JP2017115605A - Fuel injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device capable of starting an engine satisfactorily regardless of atmospheric pressure and suppressing deterioration of exhaust gas. SOLUTION: Based on the detection result of a temperature detection means 41, an increase value setting means 42 for setting an increase value obtained by increasing and correcting the amount of fuel injected from a fuel injection valve 22 at the time of starting the engine 10, and an atmospheric pressure detection. Based on the detection result of the means 43, an increase value correction means 44 for correcting the increase value to a larger value as the atmospheric pressure is lower, and an injection control means 45 for injecting the fuel from the fuel injection valve 22 according to the increase value. When the engine 10 is cold-started, the increase value correction means 44 decreases the increase amount correction amount as the elapsed time after the start of the engine 10 becomes longer. [Selection diagram] Figure 2

Description

  The present invention relates to a fuel injection control device that controls a fuel injection valve provided in an engine (internal combustion engine) to inject a predetermined amount of fuel, and more particularly to a technique for controlling the amount of fuel to be injected when the engine is started.

  In an engine mounted on a vehicle such as an automobile, fuel is injected from a fuel injection valve so as to have a predetermined target air-fuel ratio (theoretical air-fuel ratio) during normal running. A so-called start increase correction is performed in which the amount of fuel injected from the vehicle is increased from that during normal driving.

  In this start increase correction, the startability of the engine is improved by increasing the amount of fuel injected from the fuel injection valve over a predetermined period from the start of the engine. In the start increase correction, for example, the increased fuel amount (increase value) is appropriately corrected so that the fuel amount injected from the fuel injection valve increases as the engine temperature decreases.

  Further, for example, there is a fuel amount (increase value) in the starting increase correction that is increased as the altitude is higher (lower atmospheric pressure). Specifically, there is one that detects the atmospheric pressure, increases the increase value in accordance with the decrease in the atmospheric pressure, and ensures stable operability even at high temperature restart of the internal combustion engine in the highland ( For example, see Patent Document 1).

JP 2004-36541 A

  By the way, at high altitude with low atmospheric pressure, the air-fuel ratio of the engine tends to be lean. The reason is considered as follows. When the atmospheric pressure is low, the exhaust pressure in the cylinder becomes low, so that combustion gas (exhaust gas) is easily discharged from the cylinder. In addition, the amount of blow back of the so-called internal EGR is also reduced. For this reason, when the atmospheric pressure is low, the temperature in the cylinder tends to decrease. Further, it is considered that the temperature in the cylinder is lowered, so that the fuel is hardly vaporized, and the air-fuel ratio of the engine tends to become lean due to this. Further, since the temperature of the air-fuel ratio of the engine is affected as described above, the air-fuel ratio is particularly likely to become lean when the engine (in-cylinder) temperature is low.

  For this reason, when the engine is cold-started at a high altitude with a low atmospheric pressure, as an increase correction for starting, the increase value according to the atmospheric pressure is set in addition to the correction for increasing the increase value according to the engine temperature described above. It is considered that the engine can be started more appropriately by performing the correction to be increased.

  However, when these two corrections are performed together, the air-fuel ratio may be enriched more than necessary. The temperature in the cylinder of the engine gradually rises from the start, and the fuel in the cylinder gradually vaporizes accordingly. For this reason, if the two corrections are simply executed, the air-fuel ratio of the engine is enriched more than necessary during the start-up amount correction, and the exhaust gas may be deteriorated.

  The present invention has been made in view of such circumstances, and provides a fuel injection control device that can start the engine satisfactorily regardless of atmospheric pressure and can also suppress deterioration of exhaust gas. Objective.

  A first aspect of the present invention that solves the above problem is a fuel injection control device that controls a fuel injection valve provided in an internal combustion engine to inject a predetermined amount of fuel, and detects the temperature of the internal combustion engine. And an increase value setting means for setting an increase value obtained by increasing the amount of fuel injected from the fuel injection valve when starting the internal combustion engine based on a detection result of the temperature detection means, and detecting an atmospheric pressure Based on the detection result of the atmospheric pressure detection means, an increase value correction means for correcting the increase value to a larger value as the atmospheric pressure is lower, and from the fuel injection valve according to the increase value Injection amount control means for injecting, and when the internal combustion engine is cold started, the increase value correction means decreases the correction value of the increase value as the elapsed time after the start of the internal combustion engine becomes longer. It is characterized by letting In the fuel injection control apparatus.

  According to a second aspect of the present invention, in the fuel injection control device according to the first aspect, the increase value setting means gradually decreases in a plurality of stages having different gradients from an initial value after the internal combustion engine is started. An increase value is set, and the increase value correction means gradually decreases the correction value of the increase value at the switching point of each stage.

  According to a third aspect of the present invention, in the fuel injection control apparatus according to the second aspect, the increase value setting means includes a first stage in which the gradient is a predetermined primary gradient, and the gradient is greater than the primary gradient. The increase value is set so as to gradually decrease from the initial value in a second stage that is a gentle second-order gradient and a third stage in which the gradient is a third-order gradient that is gentler than the second-order gradient, The increase value correction means, without changing the primary gradient, the secondary gradient and the tertiary gradient, the correction amount at the switching point between the first stage and the second stage of the increase value, The fuel injection control apparatus is characterized in that it is smaller than the correction value of the initial value.

  According to a fourth aspect of the present invention, in the fuel injection control device according to the third aspect, the increase value correction means does not correct a switching point between the second stage and the third stage of the increase value. In the fuel injection control device.

  According to the fuel injection control device of the present invention, the air-fuel ratio immediately after the start of the internal combustion engine (engine) is stabilized to the same value regardless of the atmospheric pressure, that is, whether it is flat or high. be able to. Therefore, the engine can always be started satisfactorily and exhaust gas deterioration (discharge of unburned fuel components) can be suppressed.

It is a figure showing the schematic structure of the engine concerning one embodiment of the present invention. It is a block diagram showing a schematic structure of a fuel injection control device concerning one embodiment of the present invention. It is a figure explaining the change of the increase value at the time of engine starting in a flat ground. It is a figure explaining the change of the increase value (after correction | amendment) at the time of engine starting in a highland. It is a figure explaining the change of the air fuel ratio at the time of engine starting.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
A gasoline engine (hereinafter simply referred to as an engine) 10 shown in FIG. 1 is an intake pipe injection type (Multi Point Injection) gasoline engine (internal combustion engine), and includes a cylinder head 12 and a cylinder block 13. A piston 15 is housed in each cylinder 14 (cylinder) of the cylinder block 13 so as to be reciprocally movable. The piston 15, the cylinder 14, and the cylinder head 12 form a combustion chamber 16. The piston 15 is connected to the crankshaft 18 via a connecting rod 17. The reciprocating motion of the piston 15 is transmitted to the crankshaft 18 via the connecting rod 17.

  An intake port 19 is formed in the cylinder head 12. An intake manifold 20 is connected to the intake port 19. An intake valve 21 is provided in the intake port 19. The combustion chamber 16 and the intake port 19 are communicated and blocked by the intake valve 21. In the intake manifold 20, for example, an electromagnetic fuel injection valve 22 is provided so that fuel can be injected into the intake port 19. Although not shown, the fuel injection valve 22 is connected to a fuel supply device having a fuel tank via a fuel pipe and a fuel pump.

  An exhaust port 23 is further formed in the cylinder head 12. One end of an exhaust manifold 24 is connected to the exhaust port 23, and an exhaust pipe 25 is connected to the other end of the exhaust manifold 24. An exhaust valve 26 is provided in the exhaust port 23. Like the intake valve 21 in the intake port 19, the combustion chamber 16 and the exhaust port 23 are communicated and blocked by the exhaust valve 26.

  A spark plug 27 is attached to the cylinder head 12 corresponding to each cylinder 14. Each spark plug 27 is connected to an ignition coil 28 that outputs a high voltage. A surge tank 29 is provided on the upstream side of the intake manifold 20. A throttle valve 30 that adjusts the intake air amount is provided upstream of the surge tank 29, and a throttle position sensor (TPS) 31 that detects the opening of the throttle valve 30 is also provided. The opening of the throttle valve 30 is adjusted in conjunction with the operation of an accelerator pedal (not shown). An air flow sensor 32 for measuring the intake air amount is interposed upstream of the throttle valve 30.

A three-way catalyst 33 that is an exhaust purification catalyst is interposed in the exhaust pipe 25 connected to the exhaust manifold 24. An O ₂ sensor 34 for detecting the oxygen concentration of the exhaust gas after passing through the catalyst is provided on the downstream side of the three-way catalyst 33, and on the upstream side of the three-way catalyst 33, the air-fuel ratio of the exhaust gas before passing through the catalyst ( A linear air-fuel ratio sensor (LAFS) 35 for detecting the exhaust air-fuel ratio is provided. An O ₂ sensor can be used instead of the LAFS 35.

The ECU (electronic control unit) 36 includes an input / output device, a storage device (ROM, RAM, etc.), a central processing unit (CPU), a timer counter, and the like, and performs overall control of the engine 10. On the input side of the ECU 36, in addition to the TPS 31, air flow sensor 32, O ₂ sensor 34, linear air-fuel ratio sensor (LAFS) 35 described above, a crank angle sensor 37 that detects the crank angle of the engine 10, and the temperature of the cooling water are detected. Various sensors such as a water temperature sensor 38 that detects atmospheric pressure and an atmospheric pressure sensor 39 that detects atmospheric pressure are connected, and detection information from these sensors is input. On the other hand, on the output side of the ECU 36, various output devices such as the fuel injection valve 22, the ignition coil 28, the throttle valve 30 and the like are connected. These various output devices output the fuel injection amount, fuel injection time, ignition timing, and the like calculated by the ECU 36 based on detection information from various sensors.

  The fuel injection control device according to the present invention is configured as a part of the ECU 36 and controls the fuel injection valve 22 so that a predetermined amount of fuel is injected when the engine 10 is started. There is a feature in the control of the fuel amount in the start increase correction at the cold start. Hereinafter, the fuel amount control by the fuel injection control device will be described in detail.

  As shown in FIG. 2, the ECU 36 includes a fuel injection control unit 40 as a fuel injection control device. The fuel injection control unit 40 includes a temperature detection means 41, an increase value setting means 42, an atmospheric pressure detection means 43, an increase value correction means 44, and an injection control means 45.

  The temperature detection means 41 detects the temperature of the engine 10 based on information from the water temperature sensor 38. In the present embodiment, the temperature detection means 41 acquires the temperature of the cooling water detected by the water temperature sensor 38 as the temperature of the engine 10. As will be described later, the temperature detection means 41 detects the temperature of the engine 10 when the engine 10 is started. However, the method for detecting the temperature when the engine 10 is started is not particularly limited. You may make it estimate based on the time from.

  Based on the detection result of the temperature detection means 41, the increase value setting means 42 sets an increase value obtained by increasing the amount of fuel injected from the fuel injection valve 22 when the engine 10 is started (at the time of starting increase correction). . In this embodiment, the increase value setting means 42 sets an increase value corresponding to a flat ground (for example, the atmospheric pressure is about 760 mmHg). Specifically, the increase value setting means 42 sets the increase value in a state where the engine 10 is in the start mode as an initial value, and after releasing the start mode (after starting the engine 10), details will be described later. Set the increase value so that it gradually decreases from the initial value. The start mode is a control mode for starting the engine 10 and is canceled when the rotation speed of the engine 10 reaches a predetermined rotation speed after starting cranking.

  The atmospheric pressure detection means 43 detects the atmospheric pressure based on information from the atmospheric pressure sensor 39, for example. The method for detecting atmospheric pressure by the atmospheric pressure detecting means 43 is not particularly limited.

  The increase value correction unit 44 corrects the increase value set by the increase value setting unit 42 as necessary based on the detection result of the atmospheric pressure detection unit 43. At this time, the increase value correction means 44 corrects the increase value so that the value increases as the atmospheric pressure decreases. In this embodiment, when the atmospheric pressure detected by the atmospheric pressure detection unit 43 is lower than a predetermined threshold (for example, about 600 mmHg), the increase value correction unit 44 determines that the current location is a highland, The increase value corresponding to (for example, the atmospheric pressure is 460 mmHg) is corrected. On the other hand, when the atmospheric pressure detected by the atmospheric pressure detecting means 43 is higher than a predetermined threshold value, it is determined that the current location is a flat ground, and the increase value is not corrected.

  Further, as will be described in detail later, the increase value correction means 44 gradually decreases the correction value of the increase value as the elapsed time after the start of the engine 10 becomes longer when the engine 10 is cold-started. ing.

  When the engine 10 is started, the injection control means 45 appropriately controls the fuel injection valve 22 so that a predetermined fuel amount is injected according to the increase value set by the increase value setting means 42. When the increase value is corrected by the increase value correction means 44, the injection control means 45 appropriately controls the fuel injection valve 22 so that a predetermined fuel amount is injected according to the corrected increase value.

  The control of the fuel amount in the start increase correction at the cold start by the fuel injection control unit 40 will be further described with reference to FIG.

  First, control when the engine 10 is cold-started on a flat ground (a state where the atmospheric pressure is high) will be described. For example, when there is a start request by operating a start switch such as an ignition switch, and the engine 10 shifts to the start mode, the increase value setting means 42 is based on the temperature of the engine 10 (cooling water temperature) as shown in FIG. As shown, the initial value (1 + K0) of the increase value is set. For example, in this embodiment, when the target air-fuel ratio is the stoichiometric air-fuel ratio, the increase value corresponding to the fuel amount to be injected from the fuel injection valve 22 is set to 1.0, and the added value K0 corresponding to the temperature of the engine 10 Is added as the initial value (1 + K0) of the increase value. At this time, the lower the temperature of the engine 10, the larger this added value K0. The relationship between the added value K0 corresponding to the amount of fuel to be increased and the temperature of the engine 10 is preset and stored as a map, for example.

  When the increase value setting means 42 sets the initial value (1 + K0) of the increase value, the increase value correction means 44 sets the initial value (1 + K0) of the increase value as needed based on the detection result of the atmospheric pressure detection means 43. To correct. In the present embodiment, when starting the engine 10 on a flat ground, that is, when the atmospheric pressure detected by the atmospheric pressure detection means 43 is higher than a predetermined threshold, the increase value correction means 44 corrects the increase value. Not performed.

  Then, the injection control means 45 controls the fuel injection valve 22 according to the initial value (1 + K0) of the increase value to inject a predetermined fuel amount. The injection control means 45 holds the initial value (1 + K0) of the increase value until it is determined that the engine 10 has started, that is, until the start mode is canceled. For example, in the example shown in FIG. 3, starting (cranking) of the engine 10 is started at time t1, and when the rotational speed of the engine 10 reaches a predetermined rotational speed at time t2, it is determined that the engine 10 has started and started. The mode is released.

  Further, the increase value setting means 42 sets the increase value so as to gradually decrease from the initial value (1 + K0) after the engine 10 is started, that is, when the start mode is canceled at time t2. The increase value setting means 42 sets the increase value so as to decrease at a plurality of stages with different gradients (decrease rates) from the initial value (1 + K0), for example. In the present embodiment, the increase value setting means 42 includes a first stage in which the slope is a predetermined primary slope, a second stage in which the slope is a secondary slope that is gentler than the primary slope, and a slope that is higher than the secondary slope. In the third stage, which is a gentle third-order gradient, the increase value is set so as to gradually decrease from the initial value (1 + K0).

  Specifically, the increase value setting means 42 is configured to switch between the first stage and the second stage based on the temperature of the engine 10 during the start of the engine 10 (during start mode: time t1-t2), and the second stage. And an increase value serving as a switching point between the third stage and the third stage. Each switching point is set to an increase value at a timing when the air-fuel ratio of the engine 10 becomes a predetermined air-fuel ratio.

  In the present embodiment, first, in the first stage, the increase value is decreased from the initial value (1 + K0) with a primary gradient, and the air-fuel ratio of the engine 10 is a predetermined first air-fuel ratio (for example, A / F is about 10 to 11). The increase value (1 + K12) at the timing of the rich peak) is obtained in advance by a test, and this increase value (1 + K12) is set as a switching point between the first stage and the second stage. Further, in the second stage, the increase value is decreased by the secondary gradient, and the increase value (1 + K23) at which the air-fuel ratio of the engine 10 becomes the second air-fuel ratio (for example, A / F is about 12) that is thinner than the first air-fuel ratio. ) Is obtained in advance by a test, and this increase value (1 + K23) is set as a switching point between the second stage and the third stage. In the present embodiment, since the primary gradient, the secondary gradient, and the cubic gradient are determined in advance, the increase value after the engine 10 is started (after the start mode is released) is set by setting these switching points. Will be. Of course, these gradients may be set based on the temperature of the engine 10 during the start mode.

  Incidentally, the first air-fuel ratio corresponds to the air-fuel ratio in the middle of the engine 10 shifting to the so-called first idle, and the second air-fuel ratio corresponds to the air-fuel ratio after the engine 10 shifts to the first idle.

  Then, after the engine 10 is started, the injection control means 45 injects a predetermined amount of fuel from the fuel injection valve 22 while gradually decreasing the injection amount in accordance with the increase value set in this way. For example, in the example shown in FIG. 3, when the start mode is canceled at time t <b> 2, the injection control means 45 injects fuel from the fuel injection valve 22 according to the increase value that decreases with the primary gradient. Then, at time t3, when the increase value decreases to a value (1 + K12) which becomes a switching point between the first stage (primary gradient) and the second stage (secondary gradient), the injection control means 45 thereafter performs the secondary control. Fuel is injected from the fuel injection valve 22 in accordance with an increase value that decreases with a gradient. Furthermore, when the increase value decreases to a value (1 + K23) that becomes a switching point between the second stage (secondary gradient) and the third stage (third order gradient) at time t4, the injection control means 45 thereafter causes the third order gradient. The fuel is injected from the fuel injection valve 22 in accordance with the increase value that decreases in step. Then, when the increase value is reduced to 1.0 at time t5, that is, when the air-fuel ratio of the engine 10 is stabilized near the target air-fuel ratio (for example, the theoretical air-fuel ratio), the start increase correction is completed, and the injection control means 45 The fuel injection valve 22 is appropriately controlled by normal feedback control.

  Next, control when the engine 10 is cold-started at high altitude (a state where the atmospheric pressure is low) will be described.

First, similarly to when the engine 10 is started on a flat ground, when the engine 10 is requested to start, the increase value setting means 42 sets the initial value (1 + K0) of the increase value based on the temperature of the engine 10. Thereafter, when the atmospheric pressure detected by the atmospheric pressure detection unit 43 is lower than a predetermined threshold, the increase value correction unit 44 determines that the current location is a highland and further corrects the initial value (1 + K0). In the present embodiment, the atmospheric pressure correction coefficient K _BP corresponding to the high altitude (for example, the atmospheric pressure is 460 mmHg) is read from the map or the like, and the atmospheric pressure correction coefficient K _BP is multiplied by the initial value (1 + K0) of the increase value to obtain the high altitude The initial value ((1 + K0) × K _BP ) at the start of the engine 10 in FIG.

The injection control means 45 injects fuel from the fuel injection valve 22 in accordance with the initial value ((1 + K0) × K _BP ) of the increase value corrected in this way. As in the case of the flat ground, for example, as shown in FIG. 4, the injection control means 45 starts the initial value ((() until the start of the engine 10 is started at time t1 and the start mode is canceled at time t2 ′. 1 + K0) × _{K BP)} for holding the. Further, the increase value setting means 42 sets an increase value after the engine 10 is started (after the start mode is released) during the start mode.

  Further, the increase value correction means 44 appropriately corrects the set increase value after the engine 10 is started according to the atmospheric pressure. Here, the increase value correcting means 44 appropriately corrects the increase value at the switching point in each stage without changing the primary gradient, quadratic gradient, and cubic gradient of the increase value determined in advance. Further, at this time, the increase value correction means 44 gradually decreases the correction value of the increase value that becomes the switching point of each stage.

  Specifically, the increase value setting means 42, as described above, increases the increase value (1 + K12) serving as a switching point between the first stage (primary gradient) and the second stage (secondary gradient), and the second stage ( When the increase value (1 + K23) serving as a switching point between the second-order gradient and the third stage (third-order gradient) is obtained by calculation, the increase value correcting means 44 determines the switching point between the first stage and the second stage. The increase value (1 + K12) and the increase value (1 + K23) serving as a switching point between the second stage and the third stage are corrected as necessary.

In this embodiment, boost value correcting means 44, the boost value of the switching point between the first and second stages (1 + K12), multiplied by the atmospheric pressure correction coefficient K _BP was used to correct the initial value (1 + K0) By doing so, it is set as the increase value ((1 + K12) × K _BP ) corresponding to the highland. Since the increase value (1 + K12) serving as the switching point is a value smaller than the initial value (1 + K0), when the atmospheric pressure correction coefficient _KBP is multiplied, the correction value Ka of the increase value (1 + K12) is the initial value (1 + K0). Is smaller than the correction amount Kb. Further, in the present embodiment, correction based on atmospheric pressure is not performed for the increase value (1 + K23) serving as a switching point between the second stage and the third stage. As a result, the correction amount (0 in this embodiment) of the increase value (1 + K23) serving as the switching point between the second stage and the third stage is the increase value (1 + K12) serving as the switching point between the first stage and the second stage. Is smaller than the correction amount Ka.

  In this way, the increase value correction means 44 gradually decreases the correction value of the increase value as the elapsed time after the start of the engine 10 becomes longer by gradually decreasing the correction amount at each switching point. Yes.

Then, after the engine 10 is started, the injection control means 45 injects a predetermined amount of fuel from the fuel injection valve 22 while gradually decreasing the injection amount according to the increased value corrected in this way. For example, in the example shown in FIG. 4, when the start mode is canceled at time t <b> 2 ′, the injection control unit 45 injects fuel from the fuel injection valve 22 in accordance with the corrected increase value that decreases with the primary gradient. Then, at time t3 ′, when the increase value decreases to a value (1 + K12) × K _BP ) that becomes the switching point between the first stage and the second stage, the injection control means 45 thereafter decreases with a secondary gradient. Fuel is injected from the fuel injection valve 22 in accordance with the corrected increase value. Further, when the increase value decreases to a value (1 + K23) that becomes the switching point between the second stage and the third stage at time t4 ′, the injection control means 45 thereafter increases the corrected increase value that decreases with the cubic gradient. Accordingly, fuel is injected from the fuel injection valve 22. Then, at the time t5 ′, when the corrected increase value decreases to 1.0, the start increase correction is completed, and the injection control means 45 appropriately controls the fuel injection valve 22 by normal feedback control.

  As described above, according to the fuel injection control device of the present invention, when the engine 10 is cold-started, the change in the air-fuel ratio of the engine 10 can be stabilized regardless of whether the engine 10 is flat or high.

  For example, as shown in FIG. 5, the air-fuel ratio (Comparative Example 1) when the fuel increase correction according to the atmospheric pressure is not performed when the engine is cold started at high altitude is the cold start of the engine on the flat ground. The air-fuel ratio at the time of the departure is greatly deviated to the lean side. As described above, when the air-fuel ratio varies between the flat ground and the highland, the combustion of the engine becomes unstable, which may cause misfire and engine stall. Further, when the engine is cold started at high altitude, the amount of increase is corrected according to the atmospheric pressure. However, if the amount of increase correction is constant regardless of the elapsed time after the start of the engine (Comparative Example 2), the engine after the start If the in-cylinder fuel is easily vaporized as the in-cylinder temperature rises, the air-fuel ratio becomes too rich compared to the air-fuel ratio when the engine is cold-started on a flat ground, which may cause deterioration of exhaust gas. .

  On the other hand, when the engine is cold-started at high altitude, the air-fuel ratio of the embodiment in which the increase correction according to the atmospheric pressure is performed together with the increase correction according to the engine temperature is the air-fuel ratio when the engine is cold-started on the flat ground It becomes the same value as. In other words, according to the present invention, the correction amount of the increase value is decreased as the elapsed time after engine startup becomes longer. Therefore, when the engine is cold-started regardless of high altitude or flat ground (regardless of atmospheric pressure). The change in the air-fuel ratio can be stabilized. Therefore, according to the fuel injection control device of the present invention, the engine can always be started satisfactorily, even at the cold start of the engine, regardless of the high altitude and the flat ground, and the deterioration of exhaust gas can be suppressed. be able to.

  Further, in the above-described embodiment, the increase value correcting unit 44 does not change the primary gradient, the secondary gradient, and the tertiary gradient, and only the increase value that serves as a switching point between the first step and the second step of the increase value. As the elapsed time after starting the engine becomes longer, the correction amount of the increase value is decreased. Thereby, the control load at the time of starting of the engine 10 can be reduced.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment.

  For example, in the above-described embodiment, the example in which the increase value corresponding to the predetermined atmospheric pressure is corrected when the atmospheric pressure is less than the predetermined threshold has been described. For example, according to the detected atmospheric pressure The correction amount of the increase value may be changed in multiple stages.

  Further, for example, in the above-described embodiment, the gradient of the increase value and the switching point are set regardless of the shift position. For example, in the case where the shift position is the D range and the case where the shift position is the N range, You may make it set a gradient and a switching point, respectively. Thus, even when the shift position is changed during engine startup, the amount of increase can be appropriately changed.

In the embodiment described above, when correcting the increase value of the switching point between the first and second stages (1 + K12), to multiply the pressure correction coefficient K _BP was used to correct the initial value (1 + K0) I made it. Thereby, the control load at the time of starting the engine can be reduced. Of course, this atmospheric pressure correction coefficient may be set individually for each switching point.

  Further, for example, in the above-described embodiment, the present invention has been described by exemplifying an intake pipe injection type gasoline engine. However, of course, the present invention includes other types such as a cylinder injection type gasoline engine and a diesel engine. It goes without saying that it can also be used for types of engines.

10 Engine (Internal combustion engine)
12 Cylinder Head 13 Cylinder Block 14 Cylinder 15 Piston 16 Combustion Chamber 17 Connecting Rod 18 Crankshaft 19 Intake Port 20 Intake Manifold 21 Intake Valve 22 Fuel Injection Valve 23 Exhaust Port 24 Exhaust Manifold 25 Exhaust Pipe 26 Exhaust Valve 27 Spark Plug 28 Ignition Coil 29 Surge tank 30 Throttle valve 32 Air flow sensor 33 Three-way catalyst 34 O ₂ sensor 35 LAFS
36 ECU
37 Crank angle sensor 38 Water temperature sensor 39 Atmospheric pressure sensor 40 Fuel injection control unit 41 Temperature detection means 42 Increase value setting means 43 Atmospheric pressure detection means 44 Increase value correction means 45 Injection control means

Claims (4)

A fuel injection control device for controlling a fuel injection valve provided in an internal combustion engine to inject a predetermined amount of fuel,
Temperature detecting means for detecting the temperature of the internal combustion engine;
An increase value setting means for setting an increase value obtained by increasing the amount of fuel injected from the fuel injection valve when starting the internal combustion engine based on the detection result of the temperature detection means;
Atmospheric pressure detection means for detecting atmospheric pressure;
Based on the detection result of the atmospheric pressure detection means, an increase value correction means for correcting the increase value to a larger value as the atmospheric pressure is lower;
Injection control means for injecting from the fuel injection valve according to the increase value,
When the internal combustion engine is cold-started, the increase value correction means decreases the correction value of the increase value as the elapsed time after the start of the internal combustion engine becomes longer. The fuel injection control device according to claim 1,
The increase value setting means sets the increase value so as to gradually decrease at a plurality of stages having different gradients from the initial value after the internal combustion engine is started,
The fuel injection control apparatus characterized in that the increase value correction means gradually decreases the correction value of the increase value at the switching point of each stage. The fuel injection control device according to claim 2,
The increase value setting means includes a first stage in which the gradient is a predetermined primary gradient, a second stage in which the gradient is a secondary gradient that is gentler than the primary gradient, and the gradient is greater than the secondary gradient. In the third stage, which is a gentle third-order gradient, the increase value is set so as to gradually decrease from the initial value,
The increase value correction means, without changing the primary gradient, the secondary gradient and the cubic gradient, the correction amount at the switching point between the first stage and the second stage of the increase value, A fuel injection control device characterized in that it is smaller than the correction amount of the initial value. The fuel injection control device according to claim 3, wherein
The fuel injection control apparatus according to claim 1, wherein the increase value correction means does not correct a switching point between the second stage and the third stage of the increase value.

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