EP1914398B1 - Exhaust gas back muffler - Google Patents

Description

The invention relates to an exhaust gas silencer for an internal combustion engine according to the preamble of claim 1.

From the DE 197 43 446 C2 an exhaust system for an internal combustion engine with a rear silencer is known in which a gas outlet from a second silencer is temporarily closed and that the second silencer serves as a resonator with the gas outlet closed.

From the WO 02/01049 A a muffler is known with a shell, wherein the shell is bounded by a side wall and having a main inlet for incoming exhaust gases and a main outlet for outgoing exhaust gases, wherein at least one closed-wall line is provided which passes through the shell and at both ends thereof outside the shell through an opening formed in the side wall, the or each duct being connected to the side wall around its circumference, a valve being provided to control the cooling of the exhaust gas.

The EP 1 321 639 A2 describes a sound damping device with a muffler housing having at least one Abgaseinrittsöffnung and at least two exhaust gas outlet openings, to reduce the back pressure with sufficient sound attenuation at the same time a substantially straight first exhaust pipe is provided which connects an exhaust gas inlet opening with a first exhaust gas outlet and the interior of at least one opening with the Inside the muffler housing is in communication, wherein in the flow direction behind the openings a shut-off device is arranged, which is adjustable between a the exhaust gas flow through the first exhaust gas outlet opening at least partially disabling and this releasing position.

The DE 41 40 429 is concerned with a muffler for vehicles in particularly cramped installation situations, wherein the muffler has a perforated transverse walls in three chambers housing, of which the first chamber filled as inlet chamber and the last chamber as outlet chamber with absorbent and the intermediate chamber is formed as a resonator chamber and is provided with at least one housing the snake-shaped penetrating exhaust pipe.

The object of the invention is to provide an exhaust gas muffler for a motor vehicle, which has a simple to manufacture and assemblable structure and which generates a damped or unattenuated exhaust noise as a function of an exhaust valve position.

This object is achieved by the features of claim 1. Further advantageous features include the subclaims.

The advantages achieved by the invention are that a desired damped and unattenuated exhaust noise during driving can be generated by a closed or open exhaust flap through the internal structure of the exhaust gas muffler. This noise optimization is carried out by the exhaust muffler comprises two exhaust guide tubes, wherein the first exhaust pipe inside the exhaust muffler has an opening for forced exiting exhaust gases from the second exhaust pipe with the shut-off valve closed, in which the exhaust gases of the internal combustion engine can flow directly.

So that a damped exhaust noise can be achieved when the exhaust control flap is closed, the second exhaust pipe for discharging exhaust gases is provided with closed shut-off valve with two perforated pipe sections, which are arranged in each of a second and third chamber of the exhaust gas muffler. The now forcibly deflected exhaust gas stream flows through the perforated pipe sections of the exhaust pipe in such a way that a first chamber of Abgasnachschalldämpfers in which the mouth opening of the first exhaust guide tube is arranged, perforated with a holes bottom toward the second chamber and a chamber surrounding the perforated sheet metal pot surrounded by insulating material all around. Furthermore, the downstream subsequent third chamber is closed by bottoms, in which a further perforated pipe section of the second exhaust pipe is arranged and which is directly surrounded by an insulating material. The further perforated pipe section of the second exhaust pipe is arranged corresponding to a perforated pipe section of the first exhaust pipe in the third chamber of the exhaust gas muffler.

In the case of a closed exhaust-gas barrier flap, the branched-off exhaust-gas flow is introduced into the perforated pipe section of the first exhaust-gas guide pipe via the one perforated pipe section of the second exhaust-gas guide pipe into the inlet opening of the first exhaust-gas guide pipe and the further branched exhaust gas stream via the other perforated pipe section in the third chamber.

By cladding with insulation material of a perforated pipe section of the exhaust pipe, a sound insulation is achieved. About the sheet metal surrounding the insulating material both a sound absorption and a thermal protection is achieved in such a way that no discoloration of the exhaust gas muffler or the pot takes place.

An embodiment of the invention is illustrated in the drawing and will be described in more detail below. The drawing shows a section through a Exhaust rear silencer with the two exhaust guide tubes and the individual chambers.

The exhaust gas muffler 1 essentially comprises two mufflers S1 and S2, which are arranged separately from one another via a closed bottom 2 and have the same structure, so that only the one muffler is described.

The exhaust gas guide tubes 3 of the exhaust gas muffler are each connected to an exhaust port of an internal combustion engine, which is not shown. The exhaust gases are directed in the direction of the arrow through exhaust guide tubes 3 and depending on the position of an exhaust flap 4 in the exhaust pipe 5 through a further exhaust pipe 6.

The exhaust gas guide tubes 6 and 3 are substantially held within the exhaust gas muffler 1 in trays 7, 8, 9, which divide the chambers K1, K2 and K3. The first exhaust gas guide tube 6 has an inner mouth opening 10 which lies in the chamber K1 and it extends through the two adjoining chambers K2 and K3 and opens outwards.

The second exhaust pipe 3 extends from an outer mouth 20 through the chambers K1, K2 and K3 and also opens out into the exhaust pipe 5 with the inner exhaust valve 4 a.

This second exhaust pipe 3 has in the second chamber K2 a perforated, that is provided with holes pipe region R1, which is surrounded by a perforated metal basket 11. This is covered all around with material 12, which extends to the shell 10 of the exhaust gas muffler. Between the perforated pipe region R1 and the metal basket 11, a distance is provided. A subsequent tube region R2 of the exhaust gas guide tube 3 is perforated, that is, executed with holes which are directly surrounded by insulating material 12a. Corresponding with In the same chamber K3, a tube region R3 of the first exhaust gas guide tube 6 is perforated, ie provided with holes, in this tube region R2.

With the exhaust flap 4 open (shown in phantom), the exhaust gases from the engine can flow unattenuated through the exhaust guide tubes 3 and 6 to the outside. With the exhaust flap 4 closed, however, the exhaust gases forcibly flow only through the perforated pipe sections R1 and R2 of the second exhaust pipe 3 on the one hand through a partition wall 7 provided with holes 15 between the two chambers K1 and K2 to the mouth opening 10 and on the other hand through the perforated pipe section R3 of the first exhaust pipe 6. At the same time takes place on the outflow of exhaust gases through the insulating material 12, 12 a, a muffled exhaust noise.

Claims (3)

1. Rear muffler for an internal combustion engine, with a first and a second muffler through which exhaust gases flow and which are separated from one another and have in each case an exhaust gas delivery and discharge through an exhaust gas routing pipe issuing into an exhaust pipe which follows downstream and in which an exhaust gas shutoff flap which can be closed temporarily is arranged, the rear muffler (1) comprising two exhaust gas routing pipes (3, 6), the first exhaust gas routing pipe (6) having within the rear muffler (1) an issue orifice (10) for exhaust gases emerging positively from the second exhaust gas routing pipe (3), with the exhaust gas shutoff flap (4) closed, into which first exhaust gas routing pipe the exhaust gases from the internal combustion engine flow directly, characterized in that the second exhaust gas routing pipe (3) has for the positive discharge of exhaust gases, with the exhaust gas shutoff flap (4) closed, two perforated pipe sections (R1, R2) in each case in a second and a third chamber (K2, K3) of the rear muffler (1), in that a first chamber (K1) of the rear muffler (1), in which chamber (K1) the issue orifice (10) of the first exhaust gas routing pipe (6) is arranged, has a bottom (7) perforated with holes toward the second chamber (K2) and a perforated sheet metal pot (11) which surrounds the chamber and which is surrounded all round by insulating material (12), and in that the third chamber (K3) following downstream is closed off by bottoms (8, 9) in which a further perforated pipe section (R2) of the second exhaust gas routing pipe (3) is arranged and is surrounded directly by an insulating material (12a).
2. Rear muffler according to Claim 1, characterized in that the further perforated pipe section (R2) of the second exhaust gas routing pipe (B) is arranged, so as to match a perforated pipe section (R3) of the first exhaust gas routing pipe (6), in the third chamber (K3).
3. Rear muffler according to Claim 1 or 2, characterized in that, with the exhaust gas shutoff flap (4) closed, the branched-off exhaust gas stream flows via one perforated pipe section (R1) of the second exhaust gas routing pipe (3) into the issue orifice (10) of the first exhaust gas routing pipe (6), and the further branched-off exhaust gas stream flows via the other perforated pipe section (R2) in the third chamber (K3) into the perforated pipe section (R2) of the first exhaust gas routing pipe (6).

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