JP3939450B2 - Fuel injection amount control device for in-vehicle internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection amount control device for an in-vehicle internal combustion engine in which a combustion method is switched according to an engine operating state.
[0002]
[Prior art]
In recent years, an internal combustion engine that performs “stratified combustion” capable of combustion at an air-fuel ratio leaner than the stoichiometric air-fuel ratio at the time of engine low load has been proposed and put into practical use for the purpose of improving fuel efficiency. As an internal combustion engine that executes such “stratified combustion”, for example, an engine described in JP-A-4-228856 is known.
[0003]
In the internal combustion engine described in the publication, the fuel injected and supplied into the combustion chamber in the compression stroke of the engine is collected around the spark plug, and an air-fuel mixture composed of the collected fuel and air in the combustion chamber is ignited. By igniting the plug, “stratified combustion” is executed. In this “stratified combustion”, the throttle valve is controlled to open more than in the case of “homogeneous combustion” in order to increase the average air-fuel ratio of the air-fuel mixture, so that the pumping loss is reduced.
[0004]
In an internal combustion engine in which the “stratified combustion” is performed, the fuel injection amount is set on the basis of the accelerator opening so that an engine output torque corresponding to the accelerator pedal depression amount (accelerator opening) is obtained. An amount of fuel corresponding to the amount of fuel injected is supplied to the combustion chamber. In this way, by adjusting the fuel injection amount according to the accelerator opening, the output torque of the internal combustion engine is controlled to a value according to the accelerator opening. Since the output torque required for the internal combustion engine increases as the accelerator opening increases, the fuel injection amount is set to a larger value as the accelerator opening increases.
[0005]
However, in the “stratified combustion”, if the fuel injection amount is excessively increased, the fuel concentration of the air-fuel mixture around the spark plug increases, so that the torque fluctuation of the internal combustion engine increases and the operating state deteriorates. Therefore, in the internal combustion engine described in the above publication, the combustion mode is switched from “stratified combustion” to “homogeneous combustion” at high rotation and high load where the fuel injection amount increases. In this “homogeneous combustion”, the air-fuel mixture in which the fuel is evenly mixed with the air is burned, so even if the fuel injection amount increases, the torque fluctuation does not increase compared to the case of “stratified combustion”. .
[0006]
The fuel injection amount when the combustion method is switched between “stratified combustion” and “homogeneous combustion” is the largest value at which the torque fluctuation does not exceed the allowable value. The reason why the combustion method is switched in this way is to execute “stratified combustion” in the widest possible range of the entire operation range of the internal combustion engine and improve the fuel efficiency of the internal combustion engine.
[0007]
[Problems to be solved by the invention]
By the way, although the internal combustion engine is mounted on an automobile or the like, if the fuel injection amount determined according to the accelerator opening is reduced in order to expand the operation range in which “stratified combustion” is performed in the engine, the start of the automobile is started. The acceleration performance at the time will be reduced. It is also conceivable to improve the acceleration performance by increasing the fuel injection amount determined according to the accelerator opening, but in this case, in the internal combustion engine, “stratification” is performed so that the torque fluctuation does not exceed an allowable value. The operating range in which "combustion" is performed must be narrowed, and the fuel efficiency of the engine will deteriorate.
[0008]
The present invention has been made in view of such circumstances, and an object of the present invention is to improve the acceleration performance at the start of the vehicle while preventing the engine operating region for executing stratified combustion from becoming narrow. An object of the present invention is to provide a fuel injection amount control device for an in-vehicle internal combustion engine.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a combustion system of stratified combustion is employed in which fuel is injected during a compression stroke when the engine is mounted in a vehicle and the engine operating state is in a low rotation and low load region. In a fuel injection amount control device for a cylinder injection type in- vehicle internal combustion engine that adopts a homogeneous combustion combustion method in which fuel is injected during an intake stroke when the state is in a high rotation and high load range, the vehicle is at the start Start determination means for determining, and correction means for increasing and correcting the fuel injection amount of the internal combustion engine within a range in which the combustion system is maintained in stratified combustion when the start determination means determines that the vehicle is starting. Prepared.
[0010]
According to this configuration, since the fuel injection amount is corrected to be increased within a range in which the combustion method is maintained in stratified combustion when the vehicle starts, it is possible to prevent the operating region where stratified combustion is performed in the internal combustion engine from being narrowed. As a result, the acceleration performance at the start of the vehicle is improved, and it is possible to achieve both improvement in fuel efficiency and improvement in acceleration performance at the start.
[0011]
According to a second aspect of the invention, in the first aspect of the invention, the fuel injection amount is set based on an accelerator operation amount, and the correction means corrects the accelerator operation amount to correct the fuel injection amount. The amount was corrected to be increased.
[0012]
When the vehicle starts, the accelerator operation amount is increased and the fuel injection amount is increased. Therefore, according to the same configuration in which the accelerator operation amount is corrected and the fuel injection amount is increased, the engine output torque can be easily adjusted with respect to the accelerator operation amount when the vehicle starts.
[0013]
According to a third aspect of the present invention, in the first or second aspect of the invention, the correction means gradually increases the fuel injection amount increase correction amount when the start determination means determines that the vehicle is not starting. It was supposed to be small.
[0014]
According to this configuration, since the increase correction amount of the fuel injection amount is gradually reduced immediately after starting the vehicle, the output torque of the internal combustion engine changes smoothly according to the decrease of the increase correction amount, and the increase amount It is possible to prevent a step in the output torque of the internal combustion engine when the correction amount is reduced.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an in-line four-cylinder automobile gasoline engine will be described with reference to FIGS.
[0016]
As shown in FIG. 1, in the engine 11, a piston 12 provided in the cylinder block 11 a so as to be able to reciprocate is connected to a crankshaft 14 that is an output shaft of the engine 11 via a connecting rod 13. The reciprocating movement of the piston 12 is converted into rotation of the crankshaft 14 by the connecting rod 13. Further, a recess 12 a necessary for executing stratified combustion is formed in the head of the piston 12.
[0017]
The crankshaft 14 is connected to a vehicle wheel 28 via a transmission 27 and the like. Based on the rotation of the wheels 28, the vehicle speed sensor 28a detects the vehicle speed SPD of the automobile on which the engine 11 is mounted. The transmission 27 is driven and controlled by the transmission control computer 29, and the shift position is changed according to the running state of the automobile and the operating state of the engine 11. The transmission position of the transmission 27 is switched between six positions such as 1st speed, 2nd speed, 3rd speed, 4th speed, neutral, and reverse.
[0018]
A signal rotor 14 a is attached to the crankshaft 14. A plurality of protrusions 14b are provided on the outer periphery of the signal rotor 14a at equal angles with the axis of the crankshaft 14 as the center. A crank position sensor 14c is provided on the side of the signal rotor 14a. Then, when the crankshaft 14 rotates and each projection 14b of the signal rotor 14a sequentially passes the side of the crank position sensor 14c, the sensor 14c detects a pulse shape corresponding to the passage of each projection 14b. A signal is output.
[0019]
On the other hand, a cylinder head 15 is provided at the upper end of the cylinder block 11 a, and a combustion chamber 16 is provided between the cylinder head 15 and the piston 12. The combustion chamber 16 communicates with a pair of intake ports 17a, 17b provided in the cylinder head 15 and a pair of exhaust ports 18a, 18b (FIG. 1 shows one intake port 17b and one exhaust port). Only 18b is shown). The plane cross-sectional shapes of these intake and exhaust ports 17a, 17b, 18a, 18b are shown in FIG.
[0020]
As shown in the figure, the intake port 17a is a helical port that extends in a curved manner, and the intake port 17b is a straight port that extends in a straight line. When air passes through the intake port (helical port) 17 a and is sucked into the combustion chamber 16, a swirl is generated in the combustion chamber 16 in the direction indicated by the dashed arrow. An intake valve 19 and an exhaust valve 20 are provided in the intake ports 17a and 17b and the exhaust ports 18a and 18b, respectively.
[0021]
As shown in FIG. 1, the cylinder head 15 rotatably supports an intake cam shaft 21 and an exhaust cam shaft 22 for opening and closing the intake valve 19 and the exhaust valve 20. The intake and exhaust camshafts 21 and 22 are connected to the crankshaft 14 via timing belts and gears (both not shown), and the rotation of the crankshaft 14 is transmitted by the belts and gears. . When the intake camshaft 21 rotates, the intake valve 19 is driven to open and close, and the intake ports 17a and 17b and the combustion chamber 16 are communicated and disconnected. When the exhaust camshaft 22 rotates, the exhaust valve 20 is driven to open and close, and the exhaust ports 18a and 18b and the combustion chamber 16 are communicated and disconnected.
[0022]
In the cylinder head 15, a cam position sensor 21 b that detects a protrusion 21 a provided on the outer peripheral surface of the shaft 21 and outputs a detection signal is provided on the side of the intake camshaft 21. When the intake camshaft 21 rotates, the projection 21a of the shaft 21 passes the side of the cam position sensor 21b. In this state, detection signals are output from the cam position sensor 21b at predetermined intervals corresponding to the passage of the protrusion 21a.
[0023]
An intake pipe 30 and an exhaust pipe 31 are connected to the intake ports 17a and 17b and the exhaust ports 18a and 18b, respectively. An intake passage 32 is formed in the intake pipe 30 and the intake ports 17a and 17b, and an exhaust passage 33 is formed in the exhaust pipe 31 and the exhaust ports 18a and 18b. A throttle valve 23 is provided in the upstream portion of the intake passage 32. The throttle valve 23 is rotated by driving a throttle motor 24 composed of a direct current (DC) motor to adjust the opening degree. The opening of the throttle valve 23 is detected by a throttle position sensor 44.
[0024]
The driving of the throttle motor 24 is controlled based on the opening degree (accelerator depression amount) of an accelerator pedal 25 provided in the interior of the automobile. That is, when the driver of the automobile depresses the accelerator pedal 25, the accelerator depression amount is detected by the accelerator position sensor 26, and the throttle motor 24 is driven and controlled based on the detection signal of the sensor 26. By adjusting the opening of the throttle valve 23 based on the drive control of the throttle motor 24, the air flow area of the intake passage 32 changes, and the amount of air taken into the combustion chamber 16 is adjusted.
[0025]
A vacuum sensor 36 that detects the pressure in the passage 32 is provided in a portion of the intake passage 32 that is located downstream of the throttle valve 23. The vacuum sensor 36 outputs a detection signal corresponding to the detected pressure in the intake passage 32. A swirl control valve (SCV) 34 is provided in a portion of the intake passage 32 that is located downstream of the vacuum sensor 36 and communicates with the intake port (straight port) 17b. The SCV 34 is rotated by driving the swirl motor 35 to adjust the opening degree. As the opening of the SCV 34 becomes smaller, the amount of air passing through the intake port (helical port) 17a shown in FIG. 2 increases and the swirl generated in the combustion chamber 16 becomes stronger.
[0026]
As shown in FIG. 1, the cylinder head 15 has a fuel injection valve 40 that injects fuel into the combustion chamber 16, and a mixture of fuel and air filled in the combustion chamber 16. A spark plug 41 that performs ignition is provided. The ignition timing of the air-fuel mixture by the spark plug 41 is adjusted by an igniter 41 a provided above the spark plug 41. When the fuel is injected from the fuel injection valve 40 into the combustion chamber 16, the fuel is mixed with the air sucked into the combustion chamber 16 via the intake passage 32, and the air and fuel are mixed in the combustion chamber 16. An air-fuel mixture is formed. Further, the air-fuel mixture in the combustion chamber 16 is ignited by the spark plug 41 and combusted, and the air-fuel mixture after combustion is sent to the exhaust passage 33 as exhaust gas.
[0027]
Next, the electrical configuration of the fuel injection amount control device for the engine 11 in the present embodiment will be described with reference to FIG.
The fuel injection amount control device includes an electronic control unit (hereinafter referred to as “ECU”) 92 for controlling the operating state of the engine 11 such as ignition timing control, throttle opening control, and SCV opening control. The ECU 92 is configured as a logical operation circuit including a ROM 93, a CPU 94, a RAM 95, a backup RAM 96, and the like.
[0028]
Here, the ROM 93 is a memory in which various control programs and maps to be referred to when executing these various control programs are stored. The CPU 94 performs arithmetic processing based on the various control programs and maps stored in the ROM 93. Execute. The RAM 95 is a memory for temporarily storing calculation results in the CPU 94, data input from each sensor, and the like. The backup RAM 96 is a non-volatile memory for storing data to be saved when the engine 11 is stopped. The ROM 93, CPU 94, RAM 95, and backup RAM 96 are connected to each other via a bus 97 and are connected to an external input circuit 98 and an external output circuit 99.
[0029]
A crank position sensor 14c, a cam position sensor 21b, an accelerator position sensor 26, a vehicle speed sensor 28a, a transmission control computer 29, a vacuum sensor 36, a throttle position sensor 44, and the like are connected to the external input circuit 98. On the other hand, a throttle motor 24, a swirl motor 35, a fuel injection valve 40, an igniter 41a, and the like are connected to the external output circuit 99.
[0030]
The ECU 92 configured as described above obtains the intake pressure PM based on the detection signal from the vacuum sensor 36 and obtains the accelerator depression amount ACCP based on the detection signal from the accelerator position sensor 26. Further, the ECU 92 obtains the engine speed NE based on the detection signal from the crank position sensor 14c. Based on the intake pressure PM and the engine speed NE obtained as described above, or the accelerator depression amount ACCP and the engine speed NE, the fuel injection amount Q is map-calculated with reference to a known map. The fuel injection amount Q calculated in this way increases as the engine speed NE increases, and increases as the intake pressure PM or the accelerator depression amount ACCP increases.
[0031]
The engine load of the engine 11 is represented by the fuel injection amount Q. The ECU 92 sets the combustion method of the engine 11 to “homogeneous combustion” when the operating state of the engine 11 is in the high rotation and high load region, and sets the combustion method of the engine 11 to “ It is called “stratified combustion”. In this way, the combustion method is changed because the engine output is increased by setting the air-fuel ratio of the air-fuel mixture to the rich side during high rotation and high load where high output is required, and low rotation and low load that does not require very high output This is because sometimes the air-fuel ratio is set to a lean value to improve fuel efficiency.
[0032]
When the combustion method of the engine 11 is set to “homogeneous combustion”, the ECU 92 performs a map calculation of the fuel injection amount Q based on the intake pressure PM obtained based on the detection signal from the vacuum sensor 36 and the engine speed NE. The ECU 92 controls the fuel injection valve 40 to inject an amount of fuel corresponding to the fuel injection amount Q from the fuel injection valve 40 during the intake stroke of the engine 11. In the air-fuel mixture formed in the combustion chamber 16 based on such fuel injection, the air-fuel ratio becomes a stoichiometric air-fuel ratio or a value larger than the stoichiometric air-fuel ratio. Further, the ECU 92 drives and controls the throttle motor 24, the igniter 41a, the swirl motor 35, and the like so that the throttle opening, the ignition timing, the opening of the SCV 34, and the like are suitable for “homogeneous combustion”.
[0033]
When the combustion method of the engine 11 is “stratified combustion”, the ECU 92 calculates the fuel injection amount Q from the accelerator depression amount ACCP and the engine speed NE. The ECU 92 injects fuel during the compression stroke of the engine 11 based on the fuel injection amount Q. In the air-fuel mixture formed in the combustion chamber 16 by such fuel injection, the air-fuel ratio is set to a leaner value than the air-fuel ratio at the time of “homogeneous combustion”. Further, the ECU 92 drives and controls the throttle motor 24, the igniter 41a, the swirl motor 35, and the like so that the throttle opening degree, the ignition timing, the opening degree of the SCV 34, and the like are suitable for “stratified combustion”.
[0034]
During such “stratified combustion”, the fuel injected from the fuel injection valve 40 during the compression stroke of the engine 11 enters the recess 12 a (FIG. 1) provided in the head of the piston 12. Furthermore, a swirl is generated based on the opening degree adjustment of the SCV 34 by the drive control of the swirl motor 35, and the fuel is collected around the spark plug 41 by the movement of the swirl and the piston 12. By collecting the fuel around the spark plug 41 in this way, even if the average air-fuel ratio of the entire air-fuel mixture in the combustion chamber 16 is made larger than that during “homogeneous combustion”, the air-fuel ratio of the air-fuel mixture around the plug 41 is maintained. A good air-fuel mixture is ignited that is suitable for ignition. Further, in order to increase the average air-fuel ratio of the entire air-fuel mixture in the combustion chamber 16 as compared with “homogeneous combustion”, the throttle opening is controlled to the open side to increase the intake air amount. 11 pumping loss is reduced.
[0035]
Next, the outline of the fuel injection amount control of this embodiment will be described.
In the above-described engine 11, fuel injection is performed so that the fuel injection amount Q increases as the accelerator depression amount ACCP increases as shown in FIG. 4 under the condition that the engine speed NE is constant during “stratified combustion”. Perform quantity control. By such fuel injection amount control, an output torque of the engine 11 corresponding to the accelerator depression amount ACCP is obtained. Further, in the engine 11, when the fuel injection amount Q becomes larger than the predetermined value a under the condition that the engine speed NE is constant, the combustion system is switched from “stratified combustion” to “homogeneous combustion”.
[0036]
The predetermined value a is the largest value in the fuel injection amount Q at the time of executing “stratified combustion” so that the torque fluctuation of the engine 11 does not exceed the allowable value due to excessive fuel. When the fuel injection amount Q changes from the predetermined value a as a boundary, the combustion method of the engine 11 is switched between “stratified combustion” and “homogeneous combustion”, thereby causing the engine 11 to perform the “stratified combustion”. It is possible to improve fuel efficiency by making the operating range in which “stratified combustion” is executed in the engine 11 as wide as possible without causing large torque fluctuations due to excessive fuel.
[0037]
By the way, when the vehicle starts, since the accelerator depression amount ACCP gradually increases from “0”, “stratified combustion” is performed. However, at the time of “stratified combustion”, if the fuel injection amount Q determined according to the accelerator depression amount ACCP is made as small as possible for the purpose of improving fuel efficiency, the acceleration performance at the time of start of the vehicle is lowered.
[0038]
Further, in order to improve the acceleration performance at the time of start of the automobile, it is conceivable to set the fuel injection amount Q that changes in accordance with the accelerator depression amount ACCP, as shown by a broken line in FIG. However, in this case, the accelerator depression amount ACCP when the fuel injection amount Q reaches the predetermined value a becomes smaller than normal, and the position where the combustion system is switched in FIG. 4 changes from the point P1 to the point P2. As a result, the operating region where “stratified combustion” is performed in the engine 11 is narrowed, and the fuel consumption of the engine 11 is deteriorated.
[0039]
Therefore, in this embodiment, when it is determined that the vehicle is starting, the fuel injection amount Q is corrected to be increased by correcting the accelerator depression amount ACCP to the increasing side. By correcting the increase in the fuel injection amount Q, the acceleration performance at the start of the vehicle is improved, and the operating region where the “stratified combustion” is performed in the engine 11 is narrowed to prevent the fuel efficiency from deteriorating. Both performance improvement and prevention of fuel consumption deterioration can be achieved.
[0040]
Next, a procedure for correcting the accelerator depression amount ACCP for performing the fuel injection amount control will be described with reference to FIGS. 5 and 6 are flowcharts showing an accelerator depression amount correction routine for correcting the accelerator depression amount ACCP. This accelerator depression correction routine is executed through the ECU 92 by, for example, a time interruption every predetermined time.
[0041]
In the accelerator depression amount correction routine, the processes in steps S101 and S102 are for determining whether or not the accelerator depression amount ACCP has changed from “0” to a predetermined value. The ECU 92 determines whether the accelerator depression amount ACCP is a value other than “0” as a process of step S101, and determines whether the previous accelerator depression amount ACCP is “0” as a process of step S102. . If YES is determined in steps 101 and S102, that is, if the accelerator depression amount ACCP is changed from “0” to a predetermined value, the process proceeds to step S103.
[0042]
The ECU 92 stores “1” as a precondition fulfillment flag F in a predetermined area of the RAM 95 in the process of step S103. Therefore, when the precondition fulfillment flag F is set to “1”, the accelerator depression amount ACCP has changed from “0” to a predetermined value such as when the vehicle starts. After setting the precondition fulfillment flag F in this way, the process proceeds to step S104. Further, if it is determined NO in either one of the above steps S101 and S102, the process directly proceeds to step S104.
[0043]
The ECU 92 determines whether or not the precondition fulfillment flag F is set to “1” as the process of step S104. If “F = 1”, the ECU 92 proceeds to step S105 and counts up the counter C. The counter C indicates an elapsed time after “F = 1”, that is, an elapsed time after the accelerator depression amount ACCP changes from “0” to a predetermined value. If it is determined in step S104 that “F = 1” is not established, the process proceeds to step S106, and the ECU 92 resets the counter C to “0”.
[0044]
Thus, after executing any one of steps S105 and S106, the process proceeds to step S107 (FIG. 6). The process of step S107 is for determining whether or not the vehicle is starting. The ECU 92 determines whether or not all the correction execution conditions shown in the following (1) to (5) are satisfied as the process of step S107.
[0045]
(1) The precondition fulfillment flag F is “1” (2) The shift position of the transmission 27 is the first speed (3) The accelerator depression amount ACCP is not “0” (4) The vehicle speed SPD of the automobile is 10 km / h or less (5) The counter C is smaller than a predetermined value (for example, a value corresponding to 5 s). The speed change position of the transmission 27 is determined from the transmission control computer 29 for driving and controlling the transmission 27. The determination is made based on the output shift position signal. The vehicle speed SPD of the automobile is obtained based on a detection signal from the vehicle speed sensor 28a.
[0046]
When all the above conditions are satisfied, it is determined that the vehicle is starting, and the process proceeds to step S108. As a process of step S108, the ECU 92 calculates an accelerator correction coefficient e for increasing the fuel injection amount Q based on the current accelerator depression amount ACCP with reference to the map shown in FIG. In the subsequent process of step S109, the ECU 92 sets a value obtained by multiplying the current accelerator depression amount ACCP by the correction coefficient e as a new accelerator depression amount ACCP, and then ends this accelerator depression amount correction routine.
[0047]
The ECU 92 calculates the fuel injection amount Q based on the accelerator depression amount ACCP and the like by another routine. Since the accelerator depression amount ACCP is corrected to increase when the vehicle starts, the fuel injection amount Q calculated based on the accelerator depression amount ACCP and the like is also corrected to increase. The ECU 92 controls the fuel injection valve 40 based on the fuel injection amount Q that has been corrected to increase, and performs fuel injection, thereby improving the acceleration performance when the vehicle starts.
[0048]
On the other hand, in the process of step S107, if any one of the correction execution conditions shown in the above (1) to (5) is not satisfied, it is determined that the vehicle is not started, and the process proceeds to step S110. The ECU 92 stores “0” as a precondition fulfillment flag F in a predetermined area of the RAM 95 in the process of step S110. When “F = 0” is thus established, NO is determined in the process of step S104 (FIG. 5), the process proceeds to step S106, and the counter C is reset to “0”. Therefore, the counter C is incremented only when the automobile is started, and is returned to “0” when the automobile is not started.
[0049]
The ECU 92 determines whether or not the shift position of the transmission 27 is in the reverse (R range) as the processing of the subsequent step S111 (FIG. 6). If the shift position is reverse, the process proceeds to step S112, the accelerator correction coefficient e is set to “1.0”, and the process of step S109 is executed. In this case, since the accelerator correction coefficient e is “1.0”, the accelerator depression amount ACCP is not corrected to the increase side, and the fuel injection amount Q is corrected to be increased based on the correction of the accelerator depression amount ACCP. It will never be.
[0050]
On the other hand, if it is determined in step S111 that the shift position of the transmission 27 is not in reverse, the process proceeds to step S113. The processing of steps S113 to S115 is for gradually decreasing the accelerator correction coefficient e to “1.0” in order to restore the fuel injection amount Q that has been corrected to increase when the vehicle starts.
[0051]
In step S113, the ECU 92 sets a value obtained by subtracting “0.05” from the current accelerator correction coefficient e as a new accelerator correction coefficient e. Subsequently, as a process of step S114, the ECU 92 determines whether or not the accelerator correction coefficient e is smaller than “1.0”. If “e <1.0”, the process proceeds to the next step S115 to set the accelerator correction coefficient e to “1.0” and then proceeds to step S109. If not “e <1.0”, the process directly proceeds to step S109. move on.
[0052]
Accordingly, when the vehicle is not started, if the transmission position of the transmission 27 is reverse, the accelerator correction coefficient e is immediately set to “1.0”, and the accelerator depression amount ACCP is immediately corrected based on the accelerator correction coefficient e. It returns to the state without. Then, the fuel injection amount Q is also immediately returned to the state without correction. If the shift position of the transmission 27 is not reverse when the vehicle is not started, the accelerator correction coefficient e is gradually reduced to “1.0”, and the accelerator depression amount ACCP is gradually reduced to the accelerator correction coefficient e. It returns to the state without correction based on. Then, the fuel injection amount Q is gradually returned to the state without correction.
[0053]
Finally, the transition of the accelerator depression amount ACCP, the accelerator correction coefficient e, the fuel injection amount Q, and the vehicle speed SPD when the vehicle starts and after the start will be described with reference to the time chart of FIG.
[0054]
When it is determined at the start of the vehicle that the vehicle is starting by the process of step S107, the accelerator correction coefficient e is set to a value larger than “1.0” as shown by a solid line in FIG. 8B. The As a result, as shown by a solid line in FIG. 8A, the accelerator depression amount ACCP is corrected to the increase side by the amount that the accelerator correction coefficient e has increased. When the accelerator depression amount ACCP is corrected to the increase side in this way, the fuel injection amount Q calculated based on the accelerator depression amount ACCP and the like is also corrected to increase as shown by the solid line in FIG. . By increasing the fuel injection amount Q, the acceleration performance at the start of the vehicle is improved.
[0055]
After the vehicle has started, as indicated by a solid line in FIG. 8D, for example, when the vehicle speed SPD becomes higher than 10 km / h, it is determined that the vehicle is not at the start by the processing of step S107. The accelerator correction coefficient e is gradually reduced to “1.0” as shown by the solid line in FIG. As a result, as shown by a solid line in FIG. 8A, the accelerator depression amount ACCP is gradually returned to the uncorrected state as the accelerator correction coefficient e gradually decreases. As described above, when the accelerator depression amount ACCP is gradually returned to the state without correction, the increase correction amount of the fuel injection amount Q gradually decreases, and the fuel injection amount Q is shown by a solid line in FIG. Gradually returned to the state without correction.
[0056]
By performing the increase correction of the fuel injection amount Q at the time of start of the vehicle as described above, the acceleration performance at the time of start of the vehicle is improved while preventing the operation region where “stratified combustion” is performed in the engine 11 from being narrowed. To come. Further, after the vehicle starts, the increase correction amount of the fuel injection amount Q is gradually reduced, so that the output torque of the engine 11 changes smoothly according to the decrease of the increase correction amount. Accordingly, when the increase correction amount of the fuel injection amount Q is decreased, it is possible to prevent the drivability from deteriorating due to a step in the output torque of the engine 11.
[0057]
According to the present embodiment in which the processing detailed above is performed, the following effects can be obtained.
(1) Since the fuel injection amount Q is corrected to be increased when the vehicle is started, the operation region where “stratified combustion” is performed in the engine 11 is prevented from being narrowed, and the acceleration performance at the start of the vehicle is improved. Therefore, it is possible to achieve both the prevention of deterioration of fuel consumption and the improvement of acceleration performance.
[0058]
(2) When the vehicle starts, the accelerator depression amount ACCP is increased from “0” and the fuel injection amount Q is increased. Therefore, by correcting the accelerator depression amount ACCP based on the accelerator correction coefficient e and increasing the fuel injection amount Q, it is easy to adjust the output torque of the engine 11 with respect to the accelerator depression amount ACCP even when the vehicle starts. .
[0059]
(3) Since the increase correction amount of the fuel injection amount Q is gradually reduced after the vehicle starts, the output torque of the engine 11 changes smoothly according to the decrease of the increase correction amount, and a step is generated in the output torque. In particular, drivability can be prevented from deteriorating.
[0060]
In addition, this embodiment can also be changed as follows, for example.
In the present embodiment, the fuel injection amount Q is corrected by correcting the accelerator depression amount ACCP based on the accelerator correction coefficient e. Instead, a predetermined correction amount is added to the fuel injection amount Q. Alternatively, the fuel injection amount Q may be corrected by multiplying by a predetermined correction coefficient.
[0061]
In this embodiment, the increase correction amount of the fuel injection amount Q at the start of the automobile is gradually decreased after the start of the automobile, but the decrease does not necessarily have to be gradually performed. In the present embodiment, the accelerator correction coefficient e is calculated using a map, but instead of this, calculation using an equation may be performed.
[0062]
Instead of multiplying the accelerator correction coefficient e by the accelerator depression amount ACCP, a correction for increasing the fuel injection amount Q by adding a predetermined correction amount to the accelerator depression amount ACCP may be performed.
[0063]
【The invention's effect】
According to the first aspect of the present invention , since the fuel injection amount is corrected to be increased within a range in which the combustion system is maintained in stratified combustion when the vehicle starts , the operating range of the internal combustion engine that executes stratified combustion is narrowed. The acceleration performance at the start of the vehicle is improved while preventing the occurrence of the vehicle, and the improvement of the fuel efficiency and the improvement of the acceleration performance at the start can be achieved.
[0064]
According to the second aspect of the present invention, since the fuel injection amount is increased and corrected by correcting the accelerator operation amount, it is possible to easily adjust the engine output torque with respect to the accelerator operation amount when the vehicle starts.
[0065]
According to the third aspect of the present invention, the fuel injection amount increase correction amount is gradually reduced immediately after the vehicle starts, so that the output torque of the internal combustion engine changes smoothly according to the decrease in the increase correction amount. Thus, it is possible to prevent a step from occurring in the output torque of the internal combustion engine when the increase correction amount is decreased.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an entire engine to which a fuel injection amount control device of an embodiment is applied.
FIG. 2 is a cross-sectional view of a cylinder head showing the shape of intake and exhaust ports in the engine.
FIG. 3 is a block diagram showing an electrical configuration of the fuel injection amount control device.
FIG. 4 is a graph showing a relationship between an accelerator depression amount and a fuel injection amount.
FIG. 5 is a flowchart showing an accelerator depression amount correction procedure.
FIG. 6 is a flowchart showing an accelerator depression amount correction procedure.
FIG. 7 is a map that is referred to when an accelerator correction coefficient is calculated.
FIG. 8 is a time chart showing changes in accelerator depression amount, accelerator correction coefficient, fuel injection amount, and vehicle speed when the vehicle starts.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Engine, 14c ... Crank position sensor, 25 ... Accelerator pedal, 26 ... Accelerator position sensor, 27 ... Transmission, 28a ... Vehicle speed sensor, 29 ... Transmission control computer, 36 ... Vacuum sensor, 40 ... Fuel injection valve, 92 ... Electronics Control unit (ECU).

Claims (3)

It is a stratified combustion combustion system in which fuel is injected during the compression stroke when the engine is operating in the low rotation and low load range, and the intake stroke of the fuel when the engine operation is in the high rotation and high load range. In- cylinder injection type fuel injection amount control device for in-vehicle internal combustion engine, which is a combustion method of homogeneous combustion injected into
Start determination means for determining whether or not the vehicle is starting;
Correction means for increasing the fuel injection amount of the internal combustion engine within a range in which the combustion system is maintained in stratified combustion when it is determined by the start determination means that the vehicle is starting. A fuel injection amount control device for an in-vehicle internal combustion engine. The fuel for an in-vehicle internal combustion engine according to claim 1, wherein the fuel injection amount is set based on an accelerator operation amount, and the correction means corrects the fuel injection amount by correcting the accelerator operation amount. Injection amount control device. 3. The fuel injection amount control device for an on-vehicle internal combustion engine according to claim 1, wherein the correction unit gradually decreases the fuel injection amount increase correction amount when the start determination unit determines that the vehicle is not starting. 4. .

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