JP2007218106A - Fuel injection control device for cylinder injection spark ignition type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device for a cylinder injection spark ignition type internal combustion engine materializing shortening of start time and stable start at a time of cold start with a simple structure. <P>SOLUTION: This device is provided with a main fuel injection control means S20 injecting fuel of predetermined quantity from a fuel injection valve into a combustion chamber of each cylinder until reaching perfect explosion when the internal combustion engine is in a cold condition (S12) and it is detected that pressure correlation value of fuel reaches predetermined equivalent value (predetermined stroke number X2), and a pilot fuel injection control means S18 controlling valve open period of the fuel injection valve short to keep fuel injection quantity injected from the fuel injection valve into the combustion chamber of each cylinder in each compression stroke according to pressure of fuel less than the predetermined quantity until pressure correlation value of fuel reaches predetermined equivalent value when the internal combustion engine is in the cold condition (S12) and it is detected that pressure correlation value of fuel does not reach the predetermined equivalent value (predetermined stroke number X2). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection control device for a cylinder injection type spark ignition type internal combustion engine, and more particularly to a fuel injection control technique at the time of cold start of a cylinder injection type spark ignition type internal combustion engine.

Generally, in a gasoline engine that can inject fuel during the intake stroke, at the time of cold start, in order to ensure ignition, fuel is supplied more than usual at the start of cranking, and gradually becomes a normal fuel amount. The fuel is controlled so as to shift.
However, when the amount of fuel is increased at the time of cold start in this way, there is a problem that since the engine is cold, the fuel is difficult to vaporize and a large amount of unburned fuel is generated, leading to deterioration of exhaust gas and fuel consumption.

Therefore, in a cylinder injection type gasoline engine, a fuel injection control technique has been developed in which fuel injection is performed in a compression stroke at the time of cold start (see Patent Document 1).
By performing fuel injection in the compression stroke in this way, fuel can be collected in the vicinity of the spark plug and burned efficiently even during cold start, and the supplied fuel is kept to the minimum necessary. Thus, it is possible to suppress the generation of unburned fuel and prevent deterioration of exhaust gas and fuel consumption.
JP 2001-317390 A

By the way, when fuel injection is performed in a compression stroke in an in-cylinder injection type gasoline engine, it is necessary to inject fuel into a combustion chamber that has been compressed to high pressure. Normally, the fuel is boosted to a high pressure by a high-pressure pump that is operated by the rotation of the engine.
However, in the initial stage of the start, since the engine has started to operate, the engine rotation is slow, and the high-pressure pump cannot function sufficiently for a while, as described in Patent Document 1 above. If the fuel supply is started after waiting for the fuel to become high pressure, there is a problem that the start of fuel supply is delayed and the startability is poor.

On the other hand, if the fuel supply is started without waiting for the fuel to become high pressure, and the same amount of fuel is injected as at the time of high pressure, the fuel pressure (hereinafter referred to as the fuel pressure) is originally lowered each time the fuel is injected. There is a problem that the fuel pressure does not rise easily regardless of the operation of the high pressure pump, the fuel cannot be supplied sufficiently, the engine start is not stable, and the startability is poor.
For this reason, it is conceivable to provide a high-pressure pump with a higher output or a larger size, or to provide a motor for operating the high-pressure pump separately. This is not preferable because it is disadvantageous in terms of cost and space.

  The present invention has been made on the basis of the above-described circumstances, and the object of the present invention is to provide an in-cylinder injection type spark ignition that has a simple configuration and shortens the starting time and realizes a stable starting at the cold start. An object of the present invention is to provide a fuel injection control device for an internal combustion engine.

  In order to achieve the above object, a fuel injection control device for a cylinder injection type spark ignition type internal combustion engine according to claim 1 provides a cylinder injection type spark in which each cylinder has a fuel injection valve for directly injecting fuel into a combustion chamber. A fuel injection control device for an ignition type internal combustion engine, comprising: a high pressure pump that pressurizes fuel by operating the internal combustion engine and supplies high pressure fuel to the fuel injection valve; and detects that the internal combustion engine is in a cold state A cold detection means for detecting the pressure of the fuel pressurized by the high pressure pump or a pressure correlation value, and the internal combustion engine is cooled by the cold detection means when the internal combustion engine is started. When it is detected that the fuel pressure is greater than a predetermined pressure or the pressure correlation value has reached a value corresponding to the predetermined pressure, the fuel pressure detection means detects the fuel from the fuel injection valve to each cylinder until a complete explosion occurs. In the combustion chamber A main fuel injection control means for controlling a valve opening period of the fuel injection valve so as to inject a predetermined amount of fuel; and when the internal combustion engine is started, the cold detection means detects that the internal combustion engine is cold When the fuel pressure detecting means detects that the fuel pressure is smaller than the predetermined pressure or the pressure correlation value does not reach the predetermined pressure equivalent value, or until the fuel pressure exceeds the predetermined pressure or the pressure correlation The fuel injection is performed so that the fuel injection amount injected from the fuel injection valve into the combustion chamber of each cylinder in the compression stroke is smaller than the predetermined amount according to the pressure of the fuel until the value reaches the predetermined pressure equivalent value. And a preceding fuel injection control means for controlling the valve opening period to be short.

  In a fuel injection control device for a cylinder injection type spark ignition type internal combustion engine according to claim 2, in claim 1, the pressure correlation value is a number of strokes of the internal combustion engine integrated after the start of the internal combustion engine. The fuel pressure detecting means is a stroke number detecting means for detecting the number of strokes of the internal combustion engine, and the predetermined pressure equivalent value is integrated until the fuel pressure reaches the predetermined pressure after the start of the internal combustion engine. The predetermined number of strokes is predicted.

  According to a third aspect of the present invention, there is provided a fuel injection control device for an in-cylinder spark ignition type internal combustion engine. In the first or second aspect of the present invention, the preceding fuel injection control means continuously or intermittently supplies fuel within a range smaller than the predetermined amount. It is characterized by increasing.

  According to the fuel injection control device for a cylinder injection type spark ignition type internal combustion engine according to claim 1, when the internal combustion engine has a high pressure pump that pressurizes the fuel and supplies high pressure fuel to the fuel injection valve by the operation of the internal combustion engine, Prior fuel injection for controlling the opening period of the fuel injection valve to be short so that a smaller amount of fuel than the predetermined amount in the main fuel injection control means is injected from the fuel injection valve to the combustion chamber of each cylinder during the compression stroke when the engine is started Since the control means is provided, when the fuel supply is started in the compression stroke, if the fuel pressure has not yet sufficiently increased and is smaller than the predetermined pressure, an amount of fuel smaller than the predetermined amount is injected in advance. Therefore, it is possible to prevent the fuel pressure from decreasing and to sufficiently supply the fuel to stabilize the start of the internal combustion engine, and to start the fuel supply without waiting for the fuel to become high pressure. It is possible to shorten the startup time by preventing the timing delay of the start of the supply.

Thereby, it is possible to improve the startability at the time of cold start with a simple configuration without increasing costs.
According to the fuel injection control device for the in-cylinder spark ignition internal combustion engine according to claim 2, after the start of the internal combustion engine, the number of strokes of the internal combustion engine, which is a pressure correlation value, becomes a predetermined number of strokes corresponding to a predetermined pressure. Until this time, the amount of fuel smaller than the predetermined amount is injected in advance from the fuel injection valve into the combustion chamber of each cylinder by the preceding fuel injection control means, for example, when it is difficult to directly detect the fuel pressure Even so, it is possible to easily improve the startability during the cold start based on the number of strokes of the internal combustion engine.

  According to the fuel injection control device for a cylinder injection type spark ignition internal combustion engine according to claim 3, the fuel is continuously or intermittently increased in accordance with the increase in the fuel pressure in the preceding fuel injection control means, thereby It is possible to further shorten the start time while stabilizing the start, and further improve the startability at the cold start.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the first embodiment will be described.
Referring to FIG. 1, a longitudinal sectional view of a cylinder injection type spark ignition type internal combustion engine mounted on a vehicle, that is, a cylinder injection gasoline engine, and a schematic configuration diagram of a fuel injection control device according to the first embodiment of the present invention are shown. A configuration of a fuel injection control device for an in-cylinder injection type spark ignition type internal combustion engine according to the present invention will be described below with reference to FIG.

Reference numeral 1 denotes an in-cylinder injection gasoline engine for automobiles (hereinafter simply referred to as an engine). The engine 1 is designed such that the combustion chamber 5 and the intake device can be injected into the cylinder.
Specifically, the engine 1 is operated in the intake stroke injection mode by switching the fuel injection mode (operation mode), that is, the fuel injection in the intake stroke in which the homogeneous mixture combustion is performed, or the operation in the compression stroke injection mode. That is, this is an in-cylinder spark ignition type in-line four-cylinder gasoline engine capable of performing fuel injection in a compression stroke in which stratified combustion is performed. In addition to the operation at the rich air-fuel ratio, the operation at the lean air-fuel ratio is possible. In the compression stroke injection mode, the operation at the lean air-fuel ratio and the operation at the super-lean air-fuel ratio are possible.

  A cylinder head 2 of the engine 1 is provided with a spark plug 3 and an electromagnetic high pressure injector (fuel injection valve) 4 obliquely attached to the cylinder 6 for each cylinder. Direct injection is possible. Further, on the top surface of the piston 7 that slides and reciprocates in the cylinder 6, for example, a hemispherical depression so that the fuel spray injected from the injector 4 in the compression stroke reaches the spark plug 3 near the top dead center, That is, the cavity 8 is formed.

As the valve operating mechanism, for example, a DOHC (double overhead cam) type four-valve mechanism is adopted, and an intake side camshaft 11 and an intake side camshaft 11 are respectively disposed above the cylinder head 2 so as to drive the intake and exhaust valves 9 and 10. An exhaust camshaft 12 is rotatably supported.
An intake port 13 is formed in the cylinder head 2 so as to pass between the camshafts 11 and 12 so as to extend in a substantially upright direction, and the intake air flow passing through the intake port 13 is generated in the combustion chamber 5. It is possible to generate a reverse tumble flow in the opposite direction to normal. About the exhaust port 14, it is formed in the substantially horizontal direction like a normal engine.

  Reference numeral 16 in the drawing is a water temperature sensor for detecting the cooling water temperature Tw (cool state detecting means). Reference numeral 17 denotes a crank angle sensor that outputs a crank angle signal. The number of strokes executed by the engine 1 and the engine rotational speed Ne can be detected from the crank angle information. A cylinder discriminating sensor (not shown) that outputs a cylinder discriminating signal is attached to the camshaft 11 that rotates at half the number of revolutions of the crankshaft, so that it is possible to discriminate which cylinder the crank angle signal belongs to. is there.

An intake pipe is connected to the intake port 13 via an intake manifold 21. The intake pipe is provided with an air cleaner, a throttle valve, a throttle position sensor (TPS), an air flow sensor, and the like (both not shown). .
An exhaust pipe is connected to the exhaust port 14 via an exhaust manifold 41. The exhaust pipe is provided with a three-way catalyst, a muffler, and the like (both not shown).

  Reference numeral 50 in the figure denotes a fuel supply unit for supplying high-pressure fuel to the injector 4, and the fuel supply unit 50 is connected to the injector 4 through a pipe line and is connected to a fuel tank 52. ing. Specifically, a high-pressure fuel pump (high-pressure pump) 54 is interposed in the fuel supply unit 50, and the high-pressure fuel pump 54 is connected to the end of the camshaft 12 so as to be capable of synchronous rotation. Therefore, when the engine 1 is in operation, the high-pressure fuel pump 54 can supply a fuel with a high fuel pressure (for example, 5 MPa) to the injector 4, so that the fuel can be supplied from the injector 4 even in a compression stroke in which the inside of the cylinder becomes a high pressure. It can be injected well into the cylinder. Although not shown, the fuel supply unit 50 is provided with a pressure regulating valve for regulating the fuel pressure of the fuel discharged from the high-pressure fuel pump 54 to a desired pressure.

An electronic control unit (ECU) 70 is installed in the passenger compartment. The ECU 70 includes an input / output device (not shown), a storage device (ROM, RAM, etc.) used for storing control programs, control maps, and the like. A processing device (CPU), a timer counter, and the like are provided, and the ECU 70 performs overall control of the engine 1.
Various sensors such as the water temperature sensor 16 and the crank angle sensor 17 and the ignition switch 72 are electrically connected to the input side of the ECU 70, while the injector 4, the fuel supply unit 50, Various drive devices such as a cell motor 74 are connected, and a fuel injection amount, a fuel injection timing, an ignition timing, and the like calculated based on detection information from various sensors are output to the various drive devices. Thereby, for example, the air-fuel ratio is controlled to an appropriate target air-fuel ratio, an appropriate amount of fuel is injected from the injector 4 at an appropriate timing, and spark ignition is performed at an appropriate timing by the spark plug 3.

In particular, in the fuel injection control device according to the present invention, when the engine 1 is cold-started, the engine 1 is operated with the fuel injection mode (operation mode) as the compression stroke injection mode. Such start control will be described.
Referring to FIG. 2, the control routine of the start control according to the first embodiment of the present invention executed by the ECU 70 is shown in a flowchart, and will be described below along the flowchart.

When the ignition switch 72 is started and the start control is started, first, in step S10, the ignition is turned on and the cranking of the engine 1 is started by the cell motor 74, whereby the start of the engine 1 is started.
In step S12, it is determined whether or not the engine 1 is in a cold state (cold state). Specifically, the determination is made based on the cooling water temperature information Tw from the water temperature sensor 16. If the determination result is false (No) and it is determined that the coolant temperature Tw is equal to or higher than the predetermined temperature and the engine 1 is in the warm-up state, the process proceeds to step S22.

In step S22, normal start control in the warm-up state is performed. Specifically, for example, the fuel injection mode is switched to the intake stroke injection mode, and fuel injection is performed by increasing the fuel amount from the amount during normal operation other than at the time of starting to improve the startability.
On the other hand, if the determination result in step S12 is true (Yes) and it is determined that the coolant temperature Tw is lower than the predetermined temperature and the engine 1 is in the cold state, the process proceeds to step S14.

  In step S14, it is determined whether or not the number of strokes executed by the engine 1 since the cranking of the engine 1 is started, that is, whether the number of strokes after starting the engine 1 (pressure correlation value) is equal to or greater than the lower limit stroke number X1. To do. Here, the number of strokes after the start of the engine 1 is accumulated by the timer counter of the ECU 70 (fuel pressure detecting means). The lower limit stroke number X1 is the fuel pressure after cranking of the engine 1 is started. This is the number of strokes of the engine 1 that is predicted to be accumulated until the minimum pressure at which fuel injection can be started, that is, the lower limit pressure P1. Specifically, when cranking of the engine 1 is started, the high-pressure fuel pump 54 is operated, whereby the fuel is gradually pressurized. Since the amount of pressure that can be pressurized is a value inherent to the high-pressure fuel pump 54, the lower limit stroke number X1 is set in advance by experiments or the like to the number of strokes accumulated until the pressure amount reaches the lower limit pressure P1. (For example, 5 strokes after starting).

If the determination result in step S14 is false (No), and the number of strokes after starting the engine 1 has not reached the lower limit stroke number X1, it waits for the lower limit stroke number X1 to be reached. On the other hand, if the determination result is true (Yes) and it is determined that the number of strokes after starting the engine 1 has reached the lower limit stroke number X1, the process proceeds to step S16.
In step S16, it is determined whether or not the number of strokes (pressure correlation value) after the start of the engine 1 is equal to or greater than a predetermined stroke number X2 (predetermined pressure equivalent value). Here, the predetermined number of strokes X2 is the number of strokes of the engine 1 that is predicted to be accumulated until the fuel pressure reaches the normal high pressure P2 after the cranking of the engine 1 is started. Specifically, the predetermined number of strokes X2 is also set in advance to the number of strokes accumulated until the pressure amount reaches the normal high pressure P2 in the same manner as the lower limit number of strokes X1 (for example, after the lower limit number of strokes X1). 4-8 strokes).

If the determination result in step S16 is false (No) and the number of strokes after starting the engine 1 has not yet reached the predetermined stroke number X2, the process proceeds to step S18.
In step S18, the fuel injection mode is switched to the compression stroke injection mode, and a minimum amount of fuel necessary for detonating the fuel in the combustion chamber 5 is injected from the injector 4 to each cylinder (preceding fuel injection control means). More specifically, an amount of fuel (pulse width T1) (T2> T1) smaller than the normal starting amount (pulse width T2, predetermined amount) in the compression stroke injection mode described later is injected.

  In this manner, when fuel injection is started with a small amount of fuel under the compression stroke injection mode in a situation where the fuel pressure is low such that the number of strokes after the start of the engine 1 has not yet reached the predetermined stroke number X2, Due to the characteristics of combustion, combustion can be started earlier than when fuel injection is started after waiting for the fuel pressure to reach the normal high pressure P2, and it is possible to give the operator a sense of safety that the engine has started. Further, since the fuel pressure does not decrease so much by fuel injection, the fuel pressure can be quickly and stably increased to the normal high pressure P2 while performing fuel injection.

On the other hand, if the determination result in step S16 is true (Yes) and it is determined that the number of strokes after starting the engine 1 has reached the predetermined stroke number X2, the process proceeds to step S20.
In step S20, while maintaining the fuel injection mode in the compression stroke injection mode, a normal starting amount (pulse width T2, predetermined amount) of fuel corresponding to the engine speed Ne in the compression stroke injection mode is supplied from the injector 4. Injection into each cylinder (main fuel injection control means). In other words, if the number of strokes reaches the predetermined number of strokes X2, the fuel pressure has reached the normal high pressure P2, and it can be determined that the fuel pressure does not drop greatly even if the amount of fuel at the normal starting time is injected. After it is determined that the number of strokes after the start of the engine 1 has reached the predetermined stroke number X2, fuel supply at the start according to the engine rotational speed Ne in the compression stroke injection mode is started as usual.

In this case, since the combustion is already performed in the engine 1 by supplying a small amount of fuel, the fuel atomization is favorably promoted when the fuel supply at the normal starting time is continued, and the combustion is performed. Will progress quickly and reach a complete explosion. As a result, the engine speed Ne can be rapidly increased to the idle speed Ni.
After the combustion reaches a complete explosion, the starting operation of the ignition switch 72 is terminated. Thus, the start control is finished.

  As described above, according to the start control according to the present invention, during the cold start, the compression stroke injection is performed in a low fuel pressure state where the number of strokes after the start of the engine 1 has not yet reached the predetermined stroke number X2. A minimum amount of fuel is injected in advance in the mode, and after that, when the number of strokes reaches the predetermined number of strokes X2 and the fuel pressure rises to the normal high pressure P2, the compression stroke injection mode is maintained and the normal starting time is maintained. The amount of fuel is injected so that even during cold start, combustion can be started easily and early, and the fuel pressure can be increased stably and quickly without a decrease. be able to.

  That is, referring to FIG. 3, the relationship among the injector drive signal, fuel pressure, and engine rotational speed Ne of each cylinder (# 1 to # 4) when the start control according to the present invention is implemented is shown in a time chart. However, as shown in the figure, when the fuel pressure is low such that the number of strokes after starting the engine 1 exceeds the lower limit stroke number X1 and has not yet reached the predetermined stroke number X2, a small amount (pulse width) T1) fuel is injected, and after that, when the number of strokes reaches the predetermined number of strokes X2 and the fuel pressure rises to the normal high pressure P2, a normal start-up amount (pulse width T2) of fuel is injected. Even at the time of starting, combustion can be started at an early stage and the fuel pressure can be increased stably and promptly without decreasing, and the engine speed Ne can be increased smoothly.

  That is, referring to FIG. 4, the conventional case where fuel injection is started after the fuel pressure becomes high (solid line) and the conventional case where fuel injection is started with the fuel amount at the normal start before the fuel pressure becomes high. In the case of (dotted line), the relationship among the injector drive signal, fuel pressure, and engine speed Ne of each cylinder (# 1 to # 4) is compared and shown in a time chart. In the conventional case of FIG. The start timing of fuel injection is delayed (solid line), or the fuel pressure decreases and the engine rotational speed Ne does not increase easily (broken line). As shown in FIG. By implementing this, it is possible to suitably prevent such a delay in the start of fuel injection and a decrease in fuel pressure.

As a result, the start time can be shortened and a stable start can be realized with a simple configuration, and the startability at the cold start can be improved.
Also, at the time of cold start, even if more fuel is injected from the beginning, atomization is not promoted and a lot of surplus fuel is generated that does not contribute to combustion. By doing so, generation | occurrence | production of excess fuel can be prevented as much as possible, and deterioration of fuel consumption can also be suppressed.

For the same reason, it is not necessary to make the high-pressure fuel pump 54 have a higher output or a larger size than necessary, and it is possible to reduce the output or size of the high-pressure fuel pump 54 and to suppress an increase in cost and space. .
Next, a second embodiment will be described.
The second embodiment differs from the first embodiment in that the fuel injection control is performed by directly looking at the fuel pressure, while the fuel injection control is performed by the number of strokes after the start of the engine 1 in the second embodiment. Hereinafter, only the parts different from the first embodiment will be described.

Specifically, in the second embodiment, the high-pressure fuel pump 54 is configured to include a pressure sensor (fuel pressure detecting means) that detects a fuel pressure (not shown).
Referring to FIG. 5, the control routine of the start control according to the second embodiment of the present invention is shown in a flowchart, and will be described along the flowchart. In addition, description about a common part with the said FIG. 2 is abbreviate | omitted suitably here.

If the determination result in step S12 is true (Yes) through step S10 and it is determined that the engine 1 is in the cold state, the process proceeds to step S14 ′.
In step S14 ′, it is determined based on information from the pressure sensor whether or not the fuel pressure is equal to or higher than the minimum pressure at which fuel injection can be started directly, that is, the lower limit pressure P1. If the determination result is false (No) and the fuel pressure does not reach the lower limit pressure P1, the process waits until the lower limit pressure P1 is reached. On the other hand, if the determination result is true (Yes) and it is determined that the fuel pressure has reached the lower limit pressure P1, the process proceeds to step S16 ′.

In step S16 ′, it is determined whether or not the fuel pressure is equal to or higher than the normal high pressure P2 based on the information from the pressure sensor.
If the determination result in step S16 ′ is false (No) and the fuel pressure has not reached the normal high pressure P2, the process proceeds to step S18, and the fuel injection mode is switched to the compression stroke injection mode in the same manner as described above. Then, a minimum amount of fuel (pulse width T1) necessary for detonating the fuel is injected from the injector 4 to each cylinder (preceding fuel injection control means).

  On the other hand, if the determination result in step S16 ′ is true (Yes) and it is determined that the fuel pressure is equal to or higher than the normal high pressure P2, the process proceeds to step S20, and the compression is performed while the fuel injection mode is maintained in the compression stroke injection mode. A normal starting amount (pulse width T2, predetermined amount) of fuel corresponding to the engine speed Ne in the stroke injection mode is injected from the injector 4 to each cylinder (main fuel injection control means).

  As described above, if it is possible to detect the fuel pressure with high reliability, the start control may be performed by directly detecting the fuel pressure instead of indirectly, and as described above, at the time of the cold start. Even in such a case, combustion can be started at an early stage, and the fuel pressure can be stably and promptly increased without a decrease. The simple configuration reduces the start time and realizes a stable start. The startability at the start can be improved.

Further, by injecting a minimum amount of fuel in advance, it is possible to prevent the generation of surplus fuel and suppress deterioration of fuel consumption, and to reduce the output or size of the high-pressure fuel pump 54. This can reduce the cost and space.
This is the end of the description of the embodiment. However, the embodiment of the present invention is not limited to the above embodiment.

  For example, in the above-described embodiment, the fuel to be injected in advance is fixed to a minimum amount (pulse width T1) necessary for initiation, but, for example, the fuel injection amount is changed to a normal start amount (pulse It may be increased (variable) continuously or intermittently toward the width T2). In this way, the start time can be further shortened, and the startability at the cold start can be further improved.

  Moreover, in the said embodiment, the case where fuel injection control is performed by the number of strokes after the start of the engine 1 (first embodiment) is divided from the case where fuel injection control is performed by looking directly at the fuel pressure (second embodiment). However, the fuel injection control may be performed while monitoring both the number of strokes after starting the engine 1 and the fuel pressure.

1 is a longitudinal sectional view of a cylinder injection type spark ignition type internal combustion engine mounted on a vehicle and a schematic configuration diagram of a fuel injection control device according to a first embodiment of the present invention. It is a flowchart which shows the control routine of the starting control which concerns on 1st Example of this invention. It is a time chart which shows the relationship between the injector drive signal of each cylinder (# 1- # 4), fuel pressure, and engine speed Ne when the starting control which concerns on this invention is implemented. Each cylinder in the conventional case where the fuel injection is started after the fuel pressure becomes high (solid line) and in the conventional case where the fuel injection is started with the normal fuel amount before the fuel pressure becomes high (broken line) It is a time chart which compares and shows the relationship of the injector drive signal, fuel pressure, and engine rotational speed Ne of (# 1- # 4). It is a flowchart which shows the control routine of the starting control which concerns on 2nd Example of this invention.

Explanation of symbols

1 Engine 4 Injector (fuel injection valve)
16 Water temperature sensor (cool state detection means)
17 Crank angle sensor 54 High-pressure fuel pump (high-pressure pump)
70 Electronic Control Unit (ECU)
72 Ignition switch 74 Cell motor

Claims (3)

A fuel injection control device for a cylinder injection type spark ignition type internal combustion engine provided with a fuel injection valve in each cylinder for directly injecting fuel into a combustion chamber,
A high-pressure pump that pressurizes fuel by operating the internal combustion engine and supplies high-pressure fuel to the fuel injection valve;
Cold detection means for detecting that the internal combustion engine is cold;
Fuel pressure detecting means for detecting the pressure of the fuel pressurized by the high pressure pump or a pressure correlation value;
When the internal combustion engine is started, the cold detection means detects that the internal combustion engine is cold, and the fuel pressure detection means detects that the fuel pressure is equal to or higher than a predetermined pressure or the pressure correlation value has reached a predetermined pressure equivalent value. When it is detected, main fuel injection control means for controlling a valve opening period of the fuel injection valve so as to inject a predetermined amount of fuel from the fuel injection valve into the combustion chamber of each cylinder until a complete explosion is reached,
When the internal combustion engine is started, the cold state detection means detects that the internal combustion engine is cold, and the fuel pressure detection means detects that the fuel pressure is smaller than a predetermined pressure or the pressure correlation value reaches a predetermined pressure equivalent value. When it is detected that the fuel does not reach the predetermined pressure or until the pressure correlation value reaches the predetermined pressure equivalent value, the combustion from the fuel injection valve to each cylinder is combusted according to the fuel pressure. Preceding fuel injection control means for controlling the opening period of the fuel injection valve to be shorter so that the fuel injection amount injected into the chamber in the compression stroke is less than the predetermined amount;
A fuel injection control device for an in-cylinder injection type spark ignition type internal combustion engine. The pressure correlation value is the number of strokes of the internal combustion engine accumulated after the start of the internal combustion engine, and the fuel pressure detection means is a stroke number detection means for detecting the number of strokes of the internal combustion engine,
2. The in-cylinder engine according to claim 1, wherein the predetermined pressure equivalent value is a predetermined number of strokes estimated to be accumulated until the fuel pressure reaches the predetermined pressure after the start of the internal combustion engine. A fuel injection control device for an injection type spark ignition type internal combustion engine.   The fuel injection for a direct injection spark ignition type internal combustion engine according to claim 1 or 2, wherein the preceding fuel injection control means continuously or intermittently increases the fuel in a range smaller than the predetermined amount. Control device.

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