JP6015611B2 - Control device for internal combustion engine - Google Patents

Description

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

  Conventionally, in view of the large influence of the temperature of the internal combustion engine on the combustion state of the internal combustion engine, various controls of the internal combustion engine such as fuel injection control have been performed based on the temperature of the internal combustion engine. For example, a control device for an internal combustion engine described in Patent Document 1 includes a temperature sensor that detects a cooling water temperature of the internal combustion engine that has a correlation with the temperature of the internal combustion engine, and injects fuel based on a detected value of the cooling water temperature by the temperature sensor. Is controlling.

JP 2003-113731 A

However, when a temperature sensor for detecting the actual temperature of the internal combustion engine is provided, parts such as wiring wires are required in addition to the temperature sensor itself, and a processing step for attaching the temperature sensor is added. The manufacturing cost may increase.
Thus, the present applicant detects, for example, a resistance value of a coil of a crank angle sensor as a functional component mounted on the internal combustion engine, and an invention relating to a control device that estimates the actual temperature of the internal combustion engine based on the detected coil resistance value. Was first filed (Japanese Patent Application No. 2013-85537). According to this prior application, it is considered that the internal combustion engine can be started satisfactorily by injecting the optimum fuel injection amount according to the internal combustion engine temperature based on the estimated temperature when the internal combustion engine is started, without providing a temperature sensor.

However, in the configuration of temperature estimation according to the previous application, a predetermined time is required until the correlation between the actual temperature of the internal combustion engine and the estimated temperature is obtained after the internal combustion engine is stopped due to the difference in the heat capacity of each part. On the other hand, when restarting when sufficient time has not elapsed since the internal combustion engine was stopped, the error between the estimated temperature and the actual temperature of the internal combustion engine may be due to insufficient accuracy of the temperature correction value or the influence of disturbance. It can grow.
Then, when the fuel injection amount determined based on the estimated temperature having a large error is injected, the air-fuel ratio becomes over-rich or over-lean, which may cause performance deterioration such as start failure and drivability reduction. As described above, in the control device that estimates the actual temperature of the internal combustion engine by the temperature estimating means, deterioration of the startability due to the error of the estimated temperature becomes a new problem.

  The present invention has been made in view of the above problems, and an object of the present invention is to satisfactorily start the internal combustion engine without providing a temperature sensor for detecting the actual temperature of the internal combustion engine, and to start the internal combustion engine. It is another object of the present invention to provide a control device for an internal combustion engine that can search the actual temperature of the engine.

  The control apparatus for an internal combustion engine according to the present invention includes fuel injection command means, ignition command means, rotation speed detection means, and start control means. The fuel injection command means commands the fuel injection valve to inject the fuel injection timing and amount. The ignition command means commands ignition to the spark plug at a predetermined timing. The rotation speed detection means detects the rotation speed of the internal combustion engine.

The start control means executes an “actual temperature search process” when starting the internal combustion engine. This actual temperature search process is “calculating the fuel injection amount corresponding to the virtual temperature while sequentially changing the virtual temperature of the internal combustion engine, requesting the fuel injection command means to inject fuel at the fuel injection amount, and The actual temperature at the start of the internal combustion engine is determined by repeating a series of trial operations that require the ignition command means to ignite at the timing of the engine until at least the start of the internal combustion engine is determined based on the rotational speed of the internal combustion engine. To explore.
Here, “at the time of starting the internal combustion engine” refers to a period from when the engine starts to rotate in a stopped state to when it reaches a “determined start engine speed” at which the rotation is considered to be stable.

This actual temperature search process is specifically executed by the “injection amount change mode” or the “correction coefficient change mode”.
In the injection amount change mode, the first temperature characteristic map that defines the relationship between the actual temperature of the internal combustion engine and the optimal fuel injection amount at which the internal combustion engine can be started is referred to, and the map value of the optimal fuel injection amount corresponding to the virtual temperature is used. Repeat trial operation.
In the correction coefficient change mode, the second temperature characteristic map that defines the relationship between the actual temperature of the internal combustion engine and the correction coefficient in the calculation formula of “fuel injection amount = basic injection amount × correction coefficient” is referred to and corresponds to the virtual temperature. The trial operation is repeated with the fuel injection amount calculated based on the map value of the correction coefficient.

  The start control means applies the injection amount change mode when the rotational speed of the internal combustion engine is less than a predetermined switching speed, and applies the correction coefficient change mode when the rotational speed of the internal combustion engine exceeds the switching speed. Good. The switching rotational speed can be set, for example, to a value corresponding to the “temporary starting rotational speed” that is smaller than the above “determined starting rotational speed”, which can be regarded as “started once”.

According to the present invention, when the internal combustion engine is started, the start control means of the control device sets a virtual temperature, referring to the temperature characteristic map, the optimum fuel injection amount corresponding to the virtual temperature, or the correction coefficient corresponding to the virtual temperature The actual temperature search process is repeated to repeat the procedure of injecting fuel with the fuel injection amount calculated based on the above and confirming whether or not the engine can be started. Thereby, it is possible to start the internal combustion engine satisfactorily without searching for a temperature sensor for detecting the internal combustion engine temperature, and to search the internal combustion engine temperature at the time of starting. Therefore, the structure of the internal combustion engine is simplified, and the manufacturing cost can be reduced.
Further, since the internal combustion engine is started by repeatedly trying fuel injection without depending on the estimated temperature by the temperature estimating means, it is possible to avoid a starting failure even when the error between the estimated temperature and the actual temperature is large.

Preferably, in the actual temperature search process, the start control means lowers the virtual temperature stepwise from the high temperature side to the low temperature side while maintaining a constant temperature for a predetermined period.
Regarding the relationship between the internal combustion engine temperature and the optimal fuel injection amount or the correction coefficient in the temperature characteristic map, the higher the internal combustion engine temperature, the smaller the optimal fuel injection amount. Further, the gradient of the optimum fuel injection amount or the correction coefficient with respect to the internal combustion engine temperature is larger on the lower temperature side and smaller on the higher temperature side. For this reason, if the virtual temperature is set lower than the actual temperature, an excessive amount of fuel is injected with respect to the optimum fuel injection amount, and there is a risk of misfire due to a so-called “plug fog phenomenon” due to excessive fuel. Therefore, by gradually decreasing the virtual temperature from the high temperature side to the low temperature side and gradually increasing the fuel injection amount, it is possible to suppress the occurrence of the “fogging phenomenon” and to prevent the starting failure.

  In addition, if the virtual temperature is gradually changed from the high temperature side to the low temperature side, it may become unclear at which temperature the engine can be started. In addition, the time required for searching for the actual temperature may increase. Therefore, by gradually reducing the temperature while maintaining a constant temperature for a predetermined period, the search accuracy of the actual temperature at the start of the internal combustion engine can be improved, and the search time can be shortened. In this case, it is preferable to execute fuel injection and ignition for a predetermined number of trials while holding the virtual temperature at a constant temperature for a predetermined period.

  Furthermore, in the present invention, a temperature estimation unit that calculates an estimated temperature of the internal combustion engine based on a detected value of a physical quantity correlated with an actual temperature of the internal combustion engine is provided, and the start control unit is based on the estimated temperature calculated by the temperature estimation unit. Thus, an initial value of the virtual temperature at the start of the actual temperature search process may be set.

For example, the estimated temperature and the actual temperature of the internal combustion engine may be well correlated in some situations, such as when restarting after a sufficient time has elapsed since the internal combustion engine stopped. In addition, even if there is an error, the estimated temperature is a temporary measure for the actual temperature.
Therefore, when starting the actual temperature search process, setting the temperature based on the estimated temperature as the initial value of the virtual temperature increases the possibility of starting the process from a temperature closer to the actual temperature. Therefore, the number of trial and error until the start can be reduced, and the internal combustion engine can be started in a shorter time.

  By the way, in order to search the actual temperature by lowering the virtual temperature from the high temperature side toward the low temperature side, there is a case where the engine is started in a “lean limit state” where the virtual temperature is higher than the actual temperature. Then, during the determination period in which the crankshaft rotates a predetermined number of times from the start of the actual temperature search process, the rotational speed of the internal combustion engine reaches a predetermined value. Therefore, in this case, it is preferable that the start control means corrects the virtual temperature at the end of the actual temperature search process to the low temperature side at the stage where the actual temperature search process ends and shifts from the start to the start.

1 is an overall configuration diagram of an internal combustion engine according to a first embodiment of the present invention. The electrical block diagram which shows the structure of the temperature estimation means in a control apparatus. The time chart which shows the change of the internal combustion engine temperature Te and the coil temperature Tc of a crank angle sensor at the time of a driving | operation of an internal combustion engine, and after a driving | operation stop. (A) The figure which shows the relationship between coil resistance RS and coil temperature Tc. (B) The figure which shows the relationship between the elapsed time from the stop of an internal combustion engine, and the temperature correction value (alpha). (C) The figure which shows the relationship between coil temperature rise value (DELTA) Tc and temperature addition value (beta). The time chart which shows the whole behavior until starting of an internal combustion engine is decided. 6 is a flowchart for selecting an injection amount change mode and a correction coefficient change mode. (A) A first temperature characteristic map defining the relationship between the internal combustion engine temperature Te and the optimum fuel injection amount. (B) A second temperature characteristic map that defines the relationship between the internal combustion engine temperature Te and the correction coefficient. The flowchart of the real temperature search process by 1st Embodiment of this invention. The time chart which shows an example of the actual temperature search process of this invention. The flowchart of the correction process at the time of correction | amendment which correct | amends virtual temperature at the time of transfer from the time of starting to after starting. The flowchart of the real temperature search process by 2nd Embodiment of this invention.

  Hereinafter, an embodiment in which a control device according to the present invention is applied to a vehicle equipped with an air-cooled internal combustion engine will be described with reference to the drawings. As an internal combustion engine to which the present embodiment is applied, a four-stroke gasoline internal combustion engine that is operated with four strokes of intake, compression, expansion, and exhaust as one combustion cycle is assumed. A scooter that is a motorcycle is assumed as the vehicle, and the internal combustion engine is a single cylinder internal combustion engine. This scooter has a configuration in which an internal combustion engine mounted below a seat is covered with a shroud (cover member).

(First embodiment)
First, the outline of the configuration of the control apparatus for an internal combustion engine according to the first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, in the intake passage 12 of the internal combustion engine 10, an air cleaner 14, a throttle valve 16, a throttle sensor 17 for detecting the opening degree of the throttle valve 16, and an intake pressure of the intake passage 12 are sequentially arranged from the upstream side. An intake pressure sensor 18 is provided to detect the above. The throttle valve 16 adjusts the amount of intake air into the combustion chamber 20 of the internal combustion engine 10 by adjusting the throttle opening. The throttle opening is adjusted according to the operation of a throttle grip (not shown) operated by the user.
Further, a bypass passage 22 is connected to the intake passage 12 so that the upstream side and the downstream side of the throttle valve 16 communicate with each other. The bypass passage 22 is provided with an electromagnetic valve 24 that adjusts the amount of intake air flowing through the bypass passage 22 in order to control the rotational speed during idling of the internal combustion engine 10.

  A fuel injection valve 29 for supplying the fuel pumped up from the fuel tank 28 by the fuel pump 26 to the vicinity of the intake port is provided near the intake port on the downstream side of the intake pressure sensor 18 in the intake passage 12. Yes. The mixture of fuel and intake air injected and supplied from the fuel injection valve 29 is supplied to the combustion chamber 20 by the opening operation of the intake valve 32. In other embodiments, the fuel injection valve 29 may be provided so as to inject fuel directly into the combustion chamber 20.

  The air-fuel mixture supplied to the combustion chamber 20 is ignited by the discharge spark of the spark plug 34 protruding into the combustion chamber 20 and is used for combustion. The energy generated by the combustion of the air-fuel mixture is taken out as rotational energy of the crankshaft 38 that is the output shaft of the internal combustion engine 10 through the piston 36. A high voltage for ignition is applied to the spark plug 34 by an ignition coil 35 as an ignition device. The air-fuel mixture used for combustion is discharged into the exhaust passage 42 as exhaust gas by the opening operation of the exhaust valve 40.

  A magnet generator rotor 50 (hereinafter referred to as “rotor 50”) is attached to the crankshaft 38. As shown in FIG. 2, the rotor 50 is provided with a plurality of projections 51 for crank position signals for each predetermined rotation angle of the outer peripheral portion. In addition, the outer peripheral portion of the rotor 50 is provided with a missing tooth portion 52 as a reference position by deleting one (or two) of the plurality of protrusions 51 arranged at equal intervals. In the present embodiment, the protrusions 51 are basically provided at equal intervals of 30 ° CA, and only at the tooth missing portion 52 are at intervals of 60 ° CA. The number and interval of the protrusions 51 are not limited to this example and may be set arbitrarily.

  The cylinder block 11 of the internal combustion engine 10 is provided with a crank angle sensor 60 as a rotation detection sensor at a position facing the protrusion 51 of the rotor 50. More specifically, the crank angle sensor 60 is provided in the crankcase portion of the cylinder block 11. The crank angle sensor 60 is a known electromagnetic pickup type sensor, and includes an iron core (not shown), a detection coil 61 (hereinafter referred to as “coil 61”) provided around the iron core, and a magnetic flux passing through the coil 61. And a generated magnet (not shown).

The rotor 50 is rotated in conjunction with the rotation of the crankshaft 38. When the protrusion 51 on the outer periphery of the rotor 50 passes the position of the crank angle sensor 60, the magnetic flux passing through the coil 61 of the crank angle sensor 60 is changed by the unevenness of the protrusion 51, and an electromotive force is generated in the coil 61 by the action of electromagnetic induction. . In this case, the coil 61 detects the passage of the protrusion 51 and outputs an AC signal as a rotation angle signal at a predetermined rotation angle cycle.
The crank angle sensor 60 is attached to the base of a stator coil of an alternator provided in the vicinity of the internal combustion engine 10 in addition to the one directly mounted on the cylinder block 11, and rotates the rotor of the alternator. It may be a sensor to detect or a crank angle sensor attached to the crankcase cover side.

  The exhaust passage 42 is provided with a three-way catalyst 46 for purifying NOx, HC, CO and the like in the exhaust. An oxygen concentration sensor 48 that changes the output value in a binary manner according to the oxygen concentration in the exhaust gas is provided on the upstream side of the three-way catalyst 46.

The vehicle (scooter) of the present embodiment is equipped with a cooling device 49 for forcibly cooling the internal combustion engine 10 disposed in the shroud. The cooling device 49 includes a mechanical fan device driven by the rotation of the internal combustion engine 10, and has a known cooling fan connected to the crankshaft 38. The shroud is provided with an intake port for taking in cooling air from the outside and an exhaust port for discharging the cooling air. When the cooling device 49 is driven, the shroud is passed through the intake port and the exhaust port. Cooling air passes through it.
The cooling device 49 rotates the fan during operation of the internal combustion engine 10 to air-cool the internal combustion engine 10 and stops the air cooling when the internal combustion engine 10 stops.

  The control device 70 is configured as an electronic control unit (ECU) including a microcomputer. The microcomputer performs various internal combustion engine controls based on various programs and arithmetic expressions stored in the storage unit. In this case, the operation state of the internal combustion engine 10 is controlled by controlling the operation of the fuel injection valve 29 and the ignition coil 35 based on the signals acquired by the various sensors described above.

The control device 70 of this embodiment includes a temperature estimation unit 71, a fuel injection command unit 75, an ignition command unit 76, a rotation speed detection unit 77, and a start control unit 78. This is from a functional viewpoint and does not mean that each means is physically mounted on one substrate.
In FIG. 2, illustrations other than the temperature estimation unit 71 and the rotation speed detection unit 77 are omitted.
In the present embodiment, on the premise that a temperature sensor that directly detects the actual temperature of the internal combustion engine 10 (hereinafter, referred to as “internal combustion engine temperature”) Te is not provided, the temperature estimation means 71 includes the temperature detected by the thermistor 74, Alternatively, the internal combustion engine temperature Te is estimated based on the resistance value of the coil 60 of the crank angle sensor 60. Details of this temperature estimation will be described later.

The fuel injection command means 75 commands the operation of the fuel pump 26 and commands the fuel injection valve 29 about the fuel injection timing and the fuel injection amount.
The ignition command means 76 commands ignition plug 34 to ignite through control of ignition coil 35 at a predetermined timing.

  As shown in FIG. 2, the rotational speed detection means 77 receives the AC signal output from the crank angle sensor 60 after being converted into a pulse signal by the waveform shaping circuit 62. The rotational speed detection means 77 detects the rotational speed (rotational speed) of the internal combustion engine 10 based on the interval between the pulse signals input from the waveform shaping circuit 62. Further, the rotational speed detection means 77 determines the position of the missing tooth portion 52 that is the reference position based on the difference in the pulse signal interval caused by the difference in angular interval between the missing tooth portion 52 and the other portion in the rotor 50. Is detected.

The start control means 78 executes “actual temperature search process” which is a feature of the present invention, and controls the start of the internal combustion engine 10. As shown in FIG. 1, the start control means 78 acquires information from the temperature estimation means 71 and the rotation speed detection means 77, and the fuel injection valve 29 and the ignition command means 76 are connected to the fuel injection valve 29 and the ignition command means 76. A command to the spark plug 34 is requested.
The start control means 78 determines that the internal combustion engine 10 has started based on the change in the rotation speed of the internal combustion engine 10 detected by the rotation speed detection means 77. Specifically, it is determined that the engine has been started when the number of revolutions of the internal combustion engine 10 suddenly increases from 0, or when the number of revolutions exceeds a predetermined number.
The detailed operation of the start control means 78 will be described later.

Hereinafter, a configuration for estimating the internal combustion engine temperature Te by the temperature estimation means 71 will be described.
As shown in FIG. 2, the thermistor 74 for detecting the temperature of the control device 70 is connected to the control device 70. Since the temperature of the control device 70 is affected to some extent by the internal combustion engine temperature Te, the detected temperature of the thermistor 74 can roughly reflect the internal combustion engine temperature Te if not accurately. That is, since the attachment position of each component and the engine specifications are set, the thermistor 74 and the internal combustion engine temperature Te have a correlation, and a correlation equation can be obtained by various tests performed in advance. Based on this correlation, the temperature estimating means 71 estimates the internal combustion engine temperature Te, for example, by adding or multiplying a predetermined constant to the temperature detected by the thermistor 74.

  The crank angle sensor 60 mounted directly on the cylinder block 11 of the internal combustion engine 10 has a correlation with the internal combustion engine temperature Te. Therefore, the temperature estimating means 71 detects the resistance value of the coil 61 of the crank angle sensor 60 as follows when the internal combustion engine 10 is stopped and under the operating condition, and based on the detected coil resistance value, the internal combustion engine. The temperature Te is calculated.

The control device 70 includes an energization unit 72 for energizing the coil 61 and a voltage detection unit 73 that is an A / D circuit that detects a voltage value applied to the coil 61 when the coil energization is performed by the energization unit 72.
The energization unit 72 includes a constant voltage power source 721 having a voltage Vcc, PNP bipolar transistors 722 and 723, a resistor 724 having a resistance value R 1, a resistor 725 having a resistance value R 1, and a switch 726. The transistors 722 and 723 form a current mirror circuit, the bases of the transistors 722 and 723 are connected to each other, and the base connection is connected to the collector of the transistor 723.

  The emitters of the transistors 722 and 723 are each connected to the power source 721. A resistor 725 is connected to the collector side of the transistor 723, and the voltage detection unit 73, the coil 61, and the waveform shaping circuit 62 are connected in parallel to the other end of the resistor 725. On the other hand, a resistor 724 is connected to the collector side of the transistor 722, and a switch 726 is connected to the other end of the resistor 724. The switch 726 is a semiconductor switch, for example, and switches the transistor 722 between a conductive state and a non-conductive state.

When the switch 726 is turned on and the transistor 722 is turned on, the transistor 723 is also turned on, the transistor IS 722 outputs a current IS (IS = Vcc / R1), and the transistor 723 outputs a current IS2 (≈IS). This current IS2 becomes the coil current IS2 supplied to the coil 61. Here, since the current IS≈IS2, the coil current IS2 is obtained as IS2≈IS = Vcc / R1.
The voltage detector 73 detects the coil voltage VRS applied to the coil 61. The coil resistance value RS is calculated as RS = VRS / IS2. The temperature estimating means 71 calculates the coil temperature Tc based on the coil resistance value RS (see FIG. 4A), and further estimates the internal combustion engine temperature Te from the coil temperature Tc.

Next, the relationship between the internal combustion engine temperature Te and the coil temperature Tc during and after the operation of the internal combustion engine 10 will be described with reference to FIGS. Hereinafter, the internal combustion engine temperature Te refers to the temperature of the internal combustion engine body in the vicinity of the combustion chamber 20, that is, the temperature around the combustion chamber 20 of the cylinder head or cylinder block 11.
In the time chart of FIG. 3, the internal combustion engine 10 is started in a cold state at time t1, and then the operation of the internal combustion engine 10 is stopped at time t2. After time t2, the internal combustion engine is stopped (soaked). The period from time t1 to time t2 is, for example, about 50 minutes.

  As shown in FIG. 3, the internal combustion engine temperature Te is higher than the coil temperature Tc in the period [I] from time t <b> 1 to t <b> 2 during operation of the internal combustion engine 10. After the operation of the internal combustion engine 10 is stopped at time t2, the temperature difference between the internal combustion engine temperature Te and the coil temperature Tc gradually decreases during the period [II] until time t3. In the period [III] after time t3, the internal combustion engine temperature Te and the coil temperature Tc substantially coincide.

The temperature estimating means 71 changes the method for estimating the internal combustion engine temperature Te from the coil temperature Tc according to the above three periods. Hereinafter, the estimation method in each period will be described in the order of period [III], period [II], and period [I] for convenience of explanation.
In a period [III] in which a sufficient time has elapsed since the internal combustion engine 10 stopped, assuming that Tc≈Te, the coil temperature calculated from the coil resistance value RS using the relationship shown in FIG. Let Tc be the internal combustion engine temperature Te as it is.

In the period [II] immediately after the internal combustion engine 10 is stopped, the temperature obtained by adding the temperature correction value α shown in FIG. 4B to the coil temperature Tc is defined as the internal combustion engine temperature Te (Te = Tc + α). The temperature correction value α decreases as the elapsed time after the internal combustion engine 10 stops increases.
In addition, it supplements about the behavior of the coil temperature Tc immediately after the time t2. When the internal combustion engine 10 is stopped, the internal combustion engine 10 is cooled by natural heat dissipation while air cooling by the cooling device 49 is stopped. The coil temperature Tc temporarily increases immediately after time t2 due to the accumulated heat in the shroud, and then gradually decreases together with the internal combustion engine temperature Te.

  Next, in the period [I] during which the internal combustion engine 10 is in operation, the internal combustion engine temperature Te and the coil temperature Tc at the operation start time t1 coincide with the initial temperature Ti. When the operation of the internal combustion engine 10 is started, the internal combustion engine temperature Te and the coil temperature Tc increase. Further, the rise of the temperatures Te and Tc is limited by the cooling by the cooling device 49 and the cooling by the traveling wind. At this time, the crank angle sensor 60 is more greatly cooled by fan cooling than the internal combustion engine 10 as a whole, so the internal combustion engine temperature Te is higher than the coil temperature Tc.

  Here, if the increase value of the coil temperature Tc at the time tx during operation of the internal combustion engine 10 with respect to the initial temperature Ti is ΔTc, and the difference between the internal combustion engine temperature Te and the coil temperature Tc is the temperature addition value β, the coil temperature Tc is , Tc = Ti + ΔTc, and the internal combustion engine temperature Te are calculated as Te = Tc + β. The relationship between the coil temperature increase value ΔTc and the temperature addition value β is expressed as shown in FIG. The temperature addition value β corresponds to a temperature difference in which the crank angle sensor 60 is cooled more than the internal combustion engine 10 by air cooling by the cooling device 49.

  As described above, the temperature estimation unit 71 of the present embodiment estimates the internal combustion engine temperature Te based on the temperature detected by the thermistor 74 or the resistance value of the coil 60 of the crank angle sensor 60. Then, the control device 70 controls the operating state of the internal combustion engine 10 based on the estimated temperature estimated by the temperature estimating means 71. Thereby, since the temperature sensor which directly detects the internal combustion engine temperature Te can be abolished, it is possible to reduce the cost of components such as the temperature sensor and wiring, the processing cost for attaching the temperature sensor, and the like.

By the way, when the internal combustion engine 10 is started, the optimum fuel injection amount changes according to the internal combustion engine temperature Te. Even if the amount of fuel injected from the fuel injection valve 29 is too small or too much than the optimum fuel injection amount, the internal combustion engine 10 cannot be started well. If the fuel injection amount is too large, the spark plug 34 may get wet with fuel, so that a so-called “fogging phenomenon” may occur and the engine cannot be started.

  On the other hand, in the temperature estimation, in the period [III] in which the relationship of Tc≈Te is obtained, the estimation error is small and a highly reliable estimated temperature is obtained, but the period [III] is reached after the internal combustion engine 10 is stopped. A predetermined time is required until. In particular, in the scooter of this embodiment, when the internal combustion engine 10 is stopped, the air cooling by the cooling device 49 is stopped.

  On the other hand, when the internal combustion engine temperature Te is estimated based on the coil resistance value of the crank angle sensor 60 in the period [II] when sufficient time has not elapsed since the internal combustion engine 10 was stopped, the internal combustion engine temperature Te of FIG. There is a possibility that an error between the estimated temperature and the internal combustion engine temperature Te increases due to insufficient accuracy of the temperature correction value α or the influence of disturbance. Then, when the fuel injection amount determined based on the estimated temperature having a large error is injected, the air-fuel ratio becomes over-rich or over-lean, which may cause a start failure and a decrease in drivability.

Therefore, in the control device 70 of the present embodiment, the start control means 78 executes the “actual temperature search process”, thereby operating the virtual temperature under a predetermined condition and confirming whether or not the internal combustion engine 10 can be started. It is characterized by finding a temperature Te.
Next, the characteristic configuration and operation of the present embodiment will be described with reference to FIGS.

First, the transition at the start of the internal combustion engine 10 will be described with reference to FIG.
As shown in FIG. 5, at the start of the internal combustion engine 10, the rotational speed does not increase monotonously, but usually increases while going through several peaks. Here, two rotation speed thresholds Np and Nf are defined.
The temporary starting rotational speed Np is a rotational speed of, for example, about 800 rpm, at which the internal combustion engine 10 can be regarded as “started temporarily”. Since the rotation in the temporary start state is not yet stable, the temporary start rotation speed Np may be once lower than the temporary start rotation speed Np due to the influence of disturbance or the like once the temporary start rotation speed Np is exceeded. On the other hand, the fixed start rotation speed Nf set to a value larger than the temporary start rotation speed Np is the rotation speed at which the rotation of the internal combustion engine 10 is considered to be stable.

  In the example shown in FIG. 5, the rotational speed starts increasing from time ts0 in the stopped state, and after exceeding the provisional starting rotational speed Np at times tp1 and tp2, the rotational speed decreases again. Thereafter, when the provisional starting rotational speed Np is exceeded for the third time at time tp3, the fixed starting rotational speed Nf is reached as it is at time tf. Thus, the period from the start of rotation from the stop state to time tf is referred to as “starting time”, and the period after time tf is referred to as “after starting”.

  The start control means 78 of the present embodiment executes an actual temperature search process at the “starting of the internal combustion engine” defined as described above. In the actual temperature search processing, “a fuel injection amount corresponding to the virtual temperature is calculated while sequentially changing the virtual temperature of the internal combustion engine 10, and the fuel injection command means 75 is requested to inject fuel at the fuel injection amount. The actual temperature Te at the time of starting of the internal combustion engine 10 is searched by repeating a series of trial operations “requesting the ignition command means 76 to ignite at the timing of“ until the start of the internal combustion engine 10 is determined.

The “injection amount change mode” and the “correction coefficient change mode” applied by the start control means 78 to calculate the fuel injection amount corresponding to the virtual temperature will be described with reference to FIGS.
In the injection amount change mode, the first temperature characteristic map (FIG. 7 (a)) defining the relationship between the internal combustion engine temperature Te and the optimal fuel injection amount at which the internal combustion engine 10 can be started is referred to, and the optimum corresponding to the virtual temperature is determined. The trial operation is repeated with the map value of the fuel injection amount.
In the correction coefficient change mode, on the premise of a calculation formula of “fuel injection amount = basic injection amount × correction coefficient”, a second temperature characteristic map that defines the relationship between the internal combustion engine temperature Te and the correction coefficient in the above calculation formula (FIG. 7 (b)), the trial operation is repeated with the fuel injection amount calculated based on the map value of the correction coefficient corresponding to the virtual temperature. The basic injection amount is calculated based on a well-known technique such as a DJ map that defines the relationship between the internal combustion engine rotational speed and the intake pressure, an αN map that defines the relationship between the internal combustion engine rotational speed and the throttle opening. .

The injection amount change mode and the correction coefficient change mode are selected based on, for example, whether or not the rotational speed of the internal combustion engine 10 is less than a “predetermined switching rotational speed”. In the present embodiment, the “predetermined switching rotational speed” is equivalent to the provisional starting rotational speed Np, and as shown in the flowchart of FIG. 6, when the rotational speed is less than Np (S01: YES), the injection amount change mode (S02) When the rotation speed is Np or more (S01: NO), the correction coefficient change mode (S03) is selected.
Therefore, the injection amount changing mode is applied in the first trial operation from the stop state (the rotational speed≈0), and the correction coefficient changing mode is applied when the rotational speed reaches the provisional starting rotational speed Np.

  As shown in FIGS. 7A and 7B, the first temperature characteristic map and the second temperature characteristic map depict similar curves. To explain the first temperature characteristic map as a representative, the optimum fuel injection amount is smaller as the internal combustion engine temperature Te is higher. Further, the gradient of the optimum fuel injection amount with respect to the internal combustion engine temperature Te is larger on the low temperature side and smaller on the high temperature side. For example, in the region where the internal combustion engine temperature Te is 0 ° C. or less, the optimum fuel injection amount increases rapidly as the temperature decreases. On the other hand, when the internal combustion engine temperature Te is about 30 ° C. to 60 ° C., the gradient of the optimum fuel injection amount with respect to the temperature becomes gentle, and when the internal combustion engine temperature Te exceeds 60 ° C., the optimum fuel injection amount almost converges.

  If a temperature sensor that directly detects the internal combustion engine temperature Te is provided, in the injection amount change mode, the fuel injection amount M corresponding to the temperature Te is obtained from the first temperature characteristic map, and the fuel injection amount M is injected into the fuel. The internal combustion engine 10 can be preferably started by injecting the valve 29. When the temperature changes from Te to Te ', the fuel injection amount may be changed from M to M'.

Similarly, in the correction coefficient change mode, a correction coefficient K corresponding to the temperature Te is obtained from the second temperature characteristic map, and the fuel injection amount calculated based on the correction coefficient K is injected into the fuel injection valve 29, whereby the internal combustion engine 10 is corrected. Can be suitably started. When the temperature changes from Te to Te ′, the correction coefficient may be changed from K to K ′.
Hereinafter, obtaining the fuel injection amount with reference to the temperature characteristic map is referred to as “calculating the fuel injection amount”. The first temperature characteristic map and the second temperature characteristic map may be stored in the start control unit 78 itself, or may be stored in another storage unit and read out as necessary.

  On the other hand, when the internal combustion engine 10 is not provided with a temperature sensor as in this embodiment, the actual temperature is not known at least directly. Therefore, the start control means 78 sets the virtual temperature by trial and error while the actual temperature is unknown, calculates the optimum fuel injection amount or correction coefficient corresponding to the virtual temperature from the temperature characteristic map, and executes the fuel injection. . Then, as a result of trial and error, the internal combustion engine 10 is preferably started, and the actual temperature at the start of the internal combustion engine 10 is searched.

Next, the entire actual temperature search process executed by the start control means 78 will be described based on the flowchart of FIG. In the description of the flowchart, the symbol “S” means a step.
When the internal combustion engine 10 is started, the start control means 78 acquires the estimated temperature calculated by the temperature estimating means 71 based on the temperature detected by the thermistor 74 or the coil temperature Tc of the crank angle sensor 60 (S11). The estimated temperature may be calculated from either the detected temperature of the thermistor 74 or the coil temperature Tc of the crank angle sensor 60. Alternatively, the estimated temperature is used as both the detected temperature of the thermistor 74 and the coil temperature Tc of the crank angle sensor 60. Based on this, an average value or the like may be calculated.

  At this stage, since the rotational speed is less than the provisional starting rotational speed Np, the start control means 78 refers to the first temperature characteristic map and calculates the map value of the fuel injection amount corresponding to the estimated temperature (S12). Then, the fuel injection valve 29 requests the fuel injection command means 75 to inject the injection amount of the map value, and requests the ignition command means 76 to ignite the spark plug 34 at a predetermined time (S13). This fuel injection and ignition operation may be performed not only once but a predetermined number of times.

As a result, if the internal combustion engine 10 is started (S14: YES), the process proceeds to S20. In this case, it is considered that the estimated temperature is close to the actual temperature Te.
On the other hand, if the error between the estimated temperature and the actual temperature Te is large, the internal combustion engine 10 does not start (S14: NO) because in S13, an excessive or excessive fuel is injected with respect to the optimum fuel injection amount. Then, it transfers to S15A and starts an actual temperature search process.

  In S15A, the virtual temperature initial value T1 at the start of the actual temperature search process is set based on the estimated temperature, for example, “estimated temperature + 20 ° C.”. That is, if the estimated temperature is 60 ° C, the virtual temperature initial value T1 is set to 80 ° C, and if the estimated temperature is 20 ° C, the virtual temperature initial value T1 is set to 40 ° C. The setting of the virtual temperature initial value T1 based on the estimated temperature is not limited to the method of uniformly adding the predetermined temperature in this way, and any method such as a method of changing the added temperature according to the estimated temperature may be used.

In S16, the temperature characteristic map corresponding to the mode selected in accordance with the rotation speed in the mode selection process of FIG. 6 is referred to calculate the map value M1 of the fuel injection amount or the map value K1 of the correction coefficient corresponding to the virtual temperature T1. To do. In S17, fuel injection and ignition based on the map value M1 or K1 are executed in the same manner as S13 while the virtual temperature is maintained at a constant temperature for a predetermined period. Here, the symbols of the virtual temperature T1 and the map value M1 correspond to FIG. 9 described later.
If the internal combustion engine 10 is started at the map value M1 based on the virtual temperature T1 (S18: YES), the process proceeds to S20, and the virtual temperature T1 is regarded as the actual temperature Te of the internal combustion engine 10. On the other hand, when the internal combustion engine 10 does not start (S18: NO), the virtual temperature is reset (S19), and the steps of S16 to S18 are repeated. When the virtual temperature is regarded as the actual temperature Te in S20, the control device 70 performs subsequent operation control of the internal combustion engine 10 with the temperature Te at this time as a reference.

The present embodiment is characterized in that in the resetting of the virtual temperature in S19, the temperature is lowered step by step while being held at a constant temperature for a predetermined period from the high temperature side to the low temperature side.
As shown in FIG. 7, the temperature characteristic map shows a downward-sloping characteristic in which the optimum fuel injection amount or the correction coefficient decreases as the temperature increases. Therefore, lowering the fictive temperature from the high temperature side toward the low temperature side is synonymous with increasing the fuel injection amount in order from the small amount side. In other words, if the engine is not started with a small amount of fuel injection, it is possible to prevent the “fogging phenomenon” due to excess fuel by taking the procedure of increasing the fuel injection amount in order until the engine is started.

  In addition, if the virtual temperature is gradually changed from the high temperature side to the low temperature side, it may become unclear at which temperature the engine can be started. Therefore, the search accuracy of the actual temperature Te when the internal combustion engine 10 is started can be improved by gradually decreasing the temperature while holding it at a constant temperature for a predetermined period.

Next, an example of setting the virtual temperature in the actual temperature search process will be described with reference to the time chart of FIG. The horizontal axes of FIGS. 9A, 9B, and 9C are common time axes, and the start time of the actual temperature search process is ts0. At time ts0, the rotational speed of the internal combustion engine is 0 [rpm].
The fuel injection amount in FIG. 9B is a map value of the fuel injection amount obtained by referring to the first temperature characteristic map. The circles in FIG. 9B indicate the timing at which fuel injection is executed. The timing of ignition executed at a predetermined time is not shown. Also, the numbers on the horizontal axis in FIG. 9B indicate the number of fuel injection and ignition trials. In the following description, when “fuel injection” is simply performed, it is natural to include an ignition operation executed at a predetermined time.
FIG. 9C illustrates the behavior in which the internal combustion engine speed gradually increases while repeating increase / decrease with multiple fuel injections, and the waveform shape has no special meaning.

Hereinafter, the progress after starting the actual temperature search process at time ts0 will be described in order.
After starting the actual temperature search process, when the fuel was injected once with the map value M1 corresponding to the virtual temperature initial value T1, the internal combustion engine 10 did not start, so the virtual temperature was changed to T2 lower than T1 at time ts1. .
Next, when the fuel was injected twice at the map value M2 corresponding to the virtual temperature T2, the internal combustion engine 10 did not start, so the virtual temperature was changed to T3 lower than T2 at time ts2.
Next, when the fuel was injected four times with the map value M3 corresponding to the virtual temperature T3, the internal combustion engine 10 did not start, so the virtual temperature was changed to T4 lower than T3 at time ts3.
Next, when the fuel was injected at the map value M4 corresponding to the virtual temperature T4, the rotational speed detecting means 77 detected that the rotational speed of the internal combustion engine 10 suddenly increased after the fifth injection.
It was determined that the internal combustion engine 10 was started. This is the end of the actual temperature search process.

This process has the following characteristics regarding the setting of the virtual temperature or the number of trials.
(1) At the virtual temperature T2 after the time ts1, the virtual temperature T3 after the time ts2, and the virtual temperature T4 after the time ts3, two or more fuel injections are executed while the virtual temperature is maintained at a constant temperature for a predetermined period. Is done. Even if the set virtual temperature is close to the actual temperature Te and the map value of the fuel injection amount is almost the optimum amount, the fuel injection may not be started by one fuel injection. Therefore, it is preferable to set the number of trials as two or more as appropriate as the “predetermined number”.

  (2) The number of trials X3 (= 4 times) at the virtual temperature T3 on the low temperature side is set larger than the number of trials X2 (= 2 times) at the virtual temperature T2 on the high temperature side. Since combustion is more unstable on the low temperature side than on the high temperature side, it is preferable to secure more opportunities for combustion by increasing the number of trials on the low temperature side.

(3) The temperature difference ΔT _2-3 between the low temperature side virtual temperatures T2 and T3 is set smaller than the temperature difference ΔT _1-2 between the high temperature side virtual temperatures T1 and T2. In the temperature characteristic map, the slope of the optimal fuel injection amount with respect to temperature increases as the temperature decreases. It is preferable to change at equal intervals.

(4) A certain lower limit value (guard value) is provided for the lowest virtual temperature T4 during processing. Since the optimum fuel injection amount rapidly increases in the low temperature region of the temperature characteristic map, it is preferable to avoid an excessive amount of fuel injection by setting a lower limit value.
This lower limit value may be set based on the detected temperature of the thermistor 74 or the coil temperature Tc of the crank angle sensor 60, similarly to the estimated temperature. In addition, since the cranking rotation speed decreases as the temperature decreases, the lower limit value of the virtual temperature may be set based on the cranking rotation speed.

Next, a description will be given of a virtual temperature correction process that is executed when the above-described actual temperature search process is completed and a transition is made from “at start-up” to “after start-up” with reference to the flowchart of FIG.
In the actual temperature search process, the virtual temperature is decreased from the high temperature side toward the low temperature side to search for the actual temperature, and therefore, the engine may be started in a “lean limit state” where the virtual temperature is higher than the actual temperature. Then, during the determination period in which the crankshaft rotates a predetermined number of times from the start of the actual temperature search process (time ts0 in FIG. 9), the rotational speed of the internal combustion engine 10 reaches a predetermined value.

  In S21, it is determined whether or not the rotational speed of the internal combustion engine 10 has reached a predetermined value during the determination period. If YES in S21, the process proceeds to S22, and correction is performed to shift the virtual temperature at the end of the actual temperature search process to the low temperature side. In other words, when the engine is started in the “lean limit state”, the amount of fuel that is actually injected is insufficient with respect to the originally required injection amount. Correction can be made in an increasing direction. On the other hand, if NO in S21, the virtual temperature at the end of the actual temperature search process is maintained in S23.

(effect)
As described above, in the present embodiment, when the internal combustion engine 10 is started, the start control means 78 of the control device 70 sets the virtual temperature, and the map value of the optimum fuel injection amount corresponding to the virtual temperature with reference to the temperature characteristic map. Alternatively, an actual temperature search process is performed in which fuel is injected with the fuel injection amount calculated based on the map value of the correction coefficient, and the procedure of confirming whether start is possible is repeated. Thereby, the internal combustion engine 10 can be started satisfactorily and the internal combustion engine temperature Te at the time of starting can be searched without providing a temperature sensor for detecting the internal combustion engine temperature Te. Therefore, the structure of the internal combustion engine 10 is simplified, and the manufacturing cost can be reduced.

  Further, in the control device for an internal combustion engine according to the prior application by the present applicant, the internal combustion engine temperature Te is estimated based on the detected temperature of the thermistor 74 or the coil temperature Tc of the crank angle sensor 60 instead of the temperature sensor, The operating state of the internal combustion engine 10 is controlled by the estimated temperature. In this configuration, when the error between the estimated temperature and the actual temperature Te is large, there is a risk of performance deterioration such as start-up failure or drivability deterioration.

On the other hand, in the present embodiment, the internal combustion engine 10 is started by repeatedly trying fuel injection without depending on the estimated temperature by the temperature estimating means 71. Therefore, even when the error between the estimated temperature and the actual temperature Te is large, the starting failure Can be avoided.
Further, by controlling the subsequent operating state based on the virtual temperature at the start of the internal combustion engine 10, an over-rich air-fuel ratio that may occur when the control is performed based on the estimated temperature with a large error, or Problems such as plug smoldering can be avoided.

Further, in the present embodiment, in the actual temperature search process, the virtual temperature is decreased stepwise from the high temperature side toward the low temperature side, so that excessive fuel is injected with respect to the optimum fuel injection amount corresponding to the actual temperature Te. It is possible to prevent the occurrence of “fogging phenomenon” and to prevent starting failure.
For reference, Japanese Patent No. 3005818 discloses a technique for increasing / decreasing an alcohol correction coefficient obtained in accordance with the alcohol concentration in the fuel until the engine start is completed. In this technique, the alcohol correction coefficient is repeatedly increased and decreased, and the direction of increase / decrease is not constant. In contrast, the present embodiment is characterized in that the direction in which the virtual temperature is changed is fixed from the high temperature side to the low temperature side.

In the present embodiment, the virtual temperature initial value T1 is set based on the estimated temperature. For example, the estimated temperature and the actual temperature Te of the internal combustion engine 10 may be well correlated depending on the situation, for example, when the internal combustion engine 10 is restarted after a sufficient time has elapsed since the stop. In addition, even if there is an error, the estimated temperature is a temporary measure for the actual temperature Te.
Therefore, when starting the actual temperature search process, setting the temperature based on the estimated temperature as the initial value of the virtual temperature increases the possibility of starting the process from a temperature closer to the actual temperature Te. Therefore, the number of trials until the start can be reduced, and the internal combustion engine 10 can be started in a shorter time.

(Second Embodiment)
The actual temperature search process executed by the control apparatus for an internal combustion engine according to the second embodiment of the present invention will be described with reference to the flowchart of FIG.
The second embodiment is different from the first embodiment in that the temperature estimation means 71 is not provided or the estimated temperature is not used for the actual temperature search process even if the temperature estimation means 71 is provided. The configuration in which the temperature estimation means 71 is not provided is that the thermistor 74 is not provided in the control device 70 and is applied to the energization unit 72 and the coil 61 that supply the detection current to the coil 61 of the crank angle sensor 60. This is a configuration in which the voltage detection unit 73 for detecting the voltage to be detected is not provided.

In the flowchart of FIG. 11, steps that are substantially the same as those in the flowchart of FIG. 8 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
The flowchart of FIG. 11 does not have steps S11 to S14 compared to the flowchart of FIG. 8, and starts from S15B. In S15B, the virtual temperature initial value at the start of the actual temperature search process is set to a predetermined value such as 80 ° C., for example. That is, since there is no information that serves as a guideline for the actual temperature Te, the processing is started with the maximum temperature that can be assumed as a virtual temperature.
In the second embodiment, since the actual temperature search process can be executed without providing the temperature estimation means 71, the configuration of the control device 70 becomes simpler.

(Other embodiments)
(A) The start control means 78 for setting the virtual temperature is not limited to the configuration provided as part of the circuit of the control device 70, and a circuit for setting the virtual temperature may be added separately from the control device 70. Thereby, the virtual temperature can be set even when the control device 70 is abnormal.

  (A) In the actual temperature search process of the present invention, the accuracy of the temperature characteristic map is an important factor. In the above-described embodiment, a two-dimensional temperature characteristic map in which the parameter on which the optimum fuel injection amount depends is only the internal combustion engine temperature Te is used. For example, the oxygen concentration or the component concentration in the fuel is determined based on the internal combustion engine temperature Te. A temperature characteristic map of three or more dimensions considered as a parameter other than may be used. Alternatively, the control device 70 may correct the temperature characteristic map by a learning function based on the search result.

  (C) The temperature estimation means 71 for estimating the internal combustion engine temperature Te is not limited to the detection value of the thermistor 74 or the detection value of the coil resistance of the crank angle sensor 60, but the detection value of any physical quantity correlated with the internal combustion engine temperature Te. Based on the above, the internal combustion engine temperature Te may be estimated by a calculation formula, a map, or the like. For example, when detecting coil resistance, the structure of the energization part which supplies a predetermined electric current to a coil is not restricted to what was illustrated in FIG. 2, It is good also as what kind of structure.

(D) The temperature estimating means 71 is an internal combustion engine temperature Te based on an arithmetic expression using a temperature model described in a prior application (Japanese Patent Application No. 2013-85537) by the present applicant, particularly in a high rotation state after the internal combustion engine 10 is started. May be estimated. This temperature model integrates the temperature change amount ΔTe with reference to the engine ambient temperature T0. The temperature change amount ΔTe is the amount of heat obtained by subtracting the heat release amount Q1 from the combustion gas from the heat release amount Q2 from the cooling device 49. It is calculated by dividing by the heat capacity C of the engine 10. That is, it is expressed as the following formula.
Te = T0 + ΣΔTe = T0 + Σ {(Q1-Q2) / C}

(E) The control device for an internal combustion engine of the above embodiment is assumed to be applied to a scooter of a single cylinder engine, but is not limited to this, a motorcycle (motorcycle) on which a multi-cylinder engine is mounted, Or you may apply to vehicles other than a two-wheeled vehicle, and a general purpose internal combustion engine.
As mentioned above, this invention is not limited to the said embodiment at all, In the range which does not deviate from the meaning of invention, it can implement with a various form.

10 ... Internal combustion engine,
29 ... Fuel injection valve,
34. Spark plug,
70... (Internal combustion engine) control device,
71 ... temperature estimation means,
75 ... Fuel injection command means,
76 ... ignition command means,
77... Rotational speed detection means
78 ... Start control means.

Claims (11)

A control device (70) for controlling the operating state of the internal combustion engine (10),
Fuel injection command means (75) for instructing the fuel injection valve (29) the fuel injection timing and the injection amount;
Ignition command means (76) for commanding the spark plug (34) to ignite at a predetermined timing;
A rotational speed detecting means (77) for detecting the rotational speed of the internal combustion engine;
When the internal combustion engine is started, the fuel injection amount corresponding to the virtual temperature is calculated while sequentially changing the virtual temperature of the internal combustion engine, and the fuel injection command means is requested to inject the fuel at the fuel injection amount. By repeating a series of trial operations for requesting the ignition command means to ignite at the timing of at least until the start of the internal combustion engine is determined based on the rotational speed of the internal combustion engine, Start control means (78) for executing an actual temperature search process for searching for an actual temperature;
A control device for an internal combustion engine, comprising: In the actual temperature search process, the start control means
2. The control device for an internal combustion engine according to claim 1, wherein the virtual temperature is decreased stepwise from a high temperature side toward a low temperature side while being held at a constant temperature for a predetermined period.   3. The control of an internal combustion engine according to claim 2, wherein in the actual temperature search processing, fuel injection and ignition are executed a predetermined number of times while the virtual temperature is held at a constant temperature for a predetermined period. apparatus.   The control device for an internal combustion engine according to claim 3, wherein the predetermined number of trials is set to be larger as the virtual temperature is lower.   5. The temperature difference when the virtual temperature is lowered stepwise in the actual temperature search process is set to be smaller as the virtual temperature is lower. 6. Control device for internal combustion engine.   6. The control of the internal combustion engine according to claim 2, wherein, in the actual temperature search process, a lower limit value of the virtual temperature is set based on a cranking rotation speed of the internal combustion engine. apparatus. Temperature estimation means (71) for calculating an estimated temperature of the internal combustion engine based on a detected value of a physical quantity correlated with the actual temperature of the internal combustion engine;
The start control means sets an initial value of the virtual temperature at the start of the actual temperature search process based on the estimated temperature calculated by the temperature estimation means. The control device for an internal combustion engine according to one item.   8. The control apparatus for an internal combustion engine according to claim 7, wherein, in the actual temperature search process, a lower limit value of the virtual temperature is set based on the estimated temperature calculated by the temperature estimating means. When the rotational speed of the internal combustion engine reaches a predetermined value during the determination period in which the crankshaft rotates a predetermined number of times from the start of the actual temperature search process,
The start control means includes
9. The virtual temperature at the end of the actual temperature search process is corrected to a low temperature side at the stage where the actual temperature search process ends and shifts from the start to the start. The control apparatus for an internal combustion engine according to the item. The start control means includes
The trial operation is performed with a map value of the optimum fuel injection amount corresponding to the virtual temperature with reference to a first temperature characteristic map that defines the relationship between the actual temperature of the internal combustion engine and the optimum fuel injection amount that can be started by the internal combustion engine. Injection amount change mode that repeats, or
The actual temperature of the internal combustion engine,
Fuel injection amount calculated based on the map value of the correction coefficient corresponding to the virtual temperature with reference to the second temperature characteristic map that defines the relationship between the fuel injection amount = basic injection amount × the correction coefficient in the correction coefficient calculation formula Correction coefficient change mode for repeating the trial operation by an amount,
The control apparatus for an internal combustion engine according to any one of claims 1 to 9, wherein the actual temperature search process is executed in any one of the modes. The start control means includes
Applying the injection amount changing mode when the rotational speed of the internal combustion engine is less than a predetermined switching rotational speed,
11. The control apparatus for an internal combustion engine according to claim 10, wherein the correction coefficient change mode is applied when the rotational speed of the internal combustion engine exceeds the switching rotational speed.

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