WO2023037558A1

WO2023037558A1 - Control device and control method for internal combustion engine

Info

Publication number: WO2023037558A1
Application number: PCT/JP2021/033599
Authority: WO
Inventors: 透大下; 昌志古谷; 拓也宮村
Original assignee: 本田技研工業株式会社
Priority date: 2021-09-13
Filing date: 2021-09-13
Publication date: 2023-03-16

Abstract

An engine 1 can use alcohol fuel or a mixed fuel obtained by mixing alcohol fuel with hydrocarbon fuel, and a control device 30 comprises: an engine temperature sensor 36 that detects the temperature Teng of the engine 1; an outside air temperature sensor 38 that detects the temperature Tout of outside air introduced to the engine 1; and a controller 31 that controls the engine 1 in accordance with detecting a start command of the engine 1. If at least one among the engine temperature Teng and the outside air temperature Tout is equal to or less than a prescribed temperature Tth1, Tth2 when starting the engine 1, the controller 31 executes low-temperature start control for performing a prescribed number Pth of crankings in a state where fuel injection and ignition are prohibited, and thereafter performing the fuel injection and ignition.

Description

CONTROL DEVICE AND CONTROL METHOD FOR INTERNAL COMBUSTION ENGINE

The present invention relates to control technology when starting an internal combustion engine.

Patent Document 1 describes a control method for prohibiting fuel injection in an internal combustion engine that can use alcohol fuel until the amount of heat generated by the intake heater and the intake negative pressure reach or exceed a predetermined value. Patent Document 2 describes a control method for prohibiting fuel injection while closing an exhaust valve to recirculate air when the cooling water temperature is -20° C. or lower.

JP 2014-137019 A JP-A-10-288069

In order to achieve carbon neutrality, it is desirable to change the fuel used in the internal combustion engine from a hydrocarbon fuel to an alcohol fuel (e.g., 100% ethanol). There is room for improvement in the time startability. However, in the configuration in which the fuel or the intake air is heated by an electric heater as in

Patent Documents

1 and 2, the introduction of the electric heater increases the cost, and the battery capacity is reduced to match the power consumption of the electric heater. need to be bigger.

The present invention has been made in view of the above problems, and realizes a technology that can improve startability at low temperatures in an internal combustion engine that can use alcohol fuel with a low-cost configuration that does not require additional equipment.

In order to solve the above-mentioned problems, the present invention provides a control device for an internal combustion engine that can use alcohol fuel or a mixed fuel in which alcohol fuel is mixed with hydrocarbon fuel, comprising a first control device for detecting the temperature of the internal combustion engine. temperature detecting means; second temperature detecting means for detecting the temperature of outside air introduced into the internal combustion engine; and control means for controlling the internal combustion engine in response to detection of a start command for the internal combustion engine. and the control means performs cranking a predetermined number of times while prohibiting fuel injection and ignition when at least one of the temperature of the internal combustion engine and the temperature of the outside air is lower than a predetermined temperature when starting the internal combustion engine. After performing the low temperature start control for performing the fuel injection and the ignition.

Further, the present invention is a control method for an internal combustion engine capable of using an alcohol fuel or a mixed fuel obtained by mixing an alcohol fuel with a hydrocarbon fuel, wherein the internal combustion engine detects a first temperature sensor for detecting the temperature of the internal combustion engine. and a second temperature detecting means for detecting the temperature of outside air introduced into the internal combustion engine, wherein the control method controls the internal combustion engine in response to detection of a start command for the internal combustion engine. wherein, when starting the internal combustion engine, the controlling step prohibits fuel injection and ignition when at least one of the temperature of the internal combustion engine and the temperature of the outside air is equal to or lower than a predetermined temperature. After performing cranking for a predetermined number of times, the low temperature start control is executed to perform the fuel injection and the ignition.

According to the present invention, it is possible to realize a technology that can improve startability at low temperatures in an internal combustion engine that can use alcohol fuel with a low-cost configuration that does not require additional equipment.

Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar configurations are given the same reference numerals.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
FIG. 1 is a schematic cross-sectional view schematically showing the configuration of essential parts of an internal combustion engine of this embodiment. FIG. 2 is a block diagram showing the configuration of the control device for the internal combustion engine of this embodiment. FIG. 3 is a flowchart showing start control of the internal combustion engine according to this embodiment. FIG. 4 is a flowchart showing the low temperature start control of the internal combustion engine of this embodiment. FIG. 5 is a flow chart showing normal starting control of the internal combustion engine of this embodiment. FIG. 6 is a timing chart showing the operation during low temperature start control in this embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined arbitrarily. Also, the same or similar configurations are denoted by the same reference numerals, and redundant explanations are omitted.

The control device for an internal combustion engine of this embodiment is applied to a spark ignition engine as an internal combustion engine. The engine is, for example, a four-cycle engine that undergoes four strokes of intake, expansion, compression and exhaust during an operating cycle (one cycle). In order to achieve carbon neutrality, the engine can use alcohol fuel such as ethanol, but it can also use a mixed fuel in which a predetermined percentage (eg, 85%) of alcohol is mixed with gasoline.

In the present embodiment, an example of a control device for an engine mounted on a saddle type vehicle such as a motorcycle will be described, but the present invention is not limited to this, and can be used for three-wheeled vehicles, four-wheeled vehicles (regular automobiles, light automobiles, trucks, etc.). The present invention can also be applied to control devices for engines mounted on moving bodies other than vehicles, such as vehicles and ships (including outboard motors), and working machines such as shovels and bulldozers.

FIG. 1 is a cross-sectional view schematically showing the main configuration of an engine 1 that is applied to the internal combustion engine control device of this embodiment. Although the engine 1 is a multi-cylinder engine, FIG. 1 shows only a single cylinder. As shown in FIG. 1, an engine 1 includes a plurality of cylinders 3 formed in a cylinder block 2, pistons 4 slidably arranged inside the cylinders 3, and pistons 4 and a cylinder head 5 formed between the pistons 4 and the cylinder head 5. and a combustion chamber 6 . The piston 4 is connected to a crankshaft 8 via a connecting rod 7 , and reciprocating motion of the piston 4 along the inner wall of the cylinder 3 causes the crankshaft 8 to rotate. A circulation path for circulating cooling water for cooling the engine 1 may be formed on the inner wall of the cylinder 3 in some cases.

The cylinder head 5 is provided with an intake port 10 and an exhaust port 11 . The combustion chamber 6 is communicated with an intake passage 12 via an intake port 10 and communicated with an exhaust passage 13 via an exhaust port 11 . The intake port 10 is opened and closed by an intake valve 14 and the exhaust port 11 is opened and closed by an exhaust valve 15 . A throttle valve 16 and an injector 17 are provided in the intake passage 12 on the upstream side of the intake valve 14 . The injector 17 is arranged on the side surface of the intake passage 12 on the downstream side of the throttle valve 16 with the fuel injection opening directed toward the intake port 10 .

The throttle valve 16 is composed of, for example, a butterfly valve, and adjusts the amount of intake air flowing into the combustion chamber 6 by the throttle valve 16 . The throttle valve 16 is driven by a throttle actuator such as an electric motor. The intake valve 14 and the exhaust valve 15 are driven to open and close at predetermined timing synchronized with the rotation of the crankshaft 8 by a valve mechanism (not shown). The opening and closing timings of the intake valve 14 and the exhaust valve 15 can be changed as appropriate.

The injector 17 is driven by a control signal from a controller 31, which will be described later with reference to FIG. The fuel injection amount from the injector 17 is controlled according to the intake air amount of the engine 1 so that the actual air-fuel ratio (intake air amount A/fuel injection amount F) becomes the theoretical air-fuel ratio corresponding to the alcohol concentration. The injector 17 is driven by, for example, a piezo actuator and has high responsiveness. The injector 17 is not limited to being arranged in the intake passage 12, but may be arranged in the cylinder block 2 or the cylinder head 5 so as to face the inside of the combustion chamber 6 as an in-cylinder fuel injection valve. There may be.

A spark plug 18 is attached to each cylinder head 5 so as to face the combustion chamber 6 of the cylinder 3 . The spark plug 18 is arranged between the intake port 10 and the exhaust port 11 and generates a spark by electric energy to ignite the mixture of fuel and air inside the combustion chamber 6 .

The exhaust passage 13 is provided with an exhaust purification device 19 having a three-way catalyst or the like for purifying exhaust gas.

As in the engine 1 of the present embodiment, when alcohol fuel or a mixed fuel with a high alcohol concentration is used to achieve carbon neutrality, for example, the temperature of the engine 1 (cooling water temperature, lubricating oil temperature, etc.) or the outside air temperature In the low temperature state, the fuel injected from the injector 17 is difficult to evaporate, and the alcohol fuel has low ignitability at low temperatures, so there is a risk that startability at low temperatures will deteriorate.

Therefore, in the present embodiment, even when alcohol fuel is used, startability at low temperatures is improved by low temperature start control executed by the control device 30 for the internal combustion engine, which will be described below, and carbon neutrality is realized. can be done.

FIG. 2 is a block diagram showing the configuration of the internal combustion engine control device 30 of this embodiment. As shown in FIG. 2, the control device 30 has a controller 31, and outputs control signals to the throttle valve 16, the injector 17, and the spark plug 18 based on signals detected by various sensors connected to the controller 31. do. Further, the controller 31 controls the opening of the throttle valve 16, the fuel injection of the injector 17, and the ignition of the spark plug 18 in starting control of the engine 1, which will be described later with reference to FIG. It controls lighting/lighting out of the

indicators

22 and 23 .

The controller 31 is a computer configured by an electronic control unit (ECU) and including a CPU 31a, a ROM 31b, a RAM 31c, an I/O interface (IF) 31d and other circuits.

Sensors connected to the controller 31 include a crank angle sensor 32, an intake sensor 33, an exhaust gas sensor 34, a water temperature sensor 35, an engine temperature sensor 36, a vehicle speed sensor 37 and an outside air temperature sensor 38.

The crank angle sensor 32 is provided in the crankcase of the cylinder block 2 and outputs a pulse signal as the crankshaft 8 rotates. The controller 31 calculates the engine speed based on the pulse signal output from the crank angle sensor 32 . The controller 31 also calculates the number of times of cranking in the low temperature start control of the engine 1 described later with reference to FIG. 4 based on the pulse signal output from the crank angle sensor 32 .

Based on the signal output from the crank angle sensor 32, the controller 31 determines the crank angle at the start of the intake stroke of the cylinder 3, that is, the crank angle ( phase). The intake stroke crank angle is the crank angle when the piston 4 descends from the top dead center (TDC) to the bottom dead center (BDC), and is determined within the range of 0° to 180°. The compression stroke crank angle is the crank angle when the piston 4 rises from the bottom dead center to the top dead center, and is determined within the range of 180° to 360°.

The intake sensor 33 is provided on the downstream side of the throttle valve 16 in the intake passage 12, and is composed of a pressure sensor, an air flow meter that detects the amount of intake air, a throttle opening sensor that detects the throttle opening, and the like. The controller 31 calculates the intake pressure or intake air amount on the downstream side of the throttle valve 16 based on the signal output from the intake sensor 33 .

The exhaust gas sensor 34 is provided in the exhaust passage 13 and is composed of an air-fuel ratio sensor, an oxygen sensor, or the like that detects the air-fuel ratio or rich/lean of the exhaust gas of the engine 1 . An exhaust purification device 19 is provided downstream of the exhaust gas sensor 34 . Controller 31 calculates the actual air-fuel ratio based on the signal output from exhaust gas sensor 34 .

The water temperature sensor 35 is provided in the circulation path through which the cooling water of the engine 1 circulates, and is composed of a temperature sensor or the like that detects the temperature of the cooling water. The controller 31 calculates the temperature of the cooling water of the engine 1 (engine water temperature) from the signal output from the water temperature sensor 35 . Although not shown, the controller 31 is also connected to an accelerator opening sensor for detecting the amount of operation of the accelerator pedal (accelerator opening).

The engine temperature sensor 36 is provided in the oil pan or oil filter and is composed of a temperature sensor or the like that detects the temperature of the engine oil. The controller 31 calculates the temperature of the engine 1 based on the signal output from the engine temperature sensor 36 . If a long time has passed since the engine 1 was stopped and the temperature of the engine 1 is approximately the same as the coolant temperature, the coolant temperature of the engine 1 detected by the coolant temperature sensor 35 You may calculate the temperature of the engine 1 based on. Further, when a long time has passed since the engine 1 was stopped and the temperature of the engine 1 is approximately the same as the temperature of the outside air, the temperature of the outside air detected by the outside temperature sensor 38, which will be described later, is used. The temperature of the engine 1 may be calculated by

The vehicle speed sensor 37 outputs a pulse signal accompanying rotation of the wheels or axles according to the speed of the vehicle in which the engine 1 is mounted. Controller 31 calculates the speed of the vehicle based on the pulse signal output from vehicle speed sensor 37 .

The outside air temperature sensor 38 is provided at a position that is not affected by the heat of the engine 1 or direct sunlight, and is composed of a temperature sensor or the like that detects the outside air temperature. The controller 31 calculates the outside air temperature of the vehicle based on the signal output by the outside air temperature sensor 38 . A temperature sensor may be added to the intake sensor 33 and the outside air temperature of the vehicle may be calculated based on the intake air temperature detected by the intake sensor 33 . Further, when a long time has passed since the engine 1 was stopped and the temperature of the cooling water for the engine 1 is approximately the same as the temperature of the outside air, the cooling of the engine 1 detected by the water temperature sensor 35 The outside air temperature of the vehicle may be calculated based on the water temperature.

A power supply circuit 39 that detects the output voltage of the battery 40 is also connected to the controller 31 .

A signal is also input to the controller 31 from the starter switch 20 operated by the user (occupant) when starting the engine 1 . When the starter switch 20 is turned on and a signal instructing the start of the engine 1 is input, the controller 31 starts start control of the engine 1, which will be described later with reference to FIG. The starter switch 20 is a start assisting unit for inputting a start command for the engine 1 to the controller 31. For example, it is a push button type switch, but it is an ignition switch of a type in which a key is inserted into a key cylinder. good too.

The cranking mechanism 21 is composed of a starter motor, a flywheel, etc. that rotate (crank) the crankshaft 8 when the starter switch 20 is turned on and a signal instructing the start of the engine 1 is input.

The controller 31 controls lighting/extinguishing of the low temperature start indicator 22 and the start failure indicator 23 provided on the meter panel (not shown). The low temperature start indicator 22 is composed of an LED, a liquid crystal display, or the like that is lit during low temperature start control, which will be described later with reference to FIG. The start impossibility indicator 23 is composed of an LED, a liquid crystal display, or the like that lights up during fail control, which will be described later with reference to FIG.

<Starting Control of Engine 1>
Next, with reference to FIG. 3, start control of the engine 1 of this embodiment will be described.

FIG. 3 is a flowchart showing an example of the start control process for the engine 1 of this embodiment. 3 is realized by the CPU executing a program stored in the ROM of the controller 31 and controlling the

indicators

22 and 23, the throttle valve 16, the injector 17, the spark plug 18 and the cranking mechanism 21. be.

In this embodiment, the user continues to press the starter switch 20 until the engine 1 is started in the start control of the engine 1 in FIG. 3, and cranking is performed while the starter switch 20 is being pressed. However, once the starter switch 20 is pressed by the user, cranking is continued even if the starter switch 20 is not pressed thereafter, so-called one-push start configuration may be used.

In step S1, the controller 31 waits until the starter switch 20 is turned on and a signal instructing the start of the engine 1 is input. When the controller 31 determines that the starter switch 20 is turned on, the process proceeds to step S3.

In step S3, the controller 31 reads the signals output from the various sensors 32-38 in FIG.

In step S5, the controller 31 determines whether the vehicle speed V is zero based on the signal detected by the vehicle speed sensor 37. If the controller 31 determines that the vehicle speed V is zero, the process proceeds to step S7, and if it determines that the vehicle speed is not zero, the controller 31 ignores the command to start the engine 1 in step S1, and proceeds to the flowchart of FIG. End the process.

In step S7, based on the signal detected by the engine temperature sensor 36, the controller 31 determines whether the engine temperature Teng is equal to or less than a predetermined temperature threshold value Tth1. If the controller 31 determines that the engine temperature Teng is equal to or lower than the predetermined temperature threshold Tth1, the process proceeds to step S9, and if it determines that the engine temperature Teng is higher than the predetermined temperature threshold Tth1, the process proceeds to step S23. proceed to Note that the threshold Tth1 of the engine temperature Teng is set to 5° C. or less, for example.

In step S9, the controller 31 determines whether the outside air temperature Tout is equal to or lower than a predetermined temperature threshold Tth2 based on the signal detected by the water temperature sensor 35 or the outside air temperature sensor 38. If the controller 31 determines that the outside air temperature Tout is equal to or lower than the predetermined temperature threshold Tth2, the process proceeds to step S11, and if it determines that the outside air temperature Tout is higher than the predetermined temperature threshold Tth2, the process proceeds to step S23. proceed to Note that the threshold Tth2 of the outside air temperature Tout is set to, for example, 5° C. or less.

In step S11, the controller 31 lights the low temperature start indicator 22 to notify the user that the low temperature start control will start. As a result, the user can be made to recognize that the low-temperature start is being performed, and that the starter switch 20 needs to be kept pressed. Also, in the case of the one-push start configuration, it is possible to make the user aware that it is necessary to wait because the engine is being started at a low temperature.

In step S13, the controller 31 determines whether the output voltage Vbat of the battery 40 detected by the power supply circuit 39 is equal to or higher than a predetermined voltage threshold Vth. When the controller 31 determines that the output voltage Vbat of the battery 40 is equal to or higher than the predetermined voltage threshold Vth, the process proceeds to step S15, and determines that the output voltage Vbat of the battery 40 is less than the predetermined voltage threshold Vth. If so, the process proceeds to step S21. Note that the threshold Vth of the output voltage Vbat of the battery 40 is set to, for example, the voltage (eg, 5 V) immediately before the battery 40 runs out. As described above, when the output voltage Vbat of the battery 40 is lower than a predetermined value, the low temperature start control is not executed, thereby suppressing the consumption of the battery 40 . In this way, it is possible to determine that the engine 1 cannot be started before starting the low temperature start control, so unnecessary discharging of the battery 40 can be avoided.

At step S15, the controller 31 starts the low temperature start control of the engine 1. Details will be described later with reference to FIG.

In step S17, the controller 31 turns off the low temperature start indicator 22 and notifies the user that the low temperature start control has ended. This makes it possible for the user to recognize that the low temperature start control has ended and that it is no longer necessary to keep pressing the starter switch 20 . Moreover, in the case of the one-push start configuration, it is possible to make the user aware that there is no longer a need to wait because the engine is being started at low temperature.

At step S19, the controller 31 shifts to idling operation.

At step S21, the controller 31 starts fail control. In fail control, the controller 31 turns on the start-disabled indicator 23 and ends the processing of the flowchart of FIG. Thus, the user can be notified that the engine 1 cannot be started because the output voltage Vbat of the battery 40 is low. Since both the low-temperature start indicator 22 and the start-disabled indicator 23 are lit, the engine 1 cannot be started because the engine temperature Teng and the outside air temperature Tout are low and the output voltage Vbat of the battery 40 is low. The user can be made to recognize that. Further, when the engine temperature Teng and the outside air temperature Tout become high, only the indicator 23 when the start is impossible lights up, so that the user is made aware that the engine 1 cannot be started because the output voltage Vbat of the battery 40 is low. be able to. It should be noted that a warning light such as a battery mark or a lamp may be turned on or blinked to notify the user that the battery voltage is low, instead of using the start-disabled indicator 23 .

In step S23, the controller 31 starts normal engine 1 startup control. Details will be described later with reference to FIG.

<Low temperature start control of engine 1>
Next, the low temperature start control of the engine 1 in step S15 of FIG. 3 will be described with reference to FIG.

FIG. 3 is a flowchart showing an example of the low temperature start control process for the engine 1 in step S15 of FIG.

At step S31, the controller 31 determines whether or not the starter switch 20 that was turned on at step S1 in FIG. 3 is turned off. If the controller 31 determines that the starter switch 20 is not turned off, the process proceeds to step S33, and if it determines that the starter switch 20 is turned off, the process proceeds to step S45. In the case of the one-push start configuration, the process of step S33 is executed without making the determination of step S31.

In step S33, the controller 31 fully opens the throttle valve 16 to prohibit fuel injection from the injector 17 and ignition from the spark plug 18.

At step S35, the controller 31 drives the starter motor of the cranking mechanism 21 to start cranking.

In step S37, based on the pulse signal detected by the crank angle sensor 32, the controller 31 waits until the number of times of cranking P reaches or exceeds the threshold value Pth of the predetermined number of times. When the controller 31 determines that the number of times of cranking P has reached or exceeded the predetermined number of times threshold value Pth, the process proceeds to step S39.

In step S39, the controller 31 starts fuel injection from the injector 17 and ignition from the spark plug 18 while keeping the opening of the throttle valve 16 fully open.

In step S41, the controller 31 determines whether or not the engine speed Ne is greater than or equal to a predetermined engine speed threshold value Nth. If the controller 31 determines that the engine speed Ne is equal to or greater than the predetermined speed threshold Nth, the process proceeds to step S43, and if it determines that the engine speed Ne is less than the predetermined speed threshold Nth. advances the process to step S45.

At step S43, the controller 31 stops driving the starter motor of the cranking mechanism 21, ends the cranking started at step S35, and proceeds to step S17 in FIG.

In step S45, the controller 31 turns off the low temperature start indicator 22 that was lit in step S11 of FIG. 3, notifies the user that the low temperature start control has ended, and ends the processing of the flowcharts of FIGS. 3 and 4. .

FIG. 6 is a timing chart showing the operation during low temperature start control in this embodiment.

According to the low-temperature start control of the engine 1 of the present embodiment, in order to achieve carbon neutrality, after receiving a command to start the engine 1, the controller 31 controls the engine temperature Teng and the outside air temperature Tout while the vehicle speed V is zero. is equal to or lower than predetermined temperatures Tth1 and Tth2, the throttle valve 16 is fully opened, fuel injection from the injector 17 and ignition of the spark plug 18 are prohibited, and cranking is performed a predetermined number of times Pth by the cranking mechanism 21. Fuel injection of the injector 17 and ignition of the ignition plug 18 are started.

The number of times of cranking corresponds to the number of revolutions of the crankshaft 8, and the threshold value Pth of the number of times of cranking is set to a number of revolutions that can be driven within 5 to 10 seconds (for example, 5 to 6 revolutions). , the outside air temperature Tout, and the output voltage Vbat of the battery 40 exceed the threshold values Tth1, Tth2, and Vth, respectively. Although the number of times of cranking is determined in step S37 of FIG. 4, the period of cranking (5 to 10 seconds) may be determined.

In order to achieve carbon neutrality in the low temperature start control of the present embodiment, the controller 31 performs cranking a predetermined number of times Pth, and then gradually increases the amount of fuel injected from the injector 17 to achieve the optimal fuel consumption during normal start control. Control is performed so as to shift to the air-fuel ratio (F1<F2<F3). In particular, the fuel injection amount F1 at the beginning of fuel injection is made smaller than the fuel injection amount for the optimum air-fuel ratio during normal start control, thereby improving the low-temperature ignitability. Thus, by minimizing the amount of fuel injection necessary for starting the engine 1 and minimizing the latent heat of vaporization of the fuel when starting the engine 1 at a low temperature, excessive cooling of the combustion chamber 6 due to fuel injection is suppressed. be able to. As a result, the low-temperature ignitability can be improved when alcohol fuel is used to achieve carbon neutrality.

The air-fuel ratio A/F, cranking number P or cranking period, ignition timing, fuel injection timing, etc. in the low temperature start control of FIG. set.

As described above, according to the low temperature start control of the present embodiment, the air inside the combustion chamber 6 is compressed by cranking without using a heater, and the temperature of the air near the spark plug 18 is increased. In order to achieve this, it is possible to improve the low-temperature ignitability in the case of using the alcohol fuel. In addition, since no heater is used, carbon neutrality can be achieved with a low-cost configuration that does not require additional equipment or the like. In the present embodiment, the low temperature start control is executed when both the engine temperature Teng and the outside air temperature Tout are equal to or lower than the predetermined temperatures Tth1 and Tth2. Since the temperature Teng of the engine 1 may be approximately the same temperature as the outside air temperature Tout, when at least one of the engine temperature Teng and the outside air temperature Tout is equal to or lower than the predetermined temperatures Tth1, Tth2, the low temperature You may make it perform starting control.

<Normal Start Control of Engine 1>
Next, normal start control of the engine 1 in step S23 of FIG. 3 will be described with reference to FIG.

FIG. 5 is a flowchart showing an example of normal start control processing for the engine 1 in step S23 of FIG.

At step S51, the controller 31 determines whether the starter switch 20 that was turned on at step S1 in FIG. 3 is turned off. If the controller 31 determines that the starter switch 20 is not turned off, the process proceeds to step S53, and if it is determined that the starter switch 20 is turned off, the process of the flowcharts of FIGS. 3 and 4 is terminated. In the case of the one-push start configuration, the process of step S53 is executed without making the determination of step S51.

At step S53, the controller 31 drives the starter motor of the cranking mechanism 21 to start cranking.

In step S55, the controller 31 fully opens the throttle valve 16 and starts fuel injection from the injector 17 and ignition from the spark plug 18.

In step S57, the controller 31 determines whether or not the engine speed Ne is greater than or equal to a predetermined engine speed threshold value Nth. If the controller 31 determines that the engine speed Ne is equal to or greater than the predetermined speed threshold Nth, the process proceeds to step S59; if it determines that the engine speed Ne is less than the predetermined speed threshold Nth, ends the processing of the flow charts of FIGS.

At step S59, the controller 31 stops driving the starter motor of the cranking mechanism 21, ends the cranking started at step S53, and proceeds to step S19 in FIG.

[Summary of embodiment]
<First Aspect>
A control device 30 for an internal combustion engine 1 that can use an alcohol fuel or a mixed fuel in which an alcohol fuel is mixed with a hydrocarbon fuel,
a first temperature detection means 36 for detecting the temperature Teng of the internal combustion engine 1;
a second temperature detection means 38 for detecting an outside air temperature Tout introduced into the internal combustion engine 1;
A control means 31 for controlling the internal combustion engine 1 in response to detection of a start command for the internal combustion engine 1,
When starting the internal combustion engine 1, the control means 31 prohibits fuel injection and ignition when at least one of the engine temperature Teng and the outside air temperature Tout is equal to or lower than predetermined temperatures Tth1 and Tth2. After performing cranking for a predetermined number of times Pth, the low temperature start control is executed to perform the fuel injection and the ignition.

According to the first aspect, since the air inside the combustion chamber is compressed and heated by cranking without using a heater, low-temperature ignitability can be improved when alcohol fuel is used to achieve carbon neutrality. can be done. In addition, since no heater is used, carbon neutrality can be achieved with a low-cost configuration that does not require additional equipment or the like.

<Second Aspect>
In the first mode, in the low temperature start control, the control means 31 controls to gradually increase the fuel injection amount when starting the fuel injection after the predetermined number of times of cranking Pth.

According to the second aspect, by minimizing the amount of fuel injection required for starting the internal combustion engine 1 and minimizing the latent heat of vaporization of the fuel at the time of starting the internal combustion engine 1, the excess of the combustion chamber due to fuel injection is reduced. cooling can be suppressed.

<Third Aspect>
In the first or second aspect, the first indicator 22 is provided to notify the occupant of the low temperature start control state. The first indicator 22 notifies that the low temperature start control is to be executed when the temperatures Tth1, Tth2 or lower.

According to the third aspect, it is possible to make the user aware that it is time to start at low temperatures, and to make the user aware that it is necessary to continue the operation to start starting the internal combustion engine 1 . Also, in the case of the one-push start configuration, it is possible to make the user aware that it is necessary to wait because the engine is being started at a low temperature.

<Fourth Aspect>
In any one of the first to third aspects, a start assist means 20 for receiving a user operation for inputting a start command for the internal combustion engine 1 to the control means 31,
The control means 31 performs the cranking while the starting assist means 20 is being operated.

According to the fourth aspect, it is possible to make the user aware that it is necessary to continue the operation to start starting the internal combustion engine 1 .

<Fifth Aspect>
In any one of the first to third aspects, a start assist means 20 for receiving a user operation for inputting a start command for the internal combustion engine 1 to the control means 31,
The cranking is performed in response to the operation of the starting assist means 20 .

According to the fifth aspect, it is possible to make the user aware that it is necessary to wait because the engine is being started at low temperature.

<Sixth Aspect>
In the third aspect, the control means 31 comprises a second indicator 23 that indicates that the internal combustion engine 1 cannot be started, and a battery 40 that supplies electric power for the cranking. , when the voltage of the battery 40 is lower than a predetermined threshold value Vth, it is determined that the internal combustion engine 1 cannot be started, and the second indicator 23 notifies that the low temperature start control is not executed.

According to the sixth aspect, the user can be notified that the internal combustion engine 1 cannot be started because the output voltage Vbat of the battery 40 is low. Further, since both the low-temperature start indicator 22 and the unstartable indicator 23 are lit, at least one of the temperature Teng of the internal combustion engine 1 and the outside air temperature Tout is low and the output voltage Vbat of the battery 40 is low. The user can be made aware that 1 start-up is not possible. Further, when at least one of the temperature Teng of the internal combustion engine 1 and the outside air temperature Tout becomes high, only the indicator 23 for when the engine cannot be started lights up. A user can be made to recognize that there is.

<Seventh Aspect>
A control method (FIG. 3) for an internal combustion engine 1 capable of using an alcohol fuel or a mixed fuel in which an alcohol fuel is mixed with a hydrocarbon fuel,
The internal combustion engine 1 is
a first temperature detection means 36 for detecting the temperature Teng of the internal combustion engine 1;
a second temperature detection means 38 for detecting an outside air temperature Tout introduced into the internal combustion engine;
The control method (Fig. 3) comprises:
A step (step S15) of controlling the internal combustion engine in response to detection of a start command for the internal combustion engine 1;
In the controlling step (step S15), when the internal combustion engine 1 is started and at least one of the temperature Teng of the internal combustion engine 1 and the outside air temperature Tout is equal to or lower than predetermined temperatures Tth1 and Tth2, fuel injection and After performing cranking for a predetermined number of times Pth in a state in which ignition is prohibited, low-temperature start control is executed in which the fuel injection and the ignition are performed.

According to the seventh aspect, since the air in the combustion chamber is compressed and heated by cranking without using a heater, low-temperature ignitability can be improved when alcohol fuel is used to achieve carbon neutrality. can be done. In addition, since no heater is used, carbon neutrality can be achieved with a low-cost configuration that does not require additional equipment or the like.

In the present invention, a computer program corresponding to the start control of the engine 1 of the embodiment described above and a storage medium storing the computer program are supplied to a computer mounted on a vehicle, and the computer stores the computer program in the storage medium. The stored program code may be read and executed.

The invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the invention.

1... Engine (internal combustion engine)
Reference Signs List 2 Cylinder block 3 Cylinder 4 Piston 5 Cylinder head 6 Combustion chamber 7 Connecting rod 8 Crankshaft 10 Intake port 11 Exhaust port 12 Intake passage 13 Exhaust passage 14 Intake valve 15 Exhaust valve 16 ... Throttle valve 17 ... Injector 18 ... Spark plug 19 ... Exhaust purification device 20 ... Starter switch (starting auxiliary means)
21... Cranking mechanism 22... Low temperature start indicator (first indicator)
23 . . . Inability to start indicator (second indicator)
30... Control device 31... Controller (control means)
32... crank angle sensor 33... intake sensor 34... exhaust gas sensor 35... water temperature sensor 36... engine temperature sensor (first temperature detection means)
37... vehicle speed sensor 38... outside air temperature sensor (second temperature detection means)
39 power supply circuit 40 battery

Claims

A control device for an internal combustion engine capable of using an alcohol fuel or a mixed fuel obtained by mixing an alcohol fuel with a hydrocarbon fuel,
a first temperature detection means for detecting the temperature of the internal combustion engine;
a second temperature detection means for detecting the temperature of outside air introduced into the internal combustion engine;
a control means for controlling the internal combustion engine in response to detection of a start command for the internal combustion engine;
When starting the internal combustion engine, the control means performs cranking a predetermined number of times while prohibiting fuel injection and ignition when at least one of the temperature of the internal combustion engine and the temperature of the outside air is lower than a predetermined temperature. A control device for an internal combustion engine, characterized in that it executes low temperature start control in which the fuel injection and the ignition are performed after the fuel injection and the ignition.
2. In the low temperature start control, the control means controls to gradually increase the fuel injection amount when starting the fuel injection after the predetermined number of crankings. Control device for an internal combustion engine as described.
A first indicator that informs the occupant of the cold start control state,
3. The control means, when at least one of the temperature of the internal combustion engine and the temperature of the outside air is below a predetermined temperature, notifies the execution of the low temperature start control by means of the first indicator. 3. The control device for an internal combustion engine according to 1 or 2.
starting assist means for receiving a user operation for inputting a start command for the internal combustion engine to the control means;
4. The control apparatus for an internal combustion engine according to claim 1, wherein said control means performs said cranking while said starting assist means is being operated.
starting assist means for receiving a user operation for inputting a start command for the internal combustion engine to the control means;
4. The control apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein said cranking is performed in response to said start assist means being operated.
a second indicator indicating that the internal combustion engine cannot be started;
A battery that supplies power for performing the cranking,
When the voltage of the battery is lower than a predetermined threshold, the control means determines that the internal combustion engine cannot be started, and notifies by the second indicator that the low temperature start control is not executed. 4. A control device for an internal combustion engine according to claim 3.
A control method for an internal combustion engine capable of using an alcohol fuel or a mixed fuel obtained by mixing an alcohol fuel with a hydrocarbon fuel,
The internal combustion engine is
a first temperature detection means for detecting the temperature of the internal combustion engine;
a second temperature detection means for detecting the temperature of outside air introduced into the internal combustion engine;
The control method is
comprising a step of controlling the internal combustion engine in response to detecting a start command for the internal combustion engine;
In the controlling step, when starting the internal combustion engine, when at least one of the temperature of the internal combustion engine and the temperature of the outside air is equal to or lower than a predetermined temperature, cranking is performed a predetermined number of times while fuel injection and ignition are prohibited. A control method for an internal combustion engine, characterized by executing low-temperature start control in which the fuel injection and the ignition are performed after performing the above.