Control device of internal combustion engine

Abstract

To suitably determine the reduction of fuel residual quantity.SOLUTION: A control device 60 of an internal combustion engine of the present invention includes a control unit 61 for controlling an opening of a throttle valve 32, an estimation unit 62 for estimating an amount of intake air flowing into an engine body 11 on the basis of the opening of the throttle valve 32, and a determination unit 63 which determines that fuel residual quantity is reduced when the difference between the amount of intake air detected by an air flow sensor 33 during driving of the engine body 11 and the amount of intake air estimated by the estimation unit 62 is equal to or more than a prescribed value. The reduction of the fuel residual quantity can be suitably determined by using the difference between the actual amount of intake air and the estimated amount of intake air which is generated in a fuel deficiency condition.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine.

Background Art

[0002] Conventionally, internal combustion engines driven using gaseous fuels have been known. In a vehicle equipped with such an internal combustion engine, when the remaining fuel amount decreases and the engine runs out of fuel, the internal combustion engine stops and the vehicle cannot be driven. Further, when the engine suddenly runs out of fuel during high load operation, the catalyst for purifying exhaust gas is exposed to high temperatures, and thermal degradation progresses rapidly. Therefore, when the remaining fuel amount is decreasing, it is necessary to notify the driver to prompt fuel replenishment, and thus it is required to appropriately determine that the remaining fuel amount is decreasing.

[0003] In Patent Document 1, in order to monitor the remaining fuel amount in a fuel tank, the fuel tank is provided with fuel remaining amount detection means such as a pressure sensor and a level gauge. Further, it is disclosed that when the fuel remaining amount detection means detects that the fuel remaining amount is below a predetermined value, the notification means prompts the user to fill the fuel.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in order to appropriately determine that the remaining fuel amount is decreasing, for example, if the fuel tank is provided with a plurality of fuel remaining amount detection means, the device may become larger or the structure may become more complex by the number of fuel remaining amount detection means provided in the fuel tank.

[0006] The present invention has been made in view of the above-described problems, and an object thereof is to appropriately determine that the remaining fuel amount is decreasing.

Means for Solving the Problems

[0007] The present invention is a control device for an internal combustion engine including a fuel injector that injects gaseous fuel, a throttle valve that adjusts an intake air amount flowing into the internal combustion engine, and an air flow sensor that detects the intake air amount flowing into the internal combustion engine, wherein the control device includes control means for controlling an opening degree of the throttle valve, estimation means for estimating an intake air amount flowing into the internal combustion engine based on the opening degree of the throttle valve, and determination means for determining that the remaining fuel amount is decreasing when a difference between the intake air amount detected by the air flow sensor during driving of the internal combustion engine and the intake air amount estimated by the estimation means is equal to or greater than a predetermined value.

Effects of the Invention

[0008] According to the present invention, it is possible to appropriately determine that the remaining fuel amount is decreasing.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0010] An embodiment according to the present invention is a control device 60 for an internal combustion engine including a fuel injector 45 that injects gaseous fuel, a throttle valve 32 that adjusts the intake air amount flowing into the engine body 11, and an air flow sensor 33 that detects the intake air amount flowing into the engine body 11. The control device 60 includes a control unit 61 that controls the opening degree of the throttle valve 32, an estimation unit 62 that estimates the intake air amount flowing into the engine body 11 based on the opening degree of the throttle valve 32, and a determination unit 63 that determines that the fuel remaining amount is decreasing when the difference between the intake air amount detected by the air flow sensor 33 during the driving of the engine body 11 and the intake air amount estimated by the estimation unit 62 is equal to or greater than a predetermined value. By using the difference between the actual intake air amount and the estimated intake air amount that occurs in the case of a fuel shortage state, it is possible to appropriately determine that the fuel remaining amount is decreasing.

Example

[0011] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of a vehicle 1 equipped with a control device (hereinafter referred to as a control device) for an internal combustion engine according to the present embodiment. Note that FIG. 1 is simplified for convenience of explanation to describe the present embodiment, and it is assumed that the vehicle is equipped with components that are not shown even though they are normally provided. The vehicle 1 according to the present embodiment includes an engine 10 as an internal combustion engine, a notification device 50, a control device 60, and the like.

[0012] The engine 10 performs a series of processes including an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. The engine 10 includes an engine body 11, an intake system, an exhaust system, a fuel system, and the like. The engine body 11 is configured by integrally coupling a cylinder block 12 and a cylinder head 13. The cylinder block 12 has a crank chamber 14 formed therein. A crankshaft 15 is rotatably supported in the crank chamber 14. A piston 16 is fitted in the cylinder block 12, and as the piston 16 reciprocates, the crankshaft 15 rotates via a connecting rod 17. A combustion chamber 18 is formed between the cylinder block 12 and the cylinder head 13. An ignition plug 19 is disposed on the cylinder head 13 such that its tip is positioned inside the combustion chamber 18.

[0013] An intake port 20 communicating with the combustion chamber 18 is formed in the cylinder head 13. The intake port 20 extends obliquely from the combustion chamber 18 toward one side wall surface of the cylinder head 13. An intake valve 21 is disposed in the intake port 20, and when the valve is opened, an air-fuel mixture in which air and fuel are mixed is taken into the combustion chamber 18. The air-fuel mixture in the combustion chamber 18 is ignited by the ignition plug 19 and burns, causing the piston 16 to reciprocate inside the cylinder block 12.

[0014] An exhaust port 22 communicating with the combustion chamber 18 is formed in the cylinder head 13. The exhaust port 22 extends obliquely from the combustion chamber 18 toward the other side wall surface of the cylinder head 13. An exhaust valve 23 is disposed in the exhaust port 22, and when the valve is opened, the exhaust gas generated by burning the air-fuel mixture in the combustion chamber 18 is discharged from the combustion chamber 18. Note that the configuration of the engine body 11 is not particularly limited, and various known engines can be applied.

[0015] Further, the engine 10 has a crank angle sensor 24 and an engine speed sensor 25. The crank angle sensor 24 detects the crank angle (rotation angle of the crankshaft 15) and transmits the detected crank angle information to the control device 60. The control device 60 controls the ignition timing of the ignition plug 19 based on the crank angle information detected by the crank angle sensor 24.

[0016] The engine speed sensor 25 detects information on the engine speed, specifically the number of revolutions of the crankshaft 15 per unit time, and transmits the detected engine speed information to the control device 60. The control device 60 uses the engine speed information detected by the engine speed sensor 25 when calculating the engine load ratio.

[0017] The engine 10 has, as an intake system, an intake passage 30, an air cleaner 31, a throttle valve 32, and the like. The intake passage 30 is a passage that guides the intake air taken in from the outside of the vehicle 1 to the combustion chamber 18 via the intake port 20. The intake passage 30 is constituted by, for example, an intake pipe. The downstream side of the intake passage 30 from the throttle valve 32 is constituted by an intake manifold. In the intake passage 30, an air cleaner 31 and a throttle valve 32 are arranged in order from the upstream side.

[0018] The air cleaner 31 purifies the intake air by removing foreign matters such as dust and dirt contained in the intake air. The throttle valve 32 adjusts the intake air amount by opening and closing. The throttle valve 32 adjusts the intake air amount based on the control by the control device 60.

[0019] An air flow sensor 33 and a throttle opening sensor 34 are arranged in the intake passage 30 (around the intake passage 30). The air flow sensor 33 detects information on the intake air amount and transmits the detected intake air amount information to the control device 60. The air flow sensor 33 can detect the actual intake air amount (actual intake amount) flowing through the intake passage 30. The control device 60 uses the intake air amount information detected by the air flow sensor 33 when calculating the engine load ratio. The throttle opening sensor 34 detects information on the opening degree of the throttle valve 32 (throttle opening) and transmits the detected throttle valve 32 opening degree information to the control device 60. The control device 60 estimates the intake air amount flowing through the intake passage 30 based on the throttle valve 32 opening degree information detected by the throttle opening sensor 34.

[0020] In addition, the engine 10 has an exhaust passage 40, a catalytic converter 41, etc. as an exhaust system. The exhaust passage 40 is a passage for exhausting the exhaust gas burned in the combustion chamber 18 to the outside of the vehicle 1 via the exhaust port 22. The exhaust passage 40 is constituted by, for example, an exhaust pipe. Among the exhaust passage 40, the upstream side of the catalytic converter 41 is constituted by an exhaust manifold. In the exhaust passage 40, a catalytic converter 41, a muffler (not shown), etc. are arranged in order from the upstream side. The catalytic converter 41 purifies the toxic components contained in the exhaust gas.

[0021] In addition, the engine 10 has a fuel injector 45, a fuel tank 46, a delivery pipe, etc. as a fuel system. In this embodiment, gaseous fuel is used as the fuel. The gaseous fuel is, for example, liquefied petroleum gas (LPG) or compressed natural gas (CNG).

[0022] The fuel injector 45 injects the gaseous fuel stored in the fuel tank 46 into the intake passage 30. The fuel injector 45 adjusts the injection amount of the gaseous fuel based on the control by the control device 60. Note that the fuel injector 45 is not limited to injecting the gaseous fuel into the intake passage 30, and may be configured to inject it into the intake port 20 or the combustion chamber 18. The fuel tank 46 stores the gaseous fuel. The fuel tank 46 supplies the gaseous fuel to each cylinder's fuel injector 45 via the delivery pipe while reducing the pressure of the gaseous fuel. Note that a pressure sensor for detecting the remaining amount of the gaseous fuel may be provided in the fuel tank 46.

[0023] In addition, the vehicle 1 further includes an accelerator opening sensor 48, an atmospheric pressure sensor 49, a notification device 50, etc. The accelerator opening sensor 48 detects the operation amount of the accelerator pedal by the driver and transmits the information of the detected operation amount to the control device 60. The atmospheric pressure sensor 49 detects information on the atmospheric pressure and transmits the detected atmospheric pressure information to the control device 60.

[0024] When it is determined by the control device 60 that the fuel remaining amount has decreased, the notification device 50 notifies the driver that the fuel remaining amount in the fuel tank 46 has decreased. The notification device 50 can use, for example, a display unit such as a display or a meter panel provided in the vehicle 1, a speaker, or the like. Further, when a car navigation system is provided in the vehicle 1, the notification device 50 can use the display and speaker of the car navigation system.

[0025] The control device 60 controls the entire vehicle 1. The control device 60 can use, for example, an ECU (Electronic Control Unit). As a hardware configuration, the control device 60 has a CPU, a ROM, a RAM, and the like. In the ROM, programs and predetermined information for controlling the vehicle 1, the engine 10, and the like are stored in advance. The RAM is a work memory that temporarily stores programs and data. The CPU reads the program stored in the ROM, expands it in the RAM, and executes it to control the vehicle 1, the engine 10, and the like. Further, the control device 60 of the present embodiment determines whether or not the fuel remaining amount has decreased.

[0026] FIG. 2 is a diagram showing an example of the functional configuration of the control device 60. The control device 60 includes a control unit 61, an estimation unit 62, and a determination unit 63. The control unit 61 controls the entire vehicle 1. The control unit 61 controls the throttle valve 32 so as to achieve the target opening degree of the throttle valve 32 calculated based on the accelerator opening degree detected by the accelerator opening degree sensor 48. Further, the control unit 61 controls the fuel injector 45 so that fuel is injected at a fuel injection amount obtained by correcting the reference fuel injection amount calculated according to the engine speed detected by the engine speed sensor 25 and the intake air amount detected by the air flow sensor 33 based on information from various sensors. In addition, when the engine 10 satisfies a predetermined condition (for example, in an idling state), the control unit 61 cuts off the fuel injection from the fuel injector 45.

[0027] The estimation unit 62 estimates the intake air amount (estimated intake air amount) flowing into the combustion chamber 18 of the engine 10 based on the opening degree of the throttle valve 32 detected by the throttle opening sensor 34. Specifically, the estimation unit 62 estimates the intake air amount based on the opening degree of the throttle valve 32, the engine speed, and the atmospheric pressure. Information on a map in which the estimated basic intake air amount is associated with the opening degree of the throttle valve and the engine speed is stored in the control device 60 in advance. The estimation unit 62 can calculate the basic intake air amount by referring to the map and estimate the estimated intake air amount flowing into the engine 10 by correcting the basic intake air amount based on information such as the atmospheric pressure information.

[0028] The determination unit 63 determines whether the fuel remaining amount is decreasing based on the actual intake air amount detected by the air flow sensor 33 and the estimated intake air amount estimated by the estimation unit 62. Here, since the fuel used in this embodiment is gaseous fuel, the actual intake air amount increases or decreases according to the injection amount of the injected gaseous fuel. When the fuel is sufficiently stored in the fuel tank 46 (in a fuel full state), the fuel injector 45 can inject gaseous fuel with a predetermined injection amount instructed by the control unit 61. On the other hand, when no gaseous fuel is stored in the fuel tank 46 (in a fuel shortage state), the fuel injector 45 cannot inject gaseous fuel with a predetermined injection amount instructed by the control unit 61.

[0029] Therefore, in the case of a fuel full state, since gaseous fuel with a predetermined injection amount can be injected, the filling efficiency of the intake air flowing into the combustion chamber 18 of the engine 10 decreases compared to the case of a fuel shortage state, that is, the actual intake air amount decreases. In the case of a fuel full state, the estimated intake air amount estimated by the estimation unit 62 based on the opening degree information of the throttle valve 32 is substantially the same as the actual intake air amount detected by the air flow sensor 33.

[0030] On the other hand, in the case of a fuel shortage state, since it is impossible to inject gaseous fuel with a predetermined injection amount (since the fuel becomes lean), the filling efficiency of the intake air flowing into the combustion chamber 18 of the engine 10 increases compared to the case of a fuel sufficient state, that is, the actual intake air amount increases. Here, even in the case of a fuel shortage state, the opening degree of the throttle valve 32 instructed by the control unit 61 does not change compared to the case of a fuel sufficient state. Therefore, in the case of a fuel shortage state, a difference occurs between the actual intake air amount detected by the air flow sensor 33 and the estimated intake air amount estimated by the estimator 62 based on the information of the opening degree of the throttle valve 32. Specifically, in the case of a fuel shortage state, the actual intake air amount becomes larger than the estimated intake air amount.

[0031] In this way, using the difference between the actual intake air amount and the estimated intake air amount that occurs in the case of a fuel shortage state, it is determined whether the remaining fuel amount is decreasing. Specifically, the determination unit 63 determines that the remaining fuel amount is decreasing when the difference between the actual intake air amount detected by the air flow sensor 33 during the driving of the engine 10 and the estimated intake air amount estimated by the estimator 62 is equal to or greater than a predetermined value. Note that the predetermined value is set in advance in the control device 60 and can be calculated by verifying for each type of the vehicle 1 or by simulating for each type of the vehicle 1.

[0032] Next, an example of the process by the control device 60, specifically, the process of determining that the remaining fuel amount is decreasing will be described with reference to the flowchart of FIG. 3. The flowchart of FIG. 3 is realized, for example, by the ECU which is the control device 60 executing a program. Also, the flowchart of FIG. 3 is started when the engine 10 is started.

[0033] In S1, the control unit 61 determines whether it is in steady operation. Note that the state where the injection of gaseous fuel is cut off from the fuel injector 45 is not included in steady operation. Specifically, when the engine speed is within a predetermined range for a predetermined time, the control unit 61 determines that it is in steady operation. If it is in steady operation, proceed to S2. On the other hand, if it is not in steady operation, that is, if it is in transient operation or the injection of gaseous fuel is cut off, the processes of S2 to S5 are not performed, that is, the flowchart of FIG. 3 is ended without determining the remaining fuel amount. Thus, the reason for not performing the processes after S2 when in transient operation or when the injection of gaseous fuel is cut off is that the remaining fuel amount cannot be appropriately determined.

[0034] In S2, the control unit 61 acquires information on the intake air amount (actual intake air amount) detected by the air flow sensor 33 during the driving of the engine 10. In S3, the estimation unit 62 estimates the intake air amount (estimated intake air amount) based on the opening degree of the throttle valve 32, the engine speed, and the atmospheric pressure.

[0035] In S4, the determination unit 63 determines whether the difference between the actual intake air amount detected by the air flow sensor 33 during the driving of the engine 10 and the estimated intake air amount estimated by the estimation unit 62 is equal to or greater than a predetermined value. If the difference is equal to or greater than the predetermined value, proceed to S5. If the difference is not equal to or greater than the predetermined value, the flowchart of FIG. 3 is ended without determining the remaining fuel amount.

[0036] In S5, the determination unit 63 determines that the remaining fuel amount in the fuel tank 46 is decreasing. As described above, in the case of a fuel shortage state, the actual intake air amount becomes equal to or greater than a predetermined value more than the estimated intake air amount. Therefore, when proceeding to S5, it can be determined that the remaining fuel amount in the fuel tank 46 is decreasing. Further, when the control unit 61 determines that the remaining fuel amount in the fuel tank 46 is decreasing by the determination unit 63, it notifies that the remaining fuel amount in the fuel tank 46 is decreasing via the notification device 50. Therefore, the driver can recognize that the remaining fuel amount in the fuel tank 46 is decreasing.

[0037] When the process of S5 ends, the flowchart of FIG. 3 ends. Note that the control device 60 can sequentially determine whether the remaining fuel amount in the fuel tank 46 is decreasing by periodically executing the flowchart of FIG. 3.

[0038] Thus, in the case of a fuel shortage state, a difference occurs between the actual intake air amount detected by the air flow sensor 33 and the estimated intake air amount estimated by the estimator 62 based on the opening degree information of the throttle valve 32. Therefore, the determination unit 63 of the present embodiment determines that the remaining fuel amount is decreasing when the difference between the actual intake air amount detected by the air flow sensor 33 during the driving of the engine body 11 and the estimated intake air amount estimated by the estimator 62 is equal to or greater than a predetermined value. By using the difference between the actual intake air amount and the estimated intake air amount that occurs in the case of a fuel shortage state in this way, it is possible to appropriately determine that the remaining fuel amount is decreasing. Therefore, according to the present embodiment, it is possible to suppress the device from becoming larger or the structure from becoming more complicated by providing a means for detecting the remaining fuel amount in the fuel tank 46 more than necessary.

[0039] In addition, the determination unit 63 determines whether the remaining fuel amount is decreasing during the steady operation of the engine body 11. During transient operation in which the operating state changes rapidly with time, the intake air amount is also likely to change, and there is a risk of misjudging the remaining fuel amount. By determining whether the remaining fuel amount is decreasing only during the steady operation of the engine body 11 as in the present embodiment, it is possible to appropriately determine that the remaining fuel amount is decreasing.

[0040] As described above, the embodiments according to the present invention have been described. However, the present invention is not limited to the above-described embodiments, and changes and the like are possible within the scope of the present invention. In the above-described embodiment, the vehicle 1 equipped with the engine 10 using gaseous fuel has been described, but it may be a so-called bifuel vehicle. In the case of a bifuel vehicle, when the control device 60 determines that the fuel remaining amount of the first fuel (gaseous fuel) is decreasing, it can control to switch from the first fuel to the second fuel (gaseous fuel or liquid fuel) and inject it.

Explanation of Signs

[0041] 1: Vehicle 10: Engine 11: Engine body 16: Piston 18: Combustion chamber 30: Intake passage 32: Throttle valve 33: Airflow sensor 34: Throttle opening sensor 45: Fuel injector 46: Fuel tank 50: Notification device 60: Control device 61: Control unit 62: Estimation unit 63: Judgment unit

Claims

1. a fuel injector that injects gaseous fuel, a throttle valve that adjusts the intake air amount flowing into the internal combustion engine, an air flow sensor that detects the intake air amount flowing into the internal combustion engine, and a control device for the internal combustion engine comprising: the control device includes: control means for controlling the opening degree of the throttle valve, estimation means for estimating the intake air amount flowing into the internal combustion engine based on the opening degree of the throttle valve, determination means for determining that the fuel remaining amount is decreasing when the difference between the intake air amount detected by the air flow sensor during driving of the internal combustion engine and the intake air amount estimated by the estimation means is equal to or greater than a predetermined value; A control device for an internal combustion engine, characterized by comprising the above.

2. The estimation means: The control device for an internal combustion engine according to claim 1, characterized in that it determines whether the fuel remaining amount is decreasing during steady operation of the internal combustion engine.

Images