JPS6141939Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust gas purification device for an internal combustion engine.

Exhaust gas from a diesel engine contains fine particles such as an aggregate of carbide (mainly soot) and HC fine particles with an average particle size of about 3 μm. These fine particles are hereinafter referred to as particulate.

This patyculate is a harmful substance that pollutes the atmosphere if it is released into the atmosphere.
Conventionally, the exhaust gas has been collected using a filter attached to the exhaust pipe.

In FIG. 1, the part indicated by the reference numeral 1 is the filter that constitutes the exhaust gas purification device, and the exhaust pipe 2
It is installed in the middle of. Further, in the figure, numeral 3 is an exhaust manifold, numeral 4 is an exhaust valve, numeral 5 is an injection nozzle, numeral 6 is a swirl chamber, numeral 7 is a preheating plug, numeral 8 is a cylinder block, numeral 9 is a piston, and numeral 10 is a distribution The discharge holes of the type fuel injection pump are shown respectively.

Various types of filters 1 are used.

For example, heat-resistant materials such as ceramic honeycomb, ceramic-coated wire mesh, and glass fiber fabric may be used.

In the illustrated example, the combustion chamber is of a swirl chamber type, and the fuel injection pump is of a distribution type, but the present invention is not limited to the above types.

By the way, when the temperature reaches about 500°C or higher (around 350°C due to the presence of an oxidation catalyst), patyculate spontaneously combusts and becomes a harmless component. However, the exhaust gas temperature of a diesel engine is between 120℃ (idling) and 400℃ during steady driving, so re-combustion is impossible, and it is only during high-speed, high-load operation that the temperature of the exhaust gas near the combustion chamber in the exhaust gas passage increases. Reburning occurs at a temperature of 500℃ to 750℃.

Therefore, during steady driving, particulate matter is collected in the filter, which gradually accumulates and eventually becomes clogged, resulting in a reduction in engine output and deterioration in fuel efficiency.

The present invention was developed in view of the above-mentioned circumstances, and its purpose is to provide a means for re-burning the particulate and eliminating clogging of the filter even during normal driving. do.

The present invention will be explained in detail below.

The exhaust gas purification device according to the present invention includes a throttle valve arranged upstream of a filter, a fuel tank that communicates between an upstream position of the throttle valve and a space above the fuel tank, and a downstream position of the throttle valve and a lower position of the fuel tank. It is characterized by having a discharge passage.

FIG. 2 shows an embodiment of the present invention.

In the figure, a filter 100 is provided in the middle of an exhaust pipe 200. A throttle valve 300 is installed in the exhaust pipe 200 upstream of the filter 100.
A portion of the exhaust pipe 200 near and upstream of the exhaust pipe 200 is communicated with the upper space 400a of the auxiliary fuel tank 400 by a pressurizing pipe 500 serving as a fuel discharge passage.

In addition, the exhaust pipe 2 near and downstream of the throttle valve 300
An ejection opening 600 is formed in a part of 00, and the ejection opening 600 is connected to an ejection port of a three-way switching valve 700 through a pipe 800 as a fuel ejection passage. The suction port of the three-way switching valve 700 is communicated with the lower part of the fuel tank 400 through a pipe 1400 serving as a fuel discharge passage.

Note that here, the pipe 1400 is wound around the exhaust pipe 200 corresponding to the upstream side of the filter 100, and as described later, the pipe 1400
It is designed to heat the fuel flowing through the 0 to promote atomization. The other inlet of the three-way switching valve 700 is connected to the outlet of the air pump 1000 and the pipe 11.
It communicates via 00.

Next, an exhaust pipe 20 is provided upstream of the filter 100.
A pressure sensor 1200 is provided to detect a pressure inside the pipe of 0.

Now, when particulate matter is not sufficiently collected in the filter 100, the pressure detected by the pressure sensor 1200 also indicates a predetermined level or lower, and in such a state, the throttle valve 300 is in an open state. and the three-way switching valve 700 is switched to communicate the pipe 800 and the pipe 1100.
The compressed air from 000 is ejected from the ejection opening 600 to prevent the ejection opening 600 from being clogged with particulate matter.

Next, when the filter 100 is clogged by a predetermined amount or more due to particulate matter, the pressure detected by the pressure sensor 1200 also exceeds a predetermined level, and the throttle valve 300 is throttled based on the output of the pressure sensor 1200. controlled by.
Furthermore, the three-way switching valve 700 is also controlled so that the pipe 800 and the pipe 1400 communicate with each other.

As described above, when the exhaust gas passage of the exhaust pipe 200 is narrowed, the exhaust gas will naturally not come out sufficiently, and the amount of intake air will decrease accordingly.
As a result, the exhaust gas temperature increases.

However, temperature rise due to the above reasons alone is not enough.
It does not reach the point of re-burning the patty hydrate.

Therefore, in the present invention, as described above, the throttle valve 300 is further throttled. This results in
The pressure within the exhaust pipe upstream of the throttle valve 300 is increased. This increased pressure is then transmitted to the upper space 400a of the auxiliary fuel tank 400 through the pressurizing pipe 500, and pressurizes the fuel 1500. For this reason, the fuel 1500 flows through the pipe 1400 and further flows through the part of the pipe wound around the exhaust pipe 200, where it is heated and atomization is promoted.
It is ejected from the ejection opening 600.

Here, since the throttle valve 300 is not in a completely tightened state, a flow of exhaust gas exists in the exhaust pipe 200 downstream of the throttle valve 300, and the exhaust gas is ejected from the above-mentioned jet opening 600. The atomized fuel is ignited and combusted at the exhaust gas temperature which has increased by throttling the throttle valve 300, while maintaining the temperature associated with the combustion (this temperature is at least 500°C, the ignition temperature of the particulate). filter 10
reaches 0. Then, it is burned together with the particulate matter clogging the filter 100 to eliminate the clogging.

As described above, according to the present invention, it is possible to eliminate clogging of the particulate filter even during steady running, which is advantageous.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the exhaust gas exhaust system of a diesel engine, and FIG. 2 is a piping system diagram of an exhaust gas purification device as an embodiment of the present invention. 300...throttle valve, 400...auxiliary fuel tank, 500...pressurizing pipe (as a fuel discharge passage), 800, 1400...pipe (as a fuel discharge passage).

Claims (1)

[Scope of Claim for Utility Model Registration] In an exhaust gas purification device in which a filter is attached to a part of the exhaust pipe and particulates contained in the exhaust gas are collected by the filter, the exhaust gas purification device is disposed upstream of the filter. An exhaust gas purification device for an internal combustion engine, comprising a throttle valve, a fuel discharge passage communicating between an upstream position of the throttle valve and a space above a fuel tank, and a downstream position of the throttle valve and a lower position of the fuel tank.