KR19980038900A - Secondary air supply of car exhaust system - Google Patents

Abstract

In order to reduce the harmful components of the exhaust gas at the beginning of the start-up, secondary air is injected directly to the outlet of the exhaust gas discharged at high temperature and high pressure, and the unburned harmful components (HC, CO) in the exhaust gas and the secondary O ₂ in the air causes a combustion reaction to reduce the exhaust gas. To this end, the secondary air supply device of the present invention comprises: an air pump (4) in communication with the air cleaner and driven by battery power; An on / off valve (5) which opens only for 1 to 2 minutes during cold start by controlling the air pressurized by the air pump; It consists of an air pipe (7) for injecting the air supplied through the on / off valve directly above the exhaust valve (1) of the exhaust port (2).

Description

Secondary air supply of car exhaust system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary air supply device for an automobile exhaust system, and in particular, by supplying fresh air to the exhaust port to induce spontaneous ignition of noxious gas components, thereby reducing exhaust gas at the initial start (or cold start). To a secondary air supply.

[Private Technology]

In general, the exhaust system of an automobile includes an exhaust manifold, an exhaust pipe, a catalytic converter, and a silencer to exhaust the exhaust gas combusted in the combustion chamber of the engine to the outside.

In such an exhaust system, the exhaust gas discharged from the combustion chamber includes water vapor (H ₂ O), nitrogen (N ₂ ), carbon dioxide (CO ₂ ), and the like, which are harmless to humans, but carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides ( NO _x ) and other toxic substances.

Conventionally, as a method for removing the harmful components of the exhaust gas, the engine improvement method including the combustion chamber, the fuel, ignition, intake and exhaust system as a whole, or install an additional device for controlling the combustion state, and the lean mixer is efficiently burned. In order to achieve this, there are a stratified charge combustion method which simultaneously sucks some dense mixers, and a catalytic converter method which removes harmful gases with an oxidation or reduction catalyst.

In addition, as one of the conventionally known methods, a secondary air supply device is proposed which realizes maximum efficiency of the catalyst after blowing fresh air into the exhaust gas to reduce the content of CO and HC.

This conventional secondary air mixing device is composed of an air pump driven by a belt in a crankshaft of an engine, a control valve and a check valve for controlling pressurized air, and an air injection manifold as an air inlet.

However, when the engine is cooled down, the air-fuel ratio is rich and the combustion state is poor, and a large amount of harmful components (HC, CO) of the exhaust gas are discharged. Particularly, a part of the mixer condenses on the cold cylinder wall between 1 and 2 minutes after cold start, so that a rich air-fuel ratio [ψ = 1.8; 1.8 times the theoretical performance ratio (14.7: 1), the air-fuel ratio is 26: 1 or more]. At this time, there is a problem that the exhaust gas is discharged including an excessive amount of harmful components.

However, in the conventional secondary air supply device, the situation is that the harmful gas components of the initial start-up as described above are not effectively reduced.

Accordingly, the present invention injects secondary air directly into the outlet of the exhaust gas discharged at a high temperature and high pressure in order to reduce the harmful components of the exhaust gas at the beginning of the start-up in the prior art, thereby unburned harmful gas in the exhaust gas. The components (HC, CO) and O ₂ of the secondary air cause a combustion reaction to reduce the exhaust gas.

1 is a block diagram showing a secondary air supply apparatus for a vehicle exhaust system according to the present invention.

* Explanation of symbols for main parts of the drawings

1: exhaust valve 2: exhaust port

4: air pump 5: control valve

6: check valve 7: air pipe

In order to realize the above object, this invention proposes the secondary air supply apparatus of the automobile exhaust system provided with the following means.

That is, this invention is an air pump in communication with an air cleaner and driven by battery power; A control valve for controlling the air pressurized by the air pump;

It characterized in that it is composed of an air pipe for injecting the pressurized air as above directly above the exhaust valve of the exhaust port.

In addition, the supply of the secondary air is limited to within 1 to 2 minutes at the start of the start, and in particular, reduces harmful components of the exhaust gas generated excessively during cold start.

According to this configuration, the secondary air supply device injects the secondary air to the high-temperature, high-pressure exhaust gas emitted from the combustion chamber during cold start, so that the unburned harmful components contained in the exhaust gas is O ₂ of the secondary air Reacts with spontaneously ignites. Therefore, the exhaust gas discharges the exhaust manifold in a state where harmful components are reduced, thereby further improving the exhaust gas purification efficiency of the catalyst.

Example

EMBODIMENT OF THE INVENTION Hereinafter, the preferred embodiment for implementing this invention is demonstrated in detail based on an accompanying drawing.

Fig. 1 is an overall configuration diagram showing a secondary air supply device for an automobile exhaust system according to this embodiment.

Reference numeral 1 in the drawing refers to the exhaust valve. The exhaust valve 1 is opened and closed by a valve opening and closing mechanism interlocked with the crankshaft and controls the discharge of the gas burned in the combustion chamber.

The exhaust gas discharged when the exhaust valve 1 is opened is discharged to the outside through the exhaust port 2, the exhaust manifold 3, the catalytic converter, and the silencer.

Here, the secondary air supply apparatus according to this embodiment, in particular, by injecting secondary air to the exhaust gas discharged from the combustion chamber in order to reduce the harmful components of the exhaust gas excessively discharged by the rich air-fuel ratio at the beginning of the start-up Induces spontaneous ignition of the exhaust gas.

In order to realize this, the secondary air supply apparatus according to this embodiment controls the air pump 4 driven by the battery power source B and the air pressurized by the air pump 4 so as to perform cold start 1 to 1. The control valve 5 which opens only for 2 minutes, and the air pipe 7 which injects the air supplied through the control valve 5 directly above the exhaust valve 1 of the exhaust port 2 are comprised.

Here, the control valve 5 may be configured as a solenoid valve or an on / off valve controlled by an electronic control unit (ECU) not shown. In addition, a check valve 6 is provided between the control valve 5 and the air pipe 7, and this check valve 6 prevents the exhaust gas from flowing back.

According to the configuration of this embodiment described above, the secondary air supply device injects secondary air into the exhaust gas discharged from the combustion chamber to the exhaust port 2 during cold start for 1 to 2 minutes. In this case, since the exhaust gas forms a rich air-fuel ratio for cold start, a large amount of harmful components are discharged in an unburned state, and the unburned gas is discharged in a state of high temperature and high pressure to discharge the secondary air. By combustion reaction with O ₂ , it ignites spontaneously.

Therefore, the exhaust gas is discharged to the catalytic converter through the exhaust manifold 3 with the harmful component reduced, and further improves the exhaust gas purification efficiency of the catalyst.

Through the embodiments described above, the secondary air supply of the vehicle exhaust system according to the present invention substantially solves the problems of the prior art.

That is, the present invention has the effect of spontaneously igniting the exhaust gas generated in a large amount in the initial stage of engine start, thereby reducing harmful components in an unburned state. This effect reduces the harmful components of the exhaust gas sent to the catalytic converter, thereby maximizing the efficiency of the catalyst and realizing the reduction of automobile exhaust gas discharged to the outside through the exhaust system.

On the other hand, the present invention is not limited to the above-described specific preferred embodiments, and any person having ordinary knowledge in the field of the present invention can make various changes without departing from the gist of the present invention claimed in the claims. Would be possible.

Claims (3)

An air pump driven by battery power, a control valve opened for only 1 to 2 minutes during cold start by controlling the air pressurized by the air pump, and the air supplied through the control valve is directly above the exhaust valve of the exhaust port. Secondary air supply apparatus of the vehicle exhaust system, characterized in that consisting of air pipes for injection into the room. The secondary air supply system of an automobile exhaust system according to claim 1, wherein the control valve is composed of a solenoid valve or an on / off valve controlled by an electronic control unit. The secondary air supply system of an automobile exhaust system according to claim 1, wherein a check valve is provided between the control valve and the air pipe.