EP1395743B1 - Silencer - Google Patents

Abstract

The invention relates to a silencer (1) for noise-laden gas pipes, especially for a suction pipe and/or an exhaust pipe of an internal combustion engine, comprising an outer pipe (2) with an inlet side (3) and an outlet side (4), a plurality of diaphragm rings (9, 9', 9'', ''', 9'''') each with an outer surface connected (5) to the inner surface of the outer pipe (2), at least one insert (6) with an outer surface connected (7) to the inner surface of the outer pipe (2) and/or the diaphragm rings (9, 9', 9'', 9''', 9'''') and with a plurality of openings (8) which are closed on one side. Said insert (6) forms sub-pipes for the gas flow in the silencer, and the openings (8), which are closed on one side, open into the sub-pipes, the depth thereof being /4 in relation to the wavelength of a frequency to be silenced. At least one perforated wall (10, 10', 11, 11'), extends between at least two diaphragm rings (9, 9', 9'', 9''', 9'''') whereby an outer surface is connected (7) to at least one inner surface of the two diaphragm rings (9, 9', 9''', 9'''', wherein at least one resonance cell is fixed between the two diaphragm rings (9, 9', 9'', 9''', 9'''') of the perforated wall (10, 10', 11, 11') and the outer pipe (2).

Description

The invention relates to a silencer for noise-laden gases leading pipes according to the preamble of claim 1.

1. 1. Absorptionsschalldämpfer
   Von einem Absorptionsschalldämpfer erwartet man, daß höhere, besonders lästige Frequenzen durch Schluckstoffe absorbiert, aufgesaugt, bzw. in Reibungswärme umgewandelt werden.
   Aus der EP 0 834 011 B1 ist beispielsweise ein Absorptionsschalldämpfer für eine Brennkraftmaschine bekannt, bestehend aus einem die Ansaugluft führenden Ansaugrohr und einem dieses unter Bildung eines geschlossenen Resonanzraums umschließenden Resonatorgehäuse. Ferner ist der Absorptionsschalldämpfer mit einem Einlaßstutzen und einem Auslaßstutzen, mit Öffnungen in der Rohrwand des Ansaugrohrs, die den Innenraum des Ansaugrohrs mit dem Innenraum des Resonators verbinden, ausgerüstet. Eine oder eine axiale Folge von mehreren quer zur Längsachse des Ansaugrohrs ausgerichteten und dieses umschließenden Kammerwänden bildet bzw. bilden dabei im Resonatorgehäuse hermetisch gegeneinander abgegrenzte Resonatorkammern unterschiedlichen Volumens, wobei jede Resonatorkammer mit dem Innenraum des Ansaugrohrs über Öffnungen in der Rohrwand des Ansaugrohrs kommuniziert, ohne Überbrückung von Kammerwänden, und eine für jede einzelne Resonatorkammer auf Lage und Breite eines für diese jeweils konstruktiv vorgegebenen Resonanzfrequenzbandes aufeinander abgestimmte Dimensionierung des Resonatorkammervolumens, der Querschnittsfläche der Öffnung und der der Wandhöhe der Öffnungen entsprechenden Stärke des Ansaugrohrs im Bereich der jeweiligen Öffnung aufweist. Jede Öffnung und die dazugehörige Resonatorkammer bilden also jeweils einen auf das zu absorbierende, also zu dämpfende Frequenzband abgestimmten Helmholtz-Resonator.
   In der WO 80/02304 A1 wird ebenfalls ein Resonanzschalldämpfer in Form von Helmholz-Resonatoren beschrieben, der über perforierte Bleche aus rostfreiem, kaltflies-gepresstem, galvanisiertem Stahl, Aluminium oder anderen metallischen oder synthetischen Materialien und Dämpfungspassagen verfügt, um eine Geräuschdämpfung zu erzielen.
2. 2. Reflexionsschalldämpfer
   Die Wirkung von Reflexionsschalldämpfern beruht sowohl auf Reflexion von Schallwellen zur Schallquelle als auch auf Vervielfachung von Schallpunkten. Die Dämpfung ist dabei um so wirksamer, je zahlreicher die Reflexionsstellen sind.
   Ein Reflexionsschalldämpfer für gasdurchströmbare Rohrleitungen mit einem Einlaß, einem Auslaß und einer zwischen diesen Anschlüssen liegenden Kammer, in der quer zur Strömungsrichtung, den Strömungsquerschnitt der Kammer verkleinernd, Kulissen oder Blenden angeordnet sind, im Luftansaugkanal einer Brennkraftmaschine, ist beispielsweise aus der WO 97/09 527 bekannt.
3. 3. Interferenzschalldämpfer
   Ein Teil der Schallenergie wird bei Interferenzschalldämpfern beim Zusammentreffen nach verschieden lang zurückgelegten Wegen ausgelöscht.

Basically, one differentiates between three types of dampers, which are based on different physical principles, namely as follows:

1. 1. Absorption silencer
   From an absorption silencer, it is expected that higher, particularly annoying frequencies are absorbed, absorbed, or converted into frictional heat by sweat.
   From the EP 0 834 011 B1 For example, an absorption silencer for an internal combustion engine is known, comprising an intake pipe leading the intake air and a resonator housing enclosing this to form a closed resonance space. Further, the absorption silencer is equipped with an inlet port and an outlet port, with openings in the pipe wall of the intake pipe, which connect the interior of the intake pipe with the interior of the resonator. One or an axial sequence of a plurality of chamber walls oriented transversely to the longitudinal axis of the intake pipe and forming it form hermetically mutually delimited resonator chambers of different volume in the resonator housing, each resonator chamber communicating with the interior of the intake pipe via openings in the pipe wall of the intake pipe, without bridging Chamber walls, and for each individual resonator on the position and width of a respective structurally predetermined resonant frequency band coordinated dimensioning of the Resonatorkammervolumens, the cross-sectional area of the opening and the wall height of the openings corresponding strength of the intake pipe in the region of the respective opening. Each opening and the associated resonator chamber therefore each form a Helmholtz resonator tuned to the frequency band to be absorbed, that is to be damped.
   In the WO 80/02304 A1 Also described is a resonance muffler in the form of Helmholtz resonators, which has perforated sheets of stainless, cold-pressed, galvanized steel, aluminum or other metallic or synthetic materials and damping passages to achieve noise attenuation.
2. 2. Reflection silencer
   The effect of reflection silencers is based both on reflection of sound waves to the sound source and on multiplication of sound points. The attenuation is the more effective, the more numerous the reflection points are.
   A reflection muffler for gas durchströmbare pipes with an inlet, an outlet and a lying between these ports chamber in the transverse to the flow direction, the flow cross-section of the chamber downsizing, scenes or screens are arranged in the air intake duct of an internal combustion engine, for example, from WO 97/09 527 known.
3. 3. Interference muffler
   Part of the sound energy is extinguished in interference mufflers when meeting after different distances traveled.

Combinations of the abovementioned muffler types are of course widely known in the art. A special combination of sound damping mechanisms is for example from the DE 197 03 414 A1 known. There is a combination a reflection sound absorber in the form of axially successively connected annular aperture and a resonant damper in the form of λ / 4 resonators disclosed. A disadvantage of the known silencer are the high flow losses due to the annular diaphragms, and moreover, there is still no satisfactory tunability of the frequencies to be damped, both in terms of the range and the broadband before.

The invention is therefore based on the object, the generic, from the EP 0 834 011 B1 develop known silencer to the effect that the disadvantages of the prior art are overcome, in particular in the frequency range of 1 to 20 kHz, a tunable damping is possible.

The present object of the invention is achieved by the characterizing features of claim 1.

In claims 2 to 13 preferred embodiments of the noise damper according to the invention are described.

The invention is thus based on the surprising finding that a multiple combination of reflection mufflers and resonance mufflers allows a tuning of a frequency range to be damped from 1 to 20 kHz without significant flow losses in a compact design. The corresponding combination is based on the use of one or more hole walls, so that the ring diaphragms function both as reflection walls and to delimit Helmholtz resonators to form absorption silencers in addition to the λ / 4 resonators of the insert, without too considerable flow losses to lead.

Further features and advantages of the invention will become apparent from the following description in which an embodiment of the invention is explained in detail by way of example with reference to schematic drawings.

Figur 1

eine perspektivische Ansicht eines erfindungsgemäßen Geräuschdämpfers; und

Figur 2

eine perspektivische Ansicht gemäß Figur 1, mit zum Teil entfernten Außenrohr.

It shows

FIG. 1

a perspective view of a noise damper according to the invention; and

FIG. 2

a perspective view of Figure 1, with partially removed outer tube.

As can be seen in Figures 1 and 2, an inventive silencer 1 comprises an outer tube 2 with an inlet side 3, an outlet 4 and a contact surface 5, an insert 6 with a contact surface 7 and closed on one side openings or blind holes 8, a plurality of Ring diaphragms 9, 9 ', 9 ", 9"', 9 "", and pinhole apertures 10, 10 ', 11, 11' with holes 12, 12 ', 13, 13'. The annular apertures 9, 9 ', 9 ", 9"', 9 "" between the outer tube 2 and the insert 6 are arranged so that the contact surface 5 between the outer tube 2 and the annular apertures 9, 9 ', 9 ", 9 "', 9" "and the contact surface 7 between the annular apertures 9, 9', 9", 9 "', 9" "and the insert 6 extend, wherein the insert 6 extends substantially concentrically within the outer tube 2.

Through the insert 6 four separate line sections are provided in the silencer 1. The blind holes 8 each open to the sub-lines, are partly on opposite surfaces, preferably offset, arranged and have a depth which is tuned to a quarter of the wavelength of the herauszudämpfenden from the noise spectrum frequency. By a targeted change in the depth of the blind holes 8 over the entirety of the insert 6, an excellent broadband of the damping can be achieved, wherein the depth of the inlet side 3 to the outlet 4 increases.

Of the hole walls 10, 10 ', 11, 11', the annular apertures 9, 9 ', 9 ", 9"', 9 "" and the outer tube 2 four resonance chambers are limited. Said resonance chambers are either additional reflection mufflers or resonance mufflers, depending on the configuration of the hole wall 10, 10 ', 11, 11'. Thus, there is a reflection muffler in the case where the hole wall 10, 10 'is formed of a thin steel sheet, for example, while a resonance muffler is in the case where the hole wall 11, 11' a Wall thickness in a range of 0.6 to 5 mm, so that each hole 13, 13 'forms with the resonance chamber tunable to the absorption band to be damped by the frequency-tunable Helmholtz resonator. In addition, the perforated walls 10, 10 ', 11, 11' not only provide an additional possibility of tuning a frequency band to be damped, but at the same time also reduce the flow losses due to vortices on the annular diaphragms 9, 9 ', 9 ", 9 "', 9""certainly. As a result, the noise damper 1 is overall improved considerably over the prior art.

Neither the outer tube 2 nor the hole walls 10, 10 ', 11, 11' must be circular in radial section. The resonance behavior of each individual sound-absorbing resonance chamber is ultimately determined only by the oscillating air volume with respect to its resonant frequency, and not by geometric shapes, so that the noise damper 1 of the invention with the smallest possible design practically any available installation space is adaptable.

LIST OF REFERENCE NUMBERS

1

Silencer

2

outer tube

3

inlet side

4

outlet

5

contact area

6

commitment

7,7 '

contact area

8th

blind

9, 9 ', 9 ", 9"', 9 ""

ring diaphragm

10, 10 '

Pegboard

11, 11 '

Pegboard

12, 12 '

hole

13, 13 '

hole

Claims (13)

1. Silencer (1) for pipelines carrying noisy gases, in particular for an intake line and/or an exhaust line of an internal combustion engine, comprising
   an outer tube (2) with an inlet side (3) and an outlet side (4),
   a plurality of annular shutters (9, 9', 9", 9''', 9"") each with an outer face in the form of a contact face (5) which is connected to the inner face of the outer tube (2), and
   at least one perforated wall (10, 10', 11, 11') which stands between at least two annular shutters (9, 9', 9", 9"', 9"") with an outer face in the form of a contact face (7') which is connected to at least one inner face of the two annular shutters (9, 9', 9", 9"', 9""), wherein at least one resonance chamber is secured between the two annular shutters (9, 9', 9", 9"', 9"") of the perforated wall (10, 10', 11, 11') and the outer tube (2), characterized by at least one insert (6) with an outer face in the form of a contact face (7) and having a plurality of openings (8) which are closed at one end, wherein the annular shutters (9, 9', 9", 9"', 9"") are arranged between the outer tube (2) and the insert (6) such that the contact face (5) runs between the outer tube (2) and the annular shutters (9, 9', 9", 9"', 9"") and the contact face (7) runs between the annular shutters (9, 9', 9", 9"', 9"") and the insert (6) and the insert (6) forms partial lines for the gas flow in the silencer (1) and the openings (8) which are closed at one end open into the partial lines, and have a depth of λ/4 in relation to the wavelength of a frequency to be damped.
2. Silencer according to Claim 1, characterized in that the insert (6) has essentially plate-shaped inner walls which are arranged essentially in a cross shape or star shape in radial section, are provided on both sides with the openings (8) which are closed at one end, and preferably extend essentially over the entire axial length of the outer tube (2).
3. Silencer according to Claim 2, characterized in that the openings (8) which are closed at one end are arranged on both sides of an inner wall, offset with respect to one another on the two sides of an inner wall.
4. Silencer according to one of the preceding claims, characterized in that the openings (8) which are closed at one end are arranged essentially in rows from the inlet end (3) to the outlet end (4), wherein the depth of the openings (8) which are closed at one end is the same in one row and different from row to row, preferably with increasing depth from the inlet end (3) to the outlet end (4).
5. Silencer according to one of the preceding claims, characterized in that the distance between the annular shutters (9, 9', 9", 9"', 9"") is different, preferably increasing from the inlet end (3) to the outlet end (4).
6. Silencer according to one of the preceding claims, characterized in that at least one resonance chamber and at least one hole (13, 13') in the perforated wall (11, 11') of the resonance chamber form a Helmholtz resonator which can be matched to a frequency to be damped by means of the volume of the resonance chamber, the cross-sectional area of the hole (13, 13') in the perforated wall (11, 11') of the resonance chamber and the thickness of the perforated wall (11, 11') of the resonance chamber in the region of the hole (13, 13').
7. Silencer according to Claim 6, characterized in that the thickness of the perforated wall (11, 11') is 0.6 to 5 mm, preferably 1 to 3 mm.
8. Silencer according to one of the preceding claims, characterized in that one or more perforated walls (10, 10', 11, 11') which are arranged one behind the other from the inlet side to the outlet side extends/extend over the entire axial length of the outer tube (2), preferably concentrically within the outer tube (2).
9. Silencer according to Claim 7 or 8, characterized in that a plurality of resonance chambers are provided, wherein frequency bands of adjacent resonance chambers which are to be damped preferably overlap at least partially and/or the resonance chambers form reflection silencers and/or absorption silencers.
10. Silencer according to one of the preceding claims, characterized in that the annular shutters (9, 9', 9", 9"', 9"") are provided with openings which are closed at one end and which open into the partial lines and have a depth of λ/4, wherein the depth preferably increases from the inlet end (3) to the outlet end (4).
11. Silencer according to one of the preceding claims, characterized in that the outer tube (2), the annular shutters (9, 9', 9", 9"', 9""), the insert (6) and/or the perforated wall or perforated walls (10, 10', 11, 11') is/are formed from a metal, in particular aluminium, a heat-resistant plastic, in particular a fibre-reinforced plastic, hard rubber and/or a ceramic, such as a porous sintered material.
12. Silencer according to one of the preceding claims, characterized in that the outer tube (2) and the annular shutters (9, 9', 9", 9"', 9"") and/or the perforated wall (10, 10', 11, 11') and the insert (6) and/or the annular shutters (9, 9', 9", 9"', 9"") and the perforated wall (10, 10', 11, 11') are formed as one piece preferably as an aluminium die cast part.
13. Silencer according to one of the preceding claims, characterized in that the outer tube (2), the insert (6), the openings (8) which are closed at one end in the insert (6) and/or the holes (12, 12', 13, 13') in the perforated wall (10, 10', 11, 11') is/are essentially rotationally symmetrical, preferably circular, in radial section.

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