JP2011028950A - Fuel injection control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device which has a diagnosis function of an injector and supplies an inrush current again while a valve is maintained open by a holding current based on a diagnosis result so as to maintain the open valve state of the injector. <P>SOLUTION: The fuel injection control device includes: an energization control means for opening a valve element of the injector by supplying the inrush current to an electromagnetic coil of the injector (T0), and maintaining the open valve state of the valve element by supplying the holding current (T1), and a diagnosing means for controlling the injector by a previously set energization pattern, and diagnosing the operating state of the injector at least at a start of a vehicle based on a pressure difference between an upstream side and downstream side of the injector and the previously set energization pattern of the injector. The energization control means supplies not only the holding current for holding the open valve state of the injector, but also the inrush current (T4) again while the injector is maintained open based on information from the diagnosing means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel injection control device for supplying fuel gas to a fuel cell stack by controlling an injector.

  2. Description of the Related Art Conventionally, a fuel cell system that generates power by supplying fuel gas and oxidizing gas to a fuel cell stack has been proposed, and a fuel cell vehicle equipped with a fuel cell stack is known as a power source for a low pollution vehicle. The fuel cell system for vehicles includes a high-pressure hydrogen tank as a fuel gas supply source, a regulator that reduces the hydrogen gas in the high-pressure hydrogen tank to a certain supply pressure, and a gas of hydrogen gas according to the operating state of the fuel cell system And an injector that controls the flow rate and gas pressure.

  An injector is an electromagnetically driven on / off valve that adjusts an injection amount by driving an electromagnetic coil at a predetermined driving cycle to separate a valve body from a valve seat, and is widely used as a fuel injection electromagnetic valve for an internal combustion engine. ing. As a method for controlling the injector, as disclosed in Patent Document 1, an inrush current is caused to flow through the electromagnetic coil by using a switching element to quickly open the valve body of the injector, and then smaller than the inrush current. A fuel injection control device having a holding means for holding a valve open state of a valve body with a holding current is disclosed.

  In general, since such a fuel injection control device is an open control that does not have a self-diagnosis function, there is a problem that it is difficult to diagnose whether the fuel injection control device is operating normally. Therefore, Patent Document 2 discloses a diagnostic device for diagnosing a fuel injection control device. The diagnostic device of Patent Document 2 monitors a current waveform of an injector and compares the valve opening current diagnostic window set to the injector injection time waveform with a plurality of determination values set in advance for each holding current diagnostic window. Diagnose.

  Patent Document 3 discloses not only a self-diagnostic function but also an injector that continues during all or part of the holding current energization period in addition to the inrush current energization when an injector valve closing and fixing failure is detected. Discloses a system that attempts to open the injector by energizing an inrush current.

JP 2002-295294 A Japanese Patent Laid-Open No. 11-13519 JP 2008-140619A

  However, if the current required to keep the valve open temporarily decreases due to aging of the electromagnetic coil of the injector, etc., the injector will not be able to keep the valve open and will close, and the rush will need to be opened again. The injector cannot be opened until current is supplied. If the injector valve opening and holding time is short, the valve will be opened with the inrush current again.However, if the valve opening and holding time is long, the injector electromagnetic coil The valve opening cannot be maintained only by the holding current, and closing the valve in the middle causes a reduction in the power of the vehicle due to a decrease in the output of the fuel cell.

  Therefore, the present invention has a diagnostic function based on the pressure difference between the upstream side and the downstream side of the injector, and maintains the injector's valve open state. It aims at providing the fuel-injection control apparatus which can supply.

  In order to achieve the above object, a fuel injection control device according to the present invention supplies a pre-pressurized fuel gas to a fuel cell stack by an injector, and controls the injector. An inrush current is supplied to the electromagnetic coil to open the valve body of the injector, and an energization control means for supplying a holding current to keep the valve body open, and to control the injector with a preset energization pattern In addition, based on the pressure difference obtained by the pressure sensor on the upstream side of the injector and the pressure sensor on the downstream side of the injector, and a preset energization pattern of the injector, a diagnosis for diagnosing the operating state of the injector at least at the start of the vehicle And the energization control means maintains the valve open state of the injector based on the information of the diagnosis means. Not only holding current which, and supplying a rush current again during open-valve state hold.

  The inrush current is a current that flows when a drive voltage with a duty ratio of 100% is passed through the electromagnetic coil of the injector, and the holding current is a current that flows when a drive voltage that is PWM-controlled is passed through the electromagnetic coil. Furthermore, the valve opening time of the injector is the total time in which the inrush current for the power necessary for opening the valve is supplied for a predetermined time, and then the holding current for the power required for holding the valve is further supplied for the predetermined time.

  Here, what is important is the timing at which the inrush current is inserted during energization of the holding current, and it is necessary to obtain an appropriate timing. Therefore, at the time of diagnosis, the diagnosis means acquires a pressure difference corresponding to the energization pattern of the injector, and supplies the inrush current again based on the pressure difference and the pre-stored pressure difference stored in advance. The resupply time is obtained and notified to the energization control means. More preferably, the energization control means supplies an inrush current to the injector at every resupply time obtained by the diagnosis means.

  By using the fuel injection control device according to the present invention, a diagnosis process based on the pressure difference between the upstream side and the downstream side of the injector is executed, and the valve opening state of the injector is held. There is an effect that a necessary fuel injection amount can be secured by supplying the rush current again while the valve is held.

It is a lineblock diagram of a fuel cell system which has a fuel injection control device concerning this embodiment. FIG. 2 is a time waveform diagram of an INJ (injector) control signal, a drive signal, a valve body opening degree, and a pressure in a state in which the injector valve body is closed during an injector open holding period by the fuel injection control device of FIG. 1. It is a flowchart figure which shows the flow of the diagnostic process of the injector by the fuel-injection control apparatus of FIG. FIG. 4 is a time waveform diagram of an INJ control signal, a drive signal, a valve body opening degree, and a pressure during the injector diagnosis of FIG. 3. FIG. 4 is a time waveform diagram of a drive signal, a valve body opening degree, and a pressure in an effect check of a preventive measure selected in the diagnosis process of FIG. 3.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 shows a fuel cell system 10 having a fuel injection control device 31. The fuel injection control device 31 according to the present embodiment checks the operating state of the injector 16 by a diagnostic process described later without applying a load to the control device that controls the fuel cell system 10, and keeps the injector 16 open. This solves the problem of inadvertently closing the valve.

  The fuel cell system 10 includes a gas supply system that takes in hydrogen gas as fuel gas and oxygen-containing air as an oxidant gas and supplies the gas to the fuel cell stack 21, and generates electric power generated by the fuel cell stack 21 with a motor 33 or a battery. And an electric power supply system to be supplied to 35. Next, a power supply system and a gas supply system will be described.

  The power supply system drives the motor 33 by PWM-controlling the power generated by the fuel cell stack 21 by the inverter 32. A part of the electric power is charged by the battery 35 via the DC / DC converter 34, and the motor 33 is driven by the electric power of the battery 35 when necessary.

  The gas supply system has a fuel gas supply channel for supplying fuel gas and an oxidizing gas supply channel for supplying oxidizing gas. In the fuel gas supply channel, a hydrogen gas shut-off valve 12, a regulator 13 for depressurizing the high-pressure hydrogen gas, and a temperature of the depressurized hydrogen gas are provided downstream from the hydrogen tank 11 for storing the high-pressure hydrogen gas. Temperature sensor 14 to be measured, upstream of the injector 16, upstream pressure sensor 15 to measure the pressure of the decompressed hydrogen gas, injector 16, pressure downstream of the injector, pressure adjusted by the injector 16 Hydrogen gas is supplied to the fuel cell stack 21 by the downstream pressure sensor 17 that measures

  Further, the fuel gas supply flow path includes a circulation pump 18 that circulates hydrogen gas discharged without being consumed in the fuel cell stack 21 to the supply side, a purge valve 19 that discharges the remaining hydrogen gas, and discharged hydrogen gas. A diluter 26 for diluting the gas and a muffler 27 for discharging the diluted hydrogen gas to the atmosphere.

  The oxidant gas supply channel includes a filter 25 that removes foreign matters when air is sucked from the atmosphere, an air compressor 24 that compresses and discharges air, and a humidifier 23 that applies appropriate humidity to the sucked air. Oxidizing gas is supplied to the fuel cell stack 21. The remaining wet oxidizing gas discharged from the fuel cell stack 21 passes through the regulator 22 and is supplied to the humidifier 23. The discharged oxidizing gas passes through the diluter 26 and is released to the atmosphere via the muffler 27. The

  Next, the situation in which the valve body closes during the holding time will be outlined. Here, the situation in which the holding current decreases for a moment during the holding time is called holding current cracking. Although there is no change in the driving signal supplied to the electromagnetic coil of the injector by the switching element, etc., the holding current cracking is affected by the influence of the driving force weakened by the deterioration of the electromagnetic coil and the vibration applied to the injector body. The valve body is closed without being kept open.

  FIG. 2 shows an INJ (injector) control signal, a drive signal, a valve body opening degree, and a pressure in a state in which the valve body of the injector is closed during the opening time of the injector by the fuel injection control device 31 of FIG. These time waveform diagrams are shown over three cycles (1) to (3). The drive signal in FIG. 2 shows the current waveform supplied to the electromagnetic coil of the injector, the solid line shows a normal state, and the broken line shows a holding current crack that is an abnormal state. The pressure is a measurement waveform of the downstream pressure sensor 17, and similarly, a solid line indicates a normal state and a broken line indicates an abnormal state.

  First, the normal state will be described. The INJ control signal in FIG. 2 indicates the valve opening time (T) of the injector, and the drive signal flows after a rush time (T0) as a rush current for the power necessary for valve opening with a drive voltage with a duty ratio of 100%. The current that flows when the PWM-controlled drive voltage is applied to the electromagnetic coil is passed as a holding current for the power required to hold the valve open for a holding time (T1). When the INJ control signal is “open”, an inrush current is supplied for T0 time to open the valve body, and the valve body is opened. Next, when the holding current is supplied for T1 time, the valve body is kept in the open state with a small current value, and the pressure of the hydrogen gas increases.

  When the INJ control signal is “closed”, the holding current is stopped and the opening of the valve body is “closed”, so that the pressure is reduced by the hydrogen gas continuously flowing out to the fuel cell stack 21. Hereinafter, the pressure fluctuation as shown by the solid line in FIG. 2 is shown.

  Next, the abnormal state will be described. In FIG. 2, if a holding current crack occurs in one cycle, the valve opening state is smaller than that of the INJ control signal. Furthermore, a holding current crack occurs again in three cycles, and if it reaches a normal state, the pressure reaching P1 increases to a pressure P2 that is lower than P1, so the output of the fuel cell stack is reduced. Will cause.

  However, since the holding current cracking due to the deterioration or vibration of the electromagnetic coil does not occur frequently and the holding current cracking period is short (pulse-like), it is difficult to detect by monitoring the drive signal. Therefore, in the present embodiment, after performing many injector diagnosis processes and confirming an increase in the frequency of holding current cracking, it is decided to take preventive measures against the holding current cracking.

  FIG. 3 shows the flow of the diagnosis process of the injector 16 by the fuel injection control device 31 of FIG. 1, and FIG. 4 shows the INJ drive signal, drive signal, valve opening and pressure (downstream) during the injector diagnosis of FIG. Side)).

  The execution timing of the injector diagnosis is when the vehicle is started, when an injector-related warning is detected, or when a check by a dealer is performed. The injector diagnosis of FIG. 3 starts at such an execution timing, and it is determined in step S10 whether any of the above execution timings is reached. If it is the execution timing of the above-described injector diagnosis, a check is performed in step S12. For convenience of explaining the injector diagnosis, a case where there is an abnormality in the injector will be described.

  The injector diagnosis in step S12 is performed by the INJ control signal for the diagnosis pattern stored in advance in the fuel injection control device 31 of FIG. 1, and the fuel cell stack is detected by the hydrogen gas and the oxidizing gas supplied at the time of the diagnosis. The generated power charges the battery 35 via the DC / DC converter 34.

  In step S <b> 12, the fuel injection control device 31 first measures the temperature of the hydrogen gas by the temperature sensor 14, and measures the pressure of the hydrogen gas upstream and downstream of the injector 16 by the upstream pressure sensor 15 and the downstream pressure sensor 17. taking measurement. This is because the density of the hydrogen gas is affected by temperature and pressure, and correction is performed due to differences in measurement conditions. Before operating the injector, the pressure value of the upstream pressure sensor 15 is PA1, and the pressure of the downstream pressure sensor 17 is PA2.

  Next, according to the energization pattern set longer than the normal valve opening time, the INJ control signal in FIG. 4 is set to the TC time “open” state, the inrush current is supplied for T0 time, and then the holding current is supplied for T1 time. At this time, the pressure of the downstream pressure sensor 17 gradually increases from PA2 to PA1, and a holding current crack occurs in the middle, so pressurization is stopped and the pressure is reduced, and the state is closed after the end of the TC time. The pressure difference from PA1 becomes α.

  The fuel injection control device 31 obtains the flow rate of the hydrogen gas based on the TC time, the volume downstream of the injector stored in advance, and the pressure difference α, and from the valve opening to the closing of the valve body. The crack occurrence time T2, which is time, is calculated and stored in the internal memory. Next, in step S14, it is determined whether or not the predetermined number of necessary preventive measures has been reached. If the preventive measures are necessary, selection of preventive measures based on the plurality of stored crack occurrence times T2 ( Move to step S16).

  In this embodiment, the following two types of preventive measures are set as preventive measures. The first preventive measure is that, after measuring many crack occurrence times T2, when the holding current is output during the holding time in which the holding current time exceeds the cracking time T2 in the INJ control signal, the inrush current is set to 1 during the holding time. It is a method of supplying only once. The second preventive measure is a method in which the inrush current is repeatedly supplied during the holding time with a period equal to or shorter than the average crack occurrence time T2. From experience, it is known that the probability of current cracking occurring at a longer holding time is higher than the probability of holding current cracking occurring at a short holding time, and thus the above preventive measures are effective.

  FIG. 5 shows changes over time in the drive signal, the valve opening, and the pressure in the effect check of the preventive measure selected in the diagnosis processing of FIG. 3 (step S18). As shown in FIG. 5, it can be seen that the holding valve is not closed even if the holding current crack occurs.

  In step S16 in FIG. 3, the fuel injection control device 31 first selects the first preventive measure, sets a time T3 over the crack occurrence time T2 in FIG. 5, and supplies a new inrush current for T4 time. Create an energization pattern. Next, the effect check of step S18 is performed in the same manner as the check execution of step S12. If it is confirmed by the effect check in step S12 that the desired pressure P1 corresponding to the INJ control signal is obtained, the diagnosis process is terminated. After that, the actual control of the injector is executed including the above preventive measures.

  If the first preventive measure does not improve, the second preventive measure is implemented. However, an increase in the inrush current during the holding time may adversely affect the electromagnetic coil of the injector. For this reason, it is also preferable to suppress the inrush current holding time T4 to half or less of the inrush current holding time T0.

  As described above, the fuel injection control device according to the present embodiment has a diagnostic function based on the pressure difference between the upstream side and the downstream side of the injector, and maintains the valve open state of the injector. Thus, by supplying the rush current again while the valve is being held by the holding current, it is possible to prevent the output of the fuel cell stack from being lowered.

  In this embodiment, the fuel injection control device for the injector in the fuel cell system has been implemented. However, the present invention is not limited to this, and the fuel injection control device for an internal combustion engine can be suitably used. Needless to say.

  DESCRIPTION OF SYMBOLS 10 Fuel cell system, 11 Hydrogen tank, 12 Shut-off valve, 13, 22 Regulator, 14 Temperature sensor, 15 Upstream pressure sensor, 16 Injector, 17 Downstream pressure sensor, 18 Circulation pump, 19 Purge valve, 21 Fuel cell stack, 23 Humidifier, 24 Air compressor, 25 Filter, 26 Diluter, 27 Muffler, 31 Fuel injection control device, 32 Inverter, 33 Motor, 34 DC / DC converter, 35 Battery.

Claims (3)

In a fuel injection control device for supplying pre-pressurized fuel gas to a fuel cell stack by an injector and controlling the injector,
Energization control means for supplying an inrush current to the electromagnetic coil of the injector to open the valve body of the injector and supplying a holding current to hold the valve open state of the valve body;
Controlling the injector with a preset energization pattern, and operating the injector based on the pressure difference obtained by the pressure sensor upstream of the injector and the pressure sensor downstream of the injector, and the preset injector energization pattern Diagnostic means for diagnosing the condition at least at the start of the vehicle;
With
The energization control means supplies not only the holding current for maintaining the valve open state of the injector but also the inrush current again during the valve opening holding based on the information of the diagnostic means. The fuel injection control device according to claim 1,
The diagnostic means obtains a pressure difference corresponding to the energization pattern of the injector, obtains a resupply time for supplying the inrush current again based on the pressure difference and the pressure difference at the initial stage stored in advance, A fuel injection control device that notifies an energization control means. The fuel injection control device according to claim 1 or 2,
The energization control means supplies an inrush current to the injector at every resupply time obtained by the diagnosis means.

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