JP2009102998A - Spark ignition internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress torque fluctuation and the increase of unburnt gas in an internal combustion engine. <P>SOLUTION: The engine 10 has a piston 15, an injector 18 and a cylinder 20. The injector 18 injects fuel toward the internal wall surface of the cylinder between the top dead center and bottom dead center of the piston 15. An ECU 23 acquires data of a cylinder bore internal wall temperature, a fuel temperature, an intake air temperature and rotating speed from a water temperature sensor 25, a fuel temperature sensor 22, an intake air temperature sensor 24 and a rotation sensor 26. The ECU 23 determines injection timing based on the acquired data. When the cylinder bore internal wall temperature, fuel temperature or intake air temperature is lower than each threshold value or the engine speed is lower than a threshold value, the ECU 23 injects fuel before the piston 15 reaches the bottom dead center after passing through an injection point P in an intake stroke. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to control of fuel injection timing in a direct injection engine.

  In-cylinder spark ignition internal combustion engines that can inject fuel directly into the combustion chamber have been developed. In a cylinder injection type spark ignition internal combustion engine, fuel can be supplied directly into the combustion chamber, so that the timing of fuel injection into the cylinder can be adjusted (see Patent Document 1).

Further, since the fuel is injected into the combustion chamber separately from the intake air, various effects can be generated according to the fuel injection direction. The fuel injection direction is designed to produce a desired effect. Depending on the effect to be exerted, the injection direction may be determined so that the fuel is injected toward the inner wall of the bore.
JP-A-7-286520

  By the way, the injected fuel is required to be sufficiently vaporized before being ignited. However, in a situation where the fuel is difficult to vaporize, such as when cold, there is a possibility that part of the fuel injected to the inner wall of the cylinder cannot be vaporized and adhere to the inner wall of the cylinder.

  The cylinder inner wall is covered with lubricating oil, and the fuel that could not be vaporized is adsorbed by the lubricating oil. The adsorbed fuel is also vaporized, but may not be completely vaporized before ignition. Therefore, the amount of fuel to be burned for each cycle varies, and torque variation may occur. Further, the adsorbed fuel continued to be vaporized during the exhaust stroke after the explosion stroke, and there was a risk of increasing the unburned gas in the exhaust gas.

  An object of the present invention is to suppress torque fluctuation and increase in unburned gas even in a situation where fuel cannot be sufficiently vaporized in a combustion chamber in a spark ignition internal combustion engine capable of directly injecting fuel into a cylinder.

  A spark ignition internal combustion engine according to a first invention includes injection means, detection means, and control means. The injection means injects fuel toward an injection point that is a predetermined position between the top dead center and the bottom dead center on the inner wall of the cylinder. The detection means detects a factor that affects the vaporization of the fuel injected by the injection means in the combustion chamber. When the factor detected by the detection means deviates from a predetermined range in which fuel vaporization is promoted in the combustion chamber, the control means causes the piston that moves from the top dead center to the bottom dead center during the intake process to pass through the injection point. Control is performed so that the fuel is injected into the injection means between the time and the time when the bottom dead center is reached.

  According to the first invention, when the factor is out of the predetermined range, the fuel is injected from the time when the piston in the intake stroke passes through the injection point to the time when the bottom dead center is reached. Therefore, even when the factor is out of the predetermined range, the fuel spreads on the top surface of the piston, so that it is possible to promote the vaporization of the fuel.

  In the spark ignition internal combustion engine according to the second invention, in addition to the configuration of the first invention, the factor detected by the detecting means is a factor affecting the vaporization of the bore inner wall on the injection point side. The control means controls the fuel injection timing by the injection means based on the factor.

  According to the second invention, fuel vaporization can be promoted more accurately by paying attention to the fuel vaporization in the bore inner wall that most influences the fluctuation of the vaporization amount for each cycle.

  In the spark ignition internal combustion engine according to the third aspect of the invention, in addition to the second configuration, the factor affecting the vaporization is the bore inner wall temperature on the injection point side.

  According to the third invention, fuel vaporization can be effectively promoted by controlling the injection timing by using the bore inner wall temperature on the injection point side as a factor having the greatest influence on the vaporization in the bore inner wall. It becomes possible.

  The spark ignition internal combustion engine according to the fourth aspect of the invention includes an intake port in addition to the first configuration. The intake port performs intake into the combustion chamber so as to generate a tumble flow in the combustion chamber. The injection point is determined so that the tumble flow is strengthened by the injection means injecting fuel toward the injection point.

  According to the fourth aspect of the present invention, it is possible to prevent a problem that occurs when a jet of fuel injection is used for strengthening the tumble, that is, insufficient fuel vaporization.

  In the spark ignition internal combustion engine according to the fifth invention, in addition to the fourth configuration, the intake port generates a forward tumble flow in the combustion chamber, and the injection point is determined on the inner wall of the exhaust side bore.

  According to the fifth aspect, in an engine that generates a general forward tumble flow, it is possible to prevent insufficient fuel vaporization as described above.

  In the spark ignition internal combustion engine according to the sixth invention, in addition to the configuration of the first invention, the control means causes the fuel to be injected into the injection means as the factor changes in a direction that promotes fuel vaporization outside the predetermined range. Control to inject late.

  According to the sixth invention, it is possible to prevent the injection timing from being advanced more than necessary.

  According to the present invention, it is possible to suppress fluctuations in torque and increase in unburned gas under a situation where fuel is not sufficiently vaporized in the combustion chamber.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an engine (spark ignition internal combustion engine) to which an embodiment of the present invention is applied.

  The engine 10 is connected to a fuel tank 11, an intake passage 12, and an exhaust passage 13. Fuel is supplied to the engine 10 from a fuel tank 11. In addition, air is drawn into the engine 10 through the intake passage 12. The fuel supplied by the sucked air is burned. Exhaust gas generated by combustion in the engine 10 is discharged to the outside through the exhaust passage 13.

  The engine 10 includes a cylinder block (not shown), a cylinder head 14, a piston 15, an intake valve 16, an exhaust valve 17, an injector 18, a spark plug 19, and the like.

  A cylinder 20 is provided in the cylinder block. A piston 15 is provided in the cylinder 20. The piston 15 is slidable in the cylinder height direction of the cylinder 20. A space surrounded by the cylinder 20, the cylinder head 14, and the piston 15 is formed as a combustion chamber 21.

  The combustion chamber 21 communicates with the intake passage 12 and the exhaust passage 13. An intake valve 16 and an exhaust valve 17 are disposed in the intake passage 12 and the exhaust passage 13, respectively. By opening the intake valve 16 at a predetermined time, air is sucked into the combustion chamber 21 through the intake passage 12. By opening the exhaust valve 17 at a predetermined time, exhaust gas is discharged from the combustion chamber 21 through the exhaust passage 13.

  Note that air sucked from the intake passage 12 is forward tumble flow in the combustion chamber 21 (see T in FIG. 1), that is, the sucked air descends on the exhaust valve 17 side in the combustion chamber 21 and enters the combustion chamber 21. The intake port 12a is formed in a shape that generates a tumble flow that rises on the intake valve 16 side.

  The injector 18 is provided in the cylinder head 14 so as to inject fuel directly into the combustion chamber 21. Fuel is supplied from the fuel tank 11 to the injector 18. The injector 18 injects a predetermined amount of fuel into the combustion chamber 21 at a predetermined time.

  The fuel injection direction of the injector 18 is determined in a direction in which the forward tumble flow T generated by the air sucked from the intake port 12a is strengthened by the penetration force of the injected fuel. That is, in the direction in contact with the forward tumble flow, the same direction as the forward tumble flow is determined as the injection direction. For example, the direction toward the predetermined injection point P between the TDC (top dead center) and BDC (bottom dead center) of the piston 15 on the inner wall on the exhaust valve 17 side is determined as the fuel injection direction.

  The injector 18 has a slit-like nozzle and injects fuel in a substantially fan shape having a relatively small thickness. The injector 18 is mounted so that the fuel spray thickness center plane coincides with the longitudinal plane passing through the cylinder center axis parallel to the forward tumble flow T.

  The spark plug 19 is provided in the combustion chamber 21. The air-fuel mixture sucked into the combustion chamber 21 is ignited at a predetermined timing by the spark plug 19. The ignited air-fuel mixture burns to generate exhaust gas, which is exhausted through the exhaust passage 13.

  A fuel temperature sensor 22 is provided in the fuel tank 11. The fuel temperature of the fuel stored in the fuel tank 11 is detected by the fuel temperature sensor 22. The detected fuel temperature is transmitted to the ECU 23 as a signal.

  An intake air temperature sensor 24 is provided in the intake passage 12. An intake air temperature of air to be taken into the combustion chamber 21 is detected by the intake air temperature sensor 24. The detected intake air temperature is transmitted to the ECU 23 as a signal.

  The engine 10 is provided with a water temperature sensor 25 and a rotation sensor 26. The coolant temperature of the engine 10 and the rotation speed of the engine 10 are detected by the water temperature sensor 25 and the rotation sensor 26, respectively. The detected coolant temperature and rotation speed are transmitted to the ECU 23 as signals.

  The ECU 23 controls the operation to be performed by each part of the engine 10 based on the acquired data. For example, as will be described later, the fuel injection timing from the injector 18 is controlled. Further, the ECU 23 also controls the ignition timing of the spark plug 19 and the amount of fuel injected from the injector 18.

  In order to determine the fuel injection timing, the ECU 23 determines whether the fuel injected during the intake stroke in the combustion chamber 21 is sufficiently vaporized before the start of the explosion stroke. In order to perform the discrimination, the cylinder bore inner wall temperature when the torque fluctuation for each cycle is not substantially generated for a certain fuel injection amount is determined in advance as the inner wall temperature threshold TV1.

  The higher the cylinder bore inner wall temperature, the higher the fuel vaporization speed on the cylinder bore inner wall surface. Therefore, it can be determined that the higher the cylinder bore inner wall temperature, the more fuel vaporization is promoted in one cycle. Since the cylinder bore inner wall temperature is correlated with the water temperature, the cylinder bore inner wall temperature is calculated based on the water temperature.

  When it is determined that the cylinder bore inner wall temperature exceeds the inner wall temperature threshold TV1 and the fuel is sufficiently vaporized, the vicinity of the BDC in the intake stroke is determined as the fuel injection timing. As described above, the forward tumble flow T is generated in the combustion chamber by the air sucked from the intake port 12a in the intake stroke. The generated forward tumble flow T attenuates during the period from the intake stroke to the compression stroke TDC, but the forward tumble flow T is strengthened by injecting fuel in the vicinity of the intake stroke BDC. By strengthening the forward tumble flow T, the forward tumble flow T is reliably maintained even in the compression stroke, and turbulence is generated in the cylinder in the vicinity of the TDC in the compression stroke. This turbulence in the cylinder improves the ignitability of the air-fuel mixture.

  When the cylinder bore inner wall temperature falls below the inner wall temperature threshold TV1 and it is determined that the fuel cannot be sufficiently vaporized based on other factors as will be described later, the top surface of the piston 15 passes the injection point P during the intake stroke. The timing to perform is determined as the reference injection timing for fuel injection. Note that at a temperature equal to or lower than the inner wall temperature threshold TV1, a correspondence map of retardation correction values with respect to the cylinder bore inner wall temperature is determined in advance (see FIG. 2), and the retardation is corrected from the reference injection timing. Accordingly, the ECU 23 retards the fuel injection timing from the reference injection timing as the cylinder bore inner wall temperature increases in a situation where the cylinder bore inner wall temperature is lower than the inner wall temperature threshold TV1.

  In addition, in order to determine the fuel injection timing in the ECU 23, the fuel temperature, the intake air temperature, and the engine speed when the torque fluctuation for each cycle is not substantially generated with respect to a constant fuel injection amount are the fuel temperature threshold value. It is predetermined as TV2, intake air temperature threshold TV3, and rotation speed threshold TV4.

  The higher the fuel temperature and the intake air temperature, the higher the fuel vaporization speed. Therefore, it can be determined that the higher the fuel temperature and the intake air temperature, the more fuel vaporization is promoted in one cycle. Further, when the engine speed increases, the time of the intake stroke and the compression stroke in one cycle is shortened, so that the amount of fuel vaporized decreases. Therefore, it can be determined that the fuel cannot be sufficiently vaporized in one cycle as the engine speed increases.

  Similar to the cylinder bore inner wall temperature, it is determined that the fuel is sufficiently vaporized when the fuel temperature exceeds the fuel temperature threshold TV2, the intake air temperature exceeds the intake air temperature threshold TV3, or the engine speed falls below the engine speed threshold TV4. . As described above, when it is determined that the fuel is sufficiently vaporized due to any factor, the vicinity of the BDC in the intake stroke is determined as the fuel injection timing.

  Similar to the cylinder bore inner wall temperature, when the fuel temperature is below the fuel temperature threshold TV2, the intake air temperature is below the intake air temperature threshold TV3, and the engine speed is above the engine speed threshold TV4, the top surface of the piston 15 is in the intake stroke. The timing for passing the injection point P is determined as the reference injection timing.

  Note that at a temperature equal to or lower than the fuel temperature threshold TV2, a correspondence map of the retardation correction value with respect to the fuel temperature is predetermined (see FIG. 3), and the retardation is corrected from the reference injection timing. Therefore, the ECU 23 retards the fuel injection timing from the reference injection timing as the fuel temperature increases in a situation where the fuel temperature is lower than the fuel temperature threshold TV2.

  Note that, at a temperature equal to or lower than the intake air temperature threshold TV3, a correspondence map of the retardation correction value with respect to the intake air temperature is predetermined (see FIG. 4), and the retardation is corrected from the reference injection timing. Therefore, the ECU 23 retards the fuel injection timing from the reference injection timing as the intake air temperature increases in a situation where the intake air temperature is lower than the intake air temperature threshold TV3.

  It should be noted that at a rotation speed equal to or higher than the rotation speed threshold TV4, a correspondence map of the retardation correction value with respect to the engine rotation speed is determined in advance, and the retardation is corrected from the reference injection timing. Therefore, the ECU 23 retards the fuel injection timing from the reference injection timing as the engine rotation speed decreases in a situation where the engine rotation speed exceeds the rotation speed threshold TV4.

  Next, the control for determining the fuel injection timing that the ECU 23 causes each part of the engine 10 to execute according to the cylinder bore inner wall temperature and the like according to the present embodiment will be described using the flowchart of FIG. 6. In the control of determining the fuel injection timing, various operations are executed at a time determined for each step until the engine 10 is warmed up.

  In step S100, the ECU 23 acquires water temperature data of the engine 10. In the next step S101, the ECU 23 calculates the cylinder bore inner wall temperature on the exhaust valve 17 side based on the acquired water temperature data.

  In the next step S102, it is determined whether or not the calculated cylinder bore inner wall temperature is lower than the inner wall temperature threshold TV1. When the cylinder bore inner wall temperature exceeds the inner wall temperature threshold TV1, the process proceeds to step S112. When the cylinder bore inner wall temperature is lower than the inner wall temperature threshold TV1, the process proceeds to step S103.

  In step S103, the ECU 23 acquires fuel temperature data. In the next step S104, it is determined whether or not the fuel temperature is below the fuel temperature threshold TV2. When the fuel temperature exceeds the fuel temperature threshold TV2, the process proceeds to step S112. If the fuel temperature falls below the fuel temperature threshold TV2, the process proceeds to step S105.

  In step S105, the ECU 23 acquires intake air temperature data. In the next step S106, it is determined whether or not the intake air temperature is lower than the intake air temperature threshold TV3. When the intake air temperature exceeds the intake air temperature threshold TV3, the process proceeds to step S112. When the intake air temperature is lower than the intake air temperature threshold TV3, the process proceeds to step S107.

  In step S107, the ECU 23 acquires engine speed data. In the next step S108, it is determined whether or not the engine speed exceeds a speed threshold TV4. If the engine speed is below the speed threshold TV4, the process proceeds to step S112. If the engine speed is below the speed threshold TV4, the process proceeds to step S109.

  In step S109, the timing at which the top surface of the piston 15 passes the injection point P in the intake stroke is determined as the reference injection timing T1. Next, the process proceeds to step S110, and a retardation correction value corresponding to the cylinder bore inner wall temperature calculated in step S101 is acquired. Further, the retardation correction value corresponding to the fuel temperature acquired in step S103 is read. Further, the retard correction value corresponding to the intake air temperature acquired in step S105 is read. Further, the retard correction value corresponding to the engine speed acquired in step S107 is read. In step S111, the fuel injection timing is determined by correcting the reference injection timing T1 determined in step S109 with the respective retard correction values acquired in step S110.

  As described above, when the cylinder bore inner wall temperature exceeds the inner wall temperature threshold TV1 at step S102, when the fuel temperature exceeds the fuel temperature threshold TV2 at step S104, when the intake air temperature exceeds the intake temperature threshold TV3 at step S106, or step When the engine speed is lower than the rotation speed threshold TV4 in S108, the process proceeds to step S112, and the fuel injection timing is set near the intake stroke BDC.

  According to the spark ignition internal combustion engine having the above-described configuration, it is possible to suppress torque fluctuation and an increase in unburned gas in the exhaust gas in a situation where fuel cannot be sufficiently vaporized in the combustion chamber. Below, the effect of this embodiment is demonstrated in detail.

  Generally, in order to increase the combustion speed during homogeneous combustion, generation of tumble and enhancement of tumble are required in the combustion chamber 21. In order to reinforce the tumble generated by the intake air from the intake port 12a, it is desirable that the fuel be injected near the BDC in the intake stroke.

  On the other hand, in the injection in the vicinity of the BDC toward the injection direction designed to strengthen the tumble, fuel is injected to the inner wall of the cylinder bore. During normal operation, such as when the engine 10 is warmed up or when the fuel temperature is high, the fuel is sufficiently vaporized before reaching the cylinder bore inner wall, or liquid fuel that has reached the cylinder bore inner wall is also present. It is fully vaporized until the explosion process. However, when the fuel temperature and the intake air temperature are low, or when the engine speed is high, the fuel cannot be sufficiently vaporized until it reaches the cylinder bore inner wall, and the liquid fuel may reach the cylinder bore inner wall.

  The fuel that has been injected from the injector 18 and has not vaporized and has reached the inner wall of the cylinder 20 (see G in FIG. 7) spreads on the inner wall of the cylinder bore and the top surface of the piston 15. Since the cylinder bore inner wall is covered with the lubricating oil, the fuel spread on the cylinder bore inner wall is adsorbed by the lubricating oil covering the cylinder bore inner wall. On the other hand, the piston 15 is not covered with the lubricating oil, and the fuel spreads on the top surface of the piston 15. Generally, the vaporization rate of the fuel adhering to the top surface of the piston 15 is faster than the vaporization rate of the fuel adsorbed to the lubricating oil. Therefore, the fuel spread on the top surface of the piston 15 vaporizes faster than the fuel spread on the inner wall of the cylinder bore. Furthermore, since the top surface of the piston 15 is hotter than the inner wall of the cylinder 20, the fuel spread on the top surface of the piston 15 vaporizes faster than the fuel spread on the inner wall of the cylinder bore.

  Therefore, in the present embodiment, when the fuel cannot be sufficiently vaporized in the cylinder bore inner wall before reaching the cylinder bore inner wall or before ignition, the fuel injection timing is retarded from the reference injection timing in the range from the reference injection timing to the intake stroke BDC. I am letting. That is, the fuel injection timing is advanced from the intake stroke BDC. By advancing from the BDC, the fuel adhesion area spreading on the inner wall of the cylinder 20 decreases, while the fuel adhesion area spreading on the top surface of the piston 15 increases.

  Therefore, even when fuel cannot be sufficiently vaporized in the cylinder bore inner wall before reaching the cylinder bore inner wall or before ignition, the amount of fuel vaporized can be kept constant. Therefore, fluctuations in the amount of fuel vaporized for each cycle can be suppressed, and fluctuations in torque and increase in unburned gas can be suppressed.

  Further, since the injection timing is greatly advanced from the intake stroke BDC as the cylinder bore inner wall temperature becomes lower, the fuel adhesion area spreading on the top surface of the piston 15 further increases as the cylinder bore inner wall temperature becomes lower. Therefore, the injection timing is adjusted so as to promote the vaporization of the fuel so that the situation becomes more disadvantageous for the vaporization of the fuel on the inner wall of the cylinder bore. Therefore, it is possible to sufficiently vaporize the fuel regardless of whether or not the fuel vaporization is disadvantageous.

  If the injection timing is further advanced and the piston 15 is injected before it passes the injection point P in the intake stroke, the injected fuel (see symbol G in FIG. 8) is transferred from the top surface of the piston 15 onto the cylinder bore inner wall. spread. In this case, conversely, the fuel spreading on the inner wall of the cylinder bore becomes larger than the fuel spreading on the top surface of the piston 15, which is disadvantageous for fuel vaporization. Therefore, in this embodiment, the timing between the timing when the top surface of the piston 15 passes the injection point P and the timing when it reaches the BDC in the intake stroke is determined as the injection timing.

  Note that, when the fuel injection timing is controlled according to the fuel temperature, the intake air temperature, and the engine speed as in the present embodiment, the same effect as the control according to the cylinder bore inner wall temperature can be obtained.

  In the present embodiment, as described above, the cylinder bore inner wall temperature, the fuel temperature, the intake air temperature, or the advance angle amount from the intake stroke BDC is adjusted according to the engine speed, but the cylinder bore inner wall temperature, When the fuel temperature or the intake air temperature falls below the respective threshold value, or when the engine speed exceeds the speed threshold value TV4, the injection timing is advanced by a predetermined advance angle amount without adjusting the advance angle amount. Also good. If injection is performed after the top surface of the piston 15 in the intake stroke passes through the injection point P and before reaching the BDC, the adhesion area of the fuel spreading on the top surface of the piston 15 increases. Therefore, it is possible to sufficiently suppress the fluctuation of the vaporization amount for each cycle as compared with the case of injection near the intake stroke BDC.

  In the present embodiment, the fuel injection timing is advanced from the intake stroke BDC according to the cylinder bore inner wall temperature, fuel temperature, intake air temperature, and engine speed. The injection timing may be advanced according to any factor given.

  In the case where the advance timing of the injection timing is adjusted based on other factors, the fuel injection timing is determined in the vicinity of the BDC in the intake stroke when the factors are within a range where it is determined that fuel vaporization is promoted. Is done. On the other hand, when the factor deviates from the range, the fuel injection timing is determined between the timing when the top surface of the piston 15 passes the injection point P and the timing when it reaches the BDC in the intake stroke.

  In the present embodiment, the fuel injection timing is determined based on the cylinder bore inner wall temperature, the fuel temperature, the intake air temperature, and the engine speed, but the injection timing may be determined based on at least one factor. Good. In particular, the cylinder bore inner wall temperature has a greater effect on fuel vaporization than other factors, and therefore it is possible to simplify the process by determining the injection timing using only the cylinder bore inner wall temperature.

  Further, in the present embodiment, it is assumed that the fuel injection timing is performed once during the intake stroke, but the present invention is also applicable to a case where fuel injection is performed a plurality of times during a single cycle, for example. For example, when fuel injection is normally performed in the vicinity of the intake stroke BDC in at least one fuel injection among a plurality of injections, the injection timing is advanced as in the present embodiment when the fuel cannot be sufficiently vaporized. Horned.

  Further, in the present embodiment, the injection direction of the injector 18 is determined in the direction of the inner wall of the cylinder 20 in order to strengthen the tumble. However, not only for the purpose of strengthening the tumble but also for any other purpose. If the injection direction is the direction facing the inner wall surface of the cylinder 20 between TDC and BDC of the piston 15, this embodiment can be applied.

  In this embodiment, the fuel temperature of the fuel and the temperature of the intake air are directly detected by the temperature sensor. However, the fuel temperature and the like are indirectly set so that the cylinder inner wall temperature is detected by detecting the water temperature. It may be detected.

1 is a block diagram schematically showing a schematic configuration of an engine to which an embodiment of the present invention is applied. It is a graph which shows the retardation correction value from the injection reference time with respect to the cylinder bore inner wall temperature. It is a graph which shows the retardation correction value from the injection reference time with respect to fuel temperature. It is a graph which shows the retardation correction value from the injection reference time with respect to intake air temperature. It is a graph which shows the retardation correction value from the injection reference time with respect to an engine speed. It is a flowchart which shows the program structure of the fuel injection timing determination control which ECU performs. It is a figure which shows the adhesion state in the combustion chamber in the case of injecting a fuel between a piston passing through an injection point and reaching an intake stroke BDC. It is a figure which shows the adhesion state in the combustion chamber of the injected fuel in case a fuel is injected before a piston passes an injection point.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 12a Intake port 15 Piston 18 Injector 20 Cylinder 21 Combustion chamber 22 Fuel temperature sensor 23 ECU
24 Intake air temperature sensor 25 Water temperature sensor 26 Rotation sensor

Claims (6)

Injection means for injecting fuel toward an injection point which is a predetermined position between the top dead center and the bottom dead center on the inner wall of the cylinder;
Detecting means for detecting a factor affecting the vaporization of the fuel injected by the injection means in a combustion chamber;
When the factor detected by the detection means deviates from a predetermined range where vaporization of the fuel in the combustion chamber is promoted, a piston that moves from top dead center to bottom dead center during the intake stroke passes through the injection point. A spark ignition internal combustion engine comprising: control means for controlling the injection means to inject the fuel during a period from when it is reached to when it reaches bottom dead center.   The detection means detects a factor that affects vaporization in the bore inner wall on the injection point side, and the control means controls the injection timing of the fuel by the injection means based on the factor. 2. The spark ignition internal combustion engine according to claim 1.   The spark ignition internal combustion engine according to claim 2, wherein the factor affecting the vaporization is the bore inner wall temperature on the injection point side. An intake port for performing intake to the combustion chamber so as to generate a tumble flow in the combustion chamber;
The said injection | pouring point is defined so that the said tumble flow may be strengthened when the said injection means injects a fuel toward the said injection | spraying point, The any one of Claims 1-3 characterized by the above-mentioned. Spark ignition internal combustion engine.   The spark ignition internal combustion engine according to claim 4, wherein the intake port generates a forward tumble flow in the combustion chamber, and the injection point is defined on an inner wall of the exhaust side bore.   2. The control unit according to claim 1, wherein the control unit controls the injection unit to inject the fuel later as the factor changes in a direction to promote the vaporization of the fuel outside the predetermined range. The spark ignition internal combustion engine described.

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