Electromagnetic valve drive device

Abstract

Provided is an electromagnetic valve drive device including: a drive circuit that drives a fuel injection valve by energizing a coil of the fuel injection valve; a valve closing detection unit that detects a valve closing timing of a valve body provided in the fuel injection valve on the basis of a coil voltage value that is a voltage value of the coil; and a failure detection unit that performs failure determination on the basis of the coil voltage value read by the valve closing detection unit.

Description

Solenoid valve drive unit

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

[0002] For example, Patent Document 1 discloses an internal combustion engine provided with a fuel injection control device. The fuel injection control device disclosed in Patent Document 1 controls a fuel injection valve that directly injects fuel into a combustion chamber. The fuel injection control device disclosed in Patent Document 1 also includes a valve element operation time detection unit that detects a valve element operation time of the fuel injection valve, and a fuel injection amount correction unit that corrects the fuel injection amount in accordance with information about the valve element operation time.

[0003] International Publication No. 2019 / 225076

[0004] However, in an electromagnetic valve drive device equipped with a valve-close detection unit that detects when the fuel injection valve is closed, such as the valve element operation time detection unit of Patent Document 1, if the valve-close detection unit or the fuel injection valve malfunctions, even if fuel injection is possible, optimal flow rate control may become difficult. For this reason, it is preferable to be able to detect malfunctions in the valve-close detection unit, etc.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to make it possible to determine a failure of a valve closure detection unit or the like in an electromagnetic valve drive device equipped with a valve closure detection unit.

[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 comprising: a drive circuit that drives a fuel injection valve by energizing a coil of the fuel injection valve; a valve closure detection unit that detects the valve closure timing of a valve body provided in the fuel injection valve based on a coil voltage value that is a voltage value of the coil; and a failure detection unit that makes a failure determination based on the coil voltage value read into the valve closure detection unit.

[0008] In the solenoid valve drive device of the present invention, the failure detection unit determines a failure based on the coil voltage value read into the valve close detection unit. The coil voltage value read into the valve close detection unit changes relative to the value in a normal state without a failure, for example, if a failure occurs in the drive circuit, the valve close detection unit, or the fuel injector. In other words, when a failure occurs, the coil voltage value read into the valve close detection unit becomes unstable. Therefore, the failure detection unit can determine whether a failure has occurred based on the coil voltage value read into the valve close detection unit. Therefore, the electromagnetic valve drive device of the present invention, which includes a valve close detection unit, can determine a failure in the valve close detection unit or the like.

[0009] 1 is a schematic diagram showing a schematic configuration of a fuel injection valve controlled by a solenoid valve drive device according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a solenoid valve drive device according to a first embodiment of the present invention. FIG. 3 is a timing chart showing the relationship between a coil voltage value, a count value of an abnormality monitoring counter, and a count value of an abnormality counter according to the first embodiment of the present invention. FIG. 4 is a timing chart showing the relationship between a count value of an abnormality monitoring counter, a count value of an abnormality counter, and a fault determination flag according to the first embodiment of the present invention. FIG. 5 is a timing chart showing the relationship between a coil voltage value, a count value of an abnormality monitoring counter, and a count value of an abnormality counter at a valve closing timing according to a third embodiment of the present invention. FIG. 6 is a timing chart showing the relationship between a coil voltage value, a count value of an abnormality monitoring counter, a count value of an abnormality counter, and a fault determination flag for a certain period after start-up of a drive device according to a fourth embodiment of the present invention. FIG. 7 is a flowchart showing a method of fault determination in a fault detection unit of a solenoid valve drive device according to a fifth embodiment of the present invention.

[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 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 (coil), 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 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.

[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 (drive circuit) 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 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.

[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 closure detection unit 3c, a current supply control unit 3d, a current supply period correction unit 3e, a memory unit 3f, and a failure detection unit 3g. The valve closure detection unit 3c detects the closure of the valve element 105. That is, the valve closure detection unit 3c detects the valve closure timing of the valve element 105 included in the fuel injection valve 100. The valve closure 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.

[0028] As an 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 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).

[0030] The solenoid valve drive device 1 controls the fuel injection valve 100 based on a cycle period Ts (see FIG. 3 ) set for the fuel injection valve 100 to perform one fuel injection. Specifically, the cycle period Ts is repeated continuously over time. The solenoid valve drive device 1 causes the fuel injection valve 100 to inject fuel for each cycle period Ts. Note that the solenoid valve drive device 1 can also control the fuel injection valve 100 not to inject fuel during one cycle period Ts.

[0031] 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 Ts 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 Ts. 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 supply 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.

[0032] 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 Ts. 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.

[0033] The current conduction period correction unit 3e corrects the current conduction period based on, for example, a correction amount map M stored in the storage unit 3f. The current conduction period correction unit 3e refers to the correction amount map M and obtains a correction amount based on, for example, the valve closing timing.

[0034] Furthermore, the current-carrying period correction unit 3e corrects the current-carrying period based on the calculated correction amount. The corrected current-carrying period is input to the current-carrying control unit 3d. The current-carrying control unit 3d supplies current to the solenoid coil 103 based on the corrected current-carrying period. In this embodiment, the current-carrying period correction unit 3e stops correcting the current-carrying period during a monitoring period Tk (see FIG. 4), which will be described later.

[0035] The memory 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 detected valve closing timing and the controlled valve closing timing, and the correction amount for the current supply period. In this embodiment, the memory unit 3f also stores a high-voltage threshold VH (see FIG. 3). The high-voltage threshold VH is a threshold set so that the coil voltage value exceeds the high-voltage threshold VH during the cycle period Ts when fuel is being injected normally. In other words, during normal fuel injection, the coil voltage exceeds the high-voltage threshold VH during the cycle period Ts. The memory unit 3f also stores a drive control program for the fuel injection valve 100 and various calculated values.

[0036] The failure detection unit 3g performs a failure determination based on the coil voltage value read by the valve closure detection unit 3c. In this embodiment, the failure detection unit 3g determines an abnormality when the coil voltage value does not exceed the high-voltage threshold VH during the cycle period Ts. On the other hand, the failure detection unit 3g determines a normality when the coil voltage value exceeds the high-voltage threshold VH during the cycle period Ts. When the failure detection unit 3g determines an abnormality, it increments the count value of the abnormality counter by one. When the failure detection unit 3g determines a normality, it maintains the count value of the abnormality counter.

[0037] For example, the failure detection unit 3g sets a flag when the coil voltage value exceeds the high-voltage threshold VH. Furthermore, if the flag is not set when the cycle period Ts ends or when the coil voltage value becomes zero, the failure detection unit 3g determines that an abnormality has occurred.

[0038] When increasing the count value of the abnormality counter, the failure detection unit 3g may increase the count value of the abnormality counter, for example, when the cycle period Ts ends. Alternatively, the failure detection unit 3g may increase the count value of the abnormality counter, for example, when the coil voltage value becomes zero.

[0039] Furthermore, the failure detection unit 3g performs failure determination based on the count value of the abnormality determined as described above (count value of the abnormality counter). Specifically, the failure detection unit 3g determines that a failure has occurred when the count value of the abnormality counter exceeds a failure determination value Cx (see FIG. 4). For example, when the count value of the abnormality counter exceeds the failure determination value Cx, the failure detection unit 3g sets a failure confirmation flag and determines that a failure has occurred. The failure determination value Cx is set in advance based on experiments and simulations and is stored in the storage unit 3f.

[0040] In this embodiment, when an abnormality occurs while the count value of the abnormality counter is zero, the failure detection unit 3g starts counting a predetermined monitoring period Tk (see FIG. 4). For example, when an abnormality occurs while the count value of the abnormality counter is zero, the failure detection unit 3g starts incrementing the count value of the abnormality monitoring counter. The failure detection unit 3g increments the count value of the abnormality monitoring counter every cycle period Ts, and the period until this count value reaches an upper limit value Cmax (see FIG. 4) is defined as the monitoring period Tk. The upper limit value Cmax is set in advance based on experiments and simulations and is stored in the storage unit 3f.

[0041] When the monitoring period Tk has elapsed, the failure detection unit 3g resets the count value of the abnormality counter to zero. In other words, when the count value of the abnormality counter does not exceed the failure determination value Cx during the monitoring period Tk, the failure detection unit 3g resets the count value of the abnormality counter to zero.

[0042] In this way, the fault detection unit 3g determines that a fault has occurred if the count value of the abnormality counter exceeds a predetermined fault determination value Cx during the monitoring period Tk, which is the period that begins after determining that an abnormality has occurred when the count value of the abnormality counter is zero.

[0043] In the solenoid valve drive device 1 of this embodiment, the energization control unit 3d of the control device 3 controls the switch 2b of the drive device 2, thereby controlling the energization period of the solenoid coil 103. When the solenoid coil 103 is energized, the valve body 105 of the fuel injection valve 100 opens the injection hole 102a, and fuel is injected from the fuel injection valve 100. The control device 3 detects the valve closing timing using the valve closing detection unit 3c based on the detection result (coil voltage value) of the voltage detection unit 3a. Furthermore, the control device 3 corrects the energization period based on the valve closing timing as necessary.

[0044] Next, an example of the operation related to the failure determination of the solenoid valve drive device 1 of this embodiment will be described with reference to Figures 3 and 4. Figure 3 is a timing chart showing the relationship between the coil voltage value, the count value of the abnormality monitoring counter, and the count value of the abnormality counter. Figure 4 is a timing chart showing the relationship between the count value of the abnormality monitoring counter, the count value of the abnormality counter, and the failure determination flag.

[0045] The count value of the anomaly counter and the count value of the anomaly monitoring counter increase stepwise, by increasing by one for each cycle period Ts. However, in Fig. 4, because the width of the cycle period Ts is small, the count value of the anomaly counter and the count value of the anomaly monitoring counter are shown as if they are increasing continuously (i.e., as if the increasing portion is sloping).

[0046] 3, the coil voltage value changes during one cycle period Ts. In the case of normal injection, the coil voltage value increases when switch 2b is closed and decreases when switch 2b is opened. At this time, the coil voltage value increases beyond the high-voltage threshold VH and then decreases.

[0047] If the coil voltage value exceeds the high-voltage threshold VH during the cycle period Ts, the failure detection unit 3g does not change the count value of the abnormality counter. In other words, if the coil voltage value exceeds the high-voltage threshold VH during the cycle period Ts while the count value of the abnormality counter is zero, the count value of the abnormality counter is maintained at zero.

[0048] On the other hand, if the coil voltage value does not exceed the high-voltage threshold VH during the cycle period Ts, the failure detection unit 3g increments the count value of the abnormality counter by one. Furthermore, if the coil voltage value does not exceed the high-voltage threshold VH during the cycle period Ts while the count value of the abnormality counter is zero, the failure detection unit 3g also increments the count value of the abnormality monitoring counter. When the count value of the abnormality monitoring counter starts to increase, the failure detection unit 3g increments the count value of the abnormality monitoring counter every cycle period Ts until the count value of the abnormality monitoring counter exceeds the upper limit value Cmax, as shown in FIG. 4 . The period from when the count value of the abnormality monitoring counter starts to increase until it exceeds the upper limit value Cmax is the monitoring period Tk.

[0049] If the count value of the abnormality counter exceeds the abnormality determination value Cx before the monitoring period Tk has elapsed (i.e., before the count value of the abnormality monitoring counter exceeds the upper limit value Cmax), the failure detection unit 3g sets up a failure confirmation flag as shown in Fig. 4. In other words, if the count value of the abnormality counter exceeds the abnormality determination value Cx before the monitoring period Tk has elapsed, the failure detection unit 3g determines that a failure has occurred.

[0050] In contrast, if the count value of the abnormality counter does not exceed the abnormality determination value Cx before the monitoring period Tk has elapsed (i.e., before the count value of the abnormality monitoring counter exceeds the upper limit value Cmax), the failure detection unit 3g sets the count value of the abnormality counter to zero, as shown in Figure 4.

[0051] In this embodiment, if abnormalities occur frequently during the monitoring period Tk, the failure detection unit 3g determines that a failure has occurred. On the other hand, if the number of abnormalities occurring during the monitoring period Tk is small, the failure detection unit 3g sets the count value of the abnormality counter to zero, considering that this is an erroneous determination.

[0052] When the failure detection unit 3g determines that a failure has occurred, the control device 3 inputs a signal indicating this to a higher-level control device, thereby notifying, for example, the user of the vehicle of the possibility of a failure.

[0053] When the failure detection unit 3g determines that a failure has occurred, it is known that a failure has occurred in any of the fuel injection valve 100, the drive device 2, the voltage detection unit 3a, the valve closing detection unit 3c, and the current control unit 3d. Note that when a failure has occurred in the voltage detection unit 3a or the valve closing detection unit 3c, injection from the fuel injection valve 100 may be performed properly. In other words, the fact that the failure detection unit 3g has determined that a failure has occurred does not immediately mean that injection from the fuel injection valve 100 is inappropriate.

[0054] In this embodiment, the current-on period correction unit 3e stops correcting the current-on period during the monitoring period Tk (i.e., when the count value of the abnormality monitoring counter is not zero). A failure may have occurred during the monitoring period Tk. By stopping the correction of the current-on period during such a period when a failure may have occurred, it is possible to reduce the possibility that a failure will be determined to have occurred due to the correction of the current-on period.

[0055] The solenoid valve drive device 1 of this embodiment as described above includes the drive device 2, a valve closure detection unit 3c, and a failure detection unit 3g. The drive device 2 drives the fuel injection valve 100 by energizing the solenoid coil 103 of the fuel injection valve 100. The valve closure detection unit 3c detects the valve closure timing of the valve element 105 provided in the fuel injection valve 100 based on a coil voltage value, which is the voltage value of the solenoid coil 103. The failure detection unit 3g performs failure determination based on the coil voltage value read by the valve closure detection unit 3c.

[0056] In the solenoid valve drive device 1 of this embodiment, the failure detection unit 3g determines whether a failure has occurred based on the coil voltage value read into the valve closure detection unit 3c. For example, if a failure occurs in any of the drive device 2, the valve closure detection unit 3c, or the fuel injector 100, the coil voltage value read into the valve closure detection unit 3c changes relative to the value in a normal state where no failure has occurred. In other words, in a state where a failure has occurred, the coil voltage value read into the valve closure detection unit 3c becomes unstable. Therefore, the failure detection unit 3g can determine whether a failure has occurred based on the coil voltage value read into the valve closure detection unit 3c. Therefore, the solenoid valve drive device 1 of this embodiment can determine whether a failure has occurred in the valve closure detection unit 3c, etc.

[0057] Furthermore, in the solenoid valve drive device 1 of this embodiment, a high-voltage threshold VH is set. This high-voltage threshold VH is set so that the coil voltage value exceeds this during normal fuel injection during the cycle period Ts. The failure detection unit 3g determines that an abnormality has occurred if the coil voltage value does not exceed the high-voltage threshold VH during the cycle period Ts. Furthermore, the failure detection unit 3g performs the failure determination based on the abnormality count value.

[0058] The electromagnetic valve drive device 1 of this embodiment performs abnormality determination based on the high-voltage side threshold VH. The high-voltage side threshold VH is set to a value that the coil voltage value exceeds in the case of normal fuel injection. By using the high-voltage side threshold VH as the basis, the electromagnetic valve drive device 1 of this embodiment can easily and reliably perform failure determination.

[0059] Furthermore, in the electromagnetic valve drive device 1 of this embodiment, the failure detection unit 3g determines that a failure has occurred when the abnormality count value exceeds a predetermined failure determination value Cx during a monitoring period Tk. The monitoring period Tk is a fixed period that starts after determining that an abnormality has occurred when the abnormality count value is zero.

[0060] The electromagnetic valve drive device 1 of this embodiment determines that a failure has occurred if an abnormality occurs frequently during the monitoring period Tk. Therefore, the electromagnetic valve drive device 1 of this embodiment can prevent a malfunction due to a false detection of an abnormality that occurs singly for some reason.

[0061] Furthermore, in the electromagnetic valve driving device 1 of this embodiment, the failure detection unit 3g sets the abnormality count value to zero if the abnormality count value does not exceed the abnormality determination value Cx during the monitoring period Tk.

[0062] According to the electromagnetic valve drive device 1 of this embodiment, the abnormality count value becomes zero after the monitoring period Tk has elapsed. Therefore, the electromagnetic valve drive device 1 of this embodiment can determine that a malfunction has occurred only when a large number of abnormalities occur in a concentrated manner during the monitoring period Tk, which is a predetermined fixed period.

[0063] The electromagnetic valve drive device 1 of this embodiment also includes a current control unit 3d that sets a current-carrying period for the solenoid coil 103, and a current-carrying period correction unit 3e that corrects the current-carrying period. The current-carrying period correction unit 3e stops correcting the current-carrying period when the monitoring period Tk is reached.

[0064] In the solenoid valve drive device 1 of this embodiment, the current conduction period correction unit 3e stops correcting the current conduction period during the monitoring period Tk. By stopping the correction of the current conduction period during such a period in which a fault may have occurred, it is possible to reduce the possibility that a fault will be determined to have occurred as a result of the correction of the current conduction period.

[0065] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 5. Note that in this embodiment, descriptions of the same parts as those in the first embodiment will be omitted or simplified.

[0066] 5 is a timing chart showing the relationship between the coil voltage value, the count value of the abnormality monitoring counter, and the count value of the abnormality counter in this embodiment. The memory unit 3f stores a low-voltage threshold VL (see FIG. 5) in addition to the high-voltage threshold VH. The low-voltage threshold VL is set so that the coil voltage value falls below the high-voltage threshold VH during the same cycle period Ts during normal fuel injection.

[0067] In this embodiment, the failure detection unit 3g determines an abnormality when the coil voltage value does not decrease to the low-voltage threshold VL after exceeding the high-voltage threshold VH during the cycle period Ts. In other words, the failure detection unit 3g determines an abnormality when the coil voltage value does not fall below the low-voltage threshold VL within a predetermined period (cycle period Ts) after exceeding the high-voltage threshold VH. On the other hand, the failure detection unit 3g determines an abnormality when the coil voltage value decreases to the low-voltage threshold VL after exceeding the high-voltage threshold VH during the cycle period Ts.

[0068] For example, the failure detection unit 3g raises a flag when the coil voltage value exceeds the high-voltage threshold VH. Thereafter, the failure detection unit 3g lowers the flag when the coil voltage value falls to the low-voltage threshold VL. If the flag is not lowered at the end of the cycle period Ts or when the coil voltage value becomes zero, the failure detection unit 3g determines that an abnormality has occurred.

[0069] 5, if the coil voltage value exceeds the high-voltage threshold VH during cycle period Ts and then falls below the low-voltage threshold VL, the failure detection unit 3g does not change the count value of the abnormality counter. In other words, if the count value of the abnormality counter is zero and the coil voltage value exceeds the high-voltage threshold VH during cycle period Ts and then falls below the low-voltage threshold VL, the count value of the abnormality counter is maintained at zero.

[0070] On the other hand, if the coil voltage value exceeds the high-voltage threshold VH during the cycle period Ts but does not fall below the low-voltage threshold VL, the failure detection unit 3g increments the count value of the abnormality counter by 1. Furthermore, if the count value of the abnormality counter is zero and the coil voltage value exceeds the high-voltage threshold VH during the cycle period Ts but does not fall below the low-voltage threshold VL, the failure detection unit 3g also increments the count value of the abnormality monitoring counter. If the count value of the abnormality counter exceeds the failure determination value Cx before the monitoring period Tk has elapsed, the failure detection unit 3g determines that a failure has occurred.

[0071] In the present embodiment as described above, a high-voltage threshold VH and a low-voltage threshold VL are set. The low-voltage threshold VL is set so that, during normal fuel injection, the coil voltage value after exceeding the high-voltage threshold VH falls below this threshold during the same cycle period Ts. In the solenoid valve drive device 1 of this embodiment, the failure detection unit 3g determines that an abnormality has occurred if, during the cycle period Ts, the coil voltage value after exceeding the high-voltage threshold VH does not fall below the low-voltage threshold for a predetermined period. The failure detection unit 3g also performs the failure determination based on the abnormality count value.

[0072] The solenoid valve drive device 1 of this embodiment performs abnormality determination based on the high-voltage side threshold VH and the low-voltage side threshold VL. The high-voltage side threshold VH is set to a value that the coil voltage value exceeds during normal fuel injection. The low-voltage side threshold VL is set so that the coil voltage value, after exceeding the high-voltage side threshold VH during normal fuel injection, falls below this value during the same cycle period Ts. By using the high-voltage side threshold VH and the low-voltage side threshold VL as described above, the solenoid valve drive device 1 of this embodiment can easily and reliably perform failure determination.

[0073] Third Embodiment Next, a third embodiment of the present invention will be described with reference to Fig. 6. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0074] 6 is a timing chart showing the relationship between the coil voltage value at the valve closing timing, the count value of the abnormality monitoring counter, the count value of the abnormality counter, and the malfunction determination flag in this embodiment. The memory unit 3f stores a normal voltage value range VS1 at the valve closing timing. The normal voltage value range VS1 is preset to include a range in which the coil voltage value may exist at the valve closing timing in the case of normal fuel injection.

[0075] In this embodiment, the failure detection unit 3g determines an abnormality when the coil voltage value at the timing when the valve closure detection unit 3c detects valve closure is not within the normal voltage value range VS1 during the cycle period Ts. In other words, the failure detection unit 3g determines an abnormality when the coil voltage value at the valve closure timing is not within the predetermined normal voltage value range VS1. On the other hand, the failure detection unit 3g determines an abnormality when the coil voltage value at the valve closure timing is within the predetermined normal voltage value range VS1 during the cycle period Ts.

[0076] For example, the failure detection unit 3g sets a flag if the coil voltage value at the valve closing timing is not within a predetermined normal voltage range VS1. If the flag is set at the end timing of the cycle period Ts, the failure detection unit 3g determines that an abnormality has occurred.

[0077] 6, the failure detection unit 3g does not change the count value of the abnormality counter if the coil voltage value at the valve closing timing is within the normal voltage value range VS1. In other words, if the count value of the abnormality counter is zero and the coil voltage value at the valve closing timing is within the normal voltage value range VS1, the count value of the abnormality counter is maintained at zero.

[0078] On the other hand, if the coil voltage value at the valve closing timing is not within the normal voltage value range VS1, the failure detection unit 3g increments the count value of the abnormality counter by 1. Furthermore, if the count value of the abnormality counter is zero and the coil voltage value at the valve closing timing is not within the normal voltage value range VS1, the failure detection unit 3g also increments the count value of the abnormality monitoring counter. If the count value of the abnormality counter exceeds the failure determination value Cx before the monitoring period Tk has elapsed, the failure detection unit 3g determines that a failure has occurred.

[0079] In the present embodiment as described above, the normal voltage range VS1 at the valve closing timing is determined in advance. In the solenoid valve drive device 1 of this embodiment, the fault detection unit 3g determines that an abnormality has occurred if the coil voltage value is not within the normal voltage range VS1 at the valve closing timing. The fault detection unit 3g also performs the fault determination based on the abnormality count value.

[0080] The electromagnetic valve drive device 1 of this embodiment performs abnormality determination based on the normal voltage range VS1 at the valve closing timing. The normal voltage range VS1 at the valve closing timing is set so that the coil voltage value at the valve closing timing exists during normal fuel injection. By using the normal voltage range VS1 at the valve closing timing as described above, the electromagnetic valve drive device 1 of this embodiment can easily and reliably perform failure determination.

[0081] Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to Fig. 7. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0082] FIG. 7 is a timing chart showing the relationship between the coil voltage value, the count value of the abnormality monitoring counter, the count value of the abnormality counter, and the malfunction determination flag for a certain period after the start of the drive unit 2 in this embodiment. The memory unit 3f stores a normal voltage value range VS2 for a certain period after the start of the drive unit 2. For example, when the vehicle's ignition switch is turned on from an off state, the drive unit 2 is started and the internal combustion engine, to which fuel is supplied by the fuel injection valve 100, is started. In other words, the certain period after the start of the drive unit 2 (initial start period) is the initial operating period of the internal combustion engine. During this initial start period, fuel is injected from the fuel injection valve 100 at a predetermined injection amount, rather than fuel injection according to the accelerator operation of the vehicle. In this embodiment, this initial start period is used to determine a malfunction. The normal voltage value range VS2 is preset to include a range in which the coil voltage value may exist if fuel is injected normally during the initial start period.

[0083] In this embodiment, the failure detection unit 3g determines that an abnormality has occurred if the coil voltage value is not within the normal voltage value range VS2 during the initial startup period, whereas the failure detection unit 3g determines that an abnormality has occurred if the coil voltage value is within the preset normal voltage value range VS2 during the initial startup period.

[0084] For example, the failure detection unit 3g increases the count value of the abnormality monitoring counter when the initial startup period starts (when the ignition switch changes from an OFF state to an ON state). If the coil voltage value during this initial startup period is not within a predetermined normal voltage value range VS2, the failure detection unit 3g increases the count value of the abnormality counter.

[0085] 7, when the coil voltage value is within the normal voltage range VS2 during the initial startup period, the failure detection unit 3g does not change the count value of the abnormality counter. In other words, when the coil voltage value is within the normal voltage range VS2 during the initial startup period, the count value of the abnormality counter remains at zero.

[0086] On the other hand, the failure detection unit 3g increases the count value of the abnormality monitoring counter when the initial startup period begins (when the ignition switch changes from an OFF state to an ON state). If the coil voltage value is not within the normal voltage value range VS2 during the period in which the count value of the abnormality monitoring counter is being increased, the failure detection unit 3g also increases the count value of the abnormality monitoring counter even if the coil voltage value is not within the normal voltage value range VS2. If the count value of the abnormality counter exceeds the failure determination value Cx before the initial startup period has elapsed, the failure detection unit 3g determines that a failure has occurred.

[0087] In the present embodiment, the normal voltage range VS2 is predetermined for the initial start-up period. In the solenoid valve drive device 1 of this embodiment, the fault detection unit 3g determines that an abnormality has occurred if the coil voltage value is not within the normal voltage range VS2 during the initial start-up period. The fault detection unit 3g also determines that an abnormality has occurred based on the abnormality count value.

[0088] The solenoid valve drive device 1 of this embodiment performs abnormality determination based on the normal voltage range VS2 during the initial startup period. The normal voltage range VS2 during the initial startup period is set so that the coil voltage value exists during normal fuel injection. By using the normal voltage range VS2 during this initial startup period, the solenoid valve drive device 1 of this embodiment can easily and reliably perform failure determination.

[0089] Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to Fig. 8. Note that in this embodiment, descriptions of the same parts as those in the first to fourth embodiments will be omitted or simplified.

[0090] 8 is a flowchart showing a method of fault determination in the fault detection unit 3g of the electromagnetic valve drive device 1 of this embodiment. As shown in this figure, the fault detection unit 3g performs fault determination processing based on a first condition (step S1) and fault determination processing based on a second condition (step S2).

[0091] The abnormality determination process based on the first condition is, for example, a step of performing abnormality determination using any of the methods described in the first to fourth embodiments. That is, the failure detection unit 3g performs abnormality determination process based on the first condition using any of the following methods: the method of determining abnormality based on the coil voltage value and the high-voltage threshold value VH described in the first embodiment; the method of determining abnormality based on the coil voltage value and the high-voltage threshold value VH and the low-voltage threshold value VL described in the second embodiment; the method of determining abnormality based on the coil voltage value at the valve-closing timing and the normal voltage value range VS1 described in the third embodiment; and the method of determining abnormality based on the coil voltage value during the initial startup period and the normal voltage value range VS2 described in the fourth embodiment.

[0092] The abnormality determination process based on the second condition is a process of performing abnormality determination using, for example, one of the abnormality determination methods described in the first to fourth embodiments, which is not used in the abnormality determination process based on the first condition.

[0093] In the abnormality determination process based on the first condition, the failure detection unit 3g may perform only up to the abnormality determination or may perform only up to the failure determination. Similarly, in the abnormality determination process based on the second condition, the failure detection unit 3g may perform only up to the abnormality determination or may perform only up to the failure determination.

[0094] 8, the failure detection unit 3g of the electromagnetic valve drive device 1 of this embodiment determines whether or not an abnormality has been determined in both the abnormality determination process based on the first condition and the abnormality determination process based on the second condition (step S3). Note that step S3 may be a step of determining whether or not a failure has been determined in both the abnormality determination process based on the first condition and the abnormality determination process based on the second condition.

[0095] If an abnormality is determined in both the abnormality determination process based on the first condition and the abnormality determination process based on the second condition in step S3, the failure detection unit 3g confirms a failure (step S4). On the other hand, if an abnormality is determined in both or either of the abnormality determination process based on the first condition and the abnormality determination process based on the second condition, the failure detection unit 3g returns to step S1 again.

[0096] In the electromagnetic valve drive device 1 of this embodiment, the failure detection unit 3g determines whether or not there is an abnormality based on a plurality of conditions using the coil voltage value, and determines whether or not there is a malfunction if an abnormality is determined under a plurality of different conditions. The electromagnetic valve drive device 1 of this embodiment can more accurately detect a malfunction.

[0097] In this embodiment, a configuration has been described in which a malfunction is confirmed when an abnormality is determined in both the abnormality determination process based on the first condition and the abnormality determination process based on the second condition. However, the present invention may also employ a configuration in which, for example, malfunction determination processes are performed based on three or more conditions, and a malfunction is confirmed when an abnormality is determined in more than one of these malfunction determination processes.

[0098] 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.

[0099] For example, in the above embodiment, a configuration has been described in which a malfunction is determined when an abnormality occurs frequently during the monitoring period Tk. However, the present invention is not limited to this. For example, a malfunction may be determined when an abnormality is determined only once during the monitoring period Tk, or when a malfunction is determined only once without setting a monitoring period Tk.

[0100] The above embodiment can also be described as follows, for example:

[0101] (Supplementary Note 1) An electromagnetic valve drive device comprising: a drive circuit that drives a fuel injection valve by energizing a coil of the fuel injection valve; a valve close detection unit that detects a valve closing timing of a valve body included in the fuel injection valve based on a coil voltage value that is a voltage value of the coil; and a failure detection unit that makes a failure determination based on the coil voltage value read by the valve close detection unit.

[0102] (Supplementary Note 2) The electromagnetic valve drive device according to Supplementary Note 1, wherein a high voltage threshold is set so that the coil voltage value exceeds the high voltage threshold during normal fuel injection during a cycle period set for the fuel injection valve to perform one fuel injection, and the failure detection unit determines that an abnormality has occurred when the coil voltage value does not exceed the high voltage threshold during the cycle period, and performs the failure determination based on a count value of the abnormality.

[0103] (Supplementary Note 3) The solenoid valve drive device according to Supplementary Note 1, wherein a high-voltage side threshold is set so that the coil voltage value exceeds it during normal fuel injection during a cycle period set for the fuel injection valve to perform one fuel injection, and a low-voltage side threshold is set so that the coil voltage value after exceeding the high-voltage side threshold falls below it during the same cycle period during normal fuel injection, and the failure detection unit determines that an abnormality has occurred if the coil voltage value after exceeding the high-voltage side threshold does not fall below the low-voltage side threshold for a predetermined period during the cycle period, and makes the failure determination based on a count value of the abnormality.

[0104] (Supplementary Note 4) The electromagnetic valve drive device according to Supplementary Note 1, wherein the failure detection unit determines that an abnormality has occurred if the coil voltage value is not within a predetermined normal voltage value range at the valve closing timing, and performs the failure determination based on a count value of the abnormality.

[0105] (Supplementary Note 5) The solenoid valve drive device according to Supplementary Note 1, wherein the failure detection unit determines that an abnormality has occurred when the coil voltage value is not within a predetermined normal voltage value range within a predetermined period of time from the start of startup of the drive circuit, and performs the failure determination based on a count value of the abnormality.

[0106] (Supplementary Note 6) The electromagnetic valve drive device according to any one of Supplementary Notes 2 to 4, wherein the failure detection unit determines that a failure has occurred when the count value of the abnormality exceeds a predetermined failure determination value during a monitoring period that starts after determining that an abnormality has occurred while the count value of the abnormality is zero.

[0107] (Supplementary Note 7) The electromagnetic valve drive device according to any one of Supplementary Notes 2 to 6, wherein the failure detection unit sets the count value of the abnormality to zero when the count value of the abnormality does not exceed a predetermined failure determination value within a set period of time.

[0108] (Supplementary Note 8) The solenoid valve drive device according to Supplementary Note 6 or 7, further comprising: an energization control unit that sets an energization period for the coil; and an energization period correction unit that corrects the energization period, wherein the energization period correction unit stops correcting the energization period when the monitoring period is in progress.

[0109] (Supplementary Note 9) The electromagnetic valve drive device according to any one of Supplementary Notes 1 to 8, wherein the failure detection unit determines whether there is an abnormality based on a plurality of conditions using the coil voltage value, and determines whether there is a failure if an abnormality is determined under a plurality of different conditions.

[0110] REFERENCE SIGNS LIST 1 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 supply control unit 3e Current supply period correction unit 3f Memory unit 3g Failure detection unit 100 Fuel injection valve (electromagnetic valve) 103 Solenoid coil (coil) 105 Valve body

Claims

1. A solenoid valve drive device comprising: a drive circuit that drives a fuel injection valve by energizing a coil of the fuel injection valve; a valve close detection unit that detects the valve closing timing of a valve body of the fuel injection valve based on a coil voltage value that is a voltage value of the coil; and a failure detection unit that performs failure determination based on the coil voltage value read by the valve close detection unit.

2. The solenoid valve drive device according to claim 1, wherein a high voltage side threshold is set so that the coil voltage value exceeds the high voltage side threshold during normal fuel injection during a cycle period set for the fuel injection valve to perform one fuel injection, and the failure detection unit determines that an abnormality has occurred if the coil voltage value does not exceed the high voltage side threshold during the cycle period, and performs the failure determination based on a count value of the abnormality.

3. The solenoid valve drive device as claimed in claim 1, wherein, during a cycle period set for the fuel injection valve to perform one fuel injection, a high-voltage side threshold is set so that the coil voltage value exceeds it during normal fuel injection, and a low-voltage side threshold is set so that the coil voltage value after exceeding the high-voltage side threshold falls below it during the same cycle period during normal fuel injection, and the fault detection unit determines that an abnormality has occurred if the coil voltage value after exceeding the high-voltage side threshold does not fall below the low-voltage side threshold for a predetermined period during the cycle period, and performs the fault determination based on a count value of the abnormality.

4. The solenoid valve drive device according to claim 1, wherein the failure detection unit determines that an abnormality has occurred if the coil voltage value is not within a preset normal voltage range at the valve closing timing, and performs the failure determination based on a count value of the abnormality.

5. The solenoid valve drive device according to claim 1, wherein the failure detection unit determines that an abnormality has occurred if the coil voltage value is not within a preset normal voltage range within a predetermined fixed period of time from the start of startup of the drive circuit, and performs the failure determination based on a count value of the abnormality.

6. The solenoid valve drive device according to any one of claims 2 to 4, wherein the fault detection unit determines that a fault has occurred when the count value of the abnormality exceeds a predetermined fault determination value during a monitoring period which is a period which begins after the abnormality is determined to exist when the count value of the abnormality is zero.

7. The solenoid valve drive device according to any one of claims 2 to 5, wherein the failure detection unit sets the abnormality count value to zero if the abnormality count value does not exceed a predetermined failure judgment value within a set period of time.

8. The solenoid valve drive device according to claim 6, further comprising: an energization control unit that sets a period during which an electric current is applied to the coil; and an energization period correction unit that corrects the energization period, wherein the energization period correction unit stops correcting the energization period when the monitoring period is in progress.

9. An electromagnetic valve drive device as claimed in any one of claims 1 to 5, wherein the fault detection unit determines whether or not there is an abnormality based on a plurality of conditions using the coil voltage value, and determines whether or not there is a fault if an abnormality is determined under a plurality of different conditions.

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