JP4442258B2 - Electromagnetic actuator drive device - Google Patents

Description

  The present invention relates to a drive device that drives an electromagnetic actuator such as an injector including an electromagnetic valve.

  2. Description of the Related Art Conventionally, an electromagnetic actuator driving device (hereinafter referred to as EDU) that drives an electromagnetic actuator such as an injector by using high voltage charging energy accumulated in a capacitor by a booster circuit (DCDC converter) is known. . In the EDU, when an abnormality such as a decrease in breakdown voltage occurs in the capacitor, the voltage cannot be sufficiently boosted within a predetermined charging time, and the charging time may be extended, thereby possibly damaging the capacitor. For this reason, the EDU incorporates a DCDC lock prevention circuit that limits the time during which the DCDC converter can operate (lock prevention time) as a capacitor protection function. As a result, if an abnormality such as an internal leak occurs in the capacitor, the voltage cannot be boosted to the target voltage within the lock prevention time, so that the failure can be detected by the performance degradation of the EDU.

The lock prevention time is started by the ON signal of the IG switch as shown in FIG. 6 and then reset by the injection signal from the ECU, as shown in FIG. 6, and by the ON signal of the IG switch as shown in FIG. After that, the B system is reset by a signal indicating that the capacitor has been boosted to the target voltage (see Patent Document 1).
In the case of the A method, if there is no injection signal within the lock prevention time, the DCDC converter stops at the end of the lock prevention time.
In the case of the B method, the DCDC converter continues to operate even if there is no injection signal within the lock prevention time.
JP 2003-45717 A

  However, in the above-described A method, when the injection signal is not transmitted from the ECU in the engine operating state (for example, the fuel is cut when the vehicle is decelerated), the DCDC lock prevention circuit works to stop the DCDC converter. If the elapsed time until the signal is restarted is long, the capacitor voltage drops greatly. As a result, there is a problem that the capacitor voltage necessary for driving the injector cannot be obtained and the injection performance is lowered. In particular, in recent years, the capacity of capacitors that store boosted energy has increased, and there is a tendency for the time for performance to decrease.

On the other hand, in the B system, when the engine is stopped and left in a state where only the battery voltage is supplied (for example, at the time of engine stall), the DCDC converter continues to operate even if there is no injection signal. May worsen or may cause electric shock when touched by the user.
The present invention has been made based on the above circumstances. In the state where only the battery voltage is supplied when the engine is stopped, the DCDC converter is stopped, and in the engine operating state, the DCDC is not transmitted. An object of the present invention is to provide an electromagnetic actuator driving device capable of operating a converter.

(Invention of Claim 1)
The present invention relates to a DCDC converter that is connected to a battery via a power supply relay and, when the power supply relay is closed and controlled, boosts the battery voltage to a target voltage and stores energy supplied to the electromagnetic actuator, and the DCDC converter The operation time (lock prevention time) of the DCDC converter is set with the start of the operation, and thereafter, the lock prevention time setting for resetting the lock prevention time based on the detection signal indicating that the voltage of the DCDC converter has been boosted to the target voltage. An electromagnetic actuator driving device including a circuit, and when a starter ON signal for instructing starter start is detected, the power relay is closed and the operation of the DCDC converter is started, and the lock prevention time setting circuit The lock prevention time is set .

According to the above configuration, since the DCDC converter is stopped until the starter ON signal is detected, the DCDC converter does not operate in a state where only the battery voltage is supplied (engine stop state), and the radio The risk of noise and electric shock can be avoided.
The lock prevention time setting circuit sets the lock prevention time at the start of the operation of the DCDC converter, and thereafter resets the lock prevention time based on a detection signal indicating that the voltage of the DCDC converter has been boosted to the target voltage. Therefore, the DCDC converter can be maintained in the operating state regardless of the presence or absence of the injection signal. As a result, even when the injection signal is not detected in the engine operating state (for example, when the fuel is cut during deceleration), the DCDC converter does not stop, and the voltage of the DCDC converter can be prevented from greatly decreasing.

  The best mode for carrying out the present invention will be described in detail by the following examples.

FIG. 1 is an operation time chart of the electromagnetic actuator driving device according to the first embodiment, and FIG. 2 is a circuit diagram of the electromagnetic actuator driving device.
An electromagnetic actuator driving apparatus 1 according to a first embodiment is an injector driving apparatus (hereinafter referred to as EDU1) for driving an injector 2 (electromagnetic actuator of the present invention) that performs fuel injection on a cylinder of an internal combustion engine. is there.

  As shown in FIG. 2, the EDU 1 includes a DCDC converter 3 for boosting the battery voltage to a target voltage, and a lock prevention time setting circuit for setting an operation time (lock prevention time) of the DCDC converter 3 (see FIG. 3). ) And a drive circuit 4 for driving the injector 2 using the energy accumulated in the DCDC converter 3, and the injection signal for instructing fuel injection by the injector 2 is transmitted to the known ECU 5 ( From the electronic control unit).

  The DCDC converter 3 includes a coil 8 connected to the battery 7 via the power relay 6, an energy storage capacitor 10 connected to the low potential side of the coil 8 via a backflow prevention diode 9, and the coil 8. The energy storage capacitor 10 is started to charge with self-induced energy generated in the coil 8 based on the ON / OFF operation of the switching element 11. The battery is charged up to the target voltage (target value shown in FIG. 1). A predetermined hysteresis is set in advance for the target voltage.

As shown in FIG. 3, the lock prevention time setting circuit is connected to the constant voltage Vcc via the transistor 12 that is turned on by a detection signal indicating that the voltage of the DCDC converter 3 has been boosted to the target voltage. A lock prevention time calculation circuit 16 comprising a lock prevention time setting capacitor 14 and a comparator 15 that outputs a lock prevention detection signal (stop signal for the DCDC converter 3) when the voltage of the capacitor 14 exceeds a predetermined voltage Vref. Have. The lock prevention time calculation circuit 16 is built in the drive circuit 4.
When the starter switch 17 for starting a starter (engine starter) (not shown) is turned ON, the ECU 5 detects the ON signal ( starter ON signal ) and closes the power relay 6 (the coil 6a is controlled). Energized to close the switch 6b).

Next, the operation of the EDU 1 will be described based on the timing chart shown in FIG.
When the starter switch 17 (see FIG. 2) is turned on, the ECU 5 detects the ON signal and controls the power relay 6 of the EDU 1 to be closed.
Thereby, the operation of the DCDC converter 3 is started, and the energy storage capacitor 10 is charged to the target voltage.
On the other hand, the lock prevention time setting circuit sets the lock prevention time of the DCDC converter 3 together with the start of the operation of the DCDC converter 3, and thereafter, the detection signal indicating that the voltage of the DCDC converter 3 has been boosted to the target voltage, Reset the lock prevention time.

(Effect of Example 1)
In the EDU 1, when the ON signal of the starter switch 17 is detected by the ECU 5, the power relay 6 is closed and the operation of the DCDC converter 3 is started. In other words, the DCDC converter 3 is stopped until the ECU 5 detects the ON signal of the starter switch 17. Thereby, in the state where the starter switch 17 is OFF and only the battery voltage is supplied (engine stop state), the DCDC converter 3 does not operate, and the occurrence of radio noise and electric shock can be avoided.

  The lock prevention time setting circuit sets the lock prevention time at the start of the operation of the DCDC converter 3, and thereafter sets the lock prevention time based on a detection signal indicating that the voltage of the DCDC converter 3 has been boosted to the target voltage. Since the reset is performed, the DCDC converter 3 can be maintained in the operating state regardless of the presence or absence of the injection signal. As a result, even when the injection signal is not detected in the engine operating state (for example, at the time of fuel cut at the time of deceleration), the DCDC converter 3 does not stop and the target voltage can be maintained, so that a decrease in injection performance can be prevented.

FIG. 4 is an operation time chart of the EDU 1 according to the second embodiment.
The EDU 1 of the present embodiment is an example in which resetting of the lock prevention time by the lock prevention time setting circuit is prohibited until the first injection signal is detected after the IG switch (not shown) is turned on. It is.
As shown in FIG. 5, the lock prevention time setting circuit includes a reset inhibition circuit 18 that inhibits resetting of the lock prevention time until the first injection signal is detected, and a lock prevention time calculation circuit 16 that calculates the lock prevention time. (Same as Example 1).

The reset prohibition circuit 18 includes an RS flip-flop (FF) circuit 19 and an AND circuit 20.
When the first injection signal is input to the set terminal after the FF circuit 19 is reset by the start signal (IG switch ON signal), the output Q becomes “1”, and the voltage of the DCDC converter 3 reaches the target voltage. The output of the AND circuit 20 that performs a logical operation with the detection signal indicating that the voltage has been boosted is “1”. Therefore, until the first injection signal is input to the set terminal of the FF circuit 19, the reset signal output (output of the AND circuit 20) indicating that the voltage of the DCDC converter 3 has been boosted to the target voltage is prohibited. Yes.

Next, the operation of the EDU 1 will be described based on the timing chart shown in FIG.
When the IG switch is turned on, the ECU 5 detects the ON signal and closes the power relay 6 of the EDU 1.
Thereby, the operation of the DCDC converter 3 is started, and the energy storage capacitor 10 is charged to the target voltage (target value shown in FIG. 4).

  On the other hand, the lock prevention time setting circuit prohibits resetting of the lock prevention time until the first injection signal for the injector 2 is detected after setting the lock prevention time of the DCDC converter 3 at the start of the operation of the DCDC converter 3. Is done. When the first injection signal is detected, the lock prevention time is reset based on the detection signal indicating that the voltage of the DCDC converter 3 has been boosted to the target voltage.

(Effect of Example 2)
Since the EDU 1 is prohibited from resetting the lock prevention time by the lock prevention time setting circuit until the first injection signal is detected, the DCDC converter 3 is in a state where only the battery voltage is supplied (engine stop state). Does not work, and can avoid the occurrence of radio noise and the risk of electric shock.

  Further, when the first injection signal is detected, the lock prevention time setting circuit resets the lock prevention time based on a detection signal indicating that the voltage of the DCDC converter 3 has been boosted to the target voltage thereafter. Regardless of the presence or absence of the injection signal, the DCDC converter 3 can be maintained in the operating state. As a result, even when the injection signal is not detected in the engine operating state (for example, at the time of fuel cut at the time of deceleration), the DCDC converter 3 does not stop and the voltage of the DCDC converter 3 can be prevented from greatly decreasing.

6 is an operation timing chart of the EDU (Example 1). 1 is a circuit diagram of an EDU (Example 1). FIG. FIG. 3 is a configuration diagram of a lock prevention time calculation circuit (first embodiment). 6 is an operation timing chart of the EDU (Example 2). FIG. 6 is a circuit diagram illustrating an internal configuration of a lock prevention time setting circuit (second embodiment). It is an operation | movement timing chart of EDU (prior art). It is an operation | movement timing chart of EDU (prior art).

Explanation of symbols

1 EDU (Electromagnetic Actuator Drive Unit)
2 Injector (electromagnetic actuator)
3 DCDC converter 6 Power relay 7 Battery 16 Lock prevention time calculation circuit (lock prevention time setting circuit)
18 Reset prohibition circuit (Lock prevention time setting circuit)

Claims (1)

A DCDC converter that is connected to a battery via a power relay and that, when the power relay is controlled to be closed, boosts the battery voltage to a target voltage and stores energy supplied to the electromagnetic actuator;
When the DCDC converter starts operating, an operation time (lock prevention time) of the DCDC converter is set. Thereafter, the lock prevention time is determined based on a detection signal indicating that the voltage of the DCDC converter has been boosted to the target voltage. An electromagnetic actuator driving device comprising a lock prevention time setting circuit for resetting
When a starter ON signal for instructing starter start is detected, the power relay is closed to start the operation of the DCDC converter, and the lock prevention time is set by the lock prevention time setting circuit. Electromagnetic actuator driving device.

Images