JP3951598B2 - Exhaust gas purification device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas purifying device for collecting particulates (PM: particulate matter) discharged from a diesel engine mounted on a truck, a bus or the like.
[0002]
More specifically, the present invention relates to a joining portion of piping on the downstream side of the filter used in the exhaust gas purification device.
[0003]
[Prior art]
Exhaust gas emitted from diesel engines such as automobiles contains particulates (PM: particulate matter) with a size of several μm to several tens of μm. It is important.
[0004]
In order to remove the PM, a diesel particulate filter (DPF: Diesel Particulate Filter) is used, and an exhaust gas purification device including the diesel particulate filter is disposed in the exhaust passage of the engine.
[0005]
This DPF is composed of cordierite, a metal porous body (Celmet), an inorganic fiber material, or the like. When an inorganic fiber material is used, the fiber diameter of silicon carbide, alumina, zirconia, etc. A nonwoven fabric is formed of ceramic fibers having a length of about 1 to 20 μm and a fiber length of about 10 mm to 50 mm, and the nonwoven fabric forms a filter.
[0006]
If this filter continues to collect PM, it will cause clogging due to the collected PM. Therefore, this filter will detect clogging by a change in the exhaust pressure before and after the filter and continue to collect PM. The PM is regenerated by burning PM collected by heating with an electric heater or the like.
[0007]
And while collecting PM with one filter, the regeneration process which burns PM collected with the other filter is performed, and PM collection is performed continuously, changing with both filters.
[0008]
When this exhaust gas purification device is mounted on a vehicle such as a truck or a bus, the exhaust passage is connected to the switching passage, and two filters are arranged in parallel in the width direction of the vehicle body on the downstream side of the switching passage. There is a problem that the space required for the exhaust gas purifying device increases in the width direction, making it difficult to mount.
[0009]
Therefore, as shown in FIG. 2, the first filter 20A, the switching passage 13 and the second filter 20B are arranged in a row from the engine 10 side, and the exhaust passage 12 from the engine 10 is connected to the central switching passage 20B. Then, the outlet passage 22A for discharging the exhaust gas Gc purified by the first filter 20A is piped in parallel with the first filter 20A, the switching passage 13 and the second filter 20B. The exhaust gas Gc purified by the second filter 20B is joined to the outlet passage 22B on the side.
[0010]
The switching valve 14 provided in the switching passage 13 is configured to allow the exhaust gas G to flow to the exhaust passage 23 on the downstream side via the first filter 20A, or via the second filter 20B and the outlet passage 22B. In addition, heaters 21A and 21B for regeneration are arranged in the filters 20A and 20B, and current is supplied from the alternator 41 or the battery 43 driven by the engine 10 during regeneration to heat the filters 20A and 20B. It is configured.
[0011]
In order to supply oxygen for PM combustion during regeneration, the air A is supplied from the air pump 24 via the air pipe 25 to one of the filters 20A and 20B via the electromagnetic valves 26A and 26B, respectively. Is done.
[0012]
Further, a differential pressure between the upstream side exhaust pressure value P1 of the upstream side pressure sensor 31 and the downstream side exhaust pressure value P2 of the downstream side downstream pressure sensor 32A (or 32B) of the PM trapping filter 20A (or 20B) ( When P1-P2) or the pressure ratio (P1 / P2) exceeds a predetermined determination value, it is determined that regeneration is necessary, and regeneration work is started.
[0013]
In this regeneration operation, first, the heater 21A (or 21B) is energized and preheated for a predetermined time, and the filter 20A (or 20B) is preheated to the PM combustion temperature or higher before air supply (oxygen supply). Then, the collected PM burns. After this combustion, the air supply and the heater 21A (or 21B) are turned off, and the filter is cooled for a predetermined time.
[0014]
[Problems to be solved by the invention]
However, the oxygen-containing gas such as air or a part of the exhaust gas supplied to the filter at the time of regeneration increases the combustion rate of PM when the supply amount is large, and the amount of heat generated by combustion increases. Since the filter melts too much, the air supply amount is suppressed to a very small amount compared to the exhaust gas amount.
[0015]
Therefore, as shown in FIG. 3, when the first downstream passage 22A of the first filter 20A of the exhaust gas purification device 1 is joined to the second downstream passage 22B of the second filter 20B, the first downstream passage When the first downstream pipe Ax of 22A is simply orthogonal or obliquely crossed with the second downstream pipe Bx of the second downstream passage 22B, the exhaust gas Gc purified by the second filter 20B is converted into the first filter. There is a problem that the PM combustion gas Ga after the regeneration of 20A is pushed back to prevent smooth discharge of the PM combustion gas, or the exhaust gas Gc flows backward through the outlet passage 22A.
[0016]
If this exhaust gas backflow occurs during regeneration of the first filter 20A, sufficient air A will not reach the first filter 20A, resulting in incomplete PM combustion and insufficient regeneration. The portion that can be continued decreases, the PM collection efficiency deteriorates, and the exhaust pressure increases.
[0017]
As a result, an appropriate regeneration timing cannot be determined, exhaust gas purification performance is deteriorated, and further problems such as a decrease in engine output and a deterioration in fuel consumption caused by a general increase in exhaust pressure occur.
[0018]
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide an exhaust gas purification apparatus in which a first filter, a switching passage, and a second filter are arranged in a straight line, and is disposed on the engine side. The PM combustion gas generated during regeneration of the first filter can be exhausted by smoothly joining the purified exhaust gas exhausted by the PM trapping second filter and exhausting the first filter efficiently. The object is to provide a gas purification device.
[0019]
[Means for Solving the Problems]
An exhaust gas purification apparatus for achieving the above object is configured as follows.
[0020]
1) In the exhaust gas purifying apparatus for alternately collecting the exhaust gas passages to the first and second filters to collect particulates in the exhaust gas of the internal combustion engine mounted on the vehicle and regenerate the filter. A first downstream pipe that discharges the exhaust gas purified by one filter joins with a second downstream pipe that discharges the exhaust gas purified by the second filter on the downstream side of the second filter; The joining portion of the first downstream pipe and the second downstream pipe penetrates the tip portion of the first downstream pipe into the passage of the second downstream pipe, and the tip portion that is upstream with respect to the second downstream pipe A passage of the second downstream pipe in the joining portion is formed to be narrow , and further, a portion of the second downstream pipe where the first downstream piping joins is enlarged to increase the passage cross-sectional area. .
[0021]
According to this structure, the flow cross-sectional area of the confluence portion of the second downstream pipe is narrowed by the tip portion of the first downstream pipe, so that the flow velocity of the gas flowing through the second downstream pipe increases and flows through the first downstream pipe. The gas is sucked into the second downstream pipe. Therefore, the gas flowing through the second downstream pipe is prevented from flowing into the first downstream pipe.
[0022]
Therefore, the PM combustion gas generated at the time of regeneration of the first filter is sucked from the first downstream pipe, and smoothly flows into the purified exhaust gas in the second downstream pipe discharged by the PM trapping second filter. It will join and be discharged.
[0023]
2) In the exhaust gas purifying apparatus described above, the first filter and the second filter are arranged in a row from the engine side across the switching passage, and the exhaust passage of the engine is connected to the switching passage in the center. In addition, the first downstream pipe is piped in parallel with the first filter, the switching passage, and the second filter, and is formed by joining the second downstream pipe on the downstream side of the second filter. Is done.
[0024]
In the exhaust gas purification apparatus of this configuration, the first downstream pipe is a pipe that is significantly longer than the second downstream pipe, and the flow of gas flowing through the first downstream pipe is deteriorated. Become effective.
[0025]
With the above configuration, the PM-combusted gas from the first downstream pipe flows into the second downstream pipe without being obstructed by the purified exhaust gas flowing in the second downstream pipe, and is purified. Mixed with exhaust gas.
[0026]
Therefore, part of the air or exhaust gas containing oxygen supplied during filter regeneration efficiently passes through the entire filter, so that the entire filter is efficiently regenerated and exhaust gas is maintained while maintaining good purification performance. It becomes possible to purify.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an exhaust gas purifying apparatus according to an embodiment of the present invention will be described with reference to the drawings.
[0028]
〔overall structure〕
As shown in FIG. 2, the exhaust gas purification apparatus 1 is formed by arranging a first filter 20A, a switching passage 13 and a second filter 20B in a straight line, and the exhaust passage 12 of the engine 10 is formed by the first filter 20A. And connected to the central switching passage 13.
[0029]
Further, the first downstream passage 22A for discharging the exhaust gas Gc purified by the first filter 20A is arranged in parallel with the three of the first filter 20A, the switching passage 13, and the second filter 20B, and the second filter 20B. The second downstream side passage 22B that discharges the exhaust gas Gc purified in step 1 is joined.
[0030]
In addition, the switching valve 14 provided in the switching passage 13 causes the exhaust gas G to flow downstream via the first filter 20A and the first downstream passage 22A, or via the second filter 20B and the second downstream passage 22B. It is configured to flow into the exhaust passage 23.
[0031]
In order to supply oxygen for PM combustion at the time of regeneration, an air pump 24 is provided to supply air A containing oxygen for regeneration from the downstream side of the air cleaner 11 for intake of the engine 10 via the air pipe 25, respectively. It is configured to supply to the first filter 20A via the electromagnetic valve 26A and to the second filter 20B via the electromagnetic valve 26B.
[0032]
In addition, heaters 21A and 21B for regeneration are arranged in the filters 20A and 20B, and current is supplied from the alternator 41 or the battery 43 driven by the engine 10 during regeneration to heat the filters 20A and 20B. It is configured.
[0033]
The alternator 41 is connected to the battery 43 and the heaters 21A and 21B via the regulator 42. The battery 43 and the heaters 21A and 21B are connected in parallel, one connected to the alternator 41 and the other connected to the other. Grounded.
[0034]
Further, the control unit 30 is provided as a part of the controller in the electronic control box that controls the entire engine, and the upstream pressure sensor 31 and the temperature sensor 34 disposed in the switching passage 13 and the downstream side of the first filter 20A. The output values of the downstream pressure sensor 32A arranged on the downstream side and the downstream pressure sensor 32B arranged on the downstream side of the second filter 20B are input.
[0035]
The control unit 30 allows the switching operation of the switching valve 14 while the operating conditions and elapsed time of the engine 10 are included in the determination conditions, the oxygen pump air pump 24, and the heater heater relays 33A and 33B. Are controlled to perform switching operation of the switching valve 14 for PM collection and regeneration, energization operation to the heaters 21A and 21B for regeneration, air supply operation, and the like.
[0036]
That is, if the filter 20A (or 20B) continues to collect PM, the collected PM causes clogging. Therefore, after the upstream side exhaust pressure value P1 of the upstream side pressure sensor 31 and the PM trapping filter, When the downstream pressure value P2 of the downstream pressure sensor 32A (or 32B) on the flow side is detected and this differential pressure (P1-P2) or pressure ratio (P1 / P2) exceeds a predetermined judgment value, regeneration is performed. Is determined to be necessary, and reproduction work is started.
[0037]
In this regeneration operation, first, the heater 21A (or 21B) is energized and preheated for a predetermined time, and the filter 20A (or 20B) is preheated to the PM combustion temperature or higher, and then the air A is supplied. Then, oxygen is supplied to burn the collected PM. Then, after this PM combustion, the air supply and the heater 21A (or 21B) are turned off, and the filter is cooled for a predetermined time.
[0038]
[Structure of the merge section]
In the present invention, in the exhaust gas purification apparatus 1 having the above-described structure, the merged portion between the first downstream passage 22A of the first filter 20A and the second downstream passage 22B of the second filter 20B (X in FIG. 2). In particular, the PM combustion gas generated during regeneration of the first filter can be smoothly joined to the purified exhaust gas discharged by the PM trapping second filter and discharged. Form.
[0039]
As shown in FIG. 1, the first embodiment of this merging portion (portion X in FIG. 2) is obliquely crossed with the second downstream pipe B1 of the second downstream passage 22B of the second filter 20B. The first downstream pipe A1 of the first downstream passage 22A of the first filter 20A is connected, and the tip portion A1a of the first downstream pipe A1 is penetrated to the inside of the second downstream pipe B1.
[0040]
As shown in FIG. 1 (d), the tip portion A1a of the first downstream pipe A1 cuts the pipe A1 at the first cut line C1a and the second cut line C1b, and the second cut line C1b The small piece plate D1 is formed by welding or the like. The tip portion A1a of the first downstream pipe A1 can be formed by this simple processing.
[0041]
Further, the diameter of the portion of the second downstream pipe B1 where the first downstream pipe A1 joins is increased to increase the passage cross-sectional area, and the exhaust gas Gc purified by the penetration portion of the tip end portion A1a of the first downstream pipe A1. This prevents the cross-sectional area of the passage from becoming excessively narrow. As a result, an increase in the flow rate of the purified exhaust gas Gc is adjusted so that the exhaust pressure does not become too high, and the purified exhaust gas Gc flows smoothly while suctioning the gas Ga after PM combustion. be able to.
[0042]
With this configuration, the gas Ga after PM combustion from the first downstream pipe A1 flows into the second downstream pipe B1 without being obstructed by the purified exhaust gas Gc flowing in the second downstream pipe B1. Can be mixed with the purified exhaust gas Gc.
[0043]
Further, since the upstream portion Aa of the first downstream pipe A1 penetrates into the second downstream pipe B1, the passage of the second downstream pipe B1 becomes narrow, the flow rate of the purified exhaust gas Gc increases, and the first downstream pipe The effect of sucking the gas after PM combustion from the pipe A1 is produced.
[0044]
Further, by increasing the diameter of the second downstream pipe B1 where the first downstream pipe A1 joins and increasing the passage sectional area, the increase in the flow velocity of the purified exhaust gas Gc can be adjusted by this passage sectional area. The purified exhaust gas Gc can also flow smoothly while sucking the gas Ga after PM combustion at an appropriate speed.
[0045]
【The invention's effect】
As described above, according to the exhaust gas purification apparatus of the present invention, in the exhaust gas purification apparatus in which the first filter, the switching passage, and the second filter are arranged in a straight line, when the first filter arranged on the engine side is regenerated. The generated PM combustion gas can be smoothly joined to the purified exhaust gas discharged by the second PM trapping filter and discharged.
[0046]
That is, the gas after PM combustion discharged from the first downstream pipe of the first filter is not obstructed by the purified exhaust gas flowing through the second downstream pipe of the second filter, and the second downstream pipe. Can be mixed with the purified exhaust gas, and the tip portion of the first downstream pipe penetrates into the second downstream pipe, or the second downstream pipe is throttled. By providing the portion, the flow rate of the exhaust gas purified by narrowing the passage cross-sectional area of the downstream pipe can be increased, and the gas after PM combustion can be sucked.
[0047]
In addition, the diameter of the portion of the second downstream pipe where the first downstream pipe joins is increased to increase the passage cross-sectional area, and the passage cross-sectional area of the purified exhaust gas is increased by the penetration portion of the first downstream pipe. The exhaust gas can be prevented from becoming excessively narrow, and the purified exhaust gas can be flowed smoothly while the flow rate of the purified exhaust gas is increased moderately to suck the gas after PM combustion.
[0048]
Therefore, by smoothly discharging the gas after PM combustion during filter regeneration, part of the air and exhaust gas containing oxygen to be supplied can be efficiently passed through the filter, so that the entire filter can be efficiently The exhaust gas can be purified while maintaining good purification performance.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing a joining portion of a first downstream pipe and a second downstream pipe according to a first embodiment of the present invention, (a) is a side view including a partial cross section, and (b) is a side view. It is a top view containing a partial cross section, (c) is sectional drawing of 2nd downstream piping, (d) is a side view including partial cross section which shows the processing method of the front-end | tip part of 1st downstream piping.
FIG. 2 is a configuration diagram of an exhaust gas purification apparatus according to the present invention.
FIGS. 3A and 3B are diagrams showing a joining portion of a first downstream pipe and a second downstream pipe according to the prior art, in which FIG. 3A is a side view and FIG. 3B is a side view including a partial cross section;
[Explanation of symbols]
1 Exhaust gas purification device 10 Engine (internal combustion engine)
12 Exhaust passage 13 Switching passage 20 Filter 20A First filter 20B Second filter A1, 22A First downstream piping A1a, A2a Tip portions B1, 22B Second downstream piping C1a First cut line C1b Second cut line D1 Small plate A Oxygen Contained gas G Exhaust gas Ga PM after combustion Gc Purified exhaust gas

Claims (2)

In an exhaust gas purification apparatus that alternately switches exhaust gas passages to the first and second filters, collects particulates in exhaust gas of an internal combustion engine mounted on a vehicle, and regenerates the filter.
A first downstream pipe for discharging the exhaust gas purified by the first filter is formed on the downstream side of the second filter and joined with a second downstream pipe for discharging the exhaust gas purified by the second filter. ,
The joint portion of the first downstream pipe and the second downstream pipe penetrates the tip portion of the first downstream pipe into the passage of the second downstream pipe, and becomes the upstream portion with respect to the second downstream pipe. Is formed so as to narrow the passage of the second downstream pipe of the merging portion ,
Further, the exhaust gas purifying apparatus is characterized in that the diameter of the portion of the second downstream pipe where the first downstream pipe merges is increased to increase the cross-sectional area of the passage .   The first filter and the second filter are arranged in a row from the engine side across the switching passage, the exhaust passage of the engine is connected to the central switching passage, and the first downstream pipe is The first filter, the switching passage, and the second filter are piped in parallel, and are formed by joining the second downstream pipe on the downstream side of the second filter. The exhaust gas purification apparatus as described.

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