JPH0868314A - Structure of diesel particulate filter - Google Patents

Abstract

(57) [Abstract] [Purpose] In the structure of a diesel particulate filter, the main filter is satisfactorily regenerated, and overheat is prevented in the regeneration process. According to the present invention, a main filter 1 arranged in an exhaust system of a diesel engine and a sub filter 2 arranged in the center thereof. A bypass valve 9 is arranged on the exhaust gas inflow side of the sub filter 2, and an opening / closing valve 5 is arranged on the exhaust gas inflow side of the main filter 1.
To place. The tubular valve body that constitutes the on-off valve 5 has a throttle portion 31 extending inward in the radial direction and a through hole 8 communicating with the main exhaust gas passage 12 at the downstream end portion. On-off valve 5
Is configured to open the through hole 8 to the main exhaust gas passage 12 by the spring force of the spring 25 and to restrict the throttle portion 3 by the flow rate of the exhaust gas flowing in the bypass passage 14 that resists the spring force of the spring 25.
The opening to the main exhaust gas passage 12 is automatically adjusted by the resistance of 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a diesel particulate filter that collects exhaust gas discharged from a diesel engine by a filter and heats and incinerates it.

[0002]

2. Description of the Related Art Conventionally, a diesel particulate filter using a porous filter as an exhaust gas treatment device for treating engine exhaust gas has a large particulate collection area of the filter, and the filter has a large particulate collection area. It is accumulated and collected. In order to incinerate the accumulated particulates, a heater is attached to the surface of the filter, and when the amount of particulates accumulated exceeds a specified standard, an electric current is passed through the heater to incinerate the particulates and regenerate the filter. There is.

Conventionally, Japanese Patent Application Laid-Open No. 2-256812 discloses an electrically regenerable particulate trap. The particulate trap comprises a gas permeable support, a fiber layer composed of a plurality of ceramic fibers, and a heater, the fiber layer is arranged together with the heater in a space extending in the radial direction from the gas permeable support, and the gap between the fiber layers is provided. The exhaust gas is caused to flow to collect the particulates in the exhaust gas in the vicinity of the heater, and the heater is energized to incinerate the collected particulates. The ceramic fiber is selected from continuous fused silica, glass, alumina silica, zirconia silica, alumina chromia, titania, graphite, silicon carbide, and alumina boria silica. Further, the ceramic fibers are braided or wound directly onto the gas permeable support or heater.

[0004]

By the way, since the diesel particulate filter is mounted on a vehicle or the like,
Construct as compact as possible, carbon, soot, HC
It is necessary to configure so as to efficiently collect the particulates such as. Particulates react with oxygen and burn easily, but a high temperature is required for burning, and it is not possible to burn completely with the exhaust gas temperature alone. A conventional renewable diesel particulate filter has two filters of the same size arranged in parallel in the exhaust gas flow, and when one filter becomes clogged by the collection of particulates, the other filter is made to flow exhaust gas,
Air required for incineration of particulates is sent to the clogged filter to heat the filter, and the collected particulates are incinerated to regenerate the filter.

Regarding a diesel particulate filter having a main filter and a bypass filter, that is, a sub filter, when particulates in exhaust gas are accumulated on the main filter and the sub filter, the main filter and the sub filter are screened. Need to play. The most reliable method for regenerating the main filter and the sub-filter is to energize a heater disposed on the upstream side of the exhaust gas to heat it to about 600 ° C. or higher and heat and incinerate the particulates.

However, in order to regenerate the filter,
If air is flowing through the filter when the heater is energized, the heated heater such as a wire net will not be cooled and the temperature will not rise, and a state in which the particulates cannot be heated and incinerated occurs. Further, if no air flows through the filter being regenerated, O ₂ will not be supplied and the particulates will not be heated and incinerated. Further, the particulates deposited on the filter are incinerated with the heating of the heater such as a wire net, and as the incineration of the particulates progresses, the trapped particles of the filter become coarser, the air resistance of the filter becomes smaller, and the air in the filter becomes smaller. It tends to flow, causing a drop in temperature.

An object of the present invention is to solve the above-mentioned problems, and a main filter and a sub filter for collecting particulates such as carbon, soot and HC contained in exhaust gas discharged from a diesel engine. With a filter,
An on-off valve that opens and closes the main exhaust gas passage of the main filter and a bypass valve in the bypass passage of the sub filter are installed, and the opening degree of the main exhaust gas passage is automatically adjusted according to the flow rate of exhaust gas flowing through the on-off valve to the bypass passage. Can be adjusted to
When opening the bypass valve and regenerating it to the main filter, the opening / closing valve restricts the opening of the main exhaust gas passage to prevent excessive air from being sent to the main filter, preventing the main filter from being overcooled. It is an object of the present invention to provide a diesel particulate filter structure capable of completing filter regeneration.

[0008]

In order to achieve the above object, the present invention is constructed as follows. That is, the present invention collects the particulates contained in the exhaust gas by the filter arranged in the exhaust system of the diesel engine, and the structure of the diesel particulate filter that heats and incinerates the particulates collected by the filter, A main filter arranged in the exhaust gas passage, a sub-filter arranged parallel to the exhaust gas flow with respect to the main filter, a bypass valve for opening and closing the sub-filter arranged on the exhaust gas inflow side of the sub-filter, and A diesel particulate filter, which is arranged on the exhaust gas inflow side of the main filter and comprises an on-off valve that automatically adjusts the opening degree of the main filter according to the flow rate of exhaust gas passing through the sub filter. Concerning the structure of.

In the structure of this diesel particulate filter, the on-off valve slides around a support pipe connected to the sub-filter, and has a throttle portion extending radially inward at the downstream end and the main exhaust gas passage. A through-hole communicating with the tubular valve body forming the on-off valve is opened in the main exhaust gas passage by the spring force of a spring, and the tubular valve body is opened by the opening of the bypass valve. The opening degree of the main exhaust gas passage is operated by the flow resistance of the throttle portion due to the flow rate of exhaust gas flowing through the bypass passage against the spring force of the spring.

In the structure of this diesel particulate filter, the spring is arranged between the throttle portion of the on-off valve and the projection provided on the support pipe. Alternatively, the spring is arranged between a protrusion provided on the outer periphery of the on-off valve and a case forming the exhaust gas passage.

In the structure of this diesel particulate filter, the filter body constituting the main filter and the sub-filter is SiC or SiC with Ti, T
The filter main body is formed by laminating ceramic long-fiber materials to which additives such as a are added, and the filter main body is formed in a cylindrical shape, and a wire mesh forming a heater is arranged on the surface of the filter main body.

[0012]

The structure of the diesel particulate filter according to the present invention is configured as described above and operates as follows. That is, the structure of this diesel particulate filter has a main filter arranged in the exhaust gas passage, a sub-filter arranged in the central portion of the main filter,
The main filter is composed of a bypass valve arranged on the exhaust gas inflow side of the sub filter and an on-off valve that automatically adjusts the opening degree to the main exhaust gas passage according to the flow rate of exhaust gas passing through the sub filter. When the bypass valve is opened for the regeneration process, the air resistance of the sub-filter is smaller than that of the main filter.
Most of the exhaust gas will flow to the sub-filter, so the exhaust gas is throttled by the throttle part of the on-off valve, pressure loss acts individually, and the on-off valve slides to move the on-off valve. The opening degree to the main exhaust gas passage is narrowed down, and a slight amount of exhaust gas is made to flow to the main filter, whereupon the main filter can be energized to perform the regeneration process of the main filter. At the same time, the exhaust gas is purified by the sub filter.

Further, as the regeneration of the main filter progresses, particulates accumulate on the sub-filter, the flow rate of exhaust gas to the sub-filter decreases, and the resistance of the on-off valve to the throttle portion decreases. The opening and closing valve is pushed back by the spring force of the spring, the opening of the through hole of the opening and closing valve to the main exhaust gas passage is increased, and exhaust gas starts to flow to the main filter. The particulates accumulated on the main filter burn and generate heat, but the exhaust gas can prevent the main filter from being overheated by flowing to the main filter.

In the structure of this diesel particulate filter, the main body of the filter is composed of the main filter and the sub-filter, and the wire mesh forming the heater is arranged on the exhaust gas inflow side. Therefore, when the main filter is regenerated, the on-off valve is opened. Is closed and the bypass valve is opened, a small amount of exhaust gas is flown through the main filter to energize the wire net, and the O gas for burning particulates trapped in the main filter is discharged.
₂ can be supplied, and the particulates will be heated and burned. When the bypass valve is closed and exhaust gas is allowed to flow through the main filter, the exhaust gas leaking from the bypass valve flows through the sub-filter, and the particulates collected by the sub-filter at the time of regeneration of the main filter are Similarly, it is supplied to the sub-filter, and since the sub-filter is arranged inside the main filter,
The filter structure itself can be made compact.

[0015]

Embodiments of the structure of a diesel particulate filter according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the structure of a diesel particulate filter according to the present invention.

This diesel particulate filter is arranged in the exhaust system of a diesel engine and is capable of trapping particulates such as carbon, soot and smoke contained in exhaust gas and heating and incinerating the trapped particulates. And a case 21 connected to an exhaust pipe (not shown) of a diesel engine via a flange 23.
have. In the exhaust gas passage 22 formed in the case 21, the main filter 1 and the sub-filter 2 capable of collecting particulates are separated by the bypass cylinder 4 in the exhaust gas flow direction and are concentrically formed into the exhaust gas flow. They are arranged in parallel so as to extend from the inlet side to the outlet side. Further, the main filter 1 is composed of an inner cylinder 19 and an outer cylinder 20 which are cylindrical bodies which are concentrically and in parallel with each other in an exhaust gas flow and which are doubly stacked.

Except for the inlets 15 and 16 of the main filter 1 and the sub-filter 2 and the outlets 17 and 18 of the main filter 1 and the sub-filter 2, on the exhaust gas inlet side and the exhaust gas outlet side of the exhaust gas passage 22. In order to block the inlet side and the outlet side of the exhaust gas passage 22, a shield plate 24 is provided. A slidable tubular open / close valve 5 for opening / closing the main exhaust gas passage 12 is arranged on the upstream side of the exhaust gas inflow of the main filter 1, and the open / close valve 5 is bypassed by an actuator 11 driven by a command from a controller 10. It is opened and closed in response to the opening of the valve 9. A support pipe 13 is connected to the exhaust gas inflow side of the sub filter 2, and a bypass valve 9 for opening and closing the inlet of the sub filter 2 is arranged in the support pipe 13. Bypass valve 9
Is opened and closed by an actuator 11 driven by a command from the controller 10. The on-off valve 5 and the bypass valve 9 include a main filter 1 and a sub-filter 2
In order to regenerate the exhaust gas, a through hole through which a slight amount of exhaust gas leaks may be formed, and the on-off valve 5 and the bypass valve 9 themselves may be arranged in the exhaust gas passage 22 and the bypass passage 14 so as to leak. Good. Further, a safety valve 33 is provided at the downstream end of the sub filter 2.

In the structure of this diesel particulate filter, the main filter 1 and the sub-filter 2 are composed of the filter body 3, and the wire mesh 6 made of a conductive material at least on the exhaust gas inflow side with respect to the inner and outer surfaces of the filter body 3. ，
7 are arranged. The filter main body 3 is formed in a plate-like cylindrical shape by laminating SiC or SiC long-fiber material obtained by adding additives such as Ti and Ta. When the exhaust gas is passed through the filter body 3, the particulates in the exhaust gas are collected in the region where the fibers intersect with each other and are sequentially deposited between the fibers to increase the exhaust gas pressure on the upstream side of the filter body 3. It will be.

Regarding the wire nets 6 and 7, the wire net 6 is disposed upstream of the exhaust gas flow of the main filter 1, and the main filter 1
A wire mesh 7 is arranged on the downstream side of the exhaust gas flow. The wire nets 6 and 7 are made of corrosion-resistant heat-resistant steel containing Ni, Cr, Al, etc., and can be fixed to the main filter 1 by arranging them on the surface of the filter body 3 and appropriately locking them with a stapler or the like. . When the main filter 1 is made of two cylindrical filters, the inner cylinder 19 and the outer cylinder 20, the main exhaust gas inflow on the exhaust gas inflow side where the exhaust gas flows between the inner cylinder 19 and the outer cylinder 20. The passage 12 is formed, and a main exhaust gas outflow passage 35 on the exhaust gas outflow side is formed inside the inner cylinder 19 and outside the outer cylinder 20 so that the exhaust gas passing through the main filter 1 flows out. For example, the outer cylinder 20 will be described. The wire nets 6 and 7 are fixed to the inner and outer surfaces of the outer cylinder 20 with a stapler or the like. At this time, the wire net 6 arranged on the inner surface of the outer cylinder 20, that is, on the exhaust gas inflow side is made of a conductive material, and the terminal 30 is provided so as to function as a heater. The outer cylinder 20
The wire net 7 arranged on the outer surface of the above, that is, on the exhaust gas outflow side, does not necessarily have to be made of a conductive material.

The wire mesh 6 is provided in the controller 1 in order to heat and burn the particulates collected in the main filter 1.
The energization is controlled by the command of 0. Although not shown, the sub-filter 2 may be provided with a wire mesh like the main filter 1 to heat and burn the particulates collected by the sub-filter 2. The wire nets 6 and 7 extend over the entire inflow upstream side of the main filter 1 of the exhaust gas passage 22 and the entire inflow upstream side of the sub filter 2 of the bypass passage 14, and are connected to the controller 10 through the electrode terminals 30. . Also, wire mesh 6
Is preferably made of a Ni or Cr refractory metal,
The surface of the main filter 1 can be uniformly heated. The wire net 6 is, for example, Ni-C.
core member made of r alloy, intermediate member made of a material having a large temperature coefficient of resistance such as Ni coated on the core member,
And a coating layer made of corrosion resistant Al ₂ O ₃ or ZrO ₂ coated on the intermediate member.

In particular, this diesel particulate filter device is arranged on the exhaust gas inflow side of the main filter 1 and automatically adjusts the opening degree to the main exhaust gas passage 12 according to the flow rate of the exhaust gas passing through the sub filter 2. That is, it has an on-off valve 5. The on-off valve 5 is a tubular valve body that slides across the main exhaust gas passage 12 formed between the support pipe 13 connected to the sub-filter 2 and the exhaust pipe 36 forming the exhaust gas passage 22. . The tubular valve body has a downstream end formed with a throttle 31 extending radially inward and a through hole 8 communicating with the main exhaust gas passage 12. The tubular valve body is configured to open the through hole 8 to the main exhaust gas passage 12 by the spring force of the spring 25. Further, the opening degree of the main exhaust gas passage 12 by the tubular valve body is configured to be adjusted by the resistance of the throttle portion 31 due to the flow rate of the exhaust gas flowing through the bypass passage 14 that resists the spring force of the spring 25. The spring 25 is arranged between the throttle portion 31 of the on-off valve 5 and the protrusion 26 provided on the support tube 13.

Further, since the on-off valve 5 and the bypass valve 9 are exposed to exhaust gas, Si, which has a high corrosion resistance and a high heat resistance, is used.
It is made of C, Si ₃ N ₄ , Al ₂ O ₃ or mullite. Further, in order to prevent carbon and the like from entering the sliding surface of the tubular valve body of the on-off valve 5, a sealing material made of fiber such as SiC is provided on the exhaust pipe 36 on the upstream side of the exhaust gas flow.
It is preferable to provide it.

The controller 10 includes a rotation sensor 27 for detecting the engine speed, a load sensor 28 for detecting the engine load, a sensor (not shown) for detecting the amount of particulates deposited on the main filter 1, and an exhaust gas temperature. A temperature sensor 29 for detecting the temperature is provided. The controller 10 receives these detection signals of the engine operating state, determines the particulate collection state corresponding to the detection value of the particulate accumulation amount that is predetermined corresponding to the engine operating state, and determines the bypass valve. It is configured to control the opening timing of 9, that is, the reproduction timing of the main filter 1.

The structure of this diesel particulate filter is constructed as described above, and operates as follows. The diesel engine is driven and the exhaust gas is sent to the exhaust gas passage 22 through the exhaust pipe. At this time, the opening / closing valve 5 is opened by the spring force of the spring 25, the bypass valve 9 is closed, and the exhaust gas is discharged from the exhaust gas passage 22.
From the inlet 15 to the main exhaust gas passage 12, passes through the main exhaust gas passage 12 through the main filter 1, and the main filter 1 collects particulates such as soot, carbon, and smoke contained in the exhaust gas, Clean exhaust gas is discharged to the outlet 17. The collected particulates will be deposited on the main filter 1, and the air passage resistance of the main filter 1 will gradually increase according to the collection time. The controller 10 receives detection signals from the sensor for detecting the amount of particulate accumulation, the rotation sensor 27, the load sensor 28, and the temperature sensor 29, judges the engine operating state from the detected values, and sets the particulates preset. When the accumulated amount exceeds, the actuator 11 is operated and the bypass valve 9 is opened.

Therefore, when a predetermined amount of particulates is collected in the main filter 1, the controller 10 causes the bypass valve 9 to open the bypass passage 14 by the operation of the actuator 11 in order to regenerate the main filter 1. .
When the bypass valve 9 is opened, most of the exhaust gas passes through the sub filter 2 through the bypass passage 14 and particulates are collected by the sub filter 2. At this time, when the exhaust gas flows through the bypass passage 14, the flow of the exhaust gas collides with the throttle portion 31 of the on-off valve 5 and the throttle portion 3
The resistance of 1 resists the spring force of the spring 25 to slidably move the tubular valve body of the on-off valve 5 to the downstream side to close the through hole 8 and a small amount of exhaust gas from the exhaust gas passage 22. It is fed to the main filter 1. Further, the controller 10 issues a command to pass a current through the wire net 6 through the electrode terminal 30, the wire net 6 is heated, and the main filter 1 is heated. On the other hand, in the exhaust gas passing through the sub filter 2, the particulates contained therein are collected by the sub filter 2, and the collected particulates are collected by the sub filter 2
Deposit on.

When the main filter 1 is heated, the particulate matter trapped in the main filter 1 uses CO contained in a small amount of exhaust gas passing through the main filter 1 to generate CO.
₂ , converted to H ₂ O, incinerated, turned into gas, and exited 17
And the regeneration of the main filter 1 is completed. The completion of regeneration of the main filter 1 is determined by the controller 10 based on the incineration time with respect to the amount of particulate accumulation in consideration of the engine operating state. When the regeneration of the main filter 1 is completed, the controller 10 issues a command to operate the actuator 11 to close the bypass valve 9. When the bypass valve 9 is closed, the flow of the exhaust gas to the bypass passage 14 is stopped, the opening / closing valve 5 returns to its original state by the spring force of the spring 25, the through hole 8 communicates with the main exhaust gas passage 12, and the exhaust gas is discharged. The exhaust gas passage 22 passes through the main filter 1, and the normal exhaust gas treatment, that is, the main filter 1
Particulate collection processing by. At this time, a small amount of exhaust gas is sent to the bypass passage 14 through a through hole or a gap formed in the bypass valve 9. Therefore,
The particulates collected in the sub-filter 2 are incinerated by using the air contained in a small amount of exhaust gas passing through the sub-filter 2 from the bypass passage 14, and the sub-filter 2 is regenerated. In the diesel particulate filter, the above-mentioned operation cycle is repeated and the exhaust gas is continuously purified.

Next, another embodiment of the structure of this diesel particulate filter will be described with reference to FIG. This embodiment has the same configuration and the same function except that the arrangement position of the spring is different from that of the above-mentioned embodiment, and therefore, the same components are designated by the same reference numerals and duplicate description will be omitted. . In this embodiment, the spring 25
Is arranged between the protrusion 32 provided on the outer periphery of the on-off valve 5 and the case 21 forming the exhaust gas passage 22. The protrusion 32 projects from the case 21 through a slit 34 formed in the case 21, and the spring 25 is located outside the case 21 so as not to come into contact with exhaust gas.

[0028]

The structure of the diesel particulate filter according to the present invention is configured as described above,
It has the following effects. That is, the structure of this diesel particulate filter is such that an opening / closing valve is provided for the main filter, a bypass valve is provided for the sub filter, and the opening / closing valve automatically adjusts its opening depending on the flow rate of exhaust gas flowing through the bypass passage. Since the exhaust gas is adjusted, excessive regeneration of the exhaust gas does not flow during the main filter, and the regeneration process proceeds well, and the exhaust gas flow rate to the main exhaust gas passage increases as the regeneration process of the main filter progresses. It is possible to prevent the main filter from being overheated.

As described above, this diesel particulate filter device can be formed in a compact and simple structure, and has a very simple and continuous function of treating exhaust gas discharged from the diesel engine. Exhaust gas can be purified, and for example, it can be mounted satisfactorily in a severe place due to the space of a vehicle or the like.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the structure of a diesel particulate filter according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the structure of the diesel particulate filter according to the present invention.

[Explanation of symbols]

 1 Main Filter 2 Sub Filter 3 Filter Body 4 Bypass Cylindrical Body 5 Opening / Closing Valve 6 Upstream Wire Mesh 7 Downstream Wire Mesh 8 Through Hole 9 Bypass Valve 10 Controller 11 Actuator 12 Main Exhaust Gas Passage 13 Support Pipe 14 Bypass Passage 22 Exhaust Gas Passage 25 Spring 26 Protrusion 30 Terminal 31 Throttle

Claims (6)

[Claims] 1. A structure of a diesel particulate filter in which particulate matter contained in exhaust gas is collected by a filter arranged in an exhaust system of a diesel engine, and the particulate matter collected by the filter is incinerated by heating. A main filter arranged in the gas passage, a sub-filter arranged in parallel to the exhaust gas flow with respect to the main filter, a bypass valve arranged to open and close the sub-filter arranged on the exhaust gas inflow side of the sub-filter, and Of the diesel particulate filter, which is arranged on the exhaust gas inflow side of the main filter and comprises an opening / closing valve for automatically adjusting the opening degree of the main filter according to the flow rate of the exhaust gas passing through the sub filter. Construction. 2. The on-off valve slides around a support pipe connected to the sub-filter, and has a downstream end formed with a throttle portion extending inward in a radial direction and a through hole communicating with the main exhaust gas passage. The tubular valve element constituting the on-off valve opens the through hole to the main exhaust gas passage by the spring force of a spring, and further opens the bypass valve to open the main exhaust gas passage by the tubular valve element. 2. The structure of the diesel particulate filter according to claim 1, wherein the degree is operated by a flow resistance of the throttle portion due to a flow rate of exhaust gas flowing through the bypass passage against a spring force of the spring. 3. The structure of the diesel particulate filter according to claim 2, wherein the spring is arranged between the throttle portion of the on-off valve and a protrusion provided on the support tube. 4. The diesel particulate filter according to claim 2, wherein the spring is arranged between a protrusion provided on the outer periphery of the on-off valve and a case forming the exhaust gas passage. Construction. 5. The on-off valve and the bypass valve are made of SiC, Si ₃ N ₄ , Al ₂ O ₃ or mullite, which are highly corrosion resistant and highly heat resistant. Diesel particulate filter structure. 6. The main body of the filter constituting the main filter and the sub-filter is SiC or SiC with Ti and Ta.
It is formed by laminating ceramic long-fiber materials to which additives such as are added, the filter body is formed in a cylindrical shape, and a wire mesh forming a heater is arranged on the upstream surface of the filter body. The structure of the diesel particulate filter according to claims 1 to 4.