JP3519349B2 - Exhaust system for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exhaust system for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in a diesel engine, a particulate filter is arranged in an engine exhaust passage to remove fine particles contained in exhaust gas, and the particulate filter temporarily collects fine particles in the exhaust gas. Then, the particulate filter collected on the particulate filter is ignited and burned to regenerate the particulate filter. However, the particulate matter collected on the particulate filter does not ignite unless it reaches a high temperature of about 600 ° C. or higher, whereas the exhaust gas temperature of the diesel engine is usually considerably lower than 600 ° C. Therefore, normally, the exhaust gas is heated by an electric heater to ignite and burn the particulates collected on the particulate filter.

Further, when burning the particulates collected on the particulate filter, if the flow velocity of the exhaust gas passing through the particulate filter is too fast, the combustion will not continue, and in order to continue the burning, the particulates It is necessary to slow the flow rate of exhaust gas passing through the filter. Further, in order to make the exhaust system of the engine compact, it is preferable to arrange a particulate filter and an electric heater in the silencer.

Therefore, a particulate filter and an electric heater are arranged in the silencer, and a passage switching valve for switching the passage of the exhaust gas is provided. Normally, all the exhaust gas is particulated by this passage switching valve. When the fine particles trapped on the particulate filter are ignited and burned by flowing them into the filter, a part of the exhaust gas is heated by an electric heater and then flowed into the particulate filter in the direction opposite to that during normal operation. An exhaust device is known in which most of the remaining exhaust gas is discharged into the atmosphere without flowing into the particulate filter (see Japanese Utility Model Laid-Open No. 1-149515).

On the other hand, it is preferable that the particles collected on the particulate filter are ignited and burned by the heat of the exhaust gas without using an electric heater, and for that purpose, the ignition temperature of the particles must be lowered. Regarding this point, it has been conventionally known that the ignition temperature of fine particles can be lowered by supporting a catalyst on a particulate filter,
Therefore, conventionally, various particulate filters carrying a catalyst for lowering the ignition temperature of fine particles are known.

For example, Japanese Patent Publication No. 7-106290 discloses a particulate filter in which a mixture of platinum group metal and alkaline earth metal oxide is carried on the particulate filter. In this particulate filter, the fine particles are ignited at a relatively low temperature of approximately 350 ° C. to 400 ° C., and then continuously burned.

[0007]

In a diesel engine, the exhaust gas temperature rises from 350 ° C to 400 ° C when the load increases, and therefore the above-mentioned particulate filter apparently has a high exhaust gas heat when the engine load increases. It seems that the particles can be ignited and burned by. However, in reality, once a large amount of fine particles are accumulated on the particulate filter, these fine particles gradually change into carbon, which is difficult to burn, and as a result, the fine particles are not generated even when the exhaust gas temperature reaches 350 ° C to 400 ° C. Ignition does not burn. Therefore, in order to continuously burn the particulates on the particulate filter, it is necessary to prevent a large amount of particulates from accumulating on the particulate filter.

An object of the present invention is to provide a compact and practical exhaust system for an internal combustion engine, which is suitable for continuously oxidizing and removing fine particles on a particulate filter.

[0009]

In order to achieve the above object, in the first aspect of the present invention, a bidirectional exhaust having a first exhaust gas outflow inlet at one end and a second exhaust gas outflow inlet at the other end. A particulate filter is arranged in the flow passage, and a flow path switching valve for switching the flow path of the exhaust gas is provided. When the flow path switching valve causes the exhaust gas to flow into the first exhaust gas outlet / inlet port, the particulate filter is provided. After passing through the curate filter, the exhaust gas flowing out from the second exhaust gas inflow / outflow port is sent into the muffler chamber of the muffler, and when the exhaust gas is caused to flow into the second exhaust gas outflow / inflow port by the flow path switching valve, the particulate filter In an exhaust system of an internal combustion engine, in which the exhaust gas flowing out of the first exhaust gas outflow port after passing is sent into the muffler chamber of the muffler, the two-way exhaust passage and the particulate filter are provided. Motor, is arranged the flow path switching valve and silencing chamber in a single casing.

In the second invention, in the first invention,
A valve chamber accommodating a flow path switching valve is formed at one end of the casing, and an exhaust gas inlet into which exhaust gas discharged from the combustion chamber flows, a first exhaust gas outflow inlet, and a second exhaust gas are introduced into the valve chamber. The gas outflow inlet and the exhaust gas outlet opening to the muffler chamber are open, and the flow path switching valve guides the exhaust gas flowing from the exhaust gas inlet to the first exhaust gas outlet and the second exhaust gas. A first position for leading the exhaust gas flowing out from the gas outlet to the exhaust gas outlet, and a first position for guiding the exhaust gas flowing from the exhaust gas inlet to the second exhaust gas outlet and the first exhaust gas outlet It is possible to switch to a second position where the exhaust gas flowing out of the exhaust gas is guided to the exhaust gas outlet.

In the third invention, in the second invention,
The flow path switching valve can be switched to the third position where the exhaust gas flowing from the exhaust gas inlet is directly guided to the exhaust gas outlet without flowing through the particulate filter. According to a fourth aspect of the present invention, in the second aspect, the flow path switching valve is rotatably arranged in the central portion of the valve chamber, and the flow passage switching valve is provided in the peripheral portion of the valve chamber.
Four partition chambers divided by one partition wall are formed, and the respective partition chambers are selectively communicated with each other by the flow passage switching valve. When the flow passage switching valve is located at the first position, the exhaust gas inlet and the first
Of the exhaust gas outlet and the second exhaust gas outlet and the exhaust gas outlet communicate with each other and the flow path switching valve is located at the second position, the exhaust gas inlet and the second exhaust gas An exhaust gas inlet, a first exhaust gas outlet, a second exhaust gas outlet, and an exhaust gas outlet so that the first exhaust gas outlet and the exhaust gas outlet communicate with each other and with the outlet inlet. Are opened in each compartment.

In the fifth invention, in the fourth invention,
When the tip portion of the flow path switching valve comes into contact with the tip portions of a pair of partition walls located on opposite sides with respect to the rotation axis of the flow path switching valve, the valve chamber is divided into two by the pair of partition walls and the flow path switching valve. As a result, the compartments are selectively communicated with each other. In a sixth aspect based on the second aspect, the muffler chamber is arranged at the other end of the casing, and the particulate filter accommodating chamber is formed between the valve chamber and the muffler chamber, and the valve chamber and the particulate filter accommodating chamber are formed. A first exhaust gas outflow port, a second exhaust gas outflow port, and an exhaust gas outflow port are formed on the partition wall to be separated.

In the seventh invention, in the sixth invention,
The particulate filter accommodating chamber is disposed on both sides of the exhaust gas outflow chamber and the exhaust gas outflow chamber extending from the exhaust gas outflow port toward the muffler chamber through the central portion of the particulate filter accommodating chamber by the pair of partition walls, and each of the first and second exhaust gas outflow chambers is disposed on the both sides of the exhaust gas outflow chamber. First communication with the exhaust gas outflow inlet and the second exhaust gas outflow inlet of
And a second small chamber, and the particulate filter penetrates the exhaust gas outflow chamber so that the exhaust gas inflow / outflow ends thereof are located in the first small chamber and the second small chamber, respectively.

In the eighth invention, in the sixth invention,
A pair of particulate filters are arranged in the particulate filter accommodating chamber so that the exhaust gas sequentially passes through the respective particulate filters, and the exhaust gas outlet is connected to the muffler chamber through an exhaust gas outflow pipe extending in the particulate filter accommodating chamber. It is connected. In a ninth aspect based on the first aspect, as the particulate filter, the amount of particulates discharged from the combustion chamber per unit time can be oxidized and removed on the particulate filter without emitting a luminous flame per unit time. When the amount of the fine particles in the exhaust gas is smaller than the amount that can be removed, a particulate filter that can be oxidized and removed without emitting a bright flame when the particulates in the exhaust gas flow into the particulate filter is used, and the precious metal catalyst is carried on the particulate filter.

According to the tenth invention, in the ninth invention, when excess oxygen exists in the surroundings, the oxygen is taken in to retain the oxygen, and when the surrounding oxygen concentration decreases, the retained oxygen is released in the form of active oxygen. The oxygen releasing agent is carried on the particulate filter, and when the particulates adhere to the particulate filter, the active oxygen releasing agent releases the active oxygen, and the released active oxygen oxidizes the particulates adhering to the particulate filter. I am trying to let you.

According to the eleventh invention, in the tenth invention, the active oxygen releasing agent comprises an alkali metal, an alkaline earth metal, a rare earth or a transition metal. According to the twelfth invention, in the eleventh invention, the alkali metal and the alkaline earth metal are metals having a higher ionization tendency than calcium. In the thirteenth invention, in the tenth invention, the active oxygen releasing agent absorbs NO _x in the exhaust gas and exhausts the exhaust gas flowing into the particulate filter when the air-fuel ratio of the exhaust gas flowing into the particulate filter is lean. It has a function of releasing absorbed NO _x when the air-fuel ratio becomes the stoichiometric air-fuel ratio or becomes rich.

[0017]

FIG. 1 shows a case where the present invention is applied to a compression ignition type internal combustion engine. The present invention can also be applied to a spark ignition type internal combustion engine. Referring to FIG. 1, 1 is an engine body, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is an electrically controlled fuel injection valve, 7 is an intake valve, 8 is an intake port, and 9 is an intake port. Indicates an exhaust valve, and 10 indicates an exhaust port, respectively. The intake port 8 is connected to a surge tank 12 via a corresponding intake branch pipe 11, and the surge tank 12 is connected to a compressor 15 of an exhaust turbocharger 14 via an intake duct 13.
A throttle valve 17 driven by a step motor 16 is arranged in the intake duct 13, and the intake duct 13 is further provided.
A cooling device 18 for cooling the intake air flowing in the intake duct 13 is arranged around the device. In the embodiment shown in FIG. 1, the engine cooling water is guided into the cooling device 18, and the intake air is cooled by the engine cooling water. On the other hand, the exhaust port 10 is connected to an exhaust turbine 21 of an exhaust turbocharger 14 via an exhaust manifold 19 and an exhaust pipe 20, and an outlet of the exhaust turbine 21 is connected via an exhaust pipe 22 to a casing 23 accommodating a particulate filter and the like. Be connected.

The exhaust manifold 19 and the surge tank 12 are connected to each other via an exhaust gas recirculation (hereinafter referred to as EGR) passage 24, and an electric control type EGR control valve 25 is arranged in the EGR passage 24. In addition, the EGR passage 24
A cooling device 26 for cooling the EGR gas flowing in the EGR passage 24 is arranged around the device. In the embodiment shown in FIG. 1, the engine cooling water is guided into the cooling device 26, and the EGR gas is cooled by the engine cooling water. On the other hand, each fuel injection valve 6 is connected to a fuel reservoir, a so-called common rail 27, via a fuel supply pipe 6a. Fuel is supplied into the common rail 27 from a fuel pump 28 of an electrically controlled variable discharge amount, and the fuel supplied into the common rail 27 is supplied to the fuel injection valve 6 via each fuel supply pipe 6a. A fuel pressure sensor 29 for detecting the fuel pressure in the common rail 27 is attached to the common rail 27, and the fuel pump 28 is arranged so that the fuel pressure in the common rail 27 becomes the target fuel pressure based on the output signal of the fuel pressure sensor 29. Is controlled.

The electronic control unit 30 is composed of a digital computer and has a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, an input port 35, and an input port 35, which are connected to each other by a bidirectional bus 31. An output port 36 is provided. The output signal of the fuel pressure sensor 29 is input to the input port 35 via the corresponding AD converter 37. A load sensor 41 that generates an output voltage proportional to the depression amount L of the accelerator pedal 40 is connected to the accelerator pedal 40, and the output voltage of the load sensor 41 is input to the input port 35 via the corresponding AD converter 37. . Further input port 35
A crank angle sensor 42 that generates an output pulse each time the crankshaft rotates, for example, 30 ° is connected to.
On the other hand, the output port 36 is connected through the corresponding drive circuit 38 to the fuel injection valve 6 and the throttle valve driving step motor 1
6, the EGR control valve 25, and the fuel pump 28.

FIG. 2 shows a schematic perspective view of the casing shown in FIG. 1, and FIG. 3A shows a schematic plan view of the casing shown in FIG. Also, FIG.
3B is a side view taken along the arrow B in FIG. 3A, and FIGS. 3C, 3D, and 3E are shown in FIG.
A sectional view taken along the arrow C in FIG. Referring to FIG. 2 and FIGS. 3A to 3C, the casing 23 includes an outer peripheral wall 50 and a pair of end walls 51 and 52, and the casing 23 has a uniform shape close to an ellipse. It has a unique cross-sectional shape. Inside the casing 23, a plurality of partition walls 53a, 53b, 53 that are parallel to each other are provided.
a plurality of small chambers 54a, 54b, 54 by c, 53d
c, 54d, 54e. In this case, the end wall 5
The small chamber 54a formed between the partition wall 53a and the partition wall 53a forms a valve chamber, the small chamber 54b formed between the pair of partition walls 53a and 53b forms a particulate filter storage chamber, and the partition wall 53b and the end wall. Small chambers 54c, 5 formed between 52
4d and 54e form a muffling chamber.

The particulate filter accommodating chamber 54b has a first small chamber 56a located below by a pair of partition walls 55a and 55b extending parallel to each other between the pair of partition walls 53a and 53b, and a second upper chamber. Small room 56
b and a third small chamber 56c located in the middle. A particulate filter 57 extending through the third small chamber 56c is arranged between the first small chamber 56a and the second small chamber 56b, and the exhaust gas inflow and outflow ends of the particulate filter 57 are respectively the first and second. Of the small chamber 56a and the second small chamber 56b. First small room 56
When the exhaust gas is sent into a, the exhaust gas flows through the particulate filter 57 and flows into the second small chamber 56b, and when the exhaust gas is sent into the second small chamber 56b, the exhaust gas is particulated. It flows through the filter 57 and flows out into the first small chamber 56a. Therefore, the first small chamber 56a and the second small chamber 56b form an exhaust bidirectional passage.

On the other hand, a flow path switching valve 58 is arranged at the center of the valve chamber 54a. The flow path switching valve 58 is provided in the valve chamber 5
4a, a valve shaft 58a extending in the longitudinal direction of the casing 23 and a butterfly valve body 58b supported by the valve shaft 58a. The butterfly valve body 58b has a rectangular shape. The valve shaft 58a is rotationally controlled by a drive motor or a negative pressure diaphragm device.

On the other hand, four partition chambers 60a, 60b, 60c, 60d divided by four partition walls 59a, 59b, 59c, 59d are formed around the valve chamber 54a. Valve chamber 54a and particulate filter storage chamber 5
The first small chamber 56a is provided on the partition wall 53a which divides the partition 4b.
A first exhaust gas outlet / inlet 61 that communicates with the inside, and a second exhaust gas outlet / inlet 62 that communicates with the inside of the second small chamber 56b,
An exhaust gas outlet 63 that communicates with the third small chamber 56c is formed. On the other hand, an exhaust gas inlet 64 communicating with the exhaust pipe 22 is formed on the end wall 51.

As can be seen from FIG. 3 (C), the first exhaust gas outflow inlet 61 is opened in the compartment 61a, and
The exhaust gas outflow inlet 62 is opened in the compartment 60b, the exhaust gas outlet 63 is opened in the compartment 60c, and the exhaust gas inlet 64 is opened in the compartment 60d. As shown in FIG. 3C, the flow path switching valve 58 has a first end portion in which the front end portion of the flow path switching valve 58 abuts on the front end portions of some of the partitions 59a and 59c located on opposite sides of the valve shaft 58a. 2A in which the tip of the flow path switching valve 58 abuts the tip of a pair of partition walls 59b and 59d located on opposite sides of the valve shaft 58a.
Position B and the first position A as shown in FIG.
The rotation is controlled to a third position C which is an intermediate position between the second position B and the second position B.

When the flow path switching valve 58 is located at the first position A shown in FIG. 3C, the partition chambers 60a and 60d and the partition chambers 60b and 60c are a pair of partition walls 59a and 59c and the flow path switching valve. 58, at which time the exhaust gas inlet 64 communicates with the first exhaust gas outlet 61 and the second exhaust gas inlet 64
Of the exhaust gas outlet 62 communicates with the exhaust gas outlet 63.

On the other hand, the flow path switching valve 58 is shown in FIG.
When located in the second position B shown in FIG.
a and 60c and the compartments 60b and 60d are a pair of partition walls 59.
b and 59d and the flow path switching valve 58, the exhaust gas inflow port 64 communicates with the second exhaust gas outflow port 62 and the first exhaust gas outflow port 61 communicates with the exhaust gas outflow port 63. .

When the flow path switching valve 58 is located at the third position C shown in FIG. 3 (D), all the compartments 60a,
60b, 60c, 60d communicate with each other. On the other hand, as described above, the small chambers 54c, 54d, 54e form a sound deadening chamber. In this case, in the embodiment shown in FIG. 3 (A), the small chamber 54c is the first expansion chamber and the small chamber 54d is the second expansion chamber. The expansion chamber / resonance chamber and the small chamber 54e form a resonance chamber.

Fourth (A) shows another embodiment of the casing. Note that FIG. 4B is a side view taken along the arrow B in FIG. 4A and includes FIGS. 4C and 4D.
Shows a sectional view taken along arrows C and D in FIG. 4 (A), respectively. In FIG. 4, the same components as those shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, a pair of particulate filters 57 are provided in the particulate filter storage chamber 54b.
Are juxtaposed. One end of the particulate filter 57 is supported by the filter supporting partition wall 65, and the other end of the particulate filter 58 is attached to the stay 6.
Supported by 6. Further, a partition wall 67 for separating the first small chamber 56a and the second small chamber 56b extends between the partition wall 53a and the filter supporting partition wall 65.

In this embodiment, as shown in FIG. 4C, the first exhaust gas outflow inlet 61 and the second exhaust gas outflow inlet 62 are made up of a large number of small holes, and the exhaust gas outflow port 63 is provided with a pattern. It communicates with the exhaust gas outflow pipe 68 which penetrates the inside of the curate filter accommodating chamber 54b and opens inside the small chamber 54c. FIG. 5 shows a modification of FIG. 4 in which the particulate filter 57 shown in FIG. 4 is integrated. In this modification, the central portion 57a of the particulate filter 57 is
Is formed so that exhaust gas does not flow from the upper part to the lower part of the particulate filter 57 or from the lower part to the upper part.

FIG. 6 (A) shows a front view of a typical particulate filter, and FIG. 6 (B) shows FIG. 6 (A).
3 is a side sectional view of the particulate filter shown in FIG. The particulate filter 57 shown in FIG. 3 has an elliptical cross-sectional shape, and has a shorter axial length than the particulate filter shown in FIG. 6, but basically has the same structure as the particulate filter shown in FIG. And has the particulate filter 57 shown in FIG.
Has a longer axial length than the particulate filter shown in FIG. 6, but also has basically the same structure as the particulate filter shown in FIG. Therefore,
And each particulate filter 57 shown in FIG.
6 will be described separately, but the structure of a typical particulate filter shown in FIG. 6 will be described.

As shown in FIGS. 6A and 6B, the particulate filter has a honeycomb structure, and a plurality of exhaust flow passages 8 extending in parallel with each other.
It is equipped with 0,81. One end of these exhaust flow passages is a plug 82.
The exhaust gas flow passage 80 closed by the
The exhaust gas flow passage 81 is closed by The hatched portion in FIG. 6A indicates the plug 83. Therefore, the exhaust gas flow passages 80 and the exhaust gas flow passages 81 are alternately arranged via the thin partition walls 84. In other words, in the exhaust gas flow passage 80 and the exhaust gas flow passage 81, each exhaust gas flow passage 80 is surrounded by four exhaust gas flow passages 81, and each exhaust gas flow passage 8
1 is arranged so as to be surrounded by four exhaust gas flow passages 80.

The particulate filter is made of a porous material such as cordierite. Therefore, when the exhaust gas is fed into the particulate filter from the X direction in FIG. 6 (B), it enters the exhaust gas flow passage 80. The inflowing exhaust gas passes through the surrounding partition wall 84 as shown by the arrow and flows out into the adjacent exhaust gas flow passage 81. On the other hand, when the exhaust gas is fed into the particulate filter from the direction of the arrow Y in FIG. 6 (B), the exhaust gas flowing into the exhaust gas flow passage 81 is shown in FIG. 6 (B).
In the opposite direction to the arrow shown in FIG. 5, the gas flows through the surrounding partition wall 84 into the adjacent exhaust gas flow passage 80.

In the embodiment according to the present invention, a carrier layer made of, for example, alumina is formed on the peripheral wall surfaces of the exhaust gas flow passages 80 and 81, that is, on both side surfaces of each partition wall 84 and on the inner wall surfaces of the pores in the partition wall 84. When a precious metal catalyst and excess oxygen are present on this support, oxygen is taken in to retain oxygen and when the ambient oxygen concentration decreases, the retained oxygen is released in the form of active oxygen. The agent is carried.

In this case, in the embodiment of the present invention, platinum Pt is used as the noble metal catalyst, and as the active oxygen releasing agent, potassium K, sodium Na, lithium Li, cesium Cs, alkali metal such as rubidium Rb, barium Ba. , Calcium Ca, alkaline earth metals such as strontium Sr, lanthanum La, yttrium Y, rare earths such as cerium Ce, and at least one selected from transition metals.

In this case, the active oxygen releasing agent is an alkali metal or alkaline earth metal having a higher ionization tendency than calcium Ca, that is, potassium K, lithium Li,
It is preferable to use cesium Cs, rubidium Rb, barium Ba, and strontium Sr. Next, the action of removing particulates in the exhaust gas by the particulate filter 57 shown in FIGS. 3 and 4 will be described by taking as an example the case where platinum Pt and potassium K are supported on the carrier, but other precious metals, alkali metals, alkalis The same fine particle removing action is performed by using an earth metal, a rare earth or a transition metal.

In a compression ignition type internal combustion engine as shown in FIG. 1, combustion is performed under an excess of air, and therefore the exhaust gas contains a large amount of excess air. That is, when the ratio of air to fuel supplied into the intake passage, the combustion chamber 5 and the exhaust passage is called the air-fuel ratio of exhaust gas, the air-fuel ratio of exhaust gas in a compression ignition internal combustion engine as shown in FIG. It is lean. Further, NO is generated in the combustion chamber 5, so the exhaust gas contains NO. In addition, sulfur S in the fuel
This sulfur S reacts with oxygen in the combustion chamber 5 to become SO ₂ . Therefore, the exhaust gas contains SO ₂ . Therefore, when the exhaust gas is sent into the particulate filter 57, excess oxygen, NO and SO ₂
The exhaust gas containing the gas will flow into the exhaust gas flow passage 80 or 81.

FIGS. 7A and 7B schematically show enlarged views of the surface of the carrier layer formed on the inner peripheral surface of the exhaust gas flow passage 80 or 81 and the inner wall surface of the pores in the partition wall 84. ing. In FIGS. 7A and 7B, 90 indicates particles of platinum Pt, and 91 indicates an active oxygen release agent containing potassium K. As described above, since the exhaust gas contains a large amount of excess oxygen, the exhaust gas is exhausted to the exhaust gas flow passage 80 of the particulate filter 57.
Or when flowing into 81, these oxygen O ₂ adheres to the surface of platinum Pt in the form of O ₂ ⁻ or O ^{2 −} as shown in FIG. 7 (A). On the other hand, NO in the exhaust gas reacts with O ₂ ⁻ or O ^{2 −} on the surface of platinum Pt to become NO ₂ (2NO + O
₂ → 2NO ₂ ). Then, a part of NO ₂ produced is absorbed in the active oxygen releasing agent 91 while being oxidized on platinum Pt, and is combined with potassium K to form nitrate ion NO ₃ ⁻ as shown in FIG. 7 (A). And diffused into the active oxygen releasing agent 91, and some of the nitrate ions NO ₃ ⁻ are potassium nitrate KN.
Generates O ₃ .

On the other hand, as described above, SO is contained in the exhaust gas.
₂Also included, this SO₂The same mechanism as NO
The oxygen is absorbed in the active oxygen release agent 91. That is,
As described above, oxygen O₂Is O₂ ^-Or O^2-In the form of platinum P
attached to the surface of t and SO in exhaust gas₂Is platinum P
O on the surface of t₂ ^-Or O^2-Reacts with SO₃Becomes Next
SO generated by₃Is partially oxidized on platinum Pt.
While being absorbed into the active oxygen release agent 91, potassium K
Sulfate ion SO while binding_Four ^2-Active oxygen releasing agent in the form of
91 diffuses into potassium sulfate K₂SO_FourTo generate.
Thus, potassium nitrate is contained in the active oxygen release catalyst 91.
Mu KNO₃And potassium sulfate K₂SO _FourIs generated
It

On the other hand, in the combustion chamber 5, fine particles mainly composed of carbon C are produced, and therefore, the exhaust gas contains these fine particles. As for these fine particles contained in the exhaust gas, the exhaust gas is particulate filter 5
7 while flowing in the exhaust gas flow passage 80 or 81 or in the partition wall 84, as shown by 92 in FIG. 7B, the surface of the carrier layer, for example, the active oxygen releasing agent 91. Contact and adhere to the surface of.

Thus, the fine particles 92 are the active oxygen releasing agent 9
When attached on the surface of No. 1, fine particles 92 and active oxygen releasing agent 9
The oxygen concentration decreases at the contact surface with 1. When the oxygen concentration decreases, a difference in concentration occurs between the active oxygen releasing agent 91 having a high oxygen concentration, so that the oxygen in the active oxygen releasing agent 91 is directed toward the contact surface between the fine particles 92 and the active oxygen releasing agent 91. Try to move. As a result, potassium nitrate KNO ₃ formed in the active oxygen release agent 91 is converted into potassium K and oxygen O.
Is decomposed into NO and NO, oxygen O moves toward the contact surface between the fine particles 92 and the active oxygen release agent 91, and NO changes into the active oxygen release agent 9
It is released from the outside. The NO released to the outside is oxidized on the platinum Pt on the downstream side and is again absorbed in the active oxygen releasing agent 91.

On the other hand, at this time, a form is formed in the active oxygen releasing agent 91.
Potassium sulfate K₂SO _FourAlso potassium K and acid
Element O and SO₂Is decomposed into and oxygen O is activated with the fine particles 92.
Toward the contact surface with the oxygen releasing agent 91,₂Is active oxygen
It is released from the release agent 91 to the outside. S released outside
O₂Is oxidized on the platinum Pt on the downstream side and becomes active again.
It is absorbed in the oxygen releasing agent 91.

On the other hand, oxygen O toward the contact surface between the fine particles 92 and the active oxygen release agent 91 is oxygen decomposed from a compound such as potassium nitrate KNO ₃ or potassium sulfate K ₂ SO ₄ . Oxygen O decomposed from the compound has high energy and has extremely high activity. Therefore, fine particles 9
Oxygen toward the contact surface between 2 and the active oxygen release agent 91 is active oxygen O. When the active oxygen O comes into contact with the fine particles 92, the fine particles 92 are oxidized in a short time without emitting a bright flame, and the fine particles 92 disappear completely.
Therefore, the fine particles 92 do not deposit on the particulate filter 57. The fine particles 92 thus attached to the particulate filter 57 are oxidized by the active oxygen O, but the fine particles 92 are also oxidized by oxygen in the exhaust gas.

When the particulates accumulated in layers on the particulate filter 57 are burned, the particulate filter 57 becomes red hot and burns with a flame. The combustion with such a flame does not continue unless the temperature is high. Therefore, in order to continue the combustion with such a flame, the temperature of the particulate filter 57 must be maintained at a high temperature. On the other hand, in the embodiment according to the present invention, the fine particles 92 are oxidized without emitting a bright flame as described above, and at this time, the surface of the particulate filter 57 does not become red hot. In other words, in other words, in the embodiment according to the present invention, the fine particles 92 are removed by oxidation at a considerably low temperature. Therefore, the effect of removing fine particles by oxidation of the fine particles 92 which does not emit a bright flame used in the present invention is completely different from the effect of removing fine particles by combustion accompanied by a flame.

By the way, platinum Pt and active oxygen releasing agent 9
Since 1 is activated as the temperature of the particulate filter 57 increases, the amount of active oxygen O that can be released by the active oxygen releasing agent 91 per unit time increases as the temperature of the particulate filter 57 increases. Therefore, the amount of the oxidatively removable fine particles that can be oxidatively removed on the particulate filter 57 without emitting a luminous flame per unit time increases as the temperature of the particulate filter 57 increases.

The solid line in FIG. 9 shows the amount G of oxidatively removable fine particles that can be oxidatively removed without emitting a luminous flame per unit time. Note that in FIG. 9, the horizontal axis represents the temperature TF of the particulate filter 57. When the amount of fine particles discharged from the combustion chamber 5 per unit time is referred to as the discharged fine particle amount M, when the discharged fine particle amount M is smaller than the oxidatively removable fine particles G, that is, in the region I of FIG. 9, the fine particles are discharged from the combustion chamber 5. As soon as all the particles thus made come into contact with the particulate filter 57, they are oxidized and removed on the particulate filter 57 in a short time without emitting a bright flame.

On the other hand, when the amount M of discharged fine particles is larger than the amount G of fine particles that can be removed by oxidation, that is, in the region II of FIG. 9, the amount of active oxygen is insufficient to oxidize all the fine particles.
8A to 8C show the state of oxidation of the fine particles in such a case. That is, when the amount of active oxygen is insufficient to oxidize all the fine particles, as shown in FIG. 8A, when the fine particles 92 adhere to the active oxygen release agent 91, only a part of the fine particles 92 is oxidized. As a result, the fine particles that have not been sufficiently oxidized remain on the carrier layer. Next, when the state in which the amount of active oxygen is insufficient continues, the fine particles that were not oxidized one after another remain on the carrier layer, and as a result, FIG.
As shown in (B), the surface of the carrier layer is covered with the residual fine particle portion 93.

This residual fine particle portion 9 covering the surface of the carrier layer
3 gradually deteriorates into a carbon material that is difficult to be oxidized, and thus the residual fine particle portion 93 is likely to remain as it is. Further, when the surface of the carrier layer is covered with the residual fine particle portion 93, the NO and SO ₂ oxidizing action of platinum Pt and the active oxygen releasing action of the active oxygen releasing agent 91 are suppressed. As a result, as shown in FIG. 8C, another fine particle 94 is deposited on the residual fine particle portion 93 one after another. That is, the fine particles are deposited in a laminated form. When the fine particles are stacked in this manner, since the fine particles are separated from the platinum Pt and the active oxygen release agent 91, even the fine particles that are easily oxidized are no longer oxidized by the active oxygen O. Therefore, further fine particles are successively deposited on the fine particles 94. That is, if the state in which the amount M of discharged particulates is larger than the amount G of particulates that can be removed by oxidation continues, the particulates are deposited in a layered manner on the particulate filter 57, thus raising the exhaust gas temperature to a high temperature or particulates. Unless the temperature of the filter 57 is raised, the deposited particles cannot be ignited and burned.

As described above, in the region I of FIG. 9, the fine particles are oxidized on the particulate filter 57 in a short time without emitting a bright flame. In the region II of FIG. 9, the fine particles are laminated on the particulate filter 57. Deposits in the shape of. Therefore, the particulates are not included in the particulate filter 57.
In order to prevent the particles from being accumulated in a stacked state on the upper side, it is necessary to keep the discharged fine particle amount M smaller than the oxidatively removable fine particle amount G at all times.

As can be seen from FIG. 9, in the particulate filter 57 used in the embodiment of the present invention, it is possible to oxidize the fine particles even if the temperature TF of the particulate filter 57 is considerably low, and therefore, in FIG. In the compression ignition type internal combustion engine shown, the amount M of discharged particulates and the temperature TF of the particulate filter 57 are set to the amount M of discharged particulates.
Can be maintained so as to be usually smaller than the amount G of fine particles that can be removed by oxidation. Therefore, in the embodiment according to the present invention, the amount M of discharged particulate and the temperature TF of the particulate filter 57 are maintained so that the amount M of discharged particulate is usually smaller than the amount G of particulate that can be removed by oxidation.

As described above, if the amount M of discharged fine particles is maintained to be usually smaller than the amount G of fine particles that can be removed by oxidation, fine particles will not be deposited on the particulate filter 57 at all. As a result, the pressure loss of the exhaust gas flow in the particulate filter 57 does not change at all and is maintained at a substantially constant minimum pressure loss value. In this way, the reduction in engine output can be kept to a minimum.

Further, the action of removing fine particles by oxidizing fine particles is carried out at a considerably low temperature. Therefore, the temperature of the particulate filter 57 does not rise so much, and there is almost no risk of the particulate filter 57 deteriorating. Further, since no particulates are deposited on the particulate filter 57 at all, there is less risk of ash aggregation, and hence less risk of clogging of the particulate filter 57.

By the way, this clogging is mainly caused by calcium sulfate CaSO ₄ . That is, the fuel and the lubricating oil contain calcium Ca, and therefore the exhaust gas contains calcium Ca. This calcium Ca is SO ₃
Exists to produce calcium sulfate CaSO ₄ . This calcium sulfate CaSO ₄ is a solid and does not thermally decompose even at high temperatures. Therefore, calcium sulfate CaSO ₄ is generated, and if the pores of the particulate filter 57 are blocked by this calcium sulfate CaSO ₄ , clogging will occur.

However, in this case, the active oxygen releasing agent 9
When an alkali metal or alkaline earth metal having a higher ionization tendency than calcium Ca, such as potassium K, is used as 1, SO ₃ diffused in the active oxygen release agent 91 is combined with potassium K to form potassium sulfate K ₂ SO ₄ . However, the calcium Ca passes through the partition wall 84 of the particulate filter 57 without combining with SO ₃ and passes through the exhaust gas flow passage 8
0 or 81. Therefore, the pores of the particulate filter 57 will not be clogged. Therefore, as described above, as the active oxygen releasing agent 91, an alkali metal or alkaline earth metal having a higher ionization tendency than calcium Ca, that is, potassium K, lithium Li, cesium Cs, rubidium Rb, barium Ba, or strontium Sr is used. Would be preferable.

In the embodiments of the present invention, basically, it is intended to maintain the amount M of discharged fine particles to be smaller than the amount G of fine particles that can be removed by oxidation in all operating conditions. However, in reality, it is almost impossible to make the amount M of discharged particulate smaller than the amount G of particulate that can be removed by oxidation in all operating conditions. Therefore, in the embodiment according to the present invention, the flow direction switching valve 58 occasionally reverses the flow direction of the exhaust gas flowing in the particulate filter 57.

That is, for example, in FIG. 6B, the exhaust gas is flowing in the direction of arrow X, and at this time, fine particles are deposited on the inner wall surface of the exhaust gas flow passage 80. At this time, since fine particles are not accumulated on the inner wall surface of the exhaust gas flow passage 81, the flow direction of the exhaust gas is reversed at this time, that is, the flow direction of the exhaust gas is switched to the direction of the arrow Y in FIG. 6 (B). Fine particles in the exhaust gas and the exhaust gas flow passage 81
Oxidized and removed well on the inner wall surface of the. Further, at this time, since fine particles do not deposit on the inner wall surface of the exhaust gas flow passage 80, the fine particles already deposited can be removed by oxidation. By reversing the flow direction of the exhaust gas in this way, the fine particles are oxidized and removed on the inner wall surface of the exhaust gas flow passage 81, and the accumulated fine particles are also oxidized and removed on the inner wall surface of the exhaust gas flow passage 80. Therefore, by occasionally reversing the flow direction of the exhaust gas, it becomes possible to continuously oxidize and remove fine particles.

Further, for example, when the exhaust gas flows in the direction of arrow X in FIG. 6 (B) and the openings of the pores on the inner wall surface of the exhaust gas flow passage 80 are blocked by the solidification of fine particles, the exhaust gas There is also an advantage that when the flow direction of R is reversed, the aggregate of fine particles is blown off from the openings of the pores by the exhaust gas flow, and thereby clogging of the pores can be prevented.

Next, the control routine of the flow path switching valve 58 will be described with reference to FIG. Referring to FIG. 10, first, at step 100, it is judged if the inflow of exhaust gas to the particulate filter 57 should be prohibited. When the temperature of the particulate filter 57 is low, such as when the engine is started, the particulate filter 5
There is a possibility that a large amount of fine particles will be deposited on 7. Further, the temperature of the particulate filter 57 is lowered in the operating state in which the exhaust gas temperature is low, so that also at this time, a large amount of fine particles may be deposited on the particulate filter 57. When a large amount of particulates may be deposited on the particulate filter 57 as described above, it is determined that the inflow of exhaust gas into the particulate filter 57 should be prohibited, and the routine proceeds to step 101.

In step 101, the position of the flow path switching valve 58 is set to the third position C shown in FIG. 3 (D). At this time, through the exhaust pipe 22, from the exhaust gas outlet 64 to the valve chamber 54a
Exhaust gas that has flowed in flows into the exhaust gas outflow port 63 without flowing into the first exhaust gas outflow port 61 and the second exhaust gas outflow port 62. Therefore, at this time, a large amount of fine particles are not deposited on the particulate filter 57.

In the embodiment shown in FIG. 3A, the exhaust gas flowing out into the exhaust gas outlet 63 passes through the third small chamber 56c around the particulate filter 57 and the opening 70 formed in the partition wall 53b. 1 into the expansion chamber 54c. Therefore, in the embodiment shown in FIG. 3A, the third small chamber 56
c forms an exhaust gas outflow chamber. On the other hand, FIG. 4 (A)
In the embodiment shown in FIG. 3, the exhaust gas flowing out into the exhaust gas outlet 63 is passed through the exhaust gas outflow pipe 68 to the first expansion chamber 54c.
Flows in.

When the exhaust gas flows into the first expansion chamber 54c, the exhaust noise is reduced. Then, a part of the exhaust gas is discharged from the opening 71 formed in the partition wall 53c into the second expansion chamber 5
4d, after the exhaust noise is further reduced, the exhaust pipe 7
2 is discharged from inside the casing 23. The remaining exhaust gas flows into the communication pipe 73 having the opening 74, and the exhaust sound of a specific frequency is reduced by the resonance action.

On the other hand, when it is judged in step 100 that the inflow of the exhaust gas into the particulate filter 57 should not be prohibited, the process proceeds to step 102 and whether the inflow direction of the exhaust gas into the particulate filter 57 should be switched or not. Is determined. For example, when a certain period of time elapses after switching the inflow direction of the exhaust gas to the particulate filter 57, or when the acceleration operation in which a large amount of fine particles are discharged from the engine is completed, the inflow direction of the exhaust gas to the particulate filter 57. Is determined to be switched. When it is determined that the exhaust gas inflow direction to the particulate filter 57 should be switched, the process proceeds to step 103.

At step 103, it is judged if the inflow direction switching flag F is set or not. If the flag F is set, the routine proceeds to step 104, where the flag F is reset. Next, at step 105, the position of the flow path switching valve 58 is switched to the first position A shown in FIG. 3 (C). At this time, from the exhaust gas inlet 64 to the valve chamber 54
The exhaust gas that has flowed into the inside a is the first exhaust gas outflow port 61.
Sent in.

In the embodiment shown in FIG. 3A, the exhaust gas sent into the first exhaust gas inflow / outflow port 61 is the first small chamber 56a, the particulate filter 57, and the second small chamber 5.
6b from the second exhaust gas outflow port 62 to the valve chamber 54
It flows out into a and then into the exhaust gas outlet 63. On the other hand, in the embodiment shown in FIG. 4 (A), the exhaust gas sent into the first exhaust gas inflow / outflow port 61 has the first small chamber 5
6a, the particulate filter 57 located on the lower side in FIG. 4, the particulate filter 57 located on the upper side in FIG. 4, and the second exhaust chamber 56b through the second exhaust gas outflow port 62 into the valve chamber 54a. Then, it flows into the exhaust gas outlet 63.

Thereafter, when it is judged again in step 102 that the inflow direction of the exhaust gas to the particulate filter 66 should be switched, since the flag F is reset at this time, the steps from step 103 to step 1
Proceeding to 06, the flag F is set. Next, at step 107, the position of the flow path switching valve 58 is switched to the second position B shown in FIG. At this time, the exhaust gas inlet 6
The exhaust gas flowing into the valve chamber 54a from No. 4 is sent into the second exhaust gas outflow port 62.

In the embodiment shown in FIG. 3A, the exhaust gas sent into the second exhaust gas inflow / outflow port 62 has the second small chamber 56b, the particulate filter 57, and the first small chamber 5 therein.
6a to the valve chamber 54 from the first exhaust gas outflow inlet 61
It flows out into a and then into the exhaust gas outlet 63. On the other hand, in the embodiment shown in FIG. 4 (A), the exhaust gas sent into the second exhaust gas inflow / outflow port 62 has the second small chamber 5
6b, the particulate filter 57 located on the upper side in FIG. 4, the particulate filter 57 located on the lower side in FIG. 4, and the first exhaust chamber 56a through the first exhaust gas inflow / outflow port 61 into the valve chamber 54a. Then, it flows into the exhaust gas outlet 63.

By the way, in both the embodiment shown in FIG. 3 and the embodiment shown in FIG. 4, there is a gap between the particulate filter 57 and the casing 23. Therefore, in any of the embodiments, the particulate filter 57 is kept warm with respect to the outside air, and particularly in the embodiment shown in FIG. 3, high temperature exhaust gas flows around the particulate filter 57. Therefore, the temperature of the particulate filter 57 can be maintained at a high temperature, so that the particulates can be oxidized and removed on the particulate filter 57 over a wide motion region.

On the other hand, as described above, the flow path switching valve 58 has the first position A shown in FIG. 3 (C), the second position B shown in FIG. 3 (E), and the FIG. 3 (D). Is controlled to any one of the third positions C shown in FIG. However, a part of the exhaust gas flowing into the valve chamber 54a from the exhaust gas inlet 64 is caused to flow into the first exhaust gas outlet 61, and the remaining exhaust gas is directly caused to flow into the exhaust gas outlet 63. The switching valve 58 can be held at an intermediate position between the first position A and the third position C, and the exhaust gas inlet 6
4 to allow a part of the exhaust gas flowing into the valve chamber 54a to flow into the second exhaust gas outflow port 62 and the remaining exhaust gas directly into the exhaust gas outflow port 63.
It is also possible to hold 8 at a position intermediate between the second position B and the third position C.

In the above-described embodiments, a carrier layer made of alumina, for example, is formed on both side surfaces of each partition wall 84 of the particulate filter 57 and on the inner wall surfaces of the pores in the partition wall 84. A noble metal catalyst and an active oxygen releasing agent are carried on the top. In this case, when the air-fuel ratio of the exhaust gas flowing into the particulate filter 57 on this carrier is lean, NO contained in the exhaust gas.
The _the NO _x absorbent when the air-fuel ratio of the exhaust gas flowing into the particulate filter 57 absorbs _x emits NO _x absorbed and becomes the stoichiometric air-fuel ratio or rich can also be supported.

In this case, platinum Pt is used as the noble metal as described above, and an alkali metal such as potassium K, sodium Na, lithium Li, cesium Cs, rubidium Rb, barium Ba, calcium Ca is used as the NO _x absorbent. , At least one selected from alkaline earths such as strontium Sr, lanthanum La, and rare earths such as yttrium Y. It should be noted that, as can be seen from comparison with the above-described metal forming the active oxygen releasing agent, the metal forming the NO _x absorbent and the metal forming the active oxygen releasing agent are mostly in agreement.

In this case, different metals may be used as the NO _x absorbent and the active oxygen releasing agent, or the same metal may be used. When the same metal is used as the NO _x absorbent and the active oxygen release agent, NO _x
Both the function as the absorbent and the function as the active oxygen releasing agent are simultaneously fulfilled. Next, the action of absorbing and releasing NO _x will be described by taking as an example the case where platinum Pt is used as the noble metal catalyst and potassium K is used as the NO _x absorbent.

First, considering the action of absorbing NO _x , NO _x is absorbed by the NO _x absorbent by the same mechanism as shown in FIG. 7 (A). However, in this case, reference numeral 91 in FIG. 7A indicates a NO _x absorbent. That is, when the air-fuel ratio of the exhaust gas flowing into the particulate filter 57 is lean, the exhaust gas contains a large amount of excess oxygen, so the exhaust gas flows into the exhaust gas flow passage 80 or 81 of the particulate filter 57. Then, as shown in FIG. 7 (A), the oxygen O ₂ becomes O _2.
It attaches to the surface of platinum Pt in the form of ₂ ⁻ or O ²⁻ . on the other hand,
NO in the exhaust gas is O ₂ ⁻ or O ^{2 −} on the surface of platinum Pt.
Reacts with NO ₂ (2NO + O ₂ → 2NO ₂ ).
Then, a part of the generated NO ₂ is absorbed in the NO _x absorbent 91 while being oxidized on the platinum Pt, and is combined with the potassium K to form the nitrate ion NO ₃ as shown in FIG. 7 (A).
^In the form of ⁻ , it diffuses into the NO _x absorbent 91, and some nitrate ions NO ₃ ⁻ generate potassium nitrate KNO ₃ . In this way, NO is absorbed in the NO _x absorbent 91.

On the other hand, when the exhaust gas flowing into the particulate filter 57 becomes rich, the nitrate ion NO ₃ ⁻ is decomposed into oxygen, O and NO, and NO is released from the NO _x absorbent 91 one after another. Therefore, when the air-fuel ratio of the exhaust gas flowing into the particulate filter 57 becomes rich, NO is released from the NO _x absorbent 91 within a short time, and the released NO is reduced, so that NO is released into the atmosphere. It will not be discharged.

In this case, NO is released from the NO _x absorbent 91 even if the air-fuel ratio of the exhaust gas flowing into the particulate filter 57 is changed to the stoichiometric air-fuel ratio. However it takes some long time to release all NO _x absorbed in _the NO _x absorbent 91 to the NO from _the NO _x absorbent 91 are not only released gradually in this case. Meanwhile it can either be to use different metals as _the NO _x absorbent and the active oxygen release agent as described above, NO _x
The same metal can be used as the absorbent and the active oxygen releasing agent. Will be fulfill both functions of the function of the function and the active oxygen release agent as _the NO _x absorbent as described above at the same time in the case of using the same metal as _the NO _x absorbent and the active oxygen release agent, The one that fulfills both functions at the same time is hereinafter referred to as an active oxygen release / NO _x absorbent. In this case, reference numeral 91 in FIG.
Indicates an active oxygen release / NO _x absorbent.

Such active oxygen release / NO _x absorbent 9
When 1 is used, when the air-fuel ratio of the exhaust gas flowing into the particulate filter 57 is lean, the NO contained in the exhaust gas is absorbed by the active oxygen release / NO _x absorbent 91, and the fine particles contained in the exhaust gas. Is active oxygen release / N
When attached to the O _x absorbent 91 The particles are oxidized removed in a short time by the active oxygen released from the active oxygen release · NO _x absorbent 91. Thus both the particulates and NO _x in the exhaust gas at this time is able to be prevented from being discharged into the atmosphere.

On the other hand, when the air-fuel ratio of the exhaust gas flowing into the particulate filter 57 becomes rich, NO is released from the active oxygen release / NO _x absorbent 91. This NO is reduced by unburned HC and CO, so that NO is not discharged into the atmosphere at this time as well. Further, at this time, if the particulates are deposited on the particulate filter 57, the particulates are the active oxygen releasing / NO _x absorbent 9
It is oxidized and removed by the active oxygen released from 1.

It should be noted that NO _x absorbent or active oxygen release / N
Before absorption of NO _x capacity of the NO _x absorbent or the active oxygen release · _the NO _x absorbent is saturated when the O _x absorbent is used, NO from _the NO _x absorbent or the active oxygen release · _the NO _x absorbent Particulate filter 57 to emit _x
The air-fuel ratio of the exhaust gas flowing into is temporarily made rich.

The present invention can also be applied to the case where only a noble metal such as platinum Pt is carried on the carrier layers formed on both side surfaces of the particulate filter 57. However, in this case, the solid line indicating the amount G of particles that can be removed by oxidation moves to the right of the solid line shown in FIG.
In this case, active oxygen is released from NO ₂ or SO ₃ retained on the surface of platinum Pt.

Further, NO ₂ or S is used as an active oxygen releasing agent.
O ₃ is adsorbed and held, and these adsorbed NO ₂ or SO ₃
It is also possible to use a catalyst capable of releasing active oxygen from
Further, according to the present invention, an oxidation catalyst is arranged in the exhaust passage upstream of the particulate filter, for example, in the exhaust pipe 22, and NO in the exhaust gas is converted into NO ₂ by this oxidation catalyst.
It can also be applied to an exhaust gas purifying apparatus in which O ₂ and fine particles deposited on a particulate filter are reacted to oxidize the fine particles by this NO ₂ .

[0080]

As described above, it is possible to obtain a compact exhaust system capable of continuously oxidizing and removing fine particles in exhaust gas on a particulate filter.

[Brief description of drawings]

FIG. 1 is an overall view of an internal combustion engine.

FIG. 2 is a schematic perspective view of a casing.

FIG. 3 is a diagram showing a first embodiment of the casing.

FIG. 4 is a view showing a second embodiment of the casing.

FIG. 5 is a diagram showing a modified example of a particulate filter.

FIG. 6 is a diagram showing a particulate filter.

FIG. 7 is a diagram for explaining an oxidizing effect of fine particles.

FIG. 8 is a diagram for explaining a deposition action of fine particles.

FIG. 9 is a diagram showing a relationship between the amount of fine particles that can be removed by oxidation and the temperature of a particulate filter.

FIG. 10 is a flowchart for controlling a flow path switching valve.

[Explanation of symbols]

5 ... Combustion chamber 6 ... Fuel injection valve 23 ... Casing 25 ... EGR control valve 57 ... Particulate filter 58 ... Flow path switching valve

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI F01N 1/08 F01N 1/08 K 1/18 1/18 3/08 3/08 A 3/24 3/24 EJ 3 / 28 301 3/28 301C (72) Inventor Michio Morishita 5-3, Hawadayama, Miyoshi, Miyoshi-cho, Nishikamo-gun, Aichi Prefecture 35 Sango Hachiwadayama Factory (56) Reference JP-A-1-178715 (JP , A) JP-A-4-94409 (JP, A) JP-A-7-174018 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F01N 3/02 F01N 1/08 F01N 1/18 F01N 3/08-3/28

Claims (13)

(57) [Claims] 1. A first exhaust gas outflow inlet is provided at one end,
A particulate filter is disposed in an exhaust bidirectional flow passage having a second exhaust gas outflow inlet at the other end, and a passage switching valve for switching the passage of the exhaust gas is provided. When flowing into the first exhaust gas outflow inlet, the exhaust gas flowing out from the second exhaust gas outflow inlet after passing through the particulate filter is sent into the muffler chamber of the muffler, and the exhaust gas is removed by the flow path switching valve. Two
In the exhaust device of the internal combustion engine, the exhaust gas flowing out of the first exhaust gas outflow port after passing through the particulate filter when being made to flow into the exhaust gas outflow port of An exhaust system for an internal combustion engine in which a particulate filter, a flow path switching valve, and a muffling chamber are arranged in one casing. 2. A valve chamber accommodating the flow path switching valve is formed at one end of the casing, and an exhaust gas inflow port into which exhaust gas exhausted from a combustion chamber flows, and the first chamber.
An exhaust gas outflow inlet and a second exhaust gas outflow inlet of
An exhaust gas outlet opening to the muffler chamber is opened, and the flow path switching valve is configured to remove the exhaust gas flowing from the exhaust gas inlet first.
Of the exhaust gas flowing out of the second exhaust gas outflow inlet and the exhaust gas flowing out of the second exhaust gas outflow inlet of the first exhaust gas
Position and the exhaust gas flowing from the exhaust gas inlet
The exhaust gas flowing out from the first exhaust gas outflow port and the exhaust gas flowing out from the first exhaust gas outflow port to the exhaust gas outflow port
The exhaust system for an internal combustion engine according to claim 1, wherein the exhaust system is switchable to the position of. 3. The flow path switching valve can be switched to a third position where the exhaust gas flowing from the exhaust gas inlet is directly guided to the exhaust gas outlet without flowing through the particulate filter. Exhaust device for an internal combustion engine as described. 4. A flow path switching valve is rotatably arranged in the central portion of the valve chamber, and four partition chambers divided by four partition walls are formed in the peripheral portion of the valve chamber to switch the flow channel. When the flow path switching valve is located at the first position, the exhaust gas inflow port and the first exhaust gas outflow port communicate with each other and the second exhaust gas outflow port and the exhaust gas are selectively communicated with each other by the valve. When the gas outlet is in communication and the flow path switching valve is in the second position, the exhaust gas inlet is in communication with the second exhaust gas outflow inlet, and the first exhaust gas outflow inlet and exhaust gas outlet are in communication. 3. The internal combustion engine according to claim 2, wherein the exhaust gas inlet, the first exhaust gas outflow inlet, the second exhaust gas outflow inlet, and the exhaust gas outlet are each opened in each compartment so as to communicate with Exhaust system. 5. The pair of partition walls and the flow passage switching valve when the front end portions of the flow passage switching valve come into contact with the front end portions of the pair of partition walls located on opposite sides with respect to the rotation axis of the flow passage switching valve. The exhaust system for an internal combustion engine according to claim 4, wherein the valve chamber is divided into two, whereby the respective compartments are selectively communicated with each other. 6. A partition for disposing a muffler chamber at the other end of the casing, forming a particulate filter accommodating chamber between the valve chamber and the muffler chamber, and separating the valve chamber and the particulate filter accommodating chamber. The exhaust system for an internal combustion engine according to claim 2, wherein the first exhaust gas outflow inlet, the second exhaust gas outflow inlet, and the exhaust gas outflow outlet are formed on a wall. 7. An exhaust gas outflow chamber extending in the central portion of the particulate filter storage chamber from the exhaust gas outflow port toward the muffling chamber by a pair of partition walls, and the particulate filter storage chamber is provided on both sides of the exhaust gas outflow chamber. A first small chamber and a second small chamber that are arranged and communicate with the first exhaust gas outflow inlet and the second exhaust gas outflow inlet, respectively, and the particulate filter has an exhaust gas inflow and outflow end, respectively, which is first. 7. The exhaust device for an internal combustion engine according to claim 6, wherein the exhaust gas outflow chamber penetrates so as to be located in the small chamber and the second small chamber. 8. A pair of particulate filters are arranged in the particulate filter accommodating chamber so that exhaust gas passes through the respective particulate filters in sequence, and an exhaust gas outlet port is provided with an exhaust gas outflow pipe extending in the particulate filter accommodating chamber. The exhaust system for an internal combustion engine according to claim 6, wherein the exhaust system is connected to the muffling chamber through the exhaust system. 9. The particulate filter,
When the amount of particulates emitted from the combustion chamber per unit time is less than the amount of oxidatively removable particulates that can be oxidized and removed on the particulate filter per unit time without emitting a luminous flame, particulates in the exhaust gas are particulated. The exhaust system for an internal combustion engine according to claim 1, wherein a particulate filter that can be oxidized and removed without emitting a luminous flame when flowing into the filter is used, and the precious metal catalyst is carried on the particulate filter. 10. An active oxygen releasing agent which takes in oxygen to retain oxygen when excess oxygen is present in the surroundings and releases the retained oxygen in the form of active oxygen when the ambient oxygen concentration decreases on a particulate filter. 10. The carrier according to claim 9, wherein when the fine particles adhere to the particulate filter, the active oxygen releasing agent releases active oxygen, and the released active oxygen oxidizes the fine particles adhered to the particulate filter. Exhaust system for internal combustion engine. 11. The exhaust system for an internal combustion engine according to claim 10, wherein the active oxygen releasing agent is made of an alkali metal, an alkaline earth metal, a rare earth or a transition metal. 12. The exhaust system for an internal combustion engine according to claim 11, wherein the alkali metal and the alkaline earth metal are metals having a higher ionization tendency than calcium. 13. The active oxygen releasing agent absorbs NO _x in the exhaust gas when the air-fuel ratio of the exhaust gas flowing into the particulate filter is lean, and the air-fuel ratio of the exhaust gas flowing into the particulate filter is the theoretical air-fuel ratio. The exhaust system for an internal combustion engine according to claim 10, which has a function of releasing absorbed NO _x when the fuel ratio becomes rich.