JP2549482Y2 - Exhaust gas treatment device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment apparatus for purifying exhaust gas from a diesel engine.

[0002]

2. Description of the Related Art In general, for example, exhaust gas from a diesel engine contains particulates mainly composed of carbon, nitrogen oxides (NO _x ), carbon monoxide (C).
O) and components such as hydrocarbons (HC). And especially in the exhaust gas from the diesel engine, N
Due to the high content of O _x , a flow-through type catalyst having a built-in reduction catalyst such as a zeolite catalyst for mainly decomposing this NO _x component into N ₂ and O ₂ in the middle of the exhaust gas passage of the diesel engine 2. Description of the Related Art An exhaust gas treatment device provided with a converter has been conventionally developed.

In addition, a particulate trap for collecting particulates in exhaust gas is provided in the middle of an exhaust gas passage from a diesel engine, and the particulate trap is used to collect the particulates to purify the exhaust gas. Exhaust gas treatment devices of the type have also been developed in the past. In this case, a heater for regenerating the particulate trap is disposed upstream of the particulate trap in a cylindrical container that houses the particulate trap. When the amount of trapped particulates in the particulate trap increases, the particulates trapped in the particulate trap are burned by this heater, so that the trapped quantity of particulates in the particulate trap becomes a limit value. Regeneration processing of the particulate trap is performed to prevent the above increase and prevent the flow path resistance in the exhaust gas passage from increasing.

[0004]

[Devised Problems to be Solved] During engine operation in the exhaust gas passage type exhaust gas treatment apparatus which is interposed a catalytic converter in the flow-through for NO _x components purifying the intermediate portion of the diesel engine, the exhaust gas There is a possibility that a number of fine pores for exhaust gas distribution formed in the catalyst body may be clogged by the particulates.
For this reason, the flow resistance of the exhaust gas in the exhaust gas passage increases, and the pressure loss increases significantly. Therefore, there is a problem in improving the engine output.

Further, in a flow-through type catalytic converter using a zeolite catalyst, there is a problem that the O ₂ component decomposed by the purifying action of the zeolite catalyst is hard to be discharged from the inside of the catalyst to the outside. For this reason, the zeolite catalyst is gradually poisoned by the O ₂ component, and an oxidizing atmosphere is easily formed. Therefore, there has been a problem that the purification ability of the zeolite catalyst gradually decreases with time.

[0006] Further, sulfur dioxide (SO ₂ ) is mixed in the exhaust gas from the diesel engine because the content of the sulfur component is relatively large in the fuel of the diesel engine. When the exhaust gas mixed with the SO ₂ component is introduced into a flow-through type catalytic converter incorporating a reduction catalyst such as a zeolite catalyst, the SO ₂ component adheres to the zeolite catalyst, and the zeolite catalyst is removed. since degradation is poisoned, purification function of the zeolite catalyst original of the NO _x components is impaired, there is a problem that the purification ability of the exhaust gas is reduced.

Further, it is the type of exhaust gas treatment device by trapping particulates purifying exhaust gas in the exhaust gas from a diesel engine by particulate trap for purifying efficiently NO _x components in the exhaust gas There was a problem that could not be done.

This invention has been made in view of the above circumstances, and it is possible to efficiently purify the particulates in the exhaust gas during the operation of the engine and to perform a stable regeneration process of the particulate trap. ,
In addition, it is another object of the present invention to provide an exhaust gas treatment apparatus capable of controlling a regeneration burner so as not to exceed the heat resistant temperature of the catalyst and improving the durability of the catalyst.

[0009]

According to the present invention, a particulate trap provided in an exhaust gas passage of an internal combustion engine for collecting particulates in exhaust gas is arranged in series downstream of the particulate trap. An exhaust gas comprising: a catalyst for purifying nitrogen oxides provided; and a regeneration burner disposed upstream of the particulate trap and burning and regenerating the particulates collected in the particulate trap. A gas processing apparatus, comprising: a bypass passage that communicates an upstream portion of the particulate trap in the exhaust gas passage with a downstream portion of the catalyst to bypass the particulate trap and the catalyst; and a particulate passage in the exhaust gas passage. Switching means for switching between communication with the curated trap and communication with the bypass passage; A temperature sensor for detecting a temperature of,
Combustion stop means for stopping the burning of the particulates by the regeneration burner when the temperature of the catalyst detected by the temperature sensor reaches a preset upper limit temperature.

[0010]

In the above construction, the switching between the communication of the exhaust gas passage to the particulate trap and the communication to the bypass passage can be made by the switching means during the operation of the engine.
By switching the exhaust gas passage to the bypass passage during the regeneration of the particulate trap, the exhaust gas is prevented from flowing into the particulate trap during the regeneration process, and the particulate matter due to the inflow of the exhaust gas is prevented. Prevent changes in the regeneration temperature of the curated trap. Furthermore, when the temperature of the catalyst reaches the upper limit,
By stopping the regeneration processing operation by the regeneration burner by the combustion stopping means, the regeneration burner can be controlled so as not to exceed the heat resistant temperature of the catalyst.

[0011]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a main configuration of an exhaust gas treatment device for a diesel engine, and FIG. 2 shows a schematic configuration of an exhaust system of the diesel engine.

In FIG. 2, reference numeral 1 denotes an engine body of a diesel engine, and reference numeral 2 denotes an exhaust gas passage of the engine body 1. The exhaust gas passage 2 is provided with an exhaust gas processing unit 3 of the exhaust gas processing apparatus on the upstream side and a muffler 4 on the downstream side.

The exhaust gas processing unit 3 is provided with, for example, a cylindrical container 5 made of stainless steel. In the cylindrical container 5, a particulate trap 6 for collecting particulates in the exhaust gas is provided at a substantially central portion in the flow direction of the exhaust gas, and a flow-through type zeolite catalyst or the like is provided downstream of the particulate trap 6. The reduction catalyst 7 for purifying nitrogen oxides is disposed in series.

The main body 6a of the particulate trap 6 is formed in a substantially cylindrical shape by a porous body such as ceramics. Further, an elastic support member such as a wire mesh is provided between the particulate trap main body 6a and the cylindrical container 5. The particulate trap body 6a is elastically supported by the cylindrical container 5 via the elastic support member.

The particulate trap body 6a
As shown in FIG. 3, a large number of pores 8 are formed in parallel in the axial direction and serve as exhaust gas passages. A plurality of these pores 8 are arranged in the vertical and horizontal directions substantially in a matrix in a circular cross section which is a cross section of the particulate trap body 6a.

Furthermore, the particulate trap body 6
The opening ends of a large number of pores 8 arranged vertically and horizontally in a matrix on the upstream end surface of the block a are closed by upstream closing members 9 every other in the vertical and horizontal directions as shown in FIG. Each of the pores 8 closed by the upstream closing member 9 forms an upstream closing passage 8a.

The particulate trap body 6a
Open ends of the pores 8 not closed by the upstream closing member 9 are closed by a downstream closing member 10 on the downstream end surface of the small holes 8. Each of the pores 8 closed by the downstream closing member 10 forms a downstream blocking passage 8b.

The exhaust gas which has flowed into the cylindrical container 5 is supplied to the downstream closed passages 8b as shown by arrows in FIG.
After being introduced into the inside, the air passes through the porous partition walls 6b between the downstream closed passages 8b and the upstream closed passages 8a and flows into the upstream closed passages 8a. When the exhaust gas passes through the porous partition wall 6b between the passage 8b and the upstream closing passage 8a, the particulates in the exhaust gas are left in a state of being attached to the partition wall 6b, and the particulates are collected. It has become so.

In the main body 7a of the catalyst 7, a large number of pores are formed substantially in parallel with each other along the axial direction to serve as exhaust gas passages. The catalyst body 7a is formed of a substantially honeycomb-shaped structure.

Further, in the cylindrical container 5 of the exhaust gas treatment unit 3, a regeneration burner 12 for burning and regenerating the particulates collected in the particulate trap 6 is provided upstream of the particulate trap 6. It is arranged.

The burner 12 has a first fuel supply pipe 13
Are connected, one end of a supply pipe for primary air for combustion and a supply pipe for secondary air for combustion (not shown) are connected to each other, and an ignition plug is attached.
In this case, the other end of the first fuel supply pipe 13 is connected to a burner opening / closing valve 14 and a fuel pump 15 formed by an electromagnetic valve.
Through a fuel tank 16 for a hydrocarbon fuel such as light oil or alcohol.

The fuel tank 16 may be provided separately from the fuel tank of the engine body 1. For example, when light oil is used as the hydrocarbon fuel, the engine body 1
It may be shared with other fuel tanks.

Further, between the particulate trap 6 and the catalyst 7 in the exhaust gas treatment unit 3, a hydrocarbon supply means 17 for supplying a hydrocarbon for recovering the function of the catalyst 7 is provided.
Is provided. The hydrocarbon supply means 17 is provided with an injection nozzle 18 inserted into the cylindrical container 5. One end of a second fuel supply pipe 19 is connected to the injection nozzle 18. The other end of the second fuel supply pipe 19 is connected between the burner on / off valve 14 and the fuel pump 15 in the first fuel supply pipe 13 via an injection on / off valve 20 formed by an electromagnetic valve. I have.

On the other hand, a bypass passage 21 is connected to the exhaust gas passage 2 in parallel with the exhaust gas processing unit 3 as shown in FIG. A first opening / closing valve (switching means) 22 for opening / closing the exhaust gas processing unit 3 is provided at an inlet of the exhaust gas processing unit 3, and a second opening / closing operation for the bypass passage 21 is provided at an inlet of the bypass passage 21. On-off valves (switching means) 23 are respectively attached. The first on-off valve 22 and the second on-off valve 23 are connected to the controller 24 shown in FIG. 5 together with the burner on-off valve 14 and the injection on-off valve 20.

The controller 24 has, for example, a first pressure sensor 25 for detecting a pressure state on the upstream side of the particulate trap 6 in the cylindrical container 5, and a pressure on the downstream side of the particulate trap 6 in the cylindrical container 5. the second pressure sensor 26 for detecting the state, temperature sensor 2 for detecting the temperature of the NO _x concentration sensor 27 and a catalytic body 7a for detecting the concentration of NO _x in the exhaust gas on the upstream side of the catalyst 7
8 are connected respectively.

During operation of the engine body 1 of the diesel engine, a differential pressure between the upstream and downstream of the particulate trap 6 is detected by the controller 24 based on detection signals from the first and second pressure sensors 25 and 26. The first on-off valve 22 and the second
The opening / closing operation of the on-off valve 23 and the on / off operation of the burner 12 and the fuel pump 15 are controlled, respectively, to collect the particulates in the exhaust gas by the particulate trap 6 and to collect the particulates in the particulate trap 6. The regeneration operation of the particulate trap 6 in which the particulates are burned by the burner 12 is controlled.

Furthermore, concentration of NO _x in the exhaust gas on the upstream side of the catalyst 7 by concentration of NO _x controller 24 based on the detection signal from the sensor 27 is detected, opening and closing the injection on the basis of the detection data of the concentration of NO _x The opening and closing operation of the valve 20 is controlled, and the injection nozzle 18 of the hydrocarbon supply means 17 is controlled.
The supply of hydrocarbons from the catalyst to the catalyst 7 is controlled.

Next, the operation of the above configuration will be described.

First, during operation of the engine body 1 of the diesel engine, the first on-off valve 22 is normally in the open state,
The open / close valve 23 is held in a closed state. Therefore, in this state, the bypass passage 21 is held in a closed state, so that the exhaust gas from the engine main body 1 passes through the exhaust gas passage 2 and the cylindrical container 5 of the exhaust gas processing unit 3.
Introduced within.

Further, the exhaust gas introduced into the cylindrical container 5 flows into the downstream closed passages 8b of the particulate trap 6 as shown by arrows in FIG. The exhaust gas that has flowed into the downstream closed passages 8b continues to flow into the downstream closed passages 8b and the upstream closed passages 8a.
Through the porous partition wall 6b between the upstream side closed passage 8
flows into a ... At this time, when the exhaust gas passes through the porous partition walls 6b between the downstream closed passages 8b and the upstream closed passages 8a, the particulates in the exhaust gas are left attached to the partition walls 6b, Particulates in the exhaust gas are collected in the particulate trap 6.

The exhaust gas flowing into the upstream side closed passages 8a of the particulate trap 6 subsequently flows into the main body 7a of the catalyst 7. And this catalyst body 7a
The NO _x component in the exhaust gas is decomposed into N ₂ and O ₂ and purified when flowing through the pores.

Further, the particulates are collected by the particulate trap 6 in the exhaust gas processing unit 3, and the exhaust gas from which the NO _x component has been purified by the catalyst 7 is discharged outside through the muffler 4.

During operation of the engine body 1, the controller 24 controls the particulate trap 6 based on detection signals from the first and second pressure sensors 25 and 26.
On, along with the pressure difference between the downstream (pressure loss) PS is detected, concentration of NO _x in the exhaust gas on the upstream side of the catalyst 7 by concentration of NO _x controller 24 based on the detection signal from the sensor 27 is detected You. Then, the amount of particulate trapped by the particulate trap 6 is detected based on the differential pressure PS between the upstream and downstream of the particulate trap 6, and the regeneration processing conditions of the particulate trap 6 are determined. In addition, the particulate trap 6
The upper limit value of the amount of trapped particulates, that is, the upper limit value of the differential pressure PS is set as a predetermined set pressure PS _{0 in} advance and stored in the controller 24.

The controller 24 determines the regeneration processing conditions of the particulate trap 6 based on whether or not the detected differential pressure PS is higher than the set pressure PS ₀ .
Here, when a state where the detected differential pressure PS is smaller than the set pressure PS ₀ is detected, it is determined that the regeneration of the particulate trap 6 is not required, and the first opening / closing valve 22 is in the open state and the second opening / closing state. The valve 23 is held in a closed state, the burner 12 and the fuel pump 15 are turned off, and the burner opening / closing valve 14 is held in a closed state, and the normal operation state is held. Therefore, in this state, the particulate trap in the normal exhaust gas is collected by the particulate trap 6 described above.

When a state where the detected differential pressure PS is equal to or higher than the set pressure PS ₀ is detected, the amount of the particulate trapped in the particulate trap 6 during operation of the engine body 1 increases, and the particulate trap is increased. 6 is determined to be in a state in which the flow resistance of the exhaust gas passing through the porous partition walls 6b from the downstream closed passages 8b and flowing into the upstream closed passages 8a increases and the regeneration condition of the particulate trap 6 is satisfied. Then, the regeneration process of the particulate trap 6 is performed, for example, for an appropriate preset time.

During the regeneration operation of the particulate trap 6, the controller 24 controls the first on-off valve 2
2 is switched to a closed state, and the second on-off valve 23 is switched to an open state, whereby the bypass passage 21 is opened. Therefore, in this state, most of the exhaust gas from the engine body 1 flows from the exhaust gas passage 2 into the bypass passage 21. Further, the burner 12 and the fuel pump 15 are turned on,
The burner on-off valve 14 is switched to the open state, and the operation of the burner 12 is started.

When the operation of the burner 12 is started, high-temperature combustion gas generated from the burner 12 is blown to the particulate trap 6, and the particulate attached to the particulate trap main body 6a is cauterized. You. And the particulate trap body 6
The operation of the burner 12 is stopped when all the particulates adhering to a are cauterized.

Further, the heat generated during the regeneration processing operation of the particulate trap 6 causes the main body 7a of the catalyst 7 to generate S
It is heated to a regeneration temperature of, for example, about 600 to 700 ° C. at which the O ₂ component can be removed. Therefore, the catalyst main body 7a is heated to the regeneration temperature or higher by the high-temperature combustion gas. When the catalyst body 7a is heated to a temperature equal to or higher than the regeneration temperature as described above, the heat causes the SO adhered to the catalyst body 7a to adhere.
_{Since the two} components are removed and the ability of the catalyst 7 to purify the NO _x component is restored to the original state, it is possible to prevent a reduction in the NO _x component purifying function of the catalyst body 7a.

It should be noted, the operation of the burner 12 by the controller 24 when the state of the catalyst body 7a based on the detection signal from the temperature sensor 28 during heating of the catalyst body 7a is raised to the upper limit temperature setting value T ₀ has been detected Is immediately switched to the stop state, and the reproduction processing operation of the particulate trap 6 is stopped. Therefore, it is possible to prevent the catalyst body 7a is overheated above the upper limit temperature setting value T _0.

At the end of the regenerating operation of the particulate trap 6, the burner 12, the fuel pump 15 are switched off, the burner on-off valve 14 is switched to the closed state, and the first on-off valve 22 is opened. State, second
The on-off valve 23 is switched to the closed state. Therefore, in this state, the bypass passage 21 is closed, so that most of the exhaust gas from the engine body 1 is introduced from the exhaust gas passage 2 into the cylindrical container 5 of the exhaust gas processing unit 3 in the normal operation state. Then, the operation of collecting particulates in the exhaust gas by the particulate trap 6 is resumed.

Further, during operation of the engine body 1, NO _x
Injection on-off valve is lower than the set concentration concentration of NO _x in the exhaust gas on the upstream side of the catalyst 7 is detected by the controller 24 based on the detection signal from the density sensor 27 is stored in advance in the controller 24 20 is held in a closed state, and the fuel pump 15 is held in an off state.

[0043] Further, with the injection on-off valve 20 is switched operated in the opening state when the state where the detection value of the NO _x concentration in the exhaust gas rises above setting density is detected,
The fuel pump 15 is simultaneously switched on.
In this case, when the fuel pump 15 is driven, hydrocarbon fuel is supplied from the fuel tank 16 to the injection nozzle 18 side, and is sprayed from the injection nozzle 18 to the catalyst main body 7a in a mist. Therefore, the O ₂ component adhering to the catalyst body 7a causes a chemical reaction of H ₂ O + CO ₂ by the supply of HC contained in the fuel. Therefore, O ₂ components are removed adhering to the catalyst body 7a, the catalyst body 7a is so returned to its original state, removing function of the NO _x components by the catalyst body 7a is recovered.

Therefore, in the above configuration, during operation of the engine body 1, particulates in the exhaust gas are collected by the particulate trap 6 on the upstream side in the exhaust gas processing unit 3, and the particulates are collected. since the NO _x components in the exhaust gas passing through the trap 6 so as to purify the downstream side of the catalyst 7 of the exhaust gas treatment unit 3, at the time of driving the engine body 1 at the same time the particulates and NO _x components in the exhaust gas It can be purified efficiently. In this case, the exhaust gas from which the particulates have been removed by the upstream particulate trap 6 in the exhaust gas treatment unit 3 is guided to the downstream catalyst 7, so that the particulates in the exhaust gas cause the inside of the catalyst body 7a. Can prevent clogging of a large number of fine holes for exhaust gas distribution formed in the above. Therefore, it is possible to prevent an increase in exhaust gas flow resistance in the exhaust gas passage 2, and
The output of the engine body 1 can be improved.

Further, when the amount of the particulates trapped in the particulate trap 6 increases during the operation of the engine body 1, the regeneration burner 12 on the upstream side of the particulate trap 6 is driven to drive this burner. A regeneration operation for burning the particulates on the particulate trap 6 with the combustion gas of No. 12 is performed, and the heat generated during the regeneration operation heats the downstream catalyst body 7a to a regeneration temperature at which the SO ₂ component can be removed. As a result, the SO ₂ component attached to the zeolite catalyst can be removed. Therefore, it is possible to prevent the SO ₂ component from adhering to the zeolite catalyst 7 as in the related art, and prevent the zeolite catalyst 7 from being poisoned and deteriorated.

Further, during operation of the engine body 1, hydrocarbon is ejected from the injection nozzle 18 of the hydrocarbon supply means 17 to the catalyst 7, so that the O ₂ component adhered to the catalyst body 7a by the hydrocarbon. efficiently can be removed, it is possible to prevent a reduction in purifying performance of the NO _x components by the catalyst body 7a.

Further, O ₂ adhering to the catalyst body 7a
Since it is not necessary to separately install a device for generating the selective reducing agent as in the case of using ammonia gas or the like as the selective reducing agent for removing components, it is inexpensive in cost and advantageous in terms of safety. .

Further, since the injection nozzle 18 of the hydrocarbon supply means 17 is disposed between the particulate trap 6 and the catalyst 7, the catalyst can be efficiently removed from the injection nozzle 18 without adhering hydrocarbons to the particulate trap 6. 7
Can be supplied with hydrocarbons.

[0049] Further, arrangement of the particulate trap 6 and NO _x catalyst 7 for component purification of exhaust gas for collecting particulates in exhaust gas in a cylindrical vessel 5 of the exhaust gas treatment unit 3 in series with Therefore, the number of components can be reduced as compared with a case where these are mounted in separate dedicated containers 5, respectively, which is advantageous in terms of cost.

Further, since the injection nozzle 18 of the hydrocarbon supply means 17 and the burner 12 are connected to the common fuel tank 16, the injection hydrocarbon from the injection nozzle 18 of the hydrocarbon supply means 17 and the fuel of the burner 12 are connected. Can be simplified as compared with the case of supplying them from separate fuel tanks. Further, the first on-off valve 22 and the second
The switching means of the on-off valve 23 allows switching between the communication of the exhaust gas passage 2 to the particulate trap 6 and the communication to the bypass passage 21. Therefore, for example, when the particulate trap 6 is regenerated, the exhaust gas passage 2 is communicated with the bypass passage 21 so that the exhaust gas can be prevented from flowing into the particulate trap 6. 6 can be prevented from changing, and a stable regeneration process of the particulate trap 6 can be performed.

The present invention is not limited to the above embodiment.

For example, in the above embodiment, NO in the exhaust gas
_When the state where the detected value of the _x concentration is higher than the set concentration is detected, the injection on-off valve 20 is switched to the open state, and the fuel pump 15 is simultaneously switched to the on state to supply the hydrocarbon. supplying hydrocarbon into the catalyst 7 from the injection nozzle 18 of the means 17, when the concentration of NO _x is lower than nominal concentration which is stored in advance in the controller 24, and shows what a configuration to stop the supply of hydrocarbon but it causes a switching operation to open valve state injection on-off valve 20 only a predetermined set time when the state where the detection value of the NO _x concentration in the exhaust gas rises above setting concentration is detected, the fuel pump 15 also At the same time, switch to the ON state,
The supply of the hydrocarbon may be stopped after the set time has elapsed.

Further, it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0054]

According to the present invention, a bypass passage connecting the upstream portion and the downstream portion of the particulate trap in the exhaust gas passage and bypassing the particulate trap, and a communication passage between the exhaust gas passage and the particulate trap and a bypass passage are provided. And a switching means capable of switching between the communication with the exhaust gas and the exhaust gas, so that the particulates in the exhaust gas can be efficiently purified during the operation of the engine, and the regeneration process of the particulate trap can be performed stably. it can. Further, the switching means makes it possible to switch between communication between the exhaust gas passage to the particulate trap and communication to the bypass passage, and when the temperature of the catalyst reaches the upper limit value, the regeneration processing by the regeneration burner. Since the operation is stopped, for example, at the time of regeneration of the particulate trap, the exhaust gas passage is communicated with the bypass passage, and it becomes possible to prevent the exhaust gas from flowing into the particulate trap. In addition to being able to prevent changes in the regeneration temperature, it is possible to perform a stable regeneration process, and in addition, it is possible to control the regeneration burner so that it does not exceed the heat resistance temperature of the catalyst, thereby improving the durability of the catalyst. Play.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a main configuration of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of the entire exhaust system of the diesel engine.

FIG. 3 is a longitudinal sectional view showing a schematic configuration of a particulate trap.

FIG. 4 is a front view showing an end surface of the particulate trap.

FIG. 5 is a schematic configuration diagram showing a connection state of a controller.

[Explanation of symbols]

2 ... Exhaust gas passage, 3 ... Exhaust gas treatment unit, 5 ... Cylindrical container, 6 ... Particulate trap, 7 ... Catalyst,
12 ... burner, 17 ... hydrocarbon supply means.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F01N 3/24 F01N 3/24 EL (56) Reference JP-A-1-83809 (JP, A JP-A-48-82217 (JP, A) JP-A-1-253522 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] 1. A particulate trap disposed in an exhaust gas passage of an internal combustion engine for collecting particulates in exhaust gas, and a nitrogen oxide purifier disposed downstream of and in series with the particulate trap. A catalyst for regeneration, a regeneration burner disposed upstream of the particulate trap and burning and regenerating the particulates collected in the particulate trap. A bypass passage that communicates an upstream portion of the particulate trap of the exhaust gas passage with a downstream portion of the catalyst and bypasses the particulate trap and the catalyst; and a communication of the exhaust gas passage with the particulate trap. Switching means for switching between communication with the bypass passage, and a temperature for detecting the temperature of the catalyst; And combustion stopping means for stopping the burning of the particulates by the regeneration burner when the temperature of the catalyst detected by the temperature sensor reaches a preset upper limit temperature. Exhaust gas treatment device characterized.