JP2005163549A - Injector drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constant fuel injection amount by performing a feedback control of drive current applied to an injector. <P>SOLUTION: An injector drive device comprises: an injector 1 injecting fuel by lifting a needle valve opening/closing an injection hole of an injection nozzle by the drive current applied to a drive element therein; a means for generating the drive current for controlling a lift amount of the needle valve of the injector; an injector drive unit 2 applying the drive current to the injector to control a fuel injection amount; and an engine ECU 3 transmitting a fuel injection command signal to the injector drive unit based on an operational status detection signal of an engine. The injector drive unit 2 includes a feedback control means measuring the drive current transmitted to the injector 1 and comparing the drive current to a target current value to apply the drive current which corresponds to the target current value to the injector 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injector drive device that controls the drive of an injector that injects fuel such as gasoline, light oil, LPG, and CNG into an engine cylinder, and more specifically, feedback control of a drive current applied to the injector and constant fuel The present invention relates to an injector driving device capable of obtaining an injection amount.

  A conventional injector driving device includes a injector that lifts a needle valve that opens and closes a nozzle hole of an injection nozzle by a driving current applied to an internal driving element, and injects fuel, and a drive that controls the lift amount of the needle valve of the injector. An injector driving unit that includes a means for generating a current and controls a fuel injection amount by applying a driving current to the injector; and a fuel injection command to the injector driving unit based on an engine operating state detection signal An engine control unit for transmitting a signal.

Such an injector driving device includes a cylindrical valve body having an injection nozzle at one end and a fuel inlet at the other end, an electromagnetic coil installed in the valve body, and an extension in the electromagnetic coil. A magnetostrictive actuator (injector) having a magnetostrictive element rod that can be fitted and has one end serving as an operating end and the other end serving as a free end; And an engine control unit that is extended, and a fuel injection is performed by lifting a needle valve that opens and closes the injection hole of the injection nozzle by the operation of the magnetostrictive element rod (for example, Patent Documents) 1).
JP 2002-327659 A

  However, in the above conventional injector drive device, the injection command signal output from the engine control unit is input to the injector, and the injector lifts the needle valve with the drive current based on the injection command signal and performs fuel injection. Therefore, the injector could only be driven with a certain current waveform. In this case, a change in the inductance of the electromagnetic coil inside the injector, a change in internal resistance, or the like may occur due to a change in ambient temperature or the like, and the drive current applied to the injector may change. Therefore, the lift amount of the needle valve of the injector may change, and the fuel injection amount may change. For this reason, there is a possibility that the output of each cylinder of the engine varies.

  Also, in order to improve the combustion variation due to the variation caused by the manufacturing process of each cylinder of the engine, it is necessary to control the drive current for each cylinder, but this has not been possible in the past. It was. Therefore, there is a possibility that variations in combustion among cylinders cannot be suppressed, and engine vibration and output reduction cannot be suppressed.

  Therefore, the present invention addresses such problems, and an object of the present invention is to provide an injector drive device that can obtain a constant fuel injection amount by feedback control of the drive current applied to the injector.

  In order to achieve the above object, an injector driving device according to the present invention includes an injector for injecting fuel by lifting a needle valve that opens and closes an injection hole of an injection nozzle by a driving current applied to an internal driving element, and an injector of the injector. Means for generating a drive current for controlling the lift amount of the needle valve, an injector drive unit for controlling a fuel injection amount by applying a drive current to the injector, and the injector based on an engine operating state detection signal And an engine control unit that sends a fuel injection command signal to the drive unit.The injector drive unit measures a drive current sent to the injector and compares it with a target current value. A feedback that applies a drive current that follows the target current value to the injector. Those having a control unit.

  With such a configuration, the feedback control means provided in the injector drive unit that controls the fuel injection amount by applying the drive current to the injector measures the drive current sent to the injector and compares it with the target current value. Then, a drive current following the target current value is applied to the injector. As a result, a constant drive current that always follows the target current value is applied to the injector.

  Further, a resistor is inserted in series with a circuit portion for measuring a drive current to be sent to the injector inside the injector drive unit. As a result, the drive current sent to the injector is measured by the voltage generated across the resistor inserted in series in the circuit.

  Further, the target current value can be set by a current adjusting means provided inside the injector drive unit. Thus, a target current value to be compared with the drive current sent to the injector is set by the current adjusting means provided inside the injector drive unit.

  Furthermore, the target current value is obtained by the engine control unit according to the operating state of the engine, and is sent to the injector drive unit via the communication means that connects the engine control unit and the injector drive unit. It can be controlled by a command from As a result, the target current value obtained by the engine control unit according to the operating state of the engine is sent to the injector drive unit via the communication means, and the target current value can be controlled by a command from the engine control unit.

  The injector is provided in each of a plurality of cylinders, and the drive current is controlled for each cylinder by the injector drive unit. Thereby, with respect to the injector provided in each of the plurality of cylinders, the drive current is controlled for each cylinder by the injector driving unit.

  According to the first aspect of the present invention, the feedback control means measures the drive current sent to the injector, compares it with the target current value, and constantly applies the drive current following the target current value to the injector. A constant drive current that follows the target current value can be applied to the injector. Therefore, a constant fuel injection amount can be obtained with a constant lift amount of the needle valve of the injector. From this, it is possible to suppress variations in output for each cylinder of the engine. Further, engine vibration can be reduced.

  Moreover, according to the invention which concerns on Claim 2, the drive current sent to an injector can be measured with the voltage which generate | occur | produces at the both ends of the resistance inserted in series in the circuit. Therefore, it is possible to always monitor the drive current applied to the injector.

  Furthermore, according to the third aspect of the present invention, the target current value to be compared with the drive current sent to the injector can be set by the current adjusting means provided inside the injector drive unit. Therefore, the feedback control means can apply a predetermined drive current to the injector as compared with the drive current sent to the injector.

  Furthermore, according to the invention of claim 4, the target current value obtained by the engine control unit according to the engine operating state is sent to the injector drive unit via the communication means, and the command from the engine control unit is sent. Thus, the target current value can be controlled. Therefore, the engine control unit controls the target current value from the outside of the injector drive unit according to the operating state of the engine, and the feedback control means applies a predetermined drive current to the injector as compared with the drive current sent to the injector. be able to. Thereby, the drive current applied to the injector can be controlled for each cylinder according to the operation state in accordance with a command from the outside of the injector drive unit.

  According to the fifth aspect of the present invention, the drive current can be controlled for each cylinder by the injector drive unit with respect to the injector provided in each of the plurality of cylinders. Therefore, it is possible to suppress variations in output among the cylinders of the engine and to reduce engine vibration.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic view showing an embodiment of an injector driving device according to the present invention. This injector drive device controls the drive of an injector that injects fuel such as gasoline, light oil, LPG, CNG into the cylinder of the engine, and includes an injector 1, an injector drive unit 2, and an engine ECU 3. .

  Although the detailed structure of the injector 1 is omitted, the injector 1 has an injection nozzle 4 at one end and a fuel inlet (not shown) at the other end, and the injection nozzle 4 is driven by a drive current applied to an internal drive element. A needle valve that opens and closes the nozzle hole is lifted to inject fuel, and is provided in each cylinder according to a plurality of cylinders of the engine. The driving element for lifting the needle valve is a conventionally known giant magnetostrictive element or piezoelectric element.

  The injector drive unit 2 includes means for generating a drive current for controlling the lift amount of the needle valve of the injector 1, and controls the fuel injection amount by applying the drive current to the injector 1. A plurality of units are provided in parallel according to the number of injectors 1 and are connected to the respective injectors 1 by signal lines 5.

The engine ECU 3 serves as an engine control unit that sends a fuel injection command signal S ₂ to the injector drive unit 2 on the basis of the engine operation state detection signal S ₁ detected by the operation state detection means 6. It consists of a control microcomputer and is connected to the injector drive unit 2 by a signal line 7. The operation state detection means 6 is an accelerator pedal and the engine tachometer, and outputs the operation state detection signals S ₁ detects the rotational speed and the load of the engine.

FIG. 2 is a block diagram showing the internal configuration of the injector drive unit 2, and shows one injector drive unit 2 that supplies a drive current I ₁ to one injector 1. That is, as shown in FIG. 2, the input signal waveform shaping unit 10, the input signal monitoring unit 11, the overexcitation current power supply unit 12, the overexcitation switch 13, the constant current power supply unit 14, the MOS FET 15, and the diode 16 and 17, and further includes feedback control means 20.

The input signal waveform shaping unit 10 receives the injection command signal S ₂ output from the engine ECU ₃ , removes noise components from the injector drive signal S ₃ and the interlock signal S ₄ as the contents thereof, and provides an open collector input. Is formed into a signal waveform (for example, a rectangular wave) that can be pulled up to recognize a high level (H) and a low level (L) as an electronic circuit. Incidentally, the injector driving signal S ₃ is output through the signal line 7a from the engine ECU 3, the interlock signal S ₄ is output through the signal line 7b.

Input signal monitoring unit 11 is configured to monitor the input state takes in the injector driving signal S ₃ to be input from the engine ECU3 to the input signal waveform shaping unit 10. In this case, the injector driving signal S ₃ is comprised only ON during about 0~10ms per normal once the fuel injection, for some reason of disconnection and short circuit or the like of the signal line when you've followed ON state like , the input signal a predetermined time or more in order to prevent the abnormal fuel injection when turned oN, and interlocking the input signal waveform shaping section 10 is adapted to cut the input of the injector drive signal S ₃ .

The overexcitation current power supply unit 12 serves as a power supply that generates a high voltage in order to generate an overexcitation current for generating the drive current I ₁ supplied to the injector 1. The overexcitation switch 13 outputs a signal for turning on and off the overexcitation current generated by the overexcitation current power supply unit 12. The overexcitation current power supply unit 12 generates an overexcitation current. overexcitation current certain time after the injector drive signal S ₃ is turned oN to be supplied (for example, about 0.2 ms) because it is sufficient, it outputs a signal to turn oN the overexcitation current by the time It is supposed to be. Further, the constant current power supply unit 14 serves as a power supply for generating a predetermined voltage in order to generate a constant current for generating the drive current I ₁ supplied to the injector 1.

The MOS FET 15 uses the ON signal from the overexcitation switch 13 as a gate signal, the overexcitation current from the overexcitation current power supply unit 12 as a drain signal, and sources the overexcitation current only during the period when the gate signal is ON. To supply to the side. The first diode 16 allows the overexcitation current output from the source of the MOS FET 15 to flow toward the adder 18. The second diode 17 allows a constant current from the constant current power supply unit 14 to flow toward the adding unit 18. The adder 18 adds the overexcitation current and the constant current to generate the drive current I ₁ as one current signal. A drive current is generated by the overexcitation current power supply unit 12, the overexcitation switch 13, the constant current power supply unit 14, the MOS FET 15, the first and second diodes 16 and 17, and the addition unit 18. The means to make is comprised.

Here, in the present invention, feedback control means 20 is provided in the injector drive unit 2. This feedback control means 20 measures the drive current I ₁ sent to the injector 1 via the signal line 5 a, compares it with a target current value, and performs feedback control so as to apply a predetermined drive current I ₁ to the injector 1. The resistor R ₁ inserted in series in the circuit portion for measuring the drive current sent to the injector 1 at the output section of the constant current power supply section 14 and the target current value provided in the injector drive unit 2 A first current adjusting means (for example, a volume) 21 for setting a constant current target value I ₂ , a measured value of the drive current measured by the resistor R ₁ , and a constant current target value I ₂ from the current adjusting means 21. Are compared with each other, a resistor R ₂ inserted in series in the return line (signal line 5 b) of the drive current I ₁ from the injector 1, and an injector drive unit The measured value of the drive current measured by the second current adjusting means (for example, volume) 23 provided in the interior of the base 2 for setting the overexcitation current target value I ₃ of the target current value, and the resistor R _2. And a second comparison means 24 for comparing the overexcitation current target value I ₃ from the current adjustment means 23. The result signal compared by the first comparison means 22 is fed back to the constant current power supply unit 14, and the result signal compared by the second comparison means 24 is fed back to the overexcitation current power supply unit 12. ing.

In FIG. 2, reference numerals 25 and 26 denote operational amplifiers called “voltage followers” that prevent an excessive current from flowing due to the voltage generated at both ends of the resistor R ₁ or the resistor R ₂ .

Next, the operation of the injector drive device configured as described above will be described. In FIG. 2, first, the engine ECU 3 outputs an injection command signal S ₂ containing the injector drive signal S ₃ and the interlock signal S ₄ to the injector drive unit 2. The injector drive signal S ₃ input to the injector drive unit 2 is shaped into a signal waveform that can be recognized by the input signal waveform shaping unit 10 as high level (H) and low level (L), and input to the overexcitation switch 13. To do. In the over-excitation switch 13, an injector drive signal S ₃ is a certain time from when the ON (e.g., 0.2 ms approximately) to generate a signal to ON only overexcitation current, ON signal to the gate of the MOS FET 15 Is output.

  At this time, an overexcitation current is generated from the overexcitation current power supply unit 12 and is input to the drain of the MOS FET 15. As a result, the MOS FET 15 supplies the overexcitation current to the source side only during the period of the ON signal input to the gate, and directs the overexcitation current output from the source through the first diode 16 to the adding unit 18. Shed.

On the other hand, the injector drive signal S ₃ whose waveform has been shaped by the input signal waveform shaping unit 10 is input to the overexcitation switch 13 and also to the constant current power supply unit 14 to generate a drive current I ₁ to be supplied to the injector 1. To generate a constant current. The constant current flows toward the adder 18 via the resistor R ₁ and the second diode 17.

As a result, the addition unit 18 adds the overexcitation current from the overexcitation current power supply unit 12 and the constant current from the constant current power supply unit 14 to generate a drive current I1 as _one signal, and the injector. 1 is applied.

At this time, by the feedback control means 20, and the current value measured by the resistance R ₂ which is inserted in series into the return line (signal line 5b) driving current I ₁ from the injector 1, the second current control means The over-excitation current target value I ₃ set at 23 is compared by the second comparison means 24 and the comparison result is fed back to the over-excitation current power supply unit 12. At the same time, the current value measured by the resistor R ₁ inserted in series in the circuit portion for measuring the drive current sent to the injector 1 and the constant current target value I set by the first current adjusting means 21. ₂ is compared by the first comparison means 22, and the comparison result is fed back to the constant current power supply unit 14.

  The second comparison means 24 and the first comparison means 22 compare the input measurement current value and the target current value, respectively, increase or decrease the output current value so that they match, and the second comparison means. The control current value of the overexcitation current is output from 24 to the overexcitation current power supply unit 12, and the control current value of the constant current is output from the first comparison means 22 to the constant current power supply unit 14.

Thereafter, an overexcitation current that is feedback-controlled is generated from the overexcitation current power supply unit 12 by the input of each control current value, and a constant current that is also feedback controlled is generated from the constant current power supply unit 14. In the same manner as described above, the addition unit 18 adds the overexcitation current from the overexcitation current power supply unit 12 and the constant current from the constant current power supply unit 14 to generate a new drive current I _1. 1 is applied.

By applying the drive current I ₁ thus feedback-controlled, the injector 1 causes the internal needle valve to be sharply lifted by applying a rising overexcitation current, and then lifting the needle valve by applying a constant current. Is held and the nozzle hole of the injection nozzle is opened to inject fuel. As a result, a constant drive current I ₁ that always follows the target current value is applied to the injector 1, and a constant fuel injection amount can be obtained with the lift amount of the needle valve of the injector 1 being constant. Further, with respect to the injector 1 provided in each of the plurality of cylinders, the drive current I ₁ can be controlled for each cylinder by the injector drive unit 2. Therefore, it is possible to suppress variations in output among the cylinders of the engine and to reduce engine vibration.

  FIG. 3 is a schematic view showing another embodiment of the injector driving device of the present invention. In this injector driving device, the target current value of the feedback control described above is determined by the engine ECU 3 according to the operating state of the engine, and the injector driving unit 2 is connected via the communication means 30 that connects the engine ECU 3 and the injector driving unit 2. And can be controlled by a command from the engine ECU 3. In this case, as the communication means 30, communication means such as serial communication, parallel communication, and optical communication may be used, or communication means that performs CAN (Controller Area Network) communication for vehicle control may be used. . FIG. 3 shows a case where CAN communication is used. Reference numeral 31 denotes a CAN bus, and reference numerals 32 a and 32 b denote termination resistors of the CAN bus 31.

FIG. 4 is a block diagram showing an internal configuration of the injector drive unit 2 in the other embodiment, and shows one injector drive unit 2 that supplies a drive current I ₁ to one injector 1. That is, as shown in FIG. 4, the feedback control target current value sent from the engine ECU 3 is input to the input section of the feedback control means 20 ′ of the injector drive unit 2 that inputs via the communication means 30. A communication port / signal processing unit 33 and a D / A converter 34 are provided, and the other configuration is exactly the same as in the case of FIG.

The communication port / signal processing unit 33 takes in a target current value of feedback control input via the communication unit 30 and amplifies the signal so that it can be handled by the feedback control unit 20 ′, or updates the target current value. The processing is performed. The D / A converter 34 converts the digital target current value signal input from the engine ECU 3 into an analog signal, and the constant current target value I ₂ in the target current value is compared with the first comparison value. Similarly, the overexcitation current target value I ₃ of the target current value is output to the second comparison means 24.

Next, the operation of the injector driving apparatus according to another embodiment configured as described above will be described with reference to FIGS. 5 is a flowchart showing the operation on the engine ECU 3 side, and FIG. 6 is a flowchart showing the operation on the injector drive unit 2 side. First, the operating state of the engine is detected by the operating state detection means 6 shown in FIG. 3 (step S1 in FIG. 5). Thus, for example, the rotation speed of the engine, load, coolant temperature, and detects the battery voltage and the like, and outputs to the engine ECU3 as the driving state detection signal S _1.

Then, engine ECU3 inputs the operation state detection signal S _1, to determine the injection period and injection timing and ignition timing and the target current value of the fuel (step S2). Then, the determined target current value is transmitted to the communication port / signal processing unit 33 in the feedback control unit 20 ′ shown in FIG. 4 via the communication unit 30 (step S3). Further, an injection command signal S ₂ comprising an injector drive signal S ₃ and an interlock signal S ₄ whose contents are the determined injection period, injection timing, ignition timing, etc. is shown in FIG. 4 via signal lines 7a and 7b. It transmits to the input signal waveform shaping section 10 shown (step S4).

As a result, the communication port / signal processing unit 33 in the feedback control means 20 ′ receives the target current value (step S5 in FIG. 6). Then, the communication port / signal processing unit 33 determines whether or not the fuel injection of the corresponding cylinder is finished (step S6). If the engine is still operating, the process proceeds to “NO” and enters step S7, and the target current value of the next fuel injection is updated using the received target current value. The updated target current value is input to the D / A converter 34 and subjected to D / A conversion processing (step S8), and is output as a constant current target value I ₂ and an overexcitation current target value I _3. .

At this time, the constant current target value I ₂ is output to the first comparison means 22, and the overexcitation current target value I ₃ is output to the second comparison means 24. Then, the first comparison means 22 compares the current value measured by the resistor R ₁ inserted in series with the circuit portion for measuring the drive current sent to the injector 1 with the constant current target value I ₂ . In the second comparison means 24 compares the current value measured by the resistance R ₂ which is inserted in series into the return line driving current I ₁ from the injector 1, the over-exciting current target value I _3.

  Then, the comparison results of the comparison means 22 and 24 are output as target current values (voltage values corresponding to the target current values) to the current power supply units 12 and 14 of the corresponding cylinders (step S9). That is, the comparison result of the second comparison unit 24 is fed back to the overexcitation current power supply unit 12, and the comparison result of the first comparison unit 22 is fed back to the constant current power supply unit 14.

Thereafter, an overexcitation current that is feedback-controlled is generated from the overexcitation current power supply unit 12 and a constant current that is also feedback-controlled is generated from the constant current power supply unit 14 in the same manner as shown in FIG. , the addition section 18, and the overexcitation current from overexcitation current power supply unit 12, a constant current from the constant current power source unit 14 are added, a new drive current I ₁ is applied is generated in the injector 1. Thereby, fuel is injected from the injector 1 (step S10).

By such an operation, the drive current I ₁ applied to the injector 1 can be controlled for each cylinder according to the operation state in accordance with the command of the engine ECU 3 from the outside of the injector drive unit 2. Further, with respect to the injector 1 provided in each of the plurality of cylinders, the drive current I ₁ can be controlled for each cylinder by the injector drive unit 2. Therefore, it is possible to suppress variations in output among the cylinders of the engine and to reduce engine vibration.

It is the schematic which shows embodiment of the injector drive device by this invention. It is a block diagram which shows the internal structure of the injector drive unit in said embodiment, and has shown about one injector drive unit which supplies a drive current to one injector. It is the schematic which shows other embodiment of the injector drive device of this invention. It is a block diagram which shows the internal structure of the injector drive unit in the said other embodiment, and has shown about one injector drive unit which supplies a drive current to one injector. It is a figure explaining operation | movement of the injector drive device by other embodiment, and is a flowchart which shows operation | movement by the side of engine ECU. Similarly, it is a figure explaining operation | movement of the injector drive device by other embodiment, and is a flowchart which shows operation | movement by the side of an injector drive unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Injector 2 ... Injector drive unit 3 ... Engine ECU
DESCRIPTION OF SYMBOLS 4 ... Injection nozzle 6 ... Operating condition detection means 10 ... Input signal waveform shaping part 11 ... Input signal monitoring part 12 ... Overexcitation current power supply part 13 ... Overexcitation switch 14 ... Constant current power supply part 20, 20 '... Feedback control means 21 ... 1st current adjustment means 23 ... 2nd current adjustment means 30 ... Communication means 33 ... Communication port / signal processing part 34 ... D / A converter

Claims (5)

An injector that injects fuel by lifting a needle valve that opens and closes a nozzle hole of an injection nozzle by a drive current applied to an internal drive element;
Means for generating a drive current for controlling the lift amount of the needle valve of the injector, and an injector drive unit for controlling the fuel injection amount by applying a drive current to the injector;
An engine control unit for sending a fuel injection command signal to the injector drive unit based on an engine operating state detection signal;
Injector drive device comprising:
The injector drive unit includes a feedback control unit that measures a drive current sent to the injector, compares the measured drive current with a target current value, and applies a drive current following the target current value to the injector. Drive device.   2. The injector drive device according to claim 1, wherein a resistor is inserted in series with a circuit portion for measuring a drive current sent to the injector inside the injector drive unit.   3. The injector driving device according to claim 1, wherein the target current value can be set by a current adjusting means provided inside the injector driving unit.   The target current value is determined by the engine control unit according to the operating state of the engine, sent to the injector drive unit via the communication means connecting the engine control unit and the injector drive unit, and the command from the engine control unit. The injector drive device according to claim 1, wherein the injector drive device can be controlled by the control unit.   The injector drive device according to any one of claims 1 to 4, wherein the injector is provided in each of a plurality of cylinders, and the drive current is controlled for each cylinder by the injector drive unit.

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