JP2016056745A - Control device for high-pressure pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a high-pressure pump, for suppressing a variation in the operation response time of a solenoid valve with the operation or not of a DC/DC converter.SOLUTION: A control device for a high-pressure pump 5 to supply fuel into an injector includes a charge control part 81 for allowing the operation of a DC/DC converter 52 which boosts a power supply voltage VB to charge a capacitor 51 so that a charge voltage VC of the capacitor 51 becomes a predetermined voltage, a discharge control part 87 for, at starting a drive period for driving a flow regulating valve (a solenoid valve) 7 of the high-pressure pump 5, turning a discharge switch 63 on to discharge a current from the capacitor 51 to a coil L7 of the flow regulating valve 7, a constant current control part 89 for turning a constant current switch 43 on/off so that a constant current flows in the coil L7 for a time from finishing the discharge to finishing the drive period, and means 103 for changing a threshold value for the current which is used for the constant current control part 89 to turn the constant current switch 43 on/off, depending on the operation or not of the DC/DC converter 52.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a high-pressure pump control device that controls a high-pressure pump.

  In a diesel engine or an in-cylinder direct injection gasoline engine, fuel is directly injected from an injector into a cylinder. Therefore, a high-pressure pump that pressurizes the fuel with the driving force of the engine and supplies the fuel to the injector is used. The high-pressure pump includes an electromagnetic valve for controlling the fuel discharge amount (see, for example, Patent Document 1).

JP 2010-174768 A

  The inventor of the present invention considers that the solenoid valve of the high-pressure pump is also energized and driven in the same manner as the electromagnetic injector. In this case, the configuration and operation of the control device that controls the high-pressure pump are, for example, become that way.

  The control device boosts the power supply voltage (battery voltage) from the vehicle battery to charge the capacitor, and charging control to operate the DC / DC converter so that the charging voltage of the capacitor becomes a predetermined voltage. Means. The control device discharges the capacitor from the capacitor to the coil of the solenoid valve at the start of driving the solenoid valve of the high-pressure pump, and after the discharge from the capacitor ends until the drive period of the solenoid valve ends, A constant current flows from the voltage to the coil of the solenoid valve. In order to allow a constant current to flow through the coil, a constant current switch provided between the power supply line to which the power supply voltage is supplied and the coil is turned on / off. Specifically, when the current flowing through the coil (hereinafter also referred to as coil current) becomes smaller than the first threshold value, the constant current switch is turned on from the OFF state to increase the coil current, and the coil current is larger than the first threshold value. When the threshold value is greater than 2, the control for reducing the coil current is performed by turning off the constant current switch from ON to OFF.

  By the way, when the DC / DC converter is operated, a large current flows from the battery as a power source through the wiring to the DC / DC converter (specifically, the boosting coil and the switching element), so that the voltage drop is caused by the resistance of the wiring. Arise. Examples of the wiring include a wire harness that supplies a power supply voltage from a battery to the control device, and a printed wiring on a printed board that constitutes the control device. For this reason, a difference occurs in the power supply voltage supplied to the constant current switch when the DC / DC converter operates and when it does not operate. When a difference occurs in the power supply voltage, the slope of the coil current (especially, the slope when the constant current switch is turned on) changes during a constant current period in which a constant current flows through the solenoid valve coil. The average value of the coil current at (hereinafter referred to as the average current) changes. When the DC / DC converter is operating, compared to when the DC / DC converter is not operating, the power supply voltage supplied to the constant current switch decreases, and the average current during the constant current period decreases.

  Even when the capacitor is discharged from the capacitor to the coil of the solenoid valve, the valve body of the solenoid valve reaches the operating position accompanying the energization of the coil (hereinafter referred to as the energizing operation position). It is during the constant current period after the end. The energization operation position is a valve closing position if it is a normally open solenoid valve, and is a valve opening position if it is a normally closed solenoid valve.

  For this reason, when the average current in the constant current period changes due to the difference in power supply voltage depending on whether the DC / DC converter operates or not, the operation response time of the solenoid valve changes. The operation response time is the time from the start of energization to the coil (that is, from the start of the drive period) until the valve body of the solenoid valve reaches the energization operation position. When the operation response time of the solenoid valve changes, the control accuracy of the high-pressure pump (specifically, the control accuracy of the fuel discharge amount and the control accuracy of the pressure of the fuel supplied to the injector) decreases.

  In particular, in recent years, in the design of solenoid valves, reduction of current consumption considering the reduction in fuel consumption of vehicles has been regarded as important, and designs have been made to minimize the supply current to the solenoid valves. For this reason, the operation response time of the solenoid valve fluctuates sensitively to fluctuations in the coil current (in other words, fluctuations in the input energy to the coil).

  In view of the above, an object of the present invention is to suppress variations in the operation response time of the electromagnetic valve associated with the presence or absence of the operation of the DC / DC converter in the control device for the high-pressure pump.

  A high-pressure pump control device according to a first aspect of the invention includes a DC / DC converter that boosts a power supply voltage to charge a capacitor, a charge control unit that operates the DC / DC converter so that the capacitor charging voltage becomes a predetermined voltage, Is provided. The high-pressure pump control device is supplied with a discharge switch for connecting a capacitor and a power supply voltage upstream of a coil of an electromagnetic valve provided in the high-pressure pump in order to control the fuel discharge amount of the high-pressure pump. And a constant current switch provided between the power supply line and the upstream side of the coil. Furthermore, the high-pressure pump control device includes a discharge control means, a constant current control means, and a threshold value changing means.

The discharge control means discharges the capacitor to the coil by turning on the discharge switch at the start of the drive period of the solenoid valve.
The constant current control means turns on / off the constant current switch so that a constant current flows through the coil from the end of the discharge from the capacitor to the coil until the end of the driving period. The constant current control means controls the constant current switch to be turned on / off, and when the coil current (current flowing through the coil) becomes smaller than the first threshold, the constant current switch is turned on from off to increase the coil current. When the current becomes larger than the second threshold value, which is larger than the first threshold value, the constant current switch is turned off to turn on the coil current.

  Then, the threshold value changing means changes the first threshold value and the second threshold value used for on / off control of the constant current switch according to whether the DC / DC converter is operating. Specifically, the threshold value changing unit is configured to set the first threshold value and the second threshold value when the charge control unit operates the DC / DC converter, rather than when the charge control unit does not operate the DC / DC converter. Change to be a larger value.

  According to the high pressure pump control device, even if the DC / DC converter operates and the power supply voltage supplied to the constant current switch decreases, the first threshold value and the second threshold value are changed to large values. The average current is prevented from decreasing during a constant current period in which a constant current flows through the valve coil. Therefore, it is possible to suppress the variation in the operation response time of the solenoid valve due to the presence / absence of the operation of the DC / DC converter, and it is possible to prevent the control accuracy of the high-pressure pump from being lowered.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is a block diagram showing the structure of the fuel-injection control apparatus (ECU) of 1st Embodiment. FIG. 2 is a configuration diagram illustrating a detailed configuration of a constant current control unit while excluding a portion related to driving of an injector from the configuration of FIG. 1. It is explanatory drawing explaining operation | movement of each part in a pump current control part. In 1st Embodiment, it is explanatory drawing explaining an effect | action when a DC / DC converter does not operate | move. It is explanatory drawing explaining a comparative example. In 1st Embodiment, it is explanatory drawing explaining an effect | action when a DC / DC converter operate | moves. It is a block diagram showing the structure of the fuel-injection control apparatus (ECU) of 2nd Embodiment except the part regarding the drive of an injector. It is a flowchart showing the threshold value control process which the microcomputer of 2nd Embodiment performs.

Hereinafter, a fuel injection control device according to an embodiment to which the present invention is applied will be described with reference to the drawings.
[First Embodiment]
A fuel injection control device (hereinafter referred to as ECU) 11 of the first embodiment shown in FIG. 1 is fueled to each cylinder # 1 to # 4 of a multi-cylinder (4 cylinders in this example) engine mounted on a vehicle (automobile). 4 injectors I1 to I4, and a high pressure pump 5 that pressurizes the fuel supplied from the fuel tank with the driving force of the engine and supplies the pressurized fuel to the injectors I1 to I4. In the ECU 11, a power transistor (switching element) used as a switch is, for example, a MOSFET, but may be another type of transistor such as a bipolar transistor or IGBT (insulated gate bipolar transistor).

  Each of the injectors I1 to I4 includes coils L1 to L4. In the injector In (n is any one of 1 to 4), when the coil Ln is energized, a valve body (not shown) moves to the valve opening position (that is, opens), and fuel injection is performed. When energization of the coil Ln is stopped, the valve body returns to the original closed position (that is, closes), and fuel injection is stopped.

  Then, the ECU 11 controls the drive period of each of the injectors I1 to I4 (that is, the energization start timing and energization time for the coils L1 to L4), whereby the fuel injection timing and fuel injection to each cylinder # 1 to # 4 are controlled. Control the amount.

The high-pressure pump 5 includes a metering valve 7 that is an electromagnetic valve for controlling the fuel discharge amount. In this example, the metering valve 7 is a normally open type that is closed by energizing the coil L7.
The high-pressure pump 5 sucks / discharges fuel as a piston (plunger) reciprocates in the pump chamber, and the piston reciprocates in the pump chamber by a cam rotated by the cam shaft of the engine. Driven.

  In the high-pressure pump 5, the metering valve 7 is provided, for example, on the suction port side for sucking fuel from the fuel tank into the pump chamber. In the intake stroke of the high-pressure pump 5 (when the piston is lowered), the metering valve 7 is opened, so that fuel is drawn into the pump chamber, and the discharge stroke of the high-pressure pump 5 (when the piston is raised). , The metering valve 7 is energized and closed to discharge the fuel in the pump chamber. That is, the metering valve 7 discharges fuel from the high-pressure pump 5 by closing the valve during the period in which the piston of the high-pressure pump 5 is displaced from the bottom dead center toward the top dead center. The fuel discharged from the high-pressure pump 5 is supplied to a fuel reservoir for supplying fuel to the injectors I1 to I4 (for example, a part called a fuel delivery pipe for a gasoline engine and a part called a common rail for a diesel engine). Stored.

  Then, the ECU 11 controls the fuel discharge amount of the high-pressure pump 5 by controlling the drive period of the metering valve 7 (the energization period to the coil L7) in the discharge stroke of the high-pressure pump 5 to the injectors I1 to I4. The pressure of the supplied fuel (hereinafter also referred to as fuel pressure) is controlled. When increasing the fuel pressure, the ECU 11 increases the fuel discharge amount of the high-pressure pump 5 by increasing the drive start timing of the metering valve 7 in the discharge stroke of the high-pressure pump 5 and extending the valve closing period of the metering valve 7. increase. Conversely, when the fuel pressure is reduced, the fuel discharge amount of the high-pressure pump 5 is reduced by delaying the drive start timing of the metering valve 7 in the discharge stroke of the high-pressure pump 5 and shortening the valve closing period of the metering valve 7. Decrease.

  The upstream side and the downstream side of each of the coils L1 to L4 and L7 of the injectors I1 to I4 and the metering valve 7 are connected to the ECU 11 via in-vehicle wiring (so-called wire harness).

  The upstream side of the coil L7 is connected to the current output line 13 inside the ECU 11. Similarly, the upstream side of the coils L1 and L4 is connected to the common current output line 14 inside the ECU 11, and the upstream side of the coils L2 and L3 is connected to the common current output line 15 inside the ECU 11. It is connected.

  The injector I1 including the coil L1 and the injector I4 including the coil L4 are cylinders # 1 and # 4 of the cylinders # 1 to # 4, in which the fuel injection period may overlap. There are no cylinders). Similarly, the injector I2 provided with the coil L2 and the injector I3 provided with the coil L3 are also injectors of cylinders # 2 and # 3 whose fuel order is not continuous. The injectors I1 to I4 are divided into two groups from this viewpoint.

  The ECU 11 includes downstream switches 21 to 24 and 27 for selecting energization targets on the downstream side of the coils L1 to L4 and L7 and the ground line (0V line). In this example, the downstream switches 21 to 24 and 27 are N-channel MOSFETs. When the downstream switch 27 is turned on, it is possible to energize the coil L7 corresponding to the downstream switch 27. Similarly, when any of the downstream switches 21 to 24 is turned on, the coils L1 to L4 corresponding to the turned-on downstream switches 21 to 24 can be energized. Since the downstream switches 21 to 24 are also switches that select a cylinder to be injected with fuel, they are called cylinder selection switches.

  Further, a resistor for detecting a current flowing in the coil L7 is provided between a terminal (in this example, a source) opposite to the terminal on the coil L7 side (in this example, the drain) of the downstream switch 27 and the ground line. 33 is provided. A resistor for detecting a current flowing in the coils L1 and L4 between a terminal (source) opposite to the terminals (drains) on the coils L1 and L4 side of the downstream switches 21 and 24 and the ground line. 34 is provided. Similarly, between the terminals (sources) opposite to the terminals (drains) on the coils L2 and L3 side of the downstream switches 22 and 23 and the ground line, the currents flowing through the coils L2 and L3 are detected. A resistor 35 is provided.

  The ECU 11 is connected to a power supply line 41 to which a power supply voltage (battery voltage that is a voltage of a plus terminal of the vehicle-mounted battery in this embodiment) VB is connected, and one output terminal (source in this example) is connected to the power supply line 41. The three constant current switches 43, 44, 45 are provided. In this example, the constant current switches 43, 44, 45 are P-channel MOSFETs.

  The constant current switch 43 is a switching element that is turned on / off in order to flow a constant current through the coil L7 using the power supply voltage VB as a power source. Similarly, the constant current switch 44 is a switching element for causing a constant current to flow through either of the coils L1 and L4 using the power supply voltage VB as a power source, and the constant current switch 45 is a coil using the power source voltage VB as a power source. This is a switching element for supplying a constant current to either L2 or L3.

  For this reason, the ECU 11 includes a backflow prevention diode D1 having an anode connected to the other output terminal (drain in this example) of the constant current switch 43 and a cathode connected to the current output line 13, and an anode connected to the ground line. The anode is connected to the other output terminal (drain) of the constant current switch 44, the cathode is connected to the current output line 14, and the cathode is connected to the current output line 13. The reverse-current-preventing diode D3, the current-returning diode D4 whose anode is connected to the ground line and the cathode is connected to the current output line 14, and the other output terminal (drain) of the constant-current switch 45 are anodes. Are connected, and a cathode D5 having a cathode connected to the current output line 15; Node is connected to the ground line, the cathode comprises a diode D6 for current flywheel which is connected to the current output line 15.

  The ECU 11 further includes a capacitor 51 in which energy discharged in the coils L1 to L4 and L7 is stored, and a DC / DC converter 52 as a charging circuit that boosts the power supply voltage VB and charges the capacitor 51.

  The DC / DC converter 52 is a boosting coil 53 having one end connected to the power supply line 41 and a boosting switching element provided on a path between the other end of the coil 53 and the ground line. A switch 54, a current detection resistor 55 provided between the boost switch 54 and the ground line, the other end of the coil 53, and an output terminal (drain in this example) of the boost switch 54 on the coil 53 side. And a backflow preventing diode 56 having an anode connected to a current path connecting the two. In this example, the boost switch 54 is an N-channel MOSFET.

  The capacitor 51 is provided on a path between the cathode of the diode 56 and the ground line. Further, a resistor 57 for detecting a current flowing through the capacitor 51 is provided on the downstream side of the capacitor 51. The capacitor 51 is an aluminum electrolytic capacitor, for example, but may be another type of capacitor.

  In the DC / DC converter 52, when the boost switch 54 is turned on / off, a flyback voltage (back electromotive voltage) higher than the power supply voltage VB is generated at the connection point between the coil 53 and the boost switch 54. The capacitor 51 is charged through the diode 56 by the flyback voltage. For this reason, the capacitor 51 is charged with a voltage higher than the power supply voltage VB.

  Then, the ECU 11 connects the positive electrode side of the capacitor 51 to the current output line 13 (that is, to the upstream side of the coil L7), and the positive electrode side of the capacitor 51 to the current output line 14 (that is, the coil L1). , L4) and a discharge switch 64 for connecting the positive side of the capacitor 51 to the current output line 15 (that is, upstream of the coils L2, L3). In this example, the discharge switches 63, 64, 65 are P-channel MOSFETs.

  Further, the ECU 11 controls the microcomputer 71, the power supply circuit 72 that generates and outputs a constant voltage (for example, 5 V) VD that is the operating voltage of the microcomputer 71 from the power supply voltage VB, and the DC / DC converter 52. And a drive control circuit 73 for controlling the switches 21 to 24, 27, 43 to 45, and 63 to 65 in accordance with a drive signal output from the microcomputer 71.

  The microcomputer 71 includes a CPU 75 that executes a program, a ROM 76 that stores programs, fixed data, and the like, a RAM 77 that stores calculation results and the like by the CPU 75, an A / D converter (not shown), and the like. Although not shown, the microcomputer 71 includes a crank angle signal that generates a pulse edge every time the crankshaft of the engine rotates by a predetermined angle, a signal that represents the accelerator opening by the driver of the vehicle, A signal indicating the cooling water temperature is input.

  The microcomputer 71 drives the metering valve drive signal, which is a drive signal for driving the metering valve 7, and the injectors I1 to I4, based on the operating state of the engine detected by the various signals input. An injector drive signal, which is a drive signal for performing the operation, is output to the drive control circuit 73.

  The metering valve drive signal energizes the coil L7 of the metering valve 7 only when the level of the signal is an active level (eg, high in this embodiment) (in other words, the metering valve 7 is energized and driven). It has a meaning. For this reason, the microcomputer 71 sets a driving period of the metering valve 7 (hereinafter also referred to as a metering valve driving period) based on engine operation information, and outputs a metering valve driving signal only during the set driving period. It can be said that it is high. This is the same for each injector drive signal.

  The drive control circuit 73 is, for example, an IC. The drive control circuit 73 controls the charge control unit 81 that controls the DC / DC converter 52 (specifically, the step-up switch 54), the downstream switch 27, the constant current switch 43, and the discharge switch 63. The pump current control unit 82 for controlling the current flowing through the coil L7 (that is, the drive current of the metering valve 7), the downstream switches 21 to 24, the constant current switches 44 and 45, and the discharge switches 64 and 65 are provided. And an injector current control unit 83 that controls currents that flow through the coils L1 to L4 (that is, drive currents of the injectors I1 to I4).

  In the ECU 11, a circuit constituted by the downstream switches 21 to 24, resistors 34 and 34, constant current switches 44 and 45, diodes D3 to D6, and discharge switches 64 and 65 drives the injectors I1 to I4. This is an injector drive circuit 66 for this purpose. The injector current control unit 83 is a part that controls the injector drive circuit 66.

  In the ECU 11, resistors 91, 92, 93 are connected between the gates of the constant current switches 43, 44, 45 and the power supply line 41, respectively, and further, the gates of the constant current switches 43, 44, 45 are connected. Are connected to one ends of resistors 94, 95, and 96, respectively. The pump current control unit 82 of the drive control circuit 73 turns on the constant current switch 43 by setting the other end of the resistor 94 to low (in this example, the potential of the ground line). Similarly, the injector current control unit 83 of the drive control circuit 73 turns on the constant current switch 44 by setting the other end of the resistor 95 to low, and turns the other end of the resistor 96 low to set the constant current. Switch 45 is turned on.

Next, the charge control unit 81 of the drive control circuit 73 will be described.
The charge control unit 81 includes a charge drive control circuit 81a and a charge switch drive circuit 81b.

  When the charge drive control circuit 81a detects the charge voltage VC of the capacitor 51 and determines that the charge voltage VC is equal to or lower than the charge lower limit threshold, the charge drive control circuit 81a outputs the charge command signal until it is determined that the charge voltage VC is equal to or higher than the charge upper limit threshold. Output (see the second and third stages in FIG. 6). The charge command signal is a signal indicating that the DC / DC converter 52 is operated to charge the capacitor 51, and is a high active signal in this example. The charging lower limit threshold is a value lower by a predetermined value (for example, 5% of VT) than the target value (for example, 60 V) VT of the charging voltage VC higher than the power supply voltage VB, and the charging upper limit threshold is predetermined than the target value VT. The value is higher by a value (for example, 5% of VT).

  Although not shown, the ECU 11 includes two voltage dividing resistors that divide the charging voltage VC at a predetermined ratio and input the divided voltage to the drive control circuit 73. The charging drive control circuit 81a includes: Based on the voltage divided by the voltage dividing resistor, the charging voltage VC is detected.

  The charge switch drive circuit 81b stops the operation of the DC / DC converter 52 when the charge drive control circuit 81a does not output a charge command signal (in this example, the charge command signal is low). (In other words, the step-up switch 54 is kept off).

  On the other hand, the charge switch drive circuit 81b operates the DC / DC converter 52 while the charge drive control circuit 81a outputs a charge command signal (in this example, while the charge command signal is high). (That is, the boosting switch 54 is turned on / off). For example, the charging switch driving circuit 81b repeats the following operation as the charging control for operating the DC / DC converter 52.

  That is, the charging switch drive circuit 81b turns on the boost switch 54 and then the current detected by the voltage generated in the resistor 55 (that is, the current flowing through the coil 53 via the boost switch 54) is turned off by a predetermined amount. When increasing to the switching threshold, the boosting switch 54 is turned off. After that, when the current detected by the voltage generated in the resistor 57 (that is, the charging current flowing into the capacitor 51) decreases to a predetermined ON switching threshold, the boosting switch 54 is turned on again. As another example, for example, when the boost switch 54 is turned on and the current flowing through the coil 53 is increased to the off switching threshold, the charging switch drive circuit 81b turns off the boost switch 54 for a predetermined off time. May be turned on again.

Next, the pump current control unit 82 of the drive control circuit 73 will be described.
The pump current control unit 82 includes a downstream side switch control unit 85, a discharge control unit 87, and a constant current control unit 89.

  As shown in FIG. 3, when the metering valve drive signal output from the microcomputer 71 becomes high, the downstream side switch control unit 85 corresponds to the coil L7 while the metering valve drive signal is high. The downstream switch 27 is turned on. When the downstream switch 27 is turned on, a current can be passed through the coil L7. In the following description and FIG. 3 and other figures to be described later, “pump drive current” refers to the coil current (drive current) of the metering valve 7.

  As shown in FIG. 3, the discharge controller 87 turns on the discharge switch 63 when the metering valve drive signal becomes high. Then, the positive electrode side of the capacitor 51 is connected to the upstream side of the coil L7, and the capacitor 51 discharges to the coil L7. By this discharge, energization of the coil L7 is started. The discharge controller 87 detects the voltage generated in the resistor 33 as a pump drive current (coil current) after turning on the discharge switch 63, and the pump drive current has reached the target maximum value ip of the discharge current. Is detected, the discharge switch 63 is turned off. When the discharge switch 63 is turned off, the discharge from the capacitor 51 to the coil L7 is completed.

  Thus, at the start of the driving period of the metering valve 7, the energy stored in the capacitor 51 is discharged to the coil L7. In this example, the discharge current from the capacitor 51 to the coil L7 until reaching the target maximum value ip is a so-called peak current for speeding up the closing of the metering valve 7. For example, the discharge switch 63 may be turned on for a certain period of time.

When the metering valve drive signal becomes high, the constant current control unit 89 performs constant current control for making the pump drive current a constant current smaller than the target maximum value ip.
More specifically, the constant current control unit 89 detects a voltage generated in the resistor 33 as a pump drive current. Then, as shown in FIG. 3, when the pump drive current becomes smaller than the first threshold value iL, the constant current control unit 89 turns on the constant current switch 43 from OFF to increase the pump drive current. Constant current control is performed in which the constant current switch 43 is turned off to decrease the pump drive current when the second threshold iH is greater than the first threshold iL. When the constant current switch 43 is on, a current flows from the power supply line 41 side to the coil L7 via the constant current switch 43 and the diode D1, and when the constant current switch 43 is off, the ground line side passes through the diode D2. The current flows back to the coil L7. The magnitude relationship among the first threshold value iL, the second threshold value iH, and the target maximum value ip is “ip>iH> iL” as shown in FIG.

  During the period from the end of the discharge from the capacitor 51 to the coil L7 until the end of the driving period of the metering valve 7 (hereinafter referred to as a constant current period), a constant current is supplied to the coil L7 by the constant current control described above. The constant current switch 43 is turned on / off so as to flow. And the average value of the pump drive current in the constant current period is a value between the first threshold value iL and the second threshold value iH. Further, although the closing of the metering valve 7 is accelerated by the discharge from the capacitor 51 to the coil L7, the metering valve 7 is completely closed (that is, the valve body of the metering valve 7 reaches the valve closing position). It is during the constant current period.

  As shown in FIG. 3, the constant current switch 43 has a period from when the metering valve drive signal becomes high until the pump drive current reaches the second threshold value iH due to the discharge from the capacitor 51. It is turned on by constant current control. However, in that case, even if the constant current switch 43 is turned on, a current flows from the capacitor 51 to the coil L7 instead of from the power supply line 41 side. This is because the charging voltage VC is higher than the power supply voltage VB. Therefore, the constant current control unit 89 may start the constant current control after the discharge switch 63 is turned off (that is, after the discharge of the capacitor 51 is completed).

  As shown in FIG. 3, when the metering valve drive signal goes low, the constant current control unit 89 ends the constant current control and keeps the constant current switch 43 off. At that time, since the downstream switch 27 is also turned off, the energization to the coil L7 is stopped, the metering valve 7 is opened, and the fuel discharge of the high-pressure pump 5 is completed.

  On the other hand, the injector current control unit 83 of the drive control circuit 73 also controls the drive currents of the injectors I1 to I4 by the same operation as the pump current control unit 82. The operation will be described in comparison with the operation of the pump current control unit 82 when the metering valve drive signal becomes high.

  For example, when the drive signal for driving the injector I1 among the drive signals output from the microcomputer 71 becomes high, the injector current control unit 83 is not the downstream switch 27 but the downstream side corresponding to the coil L1. Switch 21 is turned on. Then, not the discharge switch 63 but the discharge switch 64 is turned on, and the capacitor 51 discharges the coil L1. Further, by turning on / off the constant current switch 44 instead of the constant current switch 43, a constant current flows through the coil L1. Further, for example, when the drive signal for driving the injector I2 among the drive signals output from the microcomputer 71 becomes high, the injector current control unit 83 is not the downstream switch 27 but the downstream corresponding to the coil L2. The side switch 22 is turned on. Then, not the discharge switch 63 but the discharge switch 65 is turned on, and the capacitor 51 discharges to the coil L2. Further, by turning on / off the constant current switch 45 instead of the constant current switch 43, a constant current flows through the coil L2.

  By the way, in the present embodiment, the constant current control unit 89 of the pump current control unit 82 has a first threshold value iL and a second threshold value iH (hereinafter collectively referred to as the threshold value iL, iH) is variable. Next, the configuration and the like of the constant current control unit 89 will be described with reference to FIG. In FIG. 2, the portion related to driving of the injectors I <b> 1 to I <b> 4 is removed from the configuration of FIG. 1.

  As shown in FIG. 2, the constant current control unit 89 includes resistors R1 to R4, a comparator 101, an inverting circuit 102, and a transistor (in this example, an NPN transistor) 103 as a switch.

A constant voltage VD is supplied to one end of the resistor R1, and the resistor R2 is connected between the other end of the resistor R1 and the ground line.
The non-inverting input terminal (+ terminal) of the comparator 101 is connected to the connection point between the resistor R1 and the resistor R2, and the resistor R3 is a feedback resistor between the output terminal and the non-inverting input terminal of the comparator 101. Connected as. Further, the voltage generated in the resistor 33 is input to the inverting input terminal (− terminal) of the comparator 101 as a detected value of the pump drive current.

  A constant voltage VD is also supplied to one end of the resistor R4, and the other end of the resistor R4 is connected to a connection point between the resistor R1 and the resistor R2 via the transistor 103. In this example, the other end of the resistor R4 is connected to the collector of the transistor 103, and the emitter of the transistor 103 is connected to a connection point between the resistor R1 and the resistor R2. The above-described charge command signal output from the charge drive control circuit 81a of the charge control unit 81 is supplied to the base of the transistor 103 as a drive signal. For this reason, when the charge drive control circuit 81a outputs a charge command signal (that is, when the charge command signal goes high), the transistor 103 is turned on, and the resistor R4 is connected in parallel to the resistor R1.

  When the voltage at the inverting input terminal of the comparator 101 is Vm and the voltage at the non-inverting input terminal of the comparator 101 is Vp, when the metering valve drive signal from the microcomputer 71 is high, the output of the comparator 101 is It switches between high and low according to the magnitude relationship between Vm and Vp. When the metering valve drive signal from the microcomputer 71 is low, the output of the comparator 101 remains low regardless of the magnitude relationship between Vm and Vp. In this example, the signal output circuit in the comparator 101 is, for example, an open collector type. Therefore, the output terminal of the comparator 101 is connected to the constant voltage VB by a pull-up resistor (not shown) in order to output a high level. The resistance value of the pull-up resistor is set to a sufficiently large value as compared with the resistance values of the resistors R1 to R4.

  When the output of the comparator 101 is low, the inverting circuit 102 opens the opposite side of the resistor 94 from the resistor 91 side (in other words, the gate side of the constant current switch 43). Then, the constant current switch 43 is turned off. Further, when the output of the comparator 101 is high, the inverting circuit 102 turns on the constant current switch 43 by setting the side of the resistor 94 opposite to the side of the resistor 91 to low. The inverting circuit 102 can be constituted by, for example, a grounded NPN transistor.

In such a constant current control unit 89, when the metering valve drive signal from the microcomputer 71 is low, the output of the comparator 101 becomes low and the constant current switch 43 remains off.
On the other hand, when the metering valve drive signal is high, the output of the comparator 101 switches between high and low according to the magnitude relationship between Vm and Vp. That is, when Vm is smaller than Vp, the output of the comparator 101 becomes high and the constant current switch 43 is turned on. When Vm is larger than Vp, the output of the comparator 101 becomes low. Thus, the constant current switch 43 is turned off. Vm is a voltage obtained by multiplying the pump drive current by the resistance value of the resistor 33, and Vp corresponds to a value to be compared with the pump drive current by the comparator 101. Vp is provided with hysteresis depending on the output of the comparator 101.

  In the constant current control unit 89, when a resistor connected between the non-inverting input terminal of the comparator 101 and the constant voltage VD is referred to as a threshold variable resistor Rv, when the output of the comparator 101 is high, Vp is a voltage VH obtained by dividing the constant voltage VD by the threshold variable resistor Rv and the resistor R2. The resistance value of the pull-up resistor is sufficiently larger than the resistance values of the resistors R1 to R4, and is ignored here. Further, when the parallel resistance of the resistor R2 and the resistor R3 is described as “R2 // R3”, when the output of the comparator 101 is low, Vp is equal to the constant voltage VD and the threshold variable resistor Rv and “R2 // R3”. The voltage VL is divided by The voltage VL is smaller than the voltage VH, and the difference between the voltage VL and the voltage VH is the hysteresis of Vp.

  For this reason, in the constant current control unit 89, when the metering valve drive signal becomes high, the pump drive current is initially 0 and Vm is smaller than Vp, so the output of the comparator 101 becomes high, While the constant current switch 43 is turned on, Vp becomes the voltage VH (> VL).

  When Vm becomes larger than the voltage VH (= Vp) due to the increase of the pump drive current, the output of the comparator 101 is inverted to low, the constant current switch 43 is turned off, and Vp becomes the voltage VL. Thereafter, when Vm becomes smaller than the voltage VL (= Vp) due to a decrease in the pump driving current, the output of the comparator 101 is inverted to high, the constant current switch 43 is turned on, and Vp becomes the voltage VH. By repeating such an operation, the constant current switch 43 is turned on / off. A value obtained by dividing the voltage VL by the resistance value of the resistor 33 corresponds to the first threshold value iL, and a value obtained by dividing the voltage VH by the resistance value of the resistor 33 corresponds to the second threshold value iH.

  Here, when the charge command signal is low, the transistor 103 is turned off, so that the resistor R1 becomes the threshold variable resistor Rv. On the other hand, when the charge command signal is high, the transistor 103 is turned on, and the parallel resistance of the resistor R1 and the resistor R4 becomes the threshold variable resistor Rv. Therefore, when the charge command signal is high, the resistance value of the threshold variable resistor Rv is smaller than when the charge command signal is low. As a result, the voltage VL corresponding to the first threshold value iL and the first threshold value iL Both of the voltages VH corresponding to the two threshold values iH increase.

  The above is the variable mechanism of the threshold values iL and iH. That is, if the values obtained by dividing the voltage VL and the voltage VH when the transistor 103 is off by the resistance value of the resistor 33 are iL1 and iH1, each of the iL1 and iH1 is turned off by the transistor 103. Thresholds iL and iH. Further, when the values obtained by dividing the voltage VL and the voltage VH when the transistor 103 is turned on by the resistance value of the resistor 33 are iL2 and iH2, each of the iL2 and iH2 turns on the transistor 103. Thresholds iL and iH. Then, iL2 is larger than iL1, and iH2 is also larger than iH1 (see the “pump drive current” stage in FIG. 6).

  Next, the operation of the ECU 11 will be described with reference to FIGS. 4 to 6, the “power supply voltage” stage represents the power supply voltage VB supplied from the power supply line 41 to the constant current switch 43. The stage of “charging current” represents the charging current of the capacitor 51, and the fact that the charging current remains zero indicates that the DC / DC converter 52 is not operating. On the contrary, the pulsation of the charging current indicates that the DC / DC converter 52 is operating (that is, the boosting switch 54 is turned on / off).

  As shown in FIG. 4, when the metering valve drive signal becomes high and discharging from the capacitor 51 to the coil L7 is performed, the charging voltage VC decreases. However, if the charging voltage VC is equal to or lower than the charging lower limit threshold value. If not, the charge drive control circuit 81a does not output the charge command signal (does not make it high). For this reason, the DC / DC converter 52 does not operate. In the constant current control unit 89, the transistor 103 is not turned on, and the threshold values iL and iH in the constant current control are not changed from iL1 and iH1. In FIG. 4, the power supply voltage VB is lowered because the constant current control unit 89 performs the constant current control.

  Here, FIG. 5 shows, as a comparative example, an operation when the resistor R4 and the transistor 103 are not provided in the constant current control unit 89 (that is, when the threshold values iL and iH are fixed between iL1 and iH1). An example is shown.

  As shown in FIG. 5, when the metering valve drive signal becomes high and discharge from the capacitor 51 to the coil L7 is performed, and the charge voltage VC becomes equal to or lower than the charge lower limit threshold, the charge drive control circuit 81a Output charge command signal (high). Then, the DC / DC converter 52 operates and the capacitor 51 is charged. The DC / DC converter 52 operates until the charging voltage VC reaches the charging upper limit threshold.

  When the DC / DC converter 52 is operated, the DC / DC converter 52 (specifically, the coil 53 and the booster) is passed from a battery as a power source through a wire harness and a printed wiring on the printed circuit board of the ECU 11. A large current flows through the switch 54). For this reason, a voltage drop occurs due to the resistance of the wiring. Therefore, the power supply voltage VB supplied to the constant current switch 43 is lower than when the DC / DC converter 52 does not operate (FIG. 4).

  When the DC / DC converter 52 operates and the power supply voltage VB decreases, the slope of the pump drive current (coil current) when the constant current switch 43 is turned on gradually decreases during a constant current period in which a constant current flows through the coil L7. Become. For this reason, if the threshold values iL and iH in the constant current control are the same iL1 and iH1 as in FIG. 4, the average current (average value of the pump drive current) in a certain time is lowered. As a result, the operation response time from when the energization to the coil L7 is started (that is, from the start of the metering valve drive period) until the valve body of the metering valve 7 reaches the valve closing position becomes longer. Therefore, the control accuracy of the high-pressure pump 5 (specifically, the control accuracy of the fuel discharge amount) is lowered. Note that the operation response time in FIG. 4 is T1, whereas in the example of FIG. 5, the operation response time is T2 longer than T1.

  In contrast, in the ECU 11, as shown in FIG. 6, when the charge command signal becomes high and the DC / DC converter 52 operates, the transistor 103 is turned on and the resistance value of the threshold variable resistor Rv is turned on. Changes, the threshold values iL and iH change to iL2 and iH2 which are larger than iL1 and iH1. For this reason, a decrease in the average current during the constant current period is prevented, and accordingly, the operation response time of the metering valve 7 is prevented from becoming long.

  Therefore, according to ECU11, the dispersion | variation in the operation response time of the metering valve 7 with the presence or absence of the operation | movement of the DC / DC converter 52 can be suppressed, and the fall of the control accuracy of the high pressure pump 5 can be prevented. In this embodiment, as shown in FIG. 6, iL2 and iH2 are set so that the operation response time of the metering valve 7 when the DC / DC converter 52 operates is the same T1 as in FIG. ing.

Further, considering the case where the non-operation / operation of the DC / DC converter 52 is switched while the metering valve 7 is being driven, it is preferable that the threshold values iL and iH are changed quickly.
In this regard, the constant current control unit 89 is configured such that the threshold values iL and iH change when the resistance value of the threshold variable resistor Rv changes. In the ECU 11, the transistor 103 is turned on or off in accordance with the presence or absence of the charge command signal, thereby changing the resistance value of the threshold variable resistor Rv to change the thresholds iL and iH. That is, the threshold values iL and iH are changed by a hardware circuit (in this example, the transistor 103) without using software. Therefore, for example, the delay time from when the operation of the DC / DC converter 52 is started to when the threshold values iL and iH are changed can be advantageously shortened.

  Further, since the ECU 11 uses the energy accumulated in the capacitor 51 for driving the injectors I1 to I4, the possibility that the DC / DC converter 52 operates when the metering valve 7 is driven increases. For this reason, the configuration of the above embodiment is more effective.

[Second Embodiment]
Next, the ECU of the second embodiment will be described. In addition, about the component similar to 1st Embodiment, the same code | symbol as 1st Embodiment is used.

  As shown in FIG. 7, the ECU 111 according to the second embodiment differs from the ECU 11 according to the first embodiment in the following points <1> to <4>. In FIG. 7, as in FIG. 2, the portions related to driving of the injectors I <b> 1 to I <b> 4 are omitted.

  <1> The ECU 111 includes a drive control circuit 113 instead of the drive control circuit 73, and the drive control circuit 113 includes a pump current control unit 115 instead of the pump current control unit 82. The pump current control unit 115 includes a constant current control unit 117 instead of the constant current control unit 89.

The constant current control unit 117 includes a resistor R5 and a transistor (an NPN transistor in this example) 104 as compared with the constant current control unit 89 (FIG. 2).
Like the resistor R4 and the transistor 103, a constant voltage VD is supplied to one end of the resistor R5, and the other end of the resistor R5 is connected to a connection point between the resistor R1 and the resistor R2 via the transistor 104. It has become. Further, the resistance value of the resistor R5 is smaller than the resistance value of the resistor R4. A signal output from the microcomputer 71 is supplied to each base of the transistors 103 and 104 as a drive signal. That is, each of the transistors 103 and 104 is controlled to be turned on and off by the microcomputer 71.

  Here, as a state of the constant current control unit 117, a state in which both the transistors 103 and 104 are off is referred to as a first state, and a state in which only the transistor 103 among the transistors 103 and 104 is on is referred to as a second state. A state in which only the transistor 104 of the transistors 103 and 104 is on is referred to as a third state, and a state in which both the transistors 103 and 104 are on is referred to as a fourth state.

  In the constant current control unit 117, the above-described threshold variable resistor Rv decreases in the order of the first state, the second state, the third state, and the fourth state. Therefore, the threshold values iL and iH in the constant current control are switched to four values and increase in the order of the first state, the second state, the third state, and the fourth state.

  In the following description of the second embodiment, the threshold values iL and iH in the first state are described as iL1 and iH1, the threshold values iL and iH in the second state are described as iL2 and iH2, and The threshold values iL and iH in the three states are described as iL3 and iH3, and the threshold values iL and iH in the fourth state are described as iL4 and iH4. The transistor 103 is also referred to as a first transistor 103, and the transistor 104 is also referred to as a second transistor 104.

  <2> The ECU 111 includes two voltage dividing resistors 118 and 119 that divide the power supply voltage VB of the power supply line 41 (that is, the power supply voltage VB supplied to the constant current switch 43) at a predetermined ratio. The voltage Vb divided by the voltage dividing resistors 118 and 119 is smaller than the constant voltage VD and is input to the microcomputer 71. Then, the microcomputer 71 detects the power supply voltage VB by A / D converting the voltage Vb.

  <3> The microcomputer 71 also receives a charge command signal output from the charge drive control circuit 81a of the charge controller 81. The microcomputer 71 determines whether or not the DC / DC converter 52 is operating (in other words, whether or not charging control is being performed) depending on whether the charging command signal is high or low.

  <4> The microcomputer 71 executes the threshold control process shown in FIG. 8 at regular intervals, for example. Note that the processing executed by the microcomputer 71 is realized by the CPU 75 executing a program in the ROM 76.

As shown in FIG. 8, when starting the threshold control process, the microcomputer 71 determines whether or not the DC / DC converter 52 is operating based on the charge command signal in S210.
If the microcomputer 71 determines that the DC / DC converter 52 is not in operation, the microcomputer 71 turns off both the first and second transistors 103 and 104 in S220, and then ends the threshold control process. . In this case, the threshold values iL and iH in the constant current control are the smallest values (iL1, iH1) in the first state among the four values.

  If the microcomputer 71 determines that the DC / DC converter 52 is operating in S210, the microcomputer 71 determines whether or not the power supply voltage VB is equal to or higher than the first determination value V1 in S230. If the power supply voltage VB is greater than or equal to the first determination value V1, the process proceeds to S240.

  In S240, the microcomputer 71 turns on the first transistor 103 and turns off the second transistor 104. Then, the threshold control process is finished. In this case, the threshold values iL and iH in the constant current control are values (iL2 and iH2) in the second state having the third magnitude among the four values.

  If the microcomputer 71 determines in S230 that the power supply voltage VB is not equal to or higher than the first determination value V1, the microcomputer 71 determines in S250 that the power supply voltage VB is smaller than the first determination value V1. It is determined whether it is above.

  If the power supply voltage VB is equal to or higher than the second determination value V2, the microcomputer 71 turns off the first transistor 103 and turns on the second transistor 104 in S260. Then, the threshold control process is finished. In this case, the power supply voltage VB is in a range less than the first determination value V1 and greater than or equal to the second determination value V2, and the thresholds iL and iH in the constant current control are the second of the four values. The value in the third state (iL3, iH3).

  If the microcomputer 71 determines in S250 that the power supply voltage VB is not equal to or higher than the second determination value V2, the microcomputer 71 turns on both the first and second transistors 103 and 104 in S270, and then Then, the threshold control process ends. In this case, the power supply voltage VB is less than the second determination value V2, and the threshold values iL and iH in the constant current control are the largest values (iL4 and iH4) in the fourth state among the four values.

  That is, in the ECU 111, when the DC / DC converter 52 is operating (S210: YES), the microcomputer 71 changes the threshold values iL and iH in the constant current control according to the power supply voltage VB of the power supply line 41. (S230 to S270). Specifically, the threshold values iL and iH are changed to larger values as the power supply voltage VB is lower.

For this reason, it is possible to further suppress variation in the operation response time of the metering valve 7 due to the decrease in the power supply voltage VB, and to improve the effect of preventing the control accuracy of the high-pressure pump 5 from decreasing.
In the constant current control unit 117, there are two resistance value changing circuits including resistors (R4 and R5 in the above example) and transistors (103 and 104 in the above example) connected in parallel with the resistor R1. Not limited, three or more may be provided.

[Other Embodiments]
<Modification 1>
For example, in the constant current control unit 89 (FIG. 2) of the first embodiment, a resistance value changing circuit including the resistor R4 and the transistor 103 may be provided in parallel with the resistor R2 instead of in parallel with the resistor R1. . In this case, contrary to the first embodiment, when the charge command signal goes from low to high, the transistor 103 is turned off and the thresholds iL and iH are increased. Such a modification can be similarly applied to the constant current control unit 117 (FIG. 7) of the second embodiment.

<Modification 2>
In the second embodiment, an arbitrary voltage output from the D / A converter by the microcomputer 71 becomes an input voltage (Vp) to the non-inverting input terminal of the comparator 101, and an output voltage from the microcomputer 71 You may comprise so that the threshold value iL and iH can be changed arbitrarily. In that case, for example, the microcomputer 71 monitors the output of the comparator 101 and changes the output voltage between when the output of the comparator 101 is high and when it is low, thereby providing a hysteresis of Vp. good. In this case, the resistors R1 to R5 and the transistors 103 and 104 are not necessary.

As mentioned above, although embodiment of this invention was described, this invention can take a various form, without being limited to the said embodiment. The above-mentioned numerical values are also examples, and other values may be used.
For example, the metering valve 7 of the high-pressure pump 5 may be a normally closed electromagnetic valve. Moreover, in ECU11,111 of each said embodiment, you may comprise so that the capacitor | condenser different from the capacitor | condenser 51 may be used for the drive of the injectors I1-I4.

  In addition, the functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified by the wording described in the claims are embodiments of the present invention. In addition to the ECU described above, the present invention is realized in various forms such as a system including the ECU as a constituent element, a program for causing a computer to function as the ECU, a medium storing the program, and a control method for the high-pressure pump. You can also

  DESCRIPTION OF SYMBOLS 5 ... High pressure pump, 7 ... Metering valve, L7 ... Coil, 41 ... Power supply line, 43 ... Constant current switch, 51 ... Capacitor, 52 ... DC / DC converter, 63 ... Discharge switch, 71 ... Microcomputer, 81 ... Charge control unit, 87 ... Discharge control unit, 89, 117 ... Constant current control unit, 103, 104 ... Transistor

Claims (3)

A high-pressure pump control device that controls a high-pressure pump (5) that pressurizes fuel by a driving force of an engine and supplies the fuel to an injector,
A DC / DC converter (52) for boosting the power supply voltage and charging the capacitor (51);
Charging control means (81) for operating the DC / DC converter so that a charging voltage of the capacitor becomes a predetermined voltage;
A discharge switch (63) for connecting the capacitor to the upstream side of a coil (L7) of a solenoid valve (7) provided in the high-pressure pump for controlling the fuel discharge amount of the high-pressure pump;
A constant current switch (43) provided between a power supply line (41) to which the power supply voltage is supplied and the upstream side of the coil;
A discharge control means (87) for discharging the coil from the capacitor by turning on the discharge switch at the start of the driving period of the solenoid valve;
Constant current control means (89) for turning on / off the constant current switch so that a constant current flows through the coil from the end of the discharge from the capacitor to the coil until the end of the drive period. 117), and
The constant current control means controls the constant current switch to be turned on / off, and turns on the constant current switch from off to turn on the coil current when a coil current, which is a current flowing through the coil, becomes smaller than a first threshold. When the coil current becomes larger than a second threshold value that is larger than the first threshold value, the constant current switch is turned off from turning on, and the coil current is decreased.
Furthermore, the high-pressure pump control device
The first threshold value and the second threshold value when the charge control unit is operating the DC / DC converter, rather than when the charge control unit is not operating the DC / DC converter, Providing a threshold value changing means (103, 104, 71, S210 to S270) for changing the value so as to become a large value;
High pressure pump control device characterized by In the high-pressure pump control device according to claim 1,
The constant current control means is configured such that when the resistance value of the resistance (Rv) changes, the first threshold value and the second threshold value change,
The charge control means is configured to output a signal indicating that the DC / DC converter is operated when the DC / DC converter is operated.
The threshold change means (103) is supplied with the signal from the charge control means, and changes the resistance value of the resistor according to the presence or absence of the signal, thereby changing the first threshold value and the second threshold value. To be a circuit that
High pressure pump control device characterized by In the high-pressure pump control device according to claim 1,
The threshold value changing means (103, 104, 71, S210 to S270)
When the charge control means is operating the DC / DC converter, the first threshold value and the second threshold value are changed according to the power supply voltage of the power supply line (S230 to S270),
High pressure pump control device characterized by

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