JP2000042327A - Reproducing system for exhaust gas purification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily regenerate a filter for exhaust gas purification which is a porous silicon carbide sintered compact disposed in an exhaust passage of an internal combustion engine with an inexpensive device without requiring many sensors, etc., by measuring the deposited particulate amt. of the filter and providing the system with a heater for filter regeneration forward on a gas inflow side and an air supply source for use at the time of regeneration. SOLUTION: Since a back pressure is increased by an increase in the deposition amt. of the particulates, such as soot, the particulate deposition amt. may be recognized by the measuring of the back pressure. The back pressure between the engine 40 and a honeycomb filter 11 at the time of operating the engine 40 is measured by a back pressure sensor 14 and a warning lamp for the need of the regeneration of the filter 11 is lighted when the prescribed back pressure is attained. The porous silicon carbide sintered compact of the honeycomb filter 11 for purification of the regeneration system 10 is excellent in heat resistance and even if the soot is burned with the heater 17 by supplying the air at the time of the regeneration, melting, etc., do not occur and the timing for executing the regeneration may be widely set. The execution of the regeneration at a suitable period is made possible only by monitoring the back pressure. As a result, the easy regeneration with the inexpensive device is made possible without requiring the many sensors, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regeneration system for an exhaust gas purifying apparatus for removing particulates and the like in exhaust gas discharged from an internal combustion engine such as a diesel engine.

[0002]

2. Description of the Related Art Recently, it has become a problem that particulates contained in exhaust gas discharged from internal combustion engines such as vehicles such as buses and trucks and construction machines cause harm to the environment and human bodies. This exhaust gas is passed through a porous ceramic, the particulates in the exhaust gas are collected, and as a ceramic filter that can purify the exhaust gas,
An exhaust gas purifying apparatus using a honeycomb filter made of cordierite (hereinafter, referred to as cordierite filter) has been proposed.

In this exhaust gas purifying apparatus, a cordierite filter is provided in an exhaust passage of an internal combustion engine, and particulates in exhaust gas discharged from the internal combustion engine are captured by a partition wall of the cordierite filter to purify the exhaust gas. Is done.

When such a cordierite filter is used for a long time, particulates mainly composed of graphite (soot) are deposited on the filter, the pressure loss increases, and a load is applied to the engine. Therefore, a process of regenerating the cordierite filter is generally performed by heating the cordierite filter to a high temperature using an electric heater or the like and burning and removing the accumulated particulates.

[0005] However, since the cordierite filter is made of cordierite ceramic having a melting point of about 1200 to 1300 ° C, if the amount of deposited particulates is large, when the particulates are ignited, the cordierite filter is not used. The temperature rises too high, causing the cordierite to melt and break, making it impossible to use it as a filter.

[0006] Even if the amount of accumulated particulates is not so large, if a large amount of air is supplied suddenly to burn the particulates, the temperature locally rises, and a part of cordierite is also melted. Resulting in.

Therefore, in an exhaust gas purifying apparatus using a cordierite filter, regeneration is performed using a cordierite filter regeneration system as shown in FIG. The regeneration system includes a heater 39 for heating the cordierite filter 30 disposed in the exhaust passage of the engine 40, a temperature sensor 38 for measuring the temperature of the cordierite filter 30, A back pressure sensor 36 for measuring a back pressure between the pressure sensor 30 and the engine 30; an engine rotation signal detecting element 32; a valve 35 for sending air during regeneration;
And a blower 33, a temperature sensor 38, and a back pressure sensor 3.
6. Input and output signals from the engine rotation signal detecting element 32, the flow rate sensor 34, etc., perform various calculations, and control the opening and closing of the heater relay 37 connected to the heater 39 in order to adjust the temperature of the heater 39. And a control device 31 having a microcomputer for controlling the flow rate of the blower 33.

[0008] In the regeneration system of the exhaust gas purifying apparatus, the control device 31 is used, and the engine rotation signal detecting element 3 is used.
2, the operation time of the engine 40 is integrated, the pressure signal is read from the back pressure sensor 36, and the cordierite filter 30 is read from these values.
When the amount of accumulated particulates exceeds a certain level, a signal is sent to the driver's seat or the like to operate the regeneration system.

When performing regeneration, the temperature sensor 3
8, the temperature of the cordierite filter 30 is constantly measured, and the flow rate sensor 34 and the back pressure sensor 36 are used to measure the amount of air flowing in and the pressure applied to the cordierite filter 30.

Then, based on these values, the control device 3
The amount of air flowing from the blower 33 by the
5, the particulate matter is burned while the temperature of the heater 39 is controlled by the heater relay 37 and the caution is taken so that the temperature of the cordierite filter 30 does not rise above a certain value.

However, such a reproducing system has to use a control device having various sensors, and there is a problem that the reproducing system itself becomes extremely expensive.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and does not require a large number of sensors or the like, and can easily perform regeneration using an inexpensive apparatus. It is an object of the present invention to provide a regeneration system for a gas purification device.

[0013]

SUMMARY OF THE INVENTION The present invention relates to an exhaust gas purifying apparatus in which an exhaust gas purifying honeycomb filter made of a porous silicon carbide sintered body is installed in an exhaust passage of an internal combustion engine, and a filter that is deposited on the filter. A back pressure sensor for measuring the amount of curate, a heater arranged in front of the gas inflow side of the filter for regenerating the filter, and an air supply source for supplying air during regeneration of the filter. A regeneration system for an exhaust gas purifying apparatus, comprising:

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a regeneration system for an exhaust gas purifying apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a regeneration system for an exhaust gas purifying apparatus according to the present invention. FIG.
As shown in the above, in the exhaust gas purifying apparatus regeneration system 10 of the present invention, an exhaust gas purifying honeycomb filter (hereinafter, referred to as a honeycomb filter) 11 made of a porous silicon carbide sintered body is installed in an exhaust passage of an internal combustion engine. Exhaust gas purifying device 12, a back pressure sensor 14 for measuring the amount of particulates accumulated on the honeycomb filter 11, and a gas inlet side of the honeycomb filter 11 for regenerating the honeycomb filter 11. And a metering pump 16 as an air supply source for supplying air when the honeycomb filter is regenerated.

The engine 40 and the honeycomb filter 1
And a control device 13 for inputting a signal from a back pressure sensor 14 and controlling opening and closing of the valve 15 so that the back pressure with the valve 1 can be measured.
It has.

FIG. 2 is a perspective view schematically showing a honeycomb filter 11 made of a porous silicon carbide sintered body, and FIG. 3 is a schematic view showing a porous silicon carbide sintered body constituting the honeycomb filter 11. 3 is a perspective view shown in FIG.

As shown in FIG. 3, the honeycomb filter 1
1 are provided with a large number of through holes 26, and one end of the porous silicon carbide sintered body 25 having the through holes 26 has a checkerboard-like filling material. 27 are filled. Also, at the other end (not shown), the through hole 2 in which the filler is not filled at one end is provided.
6 is filled with a filler.

FIG. 2 shows a honeycomb filter 11 in which a plurality of the porous silicon carbide sintered bodies 25 shown in FIG. 3 are bound. In FIG. 2, the through holes 26 formed in the porous silicon carbide sintered body 25 are omitted.

In this honeycomb filter 11, a plurality of porous silicon carbide sintered bodies 25 are bound via a heat-resistant adhesive layer 21 and processed into a cylindrical shape, and the outer peripheral portion is coated with a sealing material 23. ing.

As shown in FIG. 3, a plurality of through holes 26 constituting the honeycomb filter 11 are filled with the filler 27 only at one end, so that one open through hole 26 is formed. The exhaust gas that has flowed in from one end always passes through the porous partition wall 28 separating the adjacent through-holes 26 and flows out through the other through-holes 26. Then, when the exhaust gas passes through the partition wall 28, the particulates in the exhaust gas are captured.

Referring to FIG. 1 in more detail, the honeycomb filter 11 configured as described above is housed via an insulating material or the like in an exhaust gas purification device 12 connected to a pipe serving as an exhaust passage. Inside the exhaust gas purifying device 12, a heater 17 capable of heating to a temperature of 600 ° C. or higher is disposed in front of the honeycomb filter 11 on the gas inflow side in order to regenerate the honeycomb filter 11.

Another pipe is connected to the end of the exhaust gas purifying device 12 on the gas inflow side. This pipe has a back pressure sensor 14 for measuring the amount of particulates accumulated on the honeycomb filter 11 and a back pressure sensor 14. , A valve 15 for maintaining the confidentiality of the piping section to enable back pressure measurement,
A metering pump 16 as an air supply source for supplying air during honeycomb filter regeneration is connected.

Heater 17, back pressure sensor 14, and valve 1
As 5, the same one as conventionally used can be used. Although the metering pump 16 is provided in FIG. 1, the metering pump 16 only has to function as an air supply source, and it is not necessary to strictly supply a constant flow of air at the time of regeneration. This is because the honeycomb filter 11 is made of the porous silicon carbide sintered body 25 and therefore has extremely excellent heat resistance, and the temperature of the honeycomb filter 11 during reproduction is, for example, about 1200 ° C.
This is because there is no problem even if the temperature becomes higher than the normal combustion temperature. Therefore, other air supply means such as an air compressor or a blower may be provided instead of the metering pump 16.

Next, a regeneration method using the regeneration system of the exhaust gas purifying apparatus of the present invention will be described. First,
The back pressure between the engine 40 and the honeycomb filter 11 when the engine 40 is operating is measured using the back pressure sensor 14. The back pressure increases as the amount of particulates such as graphite (soot) increases. Therefore, if the relationship between the back pressure and the amount of particulates is known, the amount of particulates deposited can be determined from the back pressure. be able to.

The data relating to the amount of the accumulated particulates is lower in accuracy than the case where the amount of the particulates is calculated from the data such as the number of revolutions of the engine, as in the conventional case. There is no problem as long as the amount can be grasped. Normally, when the back pressure sensor 14 detects that the back pressure has reached a predetermined pressure, a warning lamp for informing the driver's seat panel that regeneration is necessary is lit.

FIG. 4 shows a particulate filter in a honeycomb filter 11 (FIG. 1) composed of a porous silicon carbide sintered body 25 and a conventional honeycomb filter 30 (FIG. 6) composed of a porous cordierite. It is a graph which shows the relationship between the accumulation amount and the regeneration rate.

In the case of the honeycomb filter 11 of the present invention, when the accumulation amount of the particulates is in the range of a to b, the regeneration rate becomes almost 100%. Such a ~
The range (A) of b is called a reproduction window. If the accumulation amount is smaller than a, soot remains unburned, and if the accumulation amount is larger than b, the particulates are excessively accumulated in the partition walls, so that it becomes difficult for the air to pass through the inside of the honeycomb filter 11 and the soot is burned. It becomes difficult, and afterburn also occurs.

On the other hand, in the case of the conventional honeycomb filter 30, when the width B of the reproduction window is narrow, that is, c to d, and when the accumulation amount is smaller than c, soot remains unburned and the accumulation amount becomes d.
If it is larger than this, the temperature becomes too high during soot combustion, a melting phenomenon occurs, and the honeycomb filter 30 is damaged. For this reason, in the conventional honeycomb filter 30, it is necessary to accurately grasp the amount of accumulated particulates.

In the regeneration system 10 of the exhaust gas purifying apparatus of the present invention, since the porous silicon carbide sintered body 25 is used, the width of the regeneration window is wide and the porous silicon carbide sintered body 25 is melted. No phenomena occur. Therefore, it is only necessary to monitor the back pressure using only the back pressure sensor 14,
The period for performing the reproduction can be set widely.

Therefore, unlike the conventional case, there is no need to always pay attention so as not to miss the timing of the reproduction, and the reproduction can be performed at an appropriate time without difficulty. Also, as in the past, to know exactly when playback is happening,
It is not necessary to provide a sensor or the like for measuring the operating state of the engine. During regeneration, the flow rate of the air is controlled by constantly monitoring the temperature of the honeycomb filter 30 with a flow rate sensor or a temperature sensor. There is no need to perform particulate combustion.

That is, in the present invention, while supplying electricity to the heater 17, it is only necessary to flow air at a flow rate of about 10 to 100 liters / minute using a quantitative pump or the like. Can be easily reproduced.

FIG. 5 is a block diagram showing another embodiment of the regeneration system of the exhaust gas purifying apparatus of the present invention. The regeneration system 20 of the exhaust gas purifying apparatus shown in FIG. 5 is configured similarly to the regeneration system shown in FIG. 1 except that a temperature sensor 18 is further provided.

The reason why the temperature sensor 18 is provided is that the voltage applied to the heater 17 is lower than usual due to the surrounding environment or that the temperature of the outside air is low. This is provided in consideration of a case where the temperature of the heater 17 does not rise to a predetermined temperature. Therefore, the temperature of the heater 17 is measured, and when the temperature of the heater 17 is lower than normal, the voltage applied to the heater 17 is controlled so that the temperature of the heater 17 becomes 600 ° C. or more.

As described above, in the regeneration system of the exhaust gas purifying apparatus of the present invention, when it is necessary to control the temperature of the heater 17 by controlling the voltage applied to the heater 17, the honeycomb filter can be used. A temperature sensor 18 may be provided in addition to the provided exhaust gas purification device 12, back pressure sensor 14, heater 17, and air supply source.

[0036]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 An organic binder, water and the like were added to silicon carbide powder, kneaded, extruded to form a honeycomb-shaped formed body, and subsequently dried, degreased, and fired. 2, the average pore diameter is 5 to 20 μm, the number of cells per square inch is 200, and the partition wall thickness is 0.3
mm of porous silicon carbide sintered body 25 was prepared.

Next, this porous silicon carbide sintered body 25 is
By bundling a large number using a heat-resistant adhesive containing inorganic fibers such as ceramic fibers or inorganic particles such as silicon carbide, and then cutting using a diamond cutter, the diameter as shown in FIG. The honeycomb filter 11 having a length of 165 mm and a length of 150 mm was formed, and a layer of the sealing material 23 having the same composition as the heat-resistant adhesive was formed on the outer peripheral portion.

An exhaust gas purifying device for a forklift is manufactured by using the honeycomb filter 11 manufactured by the above-described method, and subsequently, a fixed-quantity pump or the like is attached to the forklift, so that the forklift has the same configuration as that shown in FIG. A regeneration system 10 for the exhaust gas purifying apparatus is provided.

Next, this forklift was operated for 8 hours with the engine at the maximum speed under no load, and the back pressure was measured by the back pressure sensor 14.
Aq. The value of was shown. At this time, the honeycomb filter 11
Had 60 g of particulates deposited thereon.

Then, a voltage was applied to the heater 17, the temperature of the heater 17 was set to 850 ° C., and air was flowed at a flow rate of 40 liters / minute for 45 minutes using a metering pump. Can be completely burned, and the back pressure is also the initial value of 700 mmAq. Was back. When the honeycomb filter 11 was inspected, no crack, breakage, or the like was observed.

Comparative Example 1 In place of the honeycomb filter 11, a cordierite honeycomb filter 30 of the same shape (100 cells per square inch and a partition wall thickness of 0.43 mm) was installed. Example 1 except that the sensor 18 was installed.
A regenerating system for an exhaust gas purifying apparatus was constructed in the same manner as described above, and particulates were deposited under the same conditions as in the example.

Thereafter, as in the case of the first embodiment, a voltage is applied to the heater 17, the temperature of the heater 17 is set at 850 ° C., and air is supplied at a flow rate of 40 liter / min for 45 minutes using a metering pump. After flowing, the honeycomb filter 11
Increased to 1200 ° C., which caused cordierite to melt and break.

[0044]

Since the regeneration system of the exhaust gas purifying apparatus of the present invention is as described above, it does not require many sensors and the like and can easily perform the exhaust gas purifying using an inexpensive apparatus. An apparatus playback system can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing one embodiment of a regeneration system for an exhaust gas purifying apparatus of the present invention.

FIG. 2 is a perspective view schematically showing a honeycomb filter constituting the exhaust gas purifying apparatus in the exhaust gas purifying apparatus regeneration system of the present invention.

FIG. 3 is a perspective view schematically showing a porous silicon carbide sintered body constituting the honeycomb filter shown in FIG.

FIG. 4 is a graph showing the relationship between the amount of particulates deposited on a honeycomb filter constituting an exhaust gas purification device and the regeneration rate.

FIG. 5 is a block diagram schematically showing another embodiment of the regeneration system of the exhaust gas purifying apparatus of the present invention.

FIG. 6 is a block diagram schematically showing one embodiment of a conventional regeneration system for an exhaust gas purification device.

[Explanation of symbols]

 Reference Signs List 10, 20 Exhaust gas purifier regeneration system 11 Honeycomb filter 12 Exhaust gas purifier 13 Controller 14 Back pressure sensor 15 Valve 16 Metering pump 17 Heater 18 Temperature sensor 25 Porous silicon carbide sintered body

Continued on the front page F-term (reference)

Claims (1)

[Claims] An exhaust gas purifying honeycomb filter comprising a porous silicon carbide sintered body is provided in an exhaust gas purifying apparatus provided in an exhaust passage of an internal combustion engine, and an exhaust gas purifying honeycomb filter is provided for measuring an amount of particulates deposited on the filter. Exhaust gas, comprising: a back pressure sensor; a heater disposed in front of a gas inflow side of the filter for regenerating the filter; and an air supply source for supplying air during regeneration of the filter. Regeneration system for gas purification equipment.