JPS6332892Y2 - - Google Patents

Description

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

BACKGROUND ART In order to collect particulate matter contained in the exhaust gas of a diesel engine, an idea is being developed to arrange a trap means, ie, a filter means, in the middle of an exhaust pipe. The collected particulate gradually accumulates on the trap means, and the gas passing ability of the trap means gradually decreases. For this reason, it is preferable to regenerate the trap means by burning particulate once it has accumulated to some extent. During this combustion process, the particulate carbon component becomes carbon monoxide, so an oxidation catalyst can be placed for the purpose of carbon monoxide purification. It has been conventionally believed that introduction of secondary air is necessary to activate the oxidation catalyst.

Purpose of the invention The purpose of the present invention is to provide an exhaust gas purification apparatus having the above-mentioned configuration, in which the oxidation catalyst can be activated without using a secondary air introduction device such as an air pump.

Structure of the invention The exhaust gas purification device for an internal combustion engine according to the invention has the following features:
A part of the exhaust pipe is separated into two passages by a partition wall extending in the gas flow direction, and one passage is provided with a trap means and a regeneration means for burning particulate accumulated on the trap means and regenerating the trap means. and an oxidation catalyst are disposed downstream of the trap means, and a valve device is disposed in the other passage for opening this passage when the trap means is regenerated, and a valve device is disposed in the other passage to open this passage when the trap means is regenerated. It is characterized in that a passageway is formed which communicates between the trapping means of the passageway and the oxidation catalyst.

Embodiments Examples of the present invention will be described below with reference to the drawings.

The figure shows an embodiment of the present invention, in which 1 shows an exhaust pipe connected to an exhaust manifold of a diesel engine. A partition wall 2 is inserted into a part of the exhaust pipe 1. The partition wall 2 extends in the gas flow direction indicated by arrow A and separates the exhaust pipe 1 in this section into two passages 3, 4. Above and below the partition walls 3 and 4, both passages 3 and 4 merge.

A known trapping means 5 is arranged in the first passage 3, through which particulate matter in the exhaust gas is collected. An electric heater 6 is installed upstream and adjacent to the trapping means 5. When a certain amount of particulate matter collected in the trapping means accumulates, the heater is energized to burn the deposited particulate matter and regenerate the trapping means 5. It is becoming possible to do so. An oxidation catalyst 7 is disposed downstream of the trap means 5 at a position that does not protrude from the lower end of the partition wall 2, and is capable of converting harmful carbon monoxide generated during combustion for regenerating the trap means into carbon dioxide. It's becoming like that.

A control valve 8 is arranged in the second passage 4, which normally closes the second passage 4 and opens the second passage 4 only when the electric heater 6 is energized for trap means regeneration. driven by Although an actuator for this is not shown, this is a known technique and can be easily implemented by those skilled in the art.

One pipe 9 is provided passing through the partition wall 2. A pipe 9 is welded to the partition wall 2 and has one end opened into the second passage 4 to receive the dynamic pressure of the gas flow, and the other end opened into the first passage 3 between the trap means 5 and the oxidation catalyst 7. The pipe 9 has a hole 10 that opens to the oxidation catalyst 7 side. As mentioned above, when the heater 6 is energized to regenerate the trap means, the control valve 8 is open, so most of the exhaust gas flows through the second passage 4, and this gas passes through the pipe 10. It is introduced upstream of the oxidation catalyst 7.
In the case of diesel engines, the air-fuel ratio is set high, so even the exhaust gas contains a large amount of oxygen. Then, the oxygen component in the gas introduced through the pipe 9 is transferred to the electric heater 6
This is clearly higher than the oxygen content in the gas that has passed through the trap means 5. Therefore, the exhaust gas introduced from the second passage 4 to the first passage 3 through the partition wall 2 has the same effect on the oxidation catalyst 7 as if secondary air was introduced, and the oxidation catalyst 7 action will be activated.

It is clear that instead of the pipe 9, a through hole may be made in the partition wall 2 to introduce the exhaust gas, or other guide means may be provided. Further, in this embodiment, the partition wall 2 separates the single exhaust pipe 1 into two passages, but the present invention is also applicable when the second passage 4 is formed by, for example, a bypass pipe. In this case, the term septum should be interpreted as the wall of the bypass pipe.

Effects As explained above, according to the present invention, oxygen can be introduced with a very simple configuration to activate the oxidation catalyst. Therefore, harmful components in the exhaust gas are further purified.

[Brief explanation of drawings]

The figure is a sectional view of an embodiment of the exhaust gas purification device for an internal combustion engine according to the present invention. 1... Exhaust pipe, 2... Partition wall, 3... First passage,
4... Second passage, 5... Trap means, 6... Heater, 7... Oxidation catalyst, 8... Control valve, 9...
pipe.

Claims (1)

[Scope of utility model registration request] A part of the exhaust pipe is separated into two passages by a partition wall extending in the gas flow direction, and one passage is provided with a trap means and a regeneration means for burning particulate accumulated on the trap means and regenerating the trap means. and an oxidation catalyst are disposed on the downstream side of the trap means, and a valve device is disposed in the other passage for opening the passage when the trap means is regenerated. An exhaust gas purification device for an internal combustion engine, comprising a passage communicating between a trap means of the passage and an oxidation catalyst.