Exhaust gas muffler for internal combustion engines

Information

  • Patent Grant
  • 6422338
  • Patent Number
    6,422,338
  • Date Filed
    Thursday, June 1, 2000
    24 years ago
  • Date Issued
    Tuesday, July 23, 2002
    22 years ago
Abstract
An exhaust gas muffler is provided for an internal combustion engine, especially for two-stroke engines of manually guided implements such as power chain saws, brush cutters or the like. The muffler has a housing that includes two shells. One of the shells is provided with at least one outlet opening for exhaust gas. A cover is provided that guides the exhaust gas, and the cover has at least one discharge opening for the discharge of exhaust gas to the surrounding air. An exhaust gas chamber is formed within the cover. A screen element is disposed in the vicinity of the at least one discharge opening such that the exhaust gas stream is guided through the screen element.
Description




BACKGROUND OF THE INVENTION




The present invention relates to an exhaust gas muffler for internal combustion engines, especially for two-stoke engines of manually guided implements, such as power chain saws, brush cutters or the like. The muffler has a housing that includes at least two shells, wherein one of the shells is provided with at least one outlet opening for the exhaust gas, and whereby a cover is disposed over the at least one outlet opening for guiding the exhaust gas, with at least one discharge opening being provided in the cover for the discharge of the exhaust gas to the surrounding air.




WO 96/25590 discloses an exhaust gas muffler for an internal combustion engine in a portable implement. The exhaust gas muffler essentially comprises two shells that form a housing, with a partition extending between the shells. The partition divides the housing into two chambers, with the exhaust gas flowing out of the internal combustion engine into one of the chambers. Thereafter, the exhaust gas passes into the second chamber within the other shell, and from there the exhaust gas is guided through a tube to an outlet opening that is again disposed in the first shell. By means of this position of the outlet opening, the exhaust gas that exits the exhaust gas muffler is supposed to be mixed as intensively as possible with the cooling air stream of the internal combustion engine that is directed toward the exhaust gas muffler. This results not only in a rapid cooling of the exhaust gas stream, but also a cooling of the exhaust gas muffler, thereby reducing the temperature of the outer surfaces of the muffler. No measures are provided for preventing the discharge of sparks.




DE 25 39 516 A1 discloses an exhaust gas muffler for internal combustion engines for commercial agricultural and forestry implements. Since during operation of the implement the exhaust gas muffler gets very hot, this publication proposes that the wall of the exhaust gas muffler that contains the outlet opening be covered by a dish-shaped wall, with a cooling channel having a nozzle-like narrowed portioned being formed between the wall of the muffler and the covering wall. Adjoining this narrowed portion is a diffuser-like widened portion into which pass the exhaust gases that flow out of the outlet opening, whereupon they are mixed with the cooling air drawn in by the injector effect of the nozzle-like narrowed portion. Again with this arrangement, no measures are taken to prevent the discharge of glowing particles.




U.S. Pat. No. 4,370,855 describes an exhaust gas muffler for internal combustion engines in a manually guided implement, whereby a cover is secured to the outer side, i.e. the side remote from the internal combustion engine; the cover forms cooling channels between itself and the exhaust gas muffler. Disposed within the housing is a diffuser element that is surrounded by a screen that is intended to restrain particles carried along in the exhaust gas stream. The exhaust gas stream exits on that side of the exhaust gas muffler adjacent to the internal combustion engine, whereby the exhaust gas stream, via appropriate deflection, is supplied to the outer side of the exhaust gas muffler. In order to prevent the exhaust gas muffler from being overheated, it is necessary to direct the cooling air stream of the internal combustion engine against the exhaust gas muffler so that this cooling air stream reduces the temperature of the outer side of the muffler housing. With this known arrangement, the screen element must be made of high temperature resistant material since it is disposed in the immediate vicinity of the inlet opening through which the exhaust gases enter the exhaust gas muffler. Thus, the wires that form the screen cannot be as thin as would be desired, so that the mesh width of the screen element is also correspondingly large.




It is an object of the present invention to provide an exhaust gas muffler of the aforementioned general type whereby the discharge of particles along with the exhaust gas stream is significantly reduced.











BRIEF DESCRIPTION OF THE DRAWINGS




This object, and other objects and advantages of the present invention, will appear more clearly from the following specification in conjunction with the accompanying schematic drawings, in which:





FIG. 1

is a longitudinal cross-sectional view through one exemplary embodiment of an inventive exhaust gas muffler;





FIG. 2

is a cross-sectional view taken along the line II—II in

FIG. 1

;





FIG. 3

is a longitudinal cross-sectional view through a modified embodiment of the muffler of FIG.


1


.





FIG. 4

is a view of the exhaust gas muffler of

FIG. 3

taken in the direction of the arrow IV thereof;





FIG. 5

is a partial cross-sectional view taken along the line V—V in

FIG. 4

;





FIG. 6

is a modified embodiment of the portion VI in

FIG. 5

;





FIG. 7

shows a portion of a modified embodiment of the muffler of

FIG. 3







FIGS. 8-10

show various embodiments of the securement of an outer shell;





FIG. 11

shows a modified embodiment of the muffler of

FIG. 7

;





FIG. 12

is a cross-sectional view taken along the line XII—XII in

FIG. 11

; and





FIG. 13

is a modified embodiment of FIG.


12


.




SUMMARY OF THE INVENTION




The exhaust gas muffler of the present invention is characterized primarily in that an exhaust gas chamber is formed within the cover, and in the vicinity of the at least one discharge opening a screen element is disposed such that the exhaust gas stream is guided though the screen element.




During operation of the manually guided implement, the outer side of the cover has a lower temperature than does the housing that is formed from the shells, and the arrangement of the screen element in the immediate vicinity of the discharge opening prevents even small particles contained in the exhaust gas stream from being discharged; furthermore, not only during use but also when the engine is shut down dirt is prevented from passing through the discharge opening into the exhaust gas chamber. By embodying the cover as an extra shell, contact of the exhaust gas muffler itself is prevented; the temperature at the outer shell is significantly reduced, so that combustion or ignition of objects, such as branches or the like, is prevented. With regard to preventing fires, these measures therefore go beyond existing regulations.




Pursuant to one preferred specific embodiment of the present invention, the screen element can rest directly against the inner wall of the cover, so that the cover and the screen element form a common component. With such an embodiment, measures for supporting the screen element against the cover are not required. Pursuant to another embodiment of the invention, the screen element is disposed at a defined, preferably slight distance from the inner wall of the cover, whereby retaining means for supporting the screen element are provided on the inner wall of the cover. The retaining means can in a simple manner be formed by inwardly deformed wall sections of the cover. So that with a fine meshed screen element the resistance to flow for the exhaust gases is not too great, it is expedient to provide the screen element with as large a surface as possible and to provide a plurality of discharge openings. It is therefore expedient for the screen element to extend over at least half of the inner surface of the cover.




Pursuant to a preferred specific embodiment of the present invention, the cover is embodied as an outer shell that at least nearly entirely extends over the shell of the housing having the outlet opening. Since the shells of the housing of the exhaust gas muffler are customarily connected together by means of a flange connection, it is expedient to embody the outer shell in such a way that the rim thereof extends along the flange connection. In this manner, the housing of the exhaust gas muffler is entirely shielded on that side that is remote from the internal combustion engine. Securement of the outer shell to the housing of the exhaust gas muffler can be effected in various ways. For example, the rim of the outer shell can be at least partially formed in such a way that it extends over the flange rim of the housing in a form-fitting manner. Alternatively, holding clamps can be formed on the outer shell or can be placed thereon. In addition, it is possible to secure the outer shell with screws.




To the extent that due to installation conditions of the exhaust gas muffler in the portable implement portions of the housing of the muffler must be protected from contact, a shielding plate can be formed on the outer shell that preferably extends parallel to the contour of the muffler housing. To minimize production expenses, it is advantageous to make the outer shell as a single piece. So that the outer shell will have a great stability, and so that with the influence of force from the outside the volume of the exhaust gas chamber will not be too greatly reduced, a support element is provided in the exhaust gas chamber that extends between the shell of the housing and the outer shell. This support element is preferably embodied as a partition and has an aperture, so that the support element simultaneously serves as a flow distributor. Such a flow distributor is expedient if a plurality of discharge openings are distributed over the surface of the cover, so that rather than a concentrated exhaust gas stream, a more diffused exhaust gas stream is discharged into the surrounding air.




It is furthermore advantageous to provide in the cover at least one inlet opening for cooling air or surrounding air. As a consequence of the exhaust gas stream within the cover, there is generated in the exhaust gas chamber an injector effect via which air is drawn in through the inlet opening for mixing with the exhaust gas stream; this reduces the exhaust gas temperature at the discharge openings.




In addition to the screen element that is disposed within the cover, a spark extinction grid can be provided immediately adjacent to the outlet openings on the shell that forms the housing. Such a spark extinction grid can, for example, be formed by an appropriately dimensioned apertured plate, as a consequence of which the resistance to flow can be kept low. In order to impart to the exhaust gas stream in the exhaust gas chamber a defined direction of flow, it is expedient to form flow guiding elements on the outlet openings, or to provide a cap that extends over the outlet openings and is arched into the exhaust gas chamber; such a cap has apertures that lead into the exhaust gas chamber, whereby the apertures are delimited by flow guiding elements.




Further specific features of the present invention will be described in detail subsequently.











DESCRIPTION OF PREFERRED EMBODIMENTS




Referring now to the drawings in detail,

FIGS. 1 and 2

show an exhaust gas muffler


1


, the housing of which is formed from two sections or shells


2


and


3


, namely the inlet side shell


2


and the outlet side shell


3


. Disposed within the gas exhaust muffler


1


, between the shells


2


and


3


, is a baffle or partition


4


, the outer peripheral edge of which is clamped between the edges of the shells


2


and


3


. Along with the interposition of the peripheral edge of the partition


4


, the shells


2


and


3


are closed off to form a sealed housing by means of a flange connection


6


. Disposed in the partition


4


is a catalytic converter


5


, by means of which an inlet chamber


7


, which is delimited by the partition


4


and the inlet side shell


2


, is connected with an outlet chamber


8


, which is delimited by the partition


4


and the outlet shell


3


. The exhaust gas flows from the inlet chamber


7


, through the catalytic converter


5


, into the outlet chamber


8


. Disposed in the shell


2


is an inlet opening


9


(see FIG.


2


), by means of which the exhaust gas stream coming from the cylinder of the internal combustion engine in the direction of the arrow A passes into the inlet chamber


7


.




Two tubular bodies


10


, which are orthogonally oriented relative to the partition


4


, extend through the inlet chamber


7


and the outlet chamber


8


; due to the cross-sectional illustration in

FIG. 1

, only one of the tubular bodies


10


is visible therein. However, from

FIG. 2

it can be seen that two tubular bodies


10


extend though the exhaust gas muffler


1


. The outlet shell


3


is provided with an inwardly drawn recessed portion


11


, which as can be seen in

FIG. 2

has an elongated shape. Disposed in this recess


11


are a plurality of outlet openings


12


via which the exhaust gas leaves the outlet chamber


8


. A spark extinction grid


13


, which extends over the recessed portion


11


, is inserted between the recessed portion


11


and a hood or cap


14


that extends over the recessed portion


11


with its outlet openings


12


.




A cover


15


, which is in the form of an outer shell, is disposed on the outer side of the shell


3


. This outer shell


15


has a rim


16


that extends on the shell


3


along the flange connection


6


. Formed between the outer shell


15


and the shell


3


is an exhaust gas chamber


17


into which the cap


14


is arched. Openings or apertures


18


are provided in the cap


14


; these apertures are delimited by flow deflecting or guiding elements


19


. In this manner, a main direction of flow is imparted to the exhaust gas stream upon entry thereof into the exhaust gas chamber


17


. Disposed in the outer shell


15


are a plurality of discharge openings


20


,


20


′, whereby the discharge openings


20


are provided in the region of the base of the outer shell


15


, and the discharge openings


20


′ are provided on a side wall.




Disposed on the inner side of the cover


15


, and resting against the inner wall, is a mesh or screen element


30


that extends over a large surface area and covers at least all of the discharge openings


20


,


20


′. In this way, the entire exhaust gas stream, regardless of through which discharge openings


20


,


20


′ it exits the cover


15


, is guided through the screen element


30


.




Provided in the exhaust gas chamber


17


between the shell


3


and the outer shell or cover


15


is a support element


21


that is embodied as a partition having an aperture


22


. Due to the magnitude of the aperture


22


, the element


21


acts as a gas distributor, thus effecting as uniform a distribution as possible of the overall exhaust gas stream to the various discharge openings


20


,


20


′. In addition, provided in the outershell


15


are two inlet openings


23


through which surrounding air can flow into the exhaust gas chamber


17


. As a consequence of the exhaust gas stream that enters the exhaust gas chamber


17


from the apertures


18


, there results an ejector effect by means of which the surrounding air is drawn in through the inlet openings


23


. This drawn-in air is mixed in the exhaust gas chamber


17


with the exhaust gas stream, thereby significantly reducing the temperature of the exhaust gas that is discharged from the openings


20


,


20


′.




As shown in

FIG. 1

, the rim


16


of the outer shell


15


is partially rounded, as indicated by the reference numeral


24


, to form a groove by means of which the outer shell


15


extends about the flange connection


6


in a form-fitting manner. As is visible from the upper portion of

FIG. 1

, the outer shell


15


can be provided with a shielding plate


25


that is formed as an extension of the outer shell


15


. This shielding plate


25


preferably extends parallel to the wall of the housing of the exhaust gas muffler


1


, whereby this outer wall of the shell


2


is provided with a support element


26


against which the shielding plate


25


rests.




As can be seen from

FIG. 2

, the cap


14


and the support element


21


are made of a single piece, which is expedient with respect to reducing the number of individual parts and for facilitating assembly. Formed on the cap


14


is a projection


27


that can be inserted into an opening


28


in the shell


3


. Formed on the other end of the cap


14


is the support element


21


, which has a double-walled construction and via which those portions of the support element that are adjacent to the shell


3


rest thereagainst. Since the support element


21


is inserted between the inner side of the outer shell


15


and the shell


3


, and in addition the projection


27


extends into the opening


28


, not only the cap


14


but also the support element


21


are fixated.





FIG. 3

is a longitudinal cross-section through an exhaust gas muffler


31


that is mounted on an internal combustion engine


29


such that an inlet opening


39


of the muffler is aligned with an exhaust port


29


′ of the internal combustion engine. In a manner similar to that described in conjunction with the embodiment of

FIG. 1

, the exhaust gas muffler


31


comprises two shells


32


,


33


and a partition


34


that is inserted between the shells and carries a catalytic converter


5


. The two shells


32


,


33


accompanied by the interposition of the peripheral edge of the partition


34


, are joined together by means of a flange connection


36


. An inlet chamber


37


and an outlet chamber


38


are formed in the exhaust gas muffler


31


, whereby the exhaust gas can exit from the outlet chamber


38


through outlet openings


42


in a drawn portion


41


of the shell


33


. Disposed on that side of the drawn portion


41


that faces the outlet chamber


38


is a spark extinction grid


45


that is secured to the shell


33


by means of a grid mount


45


′.




A cover


35


, which is embodied as an outer shell, extends over the shell


33


. The peripheral rim


35


′ of the cover


35


rests against the shell


33


, i.e. the flange connection


36


. For this purpose, the outer shell or cover


35


has a rounded portion


46


at its rim


35


′ for accommodating the flange connection


36


. Part of the rim


35


′ is in the shape of a hook


47


that can be brought over the flange connection


36


to span the same, as shown in FIG.


3


. In this way, the outer shell


35


is secured to the housing that is formed of the shells


32


,


33


. The spark extinction grid


45


is disposed in a frame formed by the shell


33


and the grid mount


45


′ and, when the outer shell


35


is removed, can be withdrawn upwardly through a slot in the shell


33


.




In the same manner as described in conjunction with the embodiment of

FIG. 1

, an exhaust gas chamber


17


is formed between the shell


33


and the cover


35


. Disposed in the exhaust gas chamber


17


is a mesh or screen element


50


that extends in front of the discharge openings


40


that are provided in the outer shell


35


. So that the screen element


50


maintains a defined yet slight spacing from the discharge openings


40


, support elements


49


are provided against which the screen element rests. The screen element


50


is, on the one hand, secured to that portion of the rim


35


′ that is formed by the hook


47


, and on the other hand is clamped between a shoulder


43


of the shell


33


and an inwardly directed deformation


44


of the outer shell


45


. So that the tension between the shoulder


43


and the deformation


44


, in other words the clamping effect for the screen element


50


, is also maintained at the temperature changes that occur during operation, additional fastening screws


48


are provided by means of which an appropriate securing force is maintained in this abutment region.





FIG. 4

shows a view of the exhaust gas muffler


31


taken in the direction of the arrow IV in FIG.


3


. As can be seen, the outer shell


35


is provided with a plurality of discharge openings


40


in the form of elongated slots. The reference numerals utilized in

FIG. 4

correspond to those of

FIG. 3

for the same parts.





FIG. 5

shows a partial cross-sectional view taken along the line V—V in FIG.


4


. From this illustration it can be seen that the shape of the screen element


50


corresponds essentially to the contour of the outer shell


35


and that the two components have nearly uniform spacing over their entire length. In order to maintain this spacing, a plurality of the support elements


49


are provided that are expediently formed by inwardly deformed portions of the cover


35


. These support elements


49


can extend, for example, up to 7 or 8 mm into the exhaust gas chamber


17


. A plurality of discharge openings


40


are provided in the cover


35


, and they can be disposed not only in the base portion of the outer shell


35


, but also near the edge, as illustrated in the left side in FIG.


5


.

FIG. 5

also shows that two apertures


42


are provided in the drawn portion


41


, whereby flow guiding elements are provided at the edges thereof for imparting a preferred direction of flow to the exhaust gas stream. On the right side in

FIG. 5

, inlet openings


51


are provided on the cover


35


and have a function that corresponds to that of the inlet openings


23


in FIG.


2


. In other respects, the reference numerals in

FIG. 5

correspond to those of

FIGS. 3 and 4

for the same parts.





FIG. 6

shows a modification of the feature VI in FIG.


5


. In this connection, the grid mount


45


′ is embodied as an apertured plate, whereby the central portion of this plate rests against the spark extinction grid


45


by means of an appropriate arched section. The number of holes of the grid mount


45


′ can be variable, so that the counter-pressure can be determined by the design of the grid mount


45


′.





FIG. 7

shows a portion of a modified embodiment of FIG.


3


. With this arrangement, in contrast to

FIG. 3

, the portion of the shell


33


having the apertures


42


is planar, and no inner spark extinction grid is provided. Next to the apertures


42


the flow guiding element is raised, which in a straightforward manner is formed by a sheet metal strip that is bent out of the shell


33


. With regard to all of the remaining features, with the exception of the concrete shape of the hook


47


, all of the elements correspond with those of

FIG. 3

, so that in order to avoid repetition, reference is made to the description thereof.





FIGS. 8

,


9


and


10


illustrate various possibilities for securing the outer shell


35


to the housing of the exhaust gas muffler. For example,

FIG. 8

shows the securement via screws


48


that extend through the outer shell


35


and are threaded into the shell


33


. With such a fastening arrangement, the rim


35


′ of the outer shell


35


can have a very simple configuration since it needs to merely rest against the shell


33


and no form-fitting connection with the flange rim is required.

FIG. 9

shows an embodiment where the outer shell


3


is provided on its peripheral rim


35


′ with clamps


52


that are formed thereon. These clamps


52


engage around the flange connection


36


and thus hold the outer shell


35


on the housing of the exhaust gas muffler.

FIG. 10

shows an embodiment of the outer shell


35


that is provided with an outwardly flanged rim


53


that rests against the flange connection


36


of the two shells


32


,


33


and is secured by clamps


54


that are placed thereon.





FIG. 11

shows a modified embodiment of

FIG. 7

, with the outlet openings


42


being formed in the shell


33


by stamped-out holes. An outer shell


55


is formed from two shell parts


56


and


57


, with the exhaust gas chamber


17


being provided between these two shell parts. Disposed in the exhaust gas chamber


17


is a mesh or screen element


60


that extends over apertures


58


in the shell part


57


, and that on the inner side of the shell part


56


covers all of the discharge openings


59


.





FIG. 12

shows a cross-section taken along the line XII—XII in FIG.


11


. Here it can be seen that when viewed in the longitudinal direction the screen element


60


has nearly the same shape as does the previously described screen element


50


. Disposed within the exhaust gas chamber


17


are deflection plates


61


for uniformly supplying all of the discharge openings


59


. In other respects, the reference numerals for the same parts correspond with those described in conjunction with FIG.


5


.





FIG. 13

illustrates a modified embodiment of

FIG. 12

, and differs from the already described embodiment in that a spark extinction grid


45


is disposed on the inner side, in other words, in a direction of flow upstream of the apertures


58


.




The specification incorporates by reference the disclosure of German priority document 199 24 888.5 filed Jun. 1, 1999.




The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.



Claims
  • 1. An exhaust gas muffler for an internal combustion engine, especially for a two-stroke engine of a manually guided implement, said muffler comprising:a housing that includes at least two shells, wherein one of said shells is provided with at least one outlet opening for exhaust gas; a cover disposed over said at least one outlet opening for guiding said exhaust gas, wherein at least one discharge opening is provided in said cover for the discharge of said exhaust gas to surrounding air, wherein an exhaust gas chamber is formed within said cover, and wherein said cover is embodied as an outer shell that at least nearly completely extends over said one shell that is provided with said at least one outlet opening; and a screen element disposed in said cover in said vicinity of said at least one discharge opening thereof such that said exhaust gas is guided through said screen element.
  • 2. An exhaust gas muffler according to claim 1, wherein said screen element 30 rests against an inner wall of said cover 15.
  • 3. An exhaust gas muffler according to claim 1, wherein support elements are provided on an inner wall of said cover, and wherein said screen element is supported against said support elements.
  • 4. An exhaust gas muffler according to claim 3, wherein said support elements are in the form of inwardly deformed sections of said cover.
  • 5. An exhaust gas muffler according to claim 1, wherein said screen elements 30,50,60 extends over at least half of an inner surface of said covers 15,35,55 that delimits said exaust gas chamber 17.
  • 6. An exhaust gas muffler according to claim 1, wherein said shells of said housing of said muffler are interconnected by means of a flange connection, and wherein a rim of said outershell extends along said flange connection.
  • 7. An exhaust gas muffler according to claim 6, wherein said rim of said outer shell is at least partially deformed in such a way that it extends over said flange connection in a form-fitting manner, wherein holding clamps are formed on said rim of said outer shell.
  • 8. An exhaust gas muffler according to claim 6, wherein screws are provided for securement of said outer shell.
  • 9. An exhaust gas muffler according to claim 7, wherein said rim of said outer shell is at least partially radially outwardly flanged, and wherein said outer shell is secured to said flange connection of said housing by means of placed-upon clamps.
  • 10. An exhaust gas muffler according to claim 1, wherein at least one shielding plate is formed on said outer shell and preferably extends parallel to a contour of said muffler housing.
  • 11. An exhaust gas muffler according to claim 1, wherein said outer shell is a single piece.
  • 12. An exhaust gas muffler according to claim 1, wherein a support element is provided in said exhaust gas chamber and extends between said one shell of said housing and said outer shell.
  • 13. An exhaust gas muffler according to claim 12, wherein said support element is embodied as a partition having an aperture.
  • 14. An exhaust gas muffler according to claim 12, wherein a cap is provided that is arched into said exhaust gas chamber and extends over said at least one outlet opening, wherein said cap is provided with apertures that lead into said exhaust gas chamber, and wherein flow guiding elements are provided that delimit said apertures.
  • 15. An exhaust gas muffler according to claim 14, wherein said support element 21 and said hood 14 are embodied monolithically and are mechanically secured to said one shell 3.
  • 16. An exhaust gas muffler according to claim 1, wherein a plurality of discharge openings are provided in said cover and are preferably distributed over a portion of the surface of said cover.
  • 17. An exhaust gas muffler according to claim 1, wherein at least one inlet opening is provided in said cover.
  • 18. An exhaust gas muffler according to claim 1, wherein a spark extinction grid is disposed on said one shell 3 that is provided with said at least one outlet opening 12.
  • 19. An exhaust gas muffler according to claim 1, wherein a catalytic converter 5 is disposed in said muffler housing.
  • 20. An exhaust gas muffler for an internal combustion engine, especially for a two-stroke engine of a manually guided implement, said muffler comprising:a housing that includes at least two shells, wherein one of said shells is provided with at least one outlet opening for exhaust gas; a cover disposed over said at least one outlet opening for guiding said exhaust gas, wherein at least one discharge opening is provided in said cover for the discharge of said exhaust gas to surrounding air, and wherein an exhaust gas chamber is formed within said cover, said cover having at least one inlet opening for entry of surrounding air into said exhaust gas chamber; and a screen element disposed in said cover in a vicinity of said at least one discharge opening thereof such that said exhaust gas is guided through said screen element.
  • 21. An exhaust gas muffler according to claim 20, further comprising a spark extinction grid secured to one of said at least two shells by means of a grid mount.
Priority Claims (1)
Number Date Country Kind
199 24 888 Jun 1999 DE
US Referenced Citations (5)
Number Name Date Kind
4324314 Beach et al. Apr 1982 A
4370855 Tuggle Feb 1983 A
4628689 Jourdan Dec 1986 A
5883342 Wolpert Mar 1999 A
5996732 Burger et al. Dec 1999 A
Foreign Referenced Citations (2)
Number Date Country
DE 25 39 516 Sep 1975 DE
WO 9625590 Aug 1996 WO