Method for operating an electro motor-driven secondary air pump
AssigneeRobert Bosch GmbH
InventorAndreas Greim
Life of this patent
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Abstract
A method for operating an electro motor-driven secondary air pump which is provided for injecting secondary air into the exhaust system of an internal combustion engine. The secondary air pump is operated in a clocked manner. The induced voltage at the electro motor of the secondary air pump, measurable during the turn-off time of the clocked operation, is used for diagnosing as well as for controlling the speed of the secondary air pump. The diagnosis is carried out based on the evaluation of a parameter (difference quotient, differential quotient) of the induced voltage. The induced voltage is instantaneously a measure for the secondary air pump's actual speed value, so that a separate detection of the actual speed value is omitted.
Claims11
A method for operating an electro motor-driven secondary air pump which is provided for injecting secondary air into an exhaust system of an internal combustion engine, the method comprising:
- operating the secondary air pump in a clocked manner, at least one of (a) a cycle period and (b) one of a turn-off time and a turn-on time of an operating voltage of the secondary air pump being set during the clocked operation;
- providing a diagnosis of the secondary air pump by evaluating a parameter of an induced voltage occurring at the secondary air pump during the turn-off time;
- comparing the parameter to at least one predefined threshold value;
- and
- signaling an exceeding of the threshold value by a diagnostic signal.
Dependencies are inferred from the claim text.