Exhaust-gas recirculation system for an internal combustion engine
AssigneeRobert Bosch GmbH
InventorsWalter Viess, Hans Koehnle
Life of this patent
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Abstract
An exhaust-gas recirculation system includes means for diagnosing the system based upon temperature values measured in the exhaust-gas return duct when certain conditions exist. A differential value between the actual temperature in the exhaust-gas return duct and a reference temperature, which indicates the possible beginning of diagnosis, is provided for a flow-through test. The differential value is then fed to a low-pass filter. If the conditions for a diagnosis are satisfied, it is determined whether the recirculation system is in order based upon a comparison of the differential value to a threshold value. A leak test of the exhaust-gas return valve can likewise be performed based upon the differential value of the two temperatures.
Claims7
An exhaust-gas recirculation system for an internal combustion engine, comprising:
- an exhaust-gas return valve located in an exhaust-gas return duct;
- a load sensor for measuring at least one operating parameter of the internal combustion engine;
- a temperature sensor for measuring a temperature in the exhaust-gas return duct;
- a control unit coupled to the load sensor for controlling the exhaust-gas return valve based upon the measured operating parameters;
- means for determining a difference value between the measured temperature value in the exhaust-gas return duct and a preselected reference value;
- filter means for receiving a first variable based upon at least one of a measured load of the engine and a trigger signal of the exhaust-gas return valve, for receiving a second variable based upon the difference value, and for generating a filtered output value based thereon;
- and
- means for comparing the filtered output value to a first preselected threshold value and for performing a diagnosis of the exhaust-gas recirculation system based thereon by comparing the difference value to a second preselected threshold value.
Dependencies are inferred from the claim text.