JP2016186229A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device that enables early warming-up of a catalyst with a simple configuration.SOLUTION: An exhaust emission control device include: an introduction portion for introducing exhaust gas; a purification portion for purifying exhaust gas; and a discharge portion for discharging the purified exhaust gas. The exhaust emission control device further includes: an inside purification section that has an inner pipe with one end serving as the introduction portion and the other opening end and an inside catalyst accommodated in the inner pipe to purify exhaust gas; an outside purification section that has an outer pipe communicated with the opening side of inner pipe to make the exhaust gas passed through the inside catalyst turn back to the outer side of the inner pipe and flow on the introduction portion side and an outside catalyst accommodated between the inner pipe and the outer pipe to purify exhaust gas flowing in the outer pipe; and a case that is communicated with the introduction portion side of the outer pipe to form a space for making exhaust gas passed through the outside catalyst turn back and flow on the outer side of the outer pipe and of which side opposite to the introduction portion side of the outer pipe serves as the discharge portion. The case has a flat cross section, and the inner pipe, the outer pipe and the case are disposed concentrically.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust gas purification device. In particular, the present invention relates to an exhaust gas purification device that can warm up a catalyst early with a simple configuration.

In the middle of the exhaust gas exhaust route in automobiles, harmful substances (hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO _x ), etc.) contained in the exhaust gas are purified and harmless substances (water A catalyst for changing to (H ₂ O), carbon dioxide (CO ₂ ), and nitrogen (N ₂ )) is provided. This catalyst does not sufficiently perform the exhaust gas purification function until the temperature reaches the activation temperature. For example, when the engine is stopped, the catalyst is cooled by the outside air temperature. Therefore, when the engine is started, the catalyst temperature is low and sufficient exhaust gas purification performance cannot be obtained. Therefore, when starting the engine, it is required to warm up the catalyst early.

  For example, Patent Document 1 includes a main catalyst disposed in the exhaust pipe, a sub-catalyst disposed upstream of the main catalyst, and an electric heating means (heater) disposed upstream of the sub-catalyst. An exhaust gas purification device that realizes an optimal warm-up that combines a main catalyst and a sub catalyst is disclosed. The main catalyst is activated by exhaust gas from the engine that has become hot, and exhibits a function of purifying exhaust gas. The sub-catalyst has a smaller capacity than the main catalyst, and is heated by the exhaust and heater of the engine, which has become high temperature, and is activated at an early stage to exhibit an exhaust gas purification function. The exhaust pipe is provided with two passages comprising a main pipe and a sub pipe between the electric heating means and the main catalyst, and the main pipe is provided with a flow rate switching valve capable of changing the flow rate of the exhaust. The secondary catalyst is arranged in the. When the sub-catalyst is not in an active state, the flow rate switching valve is closed, and the exhaust gas does not pass through the main pipe but passes only through the sub-pipe in which the sub-catalyst is disposed toward the main catalyst. The sub pipe has a smaller cross-sectional opening area than the main pipe, and the sub catalyst is warmed up early by the high flow rate exhaust hitting the surface of the sub catalyst. When the sub-catalyst becomes active, the flow rate switching valve is opened, and the exhaust passes through the main pipe and the sub-pipe to the main catalyst. The opening and closing of the flow rate switching valve is controlled according to the temperature of the sub-catalyst, and the optimal warm-up of the main catalyst and the sub-catalyst is achieved by changing the flow rate of the exhaust gas passing through the main and sub-pipes. .

JP 09-158719 A

  However, in the conventional technique described in Patent Document 1, the arrangement of the main pipe and the sub pipe and the control of the flow rate of the exhaust gas according to the temperature of the sub catalyst are complicated. Further, early warm-up by the heater is promoted, and the wiring of the heater is required, and the battery capacity needs to be increased.

  In order to warm up the catalyst at an early stage, it may be possible to arrange the catalyst on the engine side as much as possible. However, in this case, the catalyst is exposed to high temperature after warming up. is there.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide an exhaust gas purifying apparatus capable of warming up a catalyst quickly with a simple configuration.

  The exhaust gas purification apparatus of the present invention is an exhaust gas purification apparatus comprising an introduction part for introducing exhaust gas, a purification part for purifying the exhaust gas, and a discharge part for discharging the purified exhaust gas, An inner purification part, an outer purification part, and a case are provided. The inner purification section includes an inner pipe having one end serving as the introduction section and the other end opened, and an inner catalyst housed in the inner pipe for purifying exhaust gas. The outer purification section communicates with the opening side of the inner pipe and passes through the inner catalyst to return the exhaust gas to the outside of the inner pipe and circulate to the introduction section side, the inner pipe and the outer pipe And an outer catalyst for purifying the exhaust gas flowing through the outer pipe. The case forms a space that communicates with the introduction portion side of the outer tube and circulates the exhaust gas that has passed through the outer catalyst on the outside of the outer tube, and the side opposite to the introduction portion side of the outer tube It becomes the said discharge part. The case has a flat cross section, and the inner tube, the outer tube, and the case are arranged concentrically.

  In the exhaust gas purifying apparatus, the purifying unit for purifying the exhaust gas includes a double-structure inner purifying unit and an outer purifying unit arranged concentrically, and an inner catalyst and an outer catalyst are disposed outside the purifying unit. By providing the concentric case for circulating the exhaust gas that has passed, the catalyst can be surrounded by the exhaust gas warmed by the reaction heat of the catalyst, and the catalyst can be warmed up early. Specifically, the exhaust gas introduced from the introduction part flows through the path of the inner pipe → the inner pipe and the outer pipe → the distribution space, and is discharged from the discharge part. Therefore, there is an exhaust gas flow path between the inner pipe and the outer pipe (the outer catalyst is accommodated) outside the inner catalyst, and between the outer pipe and the case outside the outer catalyst. There is a distribution path (distribution space) of exhaust gas. Since the exhaust gas surrounding the catalyst circulates without staying, the catalyst can always be surrounded by the exhaust gas warmed by the reaction heat of the catalyst. Since the exhaust gas is interposed between the catalyst and the outside air, the catalyst is hardly cooled by the outside air temperature, and the catalyst temperature can be maintained.

  Since the exhaust gas purifying apparatus described above is composed of a catalyst and a pipe that houses the catalyst, the structure is simple. In addition, the exhaust gas purifying device described above has a flat shape, that is, the outer shape of the exhaust gas purifying device has a flat shape, so that the thickness (length on the short diameter side) can be reduced and the short diameter side can be reduced. When the vehicle is in the vertical direction, it is easy to arrange. Furthermore, the exhaust gas flow path is formed by concentrically folding back from the inner pipe to the inner pipe and the outer pipe to the flow space, while ensuring a sufficient distance for the exhaust gas to pass through the catalyst. And it can suppress that the full length of an exhaust-gas purification apparatus becomes long.

1 is a schematic top view of an exhaust gas purification device according to an embodiment. 1 is a schematic cross-sectional view of an exhaust gas purification device according to an embodiment.

  Embodiments of an exhaust gas purification apparatus of the present invention will be described below with reference to the drawings. In the figure, the same reference numerals indicate the same names.

<Embodiment>
The exhaust gas purification apparatus 1 according to the embodiment purifies harmful substances in the exhaust gas. This purification of harmful substances reduces the emission of harmful substances to the atmosphere. As shown in FIG. 1, the exhaust gas purification apparatus 1 includes an introduction unit 2 that introduces exhaust gas, a purification unit 3 that purifies the introduced exhaust gas, and a discharge unit 4 that exhausts the exhaust gas purified by the purification unit 3. And comprising. The main features of the exhaust gas purification device 1 are that the purification unit 3 includes a double-structure inner purification unit 10 and an outer purification unit 20 arranged concentrically, and the exhaust gas is exhausted outside the purification unit 3. A case 31 that forms a gas circulation space 32. Details will be described below with reference to FIGS.

Inner purification unit The inner purification unit 10 includes an inner tube 11 and an inner catalyst 12 accommodated in the inner tube 11. The inner purification unit 10 is an exhaust gas introduction unit 2 on one end side, and is a first purification unit that first purifies the exhaust gas.

.. Inner tube The inner tube 11 accommodates an inner catalyst 12 to be described later. One end side of the inner pipe 11 is the exhaust gas introduction part 2, and is connected to the introduction part side exhaust pipe 200 in this embodiment. The other end side of the inner tube 11 is open. The inner tube 11 has a cylindrical shape with a uniform diameter in the axial direction from one end side to the other end side. The diameter of the inner pipe 11 is substantially the same as the diameter of the introduction side exhaust pipe 200. In general, since a catalyst requires a certain amount of capacity, in the case of a pipe or the like for storing the catalyst, the diameter of the portion for storing the catalyst is made larger than the diameter of the exhaust pipe (the connection portion between the exhaust pipe and the introduction portion). Sometimes. However, in this embodiment, since the outer catalyst 22 described later is provided, the diameter of the portion that houses the inner catalyst 12 is substantially the same as the diameter of the exhaust pipe 200 (the connection portion between the exhaust pipe 200 and the introduction portion 2). (Details will be described later). Examples of the constituent material of the inner tube 11 include iron-based materials such as stainless steel.

  The inner tube 11 includes a threaded portion (not shown) threaded on the inner peripheral surface or the outer peripheral surface near the end portion on the introduction portion 2 side. When the inner peripheral surface (outer peripheral surface) of the inner tube 11 is provided with a threaded portion that is internally threaded (male threaded), the threaded portion of the inner tube 11 is screwed onto the outer peripheral surface (inner peripheral surface) of the introduction portion side exhaust pipe 200. It has a threaded portion that can be mated with external threads (internal threads). By doing so, the inner pipe | tube 11 and the introduction part side exhaust pipe 200 can be connected by the screwing by both threading parts. When the inner peripheral surface of the inner tube 11 is provided with a threaded portion, the inner catalyst 12 is arranged so as not to cover the threaded portion, and when the outer peripheral surface of the inner tube 11 is provided with a threaded portion, the outer catalyst 22 described later has a threaded portion. Arrange so as not to cover. The inner pipe 11 and the introduction side exhaust pipe 200 can also be connected by welding.

... inner catalyst inner catalyst 12 promotes HC contained in the exhaust gas, CO, and a chemical reaction to purify harmful substances such as NO _{x H} 2 _O, into harmless substances CO 2, _{N 2.} For the inner catalyst 12, a ceramic catalyst in which a catalyst material for promoting exhaust gas purification is supported on a honeycomb-shaped ceramic carrier made of ceramic, or a honeycomb-shaped metal carrier made of metal foil is used to purify exhaust gas. A metal catalyst carrying a catalyst material to be promoted can be used. The ceramic carrier is formed by extruding a raw material such as cordierite. The ceramic carrier is inexpensive and has excellent heat resistance. The metal carrier is formed by overlapping and winding a metal corrugated plate and a flat plate. Metal carriers are easily deformed and have a high degree of freedom in shape. Examples of the catalyst material include rare metals such as platinum, rhodium, and palladium. The inner catalyst 12 is particularly excellent in maintaining the catalyst temperature, and a ceramic carrier is preferably used.

  The inner catalyst 12 has an outer peripheral shape along the inner peripheral shape of the inner tube 11 and has a cylindrical shape. The cross-sectional area of the catalyst 12 is substantially the same as the cross-sectional area of the introduction side exhaust pipe 200. That is, as described above, the inner catalyst 12 has a cross-sectional area smaller than a general cross-sectional area (a cross-sectional area larger than the cross-sectional area of the exhaust pipe 200). Therefore, since the exhaust gas having a high flow rate hits the inner catalyst 12, the inner catalyst 12 is easily warmed up early.

Outer Purification Unit The outer purification unit 20 includes an outer tube 21 disposed outside the inner tube 11 and an outer catalyst 22 accommodated between the inner tube 11 and the outer tube 21. The outer purification unit 20 is a second purification unit that further purifies the exhaust gas purified by the inner catalyst 12 (inner purification unit 10).

.. Outer tube The outer tube 21 is arranged concentrically with the inner tube 11 (see FIG. 2). The outer pipe 21 communicates with the opening side of the inner pipe 11 and is formed so that the exhaust gas that has passed through the inner catalyst 12 is folded back to the outside of the inner pipe 11 and flows to the introduction portion 2 side (see FIG. 1). ). Specifically, the outer tube 21 covers the opening side in a state where the straight portion 21 s arranged parallel to the outside of the inner tube 11 and the straight portion 21 s are connected to form a space on the opening side of the inner tube 11. And a folded portion 21r. The introduction part 2 side of the outer tube 12 is open. By providing the outer tube 21 with the folded portion 21r, the exhaust gas flowing through the inner tube 11 is folded between the inner tube 11 and the outer tube 12 by the folded portion 21r and flows toward the introduction portion 2 side. Become. Examples of the constituent material of the outer tube 21 include iron-based materials such as stainless steel.

-Outer catalyst The catalyst similar to the inner catalyst 12 can be used for the outer catalyst 22. Since the outer catalyst 22 is accommodated between the inner tube 11 and the outer tube 21, it is preferable that the outer catalyst 22 is excellent in formability, and it is preferable to use a metal carrier. The outer catalyst 22 can be formed, for example, by winding a metal carrier around the outer circumference of the inner tube.

  The outer catalyst 22 is accommodated between the straight portion 21s of the outer tube 21 and the inner tube 11 so that the radial thickness is substantially uniform over the circumferential direction (see FIG. 2). By doing so, it is easy to suppress the drift from the inner tube 11 to the outer tube 21. The outer catalyst 22 may be a capacity obtained by subtracting the capacity of the inner catalyst 12 from the capacity required as a catalyst. By doing so, even if the capacity of the inner catalyst 12 is reduced, the total capacity of the catalyst in the purification unit 3 can be made the capacity required for the catalyst.

-Case The case 31 is arrange | positioned so that the distribution space 32 which distribute | circulates exhaust gas to the outer side of the outer tube | pipe 21 may be formed. The case 31 communicates with the introduction part 2 side of the outer tube 21, and the discharge part 4 is opposite to the introduction part 2 side of the outer tube 21. In other words, the case 31 is formed so as to circulate the exhaust gas that has been communicated with the introduction portion 2 side of the outer tube 21 and passed through the outer catalyst 22 to the outside of the outer tube 21 and flows to the discharge portion 3 side. The case 31 has an end portion on the introduction portion 2 side joined to the introduction portion side exhaust pipe 200 by welding or the like, and an end portion on the discharge portion 3 side joined to the end portion of the discharge side exhaust pipe 300 by welding or the like. Yes. Examples of the constituent material of the case 31 include iron-based materials such as stainless steel.

  As shown in FIG. 2, the case 31 has a flat cross section and is arranged concentrically with the inner tube 11 and the outer tube 21. Here, the cross section of the case 31 has a racetrack shape, and other examples include a rectangular shape or an elliptical shape with rounded corners. The case 31 holds the outer tube 21 with the short diameter portions 33 and 33. The case 31 and the outer tube 21 are joined by welding or the like over the entire length along the longitudinal direction of the case 31 at the short diameter portions 33 and 33. Since the case 31 is joined to the outer tube 21 by the short diameter portions 33 and 33, the circulation space 32 is formed symmetrically on the long diameter portion side with the straight line connecting the short diameter portions 33 and 33 interposed therebetween. (See FIG. 2).

  The exhaust gas purification device 1 described above can be manufactured, for example, as follows. The inner catalyst 12 is press-fitted into the inner tube 11 to produce the inner purification unit 10. A metal catalyst using a metal carrier is wound around the outer periphery of the inner tube 11 to dispose the outer catalyst 22 so that the outer side of the outer catalyst 22 covers the opening side (the side where the threaded portion is not formed) of the inner tube 11. The outer pipe 21 is arranged on the outer pipe 21, and the outer purification section 20 in which the outer catalyst 22 is arranged between the inner pipe 11 and the outer pipe 21 is produced. The inner pipe 11 of the inner purification part 10 and the introduction part side exhaust pipe 200 are screwed together by a threaded part. A cylindrical case is disposed outside the inner purification unit 10 and the outer purification unit 20, both ends of the case are reduced in diameter by spinning (drawing), and both ends are welded to the exhaust pipes 200 and 300, respectively. Join with. An exhaust gas circulation space 32 is formed between the outer tube 21 and the case 31 by the reduced diameter case. As described above, one end of the inner pipe 11 of the inner purification section 10 becomes the introduction section 2, and as shown by the arrow in FIG. 1, the exhaust gas in the inner pipe 11 ⇒ between the inner pipe 11 and the outer pipe 21 ⇒ the distribution space 32. Thus, the exhaust gas purification apparatus 1 is obtained in which one end of the case 31 is the discharge part 4.

Effect In the exhaust gas purification apparatus 1 of the present embodiment, the purification unit 3 that purifies the exhaust gas includes a double-structure inner purification unit 10 and an outer purification unit 20 arranged concentrically, and the purification unit 3 The concentric case 31 that allows the exhaust gas that has passed through the inner catalyst 12 and the outer catalyst 22 to flow outside is provided to surround each catalyst 12, 22 with the exhaust gas warmed by the reaction heat of each catalyst 12, 22. Thus, the catalysts 12 and 22 can be warmed up early. Specifically, the exhaust gas introduced from the introduction part 2 is discharged from the discharge part 4 through a route of the inner pipe 11 → the inner pipe 11 and the outer pipe 21 → the flow space 32. Therefore, an exhaust gas flow path (the outer catalyst 22 is accommodated) between the inner tube 11 and the outer tube 21 exists outside the inner catalyst 12, and the outer tube is disposed outside the outer catalyst 22. There is an exhaust gas distribution path (distribution space 32) between 21 and the case 31. Since the outer catalyst 22 that purifies the exhaust gas folded back by the folded portion 21r exists outside the inner catalyst 12, the inner catalyst 12 is warmed up earlier and the heat retaining property of the catalyst temperature is high. In particular, since the inner catalyst 12 has a smaller capacity (small cross-sectional area) than a general catalyst, the inner catalyst 12 hits the inner catalyst 12 with a high flow rate, and the inner catalyst 12 is easily warmed up early. Even if the capacity of the inner catalyst 12 is reduced, since the outer catalyst 22 is provided outside the inner catalyst 12, if the outer catalyst 22 is a capacity obtained by subtracting the capacity of the inner catalyst 12 from the capacity required as a catalyst. The total capacity of the catalyst in the purification unit 3 can be a capacity required as a catalyst. Since the circulation space 32 of the case 31 is interposed between the catalysts 12 and 22 and the outside air, the catalysts 12 and 22 are not easily cooled by the outside air temperature, and the catalyst temperature can be maintained.

  Since the exhaust gas purification apparatus 1 of the present embodiment is composed of the catalysts 12 and 22, the pipes 11 and 21 that store the catalysts 12 and 22, and the case 31, a plurality of heaters and exhaust gas flow paths are provided. There is no need, and the structure is simple. Further, the exhaust gas flow path is formed by concentrically folding back from the inner pipe 11 to the inner pipe 11 and the outer pipe 21 to the flow space 32 so that the exhaust gas passes through the catalysts 12 and 22. It is possible to suppress an increase in the overall length of the exhaust gas purification device 1 while ensuring a sufficient distance. Furthermore, the exhaust gas purification apparatus 1 of the present embodiment can reduce the thickness (length on the short diameter side) because the case 31 has a flat shape, that is, the outer shape of the exhaust gas purification apparatus 1 has a flat shape. When the minor axis side is the vertical direction of the vehicle, it is easy to arrange.

<Modification>
In the above embodiment, the example in which the outer tube 21 is held by the short diameter portion 33 of the case 31 has been described. However, the outer tube 21 may be held by the long diameter portion of the case 31. In this case, the outer peripheral surface of the outer tube and the inner peripheral surface of the long diameter portion of the case may be connected with a rod-shaped spacer or the like. At this time, the periphery of the spacer becomes the exhaust gas circulation space. The outer tube may be held by both the short diameter part and the long diameter part. In addition, since the outer tube is held with respect to the inner tube via the catalyst, it may not be held with respect to the case. What is necessary is just to hold | maintain a case to the introduction part side and discharge part side exhaust pipe.

  The exhaust gas purifying apparatus of the present invention can be suitably used for purifying exhaust gas of an internal combustion engine.

DESCRIPTION OF SYMBOLS 1 Exhaust gas purification apparatus 2 Introducing part 3 Purifying part 4 Discharge part 10 Inner purifying part 11 Inner pipe 12 Inner catalyst 20 Outer purifying part 21 Outer pipe 21s Linear part 21r Folding part 22 Outer catalyst 31 Case 32 Distribution space 33 Short diameter part 200 Inlet side exhaust pipe 300 Exhaust side exhaust pipe

Claims (1)

An exhaust gas purification apparatus comprising: an introduction unit that introduces exhaust gas; a purification unit that purifies the exhaust gas; and a discharge unit that discharges the purified exhaust gas,
An inner purification part having an inner pipe whose one end is the introduction part and the other end is open, and an inner catalyst housed in the inner pipe for purifying exhaust gas;
An exhaust pipe that communicates with the opening side of the inner pipe and passes through the inner catalyst is folded back to the outside of the inner pipe and circulated to the introduction portion side, and is stored between the inner pipe and the outer pipe. And an outer catalyst that purifies the exhaust gas flowing through the outer pipe,
A space that communicates with the introduction portion side of the outer pipe and circulates the exhaust gas that has passed through the outer catalyst is folded outside the outer tube, and a side opposite to the introduction portion side of the outer pipe is the discharge portion. And a case,
The case has a flat cross section,
The inner pipe, the outer pipe, and the case are exhaust gas purifying devices arranged concentrically.

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