JPH05231246A - Alcohol engine - Google Patents

Abstract

PURPOSE:To improve fuel consumption in a way to keep an air-fuel ratio at a low load area in a combustible range by connecting an EGR valve to an EGR pipe and releasing the EGR valve when an engine load is low. CONSTITUTION:A part of exhaust gas is returned through an EGR pipe 27 to the intake air side. A computer 20 detects the running state of an engine 10 through the working of a rotation detecting sensor 31, an engine load sensor 32, an intake air pressure sensor 33, and an intake air temperature sensor 34 and regulates the opening of an EGR valve 28 through the working of an actuator 29 according to a preset map. Further, the computer 20 regulates the opening of an intake air throttle valve 25 by means of an actuator 26. Especially, the EGR valve 28 is opened by means of an actuator 29, and an air-fuel ratio is reduced to a value lower than value available when EGR is not carried out. This constitution improves fuel consumption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alcohol engine, and more particularly to an alcohol engine in which alcohol fuel is injected into a cylinder for combustion.

[0002]

2. Description of the Related Art Light oil has been widely used as a fuel for diesel engines. Light oil is the most suitable fuel for diesel engines because of its excellent ignitability. However, there is a drawback in that the exhaust gas contains nitrogen oxides and black smoke, and there are many problems in terms of air pollution.

In order to solve such a drawback, an alcohol engine has been proposed in which alcohol fuel is used instead of light oil. That is, while injecting alcohol fuel into the cylinder, if necessary, it is ignited by an ignition device and burned,
By compensating the poor ignitability of alcohol fuel with an ignition device, the diesel engine can be established.

[0004]

Generally, in a diesel engine using alcohol fuel, the flammable range is limited to a relatively narrow range as shown in FIG. Therefore, if only light oil is replaced with alcohol fuel, the air-fuel ratio will deviate from the flammable range in the low engine load range, which will cause incomplete combustion and worsen fuel consumption. Incompletely combusted components, that is, unburned methanol, aldehydes, hydrocarbons, carbon monoxide, etc. are discharged together with the exhaust gas.

The present invention has been made in view of the above problems, and provides an alcohol engine in which the fuel efficiency is improved by setting the air-fuel ratio within a combustible range particularly in a low load range. The purpose is that.

[0006]

DISCLOSURE OF THE INVENTION The present invention is an alcohol engine in which alcohol fuel is injected into a cylinder for combustion, and an intake system and an exhaust system are communicated with each other.
A GR pipe is provided and EGR is installed in the EGR pipe.
If the valve is connected and the engine load is low, the EG
The R valve is opened.

[0007]

In the low load region, the EGR valve is opened to allow EGR (Exhaust Gas Rec
Since the exhaust gas recirculation is performed, not only the air-fuel ratio in the low load range can be set to the combustible range, but also the ignitability due to the rise in intake air temperature can be improved. Therefore, the combustion characteristics in the middle and low load range are improved, and the fuel efficiency is improved. In addition, since incomplete combustion disappears in the low load region, emissions of unburned methanol, aldehydes, hydrocarbons, and carbon monoxide are suppressed.

[0008]

1 shows an alcohol engine according to an embodiment of the present invention, in which an intake manifold 11 and an exhaust manifold 12 are mounted on both sides of an engine body 10. Intake manifold 1
An intake pipe 13 is connected to the intake pipe 1, and the intake pipe 1
The tip of 3 is connected to the air cleaner 14. On the other hand, the exhaust manifold 12 is connected to the exhaust pipe 15.

Further, the engine 10 has a fuel injection pump 17. An electronic timer 18 is provided on the camshaft of the fuel injection pump 17, and the timing of fuel injection is adjusted by the electronic timer 18. An electronic governor 19 is provided on the rear side of the fuel injection pump 17 to adjust the supply amount of fuel injected at one time. The electronic timer 18 and the electronic governor 19 are both computer 20
Is controlled by.

An exhaust brake 23 is provided in the exhaust pipe 15, and the exhaust brake 23 is an actuator 24.
It is designed to be opened and closed by. Intake pipe 13
An intake throttle valve 25 is provided in the valve, and the opening degree is adjusted by an actuator 26.
The intake pipe 13 and the exhaust pipe 15 are connected by an EGR pipe 27. Moreover, the EGR pipe 27 has EG
An R valve 28 is attached and an actuator 29
It is designed to be opened and closed by. Moreover, the actuator 29 is controlled by the computer 20.

The rotation speed of the engine 10 is detected by a rotation speed sensor 31. The engine load or accelerator opening is detected by an engine load sensor 32 provided in the electronic governor 19. An intake pressure sensor 33 and an intake temperature sensor 34 are attached to the intake pipe 13, respectively. The sensors 31 to 34 are connected to the computer 20.

As shown in FIG. 2, a phase pulse, engine water temperature, exhaust temperature, glow current, vacuum pressure, etc. are also input to the computer 20 for controlling the engine 10. Further, the computer 20 controls the feed pump, canister, ignition device, catalyst heater, indicator lamp, diagnosis and the like.

In the above structure, the engine 10
Fuel injection pump 17 driven by a part of the output of
Pressurizes the alcohol fuel and
Each cylinder is sequentially injected at a predetermined timing. The fuel injected into the cylinder is the intake air introduced into the cylinder through the air cleaner 14, the intake pipe 13, and the intake manifold 11, and is ignited by the heat of the intake air pressurized by the piston moving to the top dead center side. It If necessary, the ignition device operates to assist ignition. Then, the exhaust gas generated by the combustion is discharged into the atmosphere through the exhaust manifold 12 and the exhaust pipe 15.

Moreover, in this engine, a part of the exhaust gas is returned to the intake side through the EGR pipe 27. The computer 20 detects the operating state of the engine 10 by the rotation detection sensor 31, the engine load sensor 32, the intake pressure sensor 33, and the intake temperature sensor 34, and the opening degree of the EGR valve 28 via the actuator 29 according to a preset map. Adjust. Further, the computer 20 adjusts the opening degree of the intake throttle valve 25 by the actuator 26.

Particularly, in the engine 10 of this embodiment, as shown in FIGS.
The R valve 28 is opened by the actuator 29, and the mixing ratio of fuel and air, that is, the air-fuel ratio in the low load region to the medium load region, is set to a value smaller than that in the case where EGR is not performed. This will improve fuel efficiency.

In a general diesel engine which generally uses light oil, EGR is used for the purpose of reducing nitrogen oxides. On the other hand, in the alcohol engine, since the combustible mixing ratio is narrow, a great effect can be obtained for improving fuel efficiency and improving ignitability by increasing intake air temperature.

When the engine is out of the flammable range when the engine is not in the low load range and EGR is not applied, not only the fuel consumption deteriorates, but also unburned methanol, aldehyde, hydrocarbons,
Carbon monoxide and the like will be discharged together with the exhaust gas.
However, by applying EGR, the air-fuel ratio can be set to the combustible range even in the low load range, as shown in FIG.
Not only will fuel efficiency be improved, but emission of harmful substances will be prevented.

In this engine, the intake air temperature and the intake air pressure are measured by the temperature sensor 34 and the pressure sensor 33, respectively.
Is detected by the computer 20, and the excessive EGR is corrected by the computer 20. The intake throttle valve 25 is operated to increase the EGR rate at an extremely low load to increase intake pressure and
It serves to increase the amount of exhaust gas returning through the pipe 27.

The computer 20 for controlling the EGR is further adapted to control the fuel system. As shown in FIG. 2, the feed pump from the tank and the feed pump from the tank for preventing the in-tube evaporation of the methanol fuel are used. Switching control of the canister for suppressing vapor emission from the tank to the atmosphere is performed. Computer 2
0 controls the ignition device, and controls the ignition auxiliary plug for a low cetane number to perform startability and power saving control during operation. In addition, the life of the plug is extended by setting the speed and load.

[0020]

As described above, according to the present invention, the EGR pipe that connects the intake system and the exhaust system is provided, and
The EGR valve is connected to the GR pipe so that the EGR valve is opened when the engine load is low.

Therefore, the mixture ratio of fuel and air in the low load range is prevented from being out of the combustible range and incomplete combustion is prevented, and combustion is promoted including ignitability due to increase in intake air temperature. This makes it possible to improve fuel efficiency and prevent incomplete combustion components, that is, unburned methanol, aldehydes, hydrocarbons, carbon monoxide, etc. from being contained in the exhaust gas.

[Brief description of drawings]

FIG. 1 is a plan view showing an alcohol engine according to an embodiment of the present invention.

FIG. 2 is a block diagram of a computer that controls an engine.

FIG. 3 is a graph showing changes in EGR rate.

FIG. 4 is a graph showing changes in air-fuel ratio.

[Explanation of symbols]

 10 engine body 11 intake manifold 12 exhaust manifold 13 intake pipe 15 exhaust pipe 17 fuel injection pump 18 electronic timer 19 electronic governor 20 computer 25 intake throttle valve 26 actuator 27 EGR pipe 28 EGR valve 29 actuator 31 rotation detection sensor 32 engine load sensor 33 Intake pressure sensor 34 Intake temperature sensor

Claims (1)

[Claims] 1. An alcohol engine in which alcohol fuel is injected into a cylinder for combustion, and an EGR pipe for connecting an intake system and an exhaust system is provided, and an EGR valve is connected to the EGR pipe, An alcohol engine, wherein the EGR valve is opened when the load is low.