JP2000345884A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a drop in performance of an internal combustion engine for directly injecting gaseous fuel to a combustion chamber. SOLUTION: This control device is provided with an injector for directly injecting gaseous fuel to a combustion chamber. In this case, it is provided with an injection required time calculating means (S12) for calculating the time T1 required for fuel injection of the injector on the basis of the rotating state of an engine, an injectable time calculating means (S14) for calculating the time T2 in which fuel injection of the injector is possible on the basis of the rotating state of the engine, and an intake stroke injection control means (S20) for performing the intake stroke injection only for the time T1-T2 which is the difference between the fuel injection required time T1 and the fuel injectable time T2 when the injection required time T1 is longer-than the injectable time T2, and for performing the compression stroke injection for the injectable time T2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine control device for an internal combustion engine that directly injects gaseous fuel into a combustion chamber.

[0002]

2. Description of the Related Art A fuel injection valve for directly injecting fuel into a combustion chamber, as disclosed in Japanese Patent Laid-Open Publication No. 5-288097, relates to an internal combustion engine for directly injecting fuel into a combustion chamber, and the fuel injection thereof. 2. Description of the Related Art There is known a valve provided with a pressure storage chamber for supplying high-pressure fuel to a valve and a supply means for supplying fuel to the pressure storage chamber. This internal combustion engine controls the fuel pressure in the storage chamber to be the target fuel pressure by adjusting the amount of fuel supplied from the fuel supply means to the storage chamber, and also controls the fuel in the storage chamber against the target fuel pressure. The lower the pressure, the earlier the fuel injection timing. Thereby, the fuel injected into the combustion chamber secures the atomization dispersion time, improves the combustion of the fuel, and reduces the amount of generated smoke.

[0003]

However, when such an internal combustion engine control technique is applied to an internal combustion engine driven by gaseous fuel, the performance of the internal combustion engine may not be sufficiently exhibited. That is, if the injection timing to the combustion chamber is changed from the compression stroke to the intake stroke, sufficient intake cannot be performed due to the large volume of the gaseous fuel, and the performance of the internal combustion engine may be degraded. Therefore, in an internal combustion engine driven by the supply of gaseous fuel, the fuel injection timing cannot be easily set to the intake stroke. On the other hand, when the internal combustion engine is driven in a high-load region and a high-speed region, it is difficult to supply a required fuel amount due to a time constraint only by the compression stroke. I have.

Accordingly, the present invention has been made to solve such a problem, and provides an internal combustion engine control device capable of reducing the deterioration of the performance of an internal combustion engine that directly injects gaseous fuel into a combustion chamber. The purpose is to:

[0005]

That is, an internal combustion engine control apparatus according to the present invention is a control apparatus for an internal combustion engine having an injector for directly injecting gaseous fuel into a combustion chamber.
Injection required time calculating means for calculating a time required for fuel injection of the injector based on the rotational state of the internal combustion engine, and injectable time calculating means for calculating a time during which fuel can be injected by the injector based on the rotational state of the internal combustion engine When the required injection time calculated by the required injection time calculation means is longer than the possible injection time calculated by the possible injection time calculation means, the intake stroke injection is performed by the difference between the required injection time and the possible injection time, and the injection is possible. And intake stroke injection control means for performing a compression stroke injection for a long time.

In the internal combustion engine control device according to the present invention, the required injection time calculating means calculates a time required for fuel injection of the injector based on a rotation state of the internal combustion engine, a load of the internal combustion engine and a pressure state of gaseous fuel. It is characterized by that. Also, in the internal combustion engine control device according to the present invention, the above-described injection possible time calculation means calculates a time during which fuel can be injected by the injector based on the rotation state of the internal combustion engine, intake valve closing timing, and ignition timing. It is characterized by the following.

According to these inventions, when the required injection time required for the injection of gaseous fuel is not longer than the injection enabled time depending on the engine driving state or the fuel pressure, the fuel injection in the compression stroke is performed. Done. On the other hand, when the required injection time required for the injection of gaseous fuel is longer than the injectable time that can be injected due to the condition of the engine rotation or the fuel pressure, the fuel injection is performed in the intake stroke by the difference, and then the injection is continued. Fuel injection is performed in the compression stroke for a possible time. As described above, since the fuel injection is performed in the compression stroke as long as the fuel injection is possible, the insufficiency of the intake air into the combustion chamber due to the injection of the gaseous fuel in the intake stroke is suppressed. Therefore, it is possible to prevent a decrease in the performance of the internal combustion engine.

[0008]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

(First Embodiment) FIG. 1 is an explanatory diagram of an internal combustion engine control device according to this embodiment.

As shown in FIG. 1, an internal combustion engine control apparatus 10 according to the present embodiment is applied to control of an internal combustion engine such as a vehicle driven by using gaseous fuel. Gaseous fuel contained in a fuel tank (not shown) is supplied to the engine 20 which is an internal combustion engine. Engine 20 to be controlled
Is a direct injection type, and has an injector 22 for directly injecting gaseous fuel into the combustion chamber 21. The injector 22 is a fuel injection unit that supplies pressurized gaseous fuel to the combustion chamber 21, and is installed, for example, for each cylinder 23 provided in the engine 20.

The combustion chamber 21 is formed above a piston 24 arranged in a cylinder 23. An intake port 25 and an exhaust port 26 are open above the combustion chamber 21. An intake valve 27 is arranged in the intake port 25, and an exhaust valve 28 is arranged in the exhaust port 26. The intake port 25 is an intake port for supplying air to the combustion chamber 21 and is opened and closed by an intake valve 27. The exhaust port 26 is an exhaust port for discharging air from the combustion chamber 21 and is an exhaust valve 2.
8 is opened and closed. An ignition device 29 is provided above the combustion chamber 21.

The engine 20 is provided with a variable valve timing mechanism 30. The variable valve timing mechanism 30 is disposed above the intake valve 27, and
7 is changed. Further, the engine 20
The crankshaft 35 is provided with a crank position sensor 36. Crank position sensor 3
Reference numeral 6 denotes an engine rotation state detecting unit that detects the rotation state of the engine 20, and detects, for example, a rotation speed and a rotation change of the engine 20.

The delivery pipe 17 is connected to the injector 22. The delivery pipe 17 is for distributing the gaseous fuel pressure-fed from the fuel tank (not shown) through the pipe 13 to the injectors 22.
The delivery pipe 17 is provided with a pressure sensor 31. The pressure sensor 31 is connected to the delivery pipe 17.
It is a fuel pressure detecting means for detecting the pressure of the gaseous fuel inside. Further, the delivery pipe 17 is provided with a fuel temperature sensor 32. The fuel temperature sensor 32 is connected to the delivery pipe 17.
It is a fuel temperature detecting means for detecting the temperature of the gaseous fuel inside.

A throttle valve 42 is provided on an intake pipe 41 provided upstream of the intake port 27.
The opening / closing state of the throttle valve 42 is operated by driving a throttle motor 43. The opening of the throttle valve 42 is determined by a throttle position sensor 44.
Is detected by Further, an accelerator sensor 51 is provided, and an operation state of an accelerator pedal 52 is detected.

The internal combustion engine control device 10 is provided with an ECU 50. The ECU 50 controls the internal combustion engine control device 10
It controls the entire device, including a CPU, a ROM,
It is mainly composed of a computer including a RAM. Various control routines including an internal combustion engine control routine are stored in the ROM.

The ECU 50 is connected to the pressure sensor 31 and receives a pressure detection signal of the gaseous fuel in the delivery pipe 17. In addition, the ECU 50 controls the fuel temperature sensor 3
2, and a temperature detection signal of the gaseous fuel in the delivery pipe 17 is input. Also, the ECU 50
It is connected to the variable valve timing mechanism 30 and receives a variable valve timing detection signal.

The ECU 50 is connected to a throttle position sensor 44, and receives a detection signal of a throttle valve opening. The ECU 50 is connected to an accelerator sensor 51, and receives a detection signal of an operation state of an accelerator pedal 52. Further, the ECU 50
Is connected to the crank position sensor 36,
A detection signal of the rotation state of the engine 20 is input.

The ECU 50 is connected to the injector 22, outputs an injection control signal to the injector 22, and controls the injection of gaseous fuel. Further, the ECU 50 outputs a valve timing control signal to the variable valve timing mechanism 30 to control the closing timing of the intake valve 27. Also,
The ECU 50 outputs an ignition control signal to the ignition device 29,
Control ignition timing. Further, the ECU 50 outputs a throttle opening control signal to the throttle motor 43 to control the opening of the throttle valve 42.

Next, the operation of the internal combustion engine control device will be described.

FIG. 2 is a flowchart showing the operation of the internal combustion engine control device 10. First, step S1 in FIG.
At 0 (hereinafter simply referred to as “S10”; the same applies to other steps), the fuel pressure is read based on the pressure detection signal output from the pressure sensor 31 and output from the crank position sensor 36. The engine rotation state is read based on the detected engine rotation signal, the engine load is read based on the detection signal output from the throttle position sensor 44, and the signal output from the sensor installed in the variable valve timing mechanism 30 is read. , The opening / closing timing of the intake valve 27 is read.

Next, the routine proceeds to S12, where the required injection time T
1 is performed. The term "required injection time" as used herein refers to the time required to inject a fixed amount of gaseous fuel in one fuel injection, based on the current engine rotation state, engine load state, fuel pressure, and the like. It is determined. That is, the required injection time T1 is calculated according to the engine rotation state, the fuel pressure, and the engine load read in S10. The calculation of the required injection time T1 may be performed by a map process using a map corresponding to the fuel pressure, the engine rotation state, and the engine load. As the engine load, a value read based on a detection signal of the accelerator sensor 51 may be used.

Then, the flow shifts to S14, where the injection possible time T
2 are performed. The “injectable time” here is a time calculated from the closing time of the intake valve 27,
It means the time until injection into the combustion chamber 21 becomes impossible at the current fuel pressure or the time until ignition by the ignition device 29. The injection possible time T2 is calculated based on the engine rotation state read in S10, the opening / closing timing of the intake valve 27, the fuel pressure, and the ignition timing of the ignition device 29.
The calculation of the injection possible time T2 may be performed by a map process using a map corresponding to the opening / closing timing of the intake valve 27, the fuel pressure, and the ignition timing of the ignition device 29.

Next, the flow shifts to S16, where it is determined whether the calculated required injection time T1 is longer than the available injection time T2. When it is determined that the required injection time T1 is longer than the available injection time T2, the process proceeds to S18, where the injection time in the intake stroke is calculated. The injection time in the intake stroke is
It is calculated based on the difference between the required injection time T1 and the available injection time T2, and specifically, T1-T2 is the injection time in the intake stroke.

Then, the flow shifts to S20, where an injection control signal is output from the ECU 50 to the injector 22, and gaseous fuel is injected. As shown in FIG. 3, the injection of the gaseous fuel starts from the time when the rotation of the crankshaft reaches the bottom dead center of the intake and the time that is the difference between the required injection time T1 and the available injection time T2 goes back. Is done. Then, the injection of the gaseous fuel is performed for the required injection time T1. For this reason, the time that is the difference between the required injection time T1 and the available injection time T2 is the intake stroke injection, and the available injection time T2 is the compression stroke injection. In this case, the start of the injection in the intake stroke is based on the required injection time T1 and the available injection time T from the intake bottom dead center.
2 may be performed from the time when the time T1-T2 has been traced back from the time when the intake valve 27 is closed, instead of from the time when the time T1-T2 which is the difference from the time T2 is traced back.

On the other hand, if it is determined in S16 that the required injection time T1 is not longer than the available injection time T2,
Then, the process proceeds to 22, and the compression stroke injection is performed. That is, E
An injection control signal is output from the CU 50 to the injector 22, and as shown in FIG. 4, the gas fuel is injected only in the compression stroke. This gaseous fuel injection is performed by the intake valve 27.
From the time of valve closing, and from the time of valve closing, the required injection time T
It ends after one elapse.

FIG. 5 shows the relationship between the required injection time and the compression stroke injection and the intake stroke injection. As shown in FIG. 5, for example, when the engine load is small and the required injection time T1 is short, the gaseous fuel is injected by the compression stroke injection.
Then, when the engine load increases and the required injection time T1 becomes longer than the available injection time T2, the intake stroke injection is performed together with the compression stroke injection. When the engine load further increases and the required injection time T1 becomes longer, only the intake stroke injection time becomes longer while the compression stroke injection time remains unchanged.

As described above, according to the internal combustion engine control device 10 according to the present embodiment, the required injection time T1 required for the injection of gaseous fuel can be injected depending on the engine rotation state or the fuel pressure. When it is not longer than the time T2, the fuel injection in the compression stroke is performed. On the other hand, when the required injection time T1 required for the injection of the gaseous fuel is longer than the injectable time T2 that can be injected depending on the engine rotation state or the fuel pressure, etc. Then, the fuel injection in the compression stroke is continued for the injectable time T2. As described above, since the fuel injection is performed in the compression stroke as long as the fuel injection is possible, the insufficiency of the intake air into the combustion chamber 21 due to the injection of the gaseous fuel in the intake stroke is suppressed. Therefore, it is possible to prevent the performance of the engine 20 from lowering.

Further, according to the internal combustion engine control apparatus 10 of the present embodiment, the injector 22 can be driven without increasing the size of the injector 22 while suppressing the performance of the engine 20 from decreasing. For example, if an injector having a large injection capacity is used as the injector 22, it is conceivable that fuel injection can always be performed in the compression stroke regardless of the rotation state of the engine 20 or the like. However, in such a case, the increase in size leads to deterioration of mountability, increase in cost, and difficulty in low injection at idling. On the other hand, in the internal combustion engine control device 10 according to the present embodiment, it is possible to drive the engine 20 efficiently without increasing the size of the injector.

Further, in the internal combustion engine control device 10 according to the present embodiment, fuel injection only during the intake stroke is not performed.
It is possible to prevent a problem that a large amount of gaseous fuel is injected in the intake stroke and the gaseous fuel flows backward to the intake pipe.

(Second Embodiment) In the first embodiment, the internal combustion engine control device 10 applied to the control of a vehicle internal combustion engine using gaseous fuel has been described. The present invention is not limited to this, and any other device that controls an internal combustion engine driven by gas fuel may be used. In this case, the same operation and effect as those of the internal combustion engine control device 10 according to the first embodiment can be obtained.

[0031]

As described above, according to the present invention, the fuel is injected in the compression stroke as long as the fuel injection is possible. Becomes insufficient. Therefore,
A decrease in the performance of the internal combustion engine can be prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an internal combustion engine control device according to a first embodiment.

FIG. 2 is a flowchart illustrating an operation of the internal combustion engine control device according to the first embodiment.

FIG. 3 is a timing chart showing an operation of the internal combustion engine control device according to the first embodiment.

FIG. 4 is a timing chart showing an operation of the internal combustion engine control device according to the first embodiment.

FIG. 5 is an explanatory diagram of the relationship between the required injection time and the compression stroke injection and the intake stroke injection in the internal combustion engine control device according to the first embodiment.

[Explanation of symbols]

10: internal combustion engine control device, 20: engine, 21: combustion chamber, 22: injector.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) F02D 13/02 F02D 13/02 J 19/02 19/02 D 41/02 301 41/02 301K 41/14 330 41/14 330B 41/34 41/34 EF term (reference) 3G092 AA06 AA11 AB06 BB01 BB06 BB13 DA01 DA08 DC03 DG08 EA08 EC09 FA02 FA50 GA05 GA06 HA06Z HA11Z HA13X HA13Z HB01X HB01Z HB02X HB03Z HEBZ HB03Z HBZ HB03Z H04Z JA01 KA09 MA11 MA19 ND03 PB08Z PE01Z PE09Z PE10Z

Claims (3)

[Claims] 1. A control device for an internal combustion engine including an injector for directly injecting gaseous fuel into a combustion chamber, wherein a required injection time calculation for calculating a time required for fuel injection of the injector based on a rotation state of the internal combustion engine. Means, an injectable time calculating means for calculating a time during which fuel can be injected by the injector based on a rotation state of the internal combustion engine, and an injection required time calculated by the required injection time calculating means. An intake stroke injection control means for performing an intake stroke injection by a difference between the required injection time and the available injection time when the injection time is longer than the available injection time calculated by the means, and performing a compression stroke injection of the available injection time; An internal combustion engine control device comprising: 2. The injection required time calculation means calculates a time required for fuel injection of the injector based on a rotation state of the internal combustion engine, a load on the internal combustion engine and a pressure state of the gaseous fuel. 2. The internal combustion engine control device according to claim 1, wherein: 3. The fuel injection time calculating means calculates a time during which fuel can be injected by the injector based on a rotation state of the internal combustion engine, intake valve closing timing, and ignition timing. Item 3. An internal combustion engine control device according to item 1 or 2.