JP3603597B2 - Internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal combustion engine that performs fuel injection at least in an intake stroke and a compression stroke, and is intended to improve the responsiveness of feedback control of rotational speed.
[0002]
[Prior art]
In a general four-cycle internal combustion engine (MPI engine) in which fuel is injected into an intake pipe and mixed with intake air to introduce an air-fuel mixture into a combustion chamber, feedback control of the rotational speed during idle operation is performed. The intake air amount is changed so that the actual rotation speed becomes a preset target rotation speed (idle speed control: ISC).
[0003]
In the conventional ISC control, when an external load such as an air conditioner or power steering is turned on, the ISC valve is opened to increase the amount of intake air and increase the rotation speed. At this time, there is a time difference between the operation state of the ISC valve and the actual increase state of the intake air amount, and the intake air amount is not immediately increased. Therefore, when feedback control of the rotation speed is continued, a predetermined amount of the intake air amount is introduced. The feedback control is performed in a state where the actual rotational speed does not increase in spite of the obtained state, resulting in over-control. Therefore, until the intake air amount is stabilized after a predetermined period has elapsed since the opening of the ISC valve, feedback control of the rotation speed is prohibited to prevent overcontrol.
[0004]
In recent years, in order to reduce harmful exhaust gas components and improve fuel efficiency, various multi-cylinder in-cylinder injection engines that inject fuel directly into the combustion chamber have been proposed instead of the intake pipe injection engine that injects fuel into the intake pipe. Have been. The multi-cylinder in-cylinder injection engine operates in an intake stroke injection mode (intake lean mode) in which fuel injection is mainly performed in the intake stroke, and a compression stroke injection mode (compression lean mode) in which fuel injection is mainly performed in the compression stroke. It can be switched according to the state. Further, during idle operation, feedback control of the rotation speed is performed so that the actual rotation speed becomes the target rotation speed set in advance.
[0005]
In the above-described multi-cylinder in-cylinder injection engine, in the compression lean mode, the combustible air-fuel ratio is wide, and the rotation speed is easily changed by changing the air-fuel ratio. Therefore, the rotation speed is feedback-controlled by changing the air-fuel ratio. ing. In the intake stroke injection mode, since the combustible air-fuel ratio is set in a narrow range near stoichio, it is difficult to change (increase) the rotation speed by changing the air-fuel ratio. Therefore, by changing the intake air amount similarly to the MPI engine, The feedback control of the rotation speed is performed.
[0006]
When an external load such as an air conditioner or power steering is turned on, the air-fuel ratio is changed to increase the rotation speed in the compression lean mode, and the intake air amount is changed to change the rotation speed in the intake stroke injection mode. I try to raise it. In this case, after the rotation speed is controlled to be increased, feedback control of the rotation speed is prohibited until the rotation speed is stabilized after a predetermined time has elapsed, thereby preventing overcontrol.
[0007]
[Problems to be solved by the invention]
In the above-described multi-cylinder in-cylinder injection engine, the predetermined period during which the feedback control of the rotational speed is prohibited is set to be the same in the compression lean mode and the intake stroke injection mode. However, when the rotation speed is increased in the compression lean mode, the response of the rotation speed is good because the fuel amount is changed, and the period is shorter than that in the intake stroke injection mode in which the rotation speed is increased by changing the intake air amount. And the rotation speed is stabilized. For this reason, in the compression lean mode, the period in which the feedback control is prohibited is long, and a useless prohibition period is set.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an internal combustion engine that can improve the responsiveness of feedback control of the rotation speed when the rotation speed is changed when an external load is applied. .
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the configuration of the present invention changes the intake air amount during the intake stroke while changing at least the fuel amount during the compression stroke so that the actual rotational speed of the engine becomes the preset target rotational speed. Control means for feedback control of the speed is provided, wherein feedback control of the rotational speed is prohibited for a predetermined period when an external load is applied by a prohibition means, and the predetermined period is separately set for an intake stroke and a compression stroke by a setting means. And
[0010]
Specifically, the feedback control prohibition period in the compression lean mode in which the rotation speed is increased by changing the fuel amount when an external load such as an air conditioner is applied is changed to the intake stroke in which the rotation speed is increased by changing the intake amount. The period is set shorter than the prohibition period of the feedback control in the injection mode, thereby ensuring the stability of the feedback control in the intake stroke injection mode and improving the responsiveness of the feedback control in the compression lean mode.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the illustrated embodiment, a multi-cylinder in-cylinder injection internal combustion engine in which fuel is directly injected into a combustion chamber is described as an example of the internal combustion engine. FIG. 1 shows a schematic configuration of a multi-cylinder direct injection internal combustion engine according to an embodiment of the present invention, and FIG. 2 shows a fuel injection control map.
[0012]
The configuration of the multi-cylinder direct injection internal combustion engine will be described with reference to FIG. As the multi-cylinder in-cylinder injection internal combustion engine, for example, an in-cylinder injection in-line four-cylinder gasoline engine (in-cylinder injection engine) 1 that directly injects fuel into a combustion chamber is applied. In the in-cylinder injection engine 1, a combustion chamber, an intake device, an exhaust gas recirculation device (EGR device), and the like are designed exclusively for in-cylinder injection.
[0013]
The cylinder head 2 of the in-cylinder injection engine 1 is provided with an ignition plug 3 for each cylinder and an electromagnetic fuel injection valve 4 as fuel supply means for each cylinder. The injection port of the fuel injection valve 4 is opened in the combustion chamber 5, and the fuel injected from the fuel injection valve 4 via the driver 20 is directly injected into the combustion chamber 5. A piston 7 is supported on the cylinder 6 of the in-cylinder injection engine 1 so as to be slidable in a vertical direction, and a top surface of the piston 7 is formed with a hemispherically concave cavity 8. The cavity 8 generates a reverse tumble flow in the intake flow, which is opposite to a normal tumble flow.
[0014]
An intake port 9 and an exhaust port 10 facing the combustion chamber 5 are formed in the cylinder head 2. The intake port 9 is opened and closed by driving an intake valve 11, and the exhaust port 10 is opened and closed by driving an exhaust valve 12. An intake side camshaft 13 and an exhaust side camshaft 14 are rotatably supported on the upper part of the cylinder head 2. The rotation of the intake side camshaft 13 drives the intake valve 11, and the exhaust side camshaft 14 The rotation drives the exhaust valve 12. A large-diameter exhaust gas recirculation port (EGR port) 15 branches diagonally downward from the exhaust port 10.
[0015]
In the vicinity of the cylinder 6 of the direct injection engine 1, a water temperature sensor 16 for detecting a cooling water temperature is provided. Further, a vane-type crank angle sensor 17 that outputs a crank angle signal SGT at a predetermined crank position (for example, 75 ° BTDC and 5 ° BTDC) of each cylinder is provided, and the crank angle sensor 17 can detect the engine rotation speed. I have. The camshafts 13 and 14 that rotate at half the number of revolutions of the crankshaft are provided with an identification sensor 18 that outputs a cylinder identification signal SGC, and the cylinder identification signal SGC can identify which cylinder the crank angle signal SGT belongs to. It has been. Reference numeral 19 in the drawing denotes an ignition coil for applying a high voltage to the ignition plug 3.
[0016]
An intake pipe 40 is connected to the intake port 9 via an intake manifold 21, and the intake manifold 21 is provided with a surge tank 22. The intake pipe 40 includes an air cleaner 23, a throttle body 24, a first air bypass valve 25 of a stepper motor type, and an air flow sensor 26. The air flow sensor 26 detects the amount of intake air, and for example, a Karman vortex flow sensor is used. Incidentally, a boost pressure sensor may be attached to the surge tank 22, and the intake air amount may be obtained from the intake pipe pressure detected by the boost pressure sensor.
[0017]
The intake pipe 40 is provided with a large-diameter air bypass pipe 27 that bypasses the throttle body 24 and sucks air into the intake manifold 21, and the air bypass pipe 27 is provided with a second air bypass valve 28 of a linear solenoid type. I have. The air bypass pipe 27 has a flow passage area similar to that of the intake pipe 40, and when the second air bypass valve 28 is fully opened, intake of an amount required in the low to medium speed region of the in-cylinder injection engine 1 is possible.
[0018]
The throttle body 24 is provided with a butterfly type throttle valve 29 for opening and closing the flow path, and a throttle position sensor 30 for detecting the opening of the throttle valve 29. A throttle voltage corresponding to the opening of the throttle valve 29 is output from a throttle position sensor 30 that detects the opening of the throttle valve 29, and the opening of the throttle valve 29 is recognized based on the throttle voltage. I have. Further, the throttle body 24 is provided with an idle switch 31 that detects the fully closed state of the throttle valve 29 and recognizes the idling state of the in-cylinder injection engine 1.
[0019]
On the other hand, an exhaust pipe 33 is connected to the exhaust port 10 via an exhaust manifold 32, and an O ₂ sensor 34 is attached to the exhaust manifold 32. The exhaust pipe 33 is provided with a three-way catalyst 35 and a muffler (not shown). The EGR port 15 is connected to the upstream side of the intake manifold 21 via a large-diameter EGR pipe 36, and the EGR pipe 36 is provided with a stepper motor type EGR valve 37.
[0020]
The fuel stored in the fuel tank 41 is sucked up by an electric low-pressure fuel pump 42 and supplied to the in-cylinder injection engine 1 via a low-pressure feed pipe 43. The fuel pressure in the low pressure feed pipe 43 is regulated to a relatively low pressure (low fuel pressure) by a first fuel pressure regulator 45 provided in a return pipe 44. The fuel supplied to the in-cylinder injection engine 1 is supplied to each fuel injection valve 4 by a high-pressure fuel pump 46 via a high-pressure feed pipe 47 and a delivery pipe 48.
[0021]
The high-pressure fuel pump 46 is, for example, a swash plate axial piston type, is driven by the camshaft 14 on the exhaust side or the camshaft 13 on the intake side, and has a discharge pressure higher than a predetermined pressure even during idling operation of the direct injection engine 1. Can be generated. Then, the fuel pressure in the delivery pipe 48 is regulated to a relatively high pressure (high fuel pressure) by the second fuel pressure regulator 50 provided in the return pipe 49.
[0022]
An electromagnetic fuel pressure switching valve 51 is attached to the second fuel pressure regulator 50. When the fuel pressure switching valve 51 is turned on, the fuel is relieved and the fuel pressure in the delivery pipe 48 can be reduced to a low fuel pressure. Reference numeral 52 in the drawing denotes a return pipe for returning a part of the fuel used for lubrication and cooling of the high-pressure fuel pump 46 to the fuel tank 41.
[0023]
The vehicle is provided with an electronic control unit (ECU) 61 as a control device. The ECU 61 includes an input / output device, a storage device for storing a control program, a control map, and the like, a central processing unit, and a timer and counters. Have been. Comprehensive control of the direct injection engine 1 is performed by the ECU 61. The detection information of the various sensors described above is input to the ECU 61. The ECU 61 determines a fuel injection mode, a fuel injection amount, an ignition timing, an introduction amount of EGR gas, and the like based on the detection information of the various sensors. The drive control of the driver 20 of the injection valve 4, the ignition coil 19, the EGR valve 37 and the like is performed.
[0024]
The input side of the ECU 61 is connected to a large number of external load switches (not shown) such as an air conditioner switch 71 in addition to the various sensors described above. Is connected.
[0025]
In the above-described in-cylinder injection engine 1, when the in-cylinder injection engine 1 is in a cold state, when the driver turns on the ignition key, the low-pressure fuel pump 42 and the fuel pressure switching valve 51 are turned on and the fuel injection valve 4 is turned on. Low fuel pressure fuel is supplied. Next, when the driver starts operating the ignition key, the in-cylinder injection engine 1 is cranked by a cell motor (not shown), and at the same time, the fuel injection control by the ECU 61 is started.
[0026]
At this time, the ECU 61 selects the first-stage injection mode (that is, the intake stroke injection mode in which fuel is injected in the intake stroke), and fuel is injected so as to have a relatively rich air-fuel ratio.
[0027]
At the time of such a start, the second air bypass valve 28 is closed to almost the vicinity of the fully closed state. Therefore, the intake air to the combustion chamber 5 is taken through the gap of the throttle valve 29 and the first air bypass valve 25. The first air bypass valve 25 and the second air bypass valve 28 are centrally managed by the ECU 61, and the respective opening amounts are determined according to the required amount of intake air bypassing the throttle valve 29.
[0028]
When the in-cylinder injection engine 1 is thus started and the in-cylinder injection engine 1 starts idling at a predetermined rotational speed, the high-pressure fuel pump 46 starts rated discharge operation, and the ECU 61 controls the fuel pressure switching valve. 51 is turned off, and high-pressure fuel is supplied to the fuel injection valve 4. The required fuel injection amount at this time is obtained from the discharge pressure of the high-pressure fuel pump 46 and the valve opening time of the fuel injection valve 4.
[0029]
Until the cooling water temperature detected by the water temperature sensor 16 rises to a predetermined value, the first injection mode is selected and fuel is injected as in the case of starting. The control of the idle speed according to the increase or decrease of the load on the auxiliary equipment such as the air conditioner is performed by the first air bypass valve 25. When the O ₂ sensor 34 is activated after a predetermined cycle, the air-fuel ratio feedback control is started according to the output voltage of the O ₂ sensor 34. Thereby, the harmful exhaust gas component is favorably purified by the three-way catalyst 35.
[0030]
When the warm-up of the in-cylinder injection engine 1 is completed, the ECU 61 calculates the target output correlation value obtained from the throttle voltage corresponding to the opening degree of the throttle valve 29, for example, based on the target average effective pressure Pet and the engine rotation speed Ne. The current fuel injection area is searched from the fuel injection map of FIG. 2 to determine the fuel injection mode. Thus, the fuel injection amount according to the target air-fuel ratio in each fuel injection mode is determined, and the drive of the fuel injection valve 4 and the drive control of the ignition coil 19 are performed according to the fuel injection amount. At the same time, opening / closing control of the first air bypass valve 25, the second air bypass valve 28, and the EGR valve 37 is also performed.
[0031]
In a low load region such as during idling or low-speed running, the fuel injection region is selected to be in the late injection lean mode in FIG. 2 (that is, the compression lean mode in which fuel is injected in the compression stroke). In this case, the first air bypass valve 25 and the second air bypass valve 28 are controlled, and a target air-fuel ratio corresponding to the target average effective pressure Pet is set based on the throttle voltage and the engine speed Ne so as to obtain a lean air-fuel ratio. Is done. Then, a fuel injection amount is set according to the target air-fuel ratio, and the drive of the fuel injection valve 4 is controlled so as to perform fuel injection according to the fuel injection amount.
[0032]
Further, in a middle load region such as at the time of constant speed running, the fuel injection mode becomes the first-stage injection lean mode or the stoichiometric feedback mode in FIG. 2 according to the load condition and the engine speed. In the first-stage injection lean mode, the first air bypass valve 25 is controlled in the same manner as a normal idle speed control valve, and the target air-fuel ratio is calculated based on the intake air amount signal from the air flow sensor 26 and the engine speed. The fuel injection amount is controlled so as to achieve a lean air-fuel ratio.
[0033]
In the stoichiometric feedback mode, as in the previous injection lean mode, the first air bypass valve 25 is controlled in the same manner as a normal idle speed control valve, and the second air bypass valve 28 is fully closed to prevent an excessive increase in output. preventing further controls the EGR valve 37 substantially fully closed, performs air-fuel ratio feedback control target air-fuel ratio in accordance with the output voltage of the O ₂ sensor 34 so that the theoretical air-fuel ratio, fuel injection amount control Is done.
[0034]
Further, in a high load region such as at the time of sudden acceleration or high speed traveling, the open loop mode in FIG. 2 is set. In this case, the second air bypass valve 28 is closed, and a target air-fuel ratio is set from a map so as to obtain a relatively rich air-fuel ratio, and the fuel injection amount is controlled according to the target air-fuel ratio.
[0035]
In the above-described in-cylinder injection engine 1, feedback control of the rotation speed is performed so that the actual rotation speed during the idling operation in which the idle switch 31 is turned on becomes the preset target rotation speed. In the compression lean mode, the flammable air-fuel ratio is wide and the rotation speed is easily changed by changing the air-fuel ratio.Therefore, changing the air-fuel ratio changes the amount of fuel injected into the engine and the amount of intake air supplied to the engine to reduce the rotation speed. Feedback control is implemented. In the intake stroke injection mode, feedback control of the rotational speed is performed by changing the amount of intake air.
[0036]
Then, when an external load such as the air conditioner switch 71 or the power steering is turned on, in the compression lean mode, the air-fuel ratio is changed by changing at least the fuel injection amount to increase the rotation speed, and in the intake stroke injection mode, The rotational speed is increased by changing the amount of intake air (control means). In this case, after the rotation speed is controlled to be high, feedback control of the rotation speed is prohibited until the rotation speed stabilizes after a predetermined period of time, thereby preventing overcontrol. means). The predetermined period in which the feedback control is prohibited until the rotation speed is stabilized is set separately in the compression lean mode and the intake stroke injection mode (setting means).
[0037]
The situation when the external load is turned on while the above-described in-cylinder injection engine 1 is performing the feedback control of the rotational speed during the idling operation will be described with reference to FIGS. FIG. 3 shows a change over time in the compression lean mode, FIG. 4 shows a change over time in the intake stroke injection mode, and FIGS. 5 and 6 show flowcharts of feedback control of the rotational speed during the idling operation.
[0038]
As shown in FIG. 3, when feedback control of the rotation speed is performed so that the actual rotation speed during idling operation in the compression lean mode becomes the preset target rotation speed, the air conditioner switch 71 that is an external load is controlled. When the power steering switch, light switch, wiper switch, and the like are turned on, the fuel coefficient increases, the fuel amount increases, and the air-fuel ratio changes. At the same time, the feedback control of the rotation speed is prohibited. Further, in response to the increase in the fuel amount, for example, the first air bypass valve 25 is opened to increase the air amount. Thus, the rotation speed during the idling operation in the compression lean mode is increased.
[0039]
By changing the fuel amount and increasing the rotation speed, the rotation speed is stabilized at a predetermined rotation speed in a short time after the fuel amount is increased. The feedback control timer of the rotation speed is operated and the feedback control of the rotation speed is prohibited for a short time t, and the feedback control is restarted after the elapse.
[0040]
In the case of the compression lean mode, since the rotation speed is high and stable with a good response due to the correction by the fuel amount, the feedback control of the rotation speed is prohibited only for a short time t, and the response of the feedback control of the rotation speed is improved. .
[0041]
On the other hand, as shown in FIG. 4, when the feedback control of the rotation speed is performed so that the actual rotation speed during the idling operation in the intake stroke injection mode becomes the preset target rotation speed, the load is an external load. When the air conditioner switch 71 (power steering switch, light switch, wiper switch, etc.) is turned on, for example, the first air bypass valve 25 is opened to change the air amount, and the fuel amount is changed accordingly. As a result, the rotation speed during idling operation in the intake stroke injection mode is increased.
[0042]
When the rotation speed is increased by changing the air amount, for example, since there is a time from when the first air bypass valve 25 is opened to when the air amount increases, the rotation speed is increased to a predetermined rotation speed after a predetermined time has elapsed. To be stable. For this reason, after the air conditioner switch 71 is turned on, the rotation speed feedback inhibition timer for the intake stroke injection mode is activated, and the feedback control of the rotation speed is performed for a longer time T than in the compression lean mode. The control is prohibited, and after a lapse, the feedback control is restarted.
[0043]
In the case of the intake stroke injection mode, a time lag occurs in the increase of the air amount, so that the feedback control of the rotation speed is prohibited during the time T when the time lag is eliminated, and the stability of the feedback control is ensured.
[0044]
The situation during the idling operation described above will be described with reference to FIGS.
[0045]
As shown in FIG. 5, it is determined in step S1 whether or not the idle switch 31 is on. If it is determined that the idle switch 31 is not on, the process returns because the operation is not idling. If it is determined in step S1 that the idle switch 31 is on, the operation is idling, so that it is determined in step S2 whether the external load signal has changed, for example, whether the air conditioner switch 71 has been turned on. You.
[0046]
When it is determined in step S2 that the air conditioner switch 71 has been turned on, it is determined in step S3 whether or not the operation is in the compression lean mode. If it is determined in step S3 that the mode is the compression lean mode, a feedback inhibition timer (time t) of the rotation speed for the compression lean mode is set in step S4. If it is determined in step S3 that the mode is not the compression lean mode, a feedback inhibition timer for the rotation speed other than the compression lean mode (for example, a rotation inhibition feedback timer for the intake stroke injection mode: time T) is set in step S5. .
[0047]
The idle operation other than the compression lean mode may be, for example, a cold start. In this case, the stoichiometric feedback mode (see FIG. 2) is set. This is a timer for inhibiting the feedback of the rotation speed for the injection mode.
[0048]
After setting the timer in step S4 or step S5, the process proceeds to step S6 in FIG. 6 to count down the timer. On the other hand, if it is determined in step S2 that the air conditioner switch 71 has not been turned on, the process proceeds to step S7, and the feedback inhibition timer for the rotation speed for the compression lean mode or the feedback inhibition for the rotation speed for the intake stroke injection mode. It is determined whether the timer has been set. If it is determined that the timer has been set, the process proceeds to step S6 and the timer is counted down.
[0049]
After counting down the timer in step S6, it is determined in step S8 whether the timer is 0 or not. If it is determined in step S8 that the timer is 0, feedback of the rotation speed is permitted in step S9. If it is determined that the timer is not 0, the feedback of the rotation speed is prohibited in step S9. On the other hand, when it is determined in step S7 that the feedback prohibition timer for the rotation speed for the compression lean mode or the feedback prohibition timer for the rotation speed for the intake stroke injection mode has not been set, the process proceeds to step S9 and the rotation is performed. Prohibits speed feedback.
[0050]
That is, when an external load is applied during the idling operation, for example, when the air conditioner switch 71 is turned on, in the case of the compression lean mode, the rotation is performed by changing the fuel amount set by the feedback inhibition timer of the rotation speed for the compression lean mode. During a short time t during which the speed stabilizes, the feedback of the rotational speed is prohibited, and in the case of the intake stroke injection mode, the air is longer than the time t set by the rotational speed feedback inhibition timer for the intake stroke injection mode. The feedback of the rotation speed is prohibited while the time T during which the rotation speed is stabilized by the change of the amount elapses.
[0051]
For this reason, when an external load is applied during the idling operation in the compression lean mode and when an external load is applied during the idling operation in the intake stroke injection mode, a period in which the feedback of the rotation speed is prohibited is set, respectively. The responsiveness of the feedback control of the rotational speed in the compression lean mode is improved, and the stability of the feedback control in the intake stroke injection mode is ensured.
[0052]
【The invention's effect】
In the internal combustion engine of the present invention, the intake air amount is changed in the intake stroke, while at least the fuel amount is changed in the compression stroke, and the rotation speed is feedback-controlled so that the actual rotation speed of the engine becomes the preset target rotation speed. Means, the feedback control of the rotational speed is prohibited for a predetermined period when an external load is applied by the prohibiting means, and the predetermined period is set separately for the intake stroke and the compression stroke by the setting means. The period during which the feedback control is prohibited in the compression lean mode in which the rotation speed is increased can be set shorter than the period in which the feedback control is prohibited in the intake stroke injection mode in which the rotation speed is increased by changing the intake air amount. . As a result, when performing the feedback control of the rotation speed, the stability of the feedback control in the intake stroke injection mode is secured, and the responsiveness of the feedback control in the compression lean mode is improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a multi-cylinder in-cylinder injection internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a fuel injection control map.
FIG. 3 is an explanatory diagram of a change over time in a compression lean mode.
FIG. 4 is an explanatory diagram of a change over time in an intake stroke injection mode.
FIG. 5 is a flowchart of rotational speed feedback control during idling operation.
FIG. 6 is a flowchart of rotational speed feedback control during idling operation.
[Explanation of symbols]
1 multi-cylinder direct injection internal combustion engine (direct injection engine)
2 Cylinder head 4 Fuel injection valve 5 Combustion chamber 9 Intake port 10 Exhaust port 25 First air bypass valve 61 ECU
71 Air conditioner switch

Claims (1)

In an internal combustion engine that performs fuel injection at least in an intake stroke and a compression stroke, the intake air amount is changed in the intake stroke, while the fuel amount is changed in the compression stroke so that the actual rotation speed of the engine becomes a preset target rotation speed. Control means for performing feedback control of the rotational speed. An internal combustion engine, comprising: setting means for separately setting.

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