JP2008190345A - Injector control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure controllability of an injector by minimizing a valve closure delay in the injector, even when a fuel injection signal becomes OFF in the middle of transfer of an injector driving current from a valve opening current to a holding current, in injector control in a fuel injection system. <P>SOLUTION: This injector control device 1A is arranged in the fuel injection system of an internal combustion engine, and is connected to the injector 2, for controlling the injector 2 for opening and closing in the predetermined timing, while adjusting output of the injector driving current by switching ON/OFF of an injection time control signal by a control means. Time required up to transfer from the valve opening current Ip to the holding current Ih is shortened by promoting fall of the injector driving current, by enabling the control means to perform control for stopping (Tip-off) the injection time control signal for a predetermined time just after finishing the valve opening current Ip. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an injector control device for controlling the fuel injection amount by opening and closing an injector in a fuel injection system of an internal combustion engine.

  In a fuel injection system for an internal combustion engine, there is a system in which an injector control device controls the amount of current flowing through the injector to control opening and closing of the injector. As shown in the waveform diagram of FIG. 4, such a method for controlling the current flowing through the injector is such that the valve opening current (Tip) and the holding current (Tih) have appropriate values based on the fuel injection signal. The injector is driven by controlling the energization time (Ti = Tip + Tih) to the injector.

  By the way, in the case of such a control method, when the injector is switched from ON to OFF, the timing for completely closing the injector 10 is usually slightly delayed from the voltage / current waveform of the actually output signal. It is. In addition to this, when the injector drive current shifts from the valve opening current (Ip) to the holding current (Ih) as shown in FIG. 4, it does not change instantaneously but gradually changes. ing.

  Therefore, as shown in the waveform diagram of FIG. 5, when the fuel injection signal is turned off for the purpose of closing the injector while the injector drive current is shifting from the valve opening current (Ip) to the holding current (Ih), Since the current at that time is larger than the normal holding current (Ih) by α, an extra time is required for the delay time (Td), and this causes the response of the injector to the operation to be further delayed. The fuel injection control is difficult to realize.

In response to such a problem of injector response delay, JP-A-8-4575 discloses a fuel temperature corresponding to the temperature of the electromagnetic coil and delays the operation of the fuel injection valve based on the fuel temperature and the battery voltage. There has been proposed a control method in which a correction pulse width for correcting time is set, and a value obtained by adding the correction pulse width to the effective injection pulse width is set as the injection pulse width. However, this control method can only cope with a delay corresponding to the fluctuation of the DC resistance of the electromagnetic coil due to a temperature change or the like. The expansion of the injector response delay due to time (Td) cannot be accommodated.
JP-A-8-4575

  The present invention is intended to solve the above-described problems, and relates to injector control in a fuel injection system, and the fuel injection signal is turned off while the injector drive current is shifting from the valve opening current to the holding current. Even in such a case, it is an object to minimize the valve closing delay of the injector so as to ensure the controllability of the injector.

  Accordingly, the present invention provides a fuel injection system in an internal combustion engine for controlling opening and closing of an injector at a predetermined timing while switching an ON / OFF signal as an injection time control signal by a predetermined control means to adjust an output of an injector driving current. In the injector control device arranged in the above, the control means promotes the fall of the injector drive current by performing control to temporarily turn off the injection time control signal for a predetermined time immediately after the valve opening current ends. Thus, the time required to shift from the valve opening current to the holding current is reduced.

  In this way, the injection time control signal is turned OFF for a predetermined time immediately after the valve opening current is finished, thereby causing the injector to generate an off-surge to sharpen the falling angle of the injector drive signal and shift to the holding current in a shorter time. Therefore, in the past, when the injection time control signal was turned off during the transition to the holding current, an extra time was required until the injector drive current stopped, whereas the injection time control signal was changed from OFF to the injector. The delay time until the drive current is stopped can be minimized.

  In addition, this injector control device is disposed in a gas fuel injection system. If the injector is for gas fuel injection, the injector to be controlled has a larger injection amount than the liquid fuel, and the stroke width is also large. Since it is large, it becomes more useful.

  According to the present invention in which the injection time control signal is turned OFF for a predetermined time immediately after the valve opening current ends to shorten the time until the shift to the holding current, the injector drive current shifts from the valve opening current to the holding current. Even when the injection time control signal is turned off halfway, the valve closing delay of the injector can be minimized, and good controllability of the injector can be ensured.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the present embodiment, the case where the injector control device 1A is disposed in a gas fuel injection system will be described.

    FIG. 1 shows a functional block diagram of an injector control device 1A of the present embodiment. The injector control device 1A includes an electronic control unit including an injection time control unit 101, a current control unit 102, and the like, and controls an injector current of the injector 2 created for gas fuel by an energization time to the injector. The control system is configured.

  The electronic control unit constituting the injector control device 1A may be one in which an electronic control unit having various functions such as other engine control functions also as an injector control device that executes a control method described in detail below. Good. Moreover, even if the injection time control means 101, the current control means 102, etc. combine the microcomputer etc. in an electronic control unit and other electronic components, a microcomputer implement | achieves these functionally by a predetermined program. However, the injector control device 1A as a whole can be used as long as it realizes the functions described below.

  As shown in FIG. 4, in the conventional injector control device, when the valve opening control time (Tip) is shifted to the holding control time (Tih), the injector driving current is changed from the valve opening current (Ip) to the holding current (Ih). It took a relatively long time for the trailing edge to reach the level of the holding current (Tih) by drawing a curve at a gentle angle.

  Therefore, as shown in FIG. 5, when the valve is to be closed when the injection time is short, the drive current flowing through the injector 2 when the fuel injection signal is OFF is larger than the set holding current (Ih) by α. For this reason, the time until the valve is closed is longer than usual, and the delay time (Td) is increased to deteriorate the controllability of the injector 2.

  Therefore, in the injector control device 1A of the present invention, the injection time control signal is stopped for a predetermined period (Tip-off) immediately after the end of the valve opening control (Tip), and an off-surge is generated in the injector 2. It is characterized by a point. Due to this off-surge, the injector drive current rapidly decreases and shifts to the holding current (Ih) set in a short time compared to the conventional case. The stop-time is appropriately set according to the usage state of the injector 2.

  Next, the operation of the injector control device 1A according to the present embodiment will be described in detail with reference to the waveform diagrams shown in the time charts in FIGS.

  In the control by the injector control device 1A according to the present embodiment, as shown in the waveform diagram of the fuel injection signal in FIG. 2, the fuel injection signal is turned on, and the injector drive current shown in the lower stage reaches a peak and the valve opening current (Ip ), The injection time control signal is temporarily stopped (Tip-off) at the timing of switching from the valve opening control time (Tip) to the holding control time (Tih).

  As a result, an off-surge occurs in the injector 2, and the waveform of the injector drive current suddenly falls to the level of the holding current (Ih) in a very short time compared to the gentle waveform according to the conventional example shown by the wavy line. In this case, since the OFF of the fuel injection signal is after the transition to the holding current (Ih) and the magnitude of the injector drive current at the OFF time is the same as the conventional example of FIG. The delay time (Td) is the same, and there is no significant difference in the delay of the valve closing time of the injector 2.

  However, as shown in FIG. 3, in the case of a short valve opening in which the fuel injection signal is turned off during the transition from the valve opening current (Ip) to the holding current (Ih) in the conventional example shown by the broken line, FIG. In contrast to the conventional example of FIG. 1, the time required for the injector drive current to stop is increased and the delay time (Td) is increased. On the other hand, the injector is temporarily stopped (Tip-off) of the injection time control signal. 2, the holding current (Ih) is reached in a shorter time compared to the conventional example of FIG. 5, or reaches a level close to this, and the expansion of the valve closing delay time of the injector 2 is zero or minimized. It will be limited.

  Therefore, even when the injector 2 is closed while the injector drive current is shifting from the valve opening current to the holding current, the controllability of the injector 2 is compared with the conventional example according to the present embodiment. Is easily maintained well. In addition, shortening the output time of the injector drive current prevents unnecessary current from flowing through the injector 2, so that there is an effect of suppressing excessive heat generation of the injector 2, and an improvement effect of its durability can be expected. It becomes.

  As described above, regarding the injector control in the fuel injection system, the present invention enables the injector to be closed even when the fuel injection signal is turned off and the injector is closed during the transition from the valve opening current to the holding current. It was possible to minimize the valve closing delay. This also ensures good controllability of the injector.

The functional block diagram of the injector control apparatus of embodiment in this invention. The wave form diagram for demonstrating the effect | action of the injector control apparatus of FIG. The wave form diagram for demonstrating an effect | action when the valve opening time of the injector control apparatus of FIG. 1 is short. The wave form diagram for demonstrating an effect | action of the injector control apparatus of a prior art example. The wave form diagram for demonstrating an effect | action when the valve opening time of the injector control apparatus of a prior art example is short.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A Injector control apparatus, 2 injectors, 101 Injection time control means, 102 Current control means

Claims (2)

  An injector disposed in a fuel injection system in an internal combustion engine for controlling opening and closing of the injector at a predetermined timing while switching an ON / OFF signal as an injection time control signal by a predetermined control means and adjusting an output of the injector drive current In the control device, the control means performs control to temporarily turn off the injection time control signal for a predetermined time immediately after completion of the valve opening current, thereby facilitating the fall of the injector driving current. An injector control device characterized by shortening the time required to shift from a valve current to a holding current. 2. The injector control device according to claim 1, wherein the injector control device is disposed in a gas fuel injection system and the injector is for gas fuel injection.

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