroke when the catalyst temperature reaches a predetermined value. Method.   10. The fuel injection valve according to claim 1, wherein the fuel injection valve is provided with an air inlet at a downstream position of the fuel metering unit, and is mixed with air supplied from the inlet. An in-cylinder injection internal combustion engine, and a combustion control method at start-up in the in-cylinder injection internal combustion engine, characterized in that the mixed gas mixture is injected into the cylinder.   10. An in-cylinder injection internal combustion engine according to claim 1, wherein a fuel injection valve having a fuel spray pattern having a small shape change ratio with respect to a change in in-cylinder pressure is used. Combustion control method at start-up in engine and direct injection internal combustion engine. In the thing in any one of Claims 5 thru | or 9, it changes according to the oxygen concentration in exhaust_gas | exhaustion as a 2nd injection in the 2nd injection control until a catalyst temperature reaches predetermined value, It is characterized by the above-mentioned. A combustion control method at start-up in a direct injection internal combustion engine.

Images