WO2005026508A1

WO2005026508A1 - Exhaust muffler

Info

Publication number: WO2005026508A1
Application number: PCT/AU2004/001231
Authority: WO
Inventors: Martin Lester Cunliffe
Original assignee: Martin Lester Cunliffe
Priority date: 2003-09-12
Filing date: 2004-09-10
Publication date: 2005-03-24

Abstract

An exhaust muffler is provided comprising an exhaust gas inlet (18) and an exhaust gas outlet (22). The muffler defines first and second flow paths from the inlet to the outlet, the first flow path being arranged to provide less resistance to exhaust gas flow than the second flow path. The muffler also provides control means operable by a user for controlling gas flow through the first flow path.

Description

EXHAUST MUFFLER

Technical Field The present invention relates to an exhaust muffler.

Background Art The resistance to exhaust gas flow in a standard muffler is typically not adjustable. A person may wish to adjust the resistance to exhaust gas flow in a muffler in order to adjust the backpressure caused on the engine to which the muffler is attached. By adjusting the backpressure, the power output and/or fuel efficiency of the engine may be altered. Alternatively, a person may wish to adjust the resistance to exhaust gas flow in a muffler in order to alter the characteristics of the exhaust sound for aesthetic reasons. To adjust the resistance to exhaust gas flow to obtain the above benefits, a different exhaust muffler must be used. This makes adjustment time consuming and expensive because of the need to replace the exhaust muffler.

Disclosure of Invention The present invention provides an exhaust muffler comprising : an exhaust gas inlet; an exhaust gas outlet; the muffler defining first and second flow paths from the inlet to the outlet; the first flow path being arranged to provide less resistance to exhaust gas flow than the second flow path; and control means operable by a user for controlling gas flow through the first flow path.

It will be seen that the present invention advantageously provides an exhaust muffler that may be "tuned" by adjustment of the proportion of exhaust gas which flows through the first and second flow paths. Accordingly, a user can adjust the backpressure caused by the muffler on the engine to which it is attached in order to enhance performance and/or fuel efficiency of the engine, or to alter the characteristics of the exhaust sound .

The muffler of the present invention may be used for everyday driving in which exhaust sound is muffled in accordance with legal requirements. However, a user can, by making an adjustment, alter the characteristics of the exhaust sound so it is made desirably more aesthetic.

The muffler of the present invention may also advantageously be provided as a single unit and does not necessarily include further exhaust pipes or components.

In a first embodiment, the first flow path passes through an aperture and the control means operates by selectively obstructing the aperture. Preferably, the aperture is provided in the wall of a pipe, the bore of the pipe being in fluid communication with the exhaust gas outlet, and the control means comprises a sleeve mounted on the pipe, the sleeve being movable to selectively and progressively obstruct the aperture.

In a second embodiment, the first flow path passes through an inlet aperture which is in alignment with a valve aperture and into a valve, the valve being in fluid communication with the exhaust gas outlet and wherein the control means operates by selectively and progressively causing the inlet aperture and the first valve aperture to become out of alignment. Preferably, the exhaust muffler is of a tri-flow muffler configuration.

Brief Description of Drawings Preferred embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a cross-sectional plan view of an exhaust muffler in accordance with a first embodiment of the invention in which the first flow path is represented; Figure 2 shows a cross-sectional plan view of the muffler of Figure 1 in which the second flow path is represented; Figure 3 shows an end view of the muffler of Figure 1; Figure 4 shows a cross-sectional side view of the muffler of Figure 1; Figure 5 shows a cross-sectional plan view of an exhaust muffler in accordance with a second embodiment of the invention in which the first flow path is represented; Figure 6 shows a cross-sectional plan view of the muffler of Figure 5 in which the second flow path is represented; Figure 7 shows a cross-sectional view of the muffler of Figure 6 along the plane A-A shown in Figure 6; Figure 8 shows a cross-sectional side view of the internal rotating component of the valve of the muffler of Figures 5 and 6 ; Figure 9 shows a cross-sectional side view of the internal rotating component of Figure 8, which has been rotated by 90°; Figure 10 shows a cross-sectional side view of the fixed sleeve of the valve of the muffler of Figures 5 and 6 ; Figure 11 shows a cross-sectional side view of the fixed sleeve of Figure 10, which has been rotated by 90°; Figure 12 shows an end view of the valve of the muffler of Figures 5 and 6, showing the gear drive for rotating the inner valve within the fixed sleeve; and Figure 13 shows an end view of the valve of the muffler of Figures 5 and 6, showing an alternative drive for rotating the inner valve within the fixed sleeve.

Modes for Carrying out the Invention Referring generally to Figures 1 to 4 , an exhaust muffler in accordance with a first embodiment of the invention is shown in the form of tunable muffler 10. The muffler 10 is shown in the form of a tri-flow muffler of the type well-known in the art. The muffler 10 consists of three chambers; an entry chamber 12, an exit chamber 14 and a middle chamber 16. Referring specifically to Figures 1 and 4, an exhaust gas inlet is shown in a form of inlet pipe 18, which extends from the engine (not shown) to the entry chamber 12. Joining pipe 20 extends between entry 12 and exit 14 chambers and enables fluid communication therebetween. An exhaust gas outlet is shown in the form of outlet pipe 22, which extends from exit chamber 14 to a point external to the muffler. Outlet pipe 22 can have an aperture in the wall of the pipe in the form of inlet aperture 24. Inlet aperture 24 is situated on the portion of outlet pipe inside entry chamber 12 and is in proximity to the end of inlet pipe 18.

A control means for controlling gas flow is shown in the form of sleeve 26, which is mounted on a portion of outlet pipe 22 in the entry chamber 12 and which may cover the inlet aperture 24. The sleeve 26 includes an aperture in the wall of the sleeve in the form of sleeve aperture 28, which can be a similar size and shape to inlet aperture 24.

The sleeve aperture 28 and inlet aperture 24 are in alignment in Figures 1, 3 and 4. Accordingly, a first flow path for exhaust gas through the muffler is defined, wherein exhaust gas is introduced into entry chamber 12 via inlet pipe 18. The gas then enters outlet pipe 22 via the aligned sleeve aperture 28 and inlet aperture 24, and thereby exits the muffler. In this configuration, a bulk of the exhaust gas passes substantially straight through the muffler, giving the desirable results described earlier.

The interior of middle chamber 16 may optionally be packed with a sound absorbing material, such as high temperature fibreglass, if it is desired that some engine noise be absorbed whilst the muffler is in this configuration .

Referring now to Figure 2, the tunable muffler 10 of Figure 1 is shown in a different configuration. In this configuration, sleeve 26 has been rotated about outlet pipe 22 and the inlet aperture 24 is now completely out of alignment with the sleeve aperture 28. Accordingly, flow through the inlet aperture 24 is not possible and instead a second flow path is defined, wherein the exhaust gas is introduced into entry chamber 12 via inlet pipe 18. The gas then flows through joining pipe 20 into exit chamber 14 and then into outlet pipe 22, from where it leaves the muffler. When exhaust gas flows through the second flow path, the direction of gas flow is changed by 360°, causing the exhaust gas to flow in different directions and causing interactions which deaden the sound. Accordingly, the engine noise becomes muffled.

It will be appreciated that the inlet 24 and sleeve 28 apertures may be in a number of different alignments. Accordingly, the proportion of exhaust gas which flows through each flow path is variable by a user, producing the desired advantages described earlier. Referring to Figures 1, 2 and 4, a number of punctures 30 are incorporated into the portions of the inlet 18, joining 20 and outlet 22 pipes that are situated in the middle chamber 16. These punctures allow a small proportion of exhaust gas to escape from the pipes and cause further interaction between gas travelling in different directions, thereby resulting in further muffling of engine noise.

Referring again to Figure 1, a flange 32 is shown attached to the end of sleeve 26, the flange being external to the muffler 10. A tab 34 is integrally formed with the flange 32. The sleeve 26 can be held in position by a locking means in the form of retaining plate 36 which is attached to the muffler using a plurality of bolts 38. Alternatively, locking pins (not shown) may be used to attach retaining plate 36 to the muffler. Outlet nipple 37 is formed integrally with retaining plate 36 and a tail pipe (not shown) may be attached to the nipple if so desired.

Referring now to Figure 3, the retaining plate 36 and tab 34 can be more clearly seen. The bolts 38 can be loosened, allowing sleeve 26 to be rotated by a user by moving tab 34. Thus, the degree of overlap between inlet aperture 24 and sleeve aperture 28, and hence the effective size of the overall aperture, can be adjusted by a user as desired. The bolts 38 can then be re-tightened to lock the sleeve in that position.

Tab 34 is movable by a user to any position between open stop 40 and closed stop 42, which are formed integral to retaining plate 36. When tab 34 is adjacent to the open stop 40, the sleeve aperture 28 is in alignment with the inlet aperture 24, and the effective size of the aperture in outlet pipe 22 is the maximum. Accordingly, the highest proportion of exhaust gas flows directly through the muffler, as described earlier.

However, when tab 34 is moved from the position adjacent to the open stop 40, the sleeve aperture 28 and the inlet aperture 24 are no longer in alignment, and the effective size of the aperture becomes progressively smaller. When tab 34 is adjacent to the closed stop 42, sleeve aperture 28 does not overlie inlet aperture 24 at all, and there is no effective aperture in outlet pipe 22. Accordingly, exhaust gas flows through the second flow path, as described earlier.

The degree of overlap between the two apertures, and hence the effective size of the aperture in outlet pipe 22, enables a user to control the proportion of exhaust gas flowing through the first and second flow paths. The amount of engine noise muffled by the muffler, as well as the back pressure caused by the muffler on the engine is therefore adjustable, thereby allowing tuning of engine performance .

Now referring to Figures 5 to 7, an exhaust muffler in accordance with a second embodiment of the invention is shown in the form of tunable muffler 100. Tunable muffler 100 is shown in the form of a tri-flow muffler known in the art. Tunable muffler 100 has an exhaust gas inlet in the form of inlet pipe 102 and an exhaust gas outlet in the form of outlet valve 104. The tunable muffler 100 can consist of four chambers; a first chamber 106, a second chamber 108, a third chamber 110 and a fourth chamber 111. The first 106 and second 108 chambers are separated by a first internal baffle 112 and the second 108 and third 110 chambers by a second internal baffle 114. The first 106 and fourth 111 chambers are separated by the outlet valve 104 and by baffles 115 (as shown in Figure 7) .

The tunable muffler 100 can also have a first joining pipe 116 and a second joining pipe 118, which respectively cause the first 106 and third 110 chambers and the third 110 and fourth 111 chambers to be in fluid communication.

As shown in Figures 5 and 6, a number of punctures 119 can be incorporated into the first 116 and second 118 joining pipes, as well as the portion of the inlet pipe 102 that is situated in the second chamber 108. These punctures allow a small proportion of exhaust gas to escape from the pipes into the second chamber 108 and cause further interaction between gas travelling in different directions, thereby resulting in further muffling of engine noise.

The interior of the second chamber 108 may optionally be packed with a sound absorbing material, such as high temperature fibreglass, if it is desired that some engine noise be absorbed whilst exhaust gas is flowing through the inlet pipe 102 and first 116 and second 118 joining pipes. The interior of the inlet pipe 102 can also be a glass packed resonator, as in a "hot dog" muffler, of the type known in the art . The inlet pipe 102 has an inlet aperture in the form of a constricted end 120. The constricted end 120 defines an opening that can have a semicircular shape. The constricted end 120 is co-operable with a valve aperture in the outlet valve 104, which is preferably shaped similarly to the constricted end 120, in the form of valve opening 122. The outlet valve 104 has a valve outlet chamber 124, which is in fluid communication with a tail pipe 126. The tail pipe 126 directs the exhaust gas in an appropriate direction once it has exited the muffler. Outlet valve 104 can be generally cylindrically shaped and can be encased by a fixed sleeve in the form of valve sleeve 127. Valve sleeve 127 is also generally cylindrically shaped.

The outlet valve 104 is operable in conjunction with the valve sleeve 127 to provide a control means for controlling gas flow, as is discussed below.

Referring now to Figures 8 and 9, the outlet valve 104 is shown in further detail. The outlet valve 104 can have two chambers, the valve outlet chamber 124 and a valve diversion chamber 128. In other embodiments, however, the outlet valve may have only the valve outlet chamber 124.

The valve diversion chamber 128 has an opening 129 which, together with the valve opening 122, define the end of the outlet valve 104. The opening 129 is also co- operable with the constricted end 120. Preferably, the opening 129 is semicircularly shaped. The valve diversion chamber 128 comprises an aperture in the wall of the outlet valve 104, in the form of diversion aperture 130. Exhaust gas which enters the valve diversion chamber 128 through the opening 129 can exit the chamber through the diversion aperture 130. The outlet valve 104 can also have an aperture in the wall of the valve outlet chamber 124, in the form of second diversion aperture 132. Exhaust gas which enters the valve outlet chamber 124 can pass through valve outlet 134, which is in fluid communication with the tail pipe 126, and thereby leave the muffler. Referring now to Figures 10 and 11, the valve sleeve 127 is shown in further detail. Valve sleeve 127 includes a first sleeve aperture 138 and a second sleeve aperture 140. As can be seen in Figures 5 and 6, the outlet valve 104 is encased by the valve sleeve 127 in the tunable muffler 100. The outlet valve 104 can be rotated with respect to the valve sleeve 127 such that first diversion aperture 130 can become aligned with first sleeve aperture 138. Simultaneously, the second diversion aperture 132 becomes aligned with the second sleeve aperture 140.

When the first diversion aperture 130 and first sleeve aperture 138 and the second diversion aperture 132 and second sleeve aperture 140 are out of alignment, the constricted end of the inlet pipe 120 is substantially in alignment with the valve opening 122. This orientation of the outlet valve 104 defines a first configuration of the tunable muffler 100.

When the first diversion aperture 130 and first sleeve aperture 138 and the second diversion aperture 132 and second sleeve aperture 140 are in alignment, the constricted end 120 of the inlet pipe 102 is substantially in alignment with the opening 129 and correspondingly, the constricted end 120 is substantially out of alignment with the valve opening 122. This orientation of the outlet valve 104 defines a second configuration of the tunable muffler 100.

Referring now to Figure 12, a mechanism that can enable a user to rotate the outlet valve 104 is shown. Rotation of a cog 142 having teeth 144, which interengage with corresponding teeth 144 on the outlet valve 104, causes the outlet valve to rotate. The cog 142 can be caused to rotate by a user by turning a nut 146 (shown in Figure 5) which is external to the turnable muffler 100. Once a user has selected a desired position, the outlet valve 104 can be prevented from rotating by means of a lock nut (not shown) .

Alternatively, as is shown in Figure 13, rotation of the outlet valve 104 may be actuated by turning a nut 148 which is located inside the bore of the outlet valve and secured to a bridge 150 that spans a diameter of the outlet valve. The nut 148 may be rotated by a user with a long socket inserted into the end of the tail pipe (not shown) .

Referring to Figure 5, the tunable muffler 100 is shown in the first configuration defining a first flow path, in which exhaust gas transferred from an engine (not shown) to the muffler via the inlet pipe 102 is caused to pass through the constricted end of the inlet pipe 120 and the valve opening 122, which are in alignment, and into the valve outlet chamber 124. The exhaust gas then flows to tailpipe 126 and exits the tunable muffler 100.

In this configuration, a bulk of the exhaust gas passes substantially straight through the muffler, giving the desirable results described earlier.

Referring now to Figure 6, the tunable muffler 100 is shown in the second configuration defining a second flow path, in which exhaust gas transferred from an engine (not shown) to the muffler via the inlet pipe 102 is caused to pass through the constricted end of the inlet pipe 120 and the opening 129, which are in alignment. The exhaust gas therefore passes into the valve diversion chamber 128. As the outlet valve 104 is in the second configuration, the first diversion aperture 130 and the first sleeve aperture 138 are in alignment and the exhaust gas can flow from the diversion chamber 128 through these apertures and into the first chamber 106.

The exhaust gas then enters the first joining pipe 116 and passes through the second chamber 108 and into the third chamber 110. From the third chamber 110, the exhaust gas passes around the inlet pipe 102 and into the second joining pipe 118, through the second chamber 108 and into the fourth chamber 111. As the outlet valve 104 is in the second configuration, the second diversion aperture 132 and the second sleeve aperture 140 are in alignment and the exhaust gas can flow through these apertures and into the valve outlet chamber 124, and hence into the tailpipe 126, where it exits from the muffler.

When exhaust gas flows through the second flow path, the direction of gas flow is changed by 360°, causing the exhaust gas to flow in different directions and causing interactions which deaden the sound. Accordingly, the engine noise becomes muffled.

It will be appreciated that the constricted end of inlet pipe 120 and the valve opening 122 may be in a number of different alignments. A user is thereby able to control the proportion of exhaust gas flowing through the first and second flow paths. The amount of engine noise muffled by the muffler, as well as the back pressure caused by the muffler on the engine is therefore adjustable, thereby allowing tuning of engine performance. Although the invention has been described with reference to particular embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. For example, the muffler of the present invention is not limited to being used on cars, and could be used on other types of vehicle, such as motorbikes, trucks, boats etc.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

CLAIMS :

1. An exhaust muffler comprising: an exhaust gas inlet; an exhaust gas outlet; the muffler defining first and second flow paths from the inlet to the outlet; the first flow path being arranged to provide less resistance to exhaust gas flow than the second flow path; and control means operable by a user for controlling gas flow through the first flow path.

2. An exhaust muffler according to claim 1 wherein the first flow path passes through a first aperture and the control means operates by selectively obstructing the aperture .

3. An exhaust muffler according to claim 2 wherein the first aperture is provided in the wall of a pipe, the bore of the pipe being in fluid communication with the exhaust gas outlet, and the control means comprises a sleeve mounted on the pipe, the sleeve being movable to selectively and progressively obstruct the first aperture.

4. An exhaust muffler according to claim 3 wherein the sleeve comprises a second aperture in a wall of the sleeve, the second aperture being cooperable with the first aperture such that rotation of the sleeve causes selective and progressive obstruction of the first aperture .

5. An exhaust muffler according to any one of claims 1 to 4 further comprising a locking means to lock the control means in a desired position.

6. An exhaust muffler according to claim 5 wherein the locking means comprises a flange extending outwardly from the sleeve which may be clamped or pinned to prevent movement of the sleeve.

7. An exhaust muffler according to any one of the preceding claims wherein the control means is also operable to completely obstruct the first aperture to prevent flow of exhaust gas through the first flow path, thereby causing substantially all of the exhaust gas to flow through the second flow path.

8. An exhaust muffler according to claim 1, wherein the first flow path passes through an inlet aperture which is in alignment with a valve aperture and into a valve, the valve being in fluid communication with the exhaust gas outlet, and wherein the control means operates by selectively and progressively causing the inlet aperture and the first valve aperture to become out of alignment and vice versa.

9. An exhaust muffler according to claim 8, wherein the control means operates by causing the valve or a portion of the valve to rotate.

10. An exhaust muffler according to claim 8 or 9, wherein the valve comprises a cylindrically shaped internal rotating portion and a fixed sleeve.

11. An exhaust muffler according to claim 10, wherein the fixed sleeve comprises a sleeve aperture, the sleeve aperture being cooperable with a wall aperture in the wall of the valve, whereby the second flow path passes through the sleeve aperture and wall aperture.

12. An exhaust muffler according to claim 11, wherein rotation of the internal rotating portion of the valve is such that the inlet aperture and valve aperture are selectively and progressively caused to become out of alignment, causing the sleeve aperture and wall aperture to become selectively and progressively aligned, and vice versa.

13. An exhaust muffler according to any one of claims 8 to 12, wherein the inlet aperture and the valve aperture are semicircularly shaped.

14. An exhaust muffler according to any one of claims 10 to 13, wherein the internal rotating portion is caused to rotate by a gear drive which is driven by a user rotating an external projection.

15. An exhaust muffler according to any one of claims 10 to 13, wherein the internal rotating portion is caused to rotate by a user rotating a member located within the valve and accessible through the bore of a tail pipe mounted to the exhaust gas outlet.

16. An exhaust muffler according to any one of claims 8 to 15, wherein a pipe which joins the exhaust gas inlet to the inlet aperture comprises a glass packed resonator.

17. An exhaust muffler according to any one of the preceding claims, wherein the muffler is of a tri-flow muffler configuration.

18. An exhaust muffler according to any one of the preceding claims, wherein an internal chamber of the muffler contains sound absorbing material .