JP6483495B2 - Boost control device for fuel injection valve - Google Patents

Description

  The present invention relates to a boost control device for a fuel injection valve that controls boosting of a voltage applied to the fuel injection valve in order to drive an electromagnetic fuel injection valve provided in an internal combustion engine or the like.

  2. Description of the Related Art Conventionally, for example, a device disclosed in Patent Document 1 is known as an application of this type of boost control device to a fuel injection control device for an internal combustion engine for a vehicle. This fuel injection control device includes a booster circuit in the ECU for boosting the voltage of a battery mounted on the vehicle. By applying the boosted high voltage to an electromagnetic fuel injection valve, the fuel injection control device The response of the injection valve is improved and the valve is opened quickly. Further, the fuel injection control device detects the valve closing timing when the fuel injection valve is fully closed by detecting the inflection point of the waveform of the current or voltage supplied to the fuel injection valve. Yes. Then, based on the valve closing timing, the power feeding time for the fuel injection valve is corrected so that an appropriate fuel injection amount can be obtained.

  Also, in a fuel injection control device equipped with a booster circuit, since the boosted voltage of the booster circuit generally decreases due to the application of a high voltage from the booster circuit to the fuel injection valve, in preparation for the next high voltage application after the application. Thus, the boosting operation is performed in the boosting circuit.

JP 2014-55571 A

  In the booster circuit described above, a large current is generated when the boosting operation is performed. When such a large current flows to the reference ground in the ECU, so-called ground floating may occur in which the potential of the reference ground fluctuates to a side higher than 0V. In this case, since the ground floating occurs even in the logic ground that is the reference of the CPU in the ECU, the input signal to the CPU based on the voltage value may fluctuate with the ground floating. As a result, the closing timing of the fuel injection valve cannot be detected properly, and the detection accuracy is lowered.

  The present invention has been made in order to solve the above-described problems, and the detection accuracy of the closing timing of the fuel injection valve is ensured while ensuring proper opening by applying a boosted voltage to the fuel injection valve. An object of the present invention is to provide a boost control device for a fuel injection valve that can be improved.

In order to achieve the above object, the invention according to claim 1 is directed to boost control for a fuel injection valve that controls boosting of a voltage applied to the fuel injection valve 4 in order to drive the electromagnetic fuel injection valve 4. A booster circuit 20 for boosting a voltage VB of a power source (battery 11 in the embodiment (hereinafter the same in this section)) and a booster circuit 20 for opening the fuel injection valve 4. The closing means for detecting the closing timing of the fuel injection valve 4 based on the application means (ECU 2) for applying the boosted voltage VC to the fuel injection valve 4 and the current IAC or voltage VINJ energized to the fuel injection valve 4 a timing detection means (ECU 2), and executes a boosting operation by the boosting circuit 20 during application of a drive voltage to at least the fuel injection valve 4, when detecting the closing timing, the step-up circuit 2 Characterized in that it comprises a control for controlling means (ECU 2) to stop the boosting operation by.

According to this configuration, the fuel injection valve can be quickly opened with high responsiveness by boosting the voltage of the power supply by the boosting circuit and applying the boosted voltage to the fuel injection valve. Further, at least during the application of the drive voltage to the fuel injection valve, the control means performs the boosting operation by the boosting circuit, and based on the current or voltage supplied to the fuel injection valve by the valve closing timing detection means, When detecting the valve closing timing when the fuel injection valve is fully closed, the control means stops the boosting operation by the boosting circuit. As a result, a large current generated when the boosting operation is performed does not flow to, for example, the reference ground in the ECU when the closing timing of the fuel injection valve is detected, and the ground floating can be prevented. As a result, the valve closing timing detecting means can appropriately detect the valve closing timing of the fuel injection valve, and the detection accuracy can be improved.

  According to a second aspect of the present invention, in the boost control device for a fuel injection valve according to the first aspect, the target boost voltage setting means for setting the target boost voltage VCOBJ as the target value of the boost voltage VC controlled by the control means. (ECU 2) is further provided, and the application means applies the boosted voltage VC (high voltage VINJH) to the fuel injection valve 4 to open the fuel injection valve 4, and then holds the fuel injection valve 4 in an open state. Therefore, the application voltage (drive voltage VINJ) of the fuel injection valve 4 is switched to the power supply voltage VB (low voltage VINJL), and the application voltage (drive voltage VINJ) of the fuel injection valve 4 is the boost voltage ( When switching from the high voltage VINJH) to the power supply voltage (low voltage VINJL) (timing t2 in FIG. 3), the control means executes the boosting operation by the boosting circuit 20, and the target boosting Pressure setting means and sets the target boost voltage VCOBJ to a larger value (high target VCOBJH).

  According to this configuration, after the boosted voltage is applied to the fuel injection valve by the applying means, the applied voltage is switched to the power supply voltage. As a result, the fuel injection valve can be quickly opened with high responsiveness, and can be appropriately held in the valve open state by the power supply voltage lower than the boosted voltage.

  Further, when the applied voltage of the fuel injection valve is switched from the boosted voltage to the power supply voltage, the boosting operation by the boosting circuit is executed by the control means, and the target boosted voltage setting means sets the target boosted voltage to a larger value. In this case, the boosting degree is increased by controlling the boosted voltage by the booster circuit to be a target boosted voltage set to a larger value by the control means. For this reason, the boosted voltage reduced by the application to the fuel injection valve can be quickly increased, thereby ensuring a sufficient boosted voltage in preparation for the next application to the fuel injection valve.

  According to a third aspect of the present invention, in the step-up control device for a fuel injection valve according to the first aspect, the application means applies the boost voltage VC (high voltage VINJH) to the fuel injection valve in order to open the fuel injection valve 4. 4 is configured to switch the applied voltage (drive voltage VINJ) of the fuel injection valve 4 to the power supply voltage VB (low voltage VINJL) in order to keep the fuel injection valve 4 in an open state after being applied to When the applied voltage (driving voltage VINJ) of the fuel injection valve 4 is switched from the boosted voltage (high voltage VINJH) to the power supply voltage (low voltage VINJL) (timing t12 in FIG. 4), the control means boosts by the booster circuit 20 The operation is started, and thereafter, when the first predetermined time TA1 has elapsed (timing t13 in FIG. 4), the boosting operation is stopped.

  According to this configuration, similarly to the second aspect, the fuel injection valve can be quickly opened with high responsiveness, and can be appropriately held in the opened state. Further, when the voltage applied to the fuel injection valve by the applying means is switched from the boosted voltage to the power supply voltage, the boosting operation by the boosting circuit is started, and then the boosting operation is stopped when the first predetermined time has elapsed. . By setting a time shorter than the time from when the applied voltage to the fuel injector switches to the closing timing of the fuel injector as the first predetermined time, the application of the power supply voltage to the fuel injector is completed. At the time, that is, when the closing timing of the fuel injection valve is detected by the valve closing timing detecting means, it is possible to increase the boosted voltage to some extent before the stop while ensuring the stop of the boosting operation by the booster circuit.

  According to a fourth aspect of the present invention, in the step-up control device for a fuel injection valve according to the third aspect, the operating state detecting means for detecting the operating state of the internal combustion engine 3 (ECU 2, crank angle sensor 61, accelerator opening sensor 62). ) And boosting operation time setting means (ECU2) for setting the first predetermined time TA1 in accordance with the detected operating state of the internal combustion engine 3.

  According to this configuration, the operation state of the internal combustion engine can be detected by the operation state detection means, and the first predetermined time can be appropriately set according to the detected operation state. For example, the higher the number of revolutions of the internal combustion engine, the shorter the valve opening time of the fuel injection valve and the earlier the valve closing timing. Therefore, when the rotational speed of the internal combustion engine is high, the boosting operation by the booster circuit can be appropriately stopped before the closing timing of the fuel injection valve by shortening the first predetermined time.

  According to a fifth aspect of the present invention, in the boost control device for a fuel injection valve according to the first aspect, the application means applies the boost voltage VC (high voltage VINJH) to the fuel injection valve in order to open the fuel injection valve 4. 4 is configured to switch the applied voltage (drive voltage VINJ) of the fuel injection valve 4 to the power supply voltage VB (low voltage VINJL) in order to keep the fuel injection valve 4 in an open state after being applied to When the applied voltage (drive voltage VINJ) of the fuel injection valve 4 is switched from the boosted voltage (high voltage VINJH) to the power supply voltage (low voltage VINJL) (timing t22 in FIG. 5), the control means boosts by the booster circuit 20 When the operation is started and the second predetermined time TA2 has elapsed from the start of application of the boost voltage (high voltage VINJH) to the fuel injection valve 4 (timing t23 in FIG. 5), the boost operation Wherein the stopping.

  According to this configuration, the fuel injection valve can be quickly opened with high responsiveness and can be appropriately held in the opened state, as in the above-described claims 2 and 3. Further, when the voltage applied to the fuel injection valve by the applying means is switched from the boosted voltage to the power supply voltage, the boosting operation by the boosting circuit is started, and the second predetermined time from the start of the application of the boosted voltage to the fuel injector When elapses, the boosting operation is stopped. By setting, as the second predetermined time, a time from the start of applying the boosted voltage to the fuel injection valve to the closing timing of the fuel injection valve, that is, a predetermined time shorter than the opening time of the fuel injection valve As in the third aspect, when the closing timing of the fuel injection valve is detected, the boost voltage can be increased to some extent before the boost operation is stopped while ensuring the stop of the boost operation by the boost circuit.

  According to a sixth aspect of the present invention, in the step-up control device for a fuel injection valve according to the fifth aspect, the control means is configured such that when a predetermined first stop time TS1 elapses after the pressure-up operation is stopped (FIG. 5). In step t25), the boosting operation is resumed.

  According to this configuration, by appropriately setting the first stop time described above, the fuel injection valve is closed after the fuel injection valve is closed while ensuring the stop of the boost operation by the booster circuit at the closing timing of the fuel injection valve. Thus, the boosting operation by the boosting circuit can be restarted appropriately.

  According to a seventh aspect of the present invention, in the boost control device for a fuel injection valve according to the first aspect, the application means applies the boost voltage VC (high voltage VINJH) to the fuel injection valve in order to open the fuel injection valve 4. 4 is configured to switch the applied voltage (drive voltage VINJ) of the fuel injection valve 4 to the power supply voltage VB (low voltage VINJL) in order to keep the fuel injection valve 4 in an open state after being applied to When the applied voltage (drive voltage VINJ) of the fuel injection valve 4 is switched from the boosted voltage (high voltage VINJH) to the power supply voltage (low voltage VINJL) (timing t22 in FIG. 5), the control means boosts by the booster circuit 20 The operation is started, and at the third predetermined time TA3 before the end of application of the power supply voltage (low voltage VINJL) to the fuel injection valve 4 (timing t24 in FIG. 5) (timing in FIG. 5). 23), characterized in that to stop the boosting operation.

  According to this configuration, the fuel injection valve can be quickly opened with high responsiveness and can be appropriately held in the opened state, as in the above-described claims 2 and 3. In addition, when the voltage applied to the fuel injection valve by the applying means is switched from the boosted voltage to the power supply voltage, the boosting operation by the booster circuit is started, and the third predetermined time is higher than when the application of the power supply voltage to the fuel injector is finished. Before the time, the boosting operation is stopped. By setting the shortest possible time as the third predetermined time, the boosted voltage can be further increased by executing the boosting operation before the boosting operation is stopped by the boosting circuit.

  According to an eighth aspect of the present invention, in the boost control device for a fuel injection valve according to the seventh aspect, the control means is configured to terminate the application of the power supply voltage (low voltage VINJL) to the fuel injection valve 4 (see FIG. 5). The step-up operation is restarted when a predetermined second stop time TS2 has elapsed from the timing t24) (timing t25 in FIG. 5).

  According to this configuration, by appropriately setting the second stop time, it is possible to ensure that the boost operation by the boost circuit is stopped at the closing timing of the fuel injection valve, while the fuel injection valve is closed. Thus, the boosting operation in the boosting circuit can be restarted appropriately.

1 is a diagram schematically showing a boost control device for a fuel injection valve according to an embodiment of the present invention, together with an internal combustion engine to which the boost control device is applied. It is a circuit diagram which shows the drive circuit for driving a fuel injection valve. It is a timing chart which shows the 1st operation example by pressure | voltage rise control processing. It is a timing chart which shows the 2nd operation example by pressure | voltage rise control processing. It is a timing chart which shows the 3rd operation example by pressure | voltage rise control processing.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. An internal combustion engine (hereinafter referred to as “engine”) 3 shown in FIG. 1 is a gasoline engine for vehicles having, for example, four cylinders (not shown). Each cylinder has a fuel injection valve (hereinafter referred to as “injector”). 4 is provided, and fuel is directly injected from the injector 4 into a combustion chamber (not shown). The operation of the injector 4 is controlled by an ECU 2 described later.

  The injector 4 is of an electromagnetic type, and although not shown, an electromagnet fixed to the upper end in the casing, an armature disposed below the electromagnet, and disposed between these electromagnets and the armature. It comprises a spring and a valve body provided integrally below the armature. The electromagnet has a yoke and a coil 4a wound around the yoke, and a drive circuit 10 shown in FIG. 2 is connected to the coil 4a. Further, the spring is provided so as to bias the valve body toward the valve closing side.

  FIG. 2 shows the drive circuit 10 included in the ECU 2. As shown in the figure, the drive circuit 10 includes a booster circuit 20 for boosting the voltage (for example, 12V) of the battery 11 and an injector drive for driving the injector 4 by applying a voltage to the coil 4a of the injector 4. The circuit 30 is configured. The operations of these circuits 20 and 30 are controlled by a CPU 40 described later. The battery 11 is charged using a generator (not shown) that uses the engine 3 as a power source.

  The booster circuit 20 includes a first switch 21, a second switch 22, a coil 23, a diode 24, and a capacitor 25. The first switch 21 is composed of an N-channel FET, and its drain is connected to the output side of the coil 23 connected to the battery 11. The source and gate of the first switch 21 are connected to the ground and the CPU 40, respectively. When the first drive signal SD1 is input to the gate from the CPU 40, the first switch 21 is turned on and the drain-source is energized.

  The second switch 22 is also composed of an N-channel type FET, and its drain is connected between the first switch 21 and the coil 23. The source and gate of the second switch 22 are connected to the capacitor 25 and the CPU 40, respectively. When the second drive signal SD2 is input to the gate from the CPU 40, the second switch 22 is turned on and the drain-source is energized.

  The diode 24 is provided in parallel with the second switch 22, the anode side thereof being connected to the drain of the second switch 22, and the cathode side being connected to the source of the second switch 22.

  In the booster circuit 20, a boosting operation is performed as follows. First, the first drive signal SD1 is output, and the first switch 21 is turned on. As a result, when the voltage VB of the battery 11 (hereinafter referred to as “battery voltage”) VB is applied to the coil 23, the coil current IL flows through the coil 23 and electric energy is stored.

  From this state, the output of the first drive signal SD1 is stopped, the first switch 21 is turned OFF, and immediately after that, the second drive signal SD2 is output and the second switch 22 is turned ON. As a result, the electrical energy stored in the coil 23 is supplied to the capacitor 25 via the second switch 22 and stored. As a result, the coil current IL decreases and the voltage of the capacitor 25 (hereinafter referred to as “capacitor voltage”) VC increases.

  Thereafter, the output of the second drive signal SD2 is stopped, the second switch 22 is turned OFF, and immediately thereafter, the first drive signal SD1 is output and the first switch 21 is turned ON, whereby the coil 23 is electrically connected. Energy is stored again. Thereafter, similarly, the boosting operation is performed by alternately switching the ON operation of one of the first and second switches 21 and 22 and the OFF operation of the other of the first and second switches 21 and 22 in synchronization with each other.

  The injector drive circuit 30 includes third to fifth switches 31 to 33 each formed of an N-channel FET, a Zener diode 34, and the like.

  The drain, source, and gate of the third switch 31 are connected to the booster circuit 20, one end of the coil 4a of the injector 4, and the CPU 40, respectively. When the third drive signal SD3 is input from the CPU 40 to this gate, the third switch 31 is turned on and the drain-source is energized.

  The drain, source, and gate of the fourth switch 32 are connected to the battery 11, one end of the coil 4a of the injector 4, and the CPU 40, respectively. When the fourth drive signal SD4 is input from the CPU 40 to this gate, the fourth switch 32 is turned on, and the drain-source is energized.

  The drain, source, and gate of the fifth switch 33 are connected to the other end of the coil 4a of the injector 4, the ground, and the CPU 40, respectively. When the fifth drive signal SD5 is input from the CPU 40 to this gate, the fifth switch 33 is turned on and the drain-source is energized.

  The Zener diode 34 has an anode side connected to the ground and a cathode side connected to the other end of the coil 4 a of the injector 4.

  With the above configuration, in this injector drive circuit 30, the third to fifth switches 31 to 33 are switched on / off in accordance with the third to fifth drive signals SD3 to SD5 from the CPU 40, and the coil 4a of the injector 4 is switched. The operation of the injector 4 is controlled by controlling the voltage application state.

  Specifically, when the third to fifth switches 31 to 33 are in the OFF state, the coil 4a of the injector 4 is not applied, and the drive current IAC does not flow through the coil 4a. By being located at the valve closing position by the urging force of the spring, the valve is kept closed.

  When the third and fifth switches 31 and 33 are turned on from this state, the boosted capacitor voltage VC is applied to the coil 4a of the injector 4, whereby a large drive current IAC flows through the coil 4a, and the electromagnet of the injector 4 Is overexcited (overexcitation control). By this overexcitation, the valve body is pulled toward the open side against the biasing force of the spring, whereby the injector 4 is opened and fuel is injected from the injector 4.

  After that, when the third switch 31 is turned off to finish the application of the capacitor voltage VC and the fourth switch 32 is turned on, the battery voltage VB is applied to the coil 4a of the injector 4. As a result, when the small drive current IAC flows through the coil 4b, the injector 4 is held in the valve open state, and fuel injection is continued (holding control).

  When the fourth and fifth switches 32 and 33 are turned off from this state, the application of the battery voltage VB is completed, and accordingly, the valve body is returned to the valve closing position where the valve body is fully closed by the biasing force of the spring. The injector 4 is closed, and the fuel injection is completed. Further, the current remaining in the coil 4a of the injector 4 flows to the ground via the Zener diode 34, whereby the electromagnet of the injector 4 is brought into a non-excited state.

  As described above, when the injector 4 is opened, by first performing overexcitation control, by applying the boosted capacitor voltage VC to the coil 4a of the injector 4 and overexciting the electromagnet, Sufficient magnetic force is secured to quickly open the injector 4 against the high fuel pressure. Further, subsequently, holding control is executed, and the battery voltage VB is applied to the coil 4a, whereby the valve opening state of the injector 4 is held in a state where power consumption is suppressed.

  Further, as shown in FIG. 1, the booster circuit 20 and the injector driving circuit 30 are provided with voltmeters 51 and 52, respectively. The former voltmeter 51 detects the capacitor voltage VC and outputs the detection signal to the CPU 40, while the latter voltmeter 52 detects the drive voltage VINJ of the injector 4 and outputs the detection signal to the CPU 40.

  The crankshaft (not shown) of the engine 3 is provided with a crank angle sensor 61 (operating state detecting means). The crank angle sensor 61 outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft rotates.

  The CRK signal is output every predetermined crank angle (for example, 1 °). The ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that a piston (not shown) is in a predetermined crank angle position slightly before the top dead center at the start of the intake stroke in any cylinder. When the engine 3 is a 4-cylinder type as described above, it is output every 180 degrees of crank angle.

  Further, a detection signal representing the depression amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle is output from the accelerator opening sensor 62 (operating state detection means) to the ECU 2.

  The CPU 40 constitutes an ECU 2 including a microcomputer together with a RAM, a ROM, an I / O interface (all not shown), and the like. The ECU 2 controls the ON / OFF of the first and second switches 21 and 22 in accordance with a control program stored in the ROM, and controls the boosting operation of the booster circuit 20 and the third to fifth switches 31 to 31. By controlling ON / OFF of 33, the injector 4 is driven to execute fuel injection control for controlling the fuel injection amount and fuel injection timing. The ECU 2 corresponds to the application means, valve closing timing detection means, control means, target boost voltage setting means, operating state detection means, and boost operation time setting means of the present invention.

  Although detailed description is omitted, the ECU 2 detects the closing timing of the injector 4 based on the driving current IAC or the driving voltage VINJ of the injector 4 energized to the coil 4a. This detection can be performed, for example, by detecting the inflection point of the waveform of the drive current IAC or the drive voltage VINJ of the injector 4 in the same manner as the above-described prior art.

  Next, boost control when performing fuel injection control by applying the drive voltage VINJ to the injector 4 will be described with reference to the timing charts of FIGS. 3 to 5 correspond to the crank angle of the engine 3 and are determined according to the operating state of the engine 3 and the like. In the following description, the above-described capacitor voltage VC stored in the capacitor 25 by the boosting operation of the booster circuit 20 is referred to as “boosted voltage VC”.

  FIG. 3 shows an operation example when the target boosted voltage VCOBJ, which is the target value of the boosted voltage VC by the booster circuit 20, is set to a larger value during application of the drive voltage VINJ to the injector 4 (hereinafter referred to as “first operation”). Example)). As shown in FIGS. 4A to 4E, immediately before the application of the drive voltage VINJ to the injector 4 (immediately before the timing t1), the drive voltage VINJ is 0 V, and the target boost voltage VCOBJ is a normal target voltage. The value VCOBJL (for example, 40V), the boosted voltage VC of the booster circuit 20 is the high voltage VCH (for example, 40V), the boosting operation by the boosting circuit 20 is stopped, and the boosting operation stop signal is turned off. ing.

  As shown in FIG. 3, first, at the timing t1, the high voltage VINJH is applied to the injector 4 as the drive voltage VINJ. Thereby, the valve opening of the injector 4 is started, and the injector 4 is quickly opened with high responsiveness. Note that, from timing t1 to timing t2 to be described later, the boosted voltage VC is lower than the high voltage VCH at the time of application due to discharge accompanying application to the injector 4.

  After the valve opening of the injector 4, the driving voltage VINJ is switched from the high voltage VINJH to the low voltage VINJL based on the battery voltage VB at timing t 2, and this low voltage VINJL is applied to the injector 4. Thereby, the opened injector 4 is held in its open state.

  At timing t2, the target boost voltage VCOBJ is set to a target value VCOBJH (for example, 45V) larger than the normal target value VCOBJL (for example, 40V), and the boost operation by the boost circuit 20 is started. As a result, as shown in FIG. 3C, the boosted voltage VC that has been reduced due to the discharge is quickly boosted by a high degree of boosting.

  Thereafter, at timing t3, the target boost voltage VCOBJ is returned to the original normal target value VCOBJL. In this case, as shown in FIG. 3D, although the boosting operation by the booster circuit 20 is continued, the boosting degree of the boosted voltage VC is lowered because the target boosted voltage VCOBJ is decreased.

  At timing t4, a boost operation stop signal for stopping the boost operation by the boost circuit 20 is turned on, whereby the execution of the boost operation by the boost circuit 20 is stopped. This timing t4 is before timing t5 at which the injector 4 is closed when the application of the drive voltage VINJ (low voltage VINJL) to the injector 4 is completed. Further, the boosting operation stop signal is turned off at timing t6 after the injector 4 is closed, and the boosting operation by the boosting circuit 20 becomes possible.

  As described above, in the boost control when realizing the first operation example, the boost operation by the boost circuit 20 is stopped at the timing t5 when the injector 4 is closed. Thus, a large current generated when the boosting operation is performed does not flow to, for example, the reference ground in the ECU 2 when the valve closing timing of the injector 4 is detected, and the ground floating can be prevented. As a result, it is possible to appropriately detect the valve closing timing of the injector 4 while ensuring appropriate valve opening by applying the boosted voltage VC to the injector 4, and to improve the detection accuracy.

  FIG. 4 shows a predetermined boosting operation by the booster circuit 20 after the drive voltage VINJ is switched from the high voltage VINJH to the low voltage VINJL until the application of the drive voltage VINJ (low voltage VINJL) to the injector 4 is completed. An operation example (hereinafter referred to as a “second operation example”) is shown in which the boosting operation is resumed after the injector 4 is closed due to the completion of application of the drive voltage VINJ. In this operation example, unlike the above-described first operation example, the target boost voltage VCOBJ is always set to a normal target value VCOBJL (for example, 40 V). Therefore, in FIG. 4, the timing of the target boost voltage VCOBJ is set. The chart shall be omitted. Further, as shown in FIGS. 4A to 4D, immediately before the drive voltage VINJ is applied to the injector 4, the drive voltage VINJ, the boost voltage VC of the boost circuit 20, the boost operation, and the boost operation stop signal are: The same as those in the first operation example.

  As shown in FIG. 4, in the present operation example, first, the high voltage VINJH as the drive voltage VINJ is applied to the injector 4 at the timing t11, and then the drive voltage VINJ is set to the low voltage at the timing t12. Switch to VINJL. Thereby, the injector 4 opened at the timing t11 is held in its open state.

  Further, the boosting operation by the booster circuit 20 is started at the timing t12, and the boosting operation stop signal is turned on at the timing t13 after the elapse of the first predetermined time TA1, whereby the boosting operation by the booster circuit 20 is stopped. Is done. The lowered boosted voltage VC is boosted by executing the boosting operation during the timing t12 to t13.

The first predetermined time TA1 is calculated by searching a predetermined map (not shown) according to the engine load based on the engine speed NE, the accelerator pedal opening AP, and the like. In this map, the first predetermined time T A 1 is set to be shorter as the rotational speed NE is higher and the engine load is higher.

  Thereafter, at timing t14, application of the drive voltage VINJ to the injector 4 is completed, and at the subsequent timing t15, the boosting operation stop signal is turned off. Thereby, as shown in FIG. 4C, the boosting operation by the boosting circuit 20 is resumed, and the boosting operation is stopped at the subsequent timing t16. The boosting operation is stopped, for example, when the boosted voltage VC reaches the high voltage VCH.

  As described above, in the step-up control when the second operation example is realized, the detection accuracy of the valve closing timing of the injector 4 is ensured while ensuring the appropriate valve opening of the injector 4 as in the case of the first operation example described above. Can be improved. In addition, by appropriately setting the first predetermined time TA1 according to the operating state of the engine 3, the boosting operation by the booster circuit 20 can be appropriately stopped before the closing timing t14 of the injector 4, Before the stop, the boost voltage VC can be increased to some extent.

  FIG. 5 shows that the boosting operation by the booster circuit 20 is executed after the drive voltage VINJ is switched from the high voltage VINJH to the low voltage VINJL until the application of the drive voltage VINJ (low voltage VINJL) to the injector 4 is completed. The step-up operation is stopped when a predetermined time has elapsed from the start of application of the drive voltage VINJ to the injector 4 and restarted when the predetermined time has elapsed since the stop (hereinafter referred to as “third”. Example of operation ") is shown. In this operation example, the target boost voltage VCOBJ is always set to the normal target value VCOBJL as in the second operation example described above, and therefore the timing chart of the target boost voltage VCOBJ is omitted in FIG. To do. Further, as shown in FIGS. 9A to 9C, immediately before the application of the drive voltage VINJ to the injector 4, the drive voltage VINJ, the boost voltage VC of the boost circuit 20, and the boost operation are the first and first The same as those in the two operation examples.

  As shown in FIG. 5, in this operation example, first, at timing t21, the high voltage VINJH is applied to the injector 4, and a count-up timer by software is started as shown in FIG. Thereafter, at timing t22, the drive voltage VINJ is switched to the low voltage VINJL. Thereby, the injector 4 opened at the timing t21 is held in its open state.

  At timing t22, the boosting operation by the boosting circuit 20 is started. Thereby, the lowered boosted voltage VC is boosted.

  Thereafter, when the second predetermined time TA2 is measured by the timer (timing t23), the boosting operation by the booster circuit 20 is stopped, and the timer is reset and restarted. The second predetermined time TA2 is set shorter than the application time TB of the drive voltage VINJ to the injector 4, that is, the fuel injection time by opening the injector 4.

  Thereafter, at timing t24, application of the drive voltage VINJ to the injector 4 is completed. When a predetermined first stop time TS1 (> TB-TA2) is measured by the restarted timer (timing t25), the boosting operation by the boosting circuit 20 is resumed, and at the subsequent timing t26, the boosting operation is resumed. Stop. Note that the boosting operation is stopped, for example, when the boosted voltage VC reaches the high voltage VCH, as in the second operation example.

  As described above, in the step-up control when the third operation example is realized, the valve closing timing of the injector 4 is secured while ensuring the appropriate valve opening of the injector 4 as in the case of the first and second operation examples described above. Detection accuracy can be improved. Further, by appropriately setting the second predetermined time TA2 and the first stop time TS1 according to the operating state of the engine 3, the boosting operation by the booster circuit 20 is appropriately performed before the closing timing t24 of the injector 4. The boosted voltage VC can be increased to some extent before the stop, and the boosting operation can be restarted appropriately after the injector 4 is closed.

  In the third operation example, the boosting operation by the booster circuit 20 is stopped with reference to the timing t21 at which the drive voltage VINJ starts to be applied to the injector 4, but the application of the drive voltage VINJ to the injector 4 is terminated. The boosting operation may be stopped based on the timing t24.

  Specifically, the boosting operation is stopped at a timing t23 that is a third predetermined time TA3 before the timing t24. In this case, the timing t23 is the timing when the time (= TB−TA3) obtained by subtracting the third predetermined time TA3 from the fuel injection time TB of the injector 4 has elapsed from the timing t21, that is, measured by the timer. . Further, when a predetermined second stop time TS2 has elapsed from timing t24 (timing t25), the boosting operation by the boosting circuit 20 is resumed, and at the subsequent timing t26, the boosting operation is stopped. The second stop time TS2 is measured by a timer that is reset at timing t24.

  As described above, when the boosting operation by the booster circuit 20 is stopped with reference to the timing t24 when the application of the drive voltage VINJ to the injector 4 is completed, the same effect as that obtained when the timing t21 is used as a reference can be obtained. .

  In addition, this invention can be implemented in various aspects, without being limited to the said embodiment described. In any of the first to third operation examples, in order to open the injector 4, the high voltage VINJH is applied and then switched to the low voltage VINJL. However, the present invention is not limited to this, For example, the switching of the drive voltage VINJ can be omitted and the high voltage VINJH can be constantly applied to the injector 4. In addition, for the detection of the valve closing timing of the injector 4, other appropriate detection methods other than those described above may be employed.

  In addition, the injector 4 of the embodiment is for a direct injection gasoline engine for a vehicle, but is not limited thereto, a port injection engine, a diesel engine, and an outboard motor in which a crankshaft is arranged vertically. It may be used for various industrial internal combustion engines such as marine vessel propulsion engines. In addition, the detailed configuration can be changed as appropriate within the scope of the gist of the present invention.

2 ECU (application means, valve closing timing detection means, control means,
Target boost voltage setting means, operating state detection means, boost operation time setting means)
3 Internal combustion engine 4 Fuel injection valve 10 Drive circuit 11 Battery (power source)
20 Booster circuit 30 Injector drive circuit 40 CPU
61 Crank angle sensor (operating state detection means)
62 Accelerator opening sensor (operating state detection means)
VB Battery voltage VC Capacitor voltage VINJ Injector drive voltage IAC Injector drive current NE Engine speed VCOBJ Target boost voltage VCOBJL Normal target value VCOBJH High target value VINJH Injector drive voltage high voltage VINJL Injector drive voltage low voltage TA1 First predetermined time TA2 Second predetermined time TA3 Third predetermined time TB Application time to the injector TS1 First stop time TS2 Second stop time

Claims (8)

A boost control device for a fuel injection valve that controls boosting of a voltage applied to the fuel injection valve to drive an electromagnetic fuel injection valve,
A booster circuit for boosting the voltage of the power supply;
Applying means for applying a boosted voltage boosted by the booster circuit to the fuel injector in order to open the fuel injector;
A valve closing timing detecting means for detecting a valve closing timing of the fuel injection valve based on a current or a voltage supplied to the fuel injection valve;
Control means for performing a boosting operation by the boosting circuit at least during application of the drive voltage to the fuel injection valve, and controlling to stop the boosting operation by the boosting circuit when detecting the valve closing timing; ,
A boost control device for a fuel injection valve, comprising: Target boost voltage setting means for setting a target boost voltage as a target value of the boost voltage controlled by the control means, further comprising:
The application means applies the boosted voltage to the fuel injection valve to open the fuel injection valve, and then sets the applied voltage of the fuel injection valve to keep the fuel injection valve open. It is configured to switch to the power supply voltage,
When the applied voltage of the fuel injection valve is switched from the boosted voltage to the power supply voltage, the control means performs a boosting operation by the booster circuit, and the target boosted voltage setting means further increases the target boosted voltage. 2. The boost control device for a fuel injection valve according to claim 1, wherein the boost control device is set to a large value. The application means applies the boosted voltage to the fuel injection valve to open the fuel injection valve, and then sets the applied voltage of the fuel injection valve to keep the fuel injection valve open. It is configured to switch to the power supply voltage,
The control means starts the boosting operation by the booster circuit when the applied voltage of the fuel injection valve is switched from the boosted voltage to the power supply voltage, and then when the first predetermined time has elapsed, 2. The boost control device for a fuel injection valve according to claim 1, wherein the boost operation is stopped. An operating state detecting means for detecting an operating state of the internal combustion engine;
Boosting operation time setting means for setting the first predetermined time according to the detected operating state of the internal combustion engine;
The boost control device for a fuel injection valve according to claim 3, further comprising: The application means applies the boosted voltage to the fuel injection valve to open the fuel injection valve, and then sets the applied voltage of the fuel injection valve to keep the fuel injection valve open. It is configured to switch to the power supply voltage,
The control means starts the boosting operation by the booster circuit when the applied voltage of the fuel injection valve is switched from the boosted voltage to the power supply voltage, and starts application of the boosted voltage to the fuel injector. 2. The boost control device for a fuel injection valve according to claim 1, wherein the boost operation is stopped when a second predetermined time elapses from the hour.   6. The boost control device for a fuel injection valve according to claim 5, wherein the control means restarts the boost operation when a predetermined first stop time has elapsed since the boost operation was stopped. . The application means applies the boosted voltage to the fuel injection valve to open the fuel injection valve, and then sets the applied voltage of the fuel injection valve to keep the fuel injection valve open. It is configured to switch to the power supply voltage,
The control means starts the boosting operation by the booster circuit when the applied voltage of the fuel injection valve is switched from the boosted voltage to the power supply voltage, and ends the application of the power supply voltage to the fuel injector. 2. The boost control device for a fuel injection valve according to claim 1, wherein the boost operation is stopped a third predetermined time before the time.   8. The fuel according to claim 7, wherein the control means restarts the boosting operation when a predetermined second stop time has elapsed from the end of application of the power supply voltage to the fuel injection valve. Boost control device for injection valve.

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