JP2014009627A - Fuel injection device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device of an internal combustion engine which stabilizes a power source voltage of a control device without using a large-capacity capacitor, in a fuel injection device provided with a circuit for boosting a battery output voltage.SOLUTION: A fuel injection valve driving part includes a boosting circuit 10, a CPU 11, a driving circuit 12, a power source circuit 13 and capacitors C21, C22, wherein a control signal is supplied from the CPU 11 to FETs Q1 to Q3 and the boosting circuit 10. The boosting circuit 10 is a circuit which boosts an output voltage VB of a battery 6 to output a first power source voltage VS1, and includes a series circuit of a coil L11 and a diode D11, a Zener diode D12, a capacitor C11, an FET Q11 and a driving circuit 21. The Zener diode D12, when a battery output voltage VB is temporarily reduced, is conducted, supplies a charge accumulated on the capacitor C11 to a battery output terminal and suppresses the lowering of the battery output voltage VB.

Description

  The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to a fuel injection device that directly injects fuel into a combustion chamber using a fuel injection valve.

  Patent Document 1 discloses a so-called direct injection fuel injection device in which fuel is directly injected into a combustion chamber of an internal combustion engine by a fuel injection valve. In this direct injection fuel injection device, a large amount of electric power is required to open the fuel injection valve. Therefore, the battery voltage is boosted to a predetermined high voltage, and the boosted voltage is used as a drive voltage to the solenoid of the fuel injection valve. Supplied.

JP 2005-163625 A

  In an internal combustion engine mounted on a vehicle, a battery is used as a power source, and when starting the engine, it is necessary to supply fuel by a fuel injection valve while driving a starter motor, so the battery output voltage temporarily decreases. . On the other hand, since it is necessary to stabilize the power supply voltage of the control device that performs the fuel injection control by eliminating the influence of such a temporary decrease in the battery output voltage, a large-capacitance capacitor is used as a power supply circuit for the control device. Used to increase costs.

  The present invention has been made paying attention to this point, and an object of the present invention is to stabilize a power supply voltage of a control device without using a large-capacity capacitor in a fuel injection device including a circuit for boosting a battery output voltage. And

  In order to achieve the above object, a first aspect of the present invention is directed to a fuel injection valve (2) for directly injecting fuel into a combustion chamber of an internal combustion engine (1), and fuel injection control means for controlling the operation of the fuel injection valve. A battery (6), a first power supply circuit (10) connected to the battery, boosting the battery output voltage (VB) and outputting a first power supply voltage (VS1), and connected to the battery (6) And a second power supply circuit (13) for stabilizing the battery output voltage (VB) and outputting a second power supply voltage (VS2) lower than the battery output voltage, from the first power supply circuit (10) to the In the fuel injection device for an internal combustion engine, configured to supply driving power for the fuel injection valve (2) and supply a power supply voltage for the fuel injection control means from the second power supply circuit (13). 1 power circuit (10 Includes a series circuit of a coil (L11) and a diode (D11), a capacitor (C11), and a switching element (Q11) connected to a connection part of the coil and the diode, and one end of the series circuit is the battery. (6), the other end of the series circuit is connected to one end of the capacitor (C11), the other end of the capacitor (C11) is grounded, and the first end of the capacitor (C11) is connected to the first end. A power supply voltage (VS1) is output, and a Zener diode (D12) is disposed between one end of the capacitor (C11) and an output terminal of the second power supply circuit (13), and the Zener diode ( The anode of D12) is connected to one end of the series circuit, and the cathode of the Zener diode (D12) is connected to the other end of the series circuit. It is characterized in that is.

  The invention according to claim 2 is a fuel injection valve for directly injecting fuel into the combustion chamber of the internal combustion engine, fuel injection control means for controlling the operation of the fuel injection valve, a battery (6), and a battery connected to the battery. The battery output voltage (VB) is boosted to output a first power supply voltage (VS1) and connected to the battery (6), and the battery output voltage (VB) is stabilized. And a second power supply circuit (13) that outputs a second power supply voltage (VS2) lower than the battery output voltage, and supplies driving power for the fuel injection valve (2) from the first power supply circuit (10). In addition, in the fuel injection device for an internal combustion engine configured to supply the power supply voltage of the fuel injection control means from the second power supply circuit (13), the first power supply circuit (10) includes a coil (L11). And Daio A series circuit of (D11), a capacitor (C11), and a switching element (Q11) connected to the connection portion of the coil and diode, one end of the series circuit is connected to the battery (6), The other end of the series circuit is connected to one end of the capacitor (C11), the other end of the capacitor (C11) is grounded, and the first power supply voltage (VS1) is output from one end of the capacitor (C11). The Zener diode (D12) is disposed between one end of the capacitor (C11) and the output terminal of the second power supply circuit (13), and the anode of the Zener diode (D12) is the second electrode. Connected to the output terminal of the power supply circuit (13), the cathode of the Zener diode (D12) is connected to one end of the capacitor (C11). It is characterized in.

  According to the first aspect of the present invention, the breakdown voltage of the Zener diode is appropriately set, specifically, the breakdown voltage of the Zener diode is obtained by subtracting the normal voltage value of the battery output voltage from the first power supply voltage. By setting it to a slightly larger value, the Zener diode can be turned on only when the battery output voltage drops below the normal voltage value, and the drop in the battery output voltage can be offset by the boosted first power supply voltage. As a result, the capacitance of the voltage stabilizing capacitor used in the second power supply circuit can be made smaller than before, and the cost can be reduced. Further, when a power switch is provided between the battery output terminal and the first power supply circuit so that the power switch is turned off before the engine is started and turned on at the start of the engine, the first power circuit is turned on when the power switch is turned on. Since the charging current of the capacitor is quickly supplied by bypassing the coil, the rise of the first power supply voltage can be accelerated and a quick start can be achieved.

  According to the second aspect of the present invention, the breakdown voltage of the Zener diode is appropriately set, specifically, the breakdown voltage of the Zener diode is subtracted from the normal voltage value of the second power supply voltage from the first power supply voltage. By setting the value slightly larger than the value, the Zener diode is turned on only when the second power supply voltage is lower than the normal voltage value, and the decrease in the battery output voltage is caused by the boosted first power supply voltage. Can be prevented. As a result, the capacitance of the voltage stabilizing capacitor used in the second power supply circuit can be made smaller than before, and the cost can be reduced.

1 is a diagram illustrating an internal combustion engine and a fuel injection device thereof according to an embodiment of the present invention. It is a circuit diagram for demonstrating the structure (1st Embodiment) of the fuel injection valve drive part contained in the electronic control unit shown in FIG. It is a circuit diagram for demonstrating the structure (2nd Embodiment) of the fuel injection valve drive part contained in the electronic control unit shown in FIG.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 shows an internal combustion engine (hereinafter referred to as “engine”) 1 and its fuel injection device according to an embodiment of the present invention. A four-cylinder engine 1 has four fuel injection valves 2 corresponding to each cylinder. I have. The fuel injection valve 2 injects fuel directly into the combustion chamber of the engine 1.

  A starter motor 4 is provided so as to be able to drive the crankshaft 3 of the engine 1, and the starter motor 4 is connected to a battery 6 via a switch circuit 7. Driving power is supplied from the battery 6 to the starter motor 4. The switch circuit 7 is connected to an electronic control unit (hereinafter referred to as “ECU”) 5, and on / off control is performed by the ECU 5.

  Each of the four fuel injection valves 2 is connected to the ECU 5, and its operation is controlled by the ECU 5. A battery 6 is connected to the ECU 5, and electric power for operating the ECU 5 and electric power for driving the fuel injection valve 2 are supplied from the battery 6.

  FIG. 2 is a circuit diagram for explaining the configuration of the fuel injection valve drive unit included in the ECU 5, and shows a circuit configuration for supplying a drive current to the solenoid L1 that drives the fuel injection valve 2 of one cylinder. . The circuits for driving the fuel injection valves of the other cylinders are similarly configured.

  2 includes field effect transistors (hereinafter referred to as “FETs”) Q1 and Q2 as switching elements for switching a power supply voltage supplied to one end of the solenoid L1, and the other end of the solenoid L1 and the ground. FET Q3 as a switching element for switching between connection and non-connection, diodes D1 to D3, resistor R1, booster circuit 10, CPU 11, drive circuit 12, power supply circuit 13, capacitors C21 and C22, The control signal is supplied from the CPU 11 to the FETs Q1 to Q3 and the booster circuit 10.

  The booster circuit 10 is a circuit that boosts the output voltage VB (for example, 13V) of the battery 6 and outputs a first power supply voltage VS1 (for example, 40V), and is a series circuit of a coil L11 and a diode D11 (hereinafter, “LD series circuit”). A Zener diode D12, a capacitor C11, resistors R11 and R12, an FET Q11, and a drive circuit 21. More specifically, one end of the LD series circuit is connected to the battery 6, the other end of the LD series circuit is connected to one end of the capacitor C11, the other end of the capacitor C11 is grounded, and the first power source is connected from one end of the capacitor C11. The Zener diode D12 is arranged in parallel with the LD series circuit, and the anode of the Zener diode D12 is connected to one end of the LD series circuit (connecting portion with the battery 6). The cathode is connected to the other end of the LD series circuit (the output terminal of the booster circuit 10).

  As the Zener diode D12, a predetermined voltage value VZ1 (for example, about 29V) whose breakdown voltage is slightly larger than a value (27V) obtained by subtracting the normal voltage value VBN (13V) of the battery output voltage VB from the first power supply voltage VS1 (40V). Use what is. By using such a Zener diode D12 having the breakdown voltage VZ1, the circuit shown in FIG. 2 operates as follows.

  When battery output voltage VB is in the vicinity of normal voltage value VBN, Zener diode D12 is turned off. On the other hand, for example, when starting the engine for operating the starter motor 34, when the battery output voltage VB decreases and the reverse bias voltage across the Zener diode D12 exceeds the breakdown voltage VZ1, the Zener diode D12 conducts and the capacitor C11 The electric charge stored in is supplied in the direction of the battery output terminal, and can be stabilized by suppressing a decrease in the battery output voltage VB. As a result, it is possible to use capacitors C21 and C22 having relatively small capacities, and the cost can be reduced.

  The CPU 11 controls the duty ratio DTY of the on / off switching signal SSW of the FET Q11 output from the output terminal DCSW according to the feedback voltage VFB input to the input terminal VIN. Specifically, the duty ratio DTY is controlled so that the feedback voltage VFB matches the target voltage VFBX, and the target voltage VFBX is set to a value corresponding to a state in which the first power supply voltage VS1 is 40V, for example.

  The power supply circuit 13 stabilizes the battery output voltage VB, outputs a second power supply voltage VS2 (for example, 6V), and supplies it to the CPU 11 as a power supply voltage. Capacitors C21 and C22 are provided to prevent the second power supply voltage VS2 from temporarily decreasing, particularly when the engine that starts the starter motor 4 is started.

  The first power supply voltage VS1 is supplied to one end of the solenoid L1 through the FET Q2 and the diode D1, and the second power supply voltage VS2 is supplied to one end of the solenoid L1 through the FET Q1. The other end of the solenoid L1 is connected to the ground via the FET Q3 and the resistor R1, and the diode D3 is disposed between the other end of the solenoid L1 and the output of the booster circuit 10.

  The second voltage control signal SDVS2 and the first voltage control signal SDVS1 output from the output terminals HSW1 and HSW2 of the CPU 11 are supplied to the gates of the FETs Q1 and Q2 via the drive circuit 12, and are output from the output terminal LSW of the CPU 11. The low-side control signal SDL is supplied to the gate of the FET Q3 through the drive circuit 13. The CPU 11 controls the drive current supplied to the solenoid L1, which is good for on / off control of the FETs Q1 to Q3, and opens and closes the fuel injection valve 2.

  As described above, the fuel injection valve drive unit shown in FIG. 2 is characterized in that the Zener diode D12 is provided. When the battery output voltage VB is in the vicinity of the normal voltage value VBN, the Zener diode D12 is in a non-conductive state. On the other hand, for example, when the engine is started to operate the starter motor 34, when the battery output voltage VB decreases and the voltage across the Zener diode D12 exceeds the breakdown voltage VZ1, the capacitor C11 is charged via the Zener diode D12. The charged electric charge is supplied to the battery output terminal, and the battery output voltage VB can be prevented from being lowered and stabilized. As a result, it is possible to use capacitors C21 and C22 having relatively small capacities, and the cost can be reduced.

When a power switch is provided between the output terminal of the battery 6 and the booster circuit 10 and the power switch is turned off before the engine 1 is started and turned on at the start of the start, the booster circuit 10 is turned on when the power switch is turned on. Since the charging current of the capacitor C11 is quickly supplied by bypassing the coil L11, the rising of the first power supply voltage VS1 can be accelerated and a quick start can be performed.
In the present embodiment, the CPU 11 constitutes a fuel injection control unit.

[Second Embodiment]
FIG. 3 is a circuit diagram for explaining a configuration of a fuel injection valve drive unit according to the second embodiment of the present invention. Except for the points described below, the second embodiment is the same as the first embodiment.

  In the circuit shown in FIG. 3, a Zener diode D <b> 12 is connected between the output terminal of the booster circuit 10 and the output terminal of the power supply circuit 13. More specifically, the anode of the Zener diode D12 is connected to the output terminal of the power supply circuit 13, and the cathode of the Zener diode D12 is connected to the connection portion between the capacitor C11 and the diode D11.

  As the Zener diode D12 in the present embodiment, the breakdown voltage is a predetermined voltage value VZ2 (for example, about 36V) slightly larger than a value (34V) obtained by subtracting the second power supply voltage (6V) from the first power supply voltage VS1 (40V). Use things. By using the zener diode D12 having such a breakdown voltage VZ2, for example, when the engine is started to operate the starter motor 34, the battery output voltage VB is reduced, and the reverse bias voltage across the zener diode D12 becomes the breakdown voltage VZ2. If exceeded, the Zener diode D12 becomes conductive, the electric charge stored in the capacitor C11 is supplied to the output terminal of the power supply circuit 13, and the second power supply voltage VS2 can be suppressed and stabilized. As a result, it is possible to use capacitors C21 and C22 having relatively small capacities, and the cost can be reduced.

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, an example in which the present invention is applied to a fuel injection device for a four-cylinder engine has been shown. Applicable. The present invention can also be applied to a fuel injection device such as a marine vessel propulsion engine such as an outboard motor having a vertical crankshaft.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Fuel injection valve 5 Electronic control unit (fuel injection control means)
6 Battery 10 Booster circuit (first power supply circuit)
13 Power supply circuit (second power supply circuit)
C11 Capacitor D11 Diode D12 Zener diode

Claims (2)

A fuel injection valve that directly injects fuel into the combustion chamber of the internal combustion engine, a fuel injection control means that controls the operation of the fuel injection valve, a battery, and a first power source connected to the battery and boosting the battery output voltage A first power supply circuit that outputs a voltage; and a second power supply circuit that is connected to the battery and that stabilizes the battery output voltage and outputs a second power supply voltage lower than the battery output voltage. A fuel injection device for an internal combustion engine configured to supply drive power for the fuel injection valve from the second power supply circuit and supply a power supply voltage for the fuel injection control means from the second power supply circuit;
The first power supply circuit includes a series circuit of a coil and a diode, a capacitor, and a switching element connected to a connection portion of the coil and the diode, and one end of the series circuit is connected to the battery, and the series circuit The other end of the capacitor is connected to one end of the capacitor, the other end of the capacitor is grounded, and configured to output the first power supply voltage from one end of the capacitor,
A zener diode is disposed in parallel with the series circuit, an anode of the zener diode is connected to one end of the series circuit, and a cathode of the zener diode is connected to the other end of the series circuit. Engine fuel injection device. A fuel injection valve that directly injects fuel into the combustion chamber of the internal combustion engine, a fuel injection control means that controls the operation of the fuel injection valve, a battery, and a first power source connected to the battery and boosting the battery output voltage A first power supply circuit that outputs a voltage; and a second power supply circuit that is connected to the battery and that stabilizes the battery output voltage and outputs a second power supply voltage lower than the battery output voltage. A fuel injection device for an internal combustion engine configured to supply drive power for the fuel injection valve from the second power supply circuit and supply a power supply voltage for the fuel injection control means from the second power supply circuit;
The first power supply circuit includes a series circuit of a coil and a diode, a capacitor, and a switching element connected to a connection portion of the coil and the diode, and one end of the series circuit is connected to the battery, and the series circuit The other end of the capacitor is connected to one end of the capacitor, the other end of the capacitor is grounded, and configured to output the first power supply voltage from one end of the capacitor,
A Zener diode is disposed between one end of the capacitor and the output end of the second power supply circuit, the anode of the Zener diode is connected to the output end of the second power supply circuit, and the cathode of the Zener diode is the capacitor. A fuel injection control device for an internal combustion engine, being connected to one end of the internal combustion engine.

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