JP2008128206A - Injector drive method and drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injector drive method controlling a fuel injection amount without receiving influence of change in the resistance value of a solenoid coil of an injector. <P>SOLUTION: An injection time giving a fuel injection amount calculated with respect to an intake air amount of an engine is calculated as a reference drive time, and power supply voltage is applied to the injector at drive start timing to start driving of the injector. Timing where opening of a valve of an injector is started is estimated as valve opening timing, from a waveform of a drive current flowing through the injector, and an elapsed time from the drive start timing to the valve opening timing is measured as a valve opening time. The reference drive time is corrected depending on the valve opening time and an actual drive time of the injector is calculated so that difference between an injection amount calculated with respect to the intake air amount and a fuel amount actually injected from the injector to be close to zero, and the drive of the injector is completed when the elapsed time from the drive starting timing reaches the actual drive time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an injector driving method for driving an injector (electromagnetic fuel injection valve) that supplies fuel to an engine, and a driving device used for carrying out the driving method.

  As shown in Patent Document 1, an injector has an injection port at its tip, a fuel passage inside, an injector body in which fuel is supplied at a predetermined pressure in the fuel passage, and an injector A valve in the body that opens and closes the injection port, a solenoid that drives the valve to the open position side when energized, and a return spring that biases the valve to the closed position side. To displace the valve to the open position to open the injection port, and when the solenoid coil is de-energized, the biasing force of the return spring returns the valve to the closed position to close the injection port.

  In this type of injector, when the pressure of the fuel supplied into the fuel passage is constant, the amount of fuel injected from the gap formed between the valve and the injection port when the valve is in the open position. Since the amount is proportional to the time to keep the valve in the open position, the time to keep the valve in the open position is taken as the injection time without measuring the fuel, and the fuel injection amount is indirectly measured from this injection time. Yes.

  However, in an injector, there is always a transient state in which the valve is displaced between an open position and a closed position when the valve is opened and closed. In this transient state, since the gap between the valve and the injection port continuously changes, the relationship established between the injection time and the injection amount is not established when the valve is in the open position. Therefore, conventionally, as disclosed in Patent Document 1, the sum of the amount of fuel leaking in the transient state when the valve is opened and the amount of fuel leaking in the transient state when the valve is closed is calculated in the valve open state. It was managed by replacing with the injection time.

  That is, assuming that the injection amount per unit energization time is A, the relationship between the time (drive time) T during which the power supply voltage is applied to the solenoid coil and the injection amount Q is represented by Q = A · T, and the valve is in the open position. The effective injection time Tinj is the injection time when the valve is in the state, and the invalid injection time T0 is the time when the sum of the amount of fuel leaking from the injection port in the transient state when the valve is opened and closed is converted to the injection time when the valve is open The injector drive time Td is set to Td = Tinj + T0.

When the power supply voltage applied to the injector is E, the resistance of the energizing circuit is R, the inductance of the solenoid is L, and the elapsed time from the start of energization is t, the drive current Iinj flowing through the solenoid coil of the injector is expressed by the following equation: be able to.
Iinj = (E / R) [1-exp {-(R / L) t}] (1)

  As is clear from the equation (1), the current flowing through the solenoid coil of the injector increases as the power supply voltage E increases, and increases as the circuit resistance R decreases. Further, the larger the inductance L, the smaller the rate of increase of current with respect to the elapsed time t.

  On the other hand, the force that moves the valve (the magnetomotive force of the solenoid) is proportional to the product N · Iinj (magnetomotive force) of the current Iinj and the number of turns N of the solenoid, so if the value of the current Iinj changes with respect to the elapsed time t. Since the force for moving the valve changes, and the time topen until the valve changes from the closed state to the open state changes, the amount of fuel leaking in the process of the valve changing from the closed state to the open state changes. End up.

  Major factors that cause the current Iinj to change with respect to the elapsed time t include changes in the circuit resistance R and the power supply voltage E. Factors that change the circuit resistance R include heat generated by the engine and fuel in addition to the heat generated by the solenoid itself. Further, factors that cause the power supply voltage E to change include a change in the electromotive force of the battery and a change in voltage caused by a change in the battery internal resistance during charging and discharging of the battery.

  In the prior art, the injector drive circuit is a constant current circuit so that the injector drive current Iinj is not changed in response to fluctuations in the circuit resistance R or the power supply voltage E. However, recently, fuel injection devices are also mounted on engines such as small two-wheeled vehicles, off-road vehicles (ATVs), lawn mowers, and agricultural machinery that are cheaper than automobiles. It has become necessary to reduce the cost, and the cost of the constant voltage circuit has become a problem.

  In view of this, a so-called saturating drive circuit in which the injector drive circuit is configured by a simple semiconductor switch circuit and does not perform current control has come to be used. The saturating drive circuit has the following two improvements.

  The first improvement is to increase the inductance of the solenoid coil by increasing the number of turns of the solenoid coil of the injector so that the fluctuation of the drive current Iinj does not cause a large variation in the injection amount, thereby reducing the drive current. Even in this case, the desired magnetomotive force can be obtained, and the resistance value Rsol of the solenoid coil is increased (using a high resistance type injector) to reduce the drive current Iinj, thereby suppressing the heat generation of the solenoid itself. Thus, the variation factor of the circuit resistance R is reduced. Due to this improvement, heat generation from the injector is reduced, so that the outer dimensions of the injector can be reduced, and it becomes easy to attach the injector to the narrow intake pipe of an engine with a small displacement.

  The second improvement is that the power supply voltage E is measured before the injector drive time is determined, and the invalid injection time T0 is changed in accordance with the measured power supply voltage E, so that the injection amount due to fluctuations in the power supply voltage E can be reduced. This is to correct the fluctuation.

Due to the improvement of the above two points, it has become possible to ensure the required injection amount accuracy with an inexpensive injector driving circuit. In recent years, fuel injection devices using a high resistance type injector and a saturating injector driving circuit have become mainstream. It has become.
JP-A-7-103020

  As described above, the fuel injection device has been applied to an engine that drives an inexpensive vehicle, an agricultural tool, or the like as compared with an automobile, but recently, it is also harsh with an engine that drives these devices. Since exhaust gas regulations have come to be applied, the conventional injection amount accuracy has become unsatisfactory.

Therefore, it is conceivable to improve the injection amount accuracy by using a constant current circuit as an injector drive circuit. However, since the current mainstream of injectors is high resistance injectors, fuel can be used even if an injector drive circuit comprising a constant current circuit is used. The injection quantity accuracy of the injection device cannot be improved. The reason is as follows.
a. Since the resistance value Rsol of the solenoid coil is high, the high resistance injector cannot secure a desired constant current when the power supply voltage E decreases.
b. The constant current circuit cannot suddenly flow a constant current from the start of driving, and cannot control the current until the current reaches a constant current value after the start of driving. The high resistance injector is designed so that the solenoid coil has a large inductance and the valve reaches the open position before the drive current reaches the constant current value after the drive starts. Even if the circuit is used, it is not possible to suppress variations in fuel leaking from the injection port when the valve is opened.

  SUMMARY OF THE INVENTION An object of the present invention is to correct an injector driving time with respect to fluctuations in power supply voltage and fluctuations in circuit resistance of an energization circuit, and to improve the fuel injection amount accuracy and driving the same. The object is to provide an injector drive for use in carrying out the method.

  The present invention is directed to an injector driving method for driving an injector that supplies fuel to an engine. In the present invention, the effective injection time that gives the fuel injection amount calculated with respect to the intake air amount of the engine is calculated as the basic drive time, and the crank angle position of the engine is set to a position suitable as a position to start driving the injector. When the coincidence timing is set as the drive start timing, the power supply voltage is applied to the injector at the drive start timing to start the injector drive, and the measurement of the elapsed time from the drive start timing is started. After starting the injector drive, the timing at which the valve opening of the injector starts or the timing at which the valve opening is completed is estimated as the valve opening timing from the waveform of the drive current flowing through the injector, and the time from the drive start timing to the valve opening timing Using the time as the valve opening time, the difference between the injection amount calculated with respect to the intake air amount and the fuel amount actually injected from the injector approaches zero (the longer the valve opening time, the longer the time for driving the injector). The shorter the valve opening time is, the shorter the time to drive the injector), the basic driving time is corrected according to the valve opening time, the actual driving time of the injector is calculated, and the drive start timing When the elapsed time has reached the actual drive time, the drive of the injector is terminated.

  When the valve opening timing is determined from the waveform of the drive current flowing through the injector as the valve opening timing, and the elapsed time from the driving start timing to the valve opening timing is measured as the valve opening time. The valve opening time reflects the power supply voltage and the resistance value of the solenoid coil.

  The long valve opening time means that the resistance value of the solenoid coil is large or the power supply voltage is low. Conversely, the short valve opening time means that the resistance value of the solenoid coil is small, Or it means that the power supply voltage is high.

  Accordingly, in order to bring the difference between the amount of fuel injected from the injector and the calculated injection amount closer to zero, the longer the valve opening time, the longer the time for driving the injector, and the shorter valve opening time, the injector. The actual drive time is calculated by performing a correction operation on the basic drive time according to the valve opening time so as to shorten the drive time, and the elapsed time from the drive start timing reaches the calculated actual drive time. If the drive of the injector is terminated at this time, when the time until the opening of the injector varies due to a change in the resistance value of the solenoid coil and / or a fluctuation in the power supply voltage, the fluctuation is compensated. Correct the amount of time that the injector is driven by the amount of fuel that flows between the amount of fuel actually injected from the injector and the injection amount calculated for the intake air amount. It is possible to reduce the error, it is possible to increase the injection amount accuracy.

  An injector driving device used to implement the above-described injector driving method includes an injector driving power source that generates a power supply voltage to be applied to the injector to drive the injector, a crank angle detecting unit that detects a crank angle of the engine, An intake air amount detection means for detecting the intake air amount of the engine, a power supply voltage detection means for detecting a power supply voltage, and an air-fuel mixture having a predetermined air-fuel ratio with respect to the intake air amount detected by the intake air amount detection means A basic drive time calculation means for calculating the fuel injection time for providing the fuel injection amount required for the basic drive time, and a drive command at the injector drive start timing detected using the crank angle information detected by the crank angle detection means Drive command signal generating means for generating a signal, and power supply voltage while the drive command signal is being generated. An injector driving circuit for applying a solenoid coil of the injector, a driving current detecting means for detecting a driving current flowing through the injector, a driving current differentiating means for differentiating the driving current detected by the driving current detecting means, and a driving current differentiating means. Valve opening timing estimating means for estimating the opening timing of the injector from the differential value of the generated drive current or the timing of completing the valve opening as the valve opening timing, and from the timing at which the drive command signal is generated to the valve opening timing A valve opening time measuring means for measuring the elapsed time as the valve opening time, a correction value calculating means for calculating a correction value used for obtaining the actual drive time of the injector by correcting the effective injection time, and the valve opening time; During actual driving of the injector by correcting the effective injection time using the calculated correction value Can be the actual drive time calculating means for calculating a, a configuration in which a injection command signal disappears means to extinguish the injection command signal when the elapsed time from the injector drive start timing matches the actual driving time to. In this case, the correction value calculation means increases the actual drive time as the valve opening time is longer so that the difference between the injection amount calculated for the intake air amount and the fuel actually injected from the injector approaches zero. The correction value is calculated such that the longer the valve opening time is, the shorter the actual driving time is.

  As described above, since the power supply voltage and the resistance value of the solenoid coil of the injector are reflected in the valve opening time, if the drive time of the injector is corrected according to the length of the valve opening time, Although it is possible to accurately correct the injector drive time without calculating the invalid injection time, the invalid injection time is calculated with respect to the power supply voltage and is based on the sum of the effective injection time and the invalid injection time. The basic driving time may be corrected according to the valve opening time.

  In such a configuration, the basic drive is performed by adding the effective injection time that gives the fuel injection amount calculated with respect to the intake air amount of the engine and the invalid injection time calculated with respect to the power supply voltage applied to the injector. Calculate the time and start driving the injector by applying the power supply voltage to the injector at the drive start timing with the timing at which the crank angle position of the engine coincides with a suitable position for starting the injector drive. At the same time, the measurement of the elapsed time from the drive start timing is started. After starting the injector drive, the timing at which the valve opening of the injector starts or the timing at which the valve opening is completed is estimated as the valve opening timing from the waveform of the drive current flowing through the injector, and the time from the drive start timing to the valve opening timing Measure the time as the valve opening time, and the basic drive time according to the valve opening time so that the difference between the injection amount calculated for the intake air amount and the fuel amount actually injected from the injector approaches zero The actual drive time is calculated by performing a correction operation on the motor, and the drive of the injector is terminated when the elapsed time from the drive start timing reaches the actual drive time.

  An injector driving device used to implement the above-described injector driving method includes an injector driving power source that generates a power supply voltage to be applied to the injector to drive the injector, a crank angle detecting unit that detects a crank angle of the engine, An intake air amount detection means for detecting the intake air amount of the engine, a power supply voltage detection means for detecting a power supply voltage, and an air-fuel mixture having a predetermined air-fuel ratio with respect to the intake air amount detected by the intake air amount detection means Effective injection time calculation means for calculating the fuel injection time corresponding to the fuel injection amount necessary for the effective injection time, and invalid injection time for calculating the invalid injection time according to the power supply voltage detected by the power supply voltage detection means And a basic drive for calculating the basic drive time of the injector by adding the invalid injection time to the effective injection time A calculation means, a drive command signal generating means for generating a drive command signal at an injector drive start timing detected using crank angle information detected by the crank angle detection means, and a power supply voltage while the drive command signal is generated An injector driving circuit for applying a solenoid coil of the injector, a driving current detecting means for detecting a driving current flowing through the injector, a driving current differentiating means for differentiating the driving current detected by the driving current detecting means, and a driving current differentiating means A valve opening timing estimating means for estimating, as a valve opening timing, a timing at which the valve opening of the injector is started or a timing at which the valve opening is completed from the differential value of the obtained drive current; and the valve opening timing from the timing at which the drive command signal is generated Valve opening time meter that measures the elapsed time until the valve opening time Means for correcting the basic driving time and calculating a correction value used for obtaining the actual driving time with respect to the valve opening time, and correcting the basic driving time by using the correction value. An actual drive time calculating means for calculating the drive time and an injection command signal extinguishing means for extinguishing the injection command signal when the elapsed time from the injector drive start timing coincides with the actual drive time. it can. Also in this case, the correction value calculation means calculates the correction value so that the difference between the injection amount calculated for the intake air amount and the fuel amount actually injected from the injector approaches zero.

  As described above, according to the present invention, after the injector driving is started, the timing at which the valve opening of the injector is started or the timing at which the valve opening is completed is obtained as the valve opening timing from the waveform of the drive current flowing through the injector. Measure the elapsed time from the injector drive start timing to the valve opening timing as the valve opening time, and use the fact that the power supply voltage and the resistance value of the solenoid coil are reflected in this valve opening time. The actual drive time is calculated by performing a correction operation on the basic drive time according to the valve opening time so that the difference between the amount of fuel injected into the engine and the injection amount calculated with respect to the intake air amount approaches zero. Therefore, when the elapsed time from the drive start timing reaches the calculated actual drive time, the drive of the injector is terminated. When the time until the valve opening of the injector is changed due to a change in the resistance value of the noid coil and / or a change in the power supply voltage, the injector driving time is corrected to compensate for the change, and the injector is corrected. Thus, the error between the amount of fuel actually injected and the calculated injection amount can be reduced, and the injection amount accuracy can be improved.

  In particular, according to the first and third aspects of the invention, the process of detecting the power supply voltage and the process of calculating the invalid injection time can be omitted, so that the time required for the process for correcting the drive time is reduced. The control response can be improved by shortening.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of the hardware configuration of an injector driving device according to the present invention. In FIG. 1, reference numeral 1 denotes a fuel that is attached to an intake pipe or a cylinder head of an engine and injects fuel into the intake pipe or the cylinder. It is an injector to inject. An injector 1 is a well-known electromagnetic fuel injection valve having an injection port at a tip, a fuel passage inside, and an injector body in which fuel is supplied at a predetermined pressure in the fuel passage, and the injector A valve that opens and closes the injection port in the body, a solenoid that drives the valve to the open position side when energized, and a return spring that biases the valve to the closed position side. ) By passing an electric current through 100, the valve is displaced to the open position to open the injection port, and when the solenoid coil is de-energized, the valve is returned to the closed position by the biasing force of the return spring to close the injection port. It is configured. In FIG. 1, Lsol and Rsol are the inductance and resistance components of the solenoid coil, respectively.

  One end of the solenoid coil 100 of the injector 1 is connected to a positive output terminal of an unillustrated injector driving power source, and the other end is connected to the drain of the MOSFET F1 constituting the injector driving switch circuit 2. The source of the MOSFET is grounded through the shunt resistor 3, and a power supply voltage E supplied from the injector driving power source is applied to the injector solenoid coil 100 through the injector driving switch 2 and the shunt resistor 3. In this example, an injector drive circuit is configured by a switch circuit made of a MOSFET.

  At both ends of the shunt resistor 3, a current detection signal Vi proportional to the drive current Iinj flowing through the injector is obtained. The current detection signal Vi is input to the differentiation circuit 5 through the voltage follower circuit 4 including the operational amplifier OP1. The differentiating circuit 5 includes an operational amplifier OP2, resistors R1 to R3, and a capacitor C1. A differential value of the injector drive current obtained from the differentiating circuit is input to the input port Pin of the microprocessor 6.

  Connected between output terminals of the power supply for driving the injector is a power supply voltage detection circuit 7 constituted by a resistance voltage dividing circuit composed of resistors R4 and R5 connected in series with each other, and a voltage detection signal obtained from this detection circuit Ve is input to the A / D conversion input terminal ADC of the microprocessor 6. A resistor R6 is connected between the gate of the MOSFET F1 and the ground, and the gate of the MOSFET and the output port Pout of the microprocessor are connected through a resistor R7. The microprocessor 6 gives a drive command signal Sinj from the output port Pout to the MOSFET through the resistor R7.

  Reference numeral 8 denotes a signal coil provided in a signal generator attached to the engine. This signal coil is used when the crank angle position of the engine coincides with the first crank angle position and the second crank angle position, respectively. First and second pulse signals Vs1 and Vs2 having different polarities are generated. In the present embodiment, the first crank angle position is set to a position sufficiently advanced from the crank angle position at which fuel injection is started, and the second crank angle position is the crank angle position at which fuel injection is started (engine Is set equal to the position immediately before the crank angle position at which the intake stroke starts. Pulse signals Vs1 and Vs2 generated by the signal coil 8 are input to the input ports A1 and A2 of the microprocessor 6 through the interface circuits 9 and 10, respectively.

  Although not shown, the microprocessor 6 detects various control conditions used when calculating the fuel injection amount, such as engine intake pipe pressure, throttle opening, intake air temperature, coolant temperature, and atmospheric pressure. Sensor output is input.

  In the injector driving method according to the present embodiment, the effective injection time for giving the fuel injection amount calculated for the intake air amount of the engine and the invalid injection time calculated for the power supply voltage applied to the injector 1 are added. By calculating the basic drive time and applying the power supply voltage to the injector at the drive start timing, the timing at which the crank angle position of the engine coincides with a suitable position for starting the injector drive is determined. The driving is started and the measurement of the elapsed time from the driving start timing is started. After the drive of the injector 1 is started, the timing at which the valve opening of the injector is started or the timing at which the valve opening is completed is estimated as the valve opening timing from the waveform of the drive current flowing through the injector.

  As will be described later, when the valve opening of the injector is started, the increase rate of the drive current of the injector becomes small and shows a maximum value, and when the valve opening of the injector is completed, the drive current of the injector becomes a minimum value. Indicates. Therefore, the timing at which the valve opening of the injector is started by detecting the point at which the increase rate of the drive current becomes smaller, the point at which the drive current shows the maximum value, or the point at which the drive current shows the minimum value is determined from The timing at which the valve opening is completed can be detected.

  When the valve opening timing is estimated as described above, the measured elapsed time is read, and the elapsed time from the drive start timing to the estimated valve opening timing is obtained as the valve opening time. Then, the basic drive time is subjected to a correction operation according to the valve opening time so that the difference between the injection amount calculated with respect to the intake air amount and the fuel amount actually injected from the injector approaches zero. The time is calculated, and the drive of the injector is terminated when the elapsed time from the drive start timing reaches the actual drive time.

  The timing at which the crank angle position of the engine coincides with a suitable position for starting the drive of the injector 1 is set as the drive start timing t1, and the drive command signal Sinj is generated at the drive start timing t1 to turn on the injector drive switch 2 When the power supply voltage is applied to the injector by setting the state, a drive current Iinj flows through the solenoid coil of the injector 1 as shown in FIG. 4, and this drive current increases according to the equation (1). As the drive current Iinj increases, the magnetomotive force of the solenoid increases and the force acting on the injector valve increases. When the force acting on the injector valve exceeds the biasing force of the return spring biasing the valve toward the closed position at time t2, the valve starts to move. Since the valve receives a force in the direction in which the permeance increases, the magnetic path resistance is further reduced by the movement of the valve. Thereby, since the effective magnetic flux linked to the solenoid coil increases, the force for moving the valve increases.

  On the other hand, when the valve moves in the direction of decreasing the magnetic path resistance, the magnetic flux interlinked with the solenoid coil increases, and therefore a voltage in a direction that prevents the magnetic flux from increasing is induced by the inductance of the solenoid coil. As a result, the increase in the drive current Iinj is hindered, so that the increase in the drive current decreases as shown in the Z part of FIG. 4 and decreases after reaching the maximum value at time t3. When the valve reaches the open position at time t4, the valve does not decrease the magnetic path resistance, so that the induced voltage in the direction that hinders the increase in drive current decreases. Therefore, the driving current Iinj increases again after showing a minimum value at the time t4 when the valve reaches the open position, and eventually becomes saturated.

  As described above, the injector drive current Iinj decreases in the process of reaching the open position after the valve starts to move, and increases again after the valve reaches the open position, as shown in part Z of FIG. Since the waveform changes, the timing t2 at which the increase rate of the drive current starts to decrease or the timing t3 at which the waveform of the drive current shows the maximum value can be estimated as the timing at which the valve opening starts, and the timing at which the minimum value is shown. t4 can be estimated as the timing when the valve opening is completed.

  The timing t2 at which the increase rate of the drive current starts to decrease can be obtained by determining whether or not the differential value of the drive current has become equal to or less than a predetermined reference value, and is a timing at which the drive current exhibits a maximum value. t3 can be obtained by determining whether or not the differential value becomes zero in the process of increasing the drive current Iinj. The timing t4 at which the waveform of the drive current shows a minimum value can be obtained by determining whether or not the differential value of the drive current has changed to zero after changing from positive to negative.

  In the present invention, the timing at which the valve opening of the injector is started or the timing at which the valve opening is completed is obtained as the valve opening timing from the waveform of the drive current Iinj flowing through the injector, and the elapsed time from the drive start timing to the valve opening timing ( T12, T13 or T14) in FIG. 4 is measured as the valve opening time.

  The long valve opening time means that the resistance value Rsol of the solenoid coil is large or the power supply voltage is low. Conversely, the short valve opening time means that the resistance value Rsol of the solenoid coil is small. Or the power supply voltage is high. That is, the valve opening time reflects the power supply voltage and the resistance value of the solenoid coil.

  Accordingly, the basic drive time is corrected according to the valve opening time so that the longer the valve opening time, the longer the time for driving the injector, and the shorter valve opening time, the shorter the time for driving the injector. If the actual drive time is calculated and the drive of the injector is terminated when the elapsed time from the drive start timing reaches the calculated actual drive time, the fluctuation of the circuit resistance or the power supply voltage When the time until valve opening is completed fluctuates, the time for driving the injector is changed by that amount, and the injection time with the injector valve in the open position deviates from the calculated injection time. Therefore, it is possible to prevent the fuel injection amount from deviating from the calculated injection amount due to fluctuations in circuit resistance and fluctuations in the power supply voltage. It is Mel possible.

  The microprocessor 6 receives the differential value of the injector drive current obtained from the differentiation circuit 5, the output signal of the power supply voltage detection circuit 7, the output of the signal coil 8, and the outputs of various sensors in the ROM (not shown). By executing the stored predetermined program, various function implementing means necessary for configuring the injector driving device are configured.

  FIG. 2 is a block diagram showing a configuration of an injector driving device including function realizing means constituted by a microprocessor. In the figure, reference numeral 10 denotes an engine, and an injector 1 is mounted so as to inject fuel into an intake pipe of the engine 10. The present invention can be applied to a two-cycle engine or a four-cycle engine having an arbitrary number of cylinders. However, in the present embodiment, the engine 10 is a single-cylinder two-cycle engine in order to simplify the description. To do.

  In FIG. 2, reference numeral 11 denotes an injector driving power source that generates a power source voltage to be applied to the injector 1 to drive the injector 1. As the injector driving power source 11, one that outputs a DC voltage, such as a battery, a generator coil in an AC generator driven by an engine, and a rectifier circuit that rectifies the output of the generator coil is used. be able to.

  Also, 12 is a crank angle detecting means for detecting the crank angle of the engine, 13 is an intake air amount detecting means for detecting the intake air amount of the engine, 14 is a power supply voltage detecting means, and 15 and 16 are effective injection time calculating means and invalidity, respectively. An injection time calculating means 17 is a basic driving time calculating means.

  When the crank angle detection means 12 recognizes the first and second pulse signals Vs1 and Vs2 generated by the signal coil 8, respectively, the crank angle position of the engine becomes the first crank angle position and the second crank angle position. Detect that there is.

  The intake air amount detection means 13 is means for detecting the intake air amount of the engine by an appropriate method. As a method of detecting the intake air amount, a method using an air flow meter (mass flow method), a method of estimating the intake air amount from the engine speed and the intake pipe pressure (speed density method), and the throttle opening A method (throttle speed method) for estimating the intake air amount from the rotational speed of the engine is known, but any of these methods may be used in the present invention.

  The power supply voltage detection means 14 is a means for reading the output of the power supply voltage detection circuit 7 and detecting the power supply voltage applied to the injector, and the effective injection time calculation means 15 is the intake air detected by the intake air amount detection means 13. This is a means for calculating the fuel injection time corresponding to the fuel injection amount required to obtain the air-fuel mixture having a predetermined air-fuel ratio with respect to the air amount as the effective injection time Tinj.

  The invalid injection time calculation means 16 is a means for calculating the invalid injection time T0 in accordance with the power supply voltage detected by the power supply voltage detection means 14, and the basic drive time calculation means 17 is set to the invalid injection time Tinj as the invalid injection time. This is a means for calculating the basic drive time T of the injector by adding T0.

  The effective injection time Tinj is an injection time necessary for injecting a predetermined amount of fuel with the valve in the open position, and the invalid injection time T0 is injected in a transient state when the injector valve is opened and closed. This is the time obtained by converting the sum of the fuel leaking from the mouth into the injection time when the valve is open. The invalid injection time T0 becomes shorter as the power supply voltage applied to the injector is higher.

  In FIG. 2, 18 is a drive start timing detecting means, 19 is a drive command signal generating means, and 20 is an injector drive circuit. The drive start timing detection means 18 is means for detecting the injector drive start timing using the crank angle information detected by the crank angle detection means 12.

  The drive start timing detection means 18 of the present embodiment is a timing at which the signal coil 8 generates the second pulse signal Vs2 at the second crank angle position set immediately before the crank angle position at which the intake stroke of the engine is started. Is detected as the injector drive start timing.

  The drive command signal generation means 19 is a means for generating a drive command signal Sinj from the port Pout at the drive start timing detected by the drive start timing detection means 18, and this drive command signal Sinj is applied to the gate of the MOSFET F1. .

  The injector drive circuit 20 is a circuit that applies the power supply voltage E to the solenoid coil of the injector 1 while the drive command signal Sinj is being generated. As described above, this injector drive circuit is constituted by the switch circuit 2 made of a MOSFET. Has been.

  In FIG. 2, 21 is a drive current detecting means, 22 is a drive current differentiating means, 23 is a valve opening timing estimating means, 24 is time measurement when the drive start timing detecting means 18 detects the drive start timing. Timer means 25, valve opening time measuring means 26, correction value calculating means 26, actual driving time calculating means 27, and injection command signal extinguishing means 28.

  The drive current detection means 21 is a means for detecting the drive current flowing through the solenoid coil of the injector 1. In this embodiment, the drive current detection means 21 is configured by the shunt resistor 3.

  The drive current differentiating means 22 is a means for differentiating the drive current detected by the drive current detecting means 21. In this example, the drive current differentiating means 22 is constituted by the differentiating circuit 5. The valve opening timing estimation means 23 is a timing at which the injector valve starts to move toward the open position from the drive current waveform (timing at which valve opening is started) or timing at which the valve opening operation (valve opening) of the injector is completed. Is a means for detecting as a valve opening timing. The valve opening timing estimation means 23 of the present embodiment estimates the timing at which the opening of the injector is started or the timing at which valve opening is completed from the differential value of the driving current obtained by the driving current differentiation means 22 as the valve opening timing. Configured.

  The valve opening time measuring means 25 measures the elapsed time from the timing when the drive command signal is generated to the valve opening timing as the valve opening time, and reads the measured value of the timer means 24 when the valve opening timing is obtained. Thus, the valve opening time is measured.

  The correction value calculation means 26 is a means for calculating a correction value used for correcting the basic drive time to obtain the actual drive time with respect to the valve opening time, and a correction that gives a relationship between the valve opening time and the correction value. A correction value is calculated by searching a value calculation map for the valve opening time and performing an interpolation calculation as necessary. The correction value calculating means 26 has a long valve opening time so that the difference between the injection amount calculated for the intake air amount by the effective injection time calculating means 15 and the fuel amount actually injected from the injector 1 approaches zero. The correction value is calculated so that the actual driving time is lengthened as the case goes, and the actual driving time is shortened as the valve opening time is shorter. The correction value may be a value that is added to or subtracted from the basic driving time, or may be a value (correction coefficient) that is multiplied by the basic driving time.

  The correction value calculation map, for example, measures the valve opening time for various values of the resistance value of the solenoid coil, and measures the deviation of the injection amount for each valve opening time. Can be created by obtaining a correction value for the drive time required to make the value zero.

  The actual driving time calculation means 27 is a means for calculating the actual driving time by correcting the basic driving time using the correction value, and adds or subtracts the correction value to or from the basic driving time. Thus, the actual driving time is calculated.

  The injection command signal extinguishing means 28 is a means for extinguishing the injection command signal when the elapsed time from the injector drive start timing (the count value of the timer means 24) coincides with the actual drive time.

  FIG. 5 shows an algorithm of an injector drive control process executed by the microprocessor to constitute the injector drive device shown in FIG. 2, and this process is performed before the signal coil 8 is sufficiently before the drive start timing. It is started when the first pulse signal Vs1 is generated at the timing. When the process of FIG. 2 is started, first, in step S1, the amount of fuel supplied into the intake pipe in order to set the air-fuel ratio of the air-fuel mixture to a predetermined value is determined as the intake air amount of the engine, the rotational speed of the engine, It is determined for various control conditions such as temperature (cooling water temperature), intake air temperature, and atmospheric pressure. When determining the amount of fuel to be supplied into the intake pipe, first, the amount of fuel required to bring the air-fuel ratio of the mixture to a predetermined value is calculated as the reference fuel amount with respect to the intake air amount, and various control conditions Is calculated by multiplying the reference fuel amount by the correction coefficient obtained by the map operation.

  After determining the amount of fuel to be supplied to the engine in step S1, the injector drive time is determined in step S2. When determining the injector driving time, first, the amount of fuel to be supplied is converted into an injection time when the injector valve is in the open position, and this injection time is set as an effective injection time Tinj. Further, the invalid injection time T0 is calculated for the power supply voltage supplied from the injector driving power source, and the invalid injection time T0 is added to the effective injection time Tinj to calculate the injector driving time Td. This injector driving time Td is set as a basic driving time.

  Next, the process proceeds to step S3, where it is determined whether or not the current timing is the drive start timing (whether or not the signal coil has generated the second pulse signal). When it is determined in step S3 that the current timing is the drive start timing (when the signal coil generates the second pulse signal), the power supply voltage is applied to the injector in step S4 to start driving the injector. . At this time, the timer is activated to start measuring the elapsed time from the drive start timing.

  After starting the injector drive, in step S5, it is determined whether or not the differential value of the drive current obtained from the differentiation circuit 5 is below the reference value (whether or not the increase rate of the drive current has decreased to the reference value). To do. When it is determined that the differential value of the drive current is equal to or less than the reference value (at time t2 in FIG. 4), the elapsed time (T12) from the drive start timing of the injector to the present time is defined as the valve opening time. On the other hand, by calculating the drive correction time to be added to or subtracted from the basic drive time to calculate the actual drive time of the injector as a correction value, and adding this correction value to the basic drive time or subtracting it from the basic drive time Calculate the actual drive time.

  In step S7, it is determined whether or not the current timing is the driving end timing. When it is determined that the current timing is the driving end timing (when the elapsed time from the driving start timing reaches the actual driving time). In step S8, the drive command signal Sinj is extinguished to turn off the MOSFET F1, thereby removing the power supply voltage applied to the injector and terminating the drive of the injector.

  In the case of the algorithm shown in FIG. 5, the effective injection time calculation means 15, the invalid injection time calculation means 16 and the basic drive time calculation means 17 are configured by steps S1 and S2, and the drive start timing detection means is determined by step S3. 18 is configured. Further, the drive command signal generating means 19 is constituted by step S4, and the valve opening timing estimating means 23 is constituted by step S5. Further, the valve opening time measuring means 25, the correction value calculating means 26, and the actual driving time calculating means 27 are configured by step 6, and the injection command signal extinguishing means 28 is configured by steps S7 and S8.

  1, the crank angle detecting means 12 is provided by the signal coil 8, the power supply voltage detecting means 14 is provided by the power supply voltage detecting circuit 7, the injector drive circuit 20 is provided by the injector drive switch 2, and the shunt resistor 3 and the voltage holo. The driver circuit 4 and the differentiating circuit 5 constitute the driving current detecting means 21 and the differentiating circuit 5, respectively.

  The intake air amount detection means 13 in FIG. 2 is configured by a process different from the process shown in FIG.

  In the above embodiment, the fuel injection amount is calculated with respect to the intake air amount, and this injection amount is converted into the injection time. However, when the pressure of the fuel applied to the injector is constant and known The effective injection is performed by directly calculating the basic injection time required to bring the air-fuel ratio of the air-fuel mixture to a predetermined value with respect to the intake air amount and correcting the basic injection time for various conditions. It is also possible to calculate time.

  In the above embodiment, the basic injection time Td is calculated by calculating the invalid injection time T0 with respect to the power supply voltage applied to the injector, and adding this invalid injection time to the effective injection time Tinj. Is corrected for the valve opening time, but not only the resistance value of the solenoid coil but also the power supply voltage is reflected in the valve opening time. The time Tinj is set as a basic drive time, a correction value for correcting the basic drive time with respect to both the power supply voltage and the resistance value of the solenoid coil is calculated with respect to the valve opening time, and the correction value is used. The actual driving time may be obtained by correcting the basic driving time.

  FIG. 3 shows the configuration of the injector driving device in such a configuration. The basic drive time calculation means 17 shown in FIG. 3 calculates the effective injection time required for setting the air-fuel ratio of the air-fuel mixture to a predetermined value with respect to the intake air amount as the basic drive time. The correction value calculation means 26 calculates a correction value used for calculation for correcting the effective injection time for both the power supply voltage and the resistance value of the solenoid coil. The actual drive time calculation means 27 calculates the actual drive time by correcting the effective injection time (basic drive time) using the correction value. The other points are the same as the example shown in FIG.

  In the case of the configuration shown in FIG. 3, the power supply voltage detection means and the invalid injection time calculation means are not required, so that the configuration of the drive device can be simplified compared to the example shown in FIG. Responsiveness can be improved by simplifying the processing for calculating time.

  In the above description, the engine is a single cylinder, but it goes without saying that the present invention can be applied to driving an injector attached to a multi-cylinder engine having two or more cylinders. A signal for detecting the crank angle position is generated for each cylinder.

  In the above description, the engine is a two-cycle engine, but the present invention can of course be applied to a four-cycle engine. When applied to a 4-cycle engine, a means for detecting the intake stroke (injection start position) of the engine, for example, an appropriate one before the top dead center of the intake stroke of each cylinder is synchronized with the rotation of the camshaft. A sensor for generating a pulse signal at the position is provided.

  In the above description, a high resistance type injector is used and a saturating type circuit (simple switch circuit) is used as the injector driving circuit. However, an injector driving circuit comprising a conventional low resistance type injector and a constant current circuit. Even when the valve is used, if the valve opening is completed before the injector driving current reaches a constant current, the present invention is applied to correct the actual driving time of the injector according to the valve opening time. Is possible. Therefore, the present invention is not limited to the case of using a high resistance type injector and a saturating injector drive circuit.

  In the example shown in FIG. 5, the process from the determination of the amount of fuel to be supplied to the engine to the end of the drive of the injector is performed in a continuous process, but other controls such as the control of the ignition device are performed in parallel. In order to perform this, for example, steps S1 and S2 in FIG. 5 may be independent drive time determination processes, and steps S3 to S8 may be injector drive processes, and the respective processes may be repeatedly executed at minute time intervals. In the case of such a configuration, when “No” is determined in steps S3, S5, and S7 of the injector driving process, the injector driving process is exited without waiting for the determination of “Yes”.

It is the circuit diagram which showed the structural example of the hardware of embodiment of this invention. It is the block diagram which showed the structure of 1st Embodiment of the injector drive device concerning this invention. It is the block diagram which showed the structure of 2nd Embodiment of the injector drive device concerning this invention. It is the graph which showed an example of the time change of the drive current which flows at the time of the drive of an injector. FIG. 3 is a flowchart showing an example of a processing algorithm executed by a microprocessor in order to configure the injector driving device shown in FIG. 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injector 2 Injector drive switch 3 Shunt resistor 5 Differentiation circuit 6 Microprocessor 7 Power supply voltage detection circuit 10 Engine 11 Injector drive power supply 13 Intake air amount detection means 14 Power supply voltage detection means 15 Effective injection time calculation means 16 Invalid injection time Calculation means 17 Basic drive time calculation means 18 Drive start timing detection means 19 Drive command signal generation means 20 Injector drive circuit 21 Drive current detection means 22 Drive current differentiation means 23 Valve opening timing estimation means 24 Timer means 25 Valve opening time measurement means 26 Correction value calculation means 27 Actual drive time calculation means 28 Injection command signal extinction means

Claims (4)

An injector driving method for driving an injector for supplying fuel to an engine,
An effective injection time giving the fuel injection amount calculated with respect to the intake air amount of the engine is calculated as a basic drive time,
The driving of the injector is started by applying a power supply voltage to the injector at the driving start timing with the timing at which the crank angle position of the engine coincides with a position suitable as a position for starting driving of the injector. At the same time, start measuring the elapsed time from the drive start timing,
From the waveform of the drive current flowing through the injector, the timing at which the valve opening of the injector is started or the timing at which valve opening is completed is estimated as the valve opening timing,
Using the elapsed time from the drive start timing to the valve opening timing as the valve opening time, the difference between the injection amount calculated with respect to the intake air amount and the fuel amount actually injected from the injector is brought close to zero. In addition, the actual driving time of the injector is calculated by performing a correction operation on the basic driving time according to the valve opening time,
Ending driving of the injector when an elapsed time from the driving start timing reaches the actual driving time;
An injector driving method characterized by the above. An injector driving method for driving an injector for supplying fuel to an engine,
The basic drive time is calculated by adding the effective injection time that gives the fuel injection amount calculated with respect to the intake air amount of the engine and the invalid injection time calculated with respect to the power supply voltage applied to the injector,
The driving of the injector is started by applying a power supply voltage to the injector at the driving start timing with the timing at which the crank angle position of the engine coincides with a position suitable as a position for starting driving of the injector. At the same time, start measuring the elapsed time from the drive start timing,
From the waveform of the drive current flowing through the injector, the timing at which the valve opening of the injector is started or the timing at which valve opening is completed is estimated as the valve opening timing,
The elapsed time from the drive start timing to the valve opening timing is measured as the valve opening time, and the difference between the injection amount calculated for the intake air amount and the fuel amount actually injected from the injector is zero. So that the basic drive time is corrected according to the valve opening time to calculate the actual drive time,
Ending driving of the injector when an elapsed time from the driving start timing reaches the actual driving time;
An injector driving method characterized by the above. An injector driving device for driving an injector for supplying fuel to an engine,
An injector driving power source for generating a power source voltage to be applied to the injector to drive the injector;
Crank angle detecting means for detecting the crank angle of the engine;
Intake air amount detection means for detecting the intake air amount of the engine;
Power supply voltage detecting means for detecting the power supply voltage;
Basic drive time calculation means for calculating, as a basic drive time, a fuel injection time that gives a fuel injection amount necessary to obtain a mixture of a predetermined air-fuel ratio with respect to the intake air amount detected by the intake air amount detection means When,
Drive command signal generation means for generating a drive command signal at an injector drive start timing detected using crank angle information detected by the crank angle detection means;
An injector drive circuit for applying the power supply voltage to a solenoid coil of the injector while the drive command signal is generated;
Drive current detection means for detecting drive current flowing through the injector;
Drive current differentiation means for differentiating the drive current detected by the drive current detection means;
A valve opening timing estimating means for estimating a timing at which valve opening of the injector is started or a timing at which valve opening is completed as a valve opening timing from a differential value of the driving current obtained by the driving current differentiating means;
A valve opening time measuring means for measuring an elapsed time from the timing at which the drive command signal is generated to the valve opening timing as a valve opening time;
Correction value calculation means for calculating the correction value used for correcting the effective injection time and obtaining the actual drive time of the injector with respect to the valve opening time;
Actual driving time calculating means for calculating the actual driving time of the injector by correcting the effective injection time using the correction value;
Injection command signal extinguishing means for extinguishing the injection command signal when the elapsed time from the injector drive start timing coincides with the actual drive time;
Comprising
The correction value calculating means calculates the correction value so that a difference between an injection amount calculated with respect to the intake air amount and a fuel amount actually injected from the injector approaches zero. Injector drive device. An injector driving device for driving an injector for supplying fuel to an engine,
An injector driving power source for generating a power source voltage to be applied to the injector to drive the injector;
Crank angle detecting means for detecting the crank angle of the engine;
Intake air amount detection means for detecting the intake air amount of the engine;
Power supply voltage detecting means for detecting the power supply voltage;
Effective injection time calculation for calculating, as an effective injection time, a fuel injection time corresponding to a fuel injection amount required to obtain a mixture having a predetermined air-fuel ratio with respect to the intake air amount detected by the intake air amount detection means Means,
An invalid injection time calculating means for calculating an invalid injection time according to the power supply voltage detected by the power supply voltage detecting means;
Basic driving time calculating means for calculating the basic driving time of the injector by adding the invalid injection time to the effective injection time;
Drive command signal generation means for generating a drive command signal at an injector drive start timing detected using crank angle information detected by the crank angle detection means;
An injector drive circuit for applying the power supply voltage to a solenoid coil of the injector while the drive command signal is generated;
Drive current detection means for detecting drive current flowing through the injector;
Drive current differentiation means for differentiating the drive current detected by the drive current detection means;
A valve opening timing estimating means for estimating a timing at which valve opening of the injector is started or a timing at which valve opening is completed as a valve opening timing from a differential value of the driving current obtained by the driving current differentiating means;
A valve opening time measuring means for measuring an elapsed time from the timing at which the drive command signal is generated to the valve opening timing as a valve opening time;
A correction value calculating means for calculating a correction value used for correcting the basic driving time and obtaining an actual driving time with respect to the valve opening time;
An actual driving time calculating means for calculating an actual driving time by correcting the basic driving time using the correction value;
Injection command signal extinguishing means for extinguishing the injection command signal when the elapsed time from the injector drive start timing coincides with the actual drive time;
Comprising
The correction value calculating means calculates the correction value so that a difference between an injection amount calculated with respect to the intake air amount and a fuel amount actually injected from the injector approaches zero. Injector drive device.

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