JP7542924B2 - Control device for internal combustion engine - Google Patents

Description

The present invention relates to a control device that controls the operation of an internal combustion engine mounted on a vehicle, etc.

Recently, hybrid vehicles equipped with two power sources, an internal combustion engine and an electric motor, have become popular. In a series-type hybrid vehicle (see, for example, Patent Document 1 below), the internal combustion engine drives a power generating motor generator to generate electricity, and the generated electricity is stored in a power storage device, i.e., a battery such as a lithium-ion secondary battery or a nickel-hydrogen secondary battery and/or a capacitor, and is also supplied to a driving motor generator. The driving motor generator then rotates the drive wheels of the vehicle to drive it.

Not only the power generation motor generator, but also the driving motor generator can generate electricity through regenerative braking and store the generated electricity in a power storage device. If the power storage device is already full of charge, the power obtained through regenerative braking is supplied to the power generation motor generator, which is operated as an electric motor to rotate and drive the internal combustion engine, thereby consuming surplus electricity.

When the amount of charge stored in the power storage device decreases or when the required output from the driving motor generator is large, the internal combustion engine is started, fuel is supplied to its cylinders and burned, and the power generating motor generator is driven by the rotational driving force output by the internal combustion engine, generating electricity to charge the power storage device or to increase the power supplied to the driving motor generator.

The power generating motor generator also serves the role of motoring, or cranking, the internal combustion engine in preparation for starting the stopped internal combustion engine. During cranking, the necessary power is supplied from the power storage device.

In a hybrid vehicle, the driving motor generator can consume the electric charge stored in the power storage device to output rotational driving force and run the vehicle even without firing the internal combustion engine. Therefore, even when the vehicle is in operation, the internal combustion engine may continue to be stopped from rotating. On the other hand, when the internal combustion engine is fired, it is often operated continuously in a relatively high-load operating range with good thermal efficiency.

In general, when an internal combustion engine is operated at idle (no load) or at a low load similar to this, a learning control is implemented to quickly bring the engine speed into line with the desired target idle speed (see, for example, Patent Document 2 below).

Specifically, the electronic throttle valve, which is an intake throttle valve, is expanded or contracted to reduce the deviation between the actual engine speed and the target idle speed, and when it is confirmed that the actual speed has converged to the target speed (when the deviation has been maintained within a predetermined error for a predetermined period of time), the throttle valve opening at that point is stored and held as a learned value. Then, when the engine later transitions back to idle or low-load operation, the throttle valve opening is operated to the previously learned learned value, thereby quickly changing the engine speed toward the target speed.

The crank chamber of an internal combustion engine is isolated from the combustion chamber by the inner wall of the cylinder bore and the piston. However, this isolation is not complete, and unburned gas leaks into the crank chamber from the gap between the inner wall of the bore and the piston during the compression stroke of the internal combustion engine, and burned gas leaks into the crank chamber from the gap between the inner wall of the bore and the piston during the expansion stroke. The leaked blow-by gas causes corrosion of the internal combustion engine body and deterioration of the lubricating oil stored in the oil pan. For this reason, it is common for internal combustion engines to be equipped with a device that ventilates the blow-by gas that accumulates in the crank chamber (see, for example, Patent Document 3 below).

The blow-by gas recirculation device includes a blow-by passage (air passage) that connects the cam chamber contained in the cylinder head and cylinder head cover to the intake passage downstream of the air cleaner and upstream of the throttle valve, a PCV passage that connects the crank chamber in the crankcase to the intake passage downstream of the throttle valve, and a PCV valve that opens and closes the PCV passage. Blow-by gas in the crank chamber is sent to the intake passage via the PCV passage. Air supplied from the blow-by passage to the cam chamber flows through the chain cover (chain case) chamber and into the crank chamber. This scavenges the blow-by gas in the chain cover chamber and the crank chamber.

JP 2020-156134 A JP 2015-086708 A JP 2020-051371 A

Naturally, learning the throttle valve opening when the internal combustion engine is idling or operating at low load is carried out during firing operation in such a low rotation and low load range. In non-hybrid vehicles, i.e. conventional vehicles that run solely by inputting engine torque output by the internal combustion engine to the drive wheels, there are many opportunities for idling while the vehicle is stopped, making it possible to carry out learning at any time. In contrast, in hybrid vehicles, efforts are made to keep the internal combustion engine stopped and not operated as much as possible, so there are few opportunities to perform idling in the first place. This makes it difficult to carry out learning at any time.

The throttle valve opening suitable for idling or low-load operation is influenced to a certain extent by the atmospheric pressure at that time. This is because the lower the atmospheric pressure, the less air, i.e., oxygen, is supplied to the cylinder. Another reason is that the flow rate of blow-by gas recirculated through the blow-by gas recirculation device depends on the atmospheric pressure. At high altitudes where the atmospheric pressure is low, more blow-by gas flows into the intake passage. In particular, internal combustion engines mounted on hybrid vehicles tend to continue operating in the high-load range, and a large amount of blow-by gas accumulates in the crank chamber, which tends to increase the flow rate of blow-by gas accordingly.

If the learning values learned at low altitudes are used for idling or low-load operation at high altitudes, the throttle valve opening will be reduced more than the appropriate value, causing an insufficient amount of intake air (and fuel injection amount) to fill the cylinder, raising concerns that this will lead to an undesirable drop in engine speed. Conversely, if the learning values learned at high altitudes are used for idling or low-load operation at low altitudes, the throttle valve opening will be increased more than the appropriate value, causing an excessive amount of intake air, unnecessarily increasing engine speed and fuel consumption.

In addition, when learning the throttle valve opening for idle or low-load operation, operating the throttle valve at the same speed at high altitudes as at low altitudes can cause large fluctuations in the intake volume, which can lead to hunting in the engine speed. At high altitudes, where atmospheric pressure is low, the rate at which the amount of air taken into the cylinder changes as a result of operating the throttle valve is greater than at low altitudes, where atmospheric pressure is high.

The present invention was developed with the above in mind, and aims to appropriately learn the throttle valve opening when the internal combustion engine is operating at idle or low load, taking into account the altitude of the vehicle's location, i.e., the atmospheric pressure, thereby stabilizing idle or low load operation.

The present invention is a control device for controlling an internal combustion engine of a vehicle which includes an internal combustion engine, a power generation motor generator driven by the internal combustion engine to generate power, an electricity storage device for storing the power generated by the power generation motor generator, and a traction motor generator which receives power from the power generation motor generator or the electricity storage device to drive drive wheels of the vehicle, and which learns an opening degree of a throttle valve suitable for bringing the engine speed close to a target idle speed when the internal combustion engine is operated at idle or at a low load close to idle , and the learning is performed by controlling an ignition switch (or a power switch, an ignition The learning process is executed at least once during the period from when an ignition key is turned ON to when it is turned OFF, and the control device stores and holds a learned value of the throttle valve opening when the learning was performed and information on the atmospheric pressure detected via the atmospheric pressure sensor when the learning was performed. The control device judges whether or not the absolute value of the difference between the current atmospheric pressure detected via the atmospheric pressure sensor and the atmospheric pressure when the learning was performed exceeds a threshold value, and if the threshold value is exceeded, the control device performs re-learning using the learned value as an initial value for the throttle valve opening and changes the control in the learning.

The present invention also provides a control device for controlling an internal combustion engine of a vehicle which includes an internal combustion engine, a power generation motor generator driven by the internal combustion engine to generate electricity, an electricity storage device for storing the electricity generated by the power generation motor generator, and a traction motor generator which receives electricity from the power generation motor generator or the electricity storage device to drive drive wheels of the vehicle, the control device learning a throttle valve opening suitable for bringing the engine speed closer to a target idle speed when the internal combustion engine is in idling operation or low -load operation close to idling operation , the learning being performed at least once during a period from when an ignition switch (or power switch, ignition key) is turned ON to when it is turned OFF, The control device stores and holds a learned value of the throttle valve opening when the learning was performed and information on the atmospheric pressure detected via the atmospheric pressure sensor when the learning was performed, and the control device judges whether the absolute value of the difference between the current atmospheric pressure detected via the atmospheric pressure sensor and the atmospheric pressure when the learning was performed exceeds a threshold value, and if the threshold value is exceeded, performs re-learning using the learned value as an initial value for the throttle valve opening , and with regard to the operation speed of the throttle valve opening when performing the re- learning, if the current atmospheric pressure detected via the atmospheric pressure sensor is lower than the atmospheric pressure when learning was performed previously, the operation speed of the throttle valve opening is made slower than that of the previous learning .

According to the present invention, the throttle valve opening degree when the internal combustion engine is operating at idle or low load can be appropriately learned by taking into account the altitude at which the vehicle is located, i.e., the atmospheric pressure, and idle or low load operation can be stabilized.

1 is a diagram showing a schematic configuration of a series type hybrid vehicle and a control device according to an embodiment of the present invention; 2 is a diagram showing an overview of an internal combustion engine mounted on the hybrid vehicle of the embodiment; FIG. 4 is a flowchart showing an example of a processing procedure executed by the control device according to a program of the embodiment. FIG. 4 is a flowchart showing an example of a processing procedure executed by the control device according to a program of the embodiment.

One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of the main systems of a hybrid vehicle in this embodiment. This hybrid vehicle includes an internal combustion engine 1, a power generation motor generator 2 that is driven by the internal combustion engine 1 to generate electricity, a power storage device 3 that stores the electricity generated by the power generation motor generator 2, and a traction motor generator 4 that receives power from the power generation motor generator 2 and/or the power storage device 3 to drive the drive wheels 62 of the vehicle.

The hybrid vehicle of this embodiment is a series hybrid type electric vehicle that uses the internal combustion engine 1 only for generating electricity, and the driving force for driving is supplied exclusively to the driving wheels 62 of the vehicle from the driving motor generator 4. The internal combustion engine 1 and the driving wheels 62 are mechanically separated, and no rotational driving force is transmitted between them. In other words, the internal combustion engine 1 can rotate and stop completely independently of the driving motor generator 4 and the driving wheels 62. Therefore, during operation of the vehicle with the ignition switch (power switch or ignition key) turned ON, even if the driver depresses the accelerator pedal to enable the vehicle to run, the internal combustion engine 1 may not be operated with fuel combustion if the storage device 3 has stored a sufficient charge and the brake booster 15 has stored a sufficient negative pressure.

The crankshaft, which is the rotating shaft of the internal combustion engine 1, is mechanically connected to the rotating shaft of the power generation motor generator 2 via a gear mechanism or by directly connecting the shaft. The rotational driving force output by the internal combustion engine 1 is input to the power generation motor generator 2, which generates electricity. The generated electricity is charged to the power storage device 3 and/or supplied to the traveling motor generator 4. The power generation motor generator 2 also functions as a motor for motoring, which generates a rotational driving force to rotate and drive the crankshaft of the internal combustion engine 1. For example, the power generation motor generator 2 performs cranking in preparation for starting the stopped internal combustion engine 1.

The traveling motor generator 4 generates driving force for the vehicle to travel, and inputs the driving force to the driving wheels 62 via the reduction gear 61. The traveling motor generator 4 also generates electricity by rotating in conjunction with the driving wheels 62, and recovers the kinetic energy of the vehicle as electrical energy. The electricity generated by this regenerative braking is charged to the power storage device 3.

However, if the electric charge has already been stored to the full capacity of the power storage device 3 and further charging is difficult, the electric power generated by the traveling motor generator 4 is supplied to the power generation motor generator 2, which is operated as an electric motor to rotate and drive the internal combustion engine 1. This consumes excess electric power while maintaining the braking performance of the vehicle. Also, since the rotation of the internal combustion engine 1 is maintained at this time, a fuel cut can be performed to temporarily stop the fuel supply to the cylinders of the internal combustion engine 1.

The generator inverter 21 converts the AC power generated by the power generation motor generator 2 into DC power. Then, the DC power is input to the storage device 3 or the drive inverter 41. When the power generation motor generator 2 is operated as an electric motor, the generator inverter 21 converts the DC power supplied from the storage device 3 and/or the drive inverter 41 into AC power and inputs it to the power generation motor generator 2.

The drive inverter 41 converts the DC power supplied from the storage device 3 and/or the generator inverter 21 into AC power and inputs it to the traveling motor generator 4. The drive inverter 41 also converts the AC power generated by the traveling motor generator 4 when performing regenerative braking of the vehicle into DC power and inputs it to the storage device 3 or the generator inverter 21. The generator inverter 21 and the drive inverter 41 form part of the PCU (Power Control Unit) 02.

The power storage device 3 is a battery and/or a capacitor, etc. The battery is a high-voltage secondary battery with a high energy density, such as a lithium-ion secondary battery or a nickel-metal hydride secondary battery. The power storage device 3 charges and stores the electric power generated by each of the power generation motor generator 2 and the traveling motor generator 4. The power storage device 3 also discharges the electric power required to operate each of the power generation motor generator 2 and the traveling motor generator 4 as electric motors, and supplies the necessary electric power to the motor generators 2 and 4.

Figure 2 shows an overview of the internal combustion engine 1 mounted on the hybrid vehicle of this embodiment. The internal combustion engine 1 is, for example, a spark-ignition four-stroke reciprocating engine, and has multiple cylinders 11 (for example, three cylinders, one of which is shown in Figure 2). An injector 111 that injects fuel toward the intake port is provided near the intake port of each cylinder 11. In addition, an ignition plug 112 is attached to the ceiling of the combustion chamber of each cylinder 11. The ignition plug 112 generates a spark discharge between a center electrode and a ground electrode when an induced voltage generated by an ignition coil is applied.

The intake passage 13 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 11. In the intake passage 13, an air cleaner 131, an electronic throttle valve 132 which is an intake throttle valve, a surge tank 133, and an intake manifold 134 are arranged in this order from upstream to downstream. The air cleaner 131 is located at the most upstream position in the intake passage 13, i.e., at the intake port which takes in air. The intake port opens to the front of the vehicle in order to take in cool air and increase the charging efficiency of the internal combustion engine.

The exhaust passage 14 for discharging exhaust gas leads the exhaust gas generated as a result of burning fuel in the cylinders 11 from the exhaust port of each cylinder 11 to the outside. An exhaust manifold 142 and a three-way catalyst 141 for purifying the exhaust gas are arranged on this exhaust passage 14.

The EGR device 12 includes an external EGR passage 121 that connects the exhaust passage 14 and the intake passage 13, an EGR cooler 122 provided on the EGR passage 121, and an EGR valve 123 that opens and closes the EGR passage 121 to control the flow rate of EGR gas flowing through the EGR passage 121. The inlet of the EGR passage 121 is connected to a location downstream of the catalyst 141 in the exhaust passage 14. The outlet of the EGR passage 121 is connected to a location downstream of the throttle valve 132 in the intake passage 13 (in particular, the surge tank 133 or the intake manifold 134).

The blow-by gas recirculation device 17 is used to send blow-by gas from the internal chambers of the internal combustion engine 1, i.e., the crank chamber, the chain cover chamber, and the cam chamber, to the intake passage 13, and its elements are the PCV passage 171, the PCV valve 172, and the blow-by passage 173.

One end of the PCV passage 171 is connected to the crankcase, and the other end is connected to a specified location (e.g., surge tank 133 or intake manifold 134) downstream of the throttle valve 132 where negative intake pressure is generated in the intake passage 13. In other words, the PCV passage 171 connects the crank chamber to the downstream side of the throttle valve 132 in the intake passage 13. Blow-by gas generated in the crank chamber is discharged to the intake passage 13 via this PCV passage 171.

The PCV valve 172 is a mechanical valve that can be opened and closed by the pressure difference between the front and rear of the valve 172, and increases and decreases the flow rate of blow-by gas flowing through the PCV passage 171. The PCV valve 172 is installed at or near the connection point of the PCV passage 171 to the crank chamber. An oil separator (not shown) is installed between the crank chamber and the PCV valve 172. The oil separator has a labyrinth structure and performs a gas-liquid separation function that separates the lubricating oil contained in the flowing gas from the gas, thereby preventing the loss of lubricating oil from the crank chamber.

One end of the blow-by passage 173 is connected to the cylinder head cover, and the other end is connected to a specified location upstream of the throttle valve 132 in the intake passage 13 (for example, immediately after the air cleaner 131). In other words, the blow-by passage 173 connects the cam chamber to the upstream side of the throttle valve 132 in the intake passage 13. An oil separator is also provided at the connection point of the blow-by passage 173 to the cam chamber.

When the PCV valve 172 is open, the blow-by gas in the cam chamber and crank chamber is sent to the intake passage 13 via the PCV valve 172 and the PCV passage 171. At the same time, air flows from the intake passage 13 into the cam chamber via the blow-by passage 173. This air flows into the chain cover chamber inside the chain cover that covers the timing chain and sprocket, and flows into the crank chamber via the chain cover chamber. This ventilates (scavenges) the cam chamber, chain cover chamber, and crank chamber. The blow-by gas that has returned to the intake passage 13 is filled into the cylinder 11 and re-burned.

The ECU (Electronic Control Unit) 0, which is a control device that controls the internal combustion engine 1, the power generation motor generator 2, the storage device 3, the inverters 21, 41 and the driving motor generator 4, is a microcomputer system having a processor, memory, an input interface, an output interface, etc. The ECU0 is made up of multiple ECUs, namely, an EFI (Electronic Fuel Injection) ECU01 that controls the internal combustion engine 1, an MG (Motor Generator) ECU02 that controls the motor generators 2, 4 and the inverters 21, 41, a BMS (Battery Management System) ECU03 that controls the power storage device 3, and an HV (Hybrid Vehicle) ECU00 that is a higher-level controller that oversees these controls, all of which are connected to each other so that they can communicate with each other via an electrical communication line such as a CAN (Controller Area Network).

The ECU 0 receives a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from a crank angle sensor that detects the rotation angle of the crankshaft of the internal combustion engine 1 and the engine speed, an accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal by the driver as the accelerator opening (in other words, the driving force that the driver is requesting from the vehicle (the driving motor generator 4)), an intake air temperature/intake pressure signal d output from a temperature/pressure sensor that detects the intake air temperature and intake pressure in the intake passage 13 (particularly, the surge tank 133 or the intake manifold 134) connected to the cylinder 11 of the internal combustion engine 1, an atmospheric pressure signal e output from an atmospheric pressure sensor that detects the atmospheric pressure, a coolant temperature signal f output from a water temperature sensor that detects the temperature of the coolant for the internal combustion engine 1, a battery SOC (State of Charge) output from a sensor (particularly, a battery current and/or battery voltage sensor) that detects the amount of charge stored in the storage device 3. Charge signal g, and negative pressure signal h output from a negative pressure sensor that detects the negative pressure stored in the constant pressure chamber of the brake booster 15 are input.

The ECU 0 then controls the increase or decrease of the rotational driving force output by the driving motor generator 4, the rotational driving force output by the internal combustion engine 1, and the amount of power generated by the power generation motor generator 2, depending on the amount of accelerator pedal depression operated by the driver, the current vehicle speed, the amount of charge stored in the power storage device 3, the power generated by the power generation motor generator 2, etc., which are sensed via various sensors.

As a general rule, if the power storage device 3 currently stores sufficient charge and the output required for the travel motor generator 4 is small, the supply of fuel to the internal combustion engine 1 is cut off and the internal combustion engine 1 is not operated. Conversely, if the amount of charge stored in the power storage device 3 falls below a lower limit or the output required for the travel motor generator 4 is large, the internal combustion engine 1 is started and fuel is supplied to the cylinders 11 and fired to combust it, and the generator motor generator 2 is driven by the rotational driving force output by the internal combustion engine 1, generating electricity to charge the power storage device 3 or to increase the power supplied to the travel motor generator 4.

In order to start the internal combustion engine 1 and generate electricity using the power generating motor generator 2 while fuel is not being supplied to the cylinders 11 of the internal combustion engine 1 and the vehicle is being driven by the driving wheels 62 using the traveling motor generator 4, the power generating motor generator 2 is first operated as an electric motor, and cranking is performed to start the internal combustion engine 1. Then, when the crankshaft of the internal combustion engine 1 has rotated a predetermined number of times or a predetermined angle or more, and cylinder discrimination has been completed to obtain the current stroke or piston position of each cylinder 11 of the internal combustion engine 1, fuel is injected at an appropriate timing in accordance with the stroke of each cylinder 11 of the internal combustion engine 1, and firing is started to ignite and burn the fuel at an appropriate timing. The rotation angle and rotation speed of the crankshaft of the internal combustion engine 1, i.e., the engine speed, can be detected (in the MG ECU 02) via a resolver attached to the power generating motor generator 2, and can also be detected (in the EFI ECU 01) via a crank angle sensor attached to the internal combustion engine 1.

When the internal combustion engine 1 is able to rotate independently and output the rotational drive force required for generating electricity, in other words, when the engine speed can maintain an upward trend even when the output of the power generation motor generator 2 is reduced, the output of the power generation motor generator 2 operating as an electric motor is reduced to zero, cranking is terminated, and the power generation motor generator 2 is then driven to rotate by the internal combustion engine 1. Furthermore, the power generation motor generator 2 is operated as a generator, and the generated power is increased from zero.

Then, the amount of intake air and fuel injection supplied to cylinder 1 of internal combustion engine 1, as well as the generated power of power generating motor generator 2, are adjusted to increase or decrease so that the engine speed follows the target speed, which is increased in stages. The final target speed is set to the speed at which internal combustion engine 1 can be operated with optimal or near-optimal efficiency and is most favorable for fuel consumption rate, or the speed at which internal combustion engine 1 can achieve maximum torque or maximum output or torque or output close to maximum.

The EFI ECU01, which is a part of the ECU0, acquires various information b, d, e, and f necessary for the operation control of the internal combustion engine 1 via the input interface, determines the engine speed, and estimates the amount of air taken into the cylinder 11. Then, it determines the operation parameters of the internal combustion engine 1, such as the required fuel injection amount (necessary to realize the target air-fuel ratio) corresponding to the intake air amount, the fuel injection timing (including the number of fuel injections per combustion), the fuel injection pressure, the ignition timing (including the number of ignitions per combustion), the required EGR rate (or the amount of EGR gas), etc. The EFI ECU01 outputs various control signals i, j, k, and l corresponding to the operation parameters to the igniter of the spark plug 112, the injector 111, the throttle valve 132, the EGR valve 123, etc. via the output interface.

The ECU 0 sometimes operates the internal combustion engine 1 at idle or a low load similar to this while firing the engine. At this time, the engine is essentially operating at no load, and the engine 1 generates little or no useful output to the outside. In other words, the power generation motor generator 2, which is driven by the engine 1, generates little or no power and does not supply power to the power storage device 3 or the motor generator 4 for driving.

As shown in FIG. 3, when an opportunity arises to idle or operate the internal combustion engine 1 at a low load (step S1), the ECU 0 of this embodiment determines the operation speed of the throttle valve 132 opening, i.e., the amount of change (increase or decrease) in the opening per unit time, according to the current atmospheric pressure (step S2), and performs feedback control of the engine speed while operating the throttle valve 132 opening in accordance with the operation speed (step S3).

In step S2, the lower the atmospheric pressure at that time, the slower the operation speed of the throttle valve 132 (the smaller the amount of change in the opening per unit time), and the higher the atmospheric pressure, the faster the operation speed of the throttle valve 132 (the larger the amount of change in the opening per unit time). This is a measure to prevent hunting of the engine speed during idling or low-load operation at high altitudes where the atmospheric pressure is low.

In step S3, ECU0 determines the deviation between the actual engine speed and the target idle speed (or the minimum speed during firing operation after starting the internal combustion engine 1), and manipulates the opening of the throttle valve 132 in a direction to reduce the deviation. That is, if the current actual speed exceeds the target speed, the opening of the throttle valve 132 is narrowed further to reduce the amount of air and fuel injection amount taken into cylinder 1. Conversely, if the current actual speed is below the target speed, the opening of the throttle valve 132 is widened further to increase the amount of air and fuel injection amount taken into cylinder 1.

When it is confirmed by feedback control that the actual engine speed has converged to the target idle speed, i.e., that the deviation (absolute value) between the actual speed and the target speed has been kept below a predetermined error for a predetermined period of time (step S4), the opening degree of the throttle valve 132 at that point in time is stored in the memory of ECU0 as a learned value (step S5). Note that in step S5, the atmospheric pressure at that time is also stored in the memory.

The learned value becomes the initial value for the opening of the throttle valve 132 in controlling the engine speed when the internal combustion engine 1 is later operated at idle or under low load again. One of the reasons for performing such learning is to deal with deterioration over time that occurs when deposits gradually build up and accumulate on the throttle valve 132 (throttle body and butterfly valve body), the intake port connected to the cylinder 11, the intake valve, the ceiling of the combustion chamber, etc.

The vehicle in this embodiment is a hybrid vehicle, and compared to conventional non-hybrid vehicles, there are fewer opportunities for the internal combustion engine 1 to idle or operate at low load. Therefore, unless the internal combustion engine 1 is intentionally operated at idle or at low load to provide an opportunity to learn the opening degree of the throttle valve 132, the learning value will not be updated in a timely manner.

On the other hand, the appropriate throttle valve 132 opening during idle or low-load operation is affected by the altitude at which the vehicle is currently located, i.e., the atmospheric pressure at that time. If a learning value learned at low altitude is used for idle or low-load operation at high altitude, the throttle valve 132 opening may be reduced more than the appropriate value, and the engine speed may drop unduly. Conversely, if a learning value learned at high altitude is used for idle or low-load operation at low altitude, the throttle valve 132 opening may be increased more than the appropriate value, which may unnecessarily increase the engine speed and increase fuel consumption.

To avoid such inconvenience, as shown in FIG. 4, the ECU 0 of this embodiment compares the atmospheric pressure when learning was most recently completed, stored in step S5, with the current atmospheric pressure, and provides an opportunity to execute learning (step S7) on the condition that the absolute value of the difference between the two has exceeded a threshold value (step S6). That is, if the internal combustion engine 1 is currently firing and generating electricity using the power generating motor generator 2, after the power generation ends, the internal combustion engine 1 continues firing and transitions to idle operation or low load operation, and the learning process shown in FIG. 3 is executed. Alternatively, if the internal combustion engine 1 is currently stopped, it is started to start firing, transitions to idle operation or low load operation, and executes the learning process shown in FIG. 3.

Incidentally, learning is performed at least once during one trip (the period from when the ignition switch is turned ON to when it is turned OFF). Therefore, when the ignition switch is turned ON and the vehicle begins operation, it is desirable to start learning as soon as possible by running the internal combustion engine 1 at idle or low load.

In this embodiment, the control device 0 for an internal combustion engine learns the opening degree of the throttle valve 132 suitable for bringing the engine speed closer to the target idle speed when the internal combustion engine 1 is operating at idle or at a low load close to idle. The control device 0 is configured to store and hold the atmospheric pressure when the learning is performed once, and to perform the learning again when the absolute value of the difference between the atmospheric pressure when the learning was performed and the current atmospheric pressure exceeds a threshold value as a necessary condition.

According to this embodiment, it is possible to avoid the inconvenience of using the learned value of the opening of the throttle valve 132 learned at a low altitude where the atmospheric pressure is high for idle operation or low load operation at a high altitude where the atmospheric pressure is low, or using the learned value of the opening of the throttle valve 132 learned at a high altitude for idle operation or low load operation at a low altitude. As a result, the engine speed during idle operation or low load operation can be appropriately converged to the target speed both at low altitudes and at high altitudes, making it possible to prevent instability in idle rotation and revving up.

In addition, in this embodiment, the control device 0 for the internal combustion engine 1 learns the opening of the throttle valve 132 suitable for bringing the engine speed closer to the target idle speed when the internal combustion engine 1 is operating at idle or at a low load similar to this, and the control device 0 for the internal combustion engine is configured to slow down the operation speed of the opening of the throttle valve 132 when performing the learning when the atmospheric pressure is low compared to when the atmospheric pressure is higher.

According to this embodiment, extreme fluctuations in the amount of intake air filled into cylinder 1 can be avoided, particularly when the internal combustion engine 1 is operated at idle or under low load at high altitudes. As a result, the engine speed during idle or under low load operation can be appropriately converged to the target speed at both low and high altitudes, making it possible to prevent instability in idle rotation and revving up.

Note that the present invention is not limited to the embodiment described above. In the above embodiment, the learning of the opening of the throttle valve 132 when the internal combustion engine 1 is operated at idle or low load is performed by actually firing the internal combustion engine 1 (operating at idle or low load). However, instead of this, it is also possible to operate the power generating motor generator 2 as an electric motor, and perform motoring to rotate and drive the internal combustion engine 1 using the motor generator 2 under a constant output torque (constant applied voltage and applied current), and while expanding and contracting the opening of the throttle valve 132 during this motoring, by measuring the intake pressure in the intake passage 13 (surge tank 133 or intake manifold 134) connected to the cylinder 1 or the amount of air taken into the cylinder 1, to obtain a learning value of the opening of the throttle valve 132 suitable for operating the internal combustion engine 1 at idle or low load.

Furthermore, the application of the present invention is not limited to internal combustion engines 1 mounted on series hybrid vehicles.

In addition, the specific configuration of each part and the contents of the processing can be modified in various ways without departing from the spirit of the present invention.

0...Control unit (ECU)
1... internal combustion engine 11... cylinder 13... intake passage 132... throttle valve d... intake air temperature/intake pressure signal e... atmospheric pressure signal i... ignition signal j... fuel injection signal k... throttle valve opening operation signal

Claims (2)

An internal combustion engine;
a power generating motor generator that is driven by the internal combustion engine to generate power;
a power storage device that stores the electric power generated by the power generation motor generator;
a driving motor generator that receives a supply of electric power from the power generation motor generator or the power storage device to drive drive wheels of a vehicle;
The present invention relates to an internal combustion engine of a vehicle,
A control device that learns a suitable throttle valve opening for bringing an engine speed closer to a target idle speed when the internal combustion engine is in an idle operation or a low-load operation close to the idle operation ,
The learning is performed at least once during a period from when an ignition switch is turned ON to when it is turned OFF,
the control device stores and holds a learned value of the opening degree of the throttle valve when the learning is performed and information on the atmospheric pressure detected via an atmospheric pressure sensor when the learning is performed;
The control device determines whether the absolute value of the difference between the current atmospheric pressure detected via an atmospheric pressure sensor and the atmospheric pressure at the time of the learning exceeds a threshold value, and if the threshold value is exceeded, performs re-learning using the learned value as an initial value for the throttle valve opening, and changes the control in the learning. An internal combustion engine;
a power generating motor generator that is driven by the internal combustion engine to generate power;
a power storage device that stores the electric power generated by the power generation motor generator;
a driving motor generator that receives electric power from the power generation motor generator or the power storage device and drives drive wheels of a vehicle;
The present invention relates to an internal combustion engine of a vehicle,
A control device that learns a suitable throttle valve opening for bringing an engine speed closer to a target idle speed when the internal combustion engine is in an idle operation or a low-load operation close to the idle operation ,
The learning is performed at least once during a period from when an ignition switch is turned ON to when it is turned OFF,
the control device stores and holds a learned value of the opening degree of the throttle valve when the learning is performed and information on the atmospheric pressure detected via an atmospheric pressure sensor when the learning is performed;
the control device judges whether or not an absolute value of a difference between the current atmospheric pressure detected via an atmospheric pressure sensor and the atmospheric pressure at the time of said learning exceeds a threshold value, and if the absolute value exceeds the threshold value, performs re-learning using the learned value as an initial value for the opening degree of the throttle valve ;
Regarding the operation speed of the throttle valve opening when performing the re- learning, if the current atmospheric pressure detected via an atmospheric pressure sensor is lower than the atmospheric pressure when the previous learning was performed, the control device for an internal combustion engine makes the operation speed of the throttle valve opening slower than that of the previous learning .

Images