JPH0598952A - Alcohol engine - Google Patents

Abstract

PURPOSE:To oxidize completely even at the time of idling by providing oxydizing catalyst in which a heater is provided in an exhaust system and operating the heater when temperature of exhaust gas has dropped. CONSTITUTION:An exhaust pipe 15 and an oxydizing catalyst 23 are provided on an exhaust manifold 12 of an engine 10 proper. A heater 24 connected to a battery 25 is provided on the oxydizing catalyst 23. Temperature of exhaust gas is detected by temperature sensors 37, 38, and whether it is within the active temperature zone of the oxydizing catalyst 23 or not is judged by a computer 28. The computer 28 closes a relay contact 26 for heating when it is below the active temperature zone. Thus, it is possible to activate the oxydizing catalyst 23 and oxydize incomplete combustion component when the engine 10 is idling and temperature of exhaust gas is low.

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 When diesel oil is used as a fuel for a diesel engine, the exhaust gas contains nitrogen oxides and black smoke, which causes air pollution. Therefore, a diesel engine has been proposed in which alcohol fuel is used instead of light oil. Such an engine is configured such that alcohol fuel is pressurized by a fuel injection pump and is injected into a cylinder by a fuel injection nozzle to burn it.

[0003]

When alcohol fuel is used instead of light oil, the amount of nitrogen oxides and black smoke in the exhaust gas can be reduced. However, it will newly contain incompletely burned components, that is, unburned methanol, aldehydes, hydrocarbons, carbon monoxide, and the like. In order to remove such unburned components or incompletely burned components, an oxidation catalyst is attached to the exhaust system of the engine, and the incompletely burned components as described above are changed into carbon dioxide gas and water by the oxidizing action of this catalyst. It releases it into the atmosphere.

However, such an oxidation catalyst does not work effectively when the temperature of the exhaust gas is low. That is, when the temperature is lower than the catalyst activation temperature, there is a problem that the above-mentioned harmful substances are directly discharged together with the exhaust gas.

The present invention has been made in view of the above problems, and even when the temperature of exhaust gas is low, the oxidation catalyst effectively acts to turn harmful substances into harmless carbon dioxide gas and water. It is intended to provide an alcohol engine which is changed and discharged.

[0006]

A first aspect of the present invention is an alcohol engine in which alcohol fuel is injected into a cylinder and burned, and an oxidation catalyst is attached to an exhaust system to remove unburned components or incompletely burned components. To oxidize, and to attach a heater to the oxidation catalyst,
Further, a temperature sensor for detecting the temperature of the exhaust gas is provided, and the heater is operated when the temperature of the exhaust gas detected by the temperature sensor falls below a predetermined value.

A second aspect of the invention is an alcohol engine in which alcohol fuel is injected into a cylinder for combustion, and an oxidation catalyst is attached to an exhaust system to oxidize unburned components or incompletely burned components. A heater is attached to the oxidation catalyst, and detection means for detecting the operating state of the engine is provided, and the detection means detects that the engine is in an idling state and the state is continued for a certain period or longer. In the above, the heater is operated.

[0008]

According to the first aspect of the invention, the temperature of the exhaust gas is detected by the temperature sensor, and when the temperature is below the predetermined temperature and below the activation temperature of the catalyst, the heater is activated. The catalyst is activated by this heater, and the unburned components and incompletely burned components contained in the exhaust gas are changed into harmless carbon dioxide gas and water.

According to the second aspect of the present invention, when the engine is detected to be in the idling state and the state is continued for a certain period of time or more, the temperature of the exhaust gas becomes low and becomes lower than the catalyst activation temperature. To activate the heater. The catalyst is activated by the operation of the heater, and the unburned components or incompletely burned components contained in the exhaust gas are oxidized and converted into carbon dioxide gas and water.

[0010]

1 shows an alcohol engine according to a first embodiment of the present invention, in which an intake manifold 11 and an exhaust manifold 12 are provided on both sides of a cylinder block of an engine body 10 constituting the alcohol engine. Are installed respectively. An intake pipe 13 is connected to the intake manifold 11, and an air cleaner 14 is connected to the tip end side of the intake pipe 13. On the other hand, an exhaust pipe 15 is connected to the exhaust manifold 12.

The engine 10 also includes a fuel injection pump 18 as a fuel supply device. A timer 19 is attached to the cam shaft of the fuel injection pump 18, and the phase angle thereof is changed to adjust the fuel injection timing. A governor 20 is attached to the rear side of the fuel injection pump 18 so that the amount of alcohol fuel injected at one time can be adjusted.

An oxidation catalyst 23 is attached to the exhaust pipe 15. A heater 24 is arranged in front of the oxidation catalyst 23. The heater 24 has one end connected to the battery 25 and the other end connected to the ground side via the relay contact 26. The opening and closing of the relay contact 26 is accomplished by a drive circuit 27 having a coil. The drive circuit 27 is controlled by the controller 28.

The controller 28 is composed of a computer, and a rotation detection sensor 31 for detecting the rotation speed of the engine 10, a water temperature sensor 32 for detecting the temperature of the cooling water of the engine 10, and a fuel injection pump 18 on the input side thereof.
The load sensor 33 that detects the load of the engine from the rotational position of the load lever of the governor 20, the vehicle speed sensor 34 that detects the vehicle speed of the vehicle in which this engine is mounted, and the key switch 35 for starting the engine, respectively. It is connected.

In the above structure, the intake air introduced through the air cleaner 14 is introduced into each cylinder of the engine 10 through the intake pipe 13 and the intake manifold 11. Then, as the piston moves toward the top dead center, the intake air is compressed and becomes hot.

Almost in synchronism with the movement of the piston toward the top dead center, the fuel injection pump 18 pressurizes the alcohol fuel and injects the pressurized fuel into the cylinder through the injection pipe and the fuel injection nozzle. The fuel spray is spontaneously ignited by the heat of pressurized intake air. Incidentally, auxiliary ignition means is used if necessary. In this way, the alcohol fuel is burned in the cylinder.

The exhaust gas generated by the combustion of the alcohol fuel in the cylinder is discharged through the exhaust manifold 12 and the exhaust pipe 15. At this time, the exhaust gas is brought into contact with the oxidation catalyst 23 attached to the exhaust pipe 15. The oxidation catalyst 23 oxidizes unburned components and incompletely burned components contained in the exhaust gas, that is, unburned methanol, aldehydes, hydrocarbons, carbon monoxide, etc., and changes them into harmless carbon dioxide gas and water. . In this way, air pollution due to exhaust gas is prevented.

Temperature sensors 37 and 38 are provided in front of and behind the oxidation catalyst 23 of the exhaust pipe 15, and the temperature of the exhaust gas is detected by these temperature sensors. Then, the computer 28 determines whether the temperature detected by the temperature sensors 37 and 38 is in the activation temperature range of the oxidation catalyst 23.

When the temperature detected by the temperature sensors 37, 38 is below the activation temperature range of the catalyst, the computer 28 closes the relay contact 26 via the drive circuit 27. Then, a current flows from the battery 25 to the heater 24,
The heater 24 is activated. As a result, the surface temperature of the oxidation catalyst 23 is raised by the heater 24, and the catalyst 23 is activated.

FIG. 2 shows the change in the exhaust gas temperature by the heater 24. Particularly, when the engine 10 is switched to the idling state and the exhaust gas temperature is gradually lowered, the heater 24 is activated, whereby the exhaust gas temperature is changed. It is clearly shown that the oxidation catalyst 23 is raised and is changed to the active state.

Generally, in an alcohol engine, the oxidation catalyst 23 is preheated or afterheated immediately after the engine is started, but the catalyst becomes inactive during a long idle time when the exhaust temperature becomes low after general operation. If the engine efficiency is increased with particular emphasis on fuel efficiency, the exhaust temperature will drop. This deactivates the catalyst.

According to this embodiment, even when the exhaust gas temperature is lower than the catalyst activation temperature, the added heater 24 imparts the activation performance to the catalyst 23. Therefore, it is particularly suitable as an exhaust gas after-treatment system for an alcohol engine, which emphasizes fuel consumption during idling.

Next, a second embodiment will be described with reference to FIGS. The parts corresponding to those of the first embodiment are designated by the same reference numerals in FIG. 3 and their description is omitted. The feature of this embodiment is that the heater 24 is driven by detecting the idling time instead of the temperature, and the temperature sensors 37 and 38 before and after the oxidation catalyst 23 are omitted.

In general, an alcohol engine has a low exhaust gas temperature immediately after its start, especially at the time of cold start.
The oxidation catalyst 23 is not activated. Therefore, a large amount of incompletely burned components were discharged together with the exhaust gas. Therefore, the heater 24 is attached in front of the oxidation catalyst 23 to raise the temperature of the surface of the catalyst 23. When the engine 10 is started by performing such preheating with the heater 24, the oxidation catalyst 23 is activated immediately after the engine 10 is started. As a precaution, the afterheat mode is set in the afterheat mode to heat the oxidation catalyst 23.

In the engine according to this embodiment, the heater 24 is operated in the afterheat mode II shown in FIG. 2 when the engine is operated in the idling state for a predetermined time or longer. This is because, when the engine is stopped for a long time after idling, the temperature of the exhaust gas becomes low and the oxidation catalyst 23 becomes inactive.

That is, in the engine according to the present embodiment, the computer 28 detects that the heater 24 mounted for preheating is in the idle state for a certain time or more, and the drive circuit 27 and the relay contact 26 are used. By energizing the heater 24 with electricity, the catalyst 23 is operated without deteriorating the fuel consumption.

As described above, in the second embodiment, in the oxidation catalyst 23 provided with the heater 24, it is detected that idling is continued for a long time, and afterheating is performed, the catalyst 2
3 is an activated state. Therefore, by effectively utilizing the heater 24 used before and after the engine is started, the oxidation catalyst 23 is activated when idling for a long time, and idle rotation is increased and combustion is performed. There is no need to worsen the exhaust temperature.

[0027]

According to the first aspect of the present invention, the heater is activated to activate the oxidation catalyst when the temperature of the exhaust gas detected by the temperature sensor falls below a predetermined value. Therefore, activation of the catalyst is achieved at the time of idling when the exhaust temperature becomes low after the general operation, and it is possible to reliably oxidize unburned components and incompletely burned components even at the time of idling.

In the second aspect of the present invention, the detection means detects that the engine is in the idling state, and the heater is activated when the state is continued for a certain time or longer. Therefore, it becomes possible to activate the oxidation catalyst during idling for a long time, and it becomes possible to oxidize unburned components and incompletely burned components in the exhaust gas by the oxidation catalyst.

[Brief description of drawings]

FIG. 1 is a plan view of an alcohol engine according to a first embodiment.

FIG. 2 is a graph showing an operation of activating an oxidation catalyst by a heater.

FIG. 3 is a plan view of an alcohol engine according to a second embodiment.

FIG. 4 is a graph showing an operation of activating a catalyst.

[Explanation of symbols]

 10 Engine Main Body 12 Exhaust Manifold 15 Exhaust Pipe 18 Fuel Injection Pump 23 Oxidation Catalyst 24 Heater 25 Battery 26 Relay Contact 27 Drive Circuit 28 Controller (Computer) 31 Rotation Detection Sensor 33 Load Sensor 35 Key Switch 37 Temperature Sensor 38 Temperature Sensor

Claims (2)

[Claims] 1. An alcohol engine in which alcohol fuel is injected into a cylinder for combustion, and an oxidation catalyst is attached to an exhaust system to oxidize unburned components or incompletely burned components. A heater is attached, a temperature sensor for detecting the temperature of the exhaust gas is provided, and the heater is activated when the temperature of the exhaust gas detected by the temperature sensor falls below a predetermined value. Alcohol engine characterized by. 2. An alcohol engine in which alcohol fuel is injected into a cylinder for combustion, and an oxidation catalyst is attached to an exhaust system to oxidize an unburned component or an incompletely burned component. A heater is attached, and detection means for detecting the operating state of the engine is further provided. When the detection means detects that the engine is in an idling state and the state is continued for a certain period or longer, the heater is used. The alcohol engine is characterized by being operated.