DE4218523C1 - Catalyst appts. allowing easy operation of temp. - includes main exhaust gas line, thin by=pass line, exhaust gas line and control unit - Google Patents

Abstract

Catalyst appts. includes main exhaust gas line which joins into silencer housing via inlet opening, catalyst integrated in the silencer, a thin bypass line which branches off from the main gas line, exhaust gas line connected to the silencer outlet and a control unit. The silencer housing is divided by the catalyst housing into prim. and chamber. The main gas line enters the prim. chamber while the bypass line enters the secondary chamber. The catalyst inlet in located near the second inlet. The primary and secondary chambers are connected by openings. ADVANTAGE - The appts. design enables the operating temp. to be achieved quickly, but ensures that its critical temp. is not exceeded.

Description

The invention relates to a catalyst arrangement according to the Preamble of the main claim.

From DE-OS 14 76 508 a device is known in which a partial load in a chamber arranged in the exhaust pipe catalyst with high flow resistance and a full load catalyst lysator are arranged with low flow resistance. At The partial load catalytic converter becomes part load via a bypass line charged with exhaust gas. With increasing load an in opens the main exhaust pipe integrated valve, causing the exhaust to the full arranged in a ring around the part-load catalytic converter load catalyst is passed.

The object of the invention is a catalyst to create order with which on the one hand the necessary loading drive temperature reached as quickly as possible and on the other hand the critical temperature that is decisive for the service life is not is exceeded.

The object is achieved by the features of the kenn drawing part of the main claim solved.

The advantage of this arrangement is that the catalyst in two different ways with different heat exhaust gas can be applied. The short bypass Cable has a low mass and / or a small surface  on. As a result, relatively hot exhaust gas reaches the catalytic converter, where through this can be heated up quickly. On the other hand, be the main exhaust pipe has a large mass and / or surface che. In this way, the exhaust gas can be part of it Give off heat. In addition, the exhaust gas must also the entire Flow through the muffler housing, which means more energy is performed so that the exhaust gas arriving at the catalyst critical temperature for the catalyst does not exceed.

By controlling the switching flap, it is therefore possible that Controlling the ratio of hot to cooled exhaust gas and thus the catalyst body at a predetermined temperature hold. On the one hand, this improves efficiency and on the other whose the life of the catalyst.

Furthermore, the external insulation of the catalyst can be omitted, since the unmoved air in the silencer when the engine is switched off housing prevents rapid cooling of the catalyst. But the sound radiation of the catalytic converter is also affected by the on Order in the silencer housing reduced. Finally points this arrangement still has the advantage of a silencer close to the engine feranordnung on, whereby the noise reduction of the exhaust system can also be improved overall.

Further advantages and configurations can be found in the lower sub say, the description and the drawing, wherein

Fig. 1 is a schematic diagram of a catalyst arrangement according to the invention partially in section and

Fig. 2 shows another embodiment also partially in section.

Fig. 1 shows the exhaust system of an internal combustion engine 1 , which is connected to the main exhaust pipe 3 via an exhaust manifold 2 . In the main exhaust pipe 3 , which opens via an inlet opening 4 in a silencer housing 5 , a switching flap 6 is arranged. Upstream of the switching flap 6 , a bypass line 7 branches off from the main exhaust line 3 and also opens into the muffler housing 5 via a second inlet opening 8 . In the muffler housing 5 a space surrounded by a housing 9 catalyst 10 is integrated, whose incident flow opening 11 the two intake ports 4, faces 8 and its outlet opening 12 in a gastight manner with an exhaust pipe 13 is connected ver. Downstream of the muffler housing 5 , additional mufflers 14 can be provided in the gas pipe 13 .

Between the inlet openings 4 , 8 , a partition 15 , which connects the muffler housing 5 with the catalyst housing 9 in the area of the inflow opening 11 , is provided. The partition 15 and the catalyst housing 9 are angeord net such that the muffler housing 5 is separated into a first chamber 16 and a second chamber 17 , with a passage opening 18 being recessed on the side of the muffler housing 5 facing the flow opening 12 . In addition, baffles or sound-absorbing elements 19 can be provided for flow guidance in both chambers 16 , 17 .

At the start of the internal combustion engine 1 , the switching flap 6 is closed so that the exhaust gas is passed through the bypass line 7 into the muffler housing 5 . The bypass line 7 is designed such that the exhaust gas emits as little energy as possible on its way to the catalytic converter 10 . The second inlet opening 8 is arranged in the area of the inflow opening 11 of the catalyst 10 between the partition 15 and one of the baffle plates 19 , so that the exhaust gas passes directly into the catalyst 10 . The catalyst 10 is brought quickly to its necessary operating temperature by the hot exhaust gas, so that the exhaust gases can be optimally cleaned after a short time.

After the operating temperature has been reached, the switching flap 6 is opened partially or completely, so that part of the exhaust gas passes through the main exhaust gas line 3 and through the inlet opening 4 into the first chamber 16 . The main exhaust pipe 3 is designed such that the exhaust gas on its way to the silencer housing 5 already releases part of its energy. In the muffler housing 5 , the exhaust gas path to the Anströmöff opening 11 is blocked by the partition 15 . The exhaust gas must therefore flow through the entire first chamber 16 before it can enter the second chamber 17 via the passage opening 18 . Here, the exhaust gas must flow through the entire second chamber 17 in the opposite direction before it can reach the inflow opening 11 of the catalytic converter 10 . Thus, since the exhaust gas in this way until the entire muffler housing 5 has to pass through, it comes with a temperature below the lyst for the Kata 10 critical temperature, to that of Catalyst 10th By controlling the two exhaust-gas part-streams as a function of the catalyst temperature, it is possible to keep the Kata lyst 10 under all operating conditions at its optimum operating temperature, which leads to a significant increase in the life of the catalyst 10th Of course, the control of the switching flap 6 can also be carried out depending on the exhaust temperature, the cooling water temperature, the gas back pressure, the engine load, the engine speed or any other operating parameters. The maximum temperature of the catalytic converter 10 can be limited by appropriate dimensioning of the bypass line 7 or by an additional switching flap arranged in the bypass line 7 .

This arrangement also improves the noise reduction of the entire exhaust system, since, on the one hand, a close-to-engine arrangement of the first muffler 5 desired for the noise reduction can be realized; on the other hand, the noise emission of the catalytic converter 10 itself can be reduced by the integration into the first silencer housing 5 . In addition, thermal insulation of the catalytic converter 10 can also be dispensed with, since the stationary air in the muffler housing 5 prevents rapid cooling of the catalytic converter 10 when the engine is at a standstill.

FIG. 2 shows a further exemplary embodiment of a catalytic converter arrangement according to the invention, the same parts as in FIG. 1 being identified by the same reference numbers. In contrast to Fig. 1, the Schallufferge housing 5 and the second muffler 14 are made in one piece and only separated from one another by a wall 20 . The connection between the two silencers 5 , 14 takes place via a short exhaust pipe 13 , which is gas-tightly connected to the outflow opening 12 of the catalytic converter 10 and opens into the second silencer 14 . As a result, this arrangement also ensures that the entire exhaust gas flows through the catalytic converter 10 .

Claims (6)

1. Catalyst arrangement consisting of
a main exhaust pipe which opens into a silencer housing via an inlet opening,
- a catalytic converter integrated in the silencer housing,
a thin bypass line that branches off from the main exhaust line and opens into the muffler housing via a second inlet opening,
an exhaust pipe which is connected to the outflow side of the catalytic converter, so that the entire exhaust gas flow can leave the silencer housing only after flowing through the catalytic converter,
a control device which is arranged downstream of the branching of the bypass line in the main exhaust line for setting the mass flow as a function of operating parameters,
characterized in that the silencer housing ( 5 ) is separated by the catalyst housing ( 9 ) into a first ( 16 ) and a second chamber ( 17 ), that the main exhaust line ( 3 ) opens into the first chamber ( 16 ), that the bypass line ( 7 ) opens into the second chamber ( 17 ) that the catalyst ( 10 ) with its inflow opening ( 11 ) is arranged in the region of the second inlet opening ( 8 ) in the second chamber ( 17 ) and that the first chamber ( 16 ) has a on the intake ports (4, 8) opposite side of the muffler housing (5) arranged passage opening (18) is in fluid communication with the second chamber (17). 2. Catalyst arrangement according to claim 1, characterized in that the bypass line ( 7 ) has a low mass and / or a ge ring surface. 3. A catalyst arrangement according to claim 1, characterized in that the control device designed as a switching flap ( 6 ) is controlled as a function of the catalyst temperature. 4. Catalyst arrangement according to claim 1, characterized in that in the muffler housing ( 5 ) baffles and / or sound-absorbing elements ( 19 ) are arranged. 5. A catalyst arrangement according to claim 1, characterized in that a second or further silencer ( 14 ) are provided in the exhaust pipe ( 13 ). 6. A catalyst arrangement according to claim 5, characterized in that both silencers ( 5 , 14 ) are made in one piece.