Title of Invention

"AN EXAUST GAS PURIFICATION DEVICE"

Abstract

An exhaust gas purification device characterized in that a small and a large diameter exhaust gas purifiers of tubular shaped punching metal each of which has a catalyst loaded therein extend in series from an end part of an exhaust pipe to an expansion chamber, the large diameter exhaust gas purifier overlaps with the small diameter exhaust gas purifier, and a reinforcing ring is attached to the overlap part of the large diameter exhaust gas purifier.

Full Text

The present invention relates to an exhaust gas purification device for use with internal combustion engines for motor-bicycles, etc. Technology incorporating exhaust gas purification devices for vehicles with the purpose of preventing atmospheric pollution are well known, of which Japanese Patent Laid Open Application No. Hei 3 - 85320 is one example. [0003] This device, as shown in Fig. 1 of the same publication, comprises an inner pipe 5 punched with a plurality of small holes, mounted inside an exhaust pipe 3, so that unburned elements in exhaust gas are oxidized by a catalyst loaded in the inner pipe 5. [0004] [Problem To Be Solved By The Invention] The exhaust pipe 3, as shown in Fig. 6, is an exhaust pipe forming an abbreviated C shape (namely, a bend pipe) and containing the inner pipe 5 with catalyst loaded therein. The reason that the inner pipe 5 is contained within the exhaust pipe 3 is to react the high temperature exhaust gas with the catalyst loaded in the inner pipe 5 to maintain high exhaust gas purification performance. However, by doing this, due to the close location of the inner pipe 5 containing the punched holes to exhaust outlet 2, the punched holes cause a disturbance in the exhaust gas flow, causing a substantial effect on the output characteristics of the engine, resulting in a decline in output. [0005] Therefore, the object of the present invention is to produce a exhaust gas purification device which maintains high exhaust gas purification performance by producing an efficient catalytic reaction, and which does not effect the output characteristics of the engine. Accordingly, there is provided an exhaust gas purification device characterized in that a small and a large diameter exhaust gas purifiers of tubular shaped punching metal each of which has a catalyst loaded therein extend in series from an end part of an exhaust pipe to an expansion chamber, the large diameter exhaust gas purifier overlaps with the small diameter exhaust gas purifier, and a reinforcing ring is attached to the overlap part of the large diameter exhaust gas purifier. [Means for Solving the Problems] To achieve the aforementioned object, Claim 1 of the present invention is characterized by being tubular in shape, having small and large diameter exhaust gas purification devices with catalysts mounted in series from an end part of an exhaust pipe to an expansion chamber, with the small diameter exhaust gas purification device being overlapped by the large diameter exhaust gas purification device, and a reinforcing ring being attached to the overlap part of the large diameter exhaust gas purification device. As the two exhaust gas purification devices are constructed so that they are mounted in series from the end part of the exhaust pipe part of the exhaust pipe to the expansion chamber, neither of the exhaust gas purification devices produces a disturbance in the exhaust gas in a location near to the exhaust outlet. Therefore, there is no concern of an effect on the output characteristics of the engine. Also, as an oxidizing reaction is caused in the first stage of the exhaust gas purification device, followed consecutively by a oxidizing reaction in the second stage of the exhaust gas purification device, even if the catalyst is located where the temperature of the exhaust gas decreases, the second stage exhaust gas purification device can increase the temperature of the catalyst to enable an efficient reaction, thereby efficiently oxidizing the unburned elements in the exhaust gas, rendering these elements harmless. Furthermore, there is the possibility that the large diameter exhaust gas purification device may become ovoid in shape due to heat distortion and come into contact with the small diameter exhaust gas purification device inside. A reinforcing ring has therefore been fitted to the overlapping part of the large diameter exhaust gas purification device, restricting any shape distortion, thereby enabling the exhaust gas purification devices to continue functioning correctly. Claim 2 is characterized by having small and large diameter exhaust gas purification devices with loaded catalysts mounted in series from an end part of an exhaust pipe to an expansion chamber, with the small diameter exhaust gas purification device being overlapped by the large diameter exhaust gas purification device, and the density of punched holes in the overlap part being less than the density for the remaining parts.As the two exhaust gas purification devices are constructed so that they are mounted in series from the end part of the exhaust pipe part of the exhaust pipe to the expansion chamber, neither of the exhaust gas purification devices produces a disturbance in the exhaust gas in a location near to the exhaust outlet. Therefore, there is no concern of an effect on the output characteristics of the engine. Also, as an oxidizing reaction is caused in the first stage of the exhaust gas purification device, followed consecutively by a oxidizing reaction in the second stage of the exhaust gas purification device, even if / 5J the catalyst is located where the temperature of the exhaust gas decreases, the second stage exhaust gas purification device can increase the temperature of the catalyst to enable an efficient reaction, thereby efficiently oxidizing the unburned elements in the exhaust gas, rendering them harmless. In addition, there is the possibility that the large diameter exhaust gas purification device may become ovoid in shape due to heat distortion and come into contact with the small diameter exhaust gas purification device. A reinforcing ring has therefore been fitted to the overlap part of the large diameter exhaust gas purification device, restricting any shape distortion, thereby enabling the exhaust gas purification devices to continue functioning correctly. [Brief Description of the Drawings] [Fig. 1] A side view of the exhaust gas purification device relating to the present invention fitted to a motor bicycle. [Fig. 2] A plan view of the exhaust gas purification device relating to the present invention fitted to a motor bicycle. [Fig. 3] A side view of the exhaust gas purification device relating to the present invention fitted to an exhaust pipe. [Fig. 4] A cross sectional view of the main parts of the exhaust gas purification device relating to the present invention. [Fig. 5] A cross sectional view taken along line 5-5 of Fig. 4. [Fig. 6] A side view of the catalyst containing first pipe member relating to the present invention. [Fig. 7] A cross sectional view taken along line 7-7 of Fig. 4. [Fig. 8] A cross sectional view taken along line 8-8 of Fig. 4. [Fig. 9] A cross sectional view of the catalyst containing second pipe member relating to the present invention. [Fig. 10] A first view describing a manufacturing process for the exhaust gas purification device relating to the present invention. [Fig. 11] A second view describing a manufacturing process for the exhaust gas purification device relating to the present invention. [Fig. 12] A third view describing a manufacturing process of the exhaust gas purification device relating to the present invention. [Embodiments] The following is an explanation of the embodiments of the present invention based on the attached drawings. The drawings are to be viewed from the direction of the numbers. Fig. 1 is a side view of a motor bicycle fitted with the exhaust gas purification device relating to the present invention. In a motor bicycle 1, a front fork 4 is pivoted via a head pipe 3 on the front part of a main frame 2. A front wheel 5 and front fender 6 are attached to the front fork 4. An engine hanger part 7 is attached to the lower part of mainframe 2, with a two cycle engine 8 being attached via the engine hangar part 7. An exhaust pipe 50 extends from the two cycle engine 8, a cantilevered swing arm 11 is pivoted via a pivot 9 at the end part of the mainframe 2. A rear wheel 12 is attached to the swing arm 11. In the diagram, 14 is a fuel tank, 15 is an air cleaner, 16 is a carburetor, 17 is a seat, 18 and 19 are seat rails, 20 is a pillion passenger seat, 21 is a rear suspension, 22 is a drive chain and 23 is a silencer. Also, 25 is a meter, 26 is a headlight, 27 are indicators attached to the left and right aperture parts of the front part of a cowling 28, 30 is a brake disk, 31 is a caliper, 32 is a radiator, 33 is a drive pulley for the exhaust timing control valve attached to the upper rim of the exhaust outlet of the engine 8, 34 is a drive motor for an exhaust timing control valve, 35 is an intake chamber, 36 is a battery, 37 is an oil tank, 38 is a tail light, 39 is a seat cowling and 40 is a rear axle. Fig. 2 is a plan view of a motor bicycle fitted with an exhaust gas purification device relating to the present invention. An exhaust pipe 50, after extending from the center to the rear of the vehicle body, goes around the rear suspension 2 1 and cantilevered swing arm 1 1 , and when seen from the riders position, extends from the right hand side of the vehicle body to the rear. In the diagram, 42 and 42 are riders steps, 43 is a brake pedal, 44 is a gear change pedal, and 45 is a handlebar. Fig. 3 is a side view of an exhaust pipe fitted with the exhaust gas purification device relating to the present invention. Exhaust pipe 50 described in Fig 1 contains an exhaust gas purification part 60, and is fitted with a bent tube shaped exhaust pipe part 5 1 , expansion chamber 52, and tail pipe part 56. Expansion chamber 52 consists of a divergent part 53 in which the cross sectional area of the duct gradually increases in the direction of the gas flow, a straight part 54 having the same cross sectional area which remains constant, and a convergent part 55 having the same cross sectional area which decreases gradually. As indicated by the dotted line, the divergent part 53 may be formed from the end part of the exhaust pipe part 51. The exhaust gas purification device 60 is described in Fig. 4. Furthermore, the above mentioned "Exhaust pipe" refers to only the bent pipe directly below the engine, and not the entire exhaust pipe. 58 is a metal hanger. Fig. 4 is a cross sectional view of the main parts of the exhaust gas purification device relating to the present invention. The exhaust gas purification device 60 consists of a first small diameter pipe member containing catalyst (small diameter exhaust gas purification device) 61 mounted on the end of exhaust pipe part 51 , and a second large diameter pipe member containing the catalyst (large diameter exhaust gas purification device) 71 mounted onto an expansion chamber 52. The catalyst containing first pipe member 61 and catalyst second containing pipe member 71 are mounted in series and in a direct line from the rear part of the exhaust pipe part 51 of exhaust pipe 50 to the expansion chamber 52. The front end part of the catalyst containing second pipe member 71 overlaps the rear end part of catalyst containing first pipe member 61. In addition, the density of the punched holes in the region of the overlapping part 94 (henceforth referred to as " overlap part 94") of first and catalyst containing second pipe members 61 and 71 is lower than for the other parts. Namely, the region of the overlap part 94 of the catalyst containing first pipe member 61 consists of the low hole density part 103 and the no hole part 10 Ib, and, the region of the overlap part 94 of the catalyst containing second pipe member 71 consists of the low hole density part 87 and the no hole part 85a. Also, reinforcing ring 93 is inserted into the no hole part 85a of the overlap part 94 of the catalyst containing second pipe member. The no hole parts lOlb and 85a are regions where there is no punched holes, and the low hole density parts 103 and 87 are regions with a lower punched hole density than other parts. An insertion member was used as the reinforcing ring 93 of the overlap part 94 of the catalyst containing second pipe member 71. Examples of other members which could also be used as reinforcing rings are members which wrap around the catalyst containing second pipe member 71 and a protruding member formed around the periphery of catalyst containing second pipe member 71. Further, the small diameter catalyst containing first pipe member 61 was mounted upstream, and the large diameter catalyst containing second pipe member 71 was mounted down stream. However, it is also possible to mount the large diameter catalyst containing second pipe member 71 upstream, and the small diameter first catalyst containing pipe 61 down stream. Fig 5 is a cross sectional view taken along line 5-5 of FIG. 4, and shows the construction of the support stay supporting the catalyst containing first pipe member 61. A support stay 62 consists of a W shaped support fitting 63, and outer ring 64 welded to the support fitting 63. Due to assembly considerations, the outer ring 64 is divided in two, into upper and lower sections. Between the outer ring 64 and inner ring 109 (refer also to Fig. 6) toroidal elastic material 65 has been added. For elastic material 65, as with the elastic material 75, stainless wool, having both heat resistance and cushioning properties, is ideally suited. The exhaust pipe part 51 comprises a combination of a right side semi-circular pipe 51R and a left side semicircular pipe 51L, with the support fitting 63 of the support stay 62 being welded in place to the right side semicircular pipe 51R. The support stay 62 supports the catalyst containing first pipe member 61 in the center of the cross section of exhaust pipe, part 5 1 . Fig. 6 is a cross sectional view of the catalyst containing first pipe member relating to the present invention. The catalyst containing first pipe member 61 consists of tubular shaped punching metal with a loaded catalyst, with the butt of matching end parts 105 and 106 welded together. Region lOla where the central inner ring 109, 109 inserts and right end part region lOlb of the catalyst containing first pipe member are no hole parts. Also, lOlc and lOlc of a set width region parallel to the butt weld part 107 of the welded end parts 105, 106 are no hole parts. Ep0^4} The edges joining no hole parts lOla, lOlb of the catalyst containing first pipe member 61 are low hole density parts 103., and the other parts are hole parts 102a, 102b. No hole parts lOla, lOlb, lOlc, lOlc are regions without punched holes 90, low hole density parts 103. are regions containing punched holes 90. (namely, in a "rough" condition). The hole parts 102a, 102b are regions with a comparatively high density of punched holes 90. The open white arrow indicates the direction of the flow of the exhaust gas. [00353 Fig. 7 is a cross sectional view taken along line 7-7 of Fig. 4, and shows the construction of front part support stay supporting the catalyst containing second pipe member 71. The front part support stay 72F comprises a W shaped support fitting 73F, and outer ring 74 welded to the support fitting 73F. Due to assembly considerations, the outer ring 74 is divided in two, into left and right sections. Toroidal elastic material 75 has been added between the outer ring 74 and inner ring 92. For the elastic material 75, stainless wool, having both heat resistance and cushioning properties, is ideally suited. Expansion chamber 52 consists of a combination of an upper shell 52T and a lower shell 52B. The W shaped support fitting 73F of the front part support stay 72F is welded in place to only the upper shell 52T. By welding the W shaped support fitting 73F of the front part support stay 72F to the upper shell 52T, the front part support stay 72F supports the second catalyst containing member 7 1 in the center of the cross section of the expansion chamber 52. Fig. 8 is a cross sectional view taken along line 8-8 of Fig. 4, and shows the construction of the end part support stay supporting the catalyst containing second pipe member 71. The shape of the W shaped support hardware 73R of end support stay 72R is only slightly different to that of the front part support stay 72F, and, as it is basically of the same construction as the front support stay 72F, it has been given the same symbols and a description has been omitted. Fig. 9 is a side view of the catalyst containing second pipe member relating to the present invention. The catalyst containing second pipe member 71 comprises tubular shaped punching metal containing the catalyst, with the butt of matching end parts 81, 82 welded together. Regions 85a, 85b, 85c of the catalyst containing second pipe member 71 where the left end part reinforcing ring 93, central inner ring 92, and right end inner ring 92 insert are no hole parts. Also, 85d and 85d, of a set width region parallel to the butt weld part 91 of the welded end parts 81, 82, are no hole parts. [0029} The edge connecting no hole part 85a and 85b and 85c of the catalyst containing second pipe member 71 is a low hole density part 87, while the other parts are hole parts 86a, 86b. No hole parts 85a, 85b, 85c, 85d, 85d are regions with no punched holes 90, low hole density part 87... is a region of a low density of punched holes 90. Furthermore, the reinforcing ring 93 suppresses the thermal change which occurs in the left end part of the catalyst containing pipe member 71 when the catalyst containing pipe member 71 is heated by exhaust gas. The open white arrow indicates the direction of the flow of the exhaust gas. t r\f\*VT\~i flptstjj The manufacturing process of the catalyst containing second pipe member 71 is explained in the following order: Fig. 10, Fig. 6, Fig. 5, Fig. 4. Fig. 10 is the first explanatory diagram of the manufacturing process of the exhaust gas purification device relating to the present invention, and shows punching metal 100 used in the manufacture of the catalyst containing first pipe member 61. Firstly, the high density and low density punching of pluralities of punched holes 90. in the correct location of the rectangular punching metal 100 is carried out, providing the punch metal 100 with no hole parts lOla, lOlb, lOlc, lOlc, low density hole parts 103, and hole parts 102a, 102b. The no hole parts lOla, lOlb, lOlc, lOlc are located on the upper and lower edges of the central part and the right end part of the punching metal 100. The low density hole parts 103 is located on the periphery of the hole parts 102a and 102b. Next, punching metal 100 is rounded, and as shown in Fig. 6, the end part 105 and the end part 106 butt welded to form first pipe member 6 la. Next, a thin coating of active alumina is applied to the internal and external surfaces of the first pipe part 61a and a catalyst element is added to this active alumina layer to produce the catalyst containing second pipe member 61. After this, the inner ring 109, 109 is mounted by welding to the left side no hold part lOla of the catalyst containing first pipe member -{00333 Next, as shown in Fig. 5, the heat resistant elastic materials 65, 65 are inserted into the inner ring 109, 109 (only one is shown), and the elastic material is held by the two piece outer ring 64. Next, the catalyst containing first pipe member 61 is mounted inside the exhaust pipe part 51 by the support fitting 63 of the outer rings 64, and 64 (Refer to Fig. 4). / Next, the manufacturing process for the catalyst containing second pipe member 71 is explained in the following order: Fig. 11, Fig. 12, Fig. 9, Fig. 6, Fig. 7, Fig. 4. Fig. 11 is a second view describing the manufacturing, process of the exhaust gas purification device relating to the present invention, and shows punching metal 80 used in the manufacture of the catalyst containing second pipe member 71. Firstly, the high density and low density punching of multiple punched holes 90 in the correct location of the rectangular punching metal 80 is carried out, providing the punching metal 80 with no hole parts 85a, 85b, 85c, 85d, 85d, low density hole part 87, and hole parts 86a, 86b. The no hole parts 85a ~ 85d are located on the upper and lower edges of the left end part, central part and the right end part of the punching metal 80. The low density hole parts 87 are located on the upper, lower, left and right edges adjoining the hole parts 86a and 86b. Fig. 12 is a third view describing a manufacturing process for the exhaust gas purification device relating to the present invention, and shows the catalyst containing second pipe member 71 rounded into a tubular form. As shown in Fig. 1 1, the rectangular punched metal 80 is rounded, and upper edge part 8 1 and lower edge part 82 are butt welded to form second pipe member 7 la. Next, a thin coating of active alumina is applied to the internal and external surfaces of the second pipe part 7 la and a catalyst element is added to this active alumina layer to produce the catalyst containing second pipe member 71. Next, inner rings 92 and 92 are placed over the central no hole part 85b and the right edge no hole part 85c of the catalyst containing second pipe member 71 and the cutaway section of central inner ring 92a and catalyst containing second pipe member 71 are welded together. 92b, 92b are the butt weld parts of the inner rings 92 and 92. Moreover, a reinforcing ring 93 is placed over left edge part of no hole part 85a of the catalyst containing second pipe member 71, the left edge part of the reinforcing ring 93 and the left end part of the catalyst containing second pipe member 7 1 are welded together. [003S1 As a result of the above mentioned manufacturing process, the reinforcing ring 93 and the inner rings 92, 92 are mounted to the no hole parts 85a, 85b and 85c of the catalyst containing second pipe member 7 1 as shown in Fig. 9. Next, as shown in Fig. 6 and Fig. 7, the heat resistant toroidal elastic materials 75 and 75 are inserted into the inner rings 92 and 92 and the elastic materials 75 and 75 are held in place by the two piece outer rings 74, 74. Next, support fittings 73F and 73R are welded to the inside of the expansion chamber 52 and the catalyst containing second pipe member 71 is mounted to the inside of the expansion chamber 52 (Refer to Fig. 4). ,/ The following is an explanation of the action of exhaust gas purification device 60 relating to the present invention. As shown in Fig. 4, the exhaust gas entering exhaust pipe part 51 (the open arrow indicates the direction of the exhaust gas flow) of the exhaust pipe 50 passes along the inside and outside of the catalyst containing first pipe member 61 and second catalyst containing part 71. Here, the catalyst containing first pipe member 61 and the catalyst containing second pipe member 7 1 are mounted in sequence and in a direct line from the end part of the exhaust pipe part 5 1 of the exhaust pipe 50 to the expansion chamber 52. Therefore, both catalyst containing pipe members 61 and 71 do not cause a disturbance in the exhaust gas in a location near to the exhaust outlet (the front part of exhaust pipe 5 1 of Fig. 3). As a result, there are no effects on the output characteristics of the engine. Also, as the end part of the catalyst containing first pipe member 61 and the front part of the catalyst containing second pipe member 7 1 are overlapped, the oxidizing reaction caused in the catalyst containing first pipe member 61 is followed consecutively by an oxidizing reaction in the catalyst containing second pipe member 71. Therefore, even if the catalyst containing second pipe member 71 is mounted in a location where the temperature of the exhaust gas decreases, the catalyst of catalyst containing second pipe member 7 1 can be heated to a temperature to enable an efficient reaction, thereby efficiently oxidizing the unburned elements in the exhaust gas, rendering them harmless. However, conversely, should the catalyst containing second pipe member become oval in shape due to heat distortion, there is the danger that it will come into contact with the catalyst containing first pipe member 61 inside. To control any damaging shape distortion, reinforcing ring 93 has been fitted to the over lap part 94 of the catalyst containing second pipe member 71, and the density of the punched holes 90... in the overlap part have been reduced compared to that of the other parts. Furthermore, the same effect can be obtained by implementing only one of the above mentioned methods, namely attaching reinforcing ring 93 to the overlap part 94 of the catalyst containing second pipe member 7 1 , or compared to other parts, reducing the density of punched holes 90... in the overlap part of the catalyst containing second pipe member 71. [OQ44-] As shown in Fig. 9, the lateral part of no hole parts 85a, 85b and 85c of the catalyst containing second pipe member 71 adjoin with low hole density part 87. Therefore, when the catalyst containing second pipe member 71 is heated by the exhaust gas, as the heat distribution in the region extending from the left side of the no hole part 85a to the low hole density parts 87 changes gently, there is no concern of cracking occurring from the punched holes 90. Similarly, there is a gentle change in the heat distribution in the region extending from central no hole part 85b to hole parts 86a and 86b, and there is also a gentle change in heat distribution in the region extending from the right side of the no hole parts 85c to 86b. Therefore, there is no concern of cracking occurring from the punched holes 90 in these regions. Also, as the butt weld 91 adjoins no hole parts 85d and 85d, it is possible to separate the butt weld part 91 from the hole part. Therefore, when the catalyst containing second pipe member 71 is heated by exhaust gas, there is no concern of cracking from the hole part towards the butt weld part 91. Furthermore, an explanation has been given for use of the exhaust gas purification device of the present embodiments in motor bicycles, however, of course the exhaust gas purification device of the present invention can be used on the exhaust pipes of industrial machinery and other internal combustion engines. The present invention of the above construction produces the following effects. In Claim 1 , as the two exhaust gas purification devices are constructed so that they are mounted in series from the end part of the exhaust pipe part of the exhaust pipe to the expansion chamber, neither of the exhaust gas purification devices produces a disturbance in the exhaust gas in a location near to the exhaust outlet. Therefore, there is no concern of an effect on the output characteristics of the engine. , Also, as an oxidizing reaction is caused in the first stage of the exhaust gas purification device, followed consecutively by a oxidizing reaction in the second stage of the exhaust gas purification device, even if the catalyst is located where the temperature of the exhaust gas decreases, the second stage exhaust gas purification device can increase the temperature of the catalyst to enable an efficient reaction, thereby efficiently oxidizing the unburned elements in the exhaust gas, rendering them harmless. In addition, conversely, there is the possibility that the large diameter exhaust gas purification device may become ovoid in shape due to heat distortion and come into contact with the small diameter exhaust gas purification device inside. A reinforcing ring has therefore been fitted to the overlapping part of the large diameter exhaust gas purification device, restricting any shape distortion, thereby enabling the exhaust gas purification devices to continue functioning correctly. , In Claim 2, as the two exhaust gas purification devices are constructed so as to be mounted in series from the end part of the exhaust pipe part of the exhaust pipe to the expansion chamber, neither of the exhaust gas purification devices produces a disturbance in the exhaust gas in a location near to the exhaust outlet. Therefore, there is no concern of an effect on the output characteristics of the engine. Further, as an oxidizing reaction is caused in the first stage of the exhaust gas purification device, followed consecutively by a oxidizing i reaction in the second stage of the exhaust gas purification device, even if the catalyst is located where the temperature of the exhaust gas decreases, the second stage exhaust gas purification device can increase the temperature of the catalyst to enable an efficient reaction, thereby efficiently oxidizing the unburned elements in the exhaust gas, rendering them harmless. In addition, conversely, there is the possibility that the large diameter exhaust gas purification device may become ovoid in shape due to heat distortion and come into contact with the small diameter exhaust gas purification device inside. A reinforcing ring has therefore been fitted to the overlapping part of the large diameter exhaust gas purification device, restricting any shape distortion, thereby enabling the exhaust gas purification devices to continue functioning correctly. [Description of the Numerals] 60 exhaust gas purification device, 61 catalyst containing first pipe member (small diameter exhaust gas purification device), 71 catalyst containing second pipe member (large diameter exhaust gas purification device), 80,100. punched metal, 85a, lOlb no hole parts, 87,103 low density hole parts, 90 punched holes, 93 reinforcing rings, 94 overlap parts. WE CLAIM:- 1. An exhaust gas purification device characterized in that a small and a large diameter exhaust gas purifiers (61, 71) of tubular shaped punching metal each of which has a catalyst loaded therein extend in series from an end part of an exhaust pipe (51) to an expansion chamber (52), the large diameter exhaust gas purifier (71) overlaps with the small diameter exhaust gas purifier (61), and a reinforcing ring (93) is attached to the overlap part (94) of the large diameter exhaust gas purifier (71). 2. An exhaust gas purification device as claimed in claim 1, wherein the overlap part (94) has less density of punched holes than the remaining part. 3. An exhaust gas purification device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Documents:

1673-del-1997-abstract.pdf

1673-del-1997-claims.pdf

1673-del-1997-correspondence-others.pdf

1673-del-1997-correspondence-po.pdf

1673-del-1997-description (complete).pdf

1673-del-1997-drawings.pdf

1673-del-1997-form-1.pdf

1673-del-1997-form-13.pdf

1673-del-1997-form-19.pdf

1673-del-1997-form-2.pdf

1673-del-1997-form-3.pdf

1673-del-1997-form-4.pdf

1673-del-1997-form-6.pdf

1673-del-1997-gpa.pdf

1673-del-1997-petition-137.pdf

1673-del-1997-petition-138.pdf