JP2018178729A - Injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection control device enabling fuel to be appropriately injected in an internal combustion engine.SOLUTION: The injection control device includes control means which changes a charging condition to a charging condition that a timing for starting the charge of the capacitor is advanced. Thus, earlier start of the charge is actualized to avoid insufficient charge when, for example, a capacitor charging speed lowers. In addition, electrical charges necessary to perform fuel injection can be accumulated in the capacitor, so that fuel can be appropriately injected.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an injection control device that controls the drive of an injection valve that injects fuel into an internal combustion engine.

  In the injection control device, the opening period and the opening / closing timing of the injector (injection valve) for injecting the fuel into the internal combustion engine are controlled by controlling the energizing current. Such an injection control device includes a booster circuit that boosts the battery voltage and charges the capacitor. At the start of the set driving period, the boosted voltage charged in the capacitor is applied to the injector to set the peak current. By flowing, the injector is quickly opened.

  By the way, in the case where fuel injection is performed multiple times in one combustion cycle as so-called multistage injection, there may occur a situation where sufficient electric charge necessary for performing the multistage injection can not be stored in the capacitor. Therefore, fuel injection other than the main fuel injection for operating the internal combustion engine among a plurality of fuel injections (hereinafter referred to as sub A technique is considered to limit the implementation of the injection) (see, for example, Patent Document 1).

JP, 2007-13547, A

  However, in the prior art described above, if it is not possible to store sufficient charge in the capacitor, the implementation of the secondary injection is limited, resulting in an increase in vibration or noise during operation of the internal combustion engine, and in combustion efficiency. There is a risk of causing a decrease.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an injection control device capable of appropriately injecting fuel in an internal combustion engine.

  In the injection control device according to claim 1, the control means (13, 14) changes the charging start timing of the capacitor to a charging condition for advancing the timing when charging of the capacitor (C1) takes time. Therefore, for example, when the charging speed of the capacitor is lowered, the start of the charging can be advanced to prevent the shortage of the charging. In addition, it is possible to store the electric charge necessary for the implementation of the fuel injection in the condenser, and it is possible to appropriately perform the injection of the fuel without restricting the implementation of the sub-injection in the multistage injection as in the prior art, for example. .

The block diagram of the injection control apparatus and injector which show 1st Embodiment Time chart showing the signal of injection control device Time chart for explaining the charging voltage and charging time detection process of the capacitor Flow chart of charge time detection process Time chart for explaining the relationship between the current supplied to the injector and the charging voltage of the capacitor Flow chart of charge voltage inclination detection processing of capacitor according to the second embodiment Time chart for explaining charge voltage inclination detection processing Flow chart of charge voltage detection process according to the third embodiment

First Embodiment
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. The injection control device 10 shown in FIG. 1 is one of a plurality of ECUs mounted on a vehicle, and injects fuel into each cylinder of a multi-cylinder engine as an internal combustion engine mounted on the vehicle (this Hereinafter, when the injector for each cylinder is represented, the drive of # 1 to #n is controlled. Note that “n” corresponds to the number of cylinders of the internal combustion engine, and in FIG. 1, one injector # 1 of the n cylinders is exemplified.

  The injection control device 10 controls the current supplied to the injector 11 to open and close the injector 11. In this case, at the start of the drive period TS shown in FIG. 2, the injection control device 10 performs peak current control for supplying a peak current described later to the injector 11 to rapidly open the injector 11. Thereafter, the injection control device 10 performs constant current control until the drive period TS ends, and holds the open state of the injector 11.

  When the coil 11s in the injector is energized, the injector 11 displaces from the valve closing position to the valve opening position against the biasing force of the return spring to perform fuel injection. When the coil 11s is deenergized, the valve body is returned to the valve closing position by the biasing force of the return spring to stop the fuel injection.

  As shown in FIG. 1, the injection control device 10 includes a microcomputer 13, a drive control IC 14, a booster circuit unit 15, and an injector circuit unit 16. These circuit units 15 and 16 include N channel type MOS transistors T1 to T1. T4, charge capacitor C1, diodes D1 to D4 and the like are included. The microcomputer 13 and the drive control IC 14 according to this embodiment include a storage unit (not shown) and constitute control means or a control unit that controls the circuit units 15 and 16.

  The microcomputer 13 controls the overall operation of the device. The microcomputer 13 includes a charge voltage detection unit 13a and a charge time calculation unit 13b as shown in FIG. 1, and functions as voltage detection means, time detection means, and inclination detection means described later. At the time of injector drive request, the microcomputer 13 receives drive request signals (injection signals S # 1 to S # n for each cylinder) for commanding valve opening and closing for each of the injectors 11 via the signal line SL. It transmits to drive control IC14.

  The drive control IC 14 performs control to supply a current to the coil 11 s of the injector 11 having a drive request. The drive control IC 14 includes a threshold voltage control unit 14 a and functions as a threshold voltage changing unit that changes a threshold voltage described later.

  A battery voltage VB output from a battery power supply, which is a direct current power supply, is supplied to a power supply terminal Pd of the injection control device 10. A coil 11 s is connected between the output terminal P 1 a and the output terminal P 1 b of the injection control device 10. Here, in FIG. 1, the upper terminal P1a is a common terminal for the coil 11s of the injector # 1 and the coils 11s of the other injectors # 2 to #n, and the lower terminal P1b is for each injector # 1 to # 1. The #n coils 11 s are respectively connected to different terminals. In the following, for convenience of explanation, the configuration related to the driving of one injector # 1 will be mainly described.

  First, in order to cause the injector 11 to open at high speed immediately after the start of driving, the booster circuit unit 15 generates a boosted voltage for supplying a discharge current as a so-called peak current to the injector 11. Between the power supply terminal Pd and the ground, a boost inductor L1, a transistor T1 also called charge MOS, and a current detection resistor R1 are connected in series.

  The drain of the transistor T1 is connected to the anode of a diode D1 for backflow prevention. The cathode of the diode D1 is connected to the node Np. The drive control IC 14 controls driving of the transistor T1 based on the voltage of the node Np of the booster circuit unit 15 so that the boosted voltage matches the target voltage. By such control, the energy stored in the inductor L1 is transferred to the charge capacitor C1 through the diode D1, and the boosting operation is performed.

  The charge capacitor C1 is, for example, an aluminum electrolytic capacitor (it may be another type of capacitor) which charges the boosted voltage. One terminal of the charge capacitor C1 is connected to the node Np of the booster circuit unit 15, and the other terminal is connected to the ground. The drive control IC 14 controls the booster circuit unit 15 (DC-DC converter) so as to charge the charge capacitor C1 at a voltage higher than the battery voltage VB by the above-described boosting operation.

  In the injector circuit portion 16, the transistor T2, also referred to as a cylinder MOS, is provided between the terminal P1b on the downstream side of the coil 11s and one terminal of the resistor R2. The resistor R2 is for current detection, and the other terminal is connected to the ground. The cylinder MOS is provided to correspond to each coil 11s for each of the injectors # 1 to #n, and corresponds to a switching element for selecting the injectors # 1 to #n to be driven. The anode of a diode D2 for energy recovery is connected to the terminal P1b on the downstream side of the coil 11s, and the cathode is connected to the node Np of the booster circuit 15, that is, the positive electrode side of the charge capacitor C1.

  In the injector circuit section 16, the transistor T3 also referred to as a discharge MOS is provided between the node Np of the booster circuit section 15 and the terminal P1a on the upstream side of the coil 11s. Furthermore, a transistor T4, also referred to as a constant current MOS, is provided between the power supply terminal Pd and the anode of the diode D3 for backflow prevention. The terminal P1a is connected to the cathode of the diode D3. Further, the terminal P1a is connected to the cathode of a current return diode D4 whose anode is connected to the ground.

  The microcomputer 13 and the drive control IC 14 can adopt any configuration that functions as control means by software stored in the storage unit, hardware, or a combination thereof. For example, the control means may be configured by digital circuits including multiple logic circuits or hardware including analog circuits.

  The microcomputer 13 detects the injection signal for each cylinder corresponding to the injectors # 1 to #n (the signal S1 # to S at the H level) based on detection information detected by various sensors (not shown) such as the engine rotational speed and the accelerator opening degree. #N) are generated and output to the drive control IC 14. The drive control IC 14 controls the on / off of each of the charge MOS, the discharge MOS, the constant current MOS, and the cylinder MOS based on the injection signals S # 1 to S # n at the time of fuel injection control, to thereby drive the coil 11s. Are energized to open the injectors # 1 to #n.

  Specifically, for example, as shown in FIG. 2, the drive control IC 14 corresponds to a period TS during which the injection signal S # n of the injector #n of the n-th cylinder for which drive is requested from the microcomputer 13 is H level. The transistor T2 is turned on, and at the start of the drive period TS, the transistor T3 is turned on.

Then, the drive control IC 14 detects the injector current which is the load current flowing through the coil 11s based on the voltage generated in the resistor R2, and determines that the load current becomes the target maximum value I _PEAK of the discharge current, thereby turning off the transistor T3. Make it Thus, when electric power is applied to the beginning of the coil 11s, the energy stored in the charging capacitor C1, the load current flowing through the coil 11s rises suddenly, the discharge current up to the peak current I _PEAK, promptly injector #n Open the valve.

In addition, the drive control IC 14 performs constant current control to turn on and off the transistor T4 so that the load current detected based on the voltage generated in the resistor R2 after turning off the transistor T3 is a constant current smaller than _IPEAK. . That is, when the drive control IC 14 determines that the load current is less than or equal to the lower threshold _{Ic_L} in the drive period TS of FIG. 2, the transistor T4 is turned on, and when it is determined that the load current is greater than or equal to the upper threshold _{Ic_H} , the transistor T4. Execute control to turn off. In this case, the lower threshold value _{Ic _L,} an upper threshold value _{Ic _H,} the target maximum value _{I PEAK,} represented by relation as in FIG 2, _{"I PEAK> Ic _H>} Ic _{_L".} When the load current decreases from the target maximum value I _PEAK and becomes equal to or less than the lower threshold I c _{_} L by the constant current control, the on / off of the transistor T 4 is repeated thereafter to average the load current values I c _{_ H} and I c. It is maintained at a constant current Ic between _{_L} .

In the constant current control described above, when the transistor T4 is on, a current flows from the power supply line side terminal Pd side to the coil 11s through the transistor T4 and the diode D3, and when the transistor T4 is off, the ground side is via the diode D4. The current flows back. During the drive period TS of FIG. 2, the transistor T4 is turned on during the initial period after the injection signal S # n becomes H level, that is, until the load current reaches the upper threshold value _{Ic_H} . Is due to the above constant current control.

  Thereafter, when the injection signal S # n from the microcomputer 13 becomes L level, the drive control IC 14 turns off the transistor T2 and terminates the constant current control by turning on and off of the transistor T4, and holds the off state. . As a result, the energization to the coil 11s is stopped, the injector #n is closed, and the fuel injection by the injector #n is completed. When the injection signal S # n becomes L level and the transistors T2 and T4 are turned off, the flyback energy generated in the coil 11s, that is, the remaining energy is recovered by the charge capacitor C1 through the diode D2. .

  Regarding the constant current control described above, in addition to the value of the constant current Ic, for example, the value of the constant current smaller than the value Ic is stored in advance in the storage unit, and constant by the drive control IC 14 in the first half of the constant current control The control for supplying the current Ic may be performed, and the control for supplying a constant current smaller than the Ic may be performed in the second half.

Further, in this embodiment, a period from when the transistor T3 is turned on to when the load current reaches _IPEAK is a capacitor discharge period (see FIG. 5), and a period other than the capacitor discharge period is a capacitor chargeable period. . That is, the drive control IC 14 is configured to be able to charge the charge capacitor C1 by the step-up operation even when performing the constant current control.

Then, the drive control IC 14 controls the booster circuit unit 15 so that the charging voltage Vc of the charge capacitor C1 becomes the target voltage by the boosting operation in the capacitor chargeable period. Specifically, the drive control IC 14 detects the charging voltage Vc of the charge capacitor C1, that is, the voltage of the node Np indicating the voltage on the positive electrode side of the capacitor C1. When the drive control IC 14 determines that the detected charge voltage Vc has decreased to the first threshold voltage Vc ₋₁ (see FIG. 5) set by the threshold voltage control unit 14a, the transistor T1 is set in the capacitor chargeable period. By repeatedly turning on and off, for example, the charge capacitor C1 is charged so as to be a full charge voltage shown as "the charge target voltage" in FIG.

  In this case, as shown in FIG. 3, when the transistor T1 is turned on, a charging current flows to the resistor R1 through the inductor L1 and the transistor T1, and when the transistor T1 is turned off, the energy stored in the inductor L1, which is a charge coil, , Via the diode D1 to the charge capacitor C1 to raise the charge voltage Vc. Therefore, the drive control IC 14 turns off the transistor T1 for a predetermined time when the current detected by the voltage generated in the resistor R1 after turning on the transistor T1, that is, the current flowing in the inductor L1 reaches a predetermined value. Is repeated to charge the charge capacitor C1 to the target voltage.

  Further, in the present embodiment, as shown in FIG. 5, it is possible to carry out multistage injection (three-stage injection is illustrated in the same figure) in which fuel injection is performed a plurality of times in one combustion cycle. The number of fuel injection stages to be implemented is determined based on the detected information such as the engine rotational speed detected in the above. When the multi-stage injection is performed, the microcomputer 13 outputs, to the drive control IC 14, the determined stage number "m", that is, the stage number information m indicating the injection stage number, before outputting the first injection signal S # n that is the first stage. Do.

By the way, the first threshold voltage Vc- ₁ described above is stored in advance in the storage unit as a charging condition related to the threshold for charging the charge necessary for the drive control of the injector 11. However, for example, when the charge rate is lowered due to the deterioration of the performance of the charge capacitor C1, etc., it may be assumed that sufficient charge can not be stored in the capacitor C1. In particular, when performing multi-stage injection, the injection interval becomes short, and the time interval to execute peak current control also becomes short.

Therefore, when the microcomputer 13 according to the present embodiment determines that it takes time to charge the charge capacitor C1 under the charge condition, the microcomputer 13 changes the charge condition to a charge condition for advancing the timing of starting charging by the drive control IC 14. It has become. For example, in the storage unit, in addition to the first threshold voltage Vc- ₁ , a second threshold voltage Vc- ₂ previously set as a threshold higher than the first threshold voltage for changing the charging condition is referred to (see FIG. 5). Is stored.

Then, when changing the charge condition, the microcomputer 13 instructs the threshold voltage control unit 14a of the drive control IC 14 to change the initial first threshold voltage Vc- ₁ to the second threshold voltage Vc- ₂ , The boosting operation in the boosting circuit unit 15 is under the charge condition to be performed at an early timing. A specific configuration relating to the change of the charging condition will be described with reference to FIG. The flowchart of FIG. 4 shows the flow of the charging time detection process executed by the microcomputer 13. In the following, it is assumed that a reference value or a predetermined value such as a reference voltage or the like is stored in advance in the storage unit.

  First, when the charge time detection process is started in the step-up operation of the step-up circuit unit 15, the microcomputer 13 detects the charge voltage Vc of the charge capacitor C1 by the charge voltage detection unit 13a of itself. Further, the microcomputer 13 measures the charging time until the detected value of the charging voltage Vc rises from the first voltage to the second voltage by the charging time calculation unit 13b of the self 13 (step S11).

Specifically, the microcomputer 13 sets a second reference voltage _{Vth _H} as a first reference voltage _{Vth _L} and the second voltage as the first voltage shown in FIG. 3, the charging of the charge capacitor C1, the charge voltage Vc is determined charging time Tc from the first reference voltage _{Vth _L} up to the second reference voltage _{Vth _H.} The reference voltages _{Vth_L} and _{Vth_H} are, for example, two voltage values that define a range larger than the first threshold voltage Vc ₋₁ and smaller than the full charge voltage, but the difference between those voltage values measures the charging time Tc. The value is set to an appropriate value that defines a predetermined voltage range that can ensure accuracy.

The microcomputer 13 in step S12 in FIG. 4 compares the charging time Tc obtained, the reference voltage _Vth _L, the normal charging time _{Tc _MAX} that is set in advance corresponding to _{Vth _H.} If the microcomputer 13 determines that the charging time Tc _concerned is equal to or shorter than the normal charging time _{Tc_MAX} (Tc ≦ _{Tc_MAX} ) (YES in step S12), the charging time Tc of the charge capacitor C1 falls within the normal time range. This process ends (END) as if there is any.

On the other hand, it is assumed that the microcomputer 13 determines that the charging time Tc exceeds the normal charging time _{Tc_MAX} (NO in step S12). As described above, if the charging time Tc of the charge capacitor C1 is not within the range of the normal time, it can be said that the charging speed in the booster circuit unit 15 is reduced.

In this case, the microcomputer 13 transmits, to the threshold voltage control unit 14a of the drive control IC 14, a signal instructing change to the second threshold voltage Vc- ₂ for the threshold voltage defining the charge start voltage (step S13). ). As a result, the drive control IC 14 performs the setting to change the initial first threshold voltage Vc- ₁ to the second threshold voltage Vc- ₂ in the threshold voltage control unit 14a, whereby the timing for starting charging of the charge capacitor C1 is started. Change the charging conditions to speed up the

The operation of the above configuration will be described with reference to FIG. FIG. 5 exemplifies the case where three-stage injection is performed in one injector #n.
During the capacitor discharge period shown in FIG. 5, the charge capacitor C1 is discharged, and the charge voltage Vc decreases with the decrease in the charge of the capacitor C1. Therefore, as the fuel injection stage number m increases, discharge of the charge capacitor C1 is repeated by the number m of stages, so that the decrease in the charge voltage Vc becomes larger.

Thus, when the drive control IC 14 determines that the charge voltage Vc has dropped to the first threshold voltage Vc- ₁ set in advance, the voltage control circuit 15 starts the boosting operation immediately after the lapse of the capacitor discharge period. Let At this time, when the charge voltage Vc rises at a normal charge rate (see the thick line on the lower right side of FIG. 5), as indicated by a thick line as “at normal charge speed” in FIG. In execution, since the charging time Tc is processed as being within the range of normal time (YES in the step S12), the setting of the first threshold voltage Vc- ₁ is maintained.

On the other hand, when the charge voltage Vc does not increase at the normal charge rate (refer to the two-dot chain line on the lower right side of FIG. 5), as represented by “when the charge rate decreases” in FIG. Since the charging time Tc is processed as exceeding the normal time range (NO in step S12), the setting change from the first threshold voltage Vc- ₁ to the second threshold voltage Vc- ₂ is performed ( Said step S13). Thereby, as shown as “after threshold value change” in FIG. 5, when the voltage drops to the second threshold voltage Vc− ₂ during multistage injection, the period other than the capacitor discharge period is regarded as the capacitor chargeable period, and the boosting operation It is intermittently performed so as to remove the capacitor discharge period, and after the multistage injection, it is continuously performed until the charge voltage Vc reaches the charge target voltage.

Further, as apparent from the figure, the second threshold voltage Vc- ₂ is higher than the first threshold voltage Vc- ₁ (Vc- ₂ > Vc- ₁ ), and after the threshold change, the first threshold voltage Vc- ₂ is higher than the first threshold voltage Vc _- 1. The charging is started earlier than in the normal time in which the threshold voltage Vc- ₁ is set. Therefore, the charging stop period, that is, the period during which the boosting operation is not performed in the capacitor chargeable period can be shortened. As a result, when the chargeable period of the charge capacitor C1 is short, for example, when the multi-cylinder engine rotates at high speed and multistage injection of fuel is performed, it is possible to secure the high charge voltage Vc of the charge capacitor C1.

  As described above, when the microcomputer 13 according to the present embodiment determines that it takes time to charge the charge capacitor C1 under the charge condition set in advance by the threshold voltage control unit 14a, the charge condition is determined as the charge capacitor. Change the charge start timing of C1 to a charge condition to accelerate.

  According to this, for example, when the charge speed of the charge capacitor C1 is lowered, the start of the charge can be advanced to prevent the occurrence of the insufficient charge. In addition, the charge necessary for performing fuel injection can be stored in charge capacitor C1, and fuel injection can be appropriately performed without restricting execution of sub-injection in multistage injection as in the prior art, for example. It becomes.

The microcomputer 13 according to the present embodiment operates as a detection unit 13a as a time detection unit that detects the charging time Tc until the charging voltage Vc of the charge capacitor C1 rises from the first reference voltage _{Vth_L} to the second reference voltage _{Vth_H.} The unit 13b is provided, and when it is determined that the charging time Tc detected by the charging time calculation unit 13b exceeds the normal charging time _{Tc_MAX} , the timing for starting charging of the charge capacitor C1 is changed to a charging condition for _advancing the timing.

According to this, it can be appropriately determined based on the detected charging time Tc whether it takes time to charge the charge capacitor C1.
The charging condition of this embodiment, with the proviso that the charge voltage Vc to the first threshold voltage Vc _-1 which is previously set as a threshold value for starting the charging of the charge capacitor C1 is lowered, the first threshold voltage Vc _- By changing to the second threshold voltage Vc- ₂ higher than _1, the timing for starting charging of the charge capacitor C1 is advanced.

  According to this, in the drive control IC 14, the charge start timing of the charge capacitor C <b> 1 can be advanced with a simple configuration in which the setting of the threshold of the threshold voltage control unit 14 a is changed.

<Other Embodiments>
6 to 8 show the second and third embodiments of the present invention, and processing different from the charging time detection processing is executed. Hereinafter, substantially different points from the above-described embodiment will be described.

  The flowchart of FIG. 6 shows the flow of the charging voltage slope detection process of the second embodiment executed by the microcomputer 13. First, when the microcomputer 13 starts charge voltage inclination detection processing during the step-up operation of the step-up circuit unit 15, the time of the charge voltage Vc of the charge capacitor C1 is detected by the charge voltage detection unit 13a and the charge time calculation unit 13b. The inclination of the charging voltage Vc in the change is detected (step S21).

  Specifically, as shown in FIG. 7, the microcomputer 13 detects the charge voltage Vc of the charge capacitor C1 twice by the charge voltage detection unit 13a with a time difference ΔTc, and the charge time calculation unit 13b detects the detected value. The value of the slope of the charging voltage Vc is determined by dividing the increase ΔVc by the time ΔTc (ΔVc / ΔTc).

  Then, in step S22 of FIG. 6, the microcomputer 13 compares the value of the calculated gradient of the charging voltage Vc with a predetermined gradient value set in advance. Here, the predetermined slope value is a value corresponding to the determination reference of the lower limit of the normal charging speed of the charge capacitor C1. Therefore, when the microcomputer 13 determines that the value of the slope of the charge voltage Vc is equal to or more than the predetermined slope value ((ΔVc / ΔTc) 所 定 predetermined slope value) (YES in step S22), the charge voltage of the charge capacitor C1 is This process is terminated (END) assuming that Vc is rising at a normal charging rate.

On the other hand, it is assumed that the microcomputer 13 determines that the value of the slope of the charging voltage Vc does not reach the predetermined slope value (NO in step S22). In such a case, it can be said that the charging speed of the charge capacitor C1 in the booster circuit unit 15 is reduced. Therefore, the microcomputer 13 transmits a signal instructing to change the first threshold voltage Vc- ₁ to the second threshold voltage Vc- ₂ to the threshold voltage control unit 14a of the drive control IC 14 (step S23). As a result, the drive control IC 14 performs setting for changing to the second threshold voltage Vc- ₂ in the threshold voltage control unit 14a.

  As described above, the microcomputer 13 according to the second embodiment detects the inclination of the charge voltage Vc in the time change of the charge voltage Vc when the charge capacitor C1 is charged. 13b, and when it is determined that the slope of the charging voltage Vc detected by the slope detection means does not reach a predetermined slope value, the timing for starting charging of the charge capacitor C1 is changed to a charging condition for advancing the timing.

  According to this, it is appropriately determined whether it takes time to charge the charge capacitor C1 based on the slope of the charge voltage Vc without waiting for the required time for the charge voltage Vc to rise to a certain reference voltage. it can.

The flowchart of FIG. 8 shows the flow of the charging voltage detection process of the third embodiment.
The microcomputer 13 obtains the charging time Tc from the first reference voltage _{Vth_L} to the second reference voltage _{Vth_H} in steps S31 and S32 of FIG. 8 similarly to the steps S11 and S12, and _calculates the charging time Tc and the charging time Tc. The normal charging time _{Tc_MAX} is compared. In steps S31 and S32, in order to determine the decrease in the charging speed in the booster circuit 15, the value of the slope of the charge voltage Vc is determined as in steps S21 and S22, and the value of the slope of the charge voltage Vc And the predetermined slope value may be compared.

Here, it is assumed that the microcomputer 13 determines that the charging time Tc exceeds the normal charging time _{Tc_MAX} (NO in step S32). In this case, the microcomputer 13 detects the charging voltage Vc of the charge capacitor C1 by the charging voltage detection unit 13a before the start of the m-stage injection in any of the injectors # 1 to #n (step S33). The detection of the charge voltage Vc in this case is performed, for example, immediately before the fuel injection, and the detection timing (detection period) immediately before the fuel injection is indicated by an arrow A in FIG. The period shown as the "charge delay detection period" in FIG. 5 is a period in which the boosting operation is performed, and is a period in which the detection process of steps S11, S21, and S31 can be performed.

Next, the microcomputer 13 compares the detected charging voltage Vc with a predetermined voltage value (step S34). Here, the predetermined voltage value is, for example, a value representing a charging voltage necessary for performing m-stage injection, and is a voltage defined in advance according to the actual number of injection stages m and the time between each injection in the multistage injection It is determined by checking the value data table. That is, if the number m of multistage injections is relatively large, the charge voltage Vc falls below the first threshold voltage Vc- ₁ during multistage injection unless relatively large charges are stored in the charge capacitor C1. Is assumed. Therefore, the microcomputer 13 does not, for example, determine that the charging voltage Vc detected when performing the three-stage injection in FIG. 5 is less than a predetermined voltage value (for example, the charging target voltage value) necessary for performing the three-stage injection. If it is determined (NO in step S34), a signal instructing change from the first threshold voltage Vc- ₁ to the second threshold voltage Vc- ₂ is transmitted to the threshold voltage control unit 14a of the drive control IC 14 ( Step S35).

  On the other hand, when the microcomputer 13 determines that the charge voltage Vc detected at the time of implementation of the three-stage injection of FIG. 5, for example, has reached the charge target voltage value (YES in step S34), the three-stage injection This process is terminated (END), assuming that the charge necessary for the implementation of the above is stored in the charge capacitor C1.

  As described above, the microcomputer 13 of the third embodiment includes the charge voltage detection unit 13a as a voltage detection unit that detects the charge voltage Vc of the charge capacitor C1 at the time of fuel injection, and the charge voltage detection unit 13a When it is determined that the charging voltage Vc detected in the above does not reach the predetermined voltage value, the timing for starting charging of the charge capacitor C1 is advanced at the time of fuel injection.

  According to this, by changing the charge condition based on the charge voltage Vc at the time of fuel injection, it is possible to prevent the timing for starting the charge capacitor C1 from being delayed. Therefore, according to the actual fuel injection, it is possible not to miss the opportunity to advance the timing of charge start and to change the charge condition as long as necessary. Thereby, the determination accuracy concerning the change of charge condition can be raised, charge can be started at an appropriate timing, and the injection of the fuel in an internal combustion engine can be performed suitably generally.

Further, according to the above configuration, for example, before performing the multistage injection, if the charge voltage Vc does not reach the predetermined voltage value, a change command to the second threshold voltage Vc- ₂ is issued prior to the injection, and the multistage injection is performed. Charging can be performed using an interval between (a period between a plurality of capacitor discharge periods in FIG. 5).

  The present invention is not limited to the embodiments described above and shown in the drawings, and the embodiments and modifications described above may be combined as appropriate, or some of the configurations may be omitted. It is what you get.

For example, in the process of FIG. 8, the steps S31 and S32 are omitted, and it is determined whether it takes time to charge the charge capacitor C1 according to the charge voltage Vc detected prior to the start of fuel injection and a predetermined value corresponding to the fuel injection. It judges by comparison of the voltage value of. As described above, even in the configuration in which only the steps S33 to S35 are performed, that is, even when the charging speed of the charge capacitor C1 is not directly detected, the charging voltage Vc before the start of fuel injection is a predetermined voltage value. If the above condition is not satisfied, the change to the second threshold voltage Vc- ₂ is performed. Therefore, similar to the above embodiment, the effect of being able to start charging at an appropriate timing can be obtained.

Further, the above-described transistors T1 to T4 are not limited to N-channel type MOS transistors, and other types of switching elements such as bipolar transistors may be used.
Although the present disclosure has been described based on the examples, it is understood that the present disclosure is not limited to the examples and structures. The present disclosure also includes various modifications and variations within the equivalent range. In addition, various combinations and forms, and further, other combinations and forms including only one element, or more or less than these elements are also within the scope and the scope of the present disclosure.

  In the drawing, 10: injection control device, 11: injector (injection valve), 13: microcomputer (control means), 13a: charge voltage detection unit (time detection means, inclination detection means, voltage detection means), 13b: charge time calculation Parts (time detection means, inclination detection means), 14 ... drive control IC (control means), 15 ... boost circuit section, C1 ... capacitor.

Claims (5)

An injection control device (10) for driving and controlling an injection valve (11) for injecting a fuel into an internal combustion engine,
A booster circuit unit (15) that generates a voltage boosted from a battery power supply;
A capacitor (C1) for charging the voltage boosted by the booster circuit section;
In which the voltage charged by the capacitor is applied to the injection valve, and a peak current is supplied to the injection valve to open the valve;
Control means (13, 14) for controlling the step-up circuit unit to charge the capacitor under charge conditions set in advance for charging the charge necessary for drive control of the injection valve;
The injection control device, wherein the control means changes the charging condition to a charging condition for advancing the timing to start charging the capacitor when it determines that it takes time to charge the capacitor under the charging condition. It comprises time detection means (13a, 13b) for detecting the charging time until the charging voltage rises from the first voltage to the second voltage by charging the capacitor,
The injection control device according to claim 1, wherein the control means changes the charging start timing of the capacitor to a charging condition for advancing the charging start timing when the charging time detected by the time detecting means exceeds the predetermined time. Slope detection means (13a, 13b) for detecting the slope of the charging voltage in the time change of the charging voltage when charging the capacitor;
The controller according to claim 1, wherein, when it is determined that the slope of the charging voltage detected by the slope detection means does not reach a predetermined slope value, the control means changes the charging condition to accelerate charging start timing of the capacitor. Injection control device. The fuel cell system further comprises a voltage detection means (13a) for detecting a charging voltage of the capacitor when injecting the fuel.
4. The control method according to any one of claims 1 to 3, wherein, when it is determined that the charging voltage detected by the voltage detecting means does not reach a predetermined voltage value, the timing of charging start of the capacitor is advanced when injecting the fuel. The injection control device according to any one of the preceding claims.   The charging condition may be changed to a second threshold voltage higher than the first threshold voltage on condition that the charging voltage is lowered to a first threshold voltage preset as a threshold for starting charging the capacitor. The injection control device according to any one of claims 1 to 4, wherein the timing of charging start of the capacitor is advanced by the.

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