JPH07166856A - Exhaust emission control device for automobile diesel engine - Google Patents

Abstract

PURPOSE:To reduce a discharge amount of nitrogen oxide and black smoke by supplying high temperature pressurized secondary air to exhaust gas, afterburning the exhaust gas, and decreasing a discharge amount of harmful discharge substance, by an exhaust emission device set up with a secondary air heating pipe in the internal side part. CONSTITUTION:A short cylindrical exhaust emission control device main unit 1, increasing an internal diameter by a necessary amount larger than the internal diameter of an exhaust manifold discharge port, is fabricated, and a coil-shaped secondary air heating pipe 2 is provided in an internal side part of this main unit. Further in the inside, a bar-shaped combustion assist metal fixture 3 is set up by a supporting fixture 4. This emission control device 1 is connected in its upper/lower to an exhaust manifold and exhaust pipe, to supply high temperature pressurized secondary air to high temperature exhaust gas circulated in the inside of these manifold and pipe, and the exhaust gas is after burned to reduce a discharge amount of harmful discharge substance. In this way, a discharge amount of nitrogen oxide and black smoke can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to purification of exhaust gas from automobiles. Nitrogen oxides and black smoke emitted from diesel engines have been raised as social problems such as adverse health effects, and the reduction of their emissions. The purpose is to prevent pollution.

[0002]

2. Description of the Related Art As a measure for emission of harmful exhaust gas of a diesel engine, improvement of combustion effect by improvement of engine,
For the discharge of black smoke, a method of filtering with a dust collector is used.

[0003]

Since the diesel engine for automobiles has a large compression ratio and a high combustion temperature as compared with a gasoline engine, the emission of harmful emission substances and nitrogen oxides is relatively large. In addition, black smoke is emitted in large amounts due to incomplete combustion of fuel at the time of high load and rapid acceleration. The challenge is to reduce the amount of harmful emissions as described above.

[0004]

Due to the characteristics of an automobile diesel engine, exhaust gas purification is not easy. that is,
Diesel engine fuel is mainly light oil, and its flash point and distillation temperature are higher than those of gasoline, so it is difficult to achieve the effect even by re-combustion by supplying secondary air as a method of purification. In order to solve the above-mentioned problems, the present invention achieves the purpose of exhaust gas purification by supplying high temperature, pressurized secondary air into exhaust gas by a purifying device to enable re-combustion.

[0005]

The air supplied by the air supply device including the air compressor, the air tank, and the air control device is introduced into the secondary air heating pipe, and the air inside the heating pipe is heated by the heat quantity of the exhaust gas flowing through the purification device. Heating, jetting into the exhaust gas,
By mixing with stirring, unburned substances in the exhaust gas,
Oxygen in the secondary air acts and reburns. The amount of heat generated by re-combustion merges with the amount of heat of the exhaust gas and heats the secondary air heating pipe and the combustion-assisting metal fitting to further increase the combustion effect.

[0006]

EXAMPLES As shown in FIGS. 1 and 2, a short tubular purifying device body (1) having a required inner diameter larger than an inner diameter of an exhaust manifold discharge port of a mounted diesel engine was produced. , A coil-shaped secondary air heating pipe (2) inside the main body, and a rod-shaped combustion assisting metal fitting (3) inside the pipe.
Is installed by a support tool (4), and the purification device is connected to the upper and lower sides of the exhaust manifold (5) and the exhaust pipe (6). The required length of the secondary air heating pipe (2),
The metal pipe of the inner diameter is formed into a coil shape, and the upper end portion is directed toward the exhaust gas discharge direction, and the trumpet-shaped air jet port is provided, and the other end is provided as an air inlet port so as to project outside the purifying device body. The combustion-assisting metal fitting (3) is made of a metal or alloy such as copper, bronze, or tungsten that is easily red-heated by heating, formed into a required number of rods, and installed inside the secondary air pipe by the same support. As a secondary air supply source, a part of the air such as an intake supercharger or an air brake may be used, but in the embodiment, a small electric compressor (blower) (7) is used as a device and compressed. Air is stored in the air tank (8). The air in the air tank is adjusted to the pressure required for supply by the pressure regulator and sent to the air control device (10) by the conduit (9). The air control device has a built-in air circulation valve, and mainly operates the air valve by an electromagnetic device of an electric circuit that is connected to each sensor such as the accelerator mechanism and the correction, such as engine temperature, rotation speed, exhaust gas concentration, etc. To control. The controlled air passes through the check valve (11) and flows into the secondary air heating pipe. The check valve is installed to prevent backflow of secondary air when the exhaust brake is used. The air in the secondary air heating pipe is heated by a part of the high heat quantity immediately after combustion in the cylinder in the exhaust gas flowing through the inside of the purifying device main body. Oxygen in the secondary air that has been jetted, stirred, mixed, and supplied into the high-temperature exhaust gas acts on unburned substances in the exhaust gas to achieve re-combustion. The combustion-assisting metal fitting heats and red heats the secondary air heating tube to assist the re-combustion action, and also accumulates the amount of heat at high temperature in the exhaust gas to increase the re-combustion effect. The amount of heat generated during reburning is
In addition to the heat quantity of the exhaust gas, it can be used again for heating the secondary air pipe and the combustion-assisting metal fitting, and the effect of the above heating is increased. In addition, since the secondary air jet is installed in the direction of exhaust gas discharge of the engine, it assists exhaust during secondary air jetting, thus reducing exhaust pressure of the engine during medium and high speed rotation.
It helps increase the output due to the exhaust effect.

[0007]

The present invention, as described by the embodiments,
It has made it easier to reburn exhaust gas from diesel engines, which had been difficult to achieve in the past, and has made it possible to reduce emissions of nitrogen oxides and black smoke, which could not be easily reduced. high temperature,
Nitrogen oxide NOx generated by high-pressure combustion reacts with unburned substances, mainly hydrocarbons HC, and re-combusts at a temperature and pressure lower than that at the time of generation, thereby causing N ₂ , H ₂ by an oxidation reaction action. Since it is converted into O and CO ₂ and discharged, it is effective in reducing the NOx emission amount. Black smoke is carbon-based solids such as soot and tar in the exhaust gas, and although it was not easy to remove it by combustion, this device allows the exhaust gas to be burned at a high temperature. Since C and O ₂ act and are emitted as CO ₂ , they are effective in reducing the emission amount of black smoke.

[Brief description of drawings]

FIG. 1 is an elevation view of the present apparatus (showing a partial cross section).

FIG. 2 is a plan view of the device.

FIG. 3 is a schematic diagram showing the arrangement of the device.

[Explanation of symbols]

1 Purification Device Main Body 9 Conduit 2 Secondary Air Heating Tube 10 Air Control Device 3 Combustion Aid Metal Fitting 11 Air Check Valve 4 Support 5 Exhaust Manifold 6 Exhaust Pipe 7 Air Compressor 8 Air Tank

Claims (1)

[Claims] 1. A short tubular purifying apparatus main body having a coil-shaped secondary air heating pipe and a combustion-assisting metal fitting on the inner side between an exhaust manifold of an automobile diesel engine and an exhaust pipe connecting portion. , Connect to the exhaust manifold and exhaust pipe, up and down, respectively. Air compressed, accumulated, and conditioned by an air compressor, air tank, and air control device in advance through a conduit,
It is introduced from the air inlet of the secondary air heating pipe, and immediately after combustion in the cylinder, due to the heat quantity of the high temperature exhaust gas itself,
The secondary air that has flowed into the heating pipe is heated, and is ejected from the air ejection port at the tip of the heating pipe into the exhaust gas flowing through the purification device. In the hot exhaust gas, hot secondary air with a pressure is mixed by stirring, and supplied,
It enables exhaust gas re-combustion for diesel engines that are not easy to re-combust, and achieves reduction of harmful exhaust gas and black smoke emissions by re-combustion. In the device configured as described above, by the purifying device having the secondary air heating pipe installed inside, the high temperature exhaust gas flowing through the inside of the device has a high temperature,
An exhaust emission control system for automobile diesel engines that supplies pressurized secondary air and reburns exhaust gas to reduce the emission of harmful emissions.