JPS593133Y2 - Secondary air supply device for multi-cylinder internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for supplying secondary air to a multi-cylinder internal combustion engine for the purpose of purifying its exhaust gas.

In general, to supply air-fuel mixture to each cylinder in a multi-cylinder internal combustion engine, the air-fuel mixture generated by one or more carburetors is
This is carried out via intake branch pipes that branch from the intake pipe assembly to which the carburetor is attached, but the arrangement shape of the intake branch pipes, the opening/closing direction of the slot valve in the carburetor, the position of the venturi, and the position of the main nozzle Due to the opening position, etc., the air-fuel mixture is biased, and the intake air-fuel mixture in a particular cylinder is always richer than in other cylinders. Compared to this, more toxic gases such as HC and CO are generated, and HC and CO in the exhaust gas from the entire engine are generated.
In some cases, the concentration of exhaust gas has increased, and the purification ability of the exhaust gas purification device has been reduced due to the high thermal load caused by the concentrated exhaust gas flow from the cylinders.

In a multi-cylinder internal combustion engine, the present invention supplies secondary air to the vicinity of the exhaust valve opening of the exhaust port of a specific cylinder where the intake air-fuel mixture concentration is high due to the structure of the intake side as described above. It facilitates oxidation reactions with HC and CO in high-temperature gases discharged from the engine, and also promotes combustion or oxidation in exhaust purification devices such as thermal reactors and catalytic converters that require secondary air, reducing emissions from the entire engine. C to be done
This makes it possible to reliably purify toxic gases such as 09HC.

Next, the present invention will be explained according to the drawings. In the drawing, 1 is an in-line four-cylinder internal combustion engine consisting of a first cylinder C1, a second cylinder C2, a third cylinder C3, and a fourth cylinder C4. Exhaust ports of each cylinder in the attached cylinder head 3) Bl, B2.

B3. An exhaust purification device 5 such as a thermal reactor or a catalytic converter is connected to B4 via a connecting pipe 4.4.4.4, and it branches from a gathering part 11 of the intake pipe 6 to which a carburetor (not shown) is attached. The branch pipe is further branched into branch pipes, and these branch pipes are connected to the intake ports A1. A2. A3. A4
It will be connected to.

In this four-cylinder internal combustion engine, certain cylinders have a richer air-fuel mixture than other cylinders, for example, the intake order (ignition order) is 1st cylinder C1 - 3rd cylinder q 4th cylinder C4 - 2nd cylinder C2. The first cylinder C1 and the fourth cylinder C4 in the case of
Exhaust port B1. Secondary air supply ports 8, 8 are opened in the vicinity of the opening part of the exhaust valve 7 in B4, and the secondary air supply ports 8, 8 are connected to the supply ports 8, 8 from outside the cylinder head 3 via supply pipes 9, 9 and the control device 10. Bt to exhaust secondary air.

It is configured to be supplied into B4.

This supply of secondary air may be performed by utilizing exhaust characteristics such as exhaust pulsation in the cylinder to which the secondary air is to be supplied, or may be performed using an air pump or the like.

In this way, the intake order (ignition order) is C1-C3-q-C
In the case of the second order, when intake is into the fourth cylinder following the third cylinder, or the first cylinder following the second cylinder, the air-fuel mixture from the gathering part of the intake pipe to the inside of both branch pipes and the inner wall of the pipe are The adhering liquid fuel is taken into the 4th cylinder or the 1st cylinder with the flow inertia given to it when it was taken into the 3rd cylinder or the 2nd cylinder, so the intake air mixture to the 4th cylinder and the 1st cylinder becomes concentrated, and as a result, the HC and CO concentrations in the gas exhausted after combustion in the first and fourth cylinders become high, but according to the present invention, the opening of the exhaust valve 7 of the exhaust port of these cylinders increases. Since secondary air is supplied nearby, the high temperature exhaust gas and secondary air can be mixed in advance in the exhaust port, reducing CO, H
The oxidation reaction of C can be promoted, and as a result, the state of the exhaust gas components from the exhaust port of each cylinder becomes approximately equal, and the exhaust gas components etc. from the exhaust port of each cylinder become approximately equal, and are transferred into the exhaust gas purification device 5 such as the following thermal reactor 5 and catalytic converter. This allows the heat load to be distributed evenly within the purifier without placing a high heat load on only the parts that make up the purifier, thereby making it possible to reliably reduce CO and HC emitted from the entire engine, thereby preventing air pollution. It has an effect.

In the above embodiment, the case where the air-fuel mixture in a specific cylinder becomes richer than in other cylinders due to the arrangement and shape of the intake manifold was explained. It goes without saying that the configuration of the present invention can also be applied to cases where the concentration of the intake air mixture to a specific cylinder becomes rich due to the uneven flow of the air-fuel mixture.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a plan view of an in-line four-cylinder internal combustion engine, and FIG. 2 is a partially omitted sectional view taken along the line II--II in FIG. 1... Internal combustion engine, C1, C2, C3, C4...
...Cylinder, B,, B2. B3. B4...
・・Exhaust port, A15 A2 t A3 tA4・・
...Intake port, 6...Intake pipe, 5...
... Exhaust purification device, 4.4.4.4 ... Exhaust connecting pipe, 7 ... Exhaust valve, 8 ... Secondary air supply hole, 9 ... ... Supply pipe, 10 ... Control device.

Claims (1)

[Scope of utility model registration request] In multi-cylinder internal combustion engines that supply air-fuel mixture from the carburetor to each cylinder via the intake pipe, secondary air is supplied near the exhaust valve opening at the exhaust port of the cylinder where the air-fuel mixture is richer than that of other cylinders. A secondary air supply device for a multi-cylinder internal combustion engine.