Title:
VEHICLE MUFFLER AND METHOD OF ASSEMBLY
United States Patent 3638756
Abstract:
A muffler for vehicles propelled by internal combustion engines. The muffler is formed of two pieces, preferably metal stampings, in which the various chambers and passages are indented or embossed. The two pieces are joined at their peripheral edges. The muffler is tuned by adjusting the relative size and arrangement of chambers and passages. In one modification the position of the pieces may be adjusted relatively to each other to permit variable tuning.
US Patent References:
Baffle type muffler with corrugated casing
Harley - October 1949 - 2484827
Silencer
Gerstung - November 1958 - 2860722
Muffler or other hollow article and fabrication of same
Tranel - July 1964 - 3140755
Muffler
Richmond - November 1964 - 3158222
Mufflers for marine engines
Betts et al. - April 1965 - 3176791
Baffle type muffler with corrugated casing
Harley - October 1949 - 2484827
Silencer
Gerstung - November 1958 - 2860722
Muffler or other hollow article and fabrication of same
Tranel - July 1964 - 3140755
Muffler
Richmond - November 1964 - 3158222
Mufflers for marine engines
Betts et al. - April 1965 - 3176791
Application Number:
04/889102
Publication Date:
02/01/1972
Filing Date:
12/30/1969
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
181/282
International Classes:
F01N1/02; F01N1/08; F01N7/18; F01N1/02; F01N7/18; F01N1/08
Field of Search:
181/35,35.3,46,56,61-63,44,45,49,47,57,48,59,53,54,72
US Patent References:
| 3220508 | Muffler with interlocked casing and baffle members | November 1965 | Nordquest et al. |
Primary Examiner:
Ward Jr., Robert S.
Claims:
I claim
1. A vehicle muffler comprising mating top and bottom pieces and means joining said pieces at their peripheral edges, said pieces having indentations defining one or more mixing chambers, and an inlet and outlet communicating with said chambers, whereby the level of noise accompanying gases introduced through said inlet is lowered and the resultant noise tuned to be characteristic of the vehicle, a low point being provided in the muffler to facilitate drainage.
2. A muffler as defined in claim 1 in which said pieces are metal stampings and the means joining the stampings include lips extending around their peripheries, and in which said indentations define at least two mixing chambers and means affording restricted communication between said chambers.
3. A muffler as defined in claim 2 in which said pieces can be adjusted relatively to each other to permit variable tuning.
4. A vehicle muffler comprising:
5. A muffler as defined in claim 4 in which said pieces have embossments between said mixing chambers and said passages defining restricted openings which slant in the direction of gas flow.
6. A muffler as defined in claim 5 in which the wall between said distribution chamber and said second mixing chamber is adapted to direct high-frequency sound waves into said passages, and said restricted openings are adapted to conduct low-frequency sound waves into said passages, where the high and low frequency sound waves blend.
7. A vehicle muffler comprising mating top and bottom pieces having lips extending around their peripheral edges, said lips having interfitting indentations, brazing material interposed between said interfitting indentations joining said pieces, said pieces having indentations defining one or more mixing chambers and an inlet and outlet communicating with said chambers, whereby the level of noise accompanying gases introduced through said inlet is lowered and the resultant noise tuned to be characteristic of the vehicle.
8. A muffler as defined in claim 7 in which said pieces are metal stampings internally coated with porcelain.
1. A vehicle muffler comprising mating top and bottom pieces and means joining said pieces at their peripheral edges, said pieces having indentations defining one or more mixing chambers, and an inlet and outlet communicating with said chambers, whereby the level of noise accompanying gases introduced through said inlet is lowered and the resultant noise tuned to be characteristic of the vehicle, a low point being provided in the muffler to facilitate drainage.
2. A muffler as defined in claim 1 in which said pieces are metal stampings and the means joining the stampings include lips extending around their peripheries, and in which said indentations define at least two mixing chambers and means affording restricted communication between said chambers.
3. A muffler as defined in claim 2 in which said pieces can be adjusted relatively to each other to permit variable tuning.
4. A vehicle muffler comprising:
5. A muffler as defined in claim 4 in which said pieces have embossments between said mixing chambers and said passages defining restricted openings which slant in the direction of gas flow.
6. A muffler as defined in claim 5 in which the wall between said distribution chamber and said second mixing chamber is adapted to direct high-frequency sound waves into said passages, and said restricted openings are adapted to conduct low-frequency sound waves into said passages, where the high and low frequency sound waves blend.
7. A vehicle muffler comprising mating top and bottom pieces having lips extending around their peripheral edges, said lips having interfitting indentations, brazing material interposed between said interfitting indentations joining said pieces, said pieces having indentations defining one or more mixing chambers and an inlet and outlet communicating with said chambers, whereby the level of noise accompanying gases introduced through said inlet is lowered and the resultant noise tuned to be characteristic of the vehicle.
8. A muffler as defined in claim 7 in which said pieces are metal stampings internally coated with porcelain.
Description:
This invention relates to improved mufflers for vehicles propelled by internal combustion engines and to improved methods of assembling and tuning such mufflers.
A conventional muffler includes a double-walled metal casing and a plurality of baffles, tubes or pipes within the casing. The space between the two walls commonly is filled with asbestos. The internal parts are spot-welded to the casing, and the end walls and wrap of the casing are crimped or lock-seamed together. A typical conventional muffler has a total of 13 pieces. A muffler usually fails through corrosion caused by an accumulation of highly corrosive condensate within its interior. Although the parts are galvanized, this method of construction leaves raw unprotected edges which are exposed to condensate and corrode rapidly. This corrosion leaves internal parts unsupported and allows them to rock and causes mechanical failure of external joints. Conventional muffler design and fabrication methods are poor in resisting corrosion and often produce conditions which accelerate failure.
A muffler not only lowers the noise of an engine to an acceptable level of about 80 to 85 decibels, but commonly is tuned to give a distinctive sound to each make of vehicle on which it is installed. Heretofore the parts of the muffler have been relatively fixed, and tuning could be accomplished only by arranging the internal parts in the proper relation when the muffler is manufactured. This necessitates a different muffler construction for each make of vehicle if each is to have its own distinctive sound.
An object of my invention is to provide improved mufflers and assembling methods in which the muffler is formed of only two pieces, whereby the muffler is simpler, of lighter weight, and more economical to manufacture than conventional mufflers.
A further object is to provide improved mufflers and assembling methods in which unprotected edges and crevices are avoided, whereby the muffler has better resistance to corrosion.
A further object is to provide improved mufflers and assembling methods which facilitate tuning the muffler to produce the sound distinctive for any particular make of vehicle.
A further object is to provide improved mufflers and assembling methods which enable muffler parts to be standardized to a greater extent than heretofore.
In the drawings:
FIG. 1 is a diagrammatic perspective view of the bottom piece of a two-piece muffler constructed in accordance with my invention to illustrate the principles;
FIG. 2 is a perspective view of one form of actual muffler constructed in accordance with my invention;
FIG. 3 is a top plan view of the bottom piece of the muffler shown in FIG. 2;
FIG. 4 is a perspective view of a modified muffler constructed in accordance with my invention to permit variable tuning; and
FIG. 5 is a fragmentary vertical sectional view of a muffler illustrating one way in which I may join the pieces.
FIG. 1 shows the bottom piece of a possible two-piece muffler constructed in accordance with my invention. The piece preferably is a metal stamping, although it can be cast or molded or formed of other materials, such as plastic or ceramic. The piece illustrated has rectangular indentations 10 and 12, a flat rectangular area 13 between indentations, and a peripheral lip 14. The flat area 13 has a passage 15 of semicircular cross section affording restricted communication between the two indentations. The ends of the piece have indented extensions 16 and 17 which communicate with the respective indentations 10 and 12. The dimensions, locations, shape, and number of indentations and passages may vary. Such variations produce different expansion and contraction of sound waves entering the muffler and various frequency attenuations to produce the desired sound output, as hereinafter explained. Preferably the indentations 10 and 12 have rounded edges, as indicated at 18. I assemble this piece with a mating top piece, and join the two pieces by any suitable means at the periphery, such as welding the two lips 14 or joining them adhesively, or by a novel means hereinafter described in connection with FIG. 5. In the muffler thus assembled, the indentations 10 and 12 afford first and second mixing chambers, and the extensions 16 and 17 afford an inlet and outlet respectively for exhaust gases from an engine.
FIGS. 2 and 3 show an actual construction of two-piece muffler in accordance with my invention designed to produce the sound characteristic of a particular make of automobile of recent model. The muffler comprises mating top and bottom pieces 21 and 22, again preferably formed of metal stampings. Indentations in the pieces form a first mixing chamber 23 adjacent the inlet end, a second mixing chamber 24 adjacent the outlet end, a distribution chamber 25 between the two mixing chambers, and lengthwise passages 26 adjacent each side edge. The ends of the pieces have indented extensions 27 and 28 which communicate with the mixing chambers 23 and 24 respectively and serve as an inlet and outlet for exhaust gases. Series of embossments 30 afford restricted communication between each side of the first mixing chamber 23 and the adjacent passage 26. Similar embossments 31 afford restricted communication between passages 26 and the second mixing chamber 24. The distribution chamber 25 is open at each side throughout its length to the adjacent passage 26. The two pieces 21 and 22 have peripheral lips 32 which are joined by any suitable means as explained in the description of FIG. 1.
FIG. 3 shows the bottom piece 22 in more detail. Besides the indentations and embossments already described, the bottom piece has two transversely spaced embossments 34 separating the first mixing chamber 23 and the distribution chamber 25, and an unbroken transverse embossment 35 which forms a wall separating the distribution chamber and the second mixing chamber 24. The embossments 30 define series of restricted openings 36 which slant from the first mixing chamber 23 toward the passage 26. The embossments 31 define series of restricted openings 37 which slant from the passage 26 toward the second mixing chamber 24. In each instance the openings 36 and 37 slant in the direction of gas flow. The opening between the two embossments 34 is designated 38.
Noises which accompany exhaust gases into the muffler commonly have a noise level of at least 125 decibels and are composed of both high-frequency and low-frequency sound waves. The muffler lowers the noise level to about 80 to 85 decibels, and suppresses undesirable sound wave components. The objective is to produce a characteristic pleasing sound which is distinctive for any particular make and model vehicle. Usually high-frequency sound waves are suppressed to avoid a tinny or metallic sound. However, if high-frequency waves are eliminated together the muffler produces an undesirable hollow sound. The resultant sound output usually sought is a smooth sequence of attenuated low-frequency booms with enough high-frequency sounds to produce a pleasing distinctive tone.
FIG. 3 also shows the pattern which sound waves follow within the muffler shown in FIG. 2. High-frequency waves tend to travel in straight courses. Hence incoming high-frequency waves mostly pass directly through the first mixing chamber 23 and opening 38 into the distribution chamber 25, as indicated by arrows 39. Such waves echo against the embossment 35, which lowers their energy level. The weakened high-frequency waves pass through both sides of chamber 25 into passages 26, as indicated by arrows 40. Low-frequency waves tend to spread sideways. Hence incoming low-frequency waves pass from the first mixing chamber 23 through openings 36 into passages 26, as indicated by arrows 41. The high and low-frequency waves blend within passages 26 and pass through openings 37 into the second mixing chamber 24, as indicated by arrows 42. The final sound output from the muffler of course depends on the relative size and shape of the chambers, passages and openings.
In the modification shown in FIGS. 2 and 3, the low point of the muffler is located near the outlet end to permit condensate to drain thereto. The area around the low point can be specially reinforced to prolong the useful life of the muffler, or the muffler can be equipped with a special drain to carry away condensate from its low point. Another possibility is to locate the low point near a hot part of the muffler so that condensate is revaporized. With my method of construction, I can locate the low point anywhere desired within the muffler.
FIG. 4 shows a two-piece muffler of modified construction in accordance with my invention designed to permit variable tuning. The muffler comprises mating top and bottom pieces 45 and 46, again preferably formed of metal stampings. Indentations in the top piece form a first mixing chamber 47 adjacent the inlet end, a second mixing chamber 48 adjacent the outlet end, a distribution chamber 49 between the two mixing chambers, and a blind chamber 50. A passage 51 affords communication between the first mixing chamber 47 and the distribution chamber 49. Passages 52 and 53 afford communication between the distribution chamber and the second mixing chamber 48 and between the distribution chamber and the blind chamber 50 respectively. The muffler has an inlet 54 formed by indentations in its two pieces, and a similar outlet not shown. The two pieces, although mating, are not necessarily alike, but the bottom piece 46 may provide chambers of other configurations, such as the chamber 55 illustrated. The two pieces have peripheral lips 56 which are joined as in the embodiments already described.
I tune the muffler of FIG. 4 by adjusting the position of the top and bottom pieces 45 and 46 relatively to each other. In the construction illustrated the pieces are arranged for adjustment lengthwise of the muffler, and the top piece carries a scale 57 to indicate the relative position it should occupy for different characteristic sounds. If the muffler is mass-produced, the scale can be used to adjust the pieces to the proper setting for any make of vehicle, thereby permitting standardization. The pieces can be extended at the lips and at the indentations which form the inlet and outlet, and trimmed off flush as shown after they are in their final position of adjustment. With this modification it is possible also to tune the muffler and join the two pieces after the muffler has been installed on a vehicle. This is a particularly desirable feature for replacement mufflers to enable a muffler formed of standardized parts to sound right on any make of vehicle. Although I show two pieces adjustable lengthwise, it is apparent they could be adjustable in other directions, such as transversely or by relative rotation.
FIG. 5 illustrates a preferred way of joining the two pieces of my muffler applicable to nonadjustable forms. The peripheral lips 60 and 61 of this muffler have interfitting indentations 62 and 63. The lower lip 60 has an upstanding flange 64 to provide stiffness. The lower lip 60 has an upstanding flange inner surfaces of the two pieces preferably have a protective coating such as porcelain, which may be applied by dipping or spraying. I interpose a layer 65 of brazing material between the indentations 62 and 63. The brazing material may be brass and may be in powder, strip or rod form. I place the assembled muffler in a porcelain baking oven and fire it. The porcelain acts as a flux and the two pieces are brazed together while they are porcelainized, but if the muffler is not porcelain coated, I can add a suitable flux. I am aware that mufflers have been porcelainized previously, but the porcelain coating could be applied only after the muffler was totally assembled by flowing the porcelain material through the muffler. This is an expensive operation, and did not always produce a uniform coating.
From the foregoing description it is seen that my invention provides a muffler of simple two-piece construction, the individual pieces of which can be formed as inexpensive stampings. The muffler not only has superior corrosion resistance, but is readily tuned to give the noise level and characteristic sound desired for any particular vehicle.
A conventional muffler includes a double-walled metal casing and a plurality of baffles, tubes or pipes within the casing. The space between the two walls commonly is filled with asbestos. The internal parts are spot-welded to the casing, and the end walls and wrap of the casing are crimped or lock-seamed together. A typical conventional muffler has a total of 13 pieces. A muffler usually fails through corrosion caused by an accumulation of highly corrosive condensate within its interior. Although the parts are galvanized, this method of construction leaves raw unprotected edges which are exposed to condensate and corrode rapidly. This corrosion leaves internal parts unsupported and allows them to rock and causes mechanical failure of external joints. Conventional muffler design and fabrication methods are poor in resisting corrosion and often produce conditions which accelerate failure.
A muffler not only lowers the noise of an engine to an acceptable level of about 80 to 85 decibels, but commonly is tuned to give a distinctive sound to each make of vehicle on which it is installed. Heretofore the parts of the muffler have been relatively fixed, and tuning could be accomplished only by arranging the internal parts in the proper relation when the muffler is manufactured. This necessitates a different muffler construction for each make of vehicle if each is to have its own distinctive sound.
An object of my invention is to provide improved mufflers and assembling methods in which the muffler is formed of only two pieces, whereby the muffler is simpler, of lighter weight, and more economical to manufacture than conventional mufflers.
A further object is to provide improved mufflers and assembling methods in which unprotected edges and crevices are avoided, whereby the muffler has better resistance to corrosion.
A further object is to provide improved mufflers and assembling methods which facilitate tuning the muffler to produce the sound distinctive for any particular make of vehicle.
A further object is to provide improved mufflers and assembling methods which enable muffler parts to be standardized to a greater extent than heretofore.
In the drawings:
FIG. 1 is a diagrammatic perspective view of the bottom piece of a two-piece muffler constructed in accordance with my invention to illustrate the principles;
FIG. 2 is a perspective view of one form of actual muffler constructed in accordance with my invention;
FIG. 3 is a top plan view of the bottom piece of the muffler shown in FIG. 2;
FIG. 4 is a perspective view of a modified muffler constructed in accordance with my invention to permit variable tuning; and
FIG. 5 is a fragmentary vertical sectional view of a muffler illustrating one way in which I may join the pieces.
FIG. 1 shows the bottom piece of a possible two-piece muffler constructed in accordance with my invention. The piece preferably is a metal stamping, although it can be cast or molded or formed of other materials, such as plastic or ceramic. The piece illustrated has rectangular indentations 10 and 12, a flat rectangular area 13 between indentations, and a peripheral lip 14. The flat area 13 has a passage 15 of semicircular cross section affording restricted communication between the two indentations. The ends of the piece have indented extensions 16 and 17 which communicate with the respective indentations 10 and 12. The dimensions, locations, shape, and number of indentations and passages may vary. Such variations produce different expansion and contraction of sound waves entering the muffler and various frequency attenuations to produce the desired sound output, as hereinafter explained. Preferably the indentations 10 and 12 have rounded edges, as indicated at 18. I assemble this piece with a mating top piece, and join the two pieces by any suitable means at the periphery, such as welding the two lips 14 or joining them adhesively, or by a novel means hereinafter described in connection with FIG. 5. In the muffler thus assembled, the indentations 10 and 12 afford first and second mixing chambers, and the extensions 16 and 17 afford an inlet and outlet respectively for exhaust gases from an engine.
FIGS. 2 and 3 show an actual construction of two-piece muffler in accordance with my invention designed to produce the sound characteristic of a particular make of automobile of recent model. The muffler comprises mating top and bottom pieces 21 and 22, again preferably formed of metal stampings. Indentations in the pieces form a first mixing chamber 23 adjacent the inlet end, a second mixing chamber 24 adjacent the outlet end, a distribution chamber 25 between the two mixing chambers, and lengthwise passages 26 adjacent each side edge. The ends of the pieces have indented extensions 27 and 28 which communicate with the mixing chambers 23 and 24 respectively and serve as an inlet and outlet for exhaust gases. Series of embossments 30 afford restricted communication between each side of the first mixing chamber 23 and the adjacent passage 26. Similar embossments 31 afford restricted communication between passages 26 and the second mixing chamber 24. The distribution chamber 25 is open at each side throughout its length to the adjacent passage 26. The two pieces 21 and 22 have peripheral lips 32 which are joined by any suitable means as explained in the description of FIG. 1.
FIG. 3 shows the bottom piece 22 in more detail. Besides the indentations and embossments already described, the bottom piece has two transversely spaced embossments 34 separating the first mixing chamber 23 and the distribution chamber 25, and an unbroken transverse embossment 35 which forms a wall separating the distribution chamber and the second mixing chamber 24. The embossments 30 define series of restricted openings 36 which slant from the first mixing chamber 23 toward the passage 26. The embossments 31 define series of restricted openings 37 which slant from the passage 26 toward the second mixing chamber 24. In each instance the openings 36 and 37 slant in the direction of gas flow. The opening between the two embossments 34 is designated 38.
Noises which accompany exhaust gases into the muffler commonly have a noise level of at least 125 decibels and are composed of both high-frequency and low-frequency sound waves. The muffler lowers the noise level to about 80 to 85 decibels, and suppresses undesirable sound wave components. The objective is to produce a characteristic pleasing sound which is distinctive for any particular make and model vehicle. Usually high-frequency sound waves are suppressed to avoid a tinny or metallic sound. However, if high-frequency waves are eliminated together the muffler produces an undesirable hollow sound. The resultant sound output usually sought is a smooth sequence of attenuated low-frequency booms with enough high-frequency sounds to produce a pleasing distinctive tone.
FIG. 3 also shows the pattern which sound waves follow within the muffler shown in FIG. 2. High-frequency waves tend to travel in straight courses. Hence incoming high-frequency waves mostly pass directly through the first mixing chamber 23 and opening 38 into the distribution chamber 25, as indicated by arrows 39. Such waves echo against the embossment 35, which lowers their energy level. The weakened high-frequency waves pass through both sides of chamber 25 into passages 26, as indicated by arrows 40. Low-frequency waves tend to spread sideways. Hence incoming low-frequency waves pass from the first mixing chamber 23 through openings 36 into passages 26, as indicated by arrows 41. The high and low-frequency waves blend within passages 26 and pass through openings 37 into the second mixing chamber 24, as indicated by arrows 42. The final sound output from the muffler of course depends on the relative size and shape of the chambers, passages and openings.
In the modification shown in FIGS. 2 and 3, the low point of the muffler is located near the outlet end to permit condensate to drain thereto. The area around the low point can be specially reinforced to prolong the useful life of the muffler, or the muffler can be equipped with a special drain to carry away condensate from its low point. Another possibility is to locate the low point near a hot part of the muffler so that condensate is revaporized. With my method of construction, I can locate the low point anywhere desired within the muffler.
FIG. 4 shows a two-piece muffler of modified construction in accordance with my invention designed to permit variable tuning. The muffler comprises mating top and bottom pieces 45 and 46, again preferably formed of metal stampings. Indentations in the top piece form a first mixing chamber 47 adjacent the inlet end, a second mixing chamber 48 adjacent the outlet end, a distribution chamber 49 between the two mixing chambers, and a blind chamber 50. A passage 51 affords communication between the first mixing chamber 47 and the distribution chamber 49. Passages 52 and 53 afford communication between the distribution chamber and the second mixing chamber 48 and between the distribution chamber and the blind chamber 50 respectively. The muffler has an inlet 54 formed by indentations in its two pieces, and a similar outlet not shown. The two pieces, although mating, are not necessarily alike, but the bottom piece 46 may provide chambers of other configurations, such as the chamber 55 illustrated. The two pieces have peripheral lips 56 which are joined as in the embodiments already described.
I tune the muffler of FIG. 4 by adjusting the position of the top and bottom pieces 45 and 46 relatively to each other. In the construction illustrated the pieces are arranged for adjustment lengthwise of the muffler, and the top piece carries a scale 57 to indicate the relative position it should occupy for different characteristic sounds. If the muffler is mass-produced, the scale can be used to adjust the pieces to the proper setting for any make of vehicle, thereby permitting standardization. The pieces can be extended at the lips and at the indentations which form the inlet and outlet, and trimmed off flush as shown after they are in their final position of adjustment. With this modification it is possible also to tune the muffler and join the two pieces after the muffler has been installed on a vehicle. This is a particularly desirable feature for replacement mufflers to enable a muffler formed of standardized parts to sound right on any make of vehicle. Although I show two pieces adjustable lengthwise, it is apparent they could be adjustable in other directions, such as transversely or by relative rotation.
FIG. 5 illustrates a preferred way of joining the two pieces of my muffler applicable to nonadjustable forms. The peripheral lips 60 and 61 of this muffler have interfitting indentations 62 and 63. The lower lip 60 has an upstanding flange 64 to provide stiffness. The lower lip 60 has an upstanding flange inner surfaces of the two pieces preferably have a protective coating such as porcelain, which may be applied by dipping or spraying. I interpose a layer 65 of brazing material between the indentations 62 and 63. The brazing material may be brass and may be in powder, strip or rod form. I place the assembled muffler in a porcelain baking oven and fire it. The porcelain acts as a flux and the two pieces are brazed together while they are porcelainized, but if the muffler is not porcelain coated, I can add a suitable flux. I am aware that mufflers have been porcelainized previously, but the porcelain coating could be applied only after the muffler was totally assembled by flowing the porcelain material through the muffler. This is an expensive operation, and did not always produce a uniform coating.
From the foregoing description it is seen that my invention provides a muffler of simple two-piece construction, the individual pieces of which can be formed as inexpensive stampings. The muffler not only has superior corrosion resistance, but is readily tuned to give the noise level and characteristic sound desired for any particular vehicle.