JPH04183917A - Exhaust gas purifier used for diesel engine - Google Patents

Abstract

PURPOSE:To oxidize carbon monoxide in a part of soot in regenerating a filter to prevent the generation of the carbon monoxide by collecting and purifying the soot contained in exhaust with the filter in normal running to prevent the generation of sulfate. CONSTITUTION:When a microcomputer 21 judges that an urban bus is traveling according to a signal from a vehicle speed sensor 22, an electric motor 26 is rotated forward and a filter bypass pipe 13 is closed by an exhaust gas change- over valve 14. Since current is not supplied to an electric motor 42, a soot burning gas change-over valve 20 is closed. Thus, exhaust gas of a Diesel engine 50 flows to a particulate filter 12 so that soot is collected and purified. Then, the microcomputer 21 supplied current to an electric motor 29 to run an axial fan 28 and send secondary air to the particulate filter 12 for burning the soot. Carbon monoxide contained in the burnt gas is oxidized to carbon dioxide by an oxidized catalyst 17.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an exhaust gas purification device used in a diesel engine in which carbon dioxide contained in exhaust gas is collected by a filter or rate filter.

Background technology In this type of exhaust gas purification device, the particulate matter
Generally, the filter is manufactured from ceramic with a honeycomb structure, and the collected waste is burned with secondary air and regenerated for use.

However, when the particulate filter is regenerated in this way, a part of it is incompletely combusted and carbon monoxide (CO) is generated, which increases the amount of exhaust gas. Purification was insufficient.

The purpose and problem of this invention is to collect the sulfur contained in the exhaust gas during normal operation with a particulate filter, purify the exhaust gas, and prevent the generation of sulfates. In addition, when the particulate filter is regenerated, the generation of carbon monoxide is avoided by oxidizing the carbon monoxide generated by incomplete combustion of a part of the particulate filter. The purpose of the present invention is to provide an exhaust gas purification device for use in diesel engines.

Disclosure of the invention related to the object/problem: In relation to the object/problem of the claimed invention "Part 1 of 2", the exhaust gas purification device used in the diesel engine of this invention is arranged in the middle of the exhaust pipe. A particulate filter that collects soot contained in exhaust gas, and a particulate filter on the upstream side of the particulate filter with respect to the flow of the exhaust gas.
A (1) gas switching valve placed in the exhaust pipe, an air supply device that supplies secondary air to the particulate filter, and an electric device placed on the secondary air inflow side of the particulate filter. An oxidation catalyst connected to the exhaust pipe, downstream of the particulate filter with respect to the heater and its secondary air flow, and one combustion gas enabling the oxidation catalyst to be communicated with the particulate filter. It is located around the area including the switching valve.

During normal operation, the exhaust gas purification device used in the diesel engine of this invention closes the combustion gas switching valve and switches the exhaust gas switching valve to remove the particulates from the tasel engine. Exhaust gas is passed through the filter, and the particulate filter collects the particulate matter contained in the exhaust gas. When the curate filter is regenerated, the combustion gas switching valve is opened and the exhaust gas switching valve is switched to divert the diesel engine exhaust gas to the particulate filter, while at the same time not passing it through the catalyst. A current is applied to the electric heater, and the air supply device supplies secondary air to the particulate filter to combust the particulates collected in the particulate filter.

That is, the secondary air is heated by the electric heater and flows through the particulate filter, combusts the soot collected in the particulate filter, and passes the combustion gas through the oxidation catalyst. released into the atmosphere.

When sonozu\ is burned in the secondary air, even if a part of sozu\ is incompletely combusted and carbon monoxide is generated, that carbon oxide is oxidized by the oxidation catalyst and released into the atmosphere. is released.

Description of Specific Examples Specific examples of the exhaust gas purification device used in the diesel engine of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a specific example 10 of an exhaust gas purification device used in a diesel engine of the present invention, which is applied to a diesel engine 50 for a city lotus.

The exhaust gas purification device 10 includes a casing 11 connected to the middle of an exhaust pipe 52 connected to an exhaust manifold 51 of the diesel engine 50, and a casing 11 disposed within the casing 11 to capture soot contained in the exhaust gas. 2, a filter bypass 13 connected to the exhaust pipe 52 on the upstream and downstream sides of the casing 11 with respect to the flow of the exhaust gas, and a filter bypass 13 connected to the exhaust pipe 52 with respect to the flow of the exhaust gas; On the upstream side of the casing 11, there is an exhaust gas switching valve 14 disposed at the connection point between the exhaust pipe 52 and the filter bypass 13, and on the downstream side of the casing 11 with respect to the flow of exhaust gas,
The particulate filter 2 is connected to the exhaust pipe 52 on the upstream side of the connection point of the bypass 13.
an air supply device 15 for supplying secondary air to a particulate filter 1 for the flow of the secondary air;
A branch pipe 19 is connected to the exhaust pipe 52 between the casing 11 and the exhaust gas switching valve 14.
An oxidation catalyst 17 installed in a catalyst chamber 18 connected to The current flowing through the combustion gas switching valve 20, the exhaust gas switching valve 14, the air supply device 15, the electric heater 16, and the combustion gas switching valve 20 according to the signal from the vehicle speed sensor 22 is controlled. It was assembled including a controlling microphone and computer 21.

The casing 11 is provided with an inlet 23 and an outlet 24, and is connected to the middle of the exhaust pipe 52 with the inlet 23 located on the diesel cone gin 50 side and the outlet 24 on the muffler (not shown) side. Ta.

The particulate filter 12 was formed from ceramic powder into a honeycomb structure in which both ends of the cells were closed in a houndstooth pattern, dried, and then fired.

The particulate filter 12 manufactured in this way was assembled into the casing 11 with the particulate filter 12 biased towards the population 23 side.

The exhaust gas switching valve 14 uses a butterfly valve and operates to switch the exhaust gas of the diesel engine 50 flowing to the particulate filter 12 and filter bypass 13 depending on whether the urban lotus is running or stopping. be done. That is, when the city bus is running, the exhaust gas switching valve 14 closes the filter bypass 13 to allow the exhaust gas to flow through the particulate filter 12, and transfers the gas contained in the exhaust gas to the particulate filter. Collected at 12,
Furthermore, when the detected value of the exhaust pressure sensor 44 exceeds a certain value, the computer 21 recognizes this, and when the city bus stops, the exhaust pipe 52 is connected to the exhaust pipe 52 and the filter bypass 13. is closed and the exhaust gas flows through the filter bypass 13, and at that time, the particulate filter 12 begins to collect the gas.
The valve is switched when the particulate filter 12 is regenerated by combustion with the secondary air blown from the air supply device 15.

A valve shaft 25 of the butterfly valve 14 is directly connected to a motor shaft 27 of an electric motor 26, and the valve is switched by the electric motor 26. Of course, the operation of the electric motor 26 is controlled by the microcomputer 21.

The air supply device 15 was assembled including an axial fan 28, an electric motor 29, and a blower pipe 3o.

The axial fan 28 has a suction port 32 and a discharge port 3.
3 and an impeller 34 rotatably supported within the casing 31, with a shaft 35 of the impeller 34 coupled to a motor shaft 36 of the electric motor 29.

The W motor 29 is connected to the microcomputer 2
Operation is controlled by 1.

The blower pipe 30 has one end connected to the suction port 32 of the casing 3I, and the other end extending into the exhaust pipe 52. Of course, the other end of the blower pipe 30 is directed toward the outlet 24 of the casing 11.

The electric heater 16 is arranged in the casing 31 next to the particulate filter 12 on its outlet side, and is energized by the microcomputer 21 and supplied from the air supply device 15. The secondary air is heated. Of course, this electric heater 1
G heats the particulate filter 12 itself and the secondary air to a temperature suitable for burning the soot trapped in the particulate filter 12.

The oxidation catalyst 17 is such that its catalyst chamber 18 is fabricated comprising a casing 37 with an inlet 38 and an outlet 39 and a honeycomb-shaped flow-through carrier 40 incorporated within the casing 37. career 40
carried by. Of course, that flow-through carrier 4
0 was molded from ceramic powder, dried and fired to produce a honeycomb structure consisting of a large number of cells.

The combustion gas switching valve 20 is a butterfly valve, and is opened and closed depending on the running and stopping of the city bus and the filter exhaust pressure. That is, when the city bus is running, this combustion gas switching valve 20 is closed and normal exhaust gas is not released, so sulfate is not generated, and when the city bus is stopped, it is opened.
Then, it is collected by the particulate filter 12! The first combustion gas, which has been combusted by the secondary air, flows into the catalyst chamber 18 and comes into contact with the oxidation catalyst 17.

In this butterfly valve 20, a valve shaft 41 is directly connected to a motor shaft 43 of an electric motor 42, and the electric motor 42 performs a valve switching operation, that is, an opening/closing operation. Of course, the electric motor 42 is
The operation is controlled by the microcomputer 21.

The microcomputer 21 electrically connects its input circuit to its vehicle speed sensor 22 and exhaust pressure sensor 44, and its output circuit to its electric motors 26, 29, 42 and electric heater 16, respectively. Depending on the signal from the pressure sensor 44, it is determined whether the city bus is running or stopped, or whether the exhaust pressure is high due to a clogged filter, and the electric motor 26, 29, 42 and electric heater are A current is applied to 16.

Next, the operation of the exhaust gas purification device 10 will be explained.

Now, when the city lotus is running, the micro-
The computer 21 determines that the urban lotus is in a running state based on the signal from the vehicle speed sensor 22, and supplies current to the electric motor 26 to rotate the electric motor 26 in the forward direction.
The filter bypass 13 is connected to the exhaust gas switching valve 14.
close.

In addition, in this case, the microcomputer 21 is
Since no current is applied to the electric motor 42, the combustion gas switching valve 20 is closed.

In this way, the filter bypass 13 is closed by the exhaust gas switching valve 14 and the branch pipe 19 is closed by the combustion gas switching valve 20, respectively, so that the exhaust gas of the diesel engine 50 is closed by the particulate gas switching valve 14 and the branch pipe 19 is closed by the combustion gas switching valve 20.・Flows into the filter 12, and the particulates ・
It is collected and purified by the filter 12, and then flows to the muffler.

When the city lotus has high exhaust pressure and is stopped, its microcomputer 21 and its vehicle speed sensor 2
2 and the signal from the exhaust pressure sensor 44 indicates that the city lotus is in a stopped state, and the patty is in a stopped state.
- It is determined that the filler 12 is clogged, and first, current is applied to the electric motor 26, 42 and the electric heater 16.

The electric motor 26 is reversed and the exhaust gas switching valve 1
4 closes the exhaust pipe 52, the electric motor 42 is rotated forward, and the branch pipe 19 is opened to the combustion gas switching valve 20, and the electric heater 16 is placed in a heating state to The exhaust gases of the diesel engine 50 flow through its filter bypass 13 to its muffler.

Immediately thereafter, the microcomputer 21 applies current to its electric motor 29 and operates its axial fan 28 to direct secondary air to the outlet 24 side of its casing 11. It flows through the blow pipe 30.

The secondary air flows from the outlet 24 into the casing 11, is heated by the electric heater 16, and flows to the particulate filter 12.

Therefore, the secondary air is not collected by the particulate matter 1 to filter 12! is combusted and becomes a combustion gas that flows into the catalyst chamber 18.

When carbon monoxide is included in the combustion gas, the
The carbon oxide is oxidized to carbon dioxide (CO7) in the catalyst chamber 18 by the oxidation catalyst 17 supported on the flow-through carrier 40, and is immediately included in the combustion gas and released into the atmosphere.

In that way, the particulate filter 12
was regenerated, and at that time, the combustion gas was also purified.

FIG. 2 schematically shows another specific example 60 of the exhaust gas purification device used in the diesel engine of the present invention, which is applied to the diesel engine 50 of a city bus.

The exhaust gas purification device 60 includes a casing 61 connected to the middle of an exhaust pipe 52 connected to an exhaust manifold 51 of the diesel engine 50, and a casing 61 disposed within the casing 61 to remove waste gas contained in the exhaust gas. Particulates to be collected A branch exhaust pipe 63 is connected to the monthly trachea 52 on the -1-stream side of the casing 61, and connected to the exhaust pipe 52 on the downstream side of the casing 61. Another casing 64 connected in the middle of the branch exhaust pipe 63, another particulate filter 65 disposed inside the other casing 64 to collect soot contained in exhaust gas, and the exhaust pipe 5
2 and the exhaust gas switching valve disposed at the branch point of the branch exhaust pipe 63 ] 4 and the exhaust gas switching valve 4 connected to the exhaust pipe 52 and the branch exhaust pipe 63 on the upstream side of the casing 61 and the other casing 64 with respect to the flow of exhaust gas. Teso's particulate fill 62 and Iya's patty = t-,
- Regarding the air supply device 66 that selectively supplies secondary air to the rate filter 65 and the flow of the secondary air]8, on the upstream side of the particulate filter 62 and other particulate filters 65. Electric heaters 16, 16 arranged on the secondary air inflow side of each of the casing 61 and the other casing 64, and the exhaust pipe 52 on the downstream side of the casing 61 and the other casing 64, respectively, with respect to the flow of exhaust gas. and the catalyst chamber 1 connected to the branch exhaust pipe 63 by a connecting pipe 67, 68.
The oxidation catalyst 17 incorporated in 8 and its connecting pipe 67°6
At the connection point of 8, a combustion engine is disposed in each of the exhaust pipe 52 and the branch exhaust pipe 63 to switch the oxidation catalyst 17 to the particulate filter 62 and other particulate filters 65. The exhaust gas switching valve 69, 70, the exhaust gas switching valve 14, the air supply device 66, the electric heater 16.16, and the combustion gas switching valve 69. It was assembled including a microcomputer 71 that controls the current flowing through the microcomputer 70.

The casings 61 and 64 each include a lower mantle 3 and an outlet lower 4, with the manlower 3 located on the diesel engine 50 side and the outlet lower 4 on the muffler (not shown) side. The exhaust pipe 52 and the branch exhaust pipe 63 are arranged in correspondence with each other in the middle.

The particulate filters 62 and 65 are manufactured in the same manner as the particulate filter 12 used in the above-mentioned exhaust gas purification device 10, and are biased toward the output lower 4 side and accommodated in the casings 61 and 64. It was incorporated.

The air supply device 66 was assembled including an axial fan 28, an electric motor 29, a blower pipe 75, 76, and a solenoid valve 77, 78.

The blast pipe 75, 76 connects one end to the casing 3.
1, and the other end thereof extends into the exhaust pipe 52 and branch exhaust pipe 63 thereof. Of course,
The other end of the blower pipe 75, 76 is connected to the casing 6
It is oriented corresponding to the input lower 3°73 of 1.64.

The solenoid valves 77 and 78 are placed in the middle of the blow pipes 75 and 76, and are controlled to open and close by the microcomputer 71.

The electric heaters 16 , 16 are arranged in the casing 61 , 64 next to the particulate filter 62 , 65 on the lower 3 73 side of the person, and the microcomputer 71 causes current to flow therein. The secondary air supplied from the air supply device 66 and the particulate filters 62 and 65 are heated.

The combustion gas switching valve 69.70 is a butterfly valve having the same structure as the exhaust gas switching valve 14 used in the above-mentioned exhaust gas purification device 10, and is used for soot collection and regeneration of the particulate filter 62.65. It is operated to switch between clean exhaust gas and combustion gas accordingly.

The microcomputer 1 has input circuits connected to its engine circuit sensor 72 and exhaust pressure sensor 44, and output circuits connected to its electric motors 26, 29, 26, 26, electric heaters 16, 16, and solenoid valve 77. The electric motors 26, 29, 26, 26 are electrically connected to the solenoid coils 79, 80 of the .78, respectively, in response to signals from the engine rotation sensor 72 and exhaust pressure sensor 44.
Electric heaters 16, 16 and solenoid coil 7
9. Apply a current to 80, and the two particulates
The collection of one particulate filter 62,65 is controlled in such a way that regeneration is repeated in the other particulate filter 62,65. Of course, that micro
The computer 7I indicates that in the initial state of operation of the diesel engine 50, exhaust gas flows through the exhaust pipe 52 and the particulate filter 62 to the muffler, and in this case, the branch exhaust pipe 63 is connected to the exhaust gas switching switch. The valve 14 controls the connecting pipe 67 so that the exhaust gas does not flow into the branch exhaust pipe 63 and the connecting pipe 67 when the combustion gas switching valve 69 closes the valve 14 .

Then, one of the particulate filters 65 is never regenerated.

Next, the operation of the exhaust gas purification device 60 will be explained.

Now, when the tea cell engine 50 is being operated and the city lotus is traveling, the microcomputer 71 determines that the tea cell engine 50 is in the operating state, and the electric motors 26, 29, 26 .26
and the electric heater 16, connect the branch exhaust pipe 63 to the exhaust gas switching valve 14, connect the connecting pipe 67 to the combustion gas switching valve 69, and connect the branch to the combustion gas switching valve 70. Each of the pipes 63 is closed, and at the same time, the solenoid valve 78 is opened, and the solenoid valve 7 is opened.
Close 7.

As such, the switching valves 14, 69, 70 are operated to switch the diesel engine 50.
Exhaust gas number 1-1 flows to the particulate filter 62, and particulate matter number 1-1 is collected and purified by the particulate filter 62, and then flows to the muffler.

In addition, in that case, the axial fan 28 is
The electric heater I (i) is put into a heating state, so that the secondary air enters the casing 64.
] 73 through the air blowing pipe 76.

The secondary air flows from the person [173 to the casing 6
4, is heated by the electric heater 16, and flows to the particulate filter 65.

Therefore, the secondary air is the particulate
□ Burn the waste collected by the filter 65,
It becomes combustion gas and flows into the catalyst chamber 18.

When carbon monoxide is included in the combustion gas, the
In the catalyst chamber 18, the carbon oxide is oxidized to carbon dioxide (CO□) by the oxidation catalyst 17 supported on the flow-through carrier 40, and is then included in the X-combustion gas and released into the atmosphere. Ru.

In that way, the particulate filter 65
was regenerated, and at this time too, the combustion gas was purified.

Such regeneration of the particulate rate filter 65 is as follows.
When a predetermined period of time has elapsed, the microcomputer 71 turns off the current flowing to the electric motor 29 and electric heater 16, completing the process.

In the above-mentioned exhaust gas purification device 1.0.60, the air supply device 15.66 was described as including an axial fan 28, but the axial fan 28 can be replaced by a compressor and an air tank.

Although the exhaust gas purification device 10.60 has been described as being applied to a city bus, it can be similarly used for trucks.

Further, in the exhaust gas purification device 10.60, the electric heater 16 used for regenerating the particulate filters 12, 62.65 can be replaced with a fuel burner or the like.

Conveniences and Benefits of the Invention As understood from the above, the exhaust gas purification device used in the diesel engine of the present invention includes a particulate filter disposed in the middle of the exhaust pipe to collect soot contained in the exhaust gas. an exhaust gas switching valve disposed in the exhaust pipe on the upstream side of the particulate filter with respect to the flow of the exhaust gas; an air supply device that supplies secondary air to the particulate filter;
Regarding the electric heater placed on the secondary air inflow side of the particulate filter and the flow of the secondary air,
The downstream side of the particulate filter includes an oxidation catalyst connected to the exhaust pipe and a combustion gas switching valve that enables communication of the oxidation catalyst with the particulate filters 1 to 1. In the exhaust gas purification device used in the diesel engine of the invention, the soot contained in the diesel engine exhaust gas is collected by the particulate filter and the exhaust gas is purified, and in this case, the exhaust gas is Since the sulfate is not passed through the oxidation catalyst, no sulfate is generated, and when the vaccumulate filter is regenerated, the carbon monoxide generated by incomplete combustion of a part of the collected waste passes through the oxidation catalyst. The combustion gas is oxidized by the secondary air heated by the electric heater in cooperation with the electric heater, and the combustion gas is purified in the process, preventing the release of carbon oxide into the atmosphere. In the diesel engine installed in the vehicle, it becomes possible and practical to regenerate the particulate filter without interfering with the operation of the vehicle.

As for the relationship between the invention and the specific examples, from the specific examples of the present invention described with reference to the drawings, various design modifications will be apparent to those who have ordinary knowledge in the technical field to which this invention pertains. Further, the contents of this invention are essential to the establishment of the invention for accomplishing the task of the invention, and are derived from the technical essence of the invention which is the nature of the invention. and can be easily replaced with a form that is objectively recognized as incorporating it.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a specific example of an exhaust gas purification device used in a diesel engine of the present invention applied to a diesel engine of a city bus, and FIG. FIG. 2 is a schematic diagram of another specific example of the exhaust gas purification device used in the diesel engine of the present invention applied to the engine. 11.61.64...Casing, 12,62°65
...Particulate filter, 13...Filter bypass, 14...Exhaust gas switching valve, 15°66
...Air supply piping, 16...Electric heater, 17...
- Oxidation catalyst, 21.71...Microcomputer. Patent applicant Hino Motors Co., Ltd., agent Patent attorney Yama 1) Osamu Ya□ (--1)

Claims (3)

[Claims] (1) A particulate filter placed in the middle of an exhaust pipe to collect soot contained in exhaust gas, and a particulate filter placed in the exhaust pipe on the upstream side of the particulate filter with respect to the flow of the exhaust gas. a switching valve; an air supply device that supplies secondary air to the particulate filter; an electric heater disposed on the secondary air inflow side of the particulate filter; Curate
An exhaust gas purification system for use in a diesel engine that includes, downstream of the filter, an oxidation catalyst connected to the exhaust pipe, and a combustion gas switching valve that allows the oxidation catalyst to communicate with the particulate filter. Device. (2) A particulate filter is placed in a casing that is connected in the middle of the exhaust pipe to collect soot contained in the exhaust gas, and a particulate filter is installed in the upstream and downstream sides of the casing with respect to the flow of the exhaust gas. a filter bypass connected to the pipe; an exhaust gas switching valve arranged at the connection point of the exhaust pipe and the filter bypass on the upstream side of the casing with respect to the flow of the exhaust gas; an air supply device connected to the exhaust pipe and supplying secondary air to the particulate filter, downstream of the exhaust pipe and upstream of the connection point between the exhaust pipe and the filter bypass; Regarding the flow of the particulate
an electric heater disposed on the secondary air inflow side of the casing on the upstream side of the filter; an oxidation catalyst connected to the exhaust pipe between the casing and the exhaust gas switching valve; and an oxidation catalyst disposed between the exhaust pipe and the oxidation catalyst. 1. An exhaust gas purification device for use in a diesel engine, including a combustion gas switching valve that allows the oxidation catalyst to communicate with the particulate filter. (3) A particulate filter that is placed in a casing connected to the middle of the exhaust pipe to collect soot contained in exhaust gas, and a particulate filter that branches off from the exhaust pipe on the upstream side of the casing with respect to the flow of the exhaust gas. a branch exhaust pipe connected to the branch exhaust pipe, another particulate filter placed in another casing connected in the middle of the branch exhaust pipe to collect soot contained in the exhaust gas, and an exhaust gas switching valve disposed at the branch point, and a particulate filter connected to the exhaust pipe and the branch exhaust pipe on the upstream side of the casing and other casings with respect to the flow of the exhaust gas; an air supply device for selectively supplying secondary air to the secondary air of the casing and of each of the other casings upstream of the particulate filter and other particulate filters with respect to the flow of the secondary air; an electric heater arranged on the air inflow side; an oxidation catalyst connected to the exhaust pipe and the branch exhaust pipe downstream of the casing and other casings, respectively, with respect to the flow of the exhaust gas; and a connection point of the oxidation catalyst; and a combustion gas switching valve disposed in each of the exhaust pipe and the branch exhaust pipe to enable switching communication of the oxidation catalyst to the particulate filter and other particulate filters. Exhaust gas purification equipment.