JP2013002476A - Solenoid valve driving apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To open a solenoid valve in constant valve opening timing all the time without being affected by temperature variation or individual variation even if there is such variation in inductance of a coil of the solenoid valve.SOLUTION: A capacitor C10 for discharging is charged by a booster circuit 50 in such a manner that its charging voltage becomes a target DC-DC voltage Vt. The target DC-DC voltage Vt is set by a microcomputer 130. When discharging from the capacitor C10 to a coil 101a of a cylinder #1 is performed, the microcomputer 130 calculates actual discharge energy En that is actually discharged from the capacitor C10 during a discharge period, and compares the calculated energy with reference energy Er. If En is not matched with Er, on the basis of a difference between the both, the target DC-DC voltage Vt is reset in such a manner that En=Er is satisfied in the discharge period, subsequent to next one, to the coil 101a of the cylinder #1.

Description

  The present invention relates to a device for driving a solenoid valve, and more particularly, to a device for discharging electrical energy having a voltage higher than a power supply voltage to a coil of the solenoid valve to improve the operation responsiveness of the solenoid valve.

  2. Description of the Related Art Conventionally, as an injector (fuel injection valve) that injects fuel into each cylinder of an internal combustion engine mounted on a vehicle, for example, an electromagnetic valve that is opened by energization of a coil (electromagnetic solenoid) is used. A fuel injection control device that controls fuel injection by driving such an injector controls the energization of the coil (the energization start timing and the energization time) to thereby control the fuel injection timing and the fuel injection amount to the internal combustion engine. Is controlling.

  Further, in such a fuel injection control device, in order to accelerate the valve opening response of the injector, the DC power supply voltage is boosted by a booster circuit such as a DC-DC converter to charge the discharging capacitor and the coil should be energized. At the start of the period, the high voltage energy (electrical energy) stored in the discharge capacitor is discharged to the coil of the injector and a specified large current (so-called peak current) is allowed to flow, so that the injector is quickly It is known that the injector is moved to the valve open state, and then the injector is held in the valve open state by supplying a constant current (so-called holding current) to the coil until the driving period ends (for example, (See Patent Document 1).

  In order to open the injector at the start of the driving period, it is necessary to discharge a predetermined energy from the discharge capacitor to the coil. However, in the technique described in Patent Document 1, the current flowing in the coil after the discharge is started It is determined that the predetermined energy can be discharged when the predetermined threshold value Io (hereinafter also referred to as “driving current”) reaches a predetermined threshold value Io.

  More specifically, a transistor as a switch for conducting / cutting off the energization path is provided in the energization path from the discharge capacitor to the coil, and a current detection resistor for detecting the current flowing through the energization path is provided. Provide. Then, the transistor is turned on to start discharging from the discharging capacitor. After that, when the detection value of the drive current by the current detection resistor reaches the threshold value Io, the transistor is turned off again.

  Then, after the transistor is turned off (after completion of the discharge), the booster circuit is operated to charge the discharging capacitor to a desired voltage to prepare for the next drive (discharge).

Japanese Patent No. 3577301

  However, the inductance of the injector coil varies due to the coil temperature, individual differences, and the like. As is well known, the current flowing through the coil depends on the applied voltage and inductance. For this reason, if the inductance varies due to temperature, individual differences, etc., the increase rate (slope) of the drive current from the start of discharge from the discharge capacitor to the threshold value Io also varies. The variation in the increase rate of the drive current means that the time taken for the energy supplied (discharged) from the discharge capacitor to the coil to reach the value required for valve opening varies, and as a result, the injector The valve opening timing will vary.

  The variation in the valve opening timing will be described more specifically with reference to FIG. FIG. 5A shows an example of the current flowing through the coil when the injector is driven, and shows three types of cases A to C. FIG. In either case, discharge from the discharge capacitor to the coil is started at the start of driving at time t0, and thereby the drive current flowing through the coil increases rapidly. When the drive current reaches a predetermined discharge current detection threshold Io, the discharge from the discharge capacitor is stopped, and then a holding current flows until the drive period ends.

  For example, in case B, since the drive current reaches the discharge current detection threshold Io at time t3, the discharge capacitor is discharged between times t0 and t3. Then, as shown in FIG. 5 (b), the energy released from the discharge capacitor at the time t2 that is a predetermined time before reaching the discharge current detection threshold Io is the minimum energy required for opening the injector. Therefore, the injector opens at time t2 as shown in FIG. 5 (c).

  On the other hand, the inductance of the coil has temperature variations and individual variations as described above. For example, the higher the coil temperature, the larger the inductance. Therefore, as the inductance increases, the increase rate of the drive current decreases, and the time until the energy released from the discharge capacitor to the coil reaches the minimum energy Eo required for valve opening also increases.

  In FIG. 5, the case C has a higher coil inductance due to the higher temperature than the case B, and the increase rate of the drive current becomes smaller than the case B, and the timing at which the released energy reaches Eo (that is, valve opening). The timing is a time t3 later than the time t2 of case B. Conversely, in case A, the inductance of the coil is smaller than in case B. Therefore, the increase rate of the drive current is larger than in case B, and the timing at which the released energy reaches Eo (valve opening timing) is that of case B. The case where it becomes time t1 earlier than time t2 is shown.

  Thus, when the inductance of the coil varies due to temperature variation, individual variation, etc., the rate of increase in drive current from the start of discharge until it reaches the discharge current detection threshold Io varies, and the timing at which the released energy reaches Eo also varies. Therefore, the valve opening timing of the injector also varies. As the inductance variation increases, the valve opening timing variation also increases.

  The present invention has been made in view of the above problems, and in a solenoid valve driving device, even if there is a temperature variation or individual variation in the inductance of the coil of the solenoid valve, a constant valve opening timing is not affected by the variation. The purpose is to be able to open the valve.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a capacitor for storing electrical energy supplied to a coil of a solenoid valve and a DC voltage of a DC power source are boosted to a higher voltage than the DC voltage. The charging means for charging the capacitor with the boosted high voltage, the switch means provided in the energizing path to cut off the energizing path from the capacitor to the coil, and the discharge start timing from the capacitor to the coil When the discharge start timing set by the discharge start timing setting means to be set, the current detection means for detecting the discharge current discharged from the capacitor to the coil, and the discharge start timing set means has arrived, the switch means is turned on to energize Conducting the path starts discharging from the capacitor to the coil, and after starting the discharge, Switch control means for stopping discharge by turning off the switch means and cutting off the energization path when the discharge current detected by the detection means exceeds a preset discharge current detection threshold. The electromagnetic valve driving device is configured to operate the electromagnetic valve by discharging from the capacitor to the coil, and further includes actual emission energy calculating means and physical quantity setting means.

  The actual emission energy calculation means is the energy released from the capacitor to the coil during the discharge period from the start of discharge from the capacitor to the coil by the switch control means at the discharge start timing until the discharge is stopped by the switch control means. Is calculated after the end of the discharge period.

  Then, the physical quantity setting means matches the actual emission energy with the reference energy in the next and subsequent discharges based on the difference between the actual emission energy calculated by the actual emission energy calculation means and the preset reference energy. As described above, the physical quantity that determines the actual emission energy in the electromagnetic valve driving device is set.

  The physical quantity that determines the actual emission energy is such that the actual emission energy also fluctuates when the physical quantity fluctuates in the solenoid valve drive device. For example, the capacitor and coil for energizing the coil from the capacitor Various physical quantities (including the charging voltage of the capacitor before the start of discharge and the impedance on the coil side (load side) as seen from the capacitor) in the discharge circuit that is included.

  In the electromagnetic valve driving device of the present invention configured as described above, a reference energy serving as a reference for the energy is set in order to make the energy to be released from the capacitor to the coil constant. If the actual emission energy actually released during the discharge period does not coincide with the reference energy, the physical quantity is set so that the actual emission energy coincides with the reference energy in the next and subsequent discharges.

  For this reason, even if the coil inductance varies due to temperature, individual differences, etc., the actual emission energy can be set regardless of the inductance variation by setting the physical quantity based on the difference between the actual emission energy and the reference energy. Can be made to coincide with the reference energy, so that the valve can be opened at a constant valve opening timing without being affected by the variation.

  Various physical quantities to be set by the physical quantity setting unit are conceivable as described above. For example, the target voltage in the charging unit may be set as described in claim 2. That is, the physical quantity setting means is configured to set the target voltage in the charging means as the physical quantity. More specifically, the target voltage is set according to the actual emission energy so that the actual emission energy matches the reference energy. The charging unit performs charging so that the charging voltage of the capacitor becomes the target voltage based on the target voltage set by the physical quantity setting unit.

  The setting of the target voltage to be charged can be realized by a relatively simple configuration or a simple process as compared with, for example, changing the setting of the impedance viewed from the capacitor by providing an impedance conversion circuit or the like.

  Various specific methods for calculating the actual emission energy by the actual emission energy calculation means are also conceivable. For example, the actual emission energy can be realized by the configuration according to claim 3. That is, a charging voltage detecting means for detecting the charging voltage of the capacitor at a predetermined detection timing before the start of the discharging period, and an emitted charge detecting means for detecting the charge discharged from the capacitor to the coil during the discharging period are provided. In this way, the actual emission energy calculation means calculates the actual emission energy based on the charging voltage detected by the charging voltage detection means and the charge detected by the emission charge detection means. The emitted charge detection means can be easily realized by, for example, detecting the discharge current and integrating it. Therefore, the actual emission energy can be calculated easily and reliably.

  Further, in the case where the emission charge detecting means is provided as described above, it is possible to provide an abnormality determination function as described in claim 4 by using the means. That is, the electromagnetic valve driving device according to claim 4 is a charge acquisition unit that acquires the charge detected by the emitted charge detection unit at a predetermined determination timing after the switch unit is turned on, and the charge acquisition unit acquires the charge. First abnormality determination means for determining whether or not the charged charge is equal to or greater than a preset abnormality determination charge threshold and determining that the electromagnetic valve driving device is abnormal when the charge is not equal to or greater than the abnormality determination charge threshold And.

  If the energization path from the capacitor to the coil is normal, after the switch means is turned on, the charge should be detected by the emitted charge detection means, but if any abnormality such as disconnection or short circuit occurs in the energization path. Assuming that the current does not normally flow from the capacitor to the coil, the charge is not normally detected by the emitted charge detection means even after the switch means is turned on.

  Therefore, it is determined whether the energization path is normal by determining whether the charge detected by the emitted charge detection means is equal to or higher than the abnormality determination charge threshold at a predetermined determination timing after the switch means is turned on. Can do. That is, the detection result by the emission charge detection means provided for calculating the actual emission energy can be used not only for setting the off timing of the switch means, but also for diagnosing abnormality of the energization path.

  Further, the electromagnetic valve driving device having the above-described configurations may further have an abnormality determination function as described in claim 5. That is, the electromagnetic valve driving device according to claim 5 includes a first detection unit that detects a charging voltage of the capacitor at a predetermined first detection timing before the start of the discharge period, and a predetermined first after the end of the discharge period. A second detection unit that detects a charging voltage of the capacitor at two detection timings, and an abnormality determination voltage in which a difference between the charging voltage detected by the first detection unit and the charging voltage detected by the second detection unit is set in advance; And a second abnormality determining means for determining whether or not the electromagnetic valve driving device is abnormal when it is determined whether or not the threshold value is equal to or greater than a threshold value.

  If the current-carrying path from the capacitor to the coil is normal, there should be some difference in the charging voltage before and after the discharge period. However, if there is some abnormality such as disconnection or short-circuit in the current-carrying path, the capacitor If the current does not normally flow from the coil to the coil, there is no difference in the charging voltage before and after the discharging period, or the difference is smaller than in the normal state.

  Therefore, it is possible to determine whether the energization path is normal by determining whether the difference between the charging voltages before and after the discharging period is equal to or greater than the abnormality determination voltage threshold, and drive the solenoid valve with higher added value. An apparatus can be provided.

It is a block diagram showing the structure of ECU (fuel injection control apparatus) of embodiment. It is a time chart for demonstrating operation | movement of a microcomputer and driving IC. It is a flowchart showing a target DC-DC voltage setting process. It is a flowchart showing an abnormality determination process. It is explanatory drawing for demonstrating the problem (variation of valve opening timing) which arises due to the inductance variation of the coil of a solenoid valve.

Preferred embodiments of the present invention will be described below with reference to the drawings.
First, FIG. 1 is a configuration diagram showing a configuration of a fuel injection control device (hereinafter referred to as ECU) of the present embodiment.

  As shown in FIG. 1, the ECU 100 according to the present embodiment includes four injectors (solenoid valves) that inject fuel into each cylinder # 1 to # 4 of a multi-cylinder (4 cylinders in this example) engine mounted on a vehicle. ) 101, 102, 103, 104 are driven. Specifically, by controlling the energization start timing and energization time of the coils 101 a, 102 a, 103 a, 104 a of the injectors 101 to 104, each cylinder # The fuel injection timing and fuel injection amount to 1 to # 4 are controlled.

  The engine of the present embodiment is a diesel engine, and a so-called common rail system is constructed in which high pressure fuel is accumulated in a common rail (accumulation chamber) and is injected from each injector into each cylinder. This common rail system is controlled by the ECU 100. Since the common rail system is well known, detailed description and illustration thereof are omitted here.

  In addition, each of the injectors 101 to 104 is constituted by a normally closed electromagnetic valve, and when the coils 101a to 104a are energized, the injectors 101 are opened to perform fuel injection. Further, when the energization to the coils 101a to 104a is interrupted, the valve is closed and fuel injection is stopped.

  Here, in this embodiment, the injectors 101 to 104 for all four cylinders are divided into two groups of two cylinders, and the injectors 101 and 103 of the cylinders # 1 and # 3 are set as the first group, and their coils 101a, One end on the upstream side of 103a is connected to the first common terminal COM1 of ECU 100, and each of the injectors 102 and 104 of cylinders # 2 and # 4 is made into a second group, and one end on the upstream side of those coils 102a and 104a is connected to ECU 100. It is connected to the second common terminal COM2. Each group is composed of injectors that are not driven simultaneously.

  The downstream ends of the coils 101a to 104a are connected to one of the cylinder selection transistors (hereinafter referred to as “cylinder selection transistors”) T10, T20, T30, and T40 via terminals INJ1, INJ2, INJ3, and INJ4 of the ECU 100. It is connected to each output terminal. The other output terminals of the cylinder selection transistors T10 to T40 are connected (grounded) to the ground line via current detection resistors R10 and R20 for each group of injectors.

  Therefore, the current flowing through the coils 101a and 103a of the injectors 101 and 103 via the cylinder selection transistors T10 and T30 corresponding to the cylinders # 1 and # 3 is detected as a voltage generated in the current detection resistor R10, and the cylinder # 2 , # 4, the currents flowing through the coils 102a and 104a of the injectors 102 and 104 through the cylinder selection transistors T20 and T40 corresponding to # 4 are detected as voltages generated in the current detection resistor R20. In this example, all transistors provided as switching elements in the ECU 100 are MOSFETs.

  In addition to the cylinder selection transistors T10 to T40 and the current detection resistors R10 and R20, the ECU 100 includes constant current control transistors (hereinafter referred to as “constant current transistors”) T11 and T21, and discharge transistors. T12, T22 (hereinafter referred to as “discharge transistor”), four diodes D11, D12, D21, D22, two capacitors (discharge capacitors) C10, C20, and a DC voltage of the in-vehicle battery 10 as a DC power source ( A booster circuit (DC-DC converter) 50 that boosts the battery voltage) VB (for example, 12V in this example), generates a voltage higher than the battery voltage VB, and charges the capacitors C10 and C20, and each capacitor C10 , C20 charging voltage detecting circuit 70, and each of the transistors A drive IC120 which a control circuit is mounted for controlling the fine boosting circuit 50, CPU, ROM, RAM and the well-known microcomputer 130 made of are provided. The microcomputer 130 includes an AD converter (analog-digital converter) 20 therein.

  The microcomputer 130 determines each cylinder # 1 based on engine operation information detected by various sensors such as the engine speed Ne, the accelerator opening ACC, the engine water temperature THW, and the rail pressure Pr that is the pressure of fuel in the common rail. Drive signals IJT1 to IJT4 for each of # 4 are generated and output to the drive IC 120. The drive signals IJT1 to IJT4 mean that the coils 101a to 104a of the injectors 101 to 104 are energized (that is, the injectors 101 to 104 are opened) only while the level of the signals is high (H level). have.

  Then, based on the drive signals IJT1 to IJT4 from the microcomputer 130, the driving IC 120 outputs cylinder selection signals TQ1 to TQ4 having the same logic level as the corresponding drive signals to the gates of the cylinder selection transistors T10 to T40. For example, while the drive signal IJT1 corresponding to the cylinder # 1 is at the low level (L level), the driving IC 120 outputs the cylinder selection signal TQ1 of the L level to the corresponding cylinder selection transistor T10, and the cylinder selection transistor T10 is output. Conversely, while the drive signal IJT1 is at the H level, the driving IC 120 outputs the cylinder selection signal TQ1 at the H level to the corresponding cylinder selection transistor T10 to turn on the cylinder selection transistor T10.

  Further, the driving IC 120 outputs the emission charge monitor voltage Vm (analog value) and the discharge stop timing signal Ps to the microcomputer 130 individually for each group, and these emission charge monitor voltage Vm and the discharge stop timing signal Ps. Details will be described later.

  In FIG. 1, only four types of signals (IJT1, IJT3, Vm, Ps) corresponding to the first group are shown for various signals input and output between the microcomputer 130 and the driving IC 120. However, for the second group, although the specific illustration is omitted, the above four types of signals and the like are input / output as in the first group.

  On the other hand, the booster circuit 50 includes an inductor L00, a charging transistor (hereinafter referred to as “charging transistor”) T00, and a charging control circuit 110 that drives the charging transistor T00. The inductor L00 has one end connected to the power supply line Lp to which the battery voltage VB is supplied, and the other end connected to one output terminal (drain) of the charging transistor T00. Further, a current detection resistor R00 is connected between the other output terminal (source) of the charging transistor T00 and the ground line. The charging control circuit 110 is connected to the gate terminal of the charging transistor T00, and the charging transistor T00 is turned on / off according to the output of the charging control circuit 110.

  Furthermore, one end (positive terminal) of the first capacitor C10 is connected to a connection point between the inductor L00 and the charging transistor T00 via a first diode D13 for backflow prevention. One end (positive terminal) of the second capacitor C20 is connected via a second diode D23 for prevention. The other ends (negative electrode side terminals) of the capacitors C10 and C20 are connected to a connection point between the source of the charging transistor T00 and the resistor R00.

  In the booster circuit 50, when the charging transistor T00 is turned on / off, a flyback voltage (back electromotive voltage) higher than the battery voltage VB is generated at the connection point between the inductor L00 and the charging transistor T00. The capacitors C10 and C20 are charged through the diodes D13 and D23 by the flyback voltage.

  As a result, the capacitors C10 and C20 are charged to a voltage higher than the battery voltage VB. The charging control circuit 110 turns on / off the charging transistor T00 when the charging permission signal from the driving IC 120 becomes active level (for example, high level). At this time, the positive side of each of the capacitors C10, C20 The terminal voltage (charge voltage of each capacitor C10, C20; hereinafter also referred to as “DC-DC voltage”) is monitored, and the DC-DC voltage is set to a preset target DC-DC voltage Vt (charge target voltage). If the charge permission signal becomes an inactive level, the charging transistor T00 is kept off and charging of the capacitors C10 and C20 is stopped.

  The target DC-DC voltage Vt is not a fixed value, but is individually calculated by the microcomputer 130 for each of the coils 101a to 104a and input from the microcomputer 130, as will be described later. This is one of the most characteristic configurations of the ECU 100 of the present embodiment. Although not shown, the charging control circuit 110 receives driving signals IJT1 to IJT4 or signals indirectly indicating them from the microcomputer 130 or the driving IC 120, whereby the charging control circuit 110 Each time the charging operation is performed, it is configured to know which injector coil is to be discharged next.

  Therefore, according to each target DC-DC voltage Vt for each coil input from the microcomputer 130, the charge control circuit 110 causes the charging voltage (DC-DC voltage) of each capacitor C10, C20 to be the next of the injector to be discharged. Charging is performed so as to match the target DC-DC voltage Vt corresponding to the coil. For example, if the next discharge target in the first group is the coil 101a of the cylinder # 1, the charging control circuit 110 uses the first capacitor C10 and the target DC-DC voltage whose charging voltage corresponds to the coil 101a. Charge to Vt.

  The number of times the charging transistor T00 is turned on / off at the time of charging (hereinafter also referred to as “the number of charging operations”) is the charging energy required to charge the capacitors C10 and C20 to be charged to the target DC-DC voltage. The number of charging operations increases as the required charging energy increases. As the number of charging operations increases, the heat generation of the charging transistor T00 increases, and the heat generation of the entire booster circuit 50 also increases.

  Further, in the ECU 100, the first discharging transistor T12 is provided for discharging from the first capacitor C10 to the first group of coils 101a and 103a connected to the first common terminal COM1, and the first discharging transistor T12 is provided. When one discharge transistor T12 is turned on, the positive electrode side terminal (high voltage side terminal) of the first capacitor C10 is connected to the first common terminal COM1.

  Similarly, the second discharge transistor T22 is provided for discharging from the second capacitor C20 to the second group of coils 102a and 104a connected to the second common terminal COM2. When the transistor T22 is turned on, the positive terminal of the second capacitor C20 is connected to the second common terminal COM2.

  In the ECU 100, the first constant current transistor T11 is provided to allow a constant current (holding current) to flow through the first group of coils 101a and 103a connected to the first common terminal COM1, and the cylinder # When the first constant current transistor T11 is turned on while either the cylinder selection transistor T10 corresponding to 1 or the cylinder selection transistor T30 corresponding to cylinder # 3 is turned on, each cylinder selection transistor T10, A current flows through the coil (101a or 103a) connected to the ON state of T30 from the power supply line Lp via the backflow prevention diode D11. The diode D12 is a feedback diode for constant current control with respect to the coils 101a and 103a, and the first constant current transistor T11 is turned off from the on state when any of the cylinder selection transistors T10 and T30 is turned on. When this is done, current is returned to the coils 101a and 103a.

  Similarly, the second constant current transistor T21 is provided to allow a constant current (holding current) to flow through the second group of coils 102a and 104a connected to the second common terminal COM2, and is supplied to the cylinder # 2. When the second constant current transistor T21 is turned on while either the corresponding cylinder selection transistor T20 or the cylinder selection transistor T40 corresponding to the cylinder # 4 is turned on, each cylinder selection transistor T20, T40 is turned on. A current flows from the power supply line Lp through the backflow prevention diode D21 to the coil (102a or 104a) connected to the one that is turned on. The diode D22 is a feedback diode for constant current control with respect to the coils 102a and 104a, and the second constant current transistor T21 is turned from on to off in a state where any one of the cylinder selection transistors T20 and T40 is turned on. When this is done, current is returned to the coils 102a and 104a.

  Each constant current transistor T11, T21 is on / off controlled by a constant current control circuit provided in the driving IC 120, and the holding current flows by this on / off control.

  Further, in the ECU 110, the voltage detection circuit 70 receives the charging voltage (DC-DC voltage) Vdc of the first capacitor C10, and divides the DC-DC voltage Vdc by the two voltage dividing resistors R41 and R42. The divided voltage value is input to the microcomputer 130 as a value indicating the DC-DC voltage Vdc of the first capacitor C10. Similarly, the voltage detection circuit 70 divides the DC-DC voltage Vdc by the two voltage dividing resistors R51 and R52 with respect to the DC-DC voltage Vdc of the second capacitor C20. Then, it is input to the microcomputer 130 as a value indicating the DC-DC voltage Vdc of the second capacitor C20.

  Note that the divided voltage value input from the voltage detection circuit 70 to the microcomputer 130 is not strictly the same value as the DC-DC voltage Vdc, but is a value indicating the DC-DC voltage Vdc. For the sake of convenience, it is assumed that the DC-DC voltage Vdc is input from the voltage detection circuit 70 to the microcomputer 130.

  Then, the driving IC 120 receives the driving signals IJT1 and IJT3 corresponding to the cylinder # 1 and the cylinder # 3 from the microcomputer 130 as circuit components corresponding to the first group, and the logical sum of the two is input. The OR circuit 31 to be output and the current are integrated while the current flows while being discharged from the first capacitor C10 to each of the coils 101a and 103a of the first group. An integrator 33 for calculating a discharge charge monitor voltage Vm indicating the discharge charge Qm discharged from the capacitor C10 and a current value (actually a voltage value indicating the current value) flowing through the current detection resistor R10 are input and ORed. A discharge control circuit 35 that receives the output signal of the circuit 31 and outputs a binary output of H level or L level according to both input signals, and this discharge control circuit 5 and the output of the OR circuit 31 and the logical product of both are output, a constant current control circuit 41 for controlling the first constant current transistor T11 corresponding to the first group, an OR circuit, And a one-shot circuit 43 that detects a falling timing at which the output signal of the circuit 31 falls from the H level to the L level and outputs an H level signal (integral clear signal) for a predetermined period at the time of detection.

  Various circuits and the like corresponding to the first group are provided in the same manner for the second group, but the operation is basically the same as that corresponding to the first group. Therefore, various circuits corresponding to the second group of the driving IC 120 are not shown in FIG. In the following description, for the driving IC 120, various circuits corresponding to the first group will be described unless otherwise specified.

  The integrator 33 provided in the driving IC 120 has a known circuit configuration including an operational amplifier 53, an input resistor R30, and a capacitor C30. That is, one end of the input resistor R30 is connected to the inverting input terminal (−input terminal) of the operational amplifier 53, and the capacitor C30 is connected between the inverting input terminal and the output terminal of the operational amplifier 53. A predetermined positive integration reference voltage is input to the non-inverting input terminal (+ input terminal) of the operational amplifier 53. Then, the current value flowing through the current detection resistor R10, which is a signal to be integrated, is input to the other end of the input resistor R30 via the integration input switch 51. The integration input switch 51 is turned on / off by an output signal from the AND circuit 39. Specifically, it is turned off while the AND circuit output signal is at the L level, and turned on while the AND circuit output signal is at the H level.

  An integration clear switch 55 for clearing (resetting) the integral value is connected to both ends of the capacitor C30. The integral clear switch 55 is turned on / off by an integral clear signal input from the one-shot circuit 43. Specifically, it is turned off while the integral clear signal is at the L level, and is turned on while the integral clear signal is at the H level.

  With such a configuration, in an initial state where there is no integral input (the integral value is cleared), the emission charge monitor voltage Vm output from the integrator 33 is input to the non-inverting input terminal of the operational amplifier 53. The initial value Va corresponds to the integration reference voltage. This means that the charge Qm emitted from the first capacitor C10 is zero.

  Then, any one of the cylinder selection transistors T10 and T30 in the first group is turned on and the first discharge transistor T12 is turned on, whereby the first capacitor C10 to any coil in the first group. When discharge (charge release) is started and the integration input switch 51 is turned on at the same time, the discharge current is detected by the current detection resistor R10, and the detected value is input to the integrator 33 to start integration. .

  The integration by the integrator 33 is performed when the first discharge transistor T12 is turned on during the energization period of the first group of coils 101a and 103a and the first capacitor C10 to the first group of coils. 101a, 103a, during which electric current flows, that is, while electric energy is discharged (charge is discharged) from the first capacitor C10 to the first group of coils. Therefore, the integrator 33 substantially calculates the emission charge Qm emitted from the first capacitor C10, and is configured to output an emission charge monitor voltage Vm indicating the emission charge Qm. Yes.

  Further, the integrator 33 of the present embodiment has a configuration in which a signal to be integrated is input to the negative input terminal of the operational amplifier 53 and a predetermined positive integration reference voltage is input to the positive input terminal. The output (discharged charge monitor voltage Vm) is the initial value Va (positive value) as described above in the initial state before the start of integration, and gradually decreases from the initial value Va when the integration is started. Become. That is, the integrator is configured such that the integral value decreases as the integration proceeds.

  Of course, the use of an integrator having such a configuration is merely an example, and conversely, using an integrator whose output value increases as the integration proceeds, the same function is exhibited. The driving IC 120 may be configured.

  The discharge control circuit 35 is for determining the stop timing of the discharge after the discharge from the first capacitor C10 to any one of the coils of the first group is started. The discharge control circuit 35, when the discharge from the first capacitor C10 is started, when the detection value of the discharge current input from the current detection resistor R10 reaches a preset discharge current detection threshold Io, The output signal to the AND circuit 39 is set to L level. After the change to the L level, when the signal input from the OR circuit 31 (the output signal of the OR circuit 31) becomes the L level, the output signal to the AND circuit 39 is switched from the L level to the H level. .

  An output signal from the discharge control circuit 35 to the AND circuit 39 is also output to the microcomputer 130 as a discharge stop timing signal Ps for informing the microcomputer 130 that the discharge from the first capacitor C10 has been stopped. The

  Next, the operation of the driving IC 120 will be described more specifically with reference to FIG. FIG. 2 shows an example of operation when fuel is injected into the first group of cylinders # 1 as an example.

  The microcomputer 130 controls the energization start timing (discharge start timing) and the energization time for the coils of the cylinders # 1 to # 4 so that each of the injectors 101 to 104 is in a predetermined order (the above energization time). ) Open the valve. Therefore, when it is time to open the injector of cylinder # 1, microcomputer 130 sets drive signal IJT1 corresponding to cylinder # 1 to the H level.

  When drive signals IJT1 and IJT3 corresponding to cylinders # 1 and # 3 are both at L level, that is, while fuel is not being injected into cylinders # 1 and # 3 (before time t2 in FIG. 2). The output of the OR circuit 31 is L level, the output of the AND circuit 39 is L level, the output of the one-shot circuit 43 is L level, and the integration input switch 51 and the integration clear switch 55 are off. Further, since the input to the integrator 33 (that is, the detected value of the current detection resistor R10) is 0, the output of the integrator 33 (discharged charge monitor voltage Vm) is the initial value Va, and the output of the discharge control circuit 35 is H level. Further, since the output of the AND circuit 39 is at the L level, the first discharging transistor T12 is turned off.

  Further, each time the discharge from either the first capacitor C10 or the second capacitor C20 is performed, the driving IC 120 supplies the voltage to the booster circuit 50 after the discharge is stopped until the next discharge is started. The charge permission signal is set to an active level, and the capacitors C10 and C20 are charged by the booster circuit 50 so that each capacitor C10 and C20 has a target DC-DC voltage Vt corresponding to the next coil to be discharged. Charge.

  Therefore, in a state where the capacitors C10 and C20 are charged to the target DC-DC voltage Vt before the energization to the cylinder # 1 is started, as shown in the lowermost stage of FIG. 2, the charging transistor T00 is turned on. / Off operation (charging operation) is stopped.

  In addition, FIG. 2 also shows a target DC-DC voltage Vt (target value corresponding to the cylinder # 1) input from the microcomputer 130 to the booster circuit 50 as an operation waveform. explain.

  When drive signal IJT1 corresponding to cylinder # 1 from microcomputer 130 becomes H level (time t2), drive IC 120 sets cylinder selection signal TQ1 corresponding to cylinder # 1 to H level as described above. Thus, the corresponding cylinder selection transistor T10 is turned on.

  Further, as the drive signal IJT 1 becomes H level, the output of the OR circuit 31 also rises from L level to H level, and the H level signal is input to one input terminal of the AND circuit 39. At this time, since the H level signal from the discharge control circuit 35 is inputted to the other input terminal of the AND circuit 39, the output of the AND circuit 39 becomes the H level, and the first discharge transistor T12 is turned on. The integration input switch 51 is also turned on.

  As a result, discharge from the first capacitor C10 to the coil 101a of the injector 101 of the cylinder # 1 is started. Then, the current flowing through the coil 101a when the discharge starts is detected by the current detection resistor R10, and the detected value is input to the discharge control circuit 35 and integrated by the integrator 33.

  When the discharge from the first capacitor C10 is started, the discharge current, that is, the current flowing through the coil 101a (injector drive current) increases as shown in the uppermost stage of FIG. 2 (peak current). Along with this, the input value to the integrator 33 also rises, so that the emission charge monitor voltage Vm (discharge charge Qm), which is the output of the integrator 33, decreases as the integration proceeds.

  After the discharge starts at time t2, when the discharge current reaches the discharge current detection threshold Io (time t3), the output of the discharge control circuit 35 becomes L level, and the output of the AND circuit 39 also becomes L level.

Therefore, the first discharge transistor T12 is turned off to stop the discharge from the first capacitor C10, and the integration input switch 51 is turned off.
At time t3, that is, when the discharge current reaches the discharge current detection threshold Io, the energy necessary for opening the valve is supplied to the coil 101a of the injector 101 of the cylinder # 1. Therefore, the injector 101 of the cylinder # 1 is surely opened by this time t3.

  After the discharge from the first capacitor C10 is stopped, the constant current control circuit 41 performs on / off control of the constant current transistor T11, thereby energizing the coil 101a with a holding current and holding the valve open state.

  Further, after the discharge from the first capacitor C10 is stopped, the charge permission signal from the driving IC 120 to the charge control circuit 110 becomes an active level, so that the booster circuit as shown in the lowermost stage of FIG. The voltage boosting operation (charging operation) by 50, that is, the on / off operation of the charging transistor T00 is started, and the charging operation is continued until the first capacitor C10 is charged to the target DC-DC voltage Vt. Note that the charge permission signal is at an inactive level and charging is prohibited at least during the discharge period in which the capacitor C10 or C20 for discharging is discharged.

  At time t4, when the predetermined fuel injection time (the energization period to the coil 101a) has elapsed and the drive signal IJT1 from the microcomputer 130 becomes L level, the drive IC 120 operates the constant current control circuit 41. And the cylinder selection signal TQ1 corresponding to the cylinder # 1 is set to L level to turn off the corresponding cylinder selection transistor T10 and stop energization of the coil 101a.

  At time t4, the drive signal IJT1 becomes L level, so that the output of the OR circuit 31 changes from H level to L level. Therefore, the output of the one-shot circuit 43 becomes H level for a certain period. Therefore, the integration clear switch 55 is turned on for a certain period when the output of the one-shot circuit 43 is at the H level, and the integration value (discharged charge monitor voltage Vm) of the integrator 33 is cleared to the initial value Va. Further, at time t4, the output of the OR circuit 31 changes from the H level to the L level, so that the output of the discharge control circuit 35 also returns to the H level.

  In this way, one fuel injection is performed by the injector 101 of the cylinder # 1. The same applies to the operations of the injectors 101 of the other cylinders # 2 to # 4. Also in the present embodiment, multistage injection and multiple injection are performed as in the technique described in Patent Document 1. In either case, the operation content of each injection (single injection) is shown in FIG. It is the same as that shown in.

  By the way, in the ECU 100 of the present embodiment configured as described above, as described with reference to FIG. 5, when the inductance of the coil varies, the gradient of the discharge current at the time of discharging from the capacitor also varies. As a result, the valve opening timing varies. Therefore, in the present embodiment, even if there is a variation in the inductance of the coil, the current always rises with a constant slope, so that the valve opening timing is always constant regardless of the variation in inductance.

  In this embodiment, “constant” with respect to the slope of the discharge current from the capacitor does not mean that the current rises linearly with a certain slope, but the current from the start of discharge to the stop of discharge. This means that the rising tendency (transient current rising process after the start of discharge) is the same even if the inductance value is different as a whole. In other words, for example, referring to FIG. 5A, the current always increases with the same tendency (for example, the upward tendency of case B) regardless of the variation in inductance.

  If the slope can be controlled to be constant regardless of the variation in inductance, the time from the start of discharge until the discharge energy reaches the minimum energy Eo required for valve opening can be made constant. If it demonstrates using Fig.5 (a), if the inclination of an electric current can be uniformly controlled to the inclination of case B, for example regardless of the dispersion | variation in an inductance, it will always open at the same valve opening timing (time t2) irrespective of the dispersion | variation in an inductance. Can be made.

Then, the present inventor considered as follows how to specifically control the current gradient to be constant. In general, assuming that the inductance of the coil is L and the voltage applied to the coil is constant Vdc, the current I flowing through the coil T seconds after the start of energization is expressed by the following equation (1).
I = (Vdc / L) * T (1)
As apparent from the above formula (1), the slope of the current I is Vdc / L. Therefore, in order to make the slope of the current I constant regardless of the variation in the inductance L, the voltage Vdc may be changed according to the variation in the inductance L. For example, if the inductance L increases 1.1 times a certain reference value (design value), if the voltage Vdc is also increased 1.1 times, as a result, the slope Vdc / L of the current I does not change. Become.

  Therefore, in order to control the current gradient constant regardless of the inductance variation of the coil, the DC-DC voltage Vdc is controlled for each coil, that is, the target DC-DC voltage Vt of the booster circuit is controlled for each coil. did. That is, the fluctuation of the current gradient caused by the inductance variation is canceled by the DC-DC voltage Vdc.

  That is, in the present embodiment, the actual emission energy En (coil which is actually released energy) is monitored by monitoring the emission charge Qm and the DC-DC voltage Vdc (in this example, the value before the emission start) at the time of the charge emission. And the target DC-DC voltage Vt of the booster circuit is feedback-corrected based on the difference between the calculated actual emission energy En and the predetermined reference energy Er required for opening the valve. In other words, the amount and slope of the released energy are made constant.

  Next, a specific method for feedback correction of the target DC-DC voltage Vt will be described with reference to the flowchart of FIG. The target DC-DC voltage setting process shown in FIG. 3 is executed by the microcomputer 130. More specifically, the target DC-DC voltage setting process is more predetermined than the discharge start timing from the capacitor during each energization period of each of the coils 101a to 104a. Execution starts at the timing before the period.

  For example, when the coil 101a of the cylinder # 1 of the first group is energized, as shown in FIG. 2, at a time t1 that is a predetermined time before the time t2 that is the energization start (discharge start) timing. Then, the target DC-DC voltage setting process of FIG. 3 is started.

  In this target DC-DC voltage setting process, since it is necessary to first acquire the DC-DC voltage Vdc immediately before the start of discharge as will be described later, the execution start timing (time t1) of this target DC-DC voltage setting process Is preferably set at a timing as close as possible to the discharge start timing (or at the same time as the discharge start timing) at least after the charging of the capacitor by the booster circuit 50 is completed. Hereinafter, the target DC-DC voltage setting process of FIG. 3 will be described with reference to FIG. 2 on the assumption that the target DC-DC voltage setting process is executed when the coil 101a of the cylinder # 1 is energized.

  When the microcomputer 130 starts the target DC-DC voltage setting process at time t1 before the start of energization of the coil 101a of the cylinder # 1, first, in S110, the first capacitor C10 is charged from the voltage detection circuit 70. The actual DC-DC voltage Vdc being read is read. That is, first, the DC-DC voltage Vdc immediately before the start of discharge is read. As described above, the first capacitor C10 should be charged to the target DC-DC voltage Vt by the booster circuit 50 before the start of discharging. Therefore, the DC-DC voltage Vdc read in S110 should be the same value as the target DC-DC voltage Vt. FIG. 2 shows an example in which the target DC-DC voltage Vt corresponding to the coil 101a of the cylinder # 1 is set to Vt1 as an example.

  Thereafter, since the discharge from the first capacitor C30 is started at time t2, in the subsequent S120, it is determined whether or not the discharge has stopped. This discharge stop determination is made based on the discharge stop timing signal Ps input from the driving IC 120.

  When the discharge is stopped (S120: YES, time t3), the discharge charge Qm from the start of the discharge is read in S130. Specifically, the reading of the discharge charge Qm is performed by reading the discharge charge monitor voltage Vm from the driving IC 120.

In S140, the actual DC-DC voltage Vdc just before the start of discharge read in S110 and the actual discharge charge Qm read in S130 are used to calculate the actual value from the first capacitor C10 by the following equation (2). The actual emission energy En released to the is calculated.
En = Qm * Vdc / 2 (2)
The charge voltage (DC-DC voltage Vdc) of the first capacitor C10 decreases as the discharge proceeds after the start of discharge. In the present embodiment, each of the capacitors C10 and C20 for discharge is all. A large-capacity aluminum electrolytic capacitor is used, and the reduction amount of the DC-DC voltage Vdc by one discharge is small. Therefore, in the calculation of the actual emission energy En in the present embodiment, it is assumed that the DC-DC voltage Vdc is constant from the start to the end of the discharge as in the above formula (2) (ignoring the charge voltage drop due to discharge) It is calculated. However, even if the decrease amount of the DC-DC voltage Vdc before and after the discharge is not small, the actual release energy En in the present embodiment is made to coincide with the reference energy Er (and the valve opening timing is controlled to be constant). In order to achieve the object, there is no problem even if the above formulas (1) and (2) are used on the assumption that the value of the DC-DC voltage Vdc at the start of discharge is maintained even during the discharge period.

  Then, in S150, it is determined whether or not the actual emission energy En calculated in S140 is larger than the reference energy Er. If En> Er is not satisfied, that is, if the actual emission energy En is equal to or less than the reference energy Er (S150: NO), it is further determined in S180 whether the actual emission energy En is smaller than the reference energy Er.

  In this embodiment, the reference energy Er is a value larger by a predetermined amount than the minimum energy Eo necessary for opening the valve, specifically, in the case B, as illustrated in FIG. Is set to the emission energy when the discharge current detection threshold Io is reached (time t3).

  Here, if En> Er, it means that excessive energy has been supplied, that is, the discharge current becomes the reference energy Er when the slope of the discharge current reaches the design reference slope (the discharge current detection threshold Io is reached). The ideal inclination to reach (for example, the inclination of case B in FIG. 5) is smaller, and thus the time until the discharge current reaches the discharge current detection threshold Io is longer. The fact that the slope of the discharge current is smaller than the reference slope means that the time required for the energy released from the first capacitor C10 to reach the minimum energy Eo required for valve opening is also the above-mentioned reference slope. This means that the valve opening timing has been delayed by an amount longer than in the case of.

  Referring to FIG. 5, when En> Er, the slope of the current is smaller than that in case B, and the discharge characteristic is as in case C. Therefore, the energy Eo that is the minimum energy required for opening the valve is the discharge energy. This means that the timing (opening timing) to reach is later than the time t2 of case B.

Therefore, in this case, it is necessary to increase the current gradient so that the actual release energy En becomes the reference energy Er in the valve opening operation after the next time.
Therefore, in this embodiment, when En> Er (S150: YES), the target DC-DC voltage Vt is increased by the increase amount Vtu from the current set value in S160 to S170. If the target DC-DC voltage Vt is increased, the charging voltage (DC-DC voltage Vdc) of the first capacitor C10 before the start of discharge also increases, so that the slope of the discharge current can be increased.

  Conversely, if En <Er, the energy supply amount was less than the design value, that is, the slope of the discharge current is the design reference slope (in this example, the slope of case B in FIG. 5). Therefore, the time until the discharge current reaches the discharge current detection threshold Io is shortened. The fact that the slope of the discharge current is larger than the reference slope means that the time until the energy released from the first capacitor C10 reaches the minimum energy Eo required for valve opening is also the reference slope. This means that the valve opening timing is shortened and the valve opening timing is earlier.

  Referring to FIG. 5, En <Er means that the current gradient is larger than that in case B and discharge characteristics are as in case A. Therefore, the energy Eo that is the minimum energy required for opening the valve is the discharge energy. This means that the timing (opening timing) at which the timing reaches is earlier than the time t2 of case B.

Therefore, in this case, it is necessary to make the current gradient smaller so that the actual release energy En becomes the reference energy Er in the valve opening operation after the next time.
Therefore, in this embodiment, when En <Er (S180: YES), the target DC-DC voltage Vt is decreased by the decrease amount Vtd from the current set value in S190 to S200. If the target DC-DC voltage Vt is decreased, the charging voltage (DC-DC voltage Vdc) of the first capacitor C10 before the start of discharging also decreases, so that the slope of the discharge current can be reduced.

  If En = Er (NO in both S150 and S180), it means that the energy supply amount is the same as the design amount, that is, the slope of the discharge current is the design reference slope (this example). Then, it is the same as the inclination of case B in FIG. Therefore, in this case, since it is not necessary to change the setting of the target DC-DC voltage Vt, this target DC-DC voltage setting process is terminated.

  Next, the processing of S160 to S170 for increasing the target DC-DC voltage Vt executed when it is determined in S150 that the actual emission energy En is larger than the reference energy Er will be described.

In S160, first, the actual inductance value is estimated from the actual emission energy En calculated in S140 and the discharge current detection threshold value Io that is the value of the current actually flowing immediately before stopping the discharge. Specifically, the inductance to be estimated as an actual estimation inductance Ln, the actual estimated inductance Ln, using official known about the coil energy "E = LI ^2/2", calculated by the following equation (3) .
Ln = 2 * En / Io ² (3)
Next, the actual estimated inductance Ln, the ideal inductance Lr that is an ideal inductance in design, the ideal DC-DC voltage Vdco that is an ideal DC-DC voltage in design, and the actual DC− read in S110. Based on the DC voltage Vdc, an increase amount Vtu to be increased from the current target DC-DC voltage Vt is calculated by the following equation (4).
Vtu = | Vdco * Ln / Lr−Vdc | (4)
The ideal DC-DC voltage Vdco is designed so that the slope of the discharge current becomes the design reference slope if the DC-DC voltage is the ideal DC-DC voltage Vdco when the inductance is the ideal inductance Lr. Reference (ideal) DC-DC voltage.

  In the above equation (4), the DC-DC voltage should be the ideal DC-DC voltage Vdco and the inductance should be the ideal inductance Lr. This is based on the idea of what value should be set for the DC-DC voltage with respect to the actual estimated inductance Ln under the assumption that the value is Ln.

  In S170, the target DC-DC voltage Vt is reset to a value increased by the above Vtu from the currently set value, and the new target DC-DC voltage Vt after the reset is set to the booster circuit 50. (In detail, to the charge control circuit 110). Thereby, the charging control circuit 110 thereafter uses the first capacitor C10 for the new target DC-DC voltage in the charging operation of the first capacitor C10 performed before the discharge to the coil 101a of the cylinder # 1 is started. Charge to Vt.

  Next, the processing of S190 to S200 for reducing the target DC-DC voltage Vt, which is executed when it is determined in S180 that the actual emission energy En is smaller than the reference energy Er, will be described.

The process of S190 is basically the same as the process of S160. First, the actual estimated inductance Ln estimated from the actual emission energy En and the discharge current detection threshold Io is obtained by the above equation (3). Then, a decrease amount Vtd to be decreased from the current target DC-DC voltage Vt is calculated by the same calculation as the above expression (4), that is, the following expression (5).
Vtd = | Vdco * Ln / Lr−Vdc | (5)
In S200, the target DC-DC voltage Vt is reduced by Vtd from the currently set value by subtracting the decrease amount Vtd from the currently set target DC-DC voltage Vt. Reset it. Then, the new target DC-DC voltage Vt after the resetting is output to the booster circuit 50 (specifically, to the charge control circuit 110).

  FIG. 2 shows an example in which the target DC-DC voltage Vt is reset from Vt1 to Vt2 higher than Vt1 (higher by Vtu) because En> Er (that is, the current slope is small). Has been.

  The same applies to the other cylinders # 2 to # 4. For example, when the coil 102a of the cylinder # 2 is energized, the target DC-DC voltage Vt corresponding to the coil 102a of the cylinder # 2 is used. Then, the target DC-DC voltage setting process of FIG. 3 is executed, and the target DC-DC voltage Vt is reset (increased, decreased, or maintained as it is). Thereby, when the discharge to the coil 102a of the cylinder # 2 is performed again next time, the charge control circuit 110 sets the target DC-DC voltage after resetting the second capacitor C20 before the start of the discharge. Charge to Vt.

  Further, the microcomputer 130 of the present embodiment acquires the actual DC-DC voltage Vdc of each of the capacitors C10 and C20 from the voltage detection circuit 70, and acquires the emission charge monitor voltage Vm from the driving IC 120, and based on these. The abnormality determination of the energization path of each coil 101a-104a is performed.

  Specifically, as in the target DC-DC voltage setting process of FIG. 3, the timing before the discharge start timing from the capacitor during the energization period of each of the coils 101a to 104a (for example, the cylinder # 1) When the coil 101a is energized, the abnormality determination process shown in FIG. 4 is started at time t1) shown in FIG. Therefore, the abnormality determination process of FIG. 4 will be described below using FIG. 2 as appropriate, assuming that the abnormality determination process is executed when the coil 101a of the cylinder # 1 is energized.

  When the microcomputer 130 starts this abnormality determination process at time t1 before the start of energization of the coil 101a of the cylinder # 1, first, in S310, the actual voltage charged from the voltage detection circuit 70 to the first capacitor C10. The DC-DC voltage Vdc is read, and the read value is defined as Vdca.

  Thereafter, discharge is started at time t2 (S320), and it is determined whether or not a predetermined time has elapsed after the start of discharge (S330). The predetermined time determined here is a time when the discharge from the first capacitor C10 should be completed and the holding current energization period should be entered if the energization path is normal. As shown, it is time t31 after time t3 when the discharge is stopped. The predetermined time is preferably set so that the elapsed time from the discharge stop is as short as possible.

  When a predetermined time has elapsed after the start of discharge (that is, when time t31 is reached) (S330: YES), in S340, the actual DC-DC voltage Vdc charged from the voltage detection circuit 70 to the first capacitor C10 is again obtained. The read value is set as Vdcb.

  Further, in S350, the discharge charge Qm from the start of discharge is monitored. Specifically, the emission charge Qm is monitored by reading the emission charge monitor voltage Vm from the driving IC 120.

  In S360, the voltage difference before and after discharge, which is the difference between the DC-DC voltage Vdca read before the start of discharge (time t1) and the DC-DC voltage Vdcb read after the discharge stop (time t31), is a predetermined voltage. It is determined whether or not the difference threshold value Vr is greater. This voltage difference threshold value Vr is a value such that the voltage difference before and after the discharge is at least larger than the voltage difference threshold value Vr if the energization path is normal and the discharge from the first capacitor C10 is normally performed. Are preset in the microcomputer 130.

  Therefore, if the voltage difference before and after discharge (Vdca−Vdcb) is larger than the voltage difference threshold value Vr in S360, it is temporarily determined that the energization path is normal, and the process further proceeds to S370. On the other hand, if it is not determined in S360 that the voltage difference before and after discharge is larger than the voltage difference threshold Vr, it is determined that some abnormality has occurred in the energization path, and the process proceeds to S380, for example, alarm output or diagnostic recording. A predetermined first abnormality process is performed, and the process proceeds to S370.

  In S370, it is determined whether or not the emission charge monitor voltage Vm read in S350 is equal to or less than a preset abnormality determination threshold value Vx, that is, whether or not the emission charge Qm is equal to or more than a predetermined threshold value Qx. As shown in FIG. 2, the abnormality determination threshold value Vx is smaller than the initial value Va of the integrator 33 and larger than the emission charge monitor voltage Vm when the discharge is stopped when the discharge is normally performed. .

  In the coil 101a of the cylinder # 1, if the energization path is normal, after the energization is started (that is, after the discharge from the first capacitor C10 is started), a current flows through the current detection resistor R10, and the current is integrated in the integrator 33. Therefore, the emission charge monitor voltage Vm, which is the output value, should gradually decrease as shown in FIG. 2 and be lower than the abnormality determination threshold value Vx. However, an abnormality such as a disconnection or a short circuit has occurred in the energization path, and even if both the first discharge transistor T12 and the cylinder selection transistor T10 are turned on, a normal current is not detected by the current detection resistor R10. Then, even if the emitted charge monitor voltage Vm does not change from the initial value Va or decreases, there is a possibility that it does not decrease with a normal inclination.

  Therefore, the microcomputer 130 appropriately sets an abnormality determination threshold value Vx that must be reached by the determination timing (time t31) if the energization path is normal, and whether the emission charge monitor voltage Vm is equal to or lower than the abnormality determination threshold value Vx. Whether or not there is an abnormality in the energization path is determined based on whether or not it is present. In other words, in the present embodiment, two types of abnormality diagnosis are performed, that is, the conduction path abnormality diagnosis based on the voltage difference before and after discharge (S360) and the conduction path abnormality diagnosis based on the emission charge monitor voltage Vm (S370). I have to.

  In the process of S370, if the emission charge monitor voltage Vm is equal to or lower than the abnormality determination threshold value Vx (that is, if the emission charge Qm is equal to or higher than the predetermined threshold value Qx) (S370: YES), it is assumed that the energization path is normal. The determination process ends. On the other hand, if the emission charge monitor voltage Vm is greater than the abnormality determination threshold value Vx (that is, if the emission charge Qm has not reached the predetermined threshold value Qx) (S370: NO), some abnormality has occurred in the energization path. The process proceeds to S390, and predetermined second abnormality processing such as alarm output and diagnosis recording is performed.

  As described above, in the ECU 100 of the present embodiment, the target value of the charging voltage of each of the capacitors C10 and C11 for discharging, that is, the target DC-DC voltage Vt, is individually determined for each of the coils 101a to 104a to be discharged. A variable setting is made based on the actual emission energy En. Specifically, the emission charge Qm and the DC-DC voltage Vdc are monitored, and the actual emission energy En (the input energy to the solenoid valve coil) actually released is calculated based on these, and the reference energy as a reference Based on the difference from Er, the target DC-DC voltage Vt is feedback-corrected so that the difference becomes 0 (that is, the actual emission energy En coincides with the reference energy Er in the next and subsequent discharges).

  With such a configuration, even if the inductance of the coil varies due to temperature, individual differences, etc., the actual emission energy En can be made to coincide with the reference energy Er regardless of the variation of the inductance. Since the amount and the inclination can be made constant, the injector can be opened at a constant valve opening timing without being affected by the variation.

  If the emission energy varies due to variations in inductance, the emission energy may become excessive. When the released energy becomes excessive, the charging operation of the booster circuit 50 (the number of times the charging transistor T00 is turned on / off) increases, the heat generation amount increases, and the fuel injection frequency is restricted, resulting in an increase in the heat generation amount. May cause various problems.

  On the other hand, in the present embodiment, since the actual emission energy En is controlled so as to match the reference energy Er, by appropriately setting the reference energy Er, it is possible to suppress the release of excessive energy. Yes. Therefore, it is possible to suppress the occurrence of various restrictions caused by the large amount of heat generation, and to improve the operation frequency of the injector.

  Further, in the present embodiment, the abnormality determination process shown in FIG. 4 is performed using the difference between the DC-DC voltage Vdc before and after the discharge period and the emission charge monitor voltage Vm, thereby determining whether there is an abnormality in the energization path. Like to do. Therefore, higher performance ECU 100 can be realized while suppressing an increase in circuit scale.

  In the present embodiment, the booster circuit 50 corresponds to the charging means of the present invention, the discharge transistors T12 and T22 correspond to the switch means of the present invention, and the microcomputer 130 includes the discharge start timing setting means and physical quantity of the present invention. The driving IC 120 corresponds to the setting control means, the switch control means of the present invention, the current detection resistors R10 and R20 correspond to the current detection means of the present invention, and the time t1 in FIG. This corresponds to the first detection timing, and the time t31 in FIG. 2 corresponds to the determination timing and the second detection timing of the present invention.

  In the target DC-DC voltage setting process of FIG. 3, the process of S110 corresponds to the process executed by the charge voltage detection of the present invention, and the process of S130 corresponds to the process executed by the emitted charge detection means of the present invention. The processing of S140 corresponds to the processing executed by the actual emission energy calculation means of the present invention, and the processing of S150 to S200 corresponds to the processing executed by the physical quantity setting means of the present invention.

  In the abnormality determination process of FIG. 4, the process of S310 corresponds to the process executed by the charging voltage detection means and the first detection means of the present invention, and the process of S340 is the process executed by the second detection means of the present invention. The process of S350 corresponds to the process executed by the charge acquisition unit of the present invention, the process of S380 corresponds to the process of the second abnormality determination unit of the present invention, and the process of S390 corresponds to the process of the present invention. The voltage difference threshold Vr used in S360 corresponds to the abnormality determination voltage threshold of the present invention, and the charge threshold Qx indicated by the abnormality determination threshold Vx used in S370 is the abnormality determination of the present invention. This corresponds to the charge threshold.

[Modification]
Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and can take various forms as long as they belong to the technical scope of the present invention. Needless to say.

  For example, in the above embodiment, the target DC-DC voltage Vt is set so that the actual emission energy En becomes the reference energy Er, but what value the actual emission energy En is controlled to be, that is, the reference energy What value Er should be set to can be determined as appropriate at least in a range equal to or higher than the minimum energy Eo required for valve opening. Therefore, for example, Er = Eo may be set.

  In the above embodiment, as a specific method for variably setting the target DC-DC voltage Vt, the actual estimated inductance Ln is estimated from the actual emission energy En and the discharge current detection threshold Io (Equation (3)), and the estimation is performed. Although the method (formula (4) or formula (5)) for obtaining the increase amount Vtu or the decrease amount Vtd of the target DC-DC voltage Vt using the actual estimated inductance Ln has been shown, such a method is merely an example, The specific method is not particularly limited as long as the amount of increase or decrease of the target DC-DC voltage Vt necessary for making the actual emission energy En coincide with the reference energy Er can be appropriately obtained.

  In the above embodiment, the target DC-DC voltage Vt is variably set as a specific method for making the actual emission energy En coincide with the reference energy Er. It is not essential to variably set, and a method of variably setting another physical quantity that determines the actual emission energy En (for example, the impedance of the entire circuit when the coil side is viewed from the capacitor) may be employed.

  In the above embodiment, the present invention is applied to a normally closed solenoid valve. However, the present invention is a normally open solenoid valve configured to be closed by energizing a coil. It can also be applied to.

DESCRIPTION OF SYMBOLS 10 ... Vehicle-mounted battery, 20 ... AD converter, 31 ... OR circuit, 33 ... Integrator, 35 ... Discharge control circuit, 39 ... AND circuit, 41 ... Constant current control circuit, 43 ... One shot circuit, 50 ... Booster circuit, DESCRIPTION OF SYMBOLS 51 ... Integration input switch, 53 ... Operational amplifier, 55 ... Integration clear switch, 70 ... Voltage detection circuit, 101-104 ... Injector, 101a-104a ... Coil, 110 ... Charge control circuit, 120 ... Driving IC, 130 ... Microcomputer, C10: first capacitor, C20: second capacitor, C30: capacitor, COM1: first common terminal, COM2: second common terminal, D11, D12, D13, D21, D22, D23: diode, L00: inductor, Lp: power supply line, R00: resistor, R10, R20: current detection resistor, R30: input resistor, R41, 42, R51, R52 ... dividing resistors, T00 ... charging transistor, T10, T20, T30, T40 ... cylinder selection transistors, T11, T21 ... constant current transistors, T12, T22 ... discharge transistor

Claims (5)

A capacitor for storing electrical energy to be supplied to the coil of the solenoid valve;
Charging means for boosting the DC voltage of the DC power source to a high voltage higher than the DC voltage, and charging the capacitor with the boosted high voltage;
Switch means provided in the energization path for conducting / interrupting the energization path from the capacitor to the coil;
A discharge start timing setting means for setting a discharge start timing from the capacitor to the coil;
Current detection means for detecting a discharge current discharged from the capacitor to the coil;
When the discharge start timing set by the discharge start timing setting means arrives, the switch means is turned on to conduct the energization path, thereby starting discharge from the capacitor to the coil. And a switch control means for stopping the discharge by turning off the switch means and cutting off the energization path when the discharge current detected by the current detection means exceeds a preset discharge current detection threshold value. When,
An electromagnetic valve driving device configured to operate the electromagnetic valve by discharging from the capacitor to the coil,
The energy released from the capacitor to the coil during the discharge period from the start of discharge from the capacitor to the coil by the switch control means at the discharge start timing until the discharge is stopped by the switch control means. An actual emission energy calculating means for calculating an actual emission energy after the end of the discharge period;
Based on the difference between the actual emission energy calculated by the actual emission energy calculation means and a preset reference energy, so that the actual emission energy matches the reference energy at the time of the next and subsequent discharges. Physical quantity setting means for setting a physical quantity that determines the actual emission energy in the electromagnetic valve driving device;
An electromagnetic valve driving device comprising: The electromagnetic valve driving device according to claim 1,
The physical quantity setting means is configured to set a target voltage in the charging means as the physical quantity,
The electromagnetic valve driving device, wherein the charging unit performs charging so that a charging voltage of the capacitor becomes the target voltage based on the target voltage set by the physical quantity setting unit. The electromagnetic valve driving device according to claim 1 or 2,
Charging voltage detecting means for detecting a charging voltage of the capacitor at a predetermined detection timing before the start of the discharging period;
Discharged charge detection means for detecting charge discharged from the capacitor to the coil during the discharge period;
With
The solenoid valve driving device characterized in that the actual emission energy calculation means calculates the actual emission energy based on the charge voltage detected by the charge voltage detection means and the charge detected by the emission charge detection means. The electromagnetic valve driving device according to claim 3,
Charge acquisition means for acquiring the charge detected by the emitted charge detection means at a predetermined determination timing after the switch means is turned on;
It is determined whether or not the charge acquired by the charge acquisition means is greater than or equal to a preset abnormality determination charge threshold, and if it is not greater than or equal to the abnormality determination charge threshold, it is determined that the electromagnetic valve drive device is abnormal. First abnormality determination means to perform;
An electromagnetic valve driving device comprising: It is an electromagnetic valve drive device given in any 1 paragraph of Claims 1-4,
First detection means for detecting a charging voltage of the capacitor at a predetermined first detection timing before the start of the discharge period;
Second detection means for detecting a charging voltage of the capacitor at a predetermined second detection timing after the end of the discharge period;
It is determined whether or not a difference between the charging voltage detected by the first detecting means and the charging voltage detected by the second detecting means is equal to or greater than a preset abnormality determination voltage threshold, and is equal to or greater than the abnormality determination voltage threshold. A second abnormality determination means for determining that the electromagnetic valve driving device is abnormal when
An electromagnetic valve driving device comprising: