Method for checking the conversion capacity of a catalytic element for converting ozone

#The invention relates to a method for checking the conversion capacity of a catalytic element for clearing ozone which is present in a vehicle.

#For reasons of environmental and personal protection, the levels of pollutants which result from vehicles with an internal combustion engine or from the generation of energy using stationary combustion installations need to be significantly reduced.

#A novel approach to reducing the levels of pollutants consists in actively removing pollutants not directly from the exhaust-gas stream from an internal combustion engine or a stationary combustion installation, but rather from the ambient air. This route is promising in particular for the removal of ground-level ozone, which has a considerable influence on the well-being of people on account of its strongly oxidizing action. Ozone itself is not a gas which is emitted directly and therefore cannot be removed in the exhaust-gas stream. It is formed when nitrogen oxides are present in outside air under solar radiation, on account of the UV component of this radiation, through complex photochemical reaction equilibria.

#The invention is explained in more detail below with reference to an exemplary embodiment and with the aid of figures, in which:

#FIG. 1 shows an outline illustration of the way in which the conversion capacity of a radiator of a vehicle which is coated with a catalytic element can be checked.

#FIG. 2 shows a flow diagram showing how the conversion capacity of a radiator of a vehicle which is coated with a catalytic element can be checked.

#In the illustration shown in FIG. 1, an ambient-air stream 2 flows to a radiator 1 of a vehicle. The incoming flow takes place as a result of the vehicle speed, by means of the air stream and/or by means of a fan. The radiator 1 is coated with a catalytic element 10 for breaking down ozone, referred to below as an ozone catalyst. Upstream of the radiator 1 there is a first sensor 3 for determining the ozone concentration in the ambient air upstream of the radiator 1. The signal of the sensor 3 is denoted by C_O3_UP. Downstream of the radiator 1 there is a second sensor 4 for determining the ozone concentration in the ambient air downstream of the radiator 1. The signal from the sensor 4 is denoted by C_O3_DOWN.

#Both sensors 3, 4 are connected to a control and evaluation device 5 which evaluates the measured values C_O3_UP, C_O3_DOWN from the two sensors 3, 4. This device 5 is preferably designed as a microprocessor. The control and evaluation device 5 may also be integrated in an engine management system 6 which controls operation of the internal combustion engine of the vehicle, as indicated by dashed lines in FIG. 1. Further operating variables of the internal combustion engine and environmental parameters, in particular the actual value of the vehicle speed V_IST, the coolant temperature TKW of the internal combustion engine which drives the vehicle, and the ambient air temperature TIA, are fed to the control and evaluation device 5.

#The control and evaluation device 5 has a fault memory 9, in which the results of the checking of the conversion capacity of the ozone catalyst are stored.