PIEZOELECTRIC ACTUATOR DRIVE DEVICE AND DC/DC CONVERTER THEREFOR
First Claim
1. A piezoelectric actuator drive device comprising:
- a DC/DC converter including a boosting coil that is fed with a power source voltage at one end thereof, a boost switch that is connected in series in a path extending between the other end of the boosting coil and a reference potential lower than the power source voltage, a reverse-flow preventing diode that has an anode connected to a current path extending between the other end of the boosting coil and the boost switch, a capacitor that is connected in series in a path extending between a cathode of the reverse-flow preventing diode and the reference potential, and boost control means for performing boost switching control in which the boost switch is turned on and off repeatedly thereby to charge the capacitor with a current from the reverse-flow preventing diode and to generate a voltage higher than the power source voltage, at a positive terminal of the capacitor on a side opposite to the reference potential;
a charging/discharging coil connected in series with a piezoelectric actuator;
a charging path for feeding a supply voltage to a series circuit of the charging/discharging coil and the piezoelectric actuator from the positive terminal of the capacitor and through a charging switch;
a discharging path connected in parallel with the series circuit for discharging stored charge of the piezoelectric actuator through a discharging switch;
a first diode connected in parallel with the charging switch with a cathode thereof located on a side of the positive terminal of the capacitor;
a second diode connected in parallel with the discharging switch with a cathode thereof located on a side of the charging/discharging coil; and
charging/discharging control means for performing charging switching control in response to a drive command externally inputted and discharging switching control in response to a drive stop command externally inputted, the charging switching control being for repeatedly turning on and off the charging switch in an OFF state of the discharging switch thereby to charge and expand the piezoelectric actuator, and the discharging switching control being for repeatedly turning on and off the discharging switch in an OFF state of the charging switch thereby to discharge and contract the piezoelectric actuator, wherein the boost control means and the charging/discharging control means are configured to perform respective controls without detecting a charging current which flows from the reverse-flow preventing diode to the capacitor, respectively.
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Accused Products
Abstract
A fuel injection control apparatus drives piezoelectric actuators for opening and closing injectors of respective cylinders based on energy stored in a capacitor of a DC/DC converter A current detecting resistor for controlling a boost switch to charge the capacitor is disposed at a position at which current flowing through the capacitor is not detected. Further, current detecting resistors for controlling the piezoelectric actuators are disposed at positions at which charging current from a diode to the capacitor is not detected. Thus, the charging of the capacitor can be performed even during the control for charging/discharging the piezoelectric actuator.
21 Citations
16 Claims
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1. A piezoelectric actuator drive device comprising:
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a DC/DC converter including a boosting coil that is fed with a power source voltage at one end thereof, a boost switch that is connected in series in a path extending between the other end of the boosting coil and a reference potential lower than the power source voltage, a reverse-flow preventing diode that has an anode connected to a current path extending between the other end of the boosting coil and the boost switch, a capacitor that is connected in series in a path extending between a cathode of the reverse-flow preventing diode and the reference potential, and boost control means for performing boost switching control in which the boost switch is turned on and off repeatedly thereby to charge the capacitor with a current from the reverse-flow preventing diode and to generate a voltage higher than the power source voltage, at a positive terminal of the capacitor on a side opposite to the reference potential; a charging/discharging coil connected in series with a piezoelectric actuator; a charging path for feeding a supply voltage to a series circuit of the charging/discharging coil and the piezoelectric actuator from the positive terminal of the capacitor and through a charging switch; a discharging path connected in parallel with the series circuit for discharging stored charge of the piezoelectric actuator through a discharging switch; a first diode connected in parallel with the charging switch with a cathode thereof located on a side of the positive terminal of the capacitor; a second diode connected in parallel with the discharging switch with a cathode thereof located on a side of the charging/discharging coil; and charging/discharging control means for performing charging switching control in response to a drive command externally inputted and discharging switching control in response to a drive stop command externally inputted, the charging switching control being for repeatedly turning on and off the charging switch in an OFF state of the discharging switch thereby to charge and expand the piezoelectric actuator, and the discharging switching control being for repeatedly turning on and off the discharging switch in an OFF state of the charging switch thereby to discharge and contract the piezoelectric actuator, wherein the boost control means and the charging/discharging control means are configured to perform respective controls without detecting a charging current which flows from the reverse-flow preventing diode to the capacitor, respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A DC/DC converter comprising:
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a boosting coil that is fed with a power source voltage at one end thereof; a boost switch that is connected in series in a path extending between the other end of the boosting coil and a reference potential lower than the power source voltage; a reverse-flow preventing diode that has an anode connected to a current path extending between the other end of the boosting coil and the boost switch; a capacitor that is connected in series in a path extending between a cathode of the reverse-flow preventing diode and the reference potential; boost control means for performing boost switching control in which the boost switch is repeatedly turned on and off, thereby to charge the capacitor with a current from the reverse-flow preventing diode and to generate a voltage higher than the power source voltage at a positive terminal of the capacitor on a side opposite to the reference potential; and boost-switch current detection means, provided in a current path extending from a power source voltage to a reference potential via the boosting coil and the boost switch, for detecting current flowing through the boost switch, wherein the capacitor has a terminal connected to the reference potential directly, wherein the boost control means is configured to turn off the boost switch from ON when the current detected by the boost switch current detection means has increased to an OFF changeover threshold value in an ON state of the boost switch during performance of the boost switching control, and wherein the boost control means is configured to turn on the boost switch from OFF when a time period for which the boost switch is held OFF reaches an OFF time set value.
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15. A DC/DC converter comprising:
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a boosting coil that is fed with a power source voltage at one end thereof; a boost switch that is connected in series in a path extending between the other end of the boosting coil and a reference potential lower than the power source voltage; a reverse-flow preventing diode that has an anode connected to a current path extending between the other end of the boosting coil and the boost switch; a capacitor that is connected in series in a path extending between a cathode of the reverse-flow preventing diode and the reference potential; and boost control means for performing boost switching control in which the boost switch is repeatedly turned on and off, thereby to charge the capacitor with a current from the reverse-flow preventing diode and to generate a voltage higher than the power source voltage at a positive terminal of the capacitor on a side opposite to the reference potential, wherein the boost control means is configured to turn off the boost switch from ON when a time period for which the boost switch is held ON reaches an ON time set value during performance of the boost switching control, and wherein the boost control means is configured to turn on the boost switch from OFF when a time period for which the boost switch is held OFF reaches an OFF time set value.
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16. A drive device for a piezoelectric actuator comprising:
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a boosting coil that is fed with a power source voltage at one end thereof; a boost switch that is connected in series in a path extending between the other end of the boosting coil and a reference potential lower than the power source voltage; a reverse-flow preventing diode that has an anode connected to a current path extending between the other end of the boosting coil and the boost switch; a capacitor that is connected in series in a path extending between a cathode of the reverse-flow preventing diode and the reference potential, and boost control means for performing boost switching control in which the boost switch is turned on and off thereby to charge the capacitor with a current from the reverse-flow preventing diode and to generate a voltage higher than the power source voltage at a positive terminal of the capacitor on a side opposite to the reference potential; a charging switch which charges the piezoelectric actuator by stored energy of the capacitor; and a discharging switch which discharges stored charges of the piezoelectric actuator, wherein the boost switch, the charging switch and the discharging switch are controlled without detection of a charging current which flows from the reverse-flow preventing diode to the capacitor.
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Specification