AU2008323603A1 - Muffler - Google Patents

Description

WO 2009/062233 PCT/AU2008/001670 1 MUFFLER FIELD OF THE INVENTION This invention relates to a thermal emission-conversion muffler, particularly to such a device which reduces emitted toxic pollutants passing through the 5 device. BACKGROUND TO THE INVENTION Noise and pollutants emitted from vehicles using internal combustion engines and devices such as exhaust stacks are an increasing issue. Engines, and other devices such as stacks, utilise mufflers and catalytic converters to 10 reduce the sound and toxic emissions. A muffler consists of an inlet pipe and an outlet pipe with a chamber between the inlet and outlet pipes. This chamber is the part of the muffler that reduces the noise of the exhaust gases by being a resonating chamber, which is tuned to cause destructive interference of the sound waves generated by the gas 15 travelling through the exhaust system. This reduces the amount of noise emitted because of the exhaust gases. Mufflers can also result in increased engine efficiency, performance, power output and assist in reducing the wear and tear on the engine components by providing reduced backpressure. 20 A muffler is typically designed to reduce exhaust noise of vehicles. They are normally installed as part of the exhaust system along the exhaust pipe. The exhaust system usually consists of tubing which conveys the waste exhaust gases away from the engine where they are created. There has also been focus on the polluting effect of vehicular exhaust. 25 Although the largest part of most combustion gases is relatively harmless nitrogen, water vapour and carbon dioxide, there are still undesirable noxious or toxic substances emitted such as carbon monoxide, hydrocarbons, nitrogen oxides, unburnt fuel and particulate matter. As such, catalytic converters can be used in engines or stacks and the like 30 to reduce the toxicity of emissions. They are used most commonly in motor vehicle exhaust systems, but also in other devices with engines such as generator sets, forklifts, mining equipment, trucks, buses and trains. A catalytic WO 2009/062233 PCT/AU2008/001670 2 converter provides an environment for a chemical reaction wherein toxic combustion by-products are converted to less toxic substances. Catalytic converters do have a number of drawbacks. They require a temperature above 4000C to work effectively and therefore substantially increase 5 toxic pollutants for about 15 minutes from a cold start. They are also damaged by misfire, rich fuel mixture, contaminated fuel, oil contamination, carbon contamination from short trip driving and various other factors that cause them to work ineffectively. It is an object of the present invention to provide an alternative or 10 complementary device that reduces the environmental impact through reduced toxic emissions of internal combustion engines and other devices such as exhaust stacks. SUMMARY OF THE INVENTION According to one aspect, the present invention provides a thermal 15 emission-conversion muffler for reducing the toxic emissions output from the muffler, the muffler having an inlet pipe, an outlet pipe, and a body extending lengthwise between the inlet and outlet pipes, the muffler further having a plurality of plates disposed within the body, the plates extending in a sideways direction substantially between the side walls of the body and being of a predetermined 20 length, and adjacent plates being at a predetermined distance from each other. Preferably, the plates are arranged in a substantially stacked manner and are parallel as regards exhaust gas flow passing through the muffler. The plate geometry may be selected from the following list: substantially flat, substantially corrugated, substantially curvilinear, substantially U-shaped, substantially 25 flattened tubes. Preferably, the predetermined length of the plates is between 35 and 45 millimetres and the predetermined distance is between 2.0 and 4.0 millimetres. Even more preferably, the predetermined distance is between 2.5 and 3.5 millimetres. 30 Alternatively, the predetermined length of the plates may be between 35 and 45 millimetres and the predetermined distance is between 5.0 and 7.0 millimetres. More preferably, the predetermined distance is between 5.5 and 6.5 millimetres.

WO 2009/062233 PCT/AU2008/001670 3 The thickness of the plates may be between 1 and 2 millimetres. The muffler may be used in conjunction with a catalytic converter. According to a second aspect, the present invention provides a thermal emission-conversion muffler for reducing the toxic emissions output from the 5 muffler, the muffler having an inlet pipe, an outlet pipe, and a body extending lengthwise between the inlet and outlet pipes, the muffler further having a plurality of plates disposed within the body, the plates extending in a sideways direction substantially between the side walls of the body and being of a predetermined surface area and adjacent plates being at a predetermined distance from each 10 other. According to a third aspect, the present invention provides a thermal emission-conversion muffler for reducing the toxic emissions output from the muffler, the muffler having an inlet pipe, an outlet pipe, and a body extending lengthwise between the inlet and outlet pipes, the muffler further having a series 15 of sets of a plurality of plates disposed within the body, the plurality of plates being arranged in a stacked manner, the plates extending in a sideways direction substantially between the side walls of the body and being of a predetermined surface area and adjacent plates being at a predetermined distance from each other, the sets of plates being separated by a predetermined separation distance. 20 According to a fourth aspect, the present invention provides a thermal emission-conversion muffler for reducing the toxic emissions output from the muffler, the muffler having an inlet pipe, an outlet pipe, and a body extending lengthwise between the inlet and outlet pipes, the muffler further having a series of sets of a plurality of plates disposed within the body, the plurality of plates 25 being arranged in a stacked manner, the plates extending in a sideways direction substantially between the side walls of the body and being of a predetermined length and adjacent plates being at a predetermined distance from each other, the sets of plates being separated by a predetermined separation distance. Each set of stacked plates may have the same predetermined length, 30 distance between the plates, and separation distance between the sets of plates. BRIEF DESCRIPTION OF THE DRAWINGS An illustrative embodiment of the present invention will be described by way of example only with reference to the accompanying figures, in which: WO 2009/062233 PCT/AU2008/001670 4 Figure 1 is a schematic of a top plan view of a thermal emission conversion muffler with a rectangular body enclosed within a muffler housing according to an embodiment of this invention; Figure 2 is a schematic of the end plan view of a thermal emission 5 conversion muffler with a rectangular body enclosed within a muffler housing according to an embodiment of this invention; Figure 3 is a schematic of one example of the plate configuration within the body of the muffler; Figures 4-8 are schematics of alternative plate configurations for the body 10 of the muffler of Figures 1 and 2; Figure 9 is a cross-sectional view of the plate configuration along the axial length of the muffler body shown in Figure 8; Figure 10 is a schematic of three alternative plate configurations for placement within the body of the muffler of Figures 1 and 2; 15 Figure 11 is a schematic of a top plan view of a thermal emission conversion muffler with a cylindrical body enclosed within a muffler housing according to an embodiment of this invention; Figure 12 is a schematic of the end plan view of a thermal emission conversion muffler with a cylindrical body enclosed within a muffler housing 20 according to an embodiment of this invention; Figures 13a and b shows schematics of two alternative plate configurations for the body of the muffler of Figures 11 and 12; Figure 14 is a schematic cross-sectional view of the plate configuration having separated regions along the axial length of a rectangular or circular body 25 for the body of the muffler of Figures 1, 2, 11 and 12. DESCRIPTION OF PREFERRED EMBODIMENT The present invention may be implemented in a variety of ways and the embodiments illustrated are to be considered only as illustrative constructions. Figures 1 and 2 show schematically the top and end plan views of a 30 thermal emission-conversion muffler 10 enclosed within a muffler body 30. The muffler 10 has an inlet pipe 20, an outlet pipe 25 and a body 30 placed between these two pipes 20,25. The body 30 is connected to the pipes 20,25 by tapered pipe sections 20a,25a extending between the body 30 and each of the inlet pipe WO 2009/062233 PCT/AU2008/001670 5 20 and outlet pipes 25. These tapered pipe sections 20a,25a may transition into the body 30 with a predetermined radii of curvature. This measure will contribute to a more even gas flow through the muffler 10. The body 30 is surrounded by a heat shield 15 with an air gap between the body and heat shield as is known in 5 the art. As shown in Figure 3 in a schematic of the inside of the body from a end view, the body 30 can be made in two parts and seam welded together 35. The body 30 and heat shield 15 of the rectangular mufflers 10 are constructed from two symmetrical halves. Internal to the body is a plurality of plates 45 held firmly 10 within a holding device 40. The plates 45 extend substantially the full sideways width of the body 30. The plates shown in Figure 3 are flattened tubes of a predetermined length and have a predetermined separation d between adjacent plates. The plates shown in Figure 3 are rectangular with bull-nosed sides. The holding device 40 is 15 configured to hold such a shape firmly in place to avoid any movement of the plates 45. Figures 4-8 are end view schematics of alternative plate 40 configurations for the body 30 of the muffler 10: Figure 4 shows the plates 45 as a serpentine shape made from 20 one piece of metal and held in place by a holding device 40 similar to the holding device in Figure 3. The plates 45 of Figure 5 are elongated U-shapes which self-lock within the holding device 40. The bent ends of the U-shaped plates 45 can be shortened or lengthened to achieve the required 25 predetermined distance d between the plates 45. Flat plates 45 in Figures 6 and 7 are held in place by crimping edges of the holding device 40. - Figure 8 shows the pre-formed holding device 40, that locks the stacked plates 45 together as one unit, before it is compressed to 30 the reduced length shown in Figures 6 and 7. The pre-formed holding device 40 may have numerous small raised humps 40a along the length of the surface and between the holding device WO 2009/062233 PCT/AU2008/001670 6 and plates to hold the plates 45 more firmly and prevent the plates from separating from the holding device 40. The rectangular and round mufflers may be constructed with one or more long narrow slots 51 in opposing sides of the muffler body 30 to allow the plates 45 to 5 be welded to the body 30. Also, the ends of the plates 45 of all the plate configurations used in the rectangular and round mufflers are radiused 52. Figure 9 is a cross-sectional view along its axial length of the plate configuration shown in Figure 8, before the pre-formed holding device 40 is compressed to the reduced length shown in Figures 6 and 7. As stated above, 10 the plates are separated by a predetermined distance d. Figure 10 is a schematic of three alternative configurations of plates 45 for placement within the body 30 of the muffler 10. The shapes shown at Figures 10a and b are corrugated versions of the plates 45 shown in Figures 3 and 4 respectively. The shapes shown in Figures 10a,b,c can be placed in a body 30 15 with flat surfaces and no corrugations. The rectangular muffler bodies 30 can be constructed using flat plates with corrugated holding devices 40 on each side of the flat plates. The ends of the flat plates are inserted into the valleys of the corrugated holding devices 40 which are compressed to lock the plates 45 into position. The flat plates 45 can be inserted 20 into each valley or every second valley depending on the predetermined distance d required between the plates 45. Corrugated holding devices 40 of about 1.5mm thickness can support the plates 45 being positioned at a distance of 3mm to 6mm apart. Alternatively, 3mm thick corrugated holding devices 45 can be used to position the plates the desired thickness apart (eg 6mm). The body 30 of the 25 rectangular muffler 10 with the corrugated holding device 40 has a rectangular section on opposing sides to lock the plates 45 and corrugated holding device 40 into position. The mufflers 10 can also include a heat shield 15 that follows the shape of the rectangular or round muffler, as shown in Figures 11 and 12. The heat shield 30 15 is open at each end to allow a flow of air between the muffler body 30 and the heat shield 15. The heat shield as shown on the round muffler in Figures 11 and 12 has a plurality of retaining portions 53 at the ends of the heat shield which are V-shape bends that bend inwards towards the tapered pipe sections 20a,25a of WO 2009/062233 PCT/AU2008/001670 7 the muffler body 30. The retaining portions 53 can be welded at the tip 54 of the retaining portions to the tapered pipe sections 20a,25a of the muffler. Apart from the shape of the body 30, the muffler 10 is the same as that shown in Figure 1. Figures 13a and b shows two alternative plate configurations for the body 5 30 of the cylindrical muffler 10 which are equivalent to those for the rectangular muffler 10 shown in Figures 5 and 4 respectively. The rectangular and round mufflers 10 can be constructed using either flat tubes, one piece of corrugated plate with a flat surface or U-shaped plates. The rectangular muffler 10 can also be constructed using flat plates. 10 Figure 14 is a schematic of another embodiment of the invention. This figure shows a series of sets of stacked plates 45 as shown in the earlier figures, but in a separated configuration. The separation xn between subsequent sets of plates allows each set of stacked plates 45 to maintain the maximum increase in temperature along its axial length and prevents the outlet temperature of each set 15 of stacked plates 45 from cooling. This allows the temperature of the exhaust gas at the outlet of the stacked plates to be controlled by maintaining or increasing the optimum length of the plates. Various configurations for separating the sets of stacked plates 45 may be employed. Two examples shown in Figure 14 are: 20 - The rectangular and round mufflers with a series of sets of stacked plates 45 have tapered sections 55 separating each set of stacked plates 45. the round mufflers with a series of stacked plates 45 can have a 1/8" (3mm) smaller diameter tube 56 with a specific length fitted 25 inside the muffler body to separate each set of stacked plates 45. In use, the exhaust gases flow through the muffler 10 and heat up the plates 45, which in tum increases the temperature of the gas flow. The applicant has found that through utilising the arrangement of stacked plates, the core temperature of the muffler body 30 can be, depending on the configuration 30 utilised, increased between four to ten times greater than the exhaust gas temperature in a pipe of the same size. The increased temperature results in the break down and reduction of the toxic pollutants: HC, CO, NOx.

WO 2009/062233 PCT/AU2008/001670 8 As this device is a 'straight through' flow for the exhaust gas, the gases are not restricted (as they are for example by the restrictive passages in a baffled muffler or by the small restrictive passages in a catalytic converter) and therefore there is no power loss due to the slowing of the exhaust gases in some 5 conventional muffler/catalytic converter systems. Also, the hotter core temperature of the muffler 10 increases the gas speed by virtue of the hotter gas temperature. This results in more power being available to the vehicle engine but also greater fuel economy. One configuration of muffler 10 has plates 45 separated by a distance d of 10 2.5-3.5 mm and a length of between 35-45mm. The muffler 10 with this configuration will be referred to as an "EV16". It was found that the temperature of the EV16 muffler core was 8 times higher than the temperature of a typical exhaust pipe of the same diameter. Eg, the temperature of a typical exhaust pipe is about 100C while the temperature of the EV1 6 muffler core was about 800*C. 15 The EV16 muffler was similar to the configuration shown in Figure 14: it was a series of 4 sets of stacked plates. The distance d between the plates 45 was 3mm and the length of the plates was 40mm. The separations x 1 ,x 2 etc between each set of stacked plates 45 was 10-50mm. The gas emission was analysed by a Bosch gas analyser. The engine the muffler 10 was fitted to was a 20 2.4 litre Diesel 4 cylinder in a 1991 Toyota Hilux Utility with a peak RPM of 4700. Note: CO, HC, NOx are toxic emissions while 02 and C02 are harmless emissions. The tests on the EV16 produced the following results (similar results were obtained for a petrol vehicle): Gas RPM 1400 results RPM: 2700 results CO 0.012% 0.071% HC 1 ppm -1 ppm NOx 120 ppm 267 ppm 02 15.84% 2.70% C02 3.60% 13.35% Table 1: Before: Results with standard exhaust system. 25 Gas RPM 1400 results RPM: 2700 results WO 2009/062233 PCT/AU2008/001670 9 CO 0.006% 0.016% HC -1 ppm -O ppm NOx 115ppm 106ppm 02 16.17% 15.43% C02 3.32% 3.83% Table 2: After: Results with the addition of a series of four 2 2 x 3 inch long EV16 mufflers of above description and fitted to standard exhaust system with no other modifications. Results show 78% lower CO emission, 60% lower NOx emissions and no 5 change to HC emissions. The particulate (smoke) emissions reduced to the point that they were not visible. Therefore, this muffler 10 reduces the toxic emissions with carbureted, fuel injected or gas vehicles that do not use a catalytic converter as well as substantially reducing the exhaust smoke from diesel emissions. Further toxic emission reduction could have been obtained by increasing from 10 four the number or sets of stacked plates. The EV16 also substantially reduces cold start emissions in vehicles without a catalytic converter or other emission control devices. Another muffler configuration has plates separated by a distance d of between 5.5 and 6.5 mm. The muffler with these plate distances will be referred 15 to as an "EV8". It was found that the temperature of the EV8 muffler core was 6 times higher than the temperature of a typical exhaust pipe of the same diameter. Eg, the temperature of a typical exhaust pipe is about 1000C while the temperature of the EV8 muffler core was about 600*C. It was found that a distance d of less than 2.5 or greater than 3.5 20 millimetres reduced the temperature of the muffler core. It was also found that a plate length of longer than 40mm reduces the outlet temperature of the muffler core, and the reduction in temperature continues the longer the plate is over 40mm. This allows the muffler core to be tuned to a specific outlet temperature. The EV8 muffler 10 was 2 % x 6 inches long with plates separated by a 25 distance d of 6mm and was fitted in front of a catalytic converter with no other modifications. The vehicle used was a 2004 Toyota Corolla Sportivo with a 1.8 litre 4 cylinder VTEC engine, with peak RPM of 8000, which uses a catalytic WO 2009/062233 PCT/AU2008/001670 10 converter and runs on premium unleaded fuel. The results are shown in Tables 3 and 4. Gas RPM 800 results RPM: 2500 results CO 0.10-0.27% 0.29 - 0.43 % HC 338-395ppm 51-78ppm 02 0.61 % 0.46 % C02 14.73% 14.73% Lambda 1.01 1.01 AFR 14.7 14.6 Table 3: Before: Results with standard exhaust system and standard OEM catalytic converter. Gas RPM 800 results RPM: 2500 results CO 0.00 - 0.02 % 0.00 - 0.01 % HC 25-42ppm* 3-5ppm* 02 0.68 % 0.31 % C02 15.02 % 15.51 % Lambda 1.03 1.01 AFR 14.9 14.7 5 Level of HC emissions in the atmosphere was 3-4ppm Table 4: After: Results with the addition of a 2 1/2 x 6 inch long EV8 muffler in conjunction with an aftermarket or standard OEM catalytic converter and fitted to standard exhaust system with no other modifications. Results show 98% lower CO emissions, 94% lower HC emissions and 85% lower NOx emissions. The NOx 10- emissions were calculated from the diesel results in Table 2. After this test, the EV8 muffler and catalytic converter were also tested on the 2.4 litre diesel vehicle, with the following results. Gas RPM 1400 results RPM: 2700 results CO 0.011% 0.019% HC Oppm 1ppm NOx 141 ppm 128 ppm 02 16.20% 15.65% C02 3.47% 3.86% WO 2009/062233 PCT/AU2008/001670 11 Table 5: After: Results with the addition of a 2 % x 6 inch long EV8 muffler in conjunction with an aftermarket catalytic converter and fitted to standard exhaust system with no other modifications. These results show that with diesel vehicles the EV16 muffler alone 5 reduces toxic emissions more than the EV8 muffler and catalytic converter combination or catalytic converters used alone. After the tests were completed for the EV8 muffler, the catalytic converters were examined and it was found that substantially no damage had been sustained by the catalytic converter, as is usual with general vehicle use, 10 indicating that the use of the EV8 muffler protects the catalytic converter from, for example, misfire, carbon contamination from excessive short trip driving, rich fuel mixture, high hydrocarbon (HC) emissions, oil contamination, contaminated fuel, high sulphur fuel, leaded fuel, engine coolant, chemical additives, silicone contamination from sealants and thermal shock. Any of these factors damage the 15 catalytic converter and render it useless which increases pollution. Therefore, this device 10 could allow the fitting of a catalytic converter to carburetted vehicles to permit reduced toxic emissions without damaging the catalytic converter. This device also assists in the operation of the catalytic converter which 20 requires a temperature above 400*C to work effectively which usually takes 15 minutes of engine running time to generate this temperature. The operation of the muffler 10 in front of the catalytic converter produces the optimum catalytic converter operating temperatures far quicker; it was found that the operating temperature of the catalytic converter was reached in 2 minutes by the EV8 25 muffler which substantially reduced cold start emissions. The length of the plates 45 is important in this regard to immediately produce the optimum temperature gas input to the catalytic converter and prevent the catalytic converter from exceeding its operating temperature. It was found that the temperature of the plates 45 was about 6000C for the first 40mm of the plates 45, then dropped to 30 about 300-400*C at 125mm. Further, use of the EV8 allows the catalytic converter to be moved 2.5 metres further away from the engine while producing the same results. In summary, the configurations tested were: WO 2009/062233 PCT/AU2008/001670 12 Muffler Applications Length Width Requirements " Fuel injected and gas 6 1/2" 9 1/4" wider than the a I x EV8 muffler is required vehicles fitted with a inlet pipe diameter per side catalytic converter ( For example, 2" EV8 * EV8 muffler must be fitted EV8 * 2", 2 1/2", 3" exhaust muffler has 2 114" in FRONT of the catalytic systems width, 2 1/2" EV8 converter muffler has 2 3/4" width, etc " Carbureted, fuel injected, 3 1/2" 9 1/2" wider than the 4 x EV16 mufflers are gas and diesel vehicles NOT fitted with a catalytic (90mm) inlet pipe diameter required per side NOT_ fitdwt aayi For example, 2" * Additional EVi 6 mufflers converter EV16 muffler has 2 may be used to further " Diesel vehicles fitted with a 1/2" width, 2 1/2" reduce toxic emissions, catalytic converter and EV16 muffler has 3" increase power or reduce EV16 particulate (smoke) filter width, etc noise .2", 2 1/2", 3", 4", 5", 6" exhaust systems Same as EV16 9 1/4" Same as EVI 6 .1 x EV1 64 muffler is (235mm) required per side 1Additional EV64 mufflers NOTE may be used to further redcedoxiemsstns " EVi 64 muffler uses 4 x EVi 6 mufflers built into 1 muffler increase ox ers reduce 4 Using either I long EV 64 muffler or 4 short EV 6 mufflers per side nisred per id EV6 Aditile V1 u r produces the same results. However, the short EV16 muffler allows more mufflers to be fitted to any part of the exhaust system to further reduce toxic emissions, increase power or reduce noise It was also found that the positioning of the muffler 10 in the exhaust system may have relevant effects. For example, the muffler may be positioned into each primary pipe of the exhaust manifold/header which, by bringing the 5 muffler closer to the exhaust port, allows the muffler to warm up more quickly and operate at a higher temperature, whereby it can work more efficiently in reducing emission of pollutants (both cold start emissions and operating emissions) and noise. The higher temperature of operation of the muffler when so positioned also increases the gas velocity through the muffler which has the upstream effect of 10 increasing the level of gas scavenging and purging in the cylinder, thereby improving engine performance. Nonetheless, the small size of the muffler 10 means that it can be fitted to any part of the exhaust system. However, in a vehicle fittedf with a catalytic converter, in order to achieve the benefits to the catalytic converter, the muffler 10 must be fitted before the catalytic converter.

WO 2009/062233 PCT/AU2008/001670 13 While it will be understood that the focus of the description above has been related to the reduction in toxic emissions, the device 10 also is beneficial in reducing the noise emitted from the outlet pipe 25. This is a result of the sound waves entering through the inlet pipe 20 reducing in amplitude due to reflecting 5 off the plates 45 inside the muffler body 30. It was found in the tests that the EV mufflers reduced the exhaust noise by 5db (36%) and increased the power by 3%. It was found that this power increase and noise reduction whether the exhaust system is a standard, restrictive or performance type. The muffler 10 may replace existing mufflers or used in conjunction with 10 them to provide the extra noise reduction. The results indicated above also work for modern vehicles using restrictive exhaust systems. Additional mufflers 10 may be fitted along the exhaust system (eg at the middle or end) to increase the gas speed at these points to provide an increase in power. It is to be noted that this muffler 10 does not have perforated tubing; 15 moving parts; spiral, turbine or venturi shapes; sound absorption material; speakers, electronics or computers; electrical heating devices; require expensive metals; and does not work like conventional mufflers or catalytic converters. It will be realised by persons skilled in the art that numerous variations and/or modifications may be made to this exhaust muffler device as shown in the 20 specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. For example, as shown, while the examples provided have described the device in use with an internal combustion engine, the device is equally suited to 25 exhaust stacks and the like. Further, the body of the muffler can be rectangular or cylindrical in cross-section. The plates may not necessarily be flat but could be corrugated, elliptical in cross section or any other suitable configuration. 30

Claims (15)

1. A thermal emission-conversion muffler for reducing the toxic emissions 5 output from the muffler, the muffler having an inlet pipe, an outlet pipe, and a body extending lengthwise between the inlet and outlet pipes, the muffler further having a plurality of plates disposed within body, the plates extending in a sideways direction substantially between the side walls of the body and being of a predetermined length, and adjacent plates being at a 10 predetermined distance from each other.

2. The muffler according to claim 1, wherein the plates are arranged in a substantially stacked manner and being parallel as regards exhaust gas flow passing through the muffler.

3. The muffler according to either claim 1 or claim 2, wherein the plate 15 geometry is selected from the following list: substantially flat, substantially corrugated, substantially curvilinear, substantially U-shaped, substantially flattened tubes.

4. The muffler according to any one of the preceding claims, wherein the predetermined length of the plates is between 35 and 45 millimetres. 20

5. The muffler according to any one of the preceding claims, wherein the predetermined distance is between 2.0 and 4.0 millimetres.

6. The muffler of claim 5, wherein the predetermined distance is between 2.5 and 3.5 millimetres.

7. The muffler according to any one of claims 1-3, wherein the predetermined 25 length of the plates is between 35 and 45 millimetres. WO 2009/062233 PCT/AU2008/001670 15

8. The muffler according to any one of claims 1-3, wherein the predetermined distance is between 5.0 and 7.0 millimetres.

9. The muffler of claim 8, wherein the predetermined distance is between 5.5 5 and 6.5 millimetres.

10. The muffler according to any one of the preceding claims, wherein the thickness of the plates is between 1 and 2 millimetres.

11. The muffler according to any one of the previous claims used in conjunction with a catalytic converter. 10

12. A thermal emission-conversion muffler for reducing the toxic emissions output from the muffler, the muffler having an inlet pipe, an outlet pipe, and a body extending lengthwise between the inlet and outlet pipes, the muffler further having a plurality of plates disposed within body, the plates extending in a sideways direction substantially between the side walls of 15 the body and being of a predetermined surface area and adjacent plates being at a predetermined distance from each other.

13. A thermal emission-conversion muffler for reducing the toxic emissions output from the muffler, the muffler having an inlet pipe, an outlet pipe, and a body extending lengthwise between the inlet and outlet pipes, 20 the muffler further having a series of sets of a plurality of plates disposed within body, the plurality of plates being arranged in a stacked manner, the plates extending in a sideways direction substantially between the side walls of the body and being of a predetermined surface area and adjacent plates being at a predetermined distance from each other, the sets of plates being separated by a 25 predetermined separation distance. WO 2009/062233 PCT/AU2008/001670 16

14. A thermal emission-conversion muffler for reducing the toxic emissions output from the muffler, the muffler having an inlet pipe, an outlet pipe, and a body extending lengthwise between the inlet and outlet pipes, 5 the muffler further having a series of sets of a plurality of plates disposed within body, the plurality of plates being arranged in a stacked manner, the plates extending in a sideways direction substantially between the side walls of the body and being of a predetermined length and adjacent plates being at a predetermined distance from each other, the sets of plates being separated by a 10 predetermined separation distance.

15. The muffler according to either of claim 13 or 14 wherein the each set of stacked plates have the same predetermined length, distance between the plates, and separation distance between the sets of plates.