JP2013148006A - Fuel injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device that can avoid a stop of fuel supply to an engine.SOLUTION: There is provided a fuel injection control device in which a first pulse signal for driving a liquid fuel injection valve, the first pulse signal being input from the outside, is converted into a second pulse signal for driving a gaseous fuel injection valve. The fuel injection control device includes: a normally-on switch that is interposed between wiring connecting the external input terminal and the external output terminal for the first pulse signal; and a signal processing part for converting the first pulse signal input via the external input terminal during gaseous fuel injection into the second pulse signal, and controlling so that the switch is turned off.

Description

 The present invention relates to a fuel injection control device.

  Conventionally, as a technology for improving the fuel efficiency and environmental protection performance of a vehicle, there is a bi-fuel system that selectively switches between liquid fuel such as gasoline and gaseous fuel such as compressed natural gas (CNG) and supplies it to a single engine. Are known. This bi-fuel system is often constructed by adding a new gas injection system to an existing gasoline injection system in order to reduce development costs.

  In the following Patent Document 1, a gasoline pulse output from an existing electronic control device that controls the gasoline injection amount (a pulse signal having a pulse width corresponding to the gasoline injection amount and used to drive a gasoline injector) Is input to a new electronic control device, and this new electronic control device converts a gasoline pulse into a gas pulse (pulse signal used to drive a gas injector) having a pulse width suitable for gas fuel. Has been.

JP-T 6-502472

  In the above prior art, a new electronic control device (hereinafter referred to as a gas ECU) is a gas injector that converts a gasoline pulse input from an existing electronic control device (hereinafter referred to as a gasoline ECU) into a gas pulse during gas operation. On the other hand, during gasoline operation, the gasoline pulse input from the gasoline ECU is output to the gasoline injector without conversion.

  Conventionally, the gasoline pulse output from the gasoline ECU is taken into the microcomputer in the gas ECU, and the gasoline pulse is converted by the processing by the microcomputer, but if this microcomputer runs out of software or fails in hardware, There is a possibility that neither the gasoline pulse nor the gas pulse can be output, and the fuel supply to the engine is stopped.

 The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a fuel injection control device capable of avoiding the stop of fuel supply to an engine.

 In order to achieve the above object, in the present invention, as a first solution means for a fuel injection control device, a first pulse signal for driving a liquid fuel injection valve, which is input from the outside, is used as a gaseous fuel injection valve. A fuel injection control device for converting the first pulse signal into a second pulse signal, wherein the normally-on switch is inserted on a wiring connecting the external input terminal and the external output terminal of the first pulse signal; And a means for converting the first pulse signal that is branched and input from the previous stage of the switch to the second pulse signal and controls the switch to be turned off when the gaseous fuel is injected. .

 Further, in the present invention, as a second solving means relating to the fuel injection control device, in the first solving means, the signal processing unit includes the first pulse signal that is branched and input from the previous stage of the switch. Further, a means is adopted in which an abnormality diagnosis of the transmission path of the first pulse signal in its own apparatus is performed based on the first pulse signal that is branched and input from the subsequent stage of the switch.

  Further, in the present invention, as a third solving means related to the fuel injection control device, in the second solving means, the signal processing unit is configured to input the first pulse signal that is branched and input from the previous stage of the switch. By comparing the logic and the logic of the first pulse signal that is branched and input from the subsequent stage of the switch, a means for diagnosing abnormality of the transmission path of the first pulse signal is adopted.

  Further, in the present invention, as a fourth solving means relating to the fuel injection control device, in the second solving means, the signal processing unit is branched from a plurality of previous stages of the plurality of switches and inputted. Abnormal diagnosis of the transmission path of the first pulse signal is performed by comparing the input order of the one pulse signal and the input order of the plurality of first pulse signals that are branched from the subsequent stage of the plurality of switches. The means of doing is adopted.

 According to the present invention, by providing a normally-on switch on the wiring connecting the external input terminal and the external output terminal of the first pulse signal, the signal processing unit may run away in software or hardware. Even if a failure occurs, the first pulse signal is always output to the liquid fuel injection valve, so that it is possible to avoid stopping the fuel supply to the engine.

It is a schematic block diagram of the fuel-injection control apparatus (gas ECU1) which concerns on this embodiment. It is a timing chart which shows the time corresponding relation of gasoline pulse signal INJ1, gasoline pulse return signal INJ1_R, and gas pulse signal GINJ1 at the time of gasoline operation. It is a timing chart which shows the time corresponding relationship between the gasoline pulse signal INJ1, the gasoline pulse return signal INJ1_R, and the gas pulse signal GINJ1 during gas operation. The temporal correspondence relationship between the gasoline pulse signals INJ1 to INJ4 and the gasoline pulse return signals INJ1_R to INJ4_R when it is assumed that gasoline injection is performed in the order of the first cylinder → the third cylinder → the fourth cylinder → the second cylinder. It is a timing chart which shows.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a fuel injection control device (gas ECU 1) according to the present embodiment. The gas ECU 1 receives four gasoline pulse signals (first pulse signals) INJ1 to INJ4 for driving the liquid fuel injection valves for four cylinders inputted from the external gasoline ECU 2, and gas fuel injection for four cylinders. This is an electronic control device that converts four gas pulse signals (second pulse signals) GINJ1 to GINJ4 for driving the valve.

 Note that the gasoline ECU 2 is, for example, a pulse of four gasoline pulse signals INJ1 to INJ4 for driving the gasoline injection amount and injection timing of each cylinder, that is, the liquid fuel injection valve for four cylinders based on the operating state of the four cylinder engine. Although it is an existing electronic control device that controls the width and the output timing, the method for controlling the gasoline injection amount and the injection timing of each cylinder is the same as the conventional method, and the description thereof will be omitted.

 As shown in FIG. 1, the gas ECU 1 of the present embodiment receives external input terminals 11 to 14 for inputting four gasoline pulse signals INJ1 to INJ4 from the gasoline ECU 2 and these four gasoline pulse signals INJ1 to INJ4. External output terminals 15 to 18 for outputting to four liquid fuel injection valves (not shown), four relay circuits 19 to 22, and a microcomputer 23 are provided.

 The relay circuit 19 is a normally-on switch inserted on a wiring connecting the external input terminal 11 and the external output terminal 15 of the gasoline pulse signal INJ1 for driving the liquid fuel injection valve of the first cylinder. . The relay circuit 20 is a normally-on switch inserted on the wiring connecting the external input terminal 12 and the external output terminal 16 of the gasoline pulse signal INJ2 for driving the liquid fuel injection valve of the second cylinder. .

 The relay circuit 21 is a normally-on switch inserted on a wiring connecting the external input terminal 13 and the external output terminal 17 of the gasoline pulse signal INJ3 for driving the liquid fuel injection valve of the third cylinder. . The relay circuit 22 is a normally-on switch inserted on a wiring connecting the external input terminal 14 and the external output terminal 18 of the gasoline pulse signal INJ4 for driving the liquid fuel injection valve of the fourth cylinder. .

 The microcomputer 23 (signal processing unit) is a microcomputer in which a CPU (Central Processing Unit) core, a memory, an input / output interface, and the like are integrated, and branches off from the preceding stage of each relay circuit 19 to 22 at the time of gas fuel injection. The gasoline pulse signals INJ1 to INJ4 inputted in this way are converted into gas pulse signals GINJ1 to GINJ4 having a pulse width suitable for the gas fuel and output to four gaseous fuel injection valves (not shown), and each relay circuit 19 to 22 is turned off. In addition, as a conversion method from a gasoline pulse to a gas pulse, a known technique such as Patent Document 1 (Japanese translations of PCT publication No. 6-502472) can be used.

 Although details will be described later, the microcomputer 23 is branched and input from gasoline pulse signals INJ1 to INJ4 that are branched from the previous stage of the relay circuits 19 to 22 and the subsequent stage of the relay circuits 19 to 22. On the basis of the gasoline pulse signals INJ1 to INJ4, which have a function of diagnosing abnormalities in the transmission paths of the gasoline pulse signals INJ1 to INJ4 in the apparatus. Hereinafter, for convenience of explanation, the gasoline pulse signals INJ1 to INJ4 branched from the rear stage of the relay circuits 19 to 22 and input to the microcomputer 23 are referred to as gasoline pulse return signals INJ1_R to INJ4_R.

Next, the operation of the gas ECU 1 configured as described above will be described in detail.
<Operation during gasoline operation>
When the microcomputer 23 of the gas ECU 1 recognizes that gasoline is selected as the current fuel from the state of a fuel changeover switch (not shown), the gasoline pulse signals INJ1 to INJ4 input from the gasoline ECU 2 are directly input to each liquid fuel. The gasoline injection mode is output to the injection valve. That is, the microcomputer 23 does not perform the control of the relay circuits 19 to 22 and the conversion process to the gas pulse during the gasoline injection mode.

  As a result, during the gasoline operation, the relay circuits 19 to 22 are always turned on, and the gasoline pulse signals INJ1 to INJ4 input from the gasoline ECU 2 are directly output to the respective liquid fuel injection valves, and the current engine operation state is obtained. The required amount of gasoline is supplied to each cylinder.

<Operation during gas operation>
On the other hand, when the microcomputer 23 of the gas ECU 1 recognizes that the gas fuel is selected as the current fuel from the state of the fuel changeover switch (not shown), the gasoline pulse signals INJ1 to INJ4 input from the gasoline ECU 2 are used as the gas pulse signal. It becomes gas fuel injection mode which converts into GINJ1-GINJ4 and outputs to each gas fuel injection valve. That is, the microcomputer 23 controls the relay circuits 19 to 22 to be turned off during the gas injection mode, and performs conversion processing to gas pulses.

  As a result, during gas operation, the relay circuits 19 to 22 are always turned off, and gas pulse signals GINJ1 to GINJ4 having pulse widths suitable for gas fuel are output from the gas ECU 1 to the gas fuel injection valves. The amount of gas fuel required for the state will be supplied to each cylinder.

  Even when the microcomputer 23 runs out of software or breaks down in hardware during gasoline operation and gas operation as described above, the relay circuits 19 to 22 are normally on switches. Since the gasoline pulse signals INJ1 to INJ4 are always output from the gas ECU 1 to the liquid fuel injection valve, it is possible to avoid stopping the fuel supply to the engine.

  However, if an abnormality occurs in the transmission path of the gasoline pulse signals INJ1 to INJ4 in the gas ECU 1 (wire breakage or short circuit, failure of the relay circuits 19 to 22), the gasoline pulse signals INJ1 to INJ4 from the gas ECU 1 are normal. May not be output to the liquid fuel injection valve. Therefore, the microcomputer 23 according to the present embodiment performs an abnormality diagnosis on the transmission path of the gasoline pulse signals INJ1 to INJ4 by processing as described below.

<Gasoline pulse transmission path abnormality diagnosis operation>
For example, when paying attention to the transmission path of the gasoline pulse signal INJ1, the microcomputer 23 outputs the logic of the gasoline pulse signal INJ1 that is branched and input from the preceding stage of the relay circuit 19 and the gasoline that is branched and input from the subsequent stage of the relay circuit 19. By comparing the logic of the pulse return signal INJ1_R, an abnormality diagnosis of the transmission path of the gasoline pulse signal INJ1 is performed.

 Specifically, the microcomputer 23 compares the logic of the gasoline pulse signal INJ1 with the logic of the gasoline pulse return signal INJ1_R as an interrupt process when the logic (level) of the gasoline pulse signal INJ1 changes. Then, the microcomputer 23 obtains the logical comparison result obtained when the logic of the gasoline pulse signal INJ1 changes from OFF to ON and the logical comparison result obtained when the logic of the gasoline pulse signal INJ1 changes from ON to OFF. Based on this, it is determined whether or not an abnormality has occurred in the transmission path of the gasoline pulse signal INJ1.

 FIG. 2 is a timing chart showing a temporal correspondence relationship between the gasoline pulse signal INJ1, the gasoline pulse return signal INJ1_R, and the gas pulse signal GINJ1 during gasoline operation. As shown in FIG. 2A, when the transmission path of the gasoline pulse signal INJ1 is normal, the gasoline pulse signal INJ1 and the gasoline pulse return signal INJ1_R have the same logic at all times during gasoline operation. The gas pulse signal GINJ1 becomes OFF logic at all times.

 Therefore, during gasoline operation, the microcomputer 23 indicates that the logical comparison result obtained when the logic of the gasoline pulse signal INJ1 changes from OFF to ON is “match”, and the logic of the gasoline pulse signal INJ1 changes from ON to OFF. When the logical comparison result obtained at the time is also “match”, it is determined that the transmission path of the gasoline pulse signal INJ1 is normal.

 On the other hand, as shown in FIG. 2B, when an abnormality occurs in the transmission path of the gasoline pulse signal INJ1, and the gasoline pulse return signal INJ1_R is fixed to OFF logic at all times, the logic of the gasoline pulse signal INJ1 is The logical comparison result when the change from OFF to ON is “mismatch”, and the logical comparison result when the logic of the gasoline pulse signal INJ1 is changed from “ON” to “OFF” is “match”. It is determined that an abnormality has occurred in the INJ1 transmission path.

 Further, as shown in FIG. 2C, when an abnormality occurs in the transmission path of the gasoline pulse signal INJ1, and the gasoline pulse return signal INJ1_R is fixed to the ON logic at all times, the logic of the gasoline pulse signal INJ1 is The logical comparison result when the change from OFF to ON is “match” and the logical comparison result when the logic of the gasoline pulse signal INJ1 changes from “ON” to “OFF” is “mismatch”. It is determined that an abnormality has occurred in the INJ1 transmission path.

 FIG. 3 is a timing chart showing temporal correspondence relationships between the gasoline pulse signal INJ1, the gasoline pulse return signal INJ1_R, and the gas pulse signal GINJ1 during gas operation. As shown in FIG. 3A, when the transmission path of the gasoline pulse signal INJ1 is normal, the gasoline pulse return signal INJ1_R becomes OFF logic at all times during gas operation, and the pulse is delayed slightly from the gasoline pulse signal INJ1. A gas pulse signal GINJ1 having a corrected width is generated.

 Therefore, during gas operation, the microcomputer 23 indicates that the logic comparison result obtained when the logic of the gasoline pulse signal INJ1 changes from OFF to ON is “mismatch”, and the logic of the gasoline pulse signal INJ1 changes from ON to OFF. When the logical comparison result obtained at this time is “match”, it is determined that the transmission path of the gasoline pulse signal INJ1 is normal.

On the other hand, as shown in FIG. 3B, when an abnormality occurs in the transmission path of the gasoline pulse signal INJ1, and the logic of the gasoline pulse return signal INJ1_R becomes the same as the gasoline pulse signal INJ1, the logic of the gasoline pulse signal INJ1 Since the logical comparison result when the value of the gasoline pulse signal INJ1 changes from OFF to ON and the logical comparison result when the logic of the gasoline pulse signal INJ1 changes from ON to OFF also matches, the microcomputer 23 It is determined that an abnormality has occurred in the transmission path of the signal INJ1.
The microcomputer 23 performs the abnormality diagnosis process during the gasoline operation and the gas operation as described above for each of the transmission paths of the gasoline pulse signals INJ1 to INJ4.

 As described above, according to the present embodiment, the fuel supply to the engine is stopped during the gasoline operation and the gas operation even if the microcomputer 23 runs out of software or malfunctions. Can be avoided, and abnormalities in the transmission paths of the gasoline pulse signals INJ1 to INJ4 including the relay circuits 19 to 22 can also be diagnosed.

In addition, this invention is not limited to the said embodiment, The following modifications are also mentioned.
(1) In the above embodiment, the microcomputer 23 branches and inputs the logic of the gasoline pulse signals INJ1 to INJ4 that are branched and input from the preceding stage of the relay circuits 19 to 22 and the subsequent stage of each of the relay circuits 19 to 22. The case where the abnormality diagnosis of the transmission path | route of each gasoline pulse signal INJ1-INJ4 is performed by comparing with the logic of the gasoline pulse return signals INJ1_R-INJ4_R which were performed was illustrated.

 On the other hand, the microcomputer 23 branches from the preceding stage of the relay circuits 19 to 22 and inputs the gasoline pulse signals INJ1 to INJ4 and inputs from the subsequent stage of the relay circuits 19 to 22. By comparing the input order of the gasoline pulse signals INJ1 to INJ4, an abnormality diagnosis of the transmission path of the gasoline pulse signals INJ1 to INJ4 may be performed.

 FIG. 4 shows the time between gasoline pulse signals INJ1 to INJ4 and gasoline pulse return signals INJ1_R to INJ4_R when it is assumed that gasoline injection is performed in the order of the first cylinder → the third cylinder → the fourth cylinder → the second cylinder. It is a timing chart which shows a typical correspondence. As shown in FIG. 4, when the transmission paths of the gasoline pulse signals INJ1 to INJ4 are normal, the input order of the gasoline pulse signals INJ1 to INJ4 matches the input order of the gasoline pulse return signals INJ1_R to INJ4_R.

 Therefore, during gasoline operation, the microcomputer 23 determines that the transmission path of each of the gasoline pulse signals INJ1 to INJ4 is the same when the input order of the gasoline pulse signals INJ1 to INJ4 matches the input order of the gasoline pulse return signals INJ1_R to INJ4_R. Judged as normal, and judged to be abnormal when they did not match. Note that even when the transmission path is normal during gas operation, the gasoline pulse return signals INJ1_R to INJ4_R are all OFF logic, so this abnormality diagnosis method cannot be used.

(2) In the above-described embodiment, the case where the relay circuits 19 to 22 that electromagnetically open and close are used as the normally-on switch is illustrated, but the present invention is not limited to this, and if it is a normally-on switch, Other switching elements such as a semiconductor switch may be used.

  DESCRIPTION OF SYMBOLS 1 ... Gas ECU (fuel injection control apparatus), 2 ... Gasoline ECU, 11-14 ... External input terminal, 15-18 ... External output terminal, 19-22 ... Relay circuit (switch), 23 ... Microcomputer (signal processing part)

Claims (4)

A fuel injection control device for converting a first pulse signal for driving a liquid fuel injection valve, which is input from the outside, into a second pulse signal for driving a gaseous fuel injection valve,
A normally-on switch inserted on a wiring connecting the external input terminal and the external output terminal of the first pulse signal;
A signal processing unit that converts the first pulse signal that is branched and input from the preceding stage of the switch to the second pulse signal and controls the switch to be turned off at the time of gaseous fuel injection;
A fuel injection control device comprising:   The signal processing unit, based on the first pulse signal that is branched and input from the previous stage of the switch and the first pulse signal that is branched and input from the rear stage of the switch, The fuel injection control device according to claim 1, wherein abnormality diagnosis of the transmission path of the first pulse signal is performed.   The signal processing unit compares the logic of the first pulse signal that is branched and input from the previous stage of the switch with the logic of the first pulse signal that is branched and input from the subsequent stage of the switch. The fuel injection control device according to claim 2, wherein an abnormality diagnosis of a transmission path of the first pulse signal is performed.   The signal processing unit is configured to input a plurality of first pulse signals that are branched and input from a front stage of the plurality of switches, and a plurality of the first pulses that are branched and input from a rear stage of the plurality of switches. The fuel injection control device according to claim 2, wherein an abnormality diagnosis of a transmission path of the first pulse signal is performed by comparing the input order of signals.

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