Solenoid valve drive device

Abstract

This solenoid valve drive device controls an energization period of a solenoid coil provided in a fuel injection valve, and injects fuel into the fuel injection valve multiple times during a single combustion cycle of an internal combustion engine. The solenoid valve drive device comprises: a succeeding energization period correction unit that corrects a succeeding energization period, which is an energization period for the next fuel injection during a single combustion cycle, by means of repeated calculation based on an energization suspension period from the completion time of a preceding energization period, which is an energization period for the previous fuel injection during the single combustion cycle, to the start time of the succeeding energization period; and an energization control unit that energizes the solenoid coil on the basis of a corrected succeeding energization period that is the succeeding energization period corrected by the succeeding energization period correction unit.

Description

Solenoid valve drive unit

[0001] The present invention relates to an electromagnetic valve drive device.

[0002] For example, Patent Document 1 discloses a fuel injection control device for an internal combustion engine. The fuel injection control device disclosed in Patent Document 1 injects fuel twice from an injector in one combustion cycle. When performing two injections in this manner, residual magnetism is generated by the current flowing through the solenoid coil when the injector is driven for the first time. Due to the influence of this residual magnetism, the second injection starts earlier than the commanded timing. In response to this, the fuel injection control device disclosed in Patent Document 1 uses a map to correct the timing of the start of current application during the second current application period (the period during which current is applied to the solenoid coil for the second fuel injection).

[0003] Japanese Patent Application Publication No. 6-101552

[0004] When multiple fuel injections are performed in one combustion cycle, the solenoid coil is energized the same number of times as the number of fuel injections. The period during which the solenoid coil is energized for a first injection is called the pre-stage energization period, and the period during which the solenoid coil is energized for a second injection is called the post-stage energization period. The influence of the residual magnetism described above varies depending on the energization halt period from the end of the pre-stage energization period to the start of the post-stage energization period. For this reason, it is conceivable to correct the start time of the post-stage energization period depending on the energization halt period using a map such as that disclosed in Patent Document 1. However, correcting the start time of the post-stage energization period changes the energization halt period depending on the amount of correction. As a result, a single correction of the start time of the post-stage energization period leaves an error in the injection timing due to the influence of residual magnetism.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to reduce errors in injection timing caused by the influence of residual magnetism in an electromagnetic valve drive device that causes a fuel injection valve to inject fuel multiple times during one combustion cycle.

[0006] The present invention employs the following configuration as a means for solving the above problems.

[0007] A first aspect of the present invention is an electromagnetic valve drive device that controls a period of time during which current is applied to a solenoid coil provided in a fuel injection valve, and causes the fuel injection valve to inject fuel multiple times during one combustion cycle of an internal combustion engine, and that employs a configuration including a rear-stage current-applying period correction unit that corrects the current-applying halt period and the rear-stage current-applying period by repeated calculation based on a current-applying halt period from the completion time of a front-stage current-applying period, which is the current-applying period for a previous fuel injection during the one combustion cycle, to the start time of a rear-stage current-applying period, which is the current-applying period for a next fuel injection, and an energization control unit that applies current to the solenoid coil based on the current-applying halt period and the corrected rear-stage current-applying period corrected by the rear-stage current-applying period correction unit.

[0008] The present invention corrects the power supply halt period and the post-stage power supply period by repeatedly performing calculations based on the power supply halt period, thereby making it possible to further reduce injection timing errors caused by the influence of residual magnetism compared to when the power supply halt period and the post-stage power supply period are corrected by a single calculation.

[0009] 1 is a schematic diagram showing a schematic configuration of a fuel injection valve 100 controlled by a solenoid valve drive device according to a first embodiment of the present invention. FIG. 1 is a schematic diagram showing the configuration of a solenoid valve drive device according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing the relationship between the position of the valve element and a command voltage of an energization control unit provided in the solenoid valve drive device according to the first embodiment of the present invention. FIG. 3 is a conceptual diagram of a correction amount map. FIG. 4 is a schematic diagram showing a state in which the energization start time of a subsequent stage energization period is adjusted based on a corrected energization halt period. FIG. 5 is a flowchart for explaining an example of the operation of a control processing unit in multi-stage injection control. FIG. 6 is a schematic diagram showing the energization period and change in the position of the valve element. FIG. 7 is a schematic diagram showing the configuration of a solenoid valve drive device according to a second embodiment of the present invention. FIG. 8 is a schematic diagram showing the energization period and change in the position of the valve element before correction. FIG.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a solenoid valve driving device according to the present invention will now be described with reference to the drawings.

[0011] (First embodiment) Fig. 1 is a schematic diagram showing the general configuration of a fuel injection valve 100 controlled by a solenoid valve drive device 1 of this embodiment. The solenoid valve drive device 1 of this embodiment is a drive device that drives the fuel injection valve 100. Specifically, the solenoid valve drive device 1 according to this embodiment drives the fuel injection valve 100 (solenoid valve) that injects fuel into an internal combustion engine mounted on a vehicle.

[0012] The fuel injection valve 100 is an electromagnetic valve (solenoid valve) that injects fuel into an internal combustion engine, such as a gasoline engine or a diesel engine, mounted on a vehicle. FIG. 1 is a schematic configuration diagram of the fuel injection valve 100. As shown in FIG. 1, the fuel injection valve 100 includes a fixed core 101, a valve seat 102, a solenoid coil 103, a needle 104, a valve body 105, a retainer 106, a lower stopper 107, a valve body biasing spring 108, a movable core 109, and a movable core biasing spring 110. In this embodiment, the fixed core 101, the valve seat 102, and the solenoid coil 103 are fixed members. The needle 104, the valve body 105, the retainer 106, the lower stopper 107, the valve body biasing spring 108, the movable core 109, and the movable core biasing spring 110 are movable members.

[0013] The fixed core 101 is a cylindrical member and is fixed to a housing (not shown) of the fuel injection valve 100. The fixed core 101 is made of a magnetic material. The valve seat 102 is fixed to the housing of the fuel injection valve 100. The valve seat 102 has an injection hole 102a. The injection hole 102a is a hole through which fuel is injected, and is closed when a valve element 105 is seated on the valve seat 102 and is opened when the valve element 105 is separated from the valve seat 102.

[0014] The solenoid coil 103 is formed by winding an electric wire in a circular shape. The solenoid coil 103 is arranged concentrically with the fixed core 101. The solenoid coil 103 is electrically connected to the electromagnetic valve drive device 1. When current is applied from the electromagnetic valve drive device 1, the solenoid coil 103 forms a magnetic path including the fixed core 101 and the movable core 109.

[0015] The needle 104 is a long rod member that extends along the central axis of the fixed core 101. The needle 104 is moved in the axial direction of the central axis of the fixed core 101 (the extension direction of the needle 104) by an attractive force generated by a magnetic path that includes the fixed core 101 and the movable core 109.

[0016] There is no particular limitation on the installation posture of the fuel injection valve 100. However, in the following description, the direction in which the movable core 109 moves due to the above-mentioned attractive force in the axial direction of the central axis of the fixed core 101 will be referred to as "upward," and the direction opposite to the direction in which the movable core 109 moves due to the above-mentioned attractive force will be referred to as "downward."

[0017] The valve element 105 is formed at the lower tip of the needle 104. The valve element 105 closes the injection hole 102a when seated on the valve seat 102, and opens the injection hole 102a when separated from the valve seat 102. The retainer 106 includes a guide member 106a and a flange 106b. The guide member 106a is a cylindrical member fixed to the upper tip of the needle 104. The flange 106b is formed at the end of the upper guide member 106a so as to protrude in the radial direction of the needle 104. The lower end face of the flange 106b is an abutment surface with the movable core biasing spring 110. The upper end face of the flange 106b is an abutment surface with the valve element biasing spring 108.

[0018] The lower stopper 107 is a cylindrical member fixed to the needle 104 between the valve seat 102 and the guide member 106a. The upper end surface of the lower stopper 107 is a contact surface with the movable core 109.

[0019] The valve body biasing spring 108 is a compression coil spring housed inside the fixed core 101 and is interposed between the inner wall surface of the housing and the flange 106b. The valve body biasing spring 108 biases the valve body 105 downward. That is, when the solenoid coil 103 is not energized, the biasing force of the valve body biasing spring 108 causes the valve body 105 to abut against the valve seat 102.

[0020] The movable core 109 is disposed between the guide member 106a and the lower stopper 107. The movable core 109 is a cylindrical member and is provided coaxially with the needle 104. A through-hole through which the needle 104 is inserted is formed in the center of the movable core 109, and the movable core 109 is movable along the direction in which the needle 104 extends. The upper end face of the movable core 109 is an abutment surface with the fixed core 101 and the movable core biasing spring 110. On the other hand, the lower end face of the movable core 109 is an abutment surface with the lower stopper 107. The movable core 109 is formed of a magnetic material.

[0021] The movable core biasing spring 110 is a compression coil spring interposed between the flange 106b and the movable core 109. The movable core biasing spring 110 biases the movable core 109 downward. That is, when power is not supplied to the solenoid coil 103, the movable core 109 is brought into contact with the lower stopper 107 by the biasing force of the movable core biasing spring 110.

[0022] Next, the electromagnetic valve drive device 1 according to this embodiment will be described. Fig. 2 is a schematic diagram of the electromagnetic valve drive device 1 according to this embodiment. As shown in Fig. 2, the electromagnetic valve drive device 1 includes a drive device 2 and a control device 3.

[0023] The drive device 2 is a circuit that drives the fuel injection valve 100 by energizing a solenoid coil 103, which is a coil of the fuel injection valve 100. As shown in FIG. 2, the drive device 2 includes a power supply device 2a and a switch 2b. The power supply device 2a includes at least one of a battery and a boost circuit. The battery is mounted on the vehicle. The boost circuit boosts the battery voltage, which is the output voltage of the battery, and outputs the boosted voltage.

[0024] The power supply device 2a can energize the solenoid coil 103 by outputting a battery voltage to the solenoid coil 103. The power supply device 2a can also energize the solenoid coil 103 by outputting a boosted voltage to the solenoid coil 103. The voltage output from the power supply device 2a to the solenoid coil 103 is controlled by a power supply control unit 3d (described later) of the control device 3. The power supply to the solenoid coil 103 is also controlled by a power supply control unit 3d (described later) of the control device 3.

[0025] The switch 2b is controlled to an on or off state by the control device 3. When the switch 2b is controlled to an on state, the voltage output from the power supply device 2a is supplied to the solenoid coil 103. This starts the flow of current to the solenoid coil 103. When the switch 2b is controlled to an off state, the supply of voltage from the power supply device 2a to the solenoid coil 103 is stopped. This stops the flow of current to the solenoid coil 103.

[0026] The control device 3 includes a voltage detection unit 3a and a control processing unit 3b. The voltage detection unit 3a detects the voltage (coil voltage) generated in the solenoid coil 103. For example, the coil voltage is the voltage across both ends of the solenoid coil 103. The voltage detection unit 3a outputs a signal indicating the value of the detected coil voltage (coil voltage value) to the control processing unit 3b.

[0027] The control processing unit 3b includes a valve closing detection unit 3c, a current supply control unit 3d, a rear-stage current supply period correction unit 3e, and a memory unit 3f. The valve closing detection unit 3c detects the closing of the valve element 105. That is, the valve closing detection unit 3c detects the valve closing timing (valve closing time) of the valve element 105 included in the fuel injection valve 100. The valve closing detection unit 3c reads the coil voltage value input from the voltage detection unit 3a and detects the closing of the fuel injection valve 100 based on the coil voltage value. Note that, for example, the valve closing timing indicates the time when the valve closing is detected when the time when the current supply to the solenoid coil 103 starts (valve opening time) is set to 0. That is, in such a case, the valve closing timing is equal to the elapsed time from the start of current supply to the solenoid coil 103 to the detection of the valve closing.

[0028] For example, the valve closure detection unit 3c detects the closure of the valve element 105 by detecting an inflection point of the coil voltage value. However, the valve closure detection unit 3c detects the closure of the valve element 105 by detecting an inflection point of a machining voltage value obtained by processing the coil voltage value. The machining voltage may be a differential value of the coil voltage value. Furthermore, high-frequency components may be removed from the coil voltage value used to detect the closure of the valve element 105 by a filter.

[0029] The current control unit 3d controls the power supply device 2a. The current control unit 3d controls the switch 2b to an on state or an off state. When the current control unit 3d controls the switch 2b to an on state, current is passed through the solenoid coil 103. When the current control unit 3d controls the switch 2b to an off state, current is stopped from passing through the solenoid coil 103.

[0030] 3 is a schematic diagram showing the relationship between the command voltage of the energization control unit 3d and the position of the valve element 105. The energization control unit 3d controls the energization period Ti based on a program stored in the storage unit 3f and a post-stage corrected energization period calculated by a post-stage energization period correction unit 3e (described later). The energization period Ti indicates the period during which current is supplied to the solenoid coil 103, and is the time from when current supply to the solenoid coil 103 starts at an energization start time SOI until when the current supply stops at an energization stop time EOI. In other words, the energization stop time EOI is the time at which the energization period Ti ends.

[0031] The control device 3 controls the current conduction period Ti to control the amount of fuel injected from the fuel injection valve 100 (hereinafter referred to as the fuel injection amount). The control device 3 also controls the current conduction start time and current conduction stop time of the current conduction period Ti. In other words, the control of the current conduction period Ti here includes not only the control of the length of the current conduction period Ti but also the control of the start and stop times of the current conduction period Ti.

[0032] The electromagnetic valve drive device 1 of this embodiment performs multi-stage injection control, in which the fuel injection valve 100 injects fuel multiple times in one combustion cycle of an internal combustion engine (for example, a cycle in which the intake stroke, compression stroke, combustion stroke, and exhaust stroke are performed once each). In this embodiment, as shown in Fig. 3, an example will be described in which the fuel injection valve 100 performs two fuel injections in one combustion cycle. Of the two fuel injections performed in one combustion cycle, the earlier fuel injection is called a front-stage injection, and the next fuel injection is called a rear-stage injection.

[0033] The fuel injection valve 100 injects fuel for each current conduction period Ti. That is, in this embodiment, two current conduction periods Ti are provided in one combustion cycle. The previous current conduction period Ti is a current conduction period for pre-stage injection. The previous current conduction period Ti is referred to as a pre-stage current conduction period Tia. The next current conduction period Ti is a current conduction period for post-stage injection. The next current conduction period Ti is referred to as a post-stage current conduction period Tib.

[0034] Between the first-stage current supply period Tia and the second-stage current supply period Tib, there is provided a current supply halt period Tp during which current supply to the solenoid coil 103 is halted. This current supply halt period Tp is the period from current supply stop time EOI of the first-stage current supply period Tia to current supply start time SOI of the second-stage current supply period Tib.

[0035] The rear-stage current supply period correction unit 3e corrects the current supply halt period and the rear-stage current supply period Tib based on a correction amount map M described below that is stored in the storage unit 3f. The rear-stage current supply period correction unit 3e refers to the correction amount map M and determines the correction amounts for the current supply halt period and the rear-stage current supply period Tib based on the current supply halt period Tp.

[0036] If the value of the power supply suspension period Tp before correction is stored in advance in the storage unit 3 f as a suspension period map (not shown), the value of the suspension period map may be read out and acquired from the storage unit 3 f. Furthermore, the power supply suspension period Tp before correction may be calculated based on the current rotation speed of the internal combustion engine, the total power supply period in one combustion cycle corresponding to the current intake air amount of the internal combustion engine, and the predetermined number of executions of multi-stage fuel injection in one combustion cycle (the predetermined number of power supply periods in one combustion cycle).

[0037] Furthermore, the rear-stage current supply period correction unit 3e corrects the current supply halt period Tp and the rear-stage current supply period Tib based on the calculated correction amount. The corrected current supply halt period Tp and the corrected rear-stage current supply period Tib are input to the current supply control unit 3d. The current supply control unit 3d supplies current for the rear-stage injection to the solenoid coil 103 based on the corrected current supply halt period Tp and the corrected rear-stage current supply period Tib.

[0038] When multi-stage injection control is performed, the start timing of the rear-stage injection is advanced beyond a predetermined value due to the influence of residual magnetism after the rear-stage injection and the increase in the effective boost voltage. Residual magnetism is generated in the solenoid coil 103 after energization for fuel injection. For example, the magnetic flux generated in the solenoid coil 103 by energization for the rear-stage injection approaches zero after the end of energization for the rear-stage injection, but does not immediately reach zero at the end time EOI of the energization for the rear-stage injection period Tia. Therefore, magnetic flux due to energization for the rear-stage injection may remain in the solenoid coil 103 at the start time SOI of the energization for the rear-stage injection period Tib. In other words, the magnetic flux remaining in the fuel injection valve 100 at the start time SOI of the rear-stage injection period Tib is residual magnetism (residual magnetic flux density). Due to the influence of this residual magnetism, the attractive force of the movable core 109 at the start of the rear-stage injection is greater than the attractive force of the movable core 109 at the start time SOI of the rear-stage injection. This advances the start timing of the post-stage injection.

[0039] The effective boost voltage is the voltage applied to the solenoid coil 103 at the energization start time SOI of the energization period Ti. When energization for the pre-stage injection is completed, the voltage remaining in the solenoid coil 103 temporarily drops to the clamp voltage and then decreases at a predetermined time constant to return to zero. For this reason, the voltage of the solenoid coil 103 may not have returned to zero at the energization start time SOI of the post-stage energization period Tib. Due to the influence of this residual voltage, the boost voltage applied to the solenoid coil 103 at the energization start time SOI of the post-stage energization period Tib is higher than the value at the energization start time SOI of the pre-stage energization period. In other words, the effective boost voltage increases. This advances the start timing of the post-stage injection.

[0040] As described above, the correction amount map M is a map showing the relationship between the power supply halt period Tp and the correction amount for the rear-stage power supply period Tib. This correction amount is set so that the power supply halt period Tp is corrected to be longer to optimize the start timing of the rear-stage injection due to the advancement of the start timing of the rear-stage injection caused by the increase in residual magnetism and effective boost voltage, and the rear-stage power supply period Tib is corrected to be shorter to advance the end timing of the rear-stage injection.

[0041] Specifically, when the start timing of the rear-stage injection is advanced by a time Ta (see FIG. 7 ) from the design value, the power supply stop period Tp is corrected to be longer by the time Ta in order to make the power supply start time SOI of the rear-stage power supply period Tib coincide with the predetermined value, and the power supply stop time EOI of the rear-stage power supply period Tib coincide with the design value, so the correction amount is set to shorten the rear-stage power supply period Tib by the time Ta. This correction amount is determined by preliminary experiments and simulations performed in advance.

[0042] As described above, the influence of residual magnetism and the influence of an increase in the effective boost voltage decrease over time. In other words, the longer the power supply suspension period Tp, the less the advancement of the start timing of the post-injection. For this reason, the correction amount map M associates the power supply suspension period Tp with the correction amount so that the longer the power supply suspension period Tp, the smaller the correction amount.

[0043] FIG. 4 is a conceptual diagram of the correction amount map M. As shown in this figure, the correction amount map M is a map showing the relationship between the power supply halt period Tp and the correction amount for the subsequent-stage power supply period Tib. Note that in FIG. 4, the correction amount values ​​are abbreviated as "XX." For example, as shown in FIG. 4, in the correction amount map M, the power supply halt period Tp is divided into predetermined periods Tp1 to Tpn. Furthermore, in the correction amount map M, the correction amount for the subsequent-stage power supply period Tib is set for each of Tp1 to Tpn.

[0044] 2 , the latter-stage current supply period correction unit 3e includes a correction amount calculation unit 3e1, a corrected current supply suspend period calculation unit 3e2, and a convergence condition determination unit 3e3. The correction amount calculation unit 3e1 calculates a correction amount for the current supply start time SOI of the latter-stage current supply period Tib based on the pre-correction current supply period, which is the current supply suspend period Tp before correction. The correction amount calculation unit 3e1 calculates the correction amount from a correction amount map M. The post-correction current supply suspend period calculation unit 3e2 calculates the post-correction current supply suspend period by correcting the pre-correction current supply suspend period based on the correction amount calculated by the correction amount calculation unit 3e1.

[0045] In this embodiment, the rear-stage current conduction period correction unit 3e repeatedly calculates the corrected current conduction halt period using the corrected current conduction halt period as the pre-correction current conduction change period until a predetermined convergence condition is met. In other words, until the convergence condition is met, the correction amount calculation unit 3e1 calculates a correction amount using the previous post-correction current conduction halt period as the pre-correction current conduction change period, and the post-correction current conduction halt period calculation unit 3e2 calculates the corrected current conduction halt period based on the calculated correction amount. In other words, the rear-stage current conduction period correction unit 3e repeatedly calculates the correction amount and the corrected current conduction halt period based on the most recent current conduction halt period until the convergence condition is met, thereby correcting the current conduction halt period Tp and the rear-stage current conduction period Tib.

[0046] The convergence condition determination unit 3e3 determines whether the convergence condition for stopping the above-mentioned repetitive calculation is met. When the convergence condition determination unit 3e3 determines that the convergence condition is met, the calculations by the correction amount calculation unit 3e1 and the post-correction power-on pause period calculation unit 3e2 are stopped. In addition, the power-on start time SOI of the second-stage power-on period Tib is determined based on the most recent post-correction power-on pause period at the time the convergence condition is met.

[0047] For example, the convergence condition determination unit 3e3 determines that the convergence condition is met when the difference between the most recent corrected power-on pause period and the immediately preceding corrected power-on pause period is within a predetermined range. In other words, the convergence condition in this case is that the difference between the most recent corrected power-on pause period and the immediately preceding corrected power-on pause period is within a predetermined range.

[0048] For example, the convergence condition of the convergence condition determination unit 3e3 is set to a predetermined range in which the positive threshold value can be expressed in so-called least significant bit (LSB) units in numerical representation as 2LSB or less and the negative threshold value can be expressed as 2LSB or more, and it is determined that the convergence condition is achieved if the difference between the most recent corrected power-on pause period and the immediately preceding corrected power-on pause period is within the range of the positive and negative threshold values. Note that in this embodiment, the value (resolution) of 1LSB of the power-on pause period is set to 1 microsecond, for example.

[0049] Alternatively, the convergence condition determination unit 3e3 may determine that the convergence condition is met when the difference between the correction amount used to determine the most recent corrected power supply pause period and the correction amount used to determine the immediately previous corrected power supply pause period is within a predetermined range. In other words, the convergence condition in this case is that the difference between the correction amount used to determine the most recent corrected power supply pause period and the correction amount used to determine the immediately previous corrected power supply pause period is within a predetermined range.

[0050] For example, the convergence condition of the convergence condition determination unit 3e3 is set to a predetermined range in which the positive threshold can be expressed in so-called least significant bit (LSB) units in numerical representation as 2LSB or less and the negative threshold can be expressed as 2LSB or more, and it is determined that the convergence condition is achieved if the difference between the correction amount used to calculate the most recent corrected power-on pause period and the correction amount used to calculate the immediately previous corrected power-on pause period is within the range of the positive and negative thresholds. Note that in this embodiment, the value (resolution) of 1LSB of the power-on pause period is set to 1 microsecond, for example.

[0051] Alternatively, the convergence condition determination unit 3e3 may determine that the convergence condition is met when the number of calculations of the corrected power-on pause period reaches a predetermined number. In this case, the convergence condition is that the number of calculations of the corrected power-on pause period reaches a predetermined number. For example, the convergence condition determination unit 3e3 determines that the convergence condition is met when the number of calculations of the corrected power-on pause period reaches four, assuming that the predetermined number is four.

[0052] 5 is a schematic diagram showing the state in which the energization start time SOI of the second-stage energization period Tib is adjusted based on the corrected energization pause period Tp′. In FIG. 5, the upper part shows the command voltage of the energization control unit 3 d, the middle part shows the position of the valve element 105, and the lower part shows the count value of the countdown timer.

[0053] 5, the energization control unit 3d in this embodiment starts energizing the solenoid coil 103 at the energization start time SOI of the first-stage energization period Tia, and simultaneously operates a countdown timer whose initial value at the energization start time SOI is the first-stage energization period Tia to measure the time until the energization stop time EOI of the first-stage energization period Tia. In other words, the timing when the countdown timer whose initial value is the first-stage energization period Tia reaches zero is the energization stop time EOI of the first-stage energization period Tia.

[0054] Next, the energization control unit 3d stops energization of the solenoid coil 103 at the energization stop time EOI of the first-stage energization period Tia, and at the same time, starts a countdown timer whose initial value at the energization stop time EOI is the value of the corrected energization halt period Tp' to measure the time until the energization start time SOI of the second-stage energization period Tib. The timing when the countdown timer whose initial value is the value of the corrected energization halt period Tp' reaches zero is the energization start time SOI of the second-stage energization period Tib.

[0055] Furthermore, the energization control unit 3d resumes energization of the solenoid coil 103 at the energization start time SOI of the latter-stage energization period Tia, and simultaneously operates a countdown timer whose initial value at the energization start time SOI of the latter-stage energization period Tib is the corrected latter-stage energization period Tib to measure the time until the energization stop time EOI of the latter-stage energization period Tib. Thus, the timing when the countdown timer whose initial value is the corrected latter-stage energization period Tib reaches zero is the energization stop time EOI of the latter-stage energization period Tib. The energization control unit 3d stops energization of the solenoid coil 103 at the energization stop time EOI of the latter-stage energization period Tib, thereby ending the multi-stage fuel injection for one combustion cycle.

[0056] In the energization control unit 3d configured as described above, when the value of the energization pause period Tp is replaced with the corrected energization pause period Tp′ obtained after the above-described repeated calculations and the energization start time SOI of the rear-stage energization period Tib is adjusted, the energization stop time EOI of the rear-stage energization period Tib changes by the same amount as the correction amount of the energization start time SOI. In other words, even if the energization start time SOI of the rear-stage energization period Tib is adjusted, the injection amount of the rear-stage injection (the time from the energization start time SOI of the rear-stage energization period Tib to the energization stop time EOI measured by the countdown timer) does not change. For this reason, in this embodiment, the rear-stage energization period correction unit 3e includes an energization stop time adjustment unit 3e4 that corrects the initial value of the countdown timer that measures the rear-stage energization period Tib to adjust the energization stop time EOI of the rear-stage energization period Tib so that the injection amount of the rear-stage injection becomes a predetermined value.

[0057] The power supply stop time adjustment unit 3e4 adjusts the power supply stop time EOI of the rear-stage power supply period Tib so that the amount of fuel injected in the rear-stage injection is equal to a predetermined value. For example, the power supply stop time adjustment unit 3e4 sets the corrected rear-stage power supply period Tib, which is a value obtained by subtracting the correction amount for the power supply start time SOI from the value of the rear-stage power supply period Tib before correction, as the initial value of a countdown timer for measuring the elapsed time from the power supply start time SOI of the above-mentioned rear-stage power supply period Tib to the power supply stop time EOI. This makes it possible to properly adjust the power supply stop time EOI so that the length from the power supply start time SOI to the power supply stop time EOI of the rear-stage power supply period Tib based on the corrected power supply stop period Tp′ matches a predetermined value.

[0058] The storage unit 3f stores the above-mentioned correction amount map M. The storage unit 3f may also store the above-mentioned convergence conditions. The storage unit 3f also stores a drive control program for the fuel injection valve 100 and various calculated values.

[0059] Next, an example of the operation of the control processing unit 3b in the multi-stage injection control will be described with reference to Figures 6 and 7. Figure 6 is a flowchart for explaining an example of the operation of the control processing unit 3b in the multi-stage injection control. Figure 7 is a schematic diagram showing the current application period Ti and the change in the position of the valve element 105.

[0060] As described above, the control processing unit 3b performs two fuel injections, i.e., a pre-stage injection and a post-stage injection, during one combustion cycle. For example, the control processing unit 3b corrects the post-stage current application period Tib by executing steps S1 to S6 shown in FIG. 6 before the fuel injection.

[0061] In order to correct the rear-stage current application period Tib, the correction amount calculation unit 3e1 of the control processing unit 3b first refers to a correction amount map (step S1), and then calculates a correction amount based on the pre-correction current application suspend period Tp (step S2).

[0062] The corrected power supply suspension period calculation unit 3e2 of the control processing unit 3b calculates the corrected power supply suspension period using the correction amount calculated in step S2. Subsequently, the convergence condition determination unit 3e3 of the control processing unit 3b determines whether the convergence condition is met (step S4).

[0063] If it is determined in step S4 that the convergence condition is not met, step S1 is executed again. When step S1 is executed again, the correction amount calculation unit 3e1 sets the post-correction power supply suspension period calculated in step S3 as the pre-correction power supply suspension period.

[0064] On the other hand, if it is determined in step S4 that the convergence condition is met, the post-current supply period correction unit 3e establishes the corrected current supply halt period Tp' obtained in step S3 as the corrected current supply halt period Tp', and thereby determines the current supply start time SOI of the post-current supply period Tib (step S5). Subsequently, the post-current supply period correction unit 3e adjusts the post-current supply period Tib so that the injection amount coincides with a predetermined value, and thereby determines the current supply end time EOI (step S6).

[0065] The correction of the power supply halt period Tp and the rear-stage power supply period Tib is completed by steps S1 to S6. Thereafter, the power supply control unit 3d of the control processing unit 3b controls the drive unit 2 based on the power supply halt period Tp' and the rear-stage power supply period Tib, and energizes the solenoid coil 103 to cause the fuel injection valve 100 to inject fuel (step S7).

[0066] For example, as shown in the upper part of Figure 7, if fuel injection is performed based on the pre-current period Tia, the current-supply halt period Tp, and the post-current period Tib before steps S1 to S6 are executed (before the current-supply halt period Tp and the post-current period Tib are corrected), the injection start timing of the post-stage injection will be advanced by the time Ta due to the influence of residual magnetism, etc.

[0067] 7, by applying the corrected current supply pause period Tp' to correct the current supply start time SOI of the rear-stage current supply period Tib in step S5, the injection start timing of the rear-stage injection is delayed by the time Ta, and as a result, the current supply start time SOI coincides with the predetermined timing (command value). On the other hand, when the current supply start time SOI of the rear-stage current supply period Tib is corrected in step S5 based on the corrected current supply pause period Tp' calculated in step S3, the current supply end time EOI of the rear-stage injection is also delayed by the time Ta.

[0068] 7, the delay in the post-injection de-energization time EOI that occurred in step S5 is eliminated by shortening the post-injection energization period Tib by the time Ta in step S6. Therefore, by having the control processing unit 3b perform the above-mentioned steps S1 to S6, it becomes possible to execute appropriate fuel injection that matches the command value in step S7.

[0069] The electromagnetic valve drive device 1 of this embodiment controls the energization period of a solenoid coil 103 provided in a fuel injection valve 100, causing the fuel injection valve 100 to inject fuel multiple times during one combustion cycle of an internal combustion engine. The electromagnetic valve drive device 1 of this embodiment also includes a rear-stage energization period correction unit 3e and an energization control unit 3d. The rear-stage energization period correction unit 3e corrects the energization halt period Tp and the rear-stage energization period by repeated calculation based on the energization halt period from the stop time of the front-stage energization period, which is the energization period for a previous fuel injection during one combustion cycle, to the start time of the rear-stage energization period, which is the energization period for the next fuel injection. The energization control unit 3d energizes the solenoid coil 103 based on the corrected energization halt period Tp' and the corrected rear-stage energization period determined by the rear-stage energization period correction unit 3e.

[0070] The solenoid valve drive device 1 of this embodiment corrects the power supply pause period and adjusts the subsequent power supply period by performing repeated calculations based on the power supply pause period. Note that repeated calculations based on the power supply pause period mean repeating calculations using the most recent power supply pause period as an explanatory variable in the calculation process. The solenoid valve drive device 1 of this embodiment can more accurately reduce injection timing errors caused by the influence of residual magnetism compared to correcting the power supply pause period by referencing a map only once.

[0071] Furthermore, in the solenoid valve drive device 1 of this embodiment, the rear-stage power supply period correction unit 3e has a correction amount calculation unit 3e1 and a corrected power supply halt period calculation unit 3e2. Correction amount calculation unit 3e1 first calculates a correction amount for the start time of the rear-stage power supply period based on a pre-correction power supply halt period, which is the power supply halt period before correction. Next, post-correction power supply halt period calculation unit 3e2 corrects the pre-correction power supply halt period based on the correction amount to calculate the corrected power supply halt period. Furthermore, the rear-stage power supply period correction unit 3e continues to repeatedly calculate the correction amount and the corrected power supply halt period, using the most recent post-correction power supply halt period as the pre-correction power supply halt period, until a predetermined convergence condition is achieved.

[0072] The electromagnetic valve drive device 1 of this embodiment repeatedly calculates the correction amount based on the current supply halt period using the correction amount calculation unit 3e1 and calculates the corrected current supply halt period based on the correction amount using the subsequent stage current supply period correction unit 3e. By repeating these calculations, the electromagnetic valve drive device 1 of this embodiment can bring the injection timing closer to the command value.

[0073] The solenoid valve drive device 1 of this embodiment also includes a storage unit 3f. The storage unit 3f stores a correction amount map M that indicates the relationship between the power supply halt period and the correction amount. The correction amount calculation unit 3e1 calculates the correction amount based on the correction amount map M. The solenoid valve drive device 1 of this embodiment can calculate the correction amounts for the power supply halt period and the latter-stage power supply period Tib by referring to the correction amount map M. Therefore, the solenoid valve drive device 1 of this embodiment can easily calculate the correction amounts for the power supply halt period and the latter-stage power supply period Tib.

[0074] Furthermore, in the electromagnetic valve drive device 1 of this embodiment, for example, the subsequent current supply period correction unit 3e determines that the convergence condition has been achieved when the difference between the most recent corrected current supply pause period and the immediately previous corrected current supply pause period is within a predetermined range.

[0075] The solenoid valve drive device 1 of this embodiment stops the repeated calculation when the amount of change in the most recent corrected energization pause period from the immediately previous corrected energization pause period decreases. Therefore, the calculated corrected energization pause period can reduce errors in injection timing due to residual magnetism, etc. For example, by setting the convergence condition that the amount of change in the corrected energization pause period is within a range that can be expressed in least significant bit (LSB) units as a positive threshold value of 2 LSB or less and a negative threshold value of 2 LSB or more, errors in injection timing due to residual magnetism, etc. are substantially eliminated.

[0076] Furthermore, in the electromagnetic valve drive device 1 of this embodiment, for example, the subsequent current supply period correction unit 3e determines that the convergence condition has been achieved when the difference between the correction amount used to determine the most recent corrected current supply pause period and the correction amount used to determine the immediately previous corrected current supply pause period is within a predetermined range.

[0077] The solenoid valve drive device 1 of this embodiment stops the repeated calculation when the amount of change in the most recent correction amount from the immediately previous correction amount decreases. Therefore, the calculated correction amount can reduce errors in injection timing due to residual magnetism, etc. For example, by setting the convergence condition that the amount of change in the correction amount falls within a range that can be expressed in least significant bit (LSB) units as a positive threshold value of 2 LSB or less and a negative threshold value of 2 LSB or more, errors in injection timing due to residual magnetism, etc. are substantially eliminated.

[0078] In the electromagnetic valve drive device 1 of this embodiment, the rear-stage current-carrying-period correcting unit 3 e can also determine that the convergence condition is met when the number of calculations of the corrected current-carrying-off period reaches a predetermined number. The number of calculations of the corrected current-carrying-off period can be determined, for example, by a preliminary experiment or simulation that is carried out in advance.

[0079] According to the electromagnetic valve drive device 1 of this embodiment, the repeated calculation is stopped when the number of calculations of the corrected de-energization period reaches a predetermined number, thereby preventing the repeated calculation from diverging.

[0080] In the solenoid valve drive device 1 of this embodiment, the post-stage current supply period correction unit 3e corrects the current supply halt period related to the start time SOI of the post-stage current supply period based on the most recent correction amount after the repeated calculation was stopped. The post-stage current supply period correction unit 3e also corrects the post-stage current supply period related to the current supply end time EOI based on the correction amount.

[0081] The solenoid valve drive device 1 of this embodiment can adjust the injection start time of the rear stage injection (the opening timing of the solenoid valve) and the time (fuel injection amount) from the injection start time of the rear stage injection to the injection stop time (the closing timing of the solenoid valve) to the command value. Therefore, errors in the opening timing of the solenoid valve (earlier opening timing) and errors in the fuel injection amount (increase in the effective fuel injection amount) in the rear stage injection due to residual magnetism after the front stage injection, etc. are substantially eliminated. The valve closing timing can be detected by the valve closing detection unit 3c.

[0082] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Figures 8 to 10. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0083] 8 is a schematic diagram of the electromagnetic valve drive device 1A of this embodiment. As shown in this figure, in this embodiment, the storage unit 3f stores a correction amount derivation function F instead of the correction amount map M of the first embodiment. In addition, in this embodiment, the correction amount calculation unit 3e1 calculates the correction amount by repeatedly calculating the correction amount derivation function F until a predetermined convergence condition is achieved.

[0084] The correction amount derivation function F is a function for determining the correction amount x for the power supply halt period and the rear-stage power supply period, with the power supply halt period used as an explanatory variable. The correction amount derivation function F will now be described with reference to FIGS. 9 and 10. FIG. 9 is a schematic diagram showing the power supply halt period Tp and the rear-stage power supply period Tib before correction and the change in the position of the valve disc 105. FIG. 10 is a schematic diagram showing the power supply halt period Tp and the rear-stage power supply period Tib after correction and the change in the position of the valve disc 105.

[0085] As shown in Figures 9 and 10, the time from the energization start time SOI of the front-stage energization period Tia, which is not affected by residual magnetism, etc., to the valve-opening timing of the front-stage injection is defined as Tona. The time from the energization stop time EOI of the front-stage energization period Tia to the valve-opening timing of the rear-stage injection before correction is defined as Tonb. The power-on halt period before correction is defined as Tp. The time (advancement time) by which the valve-opening timing of the rear-stage injection, which is affected by residual magnetism, etc., of the front-stage injection, is advanced compared to the above-mentioned Tona is defined as ΔTon. The time from the energization stop time EOI of the front-stage energization period Tia to the valve-opening timing of the rear-stage injection after correction is defined as Tonb'. The power-on halt period after correction is defined as Tp'. The corrected advancement time is defined as ΔTon'. The correction amount of the power-on halt period to eliminate the influence of residual magnetism, etc., of the front-stage injection is defined as x.

[0086] The time Tonb from the de-energization time EOI of the pre-energization period Tia to the valve opening timing of the post-injection before correction is expressed by the following equation (1) when ΔTon is a negative value.

[0087]

[0088] The corrected power supply suspension period Tp' is obtained by adding the correction amount x to the power supply suspension period Tp before correction. Note that by applying the corrected power supply suspension period Tp', the advancement time is also the corrected advancement time ΔTon' rather than the pre-correction ΔTon. Therefore, as shown in the following equation (2), the time Tonb' from the de-energization time EOI of the corrected early-stage power supply period Tia to the corrected valve-open timing of the late-stage injection is the sum of the value obtained by adding the correction amount x to the pre-correction power supply suspension period Tp and the value obtained by adding the time Tona from the energization start time SOI of the early-stage power supply period Tia that is not affected by residual magnetism or the like to the valve-open timing of the late-stage injection to the sum of the corrected advancement time ΔTon' (a negative value).

[0089]

[0090] Furthermore, the time Tonb' from the current stop time EOI of the pre-current period Tia to the valve opening timing of the post-injection after correction for the effects of residual magnetism, etc. can also be expressed as equal to the sum of the current stop period Tp before correction and the time Tona from the current start time SOI of the pre-current period Tia that is not affected by residual magnetism, etc. to the valve opening timing of the post-injection, as shown in the following equation (3):

[0091]

[0092] Here, the advance time ΔTon before correction or the advance time ΔTon′ after correction can be expressed by a quadratic approximation such as the following equation (4) which includes constants α, β, and γ obtained in advance by experiments or simulations.

[0093]

[0094] Substituting equation (4) into the corrected advance time ΔTon′ in equation (3) gives the following equation (5), which can be further transformed into equation (6) below.

[0095]

[0096]

[0097] Here, if the constant α in equation (6) is A, (1 + 2αTp + β) is B, and (αTp2 + βTp + γ) is C, the correction amount x can be calculated by the following equation (7), which is a further modification of equation (6). Therefore, equation (7) and the above A, B, and C constitute a correction amount derivation function F for deriving the correction amount x based on the power supply suspension period Tp before correction.

[0098]

[0099] The correction amount calculation unit 3e1 repeatedly calculates the correction amount x using the correction amount derivation function F, for example, until the above-mentioned predetermined convergence condition is achieved, thereby deriving a correction amount that can reduce or eliminate errors in the injection timing and injection amount.

[0100] The solenoid valve drive device 1A of this embodiment includes a storage unit 3f that stores a correction amount derivation function F for determining the correction amount x using the power supply pause period Tp as an explanatory variable. The correction amount calculation unit 3e1 repeatedly calculates the correction amount x and the power supply pause period using the correction amount derivation function F until the above-mentioned predetermined convergence condition is met. The corrected power supply pause period calculation unit 3e2 determines the corrected power supply pause period and the corrected subsequent stage power supply period based on the most recent correction amount and power supply pause period after the repeated calculations have been stopped.

[0101] The solenoid valve drive device 1A of this embodiment corrects the power supply halt period and the post-stage power supply period by repeatedly calculating the power supply halt period Tp, as in the first embodiment. Therefore, the solenoid valve drive device 1A of this embodiment can reduce errors in injection timing due to the influence of residual magnetism, etc., as in the case where the power supply halt period and the post-stage power supply period are corrected by repeatedly referring to a map.

[0102] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above-described embodiments. The shapes and combinations of the components shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0103] In the above embodiment, an example in which two fuel injections are performed in one combustion cycle has been described. However, this is not limited thereto. Three or more fuel injections may be performed in one combustion cycle. In such a case, for example, of three consecutive fuel injections performed in one combustion cycle, the earliest fuel injection is a pre-stage injection and the second fuel injection is a post-stage injection (next fuel injection). Based on the pre-correction energization halt period from the energization end timing of the earliest fuel injection to the energization start timing of the second fuel injection, the energization halt period from the end timing of the earliest fuel injection to the start timing of the second fuel injection and the energization period of the second fuel injection can be corrected. Furthermore, based on the energization halt period from the energization end timing of the second fuel injection to the energization start timing of the third fuel injection, the second fuel injection can be treated as a pre-stage injection and the third fuel injection as a post-stage injection (next fuel injection), the energization halt period from the end timing of the second fuel injection to the start timing of the third fuel injection and the energization period of the third fuel injection can be corrected. As described above, even when fuel injection is performed three or more times in one combustion cycle, the same control as in the above embodiment can be performed.

[0104] The above embodiment can also be described as follows, for example:

[0105] (Supplementary Note 1) An electromagnetic valve drive device that controls a period of energization of a solenoid coil provided in a fuel injection valve and causes the fuel injection valve to inject fuel multiple times during one combustion cycle of an internal combustion engine, comprising: a rear-stage energization period correction unit that corrects the energization halt period and the rear-stage energization period by repeated calculation based on an energization halt period from a completion time of a front-stage energization period, which is the energization period for a previous fuel injection during the one combustion cycle, to a start time of a rear-stage energization period, which is the energization period for a next fuel injection; and an energization control unit that energizes the solenoid coil based on the energization halt period and the corrected rear-stage energization period corrected by the rear-stage energization period correction unit.

[0106] (Supplementary Note 2) The solenoid valve drive device according to Supplementary Note 1, wherein the latter stage current supply period correction unit includes: a correction amount calculation unit that calculates a correction amount for a start time of the latter stage current supply period based on a pre-correction current supply pause period that is the current supply pause period before correction; and a post-correction current supply pause period calculation unit that corrects the pre-correction current supply pause period based on the correction amount to calculate a post-correction current supply pause period, and the latter stage current supply period correction unit repeatedly calculates the post-correction current supply pause period by using the post-correction current supply pause period as the pre-correction current supply pause period until a predetermined convergence condition is achieved.

[0107] (Supplementary Note 3) The electromagnetic valve drive device according to Supplementary Note 2, further comprising: a storage unit that stores a map indicating a relationship between the power supply suspension period and the correction amount; and the correction amount calculation unit calculates the correction amount based on the map.

[0108] (Supplementary Note 4) The electromagnetic valve drive device according to claim 2, further comprising: a storage unit that stores a function that can derive the correction amount using the power supply stop period as an explanatory variable; and the correction amount calculation unit calculates the correction amount based on the function.

[0109] (Supplementary Note 5) The electromagnetic valve drive device according to any one of Supplementary Notes 2 to 4, wherein the latter-stage current-carrying-period correction unit determines that the convergence condition is achieved when a difference between the latest corrected current-carrying-pause period and the immediately previous corrected current-carrying-pause period is within a predetermined range.

[0110] (Supplementary Note 6) The electromagnetic valve drive device according to any one of Supplementary Notes 2 to 4, wherein the latter-stage current-carrying-period correction unit determines that the convergence condition is achieved when a difference between the correction amount used to calculate the most recent corrected current-carrying-pause period and the correction amount used to calculate the immediately previous corrected current-carrying-pause period is within a predetermined range.

[0111] (Supplementary Note 7) The electromagnetic valve drive device according to any one of Supplementary Notes 2 to 4, wherein the latter-stage current-carrying-period correction unit determines that the convergence condition is achieved when the number of calculations of the corrected current-carrying-off period reaches a predetermined number.

[0112] (Appendix 8) The electromagnetic valve drive device according to any one of claims 2 to 7, characterized in that the energization control unit performs processing to determine the start time of the latter-stage energization period based on a value obtained by adding the corrected energization halt period to the former-stage energization period, using the start time of the former-stage energization period as a reference, performs processing to determine the end time of the latter-stage energization period using the corrected latter-stage energization period, using the start time of the latter-stage energization period as a reference, and energizes the solenoid coil during the period from the start time of the latter-stage energization period to the end time of the latter-stage energization period.

[0113] (Supplementary Note 9) The electromagnetic valve drive device according to any one of claims 2 to 7, characterized in that the energization control unit: performs processing to determine a start time of the latter-stage energization period based on the corrected energization halt period, using the completion time of the former-stage energization period as a reference; performs processing to determine an end time of the latter-stage energization period using the corrected latter-stage energization period, using the start time of the latter-stage energization period as a reference; and energizes the solenoid coil during a period from the start time of the latter-stage energization period to the end time of the latter-stage energization period.

[0114] REFERENCE SIGNS LIST 1 Electromagnetic valve driving device 1A Electromagnetic valve driving device 2 Driving device 2a Power supply device 2b Switch 3 Control device 3a Voltage detection unit 3b Control processing unit 3c Valve closing detection unit 3d Current control unit 3e Post-stage current application period correction unit 3e1 Correction amount calculation unit 3e2 Corrected current application stop period calculation unit 3e3 Convergence condition determination unit 3e4 Current application stop time adjustment unit 3f Memory unit 100 Fuel injection valve 103 Solenoid coil F Correction amount derivation function M Correction amount map (map)

Claims

1. An electromagnetic valve driving device that controls the energization period of a solenoid coil provided in a fuel injection valve and injects fuel a plurality of times into the fuel injection valve during one combustion cycle of an internal combustion engine, a subsequent energization period correction unit that corrects the energization pause period and the subsequent energization period by iterative calculation based on the energization pause period from the completion time of the previous energization period, which is the energization period for the previous fuel injection during the one combustion cycle, to the start time of the subsequent energization period, which is the energization period for the next fuel injection; and an energization control unit that energizes the solenoid coil based on the corrected energization pause period and the corrected subsequent energization period corrected by the subsequent energization period correction unit. The electromagnetic valve driving device is characterized by comprising the above.

2. The subsequent energization period correction unit includes: a correction amount calculation unit that obtains a correction amount for the start time of the subsequent energization period based on the pre-correction energization pause period, which is the energization pause period before correction; and a post-correction energization pause period calculation unit that corrects the pre-correction energization pause period based on the correction amount to obtain a post-correction energization pause period. The subsequent energization period correction unit repeats obtaining the post-correction energization pause period until a predetermined convergence condition is achieved, using the post-correction energization pause period as the pre-correction energization pause period. The electromagnetic valve driving device according to claim 1 is characterized by the above.

3. The electromagnetic valve driving device according to claim 2 is characterized by comprising a storage unit that stores a map showing the relationship between the energization pause period and the correction amount, and the correction amount calculation unit obtains the correction amount based on the map.

4. The electromagnetic valve driving device according to claim 2 is characterized by comprising a storage unit that stores a function from which the correction amount can be derived using the energization pause period as an explanatory variable, and the correction amount calculation unit obtains the correction amount based on the function.

5. The electromagnetic valve driving device according to claim 2 is characterized in that the subsequent energization period correction unit determines that the convergence condition is achieved when the difference between the most recent post-correction energization pause period and the previous post-correction energization pause period is within a predetermined range.

6. The electromagnetic valve driving device according to claim 2 is characterized in that the subsequent energization period correction unit determines that the convergence condition is achieved when the difference between the correction amount used to obtain the most recent post-correction energization pause period and the correction amount used to obtain the previous post-correction energization pause period is within a predetermined range.

7. The electromagnetic valve driving device according to claim 2, wherein the post-stage energization period correction unit determines that the convergence condition is achieved when the number of calculations of the corrected energization pause period reaches a predetermined number of times.

8. The energization control unit performs a process of estimating the start time of the post-stage energization period based on a value obtained by adding the corrected energization pause period to the pre-stage energization period with reference to the start time of the pre-stage energization period, performs a process of estimating the end time of the post-stage energization period using the corrected post-stage energization period with reference to the start time of the post-stage energization period, and energizes the solenoid coil during a period from the start time to the end time of the post-stage energization period. The electromagnetic valve driving device according to any one of claims 2 to 7, characterized in that.

9. The energization control unit performs a process of estimating the start time of the post-stage energization period based on the corrected energization pause period with reference to the completion time of the pre-stage energization period, performs a process of estimating the end time of the post-stage energization period using the corrected post-stage energization period with reference to the start time of the post-stage energization period, and energizes the solenoid coil during a period from the start time to the end time of the post-stage energization period. The electromagnetic valve driving device according to any one of claims 2 to 7, characterized in that.