JP5300466B2 - Exhaust purification device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device easily assembled without being deformed by thermal distortion. <P>SOLUTION: The exhaust emission control device includes a cylindrical body 1 mounted in an exhaust flow path of an internal combustion engine, and connected at one end to the upstream-side exhaust flow path and the other end to the downstream-side exhaust flow path. A catalyst 4 is arranged in the cylindrical body 1 at its downstream side, and an adsorption flow path 10 in which an adsorbing material 8 is provided for adsorbing unburnt gas in exhaust gas and a main flow path 12 which is provided in parallel to the adsorption flow path 10 are formed in the cylindrical body 1 at its upstream side beyond the catalyst 4. A selector valve 14 is provided for selecting the adsorption flow path 10 or the main flow path 12. In this case, a flow path pipe 6 having a smaller outer shape than the cylindrical body 1 is inserted into the cylindrical body 1 and the outer periphery of the flow path pipe 6 is fixed in contact with the inner periphery of the cylindrical body 1, while the adsorbing material 8 is arranged in the flow path pipe 6 to form the adsorption flow path 10 passing through the flow path pipe 6 and form the main flow path 12 between the outer periphery of the flow path pipe 6 and the inner periphery of the cylindrical body 1. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention is provided in parallel with the adsorption flow path, which is interposed in the exhaust flow path of the internal combustion engine and in which the adsorbent which adsorbs the unburned gas in the exhaust is interposed on the upstream side of the catalyst. The present invention relates to an exhaust purification device capable of switching between main flow paths.

  Conventionally, as disclosed in Patent Document 1, an adsorption passage provided in an exhaust pipe on the upstream side of a catalyst and provided with an adsorbent for adsorbing unburned gas in the exhaust is provided in parallel with the adsorption passage. There is known an exhaust emission control device capable of switching between a main flow path formed by a switching valve.

In this exhaust purification system, the main body is formed with a middle structure in which the upper half of the cross-sectional shape is a semicircular arc and the lower half of the cross-sectional shape is a semicircular arc, and the inside of the main body is partitioned by a partition wall. Thus, an adsorbent is arranged on one side to form an adsorption channel, and the main channel is formed on the other side.
Japanese Patent No. 3587670

  However, in such conventional devices, welding is performed along the longitudinal direction in order to unite the upper half and the lower half while preventing the leakage of exhaust gas, but the weld line is long, and the main body deforms due to thermal strain. It's easy to do. For example, a gap or the like is generated between the catalyst and the main body after welding, and the catalyst holding performance may not be ensured due to deformation due to thermal distortion, resulting in the occurrence of defective products and an increase in cost.

  Moreover, the partition has to be attached so as to partition the inside of the main body, and there is a problem that the assembling property of the partition is poor and the work becomes complicated.

  An object of the present invention is to provide an exhaust purification device that is easy to assemble without causing deformation due to thermal distortion.

In order to achieve this problem, the present invention has taken the following measures in order to solve the problem. That is,
A cylindrical tubular body interposed in the exhaust flow path of the internal combustion engine, one end connected to the upstream exhaust flow path, and the other end connected to the downstream exhaust flow path, An adsorption flow path provided with an adsorbent for adsorbing unburned gas in the exhaust gas on the upstream side of the catalyst in the cylindrical body, the catalyst being disposed on the downstream side in the cylindrical body, and the adsorption In an exhaust emission control device provided with a switching valve for switching between the adsorption channel and the main channel, forming a main channel provided in parallel with the channel,
A flow path pipe having a smaller outer shape than the cylindrical main body is inserted into the cylindrical main body, and the outer periphery of the flow path pipe is fixed in contact with the inner periphery of the cylindrical main body. The adsorbent is disposed to form the adsorption flow path passing through the flow path pipe, and the main flow path is formed between the outer circumference of the flow path pipe and the inner circumference of the cylindrical body ,
The channel pipe is
A semicircular pipe portion formed in a semicircular shape so as to have an outer diameter substantially the same as the inner diameter of the cylindrical main body,
A cylindrical straight pipe portion having an outer diameter in which a gap is formed between the adsorbent and an inner periphery of the cylindrical main body;
The exhaust pipe is characterized in that the semicircular tube portion is in close contact with the inner periphery of the cylindrical body, and the straight tube portion is in substantially line contact with the inner periphery of the cylindrical body. That is the purification device.

It may be configured to place the selector valve to the semicircular end side of the front Symbol flow pipe. Further, the downstream end of the cylindrical main body is reduced in diameter to form a downstream connecting portion connected to the downstream exhaust passage, and the upstream exhaust is provided at the upstream end of the cylindrical main body. It is good also as a structure which attached the cover member which formed the upstream connection part connected to a flow path.

  Since the exhaust gas purification apparatus of the present invention inserts the flow channel pipe into the cylindrical main body and fixes the inner periphery of the cylindrical main body and the outer periphery of the flow channel tube, It is possible to suppress deformation due to thermal distortion, such as by welding, and it is possible to assemble by inserting it into the cylindrical main body.

  Further, by forming the end side of the flow channel tube in a semicircular shape and making it adhere in a semicircular shape along the inner periphery of the cylindrical main body, a plurality of spot welded portions can be easily obtained, and the fixing strength can be secured. . In that case, the structure of the switching valve can be simplified by disposing the switching valve on the semicircular end side of the flow channel pipe.

  Furthermore, by reducing the diameter of the downstream side of the cylindrical main body to form the downstream side connection portion and attaching the lid member to the upstream side, the influence of thermal distortion due to welding when the lid member is attached can be suppressed.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  As shown in FIG. 1, 1 is a cylindrical main body, and in this embodiment, the cylindrical main body 1 is formed in a cylindrical shape that is long in the axial direction. The cylindrical main body 1 is provided with a circular large-diameter portion 1a having a substantially constant cross-sectional shape along the axial direction from one end side, and a tapered portion 1b having a tapered diameter is formed on the other end side. In addition, a cylindrical downstream connection portion 1c is formed so as to be connected to the taper portion 1b.

  Since the cylindrical main body 1 can be formed by reducing the diameter of the end of the cylindrical pipe by spinning or the like and forming the downstream connection portion 1c, it can be formed by a simple process of processing the end of the pipe. An exhaust pipe as a downstream exhaust passage (not shown) is connected to the downstream connection portion 1c. The large-diameter portion 1a may have a shape that is substantially a raw material pipe.

  A cylindrical three-way catalyst 4 is inserted into the large-diameter portion 1a of the cylindrical main body 1 on the downstream connection portion 1c side. A buffer material or the like (not shown) may be provided on the outer periphery of the three-way catalyst 4. The three-way catalyst 4 is a ceramic carrier on which a noble metal such as platinum, palladium or rhodium is supported as a catalyst, and is known to purify HC, CO, NOx, etc. in exhaust gas by oxidation reaction or oxidation / reduction reaction. belongs to.

  In the large diameter portion 1 a of the cylindrical main body 1, a flow channel pipe 6 is further inserted upstream of the three-way catalyst 4. The channel pipe 6 is smaller than the outer shape of the cylindrical main body 1 so that it can be inserted into the cylindrical main body 1, and the channel pipe 6 has a cylindrical straight pipe portion 6a whose outer diameter is smaller than the inner diameter of the large diameter portion 1a. I have.

  As shown in FIG. 2, the inner diameter of the large-diameter portion 1a and the straight pipe are formed between the inner circumference of the large-diameter portion 1a and the outer circumference of the straight pipe portion 6a so that a crescent-shaped gap through which the exhaust can pass is formed. The outer diameter of the part 6a is determined.

  An adsorbent 8 is inserted into the straight pipe portion 6a, and the adsorbent 8 is formed by coating a ceramic carrier having a large number of small holes with zeolite or a stainless steel foil-like plate coated with zeolite. Are well known. Moreover, not only zeolite but what consists of activated carbon may be used. A buffer material or the like (not shown) may be disposed on the outer periphery of the adsorbent 8.

  A semicircular pipe portion 6b is formed on one end side of the flow channel pipe 6 and connected to the straight pipe portion 6a on the upstream side of the exhaust gas. The flow path pipe 6 is formed by subjecting a pipe as a raw material to press processing or the like to form a semicircular pipe portion 6b, and the straight pipe portion 6a may be substantially in the shape of a raw material pipe. In the present embodiment, the straight pipe part 6a and the semicircular pipe part 6b are formed by pressing a single pipe. However, the present invention is not limited thereto, and the straight pipe part 6a and the semicircular pipe part 6b May be formed separately, and the flow channel pipe 6 may be formed integrally by welding, brazing, or the like. In the present embodiment, the semicircular pipe portion 6b is formed only on one side of the straight pipe portion 6a. However, the present invention is not limited to this, and the semicircular pipe portions 6b may be formed on both sides of the straight pipe portion 6a.

  Further, as shown in FIG. 3, the semicircular pipe portion 6 b is substantially the same as the inner diameter of the cylindrical main body 1 so that a part in the circumferential direction can be brought into semicircular contact with the inner periphery of the cylindrical main body 1. It is formed in a semicircular shape so as to have the same outer diameter. Except for the semicircular outer shape, the chords other than the arc are linearly formed, and the outer shape of the semicircular pipe portion 6b is substantially semicircular. When forming into a semicircular shape, it is not necessary to be a half of a circle, and it may be a shape that can be easily processed from a pipe of a material.

  After the adsorbent 8 is inserted into the channel tube 6, the channel tube 6 is inserted into the large-diameter portion 1a of the cylindrical body 1, and as shown in FIG. 1, the semicircular outer periphery of the semicircular tube portion 6b. Is closely attached to the inner periphery of the cylindrical main body 1, and the cylindrical main body 1 and the flow channel pipe 6 are fixed by welding or the like. The welding may be spot welding, and can be fixed with sufficient strength by spot welding at a plurality of locations. By using the semicircular semicircular pipe portion 6b, a plurality of spot welds can be easily obtained, and the fixing strength can be ensured. And while being able to ensure a spot welding location also along a longitudinal direction, a spot welding location can be ensured also along the circumferential direction, and fixed strength can be ensured also from this point.

  By inserting the channel pipe 6 into the cylindrical main body 1 and bringing it into close contact with the inner periphery, an adsorption channel 10 in which exhaust gas flows through the channel pipe 6 and the cylindrical main body 1 A main flow path 12 through which exhaust gas flows between the inner periphery and the outer periphery of the flow path pipe 6 is formed in parallel.

  A switching valve 14 is provided on the upstream side of the flow path pipe 6. In this embodiment, the switching valve 14 includes a butterfly-type valve body 16, and the valve body 16 is supported so as to be swingable. The valve body 16 may be swingably supported by the large diameter portion 1a or may be swingably supported by the flow path pipe 6.

  The valve body 16 is swung by an actuator (not shown). As shown by a solid line in FIG. 1, the switching valve 14 abuts the valve body 16 against the protrusion 18 of the large-diameter portion 1a and closes the main flow path 12. As shown by a two-dot chain line in FIG. 1, the valve body 16 can be swung between the valve body 16 and a position where the adsorption flow path 10 is closed.

  Furthermore, a lid member 20 is attached to the upstream opening of the large diameter portion 1a. The lid member 20 includes a cylindrical portion 20a that can be fitted into the opening of the large-diameter portion 1a, a tapered portion 20b that is connected to the cylindrical portion 20a and is reduced in diameter toward the upstream side, and a cylindrical shape that is connected to the tapered portion 20b. Upstream connection portion 20c. The cylindrical portion 20a is fitted into the large-diameter portion 1a, and is leak-tightened and fixed by all-around welding. An upstream exhaust passage (not shown) is connected to the upstream connection portion 20c.

  The welded portion between the large-diameter portion 1a and the lid member 20 is at the upstream opening farthest from the three-way catalyst 4, and the large-diameter portion 1a outside the three-way catalyst 4 is deformed by thermal distortion due to welding heat. Can be suppressed. Moreover, since the flow path pipe 6 in which the adsorbent 8 is inserted is in a state in which the large diameter portion 1a and the straight pipe portion 6a are substantially in line contact, the heat from the large diameter portion 1a is transferred to the straight pipe portion 6a. Therefore, even if it is relatively close to the welding location, it is possible to suppress deformation due to thermal distortion caused by the welding heat of the straight pipe portion 6a.

  Next, the operation of the above-described exhaust purification device of this embodiment will be described.

  When the internal combustion engine is started, the exhaust gas temperature is low, and the exhaust gas contains a large amount of unburned gas. At the time of starting, as shown by a solid line in FIG. 1, the switching valve 14 is swung to a position where the main flow path 12 is closed by the valve body 16, and flows into the large diameter portion 1a via the upstream connection portion 20c of the lid member 20. Exhaust gas at the start flows into the adsorption flow path 10. In the adsorption flow path 10, unburned gas in the exhaust gas is adsorbed when passing through the adsorbent 8 in the straight pipe section 6 a from the semicircular pipe section 6 b of the flow path pipe 6. The exhaust gas that has passed through the adsorbent 8 flows into the large-diameter portion 1a, passes through the three-way catalyst 4, and flows out to the downstream exhaust passage through the downstream connection portion 1c.

  When the exhaust gas temperature rises and the three-way catalyst 4 is activated, the switching valve 14 is switched, and the adsorption passage 10 is closed by the valve body 16 as shown by a two-dot chain line in FIG. Lead to. Exhaust gas that has flowed into the large diameter portion 1a via the upstream connection portion 20c of the lid member 20 flows from the large diameter portion 1a through the main flow path 12 between the inner periphery of the large diameter portion 1a and the outer periphery of the flow channel pipe 6. The harmful components in the exhaust gas are purified by the oxidation reaction or oxidation / reduction reaction by the three-way catalyst 4 through the three-way catalyst 4. Exhaust gas that has passed through the three-way catalyst 4 flows out to the downstream exhaust passage via the downstream connection portion 1c.

  Further, at a suitable timing, the valve body 16 is swung by a predetermined angle so that a part of the exhaust gas also flows through the adsorption channel 10, and a part of the exhaust gas flows into the adsorbent 8. Thereby, the unburned gas adsorbed by the adsorbent 8 is desorbed, flows into the large diameter portion 1a from the adsorption flow path 10, passes through the three-way catalyst 4, and downstream via the downstream connection portion 1c. To the exhaust passage on the side. At that time, the unburned gas is combusted by the three-way catalyst 4 and the exhaust gas is purified.

  As described above, the flow path pipe 6 is inserted into the cylindrical main body 1, the inner periphery of the cylindrical main body 1 and the outer periphery of the flow path pipe 6 are closely attached and fixed by welding, etc. It is difficult to receive, and there is little possibility that a gap is generated between the three-way catalyst 4 and the cylindrical main body 1 or a gap is generated between the adsorbent 8 and the flow path pipe 6. Moreover, the flow path pipe 6 may be inserted into the cylindrical main body 1 and fixed, and assembly is easy.

  Further, a semicircular semicircular pipe portion 6 b is formed on the end side of the flow path pipe 6, and a part of the flow path pipe 6 in the circumferential direction is adhered in a semicircular shape along the inner periphery of the cylindrical body 1. This facilitates the arrangement of the switching valve 14 and can be firmly fixed.

  Further, the downstream end of the cylindrical main body 1 is reduced in diameter to form the downstream connection portion 1c, and the flow path pipe 6 in which the three-way catalyst 4 and the adsorbent 8 are arranged is inserted into the cylindrical main body 1. By attaching the lid member 20 formed with the upstream connection portion 20c to the upstream end of the cylindrical main body 1, it can be easily assembled.

  The present invention is not limited to such embodiments as described above, and can be implemented in various modes without departing from the gist of the present invention.

It is sectional drawing of the exhaust gas purification apparatus as one Embodiment of this invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylindrical main body 1a ... Large diameter part 1b ... Tapered part 1c ... Downstream connection part 4 ... Three-way catalyst 6 ... Channel pipe 6a ... Straight pipe part 6b ... Semicircular pipe part 8 ... Adsorbent 10 ... Adsorption channel DESCRIPTION OF SYMBOLS 12 ... Main flow path 14 ... Switching valve 16 ... Valve body 18 ... Projection part 20 ... Lid member 20a ... Cylindrical part 20b ... Tapered part 20c ... Upstream side connection part

Claims (3)

A cylindrical tubular body interposed in the exhaust flow path of the internal combustion engine, one end connected to the upstream exhaust flow path, and the other end connected to the downstream exhaust flow path, An adsorption flow path provided with an adsorbent for adsorbing unburned gas in the exhaust gas on the upstream side of the catalyst in the cylindrical body, the catalyst being disposed on the downstream side in the cylindrical body, and the adsorption In an exhaust emission control device provided with a switching valve for switching between the adsorption channel and the main channel, forming a main channel provided in parallel with the channel,
A flow path pipe having a smaller outer shape than the cylindrical main body is inserted into the cylindrical main body, and the outer periphery of the flow path pipe is fixed in contact with the inner periphery of the cylindrical main body. The adsorbent is disposed to form the adsorption flow path passing through the flow path pipe, and the main flow path is formed between the outer circumference of the flow path pipe and the inner circumference of the cylindrical body ,
The channel pipe is
A semicircular pipe portion formed in a semicircular shape so as to have an outer diameter substantially the same as the inner diameter of the cylindrical main body,
A cylindrical straight pipe portion having an outer diameter in which a gap is formed between the adsorbent and an inner periphery of the cylindrical main body;
The exhaust pipe is characterized in that the semicircular pipe portion is in close contact with the inner periphery of the cylindrical main body, and the straight pipe portion is substantially in line contact with the inner periphery of the cylindrical main body. Purification equipment. An exhaust emission control device as claimed in claim 1, characterized in that a said switching valve in semicircular end side of the flow pipe. The downstream end of the cylindrical main body is reduced in diameter to form a downstream connection portion connected to the downstream exhaust passage, and the upstream exhaust passage is connected to the upstream end of the cylindrical main body. The exhaust emission control device according to claim 1 or 2 , further comprising a lid member formed with an upstream connection portion connected to the exhaust gas.

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