JP2006138258A - Fuel injection device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration of startability of an engine caused by short of fuel injection quantity due to drop of power source voltage applied on an injector at engine start-up in a fuel injection device for internal combustion engine. <P>SOLUTION: This fuel injection device is provided with a start determination means determining whether start of the engine is completed or not, and a voltage command generation means generating first voltage command signal Sc1 when the determination means determines that start of the engine is completed and generating second voltage command signal Sc2 when the determination means determines that start of the engine is not completed, and is further provided with a capacitor charging control circuit 202 controlling voltage at both ends of a power source capacitor C1 to limit voltage at the both ends of the power source capacitor C1 to a set first control voltage or lower when the first voltage command signal is generated and to permit voltage at the both ends of the power source capacitor C1 to rise to a second control voltage higher than the first control voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection device for an internal combustion engine that operates by being supplied with a power supply voltage from a power supply device that outputs a DC voltage using an AC generator driven by the internal combustion engine as a power source.

  A fuel injection device for an internal combustion engine includes a power supply device that outputs a DC voltage, an injector that is attached to an intake pipe or a cylinder head of the engine and injects fuel when a drive current is applied, and a predetermined injection timing A control unit that generates an injection command signal, and an injector drive circuit that applies an output voltage of the power supply device to the injector while the injection command signal is being generated and causes a drive current to flow through the injector. In addition, an electric fuel pump is provided as means for supplying fuel to the injector, and a pressure regulator is provided for controlling the fuel pressure supplied from the fuel pump to the injector to be constant.

  In a fuel injection device used in an internal combustion engine that drives a vehicle or the like equipped with a battery, a battery is used as the power supply device. In a fuel injection device used in an internal combustion engine that drives a vehicle or the like not equipped with a battery, for example, a patent is used. As shown in Document 1, as the power supply device, one that converts an output of an AC generator driven by an internal combustion engine into a DC output is used.

  As the injector, an electromagnetic fuel injection valve is usually used. This type of injector includes an injector body that is supplied with fuel from a fuel pump, a valve that opens and closes a fuel injection port provided at the tip of the injector body, and a solenoid that drives the valve. When the drive current applied to the valve reaches a predetermined level, the valve is opened to start fuel injection, and the valve is kept open while the predetermined drive current is flowing through the solenoid coil. The injection operation is performed. Of the time during which the power supply voltage is applied to the solenoid coil of the injector, the time from when application of the power supply voltage is started until the valve is opened is the invalid injection time, and the time during which the valve is open is the effective injection time. The signal width of the injection command signal is set equal to a time corresponding to the sum of the invalid injection time and the effective injection time. The invalid injection time depends on the magnitude of the power supply voltage applied to the solenoid coil.

  When controlling a fuel injection device equipped with this type of injector, the fuel injection time is calculated for various control conditions such as engine speed, throttle valve opening, intake air temperature, and engine coolant temperature. Then, an injection command signal having a signal width obtained by adding the invalid injection time to the calculated injection time is given to the injector driving circuit to drive the injector. Therefore, in order to accurately inject fuel, it is necessary to keep the invalid injection time constant and to keep the power supply voltage applied to the injector constant. Therefore, when using a power supply device that converts the output of the AC generator driven by the engine into a DC output, the power supply device outputs a constant DC voltage regardless of the rotational speed of the engine. Composed.

In the fuel injection device described in Patent Document 1, a rectifier that rectifies the output of an AC generator driven by an internal combustion engine, and a constant voltage that controls the output voltage of the rectifier to be limited to a predetermined control voltage or less. A power supply device for driving the injector is constituted by the circuit.
Utility Model Registration No. 2573118

  As described above, when a generator driven by an internal combustion engine is used as a power source, and the power supply device is provided with a constant voltage circuit having a function of limiting the output voltage to a certain control voltage or less, the power supply voltage is applied to the injector. If sufficient cranking speed cannot be obtained due to insufficient operating force when starting the engine, the power supply voltage applied to the injector will be insufficient due to insufficient generator output, and the probability of engine startup failure will increase. was there. In other words, if the operating force for cranking is insufficient when starting the engine, the rotation speed of the crankshaft of the engine will drop significantly when the piston of the engine approaches the top dead center of the compression stroke. The peak value of the output voltage of the generator may become lower than the control voltage of the constant voltage circuit, and the power supply voltage applied from the power supply device to the injector may become lower than the specified value. If the power supply voltage applied to the injector from the power supply device decreases in this way, the invalid injection time of the injector becomes longer than expected, or the injector valve cannot be fully opened. The engine fails to start due to insufficient quantity.

  In order to solve such a problem, conventionally, the number of turns of the armature coil of the generator is increased so that the generator outputs a high voltage even when the rotational speed of the engine is low. However, increasing the number of turns of the armature coil of the generator not only increases the size of the generator and increases the cost, but also increases the size of the engine and increases its weight. There was a problem that it was impossible to meet the demand for saving.

  Accordingly, it is an object of the present invention to provide a fuel injection device for an internal combustion engine that eliminates the possibility of engine start failure due to insufficient power supply voltage applied to an injector at engine start.

  A fuel injection device for an internal combustion engine to which the present invention is applied includes a rectifier that rectifies the output of an AC generator driven by the internal combustion engine, and a power supply that is charged to one polarity by the output of the rectifier The apparatus includes an injector that operates using the voltage across the power supply capacitor as the power supply voltage.

  In the present invention, when the start of the internal combustion engine is completed, the voltage across the power supply capacitor is limited to a preset control voltage or less, and when the internal combustion engine is not started, the voltage across the power supply capacitor is limited. Is provided with power supply voltage control means for controlling the voltage across the power supply capacitor so as to allow the voltage to exceed the control voltage.

  As described above, by allowing the voltage across the power supply capacitor to exceed the control voltage when the start of the internal combustion engine is not completed, the rotational speed of the engine immediately after the start operation is started The power supply capacitor can be charged to a voltage close to the peak value of the high voltage generated by the generator when in a high state. Therefore, even when the engine piston approaches top dead center and the rotational speed of the generator decreases, a high voltage at both ends of the power supply capacitor can be applied to the injector as a power supply voltage. It is possible to prevent a situation where the voltage is insufficient and the fuel injection amount is insufficient. Therefore, the startability of the engine can be improved without using a particularly large generator.

  In a preferred aspect of the present invention, a fuel injection device for an internal combustion engine includes a rectifier that rectifies the output of an AC generator driven by the internal combustion engine, and a power supply capacitor that is charged to one polarity by the output of the rectifier. An injector that injects fuel when a drive current is applied, a control unit that generates an injection command signal at a predetermined injection timing, and an injector that supplies a voltage across a power supply capacitor while the injection command signal is generated And an injector driving circuit for supplying a driving current to the injector.

  In this case, start determination means for determining whether or not the internal combustion engine has been started, and the first voltage command signal when it is determined by the start determination means that the engine has been started. And the voltage command generating means for generating the second voltage command signal when it is determined by the start determining means that the engine has not been started, and the first voltage command signal is generated The voltage at both ends of the power supply capacitor is limited to the set first control voltage or less, and when the second voltage command signal is generated, the voltage at both ends of the power supply capacitor is higher than the first control voltage. And a capacitor charge control circuit for controlling the voltage across the power supply capacitor so as to allow the voltage to rise up to the control voltage.

  A magnet type AC generator is often used as the AC generator. When such a generator is used, the capacitor charging control circuit has a shorting switch provided so as to short-circuit between the output terminals of the AC generator through the rectifier when turned on, and both ends of the power supply capacitor. A resistance voltage dividing circuit to which a voltage is applied, a shorting switch triggering means for triggering the shorting switch when the output voltage of the resistance voltage dividing circuit reaches a set value, and a first voltage command signal The resistor that maintains the OFF state when the voltage is generated, sets the voltage dividing ratio of the resistance voltage dividing circuit to a large value, and is turned on while the second voltage command signal is generated to constitute the resistance voltage dividing circuit. It is preferable to have a configuration including a voltage dividing ratio changeover switch provided so as to switch the voltage dividing ratio of the resistance voltage dividing circuit to a small value by short-circuiting a part thereof.

  When the alternator is a magnet-type alternator, the capacitor charging control circuit includes a shorting switch provided to short-circuit between the output terminals of the alternator through the rectifier when turned on. A resistance voltage dividing circuit to which a voltage across the power supply capacitor is applied, and a shorting switch trigger that triggers the shorting switch to turn on when the output voltage of the resistance voltage dividing circuit reaches a set value And the voltage dividing ratio of the resistance voltage dividing circuit is increased by short-circuiting a part of the resistors constituting the resistance voltage dividing circuit which is turned on while the first voltage command signal is generated, A voltage dividing ratio changeover switch provided to keep the OFF state and reduce the voltage dividing ratio of the resistance voltage dividing circuit when the second voltage command signal is generated may be provided. That.

  In another preferred aspect of the present invention, the start determination means for determining whether or not the start of the internal combustion engine is completed, and the first voltage when the start determination means determines that the start is completed. A voltage command generating means for generating a second voltage command signal when the start determination means determines that the start is not completed by the start determination means, and a first voltage command signal is generated When the second voltage command signal is generated, the voltage at both ends of the power supply capacitor is limited to the peak value of the output voltage of the AC generator. A capacitor charge control circuit is provided that controls the voltage across the power supply capacitor to allow it to rise.

  When the AC generator is a magnet type AC AC generator, the capacitor charging control circuit includes a short-circuit switch provided to short-circuit between the output terminals of the AC generator through a rectifier when turned on. A resistance voltage dividing circuit to which a voltage across the power supply capacitor is applied, a short circuit switch triggering means for triggering the short circuit switch to turn on when the output voltage of the resistance voltage dividing circuit reaches a set value; The short-circuit switch is allowed to be triggered when the voltage command signal of 1 is generated, and the short-circuit switch is prohibited from being triggered when the second voltage control is generated. And a trigger control switch.

  In a preferred aspect of the present invention, the power supply voltage of the fuel pump that supplies fuel to the injector is supplied from the power supply device. With this configuration, the fuel pump can be driven with a sufficient power supply voltage at the time of starting operation, and the pressure of the fuel applied to the injector can be quickly raised to a specified value, so that the startability of the engine can be improved. it can.

  As described above, according to the present invention, since the voltage across the power supply capacitor is allowed to exceed the control voltage when the start of the internal combustion engine is not completed, immediately after the start operation is started. The power supply capacitor can be charged to a value close to the peak value of the high voltage generated by the generator when the engine rotation speed is high, and the engine rotation speed approaches the top dead center. When lowered, a high voltage across the power supply capacitor can be applied to the injector as a power supply voltage. Therefore, even when a large generator is not used, it is possible to prevent the situation where the injector power supply voltage is insufficient and the fuel injection amount is insufficient when starting the engine, thereby improving the startability of the engine. Can do.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows the hardware configuration of a preferred embodiment of the present invention. In the figure, reference numeral 1 denotes an armature coil which is provided in a magnet type AC generator driven by an internal combustion engine (not shown) and outputs an AC voltage in synchronization with the rotation of the engine. Reference numeral 2 denotes a power supply device that converts an AC output voltage output from the armature coil 1 into a DC voltage. This power supply device rectifies the output of the armature coil 1 and charges to one polarity with the output of the rectifier 201. And a capacitor charge control circuit 202 that controls the voltage across the power capacitor C1.

  Reference numeral 3 denotes an injector to which a power supply voltage is applied from the power supply device 2, and reference numeral 4 denotes an electronic control unit (ECU) that performs various control operations necessary for operating the internal combustion engine. In this embodiment, the control unit generates a control signal for controlling an ignition device for igniting the internal combustion engine, an injection command signal Sj for determining the fuel injection start timing and the injection time, and the power supply device First and second voltage command signals Sc1 and Sc2 for controlling the output voltage are output. The ignition system and the control system that controls the ignition system are not shown.

  Reference numeral 5 denotes a control power supply device that applies a power supply voltage to the ECU 4. Reference numeral 6 denotes an output voltage of the power supply device 2 that is applied to the injector 3 when the ECU 4 generates the injection command signal Sj, so that a drive current flows through the solenoid coil 3a of the injector 3. It is an injector drive circuit. Reference numeral 7 denotes an electric fuel pump that supplies fuel to the injector 3, and this fuel pump operates when a power supply voltage is applied from the power supply device 2.

  Further, each part will be described in detail. The rectifier 201 is a single-phase diode bridge full-wave rectifier configured by bridge-connecting the diodes Da to Dd, and the negative side DC output terminal is grounded. The power supply capacitor C1 is composed of an electrolytic capacitor, and one end thereof is grounded. The other end of the power supply capacitor C1 is connected to the cathode of the diode D1 whose anode is connected to the positive side output terminal of the rectifier 201, and is also connected to the anode of the diode D2, and the cathode of the diode D2 is the solenoid coil 3a of the injector 3. It is connected to one end. The power supply capacitor C1 is charged to the illustrated polarity through the diode D1 by the output voltage of the rectifier 201. The voltage across the power supply capacitor C1 (the output voltage of the power supply device 2) is applied to the injector solenoid coil 3a through the diode D2 and the injector drive circuit 6.

  Capacitor charge control circuit 202 limits the voltage across power supply capacitor C1 to the set first control voltage or lower when ECU 4 is generating first voltage command signal Sc1 from port A1, and ECU sets the first When the voltage command signal Sc2 of 2 is generated, the voltage across the power supply capacitor C1 is allowed to allow the voltage across the power supply capacitor C1 to rise to a second control voltage higher than the first control voltage. Is a circuit for controlling

  In the illustrated example, when this capacitor charging control circuit 202 is turned on, the short-circuit switch 202A that short-circuits between the output terminals of the AC generator through the diode that constitutes the rectifier 201, and the voltage across the power supply capacitor C1. , A short-circuit switch trigger means 202C that triggers the short-circuit switch to turn on when the output voltage of the resistance voltage-divider circuit reaches a set value, and a second voltage command A voltage division ratio changeover switch provided to reduce the voltage division ratio of the resistance voltage dividing circuit 202B by turning on only during the generation of the signal Sc2 and short-circuiting part of the resistors constituting the resistance voltage dividing circuit. 202D.

  In the illustrated example, the short-circuit switch 202A includes a thyristor Th1, and the anode and cathode of the thyristor are connected to the plus side DC output terminal and the minus side DC output terminal of the rectifier 201.

  The resistance voltage dividing circuit 202B includes first to third resistors R1 to R3 connected in series. In the illustrated example, one end of the first resistor R1 is connected to the other end (positive side terminal) of the power supply capacitor C1, and one end of the second resistor R2 is connected to the other end of the first resistor R1. ing. One end of a third resistor R3 is connected to the other end of the second resistor R2, and the other end of the third resistor R3 is connected to a ground potential portion (one end of a power supply capacitor). In this example, the connection point between the first resistor R1 and the second resistor R2 is a voltage dividing point, and the voltage across the power supply capacitor C1 is set between the voltage dividing point and the ground potential portion. A proportional detection voltage appears.

  The anode and cathode of the Zener diode ZD1 are connected to the voltage dividing point of the resistance voltage dividing circuit 202B and the gate of the thyristor Th1, respectively, and the Zener diode constitutes a short circuit switch trigger means 202C.

  The collector of the NPN transistor TR1 whose emitter is grounded is connected to the connection point between the resistors R2 and R3 of the resistance voltage dividing circuit 202B, and the base of the transistor TR1 is connected to the port A1 of the ECU 4. A voltage dividing ratio changeover switch 202D is configured by the transistor TR1.

  The injector 3 is a well-known one that includes an injector body having an injection port at the tip, a needle valve that opens and closes the injection port, and a solenoid that drives the valve. The injector 3 is attached to an intake pipe of an engine and has a fuel in the intake pipe. Or attached to the cylinder head of the engine to inject fuel into the combustion chamber. Fuel is supplied to the injector 3 from a fuel pump 7. The pressure of the fuel applied to the injector is kept constant by a pressure regulator.

  The injector drive circuit 6 is composed of a switch circuit using a semiconductor switch element such as a transistor. While the injection command signal Vj is applied from the port A2 of the ECU 4, the injector drive circuit 6 is turned on so that the power supply device 2 An output voltage (voltage across the power supply capacitor C1) Vc is applied to the solenoid coil 3a of the injector 3.

  The control power supply circuit 5 includes a rectifier 501 that rectifies the output of another armature coil 8 provided with the armature coil 1 in the magnet generator, a smoothing capacitor C2 connected between the output terminals of the rectifier 501, The constant voltage circuit 502 controls the voltage across the capacitor C2 so as to keep it constant. The constant voltage circuit 502 can be configured by a commercially available regulator IC. The control power supply circuit 5 outputs a control power supply voltage Vcc having a voltage value (for example, 5 V) suitable for driving the ECU 4 from the constant voltage circuit 502. This control power supply voltage Vcc is applied to the power supply terminal of the ECU 4.

  Although not shown, the ECU 4 includes the output of the pulse signal generator 9 that generates a pulse signal at a predetermined crank cow position of the engine, the throttle valve opening of the engine, the coolant temperature, the intake air temperature, the intake pressure, and the like. Outputs of various sensors 10 that detect control conditions are input. The ECU 4 includes a microprocessor, and configures various control means necessary for operating the internal combustion engine by causing the microprocessor to execute a predetermined program.

  Among the control means constituted by the microprocessor, there are a rotational speed detecting means for detecting the rotational speed of the engine from the generation interval of the pulse signal generated by the pulse signal generator, and whether or not the internal combustion engine has been started. A first voltage command signal is generated when the start determination means determines that the start is completed, and the start determination means determines that the start is not completed. A voltage command generating means for generating a second voltage command signal when the engine is in operation, and fuel injection time for various control conditions such as engine speed, throttle valve opening, cooling water temperature, intake air temperature, intake pressure, etc. And an injection time calculation means for calculating a rectangular wave-like injection command signal Sj having a signal width obtained by adding an invalid injection time to the injection time when a crank angle position at which fuel injection is started is detected Injection command generating means for controlling the engine, and control means necessary for controlling the ignition timing of the engine.

  Of the above control means, the control means other than the start determination means and the voltage command generation means may be already known, and thus detailed description thereof will be omitted.

  FIG. 5 shows a flowchart showing an algorithm of a task to be executed by the microprocessor in order to constitute the start determination means and the voltage command generation means. The task shown in FIG. 5 is executed every minute after the microprocessor power supply is established and the microprocessor is started.

  When the task shown in FIG. 5 is started, it is first determined in step 1 whether or not the current rotational speed is less than a set speed set for determining completion of engine start. As a result, when it is determined that the rotational speed is equal to or higher than the set speed, the process proceeds to step 2 to determine whether or not the set time has elapsed since the start operation of the engine was started. The set time is set to the maximum value of the time that is expected to elapse from the start operation to the end time. When it is determined in step 2 that the elapsed time since the start operation is started is equal to or longer than the set time, the process proceeds to step 3 to instruct to set the control voltage of the power supply device to the first control voltage V1. After generating the voltage command signal Sc1 of 1, this task is finished. When it is determined in step 1 that the rotational speed is less than the set speed, or when it is determined in step 2 that the elapsed time from the start of the start operation is less than the set time, the process proceeds to step 4 to control voltage of the power supply device To generate the second voltage command signal Sc2 for commanding to set the second control voltage V2 (> V1).

  In this embodiment, the state in which the potential of the port A1 of the ECU 4 is at the zero level (ground potential) is the state in which the first voltage command signal Sc1 is generated, and the state in which the potential of the port A1 is at the high level. The voltage command signal Sc2 of 2 is generated.

  In the case of the algorithm shown in FIG. 5, steps 1 and 2 constitute start determination means for determining whether or not the internal combustion engine has been started, and steps 3 and 4 start the start by the start determination means. A voltage command generation that generates a first voltage command signal when it is determined that the start is completed and generates a second voltage command signal when it is determined that the start is not completed by the start determination means Means are configured.

  In the power supply device 2 shown in FIG. 1, the voltage Vc across the power supply capacitor C1 is detected by the resistance voltage dividing circuit 202B. When the voltage across the power supply capacitor C1 exceeds a certain value due to a rise in the output voltage of the armature coil 1 and the detection voltage output from the resistance voltage dividing circuit 202B exceeds the Zener voltage of the Zener diode ZD1, a trigger signal is sent to the thyristor Th1. As a result, the thyristor becomes conductive, so that the armature coil 1 is short-circuited through the diode constituting the rectifier 201 and the thyristor Th1, and charging of the power supply capacitor C1 is stopped. When the voltage across the power supply capacitor C1 decreases and the detection voltage output from the resistance voltage dividing circuit 202B falls below the zener voltage, the supply of the trigger signal to the thyristor Th1 is stopped, and the thyristor Th1 has its anode current below the holding current. When it becomes, it turns off. As a result, the charging of the power supply capacitor C1 is resumed.

  Therefore, in the power supply device shown in FIG. 1, when the detection voltage output from the resistance voltage dividing circuit 202B exceeds the Zener voltage of the Zener diode ZD1, the voltage across the power supply capacitor C1 becomes the control voltage, and the above operation is repeated. The voltage Vc across the power supply capacitor C1 is kept below the control voltage. If the armature coil 1 outputs a voltage exceeding the control voltage during steady operation of the internal combustion engine, the voltage Vc obtained at both ends of the power supply capacitor C1 during steady operation of the engine becomes a constant value equal to the value of the control voltage. Kept.

In the embodiment shown in FIG. 1, when the ECU 4 generates the first voltage command signal (zero level signal) Sc1 from the port A1, the transistor TR1 constituting the voltage division ratio changeover switch is in the OFF state. The respective resistance values of the resistors R1 to R3 are represented by the same symbols R1 to R3, and the voltage across the power supply capacitor C1 is Vc. The detection voltage output from the resistance voltage dividing circuit 202B when the transistor TR1 is in the OFF state Vs1 is given by the following equation.
Vs1 = Vc (R2 + R3) / (R1 + R2 + R3) (1)

On the other hand, when the ECU 4 generates the second voltage command signal (high level signal) Sc2 from the port A1, the transistor TR1 is turned on to short-circuit both ends of the resistor R3. The detection voltage Vs2 output by 202B is given by the following equation (2).
Vs2 = Vc · R2 / (R1 + R2) (2)

Here, the voltage division ratio (R2 + R3) / (R1 + R2 + R3) when the first voltage command signal Sc1 is generated is compared with the voltage division ratio R2 / (R1 + R2 + R3) when the second voltage command signal Sc2 is generated. Then
(R2 + R3) / (R1 + R2 + R3)> R2 / (R1 + R2) (3)
It becomes. That is, the voltage dividing ratio of the resistance voltage dividing circuit 202B takes a large value when the first voltage command signal Sc1 is generated and takes a small value when the second voltage command signal Sc2 is generated. In response to the voltage command signal. Here, when the voltage Vc at both ends of the power supply capacitor C1 is constant and the detection voltages Vs1 and Vs2 are compared, Vs1> Vs2.

  Thus, for the same voltage Vc, the detection voltage Vs1 output from the resistance voltage dividing circuit 202B when the first voltage command signal Sc1 is generated and the second voltage command signal Sc2 are generated. When the detection voltage Vs2 output by the resistance voltage dividing circuit is compared, the detection voltage Vs1 output by the resistance voltage dividing circuit 202B when the first voltage command signal Sc1 is generated is more likely to be the second voltage command. Since the detection voltage Vs2 output from the resistance voltage dividing circuit when the signal Sc2 is generated is higher than the detection voltage Vs2 output from the resistance voltage dividing circuit, both ends of the power supply capacitor C1 when the detection voltage output from the resistance voltage dividing circuit exceeds the Zener voltage of the Zener diode ZD1. This voltage (control voltage) is higher when the second voltage command signal Sc2 is generated than when the first voltage command signal Sc1 is generated. Here, the control voltage when the first voltage command signal Sc1 is generated is the first control voltage V1, and the control voltage when the second voltage command signal Sc2 is generated is the second control voltage V2. Then, V1 <V2.

  Accordingly, the capacitor charging control circuit 202 provided in the power supply device 2 of FIG. 1 has the first control voltage V1 in which the voltage across the power supply capacitor C1 is set when the first voltage command signal Sc1 is generated. Limiting to the following, when the second voltage command signal Sc2 is generated, the voltage across the power supply capacitor C1 is allowed to rise to the second control voltage V2 higher than the first control voltage V1.

  FIG. 6 shows the voltage waveform output from the armature coil 1, the voltage obtained across the power supply capacitor C1, and the voltage dividing ratio of the resistance voltage dividing circuit 202B in the example shown in FIG. It is the figure which compared and showed the waveform of the voltage obtained at the both ends of a power supply capacitor when not having performed.

  In FIG. 6, Vo is the minimum value of the power supply voltage that must be applied across the solenoid coil of the injector in order to operate the injector. When the voltage applied to the solenoid coil of the injector is less than this voltage Vo, The fuel cannot be injected. V1 and V2 are a first control voltage and a second control voltage, respectively, and V3 is a withstand voltage of a diode constituting the rectifier 201. A waveform a shown in FIG. 6 is an output voltage waveform of the generator (armature coil 1), and b is a waveform of a voltage obtained at both ends of the power supply capacitor C1 when charging of the power supply capacitor C1 is not controlled. It is. Further, c is a waveform of a voltage obtained at both ends of the power supply capacitor C1 when the first voltage command signal Sc1 is generated, and d is a power supply capacitor C1 when the second voltage command signal Sc2 is generated. It is the waveform of the voltage obtained at both ends.

  The first control voltage V1 is a voltage that regulates the output voltage of the power supply device during steady operation of the internal combustion engine, and the second control voltage V2 is the output of the power supply device when the engine is being started. It is a voltage that defines the maximum value of the voltage. As shown in FIG. 6, the second control voltage V2 is set sufficiently higher than the control voltage V1 during steady operation and lower than the withstand voltage of the rectifier diode. The waveforms c, d, and b shown in FIG. 6 are individually shown in FIGS. 7A, 7B, and 7C for easy understanding.

  With the above configuration, when the internal combustion engine has not been started, as shown in FIG. 7B, the voltage Vc across the power supply capacitor is the first control voltage V1 that is the control voltage during steady operation. Is allowed to rise up to the second control voltage V2, so that when the engine is started, a generator is generated immediately after the start operation is started and the engine is still at a high rotational speed. The power supply capacitor C1 can be charged to a voltage V2 close to the peak value of the high voltage. Accordingly, even when the piston of the engine approaches top dead center and the rotational speed of the generator decreases, the high voltage Vc at both ends of the power supply capacitor C1 can be applied to the solenoid coil of the injector 3 as a power supply voltage. Even if a large generator is not used, it is possible to prevent a situation in which the power supply voltage of the injector is insufficient and the fuel injection amount is insufficient when the engine is started.

  When configured as described above, the power supply voltage applied to the injector at the time of starting the engine becomes higher, so that the invalid injection time of the injector becomes shorter than the invalid injection time during normal operation, and the effective injection time becomes longer. Although the amount tends to increase, fuel increase control that increases the fuel injection amount is originally performed at the time of starting the engine, so there is no problem.

  After the start of the engine is completed, the voltage Vc across the power supply capacitor C1 is maintained at the first control voltage V1, which is the control voltage during steady operation, regardless of the rotational speed of the engine. A constant power supply voltage is always applied, and the fuel injection operation during steady operation can be stably performed.

  In the above embodiment, the armature coil 1 and the other armature coil 8 provided in the magnet generator are used as the power source of the control power supply device 5, but the other armature coil 8 is not used. As shown in FIG. 2, the control power supply 5 can also be configured by a constant voltage circuit 502 that converts the voltage across the power supply capacitor C1 into a constant voltage Vcc suitable for driving the ECU 4. The other configuration of the embodiment shown in FIG. 2 is the same as that of the embodiment shown in FIG.

  In the embodiment shown in FIG. 1, while the first voltage command signal Sc1 is a zero level signal and the second voltage command signal Sc2 is a high level signal, the second voltage command signal Sc2 is generated. Only the voltage dividing ratio of the resistance voltage dividing circuit 202B is reduced by turning on the voltage dividing ratio changeover switch 202D so as to short-circuit a part of the resistors constituting the resistance voltage dividing circuit 202B, but the first voltage command The signal Sc1 is set to a high level signal, the second voltage command signal Sc2 is set to a zero level signal, and when the first voltage command signal Sc1 is generated, the voltage dividing ratio changeover switch 202D is turned on and the resistor voltage is divided. By short-circuiting a part of the resistance of the circuit, the voltage dividing ratio of the resistance voltage dividing circuit is increased, and when the second voltage command signal Sc2 is generated, the voltage dividing ratio changeover switch 202D is turned off and the resistance voltage dividing circuit is turned off. Circuit voltage division ratio It may constitute a capacitor charging control circuit 202 to a small value.

  FIG. 3 shows an example in which the capacitor charging control circuit 202 is configured as described above. In the example shown in FIG. 3, the collector of the transistor TR1 constituting the voltage dividing ratio changeover switch 202D is connected to the connection point between the resistors R1 and R2, and the emitter of the transistor TR1 is connected to the connection point between the resistors R2 and R3. ing. Although not shown in FIG. 3, the base of the transistor TR1 is connected to the port A1 of the ECU 4. The ECU 4 generates a high level first voltage command signal Sc1 from the port A1 when the engine start is completed, and a zero level second voltage from the port A1 when the engine start is not completed. Command signal Sc2 is generated.

  In the example shown in FIG. 3, the output voltage of the resistor voltage dividing circuit 202B is taken out from both ends of the resistor R3, and the voltage at both ends of the resistor R3 is applied to the gate of the thyristor Th1 through the Zener diode ZD1. Yes.

In the capacitor charge control circuit 202 shown in FIG. 3, when the ECU is generating the first voltage command signal Sc1 at a high level, the transistor TR1 is turned on to short-circuit both ends of the resistor R2, so that the resistance component The detection voltage Vs1 output from the voltage circuit 202B is given by the following equation.
Vs1 = Vc · R3 / (R1 + R3) (4)

On the other hand, when the ECU is generating the second voltage command signal Sc2 at the zero level, the transistor TR1 is in the off state, so that the detection voltage Vs2 output from the resistance voltage dividing circuit 202B is given by the following equation. It is done.
Vs2 = Vc.R3 / (R1 + R2 + R3) (5)

Here, when the voltage division ratio R3 / (R1 + R3) when the first voltage command signal Sc1 is generated is compared with the voltage division ratio R3 / (R1 + R2 + R3) when the second voltage command signal Sc2 is generated,
R3 / (R1 + R3)> R3 / (R1 + R2 + R3) (6)
It becomes. That is, the voltage dividing ratio of the resistance voltage dividing circuit 202B takes a large value when the first voltage command signal Sc1 is generated and takes a small value when the second voltage command signal Sc2 is generated. In response to the voltage command signal. Here, when the voltage Vc at both ends of the power supply capacitor C1 is constant and the detection voltages Vs1 and Vs2 are compared, Vs1> Vs2.

  Also in this case, for the same voltage Vc, the detection voltage Vs1 output from the resistance voltage dividing circuit 202B when the first voltage command signal Sc1 is generated causes the second voltage command signal Sc2 to be generated. The voltage across the power supply capacitor C1 when the detection voltage output from the resistance voltage divider circuit exceeds the Zener voltage of the Zener diode ZD1 (control voltage) is higher than the detection voltage Vs2 output from the resistance voltage divider circuit. Is higher when the second voltage command signal Sc2 is generated than when the first voltage command signal Sc1 is generated. Here, the control voltage when the first voltage command signal Sc1 is generated is the first control voltage V1, and the control voltage when the second voltage command signal Sc2 is generated is the second control voltage V2. Then, V1 <V2.

  The capacitor charge control circuit 202 shown in FIG. 3 includes a short-circuit switch 202A provided to short-circuit between the output terminals of the AC generator through the rectifier 201 when turned on, and the voltage across the power supply capacitor C1. Is applied to the resistance voltage dividing circuit 202B, the short-circuit switch triggering means 202C for triggering the short-circuiting switch when the output voltage of the resistance voltage dividing circuit 202B reaches a set value, and the first voltage. The voltage dividing ratio provided to increase the voltage dividing ratio of the resistance voltage dividing circuit 202B by turning on only during the generation of the command signal Sc1 and short-circuiting a part of the resistors constituting the resistance voltage dividing circuit 202B. And a changeover switch 202D.

  If the peak value of the output voltage of the generator does not exceed the withstand voltage of the injector when the engine is started, the voltage across the power supply capacitor C1 is set when the first voltage command signal Sc1 is generated. It is limited to the first control voltage V1 or less, and when the second voltage command signal Sc2 is generated, the voltage across the power supply capacitor C1 is allowed to rise to the peak value of the output voltage of the AC generator. Alternatively, the capacitor charging control circuit 202 may be configured.

  FIG. 4 shows an example of the capacitor charging control circuit 202 configured as described above. In this example, the resistance voltage dividing circuit 202B is composed of a series circuit of resistors R1 and R2, and one end of the resistor R1 is connected to the resistor R1. The power supply capacitor C1 is connected to the non-ground side terminal. The other end of the resistor R1 is connected to the collector of the transistor TR1, and the resistor R2 is connected between the emitter of the transistor TR1 and the ground. The base of the transistor TR1 is connected to a port of an ECU (not shown in FIG. 4). In this example, a trigger control switch 202D ′ is configured by the transistor TR1. The point that the shorting switch 202A is constituted by the thyristor Th1 and the point that the shorting switch trigger means 202C is constituted by the Zener diode ZD1 are the same as in the embodiment shown in FIG.

  That is, the capacitor charging control circuit 202 shown in FIG. 4 includes a shorting switch 202A provided so as to short-circuit between the output terminals of the AC generator through the rectifier 201 and the both ends of the power supply capacitor C1. A voltage dividing circuit 202B to which a voltage of 1 is applied, a shorting switch triggering means 202C for triggering the shorting switch 202A to turn on when the output voltage of the resistance voltage dividing circuit 202B reaches a set value, The short-circuit switch 202A is allowed to be triggered when the first voltage command signal Sc1 is generated, and the short-circuit switch 202A is prohibited from being triggered when the second voltage control Sc2 is generated. And a trigger control switch 202D ′ provided as described above.

  In the example shown in FIG. 4, the ECU outputs a high-level first voltage command signal Sc1 from the port A1 when the engine has been started, and when the engine has not been started, the ECU A second voltage command signal Sc2 of zero level is output from A1. In the capacitor charging control circuit shown in FIG. 4, when the start of the internal combustion engine is not completed, the transistor TR1 is kept off, and the resistance voltage dividing circuit 202B is prohibited from outputting the detection voltage. Th1 is prohibited from being triggered. In this state, the power supply capacitor C1 is allowed to be charged up to the peak value of the output voltage of the armature coil 1. Therefore, even when the piston approaches the top dead center of the compression stroke when the engine is started and the rotational speed of the generator decreases, a high power supply voltage can be applied to the injector 3 and the injector 3 can be operated normally. .

  Since the transistor TR1 is turned on when the engine has been started, the resistance voltage dividing circuit 202B outputs a detection voltage, and the voltage across the power supply capacitor C1 exceeds the control voltage V1, causing the resistance voltage division. When the detection voltage output from the circuit 202B exceeds the Zener voltage of the Zener diode ZD1, a trigger signal is given to the gate of the thyristor Th1. As a result, the thyristor Th1 becomes conductive, the output of the generator is short-circuited through the rectifier 201, the charging of the power supply capacitor C1 is stopped, and the voltage across the power supply capacitor C1 is prevented from exceeding the control voltage V1.

It is the circuit diagram which showed schematically the structure of the hardware of embodiment of this invention. It is the circuit diagram which showed schematically the structure of the hardware of other embodiment of this invention. It is the circuit diagram which showed the modification of the capacitor | condenser charge control circuit used by this invention. It is the circuit diagram which showed the other modification of the capacitor | condenser charge control circuit used by this invention. 4 is a flowchart showing an algorithm of a task to be executed by a microprocessor in order to constitute start determination means and voltage command generation means in the embodiment of the present invention. In the embodiment shown in FIG. 1, the output voltage waveform of the power supply apparatus when the voltage across the power supply capacitor is controlled to be kept below the first control voltage, and the voltage across the power supply capacitor are expressed as the second control voltage. Shown by comparing the output voltage waveform of the power supply when controlled to keep below, the output voltage waveform of the power supply when the voltage across the power supply capacitor is not controlled, and the output voltage waveform of the generator FIG. (A) is a waveform diagram showing the output voltage waveform of the power supply device when the voltage across the power supply capacitor is controlled to be kept below the first control voltage, and (B) is the second voltage across the power supply capacitor. The waveform figure which showed the output voltage waveform of the power supply device at the time of controlling so that it may keep below the control voltage of (C), (C) showed the output voltage waveform of the power supply device when the voltage of the both ends of a power supply capacitor was not controlled It is a waveform diagram.

Explanation of symbols

1 Armature coil of magnet type AC generator 2 Power supply device C1 Power supply capacitor
201 Rectifier 202 Capacitor Charging Control Circuit 202A Short-Circuit Switch 202B Resistance Divider Circuit 202C Short-Circuit Switch Trigger Means 202D Divider Ratio Switch

Claims (7)

A power supply device comprising a rectifier that rectifies the output of an AC generator driven by an internal combustion engine, and a power supply capacitor that is charged to one polarity by the output of the rectifier, and operates using the voltage across the power supply capacitor as a power supply voltage An internal combustion engine fuel injection device comprising:
When the start of the internal combustion engine is completed, the voltage across the power supply capacitor is limited to a preset control voltage or less, and when the start of the internal combustion engine is not completed, the voltage across the power supply capacitor is A fuel injection device for an internal combustion engine comprising power supply voltage control means for controlling the voltage across the power supply capacitor so as to allow the control voltage to be exceeded. A power supply device comprising a rectifier that rectifies the output of an AC generator driven by an internal combustion engine, and a power supply capacitor that is charged to one polarity by the output of the rectifier, and injects fuel when a drive current is applied An injector, a control unit that generates an injection command signal at a predetermined injection timing, and a voltage across the power supply capacitor is applied to the injector while the injection command signal is being generated, so that the drive current flows through the injector A fuel injection device for an internal combustion engine comprising an injector drive circuit,
Start determination means for determining whether start of the internal combustion engine is completed;
A first voltage command signal is generated when it is determined by the start determination means that the start of the engine has been completed, and it is determined by the start determination means that the start of the engine has not been completed. Voltage command generating means for generating a second voltage command signal sometimes;
When the first voltage command signal is generated, the voltage across the power supply capacitor is limited to a preset first control voltage or less, and when the second voltage command signal is generated, the power source A capacitor charge control circuit that controls charging of the power supply capacitor to allow the voltage across the capacitor to rise to a second control voltage that is higher than the first control voltage;
A fuel injection device for an internal combustion engine comprising: The AC generator comprises a magnet type AC generator,
The capacitor charging control circuit includes a shorting switch provided so as to short-circuit between the output terminals of the AC generator through the rectifier when turned on, and a resistor to which a voltage across the power supply capacitor is applied. A voltage dividing circuit; a shorting switch triggering means for triggering the shorting switch when the output voltage of the resistance voltage dividing circuit reaches a set value; and the first voltage command signal is generated. The resistor voltage divider circuit is configured to hold the off-state and increase the voltage-dividing ratio of the resistor-divider circuit so that the resistor-divider circuit is turned on while the second voltage command signal is generated. The fuel injection device for an internal combustion engine according to claim 2, further comprising a voltage dividing ratio changeover switch provided to switch a voltage dividing ratio of the resistance voltage dividing circuit to a small value by short-circuiting a part thereof. The AC generator comprises a magnet type AC generator,
The capacitor charging control circuit includes a shorting switch provided so as to short-circuit between the output terminals of the AC generator through the rectifier when turned on, and a resistor to which a voltage across the power supply capacitor is applied. A voltage dividing circuit; a shorting switch triggering means for triggering the shorting switch when the output voltage of the resistance voltage dividing circuit reaches a set value; and the first voltage command signal is generated. When the second voltage command signal is generated, the voltage dividing ratio of the resistance voltage dividing circuit is increased by short-circuiting a part of the resistors constituting the resistance voltage dividing circuit. The fuel injection device for an internal combustion engine according to claim 2, further comprising a voltage division ratio changeover switch provided so as to maintain an off state and reduce a voltage division ratio of the resistance voltage dividing circuit. A power supply device comprising a rectifier that rectifies the output of an AC generator driven by an internal combustion engine, and a power supply capacitor that is charged to one polarity by the output of the rectifier, and injects fuel when a drive current is applied An injector, a control unit that generates an injection command signal at a predetermined injection timing, and a voltage across the power supply capacitor is applied to the injector while the injection command signal is being generated, so that the drive current flows through the injector A fuel injection device for an internal combustion engine comprising an injector drive circuit,
Start determination means for determining whether start of the internal combustion engine is completed;
A first voltage command signal is generated when the start determination means determines that the start is completed, and a second voltage is generated when the start determination means determines that the start is not complete. Voltage command generating means for generating a command signal;
When the first voltage command signal is generated, the voltage across the power supply capacitor is limited to a preset first control voltage or less, and when the second voltage command signal is generated, the power source A capacitor charge control circuit that controls the voltage across the power supply capacitor to allow the voltage across the capacitor to rise to the peak value of the output voltage of the AC generator;
A fuel injection device for an internal combustion engine comprising: The AC generator comprises a magnet type AC AC generator,
The capacitor charging control circuit includes a shorting switch provided so as to short-circuit between the output terminals of the AC generator through the rectifier when turned on, and a resistor to which a voltage across the power supply capacitor is applied. A voltage dividing circuit; a shorting switch triggering means for triggering the shorting switch when the output voltage of the resistance voltage dividing circuit reaches a set value; and the first voltage command signal is generated. Trigger control switch provided to allow the shorting switch to be triggered when the second voltage control is occurring, and to prohibit the shorting switch from being triggered when the second voltage control is occurring The fuel-injection apparatus for internal combustion engines of Claim 4 provided with these. The fuel injection device for an internal combustion engine according to any one of claims 1 to 6, wherein a power supply voltage of a fuel pump that supplies fuel to the injector is supplied from the power supply device.

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