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AssigneeRobert Bosch GmbH
InventorJohannes-Jorg Rueger
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The invention describes an apparatus and method for detecting a short circuit to a battery voltage when driving a piezoelectric element, for example, used as an actuator in a fuel injection system of an internal combustion engine. The apparatus and method are characterized in that separate switches are used for selecting a piezoelectric element to be operated and for selecting the operation that is to be performed on the piezoelectric element. A short circuit to battery voltage is detected by first activating the switches to select a piezoelectric element. For a predetermined time interval, the invention monitors for abnormal currents flowing in series with the piezoelectric element. If abnormal currents are detected, an error signal is generated indicating a short circuit to battery voltage. If no abnormal currents are detected during the predetermined time interval, then the switches for selecting a charging or discharging operation are activated to continue with the normal cycling of the piezoelectric elements.
An apparatus for detecting a short circuit from a piezoelectric element (10, 20, 30, 40, 50, or 60) to a battery voltage when driving the piezoelectric element (10, 20, 30, 40, 50, or 60), the apparatus characterized by an element selection switch for selecting the piezoelectric element for operation, an operation selection switch for selecting a charging or discharging circuit to be connected to the piezoelectric element (10, 20, 30, 40, 50, or 60), and a control unit (D) that activates the element selection switch for a predetermined time interval before activating the operation selection switch, the control unit (D)further generating an error signal if a current measurement is greater than a predetermined maximum during the predetermined time interval.
A method for detecting a short circuit from a piezoelectric element (10, 20, 30, 40, 50, or 60) to a battery voltage when driving the piezoelectric element (10, 20, 30, 40, 50, or 60), in particular for operating an apparatus according to one of the foregoing claims, the method characterized by closing a switch to select the piezoelectric element (10, 20, 30, 40, 50, or 60) for operation, monitoring a current measurement for a predetermined time interval before closing a switch to select a charging or discharging circuit to connect to the piezoelectric element (10, 20, 30, 40, 50, or 60), and generating an error signal if the current measurement during the predetermined time interval is greater than a predetermined maximum.
Dependencies are inferred from the claim text.