JPS605767B2 - Combustion device of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention improves the combustion device itself of an internal combustion engine in order to reduce carbon monoxide and hydrocarbons contained in exhaust gas. In the maintained cylinder, a new secondary air supply is provided to cause oxygen to react with the combusted components, especially the unburnt components released from the quench area on the cylinder inner wall, before being discharged to the exhaust system. An object of the present invention is to provide a combustion device for an internal combustion engine that can reduce a considerable amount of carbon monoxide and hydrocarbons.

Hereinafter, the present invention will be specifically explained based on illustrated embodiments. In the figure, reference numeral 1 is a cylinder, and a piston 2 is slidably inserted into the cylinder. cylinder head 3
A combustion chamber 4 is formed inside, and an intake valve 5 is installed here.
An intake passage 5a communicates with the intake passage 5a, and an exhaust passage 6a communicates with the exhaust valve 6. Further, a spark plug (not shown) is located in the combustion chamber 4, and apart from this,
An air injection valve 7 is facing forward. Note that the exhaust passage 6a is
It is preferable that a heat insulating structure 8 be provided on the wall surface, and if necessary, a secondary air supply pipe (not shown) may be inserted therethrough.

In such a configuration, like a normal engine,
After passing through the suction stroke, compression stroke, and explosion stroke, the exhaust stroke begins, but earlier than the timing of the exhaust valve 6 in the exhaust stroke (from the explosion stroke to the exhaust stroke), the secondary air from the injection valve 7 enters the combustion chamber. Air is blown into cylinder 1.

This injection timing is, for example, about 20 crank angle degrees from the control valve timing, and if it is earlier, the injection pressure of the secondary air may be as low as about 5k9/block.

(Therefore, a relatively simple secondary air supply device is sufficient). As a result, during the exhaust stroke, the combustion components from the quench area of the cylinder wall surface that are scraped up and separated by the rise of the piston 2 are mixed with the high-temperature combustion gas and secondary air, so that they are rapidly oxidized in the combustion chamber 4. Performs subsequent combustion to oxidize unburned components and reduce carbon monoxide and hydrocarbons. FIG. 3 illustrates the secondary air injection timing according to the present invention in terms of the relationship between the combustion chamber pressure and the exhaust valve opening timing. The timing when the exhaust valve starts opening is later than the timing Qac.
Secondary air injection ends at (near bottom dead center).

That is, the hatched section in the figure indicates the secondary air injection period. In a normal engine, the end combustion gas in the quench region is exhausted together with the exhaust gas, so unless it is removed by after-treatment,
However, in the present invention, it is possible to perform oxidation treatment to a considerable extent through a secondary reaction within the engine, making it possible to omit an after-treatment device, or to reduce the size and simplicity of the after-treatment device.

In this embodiment, a heat insulating structure 8 is provided so that carbon monoxide and hydrocarbons in the exhaust gas can undergo self-reaction even within the exhaust passage 6a.

Also, consideration can be given to the secondary air supply. As described in detail above, this invention provides a secondary air injection valve facing into the combustion chamber of an engine, and from a time slightly earlier than the valve timing of the exhaust valve to approximately bottom dead center, the secondary air injection valve is The configuration is such that air is injected into the combustion chamber, and the unburned components that are scraped up and peeled off from the cylinder wall surface by the piston rise in the exhaust stroke are oxidized and cause secondary combustion. Since the unburned components are secondary combusted from the quench region, the exhaust temperature is sufficiently high, and there is no need to delay the ignition timing to raise the temperature of the reactor, as is the case with conventional methods, and good output and fuel efficiency can be maintained. .

In addition, since the secondary combustion can be completed in the combustion chamber and the subsequent exhaust passage relatively close to the combustion chamber, it may be cooled in the subsequent exhaust system, resulting in burnout of the exhaust pipe and heat damage to passersby. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are longitudinal sectional side views showing the beginning and middle of the exhaust stroke in an embodiment of the present invention, and FIG. It is a pressure indication diagram for comparison.

DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Piston, 3... Cylinder head, 4... Combustion chamber, 5... Intake valve, 5a.
...Intake passage, 6...Exhaust valve, 6a...
...Exhaust passage, 7...Air injection valve, 8...
...Insulated structure.

Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In an engine equipped with a secondary air injection valve facing into the combustion chamber, the injection valve injects secondary air into the combustion chamber from a time slightly earlier than the opening timing of the exhaust valve until approximately bottom dead center. An internal combustion engine characterized in that the engine is configured to inject air, and is configured to oxidize and cause secondary combustion of unburned components that are scraped up and peeled off from the cylinder wall surface by the rise of the piston in the exhaust stroke in the combustion chamber. Combustion device.