US20130048416A1

US20130048416A1 - Exhaust muffler

Info

Publication number: US20130048416A1
Application number: US13/221,985
Authority: US
Inventors: Rajdeep S. Pradhan
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2011-08-31
Filing date: 2011-08-31
Publication date: 2013-02-28
Also published as: AU2012204036A1

Abstract

An exhaust muffler for an internal combustion engine, the exhaust muffler including a housing having a first end plate and a second end plate. The second end plate is disposed opposite to the first end plate. The exhaust muffler also includes an inlet pipe connected to the first end plate and an outlet pipe connected to the second end plate of the housing. A plurality of passages are disposed within the housing along a longitudinal axis of the housing, the plurality of passages have different lengths.

Description

TECHNICAL FIELD

The present disclosure relates to exhaust mufflers for internal combustion engines, and more particularly to an exhaust muffler configured to provide sound attenuation for a broad range of frequencies.

BACKGROUND

Mufflers are employed with internal combustion engines for reduction and modulation of noise emitted during operation of the internal combustion engines. For example, U.S. Pat. No. 4,574,914 (the '914 patent) discloses a muffler for a high-performance internal combustion engine. A casing of the muffler has an elongated transverse cross-section with a height dimension of only slightly larger than the height dimension of the inlet exhaust pipe and a width dimension in the range of about 2 to 4.5 times the height dimension. The muffler includes a divergently tapering planar first partition and a second partition. The first partition has a cup-shaped back surface so that contraction of gases around a back side of the first partition is highly effective in attenuating sound, and both partitions are sloped in a direction toward an outlet from the muffler so as to minimize generation of back pressure, which is not substantially greater than the back pressure in a straight pipe.

SUMMARY

In an aspect, the present disclosure provides an exhaust muffler for an internal combustion engine. The exhaust muffler includes a housing having a first end plate and a second end plate. The second end plate disposed opposite to the first end plate. An inlet pipe is connected to the first end plate. The exhaust muffler further includes a plurality of passages disposed within the housing along a longitudinal axis of the housing, the plurality of passages have different lengths. Further, an outlet pipe is connected to the second end plate of the housing.
Other features and aspects of the present disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an perspective view of an exhaust muffler, according to an aspect of this disclosure; and

FIG. 2 is a sectional view of the exhaust muffler of FIG. 1, taken along plane X-X′.

DETAILED DESCRIPTION

FIG. 1 illustrates a perspective view of an exhaust muffler 100, according to an aspect of the present disclosure. The exhaust muffler 100 may be installed in an exhaust system of an engine (not shown). In an embodiment, the engine may be, without any limitation, an internal combustion engine, a gasoline or diesel engine, a natural gas engine, a propane gas engine, and the like. The engine may further include a number of cylinders arranged in any suitable configuration, for example, in-line arrangement, “V” arrangement, radial arrangement, or the like. The engine may be used to power any machine or other device, including on-highway trucks or vehicles, off-highway trucks or machines, earth moving equipment, generators, aerospace applications, locomotive applications, marine applications, pumps, stationary equipment, or other engine powered applications. Based on the application, the size of the engine may vary without deviating from the scope of the present disclosure.
The exhaust muffler 100 includes a housing 102 having a first end plate 104, and a second end plate 106. The housing 102 may have cylindrical shape with a longitudinal axis AA′ extending along a length of the housing 102, such that the first and the second end plates 104 and 106 are disposed opposite to each other. The first and the second end plates 104 and 106 may be joined with the housing 102 using welding. The housing 102, and the first and the second end plates 104 and 106, may be made of aluminized steel, stainless steel, or the like. In various other embodiments of the present disclosure, the housing 102 may have a rectangular shape, conical shape etc. In FIG. 1, a portion of the housing 102 is removed to provide a partial view of the internal components of the exhaust muffler 100.
As illustrated in FIG. 1, the exhaust muffler 100 includes one or more inlet pipes, such as two inlet pipes 108, connected to the first end plate 104. The inlet pipes 108 may allow a flow of the exhaust gases into a first chamber 110 of the housing 102. In an embodiment, the inlet pipes 108 may be at an offset from the longitudinal axis AA′ of the housing 102. The exhaust muffler 100 further includes an outlet pipe 112 connected to the second end plate 106 along the longitudinal axis AA′. The outlet pipe 112 may discharge the exhaust gases from a second chamber 114 of the housing 102. In an embodiment, the inlet and the outlet pipes 108 and 112 may include flange portions to connect with an exhaust pipe and a tailpipe in the exhaust system.
According to an embodiment of the present disclosure, a plurality of passages 116 may be disposed within the housing 102 extending along the longitudinal axis AA′. The passages 116 may allow the exhaust gases to flow from the first chamber 110 to the second chamber 114 of the housing 102. In the illustrated embodiment, the passages 116 may include tubes, such as 118, 120, 122, 124, and 126. In various other embodiments, the passages 116 may include fewer or higher number of tubes, without deviating from the scope of the present disclosure. In another embodiment, the passages 116 may unitarily formed with the housing 102 and include a plurality of channels extending along the longitudinal axis AA′. In an embodiment, the passages 116 may be different lengths, as illustrates in FIG. 1, the tubes 118, 120, and 122 are longer than the tubes 124 and 126. The other aspects of the exhaust muffler 100 are described in conjunction with FIG. 2 illustrating a sectional view of the exhaust muffler 100 along a plane X-X′.
As illustrated in FIG. 2, the inlet pipe 108 may include a tubular body portion 128, which extends into the first chamber 110. In an embodiment, the tubular body portion 128 may have diameter in a range of about 8 inches to 15 inches. The tubular body portion 128 may include one or more intermediate openings 130 positioned within a first resonator chamber 132. In an embodiment, the intermediate openings 130 may have a diameter in a range of about 3.5 inches to 4 inches. The first resonator chamber 132 may be defined by the first end plate 104 and an intermediate plate 134. The first resonator chamber 132 may have a specific volume and dimensions to generate a reflected sound wave to cancel out one or more frequencies of sound in the exhaust gases. Further, perforated sheets 135 may be attached to the first and the second end plates 104 and 106. The perforated sheets 135 may have about 25% to 40% open area (OA).
Moreover, the tubular body portion 128 of the inlet pipe 108 may include a perforated portion 136 made from perforated sheets having about 25% to 40% open area (OA). In an embodiment, the perforated portion 136 may have a diameter in a range of about 10 inches to 18 inches. Further, the perforated portion 136 may have staggered holes having diameter in a range of about 0.5 inches to 1.5 inches. The perforated portion 136 extends into the first chamber 110 of the housing 102, such that the exhaust gases coming from the inlet pipe 108 flow into the first chamber 110 through the holes provided on the perforated portion 136. In an embodiment, the inlet pipe 108 may include an end portion 138 connected to the perforated portion 136. The end portion 138 may have a diameter in a range of about 8 inches to 15 inches, such that an internal space defined by the end portion 138 may also act as a resonator chamber. In an embodiment, the end portion 138 may be positioned at an offset from a longitudinal axis BB′ of the inlet pipe 108. In another embodiment, the end portion 138 may also include perforations. It may be apparent to a person skilled in the art that another inlet pipe 108 (see FIG. 1) may be structurally similar and may be configured to dispense the exhaust gases into the first chamber 110.
In an embodiment, the exhaust muffler 100 further includes a second resonator chamber 140 disposed within the housing 102. As illustrated in FIG. 2, the second resonator chamber 140 divides the housing 102 into the first chamber 110 and the second chamber 114. The second resonator chamber 140 may be defined by a first side wall 142 and a second side wall 144. The first and the second side walls 142 and 144 may be joined with the housing using welding. Further, the first side wall 142 of the second resonator chamber 140 includes an opening 146 and a guiding portion 148 extending from a peripheral surface of the opening 146. The second resonator chamber 140 may also have a specific volume and length to generate a reflected sound wave to cancel out a certain frequency of sound in the exhaust gases.
In an embodiment, the passages 116 may be supported by the first side wall 142 and the second side wall 144. The passages 116 may pass through the first side wall 142 and the second side wall 144, such that the passages 116 extend longitudinally from the first chamber 110 to the second chamber 114. Therefore, the passages 116 may allow the exhaust gases to flow from the first chamber 110 to the second chamber 114. Further, FIG. 2 illustrates a sectional view of the tube 122 defining one of the passages 116. The tube 122 may have an inner surface 150 made of a perforated sheet, such that the inner surface 150 may have about 25% to 40% open area (OA). Further, a layer 152 of sound absorbing material is provided over the inner surface 150 to absorb sound in the exhaust gases and also provide thermal insulation. The layer 152 may include fiberglass, steel wool, or the like. The tube 122 may also include an outer surface 154 to cover the layer 152 of the insulating material.
In an embodiment, the tube 122 may have a length in a range of about 30 inches to 40 inches and a diameter in a range of about 5 inches to 10 inches. Further, the tube 122 may have a first end 156 and a second end 158 disposed in the first chamber 110 and the second chamber 114, respectively. In an embodiment, the first end 156 and the second end 158 are provided with bell-mouth shaped entry and exit portions 160 and 162 respectively, for the entry and exit of the exhaust gases. In an embodiment, the bell-mouth shape entry and exit portions 160 and 162 may have length in a range of about 2 inches to 5 inches to provide a smooth flow of the exhaust gases and reduce a pressure drop in the flow of the exhaust gases.
In an embodiment, the first end 156 may include an inlet portion 164 adjacent to the bell-mouth shaped entry portion 160. The inlet portion 164 may be also made of a perforated sheet having about 25% to 40% open area (OA). The inlet portion 164 may allow the exhaust gases to enter the tube 122 through the perforations provided on the inlet portion 164. The inlet portion 164 may have a length in a range of about 5 inches to 10 inches and a diameter in a range of about 5 inches to 10 inches. Moreover, it will apparent to a person skilled in the art that the passages 116 including the tubes 118, 122, 124, and 126 may, functionally and structurally similar to the tube 122, as described above. In an embodiment the length of tubes 120 and 124 may be substantially equal to the tube 118. However, the length of tubes 118 and 126 may be in a range of about 25 inches to 35 inches. In an embodiment, the passages 116 may be at an offset from the longitudinal axis BB′ of the inlet pipes 108.

INDUSTRIAL APPLICABILITY

Internal combustion engines are employed with various machines, including on-highway trucks or vehicles, off-highway trucks or machines, earth moving equipment, generators, aerospace applications, locomotive applications, marine applications, pumps, stationary equipment, or other engine powered applications. During operation, an internal combustion engines may produce high, medium and low frequency sound waves by repeated opening of exhaust valves to blow out the exhaust gases. In an aspect of the present disclosure, the exhaust muffler 100 is deigned to attenuate high, low, and medium frequency sound waves.
In general, the first and the second resonator chambers 132 and 140 of the exhaust muffler 100 are configured to reflect the sound waves and cancel out the incoming sound waves. In an aspect of the present disclosure, the first and the second resonator chambers 132 and 140 are deigned to resonate and cancel out at low frequency of sound waves. However, for the high and medium frequency sound waves the resonator chambers 132 and 140 may not have any effect.
Further, the sound waves propagating through the passages 116 may be attenuated by absorbing the high and medium frequency sound waves by the layer 152 of the absorbing material. The layer 152 of the absorbing material may absorb the high and medium frequency sound waves and transform acoustic energy into heat energy. The layer 152 also may provide thermal insulation to the other components on the exhaust muffler 100. By providing a plurality of passages 116 having different lengths the exhaust muffler 100 may provide sound attenuation for a broad range of high and medium frequencies.
Moreover, the first chamber 110 and the second chamber 114 may allow the exhaust gases to expand. A sudden expansion of the exhaust gases also produces a reflected sound wave to attenuate sound waves in a broad frequency ranges. Moreover, by proving the bell-mouth entry and exit portions 160 and 162 for the passages 116 the pressure drop caused by sudden expansion is reduced. The bell-mouth entry and exit portions 160 and 162 also provide a smooth change in areas while entering or exiting the passages 116.
The exhaust muffler 100 of the present disclosure reduces the sound produced by the exhaust gases of the internal combustion engine. In an aspect of the present disclosure, the exhaust muffler 100 attenuates high, medium and low frequency sound waves. Moreover, the exhaust muffler 100 of the present disclosure, during the propagation of the exhaust gases therethrough, also reduces pressure drop in the exhaust gases thereby ensuring efficient operation of the internal combustion engine.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines and systems without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.

Claims

1. An exhaust muffler for an internal combustion engine, the exhaust muffler comprising:

a housing having a first end plate and a second end plate, the second end plate disposed opposite to the first end plate, wherein a perforated sheet having a plurality of openings is attached adjacent to at least one of the first end plate and the second end plate;

an inlet pipe connected to the first end plate;

a plurality of passages disposed within the housing along a longitudinal axis of the housing, the plurality of passages have different lengths; and

an outlet pipe connected to the second end plate of the housing.

2. The exhaust muffler of claim 1, wherein the plurality of passages includes tubes.

3. The exhaust muffler of claim 2, wherein the tubes include a bell-mouth shaped entry portion and a bell-mouth shaped exit portion.

4. The exhaust muffler of claim 3, wherein the tubes further include an inner surface, an outer surface, and a layer of sound absorbing material disposed between the inner surface and the outer surface.

5. The exhaust muffler of claim 4, wherein the inner surface is made of perforated sheet having about 25% to 40% open area.

6. The exhaust muffler of claim 4, wherein the tubes further include an inlet portion adjacent to the bell-mouth shaped entry portion.

7. The exhaust muffler of claim 6, wherein the inlet portion is made of a perforated sheet having about 25% to 40% open area.

8. The exhaust muffler of claim 1 further including a first resonator chamber defined by the first end plate and an intermediate plate.

9. The exhaust muffler of claim 8, wherein the inlet pipe includes a tubular body portion offset from the longitudinal axis and having an intermediate opening positioned within the first resonator chamber.

10. The exhaust muffler of claim 8, wherein the inlet pipe includes a perforated portion extending into the housing.

11. The exhaust muffler of claim 1 further including a second resonator chamber disposed within the housing, the second resonator chamber is defined by a first side wall and a second side wall.

12. The exhaust muffler of claim 11, wherein the passages are supported by the first side wall and the second side wall.

13. The exhaust muffler of claim 11, wherein the second resonator chamber includes an opening.

14. (canceled)

15. An exhaust muffler for an internal combustion engine, the exhaust muffler comprising:

a first resonator chamber defined by the first end plate and an intermediate plate;

an inlet pipe connected to the first end plate, the inlet pipe includes a tubular body portion having an intermediate opening positioned within the first resonator chamber;

a second resonator chamber disposed within the housing, the second resonator chamber is defined by a first side wall and a second side wall;

a plurality of passages disposed within the housing along a longitudinal axis of the housing, the plurality of passages supported by the first side wall and the second side wall and have different lengths; and

an outlet tube connected to the second end plate of the housing.

16. The exhaust muffler of claim 15, wherein the plurality of passages includes tubes having a bell-mouth shaped entry portion and a bell-mouth shaped exit portion.

17. The exhaust muffler of claim 16, wherein the tubes further include an inner surface, an outer surface, and a layer of sound absorbing material disposed between the inner surface and the outer surface.

18. The exhaust muffler of claim 17, wherein the inner surface is made of perforated sheet having about 25% to 40% open area.

19. The exhaust muffler of claim 18, wherein the tubes further include an inlet portion adjacent to the bell-mouth shaped entry portion, the inlet portion is made of a perforated sheet having about 25% to 40% open area.

20. The exhaust muffler of claim 15, wherein the inlet pipe includes a perforated portion extending into the housing.

21. The exhaust muffler of claim 1, wherein the perforated sheet attached to at least one of the first end plate and the second end plate includes about 25% to 40% open area.