JPS6332891Y2 - - 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.

Purpose of the invention It is well known that oxidation catalysts are suitable for purifying carbon monoxide. However, since the time required to purify carbon monoxide through the above-mentioned combustion process is very short and the hydrocarbon components have already been collected by the trap means, it is not necessary to constantly pass the exhaust gas through the oxidation catalyst; Such a configuration would conversely accelerate the deterioration of the oxidation catalyst. An object of the present invention is to provide an exhaust gas purification device that can improve the purification efficiency of harmful gas components in the exhaust gas of an internal combustion engine and can reduce deterioration of an oxidation catalyst.

Structure of the invention The exhaust gas purification device for an internal combustion engine according to the invention has the following features:
A trap means is provided in the middle of the exhaust pipe, and a regeneration means is disposed in the trap means for burning particulate when it accumulates and regenerating the trap means.Furthermore, an oxidation catalyst is disposed downstream of the trap means. In the exhaust gas purification device for an internal combustion engine, the exhaust pipe is branched between a trap means and an oxidation catalyst, the oxidation catalyst is disposed in one of the branched pipes, and the regeneration means is disposed in one of the branched pipes. is characterized in that a control valve is arranged that allows exhaust gas to pass only when the system is operating.

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

FIG. 1 shows a first embodiment of the present invention, in which 1 indicates an exhaust pipe connected to an exhaust manifold of a diesel engine. The exhaust pipes 1 are connected to each other by a partition wall 2.
It is divided into 3 and 4 passages. A conventional trap means 5 is arranged in the first passage 3, and an electric heater 6 is arranged upstream and adjacent thereto. On the other hand, a control valve 7 is arranged in the second passage 4. The configuration up to this point is well known, and the electric heater 6
Although a current supply device and an actuator for the control valve 7 are not shown, when the trap means 5 is to be regenerated, the electric heater 6 is energized, and the control valve 7 is driven based on the electric signal at this time. That is,
When the electric heater 6 is energized, the control valve 7
is brought into the open position as shown in FIG. 1, and the control valve 7 is otherwise closed. This increases the particulate collection ability and promotes the combustion process of the particulate accumulated in the trap means 5.

A U-shaped bypass pipe 8 having an inlet above the downstream end of the partition wall 2 is connected to the first passage 3, and an outlet thereof is connected to the first passage 3 again downstream of the lower end of the partition wall 2.
(which joins the second passage). A well-known oxidation catalyst 9 is arranged in the bypass pipe 8, and a control valve 10 is arranged at the inlet of the bypass pipe 8. The control valve 10 is capable of selectively switching the flow of exhaust gas in the first passage 3 to the bypass pipe 8 or to direct the first passage directly in the 3' direction.

Although the actuator of the control valve 10 is not shown, it may be mechanically interlocked with the first control valve 7 or may be electrically driven by an energization signal to the electric heater 6. The control valve 10 is
In order to regenerate the trap means 5, the first passage 3 and the bypass pipe 8 are brought into communication when the electric heater 6 is energized, and the bypass pipe 8 is brought into communication at other times.
The first passage 3 is directly communicated with its downstream side 3' by closing the first passage 3. 11 is a well-known secondary air supply device for supplying air to the oxidation catalyst 9.

With such a configuration, the particulate matter in the exhaust gas is collected by the trap means 5, and the collected particulate matter is combusted when the trap means 5 is regenerated. Carbon monoxide may be generated during combustion regeneration, but since the downstream side of the trap means is connected to the oxidation catalyst 9, harmful carbon monoxide is oxidized to carbon dioxide.
Exhaust gas does not pass through the oxidation catalyst except during combustion regeneration.
Therefore, there is almost no deterioration of the oxidation catalyst.

FIG. 2 shows a second embodiment of the invention, in which there is no bulkhead 2 and therefore the second passage 4 and the control valve 7 disposed therein, and the trap means 5 traverses the entire exhaust pipe 1. This embodiment differs from the embodiment shown in FIG. 1 in terms of its arrangement. The rest of the structure is the same as that of the embodiment shown in FIG. 1, and its operation is obvious, so a description thereof will be omitted.

FIG. 3 shows a third embodiment of the present invention, in which the inlet of the bypass pipe 8 is connected to the first passage 3 and the second passage.
It is connected to the exhaust pipe 1 at a point where the passage 4 joins with the lower end of the partition wall 2. The rest of the configuration is the same as the embodiment shown in FIG. 1, but when the exhaust gas is passed through the oxidation catalyst 9, the exhaust gas passing through the second passage 4 is also passed through the oxidation catalyst 9 at the same time. Therefore, the secondary air supply device 11 in FIG. 1 is omitted. This is possible because the air-fuel ratio of diesel engines is set higher and the exhaust gas contains more oxygen. The operation is similar to the above embodiment.

Effects of the Invention As explained above, according to the present invention, the purification efficiency of harmful gas components in exhaust gas is increased and deterioration of the oxidation catalyst is reduced.

[Brief explanation of drawings]

Figure 1 shows the first example of the exhaust gas purification device according to the present invention.
FIG. 2 is a sectional view of the second embodiment, and FIG. 3 is a sectional view of the third embodiment. 1... Exhaust pipe, 5... Trap means, 6... Heater, 8... Bypass pipe, 9... Oxidation catalyst, 1
0...Control valve.

Claims (1)

[Scope of utility model registration request] A trap means is provided in the middle of the exhaust pipe, and a regeneration means is disposed in the trap means for burning particulate when it accumulates and regenerating the trap means.Furthermore, an oxidation catalyst is disposed downstream of the trap means. In the exhaust gas purification device for an internal combustion engine, the exhaust pipe is branched between a trap means and an oxidation catalyst, the oxidation catalyst is disposed in one of the branched pipes, and the regeneration means is disposed in one of the branched pipes. 1. An exhaust gas purification device for an internal combustion engine, characterized in that a control valve is disposed that allows exhaust gas to pass only when the control valve is operating.