JP2015086839A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device capable of sufficiently reducing manufacturing costs and simplifying a structure in comparison with a conventional one.SOLUTION: A fuel injection device includes: a fuel supply pipe 24a branched from a gas fuel injector 22a at a downstream side, and forming a fuel supply passage 25a communicated to uniformly supply CNG to cylinders #1 and #2 formed on an engine 2; a fuel supply pipe 24b branched from the gas fuel injector 22b at a downstream side and forming a fuel supply passage 25b communicated to uniformly supply CNG to cylinders #3 and #4 formed on the engine 2; and an injection control portion 60 controlling the gas fuel injectors 22a and 22b to start injection of CNG when specific cylinders #2 and #3 are in exhaust stroke.

Description

  The present invention relates to a fuel injection device, and more particularly to a fuel injection device for an internal combustion engine that uses at least gaseous fuel as a driving fuel.

  As a vehicle equipped with an internal combustion engine that uses at least gaseous fuel as a driving fuel, for example, there are a plurality of fuels such as gasoline as a liquid fuel and compressed natural gas (hereinafter simply referred to as “CNG”) as a gaseous fuel. A vehicle equipped with a bi-fuel engine that uses fuel as a driving fuel is known.

  In general, a vehicle equipped with a bi-fuel engine is provided with a gasoline injection injector and a CNG injection injector for each cylinder formed in the internal combustion engine. There is a problem that it becomes complicated.

  In order to solve such a problem, Patent Document 1 discloses that a liquid fuel and gas fuel are used for supplying liquid fuel to a plurality of cylinders with a single liquid fuel injection device. Proposed.

Japanese Patent Application Laid-Open No. 2004-124891

  However, although what is proposed in Patent Document 1 is considered for a liquid fuel injection device, it is not considered for an expensive gaseous fuel injection device as compared with a liquid fuel injection device. There existed a subject that cost reduction and simplification of structure were not fully aimed at.

  Accordingly, the present invention has been made to solve such problems, and provides a fuel injection device capable of sufficiently reducing the manufacturing cost and simplifying the structure as compared with the conventional one. For the purpose.

  A first aspect of the present invention is a fuel injection device for an internal combustion engine provided with a gaseous fuel injector for injecting gaseous fuel, and is branched from a downstream side of the gaseous fuel injector and is formed of cylinders formed in the internal combustion engine. A series of four strokes comprising a fuel supply pipe that forms a fuel supply passage communicating with the two cylinders, and an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke so that gaseous fuel is evenly supplied to the two cylinders. Among these, an injection control unit that controls the gaseous fuel injector to start injection of gaseous fuel when a specific cylinder of the two cylinders is in the exhaust stroke is provided.

  As a second aspect of the present invention, the fuel supply passage may communicate with a specific cylinder and a cylinder that is ignited next to the specific cylinder.

  As a third aspect of the present invention, the fuel supply passage communicates with a specific cylinder and a cylinder that is ignited after the specific cylinder, and the injection control unit is ignited after the specific cylinder. The gaseous fuel injector may be further controlled to start the injection of gaseous fuel when the cylinder is in the exhaust stroke.

  As a fourth aspect of the present invention, a liquid fuel injector that injects liquid fuel, a rotation angle sensor that detects a rotation angle of an output shaft of the internal combustion engine, and an internal combustion engine based on the rotation angle detected by the rotation angle sensor And a misfire counter that counts the number of times the misfire has been detected by the misfire detection unit, and the injection control unit has a predetermined threshold value counted by the misfire counter. It is also possible to prohibit the injection of gaseous fuel by the gaseous fuel injector and to control the liquid fuel injector so as to inject the liquid fuel on the condition that the above is exceeded.

  As a fifth aspect of the present invention, based on the valve that adjusts the intake air amount of the internal combustion engine, the rotation angle sensor that detects the rotation angle of the output shaft of the internal combustion engine, and the rotation angle detected by the rotation angle sensor, On condition that a misfire detection unit that detects misfire of the internal combustion engine, a misfire counter that counts the number of times the misfire is detected by the misfire detection unit, and a count value counted by the misfire counter exceeds a predetermined threshold value And a valve control unit that controls the valve so that the intake air amount becomes less than a predetermined intake air amount.

  As described above, the first aspect described above can inject gas fuel into two cylinders with one gas fuel injector, and therefore, compared with the conventional one in which the gas fuel injector is provided for each cylinder. Thus, it is possible to sufficiently reduce the manufacturing cost and simplify the structure.

  In the second aspect, gaseous fuel for two cylinders, that is, a specific cylinder and a cylinder that is ignited next to the specific cylinder, can be injected into one gaseous fuel injector.

  In the third aspect, gaseous fuel for two cylinders, that is, a specific cylinder and a cylinder that is ignited two times after the specific cylinder, can be injected into one gaseous fuel injector.

  In the fourth aspect, on the condition that the count value of the misfire counter exceeds the threshold value, the gaseous fuel injector is prohibited from injecting the gaseous fuel, and the liquid fuel injector is controlled to inject the liquid fuel. The occurrence of misfire in the internal combustion engine can be suppressed.

  In the fifth aspect, since the intake air amount of the internal combustion engine is suppressed on the condition that the count value of the misfire counter exceeds the threshold value, the occurrence of misfire in the internal combustion engine can be suppressed.

FIG. 1 is a configuration diagram showing a main part of a vehicle equipped with a fuel injection device according to a first embodiment of the present invention. FIG. 2 is a conceptual diagram showing a series of four strokes of each cylinder of the engine shown in FIG. FIG. 3 is a conceptual diagram showing the injection timing of gaseous fuel for each cylinder of the engine shown in FIG. FIG. 4 is a configuration diagram showing a main part of a vehicle equipped with a fuel injection device according to the second embodiment of the present invention. FIG. 5 is a conceptual diagram showing the injection timing of gaseous fuel for each cylinder of the engine shown in FIG. FIG. 6 is a flowchart showing a misfire detection operation of the fuel injection device according to the second embodiment of the present invention. FIG. 7 is a timing chart for explaining the misfire detection operation of the fuel injection device according to the second embodiment of the present invention. FIG. 8 is a configuration diagram showing a main part of a vehicle equipped with a fuel injection device according to the third embodiment of the present invention. FIG. 9 is a flowchart showing a misfire detection operation of the fuel injection device according to the third embodiment of the present invention. FIG. 10 is a timing chart for explaining the misfire detection operation of the fuel injection device according to the third embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
As shown in FIG. 1, a vehicle 1 equipped with a fuel injection device according to a first embodiment of the present invention includes an internal combustion engine type engine 2 and an ECU (Electronic Control Unit) 3. Yes.

  A plurality of cylindrical cylinders 10 are formed in the engine 2. Each cylinder 10 accommodates a piston 11 so as to be able to reciprocate. As shown in FIG. 2, the engine 2 performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston 11 reciprocates twice in the cylinder 10, and between the compression stroke and the expansion stroke. It is constituted by a four-cycle engine that ignites.

In the present embodiment, the engine 2 is configured by an in-line 4-cylinder engine. However, in the present invention, an in-line 6-cylinder engine, a V-type 6-cylinder engine, a V-type 12-cylinder engine, or a horizontally opposed 6 engine. You may be comprised by various types of engines, such as a cylinder engine.
Further, the four cylinders 10 arranged in series are shown with identification numbers # 1 to # 4, respectively. In the following description, each cylinder 10 is referred to as “cylinder # 1” and “cylinder # 2”. , Also referred to as “cylinder # 3” or “cylinder # 4”.

The engine 2 is provided with a crankshaft 12 as its output shaft. The piston 11 accommodated in each cylinder 10 is connected to the crankshaft 12 via a connecting rod that converts the reciprocating motion into a rotational motion.
Therefore, the engine 2 generates a driving force for driving the vehicle 1 by causing the piston 11 to reciprocate by burning the fuel / air mixture in the cylinder 10 and rotating the crankshaft 12. It has become.

The crankshaft 12 is provided with a rotation angle sensor 13 that detects the rotation angle of the crankshaft 12. Specifically, the rotation angle sensor 13 has a signal rotor provided so as to rotate integrally with the crankshaft 12. On the outer periphery of the signal rotor, teeth are formed at regular intervals, for example, every 30 degrees, except for the reference missing tooth.
The rotation angle sensor 13 has a sensor for detecting the passage of these teeth. This sensor generates a pulse signal corresponding to the presence or absence of the teeth of the signal rotor. That is, the rotation angle sensor 13 generates a pulse signal corresponding to the rotation of the crankshaft 12.

The engine 2 is provided with an intake manifold 20. The intake manifold 20 communicates with an intake passage for sucking outside air. That is, the intake manifold 20 communicates the intake passage and each cylinder 10.
The intake manifold 20 is provided with four liquid fuel injectors 21 that inject liquid fuel toward each cylinder 10, and two gaseous fuel injectors 22 a and 22 b that inject gaseous fuel toward each cylinder 10. .

The liquid fuel injector 21 has a solenoid coil and a needle valve that are controlled by the ECU 3. For example, gasoline is supplied to each liquid fuel injector 21 at a predetermined pressure as the liquid fuel. When the solenoid coil is energized by the ECU 3, the liquid fuel injector 21 opens the needle valve and injects liquid fuel toward the cylinder 10.
In addition, although the liquid fuel in this Embodiment is gasoline, it replaces with gasoline and may be alcohol fuel which mixed alcohol and gasoline, such as hydrocarbon fuels, such as light oil, and ethanol.

The injection port of the gaseous fuel injector 22a is connected to the fuel supply pipe 24a. The gaseous fuel injector 22b has an injection port connected to the fuel supply pipe 24b. Each gaseous fuel injector 22a, 22b has a solenoid coil and a needle valve controlled by the ECU 3.
In the present embodiment, CNG is supplied to each gaseous fuel injector 22a, 22b as a gaseous fuel at a predetermined pressure. When the solenoid coil is energized by the ECU 3, the gaseous fuel injectors 22a and 22b open the needle valve and inject gaseous fuel, that is, CNG into the fuel supply pipes 24a and 24b, respectively.

Specifically, the fuel supply pipe 24a branches downstream from the gaseous fuel injector 22a, and communicates with the two cylinders 10 so that CNG is uniformly supplied to the two cylinders 10 out of the four cylinders 10. A fuel supply passage 25a is formed. In the present embodiment, the fuel supply passage 25a communicates with a specific cylinder # 2 and a cylinder # 1 that is ignited next to the cylinder # 2.
That is, the fuel supply passage 25a is formed such that the distance and diameter from the injection port of the gaseous fuel injector 22a to the cylinder # 1 and the distance and diameter from the injection port of the gaseous fuel injector 22a to the cylinder # 2 are equal. Has been.

The fuel supply pipe 24b branches downstream from the gaseous fuel injector 22b, and a fuel supply passage 25b that communicates with the two cylinders 10 so that CNG is uniformly supplied to the two cylinders 10 of the four cylinders 10. Form. In the present embodiment, the fuel supply passage 25b communicates with a specific cylinder # 3 and a cylinder # 4 that is ignited next to the cylinder # 3.
That is, the fuel supply passage 25b is formed such that the distance and diameter from the injection port of the gaseous fuel injector 22b to the cylinder # 3 and the distance and diameter from the injection port of the gaseous fuel injector 22b to the cylinder # 4 are equal. Has been.

The intake manifold 20 is provided with a surge tank 26 having a predetermined volume that suppresses pulsation and interference of intake air, and a throttle valve 27 for adjusting the intake air amount of the engine 2.
The throttle valve 27 is constituted by a thin disc-like valve body, and includes a shaft in the center of the valve body. The throttle valve 27 is provided with a throttle valve actuator 28 for rotating the valve body by rotating the shaft in accordance with the control of the ECU 3 and adjusting the intake air amount to the throttle valve 27. The throttle valve 27 is provided with a throttle opening sensor 29 that detects the opening of the throttle valve 27.

Further, the engine 2 is provided with an exhaust manifold 30 for discharging exhaust gas to the outside of the vehicle. The exhaust manifold 30 communicates with the exhaust passage. That is, the exhaust manifold 30 communicates the exhaust passage and each cylinder 10.
A catalyst device 31 is provided in the exhaust manifold 30. The catalyst device 31 generally includes a three-way catalyst that can efficiently remove harmful substances such as unburned hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) contained in exhaust gas. ing. As this three-way catalyst, a catalyst having a function of efficiently removing NOx even from exhaust gas having a high NOx content is preferably used.

The ECU 3 includes a computer unit that includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a flash memory, an input port, and an output port.
A program for causing the computer unit to function as the ECU 3 is stored in the ROM of the ECU 3 together with various control constants and various maps. That is, in the ECU 3, when the CPU reads a program from the ROM into the RAM and executes the read program, the computer unit functions as the ECU 3.

  In the present embodiment, various sensors including the rotation angle sensor 13 and the throttle opening sensor 29 are connected to the input port of the ECU 3. On the other hand, various control objects such as a liquid fuel injector 21, gaseous fuel injectors 22a and 22b, and a throttle valve actuator 28 are connected to the output port of the ECU 3. The ECU 3 controls various control objects based on information obtained from various sensors.

In the present embodiment, the ECU 3 constitutes an injection control unit 40, and the engine 2 is driven by gasoline injected from the liquid fuel injector 21 in accordance with the operation of a switch provided on an instrument panel or the like and the operating state of the vehicle 1. The liquid fuel drive mode for driving the engine 2 and the gas fuel drive mode for driving the engine 2 by the CNG injected from the gaseous fuel injectors 22a and 22b are taken.
In the liquid fuel drive mode, the ECU 3 controls each liquid fuel injector 21 to start gasoline injection when each cylinder 10 is in the exhaust stroke.

In FIG. 3, as indicated by the hatching pattern, in the gaseous fuel drive mode, the ECU 3 injects CNG when a specific cylinder in the two cylinders 10 with which the fuel supply passages 25 a and 25 b communicate with each other is in the exhaust stroke. The gaseous fuel injectors 22a and 22b are controlled so as to start the operation.
That is, the ECU 3 controls the gaseous fuel injector 22a to start CNG injection when a specific cylinder # 2 of the two cylinders # 1 and # 2 with which the fuel supply passage 25a communicates is in the exhaust stroke. It is like that.

Here, CNG is injected into cylinder # 2 at substantially the same timing as in the liquid fuel drive mode. On the other hand, CNG is injected into cylinder # 1 earlier than when in the liquid fuel drive mode.
However, since CNG is a gas, it does not adhere to the inner surface of the intake manifold 20 and the valves that open and close the intake manifold 20 and the cylinder # 1. For this reason, CNG is supplied to the cylinder # 1 without shortage.
The ECU 3 controls the gaseous fuel injector 22a so as to inject two cylinders, that is, twice as much CNG as compared with the case where CNG is injected into each cylinder 10.

Similarly, in the gaseous fuel drive mode, the ECU 3 starts CNG injection when a specific cylinder # 3 of the two cylinders # 3 and # 4 with which the fuel supply passage 25a communicates is in the exhaust stroke. The gaseous fuel injector 22a is controlled.
Here, CNG is injected into cylinder # 3 at substantially the same timing as in the liquid fuel drive mode. On the other hand, CNG is injected into cylinder # 4 earlier than when in the liquid fuel drive mode.
However, since CNG is a gas, it does not adhere to the inner surface of the intake manifold 20 and the valves that open and close the intake manifold 20 and the cylinder # 4. For this reason, CNG is supplied to the cylinder # 4 without being insufficient.
Further, the ECU 3 controls the gaseous fuel injector 22b so as to inject the amount of CNG for two cylinders, that is, twice as much as the case where CNG is injected into each cylinder 10.

As described above, in the present embodiment, the CNG for two cylinders # 1 and # 2 is injected into the gaseous fuel injector 22a, and the CNG for two cylinders # 3 and # 4 is gasified. Since fuel can be injected into the fuel injector 22b, it is possible to sufficiently reduce the manufacturing cost and simplify the structure as compared with the conventional one in which a gaseous fuel injector is provided for each cylinder.
Instead of the present embodiment, the fuel supply pipe 25a is configured so that the fuel supply passage 25a communicates with a specific cylinder # 1 and a cylinder # 3 that is ignited next to the cylinder # 1. The fuel supply pipe 25b may be configured so that the passage 25a communicates with a specific cylinder # 4 and a cylinder # 2 that is ignited next to the cylinder # 4. In this case, the ECU 3 injects CNG into the gaseous fuel injector 22a when the specific cylinder # 1 is in the exhaust stroke, and injects CNG into the gaseous fuel injector 22b when the specific cylinder # 4 is in the exhaust stroke. Configured to let

(Second Embodiment)
In the present embodiment, differences from the first embodiment of the present invention will be described. In addition, among the components in the present embodiment, the same components as those in the first embodiment of the present invention are denoted by the same reference numerals, and different points will be described.

  As shown in FIG. 4, the gaseous fuel injector 22a in the present embodiment has an injection port connected to the fuel supply pipe 50a. The gaseous fuel injector 22b has an injection port connected to the fuel supply pipe 50b.

The fuel supply pipe 50a branches downstream from the gaseous fuel injector 22a, and forms a fuel supply passage 51a communicating with the cylinder 10 so that CNG is uniformly supplied to two cylinders 10 of the four cylinders 10. . In the present embodiment, the fuel supply passage 51a communicates with a specific cylinder # 1 and a cylinder # 4 that is ignited two cylinders after the cylinder # 1.
That is, the fuel supply passage 51a is formed such that the distance and diameter from the injection port of the gaseous fuel injector 22a to the cylinder # 1 and the distance and diameter from the injection port of the gaseous fuel injector 22a to the cylinder # 4 are equal. Has been.

The fuel supply pipe 50b branches downstream from the gaseous fuel injector 22b, and forms a fuel supply passage 51b communicating with the cylinder 10 so that CNG is uniformly supplied to the two cylinders 10 out of the four cylinders 10. . In the present embodiment, the fuel supply passage 51b communicates with a specific cylinder # 2 and a cylinder # 3 that is ignited after the cylinder # 2.
That is, the fuel supply passage 51b is formed such that the distance and diameter from the injection port of the gaseous fuel injector 22b to the cylinder # 2 are equal to the distance and diameter from the injection port of the gaseous fuel injector 22b to the cylinder # 3. Has been.

The ECU 3 is different from the first embodiment of the present invention in the program stored in the ROM. Specifically, the ECU 3 constitutes an injection control unit 60, and the engine 2 is driven by gasoline injected from the liquid fuel injector 21 in accordance with an operation of a switch provided on an instrument panel or the like and an operating state of the vehicle 1. The driving mode is either a liquid fuel driving mode for driving or a gaseous fuel driving mode for driving the engine 2 by CNG injected from the gaseous fuel injectors 22a and 22b.
In the liquid fuel drive mode, the ECU 3 controls each liquid fuel injector 21 to start gasoline injection when each cylinder 10 is in the exhaust stroke.

  In FIG. 5, as indicated by the hatching pattern, in the gaseous fuel drive mode, the ECU 3 determines whether the CNG is in the exhaust stroke when a specific cylinder is in the exhaust stroke of the two cylinders 10 through which the fuel supply passages 51 a and 51 b communicate. The gaseous fuel injectors 22a and 22b are controlled so as to start injection.

That is, the ECU 3 controls the gaseous fuel injector 22a to start CNG injection when the two cylinders # 1 and # 4 with which the fuel supply passage 51a communicates are in the exhaust stroke.
Here, CNG is injected into cylinders # 1 and # 4 at substantially the same timing as in the liquid fuel drive mode.

The ECU 3 controls the gaseous fuel injector 22a so as to inject 8/5 times the amount of CNG compared to the amount when fuel is injected into each cylinder 10. That is, the ECU 3 controls the gaseous fuel injector 22a so as to inject 4/5 times the amount of CNG into one cylinder 10.
Here, when cylinder # 1 is in the exhaust stroke, cylinder # 4 is in the compression stroke, so when cylinder # 1 is in the intake stroke, part of the CNG injected into cylinder # 4 is Inhaled by # 1. At this time, since CNG of about 1/5 times remains in the cylinder # 4, the CNG sucked into the cylinder # 1 is 4/5 times the amount of CNG injected during the exhaust stroke. In total, it becomes 1 time. Similarly, the amount of CNG sucked into the cylinder # 4 is also doubled.

In the gaseous fuel drive mode, the ECU 3 controls the gaseous fuel injector 22b so as to start CNG injection when the two cylinders # 2 and # 3 with which the fuel supply passage 51a communicates are in the exhaust stroke. It has become.
Here, CNG is injected into cylinders # 2 and # 3 at substantially the same timing as in the liquid fuel drive mode.

  Further, the ECU 3 controls the gaseous fuel injector 22b so as to inject 8/5 times as much CNG as compared with the case of injecting fuel into each cylinder 10. That is, the ECU 3 controls the gaseous fuel injector 22b so as to inject 4/5 times the amount of CNG into one cylinder 10.

  In the present embodiment, as compared with the first embodiment of the present invention, each cylinder 10 is injected with CNG in the exhaust stroke and the compression stroke, and is 4/5 times the amount of CNG injected in the exhaust stroke. Then, 1/5 times the amount of CNG injected in the compression stroke is sucked in in the intake stroke. For this reason, when the engine speed of the engine 2 increases, each cylinder 10 cannot sufficiently intake CNG injected in the compression stroke, and the engine 2 may misfire.

  For this reason, as shown in FIG. 4, the ECU 3 detects the misfire by the misfire detection unit 61 that detects misfire of the engine 2 and the misfire detection unit 61 based on the rotation angle detected by the rotation angle sensor 13. And misfire counter 62 that counts the number of times of occurrence.

  The misfire detection unit 61 counts the pulses of the pulse signal on the basis of the position corresponding to the missing tooth of the pulse signal generated by the rotation angle sensor 13, and is delayed in counting even though the engine 2 is in the operating state. If there is, it is detected as misfire.

Further, the ECU 3 prohibits gaseous fuel injection by the gaseous fuel injectors 22a and 22b on condition that the count value Cm counted by the misfire counter 62 exceeds a predetermined threshold value TH (for example, 4), The liquid fuel injector 21 is controlled to inject liquid fuel.
That is, the ECU 3 switches the drive mode from the gas fuel drive mode to the liquid fuel drive mode on condition that the count value Cm counted by the misfire counter 62 exceeds a predetermined threshold value TH.

  The misfire detection operation by the fuel injection device according to the embodiment of the present invention configured as described above will be described with reference to FIG. The misfire detection operation described below is executed, for example, when the gaseous fuel drive mode is selected by a switch provided on an instrument panel or the like.

First, the ECU 3 selects the gaseous fuel drive mode as the drive mode (step S1). Next, the ECU 3 determines whether or not misfire of the engine 2 has been detected based on the rotation angle detected by the rotation angle sensor 13 (step S2).
If it is determined that the misfire of the engine 2 has not been detected, the ECU 3 returns the misfire detection operation to step S1. On the other hand, when determining that the misfire of the engine 2 has been detected, the ECU 3 adds 1 to the count value Cm of the misfire counter 62 (step S3).

  Next, the ECU 3 determines whether or not the count value Cm of the misfire counter 62 has exceeded the threshold value TH (step S4). Here, when it is determined that the count value Cm of the misfire counter 62 does not exceed the threshold value TH, the ECU 3 returns the misfire detection operation to step S1. On the other hand, when determining that the count value Cm of the misfire counter 62 has exceeded the threshold value TH, the ECU 3 switches the drive mode from the gas fuel drive mode to the liquid fuel drive mode (step S5).

Next, the ECU 3 determines whether or not misfire has been detected by the misfire detection unit 61 over a predetermined time (step S6). If it is determined that misfire has been detected, the ECU 3 returns the misfire detection operation to step S5.
On the other hand, when determining that no misfire has been detected, the ECU 3 resets the count value Cm of the misfire counter 62 to 0 (step S7), and returns the misfire detection operation to step S1.

  For example, as shown in FIG. 7, if misfire is detected by the misfire detection unit 61 at each time from time t1 to time t5, the count value Cm counted by the misfire counter 62 at time t5 is determined in advance. In order to exceed the threshold value TH (= 4), the injection control unit 60 switches the drive mode from the gaseous fuel drive mode to the liquid fuel drive mode.

  As described above, in the present embodiment, the CNG for two cylinders # 1 and # 4 is injected into the gaseous fuel injector 22a, and the CNG for two cylinders # 2 and # 3 is gasified. Since fuel can be injected into the fuel injector 22b, it is possible to sufficiently reduce the manufacturing cost and simplify the structure as compared with the conventional one in which a gaseous fuel injector is provided for each cylinder.

  Further, in the present embodiment, on the condition that the count value Cm of the misfire counter 62 exceeds the threshold value TH, the injection of the gaseous fuel by the gaseous fuel injectors 22a and 22b is prohibited, and the liquid fuel is injected so as to inject the liquid fuel. Since the injector is controlled, the occurrence of misfire in the engine 2 can be suppressed.

(Third embodiment)
In the present embodiment, differences from the second embodiment of the present invention will be described. In addition, among the components in the present embodiment, the same components as those in the second embodiment of the present invention are denoted by the same reference numerals, and different points will be described.

  The ECU 3 is different from the second embodiment of the present invention in the program stored in the ROM. Specifically, in the second embodiment of the present invention, the ECU 3 configures the injection control unit 60 as shown in FIG.

  The injection control unit 70 causes the injection control unit 60 to inject gaseous fuel by the gaseous fuel injectors 22a and 22b on the condition that the count value Cm counted by the misfire counter 62 has exceeded a predetermined threshold value TH. The function of prohibiting and controlling the liquid fuel injector 21 to inject liquid fuel is omitted.

  Instead, the ECU 3 sets the intake air amount of the engine 2 to be less than the predetermined intake air amount on condition that the count value Cm counted by the misfire counter 62 exceeds a predetermined threshold value TH. Thus, the valve control unit 71 for controlling the throttle valve 27 via the throttle valve actuator 28 is further configured.

  The misfire detection operation by the fuel injection device according to the embodiment of the present invention configured as described above will be described with reference to FIG. The misfire detection operation described below is executed, for example, when the gaseous fuel drive mode is selected by a switch provided on an instrument panel or the like.

First, the ECU 3 selects the gaseous fuel drive mode as the drive mode (step S11). Next, the ECU 3 determines whether or not misfire of the engine 2 has been detected based on the rotation angle detected by the rotation angle sensor 13 (step S12).
If it is determined that the misfire of the engine 2 has not been detected, the ECU 3 returns the misfire detection operation to step S11. On the other hand, when determining that the misfire of the engine 2 has been detected, the ECU 3 adds 1 to the count value Cm of the misfire counter 62 (step S13).

Next, the ECU 3 determines whether or not the count value Cm of the misfire counter 62 has exceeded the threshold value TH (step S14). Here, if it is determined that the count value Cm of the misfire counter 62 does not exceed the threshold value TH, the ECU 3 returns the misfire detection operation to step S11.
On the other hand, when it is determined that the count value Cm of the misfire counter 62 exceeds the threshold value TH, the ECU 3 passes the throttle valve actuator 28 so that the intake air amount of the engine 2 becomes less than a predetermined intake air amount THq. Then, the throttle valve 27 is controlled (step S15).

Next, the ECU 3 determines whether or not misfire has been detected by the misfire detection unit 61 over a predetermined time (step S16). If it is determined that misfire has been detected, the ECU 3 returns the misfire detection operation to step S15.
On the other hand, when determining that no misfire has been detected, the ECU 3 resets the count value Cm of the misfire counter 62 to 0 (step S17), and returns the misfire detection operation to step S11.

  For example, as shown in FIG. 10, when misfire is detected by the misfire detection unit 61 at each time from time t1 to time t5, the count value Cm counted by the misfire counter 62 at time t5 is determined in advance. Since the threshold value TH (= 4) is exceeded, the valve control unit 71 controls the throttle valve 27 via the throttle valve actuator 28 so that the intake air amount of the engine 2 becomes less than a predetermined intake air amount THq. To do. That is, at time t5, the throttle valve 27 changes from the non-restricted state to the restricted state.

  As described above, in the present embodiment, similarly to the second embodiment of the present invention, CNG corresponding to 10 cylinders of two cylinders # 1 and # 4 is injected into the gaseous fuel injector 22a, and cylinder # 2 , # 3 CNG for 10 cylinders can be injected into the gas fuel injector 22b, so that the manufacturing cost can be reduced and the structure can be reduced as compared with the conventional gas fuel injector provided for each cylinder. Can be sufficiently simplified.

  Further, in the present embodiment, on the condition that the count value Cm of the misfire counter 62 exceeds the threshold value TH, the intake air amount of the engine 2 is suppressed, so that the occurrence of misfire in the engine 2 is suppressed. it can.

  Although the embodiments of the present invention have been disclosed above, it is obvious that those skilled in the art can make modifications without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the claims recited in the claims.

1 vehicle 2 engine (internal combustion engine)
3 ECU (injection control unit, misfire detection unit, misfire counter, valve control unit)
10 cylinder 12 crankshaft (output shaft)
DESCRIPTION OF SYMBOLS 13 Rotation angle sensor 21 Liquid fuel injector 22a, 22b Gaseous fuel injector 24a, 24b, 50a, 50b Fuel supply pipe 25a, 25b, 51a, 51b Fuel supply path 27 Throttle valve (valve)
40, 60, 70 Injection control unit 61 Misfire detection unit 62 Misfire counter 71 Valve control unit

Claims (5)

A fuel injection device for an internal combustion engine provided with a gaseous fuel injector for injecting gaseous fuel,
A fuel supply passage is formed that branches downstream from the gaseous fuel injector and communicates with the two cylinders so that the gaseous fuel is uniformly supplied to two of the cylinders formed in the internal combustion engine. A fuel supply pipe;
In the series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke, the gas fuel injection is started when a specific cylinder of the two cylinders is in the exhaust stroke. An injection control unit that controls a fuel injector.   2. The fuel injection device according to claim 1, wherein the fuel supply passage communicates with the specific cylinder and a cylinder that is ignited next to the specific cylinder. The fuel supply passage communicates with the specific cylinder and a cylinder that is ignited two times after the specific cylinder,
The said injection control part further controls the said gaseous fuel injector so that injection of the said gaseous fuel may be started when the cylinder ignited after the said specific cylinder exists in the said exhaust stroke. Item 4. The fuel injection device according to Item 1. A liquid fuel injector for injecting liquid fuel; and
A rotation angle sensor for detecting a rotation angle of the output shaft of the internal combustion engine;
A misfire detection unit that detects misfire of the internal combustion engine based on the rotation angle detected by the rotation angle sensor;
A misfire counter that counts the number of times misfire has been detected by the misfire detection unit, and
The injection control unit prohibits injection of gaseous fuel by the gaseous fuel injector and injects the liquid fuel on condition that the count value counted by the misfire counter exceeds a predetermined threshold value. The fuel injection device according to claim 3, wherein the liquid fuel injector is controlled. A valve for adjusting the intake air amount of the internal combustion engine;
A rotation angle sensor for detecting a rotation angle of the output shaft of the internal combustion engine;
A misfire detection unit that detects misfire of the internal combustion engine based on the rotation angle detected by the rotation angle sensor;
A misfire counter that counts the number of times misfire has been detected by the misfire detector;
A valve control unit that controls the valve so that the intake air amount becomes less than a predetermined intake air amount on condition that the count value counted by the misfire counter exceeds a predetermined threshold; The fuel injection device according to claim 3, further comprising:

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