Electromagnetic valve drive device

Abstract

An electromagnetic valve drive device wherein an energization period correction unit, in a first injection mode, corrects an energization period on the assumption of a linear relationship between a valve closing timing and a correction amount for the energization period, and, in a second injection mode, corrects the energization period on the basis of the relationship between a valve closing timing during a movement period due to rebound of a valve part and an actual energization period.

Description

Solenoid valve drive unit

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

[0002] Patent Document 1 discloses a fuel injection valve control device capable of injecting a small amount of fuel. The fuel injection valve control device disclosed in Patent Document 1 performs a fuel injection operation of an input target fuel injection amount by lowering the valve element of a solenoid valve toward a closed position within a bouncing period before the valve element finishes bouncing from a fully open position. The fuel injection valve control device disclosed in Patent Document 1 can inject a small amount of fuel with higher accuracy than when the valve element is moved to the closed position after the valve element has reached a stable open state.

[0003] Japanese Patent Application Laid-Open No. 2017-137785

[0004] Incidentally, electromagnetic valve drive devices such as the fuel injection valve control device disclosed in Patent Document 1 may include a valve-closing detection unit that detects valve-closing timing to suppress errors caused by individual differences in fuel injection valves, aging, etc. Such electromagnetic valve drive devices, for example, detect the actual valve-closing timing using the valve-closing detection unit and determine the difference between the actual valve-closing timing and the controlled valve-closing timing. The electromagnetic valve drive device corrects the energization period of the coil of the fuel injection valve so as to cancel the error in injection amount caused by this difference.

[0005] When the valve disc closes after reaching the stable open state as described above, the correction amount for the energization period is linearly related to the difference between the actual valve closing timing and the controlled valve closing timing. However, when control is performed to stop the energization of the coil during the period of movement due to the rebound of the valve section, including the valve disc, as in the bounce period of Patent Document 1, the difference between the actual valve closing timing and the controlled valve closing timing becomes nonlinear. Therefore, as with an injection mode in which the valve section closes after reaching the stable open state, if the energization period is corrected during the period of movement due to the rebound of the valve section, the fuel injection amount cannot be accurately controlled.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an electromagnetic valve drive device that controls a fuel injection valve, which makes it possible to appropriately correct the energization period in accordance with the actual valve closing timing, regardless of whether the injection mode is one in which energization to the coil is stopped after the valve portion reaches a stable open state, or one in which energization to the coil is stopped during the movement period caused by the valve portion bouncing back.

[0007] The present invention employs the following configuration as a means for solving the above problems.

[0008] A first aspect of the present invention is an electromagnetic valve drive device for controlling a fuel injection valve including a movable core that is pulled in a valve opening direction by energizing a coil, a valve portion that is moved in the valve opening direction as the movable core moves in the valve opening direction, and a biasing portion that biases the valve portion in a valve closing direction, the device comprising: a valve closing detection portion that detects a valve closing timing of the valve portion based on a coil voltage value that is a voltage value of the coil; a current conduction period correction portion that corrects a current conduction period to the coil based on the valve closing timing; and a current conduction control portion that controls current conduction to the coil based on the corrected current conduction period, The fuel injection valve can be controlled based on a first injection mode in which current is maintained to the coil even after movement due to rebound of the valve portion has stopped, and a second injection mode in which current is stopped to the coil during a period of movement due to rebound of the valve portion after the movable core, being moved in the valve opening direction, has come into contact with a stopper, and the current flow period correction unit corrects the current flow period in the first injection mode by using a linear relationship between the valve closing timing and a correction amount for the current flow period, and corrects the current flow period in the second injection mode based on a relationship between the valve closing timing and an actual current flow period during the period of movement due to rebound of the valve portion.

[0009] In a fuel injection valve controlled by the electromagnetic valve drive device of the present invention, when the movable core is moved toward the stopper, the valve portion in the closed state is moved in the valve-opening direction together with the movable core. When the movable core collides with the stopper, the valve portion separates from the movable core due to inertial force and is then biased by the biasing portion to bounce back in the valve-closing direction. When the bouncing valve portion collides with the movable core, the movable core moves slightly in the valve-closing direction and then moves again toward the stopper. As a result, the valve portion moves back and forth in the valve-closing and valve-opening directions. In other words, the valve portion continues to move from the time the movable core abuts the stopper until the reciprocating movement converges (the period of movement due to the bouncing of the valve portion). In contrast, the electromagnetic valve drive device of the present invention can control the fuel injection valve in a first injection mode in which current is maintained to the coil even after the bouncing movement of the valve portion stops after the movable core, which is moving in the valve-opening direction, abuts the stopper. In the first injection mode, the electromagnetic valve drive device of the present invention corrects the energization period by establishing a linear relationship between the valve closing timing and the correction amount for the energization period. The electromagnetic valve drive device of the present invention can also control the fuel injection valve in a second injection mode in which energization to the coil is stopped during a period of movement due to rebound of the valve portion after the movable core, moving in the valve opening direction, contacts the stopper. In the second injection mode, the electromagnetic valve drive device of the present invention corrects the energization period based on the relationship between the valve closing timing and the actual energization period during the period of movement due to rebound of the valve portion. In other words, the present invention corrects the energization period using different correction methods in the first injection mode and the second injection mode. Therefore, in the electromagnetic valve drive device for controlling the fuel injection valve, the present invention makes it possible to appropriately correct the energization period according to the actual valve closing timing in both the injection mode in which energization to the coil is stopped after the valve portion reaches a stable open state and the injection mode in which energization to the coil is stopped during the period of movement due to rebound of the valve portion.

[0010] FIG. 1 is a schematic diagram showing a schematic configuration of a fuel injection valve controlled by a solenoid valve drive device of a first embodiment of the present invention. FIG. 2 is a schematic diagram showing the operation of a fuel injection valve of a fuel injection valve controlled by the solenoid valve drive device of a first embodiment of the present invention. FIG. 3 is a schematic diagram showing the operation of a fuel injection valve of a fuel injection valve controlled by the solenoid valve drive device of a first embodiment of the present invention. FIG. 4 is a schematic diagram showing the operation of a fuel injection valve of a fuel injection valve controlled by the solenoid valve drive device of a first embodiment of the present invention. FIG. 5 is a schematic diagram showing the operation of a fuel injection valve of a fuel injection valve controlled by the solenoid valve drive device of a first embodiment of the present invention. FIG. 6 is a schematic diagram showing the operation of a fuel injection valve of a fuel injection valve controlled by the solenoid valve drive device of a first embodiment of the present invention.

[0011] 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.

[0012] (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 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.

[0013] 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 (stopper), a valve seat 102, a solenoid coil 103 (coil), a needle 104, a valve body 105, a retainer 106, a lower stopper 107, a valve body biasing spring 108 (biasing portion), 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.

[0014] The fixed core 101 is a cylindrical member that is fixed to a housing (not shown) of the fuel injection valve 100. The fixed core 101 is made of a magnetic material. The fixed core 101 functions as a stopper that restricts the movement of the movable core 109 that is attracted by the solenoid coil 103.

[0015] 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 body 105 is seated on the valve seat 102, and is opened when the valve body 105 is separated from the valve seat 102.

[0016] 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.

[0017] 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.

[0018] There are no particular limitations 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 the valve-opening direction, 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 the valve-closing direction.

[0019] The valve element 105 is formed at the tip of the needle 104 in the valve closing direction. The valve element 105 closes the injection hole 102a by seating on the valve seat 102, and opens the injection hole 102a by moving away 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 tip of the needle 104 in the valve opening direction. The flange 106b is formed at the end of the guide member 106a in the valve opening direction so as to protrude in the radial direction of the needle 104. The end face of the flange 106b in the valve closing direction is an abutment surface with the movable core biasing spring 110. The end face of the flange 106b in the valve opening direction is an abutment surface with the valve element biasing spring 108.

[0020] The lower stopper 107 is a cylindrical member fixed to the needle 104 between the valve seat 102 and the guide member 106a. The lower stopper 107 has an end face in the valve opening direction that abuts against the movable core 109.

[0021] 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 in the valve closing direction. 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.

[0022] 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 end face of the movable core 109 in the valve opening direction is an abutment surface with the fixed core 101 and the movable core biasing spring 110. On the other hand, the end face of the movable core 109 in the valve closing direction is an abutment surface with the lower stopper 107. The movable core 109 is formed of a magnetic material.

[0023] 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 in the valve closing direction. That is, when the solenoid coil 103 is not energized, the movable core 109 is brought into contact with the lower stopper 107 by the biasing force of the movable core biasing spring 110.

[0024] In this embodiment, the needle 104, the valve body 105, and the retainer 106 are moved integrally by energizing the solenoid coil 103. The needle 104, the valve body 105, and the retainer 106, which are integrated together, form a valve portion 120. That is, in this embodiment, the valve portion 120, which has the valve body 105, is moved in the valve opening direction by energizing the solenoid coil 103.

[0025] The fuel injection valve 100 is controlled by the electromagnetic valve drive device 1 of this embodiment based on three injection modes: a first injection mode, a second injection mode, and a third injection mode, which will be described later.

[0026] The first injection mode is an injection mode in which current is maintained to the solenoid coil 103 even after the movable core 109, which is moved in the valve opening direction from the closed valve state (a state in which the valve body 105 abuts against the valve seat 102 and closes the injection hole 102a), abuts against the fixed core 101 and the movement of the valve portion 120 due to bouncing stops.

[0027] The first injection mode will be described in more detail with reference to Figures 2 to 6. Figures 2 to 6 are schematic diagrams showing the operation of the fuel injection valve 100. In the first injection mode, when the solenoid coil 103 is energized in the valve-closed state shown in Figure 1, the movable core 109 is moved in the valve-opening direction as shown in Figure 2. Thereafter, as shown in Figure 3, the movable core 109 abuts against the retainer 106 from the valve-closing direction. When the movable core 109 is further moved in the valve-opening direction, the valve portion 120 is moved in the valve-opening direction.

[0028] 4, when the movable core 109 collides with the fixed core 101, the movement of the movable core 109 is stopped. Meanwhile, the valve portion 120 continues to move in the valve opening direction due to inertial force, and overshoots to a position where the retainer 106 moves away from the movable core 109 in the valve opening direction.

[0029] The overshooting valve portion 120 rebounds in the valve closing direction due to the biasing force of the valve body biasing spring 108, and abuts against the movable core 109 from the valve opening direction, as shown in Figure 5. As shown in Figure 5, the impact force generated when the valve portion 120 collides with the movable core 109 causes the movable core 109 to move slightly away from the fixed core 101 in the valve closing direction.

[0030] The movable core 109, which is slightly separated from the fixed core 101 in the valve closing direction, is again drawn in the valve opening direction and abuts against the fixed core 101 because the solenoid coil 103 is energized. Thereafter, as shown in Figure 6, the movable core 109 abuts against the fixed core 101, and the valve portion 120 is stabilized in abutment against the movable core 109.

[0031] In this way, the valve portion 120 continues to move back and forth due to the bouncing until it reaches the stable state shown in Fig. 6. The number of times that the valve portion 120 repeats the bouncing back and forth movement may be one or more.

[0032] As shown in FIG. 6, the first injection mode is an injection mode in which the solenoid coil 103 remains energized for a certain period of time even after the valve portion 120 has stopped moving due to bouncing and stabilized, thereby keeping the valve portion 120 in an open state for a long period of time.

[0033] The second injection mode is an injection mode in which current supply to the solenoid coil 103 is stopped during the period of movement due to the rebound of the valve portion 120 after the movable core 109, which is moved from the valve closed state in the valve opening direction, abuts against the fixed core 101. In this second injection mode, the valve opening period is shorter than in the first injection mode, and the fuel injection amount is smaller than in the first injection mode.

[0034] In the second injection mode, the supply of current to the solenoid coil 103 is stopped during the reciprocating movement of the valve portion 120 due to rebounding as described in the first injection mode (for example, the states shown in Figures 4 and 5). Note that the second injection mode is entered if the supply of current to the solenoid coil 103 is stopped after the movable core 109 collides with the fixed core 101 from the valve closed state until the movement of the valve portion 120 due to rebounding stops.

[0035] The third injection mode is an injection mode in which the supply of current to the solenoid coil 103 is stopped before the movable core 109, which is moved from the valve closed state in the valve opening direction, abuts against the fixed core 101. The third injection mode has a shorter valve opening period than the first and second injection modes, and is the injection mode in which the fuel injection amount is the smallest among the three injection modes.

[0036] Next, the electromagnetic valve driving device 1 according to this embodiment will be described. Fig. 7 is a schematic diagram of the electromagnetic valve driving device 1 according to this embodiment. As shown in Fig. 7, the electromagnetic valve driving device 1 includes a driving device 2 and a control device 3.

[0037] 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. 7 , 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.

[0038] The power supply device 2a may energize the solenoid coil 103 by outputting a battery voltage to the solenoid coil 103. The power supply device 2a may 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 the control device 3. In addition, the energization of the solenoid coil 103 is controlled by the control device 3.

[0039] 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.

[0040] 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.

[0041] The control processing unit 3b includes a valve closing detection unit 3c, a current supply control unit 3d, a current supply period correction unit 3e, and a memory unit 3f. The valve closing detection unit 3c detects the closure of the valve element 105. That is, the valve closing detection unit 3c detects the valve closing timing 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 closure of the fuel injection valve 100 based on the coil voltage value. The valve closing timing indicates the time at which the valve closing is detected, assuming that the time at which the solenoid coil 103 starts to be energized is set to 0. That is, the valve closing timing here is the elapsed time from the start of energization of the solenoid coil 103 to the detection of valve closure.

[0042] 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.

[0043] The current supply control unit 3d controls the power supply device 2a. The current supply control unit 3d controls the switch 2b to an on state or an off state. When the current supply control unit 3d controls the switch 2b to an on state, current is supplied to the solenoid coil 103. When the current supply control unit 3d controls the switch 2b to an off state, current is stopped from being supplied to the solenoid coil 103. The current supply control unit 3d controls the current supply period based on a program stored in the memory unit 3f and a post-stage corrected current supply period obtained by a current supply period correction unit 3e (described later).

[0044] The electromagnetic valve drive device 1 controls the fuel injection valve 100 based on a cycle period set for the fuel injection valve 100 to perform one fuel injection. Specifically, the cycle period is repeated continuously over time. The electromagnetic valve drive device 1 causes the fuel injection valve 100 to inject fuel for each cycle period. Note that the electromagnetic valve drive device 1 can also control the fuel injection valve 100 not to inject fuel during one cycle period.

[0045] The solenoid valve drive device 1 controls the flow rate of fuel injected from the fuel injection valve 100 by controlling the energization period for each cycle period that is repeated over time. One energization period indicates the period during which current is supplied to the solenoid coil 103 in one cycle period. The energization period is the time from when current begins to be supplied to the solenoid coil 103 at the energization start time to when the current is stopped. The control device 3 controls the amount of fuel injected from the fuel injection valve 100 (fuel injection amount) by controlling this energization period.

[0046] The electromagnetic valve drive device 1 of this embodiment performs multi-stage injection control, for example, 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, the fuel injection valve 100 performs two fuel injections in one combustion cycle. In other words, one combustion cycle includes two cycle periods. However, the number of fuel injections in one combustion cycle can be changed. For example, 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.

[0047] The current conduction period correction unit 3e corrects the current conduction period based on, for example, a correction amount map M stored in the memory unit 3f. The current conduction period correction unit 3e references the correction amount map M and determines the correction amount based on, for example, the valve closing timing. The current conduction period correction unit 3e corrects the current conduction period by adding this correction amount to the current conduction period corresponding to the fuel injection amount input from a higher-level control device or the like. In addition, in this embodiment, when the fuel injection valve 100 is controlled in the second injection mode, the current conduction period correction unit 3e determines the second injection mode correction amount from the current conduction period correction amount determined from the correction amount map M using the coefficient map Mk stored in the memory unit 3f.

[0048] Furthermore, the current conduction period correction unit 3e corrects the current conduction period based on the calculated correction amount. The corrected current conduction period is input to the current conduction control unit 3d. The current conduction control unit 3d conducts current to the solenoid coil 103 based on the corrected current conduction period.

[0049] The storage unit 3f stores the above-mentioned correction amount map M. The correction amount map M is a map showing the relationship between the difference between the actual valve closing timing detected by the valve closing detection unit 3c and the controlled valve closing timing, and the correction amount for the energization period. The controlled valve closing timing is the valve closing timing based on the energization period corresponding to the fuel injection amount input from a host control device or the like of the solenoid valve drive device 1. In the correction amount map M, the correction amount is set so that the error in the injection amount due to the difference between the actual valve closing timing and the controlled valve closing timing (valve closing time difference) is canceled. In this correction amount map M, the valve closing time difference and the correction amount for the energization period have a linear relationship.

[0050] However, in the second injection mode, it may be difficult to sufficiently reduce the error in the injection amount using the correction amount map M in which the valve closing time difference and the current conduction period correction amount have a linear relationship. Figure 8 is a graph showing the relationship between the current conduction period Ti and the valve closing timing Toff of a certain fuel injection valve 100. As described above, the second injection mode is an injection mode in which the injection period (current conduction period) is shorter than that of the first injection mode and longer than that of the third injection mode. In Figure 8, the current conduction period Ti between the current conduction period Ti1 and the current conduction period Ti2 corresponds to the second injection mode, the current conduction period Ti is longer than that of the current conduction period Ti2 corresponds to the first injection mode, and the current conduction period Ti is shorter than that of the current conduction period Ti1 corresponds to the third injection mode.

[0051] 8, during the current conduction period Ti in the first injection mode, the relationship between the current conduction period Ti and the valve closing timing Toff is linear. On the other hand, during the current conduction period Ti in the second injection mode, the relationship between the current conduction period Ti and the valve closing timing Toff is nonlinear. During such current conduction period Ti in the second injection mode, the valve unit 120 is moving and the position of the valve unit 120 is unstable. Therefore, the correction amount map M, in which the valve closing time difference and the correction amount for the current conduction period have a linear relationship, may not be able to sufficiently correct the injection amount error.

[0052] In order to further reduce the error in the fuel injection amount in the second injection mode as described above, the memory unit 3f stores a coefficient map Mk. The coefficient map Mk is a map in which the current application period Ti is associated with a coefficient for further reducing the error in the fuel injection amount. These coefficients are multiplied by the correction amount calculated by the correction amount map M to reduce the error in the fuel injection amount.

[0053] Specifically, to determine the coefficient, first, the relationship between the energization period Ti from the energization period Ti1 to the energization period Ti2 of the fuel injector 100 to be controlled and the actual valve closing timing Toff (actual valve closing timing) is obtained by experiment or simulation. This relationship represents the characteristic of the fuel injector 100 from the energization period Ti1 to the energization period Ti2 (hereinafter referred to as the reference characteristic). The coefficient is the reciprocal of the slope of a graph based on this reference characteristic (a graph showing the relationship between the energization period Ti and the valve closing timing Toff as shown in FIG. 8). In this way, the coefficient is determined. Note that the memory unit 3f stores the correction amount map M, the coefficient map Mk, as well as a drive control program for the fuel injector 100 and various calculated values.

[0054] In the electromagnetic valve drive device 1 of this embodiment as described above, when the fuel injection valve 100 is controlled in the first injection mode (when the current conduction period Ti is longer than the current conduction period Ti2), the current conduction period correction unit 3e corrects the current conduction period by adding the correction amount indicated in the correction amount map M to the current conduction period corresponding to the fuel injection amount input from a higher-level control device or the like.

[0055] Furthermore, when the fuel injection valve 100 is controlled in the second injection mode (when the current conduction period Ti is from the current conduction period Ti1 to the current conduction period Ti2), the current conduction period correction unit 3e acquires a correction amount from the correction amount map M based on the current conduction period corresponding to the fuel injection amount input from a higher-level control device, etc. Furthermore, the current conduction period correction unit 3e obtains a second injection mode correction amount by multiplying the acquired correction amount by a coefficient corresponding to the current conduction period corresponding to the fuel injection amount input from a higher-level control device, etc. Furthermore, the current conduction period correction unit 3e corrects the current conduction period by adding the second injection mode correction amount to the current conduction period corresponding to the fuel injection amount input from a higher-level control device, etc.

[0056] The fuel injection valve 100 controlled by the electromagnetic valve drive device 1 of this embodiment as described above includes a movable core 109, a valve portion 120, and a valve element biasing spring 108. The movable core 109 is pulled in the valve opening direction when current is applied to the solenoid coil 103. The valve portion 120 is moved in the valve opening direction in conjunction with the movement of the movable core 109 in the valve opening direction. The valve element biasing spring 108 biases the valve portion 120 in the valve closing direction.

[0057] The solenoid valve drive device 1 of this embodiment includes a valve closing detection unit 3c, a current conduction period correction unit 3e, and a current control unit 3d. The valve closing detection unit 3c detects the valve closing timing of the valve unit 120 based on a coil voltage value, which is the voltage value of the solenoid coil 103. The current conduction period correction unit 3e corrects the current conduction period to the solenoid coil 103 based on the valve closing timing. The current conduction control unit 3d controls the current conduction to the solenoid coil 103 based on the corrected current conduction period.

[0058] The electromagnetic valve drive device 1 of this embodiment can control the fuel injection valve 100 based on a first injection mode and a second injection mode. The first injection mode is an injection mode in which current is maintained to the solenoid coil 103 even after the movable core 109, moving in the valve opening direction, stops moving due to rebound of the valve portion 120 after it abuts against the fixed core 101. The second injection mode is an injection mode in which current is stopped to the solenoid coil 103 during the period in which the movable core 109, moving in the valve opening direction, abuts against a stopper and the valve portion 120 stops moving due to rebound.

[0059] In the first injection mode, the current conduction period correction unit 3e corrects the current conduction period based on a linear relationship between the valve closing timing and the correction amount of the current conduction period, and in the second injection mode, the current conduction period correction unit 3e corrects the current conduction period based on the relationship between the valve closing timing and the actual current conduction period during the movement period due to the rebound of the valve portion 120.

[0060] In the fuel injection valve 100 controlled by the electromagnetic valve drive device 1 of this embodiment, the valve portion 120 in the valve-closed state is moved in the valve-opening direction together with the movable core 109 as the movable core 109 moves toward the stopper. When the movable core 109 collides with the stopper, the valve portion 120 separates from the movable core 109 due to inertial force and then bounces back in the valve-closing direction as it is urged by the valve body biasing spring 108. When the rebounded valve portion 120 collides with the movable core 109, the movable core 109 moves slightly in the valve-closing direction and then moves again toward the fixed core 101. As a result, the valve portion 120 reciprocates in the valve-closing direction and the valve-opening direction. In other words, the valve portion 120 continues to move during the period from when the movable core 109 abuts against the stopper until the reciprocating movement converges (the movement period due to the rebound of the valve portion 120).

[0061] In contrast, the electromagnetic valve drive device 1 of this embodiment can control the fuel injection valve 100 in a first injection mode in which current is maintained to the solenoid coil 103 even after the movable core 109, which is being moved in the valve opening direction, stops moving due to the rebound of the valve portion 120 after it comes into contact with the fixed core 101. In this first injection mode, the electromagnetic valve drive device 1 of this embodiment corrects the current supply period using a linear relationship between the valve closing timing and the correction amount for the current supply period.

[0062] Furthermore, the electromagnetic valve drive device 1 of this embodiment can control the fuel injection valve 100 in a second injection mode in which the supply of current to the solenoid coil 103 is stopped during the period of movement caused by the rebound of the valve portion 120 after the movable core 109, which is moved in the valve opening direction, abuts against the stopper. In such a second injection mode, the electromagnetic valve drive device 1 of this embodiment corrects the energization period based on the relationship between the valve closing timing and the actual energization period during the period of movement caused by the rebound of the valve portion 120.

[0063] In other words, the electromagnetic valve drive device 1 of this embodiment corrects the energization period using different correction methods in the first injection mode and the second injection mode. Therefore, the electromagnetic valve drive device 1 of this embodiment can appropriately correct the energization period in accordance with the actual valve closing timing in either injection mode, that is, the injection mode in which energization to the solenoid coil 103 is stopped after the valve portion 120 has reached a stable valve open state, or the injection mode in which energization to the solenoid coil 103 is stopped during the period of movement due to the valve portion 120 bouncing.

[0064] In the solenoid valve drive device 1 of this embodiment, in the second injection mode, the current supply period correction unit 3e calculates the second injection mode correction amount by multiplying the correction amount calculated based on the linear relationship between the valve closing timing and the current supply period by a coefficient determined based on the relationship between the valve closing timing and the actual current supply period. The current supply period correction unit 3e also corrects the current supply period based on the second injection mode correction amount.

[0065] The coefficients differ depending on the fuel injection valve 100 to be driven. In other words, the coefficients are determined according to the individual characteristics (the reference characteristics described above) of the fuel injection valve 100. Such coefficients can be determined in advance through experiments or simulations. Therefore, by using the coefficients to determine the second injection mode correction amount and correcting the energization period based on this second injection mode correction amount, the energization period can be corrected in the second injection mode without performing complex calculations. Therefore, the solenoid valve drive device 1 of this embodiment can reduce the calculation load of the energization period correction unit 3e.

[0066] In the electromagnetic valve drive device 1 of this embodiment, the coefficient is the reciprocal of the slope of a graph based on a reference characteristic that indicates the relationship between the valve closing timing and the actual energization period during the movement period due to the rebound of the valve portion 120.

[0067] By using such coefficients, it becomes possible to control the injection amount more accurately than when correcting the power supply period in the second injection mode using only the correction amount map M in which the power supply period and the correction amount have a linear relationship.

[0068] In addition, the present embodiment includes a storage unit 3f that stores a coefficient map Mk that indicates the relationship between the coefficient and the current-flow period. The electromagnetic valve drive device 1 of the present embodiment can reduce the time required to read the coefficient into the current-flow period correction unit 3e, compared to when the coefficient map Mk is stored in an external device, for example.

[0069] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 9. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0070] 9 is a schematic diagram of the electromagnetic valve drive device 1A according to this embodiment. As shown in FIG. 9, the storage unit 3f of the electromagnetic valve drive device 1A stores a second injection mode correction amount calculation map Md. The second injection mode correction amount calculation map Md is a map showing the relationship (reference characteristic) between the valve closing timing and the actual energization period during the movement period due to the rebound of the valve portion 120 (i.e., the second injection mode).

[0071] The second injection mode correction amount calculation map Md can be created, for example, by swapping the vertical and horizontal axes of the range from the current conduction period Ti1 to the current conduction period Ti2 of the reference characteristic shown in Figure 8 above, and using the actual current conduction period as the correction reference current conduction period. That is, in the second injection mode correction amount calculation map Md, the horizontal axis represents the valve closing timing, and the vertical axis represents the correction reference current conduction period. The correction reference current conduction period differs from the actual current conduction period only in name, but has the same value as the actual current conduction period.

[0072] In the second injection mode, the current conduction period correction unit 3e corrects the current conduction period using a second injection mode correction amount calculation map Md that indicates the reference characteristics of the fuel injection valve 100. Specifically, the current conduction period correction unit 3e calculates the difference between the correction reference current conduction period (i.e., the actual current conduction period) at the valve closing timing detected by the valve closing detection unit 3c and the current conduction period when the valve closing timing is detected. The current conduction period correction unit 3e uses this difference as a correction amount and corrects the current conduction period by adding the calculated correction amount to the current conduction period corresponding to the fuel injection amount input from a higher-level control device or the like.

[0073] In the solenoid valve drive device 1A of this embodiment as described above, in the second injection mode, the current conduction period correction unit 3e calculates the difference between the actual current conduction period and the current conduction period at the valve closing timing detected by the valve closing detection unit 3c based on the reference characteristic, and further corrects the current conduction period based on the difference.

[0074] According to the electromagnetic valve drive device 1A of this embodiment, the energization period can be corrected in the second injection mode without performing complex calculations, thereby reducing the calculation load on the energization period correction unit 3e.

[0075] Furthermore, in the electromagnetic valve drive device 1A of this embodiment, the storage unit 3f stores a second injection mode correction amount calculation map Md. The electromagnetic valve drive device 1A of this embodiment can correct the energization period in a shorter time than, for example, when the second injection mode correction amount calculation map Md is stored in an external device.

[0076] 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.

[0077] In the above embodiment, the configuration in which the current supply period in the second injection mode is corrected using the coefficient map Mk and the second injection mode correction amount calculation map Md has been described. However, the present invention is not limited to this. The present invention may be modified so that the characteristics of the fuel injector 100 in the second injection mode are acquired in advance, and the injection amount error in the second injection mode may be reduced using a method different from that used in the first injection mode based on the characteristics acquired in advance.

[0078] The above embodiment can also be described as follows, for example:

[0079] (Supplementary Note 1) An electromagnetic valve drive device for controlling a fuel injection valve including a movable core that is pulled in a valve opening direction by energizing a coil, a valve portion that is moved in the valve opening direction as the movable core moves in the valve opening direction, and a biasing portion that biases the valve portion in a valve closing direction, the device comprising: a valve closing detection portion that detects a valve closing timing of the valve portion based on a coil voltage value that is a voltage value of the coil; an energization period correction portion that corrects an energization period to the coil based on the valve closing timing; and an energization control portion that controls energization to the coil based on the corrected energization period, and the fuel injection valve can be controlled based on a first injection mode in which energization to the coil is maintained even after the movable core moved in the valve opening direction has stopped moving due to rebounding after abutting a stopper, and a second injection mode in which energization to the coil is stopped during a period in which the movable core moved in the valve opening direction has stopped moving due to rebounding after abutting a stopper, and the energization period correction portion in the first injection mode, the energization period is corrected based on a linear relationship between the valve closing timing and a correction amount for the energization period, and in the second injection mode, the energization period is corrected based on a relationship between the valve closing timing and an actual energization period during the movement period due to bouncing of the valve portion.

[0080] (Supplementary Note 2) In the second injection mode, the current supply period correction unit obtains a second injection mode correction amount by multiplying the correction amount obtained by linearly determining the correction amount for the valve closing timing and the current supply period by a coefficient determined based on a relationship between the valve closing timing and the actual current supply period, and corrects the current supply period based on the second injection mode correction amount.

[0081] (Supplementary Note 3) The electromagnetic valve drive device according to Supplementary Note 2, wherein the coefficient is an inverse of a slope of a graph based on a reference characteristic that indicates a relationship between the valve closing timing and the actual energization period during the movement period due to rebound of the valve portion.

[0082] (Supplementary Note 4) The electromagnetic valve drive device according to Supplementary Note 3, further comprising a storage unit that stores a coefficient map that indicates a relationship between the coefficient and the energization period.

[0083] (Supplementary Note 5) The solenoid valve drive device according to Supplementary Note 1, wherein in the second injection mode, the current supply period correction unit determines a difference between the actual current supply period and the actual valve closing period at the valve closing timing detected by the valve closing detection unit based on a reference characteristic indicating a relationship between the valve closing timing and the actual current supply period during the movement period due to rebound of the valve unit, and corrects the current supply period based on the difference.

[0084] (Supplementary Note 6) The electromagnetic valve drive device according to Supplementary Note 5, further comprising a storage unit configured to store a second injection mode correction amount calculation map indicating a relationship between the valve closing timing and the actual energization period during the movement period due to rebound of the valve portion.

[0085] REFERENCE SIGNS LIST 1 Electromagnetic valve drive device 1A Electromagnetic valve drive device 2 Drive device 3 Control device 3a Voltage detection unit 3b Control processing unit 3c Valve closing detection unit 3d Current supply control unit 3e Current supply period correction unit 3f Memory unit 100 Fuel injection valve 101 Fixed core (stopper) 102 Valve seat 103 Solenoid coil (coil) 104 Needle 105 Valve body 106 Retainer 107 Lower stopper 108 Valve body biasing spring (biasing unit) 109 Movable core 110 Movable core biasing spring 120 Valve unit M Correction amount map Md Second injection mode correction amount calculation map Mk Coefficient map

Claims

1. A solenoid valve drive device for controlling a fuel injection valve including a movable core that is pulled in a valve opening direction by energizing a coil, a valve portion that is moved in the valve opening direction as the movable core moves in the valve opening direction, and a biasing portion that biases the valve portion in a valve closing direction, the device comprising: a valve closing detection portion that detects a valve closing timing of the valve portion based on a coil voltage value that is a voltage value of the coil; an energization period correction portion that corrects an energization period to the coil based on the valve closing timing; and an energization control portion that controls energization to the coil based on the corrected energization period, and is capable of controlling the fuel injection valve based on a first injection mode in which energization to the coil is maintained even after the movable core moved in the valve opening direction stops moving due to bouncing after it abuts against a stopper, and a second injection mode in which energization to the coil is stopped during a period of movement due to bouncing of the valve portion after the movable core moved in the valve opening direction abuts against a stopper, and the energization period correction portion the first injection mode corrects the energization period based on a linear relationship between the valve closing timing and a correction amount of the energization period, and the second injection mode corrects the energization period based on a relationship between the valve closing timing and an actual energization period during the movement period due to bouncing of the valve portion.

2. The solenoid valve drive device as claimed in claim 1, wherein, in the second injection mode, the current flow period correction unit obtains a correction amount for the second injection mode by multiplying the correction amount obtained by linearly determining the correction amount for the valve closing timing and the current flow period by a coefficient determined based on the relationship between the valve closing timing and the actual current flow period, and corrects the current flow period based on the correction amount for the second injection mode.

3. The solenoid valve drive device according to claim 2, wherein the coefficient is the reciprocal of a slope of a graph based on a reference characteristic showing the relationship between the valve closing timing and the actual energization period during the movement period due to the rebound of the valve portion.

4. The solenoid valve drive device according to claim 3, further comprising a storage unit that stores a coefficient map indicating the relationship between the coefficient and the energization period.

5. The solenoid valve drive device as described in claim 1, wherein, in the second injection mode, the current flow period correction unit determines a difference between the actual current flow period and the current flow period at the valve closing timing detected by the valve closing detection unit based on a reference characteristic indicating the relationship between the valve closing timing and the actual current flow period during the movement period due to bouncing of the valve portion, and corrects the current flow period based on the difference.

6. The solenoid valve drive device according to claim 5, further comprising a storage unit that stores a second injection mode correction amount calculation map that indicates the relationship between the valve closing timing and the actual current supply period during the movement period due to the rebound of the valve portion.

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