JPH11159360A - Method and device for controlling combustion of dual fuel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of abnormal combustion in the case where an air-fuel mixture ratio of the gaseous fuel is lean in a device provided with a primary and a secondary fuel system by providing a fuel injection pressure adjusting process for adjusting the fuel injection pressure so as to control the fuel when abnormal combustion is generated. SOLUTION: In a dual fuel engine to be operated by supplying the gaseous fuel from an intake pipe through a mixer or the like and injecting the liquid fuel for operation to a combustion chamber from an injection nozzle 8 through a fuel injection device, an exhaust manifold inner pressure sensor 25 fitted to an engine E is connected to an abnormal combustion condition reading means 16 of a control device 15. A pressure sensor 12 fitted to a pressure accumulator 10 is connected to a pressure sensor signal reading means 19, and connected to a pressure-feeding pump control means 18 and a pressure-feeding pump 9. At the time of operation, the signal from the inner pressure sensor 25 is read by the reading means 16, and the abnormal combustion corresponding means 17 discriminates whether combustion is abnormal or not, and in the case of YES, injection pressure of the liquid fuel is raised.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas fuel (primary fuel) supplied from a mixer or the like via an intake pipe, and a liquid fuel (secondary fuel) injected into a combustion chamber via a fuel injection device. Regarding dual fuel engines. In other words, the present invention relates to combustion of a dual fuel engine having a primary fuel system that mixes and supplies air and gaseous fuel, and a secondary fuel system that includes a fuel injection device that injects liquid fuel into a cylinder. The present invention relates to a control method and device.

[0002]

2. Description of the Related Art For example, a dual fuel engine which supplies gaseous fuel such as city gas from an intake pipe via a mixer or the like and injects liquid fuel such as light oil into a combustion chamber via a fuel injection device to operate is known. Have been.

[0003] In order to protect the environment, a dual fuel engine uses a main fuel (primary fuel) as a gaseous fuel and a small amount of liquid fuel (secondary fuel) injected into a combustion chamber as an ignition source. NO in exhaust gas while maintaining high efficiency of
It is possible to reduce x.

Here, it is extremely effective to increase the air ratio of gaseous fuel in order to reduce NOx in exhaust gas.

[0005] However, if the mixture ratio of the gaseous fuel is excessively reduced for exhaust gas purification (reduction of NOx in the exhaust gas), the fuel / air mixture ratio varies between cylinders of the gas engine. Further, there is a problem that a so-called "misfire" (or abnormal combustion) occurs in some cylinders due to insufficient supply of liquid fuel or the like.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems of the prior art, and can suppress occurrence of abnormal combustion even when the mixture ratio of gaseous fuel is made lean. It is an object of the present invention to provide a method and an apparatus for controlling combustion of such a dual fuel engine.

[0007]

SUMMARY OF THE INVENTION A combustion control method for a dual fuel engine according to the present invention comprises a primary fuel system for mixing and supplying air and gaseous fuel, and a fuel injection device for injecting liquid fuel into a cylinder. An abnormal combustion detection step for detecting the occurrence of abnormal combustion (or misfire, hereinafter the same in the present specification), and a case where abnormal combustion occurs. And a fuel injection pressure adjusting step of controlling combustion by adjusting the fuel injection pressure based on a signal from the abnormal combustion detection means.

Further, according to the combustion control method for a dual fuel engine of the present invention, air and gaseous fuel are mixed and supplied.
A combustion control method for a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder; an abnormal combustion detection step of detecting occurrence of abnormal combustion; A fuel injection timing adjusting step of adjusting the fuel injection timing based on a signal from the abnormal combustion detecting means when combustion occurs to control combustion.

Further, according to the present invention, there is provided a combustion control method for a dual fuel engine, comprising: a primary fuel system for mixing and supplying air and gaseous fuel; and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder. A combustion control method for a dual fuel engine having an abnormal combustion detection step of detecting the occurrence of abnormal combustion, and adjusting the fuel injection amount by a signal from the abnormal combustion detection means when abnormal combustion occurs, to perform combustion. Controlling the fuel injection amount.

[0010] A combustion control method for a dual fuel engine according to the present invention provides a primary fuel system for mixing and supplying air and gaseous fuel, and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder. A combustion control method for a dual-fuel engine having an abnormal combustion detection step of detecting the occurrence of abnormal combustion, and, when abnormal combustion occurs, the engine control device determines a fuel injection timing by a signal from the abnormal combustion detection means. Controlling the combustion by adjusting the fuel injection pressure or the fuel injection amount.

A combustion control device for a dual fuel engine according to the present invention comprises a primary fuel system for mixing and supplying air and gaseous fuel, and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder. In the combustion control device for a dual fuel engine having the above, an abnormal combustion detecting means for detecting the occurrence of abnormal combustion, and a control means for controlling the fuel injection pressure based on a signal from the abnormal combustion detecting means are provided. .

Further, the combustion control apparatus for a dual fuel engine according to the present invention supplies a mixture of air and gaseous fuel.
Abnormal combustion detection means for detecting the occurrence of abnormal combustion in a combustion control device of a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder; Control means for controlling the fuel injection timing based on a signal from the abnormal combustion detection means.

Further, a combustion control apparatus for a dual fuel engine according to the present invention comprises a primary fuel system for mixing and supplying air and gaseous fuel, and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder. A combustion control device for a dual fuel engine having an abnormal combustion detecting means for detecting occurrence of abnormal combustion, and a control means for controlling a fuel injection amount based on a signal from the abnormal combustion detecting means. I have.

A combustion control device for a dual fuel engine according to the present invention comprises a primary fuel system for mixing and supplying air and gaseous fuel, and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder. In a combustion control device of a dual fuel engine having a system, an abnormal combustion detecting means for detecting occurrence of abnormal combustion, and a fuel injection timing, a fuel injection pressure, or a fuel injection amount controlled by a signal from the abnormal combustion detecting means. And a control device that performs the control.

According to the method and apparatus for controlling combustion of a dual fuel engine of the present invention having the above-described configuration,
If the occurrence of abnormal combustion is detected, the fuel injection timing,
Either the fuel injection pressure, the fuel injection amount, or a combination thereof is performed. Here, when abnormal combustion occurs in the gas engine, the abnormal combustion is eliminated by controlling the fuel injection timing, fuel injection pressure, or fuel injection amount. Therefore, according to the present invention, even if the air ratio of the primary fuel is increased (the ratio of the gaseous fuel included in the primary fuel is reduced) and abnormal combustion is likely to occur, the abnormal combustion is prevented from occurring. It can be controlled to eliminate or suppress it.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a piston 2 is slidably inserted into a cylinder 1 of a dual fuel engine generally indicated by reference numeral E, and a pin 3 of the piston 2 and a crank pin 4 of a crankshaft (not shown) are connected by a connecting rod 5. Have been. Here, the symbol A indicates the locus of the center of the crankpin 4.

An intake port 6 and an exhaust port 7 are provided on a cylinder head 14 mounted on the upper surface of the cylinder 1. The intake port 6 has an intake valve 6a, and the exhaust port 7 has an exhaust valve 7a. An injection nozzle 8 is attached to a cylinder head 14 on the center line of the cylinder, and is connected to a pressure pump 9 via an accumulator 10 by an injection pipe 11.

The exhaust manifold internal pressure sensor 2 serving as abnormal combustion detecting means attached to the engine E
5 is connected to the abnormal combustion state reading means 16 of the control device 15 by an electric circuit, the pressure sensor 12 attached to the accumulator 10 is connected to the pressure sensor signal reading means 19 by an electric circuit, (Control means for controlling the fuel injection pressure based on a signal from the abnormal combustion detection means or control means for controlling the fuel injection amount based on a signal from the abnormal combustion detection means) is connected to the pump 9 by an electric circuit. Note that reference numeral F indicates a fuel circuit that supplies fuel to the pressure pump 9.

The operation will be described below with reference to FIG. At the time of operation, first, a signal from the internal pressure sensor 25 is read by the reading means 16 (step S1), and judgment is made by the abnormal combustion handling means 17 (step S2). If the determination is NO, the process returns. If the determination is YES, the injection pressure of the liquid fuel is increased (step S3), the return is made, and the control ends. In this embodiment, since a so-called common rail type fuel injection device using an accumulator is used, an increase in the injection pressure is accompanied by a change in the injection amount at the same time.

FIG. 2 shows a second embodiment of the present invention.
The control device 15a is provided with the pump control means 18 in the first embodiment, while the injection timing / period control means 20 (the control for controlling the fuel injection timing by the signal from the abnormal combustion detection means) is provided. The injection timing / period control means 20 is connected to the nozzle 8 by an electric circuit. Others are substantially the same as those of the first embodiment of the present invention. The operation of the second embodiment in FIG. 2 is different from the operation (first embodiment) indicated by “injection pressure increase” in step S3 in FIG. 4 in the operation indicated by “injection timing advance” in step S3 in FIG. Except for the difference, the operation is substantially the same as that of the first embodiment shown in FIG.

FIG. 3 shows a third embodiment of the present invention, in which a control device 15b is configured by adding the second embodiment to the first embodiment.
, The injection pressure (amount) and the injection timing are changed to determine from the change in the presence or absence of abnormal combustion (steps S1 to S5),
Finally, the injection pressure (or injection amount) or the injection timing is changed, or a combination of these controls is performed so that the lean burn state is stably obtained.

[0022]

The present invention is constructed as described above, and is controlled so as to avoid abnormal combustion by a signal from the abnormal combustion detecting means. Therefore, the dual fuel engine supplies fuel with a low air ratio to the dual fuel engine. However, the combustion operation can be performed while preventing or suppressing abnormal combustion.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a combustion control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a third embodiment of the present invention.

FIG. 4 is a flowchart of the control in FIG. 1;

FIG. 5 is a flowchart of the control in FIG. 2;

FIG. 6 is a flowchart of the control in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder 2 ... Piston 5 ... Connecting rod 6 ... Intake port 7 ... Exhaust port 8 ... Injection nozzle 9 ... Pumping pump 10 ... Accumulator 14 ... Cylinder head 15 ・ ・ ・ Control device

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification code FI F02M 21/02 F02M 21/02 V 25/00 25/00 TL

Claims (8)

[Claims] 1. A method of mixing and supplying air and gaseous fuel
A combustion control method for a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder; an abnormal combustion detection step of detecting occurrence of abnormal combustion; A fuel injection pressure adjusting step of adjusting fuel injection pressure based on a signal from abnormal combustion detection means to control combustion when combustion occurs, and a combustion control method for a dual fuel engine. 2. Mixing and supplying air and gaseous fuel 1
A combustion control method for a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder; an abnormal combustion detection step of detecting occurrence of abnormal combustion; A fuel injection timing adjusting step of adjusting fuel injection timing by a signal from abnormal combustion detection means when combustion has occurred to control combustion. 3. A method of mixing and supplying air and gaseous fuel.
A combustion control method for a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder; an abnormal combustion detection step of detecting occurrence of abnormal combustion; A fuel injection amount adjusting step of adjusting the fuel injection amount based on a signal from abnormal combustion detection means when combustion has occurred to control combustion. 4. Mixing and supplying air and gaseous fuel 1
A combustion control method for a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting a liquid fuel into a cylinder; an abnormal combustion detection step of detecting occurrence of abnormal combustion; If combustion occurs,
Controlling the combustion by adjusting the fuel injection timing, the fuel injection pressure, or the fuel injection amount by a signal from the abnormal combustion detection means, and controlling the combustion of the dual fuel engine. 5. A method of mixing and supplying air and gaseous fuel.
Abnormal combustion detection means for detecting occurrence of abnormal combustion in a combustion control device of a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder; Control means for controlling the fuel injection pressure based on a signal from abnormal combustion detection means. The combustion control apparatus for a dual fuel engine. 6. A method of mixing and supplying air and gaseous fuel.
Abnormal combustion detection means for detecting occurrence of abnormal combustion in a combustion control device of a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder; Control means for controlling fuel injection timing based on a signal from abnormal combustion detection means. A combustion control apparatus for a dual fuel engine. 7. A method of mixing and supplying air and gaseous fuel 1
Abnormal combustion detection means for detecting occurrence of abnormal combustion in a combustion control device of a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder; Control means for controlling a fuel injection amount based on a signal from abnormal combustion detection means. A combustion control apparatus for a dual fuel engine. 8. A method of mixing and supplying air and gaseous fuel.
Abnormal combustion detection means for detecting occurrence of abnormal combustion in a combustion control device of a dual fuel engine having a secondary fuel system and a secondary fuel system having a fuel injection device for injecting liquid fuel into a cylinder; A control device for controlling a fuel injection timing, a fuel injection pressure, or a fuel injection amount based on a signal from abnormal combustion detection means, a combustion control device for a dual fuel engine.