Cold run controller
The air systems (KLR) is a component which in older cars with petrol engine and controlled catalyst the emissions after a cold start is reduced. Since the emissions test before the Euro 2 standard did not include a cold start, many vehicles were not yet optimized for a low-emission start. A cold run controller helps such vehicles to have a lower-emission cold start.
functionality
As long as the engine, the catalytic converter and the lambda probe have not yet reached their operating temperature , the gasoline-air mixture is not completely burned or pollutants are not completely converted. In addition, the mixture is set significantly richer in the cold running phase. The exhaust gas therefore contains significantly more carbon monoxide (CO) and hydrocarbons (C x H y ) than in the operating temperature phase.
A cold run controller supplies the intake system with an additional air flow controlled by a valve during the cold run phase , which causes the mixture to become leaner and thus hotter combustion. At the same time, the idle speed is increased slightly, which ensures stable idling. Overall, the cold running phase is shortened and the overall pollutant emissions are reduced because the catalytic converter is brought to operating temperature more quickly.
The required amount of air is preset for the vehicle / engine on the air valve. Since the air valve opens and closes depending on the water temperature, it is installed in a convenient place in the small cooling circuit of the engine (typically in a water hose for heating the vehicle). Intervention in the engine control is not required.
When the cooling water has reached a certain temperature, the air valve closes and the additional air supply is ended.
In addition to the mechanical KLR, there is also an electronically controlled system. The difference is that the EGS control unit provides faster signal evaluation and control. By evaluating the lambda sensor signal, additional air is specifically supplied to the engine in connection with the GAT air control valve into the intake manifold. This ensures consistent running properties in the cold state (starting phase) as well as in the warm state (driving). Here, too, the general restrictions on use apply as with the mechanical KLR.
Installation
Before installation, the vehicle should undergo a separate catalytic converter test to check that the catalytic converter is functioning properly. If the catalytic converter does not (or no longer, e.g. due to aging) achieve the required effect for classification in a new pollutant class, installing a cold-running controller would be pointless. The catalytic converter test ensures that a change acceptance, which de facto certifies an improved emission behavior, is also valid. If the catalytic converter is restricted in its effectiveness (e.g. due to aging or damage), no reliable statement can be made about the actual emission behavior of the vehicle. Contrary to the often held opinion that the catalytic converter test is purely a matter of form, it is an essential part of the examination of the vehicle as part of the change acceptance. The form for the catalytic converter test enclosed by the manufacturers, however, does not necessarily have to be filled out, and it is also not necessary to submit it to the road traffic authority.
It is also clear in which engines a KLR cannot be used: This applies to all engines whose controls record the intake manifold pressure and can compensate for the additional KLR air by adjusting the throttle valve or an additional air slide in the opposite direction. The KLR would therefore be ineffective.
The same applies to all engine controls with speed stabilization via air-side correction (again via throttle valve or additional air slide). Here, the KLR speed increase would be recognized and also compensated.
The KLR cannot be used for engine controls with ignition-side or air-ignition-side speed correction. This would result in unpredictable control loop overlaps.
advantages
The KLR is usually retrofitted in order to achieve a classification in a better emission class, which can result in significant savings in vehicle tax . The tax saving is proportional to the displacement. The upgrade is possible only in vehicles, serially produced a controlled catalytic converter factory Euro-1 have norm, to reach the Euro 2 or D3 standard. The installation of a KLR is also worthwhile for older vehicles, as the investment usually pays for itself after a few years due to the tax saved.
disadvantage
There are no direct disadvantages. Only the built-in parts of the KLR should be checked regularly for correct fit and firmness.
environmental Protection
Cold run controllers are used exclusively to reach the operating temperature more quickly. Only here is a contribution to environmental protection achieved by reducing pollutant emissions directly after a cold start.
In the subsequent operation and especially under real operating conditions, cold running controllers have no influence on the pollutant behavior of the vehicle.
In contrast, there are emissions from the manufacture, sale and installation of the system.
Alternatives
For vehicle models with emission class Euro 1, for which no KLR is available, or for vehicles with a defective catalytic converter, upgrade or exchange catalytic converters are ideal. This variant is quite costly, since the existing catalytic converter is exchanged for a technically improved copy. However, an upgrade catalytic converter reduces pollutant emissions even after the operating temperature has been reached.
Since KLR does not function in principle in diesel vehicles, only upgrade oxidation catalytic converters can be used for classification in a better emission class. With large-volume engines (especially diesel vehicles), changing the catalytic converter can quickly pay for itself due to the tax savings.
So-called mini-catalysts (e.g. from Walker or Oberland-Mangold), which are installed in addition to the series catalyst, represent a newer alternative . The alternative is comparatively cheap, but the original catalytic converter must still be fully functional. This additional miniature is ideally dimensioned in such a way that it does not generate an increase in exhaust gas back pressure and therefore remains neutral in terms of engine performance. The manufacturer must provide proof of durability in order to obtain the ABE. Practical values do not currently exist because they have not been on the market for very long.
literature
- Hans-Hermann Braess, Ulrich Seiffert: Vieweg manual automotive technology. 2nd edition, Friedrich Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig / Wiesbaden, 2001, ISBN 3-528-13114-4 .
- Karl-Heinz Dietsche, Thomas Jäger, Robert Bosch GmbH: Automotive pocket book. 25th edition, Friedr. Vieweg & Sohn Verlag, Wiesbaden, 2003, ISBN 3-528-23876-3 .