JPS63198717A - Internal combustion engine exhaust particle removal device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Field of Application in Industry 1-> The present invention relates to a device that collects, burns, and removes particles such as soot and carbon powder contained in the exhaust gas of internal combustion engines such as diesel engines. .

<Prior Art and its Problems> For diesel engines, a known technique is to provide a filter made of ceramic foam or the like in the exhaust passage to collect soot particles contained in the exhaust gas.

However, the particles collected by the filter will not burn unless they are heated to a temperature of about 600° C. or higher. In addition, in diesel engines, the temperature of the exhaust gas during operation is usually about 40°C.
The temperature is below 0°C, and it rarely becomes 1- above 600°C.

Therefore, since the particles trapped in the filter are hardly combusted by the heat of the exhaust gas, the filter will become clogged with the trapped particles.

Therefore, a particulate removal device is required to burn and remove the particles collected by the filter.

First Conventional Example This 13"-j particle removal device removes particles from a large diameter portion of the exhaust passage 22 of a diesel engine 21, as shown in FIG.
A collection filter 23 is provided, and the filter 2 of the exhaust path 22
3 Connecting the detour 24 between the upstream position and the downstream position,
A 9J switching valve 25 for switching the flow of exhaust gas to the exhaust path 22 side or the detour path 24 side is provided at the entrance 1 of the detour path 24.

A combustion chamber 26 is provided on the population side of the filter 23, and a fuel spray nozzle 27 for spraying fuel from the diesel engine 21 toward the filter 23 is provided in the combustion chamber 26, and an air supply for supplying air for combustion. A spark plug 29 for igniting the mixture of fuel and air is connected to the passage 28, and a pressure detector 30 for detecting the pressure in the combustion chamber 26 is provided.

In this exhaust particle removal device, the exhaust gas normally flows through the exhaust path 22 in which the filter 23 is located, and as the amount of particles collected by the filter 23 increases, the pressure loss due to the filter 23 increases by 4 Jl. Increased combustion chamber 2
When the pressure in the combustion chamber 26 increases and the pressure in the combustion chamber 26 reaches a predetermined value, that is, when the filter 23 becomes clogged with trapped particles, the pressure detector 30 outputs an output.

Then, the 11f raw operation of the filter 23 starts, and! /j
When the diversion jf 25 is activated, the flow of exhaust gas is switched from the exhaust path 2z side to the detour path 24 side, and the flow is changed to the combustion chamber 26.
Fuel is supplied from the fuel spray nozzle 27 and air is supplied from the air supply path 28 to form a mixture of fuel and air. This mixture is ignited by the ignition plug 29 and combusts, creating a flame in the combustion chamber 26. Occur. This flame burns the particles -γ collected in the filter 23, and the filter 23 is cleared of clogging, and the filter 23 is formed.

However, in this exhaust particle removal device, the combustion chamber z
Since the filter 23 is heated by the flame generated at step 6, it is difficult to uniformly heat the entire filter 23 to a temperature of q1. Therefore, the temperature of each part of the filter 23 becomes non-uniform, and particles are burned in the low-temperature part of the filter 23, while damage occurs due to overheating in the high-temperature part of the filter 23.

Also,',! + When the fire plug 29 is used for a long period of time, soot etc. accumulate and the ignition performance deteriorates [7. Then, a flame is generated in the combustion chamber 26 +iij
4. 2. A large amount of fuel reached the filter 23 and adhered to the filter 23, and then a flame was generated at one point, and the fuel that had landed on the filter 23 burned, causing the fuel to adhere to the filter 23. is overheated and damage occurs.

Second Conventional Example This exhaust particle removal device uses an electric heater 31 as shown in FIG. It is attached to the 11th large side of the .

When the output of the pressure detector 30 starts the 1V operation of the filter 23 in the same manner as in the previous device, the electric heater 31 is activated, and the heat of the upper heater 31 causes the filter z3 to collect on the person 11 side. The particles are combusted, and the combustion of the particles is sequentially propagated to the filter 23 by the combustion heat, and the particles collected in each part of the filter 23 are combusted.

However, in order to burn the particles in each part of the filter 23 in 1 minute, it takes 1 heat generation. It requires an electric heater with a lot of power, and requires a large amount of electricity.

Third Conventional Example This exhaust particle removal device uses the fuel spray nozzle 27 in the device of the first conventional example. In place of the air supply path 28 and the spark plug 29, as shown in FIG. 7, an air spray nozzle 42 is provided which sprays a solution 41 containing catalyst metal ions that lower the combustion temperature of particles using an air stream. ing.

That is, the air spray nozzle 4 facing the population of the filter 23
2, the catalyst solution 41 is supplied by the catalyst supply path 43 with a pump.
A tank 44 is connected to the tank 44, and an air supply path 4 with a pump is connected.
5 is connected.

When the regeneration operation of the filter 23 is started in accordance with the output of the pressure detector 30 in the same manner as in the first conventional device, the catalyst solution 41 is transferred from the air spray nozzle 42 to the filter 23.
The combustion temperature of the particles that have been atomized and collected by the filter 23 is reduced to about 300° C. by the catalyst, and the particles are combusted.

However, in this device, a catalyst solution 41 is not provided in addition to the combustion engine 1 of the diesel engine.
As the installation becomes larger, the catalyst solution 41 must be periodically replenished, similar to the feedstock in a diesel engine.

Further, a part of the catalyst solution 41 sprayed by the air spray nozzle 42 passes through the filter 23 and is released into the atmosphere, causing new air pollution due to the catalyst.

The main purpose of the present invention is to solve the conventional problems as described in 1-.

Points of focus for solving the problems> In order to achieve [Objective 1] of -4-, first of all,
After examining the three types of conventional devices described in section 1, we found that the device of the first conventional example using fuel from a diesel engine was superior. In improving the device, we focused on the following points.

1) When the fuel of a diesel engine is combusted using a catalyst, it is more uniformly combusted than combustion using a flame in the first conventional device.

2) When using a noble metal catalyst such as platinum, palladium, or rhodium, diesel engine fuel can reach a temperature of 250 to 300°C.
Combustion begins at a temperature of about

3) During normal operation of a diesel engine, the exhaust gas temperature easily reaches 250 to 300°C.

4) Therefore, when fuel is sprayed onto a noble metal catalyst heated by exhaust gas, combustion begins.

Means for Solving the Problems> The present invention provides a filter for collecting particles in the exhaust gas in the exhaust path of an internal combustion engine.

A catalyst body that lowers the combustion temperature of the following fuel is provided at a position on the inlet 11 side or outlet side of the filter that is heated by the exhaust gas from the exhaust passage, and a catalyst body that lowers the combustion temperature of the fuel described below is installed on the side opposite to the filter side of the catalyst body to mix fuel and air. Set up a room.

A fuel spray nozzle for spraying the fuel of the internal combustion engine onto the catalyst body is installed in the mixing chamber, and an air supply path is connected to the mixture chamber, and the particles collected by the filter are used to burn the fuel using the catalyst body. This is an exhaust particle removal device for an internal combustion engine, characterized in that it is configured to perform combustion using heat generated by the combustion engine.

<Operation and Effects of the Invention> In the exhaust particle removal device for an internal combustion engine that has not yet emitted IJI,
The particles collected by the filter are combusted by the heat generated by combustion of the combustion engine 1 of the internal combustion engine using a catalyst heated by exhaust heat.

Therefore, since the heat of combustion using a catalyst is used to burn the particles collected by the filter, the particles collected in each part of the filter are uniform compared to the first conventional device that uses the heat of combustion by flame. It is difficult to cause damage due to insufficient combustion of collected particles or overripening of the filter.

Further, since a spark plug is not required, there is no problem caused by deterioration in the performance of the spark plug as in the first conventional device using a spark plug.

Further, since an electric heater is not required, unlike the second conventional device using an electric heater, no electric power is consumed.

Furthermore, since the fuel of the internal combustion engine is used for combustion of the collected particles and no catalyst solution is used, unlike the third conventional apparatus which uses a catalyst solution, there is no problem mentioned above due to the use of a catalyst solution. .

First Embodiment> As shown in FIG. 1, the exhaust particle removal device for an internal combustion engine of this example includes a filter for collecting particles in the exhaust gas in the large l-\ section of the exhaust path 2 of the diesel engine l. 3 is installed.

The filter 3 has a honeycomb structure made of porous cordierite, and has 200 flow passages per medium inch between the input and output sides, and the passages between the input and output sides of each wave passage. Either one of the eyes is closed, and wave channels with closed entrances and flow channels with closed exits are arranged alternately.

Therefore, the exhaust gas passing through the filter 3 flows into the channel with one opening and the outlet closed, passes through the porous wall of that channel, and exits into the adjacent channel, i.e., with the inlet closed. [1.1 flows into the open channel, and 1. When the exhaust gas containing 0 particles flowing out from i'l passes through the porous wall of the wave path of the filter 3, the particles are collected on the porous wall and removed.

As shown in FIG. 1, a detour 4 is connected between the upstream and downstream positions of the filter 3 in the exhaust path 2, and the exhaust flow is directed to the exhaust path 2 to the detour 4. Or, the switching valve 5 for switching to the detour route 4 is sunk.

As shown in FIG. 1, in the large diameter portion of the exhaust passage 2, a catalyst body 6 having a honeycomb structure having the same diameter as the filter 3 is installed concentrically with the filter 3 with a gap provided on the inlet side of the filter 3. There is.

The catalyst body 6 is a honeycomb structure carrier made of cordierite.
It is coated with alumina and supports the catalytic metal platinum.

The carrier having a honeycomb structure has 200 wave channels per square inch between the first side and the first side.

Six catalyst bodies [-1 side of the exhaust passage 2, as shown in FIG. are doing.

In the center of the small diameter end of the mixing chamber 7, as shown in FIG.
An air spray nozzle 8 for spraying the fuel of the diesel engine 1 using an air stream is installed concentrically facing the catalyst body 6.

That is, a fuel supply path IO with a pump 9 and an air supply path 2 with a pump 11 are connected to the air flow spray nozzle 8, which is a type of fuel spray nozzle. In addition, on the circumference 11t of the mixing chamber 7, an air supply path 13 with a throttle branched from the downstream side of the pump 11 of the air supply path 12 is connected to a position immediately before the air spray nozzle 8, so that the air spray nozzle 8 can spray the air. The fuel is distributed almost uniformly on the lateral surface of the catalyst body 6.

As shown in the first factor, the mixing chamber 7 is equipped with a pressure detector 14 which outputs an output in order to start the ILT operation of the filter 3 when the pressure in the mixing chamber 7 reaches a constant value.

In the exhaust particle removal device for the internal combustion engine 1t1 of this example,
1F is like 11! For N, catalyst body 6 and filter 3
The catalyst body 6 is heated by the exhaust gas, and particles in the +Jl air are collected by the filter 3.

As the amount of particles collected by the filter 3 increases, the pressure in the mixing chamber 7 increases, and when the pressure in the mixing chamber 7 reaches +iQ, that is, the filter 3 becomes overwhelmed by the collected particles. The pressure detector 14 outputs this.

Then, the IIf raw operation of filter 3 starts at 1511,
! /J exchange valve 5 operates, and the flow of exhaust gas is directed to exhaust path 2 (I
Switching from ll to detour 4, and into mixing chamber 7,
Fuel is atomized by an air stream from the air spray nozzle 8, and air is supplied from the air supply path 13 to form a mixture of fuel and air, and this mixture is distributed almost uniformly on the inlet surface of the catalyst body 6. The fuel adhering to the catalyst body 6 heated by the exhaust gas is combusted, and the inlet surface of the filter 3 is almost uniformly heated by the heat of this combustion.
The particles trapped in the filter 3 are burned, and the filter 3
11 blockages will be resolved.

Diesel engine 1 with exhaust j14 in experiment 2.21 has approximately 3
．． It was operated at a constant rotation speed of 000 rpm.

Immediately after the start of operation, the pressure in the mixing chamber 7 is detected by the pressure detector 14.
According to , it was about 100l1Hg.

Immediately after 15 hours of continuous operation, the pressure in the mixing chamber 7 was approximately 200+smHg according to the pressure detector 14.

Therefore, the regeneration operation of the filter 3 is started, and the flow of exhaust gas is diverted to the bypass route 4 by operating the switching valve 5, as described in "-".
By switching to the side and operating the air spray nozzle 8, a mixture was formed in the mixing chamber 7, and this mixture was sprayed onto the catalyst body 6. The air-fuel mixture had a blowing speed of Q per second, 3 m, and an excess air ratio of about 4.

As shown in FIG. 1, there is a point A at the front side of the center of the inlet face of the catalyst body 6, a point B at the center position of the gap between the catalyst body 6 and the filter 3, and a point 0 at the center position of the filter 3. The temperature at each point was measured by a thermocouple, and the pressure in the mixing chamber 7 was measured by a pressure detector 14. The results of these measurements are shown in the diagram of FIG.

As is clear from this diagram, after the start of the IIf operation of the filter 3, the temperature at point A on the front side of the catalyst body 6 gradually increases but does not change significantly, whereas the temperature of the catalyst body 6 and the filter The temperature at point B between 3 and point 0 inside the filter 3 rose rapidly, indicating that the filter 3 was heated by the heat generated by combustion of the fuel in the catalyst body 6.

Further, the pressure in the mixing chamber 7 increased by -1-1- and then decreased, indicating that the ventilation resistance, that is, the clogging of the filter 3, decreased.

After regenerating the filter 3 for 3 minutes, the switching valve 5 was returned to its original position and the operation of the air spray nozzle 8 was stopped. The pressure detector 14 again showed a pressure of about 100 mmHH, and the filter 3 was born at 11f.

In addition, when the diesel engine 1 was continuously operated and the pressure in the mixing chamber 7 increased to over 200 tamHg, the operation of the diesel engine 1 was stopped and the catalyst body 6 was taken out and examined. A small amount of particles were observed on the road wall.

The catalyst body 6 was returned to its original position, the diesel engine 1 was restarted, and the filter 3 was regenerated. When the catalyst body 6 was again taken out and examined, it was found that the catalyst body 6
No particle adhesion was observed not only on the wall of the wave channel but also on other parts. Therefore, the adhesion of particles to the catalyst body 6 is 1
It turned out to be no problem.

I repeated the regeneration operation of filter 3 many times, but
After the filter 3 is regenerated, the pressure detection 'J:iia
showed a nearly constant pressure around 100+smHg.

Second Embodiment> The exhaust particle removal device for an internal combustion engine of this example introduces exhaust gas into the inlet side of the catalyst body 6 in the previous example, whereas the exhaust gas is introduced into the inlet side of the catalyst body 6 as shown in FIG. and the catalyst body 6. Filter 3 and catalyst body 6
A pressure detector 14 is added to the gap between the two, which outputs an output when the pressure in the gap reaches a set value.

The other points are almost the same as in the case of the third case.
The same symbol (-) is attached to the figure.

Third Embodiment The exhaust particle removal device for an internal combustion engine of this embodiment is different from the first embodiment in which the exhaust gas is passed through the mixing chamber 7, the catalyst body 6, and the filter 3 in this order.

As shown in FIG. 4, the exhaust gas is configured to flow in the order of the filter 3, the catalyst body 6, and the mixing chamber 7, that is, in the reverse direction. At the exit of the detour path 4, the exhaust flow is passed through a filter 3 and a catalyst body 6.
A νJ switching valve 5 is provided on the exhaust path 2 side or the detour path 4 side, and a pressure detector 14 is installed at a position upstream of the filter 3 in the exhaust path 2, which outputs an output when the pressure at that position reaches a set value. ing.

The other points are almost the same as those in the ml example, and the catalyst body 6 contains one or more noble metals such as platinum, palladium, and rhodium. Supported materials are the best because they have high activity at low temperatures.

However, since XIL metal catalysts are expensive, they are used in combination with catalysts supporting metal oxides such as ferric oxide, cobalt oxide, and nickel oxide.
The metal oxide catalyst may be placed on the spray nozzle side and the metal oxide catalyst body on the filter side. In this way, the precious metal catalyst body? It is cheaper and exhibits similar catalytic performance compared to when used alone.

The 4!1 catalyst body has a honeycomb structure, which is excellent because of its low ventilation resistance, but it may also have a foam with porous chambers.

As for the fuel spray nozzle 8, although an airflow spray nozzle has excellent atomization performance, it may be a pressure spray nozzle, an ultrasonic spray nozzle, or the like.

[Brief explanation of the drawing]

FIG. 1 shows exhaust particles of an internal combustion engine according to a first embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view of the removal device. Figure 2 shows points A, B and 0 in the same exhaust particle removal device.
FIG. 2 is a diagram showing temperature changes at points and pressure changes in a mixing chamber. FIG. 3 is a partially schematic cross-sectional view of an exhaust particle removal device for an internal combustion engine according to a second embodiment. FIG. 4 is a schematic cross-sectional view of an exhaust particle removal device for an internal combustion engine according to a third embodiment. FIG. 5 is a schematic cross-sectional view of a first conventional example of an exhaust particle removal device for an internal combustion engine. FIG. 6 is a schematic cross-sectional view of a second conventional example of an exhaust particle removal device for an internal combustion engine. FIG. 7 is a schematic cross-sectional view of a third conventional example of an exhaust particle removal device for an internal combustion engine. l: Diesel engine, internal combustion engine 2: Exhaust passage 3: Filter 6: Catalyst body 7: Mixing chamber 8: Fuel spray nozzle, air spray nozzle 12: '-ζ air supply passage 13: Air supply passage Patent applicant Corporation: Deputy Director of ru Central Research Institute
Person Patent attorney To Katsura Mizuno 7'2 Figure 0 0.5 1 1.5 Time [minutes] Figure 7'3 Figure 4

Claims (1)

[Claims] 1) A filter for collecting particles in the exhaust gas is provided in the exhaust passage of the internal combustion engine, and the following is installed on the inlet side or outlet side of the filter at a position heated by the exhaust gas in the exhaust passage. A catalyst body that lowers the combustion temperature of the fuel is provided, a mixing chamber for fuel and air is provided on the side opposite to the filter side of the catalyst body, a fuel spray nozzle is provided in the mixing chamber to spray fuel from the internal combustion engine onto the catalyst body, Further, there is provided an exhaust particle removal device for an internal combustion engine, characterized in that an air supply path for supplying air is connected, and the particles collected by the filter are combusted by heat generated by combustion of fuel using a catalyst body. . 2) The exhaust particle removal device for an internal combustion engine according to claim 1, wherein the catalyst body supports one or more noble metals such as platinum, palladium, and rhodium. 3) The catalyst body consists of a catalyst body that supports one or more noble metals such as platinum, palladium, and rhodium, and a catalyst body that supports metal oxides such as ferric oxide, cobalt oxide, and nickel oxide, 2. The exhaust particle removal device for an internal combustion engine according to claim 1, wherein the former catalyst body is disposed on the fuel spray nozzle side, and the latter catalyst body is disposed on the filter side. 4) The exhaust particle removal device for an internal combustion engine according to claim 1, 2 or 3, wherein the carrier of the catalyst body has a honeycomb structure. 5) The exhaust particle removal device for an internal combustion engine according to any one of claims 1 to 4, wherein the fuel spray nozzle is an airflow spray nozzle that sprays fuel using an airflow.