JP2011001821A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that switching control is complicated in a conventional technology since a cycle is determined first and then a duty ratio is determined within the cycle.SOLUTION: An engine control device consists of a battery for supplying power, a booster coil having current supplied from a battery, a switching element for passing current to the booster coil, a diode for blocking the current, a booster capacitor charged through the diode, a battery voltage detection part for detecting a battery voltage, an energizing time control part for controlling energizing time of the booster coil, a blocking part for blocking the energization to the booster coil for a fixed period of time, and a booster control part for making the energizing time of the booster coil shorter than a prescribed time period when a battery voltage is higher than a prescribed voltage and for making the energizing time of the booster coil longer than the prescribed time period when the battery voltage is lower than the prescribed voltage.

Description

  The present invention relates to a fuel injection valve drive circuit for a direct injection engine.

  To drive a fuel injection valve for a direct injection engine, a high voltage is applied to the fuel injection valve to open the valve by applying an overexcitation current, and a battery voltage is applied to supply a holding current to open the valve. And the fuel injection valve is driven.

  In recent years, there has been a demand for split injection by shortening the charging time (boosting time) to the capacitor due to engine output improvement, exhaust gas regulation, and the like. Here, the switching period of the current passed through the coil of the booster circuit for each fuel injection by the microcomputer, and the ratio of the time during which the coil of the booster circuit is energized and the time when the energization is stopped within the period (duty ratio) ) In accordance with the battery voltage, there is a technique for shortening the charging time (see Patent Document 1).

JP 2001-55948 A

  According to Patent Document 1, since the cycle is first determined and the duty ratio is determined within the cycle, there is a problem that the switching control becomes complicated. Further, since the switching cycle and the duty ratio are calculated from the battery voltage for each fuel injection, there is a problem that if the battery voltage fluctuates between the fuel injection and the next fuel injection, the boosting time becomes long.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an engine control device that simplifies switching control so as not to increase the boost time.

  In order to solve the above problems, one of the desirable aspects of the present invention is as follows.

  The engine control device includes: a battery that supplies power; a booster coil that is supplied with current from the battery; a switching element that passes current through the booster coil; a diode that interrupts current; and a booster capacitor that is charged via the diode A battery voltage detection unit for detecting the voltage of the battery, an energization time control unit for controlling the energization time of the booster coil, and a blocking unit for interrupting energization of the booster coil for a certain period, and the battery voltage is higher than a predetermined voltage In this case, a boost control unit is provided that makes the energization time of the booster coil shorter than the predetermined time and makes the energization time of the booster coil longer than the predetermined time when the voltage of the battery is lower than the predetermined voltage.

  ADVANTAGE OF THE INVENTION According to this invention, the engine control apparatus which simplified switching control so that pressure | voltage rise time may not become long can be provided.

1 is a diagram illustrating a configuration of an engine control device according to a first embodiment. The figure which shows the whole operation | movement waveform of an engine control apparatus. The figure which shows the typical operation | movement waveform of an engine control apparatus. The figure which shows the electric current rise time which flows into a step-up coil, and a power supply voltage characteristic. The figure which shows the structure of the engine control apparatus of Example 2. FIG.

  Hereinafter, embodiments will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an engine control apparatus according to the first embodiment.

  The engine control apparatus includes a booster circuit 100 that is supplied with power by a battery power supply 1 and its power supply ground 4, a drive circuit 200 that drives the injector 3 using the boosted voltage boosted by the booster circuit 100, and the injector 3 A current regeneration diode 2 for regenerating the regenerative current to the booster circuit 100 is provided.

  The engine control device includes an input circuit of various sensors including a fuel pressure of a common rail that supplies fuel to an engine rotation sensor and an injector, an arithmetic device that calculates an energization timing of the injector 3 according to those input signals, Drive circuit (ignition coil drive circuit, throttle drive circuit, etc.), communication circuit with other control devices, control circuit corresponding to various diagnoses and fail safe, power supply circuit for supplying power to them, etc. .

  The booster circuit 100 includes a booster coil 101 having an inductance component for boosting the voltage of the battery power supply 1, a booster switch element 102-2 for energizing / cutting off the current to the booster coil, and protecting the booster switch element from negative surges. By switching off the switching-side diode 102-1 and the boosting switch element, a path for charging the boosting capacitor 111 with a high voltage that generates energy stored in the boosting coil, and the backflow from the boosting capacitor 111 to the battery power supply 1 are prevented. It comprises a charging diode 110-1 and a boost control circuit 120.

  The step-up control circuit 120 includes a step-up control unit 124, a step-up voltage detection unit 122, a power supply voltage detection unit 127, and a counter 126 that generates a step-up energization timing signal in the step-up control unit 124 based on a basic clock from the oscillator 131. .

  When the drive circuit 200 applies an injector current to the injector 3 using the boost voltage, and as a result, the boost voltage detection unit 122 detects that the boost voltage has dropped below the boost start voltage 401 (see FIG. 2). The boost control unit 124 starts a boost operation. When the boosting operation is started, the boost control unit 124 changes the boost control signal for energizing the boost switch element 102-2 from LOW to HIGH, and at the same time, the counter 126 starts measuring the energization time. As a result, a current flows from the battery power source 1 to the booster coil 101 and energy is accumulated in the booster coil 101.

  FIG. 3 is a diagram illustrating typical operation waveforms of the engine control apparatus.

  The power supply voltage detection unit 127 detects the voltage of the battery power supply 1, and the boost control unit 124 calculates the boost coil current rise time 501 corresponding to the voltage. The boosting coil current rising time 501 outputs a reset signal from the boosting control unit 124 to the counter 126 when the counter value by the counter 126 reaches the boosting coil energizing time 501 after the energization of the boosting coil 101 is started. Is cleared to 0, and the boost control unit 124 changes the boost control signal for controlling the opening / closing of the boost switch element 102-2 from HIGH to LOW to cut off the boost switching current.

  When the boost control signal changes from HIGH to LOW, the counter 126 starts measuring the boost coil current charging time 502. The current flowing in the booster coil 101 cannot flow to the power supply ground through the booster switch element 102-2, and the energy stored by the inductance component of the booster coil 101 generates a high voltage. When this voltage becomes higher than the voltage obtained by adding the boosted voltage stored in the boost capacitor 111 and the forward voltage of the charging diode 110-1, the energy stored in the boosting coil 101 passes through the charging diode 110-1. The charging capacitor 111 shifts to the boost capacitor 111.

  At this time, the charging current starts from the switching stop current 410 flowing in the coil immediately before the boost switch element 102-2 is cut off, and rapidly decreases with the energy transfer to the boost capacitor 111. When the preset boost coil current charging time 502 elapses, the boost control unit 124 outputs a reset signal to the counter 126, the counter value is cleared to 0, and the boost voltage detection unit 122 boosts the voltage by the above operation. When it is detected that the voltage does not reach the predetermined boost stop voltage 402, the boost control unit 124 changes the boost control signal from LOW to HIGH to energize the boost switch element 102-2, and the counter 126 determines the boost coil current. The measurement of the rising time 501 is started. This operation is repeated until the boosted voltage reaches a predetermined boost stop voltage 402.

  FIG. 4 is a diagram showing the rise time of the current flowing through the booster coil and the power supply voltage characteristics.

  In general, the current flowing in the coil is obtained by Equation 1. At this time, when the current value is made constant, the relationship between the time when the current flowing through the coil reaches the constant value and the power supply voltage is expressed by Equation 2, and the time when the coil current reaches the constant value and the power supply voltage are inversely proportional. That is, when the voltage of the battery power source 1 is constantly monitored, it can be seen that the voltage is fast when the voltage of the battery power source 1 is high, and slow when the voltage is low, so that the boosting coil current rise time 501 can be adjusted to the characteristics. Even when the voltage of the battery power supply 1 fluctuates at the time of starting or due to an excessive electric load, the boosted voltage recovery time can be shortened and it is possible to cope with divided injection of the injector.

  Note that it is desirable to set an upper limit for the boost coil current rise time 501 to protect the booster circuit from excessive current.

  FIG. 5 is a diagram illustrating the configuration of the engine control apparatus according to the second embodiment. The difference from FIG. 1 is the same as that of the first embodiment except that the current detection resistor 103 and the current detection unit 121 are used instead of the power supply voltage detection unit 127.

  The second embodiment uses the characteristic of FIG. 4 that the rise time of the current flowing through the booster coil varies depending on the voltage value of the battery power supply 1, and the time until the current flowing through the booster coil reaches the threshold is determined as the boost coil current rise time. 501. In the boost coil current rise time 501, when the current detection unit 121 detects a voltage generated by the boost coil current flowing through the current detection resistor 103 and reaches the current threshold value 410, a reset signal is sent from the boost control unit 124 to the counter 126. This is the time from when the counter value is cleared to 0, and the boost control unit 124 changes the boost control signal for controlling the opening / closing of the boost switch element 102-2 from HIGH to LOW to cut off the boost switching current.

  Also in the second embodiment, the counter value is provided with an upper limit value, and even when the battery power supply 1 voltage is low and the boost coil current does not reach the current threshold value 410, the boost switch element 102-2 is prevented from being energized at all times. desirable.

  According to the present invention, by separately controlling the energization time and the energization stop time for the boosting coil, the control can be simplified and the battery voltage fluctuation can be dealt with immediately, thereby shortening the boosting time. be able to.

DESCRIPTION OF SYMBOLS 1 Battery power supply 2 Current regeneration diode 3 Injector 4 Power supply ground 100 Boost circuit 101 Boost coil 102-1 Switching side diode 102-2 Boost switch element 103 Current detection resistor 110-1 Charging diode 111 Boost capacitor 120 Boost control circuit 121 Current detection part 122 Boost Voltage Detection Unit 124 Boost Control Unit 126 Counter 127 Power Supply Voltage Detection Unit 131 Oscillator 200 Drive Circuit

Claims (4)

A battery for supplying power;
A booster coil supplied with current from the battery;
A switching element for passing a current through the booster coil;
A diode that cuts off the current;
A step-up capacitor charged via the diode;
A battery voltage detector for detecting the voltage of the battery;
An energization time control unit for controlling the energization time of the booster coil;
A shut-off unit that shuts off the energization of the booster coil for a certain period;
When the voltage of the battery is higher than a predetermined voltage, the energization time of the booster coil is made shorter than the predetermined time, and when the battery voltage is lower than the predetermined voltage, the energization time of the booster coil is made longer than the predetermined time An engine control device comprising: A current detector for detecting a current flowing through the booster coil;
The engine control device according to claim 1, wherein when the current detection unit detects that the current becomes constant, the boost control unit turns off a switching element.   3. The engine control device according to claim 1, wherein the period of time during which the energization is interrupted for a certain period is a time necessary for charging the capacitor with the back electromotive force generated by the booster coil. A battery for supplying power;
A booster coil supplied with current from the battery;
A switching element for passing a current through the booster coil;
A diode that cuts off the current;
A step-up capacitor charged via the diode;
A current detection resistor indicating a resistance for detecting the current;
An energization time control unit for controlling the energization time of the booster coil;
Including a shut-off unit that shuts off the energization of the booster coil for a certain period,
When the voltage of the battery is higher than a predetermined voltage, the energization time of the booster coil is made shorter than the predetermined time, and when the battery voltage is lower than the predetermined voltage, the energization time of the booster coil is made longer than the predetermined time An engine control device comprising:

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