DE9217940U1 - Exhaust system for diesel vehicles - Google Patents

Description

"Exhaust system for diesel vehicles"

The invention relates to an exhaust system for diesel vehicles with an exhaust catalyst and a silencer in a housing in which a pre-chamber and a main chamber with sound-insulating fittings are provided.

It is known to arrange a suitable exhaust catalyst between the engine outlet and the muffler in exhaust systems for diesel vehicles. Known mufflers used consist of a housing and several chambers connected in series, whereby at least one pre-chamber without any installations is usually provided and the sound-absorbing installations are arranged in a single or multi-part main chamber. The actual metal or ceramic carrier of the exhaust catalyst is necessarily housed in its own housing, which is held to the vehicle body with special fastenings. In many diesel vehicles, the space behind the exhaust manifold of the diesel engine and the muffler is limited, so that

the housing of the exhaust catalyst is difficult. The very close arrangement of the exhaust catalyst behind the diesel engine means that, under varying load conditions, the exhaust catalyst is also exposed to the peak temperatures of the exhaust gas, particularly at high engine loads. In these high temperature ranges in particular, the problem of increased particle formation in the exhaust gas occurs, which is partly caused by the catalytic conversion of SO ₂ from the sulphur contained in the diesel fuel into sulphuric acid and sulphates, which accumulate on the soot particles, at these relatively high temperatures .

The object of the invention is to arrange the necessary exhaust gas catalyst in an exhaust system of the type mentioned at the beginning in a structurally favorable manner in the region of exhaust gas temperatures that are as homogeneous as possible .

This object of the invention is achieved with an exhaust system of the type mentioned at the outset, which is characterized in that the exhaust gas catalyst is arranged in the silencer housing between the pre-chamber and the main chamber.

With such a design, the size of the muffler housing and thus also the external fastening can be retained, so that such a combined muffler system can be retrofitted to diesel vehicles in a particularly favorable manner. The necessary reduction in the sound-insulating fittings is justifiable, since the exhaust catalyst also has a sound-damping effect. Since, according to the invention, the exhaust catalyst is arranged behind the pre-chamber in the muffler housing, which leads to turbulence and equalization of the exhaust gas temperature, the exhaust catalyst is no longer exposed to short-term temperature peaks in the exhaust gas, which reduces sulfate formation and thus also increased particle formation.

ized, especially when the exhaust system according to the invention is not operated at full load.

According to a preferred embodiment of the invention, a chamber free of installations is provided between the exhaust gas catalyst and the main chamber with access to the casing of the exhaust gas catalyst. This measure leads to a uniform temperature exposure of the exhaust gas catalyst in the radial and axial directions.

In an exhaust system according to claim 4, it is possible to avoid flow through the exhaust gas catalyst, especially in full-load operation when exhaust gas temperatures are reached that lead to increased sulfate formation and thus to increased particle formation, which could place a heavy load on the catalyst. The corresponding control can be carried out from the outside via an actuator according to claim 5.

The invention is explained in more detail below using an illustrated embodiment. The basic illustration shows

Fig. 1 a longitudinal section through a silencer with integrated exhaust catalyst,

Fig. 2 is a section along the line A-B in Figure 1, Fig. 3 is a section along the line C-D in Figure 1,

Fig. 4 a longitudinal section through a silencer

with integrated exhaust catalyst and a bypass system,

Fig. 5 a section along the line A-B in Figure 4

and

Fig. 6 is a section along the line C-D in Figure 4.

First, reference is made to Figures 1 - 3. The silencer shown with its housing 1 is part of an exhaust system of a diesel vehicle. The exhaust gas from the engine enters a pre-chamber 11 without any built-in components via the inlet 15, to which a chamber 12 is connected, which accommodates the exhaust catalyst 2 in its walls 121 and 122, approximately coaxially to the housing 1. The exhaust gases flow through this exhaust catalyst 2 and enter the chamber 12a, which is also without any built-in components, and can be distributed in this space and through the holes 122a in the chamber 12. This chamber 12a is followed by the main chamber 13, which is preceded by a sub-chamber 13a, which borders the chamber 12a with the chamber wall 131, which is perforated with the holes 132. From the chamber 12a, the exhaust gas flows partly through the holes 132 and partly through the sound-insulating fittings 14 to the sound-insulating perforated discharge pipe 16.

In a silencer according to Figures 4-6, a bypass guide is provided in the silencer housing 1 in addition to the exhaust gas guide through the exhaust gas catalyst 2' from the pre-chamber 11 to the main chamber 13. The pre-chamber 11 is separated by an additional chamber wall 18 in which the openings 181 and 182 are provided one below the other. A transition channel 21' to the exhaust gas catalyst 2' is connected to the opening 181, which in turn is accommodated in the walls 121 and 122. Both walls 121 and 122 are provided with openings 121a and 122a. A flap 19 that can be pivoted from the outside or a corresponding cover is arranged in front of the chamber wall 18, via which the inlet nozzles 191 and 192 can be closed, as can be seen in Figure 5. By pivoting this flap 19, if necessary via an actuator, the transition channel 21' or the opening 182 to the bypass 17 can be closed or opened as desired.

When the opening 182 is open, the exhaust gas flows from the pre-chamber 11 through the bypass designated overall by the number 17 through the holes 121a and 122a in the chamber walls 121 and 122 to the chamber 12a downstream of the exhaust gas catalyst 2' and from there in the manner already described to the sub-chamber 13a of the main chamber 13.

Z &ugr; s amme &eegr; _s t ejJ_ujig_jdgilJ3£L ^u gs &zgr; e &igr; che &eegr;

I Silencer housing

II Prechamber

12 Chamber 12a Chamber

121 Chamber wall 121a Hole

122 Chamber wall 122a Hole

1 3 Main chamber 13a Te i1 chamber

131 Chamber wall

132 Bore

133 Partition wall

14 sound-insulating pipes

15 Entrance

16 sound-insulating discharge pipe

17 Bypass

18 Chamber wall 181 breakthrough 182 breakthrough 19 .Flap 191 Inlet nozzle 192 Inlet nozzle 2, 2 ¹ Catalytic converter 21 ' Transition channel

Claims (5)

Protection claims 1. Exhaust system for diesel motor vehicles with exhaust catalyst and a silencer in a housing in which a pre-chamber and a main chamber with silencer-insulating fittings are provided, characterized in that the exhaust catalyst (2, ²¹ ) is arranged in the silencer housing (1) between the pre-chamber (11) and the main chamber (13, 13a) . 2. Exhaust system according to claim 1, characterized in that a chamber (12a) free of installations is provided between the exhaust gas catalyst (2, 2') and the main chamber (13, 13a). 3. Exhaust system according to one or more of the preceding claims, characterized in that the exhaust gas catalyst (2, 2') is accommodated in a chamber (12), the chamber walls (121, 122) supporting the exhaust gas catalyst (2, 2') being at least partially perforated. 4. Exhaust system according to one or more of the preceding claims, characterized in that the exhaust gas catalyst ( ²¹ ) is connected to the prechamber ( ¹¹ ) by a transition channel (211) and in the chamber wall (18) serving for the connection, in addition to the opening (181) for the connection, a further opening (182) is provided, which opens into a bypass (17) guided outside the exhaust gas catalyst ( ²¹ ) in the silencer housing (1), which leads to the chamber (12a) forming a buffer space, wherein both openings (181, 182) can be optionally closed from the outside via a flap (19) or cover. 5. Exhaust system according to claim 4, characterized in that the flap (19) or a corresponding closure panel can be actuated via an actuator.