JP2020067053A - Control device of internal combustion engine - Google Patents

Abstract

To suppress the generation of exhaust emission at a start of an internal combustion engine by promoting the vaporization of fuel by using an existing device.SOLUTION: A control device of an internal combustion engine 1 is employed to the internal combustion engine 1 having an exhaust valve stop mechanism 29 which can stop an operation while maintaining an exhaust valve 28 in a closed state even if a crankshaft is rotated, and a fuel injection valve 25 which can inject fuel to an intake port 23, and comprises a motor 13 which can rotate the crankshaft. At a start of the internal combustion engine 1, the control device performs control for injecting the fuel from the fuel injection valve 25 in a state that the crankshaft is rotated while closing and stopping the exhaust valve 28, after that, opening and closing an intake valve 27 while rotating the crankshaft while maintaining the exhaust valve 28 in the closed state, and starting combustion in a combustion chamber 22, and an opening/closing operation of the exhaust valve 28 after a fuel concentration of the combustion chamber 22 reaches a prescribed value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to control of operations of an exhaust valve and a fuel injection valve at the time of starting the internal combustion engine.

  When the temperature of the internal combustion engine is low, a part of the injected fuel may not be vaporized, and the fuel may adhere to the wall of the intake port or the combustion chamber without being evaporated. Then, the emission of unburned hydrocarbons and particulate matter increases in the exhaust gas. Therefore, a mechanism has been proposed in which an auxiliary intake passage provided with a heating means is provided in parallel with the main intake passage to heat the internal intake engine in the auxiliary intake passage when the internal combustion engine is at a low temperature to promote fuel vaporization (see Patent Document 1). Further, a fuel supply device has been proposed in which liquid fuel is injected into a vaporization chamber to be vaporized, and the vaporized fuel is supplied to an internal combustion engine (see Patent Document 2). Further, there is proposed an intake device for an internal combustion engine that promotes fuel vaporization by providing a large number of spherical embosses on the wall surface of an intake port downstream of the fuel injection valve to increase the surface area (see Patent Document 3). ).

JP-A-7-139455 JP, 2011-163316, A JP, 2007-332823, A

  However, if the auxiliary intake passage provided with the heating means and the fuel vaporization chamber are provided in order to promote the vaporization of the fuel, the manufacturing cost increases. Further, it is not easy to manufacture that the intake port is provided with a special shape as shown in Patent Document 3.

  Therefore, an object of the present invention is to promote vaporization of fuel by using an existing device as much as possible to suppress generation of emission at the time of starting the internal combustion engine.

  The control device for an internal combustion engine according to the present invention includes an exhaust valve stop means that can stop the operation with the exhaust valve closed even when the crankshaft rotates, and a fuel supply that can inject fuel to at least one of the intake port and the combustion chamber. A control device for an internal combustion engine, which is applied to an internal combustion engine including: an external power that can rotate a crankshaft; and an external power control means that controls the external power. After injecting fuel from the fuel supply means with the crankshaft rotating with the valve closed and stopped, open the intake valve while rotating the crankshaft with the exhaust valve closed to open the fuel concentration in the combustion chamber. Is controlled to start the combustion in the combustion chamber and the opening / closing operation of the exhaust valve after reaching a predetermined value.

  As described above, at the time of starting the internal combustion engine, by opening and closing the intake valve while rotating the crankshaft with the exhaust valve closed after injecting fuel from the fuel supply means, it is possible to increase the temperature of the air-fuel mixture due to compression in the combustion chamber. By the flow of the air-fuel mixture reciprocating between the intake port and the fuel chamber, the vaporization of the fuel adhering to the wall surfaces of the combustion chamber and the intake port is promoted, and the emission can be suppressed.

  In one aspect of the control device for an internal combustion engine of the present invention, the control may be performed when the internal combustion engine is started during cold when the temperature of the internal combustion engine is equal to or lower than a predetermined temperature.

  According to this aspect, the vaporization of the fuel adhering to the walls of the combustion chamber and the intake port at the time of cold start is promoted, and the generation of emissions can be suppressed.

  In one mode of the control device for an internal combustion engine of the present invention, fuel injection may be performed in multiple times while the crankshaft is rotating while the exhaust valve is closed and stopped.

  According to this aspect, the amount of fuel injected at one time is small, so that the amount of fuel adhering to the wall surface is small and the vaporization of the fuel is facilitated. Further, since the fuel is injected again after the vaporization has progressed to some extent, the vaporization is promoted more than in the case where the same amount is injected at one time, and the fuel adhesion to the wall surface can be suppressed. Therefore, it is possible to suppress the generation of emissions at the time of starting the internal combustion engine.

  According to the present invention, if the exhaust valve stop means that can stop the operation while the exhaust valve is closed even if the crankshaft is rotated is provided, the existing device is used to promote the vaporization of the fuel and the emission at the time of starting the internal combustion engine. Can be suppressed.

FIG. 1 is a diagram showing a control device for an internal combustion engine according to an embodiment of the present invention. FIG. 1 is a sectional view taken along a plane along a center line of a cylinder of an internal combustion engine to which a control device according to an embodiment of the present invention is applied. 3 is a flowchart showing an example of a control routine executed by the ECU in the first embodiment. FIG. 1 is a side view showing a combustion chamber of an internal combustion engine to which the control device according to the first embodiment is applied. 8 is a flowchart showing a control routine executed by the ECU in the second embodiment. 8 is a flowchart showing a control routine executed by the ECU in the third embodiment.

<First form>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The internal combustion engine 1 shown in FIG. 1 is mounted on a vehicle (not shown) as a driving power source. The internal combustion engine 1 is configured as an in-line 4-cylinder type internal combustion engine in which four cylinders 2 are arranged in one direction. An intake passage 30 and an exhaust passage 40 are connected to each cylinder 2.

  The intake passage 30 includes an air cleaner 31 and a throttle valve 32. The internal combustion engine 1 distributes the intake air filtered by the air cleaner 31 to each cylinder 2 via the throttle valve 32 and fills each cylinder 2 with the intake air. The throttle valve 32 can adjust the flow rate of intake air flowing through the intake passage 30. The exhaust passage 40 includes an exhaust catalyst 41. Exhaust gas discharged from each cylinder 2 is discharged to the atmosphere after purification of harmful substances by the exhaust catalyst 41.

  As shown in FIG. 2, the internal combustion engine 1 includes a cylinder block 11 in which each cylinder 2 is formed, and a cylinder head 12 that closes an opening of each cylinder 2. By inserting the piston 21 into each cylinder 2, a combustion chamber 22 is formed between the piston 21 of each cylinder 2 and the cylinder head 12. An intake port 23 and an exhaust port 24, which open toward the combustion chamber 22 for each cylinder 2, are formed in the cylinder head 12. The intake port 23 constitutes a part of the intake passage 30, and the exhaust port 24 constitutes a part of the exhaust passage 40. The cylinder head 12 is provided with a fuel injection valve 25 as a fuel supply means for injecting fuel into the intake port 23. The cylinder head 12 is provided with an ignition plug 26 that ignites a mixture of fuel and intake air in the combustion chamber 22. The intake port 23 is provided with an intake valve 27, and the exhaust port 24 is provided with an exhaust valve 28.

  As shown in FIG. 1, the internal combustion engine 1 can stop the operation of the exhaust valve 28 while keeping the exhaust valve 28 closed even if the piston 21 is reciprocated in the cylinder 2 by rotating a crankshaft (not shown). An exhaust valve stop mechanism 29 is provided as a means. A motor 13 is provided as an external power source capable of rotating the crankshaft. The internal combustion engine 1 includes a cooling water temperature sensor 14 that measures the temperature of the cooling water of the internal combustion engine 1.

  Control of each part of the internal combustion engine 1 is controlled by an engine control unit (ECU) 50 configured as a computer. The ECU 50 has a CPU that is an arithmetic processing unit and a storage unit such as a RAM or a ROM. The CPU has a function of executing a program stored in the storage unit in advance. The ECU 50 performs various controls on the fuel injection valve 25, the spark plug 26, the throttle valve 32, the exhaust valve stop mechanism 29, and the like. The ECU 50 also controls the motor 13 as an external power control means. The output signal of the cooling water temperature sensor 14 and the like are input to the ECU 50.

  FIG. 3 is a flowchart showing an example of a control routine executed by the ECU 50. The program of the control routine of FIG. 3 is held in the ECU 50, and is read and executed when the internal combustion engine 1 is started.

  In this control routine, when there is a request to start the internal combustion engine 1 in step S1, the ECU 50 starts motoring to rotate the crankshaft using the motor 13 in step S2. Next, in step S3, the ECU 50 adjusts the opening degree of the throttle valve 32. Next, in step S4, the ECU 50 causes the exhaust valve stop mechanism 29 to stop with the exhaust valve 28 closed. Next, in step S5, the ECU 50 causes the fuel injection valve 25 to inject fuel.

  After that, the motoring is continued with the exhaust valve 28 closed, and after the fuel concentration in the combustion chamber 22 reaches a predetermined value, the ECU 50 performs the combustion in the combustion chamber 22 and the opening / closing operation of the exhaust valve 28 in step S6. Then, the combustion operation is started. The combustion in the combustion chamber 22 is performed using the spark plug 26.

  In step S6, the determination that the fuel concentration in the combustion chamber 22 has reached the predetermined value is made by conducting an experiment, numerical calculation, etc. in advance from the fuel injection in step S5 until the fuel concentration in the combustion chamber 22 reaches the predetermined value. Is obtained and stored in the ROM of the ECU 50, and the time is elapsed after the fuel injection. In addition, if the intake port 23 is provided with an air-fuel ratio measuring device, the air-fuel ratio measuring device may measure the fuel concentration for determination. Further, by providing a temperature sensor in the intake port 23, the relationship between the temperature of the intake port 23 and the time from the start of motoring in step S2 to the time when the fuel concentration in the combustion chamber 22 reaches a predetermined value is experimentally or It may be determined by numerical calculation or the like and stored in the ROM of the ECU 50, the temperature of the intake port 23 before the start of motoring may be measured, and it may be determined that the time corresponding to the temperature has elapsed from the start of motoring.

  FIG. 4 shows a state in the combustion chamber 22 from the execution of fuel injection in step S5 to the start of combustion operation in step S6 during the intake stroke. FIG. 4 shows an example in which fuel is injected from the fuel injection valve 25 during the intake stroke.

  First, as shown in FIG. 4A, when the fuel is injected by the fuel injection valve 25 in the intake stroke in step S5, the injected fuel rides on the flow of intake air and a part thereof is vaporized into the combustion chamber 22. Although it flows in, part of it adheres to the intake port 23 and the inner wall of the combustion chamber 22 in a non-evaporated state.

  Next, in the compression stroke shown in FIG. 4B, the gas in the combustion chamber 22 is compressed and the temperature rises, and the vaporization of the unvaporized fuel that has adhered is promoted. Here, combustion by ignition is not performed, and the gas in the combustion chamber 22 expands in the expansion stroke shown in FIG. 4 (c). Next, in the process shown in FIG. 4D, the intake valve 27 and the exhaust valve 28 are both closed, so the gas in the combustion chamber 22 is compressed again. After that, as shown in FIG. 4E, the intake valve 27 is opened, and the gas compressed in the combustion chamber 22 flows to the intake port 23, so that the flow promotes vaporization of the fuel adhering to the intake port 23. It After that, in the intake stroke shown in FIG. 4 (f), gas flows from the intake port 23 into the combustion chamber 22, and the flow promotes vaporization of the fuel adhering to the wall surface. After that, in the compression stroke shown in FIG. 4 (g), the gas in the combustion chamber 22 is compressed and the temperature rises, and the vaporization of the attached non-evaporated fuel is promoted.

  Thereafter, the steps shown in FIGS. 4C to 4G are repeated until the ECU 50 determines that the fuel concentration in the combustion chamber 22 has reached the predetermined value. The vaporization of the fuel adhering to the wall surface is promoted to reduce the adhering amount.

  When the ECU 50 determines that the fuel concentration in the combustion chamber 22 has reached the predetermined value, the process proceeds to step S6, the combustion in the combustion chamber 22 and the opening / closing operation of the exhaust valve 28 are started, and the combustion operation is started. . Therefore, as shown in FIG. 4 (h), ignition is performed by the ignition plug 26 in the latter stage of the compression stroke, and the exhaust valve 28 is opened in the exhaust process shown in FIG. 4 (i) to burn the combusted gas from the combustion chamber 22 to the exhaust port. Exhaust to 24.

  Through the series of steps from FIG. 4 (a) to FIG. 4 (i) described above, the combustion operation is started after reducing the amount of fuel adhered to the intake port 23 and the wall surface of the combustion chamber 22, so that the internal combustion engine 1 is started. It is possible to suppress the occurrence of time-related emissions. Although the fuel injection valve 25 injects the fuel in the intake stroke in FIG. 4 as shown in FIG. 4A, the fuel may be injected in other times than the intake stroke. When the fuel is injected at a timing other than during the intake stroke, the fuel injected in step S5 is not directly introduced into the combustion chamber 22 but adheres to the intake port 23 and the intake valve 27. By repeating the steps shown up to 4 (g), the vaporization of the attached fuel is promoted.

<Second form>
Next, the second embodiment of the present invention will be described. This form has the same configuration as the first form except that the control routine controlled by the ECU 50 is different.

  FIG. 5 is a flowchart showing a control routine executed by the ECU 50. The program of the control routine of FIG. 5 is stored in the ECU 50, and is read and executed when the internal combustion engine 1 is started.

  In this control routine, when there is a request to start the internal combustion engine 1 in step S11, the ECU 50 determines in step S12 whether it is cold. The ECU 50 determines that it is cold when the temperature of the cooling water of the internal combustion engine 1 measured by the cooling water temperature sensor 14 is equal to or lower than the threshold value. The determination as to whether it is cold may be made based on the elapsed time after the internal combustion engine 1 is stopped.

  If it is cold, control from step S13 to step S17 is performed. The control from step S13 to step S17 is exactly the same as the control from step S2 to S6 in FIG.

  If it is not cold, the ECU 50 starts motoring using the motor 13 to rotate the crankshaft in step S21. Next, in step S22, the ECU 50 adjusts the opening degree of the throttle valve 32. Then, the ECU 50 causes the fuel injection valve 25 to inject fuel in step S23, and starts the combustion operation in step S24. If it is not cold, even if the fuel injection valve 25 injects fuel at the time of starting the internal combustion engine 1, the fuel is easily vaporized, and unvaporized fuel does not adhere to the wall surfaces of the intake port 23 and the combustion chamber 22. Since the number is small, the stroke shown in FIG. 4 (c) to FIG. 4 (g) is not performed, and the injection combustion operation of step S24 is started.

  By executing the program of the control routine of FIG. 5, when the engine is not cold, the injection combustion operation can be started immediately after the fuel injection is started when the internal combustion engine 1 is started, while the combustion chamber 22 and the intake air are started at the cold start. The vaporization of the fuel adhering to the wall surface of the port 23 is promoted, and the emission can be suppressed.

<Third form>
Next, a third mode of the present invention will be described. This form has the same configuration as the first form except that the control routine controlled by the ECU 50 is different.

  FIG. 6 is a flowchart showing an example of a control routine executed by the ECU 50. The program of the control routine of FIG. 6 is held in the ECU 50, and is read and executed when the internal combustion engine 1 is started.

  In this control routine, when there is a request to start the internal combustion engine 1 in step S31, the ECU 50 starts motoring to rotate the crankshaft using the motor 13 in step S32. Next, in step S33, the ECU 50 adjusts the opening degree of the throttle valve 32. Next, in step S34, the ECU 50 causes the exhaust valve stop mechanism 29 to stop with the exhaust valve 28 closed. The control from step S31 to step S34 is exactly the same as the control from step S1 to S4 in FIG.

  Next, in step S35, the ECU 50 causes the fuel injection valve 25 to inject the fuel several times. For example, when the fuel injection is divided into three injections, the first fuel injection is performed in the intake stroke of FIG. 4 (a), and the strokes shown in FIGS. 4 (c) to 4 (g) are repeated. Then, the second fuel injection is performed in the first intake stroke of FIG. 4 (f), and the third fuel injection is performed in the second intake stroke of FIG. 4 (f). By injecting the fuel in several times in this way, the amount of fuel injected at one time is reduced, and the amount of fuel adhering to the wall surfaces of the intake port 23 and the combustion chamber 22 is reduced. Therefore, the evaporation of fuel becomes easy to proceed. By injecting again after evaporating to some extent, vaporization is promoted more than in the case of injecting the same amount at one time, and the adhesion of fuel to the wall surface can be suppressed.

  After that, the motoring is continued with the exhaust valve 28 closed, and when the ECU 50 determines that the fuel concentration in the combustion chamber 22 has reached the predetermined value, the ECU 50 causes the combustion and exhaust valve 28 in the combustion chamber 22 to proceed in step S36. The opening / closing operation of is started and the combustion operation is started. The combustion in the combustion chamber 22 is performed using the spark plug 26.

  By executing the program of the control routine of FIG. 6, the fuel is injected in several times in step S5, and the adhesion of the fuel to the wall surface is further reduced as compared with the first mode, so that the generation of emissions is suppressed. You can Although it is described here that the fuel is injected during the intake stroke, the third embodiment may also inject fuel other than during the intake stroke, as in the first embodiment.

<Supplement to Embodiment>
The control device for an internal combustion engine according to the present disclosure is not limited to the above-described form, and can be implemented in various forms within the scope of the gist of the present disclosure. In each of the above-described embodiments, the invention is applied to a four-cylinder internal combustion engine, but it can be applied regardless of the number of cylinders. Further, in each of the above-described embodiments, the fuel injection valve 25 is applied to the internal combustion engine provided in the intake port 23. However, the direct injection type internal combustion engine or the fuel injection valve 25 in both the intake port 23 and the combustion chamber 22 is used. It can also be applied to an internal combustion engine provided with. Further, in each of the above-described embodiments, the opening degree of the throttle valve 32 is adjusted after starting the motoring, but the opening degree of the throttle valve 32 may be adjusted before starting the motoring.

1 internal combustion engine, 2 cylinders, 11 cylinder block, 12 cylinder head, 13 motor, 14 cooling water temperature sensor, 21 piston, 22 combustion chamber, 23 intake port, 24 exhaust port, 25 fuel injection valve, 26 spark plug, 27 intake Valve, 28 exhaust valve, 29 exhaust valve stop mechanism, 30 intake passage, 31 air cleaner, 32 throttle valve, 40 exhaust passage, 41 exhaust catalyst, 50 ECU.

Claims (3)

The present invention is applied to an internal combustion engine provided with an exhaust valve stop means capable of stopping the operation with the exhaust valve closed even when the crankshaft is rotated, and a fuel supply means capable of injecting fuel into at least one of the intake port and the combustion chamber,
A control device for an internal combustion engine, comprising: external power capable of rotating the crankshaft; and external power control means for controlling the external power,
At the time of starting the internal combustion engine, after the fuel is injected from the fuel supply means while the crankshaft is rotating while the exhaust valve is closed and stopped, the crankshaft is rotated while the exhaust valve is closed. The internal combustion engine is characterized in that the intake valve is opened and closed while the fuel concentration in the combustion chamber reaches a predetermined value, and then control is performed to start combustion in the combustion chamber and opening / closing operation of the exhaust valve. Control device. A control device for an internal combustion engine according to claim 1,
A control device for an internal combustion engine, wherein the control is performed when the internal combustion engine is started during cold when the temperature of the internal combustion engine is equal to or lower than a predetermined temperature. A control device for an internal combustion engine according to claim 1 or 2, wherein
A control device for an internal combustion engine, wherein fuel injection is performed in a plurality of times while the crankshaft is rotating while the exhaust valve is closed and stopped.

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