WO2006087623A1

WO2006087623A1 - Gas flow muffler

Info

Publication number: WO2006087623A1
Application number: PCT/IB2006/000311
Authority: WO
Inventors: Oliver Weiss
Original assignee: Itw-Befestigungssysteme Gmbh
Priority date: 2005-02-17
Filing date: 2006-02-16
Publication date: 2006-08-24
Also published as: DE102005007290B3

Abstract

Gas flow muffler for arranging over a waste gas discharge aperture (3), in particular of a gas-operated appliance such as a hand tool, the gas flow muffler comprising a hood (5) with a plurality of fibres or wires (10) which are attached to one end of the hood and which can be displaced by the streaming in of waste gas and which are parallel to or at an angle to the inflow direction of the waste gas, the hood comprising at least one gas outlet aperture (8) at an angle to, preferably transverse to, the inflow direction of the waste gas.

Description

Gas flow silencer

The invention relates to a gas flow muffler for arranging over a Abgasausströmöffnung in particular a gas-powered device of a hand tool.

Gas flow mufflers are known in a variety of constructive forms corresponding to the wide range of possible applications. Conventional gas flow silencers, which offer good sound damping properties over a relatively large frequency range, however, are relatively large and complex. For a variety of applications, for example, in connection with hand tools such as hand-held driving tools for nails and staples or the like, they are therefore only partially suitable. Another problem with known dampers is that they can become clogged up relatively quickly and therefore have to be cleaned in relatively short intervals. As a result, the damping is influenced and thus also the function of the object to be damped, so for example a gas-powered hand tool or the like.

A resonant damper is known in which the body of a system capable of oscillating is excited by the exhaust gas to resonate. This creates resonances, whereby specific frequencies can be selectively damped. Also known is a Reflexioπsdämpfer, which consists essentially of different sized chambers, which communicate with each other by pipes or channels. In addition, absorptiσnsdämpfer are known in which filler material such as rock wool is included. Finally, interference dampers have already been proposed in which the exhaust gas flow is divided and re-embossed according to different long distances, whereby mutually distinct sound waves cancel each other partially.

All these measures are associated with conventional dampers, especially when these sound-reducing principles are used in combination, with a relatively large and complex design of the damper. Especially in the case of pneumatically operated hand tools, the sound can be due to the limited device size to a satisfactory extent, so that there is still the need for a suitable gas flow muffler in particular, but not exclusively for these applications.

In such pneumatically operated hand tools, for example in the form of compressed air and Eiπtreibwerkzeugeπ such Treiblad ungsbetriebenen bolt drivers or propellant operated nail or staplers arise during operation exhaust air, to avoid power and / or speed reduction, are delivered almost abruptly and unhindered to the environment got to. This typical pulse-like discharge of the gas (even with a frequency-dependent duration of about 0.01-1 second) causes a considerable noise pollution and health hazard for the user and his environment.

In particular, for such gas or pneumatic hand tools has also been provided an air shield damper, in which a wire mesh is arranged in a chamber which is to dampen the flow of exhaust air and the sound stronger. It has been shown that the damping can be improved, but by cooling the air to low temperatures are achieved, so that deposits on the MetaHdrahtgewirr ice, which after a relatively short operating time of the pneumatic tool to a complete blockage and thus inoperability of the device.

The invention is therefore an object of the invention to provide a gas flow muffler, which allows for simple and reliable construction effective reduction of noise pollution by the particular abrupt ejection of the exhaust gas.

In order to solve this problem, it is provided according to the invention that the gas strut silencer has a hood with a plurality of fibers or wires which are fixed at one end to the hood and can be deflected by inflowing exhaust gas, which are parallel or at an angle to the exhaust gas inflow direction Hood has at least one gas outlet opening lying at an angle, preferably transversely to the direction of the exhaust gas inlet. The provision according to the invention of the movable, deflectable fibers or wires, which in the case of the fibers may preferably be made of plastic, in the case of metal wires and slightly resilient, surprisingly results in excellent sound damping by forcing a plurality of deflections and / or braking of the Sound-causing gas jet or stream achieved, with the disadvantages, as they have occurred with rigid wire mesh, do not occur here. The fibers or wires are preferably arranged in the form of spaced bundles with a relatively dense fiber or wire packing within a bundle. The fibers or wires or the bundles can all be arranged essentially in a common preferred direction, that is, they are all preferably, for example, parallel to one another and, for example, parallel to the exhaust gas inlet direction. It is also conceivable, however, for the preferred direction to change over the hood area over which the fibers or wires or the bundles are distributed. For example, the fibers, wires or bundles can all be positioned orthogonal to the hood inner surface, or have any other angle to one another and thus also to the exhaust gas inflow direction. In any case, they have in common that they are fixed at one end to the hood, while the other end, which allows for readability, is free.

The spacing of the fibers or wires or bundles preferably arranged in radial rings preferably decreases from the inside to the outside as seen in the radial outflow direction, with the adjacent fibers or wires or bundles being able to interlock at least in the region of their ends, so that at least in the region The free, flexible ends results in a dense, but movable braid.

The concentric and relatively dense arrangement of the preferably bundled, ausleπkbaren and thus quasi-elastic fibers leads to reflection effects (the total reflection of all, for example, 14,000 fibers, which may be provided in a serving for a hand tool such as a pneumatic driving device hood corresponds to about a square of 40 cm edge length T / IB2006 / 000311

The exhaust gas or air flow is harmonized by the reduction in pressure differences in its outflow. The residence time of the exhaust gas or air volume in the silencer is thereby increased and due to the deflection to the gas outlet opening, which is preferably positioned radially to the exhaust gas inlet direction so that the expulsion of the exhaust or air volume necessary for the cycle is prolonged in time depending on the pressure difference level. However, the function is not adversely affected because the fibers due to their elasticity and flexibility dynamically re-adjust to any pressure difference height. The overflow from one ring volume to the other with concentric bundle arrangement in each case in the radial outflow direction takes place partly by the spaces between the bundles, resulting from the Beabstanduπg the fiber or wire bundles, on the other hand by the lateral Ausleπkung the fibers and thus the lifting from the device or tool housing surface lying opposite the fibers and the additionally opening cross-section. The damping mechanisms listed below are improved by the extension of the residence time in their effectiveness. The pressure at the outlet opening is reduced, pressure peaks are smoothed Through this differential pressure reduction, the airborne sound broadband in its frequency is shifted to a "more comfortable" for human hearing and measurably significantly reduced.

Reducing the air velocity at the hood outlet increases user comfort by reducing dust or sawdust. A sharp exhaust or exhaust air jet with a strong pressure difference would indeed transport the airborne sound away from the device, but in some circumstances towards a person standing next to the user.

With the inventive division of the elastic fiber or wires in a plurality of beabstand eten, in itself tightly packed fiber bundles of the above-mentioned asymmetrical division of the bundle or Bürstenanordπung will _¬ fundamentally made entirely different channels. The main air flow is thereby divided into individual air streams with different lengths and winding paths to the outlet. A time-delayed arrival at the outlet, ie the gas Austrittsöffπung, - it's not all around the hood an air outlet possible, but only in a limited peripheral area - is made possible. The sound waves attenuate by resonances and interference that flexionsflächen to the Re ^¬ (fiber bundles damper inside, tool housing surface) of the individual air currents occur when meeting.

However, the distances of the brushes are chosen so that different sized annular areas remain free, so as to create different resonance spaces. If the ends of the fibers or wires or bundles engage in one another, the free spaces are limited towards the interior of the hood.

In the gas flow ^muffler according to the invention, the absorption ^¬ principle is used by moving in the air flow brush fibers. The case caused Schwϊngbewegungen of the individual fibers and fiber bundles whoever causes ^¬ ^¬ the chaotic detaching in detail by itself laminar boundary layers and induced eddy. The generation of the vortex "consumes" sound energy by converting it into heat.

It is expedient if the fibers or wires profiled, in particular corrugated. A structuring to increase the surface is also advantageous, and this structuring can be produced by any desired thermal, chemical or mechanical methods in the context of fiber or wire production or bundling. For example, the surface can be artificially roughened or otherwise rendered as uneven.

It is expedient, furthermore, if the area of the hood, the position in the Moπtage- is located immediately above the Gasaustrittsöffπung, free of fibers and Dräh ^¬ th is, so that the inflowing exhaust air first hits the hood ceiling, where it is distributed and into the fiber - or Drahtεtruktur occurs and set the unterschiedli ^¬ Chen physical Dämpf ungsphäπomene.

A particularly advantageous development of the invention provides for the hood to be equipped with the at least one, which is only limited over a limited circumferential angle. 0311

ckenden gas outlet opening in the mounting position to perform rotatably adjustable about its center axis. This allows the user to arbitrarily set the air outlet in a direction in which neither he nor a bystander or other environment parts can be disturbed by the blown gas. Alternatively to Verdrehausführung the entire hood, it is also conceivable that the hood has a ring on which the at least one gas outlet opening is provided, and which is rotatably adjustable about the center axis of the hood in the mounting position. In the assembled state so the hood is rotationally fixed, the adjustment of the air outlet direction via the ring, which can be easily rotated about the hood center axis. Regardless of whether the hood or the ring is rotatably adjustable, the hood or ring in any case is close to the tool housing or the like.

In addition to the possibility to perform the gas outlet opening in the form of closely adjacent holes, it is possible to perform the outlet opening in the form of a Schlstzausnehmung otherwise on the WerkΣeuggehäuse or the like sealingly seated hood or the ring.

For easy attachment of the gas flow muffler hood center is preferably a receptacle for a hood passing through fastening means, in particular a screw provided by means of which the gas flow muffler to a exhaust gas outlet having the object, in particular the gasge _¬ driven device is fastened. This fastener, so for example, the screw, then forms the axis of rotation for the optionally drehverstellbare hood or the ring. In any case, this is a simple attachment of the muffler possible.

The innovative use of the movable, quasi-elastic fiber bundles for gas flow sound damping also enables the system to have a self-cleaning effect. The relatively open structure, the main flow direction of the exhaust air towards the fiber ends and outlet opening, thus cleans the system every working cycle. The constant movement of the fibers supports the cleaning gungsproΣess. Clogging as with filter dampers by dirt and ice is therefore no longer possible. The use of this Dämpfuπgssystems is therefore possible in countries with harsh environmental conditions. By maintaining the Auslassöffnungsquerschnitts necessary for the function of the compressed air tool backflow behavior is adversely affected at any cycle time. The function and performance of the compressed air tool are fully maintained over the entire period of use, unlike conventional gas flow silencers.

The flexibility of the damping material (fibers, wires) allows the use of the gas flow muffler on various hand tools without geometric variation of the damper or the tool. The tools must therefore not be structurally changed to use the gas flow muffler, if necessary, only provide a corresponding Befestigungsaufπahme for the damper side fastener. The standard justice remains in any case preserved, costly inspections omitted. The geometry and position of the damper on the outside of the tool allows easy and cost-effective installation.

However, a use of such a damper is not limited to hand tools as already stated. Rather, the damper can also be used wherever exhaust sound is emitted, especially where it is delivered cyclically. To mention here are, for example, power and Arbeitsmaschiπen or valves and the like.

In addition to the gas flow muffler itself, the invention relates to a gas-powered device, in particular a pneumatic hand tool, comprising a gas flow muffler of the type described above. It is expedient if a receptacle, in particular a threaded bore, for receiving a fastener provided on the gas flow muffler to the device in the region of the exhaust port , in particular a screw is provided. Further advantages, features and details of the invention will become apparent from the following description of an embodiment and with reference to the drawings. Showing:

1 is a partially sectioned side view of the tool housing part of a pneumatic hand tool with attached erfindungs ^¬ according gas flow muffler,

2 is a side view of a modified Gasaustrittsrϊng,

_Rg, 3 an exploded perspective view of the tool housing portion and the end portions of the gas flow sound ^¬ damper according to the invention,

Fig. 4 is a bottom view of the hood of the gas flow ^¬ muffler according to the invention.

Fig. 5 is a section through the hood of Fig. 4, and

Fig. 6 is a partial view of a erfinduπgsgemäßen gas flow muffler to illustrate another preferred orientation of the fiber or wire bundle.

Fig. 1 shows the end 1 of the tool housing part 2 of a pneumatic hand tool, such as a Druckluftnagelgeräts. For the Luftaustritts ^¬ seteil 2 is shown for the Luftaustrittsöffnungeπ 3 (in section, only one Austrittsöff- nuπg shown) the Deckenπwand 4 an inventive gas flow muffler with its hood 5 by means of a fastener in the form of a screw 6, in a corresponding internal thread, the is formed on the ceiling wall 4, is screwed. The gas flow muffler has a drehba ^¬ ren ring 7, which is supported on the hood 5, on which ring 7 is pressed against the de ^¬ ckenwand 4 and thus relatively tightly seated on this. The ring 7 is formed with respect to the center axis, via the Befestiguπgselement in Form of the screw 6, vertically extending Gasaustrittsöffπung provided in the form of an air outlet slot 8. The hood 5 is provided for Halteruπg of the ring 7 with a molded shoulder 9 and is preferably made of plastic, if a Kunststoffausführuπg in terms of exhaust gas temperatures is appropriate. On the inside of the hood 5, a plurality of bristle or Drahtbündeϊπ 10 (spring wire bundle) is arranged from each closely packed elastic fibers or wires, wherein the fibers or wires or bundles 10 are fixed with one end in the hood, but otherwise free are arranged in the overlapped by the hood 5 space, so therefore are movable with their free length. The bundles 10 are substantially parallel to the axis 11 of the hood or the tool housing cover and thus substantially parallel to the gas outlet direction of the or the gas outlet openings 3. All bundles 10 have the same preferred direction with respect to their hood-like arrangement and location in space. Since the surface of the fibers or wires has a significant Eiπfluss on the sound attenuation performance, it is advantageous if the wires or fibers are coated or pretreated, or profiled, for example, are corrugated.

The two superposed annular elevations 12a on the hood 5 and 12b on the ceiling wall 4 surrounding space of the hood 5 above the air outlet openings 3, as shown in FIG. 1, largely free of fiber or wire bundles 1 O ₁ wherein the bundles, such 4 can be seen, are preferably arranged in circular ring structures which are offset from one another and wherein the package is inside less dense than outside.

Fig. 2 shows a ring 7 \ in which instead of a gas outlet opening forming slot 8, a group of holes 8 'is provided for the exit of the damped and multiply reflected and deflected air. The ring 7 or T is about the axis 11 of the hood 5, as defined by the screw 6, rotatable with respect to the fixed hood and the tool housing cover, so that only about a part of the ring circumference extending gas outlet opening of any shape in any Move position. Fig. 3 shows in the form of an exploded view of the tool housing cover 2, in which case the elevation 12b is clearly visible with the internal thread. In this internal thread, the screw 6 is screwed. To mount the ring 7, which has a relatively long Gasaustrittsöffnuπg 8 shown here, attached to the hood 5 edge, after which the screw 6 is inserted through the hollow elevation 12a and is screwed into the internal thread of the elevation 12b.

4 and 5 show the arrangement of the mounting holes 13, in which the fiber or wire bundles 10 are used. As can be seen, these are all parallel to one another, by means of which the direction of advance of the bundles is defined.

Another arrangement of the bundles shows the Teilanβicht in Fig. 6. There are on the hood 5 ', the support holes 13' in which the fiber or wire bundles 10 'are added, not parallel, but the angle α to the axis 11' of inside out. As can be seen, the outer bundle 10 'is much more tilted to the axis 11' than an inner one. An Altemativanordnung could also be such that the Halteruπgsbohrungen are always perpendicular to the inner wall of the hood, so that the individual bundles with their free ends almost run towards each other. Basically, the bundles can be so long or run so that they interlock with their free ends. They are then spaced apart from each other only in the upper, hood-like area, where forms a corresponding gap.

Functionally, the exhaust gas, for example air, flows in accordance with the exhaust gas inflow direction, which is parallel to the axis 11, via the cover wall-side exhaust opening 3 into the hood, where it is strongly swirled and where as a result of Verwirbelung or inflowing exhaust air, the fibers or wires or the bundles are moved. The air outlet then takes place perpendicular to the Abgasenϊntrörnrichtung due to the Ausrich _¬ tion of the slots or holes 8 and 8 '. The air flow is interrupted completely randomly, it form completely different flow channels, which also change continuously due to the continuous movement of the fibers or wires. The main air flow is divided into a large number of individual air flows with different divided by long and winding paths to the outlet, which sets a remarkable sound attenuation.

Claims

claims

1. gas flow muffler for arranging over a Abgasausströrnöffnuπg particular of a gasgetriebeneπ device such as a hand tool, characterized in that the gas flow muffler a hood (5, 5 ') with a plurality of one end to the hood (5, 5') fixed by inflowing Exhaust deflectable fibers or wires (10, 10 ^' ) which are parallel or at an angle to the exhaust gas inlet, said hood (5, 5 ") at least one at an angle, preferably transverse to Abgaseiπstrσmrichtuπg Hegende gas outlet opening (S, 8 ^r ) having

2. gas flow muffler according to claim 1, characterized in that the fibers or wires in the form beabstaπdeter bundles (10, 10 ') are arranged.

3. gas flow muffler according to claim 1 or 2 _S characterized in that the fibers or wires or the bundles (10, 10 ^* ) are all arranged substantially in a common preferred direction, or that the preferred direction over the hood surface over which the fibers or Wires or the bundles (10, 10 ^' ) are arranged changes.

4. gas flow muffler according to one of the preceding claims, characterized in that the distance of the fibers or wires, optionally the bundle (10, 10 ') seen in the radial outflow direction decreases from the inside to the outside.

5. gas flow muffler according to one of the preceding claims, characterized in that adjacent fibers or wires or bundles (10, 10 ') at least in the region of their ends engage with each other.

6. gas flow muffler according to one of the preceding claims, characterized in that the fibers or wires profiled, in particular are corrugated.

7. Gastrornschaildämpfer according to any one of the preceding claims, characterized in that the fibers or wires are structured to increase the surface.

8. gas flow muffler according to one of the preceding claims, characterized in that the region of the hood (5, 5 ^" ), which is in the assembly day directly above the gas outlet opening (3), is free of fibers or wires.

9. gas flow muffler according to one of the preceding claims, characterized in that the hood with the at least one, extending only over a limited circumferential angle gas outlet opening in the mounting position about its central axis is rotationally adjustable.

10. gas flow muffler according to one of claims 1 to 8, characterized in that the hood (5, 5 ') has a ring (7, 7'), on which the at least one gas outlet opening (8, 8 ') is provided, and the about the center axis (11, 11 ') of the hood (5, 5') in the assembly position is rotationally adjustable.

11. Gas flow muffler according to one of the preceding claims, characterized in that the at least one gas outlet opening (8 ') is formed in the form of closely spaced holes.

12. gas flow muffler according to one of claims 1 to 10, characterized in that the gas outlet opening (8) is designed as a slot recess.

13. Gas flow muffler according to one of the preceding claims, characterized in that the center of the hood a receptacle for the hood (5, 5 ') passing through fastening means, in particular a screw (6), is provided, by means of which the gas flow muffler at a Abgasöffπung having Object (2), in particular a gas-powered device can be fastened

14. Gas-driven device, in particular hand tool, comprising a gas flow muffler according to efnem of claims 1 to 13.

15. Gas-driven device according to claim 14, characterized in that in the region of the exhaust opening (3) is provided a receptacle (12b), in particular a threaded bore, for receiving a provided on the gas flow muffler Befestigungsiguπgsmittels, in particular a screw (6).