JP2016217330A - Fuel injection controller of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress excessive fuel in gas fuel operation.SOLUTION: An electronic controller 40 includes a second ECU 42 configured to convert a gasoline injection signal G to a CNG (compressed natural gas) injection signal C in CNG operation and output it. A sub signal Gs having a pulse width shorter than that of the main signal Gm is added to the gasoline injection signal G at the time of acceleration operation. The second ECU 42 ignores the sub signal Gs in deriving the CNG injection signal C, at the time of acceleration operation in the CNG operation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel injection control device for an internal combustion engine capable of switching between a liquid fuel operation in which liquid fuel is injected into an intake passage and a gas fuel operation in which gaseous fuel is injected into an intake passage.

  Conventionally, there is a bi-fuel engine capable of switching between a liquid fuel operation in which liquid fuel such as gasoline is injected into an intake port and a gas fuel operation in which gaseous fuel such as CNG (compressed natural gas) is injected into an intake port. . This bi-fuel engine fuel injection system is configured by adding a new CNG fuel injection system to an existing gasoline engine fuel injection system for the purpose of reducing development costs. .

  For example, in Patent Document 1, a drive signal output from an existing electronic control device that controls driving of a gasoline injection valve is input to a new electronic control device, and the drive signal is input to the CNG injection valve by the new electronic control device. A technique for converting the drive signal into a drive signal is disclosed.

JP 2013-148006 A

  By the way, at the time of acceleration operation at the time of gasoline operation, the injection amount of gasoline is increased as the intake air amount increases. At this time, a part of the injected gasoline adheres to the wall surface of the intake port and is not supplied into the combustion chamber, so that there is a shortage of gasoline used for combustion. Therefore, conventionally, the amount of gasoline adhering to the wall surface is taken into account, so that much gasoline is injected accordingly. However, since CNG is a gas, it does not adhere to the wall surface of the intake port. Therefore, if the gasoline injection valve drive signal is converted into the CNG injection valve drive signal during acceleration operation during CNG operation, the amount of CNG is increased in the same manner as during gasoline operation, resulting in excessive CNG. This may cause a problem that the combustion state deteriorates.

  An object of the present invention is to provide a fuel injection control device for an internal combustion engine that can suppress excessive fuel consumption during gas fuel operation.

  In order to achieve the above object, a fuel injection control device for an internal combustion engine injects and supplies liquid fuel into an intake passage by means of a liquid fuel operation and a gas fuel injection valve. The control unit is applied to an internal combustion engine capable of switching between gas fuel operation and includes a control unit that converts a drive signal of the liquid fuel injection valve into a drive signal of the gas fuel injection valve and outputs the gas fuel operation signal. The control unit is configured such that the ratio of the time width of the drive signal of the gas fuel injection valve to the time width of the drive signal of the liquid fuel injection valve is smaller during acceleration operation during gas fuel operation than during non-acceleration operation. And a drive signal for the gaseous fuel injection valve is derived.

  In the acceleration operation, the liquid fuel injected from the liquid fuel injection valve is taken into account that the amount of liquid fuel adhering to the wall surface of the intake passage is not used for combustion. The time width of the drive signal for the injection valve is set longer.

  Further, according to the above configuration, the ratio of the time width of the drive signal of the gas fuel injection valve to the time width of the drive signal of the liquid fuel injection valve is smaller during acceleration operation during gas fuel operation than during non-acceleration operation. Thus, the drive signal of the gaseous fuel injection valve is derived by the control unit. The gaseous fuel injection valve is driven by this drive signal. For this reason, in the gas fuel operation in which the injected gaseous fuel does not adhere to the wall surface of the intake passage, the fuel injection amount is not increased as in the acceleration operation in the liquid fuel operation, and the gas fuel is excessive. It can be suppressed.

  In the fuel injection control device for an internal combustion engine, a sub signal having a pulse width shorter than that of the main signal is added to the drive signal of the liquid fuel injection valve during acceleration operation in addition to the main signal. It is preferable that the sub-signal is ignored when deriving the drive signal for the gaseous fuel injection valve during acceleration operation.

  In the acceleration operation, the liquid fuel injected from the liquid fuel injection valve is taken into account that the amount of liquid fuel adhering to the wall surface of the intake passage is not used for combustion. In addition to the main signal, a sub signal is added to the injection valve drive signal.

  Moreover, according to the said structure, a sub signal is disregarded when the drive signal of a gaseous fuel injection valve is derived | led-out by a control part at the time of the acceleration operation at the time of gaseous fuel operation. That is, the main signal among the drive signals for the liquid fuel injection valve is converted into the drive signal for the gaseous fuel injection valve, and the sub signal is not converted into the drive signal for the gaseous fuel injection valve. Thereby, in the acceleration operation during the gas fuel operation, compared with the non-acceleration operation, the time of the drive signal of the liquid fuel injection valve (the sum of the pulse width of the main signal and the pulse width of the sub signal) of the gas fuel injection valve The ratio of the time width of the drive signal is reduced. For this reason, it is possible to prevent the gaseous fuel from becoming excessive in the gaseous fuel operation in which the injected gaseous fuel does not adhere to the wall surface of the intake passage.

  In the fuel injection control device for an internal combustion engine, the control unit determines a pulse width of the drive signal of the liquid fuel injection valve when deriving the drive signal of the gas fuel injection valve during acceleration operation during gas fuel operation. A configuration in which it is determined that the drive signal is the sub-signal when the time is shorter than the predetermined time is preferable.

  Of the drive signals of the liquid fuel injection valve, the sub signal has a pulse width shorter than that of the main signal because the sub signal is for increasing the injection amount of the liquid fuel in consideration of the amount of wall surface adhesion of the liquid fuel. Therefore, in the above configuration, if the predetermined time is set to a time longer than the upper limit of the range that the sub signal can take, it is possible to accurately determine whether or not the drive signal of the liquid fuel injection valve is the sub signal. Can do.

  In the fuel injection control device for an internal combustion engine, the second control unit may be out of a predetermined period during which the main signal can be detected when deriving a drive signal for the gaseous fuel injection valve during acceleration operation during gaseous fuel operation. In this case, it is preferable that when the driving signal of the liquid fuel injection valve is detected, it is determined that the driving signal is the sub signal.

  Of the drive signal of the liquid fuel injection valve, the main signal is detected within a predetermined period, and the sub signal is detected outside the predetermined period. For this reason, when the drive signal of the liquid fuel injection valve is detected outside the predetermined period during which the main signal can be detected when the drive signal of the gaseous fuel injection valve is derived, the drive signal is a sub signal. It can be accurately determined.

  According to this configuration, it is possible to accurately determine whether or not the drive signal is a sub signal.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that it becomes fuel excess at the time of gaseous fuel driving | operation.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows typically the whole structure about one Embodiment of the fuel-injection control apparatus of an internal combustion engine. (A), (b) is a timing chart which shows together transition of a gasoline injection signal and a CNG injection signal. The flowchart which shows the execution procedure of the derivation | leading-out process of the gasoline injection signal in the same embodiment. The flowchart which shows the execution procedure of the drive control process of the gasoline injection valve of the embodiment. The flowchart which shows the execution procedure of the drive control process of the CNG injection valve of the embodiment. (A) is a timing chart which shows transition of the gasoline injection signal at the time of steady operation, (b) is a timing chart which shows transition of the CNG injection signal at the time of steady operation. (A) is a timing chart which shows transition of the gasoline injection signal at the time of acceleration operation, (b) is a timing chart which shows transition of the gasoline injection signal at the time of acceleration operation. (A), (b) is a timing chart which shows the transition of the gasoline injection signal and CNG injection signal in a modification.

Hereinafter, an embodiment will be described with reference to FIGS.
The internal combustion engine of this embodiment injects and supplies gasoline operation (liquid fuel operation) in which gasoline as liquid fuel is injected into the intake port 14 and CNG (compressed natural gas) as gaseous fuel into the intake port 14. This is a so-called bi-fuel engine for vehicle use capable of switching between CNG operation (gaseous fuel operation). This bi-fuel engine is designed on the basis of an in-line four-cylinder gasoline engine, and is configured by adding a CNG supply system to the gasoline engine that is the base.

  As shown in FIG. 1, a throttle valve 11 is installed in the intake passage 10 of the bi-fuel engine. The throttle valve 11 is driven to open and close by a throttle motor 12, and changes the flow passage area of intake air. The intake passage 10 is branched for each cylinder in an intake manifold 13 provided on the downstream side of the throttle valve 11, and then connected to the combustion chamber 15 of each cylinder via an intake port 14. Note that a spark plug 16 for spark ignition of the air-fuel mixture introduced into the combustion chamber 15 of each cylinder is installed.

  A gasoline injection valve 17 for injecting gasoline is installed in the intake port 14 of each cylinder. Gasoline pumped out by a fuel pump 19 from a gasoline tank 18 that stores gasoline is supplied to each gasoline injection valve 17.

  Further, a vehicle equipped with this bi-fuel engine is provided with a CNG cylinder 20 in which CNG is stored in a high pressure state. The CNG cylinder 20 is provided with a manual valve 21 for manually shutting out the outflow of CNG, and a high-pressure CNG pipe 22 is connected via the manual valve 21. The CNG cylinder 20 is connected to a CNG regulator 23 for reducing the CNG sent from the CNG cylinder 20 to a necessary pressure through the high-pressure CNG pipe 22. The CNG regulator 23 incorporates an oil separator (not shown) that separates oil in the CNG.

  The high-pressure CNG pipe 22 is provided with two shut-off valves 24 and 25 in order from the upstream side for shutting off the flow of CNG. These shutoff valves 24 and 25 are opened at the start of the CNG operation, and are closed at the end of the CNG operation. In addition, a high-pressure fuel pressure sensor 26 for detecting the pressure of CNG flowing through the high-pressure CNG pipe 22 is installed between the two shutoff valves 24 and 25.

  On the other hand, a low-pressure CNG pipe 27 is connected to the discharge port of the CNG regulator 23. The CNG regulator 23 is connected to a CNG delivery pipe 28 that stores low-pressure CNG decompressed by the CNG regulator 23 via the low-pressure CNG pipe 27. The CNG delivery pipe 28 is provided with a low-pressure side fuel pressure sensor 29 that detects the pressure of the CNG inside the CNG delivery pipe 28 and a low-pressure side fuel temperature sensor 30 that detects the temperature of the CNG inside the CNG delivery pipe 28. In addition, CNG injection valves 31 corresponding to the number of cylinders of the bi-fuel engine are attached to the CNG delivery pipe 28. Each CNG injection valve 31 is connected to a CNG nozzle 33 of each cylinder installed in the intake manifold 13 via a CNG hose 32 provided for each CNG injection valve 31.

Such control of the bi-fuel engine is performed by the electronic control unit 40. The electronic control device 40 includes a first ECU 41 and a second ECU 42.
Each of the first ECU 41 and the second ECU 42 includes a central processing unit (CPU) that executes various arithmetic processes for engine control, an engine control program, and an arithmetic map. Further, the first ECU 41 and the second ECU 42 are a read only memory (ROM) in which various data are stored, a random access memory (RAM) for temporarily storing the calculation results of the CPU, and input / output of signals to / from the outside. An input / output port (I / O) is provided.

  Various sensors for detecting the engine operating state and the vehicle traveling state are connected to the input port of the first ECU 41. Such sensors include a vehicle speed sensor 43 that detects the vehicle speed, an accelerator pedal sensor 44 that detects the amount of depression of the accelerator pedal, an air flow meter 45 that detects the amount of intake air, a crank angle sensor 46 that detects the crank angle, and an engine coolant temperature. There are a water temperature sensor 47 for detecting the throttle valve, a throttle sensor 48 for detecting the opening of the throttle valve 11, and the like.

Further, the gasoline injection valve 17, the spark plug 16, the throttle motor 12 and the like are connected to the output port of the first ECU 41.
A sensor that is input to the input port of the first ECU 41 is connected to the input port of the second ECU 42. That is, signal lines of various sensors of the gasoline system are branched and connected to the second ECU 42.

  Further, the above-described high pressure side fuel pressure sensor 26, low pressure side fuel pressure sensor 29, and low pressure side fuel temperature sensor 30 are connected to the second ECU 42. Further, the second ECU 42 is connected with a CNG changeover switch 49 for the user to manually switch between the gasoline operation and the CNG operation of the bi-fuel engine.

Further, the shutoff valves 24 and 25, the CNG injection valve 31 and the like are connected to the output port of the second ECU 42.
The first ECU 41 controls the throttle valve 11 according to the depression amount of the accelerator pedal. The first ECU 41 derives a driving signal for the gasoline injection valve 17 (hereinafter referred to as a gasoline injection signal G) based on the engine speed and the intake air amount.

  During the gasoline operation, the second ECU 42 drives the gasoline injection valve 17 by outputting the gasoline injection signal G input from the first ECU 41 to the gasoline injection valve 17 as it is.

  Further, during the CNG operation, the second ECU 42 derives a drive signal for the CNG injection valve 31 (hereinafter, CNG injection signal C) based on the gasoline injection signal G. That is, the gasoline injection signal G is converted into a CNG injection signal C. The CNG injection valve 31 is driven by outputting the CNG injection signal C to the CNG injection valve 31.

  Here, as shown in FIGS. 2 (a) and 2 (b), the second ECU 42 sets the CNG injection signal C unless it is after grasping both the start timing t1 and the end timing t3 of the gasoline injection signal G. Can not do it. Therefore, the second ECU 42 sets the start timing t2 of the CNG injection signal C so that the end timing t4 of the CNG injection signal C is later than the end timing t3 of the gasoline injection signal G. Therefore, the start timing t2 and the end timing t4 of the CNG injection signal C are delayed from the start timing t1 and the end timing t3 of the gasoline injection signal G, respectively.

  By the way, as described above, during the acceleration operation during the gasoline operation, the injection amount of the gasoline is increased as the intake air amount increases. At this time, a portion of the injected gasoline adheres to the wall surface of the intake port 14 and is not supplied into the combustion chamber 15, so that there is a shortage of gasoline used for combustion.

  Therefore, in the present embodiment, in consideration of the amount of wall surface adhesion of gasoline, the corresponding amount of gasoline is supplied by sub-injection different from main injection. That is, a sub signal Gs having a pulse width shorter than that of the main signal Gm is added to the gasoline injection signal G during acceleration operation in addition to the main signal Gm.

  In addition, the second ECU 42 ignores the sub signal Gs when deriving the drive signal of the CNG injection valve 31 during acceleration operation during CNG operation. Accordingly, the time width of the CNG injection signal C with respect to the time width of the gasoline injection signal G (the sum of the pulse width of the main signal Gm and the pulse width of the sub signal Gs) during acceleration operation during CNG operation compared to during non-acceleration operation. The ratio is made smaller.

  Next, the execution procedure of the derivation process of the gasoline injection signal G will be described with reference to FIG. Note that this series of processing is repeatedly executed by the first ECU 41 for each predetermined crank angle regardless of whether the operation is a gasoline operation or a CNG operation.

  As shown in FIG. 3, in this series of processes, first, the first ECU 41 reads signals from various sensors of the gasoline system such as the crank angle sensor 46 and the air flow meter 45 (step S11). Subsequently, the gasoline injection signal G is derived by referring to a map that preliminarily defines the relationship between the read signal and the gasoline injection signal G (step S12), and this series of processes is temporarily terminated.

  Next, the execution procedure of the drive control process for the gasoline injection valve 17 will be described with reference to FIG. Note that this series of processing is repeatedly executed at predetermined crank angles by the second ECU 42 during gasoline operation.

  As shown in FIG. 4, in this series of processes, first, the second ECU 42 reads the gasoline injection signal G derived by the first ECU 41 (step S21). Subsequently, a gasoline injection signal G is output to the gasoline injection valve 17 (step S22). Then, this series of processes is temporarily terminated. Thus, the gasoline injection valve 17 is opened in response to the gasoline injection signal G, and gasoline is injected and supplied into the intake port 14.

  As shown in FIG. 6A, during the steady operation, the gasoline injection signal G (main signal Gm) is output in the exhaust stroke of each cylinder # 1 to # 4. In the present embodiment, the gasoline injection signal G is output in the order of the first cylinder # 1, the third cylinder # 3, the fourth cylinder # 4, and the second cylinder # 2.

  Further, as shown in FIG. 7A, during the acceleration operation, the main signal Gm of the gasoline injection signal G is output in the exhaust stroke of each of the cylinders # 1 to # 4, and the subsequent intake stroke to the intake stroke. The sub-signal Gs is output through. In the present embodiment, two sub signals Gs are output.

  Next, the execution procedure of the drive control process for the CNG injection valve 31 will be described with reference to FIG. This series of processing is repeatedly executed by the second ECU 42 at every predetermined crank angle during CNG operation.

  As shown in FIG. 5, in this series of processes, first, the second ECU 42 reads signals from various sensors of the gasoline system (step S31). Subsequently, signals of various sensors of the CNG system are read (step S32). Subsequently, the gasoline injection signal G derived by the first ECU 41 is read (step S33). Subsequently, it is determined whether or not acceleration operation is being performed (step S34). Here, it is determined that the acceleration operation is being performed when the opening degree of the throttle valve 11 changes to the open side.

  If it is determined in step S34 that the acceleration operation is not being performed (step S34: “NO”), then the gasoline injection signal G is converted into a CNG injection signal C (step S37), and the CNG injection valve The CNG injection signal C is output to 31 (step S38). Then, this series of processes is temporarily terminated. Thereby, the CNG injection valve 31 is opened in response to the CNG injection signal C, and CNG is injected and supplied into the intake port 14.

  On the other hand, if it is determined in step S34 that the acceleration operation is being performed (step S34: “YES”), then, whether or not the pulse width of the gasoline injection signal G is equal to or longer than the predetermined time Δt1. Is determined (step S35). The predetermined time Δt1 is set to a time longer than the upper limit value of the range that the sub signal Gs can take.

  If it is determined in step S35 that the pulse width of the gasoline injection signal G is equal to or greater than the predetermined time Δt1 (step S35: “YES”), it is determined that the gasoline injection signal G is the main signal Gm. (Step S36). And step S37 and step S38 are performed in order and this series of processes are once complete | finished.

  On the other hand, in the determination process of step S35, when it is determined that the pulse width of the gasoline injection signal G is not equal to or greater than the predetermined time Δt1 (step S35: “NO”), it is determined that the gasoline injection signal G is the sub signal Gs. (Step S39), and this series of processes is temporarily terminated. That is, in this case, the gasoline injection signal G is ignored.

  As shown in FIGS. 6A and 6B, for example, during steady operation, the CNG injection signal C is delayed from the gasoline injection signal G (main signal Gm) in the exhaust stroke of each cylinder # 1 to # 4. Is output.

  As shown in FIGS. 7A and 7B, during the acceleration operation, the CNG injection signal C is output later than the main signal Gm of the gasoline injection signal G in the exhaust stroke. However, at this time, the CNG injection signal C corresponding to the sub signal Gs output from the exhaust stroke to the intake stroke of each cylinder # 1 to # 4 is not output.

Next, the operation of this embodiment will be described.
During acceleration operation during CNG operation, the sub-signal Gs is ignored when the second ECU 42 derives the CNG injection signal C. That is, the main signal Gm of the gasoline injection signal G is converted into the CNG injection signal C, and the sub signal Gs is not converted into the CNG injection signal C. For this reason, excessive CNG can be suppressed in the CNG operation in which the injected CNG does not adhere to the wall surface of the intake port 14.

According to the fuel injection control device for an internal combustion engine according to the present embodiment described above, the following effects can be obtained.
(1) The second ECU 42 ignores the sub-signal Gs of the gasoline injection signal G when deriving the CNG injection signal C during acceleration operation during CNG operation.

According to such a configuration, excessive CNG can be suppressed in the CNG operation in which the injected CNG does not adhere to the wall surface of the intake port 14.
(2) During acceleration operation during CNG operation, the second ECU 42 derives the CNG injection signal C. If the pulse width of the gasoline injection signal G is shorter than a predetermined time Δt1, the second ECU 42 It is determined that the signal is Gs, and the gasoline injection signal G is ignored.

  Since the sub signal Gs is for increasing the injection amount of gasoline in consideration of the amount of gasoline wall adhesion, the sub signal Gs has a shorter pulse width than the main signal Gm. For this reason, if the predetermined time Δt1 is set to a time longer than the upper limit of the range that the sub signal Gs can take as in the present embodiment, it is accurately determined whether or not the gasoline injection signal G is the sub signal Gs. can do.

<Modification>
In addition, the said embodiment can also be changed as follows, for example.
If the engine operating state in which the sub signal Gs is output is limited to the acceleration operation, the determination process in step S34 illustrated in FIG. 5 can be omitted.

  The sub signal Gs is not limited to being output after the main signal Gm, and may be output before the main signal Gm. Further, it may be output before and after the main signal Gm.

  When the gasoline injection signal G is detected outside the predetermined crank angle range where the main signal Gm can be detected, that is, outside the predetermined period, the second ECU 42 can determine that the gasoline injection signal G is the sub signal Gs. Even in this case, it is possible to accurately determine whether or not the gasoline injection signal G is the sub signal Gs.

  The gasoline injection signal G is not limited to one that is divided into the main signal Gm and the sub signal Gs. For example, as shown in FIG. 8A, the pulse width g2 of the gasoline injection signal G during acceleration operation is changed to the pulse width g1 during steady operation so that the amount of gasoline corresponding to the amount of gasoline adhering to the wall surface is increased. Can be larger. In this case, as shown in FIGS. 8 (a) and 8 (b), the ratio c2 / g2 of the CNG injection signal C to the pulse width g2 of the gasoline injection signal G during acceleration operation is equal to that during non-acceleration operation such as during steady operation. What is necessary is just to derive | lead-out the CNG injection signal C at the time of acceleration operation so that it may become smaller than the said ratio c1 / g1. Even in this case, in the CNG operation, the fuel injection amount is not increased as in the acceleration operation during the gasoline operation, and it is possible to suppress the excessive CNG. Therefore, it is possible to suppress excessive fuel during CNG operation.

  -The internal combustion engine of the said embodiment is applicable to the bi-fuel engine which uses liquid fuels other than gasoline, or uses gaseous fuels other than CNG in the aspect similar to it, or it.

  DESCRIPTION OF SYMBOLS 10 ... Intake passage, 11 ... Throttle valve, 12 ... Throttle motor, 13 ... Intake manifold (intake passage), 14 ... Intake port (intake passage), 15 ... Combustion chamber, 16 ... Spark plug, 17 ... Gasoline injection valve (liquid Fuel injection valve), 18 ... gasoline tank, 19 ... fuel pump, 20 ... CNG cylinder, 21 ... manual valve, 22 ... high pressure CNG pipe, 23 ... CNG regulator, 24 ... shutoff valve, 25 ... shutoff valve, 26 ... high pressure side Fuel pressure sensor, 27 ... Low pressure CNG pipe, 28 ... CNG delivery pipe, 29 ... Low pressure side fuel pressure sensor, 30 ... Low pressure side fuel temperature sensor, 31 ... CNG injection valve (gaseous fuel injection valve), 32 ... CNG hose, 33 ... CNG nozzle, 40 ... electronic control device, 41 ... first control unit, 42 ... second control unit (control unit), 43 ... vehicle speed sensor, 44 ... Kuseru pedal sensor, 45 ... air flow meter, 46 ... crank angle sensor, 47 ... water temperature sensor, 48 ... throttle sensor, 49 ... CNG change-over switch.

Claims (4)

Applied to an internal combustion engine capable of switching between a liquid fuel operation in which liquid fuel is injected into an intake passage by a liquid fuel injection valve and a gas fuel operation in which gaseous fuel is injected into an intake passage by a gas fuel injection valve;
A fuel injection control device for an internal combustion engine comprising a control unit that converts a drive signal of the liquid fuel injection valve into a drive signal of the gaseous fuel injection valve and outputs it during gas fuel operation,
The control unit is configured such that the ratio of the time width of the drive signal of the gas fuel injection valve to the time width of the drive signal of the liquid fuel injection valve is smaller during acceleration operation during gas fuel operation than during non-acceleration operation. To derive a drive signal for the gaseous fuel injection valve,
A fuel injection control device for an internal combustion engine. A sub signal having a pulse width shorter than that of the main signal is added to the drive signal of the liquid fuel injection valve during acceleration operation,
The control unit ignores the sub signal when deriving a drive signal of the gaseous fuel injection valve during acceleration operation during gaseous fuel operation,
The fuel injection control device for an internal combustion engine according to claim 1. In the acceleration operation at the time of the gas fuel operation, when the pulse width of the drive signal of the liquid fuel injection valve is shorter than a predetermined time when the drive signal of the gas fuel injection valve is derived, the control unit Determining that the drive signal is the sub-signal;
The fuel injection control device for an internal combustion engine according to claim 2. The control unit detects the drive signal of the liquid fuel injection valve outside a predetermined period during which the main signal can be detected when deriving the drive signal of the gaseous fuel injection valve during acceleration operation during gas fuel operation. If it is determined that the drive signal is the sub signal,
The fuel injection control device for an internal combustion engine according to claim 2.