Internal-combustion-engine fuel injection control device
View Patent ↗An internal-combustion-engine fuel injection control device which can accurately control a boosted voltage applied to a fuel injection valve during fuel injection and can control a variation in a fuel injection amount without increasing a size or a cost of the fuel injection control device even when a width of a fuel injection driving pulse to drive the fuel injection valve is small is provided. A fuel injection control device includes a boosting operation control unit configured to start a boosting operation at predetermined timing regardless of an amount of a detected voltage when the detected voltage is higher than a threshold voltage for starting boosting and is lower than a threshold voltage for stopping boosting.
1. An internal-combustion-engine fuel injection control device comprising:
a booster circuit configured to generate a boosted voltage that opens a fuel injection valve, the fuel injection valve being configured to directly supply fuel into a combustion chamber;
a boosting operation control unit; and
a voltage detection unit configured to detect an actual voltage in the booster circuit, wherein
a boosting operation is started when the actual voltage detected by the voltage detection unit reaches a first threshold voltage that triggers a start of boosting,
the boosting operation is stopped when the actual voltage detected by the voltage detection unit reaches a second threshold voltage for stopping boosting,
the boosting operation control unit is configured to start the boosting operation at a predetermined timing, and the boosting operation is started without regard to a timing of a fuel injection,
the boosting operation control unit includes a circuit configured to temporarily change a value of the actual voltage detected by the voltage detection unit to a value that is lower than the first threshold voltage that triggers the start of boosting by dividing the boosted voltage and providing a divided portion of the boosted voltage to the voltage detection unit, and
the circuit includes a first resistor and a switching element that are connected to GND at a connection point of a second and third resistor configured to divide the boosted voltage.
2. The internal-combustion-engine fuel injection control device according to claim 1 , wherein the fuel injection control device includes a plurality of threshold voltages for starting boosting which voltages have different voltage values, and
the boosting operation control unit includes a switch for switching a threshold voltage for starting boosting which switch is configured to switch which of the plurality of threshold voltages for starting boosting is selected.
3. The internal-combustion-engine fuel injection control device according to claim 1 , wherein the circuit is configured to start the boosting operation when the detected voltage is lower than the threshold voltage for stopping boosting.
4. The internal-combustion-engine fuel injection control device according to claim 1 , wherein the predetermined timing is repeatedly set with a predetermined time interval passing between each setting of the timing.
5. The internal-combustion-engine fuel injection control device according to claim 4 , wherein the predetermined timing is timing at which voltage is not applied to the fuel injection valve.
6. The internal-combustion-engine fuel injection control device according to claim 1 , wherein the predetermined timing is timing at which voltage generated in the booster circuit is applied to the fuel injection valve.
7. The internal-combustion-engine fuel injection control device according to claim 1 , wherein the predetermined timing is timing at which predetermined delay time is elapsed from application of voltage generated in the booster circuit to the fuel injection valve.
8. The internal-combustion-engine fuel injection control device according to claim 1 , wherein the predetermined timing is timing after application of voltage generated in the booster circuit to the fuel injection valve is over.
9. The internal-combustion-engine fuel injection control device according to claim 1 , wherein the predetermined timing is timing at which voltage is applied to the fuel injection valve.
10. The internal-combustion-engine fuel injection control device according to claim 1 , wherein the predetermined timing is timing at which application of voltage to the fuel injection valve is over.