DE9010744U1 - Catalyst for Trabant - Google Patents

Description

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Catalyst for Trabant

The object for which protection as a utility model is being applied for is a catalyst for the Trabant passenger car of the 601 series with an air-cooled 2-cylinder 2-stroke engine. The task of the catalyst for the Trabant is to largely and permanently remove harmful components (carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides) from the exhaust gases coming out of the engine.

Dtii= Modr ¹ ! Traba . .':, 601 was produced in large numbers with the 2TaUt-Wc-L-; in the last ^two decades. A version with a catalyst for Trabant to purify exhaust gases was not available from the manufacturer. The activities to improve exhaust gases were limited exclusively to engine-related measures in the area of mixture formation, ignition and charge exchange; the applicant is not aware of any car with a 2-stroke engine that was delivered or retrofitted with a catalyst for Trabant. Research with manufacturers of catalyst carriers and coaters has shown that catalysts have so far only been combined with small-volume 2-stroke engines in mopeds and light motorcycles as well as in chain saws or similar.

Solutions already presented for the Trabant 601 have the disadvantage that either

1. the catalytic converter for the Trabant is positioned too far away from the engine and/or is too large and therefore starts too late or not at all.

or

2. the catalytic converter is too small for the Trabant and therefore costs a lot of power and causes the engine to ring loudly.

or

3. the catalyst for the Trabant is too close to the engine and therefore ' .· gets hot and ages quickly.

or

4. the catalyst for Trabant is located in a place where the ground clearance is severely affected or

5. the catalyst for Trabant has to be welded on and is therefore not easy to install,

or

6. the catalytic converter for Trabant has at least one flange, which means that a counter flange must be welded to the standard exhaust pipe.

The task to be solved contains the following problem:

1. A catalyst has the property of only becoming effective above a certain operating temperature, the so-called light-off temperature.

2. Heating is done by the engine exhaust gases. In order to start as quickly as possible, the catalyst should be as small as possible and positioned as close to the engine as possible

3. However, in order to achieve the highest possible conversion rate (conversion of the harmful exhaust gas components), the catalyst must be as large as possible. A large catalyst, however, starts more poorly due to its greater heat absorption capacity.

■1 . The service life of a catalyst depends heavily on its thermal stress. The arrangement close to the engine and a high conversion rate result in high temperatures in the catalyst and thus reduce its service life.

In addition, the 2-stroke engine, due to its high hydrocarbon content in the exhaust gas, generates high temperatures, particularly in the oil flow, as a result of exothermic reactions in the catalyst.

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starts up as quickly as possible (after just 250 s in the US cycle), does not get too hot (immediately after the catalyst has started up, a maximum of 850 degrees C at full load) and still achieves a high cleaning effect (in the European cycle (cold test) at least 30 % for CO, HC and NOx, in the European cycle (hot test, catalyst started up) at least 80% for CO and HC).

6. Further demands were:

6.1. Easy installation and easy replacement

6.2. Functional design and arrangement

6.3. Sufficient service life (after 30 000 km in the European cycle

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6.4. Power loss less than or equal to 5%

6.5. Slight reduction in ground clearance (maximum 15 mm)

6.6. Low price

As can be seen from the problem, an optimal compromise solution had to be developed with due consideration of the individual requirements.

The catalyst described below is the result of a long series of tests and measurements, which culminate in a 30,000 km continuous full-load test under official supervision.

The task was solved by a cylindrical catalyst with a metal carrier (number of cells: 200 cpsi, dimensions 74.5 x 70, coating Pt/Rh 5:1), which is connected to cones and pipe sockets at both ends. The internal angle L of the cones was chosen to be large so that the installation length is as short as possible and the pni-nViut rnmitntf ^{the catalyst} is as low as ^possible .

Because the pipe sockets are each placed on their counterparts, a constriction in the pipe area is avoided. In order to be able to install the catalytic converter in a standard vehicle, the front bend of the exhaust intermediate pipe must be completely cut off (<~a. 160 mm). The pipe ends of the standard exhaust system extend so far into the slotted pipe sockets on the catalytic converter that ^a sufficient overlap area (approx. 20 mm) is created from the end of the slots to the end of the standard pipes. This overlap ensures adequate gas sealing, which makes additional sealing measures unnecessary. The clamps in the area of the slots only have a clamping function and not a sealing function.

The clamp connection allows the catalyst to be easily installed and removed, making it easy to replace it or remove contamination if necessary.

The front clamp is positioned so that a holder for the safety suspension can be attached to the screw. This means that there is no need to weld a holder onto the catalytic converter. In addition, the rubber retaining ring can always be optimally positioned and pre-tensioned by turning the clamp, regardless of the installation tolerances. The compact external dimensions of the catalytic converter mean that it can be installed directly after the front silencer next to the engine mount and in front of the wishbone on the front axle. The floor

clearance is only reduced by 15 mm at the lowest point. This is of minor importance because the point is in the area of the front axle and not in the overhang or between the axles.

Furthermore ^, the catalytic converter is specially designed and arranged so that ^it is located at the rear of the vehicle. Additional shielding measures are therefore not necessary.

Representation of the catalyst for Trabant

An example of the catalyst is described using the figures 1 and 2, < &eegr; Photo explains the installation situation on the vehicle: Shown are:

Figure 1 the side view of the catalyst for Trabant Figure 2 the front view of the catalyst for Trabant with clamp and holder

In Figure 1, the cylindrical catalyst body with metal carrier insert is marked (0). Welded to it are short cones (1) + 2), to which slotted pipe sockets (3) and (4) are connected. While the pipe socket (3) is arranged centrally on the gas inlet side, the pipe socket (4) on the gas outlet side forms an angle with the catalyst axis.

In Figure 2, the cylindrical cone (1) and the pipe socket (3) can be seen from the front. Also shown are the rotatably arranged clamp (5) and the holder (6) onto which the retaining rubber is attached.

List of reference symbols

0 - Metal carrier insert

1 - Cylindrical cone

2 - Cone

3 - Pipe socket (centric)

4 - Pipe socket/gas outlet side (angled)

5 - Clamp

6 - Cold

7 - Hexagon screw M8 x 75

8 - Washer for M 8 (3 mm thick)

9 - Washer for M 8 (3 mm thick)

- Washer for M 8 (1.5 mm thick) - Stop nut M 8 (SW 12)

Claims (8)

Protection claims 1. Catalyst for Trabant in cylindrical construction (0) with metal support _which is welded at both ends by ^cones (1) and (2) and pipe sockets (3) and (4), characterized in that the cones (1) and (2) are very short and of the pipe sockets one (3) is arranged centrally and the other (4) at a certain angle to the catalyst longitudinal axis. 2. Catalyst for Trabant according to claim 1, characterized in ( net that the cones (1) and {2) have an interior angle of 80 to 90 degrees. 3. Catalyst for Trabant according to claim 1 and 2, characterized in that the pipe socket on the gas inlet side (3) is arranged coaxially to the catalyst axis 4. Catalyst for Trabant according to one of claims 1 to 3, characterized in that the pipe socket on the gas outlet side (4) is arranged at an angle of 22 +/- 5 degrees to the catalyst longitudinal axis. 5. Catalyst for Trabant according to one of claims 3 and 4, characterized in that the pipe sockets (3) and (4) have an inner diameter of 35 +/- 0.5 mm and a length of at least 30 mm. 6. Catalyst for Trabant according to one of claims 3 to 5, characterized in that the pipe sockets (3) and (4) are provided at their ends with 2 to 4 locking slots of at least 10 mm length. 7. Catalytic converter for Trabant according to one of claims 1 to 6, characterized in that the angled pipe socket (4) has been pressed into an oval shape at its end facing the catalyst for Trabant so that it fits onto a cutting line created by surface separation (sawing, grinding, etc.) on the cylindrical cone and can be welded in the plane of the cutting line. 8. Catalyst for a catalyst according to one of claims 1 to 7, comprising a loose holder (6) which can be adapted to the installation tolerances by twisting it around the axis of the hexagon screw ₍ 7) and by twisting and/or axially shifting the clamp (5).