Control apparatus for electroexpansive actuator enabling variation of stroke
AssigneeNippon Soken, Inc.
InventorsMasahiro Takigawa, Toshihiko Igashira, Yasuyuki Sakakibara, Kazuhide Watanabe
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Abstract
A color apparatus includes an electroexpansive actuator, a unit for supplying a charge to the electroexpansive actuator, and a unit for controlling an amount of charge discharged from the electroexpansive actuator, and a stroke of the electroexpansive actuator is controlled in accordance with the amount of charge discharged therefrom. When such an electroexpansive actuator is applied to a control apparatus for a fuel injection valve, a fuel injection amount per ON/OFF operation of the fuel injection valve or a fuel injection rate can be freely controlled.
Claims34
A control appartus for an electroexpansive actuator, comprising:
- an electroexpansive actuator which has a stroke that is controlled in accordance with an amount of potential discharged therefrom;
- means for supplying a potential to said electroexpansive actuator;
- and
- means for controlling an amount of potential discharged from said electroexpansive actuator, comprising
- (a) a capacitor, coupled to said electroexpansive actuator, for receiving a storing said potential discharged from said electroexpansive actuator as a stored potential, and
- (b) means for controlling said stored potential of said capacitor before the charge is discharged from said actuator.
A control apparatus for fuel injection valve, comprising:
- an electroexpansive actuator;
- means for supplying a potential to said electroexpansive actuator;
- means for controlling an amount of potential discharged from said electroexpansive actuator, said control means comprising (a) a capacitor for receiving and storing said potential discharged from said electroexpansive actuator as a stored potential and (b) means for controlling an amount of said residual potential of said capacitor before said potential is discharged from said actuator, said amount being selectively changed in accordance with an engine speed;
- and
- a nozzle needle, coupled to said exlectroexpansive actuator, for selectively assuming a position engaged with or lifted from a valve seat, in accordance with an expansion/contraction of said electroexpansive actuator upon supply/discharge of said potential to/from said electroexpansive actuator,
- wherein an amount of lift of said nozzle needle is controlled in accordance with said amount of potential discharged from said electroexpansive actuator.
An apparatus for controlling fuel injection in a diesel engine comprising:
- a fuel injection valve having an electroexpansive actuator coupled to a nozzle needle;
- a DC power source;
- a first switching element connected in series between said actuator and said power source;
- a second switching element connected in parallel with said actuator;
- a capacitor;
- a third switching element connected in series between said actuator and said capacitor;
- circuit means for generating a pilot injection signal and a main injection signal in accordance with operating condition of said engine;
- means for turning on said first switching element to render it conductive before said pilot injection signal and main injection signal are generated, to charge said actuator using said DC power source;
- means for turning on said third switching element to render conductive said third switching element in response to said pilot injection signal, to discharge a potential of said actuator until a voltage of said actuator is decreased to a reference level, said nozzle needle being lifted by the contraction of said actuator to cause a pilot fuel injection into said engine;
- means for determining said reference level so that a lift of said nozzle needle for said pilot fuel injection is limited to being less than full lift thereof;
- and
- means for turning on said second switching element in response to said main injection signal to discharge said potential of said actuator so that said nozzle needle is fully lifted by the contraction of said actuator for a main fuel injection into said engine.
A method for controlling an electroexpansive actuator to drive a fuel injection valve of an engine, comprising the steps of:
- supplying a potential to said electroexpansive actuator;
- providing a capacitor to receive potential from said electroexpansive actuator;
- discharging said capacitor until a potential of said capacitor is lowered to a predetermined value before said capacitor receives potential from said electroexpansive actuator;
- and
- subsequent to said discharging step, discharging a potential in said electroexpansive actuator into said capacitor, wherein a stroke of said electroexpansive actuator is controlled in accordance with an amount of potential discharged thereform.
Dependencies are inferred from the claim text.