Bayerische Motoren Werke Aktiengesellschaft

Siemens Aktiengesellschaft

Michael Krauss

Stefan Treinies

Alexander Ketterer

A cooling system for an internal combustion engine has a pipeline leading from the internal combustion engine to a radiator, a return pipeline from the radiator to the internal combustion engine, a bypass line connecting the pipeline and the return pipeline, and a thermostat valve, through which the coolant is passed from the internal combustion engine through the bypass line and/or through the radiator back to the internal combustion engine, depending on the operating conditions. At least one temperature sensor is provided in the cooling system, and an output signal is supplied to a control unit. In the case of a change from a first operating condition, for which the coolant must be passed through the thermostat valve initially only through the bypass line, to a second operating condition, for which the coolant is permitted to flow through the thermostat at least partially through the radiator, the control unit checks whether an increase in the temperature of the coolant commences at the outlet of the radiator.

Cooling system for an internal combustion engine in motor vehicles and operating process therefor

In a method for checking the conversion capability of a catalytic converter, in particular a precatalytic converter associated with internal combustion engines of motor vehicles, the checking is undertaken through the use of a temperature measurement immediately downstream of the catalytic converter. Initially the temperature at the beginning and at the end of a predetermined idling phase is measured for a predetermined number of idling phases, following an overrun phase in predetermined operating states of a motor vehicle with an internal combustion engine. Then the difference of the temperature measurements for each idling phase is formed. The sum of all of the temperature differences and the sum of the duration of the idling phases are formed and subsequently a quotient of these results is formed. This quotient determines an average gradient. The average gradient determined in this way is compared with a limiting value and the catalytic converter is recognized as defective if the predetermined limiting value is exceeded. The method may be applied to motor vehicles with internal combustion engines.

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Munchen, Germany

Michael Krauss