JP2009085043A - Drive device for fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain a stable operation state of an internal combustion engine even when a fuel injection valve is broken by detecting the failure of the fuel injection valve and performing failure time control. <P>SOLUTION: The drive device for the fuel injection valve is provided with a single cylinder type high pressure fuel pump, an excitation (high voltage) drive part for electric current applied to the fuel injection valve and an electric current holding drive part. In the drive device, to perform stable fuel injection control of the internal combustion engine when the excitation drive is abnormal, the fuel injection valve is driven by the holding drive part and fuel injection valve drive time by the holding drive part is determined based on fuel pressure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive device for a fuel injection valve used in an internal combustion engine.

  Conventionally, in a drive control device for a fuel injection valve, there has been a problem that when the high voltage system becomes abnormal, the fuel injection valve cannot be opened normally, so that stable fuel injection amount control cannot be performed. Therefore, when the high voltage system becomes abnormal, the supply of the fuel injection valve opening current supplied at a high voltage is stopped, the holding current is applied to open the fuel injection valve, and only the holding current is supplied. It is known to perform control to correct the fuel injection by correcting the response delay of the fuel injection valve caused by applying (refer to Patent Document 1).

  In addition, when the peak current for opening the fuel injector is not supplied (high voltage system is abnormal), the hold current is increased by using means for increasing the normal fuel injector hold current. It is known that by uniformly increasing the fuel injection valve, the desired fuel injection control can be performed (see Patent Document 2).

Japanese Patent Laid-Open No. 11-13524 JP 2002-295294 A

  The technique described in Patent Document 1 uses the same method as the normal control for the holding current itself, and corrects the fuel injection pulse width. When the fuel pressure at the time of high voltage system failure is high, the fuel injection valve is opened. Since it cannot be controlled, it is premised on a means for reducing the fuel pressure in addition to the fuel injection from the fuel injection valve, and an actuator with a high system cost that can independently control the fuel pressure to be lowered is required. If there is no means that can independently control the fuel pressure to be lowered, there is a problem that the operation of the internal combustion engine cannot be continued if the high voltage system fails in a high fuel pressure state.

  On the other hand, the technique described in Patent Document 2 is uniformly driven without separately using a supply current to the fuel injection valve necessary for opening the fuel injection valve and a current necessary for maintaining (maintaining) the valve open state. Since fuel injection is performed by increasing the current, unnecessary energy is consumed, leading to an increase in heat to the drive circuit and an increase in electricity consumption.

  In the present invention, even when a high voltage drive failure of the fuel injection valve occurs, the supply control of the fuel injection drive current based on the fuel pressure value is performed, so that the heat to the drive circuit or the increase in the electric consumption is not accompanied. An object of the present invention is to provide a fuel injection device that enables operation of an internal combustion engine.

  In order to achieve the above object, the present invention is a fuel injection valve drive device having a single cylinder type high-pressure fuel pump, and as the drive device for the fuel injection valve, excitation of a current applied to the fuel injection valve (high voltage) ) It has a drive unit and a current holding drive unit, and when the excitation drive is abnormal, the holding drive drive unit drives the fuel injection valve, and the fuel injection valve drive time by the holding drive unit is based on the fuel pressure Provide control means to determine.

  In addition, the present invention provides a fuel injection valve driving device, wherein the holding driving unit includes a first holding driving unit (Ih1) and a second holding driving unit (Ih2) having different currents.

  The present invention further includes means for estimating at least one of a temperature of a drive circuit of the holding drive unit and a temperature of the fuel injection valve based on a fuel injection valve drive time by the holding drive unit, and the temperature estimation Provided is a fuel injection valve drive device that calculates a target fuel pressure from a value.

  By performing the above control, a stable operation state of the internal combustion period can be ensured even when the fuel injection device of the in-cylinder fuel injection type internal combustion engine becomes abnormal.

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram showing a control system for a direct injection engine according to the control apparatus for an internal combustion engine of the present embodiment. In FIG. 1, air taken into the engine 1 is taken in from an input portion 4 of an air cleaner 3, passes through an intake air meter 5, passes through a throttle valve body 7 provided with a throttle valve 6 that controls the suction flow rate, and then enters a collector 8. to go into. Here, the throttle valve 6 is connected to a motor 10 that drives the throttle valve 6, and the throttle valve 6 can be operated by driving the motor 10 to control the amount of intake air.

  The intake air that reaches the collector 8 is distributed to the intake pipes 19 connected to the cylinders 2 of the engine 1 and led to the combustion chambers in the cylinders 2.

  On the other hand, fuel such as gasoline is sucked and pressurized from a fuel tank 11 by a fuel pump 12 and supplied to a fuel system in which a fuel injection valve 13 and a variable fuel pressure regulator 14 for controlling the fuel pressure within a predetermined range are provided. The The fuel pressure is measured by a fuel pressure sensor 34. Fuel is injected into the combustion chamber from a fuel injection valve 13 that opens a fuel injection port in the combustion chamber of each cylinder 2. The air that has flowed into the combustion chamber and the injected fuel are mixed and ignited by the spark plug 35 from the ignition coil 17 by the piezoelectric and burned.

  Exhaust gas combusted in the combustion chamber of the engine 1 is guided to the exhaust pipe 28 and discharged outside the engine 1 through the catalyst.

  A signal indicating the intake flow rate is output from the air flow meter 5 and is input to the control unit 15. Further, a throttle sensor 18 for detecting the opening of the throttle valve 6 is provided in the throttle body 7. Is attached, and its output is also input to the control unit 15.

  The crank angle sensor 16 is rotationally driven by a cam shaft (not shown) of the engine 1 and detects the rotational position of the crank shaft with an accuracy of at least about 1 to 10 °. Signals are also input to the control unit 1.

  Each signal controls fuel injection timing, injection flow rate (fuel injection valve pulse width control), ignition timing, and the like.

  The A / F sensor 20 provided in the exhaust pipe 28 detects and outputs the actual operating air-fuel ratio from the exhaust gas component, and the signal is also input to the control unit 15.

  FIG. 2 is an example showing a configuration of a control device for a failure of the fuel injection device according to the control device for the internal combustion engine of the present embodiment. The fuel injection valve 13 incorporates a coil 13a coil for driving an electromagnetic valve in the fuel injection valve, and the power is injected from the battery 30 via the control unit 15 via the fuses 43a and 43b and the relay 31. Led to the valve. In order to drive the fuel injection valve even under high fuel pressure, the control unit 15 supplies a high voltage (for example, 65V) higher than the battery voltage generated by the high voltage generation circuit 15a at the beginning of driving the fuel injection valve. High current is supplied and the high voltage supply time is controlled. Next, when a current sufficient to open the fuel injection valve is supplied, the high voltage supply is stopped and the battery voltage is supplied to supply a current that can maintain the open state of the fuel injection valve. . The voltage and current supplied to the fuel injection valve are controlled by ON / OFF control of the injector drive circuit (Hi) 15b and the injector drive circuit (Lo) 15c. The ON / OFF control is applied to the coil 13a in the fuel injection valve. The flowing current is detected and performed by the drive custom IC 15d. The details of the current generation for driving the fuel injection valve will be described with reference to FIGS.

  Next, the CPU 26 in the control unit 15 performs self-diagnosis determination of the fuel injection system in block 26a. Here, based on the case where the abnormality is determined by the self-diagnosis or the case where the abnormality is not determined (normal), the current waveform form supplied to the fuel injection valve is designated by the block 26b. The current waveform form can be specified by communicating between the CPU 26 and the fuel injection valve drive custom IC 15d. Here, the current waveform form will be described later with reference to FIGS. Further, since the communication method between the CPU 26 and the fuel injection valve drive custom IC 15d is not related to the present invention, detailed description is not necessary.

  Next, in block 26C, a pulse width for driving the fuel injection valve is calculated based on the case where the abnormality is determined by the self-diagnosis or the case where the abnormality is not determined (normal). In case of failure, the pulse width is calculated and supplied longer than normal. Since this method is disclosed in Japanese Patent Application Laid-Open No. 11-13524, detailed description is not necessary.

  As described above with reference to FIG. 2, the present invention controls the fuel injection control by appropriately changing the drive current and pulse width of the fuel injection valve based on the self-diagnosis result.

  FIG. 3 shows an example of a circuit configuration for driving and controlling the fuel injection valve described in FIG.

  A voltage higher than the battery voltage is generated by a high voltage generation circuit (for example, a DC-DC converter) shown in the drawing. The generated high voltage supplies power to the coil 13a in the fuel injection valve via the diode and the transistor TR_HiVboost provided upstream of the fuel injection valve, and turns on the transistor TR_Low provided downstream of the fuel injection valve. By passing the current.

  In the control for supplying a high voltage, the current flowing through the coil 13a current in the fuel injection valve is detected by the shunt resistance shown in the figure, and when the desired current is reached, the supply of the high voltage is stopped and the next driving step is performed. It shifts to the drive control by the battery voltage which is. As the next step of driving the fuel injection valve, the voltage supplied by the holding power supply circuit (holding power = battery voltage) shown in the figure is connected to the transistor TR_HiVb provided upstream of the fuel injection valve via the diode. Thus, the power is supplied to the coil 13a in the fuel injection valve, and a current is passed by turning on the transistor TR_Low provided downstream of the fuel injection valve in the same manner as the high voltage supply. The current flowing through the coil 13a in the fuel injection valve by the battery voltage is controlled by detecting the current by the shunt resistance shown in the figure as described above. Although omitted in the drawing, the drive control of each transistor for flowing a current to the fuel injection valve is executed by the drive custom IC described in FIG. An example of the form of current flowing through the fuel injection valve of the present invention described above will be described with reference to FIGS.

  FIG. 4 is a diagram showing an example of the drive current of the normal fuel injection valve of the present invention.

  The injector (fuel injection valve) drive pulse signal TI shown at the top in the figure is a signal supplied from the CPU 26 to the fuel injection valve custom IC 15d, and the valve in the fuel injection valve is opened in the pulse signal section (TI). Valve and fuel injection.

  Next, an injector (fuel injection valve) drive current switching signal Thold1 in the figure is a signal used for timing of switching a current value to be supplied to the fuel injection valve described below, and the fuel injection valve custom IC 15d from the CPU 26 as in the case of the TI. Is a signal supplied to

  Next, the injector (fuel injection valve) current waveform shown in the figure is an example of the current flowing through the fuel injection valve for driving the fuel injection valve generated by the drive circuit and the drive method shown in FIGS. It is. The high voltage described with reference to FIG. 3 is supplied until the desired current value Ip shown in the figure is reached, and when the voltage reaches Ip, the high voltage supply is terminated. Thereafter, the power supply to the fuel injector is switched from the high voltage to the battery voltage, and during the period when the Thold1 pulse signal is supplied, the current flowing through the fuel injector is controlled to the desired value Ih1. Thereafter, during the period in which the pulse signal TI is supplied and the period in which the Thold1 pulse signal supply is completed, the current is controlled to a desired current value Ih2 lower than Ih1.

  The valve operation in the injector (fuel injection valve) shown at the bottom in the figure is opened by the current value, the opened state is maintained, and the valve is closed after the TI pulse signal supply ends. It shows the behavior that becomes the action.

  As described above, even when the fuel pressure is high, the fuel injection valve is controlled stably by overcoming the fuel pressure, and the fuel injection amount supplied to the internal combustion engine is controlled.

  However, when the fuel pressure is high and the high voltage supply means (high voltage generation circuit, nine drive transistor, drive custom IC) fails and the current Ip necessary for the fuel injection valve cannot be supplied. Therefore, the desired fuel injection amount control cannot be performed, and a stable operation state of the internal combustion engine cannot be maintained. In this case, the fuel injection valve is driven by the normal current control of Ih1 and Ih2, and even when the high voltage means function is in a failure state, a predetermined amount of fuel injection control is performed, and the operating state of the internal combustion engine Can be secured.

  FIG. 5 is a diagram showing an example of a fuel injection drive current waveform when the high voltage function of the present invention fails.

  As described with reference to FIG. 4, current is supplied to the fuel injector by the injector (fuel injector) drive pulse signal TI and the Thold pulse signal. Here, when a failure is detected as described with reference to FIG. 2, the high voltage supply is cut off and the drive waveform based only on the battery voltage is designated by the fuel injection valve drive waveform command by the block 26b of FIG. The high voltage supply is cut off by the fuel injection drive custom IC (the transistor TR_HiVboost described with reference to FIG. 3 is turned off), and current is supplied to the fuel injection valve.

  As a result, the current indicated by the injector (fuel injection valve) drive current waveform shown in the middle of FIG. 5 flows to the fuel injection valve, and the current is controlled by the currents Ih1 and Ih2 described in FIG. It will be. Here, switching between Ih1 and Ih2 is performed by a Thold1 pulse signal as in FIG. As a result, the operation is performed like the valve operation in the injector (fuel injection valve) shown in the lowermost stage of FIG. Here, since the operation of the injector (fuel injection valve) valve operation of FIG. 4 is not supplied with the current that opens the fuel injection valve at a high speed as shown in FIG. 5, the opening of the fuel injection valve is as shown in FIG. On the other hand, the valve opening time becomes longer, and the time until the valve opening is greatly influenced by the fuel pressure of the internal combustion engine (the relationship with the fuel pressure will be described in detail in FIG. 7 described later). .

  Next, the flow rate characteristic of the fuel injection valve in the drive current waveform of the fuel injection valve described in FIGS. 4 and 5 will be described.

  FIG. 6 is an example showing the fuel injection flow rate characteristics when the fuel injection valve drive of the present invention is normal and failure.

  The solid line shown in the figure is the injection quantity characteristic of the fuel injection valve at the normal time (normal fuel injection valve supply current waveform driving explained in FIG. 4).

  On the other hand, the dotted line in the figure is the flow rate characteristic of the fuel injection valve without high voltage supply (Ih1, Ih2 current waveform driving by only the battery voltage without supplying the high voltage power source described in FIG. 5).

  Thus, when there is no high voltage supply (dotted line) when normal (solid line), the valve opening force of the fuel injection valve is reduced, which requires time until the valve opens. Therefore, it is necessary to supply a long pulse width for fuel injection (horizontal axis in the figure). However, if the pulse width is sufficiently controlled until the fuel injection valve is opened, a desired fuel injection amount can be supplied to the internal combustion engine.

  Next, FIG. 7 is an example showing the relationship between the Thold 1 supply time of the present invention and the fuel pressure at which fuel can be injected.

  As described with reference to FIGS. 5 and 6, when the high voltage supply is not performed, the force to open the fuel injection valve is reduced. Therefore, the fuel injection valve opens under the fuel pressure and the fuel pressure. The valve relation is related to Thold1, which is the time for supplying the fuel injection valve drive current Ih1.

  As the Thold 1 supply time is increased, the valve opening force until the fuel injection valve is opened is ensured, and it is necessary to increase the Thold 1 pulse width as the fuel pressure increases. If such a long Thold 1 is supplied, fuel injection is possible even at the set fuel pressure of the internal combustion engine shown in the figure. The uppermost dotted line shown in the figure is for the normal state (normal fuel injection valve supply current waveform driving explained in FIG. 4), and has a high fuel injection valve opening force due to high voltage supply. This is shown as a reference characteristic that is relatively unrelated to Thold1.

  In this way, even when the high voltage means function is in a failure state, a predetermined amount of Thold1, which is the fuel injection valve drive current value Ih1 supply time, is controlled based on the fuel pressure as compared with the normal control state. Fuel injection control can be performed to ensure the operating state of the internal combustion engine.

  Next, FIG. 8 is an example showing the relationship between the Thold 1 pulse width of the present invention and the heat of the fuel injection valve drive circuit and the fuel injection valve.

  When Thold1 is controlled to be longer than the normal control state due to the failure of the high voltage means function, a high current (Ih1) value flows through the fuel injection valve drive circuit and the fuel injection valve for a long period of time. I get fever. The amount of heat generation increases as the Thold 1 supply time is increased, and the temperature exceeds the temperature allowed by the drive circuit and the fuel injection valve. If the fuel injection valve is driven and controlled as it is, the drive is activated. Because it causes thermal damage to the circuit or fuel injection valve, it cannot be used as it is.

  Next, FIG. 9 is an example showing the relationship between the fuel injection valve driving state and the operating time of the internal combustion engine when the high voltage means of the present invention functions.

  In this way, the fuel injection valve drive circuit and the fuel injection valve generate higher heat depending on the operation time of the internal combustion engine (or the speed of the internal combustion engine) due to the heat balance of the surrounding heat sink and self-heating. When the Thold1 supply time is longer than a predetermined value, there are upper limits of the operation time and the rotational speed of the internal combustion engine, and when the upper limits are exceeded, the temperature exceeds the temperature allowed by the drive circuit and the fuel injection valve. It will be a thing. On the other hand, when the Thold 1 supply time is shorter than the predetermined value, the temperature allowed by the drive circuit and the fuel injection valve is independent of the operation time and the rotational speed of the internal combustion engine due to the relationship between the heat sink of the surrounding and the self-heating heat. Not reach.

  In this way, even if the high voltage means function fails, the Thold1 supply time cannot be simply increased in order to ensure the operation of the internal combustion engine.

  Therefore, if the relationship with the fuel pressure described with reference to FIG. 7 can be satisfied and the relationship shown in FIG. 8 and FIG. 9 can be maintained, the fuel that can operate the internal combustion engine even if the high voltage means function fails. The injection amount can be controlled, and the influence on the heat to the fuel injection drive circuit and the fuel injection can be avoided. Therefore, when the high voltage means function fails, the fuel pressure can be controlled to be able to be injected even with Thold 1 which does not affect the heat to the fuel injection drive circuit and the fuel injection.

  FIG. 10 is an example of a control flowchart of the present invention.

  The control method of the present invention based on the contents described above will be described with reference to FIG. Block 101 determines whether the high voltage means function has failed. When the block 101 determines that the high voltage means function has failed, the block 102 stops the fuel injection valve drive current supply by the high voltage. Here, the driving stop method is the same as that described with reference to FIGS. 2 and 3, and need not be described here. Further, the high voltage drive stop may be any of the fuel injection valves of all the cylinders of the internal combustion engine or only the cylinder specified by the self-diagnosis of the block 101, but it is preferable to stop all the cylinders. Simplification of fuel injection control of internal combustion engine and stabilization of drivability at the time of failure (Due to the difference in fuel injection amount control accuracy between the failed cylinder and normal cylinder, there is a possibility that the drivability of the internal combustion engine may deteriorate, It is possible to stabilize the drivability by controlling the same fuel injection in the cylinder). Next, in block 103, a Thold1 pulse width is calculated based on the fuel pressure of the internal combustion engine. The calculation method may be either a calculation formula based on the fuel pressure or a table calculation based on the fuel pressure. At least Thold1 based on the fuel pressure is obtained. In block 104, fuel injection pulse width correction is performed by increasing the valve opening time of the fuel injection valve due to high voltage drive stop. Thereby, even if it is a high voltage drive stop state, desired fuel injection amount control can be performed.

  FIG. 11 shows an example of a flowchart of the heat estimation control of the drive circuit and the fuel injection valve of the present invention. Block 103 is the control block diagram described in FIG. In block 111, the fuel injection drive circuit and the fuel are set with parameters of at least one of the rotational speed (fuel injection cycle) of the internal combustion engine, the operation time of the internal combustion engine, the coolant temperature of the internal combustion engine, and the Thold1 pulse width. This is to estimate the heat (self-heating) of the injection valve. Based on the estimated heat value calculated in block 111, a target fuel pressure of the internal combustion engine is calculated in block 112. As a result, the upper limit value of the target fuel pressure that can be set within the heat-affected range of the fuel injection drive circuit and the fuel injection valve can be set, and more stable without applying means for reducing the fuel pressure more than necessary. It is possible to ensure the operating state of the internal combustion engine. Here, the relationship between the fuel pressure and the heat of the fuel injection drive circuit and the fuel injection valve is as described with reference to FIGS.

  FIG. 12 is a diagram showing an example of the effect on the operation region of the internal combustion engine when the high voltage means function according to the present invention fails.

  The dotted line shown in the figure indicates the operable region when the high voltage means function fails when the present invention is not applied, and the lower side of the dotted line is operable. On the higher internal combustion engine speed side, the cycle for supplying Ih1 is accelerated. As a result, the fuel injection drive circuit and the fuel injection valve are subject to thermal restrictions, and operation exceeding the predetermined engine speed becomes unacceptable. . As described above with reference to FIGS. 8 and 9, the operable rotational speed decreases as the traveling time of the internal combustion engine becomes longer. On the other hand, the operable region according to the present invention is indicated by a solid line in the figure. By supplying the minimum necessary amount of Ih1 based on the fuel pressure of the internal combustion engine, the fuel pressure of the internal combustion engine is appropriately controlled without being subject to thermal restrictions of the fuel injection drive circuit and the fuel injection valve (Thold1 required pulse width) Therefore, the operating range of the internal combustion engine can be expanded. In addition, the present invention can be realized without increasing the number of necessary parts and the cost of the internal combustion engine control device.

The control system figure of the direct injection engine which concerns on the control apparatus of the internal combustion engine of this invention. An example which shows the structure of the control apparatus at the time of the failure of the fuel-injection apparatus which concerns on the control apparatus of the internal combustion engine of this invention. The figure which showed an example of the circuit structure which drive-controls the fuel injection valve of this invention. The figure which showed an example of the drive current of the normal time fuel injection valve of this invention. The figure which showed an example of the fuel-injection drive current waveform when the said high voltage function of this invention fails. The fuel-injection flow characteristic figure at the time of the fuel-injection valve drive of this invention being normal and failure. FIG. 4 is a relationship diagram of Thold1 supply time and fuel pressure capable of fuel injection according to the present invention. The Thold1 pulse width of this invention, the fuel injection valve drive circuit, and the heat relationship figure of a fuel injection valve. The relationship diagram of the fuel-injection-valve drive state when the said high voltage means of this invention functions, and the operation time of an internal combustion engine. The control flowchart figure of this invention. The flowchart of the heat estimation control of the drive circuit and fuel injection valve of this invention. An example of the effect on an internal combustion engine operation area | region when the high voltage means function by this invention fails.

Explanation of symbols

13 Fuel injection valve 26 Calculation means (CPU)
15a High voltage generation circuit 15b Fuel injection valve drive circuit (Hi)
15c Fuel injection valve drive circuit (Lo)
15d Fuel injection valve drive custom IC
26b Fuel injection valve drive waveform command means

Claims (6)

  A fuel injection valve drive device having a single cylinder type high-pressure fuel pump, wherein the fuel injection valve drive device includes an excitation drive unit for current applied to the fuel injection valve and a current holding drive unit, and the excitation A fuel injection valve drive device characterized in that when the drive unit is abnormal, the holding drive unit drives the fuel injection valve, and the fuel injection valve drive time by the holding drive unit is determined based on fuel pressure.   2. The fuel injection valve drive device according to claim 1, wherein the holding drive unit includes a first holding drive unit (Ih1) and a second holding drive unit (Ih2) having different currents. Valve drive device.   3. The fuel injection valve drive device according to claim 2, wherein the first drive unit has a higher current value than the second drive unit. 4.   The fuel injection valve drive device according to any one of claims 1 to 3, wherein when the excitation drive is abnormal, the holding drive drive unit drives the fuel injection valve. A drive device for a fuel injection valve, characterized in that the drive time of the holding drive section (Ih1) is determined based on the fuel pressure.   A fuel injection valve drive device having a single cylinder type high-pressure fuel pump, wherein the fuel injection valve drive device has an excitation (high voltage) drive unit for current applied to the fuel injection valve and a current holding drive unit. When the excitation drive is abnormal, the holding drive drive unit drives the fuel injection valve, and based on the fuel injection valve drive time by the hold drive unit, the temperature of the drive circuit of the holding drive unit and the fuel injection valve A fuel injection valve driving device comprising means for estimating one or more of temperatures, and calculating a target fuel pressure from the estimated temperature value.   6. The fuel injection valve drive device according to claim 5, wherein the temperature of the drive circuit of the holding drive unit or the means for estimating the temperature of the fuel injection valve is the number of revolutions of the internal combustion engine, the operation time of the internal combustion engine, and the coolant temperature. A fuel injection device for an internal combustion engine, which is calculated based on any one or more parameters.

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