Title of Invention

AN EXHAUST MUFFLER

Abstract

ABSTRACT AN EXHAUST MUFFLER An exhaust muffler for an internal combustion engine having and an elongated core within the casing. The casing including a tapered outlet end terminating in an outlet pipe and an inlet pipe at an inlet end and the elongated core being hollow and possibly filled with an energy absorbent material. The surface of the core may be perforated. The casing and the elongated core define between them an annular exhaust flow region. There are a plurality of vanes extending between the core and the casing in the annular exhaust flow region, the vanes being so shaped that they are adapted to cause a swirling of the flow of exhaust in the annular exhaust flow region in use. Figure 1

Full Text

TITLE AN EXHAUST MUFFLER FIELD OF THE INVENTION This invention relates to an exhaust system for an internal combustion engine and in particularly to a muffler arrangement. The Invention will be generally discussed in relation to its application to a motor vehicle internal combustion engine exhaust system but it will be realised that it is equally applicable to other forms of engines such as stationary engines. The invention may be applied to motor cycles, motor cars or trucks. BACKGROUND OF THE INVENTION An exhaust muffler for a motor vehicle has the main function of reducing the sound of an engine while at the same time not causing too much back pressure to the flow of exhaust from the engine. It is the object of this invention to provide an exhaust muffler which has good sound absorbent qualities while at the same time providing minimal back pressure thereby enhancing the efficiency of a motor vehicle upon which it is used or to at least to provide the public with a useful alternative; BRIEF SUMMARY OF THE INVENTION In one form therefore although this may not necessarily be the only or broadest form the invention is said to reside in an exhaust muffler for an internal combustion engine, the exhaust muffler comprising a casing, the casing including a tapered outlet end terminating in an outlet pipe and an inlet pipe at an inlet end, an elongated core within the casing, the elongated core being hollow and the surface of the core being perforated, the casing and the elongated core defining between them an annular exhaust flow region, and a plurality of vanes extending between the core and the casing in the annular exhaust flow region, the vanes being so shaped that they are adapted to cause a swirling of the flow of exhaust in the annular exhaust flow region in use. it will be seen that by this invention therefore there is provided an exhaust muffler which has an essentially straight through flow path only interrupted by vanes which cause a swirling or helical flow of exhaust through the exhaust muffler thereby providing minimal back pressure. In fact the helical flow of the exhaust appears to actually encourage flow and draw exhaust through the exhaust muffler and in fact considerable reduction in back pressure is found in practice. Preferably the casing is cylindrical with frusto-conical tapered outlet ends and inlet ends. This helps to provide for a smooth flow of exhaust into and out of the muffler. The inlet end may be domed rather than frusto-conical in shape or may even have a stepped inlet end between the inlet pipe and the casing because flow in this region is not so critical. The elongated core may be perforated so as to have up to fifty percent surface area of apertures. In one preferred embodiment the apertures may be each holes of approximately three millimetres diameter. The elongated core may have domed ends to assist with flow into and out of the annular exhaust flow region. Alternatively one or both of the ends of the elongated core may be tapered to a conical shape. In one preferred embodiment the inlet end may be domed and the outlet end tapered. The elongated core may be filled with an absorbent material so that some degree of sound absorption can occur in the elongated core. In one preferred embodiment the energy absorbent material is long strand glass fibre although other materials which would of course clearly have to be heat resistant could be used. The vanes may be helical or spiral and there may be two, three or four vanes around the periphery of the elongated core. In one preferred embodiment of the invention there may be a first set of four vanes at the inlet end of the elongated core being helical in configuration and extending approximately one third of the length of the elongated core and then a second set of four vanes terminating at the outlet end of the elongated core again approximately one third of the length of the elongated core. This has been found to be a sufficient amount of vanes. The vanes may be plates or tubes. In a preferred embodiment the casing may comprise an inner wall spaced apart from an outer wall defining a space therebetween and with the inner wall being perforated . The space between the inner wall and the outer wall may be filled with fibre glass mat. A typical exhaust muffler according to this invention may have a casing with an outside diameter of one hundred and twenty five millimetres and three hundred and thirty millimetres long and an elongated core one hundred millimetres in outside diameter and three hundred and thirty millimetres long. Each of the vanes may be made from twelve millimetre diameter tube one hundred and ten millimetres long which are curved and then welded to the surface of the elongated core. The ends of the casing may be frusto-conical approximately one hundred and twenty millimetres long terminating in inlet or outlet pipes fifty millimetres of seventy five millimetres in diameter. Using an exhaust muffler of construction of the present invention it has been found that there has been increased torque available from an engine and increased horse power which has provided an improved fuel consumption for the vehicle. Although no quantitative sound tests have been done it does appear that the amount of sound absorption is at least as good as existing types of exhaust mufflers. This then generally describes the invention but to assist with understanding reference will now be made to the accompanying drawings which show preferred embodiments of the invention. DETAILED DESCRIPTION In the drawings FIG 1 shows a cross sectional view of a first embodiment of an exhaust muffler of the invention; FIG 2 shows a cross sectional view of an alternative embodiment of the invention; FIG 3 shows a cross sectional view of a still further embodiment of the invention; FIG 4 shows a cross sectional view of the embodiment of the exhaust muffler shown in FIG 1; and FIG 5 shows a cross sectional view of a part of the outer casing of an alternative embodiment of the exhaust muffler according to this invention. Now looking more closely at the drawings it will seem that the exhaust muffler shown in the embodiment shown in FIG 1 comprises a casing 1 having a frusto-conical shaped inlet end 2 and frusto-conical shaped outlet end 3. An inlet pipe 4 enters the exhaust muffler an outlet pipe 5 exits the muffler. Within the casing is an elongated core 6 which has dome shaped inlet end 7 and a dome shaped outlet end 8. Pieces of piping are bent with a substantially helical form to provide vanes 9 at the inlet end of the elongated core and vanes 10 at the outlet end of the elongated core. ta the embodiment shown in FIG 2 the construction is essentially similar although there is a domed inlet end 20 to the casing 22 and a conical outlet end 21 to the elongated core 23. In the embodiment shown in FIG 3 the vanes 25 of a substantially helical configuration are comprised of plates extending between the elongated core 26 and the casing 27. In FIG 4 which is a cross section on the line 4-4' in FIG 1 it will be seen that the elongated casing 6 is filled with long strand glass fibres 27. In FIG 5 it will be seen that in one embodiment the outer casing is comprised of an outer layer 30 and an inner layer 31 with the inner layer being perforated and having perforations 32 to assist in the absorption of sound emanating from the muffler. In the space between the inner and outer wall may be a packing 33 comprised of a suitable material such as fibre glass mat. Preferably the perforations may provide up to 40% open spaces in the inner wall. The construction of the muffler and in particular defining the space between the inner and the outer wall may be achieved by fitting by welding the inner wall on the inside of the extremity of the end cone 34 and fitting by welding the outer wall to the outside of the extremity of the end cone 34. The exhaust muffler of this present invention may be constructed from steel or stainless steel or any other suitable material and may be of welded or other suitable construction. The inlet and outlet pipes may be constructed for flange slip or welded joining to exhaust pipes of an internal combustion engine. Throughout this specification various indications have been given as to the scope of this invention but the invention is not limited to any one of these but may reside in two or more of these combined together. The examples are given for illustration only and not for limitation. Throughout this specification unless the context requires otherwise, the words 'comprise' and 'include' and variations such as 'comprising' and 'including' will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. CLAIMS 1. An exhaust muffler for an internal combustion engine, the exhaust muffler comprising a casing, the casing including a tapered outlet end terminating in an outlet pipe and an inlet pipe at an inlet end, an elongated core within the casing, the elongated core being hollow and the surface of the core being perforated, the casing and the elongated core defining between them an annular exhaust flow region, and a plurality of vanes extending between the core and the casing in the annular exhaust flow region, the vanes being so shaped that they are adapted to cause a swirling of the flow of exhaust in the annular exhaust flow region in use. 2. An exhaust muffler as in Claim 1 wherein the casing is cylindrical with frusto-conical tapered outlet ends and inlet ends. 3. An exhaust muffler as in Claim 1 wherein the inlet end is domed 4. An exhaust muffler as in Claim 1 wherein the inlet end has a stepped inlet end between the inlet pipe and the casing. 5. An exhaust muffler as in any one previous claim wherein the elongated core is perforated so as to have up to fifty percent surface area of apertures. (L An exhaust muffler as in Claim 5 wherein the apertures are each holes of approximately three millimetres diameter, 7. An exhaust muffler as in Claim 1 wherein the elongated core has domed ends to assist with flow into and out of the annular exhaust flow region. 8. An exhaust muffler as in any one previous claim wherein one or both of the ends of the elongated core is tapered to a conical shape. • 9. An exhaust muffler as in any one previous claim wherein the elongated core has its inlet end domed and its outlet end tapered. 10. An exhaust muffler as in any one previous claim wherein the elongated core is filled with an energy absorbent material. 11. An exhaust muffler as in Claim 1 wherein the energy absorbent material is long strand glass fibre. 12. An exhaust muffler as in any one previous claim wherein the vanes are helically or spirally arranged and there are two, three or four vanes around the periphery of the elongated core. 13. An exhaust muffler as in any one previous claim having a first set of four vanes at the inlet end of the elongated core being helical in configuration and extending approximately one third of the length of the elongated core and a second set of four vanes terminating at the outlet end of the elongated core approximately one third of the length of the elongated core. 14. An exhaust muffler as in any one previous claim wherein the vanes are plates or tubes. 15. An exhaust muffler as in any one previous claim wherein the casing comprises an inner wall spaced apart from an outer wall defining a space therebetween with the inner wall being perforated . 16. An exhaust muffler as in Claim 15 wherein the space between the inner wall and the outer wall is filled with fibre glass mat. 17. An exhaust muffler according to any one previous claim wherein the casing has an outside diameter of one hundred and twenty five millimetres and a length of three hundred and thirty millimetres and an elongated core one hundred millimetres in outside diameter and three hundred and thirty millimetres long, wherein each of the vanes is made from twelve millimetre diameter tube one hundred and ten millimetres long and which are curved and then welded to the surface of the elongated core, the ends of the casing being frusto-conical and being approximately one hundred and twenty millimetres long terminating in inlet or outlet pipes of fifty millimetres or seventy five millimetres in diameter. 18. An exhaust muffler substantially as hereinbefore described with reference to and as illustrated in the drawings.

Documents:

701-mas-1997-abstract.pdf

701-mas-1997-claims duplicate.pdf

701-mas-1997-claims original.pdf

701-mas-1997-correspondence others.pdf

701-mas-1997-correspondence po.pdf

701-mas-1997-description complete duplicate.pdf

701-mas-1997-description complete original.pdf

701-mas-1997-drawings.pdf

701-mas-1997-form 1.pdf

701-mas-1997-form 26.pdf

701-mas-1997-form 3.pdf

701-mas-1997-other documents.pdf

abs-701-mas-1997.jpg