This invention relates to a thermal emission-conversion muffler, particularly to such a device which reduces emitted toxic pollutants passing through the device.
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 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 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.
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. 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 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 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 400° C. to work effectively and therefore substantially increase 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 complementary device that reduces the environmental impact through reduced toxic emissions of internal combustion engines and other devices such as exhaust stacks.
According to one 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 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 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 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.
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.
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 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 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 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.
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 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, distance between the plates, and separation distance between the sets of plates.
An illustrative embodiment of the present invention will be described by way of example only with reference to the accompanying figures, in which:
a and b shows schematics of two alternative plate configurations for the body of the muffler of
The present invention may be implemented in a variety of ways and the embodiments illustrated are to be considered only as illustrative constructions.
As shown in
The plates shown in
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 into each valley or every second valley depending on the predetermined distance d required between the plates 45. Corrugated holding devices 40 of about 1.5 mm thickness can support the plates 45 being positioned at a distance of 3 mm to 6 mm apart. Alternatively, 3 mm thick corrugated holding devices 45 can be used to position the plates the desired thickness apart (eg 6 mm). The body 30 of the 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
a and b shows two alternative plate configurations for the body 30 of the cylindrical muffler 10 which are equivalent to those for the rectangular muffler 10 shown in
Various configurations for separating the sets of stacked plates 45 may be employed. Two examples shown in
In use, the exhaust gases flow through the muffler 10 and heat up the plates 45, which in turn 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 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.
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 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 2.5-3.5 mm and a length of between 35-45 mm. 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 100° C. while the temperature of the EV16 muffler core was about 800° C.
The EV16 muffler was similar to the configuration shown in
Results show 78% lower CO emission, 60% lower NOx emissions and no 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 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 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 100° C. 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 millimetres reduced the temperature of the muffler core. It was also found that a plate length of longer than 40 mm reduces the outlet temperature of the muffler core, and the reduction in temperature continues the longer the plate is over 40 mm. This allows the muffler core to be tuned to a specific outlet temperature.
The EV8 muffler 10 was 2½×6 inches long with plates separated by a distance d of 6 mm 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 converter and runs on premium unleaded fuel. The results are shown in Tables 3 and 4.
After this test, the EV8 muffler and catalytic converter were also tested on the 2.4 litre diesel vehicle, with the following results.
These results show that with diesel vehicles the EV16 muffler alone 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, 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 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 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 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 600° C. for the first 40 mm of the plates 45, then dropped to about 300-400° C. at 125 mm.
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:
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 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 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 fitted with a catalytic converter, in order to achieve the benefits to the catalytic converter, the muffler 10 must be fitted before the catalytic converter.
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 off the plates 45 inside the muffler body 30. It was found in the tests that the EV mufflers reduced the exhaust noise by 5 db (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 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; 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 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 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.
Number | Date | Country | Kind |
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2007906183 | Nov 2007 | AU | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/AU2008/001670 | 11/12/2008 | WO | 00 | 5/11/2010 |