DE102004022972A1 - Resonator for exhaust-gas system, has control unit adjustable relative to neck such that flow through cross section of resonator is varied and effective length of resonator is varied for adjusting resonance frequency of the resonator - Google Patents

Abstract

The resonator has a resonance body (18) and a neck (22) that has a flow channel (12) for vibrating gas streams. A movable control unit is provided in the body. The unit is adjustable relative to the neck in such a manner that flow through cross section of the resonator is varied and an effective length of the resonator is varied for adjusting resonance frequency of the resonator. An independent claim is also included for an exhaust-gas system of a motor vehicle comprising a resonator.

Description

The The invention relates to a resonator according to the preamble of the claim 1 for the reduction of noise in systems with pulsating gas streams, especially in a Exhaust system or an intake system of an internal combustion engine. Of Furthermore, the invention relates to an exhaust system or an intake system for one Internal combustion engine equipped with a resonator according to the invention is.

By the clocked combustion process in an internal combustion engine arise in the fresh air stream sucked in by the fresh air intake system and in the exhaust gas stream flowing through the exhaust system of the internal combustion engine Pressure pulses, which depend on from the speed of the internal combustion engine to the formation of sound waves different frequencies in the fresh air flow or in the exhaust gas flow to lead. Through the use of silencers in the intake system or the exhaust system in particular the for the human hearing audible Frequencies muted become. About that In addition to be prevented with the help of silencers that Sound waves from the intake system or the exhaust system to the body as well as the chassis of the vehicle and make them vibrate.

Around higher frequency To dampen sound waves, it is known, the fresh air flow or the exhaust gas flow through a so-called sound absorber or absorption silencer too conduct, in which the energy of the sound waves in a damping material by friction in heat is converted and so the sound waves are attenuated. low Sound waves can be damped with the help of a so-called resonator, which consists of a with the gas channel through which the pulsating gas flows, for example the exhaust pipe, related pipe section, and resonator neck called, and is formed with a resonator connected to the resonator neck. Due to the low-frequency sound waves in the Resonatorhals and in the sound box Gas volumes contained in resonant vibrations, wherein the gas volumes each own masses a damping of low-frequency Contribute proportions of sound waves.

wobei c_p,T die temperatur- und druckkorrigierte Schallgeschwindigkeit, A die durchströmte Querschnittsfläche des Resonatorhalses des Helmholtz-Resonators, V das Volumen des Resonanzkörpers des Helmholtz-Resonators sowie I_eff die durchströmte effektive Länge des Resonatorhalses darstellen.The damping effect is limited in a conventional resonator with a constant damping effect, for example a Helmholtz resonator, but by the volume of the resonator and the flow cross-section and the length of the Resonatorhalses to a certain frequency or a very limited frequency range of the sound waves. Thus, the resonance frequency of the Helmholtz resonator is simplified by:

where c _{p, T represent} the temperature- and pressure-corrected sound velocity, A the cross-sectional area of the resonator neck of the Helmholtz resonator, V the volume of the resonance body of the Helmholtz resonator, and I _eff the effective length of the resonator neck.

There a conventional one Internal combustion engine while passing through its speed range but deep Frequencies in a big one Frequency range generated from about 30 to 180 hertz, Helmholtz resonators with constant damping effect only a small section of this frequency range effective dampen.

Out This reason has been going on for some time attempts to use variable damping resonators for intake systems and exhaust systems of internal combustion engines to be provided in are able, as possible to attenuate the entire frequency range of low frequencies, the occur during operation of an internal combustion engine.

So revealed the DE 200 18 689 U1 a resonator in which a tube of constant cross-section, which is in fluid communication with the exhaust pipe of the exhaust system, is used as the resonance body. In order to adjust the resonant frequency of the resonator, a piston is introduced as an actuator in the resonator, by which the volume of the resonator is to be selectively changed.

In the EP 1 085 200 A2 For example, a resonator for an exhaust system is described, in which a piston can be introduced into the resonance body in order to change the volume of the resonator.

From the DE 196 18 432 A1 For example, a resonator for an intake device of an internal combustion engine is known. In this resonator, the effective damping volume is varied in size by means of switchable tube sections and flaps.

The EP 1 067 511 A2 discloses an arrangement in which two U-shaped resonating body are pushed onto correspondingly shaped connecting pieces on the exhaust pipe of the exhaust system, wherein the flow-through length and the volume of the two resonant body by respective back and forth displacement along the connecting piece verän can be changed.

From the DE 100 04 991 A1 a Helmholtz resonator with variable resonance frequency is known in which the resonance body is in flow communication with the exhaust pipe through two pipe sections, wherein the opening cross sections of the two pipe sections can be changed by means of diaphragms to set different resonance frequencies.

The DE 197 54 840 A1 WO 99 17012 A and the DE 43 05 333 C1 each reveal a resonator in which the resonator is connected by connecting pieces with different flow cross-sections with the exhaust pipe from the gas system or the intake pipe of the internal combustion engine. In this case, the resonant frequency of the resonator should be changed by activating the differently dimensioned connecting pieces.

The DE 100 02 984 C2 describes an acoustic absorber with a resonance chamber, in which an elastic membrane is arranged, whose vibration behavior can be changed by applying a pressure for adjusting the resonance frequency.

From the EP 1 381 025 A2 a noise damping device with a Helmholtz resonator is known in which the resonator body is connected by two connecting necks with a gas passage through which a pulsating gas flow flows. One of the connecting necks is provided with a flap which can be closed by an actuator to lock the connecting neck. However, only two different frequencies can be damped with this known device. There are also tightness problems on the flap, which must be dimensioned smaller due to the thermal expansion occurring in particular in an exhaust system in order to prevent seizing of the flap.

The Although previously described different approaches show under laboratory conditions a good damping effect. Due to high temperatures and high pressure fluctuations, which prevail especially in exhaust systems are leaks constructive but not avoid what the use of this Restricted known resonators in a motor vehicle.

Of the Invention is based on the object, a resonator for reduction of noises in systems with pulsating gas streams or one with such Resonator equipped exhaust system or intake system for a Specify internal combustion engine, in which or by its use Setting the resonance frequency over a big Frequency range is easily possible.

The Invention solves This object is achieved by a resonator with the features of claim 1. Furthermore solves the invention of this object by an exhaust system according to claim 18 and by an intake system according to claim 20, each with a resonator according to the invention are equipped.

In the resonator according to the invention not only the flow-through cross-sectional area A of the Resonatorhalses, but at the same time effective for the resonance effect length I _{eff of} the Resonatorhalses and / or the effective volume V of the resonator is changed by means of the movable actuator.

Since in a conventional internal combustion engine, the speed changes in a ratio of about 1: 6, it is clear from the above formula that the necessary change in the resonant frequency f _res by this factor is only possible if the cross-sectional area A or the effective length I _{eff of} the resonator neck and the volume of the resonator each by a factor 36 will be changed.

In the case of the resonator according to the invention, it is now possible to set at least one of the two other parameters mentioned above, in addition to the cross-sectional area A flowed through, namely the effective length I _{eff of} the resonator or the resonator volume V of the resonator body, so that in the resonator according to the invention at realistic size ratios and control path lengths make it possible to set a significantly greater change in the resonant frequency as compared with the prior art. In addition, in the resonator according to the invention no seals in the resonator neck are required because to change the resonant frequency only the actuator must be changed in position relative to the resonator neck, so that the entire assembly is insensitive to manufacturing tolerances or temperature-dependent dimensional changes and occurring in the prior art Leakage problems are solved.

As have already shown the first series of experiments with the resonator according to the invention, can be with the resonator according to the invention low frequencies in relation to effectively dampen from about 1: 5, so that almost the entire frequency range is lower frequencies more common Internal combustion engines is covered.

Further advantageous developments of the invention will become apparent from the subsequent description, the drawings and the subclaims.

So is in a particularly preferred embodiment of the resonator according to the invention the Control element designed so that when adjusting the control element the distance of its outer contour to the inner contour of the Resonatorhalses changes while at the same time Length changes, with the adjusting element is inserted in the resonator neck. So that becomes for the resonant frequency essential, flowed through Cross section in the resonator neck in this embodiment by the distance the outer contour of the adjusting element to the inner contour of the Resonatorhalses, while the effective length of the resonator neck depends on how far the actuator is inserted into or out of the resonator neck this is pulled out. In which the distance of the actuating element to the resonator neck and the length changed is introduced with the actuator in the resonator neck, For example, the resonance frequency of the resonator can be changed easily.

Around a striking of the actuating element on the inner contour of the resonator neck to avoid effectively, it is also advantageous in this embodiment, when the actuator so relative to the inner contour of the Resonatorhalses is designed to be movable in any position spaced from the Inner contour of the Resonatorhalses is arranged.

Of Further, in a particularly preferred embodiment of previously described embodiment of the resonator according to the invention proposed to make the actuator so that it is completely off can be moved out of the resonator neck. This ensures that the entire opening area the resonator neck is effective.

In a particularly preferred further embodiment, the resonator according to the invention has a resonator neck which widens in the flow cross section and into which the actuating element is at least partially introduced, the outer contour of the actuating element being adapted at least in sections to the tapering inner contour of the resonator neck. By the actuator is moved relative to the opening area, it comes not only to a change in the flowed through cross-sectional area A of the Resonatorhalses, but also to a change in the effective length of the resonator neck I _eff , while the effective volume V of the resonator remains unchanged.

Of the Resonator neck is preferably widened funnel-shaped in this embodiment formed, i. the opening area has a rotationally symmetrical inner contour, whereby the Production of the resonator neck as a rotationally symmetrical component much easier. The outer contour of the actuating element is at least in this embodiment of the resonator partially formed as a cone or as a truncated cone. Of the Resonator neck is preferably expanded in the direction of the resonator educated.

at a corresponding design of the expanding resonator neck For example, the actuator can also be wedge-shaped or pyramid-shaped be while the inner contour of the resonator neck shows a complementary course.

at an alternative embodiment comes a plate-shaped Actuator used, which is arranged in the resonator and relative to the mouth of the Resonator neck in the resonator body is movable back and forth. By adjusting the distance of the control element to the mouth opening can at the same time the flow-through cross-section, delimited by the actuator and the wall portion of the resonator is, through which the gas pulsates, as well as the resonance volume of the resonance body adjusted be, which depends on the position of the actuating element in the sound box.

there it is of particular advantage in this alternative embodiment, if the plate-shaped Control element with its flat side transverse to the pulsation of the runs in the resonator neck pulsating gas and seen axially in the pulsation direction back and forth is adjustable and the flat side of the control element is sized so that it is bigger as the cross-sectional area the mouth of the Resonator neck, so that the actuator completely covers the mouth opening. The perfused Cross section is then from the wall section, preferably the floor, of the sound box, in which the mouth opening is formed is, and facing the mouth opening Flat side of the actuator limited.

The adjusting element is preferably made of a flat material, preferably a metal sheet, wherein only the flat material forms the outer contour of the actuating element. This results in the advantage that the actuating element has a comparatively low weight and the actuator for adjusting the adjusting element can consequently be dimensioned correspondingly small. Furthermore, in this embodiment of the resonator according to the invention, it is particularly advantageous if the actuating element is at its end opposite the end to be inserted into the resonator neck is open, so that the resonance volume of the resonator body is hardly affected by the actuator.

To the Setting the resonance frequency, the actuator is preferably moved between each predetermined positions back and forth, so that the control of the actuator is comparatively easy.

To the Adjusting the control element is preferably an actuator used electrically, hydraulically or pneumatically actuated actuator. In particular, the use of an electrically operated Actuator has the advantage that the actuator with comparatively high positioning speed and sufficiently high accuracy Adjustment can adjust. Also an adjustment by the exhaust itself is conceivable in principle.

Especially Preferably, a servo motor is used as the actuator. alternative but it is also possible to use a vacuum box as an actuator, for example with an upstream section of the exhaust system or a section the intake system to operate connected is. The use of a vacuum box is especially then advantageous if the actuator only between two positions to adjust.

Around one possible exact match to achieve the resonance frequency of the resonator with the disturbing frequency it is particularly advantageous if the actuator depending on the speed of the internal combustion engine and / or in dependence from the flow rate and / or the temperature of the gas flow in the exhaust system or the intake system is adjusted. Alternatively, it is possible to adjust the actuator accordingly to adjust a predetermined map of the engine control. Especially the adjustment of the actuating element as a function of the speed or the map of the internal combustion engine has the advantage that with appropriate consideration a corresponding delay, the dependent is predetermined by the duration, for example, the exhaust gas flow after change the speed of the internal combustion engine needed to get to the resonator, the actuator can be moved in an optimized damping position can. The actuator can either in each case predetermined positions to be moved. Alternatively, it is also possible, the actuator, in particular when using a servomotor as an actuator, very fine in its position to vary relative to the resonator neck. Furthermore, the adjustment of the actuating element in dependence of an acoustically relevant size at the outlet of the exhaust system or at the inlet of the intake system.

at Test series with the resonator according to the invention has been found that with a combination of expanding resonator neck and adjustable actuator a resonant frequency range of about 30 hertz to 180 hertz can be adjusted.

A Tuning of the resonator according to the invention to lower frequencies to achieve by reducing the throat area. at a too small cross section leaves however, the effectiveness inevitably to. A tuning of the resonator to lower frequencies is also possible through an extension reach the Resonatorhalses. Not to the adjustment too big and Therefore, it is favorable for low frequencies a second Resonator neck provide that are not made even variable got to.

This second resonator neck is in its length and its cross section so that it becomes effective once the effectiveness of the variable Resonator because of a too small flowed through cross-section A clearly subsides. In contrast to known solutions, in which instead of the variable first resonator neck according to the invention A neck with flap is used for the variable resonator neck no special tightness necessary. In principle, the second resonator neck can also be made variable be.

There the sound box from the exhaust gas is not flowed through directly, the resonator can completely or partially made of plastic or a light metal or a Combination made of several plastics and light metals be. However, the resonator and its components can also be made of the same Material be made, such as the exhaust system or the intake system.

In Similarly, the actuator can also be made of a plastic or a light metal or a combination of these.

According to one In another aspect, the invention relates to an exhaust system for a motor vehicle, with a resonator according to the invention, equipped as described above. The resonator stands preferably with a pipe section of the exhaust pipe in fluid communication, the, compared with other pipe sections of the exhaust pipe, the lowest Has flow cross-section. It has been shown that by connecting the resonator with a pipe section of the exhaust pipe with the smallest flow cross-section the largest damping effect can be achieved.

According to a third aspect, the invention relates to an intake system for an internal combustion engine, which with a Re sonator is equipped.

Further Features and advantages of the invention will become apparent from the following Description of a preferred embodiment with reference on the attached Drawing. It shows:

1 1 is a schematic, perspective view of a resonator with a variable resonator neck and a bass frequency neck according to the invention;

2 a schematic sectional view of an enlarged section of the resonator according to the invention,

3 a diagram in which the transmission loss based on the frequency is shown and

4 a schematic sectional view of an embodiment of the resonator according to the invention.

In 1 is a schematic perspective view of an inventive resonator 10 shown with an exhaust pipe 12 a not shown exhaust system of an internal combustion engine is in flow communication. The exhaust pipe 12 is in the present case at its two ends with flanges 14 and 16 provided so that the resonator 10 together with the exhaust pipe 12 can be used in an existing exhaust system as a unit.

The resonator 10 has a cylindrical resonator body 18 with a resonance volume 20 , The one end of the resonator 18 stands by one in the direction of the resonator 18 expanding resonator neck 22 over an opening 24 with the exhaust pipe 12 the exhaust system in flow communication. The other end of the resonator 18 is through a plate 26 locked.

In the center of the plate 26 is a first sliding guide 28 arranged. Spaced to the first slide 28 is inside the sound box 18 a second sliding guide 30 arranged, which concentric with the first sliding guide 28 is positioned and by three radially from the second sliding guide 30 outwardly projecting spacers 32 inside the resonator 18 is held.

The two sliding guides 28 and 30 serve as guides for a pole 34 , at the end of a frusto-conical actuator 36 is fastened, which with its end of smaller diameter in the direction of the funnel-shaped expanding resonator neck 22 shows.

The truncated cone-shaped actuator 36 is formed by a flat material, in the present case a sheet, wherein the flat material is formed so that the conical outer contour of the actuating element 36 to the inner contour of the funnel-shaped expanding resonator neck 22 is adapted, wherein the end face of the actuating element 36 closed is. To the weight of the control element 36 keep as low as possible and thus the actuator 36 the resonance volume 20 of the resonator 18 not affected as possible, is the frusto-conical actuator 36 open at its end of larger diameter.

The frustoconical actuator 36 can with the help of a servomotor, not shown inside the resonator 18 be moved back and forth, where the actuator 36 in the funnel-shaped expanding resonator neck 22 can be inserted or withdrawn from the resonant frequency of the resonator 18 to change, as will be described in detail later.

Adjacent to the resonator neck 22 is a deep-frequency neck 38 arranged, which is formed in the shape of a right angle bent tube. The one end of the deep-frequency neck 38 stands through an opening 40 with the exhaust pipe 12 in fluid communication, while the other end of the deep frequency neck 38 through an opening, not shown, in the interior of the sound box 18 protrudes. This ensures that the resonance volume 20 of the resonator 18 both through the resonator neck 22 as well as through the deep-frequency neck 38 is shared, resulting in a particularly compact design of the resonator 10 results.

The following is based on the 2 and 3 the mode of action of the resonator according to the invention 10 explained in more detail.

As already described, the rotational speeds of a conventional internal combustion engine change in its operation in a ratio of about 1: 6, so that inter alia low-frequency sound waves occur in a range of 30 to 180 hertz. With the help of the resonator according to the invention 10 It is now possible to specifically attenuate certain low-frequency sound waves in the exhaust stream.

For this purpose, the actuator, not shown, is connected to the control of the internal combustion engine and in dependence on the rotational speed of the internal combustion engine in compliance with a correspondingly predetermined time delay, the frusto-conical actuator 36 relative to that funnel-shaped expanding resonator neck 22 adjusted. It is possible, the actuator 36 either to move back and forth between fixed predetermined positions or the actuator 36 for a particularly accurate adjustment of the damping effect stepless relative to the funnel-shaped expanding resonator neck 22 to adjust.

Will the actuator 36 further into the funnel-shaped expanding resonator neck 22 of the resonator 18 introduced, on the one hand takes the still free opening cross-section A, through which the exhaust gas in the first resonator 18 can flow continuously, while at the same time the effective length I _eff , which through the actuator 36 and the resonator neck 22 is defined, is enlarged, how 2 shows, in the funnel-shaped expanding resonator neck 22 and the actuator 36 enlarged shown in section.

On this way you can different frequencies are effectively damped.

The damping effect of the resonator according to the invention 10 could be proven in first series of experiments. In 3 is the high damping effect of the resonator according to the invention 10 expressed in dB relative to the frequency in Hertz.

Thus, the resonator according to the invention 10 at completely out of the resonator neck 22 pulled actuator 36 the dotted damping curve D ₁ with the highest damping effect between 160 and 170 hertz.

If sound waves are to be attenuated in lower frequency ranges, only the control element needs to be damped 36 in the resonator neck 22 are moved in, whereby the flow-through cross-section A decreases, while the effective length I _{eff of} the resonator neck 22 increases and thus the resonant frequency of the resonator 10 reduced.

By appropriate adjustment of the control element 36 Thus, different frequency ranges can be specifically damped, as are the various other damping curves D ₂ to D ₅ in FIG 3 demonstrate.

Is the control element 36 completely in the resonator neck 22 moves, with a small distance between the inner contour of the Resonatorhalses 22 and the actuator 36 remains, the resonator has 18 only a limited damping effect. In this operating state comes the Tiefenfrequenzhals 38 for use. The effective length I _eff and the flow cross-section A of the deep-frequency neck 38 is chosen so that particularly low-frequency sound waves with a frequency of less than about 35 hertz through the resonator 10 be dampened, like those in 3 shown damping curve D ₅ shows.

If higher-frequency components in the sound waves are to be damped again, the actuator must 36 only back from the resonator neck 22 be pulled out.

In 4 is a modified embodiment of the in the 1 and 2 shown resonator 10 shown, wherein identical components are identified for simplicity with identical reference numerals. So has the in 4 shown resonator 50 also a resonator 18 passing through a resonator neck 52 with the exhaust pipe 12 is in flow communication. Furthermore, the resonator has 50 also a deep-frequency neck 38 who, like the one in 1 shown resonator 10 in which sound box 18 ends.

The resonator neck 52 is formed in this modified embodiment as a tube with a constant cross section and ends in a concentric with the cylindrical resonator body 18 in its flat bottom 54 trained mouth opening 56 such that the pulsation direction P of the exhaust gas is substantially in the longitudinal direction of the resonance body 18 is directed.

In the sound box 18 is also one on the pole 34 held actuator 58 provided, which is formed in this modified embodiment as a circular plate. The concentric to the mouth opening 56 arranged actuator 58 is dimensioned so that there is on the one hand the mouth opening 56 covered, on the other hand, however, sufficient distance to the inner peripheral surface of the resonator 18 holds. This is an annular gap 60 formed by the pulsating exhaust gas flow to the interior of the resonator 18 can communicate.

As 4 can be seen, while the flowed through cross section A of the annular gap 60 by the distance of the underside of the control element 58 to the ground 54 defined while the effective length I _eff from the diameter of the actuator 58 depends.

To the resonant frequency of the resonator 50 to change, only the actuator must 58 from the mouth opening 56 away or moved towards this. On the one hand, the distance of the control element changes 58 to the ground 54 and thus the flow-through cross-section A of the annular gap 60 , On the other hand, the resonance volume changes 20 of the resonator 18 that through the plate 26 , the wall of the resonator 18 as well as the top of the control element 58 is limited.

Will the actuator 58 in the sound box 18 from the mouth opening 56 moves away, the cross-section A flows through, while the resonance volume 20 decreases, whereby the resonance frequency increases. To reduce the resonance frequency, the actuator becomes 58 in the direction of the mouth opening 56 moves, whereby the flow-through cross-section A decreases, while the resonance volume 20 increases.

Is the control element 58 at a short distance to the ground 54 held without touching it, is the annular gap 60 no longer effective during the deep-frequency neck 38 acts as a damping unit.

With the resonators according to the invention 10 and 50 It is possible depending on parameters such as the current speed of the internal combustion engine to selectively attenuate low-frequency sound waves in the exhaust gas flow. An essential advantage of the resonators according to the invention 10 and 50 consists in the fact that the resonator 10 respectively. 50 is comparatively simple and compared to the previously known resonators with variable damping effect has a low overall volume, but at the same time is able to effectively attenuate low-frequency sound waves over a very large frequency range. Furthermore, no sealing of the resonator against the exhaust gas stream is required at critical areas.

The in the 1 to 4 described resonators 10 and 50 can also be used in an intake system of an internal combustion engine to effectively damp the intake noise.

10

resonator

12

exhaust pipe

14

flange

16

flange

18

sound

20

resonance volume

22

resonator neck

24

opening

26

plate

28

first slide

30

second slide

32

spacer

34

pole

36

actuator

38

Low frequency neck

40

opening

D, to D ₅

 attenuation curves

50

resonator

52

resonator neck

54

ground

56

mouth

58

actuator

60

annular gap

P

Pulsationsrichtung

Claims (20)

Resonator for reducing noise in installations with pulsating gas flows, in particular in exhaust systems or intake systems of an internal combustion engine, with a resonance body ( 18 ), which by a resonator neck ( 22 ; 52 ) with a flow channel ( 12 ) can be brought into fluid communication for the pulsating gas flows, and a movable control element ( 36 ; 58 ) for adjusting the resonant frequency of the resonator ( 10 ; 50 ), characterized in that the actuating element ( 36 ; 58 ) relative to the resonator neck ( 22 ; 52 ) is adjustable, that of the resonant frequency (f _res ) prevailing flow-through cross-section (A) of the resonator ( 10 . 50 ) as well as simultaneously the resonant frequency influencing effective length (I _eff ) of the resonator ( 10 . 50 ) and / or the resonance volume (V) of the resonance body ( 18 ) for adjusting the resonant frequency of the resonator ( 10 . 50 ) is variable. Resonator according to claim 1, characterized in that by adjusting the adjusting element ( 36 ) the distance of the outer contour of the actuating element ( 36 ) to the inner contour of the resonator neck ( 22 ) and the length with which the actuator ( 36 ) in the resonator neck ( 22 ) is introduced. Resonator according to claim 2, characterized in that the outer contour of the actuating element ( 36 ) to the inner contour of the resonator neck ( 22 ) in each position of the actuating element ( 36 ) is spaced. Resonator according to at least one of claims 2 or 3, characterized in that the actuating element ( 36 ) from the resonator neck ( 22 ) is completely moved out. Resonator according to at least one of claims 1 to 4, characterized in that the resonator neck ( 22 ) in the flow cross-section and that the actuating element ( 36 ) in its outer contour at least in sections to the widening inner contour of the Resonatorhalses ( 22 ) and for adjusting the resonant frequency of the resonator ( 10 ) in the expanding resonator neck ( 22 ) into or out of this is movable. Resonator according to claim 5, characterized in that the resonator neck ( 22 ) is funnel-shaped and preferably in the direction of the resonator ( 18 ), and that the outer contour of the actuating element ( 36 ) is formed at least in sections as a cone or truncated cone. Resonator according to claim 1, characterized in that in the resonant body ( 18 ) a plate-shaped actuating element ( 58 ), which is relative to the mouth ( 56 ), with which the resonator neck ( 52 ) in the sound box ( 18 ), is movable back and forth, that by adjusting the distance of the actuating element ( 58 ) to the mouth opening ( 56 ) at the same time the flow-through cross-section (A) and the resonance volume ( 20 ) of the resonance body ( 18 ) is adjustable. Resonator according to claim 7, characterized in that the plate-shaped control element ( 58 ) with its flat side transverse to the pulsation direction (P) of the resonator neck ( 52 ) pulsating exhaust gas and axially in the direction of pulsation (P) is adjustable back and forth that the flat side of the actuating element ( 58 ) is greater than the cross-sectional area of the mouth opening ( 56 ) of the resonator neck ( 52 ) and that the actuator ( 58 ) the mouth opening ( 56 ) completely covered, wherein the flow-through cross-section (A) of the wall portion, preferably the bottom ( 54 ), the sound box ( 18 ), in which the mouth opening ( 56 ) is formed, and the mouth opening ( 56 ) facing flat side of the actuating element ( 58 ) is limited. Resonator according to at least one of claims 1 to 6, characterized in that the actuating element ( 36 ) is made of a flat material, preferably a metal sheet, and only the flat material, the outer contour of the actuating element ( 36 ), wherein the actuating element ( 36 ) at its end into the resonator neck ( 22 ) end to be inserted is preferably open. Resonator according to at least one of the preceding claims, characterized in that the actuating element ( 36 ; 58 ) is to be moved to set the resonance frequency in each predetermined positions. Resonator according to at least one of the preceding claims, characterized by an actuator which can be actuated electrically, hydraulically or pneumatically and which is used for adjusting the actuating element ( 36 ; 58 ) is coupled with this. Resonator according to at least one of claims 10 or 11, characterized in that the actuator is the actuator ( 36 ; 58 ) as a function of the rotational speed of the internal combustion engine and / or adjusted in dependence on the flow velocity of the gas stream in the exhaust system and / or in dependence on the characteristic map of the engine control. Resonator according to at least one of the preceding claims, characterized in that the resonator ( 10 ; 50 ) a second resonator neck ( 38 ) which is spaced from the first resonator neck ( 22 ; 52 ) through a second opening ( 40 ) with the flow channel ( 12 ) can be brought into fluid communication. Resonator according to claim 13, characterized in that the second resonator neck ( 38 ) spaced from the first resonator neck ( 22 ; 52 ) in the sound box ( 18 ) opens. Resonator according to one of claims 13 or 14, characterized in that the second resonator neck ( 38 ) is a tube with preferably constant flow cross-section. Resonator according to at least one of the preceding claims, characterized in that the resonant body ( 18 ) is made of a plastic, a light metal, preferably made of aluminum, an aluminum alloy, titanium or a titanium alloy, or a combination of plastic and light metal. Resonator according to at least one of the preceding claims, characterized in that the actuating element ( 36 ; 58 ) is made of a plastic, a light metal, preferably made of aluminum, an aluminum alloy, titanium or a titanium alloy, or a combination of plastic and light metal. Exhaust system for a motor vehicle, having a resonator ( 10 ; 50 ) according to one of claims 1 to 17. Exhaust system according to claim 18, characterized in that the pipe section of the exhaust pipe ( 12 ), with which the resonator ( 10 ; 50 ) is in flow communication, compared to other pipe sections of the exhaust pipe, having the smallest flow cross-section. Intake system for an internal combustion engine, with a resonator ( 10 ; 50 ) according to one of claims 1 to 17.