Control device for internal combustion engines

Abstract

To provide a control device for an internal combustion engine that can suppress the recurrence of abnormal combustion after it has occurred. [Solution] The engine 2 has a plurality of cylinders 11, each cylinder 11 having an intake valve 15 that opens and closes an intake port 13 used to supply air to a combustion chamber 12, an exhaust valve 16 that opens and closes an exhaust port 14 used to discharge exhaust gas from the combustion chamber 12, and an injector 19 that injects fuel into the combustion chamber 12. The ECU 3 stops fuel injection to any cylinder 11 in the next combustion cycle if abnormal combustion occurs in that cylinder 11.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes an internal combustion engine that uses hydrogen gas in addition to gasoline as fuel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since hydrogen fuel has a lower ignition energy compared to gasoline fuel and the like, there is a high possibility of causing so-called pre-ignition that self-ignites using a heat source such as an ignition plug or an exhaust valve. If pre-ignition occurs continuously, it may affect the operation of the internal combustion engine.

[0005] Therefore, an object of the present invention is to provide a control device for an internal combustion engine that can suppress the recurrence of abnormal combustion after abnormal combustion has occurred.

Means for Solving the Problems

[0006] To solve the above problems, the present invention is a control device for an internal combustion engine having a plurality of cylinders and burning fuel injected from an injector in each cylinder, and includes a control unit that stops fuel injection in the cylinder in the next combustion cycle when abnormal combustion occurs in any cylinder.

Effects of the Invention

[0007] Thus, according to the present invention, it is possible to suppress the recurrence of abnormal combustion after it has occurred. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram of a vehicle equipped with a control device for an internal combustion engine according to one embodiment of the present invention. [Figure 2] Figure 2 is a timing diagram showing an example of control during abnormal combustion in an internal combustion engine control device according to one embodiment of the present invention. [Figure 3] Figure 3 is a flowchart showing the procedure for abnormal combustion handling processing of an internal combustion engine control device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] A control device for an internal combustion engine according to one embodiment of the present invention is a control device for an internal combustion engine having a plurality of cylinders and burning fuel injected from an injector in each cylinder, and is configured to include a control unit that stops fuel injection in the next combustion cycle if abnormal combustion occurs in any of the cylinders.

[0010] As a result, the control device for an internal combustion engine according to one embodiment of the present invention can suppress the recurrence of abnormal combustion after it has occurred. [Examples]

[0011] Hereinafter, with reference to the drawings, a control device for an internal combustion engine according to an embodiment of the present invention will be described in detail.

[0012] In Figure 1, a vehicle 1 equipped with a control device for an internal combustion engine according to one embodiment of the present invention is configured to include an internal combustion engine 2 and an ECU (Electronic Control Unit) 3 as a control unit.

[0013] Engine 2 has multiple cylinders 11, and Figure 1 schematically shows a cross-section of one of the multiple cylinders 11 in engine 2. In this embodiment, each cylinder 11 includes a cylinder body 11a used to define its combustion chamber 12, and components attached to the cylinder body 11a, as described later. In describing this embodiment, it is assumed that engine 2 has three cylinders 11. However, engine 2 is not limited to this and may have two or four or more cylinders 11.

[0014] Each cylinder 11 has an intake port 13 used to supply air to its combustion chamber 12 and an exhaust port 14 used to discharge exhaust gas from its combustion chamber 12. Each cylinder 11 also has an intake valve 15 configured to open and close its intake port 13 and an exhaust valve 16 configured to open and close its exhaust port 14. Each cylinder 11 has an intake valve variable mechanism 17 configured to control the opening and closing of the intake valve 15 and an exhaust valve variable mechanism 18 configured to control the opening and closing of the exhaust valve 16.

[0015] Each cylinder 11 has an injector 19 configured as a fuel injection mechanism capable of supplying hydrogen as fuel to its combustion chamber 12. The injector 19 is configured to inject fuel at the intake port 13. The fuel injected from the injector 19 is supplied to the combustion chamber 12 from the intake port 13 when the intake valve 15 is open at the intake port 13. Each cylinder 11 also has a spark plug 20 capable of performing ignition based on a spark discharge in its combustion chamber 12. The spark plug 20 induces a spark discharge between its center electrode and ground electrode upon application of an induced voltage generated by the ignition coil 21. The ignition coil 21 is equipped with a detection circuit for detecting ion current. The detected ion current is output to the ECU 3.

[0016] Engine 2 has a cylinder block 23 that defines the liner walls 22 of a plurality of cylinders 11. Each cylinder 11 has a piston 24 configured to reciprocate in its axial direction. Each cylinder 11 has a cylinder head 25 located on its top side. The combustion chamber 12 of each cylinder 11 is enclosed by its liner wall 22, piston 24 and cylinder head 25. In each cylinder 11, the intake port 13 and exhaust port 14 are connected to the cylinder head 25, and the spark plug 20 is mounted on the cylinder head 25.

[0017] Engine 2 has a crankcase 26 positioned on the bottom side of the cylinders 11 relative to the cylinder block 23, and a crankshaft 27 positioned within the crankcase 26. The piston 24 in each cylinder 11 is connected to the crankshaft 27 via a connecting rod 28. The reciprocating motion of the piston 24 in each cylinder 11 is converted into rotational motion of the crankshaft 27. Furthermore, a throttle valve 29 is provided upstream of the intake port 13 in the airflow. The throttle valve 29 is configured to allow adjustment of the airflow rate supplied from the intake port 13 to the combustion chamber 12.

[0018] In a single combustion cycle of a four-stroke engine 2, the intake stroke, compression stroke, combustion stroke, and exhaust stroke typically occur in that order. In one combustion cycle, the crankshaft 27 rotates twice. Therefore, in one combustion cycle, the crank angle changes by a total of 720°, and in each of the intake stroke, compression stroke, combustion stroke, and exhaust stroke, the crank angle changes by a total of 180°.

[0019] The ECU3 consists of a computer unit equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory, input ports, and output ports.

[0020] In the ROM of this computer unit, a program for making the computer unit function as ECU3 is stored together with various control constants, various maps, etc. That is, by the CPU executing the program stored in the ROM, the computer unit functions as ECU3.

[0021] In addition to the aforementioned ignition coil 21, various sensors such as a water temperature sensor 32, a vehicle speed sensor 33, a crank angle sensor 34, an accelerator opening sensor 35, and a combustion pressure sensor 36 are connected to the input port of ECU3.

[0022] The water temperature sensor 32 detects the temperature of the cooling water of the engine 2. The water temperature sensor 32 is attached, for example, to a water jacket (not shown) provided in the cylinder head 25.

[0023] The vehicle speed sensor 33 detects the vehicle speed of the vehicle 1. The crank angle sensor 34 detects the angle of the crank angle of the crankshaft 27. ECU3 detects the rotational speed of the crankshaft 27, that is, the engine rotational speed which is the rotational speed of the engine 2, from the crank angle detected by the crank angle sensor 34.

[0024] The accelerator opening sensor 35 detects the accelerator opening which represents the operation amount of the accelerator pedal 31 operated by the driver.

[0025] The combustion pressure sensor 36 detects the pressure in the combustion chamber 12. ECU3 detects the pressure fluctuation during combustion of the engine 2 by the combustion pressure sensor 36.

[0026] On the other hand, various controlled objects such as an intake valve variable mechanism 17, an exhaust valve variable mechanism 18, an injector 19, an ignition coil 21, and a throttle valve 29 are connected to the output port of ECU3.

[0027] The ECU 3 calculates the required load for the engine 2 based on the accelerator opening detected by the accelerator opening sensor 35, and calculates the target ignition timing, fuel injection amount, and intake air amount for the engine 2 according to that required load. The ECU 3 then controls the ignition coil 21, injector 19, and throttle valve 29 to achieve the calculated target ignition timing, fuel injection amount, and intake air amount, thereby controlling the operating state of the engine 2.

[0028] In this embodiment, if abnormal combustion occurs in any of the cylinders 11, the ECU 3 stops fuel injection in the cylinder 11 where the abnormal combustion occurred during the next combustion cycle.

[0029] Abnormal combustion refers to phenomena such as pre-ignition and knocking, and is detected based on factors such as the ion current detected by the ignition coil 21, the crank angle detected by the crank angle sensor 34, and the pressure in the combustion chamber 12 detected by the combustion pressure sensor 36.

[0030] When detected by the ignition coil 21, the ECU 3 determines an abnormal condition based on the combustion timing indicated by the increase in ion current. When detected by the crank angle sensor 34, the ECU 3 determines an abnormal condition based on the angular velocity and angular acceleration during normal operation. When detected by the combustion pressure sensor 36, the ECU 3 determines an abnormal condition based on dp / dθ (rate of pressure increase per unit time).

[0031] If abnormal combustion occurs in any of the cylinders 11 of the multiple cylinders 11, the ECU 3 will stop fuel injection in the cylinder 11 where the abnormal combustion occurred in the next combustion cycle, and will also completely close the intake valve 15 and the exhaust valve 16.

[0032] As shown in Figure 2, during normal operation shown in the upper part of the figure, the intake valve 15 opens during the intake stroke and the exhaust valve 16 opens during the exhaust stroke.

[0033] In the lower part of the diagram, when abnormal combustion occurs, if abnormal combustion is detected at times T1, T2, and T3, the intake valve 15 is closed during the intake stroke at time T4 of the next combustion cycle, and the exhaust valve 16 is closed at time T5.

[0034] The abnormal combustion countermeasures performed by the control device for the internal combustion engine according to this embodiment, configured as described above, will be explained with reference to Figure 3. The abnormal combustion countermeasures described below are started when the ECU3 starts operating and are executed at predetermined time intervals.

[0035] In step S1, the ECU3 determines whether abnormal combustion is occurring in each cylinder 11, and if abnormal combustion is occurring, it turns on the abnormal combustion determination flag corresponding to the cylinder 11 where abnormal combustion is occurring. After executing the process in step S1, the ECU3 executes the process in step S2.

[0036] In step S2, the ECU3 determines whether or not there is a cylinder 11 with an abnormal combustion detection flag turned on.

[0037] If the ECU 3 determines that there is a cylinder 11 with the abnormal combustion detection flag turned on, it executes the process in step S3. If the ECU 3 determines that there is no cylinder 11 with the abnormal combustion detection flag turned on, it terminates the abnormal combustion handling process.

[0038] In step S3, the ECU3 performs cylinder deactivation control, stopping fuel injection in the cylinder 11 where the abnormal combustion occurred and closing the intake valve 15 and exhaust valve 16 completely in the combustion cycle following the abnormal combustion. After performing the process in step S3, the ECU3 terminates the abnormal combustion countermeasures process.

[0039] Thus, in this embodiment, if abnormal combustion occurs in any of the cylinders 11, the ECU 3 stops fuel injection in the cylinder 11 where the abnormal combustion occurred in the next combustion cycle.

[0040] This stops fuel injection to cylinder 11 where abnormal combustion occurred, thereby halting operation, cooling the inside of the cylinder, and preventing the recurrence of abnormal combustion.

[0041] Furthermore, if abnormal combustion occurs in any of the cylinders 11, the ECU 3 will stop fuel injection in the cylinder 11 where the abnormal combustion occurred in the next combustion cycle, and will also completely close the intake valve 15 and the exhaust valve 16.

[0042] As a result, by completely closing the intake valve 15 and the exhaust valve 16, adiabatic expansion occurs during the intake and combustion strokes of the combustion cycle, enabling more effective cooling of the inside of the cylinder.

[0043] Furthermore, by completely closing the intake valve 15 and the exhaust valve 16, it is possible to prevent excess oxygen from entering the exhaust pipe and catalyst.

[0044] Furthermore, it can suppress the temperature rise caused by high-temperature exhaust gas flowing back into the cylinder, and the recurrence of abnormal combustion that results from this.

[0045] Furthermore, Engine 2 can operate using hydrogen as fuel. This makes it possible to suppress repeated occurrences of abnormal combustion, even when using hydrogen, which has low ignition energy, as fuel.

[0046] In this embodiment, we have shown the use of hydrogen as the fuel for engine 2, but it is possible to control it similarly with other fuels as well.

[0047] In this embodiment, an example has been described in which the ECU3 performs various judgments and calculations based on various sensor information. However, the embodiment is not limited to this, and the vehicle 1 may be equipped with a communication unit capable of communicating with an external device such as an external server, and various judgments and calculations may be performed by the external device based on detection information from various sensors transmitted from the communication unit, and the judgment and calculation results may be received by the communication unit and used to perform various controls.

[0048] While embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that modifications can be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims. [Explanation of Symbols]

[0049] 1 vehicle 2 engines 3 ECU (control unit) 11 cylinders 11a Cylinder body 12 Combustion chamber 15 Intake valve 16 Exhaust valve 17. Variable intake valve mechanism 18. Exhaust valve variable movement mechanism 19 Injectors 20 Spark plugs 21 Ignition Coil 31 Accelerator pedal 34 Crank angle sensor 36. Combustion pressure sensor

Claims

1. A control device for an internal combustion engine having multiple cylinders, which burns fuel injected from an injector in each cylinder, A control device for an internal combustion engine, comprising a control unit that stops fuel injection in any cylinder in the next combustion cycle if abnormal combustion occurs in that cylinder.

2. The control device for an internal combustion engine according to claim 1, wherein, if abnormal combustion occurs in any cylinder, the control unit stops fuel injection in that cylinder in the next combustion cycle, and also completely closes the intake valve and the exhaust valve.

3. The control device for the internal combustion engine according to claim 1 or claim 2, wherein the internal combustion engine is capable of operating with hydrogen as fuel.

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