CN1184523A - Exhaust purification device for internal combustion engines - Google Patents

Abstract

The exhaust purification device is provided with a thin-walled steel plate (22) with catalyst metal on the central part of the section of the exhaust pipe (5) extending from the exhaust port (4) of the engine (3). That is to say, since the catalyst metal is arranged at the central part of the cross-section of the exhaust pipe (5) where the exhaust temperature is relatively high, in addition to fully exerting the purifying effect of the exhaust gas, the cost of the device can also be reduced.

Description

Exhaust purification device for internal combustion engines

technical field

The present invention relates to an improvement of an exhaust gas cleaning device for cleaning exhaust gases from an internal combustion engine, ie, an engine.

Background technique

Conventionally, as an exhaust purification device for an internal combustion engine, for example, "exhaust purification device for an internal combustion engine" disclosed in Japanese Patent Publication No. 3-85316 and "motorcycle, etc." disclosed in Japanese Patent Publication No. 4-287821. Exhaust purification device" is a public technology.

The above-mentioned Japanese Patent Publication No. 3-85316 discloses the "exhaust gas purification device for an internal combustion engine" as shown in Figures 17 and 18. The exhaust pipe 100 is connected to the exhaust port of a small internal combustion engine mounted on a motorcycle or the like. , along the inner wall of the exhaust pipe 100, an inner pipe 101 made of a perforated plate extending in the same direction as the exhaust pipe 100 is provided, and a catalyst carrier 102 is attached on the wall surface of the inner pipe 101.

The "exhaust purification device for motorcycles and the like" disclosed in the above-mentioned Japanese Patent Publication No. 4-287821 is shown in Fig. 19, Fig. 20 and Fig. 21. The exhaust port of the exhaust muffler (corresponding to the exhaust pipe) 110 is provided with a catalyst pipe 111 at the central part of the section, and a catalyst body 112 is installed in the catalyst pipe 111 . The catalyst body 112 has a catalyst material attached to the catalyst element of the honeycomb structure.

In general, in order to fully exert the activation effect of the catalyst, it is necessary to activate the catalyst at a high temperature. However, for small internal combustion engines, it is difficult to increase the exhaust gas temperature to the extent that the catalyst is activated. Therefore, it is necessary not only to increase the temperature of the catalyst as much as possible, but also to consider the fact that the temperature of the exhaust gas flowing through the exhaust pipe is relatively high in the center of the cross section of the pipe and relatively low near the pipe wall.

However, the "exhaust gas purification device of an internal combustion engine" shown in Fig. 17 and Fig. 18 has a catalyst-carrying inner pipe 101 along the inner wall of the exhaust pipe 100, so it is difficult to fully perform the purification function.

In the "exhaust purification device for motorcycles and the like" shown in Figures 19 to 21, a catalyst body 112 is provided at the central part of the cross section of the exhaust muffler 110. Because the exhaust gas temperature is relatively high, it is easy to perform the purification function. However, compared with the inner tube 101 made of a porous plate shown in FIGS. The flow velocity is relatively high in the central part of the pipe section, so the pressure loss is greater. As a result, the pressure loss greatly affects the performance of the internal combustion engine, and it is a factor that cannot be ignored particularly for a low output internal combustion engine such as a motorcycle. In addition, the structure in which the catalyst main body 112 composed of a catalyst element having a honeycomb structure is installed in the catalyst pipe 111 is compared with the structure in which the inner pipe 101 is arranged in the exhaust pipe 100 shown in FIGS. 17 and 18 . Further increase the manufacturing cost.

disclosure of invention

Therefore, it is an object of the present invention to provide an exhaust gas purification device for an internal combustion engine that (1) fully exerts the purification effect, (2) minimizes the influence on the performance of the internal combustion engine, and (3) is inexpensive.

According to the present invention, a thin-walled steel plate with a catalyst metal is provided approximately in the center of the cross section of the exhaust pipe extending from the exhaust port of the internal combustion engine. Therefore, by disposing the catalytic metal in the approximate center of the cross-section where the exhaust temperature is high in the exhaust pipe, the catalytic metal can be activated and the purifying effect of the exhaust gas can be sufficiently exhibited.

The thin-walled steel plate is preferably a cylindrical body extending in the axial direction of the exhaust pipe, so that the pressure loss when the exhaust gas passes through can be reduced.

The aforementioned cylindrical body is constituted by a perforated plate, and the exhaust gas upstream side of the cylindrical body is preferably sealed. That is, since the exhaust gas passes through the holes provided in the wall of the cylinder, the exhaust gas can contact the catalyst metal on the inner and outer surfaces of the second carrier. As a result, the area where the exhaust gas contacts the catalyst metal can be increased, and the purification effect of the exhaust gas can be improved.

Furthermore, in the present invention, in the substantially central part of the section of the exhaust pipe extending from the exhaust port of the internal combustion engine, a cylindrical body made of thin-walled steel plate with catalyst metal extending in the axial direction of the exhaust pipe is provided. In the air pipe, the cylinder body made of thin-walled steel plate is supported, and a partition plate for closing the passage between the cylinder body made of thin-walled steel plate and the exhaust pipe is provided. That is, the partition plate separates it from the front to the rear, restricts the pulsation of the exhaust gas from the internal combustion engine, and makes the flow generally smooth and stable. In this way, the purification capability of the exhaust gas purification device does not change, thereby improving the purification effect. In addition, since the cylinder body made of thin-walled steel plate is supported by the partition plate that restricts the pulsation of the exhaust gas, it is not necessary to use a special support member.

Furthermore, the cylindrical body made of the thin-walled steel plate is telescopically installed in the axial direction with respect to the aforementioned exhaust pipe, so that the thermal expansion that occurs between the cylindrical body and the exhaust pipe made of the thin-walled steel plate can be absorbed. The difference in the amount of extension between.

Furthermore, in the exhaust gas purification device of an internal combustion engine according to the present invention, a first carrier with a catalyst metal is provided along the vicinity of the inner wall of an exhaust pipe extending from an exhaust port of the internal combustion engine, and is disposed approximately in the center of the cross section of the first carrier. A second support with a catalyst metal. In other words, since the catalyst metal-carrying carrier is provided near the inner wall of the exhaust pipe and approximately in the center of the cross section, the purification effect of exhaust gas can be further improved without adversely affecting the performance of the internal combustion engine.

A brief description of the graphics

Fig. 1 is a side view of a motorcycle equipped with an exhaust purification system for an internal combustion engine according to a first embodiment of the present invention.

Fig. 2 is a side view of the first embodiment of the exhaust pipe of the present invention.

Fig. 3 is a sectional view of A-A in Fig. 2 .

Fig. 4 is a B-B sectional view in Fig. 3 .

Fig. 5 is a perspective view of the first embodiment of the second exhaust purification device of the present invention.

Fig. 6 is a C-C sectional view in Fig. 2 .

Fig. 7 is a D-D sectional view in Fig. 6 .

Fig. 8 is an E-E sectional view in Fig. 6 .

9A to 9E are diagrams illustrating assembly of the first embodiment of the second carrier of the present invention.

10A to 10D are schematic diagrams of modifications of the first embodiment of the second carrier of the present invention.

11A to 11H are schematic diagrams of modified examples of the supporting structure of the first embodiment of the second carrier of the present invention.

Fig. 12 is a perspective view of a second exhaust purification device of the second embodiment.

Fig. 13 is a sectional view taken along line F-F in Fig. 12 .

Fig. 14 is a schematic diagram of a modified example of the second exhaust purification device of the second embodiment.

Fig. 15 is a G-G sectional view in Fig. 14 .

Fig. 16A to Fig. 16E are schematic structural diagrams of the exhaust purification device of the third embodiment.

Fig. 17 is a cross-sectional view of an exhaust pipe in the prior art.

Fig. 18 is a partial longitudinal sectional view of a prior art exhaust pipe.

Fig. 19 is a plan view of a prior art exhaust muffler.

Fig. 20 is a partial sectional perspective view of a conventional exhaust purification device.

Fig. 21 is a longitudinal sectional view showing the structure of the vicinity of the catalyst tube in the prior art.

Best form for carrying out the invention

Embodiments of the present invention are described below according to the accompanying drawings. First, a first embodiment will be described with reference to FIGS. 1 to 9 .

In Fig. 1, a motorcycle 1 is equipped with a two-stroke engine (internal combustion engine) 3 near the center of the car body 2, an exhaust port 4 of the engine 3 is connected with an exhaust pipe 5, and the rear portion of the exhaust pipe 5 is connected with a muffler 6.

Figure 2 shows the exhaust pipe 5 of the present invention. This exhaust pipe 5 is made of a thin-walled steel plate with a circular structure in section, and its one end 5a is connected to the exhaust port 4 (referring to Fig. 1 ) of the engine 3 by a flange, and the other end 5b is connected by a flange. The muffler 6 (see FIG. 1 ) houses a first exhaust purification device 10 on the upstream side of the exhaust gas and a second exhaust purification device 20 on the downstream side of the exhaust gas. The first exhaust purification device 10 is a pre-purification device, and the second exhaust purification device 20 is a post-purification device. The portion of the exhaust pipe 5 where the second exhaust purification device 20 is arranged on the exhaust gas downstream side has a larger diameter than the other portions.

FIG. 3 shows a cross-sectional structure of the aforementioned first exhaust purification device 10 .

The first exhaust purification device 10 is composed of an inner pipe 11 arranged inside the exhaust pipe 5 . The inner pipe 11 is a cylindrical body extending in the same direction as the exhaust pipe 5 along the inner wall of the exhaust pipe 5, and is composed of a perforated plate made of thin steel plate. One end 11a of the inner pipe 11 is fixed to the exhaust pipe 5 by welding, and the other end 11b is supported by the supporting member 13, and can expand and contract relative to the exhaust pipe 5 in the axial direction. In this way, the difference in axial extension between the exhaust pipe 5 and the inner pipe 11 that occurs with thermal expansion can be absorbed.

The inner tube 11 is provided with a noble metal having a catalyst function such as platinum or rhodium (adhered by coating a solution containing the noble metal, etc.) on the wall surface with a plurality of holes 11c. The size of the middle portion of the exhaust pipe 5 is such that a gap 5 c can be provided between the inner pipe 11 and the inner pipe 11 .

The exhaust pipe 5 in FIG. 4 is made into a radially divided semi-cylindrical shape, and the two semi-cylindrical parts are welded together in a state where the inner pipe 11 is housed therein.

The supporting member 13 has a corrugated structure in the circumferential direction by rolling a corrugated plate (corrugated plate) into a cylindrical shape and fixing overlapping surfaces by spot welding. Therefore, the supporting member 13 can expand and contract in the radial direction with respect to the exhaust pipe 5 by elastic deformation, and absorbs the difference in elongation between the exhaust pipe 5 and the inner pipe 11 due to thermal expansion. However, the support member 13 is not limited to the structure constituted by the aforementioned corrugated plate, and may also adopt a structure formed into a ring shape by braiding stainless steel wires, for example.

Reference numerals 14, 14 denote protectors for covering the high-temperature exhaust pipe 5, which are formed as a pair divided in the radial direction. The protectors 14, 14 are fixed to several nuts 15 welded on the outer peripheral surface of the exhaust pipe 5 with bolts.

In FIG. 5, the second exhaust purification device 20 of the present invention is shown. The second exhaust purification device 20 is provided with a pair of first carriers 21, 21 along the vicinity of the inner wall surface of the exhaust pipe 5, and the substantially central portion of the cross-section of the first carriers 21, 21 (the substantially central portion of the exhaust pipe 5 ) is configured with a second carrier 22 , and the first carriers 21 , 21 and the second carrier 22 extend along the axial direction of the exhaust pipe 5 .

The first carrier 21, 21 is made of a pair of semi-cylindrical bodies divided radially, the second carrier 22 is made of a columnar cylinder with a diameter smaller than the first carrier 21, 21, and the first carrier 21, 21 and the second carrier 22 are made of Perforated plate made of thin-walled steel plate. The first carrier 21, 21 and the second carrier 22 are respectively provided with platinum or rhodium and other precious metals with catalyst function on the walls with a plurality of holes (21a, 22c) (attached by coating a solution containing precious metals, etc.). The exhaust pipe 5 is sized to have a gap between it and the first carrier 21 , 21 .

In FIG. 6, a support member 23 is provided on the exhaust upstream side (the left side of the figure) in the exhaust pipe 5 for supporting one end 22a of the second carrier 22 so that the second carrier 22 can be positioned relative to the exhaust gas. The trachea 5 expands and contracts in the axial direction. The support member 23 has a cushioning component 24 that supports one end 22a of the second carrier 22 and allows the one end 22a to pass through, an annular support 25 for installing the cushioning component 24 and fixing the support 25 on the row. Bracket 26 on the trachea 5. Therefore, it is possible to absorb the difference in axial extension that occurs between the exhaust pipe 5 and the second carrier 22 with thermal expansion.

A partition 27 for supporting the second carrier 22 and blocking the passage between the second carrier 22 and the exhaust pipe 5 is provided on the exhaust gas downstream side in the exhaust pipe 5 (right side in the figure). The above-mentioned partition plate 27 composed of an end plate (a slightly dish-shaped end plate) made of a thin-walled steel plate is fixed on the exhaust pipe 5 by plug-welding its flange portion 27a, and the second carrier 22 The other end portion 22b is inserted into and welded to a through hole 27b at a substantially central portion of the section, and fixed. One end (exhaust gas upstream side) 22 a of the second carrier 22 is closed by a cap 28 .

In FIG. 7, the cushioning member 24 has a corrugated structure in the circumferential direction by rolling a corrugated plate (corrugated plate) into a cylindrical shape and fixing the overlapped surfaces by spot welding. Therefore, the buffer member 24 can expand and contract in the radial direction with respect to the exhaust pipe 5 by elastic deformation, and absorbs the difference in elongation between the exhaust pipe 5 and the second carrier 22 due to thermal expansion.

As shown in FIG. 8 , both end portions of the pair of first carriers 21 , 21 are fixed by spot welding near the edge portion of the radially divided exhaust pipe 5 .

The following describes the assembly sequence of the second carrier 22 with the above structure according to FIG. 6 and FIGS. 9A-9E .

First, as shown in FIG. 9A, the cover 28 is fitted on the one end 22a of the second carrier 22, and then as shown in FIG. 9B, the edge of the second carrier 22 and the edge of the cover 28 are welded together Fix and block one end 22a.

Then, as shown in FIG. 9C, the other end portion 22b of the second carrier 22 is inserted into the through hole 27b of the partition plate 27, and fixed together by welding.

Then, as shown in FIG. 9D , the holder 25 on which the cushioning member 24 (see FIG. 6 ) is attached is inserted into the one end portion 22 a of the second carrier 22 , and assembled in the posture shown in FIG. 9E .

Finally, position the second carrier 22 in the posture shown in FIG. 9E within the lower half of the half-divided exhaust pipe 5 shown in FIG. The upper half of the exhaust pipe 5 is covered and the upper and lower halves are welded together, and the exhaust pipe 5 and the flange portion 27a of the partition plate 27 are connected together by plug welding, and the assembly operation is completed.

The functions of the first exhaust purification device 10 and the second exhaust purification device 20 will be described below based on FIGS. 2 and 6 .

As shown in Figure 2, when the exhaust gas from the engine flows in from the side of one end 5a of the exhaust pipe 5 and passes through the first exhaust purification device 10, it contacts and reacts with the noble metal on the inner pipe 11, and reaches the second exhaust after being purified. Purification device 20.

As shown in FIG. 6 , in the second exhaust purification device 20 , the exhaust gas flows from the left side of the figure. However, since the one end portion 22a of the second carrier 22 is closed by the cover 28, exhaust gas cannot flow in from this end portion 22a.

The part of the exhaust pipe 5 where the second exhaust purification device 20 is installed has a larger diameter than the other parts, and the front and rear of the exhaust pipe 5 are separated by the partition plate 27 , so that the upstream side of the exhaust gas becomes an expansion chamber 29 . Therefore, the pulsation of the exhaust gas from the engine 3 can be restricted by the expansion chamber 29, and the flow of the exhaust gas can be substantially smooth and stable. Therefore, the exhaust gas flows along the vicinity of the pipe wall of the exhaust pipe 5 along the direction indicated by the arrow in FIG. 6 , and the exhaust gas contacts and reacts with the noble metal on the first carrier 21 , 21 to achieve the purpose of purification.

Furthermore, the exhaust gas enters the second carrier 22 through several holes 22c on the wall of the second carrier 22, and is discharged into the atmosphere from the exhaust downstream side of the exhaust pipe through the other end 22b. When the exhaust gas passes through the second carrier 22, it contacts and reacts with the noble metal on the second carrier 22 to purify it.

In this case, since the exhaust gas passes through several holes 22c provided on the wall of the second carrier 22, and contacts with the catalyst metal on the inner and outer surfaces of the second carrier 22, the contact area between the exhaust gas and the catalyst metal can be increased to fully Play the role of purification of catalyst metals.

As described above, in order to fully exert the purifying effect of the catalyst metal, the catalyst must be activated at high temperature. On the other hand, the temperature of the exhaust gas flowing through the exhaust pipe 5 is relatively high at the center of the cross section of the pipe. Since the exhaust gas with a relatively high temperature flowing through the central part of the cross section of the exhaust pipe 5 also passes through in contact with the catalyst metal, the second carrier 22 can increase the temperature of the catalyst and fully activate it, fully exerting the purification effect . In addition, since the second carrier 22 is made of a cylinder made of a porous plate, it can reduce the pressure loss when the exhaust gas passes through, and reduce the impact on the performance of the engine.

In this way, the exhaust gas contacts with the noble metals on the first carriers 21 and 21 and the second carrier 22 to react and be purified, so the purification efficiency is high. In addition, since the flow of the exhaust gas is substantially smooth and stable, the purification capability of the second exhaust purification device 20 remains unchanged and the purification efficiency is high.

The temperature of the second carrier 22 is higher than that of the exhaust pipe 5 due to reaction heat or the like. Since the other end 22b of the second carrier 22 is fixed on the exhaust pipe 5 by the partition plate 27, when a difference in elongation occurs between the exhaust pipe 5 and the second carrier 22 due to thermal expansion, the second carrier 22 One end portion 22a can extend along the direction of the hollow arrow, so that the second carrier 22 can absorb the difference in the amount of extension. The difference in radial extension between the exhaust pipe 5 and the second carrier 22 can be absorbed by the elastic deformation of the damping element 24 .

The above-mentioned second carrier 22 adopts a structure in which the exhaust gas upstream side is closed, but a structure as shown in FIGS. 10A to 10D may also be used, for example.

10A to 10D show modifications of the second carrier 22 related to the first embodiment described above.

Fig. 10A shows a structure in which one end portion 22a of the second carrier 22 is closed by a cover 31 made of a perforated plate bulging toward the exhaust gas upstream side and formed by press forming.

FIG. 10B shows a structure in which one end 22 a of the second carrier 22 is flattened by extrusion as a cover 32 .

Resistor 10C shows the structure that several pieces of perforated plates are installed on one end 22a of the second carrier 22, and the plates made of these several pieces of perforated plates are installed in a spiral shape (windmill shape) and used as a cover 33 to increase The flow resistance of the exhaust gas.

FIG. 10D shows a structure in which one end portion 22a of the second carrier 22 is closed by a cover 34 made of a flat plate-shaped perforated plate. Instead of the cap 34 made of a flat perforated plate, one end 22a itself may be folded toward the center of the second carrier 22 to form a flat cap to close the upstream side of the exhaust gas.

Therefore, each cover 31, 32, 33, 34 shown in Fig. 10A to Fig. 10D has the same effect as the structure of the first embodiment, and since it is made of a perforated plate, by providing each cover 31, 32 , 33, 34, compared with the structure of the first embodiment, the pressure loss can be further reduced.

The supporting structure of the second carrier 22 is that one end of the second carrier 22 is telescopically supported in the axial direction relative to the exhaust pipe 5, and the other end is fixed on the exhaust pipe 5, as shown in Figures 11A to 11H, for example. Structure.

11A to 11H show modified examples of the supporting structure of the second carrier 22 of the first embodiment. The exhaust gas flows in the direction indicated by the arrow in these figures, and the one end portion 22a of the second carrier 22 is elongated in the direction indicated by the hollow arrow due to thermal expansion.

The supporting structure of the second carrier 22 shown in FIG. 11A is that one end 22 a of the second carrier 22 extends from the supporting member 23 toward the exhaust upstream side, and the one end 22 a is closed by a flat cover 28 .

The supporting structure of the second carrier 22 shown in FIG. 11B adopts a structure in which the exhaust gas upstream side of the supporting member 23 (the left side in the drawing) is closed by a cover 36 . There is a gap S1 between the one end portion 22a and the cover 36 that is larger than the elongation of the second carrier 22 due to thermal expansion. In this case, there is no need to attach a cover to the one end portion 22a of the second carrier 22 .

The supporting structure of the second carrier 22 shown in FIG. 11C adopts a structure in which the length of the support 25 of the supporting member 23 along the axial direction of the exhaust pipe 5 is longer than that of the bracket 26 .

The supporting structure of the second carrier 22 shown in FIG. 11D adopts a structure in which the second carrier 22 is supported by only one end of the partition plate 27 . The support member 37 is composed of a buffer member 38, a support 39 for accommodating the buffer member 38, and a partition plate 27 for fixing the support 39 on the exhaust pipe 5. The buffer member 38 supports the other end 22b of the second carrier 22. , so that the other end portion 22b can expand and contract in the axial direction of the exhaust pipe 5 . There is a gap S2 between the other end portion 22b and the flange 39a of the holder 39, and the gap S2 restricts the amount of movement and elongation of the other end portion 22b within the range of the gap S2.

FIG. 11E shows a modified example of the structure in FIG. 11D , and the lengths of the buffer member 38 and the support 39 are shorter than the structure in FIG. 11D .

The supporting structure of the second carrier 22 shown in FIG. 11F adopts that one end 22a of the second carrier 22 is fixed on the exhaust pipe 5 by a bracket 41, and the other end 22b of the second carrier 22 is supported by a support member 42. A structure supported at both ends that can expand and contract in the axial direction of the exhaust pipe 5 . The support member 42 is composed of a buffer member 43, a seat 44 for accommodating the buffer member 43, and a partition plate 27 fixing the seat 44 on the exhaust pipe 5. The buffer member 43 supports the other end 22b of the second carrier 22, so that The other end portion 22b is expandable and contractible in the axial direction of the exhaust pipe 5 . The other end portion 22b extends from the support member 42 toward the exhaust gas downstream side (left side in the figure).

The supporting structure of the second carrier 22 shown in FIG. 11G is a modified example of the structure in FIG. 11F. A cover 45 is installed on one end 22a of the second carrier 22 to close the one end 22a. The cover 45 has a punching Cut claws.

Fig. 11H is a modified example of the above-mentioned buffer members 24, 38, 43, which employs a ring-shaped buffer member 48 formed by weaving stainless steel wires. For example, the support member 46 is formed of a seat plate 47 wound on the other end portion 22b of the second carrier 22, inserted on the seat plate 47 and supports the other end portion 22b so that the other end portion 22b can move along the direction of the exhaust pipe 5. Two axially telescopic buffer members 48 at the front and rear, a cylindrical support 49 for accommodating the two buffer members 48 , and a partition plate 27 for fixing the support 49 to the exhaust pipe 5 are constituted.

The second embodiment of the second exhaust purification device will be described below based on FIGS. 12 and 13 .

In FIG. 12 , the second exhaust purification device 50 is provided with a first carrier 51 along the vicinity of the inner wall surface of the exhaust pipe 5, and the approximate central portion of the cross section of the first carrier 51 (approximately the center of the cross section of the exhaust pipe 5 Part) is provided with a second carrier 52. The first carrier 51 and the second carrier 52 extend along the axial direction of the exhaust pipe 5 .

The aforementioned first carrier 51 is formed of a cylindrical body with conical portions 51a, 51a at both ends in the axial direction, and one or both of the conical portions 51a, 51a are fixed to the exhaust pipe 5 by welding. The second carrier 52 is made of a flat plate, one or both ends of which are fixed in the first carrier 51 by welding.

The first carrier 51 and the second carrier 52 are composed of perforated plates made of thin-walled steel plates. The first carrier 51 and the second carrier 52 are respectively provided with platinum or rhodium and other noble metals having a catalyst function on the walls with a plurality of holes 51c and 52a (attached by coating a solution containing noble metals, etc.).

FIG. 13 shows a state in which the second carrier 52 constituted by a flat plate is erected inside the first carrier 51 .

The action of the second exhaust purification device 50 of the second embodiment described above will be described below with reference to FIG. 12 .

The exhaust gas of the engine flows in the direction indicated by the arrow in the figure, the exhaust gas flowing near the tube wall flows through several holes 51c provided on the wall of the first carrier 51, and the exhaust gas flowing through the roughly central part of the section passes through Flow through several holes 52a opened on the wall of the second carrier 52 . Therefore, the exhaust gas contacts and reacts with the noble metals on the first carrier 51 and the second carrier 52 to achieve the purpose of purification.

In this case, since the exhaust gas passes through several holes 52a provided on the wall of the second carrier 52, and contacts with the catalyst metal on the inner and outer surfaces of the second carrier 52, the contact area between the exhaust gas and the catalyst metal can be increased to fully Play the role of purification of catalyst metals.

The precious metal on the second carrier 52 can become high temperature due to contact with the relatively high temperature exhaust gas flowing through the central part of the cross section of the exhaust pipe 5, fully activated, and fully play the role of purification.

Since the second carrier 52 is constituted by a flat plate extending axially along the exhaust pipe 5, compared with the structure of the aforementioned first embodiment, the pressure loss when the exhaust gas passes can be further reduced.

The second exhaust purification device 50 of the above-mentioned second embodiment may also adopt the structures shown in FIGS. 14 and 15 .

That is, FIG. 14 shows a modified example of the second exhaust purification device 50 of the second embodiment. The cross-sectional shape of the first carrier 51 is a notched circular cross-section, which is formed by cutting away a part of the cylindrical body in the radial direction (for example, the lower part in FIG. 14 ).

In FIG. 15 , flange portions 51 b , 51 b formed by bending both edges of the notched section of the first carrier 51 are connected to the inner wall of the exhaust pipe 5 . The second carrier 52 passes through the notch of the first carrier 51 and is connected to the inner wall of the exhaust pipe 5 .

16A to 16E show a schematic structure of an exhaust purification device according to a third embodiment of the present invention.

The exhaust purification device 61 of Fig. 16A adopts the structure that two-stage purification devices are arranged in the exhaust pipe 5, and a regulating valve (such as a butterfly valve) for adjusting the exhaust gas volume is installed between the front-stage purification device and the rear-stage purification device. 62. The pre-stage purification device adopts the structure of the first exhaust purification device 10 shown in FIG. 3 , and the post-stage purification device adopts the structure of the second exhaust purification device 50 shown in FIG. 12 .

The exhaust purification device 63 in FIG. 16B adopts a structure in which three stages of purification devices are installed in the exhaust pipe 5 . The pre-stage purification device adopts the structure of the first exhaust purification device 10 shown in FIG. 3 , the middle stage purification device adopts the structure of the second exhaust purification device 50 shown in FIG. The other end portion 5 b of the exhaust pipe 5 is extended to the structure of the outlet pipe 64 inside the exhaust pipe 5 . The lead-out pipe 64 is made of a perforated plate made of thin-walled steel plate. On the wall surface with a plurality of holes, precious metals such as platinum or rhodium are provided with catalytic functions (attached by coating a solution containing precious metals, etc.).

The exhaust purification device 65 in FIG. 16C has a structure in which a carrier 66 extending in the axial direction of the exhaust pipe 5 is provided at the substantially central portion of the cross section of the exhaust pipe 5 . The carrier 66 is a flat plate made of a porous plate made of a thin-walled steel plate. On the wall surface with a plurality of holes, precious metals with catalyst functions such as platinum or rhodium are provided (attached by coating a solution containing precious metals, etc.) .

The exhaust gas purification device 67 in FIG. 16D is a modified example of the exhaust gas purification device shown in FIG. 16C . Instead of a flat plate structure, the carrier 66 adopts a corrugated plate (corrugated plate) structure.

The exhaust purification device 68 in FIG. 16E adopts a structure in which a semi-cylindrical carrier 69 is arranged, and the axial ends of the semi-cylindrical carrier 69 extending axially along the exhaust pipe 5 are closed. The radially open end 69 a of the carrier 69 is arranged at a substantially central portion of the cross section of the exhaust pipe 5 . The carrier 69 is made of a porous plate made of thin-walled steel plate. On the wall surface with a plurality of holes, a precious metal having a catalytic function such as platinum or rhodium (attached by coating a solution containing a precious metal, etc.) is provided.

The carriers 66 and 69 shown in FIG. 16C , FIG. 16D and FIG. 16E are also applicable to the structure in which multi-stage purification devices are arranged in the exhaust pipe 5 shown in FIG. 16A and FIG. 16B .

The "thin-walled steel plate" with the catalyst metal in the above-mentioned first, second, third embodiments and their modified examples is installed in the approximate center of the cross section of the exhaust pipe 5 or in the approximate cross section of the first carrier 21, 51. For the central part, as a specific example, for the first embodiment shown in Figures 1 to 9 and the modified examples shown in Figures 10 and 11, a second carrier 22 made of a cylinder made of a perforated plate is used. structure, for the second embodiment shown in Fig. 12 and Fig. 13, the modified example shown in Fig. 14 and Fig. 15 and the third embodiment shown in Fig. 16A and Fig. 16B, the flat plate made of perforated plate is used The structure of the second carrier 52, for the third embodiment shown in Fig. 16C, Fig. 16D and Fig. 16E, adopts the structure of carriers 66, 69 made of a flat plate made of a porous plate, a corrugated plate or a semi-cylindrical shape.

In this way, in the present invention, "thin-walled steel plate" is not limited to the structures of the above-mentioned embodiments or modifications thereof, and there is no limitation on the structure of the perforated plate, and the hole shape, hole size and number of the perforated plate can be arbitrary. of.

Industrial Applicability

In the above-mentioned exhaust purification device for an internal combustion engine of the present invention, since the thin-walled steel plate with the catalyst metal is provided in the approximate center of the section of the exhaust pipe extending from the exhaust port of the internal combustion engine, the catalyst metal is placed at a place where the exhaust gas temperature is high. Therefore, the catalytic metal can be activated to fully exert its exhaust gas purification effect, and the cost can be reduced.

In addition, the exhaust gas purification device of the internal combustion engine of the present invention, because the thin-walled steel plate is a cylinder extending axially along the exhaust pipe, can reduce the pressure loss when the exhaust gas passes through, and has the advantage that it will not affect the performance of the internal combustion engine .

Furthermore, the exhaust purification device of the internal combustion engine of the present invention, since the cylinder body is made of a perforated plate, the exhaust gas upstream side of the cylinder body is sealed, and the exhaust gas passes through a plurality of holes opened on the cylinder body wall, so that the exhaust gas is exhausted. The gas contacts the catalyst metal on the inner and outer surfaces of the second support. As a result, the area where the exhaust gas contacts the catalyst metal can be increased, and the exhaust gas purification effect can be further improved.

Furthermore, in the exhaust purification device of the internal combustion engine of the present invention, since the substantially central part of the section of the exhaust pipe extending from the exhaust port of the internal combustion engine is provided with a thin-walled steel plate with catalyst metal extending in the axial direction of the exhaust pipe. The cylinder made of thin-walled steel plate is supported in the exhaust pipe, and the passage between the cylinder made of thin-walled steel plate and the exhaust pipe is closed by a partition, so that the catalyst metal is arranged in the exhaust pipe. Therefore, the catalyst metal can be activated to fully exert its exhaust gas purification effect, and the cost can be reduced. In addition, since the front and rear are separated by the partition, the pulsation of the exhaust gas from the internal combustion engine is limited, and the flow becomes a basically stable and smooth flow. Therefore, the purification ability of the exhaust purification device will not be changed, and its purification can be fully utilized effect. In addition, since the cylinder body made of thin-walled steel plate is supported by the partition plate that restricts the pulsation of the exhaust gas, special support members are not required, and the support structure can be simplified.

In addition, in the exhaust purification device of an internal combustion engine of the present invention, since the cylinder body made of thin-walled steel plate is telescopically installed in the axial direction relative to the exhaust pipe, it is easy to absorb the cylinder body and exhaust gas caused by thermal expansion. The difference in elongation between tubes.

In addition, in the exhaust gas purification device of an internal combustion engine according to the present invention, a first carrier with a catalyst metal is provided along the vicinity of the inner wall surface of the exhaust pipe extending from the exhaust port of the internal combustion engine, and a catalyst-carrying metal is provided at the approximate center of the cross-section of the first carrier. The second carrier of the metal, so that the carrier with the catalyst metal is arranged at two positions near the inner wall surface of the exhaust pipe and at the approximate center of the cross section, so that the exhaust gas purification effect can be further improved without affecting the performance of the internal combustion engine. It has the advantage that the cost can be further reduced.

Claims (8)

1. An exhaust purification device for an internal combustion engine, comprising an internal combustion engine (3) and an exhaust pipe (5) extending from the exhaust port (4) of the internal combustion engine (3) for purifying the exhaust gas from the aforementioned internal combustion engine (3) ), which is characterized by, A thin-walled steel plate (22) with a catalyst metal is provided approximately in the center of the section of the exhaust pipe (5). 2. The exhaust purification device of an internal combustion engine according to claim 1, wherein the thin-walled steel plate (22) is a cylindrical body extending axially along the exhaust pipe (5). 3. The exhaust gas purification device of an internal combustion engine according to claim 2, wherein said cylindrical body is formed of a perforated plate, and the upstream side of the exhaust gas is sealed. 4. An exhaust purification device for an internal combustion engine, comprising an internal combustion engine (3) and an exhaust pipe (5) extending from the exhaust port (4) of the internal combustion engine (3) for purifying the exhaust gas from the aforementioned internal combustion engine (3) ), which is characterized by, In the approximate central part of the section of the aforementioned exhaust pipe (5), a cylindrical body (22) made of a thin-walled steel plate with catalyst metal extending axially along the aforementioned exhaust pipe (5) is provided. (5), support the cylinder body (22) that aforementioned thin-walled steel plate is made, and be provided with the passageway between the cylinder body (22) that aforementioned thin-walled steel plate is made and exhaust pipe (5) Partition (27). 5. The exhaust purification device of an internal combustion engine according to claim 4, characterized in that the cylinder body (22) made of thin-walled steel plate is telescopically installed in the axial direction relative to the exhaust pipe (5). 6. An exhaust purification device for an internal combustion engine, comprising an internal combustion engine (3) and an exhaust pipe (5) extending from the exhaust port (4) of the internal combustion engine (3) for purifying the exhaust gas from the aforementioned internal combustion engine (3) ), which is characterized by, A first carrier (21, 51) with a catalyst metal is provided along the vicinity of the inner wall of the exhaust pipe (5), and a second carrier with a catalyst metal is arranged approximately in the center of the section of the first carrier (21, 51). (22, 52). 7. The exhaust purification device of an internal combustion engine according to claim 6, characterized in that, the first carrier (51) is made of a cylinder, and the second carrier (52) is made of a flat plate. 8. The exhaust purification device of an internal combustion engine according to claim 6, characterized in that the first carrier (21, 51) and the second carrier (22, 52) have several holes (21a, 51c, 22c, 52a ).

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