| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a piezoelectric actuator-controlled fuel injector which is not subjected to high differential voltages for a high proportion of its operating cycle. <P>SOLUTION: Fuel injectors 12a, 12b include a piezoelectric actuator 11 having a stack of piezoelectric elements 9 and, in use, communicate with a fuel rail. A method of operating the fuel injector comprises the steps of: (a) applying a discharge current I<SB>discharge</SB>to the actuator for a prescribed discharge time (from T<SB>0</SB>to T<SB>1</SB>) so as to cause the stack to discharge from a first differential voltage level V<SB>0</SB>across the stack to a second differential voltage level V<SB>1</SB>/V<SB>2</SB>; (b) maintaining the second differential voltage level for a prescribed time (from T<SB>1</SB>to T<SB>2</SB>); and (c) applying a charge current I<SB>CHARGE</SB>to the actuator for a charge time (from T<SB>2</SB>to T<SB>3</SB>; from T<SB>2</SB>to T<SB>3'</SB>) so as to charge the stack from the second differential voltage level to a third differential voltage level V<SB>3</SB>. The third differential voltage level is selected according to at least two engine parameters selected from a rail pressure (P), an electric pulse time T<SB>on</SB>, and a piezoelectric stack temperature Temp. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
