JP2024104230A - Control device for internal combustion engine - Google Patents

Abstract

To provide the acceleration feeling intended by a vehicle driver under a wide range of situations.SOLUTION: A control device for an internal combustion engine controls the internal combustion engine mounted on a vehicle, and is configured to change the relationship between the amount of depression of an accelerator pedal operated by the driver and the target opening of a throttle valve in accordance with the amount of retard correction of ignition timing for the mixture filled in a cylinder, and also in accordance with the acceleration of a vehicle speed. If acceleration is insufficient when starting, the throttle valve opening can be quickly increased to increase the output of the internal combustion engine, so that it is possible to prevent the driver from having dissatisfaction feeling.SELECTED DRAWING: Figure 2

Description

The present invention relates to a control device that controls the operation of an internal combustion engine installed in a vehicle as a power source.

The throttle valve, which is installed as an intake throttle valve in the intake passage of an internal combustion engine, is operated based on the intentions of the vehicle driver. As a general rule, the more the driver operates the accelerator pedal, i.e., the more the throttle valve opens. The relationship between the two is usually determined in advance as a unique relational expression or map data.

By the way, a so-called knock control system is known in which, when it detects abnormal combustion in a cylinder, such as knocking, the ignition timing of the air-fuel mixture is retarded until the abnormal combustion is suppressed, and the ignition timing is advanced as long as abnormal combustion does not occur. As a side effect, when the ignition timing is retarded away from MBT (Minimum advance for Best Torque), the thermal efficiency is accordingly worsened and the output of the internal combustion engine is reduced. Therefore, attempts have been made to further increase the throttle valve opening depending on the amount of retard correction of the current ignition timing, thereby compensating for the reduced output of the internal combustion engine (for example, see the following patent document).

JP 2000-186581 A

However, even if the throttle valve opening is adjusted only by the amount of ignition timing retard correction, there are cases where sufficient power and dynamic performance cannot be obtained. This is the case when the vehicle is on an uphill road and a large amount of power is required, or when abnormal combustion occurs frequently due to aging of the internal combustion engine, causing the ignition timing to be significantly retarded.

The present invention was developed with the above points in mind, and aims to realize the acceleration sensation that the vehicle driver intends in a wide range of situations.

The present invention is a control device for an internal combustion engine mounted on a vehicle, which changes the relationship between the amount of depression of the accelerator pedal operated by the driver and the target opening of the throttle valve according to the amount of retard correction of the ignition timing of the mixture filled in the cylinder, and also changes it according to the acceleration of the vehicle speed.

The present invention makes it possible to realize the acceleration sensation intended by the vehicle driver under a wide range of conditions.

1 is a diagram showing a schematic configuration of a vehicle internal combustion engine and a control device according to an embodiment of the present invention; 2 is a flowchart showing an example of a procedure of a process executed by the control device for the internal combustion engine according to a program of the embodiment; 6 is a diagram illustrating an example of a correction amount of a target value of the opening degree of the throttle valve according to a retard correction amount of the ignition timing in the control of the embodiment. FIG. 5 is a diagram illustrating an example of a correction amount of a target value of the opening degree of the throttle valve according to an output of an acceleration sensor in the control of the embodiment. FIG. 5 is a diagram illustrating an example of a correction amount of a target value of the opening degree of the throttle valve according to the acceleration of the vehicle speed in the control of the embodiment. FIG.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle according to this embodiment. This internal combustion engine is a spark-ignition four-stroke reciprocating engine, and is equipped with a number of cylinders 1 (one of which is shown in FIG. 1). An injector 11 that injects fuel toward the intake port is provided upstream of the intake valve of each cylinder 1, near the intake port connected to each cylinder 1. In addition, an ignition plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The ignition plug 12 generates a spark discharge between a center electrode and a ground electrode when an induced voltage generated by an ignition coil is applied to the ignition coil. The ignition coil is integrally built into the coil case together with an igniter, which is a semiconductor switching element.

The intake passage 3, which supplies intake air to the cylinders 1, takes in air from the outside and directs it to the intake port of each cylinder 1. An air cleaner 31, an electronic throttle valve 32, which is an intake throttle valve, a surge tank 33, and an intake manifold 34 are arranged in this order from upstream on the intake passage 3.

The exhaust passage 4 for discharging exhaust gas from the cylinders 1 guides the exhaust gas generated by burning fuel in the cylinders 1 to the outside through the exhaust port of each cylinder 1. An exhaust manifold 42 and a three-way catalyst 41 for purifying the exhaust gas are arranged on the exhaust passage 4.

The exhaust gas recirculation device 2 includes an external EGR passage 21 that connects the exhaust passage 4 and the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR valve 23 that opens and closes the EGR passage 21 to control the flow rate of EGR gas flowing through the EGR passage 21. The inlet of the EGR passage 21 is connected to a predetermined location downstream of the catalyst 41 in the exhaust passage 4. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3 (in particular, the surge tank 33 or the intake manifold 34).

The ECU (Electronic Control Unit) 0, which is the control device for the internal combustion engine in this embodiment, is a microcomputer system having a processor, memory, an input interface, an output interface, etc. The ECU 0 may be configured by connecting multiple ECUs or controllers so that they can communicate with each other via an electric communication line such as a CAN (Controller Area Network).

The input interface of the ECU 0 includes 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 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 of the vehicle as the accelerator opening (in other words, the required engine load factor or engine torque), a cooling water temperature signal d output from a water temperature sensor that detects the temperature of the cooling water of the internal combustion engine, an intake air temperature/intake pressure signal e output from an intake air temperature/intake pressure sensor that detects the intake air temperature and intake pressure of the intake air (particularly, in the surge tank 33 or the intake manifold 34) flowing through the intake passage 3 toward the cylinder 1, a vibration signal f output from a vibration-type knock sensor 13 that detects the magnitude of vibration of the cylinder block containing the cylinder 1, a signal g output from an acceleration sensor (G sensor) that detects the acceleration of the vehicle and/or the gradient of the road surface on which the vehicle is located, and an air-fuel ratio sensor (linear A/F sensor or O sensor) that detects the air-fuel ratio of the gas discharged from the cylinder 1 and flowing through the exhaust passage 4. ₂ sensor) and the like are input.

The output interface of ECU0 outputs an ignition signal i to an igniter associated with the spark plug 12, a fuel injection signal j to the injector 11, an opening control signal k to the electronic throttle valve 32, an opening control signal l to the EGR valve 23, etc.

The processor of ECU0 interprets and executes programs stored in memory in advance, and calculates operating parameters to control the operation of the internal combustion engine. ECU0 acquires various pieces of information a, b, c, d, e, f, g, and h required for controlling the operation of the internal combustion engine via an input interface, and determines various operating parameters such as the required fuel injection amount appropriate to the amount of air taken into cylinder 1, fuel injection timing (including the number of fuel injections per combustion), fuel injection pressure, ignition timing (including the number of spark ignitions per combustion), required EGR rate (or EGR gas amount), etc. ECU0 applies various control signals i, j, k, and l corresponding to the operating parameters via an output interface.

To add a bit more about the knock control system, ECU0 refers to the vibration signal f output by the knock sensor 13 to determine whether or not abnormal combustion such as knocking has occurred in each cylinder 1, and adjusts the ignition timing according to the result of the determination. ECU0 compares the current sampled value of the vibration signal f, which indicates the strength of vibration of the cylinder 1 or cylinder block of the internal combustion engine 1, with the knock determination value, and if the former exceeds the latter, it determines that abnormal combustion has occurred in that cylinder 1. Conversely, if the sampled value of the vibration signal f is equal to or less than the knock determination value, it determines that abnormal combustion is not occurring in that cylinder 1.

When abnormal combustion is detected in cylinder 1, the ignition timing is gradually retarded until abnormal combustion no longer occurs; in other words, the amount of retard correction added to the base ignition timing is gradually increased. On the other hand, when abnormal combustion is not detected, the ignition timing is gradually advanced as long as abnormal combustion does not occur, that is, the amount of retard correction added to the base ignition timing is reduced, bringing the ignition timing as close as possible to the MBT and improving the thermal efficiency of the internal combustion engine. The determination of the presence or absence of abnormal combustion and the retard/advance correction of the ignition timing can be performed individually for each cylinder 1.

ECU0 learns the amount of retard correction of the ignition timing when the abnormal combustion has subsided. That is, the retard correction amount is stored in memory as a learned value corresponding to the current operating range of the internal combustion engine [engine speed, engine load factor (or engine torque, intake pressure in surge tank 33 or manifold 34, amount of intake air or amount of fuel injected into cylinder 1)]. The learned value is read from memory when the corresponding operating range is entered in subsequent control of the internal combustion engine, and is used to correct the ignition timing.

The opening of the throttle valve 32 in the intake passage 3 of the internal combustion engine is adjusted based on the intention of the driver of the vehicle. Figure 2 shows the procedure for determining the target value of the opening of the throttle valve 32 by the ECU 0. First, the base opening, which is the basic amount of the opening of the throttle valve 32, is set according to the accelerator opening, which is the amount of operation of the accelerator pedal by the driver (step S1). In general, the base opening increases as the accelerator opening increases. The relationship between the accelerator opening and the base opening is determined in advance as a unique relational equation or map data, and is stored and held in memory. In step S1, the ECU 0 searches the map data using the current accelerator opening obtained by referring to the accelerator opening signal c as a key, or substitutes the accelerator opening into the relational equation to calculate the base opening.

Next, the ECU 0 corrects the base opening according to the retard correction amount of the ignition timing (step S2). FIG. 3 illustrates an example of the tendency of the correction of the opening of the throttle valve 32 according to the retard correction amount of the ignition timing. In FIG. 3, the horizontal axis is the accelerator opening, and the vertical axis is the throttle valve 32 opening corrected from the base opening. L1 is the corrected opening when the retard correction amount of the ignition timing is maximum (the ignition timing is farthest from the base ignition timing), L3 is the corrected opening when the retard correction amount is minimum (the ignition timing is closest to the base ignition timing), and L2 is the corrected opening when the retard correction amount is about intermediate. The opening of the throttle valve 32 is corrected so that it is enlarged more compared to the base opening as the retard correction amount of the ignition timing is larger. The relationship between the retard correction amount of the ignition timing and the correction amount of the throttle valve 32 opening is determined in advance as a relational expression or map data, and is stored and held in memory. In step S2, ECU0 reads the learned value of the ignition timing retard correction amount corresponding to the current operating range of the internal combustion engine [engine speed, engine load factor], and searches the map data using the learned value as a key, or substitutes the learned value into a relational expression to calculate the opening correction amount.

Next, the ECU 0 corrects the opening calculated in step S2 according to the output value of the acceleration sensor (step S3). Figure 4 illustrates an example of the tendency of the throttle valve 32 opening correction according to the acceleration sensor output value. In Figure 4, the horizontal axis is the gradient of the road surface as the output value of the acceleration sensor, and the vertical axis is the coefficient by which the opening calculated in step S2 is multiplied as the correction amount. When the gradient of the road surface detected via the acceleration sensor is 0°, i.e. horizontal, the coefficient is set to 1, that is, the throttle valve 32 opening is not corrected. When the gradient of the road surface is a positive value and is an upward gradient, the coefficient is set to be greater than 1, and the throttle valve 32 opening is corrected in a direction to be enlarged. The amount of enlargement increases as the absolute value of the upward gradient increases. When the gradient of the road surface is a negative value and is a downward gradient, the coefficient is set to be less than 1, and the throttle valve 32 opening is corrected in a direction to be reduced. The amount of reduction increases as the absolute value of the downward gradient increases. The relationship between the acceleration sensor output value and the throttle valve 32 opening correction amount is determined in advance as a relational equation or map data, and is stored and held in memory. In step S3, ECU0 searches the map data using the output value obtained by referring to the acceleration sensor output signal g as a key, or substitutes the output value into the relational equation to calculate the opening correction amount.

The amount of correction to the opening according to the output value of the acceleration sensor is set and updated each time the vehicle is stopped and the vehicle speed is 0 or less than a threshold close to 0, and the same amount of correction can be used for a while after starting or until the vehicle is stopped again. Of course, it is also possible to set the amount of correction according to the current output value of the acceleration sensor each time a calculation cycle for the target opening of the throttle valve 32 occurs.

Furthermore, ECU0 applies a correction to the opening calculated in step S3 according to the actual vehicle acceleration (step S4). Figure 5 illustrates an example of the tendency of the correction of the opening of the throttle valve 32 according to the acceleration of the vehicle speed. In Figure 5, the horizontal axis is the acceleration of the vehicle speed, and the vertical axis is the coefficient by which the opening calculated in step S3 is multiplied as a correction amount. The opening of the throttle valve 32 should be enlarged more as the acceleration of the vehicle that starts and accelerates is smaller. For this reason, the correction coefficient greater than 1 is set to a larger value as the acceleration of the vehicle speed is smaller, and a smaller value as the acceleration of the vehicle speed is larger. However, when the acceleration of the vehicle speed exceeds a predetermined threshold value, the coefficient is set to 1, and the opening of the throttle valve 32 is not corrected. The relationship between the acceleration of the vehicle speed and the correction amount of the throttle valve 32 opening is determined in advance as a relational expression or map data, and is stored and held in memory. In step S4, ECU0 estimates the acceleration of the current vehicle speed from the vehicle speed value (time series) obtained by referring to the output signal a of the vehicle speed sensor and/or the acceleration value (time series) obtained by referring to the output signal g of the acceleration sensor. Then, the ECU0 searches map data using the acceleration as a key, or substitutes the acceleration into a relational expression to calculate the amount of correction to the opening.

Overall,
The target opening of the throttle valve 32 = the opening obtained by adding the retard correction amount of the ignition timing to the base opening x the correction amount according to the output value of the acceleration sensor x the correction amount according to the acceleration of the vehicle speed. The ECU 0 provides the opening control signal k to the electronic throttle valve 32 so as to achieve the obtained target opening.

The reason why the correction amount according to the acceleration sensor output value and the correction amount according to the acceleration of the vehicle speed are used in combination is that with the former alone, it is not possible to determine whether the acceleration is sufficient or insufficient until the vehicle has started moving after being stopped, which may cause the driver to feel dissatisfied. By also using the latter correction amount according to the actual acceleration of the vehicle speed, the opening of the throttle valve 32 can be quickly increased to increase the output of the internal combustion engine if the acceleration at the time of starting is insufficient, and the driver does not feel dissatisfied.

In this embodiment, an internal combustion engine control device 0 is configured to control an internal combustion engine mounted on a vehicle, and changes the relationship between the amount of depression of the accelerator pedal operated by the driver and the target opening of the throttle valve 32 according to the amount of retard correction of the ignition timing of the mixture filled in the cylinder 1, and also according to the acceleration of the vehicle speed.

According to this embodiment, the acceleration feeling intended by the vehicle driver can be realized under a wide range of conditions, and the drivability of the vehicle can be maintained at a high level. Implementing the control of this embodiment does not require the addition of new hardware, and does not unnecessarily increase costs.

The present invention is not limited to the embodiment described above. The specific configuration of each part and the processing procedure can be modified in various ways without departing from the spirit of the present invention.

0...Control unit (ECU)
1... cylinder 12... spark plug 32... throttle valve a... vehicle speed signal b... crank angle signal c... accelerator opening signal e... intake air temperature/intake pressure signal f... vibration signal g... acceleration signal i... ignition signal j... fuel injection signal k... throttle valve opening control signal

Claims (1)

A control device for controlling an internal combustion engine mounted on a vehicle,
A control device for an internal combustion engine that changes the relationship between the amount of depression of an accelerator pedal operated by a driver and a target opening degree of a throttle valve according to the amount of retard correction of the ignition timing of the mixture filled in the cylinder, and also according to the acceleration of the vehicle speed.

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