Injection control device

An injection control device for controlling a solenoid used in an injection valve that injects fuel to an internal combustion engine, the injection control device comprising:

• a first upstream switch disposed on an upstream side of a first power supply path that extends from a direct current (DC) power supply line to the solenoid, the DC power supply line configured to supply a DC voltage to the solenoid;
• a second upstream switch disposed on an upstream side of a second power supply path that extends from a boost power supply line to the solenoid, the boost power supply line configured to supply a boosted voltage to the solenoid, the boosted voltage obtained by boosting the DC voltage;
• a downstream switch disposed on a downstream side of the first and second power supply paths;
• a backflow prevention diode disposed at a position between an upstream terminal of the solenoid and the first upstream switch, an anode of the diode connected to the first upstream switch;
• a short circuit switch disposed at a position between the upstream terminal of the solenoid and the first upstream switch, the short circuit switch arranged in parallel with the backflow prevention diode;
• a drive controller configured to control a drive of the solenoid by controlling an ON and OFF switching of the first upstream switch, the second upstream switch, the downstream switch, and the short-circuit switch, the drive controller further configured to drive the solenoid to an open position by switching ON the downstream switch and one of the first upstream switch and the second upstream switch;
• and
• an applied voltage detector configured to detect an applied voltage to the solenoid,
• wherein the drive controller is further configured to switch the short circuit switch to OFF when the applied voltage detected by the applied voltage detector is greater than the DC voltage.

An injection control device for controlling a solenoid used in an injection valve that injects fuel to an internal combustion engine, the injection control device comprising:

• a first upstream switch disposed on an upstream side of a first power supply path that extends from a direct current (DC) power supply line to the solenoid, the DC power supply line configured to supply a DC voltage to the solenoid;
• a second upstream switch disposed on an upstream side of a second power supply path that extends from a boost power supply line to the solenoid, the boost power supply line configured to supply a boosted voltage to the solenoid, the boosted voltage obtained by boosting the DC voltage;
• a downstream switch disposed on a downstream side of the first and second power supply paths;
• a backflow prevention diode disposed at a position between an upstream terminal of the solenoid and the first upstream switch, an anode of the diode connected to the first upstream switch;
• a short circuit switch disposed at a position between the upstream terminal of the solenoid and the first upstream switch, the short circuit switch arranged in parallel with the backflow prevention diode;
• and
• a drive controller configured to control a drive of the solenoid by controlling an ON and OFF switching of the first upstream switch, the second upstream switch, the downstream switch, and the short-circuit switch, the drive controller further configured to drive the solenoid to an open position by switching ON the downstream switch and one of the first upstream switch and the second upstream switch,
• wherein the first upstream switch and the short circuit switch are both n-type MOSFETs, and
• wherein the drive controller is further configured to generate an ON drive voltage for turning ON the first upstream switch and an ON drive voltage for turning ON the short circuit switch by using a common bootstrap circuit shared by the first upstream switch and the short circuit switch.