DE19520157A1 - Motor vehicle exhaust silencer with choke flap - Google Patents

Abstract

The choke flap (10) is held closed by permanent magnet (11) and/or spring etc. and is opened by the exhaust flow. The flap lies in a tube sector (9) which forms an extension of the exhaust entry pipe (3) and goes over into the exhaust outlet pipe (4). The outlet pipe encloses the end part of the extension (9), leaving an annular gap between pipe (4) and extension (9) to pass the exhaust through the two chambers (K3-5) into the outlet pipe (4). Two outlet pipes can be used so as to separate the main exhaust flow from that passing through the sector (9) and lead these flows off outwards. Where the flap is arranged in the offtake pipe leading from divider pipe to the main chamber, the sector housing the flap connected directly to the outlet pipe (4). In the pipe extension (9) the choke flap (10) can swivel round an axis (13) joined to the antipole of the magnet by a linkage, flap or extension being circular, elliptical, square or polygonal in the flap region. The flap itself can be flat or profiled, specifically in vane shape.

Description

The invention relates to a silencer for motor vehicles with an exhaust gas inlet pipe and an exhaust gas outlet pipe and several chambers provided in a housing, the form a series filter for the exhaust gas flow, and with one Throttle valve to reduce exhaust back pressure higher speeds.

Mufflers serve as part of an exhaust system Motor vehicle damping the intense noise of the intermittently from the exhaust pipe of a high-speed Ver Internal combustion engine (engine) exhaust gases. Of the permissible noise level is limited by regulations. The required noise insulation can be achieved through dissipative and Impedance silencers can be achieved. Mostly Combinations of both types are used.

Dissipative silencers (absorption and relaxation Silencers) convert sound energy directly into heat, generate little back pressure and appear relatively wide dig, but require at low frequencies (in the lower Speed range) large transverse dimensions.

Impedance silencers (resonance, reflection, interference Mufflers) provide sound insulation by placing them in the Introduce flow channel points with jumps in impedance (Cross-sectional jumps, coupled resonators, detours  and the like) on which sound waves can be reflected. However, these reflections only occur with very specific ones Frequencies on. Impedance silencers must therefore be matched become and appear relatively narrow-band.

It is therefore recommended to use a combination of different Damping mechanisms in a series filter with several Damping chambers ("acoustic filters") to use. By appropriately trained inline filters can handle the alternating pressures of the exhaust gas flow effectively smoothed and thus the outside urgent noise can be significantly reduced. Through the Reflections and diversions in the impedance attenuation chambers however, a relatively strong exhaust back pressure is created, which is considerable, especially at high speeds Loss of performance leads.

The back pressure and thus the loss of performance at high Reducing engine speeds has already been a two way Exhaust control suggested when using a control valve open an exhaust gas bypass passage in the main muffler can. For this purpose, the control valve is actuated by an actuator closed and opened a piston and a lever. The Actuator is connected to a membrane box, through which the Exhaust gas pressure measured in the pressure chamber of the main silencer becomes. At low pressure in the main muffler that remains Control valve closed so that the exhaust gas does not bypass can flow through and the noise in the main muffler be steamed the usual way. At higher speeds and the resulting increase in back pressure becomes the control valve til increasingly open via the actuator, so that a additional amount of exhaust gas can flow through the bypass and the Back pressure decreases accordingly. Thus, the Reduce power loss at higher speeds. The Arrangement of the actuator with diaphragm box, piston and Lever for actuating the control valve is relative  complex and thus leads to considerable costs increase. In addition, those with the familiar two-way Exhaust control achieved an increase in performance accessible for further improvement.

The object of the invention is therefore an effective reduction the power loss due to the exhaust back pressure at higher Speeds in a simple and inexpensive way possible.

This object is achieved with a silencer solved the type mentioned, in which the throttle valve through at least one magnet, preferably a permanent magnets, and / or at least one spring or the like. in is held in the closed position, and in which the Throttle valve can be opened via the exhaust gas flow.

The throttle valve is activated by the magnet and / or the spring at low speeds reliably in the closed position kept so that the noise is significantly reduced becomes. However, as soon as one by the strength of the magnet or the Exhaust gas back pressure determined is opened the throttle valve automatically, so that an additional Exhaust gas flow can flow away. External control of the Throttle valve and its own drive mechanism is not required. The opening movement of the Dampered flap to damage the flap system to avoid the suddenly opening flap. The opening speed of the flap can be adjusted via the Set the spring characteristic as desired.

According to a preferred embodiment of the invention Throttle valve in an essentially extension of the Exhaust gas inlet pipe arranged pipe section provided. The Throttle valve is thus in the direct exhaust gas flow, so that a  particularly effective back pressure reduction is achieved because for the exhaust gas flow flowing through the open throttle valve no redirection is required. This creates in essentially no exhaust back pressure. Of course lies it within the scope of the invention that the throttle valve receiving pipe section also slightly to the exhaust Input tube can be arranged offset.

According to the invention, the throttle valve is also accommodated Pipe section in the exhaust pipe over, so that also build-up of counter pressure is avoided at this point.

Since only a partial flow of the exhaust gas is opened when the throttle valve is open through the pipe section receiving the throttle valve drains off, while the remaining exhaust gas in the chambers of the Muffler is deflected and damped in the usual way, it is necessary to recycle these two exhaust streams merge. In a preferred development of The invention therefore surrounds the exhaust gas outlet pipe which Throttle valve receiving tube section at least in its End range and the exhaust gas flow directed through the chambers can via a between the exhaust pipe and the Throttle valve receiving pipe section provided Annular gap or the like flow into the exhaust gas outlet pipe.

In another embodiment of the invention there are two Exhaust pipes are provided through which the main exhaust gas flow or Partial stream can be discharged separately to the outside.

In another preferred embodiment of the invention the throttle valve in the exhaust pipe system arranged, from which a partial pipe leads into the chamber housing, the pipe section receiving the throttle valve directly is connected to the exhaust pipe.  

According to the throttle valve is in the pipe section an axis is pivotally mounted, and the axis of rotation is over a lever mechanism connected to a magnetic counter plate.

The throttle valve can be circular, elliptical, square, be polygonal or the like. As long as a simple one Swiveling is guaranteed. The same applies self-ver of course for the pipe section receiving the throttle valve at least in the area of the valve holder.

According to a particularly simple embodiment, the Throttle valve, but it can support the Opening movement also be profiled and points to this especially a wing profile.

According to the invention, the axis of rotation can be the throttle valve receiving pipe section or in a separate housing or the like. Be stored.

To close the engine speed as the engine speed decreases Throttle valve effect in this speed range there is a higher noise reduction, the throttle valve via a spring from the open to the closed Position traceable. Again is about the spring curve adjustable at which exhaust gas back pressure the throttle valve again closes.

In one embodiment of the invention, the throttle valve is a additional damping spring assigned to the valve system protect from damage and to ensure a more even To achieve opening or closing movement. This will driving comfort increases.

To a particularly when closing the throttle valve to enable reliable coupling of the magnet  this in a further development of the invention is movably mounted, so that he can adapt to the opposite side.

To reduce the temperature load from the hot exhaust gas gladly, is in a preferred embodiment of the invention provided that the valve holder, the lever mechanism, the magnet and / or the spring (s) in a separate, preferably not through the exhaust gas flow chamber or outside of Chamber housing or the exhaust pipe are provided.

Given the in and around the exhaust pipe and the muffler prevailing high temperatures is also according to the invention provided that the throttle valve, the valve holder, the Lever mechanism, the magnet and / or the spring (s) high are temperature resistant.

Further training, advantages and possible applications of Invention also result from the following description of exemplary embodiments and the drawing. Thereby everyone described and / or illustrated features for himself or in any combination the subject of Invention, regardless of its summary in the Claims or their relationship.

Show it:

Fig. 1 shows a schematic longitudinal section through a sound-damping system according to the present invention,

Fig. 2 shows a section along the line II-II in Fig. 1,

Fig. 3 shows a section along the line III-III in Fig. And

Fig. 4 is a schematic partial section through a second embodiment of the present invention.

Referring first to FIGS. 1 to 3, a muffler 1 has a housing 2 and an exhaust muffler on the fed via an exhaust gas inlet tube 3, an exhaust gas stream SE from a motor not shown and from which an exhaust gas outlet pipe 4, an exhaust gas stream SA is dissipated to the free atmosphere.

The pressure of the inlet-side exhaust gas flow SE supplied from the exhaust pipes combined in the exhaust manifold of the individual cylinders of the internal combustion engine to the exhaust gas inlet pipe 3 of the muffler 1 is a few atmospheres above that of the free atmosphere. It arrives intermittently (at every exhaust valve game), forming sound waves that are 5 to 10 times faster than the exhaust gas flow, at the muffler. The sound wave leads to compressions and dilutions propagating at the speed of sound in the almost uniformly flowing exhaust gas stream, so that the exhaust impulses are composed of a medium direct flow and an alternating flow. Since only the AC components are audible, it is important to build the exhaust system so that the AC flow, which consists of a mixture of different frequencies, is blocked or at least reduced, while the DC components can flow away without resistance if possible. For this purpose, the exhaust gas flow SE is first led from the exhaust gas inlet pipe 3 into a perforated pipe 5 , from which it flows radially into the chambers K1, K2 and K3 through the perforation openings, not shown, and also into the chamber K3 through the end axial opening of the perforated pipe 5 can leak.

The chambers K1 and K2 are absorption dampers in which the sound energy is converted into heat by friction against a porous sound absorbent material 6 (glass wool, steel wool or the like). In the chamber K3, a reflection damper, the sound is damped without generating heat. This is done by reflections on the walls of the chamber K3, from which the exhaust gas flow is forwarded via a deflection pipe 7 with a 180 ° deflection of its direction into a further chamber K4 and from there through a further deflection pipe 8 with another 180 ° deflection into a chamber K5 . The exhaust gas flow enters the exhaust gas outlet pipe 4 from the chamber K5 and from there into the free atmosphere.

At the chamber K3, in extension of the exhaust gas inlet pipe 3 and the perforated pipe 5, a pipe section 9 connects to the exhaust pipe 4 , the latter overlapping the pipe section 9 in its last section. In this case, an annular gap 16 is left free between the pipe section 9 and the exhaust gas outlet pipe 4 , through which the exhaust gas flow directed into the chamber K5 can enter the exhaust gas outlet pipe 4 and then exit into the free atmosphere.

The annular gap 16 can have any shape that depends on the shape of the pipe section 9 and the exhaust gas outlet pipe 4 . In the embodiment shown in FIG. 3, the pipe section 9 is square, while the exhaust gas outlet pipe 4 is cylindrical. This results in the shape of the annular gap 16 shown in FIG. 3. The pipe section 9 and the exhaust gas outlet pipe 4 can, however, also have any other shapes, as long as the annular gap 16 formed between them is sufficiently large to let the exhaust gas flow through.

In another embodiment, not shown, the exhaust gas flow is conducted, for example, by extending the deflection tube 8 directly to the outside, so that no annular gap 16 is required. Due to the fact that there is no further deflection, the soundproofing properties are of course somewhat impaired.

In the pipe section 9 , a throttle valve 10 is pivotally mounted. The throttle valve 10 is held in its closed position by a magnet 11 , preferably a permanent magnet. In addition, a spring 12 is provided which also holds the throttle valve 10 in its closed position.

As can be seen in particular from FIG. 2, the throttle valve 10 is mounted so as to be pivotable about an axis 13 , the axis bearing of the axis 13 being able to take place in the pipe section 9 or in a separate housing (not shown) provided around the pipe section 9 . The axle receptacle can also be part of the throttle valve 10 or can be designed as a separate part. The axis 13 is connected via a lever mechanism 14 , to which the spring 12 also expediently acts, to a magnetic counter plate 15 , on which the magnet 11 acts. The magnet 11 and the magnetic counterplate 15 can be fastened by screwing, crimping or the like. Advantageously, the magnet 11 is pivotally mounted so that it can exactly adapt to the position of the magnetic counter plate 15 and a maximum holding force is achieved. Of course, instead of a single magnet 11 , two or more magnets 11 can also be provided, which are arranged, for example, on both sides of the flap 10 .

The throttle valve 10 and the pipe section 9, at least in the section receiving the throttle valve 10, are square. However, they can also have a circular, elliptical, polygonal or other shape, as long as it is ensured that the throttle valve 10 is freely pivotable in the pipe section 9 .

In order to support the opening movement of the throttle valve 10 , it has a wing profile. However, it can just as well be flat or have a different profile.

At low speeds, the throttle valve 10 is closed and the exhaust gas flow flows through the chambers K3 to K5. If the engine speed and thereby the amount of exhaust gas introduced into the exhaust are increased, the reflections and deflections in chambers K3, K4 and K5 result in an increasing exhaust gas back pressure. As soon as this exhaust gas back pressure exceeds a predetermined by the strength of the magnet and / or the spring 12 , so that the force of the magnet 11 and the spring 12 is no longer sufficient to hold the throttle valve 10 in its closed position, it opens up to the position shown in dashed lines in Fig. 1. The opening movement is damped in a controlled manner by the characteristic curve of the spring 12 in order to prevent damage to the flap mechanism. Through a suitable selection of the spring characteristic, a continuous opening of the throttle valve 10 can be achieved. When the throttle valve 10 is opened , part of the exhaust gas flow can escape directly through the pipe section 9 into the exhaust gas outlet pipe 4 , so that the back pressure which forms in the chamber K3 and the power loss of the engine caused thereby is reduced.

If the engine speed and thus the back pressure in the chamber K3 is reduced again, the throttle valve 10 is closed again by the spring 12 , an additional spring (not shown) being able to dampen the closing movement. The closing process of the throttle valve 10 can also be set in a targeted manner by selecting the characteristic curve of this spring (not shown).

As is apparent from FIGS. 1 and 2, the axle of the throttle valve 10, the lever mechanism 14, the magnet 11 and the spring 12 outside of the pipe section 9 in a chamber K6 are disposed of the housing 2, which is not flowed through by the exhaust gas stream. The temperature load of these elements is thus reduced by the hot exhaust gas. Nevertheless, the flap holder, the lever mechanism 14 , the magnetic plate 15 , the magnet 11 and the spring 12 are made of high-temperature resistant material.

In the second embodiment of the invention shown in FIG. 4, a throttle valve 17 is arranged in an exhaust pipe 18 in front of the muffler or housing 2 . The exhaust pipe 18 branches in front of the housing 2 into a partial pipe 3 which corresponds to the exhaust gas input pipe and which leads the exhaust gas flow SE into the housing 2 , and a pipe section 19 which receives the throttle valve 17 and which passes the housing 2 to the exhaust gas output pipe 4 leads. The throttle valve 17 is held in the same way as the throttle valve 10 described above, so that a detailed description of the individual elements is not necessary again. The structure of the housing 2 corresponds to that of the exhaust pot described above except for the fact that the pipe section 9 with the throttle valve mechanism and the chamber K6 surrounding it can be dispensed with.

With the invention it is possible to reduce the exhaust gas back pressure and thus the power loss at higher speeds in a simple manner by the throttle valve 10 , 17 opens automatically and part of the exhaust gas flow can be discharged into the atmosphere without Umlenkun conditions. At lower speed, in which the noise reduction is of greater importance, however, the throttle valve 10 , 17 is closed, so that the noise is largely eliminated by the deflections of the entire exhaust gas flow.

Reference list

1 silencer
2 housings
3 exhaust gas inlet pipe
4 exhaust pipe
5 perforated tube
6 sound absorbing material
7 deflecting tube
8 deflecting tube
9 pipe section
10 throttle valve
11 magnet
12 spring
13 axis
14 lever mechanism
15 magnetic disk
16 annular gap
17 throttle valve
18 exhaust pipe
19 pipe section
K1 chamber
K2 chamber
K3 chamber
K4 chamber
K5 chamber
K6 chamber
SE inlet-side exhaust gas flow
SA exhaust gas flow on the output side.

Claims (15)

1. Muffler for motor vehicles with an exhaust gas inlet pipe ( 3 ), an exhaust gas outlet pipe ( 4 ) and several chambers provided in a housing 2 (K1, K2, K3, K4, K5) which form a series filter for the exhaust gas flow, and with a throttle valve ( 10 , 17 ) for reducing the exhaust gas back pressure at higher speeds, characterized in that the throttle valve ( 10 , 17 ) by at least one magnet ( 11 ), preferably a permanent magnet, and / or at least one spring ( 12 ) or the like is held in the closed position and that the throttle valve ( 10 , 17 ) can be opened via the exhaust gas flow. 2. Silencer according to claim 1, characterized in that the throttle valve ( 10 ) is provided in a substantially in extension of the exhaust gas inlet pipe ( 3 ) arranged pipe section ( 9 ). 3. Muffler according to claim 2, characterized in that the throttle valve ( 10 ) receiving pipe section ( 9 ) merges into the exhaust gas outlet pipe ( 4 ). 4. Muffler according to claim 2 or 3, characterized in that the exhaust gas outlet pipe ( 4 ) surrounds the throttle valve ( 10 ) receiving tube section ( 9 ) at least in its end region, and in that between the exhaust gas outlet pipe ( 4 ) and the annular gap ( 16 ) or the like provided to the pipe section ( 9 ) receiving the throttle valve ( 10 ). The exhaust gas flow conducted through the chambers (K3, K4, K5) can flow into the exhaust gas outlet pipe ( 4 ). 5. Muffler according to claim 2 or 3, characterized in that two exhaust gas outlet pipes ( 4 ) are provided, via which the main exhaust gas stream and the exhaust gas partial flow flowing through the pipe section ( 9 ) are discharged separately to the outside. 6. Muffler according to claim 1, characterized in that the throttle valve ( 17 ) is arranged in the exhaust gas-carrying pipeline system ( 18 ), of which a partial pipe ( 3 ) leads into the chamber housing ( 2 ), and in that the throttle valve ( 17 ) receiving pipe section ( 19 ) is connected directly to the exhaust gas outlet pipe ( 4 ). 7. Throttle valve according to one of claims 2 to 6, characterized in that the throttle valve ( 10 , 17 ) in the tube section ( 9 , 19 ) about an axis ( 13 ) is pivotally mounted, and that the axis ( 13 ) via a lever mechanism ( 14 ) is connected to a magnetic counter plate ( 15 ). 8. Silencer according to one of claims 1 to 7, characterized in that the throttle valve ( 10 , 17 ) and / or the pipe section receiving it ( 9 , 19 ) is circular, elliptical, square or polygonal at least in the region of the valve holder. 9. Silencer according to one of claims 1 to 8, characterized in that the throttle valve ( 10 , 17 ) has a flat or profiled design, in particular a wing profile. 10. Muffler according to claim 7, characterized in that the axis ( 13 ) in which the throttle valve ( 10 , 17 ) receiving tube section ( 9 , 19 ) or in a separate housing or the like. 11. Silencer according to one of claims 1 to 10, characterized in that the throttle valve ( 10 , 17 ) via a spring ( 12 ) from the open to the closed position is returnable bar. 12. Silencer according to one of claims 1 to 11, characterized in that the throttle valve ( 10 , 17 ) is associated with an additional union damping spring. 13. Silencer according to one of claims 1 to 12, characterized in that the magnet ( 11 ) is movably mounted. 14. Silencer according to one of claims 1 to 13, characterized in that the flap seat, the lever mechanism ( 14 ), the magnet ( 11 ) and / or the spring ( 12 ) in a separate, preferably not flowed through by the exhaust gas chamber (K6 ) or outside the chamber housing ( 2 ) or the exhaust pipe ( 3 , 18 ) are provided. 15. Silencer according to one of claims 1 to 14, characterized in that the throttle valve ( 10 , 17 ), the flap receptacle ( 13 ), the lever mechanism ( 14 ), the magnet ( 11 ) and / or the spring ( 12 ) resistant to high temperatures are.