An exhaust-gas muffler (1) has a housing (2) through which at least one sleeve (11) projects. At one end, the sleeve (11) has an attachment opening (10) and at the opposite-lying end has an access opening (14). To avoid a contamination of the sleeve (11) during operation, a plug (15, 25, 35, 40, 45, 55) of a pressed metal wire is arranged in the access opening (14).

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority of German patent application no. 10 2008 026 333.8, filed May 31, 2008, the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to an exhaust-gas muffler having a housing through which at least one sleeve projects. The sleeve has an attachment opening at one end and, at the opposite-lying end, the sleeve has an access opening.

BACKGROUND OF THE INVENTION

For attaching an exhaust-gas muffler to the cylinder of an internal combustion engine it is known to provide one or several sleeves which project through the entire muffler housing and to arrange attachment elements at the base facing toward the cylinder, for example, attachment screws with which the exhaust-gas muffler can be fastened to the cylinder of the engine. The sleeves make the use of short attachment screws possible.

Dirt can collect in the sleeves during operation of the engine. To avoid this, cover caps of metal are known with which the sleeves can be closed off on the outside of the muffler. These cover caps are usually tightly clamped into the sleeves. These cover caps can loosen because of the high temperatures during operation and because of vibrations and the like. To disassemble the exhaust-gas muffler, the cover caps must first be removed so that the attachment elements are accessible.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an exhaust-gas muffler of the type described above wherein a contamination of the sleeves of the exhaust-gas muffler is avoided in a simple manner.

The exhaust-gas muffler of the invention includes: a housing; at least one sleeve extending through the housing; the sleeve having a first end defining an attachment opening and a second end lying opposite the first end and the second end defining an access opening; a plug made of pressed metal wire; and, the plug being disposed in the access opening.

In lieu of the known covers for closing the sleeves, it is suggested that a plug be provided which is arranged in the access opening. The plug comprises pressed metal wire. The metal wire is placed in irregular loops and is pressed into plug form. In this way, a flexible element having a very large surface is provided.

Advantageously, the plug has a cylindrical section which is braced against the inner wall of the sleeve. The plug is especially pressed into the sleeve. The plug is therefore held in the sleeve because of its inherent elasticity. The metal loops on the outer side of the cylindrical section of the plug touch the inner wall of the sleeve. These touching locations form a point contact or line contact directly after assembly. During operation, vibrations and the high temperatures of the muffler lead, in this region, to the smallest relative movements between the metal loops and the inner wall of the sleeve at each touching location. These relative movements cause microscopically small wear and contact corrosion at the touching locations. Because of the multiplicity of the wear marks and corrosion particles, a tight form and friction connection is achieved between the plug and the sleeve.

In this way, the plug is reliably held in the sleeve in all operating states. Directly after pressing the plug into the sleeve, the plug is held less tight than after a certain operating time because of the wear marks and the corrosion particles. Additional attachment means for the plug can be omitted.

Advantageously, the plug has a conical section at the end thereof projecting into the sleeve whereat the plug tapers. In this way, the insertion of the plug into the sleeve during assembly is facilitated. Because of the conical section, the cylindrical section of the plug is shortened so that, overall, an increased elasticity results. It is practical that a plug have a chamfer at its end facing away from the attachment opening. The chamfer too increases the elasticity of the plug at the end of the plug arranged at the outside of the exhaust-gas muffler. Because of the chamfer, projecting edges of the plug, which result when the plug is not pushed completely into the sleeve, can be avoided.

Advantageously, the plug has a through opening. Because of the through opening, the plug closes the access opening only partially. Here, it is especially provided that the exhaust-gas muffler has an attachment element arranged in the sleeve which extends through the attachment opening and is accessible through the through opening. In this way, the plug need not be disassembled for loosening or fixing the attachment element, for example, for maintenance purposes. The plug can remain in the access opening. The work tool, such as a screw driver or the like, is used to loosen or fix the attachment element. This work tool usually has a significantly lesser outer diameter than the head of the attachment element and the inner diameter of the sleeve. In this way, a through opening in the plug, which is significantly smaller than the head of the attachment element, is sufficient in order to make possible a loosening or fixing of the attachment element after assembly of the attachment element in the sleeve. A contamination of the sleeve is substantially avoided because of the significantly reduced diameter of the through opening.

Advantageously, the plug has a resilient section which at least partially closes the through opening. The resilient section can be pressed away by the work tool to loosen or fix the attachment element so that the attachment element is accessible. After loosening or fixing the attachment element, the work tool is guided out of the sleeve and the plug so that the resilient section can spring back and the through opening can at least again be partially closed. In this way, and in a simple manner, the access opening is closed during operation and a contamination of the sleeve is avoided and, simultaneously, the attachment element is accessible for a work tool. The resilient section is advantageously arranged at the end of the plug projecting into the sleeve. A simple configuration results when the resilient section is formed by individual wire loops. The resilient section can thereby be formed by a special arrangement of the metal wire in the region of the resilient section. The wire loops are advantageously aligned in the resilient section in one direction and are not connected to each other in the peripheral direction. A resilient expansion is made possible because of the inherent elasticity of the wire.

It can also be advantageous that the through opening is closed with a closing stopper. To loosen or fix the attachment element, the closing stopper can be removed so that the attachment element is accessible via the through opening. Because of the reduced temperature in the interior of the plug, the closing stopper does not bake together with the plug so that the accessibility of the through opening is ensured. The closing stopper is advantageously arranged at the end of the plug facing away from the attachment opening. Advantageously, the closing stopper has a cylindrical section which projects into the through opening. In this way, and in a simple manner, a fixing of the closing stopper in the plug is achieved. The closing stopper has an edge whose outer diameter is greater than the inner diameter of the through opening. In this way, it can be ensured that the closing stopper cannot be pushed completely into the plug which would make a disassembly of the closing stopper more difficult. The edge of the closing stopper projects beyond the plug so that the closing stopper can be pulled at the edge from the plug.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The exhaust-gas muffler1shown inFIG. 1can, for example, be an exhaust-gas muffler in a portable handheld work apparatus such as a motor-driven chain saw, cutoff machine, brushcutter or the like. The exhaust-gas muffler1has a housing2into which an inlet3leads. The inlet3is connected to the outlet from an internal combustion engine, for example, a two-stroke engine or a mixture-lubricated four-stroke engine. In the interior of the housing2, an exhaust-gas spray nozzle4is arranged next to the inlet3and this spray nozzle leads to a good attenuation of noise. The housing2is made up of a first half shell5and a second half shell6which are connected gas tight to each other at an edge7. The first half shell5has the inlet3and is advantageously arranged facing toward an internal combustion engine. An outlet (not shown) leads from the housing2and is covered by an outlet cover or hood8. A stiffening sheet metal member9is arranged in the interior of the first half shell5and is arranged on the side facing toward the internal combustion engine and has an opening for the inlet3into the housing2.

Attachment screws12are provided for fixing the exhaust-gas muffler1on the outlet of an internal combustion engine and one of the attachment screws12is shown inFIG. 1. The attachment screws12are arranged next to the inlet3and extend through attachment openings10of the exhaust-gas muffler1. The attachment openings10are configured as passthrough openings through the first half shell5, the reinforcement sheet metal piece member9as well as the base13of the sleeves11. In the embodiment, two sleeves11are provided which pass through the housing2of the exhaust-gas muffler1and extend from the side of the housing2, which lies opposite to the inlet3, up to next to the reinforcement sheet metal member9. The sleeves11are configured closed to the interior space of the housing2. The head of the attachment screw12can lie on the base13of the sleeve11and so fix the exhaust-gas muffler1to a cylinder of an internal combustion engine.

To assemble the attachment screws12in the sleeves11, the sleeves11each have an access opening14on the side lying opposite the base13. The access opening14connects the interior of the sleeve11to the ambient. The attachment screws12can be arranged in the attachment openings10via the access openings14. A tool can be introduced and led to the attachment screws12via the access openings14and, with this tool, the attachment screws12can be fixed or released.

A plug15is arranged in the sleeve11in the region of the access opening14to prevent a contamination of the interior of the sleeve11. This is shown by way of example inFIG. 1for one of the two sleeves11. The plug15comprises a metal wire22which is arranged in non-uniform loops21and is pressed into the shape of a plug shown inFIG. 1. The plug is permeable to air so that the sleeve11is not closed off seal tight to the ambient.FIG. 20is a perspective enlarged view of plug15clearly showing the non-uniform loops making up the plug. The wire is made of high-grade steel and has a diameter of 0.23 mm; however, the high-grade steel can have a diameter lying in the range of 0.1 mm to 1 mm.

InFIG. 19, the build-up with metal wire loops21is shown by way of example for a plug55. The other plugs shown are built up in a corresponding manner and, to simplify the illustration in the drawings, the plug is, however, shown by hatching. As shown inFIG. 19, air can pass between the individual metal wire loops21because of the intermediate spaces shown between the loops21. The flow of air is indicated by arrow61.

The metal wire22has a high thermal stability. Because of the local contacts of the plug with the sleeve11at individual metal wire loops21as shown inFIGS. 1 and 2, the plug15is fixed in the sleeve11at the high temperatures during operation and because of wear via wear marks and corrosion particles so that the plug15is held tightly in the sleeve11. The wear is generated by vibrations. The plug15is advantageously pressed into the sleeve11and is first held in the sleeve11by its inherent elasticity.

In order to ensure a reliable seating of the plug15in the sleeve11, the outer diameter (a) of the plug15(seeFIG. 4) corresponds at least to the inner diameter (b) of the sleeve11shown inFIG. 1. Advantageously, the outer diameter (a) is somewhat greater than the inner diameter (b) so that the plug15is braced in the sleeve11.

AsFIGS. 3 and 4show, the plug15has a cylindrical section18which extends into a conical section19. The conical section19projects into the sleeve11in the direction toward the base13. At the conical section19, the outer diameter (a) tapers to a lesser diameter. The conical section19is configured to be flat at its end projecting into the interior of the sleeve11.

AsFIG. 2shows, the sleeve11has an outwardly projecting fold16in the region of the access opening14whereat the second half shell6lies in contact engagement. The sleeve11is bent over outwardly to edge17outside of the second half shell6so that the second half shell6is held between the fold16and the edge17. In this way, a gas-tight connection is provided between the sleeve11and the second half shell6. A recess20is formed in the sleeve11in the region of the fold16and the plug15is pressed partially into this recess20. In this way, a form-tight fixation of the plug15in the sleeve11is obtained. To loosen the attachment screw12, the plug15must be removed from the sleeve11or a corresponding opening must be introduced into the plug15.

FIGS. 5 and 6show an embodiment of a plug25whose configuration corresponds essentially to that of plug15. In addition to the cylindrical section18and the conical section19, the plug25has a chamfer26on the side facing away from the conical section19and projecting on the outer side of the exhaust-gas muffler1.

FIGS. 8 to 11show an embodiment of a plug35. The plug35likewise has a cylindrical section18from which a conical section19extends. In addition, the chamfer26, which is shown inFIGS. 5 to 7, can be provided. AsFIGS. 8 to 11show, the plug35has a through opening36whose inner diameter (c) is less than the inner diameter (b) of the sleeve11and the outer diameter (a) of the cylindrical section18. The inner diameter (c) advantageously corresponds to the outer diameter of a work tool which is needed to tighten or loosen the attachment screw12. The attachment screw12is accessible for a work tool through the through opening36so that the plug35can remain in the access opening14when the exhaust-gas muffler1is, for example, loosened from the cylinder or is tightened thereon. The inner diameter (c) is advantageously less than the head of an attachment screw12so that the attachment screw12is held in the sleeve11so as not to separate therefrom.

FIG. 12shows an embodiment of a plug40which has a through opening41. The through opening41has an inner diameter (c). The plug40differs from the plug35by a shortened cylindrical section18. AsFIGS. 14 and 15show, a spring section42extends from the cylindrical section18whereat the plug40tapers to a point in the embodiment. The spring section42is so configured that a widening in the direction of the arrows50is possible when, for example, a work tool is pushed through the through opening41. In the position shown inFIG. 15, the spring section42substantially closes the through opening41. In this way, the sleeve11is closed during operation so that the sleeve11cannot become contaminated. For maintenance purposes, a work tool can be pushed through the through opening41which widens the spring section42and so makes possible access to the interior of the sleeve11and to the attachment screw12. After removing the work tool, the spring sections42again move toward each other so that the through opening41is essentially closed by the spring sections42.

FIG. 13shows an embodiment of a plug45which likewise has a shortened cylindrical section18. The plug45, however, has no through opening. As shown inFIG. 16, the plug45has a conical section46whereat the plug45tapers to a tip.

As shown inFIG. 17, a closing stopper43can be additionally arranged in the plug40and this closing stopper projects from the outer side into the through opening41. The closing stopper43has a cylindrical section38which is arranged in the through opening41as well as an edge37. The edge37has an outer diameter (e) which is significantly greater than the inner diameter (c) of the through opening41. In this way, it is ensured that the edge37lies against the end face of the plug40. At the edge37, the closing stopper43can easily be removed from the through opening41when access is needed to the attachment screw12.

As shown inFIG. 17, the cylindrical section38has an outer diameter (d) which corresponds approximately to the inner diameter (c) of the through opening41. Advantageously, the outer diameter (d) is slightly greater than the inner diameter (c) when the closing stopper43is not mounted in the through opening41so that the closing stopper43is pressed into the through opening41. A profile39is provided at the outer end of the cylindrical section38. The profile39leads to a better fixation of the closing stopper43in the through opening41. The closing stopper43can likewise comprise a pressed metal wire; however, other materials can also advantageously be used for the closing stopper43. For example, the closing stopper43can consist of solid material such as metal.

InFIG. 18, an embodiment of a closing stopper44is shown which can be arranged in the through opening41. The closing stopper44has an edge47which likewise has an outer diameter (e) which is significantly greater than the inner diameter (c) of the through opening41. The edge47of the closing stopper44is configured to be slightly arcuate so that the edge47lies against the end face of the plug40. The closing stopper44has a cylindrical section48which projects into the through opening41and has a profile49which is configured to be greater than the profile39of the closing stopper43. The cylindrical section48likewise has an outer diameter (d) which is advantageously slightly greater than the inner diameter (c) of the through opening41in the non-assembled state of the closing stopper44. Closing stoppers (43,44) can be advantageous for plug40having a spring section42as well as for plug35wherein the through opening36is configured to be open.

FIG. 19shows an embodiment of a plug55which has a cylindrical section58and a conical section59. A spring section62extends from the conical section59and this section62is configured by individual wire loops60. The wire loops60are pretensioned radially inwardly in the direction toward the through opening41. The wire loops60are each connected at their ends to the conical section59so that the wire loops60are not connected directly to each other in the peripheral direction. In this way, an expansion of the spring section62is made possible in a simple manner. The spring section42of the plug40can be correspondingly configured. The entire plug is built up of metal wire22which is placed or laid in loops21and which define the wire loops60. The arrow61shown with a broken line indicates the air permeability of the plug55.