JP7400657B2 - engine control device - Google Patents

Description

The present invention relates to an engine control device having a function of learning the value of a control parameter for idle rotation speed and optimizing it each time.

2. Description of the Related Art Engine control devices are known that perform feedback control to maintain the engine rotational speed at a predetermined rotational speed during engine idling. The idle rotation speed is controlled by feeding back values of control parameters such as throttle opening and ignition timing. The actual values of the control parameters vary depending on individual engine differences and changes over time. In order to respond to these changes, the values of each control parameter that corresponds to the target idle rotation speed are learned at a predetermined timing, and the idle rotation speed is controlled using the learned control parameter values during the next idling. is started.

Regarding idle rotation speed control, Patent Document 1 described below describes a technique for stopping the engine if the idling state is prolonged and a predetermined period of time has elapsed even before learning of control parameters is completed.

Japanese Patent Application Publication No. 2004-52599

When learning of idle rotation speed control is not necessary, such as when there is little change in idle rotation speed from before, continuing idling for this learning will waste fuel. An object of the present invention is to suppress fuel consumption due to learning of idle rotation speed control.

In the engine control device according to the present invention, during idle rotation speed control in which the idle rotation speed is feedback-controlled via an engine torque command value, the absolute value of the deviation of the rotation speed from a target value is within a first deviation threshold. Learning of idle rotation speed control that updates the initial command value during idling to the value at that time when the absolute value of the feedback correction amount is maintained below the first correction amount threshold for a first predetermined time. I do . Then, when a command is issued to automatically stop the engine while the vehicle is idling in a state where idle rotation speed control learning has not been executed in a certain operation, the absolute value of the rotation speed deviation is less than the first deviation threshold. When the absolute value of the feedback correction amount is maintained below the second correction amount threshold, which is smaller than the first correction amount threshold, for a second predetermined time period that is shorter than the first predetermined time period. , stop the engine. In this case, idle rotation speed control learning is not performed. In addition, if the absolute value of the rotation speed deviation is below the second deviation threshold and the absolute value of the feedback correction amount is not maintained below the second correction amount threshold for a second predetermined period of time, idling is continued. to perform idle rotation speed control learning.

By determining the stability of the idle rotation speed in a time shorter than the time required to learn the idle rotation control, the engine can be stopped without waiting for the learning to be completed, and fuel consumption can be suppressed.

1 is a diagram showing a schematic configuration of a system including an engine control device and an engine according to the present embodiment. FIG. 3 is a block diagram related to idle rotation speed control. It is a flowchart concerning learning of idle rotation speed control.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a system including an engine 10 and an engine control device 12 that drive a vehicle. The engine 10 may be an internal combustion engine, in particular a gasoline engine, but also a diesel engine. The engine control device 12 includes an accelerator pedal 14 and a brake pedal 16 operated by the driver, sensors such as a vehicle speed sensor 18 for grasping the running state of the vehicle, and an engine rotation speed sensor 20 and a coolant temperature sensor 22. The rotational speed and output of the engine 10 are controlled based on information from sensors and the like for ascertaining the state of the engine 10. In a hybrid vehicle that includes a motor in addition to the engine 10 as a prime mover for driving the vehicle, the amount of electricity stored in a battery that supplies power to the motor is also information used to control the engine. Based on the above information, the engine control device 12 controls the opening degree of the throttle valve 30, fuel injection amount, ignition timing, etc., so that the engine 10 is operated at a desired rotational speed and output.

The engine 10 idles when driving force is not required, such as when the vehicle is stopped. Furthermore, in order to suppress fuel consumption due to idling, the engine automatically stops (idling stop) when predetermined conditions are met. Then, it is restarted when driving force is required. The rotation speed during idling is determined by finely adjusting the amount of intake air and adjusting the ignition timing, for example, by adjusting the opening degree of the throttle valve 30, especially the opening degree of the idle rotation speed control valve arranged in parallel with the main valve. controlled by A target value for the idle rotation speed is set in advance, and values of control parameters such as the opening degree of the throttle valve 30 and the ignition timing are adjusted so that the actual idle rotation speed becomes the target value.

More specifically, the command value of the torque generated by the engine 10 (hereinafter referred to as the torque command value) and the value of each control parameter are stored in association with each other as a control map, and the engine rotation speed is determined by the torque command value. Feedback is provided via. As shown in FIG. 2, the values of control parameters such as the opening degree of the throttle valve 30 are calculated based on the torque command value, and the engine is controlled (B40). Then, the engine rotation speed is compared with the target rotation speed, and based on the deviation, a torque correction amount is calculated with reference to the control map (B42), and is fed back to the torque command value. For example, when the actual idle speed is lower than the target value, the torque command value of the engine 10 is increased, and the opening degree of the throttle valve 30 is increased based on this increased torque command value. As a result, the rotation speed increases. Note that the torque command value is also one of the control parameters.

At the start of idling, control is started based on a predetermined initial value of the torque command value at idling, but due to individual differences in the engine 10 and changes over time, the friction of the engine 10 changes and the target rotation The torque required to achieve the speed changes. In order to cope with this change, engine control is known that performs idle rotation speed control learning (hereinafter referred to as ISC learning) in which an appropriate torque command value is learned and updated. During one operation of the vehicle, that is, from when the ignition switch is turned on until it is turned off, the torque command value is memorized when the engine reaches the target rotation speed during the first idling after the engine has warmed up. In other words, this command value is learned and used as the initial value when starting idling thereafter. After idling starts, the torque command value changes based on feedback control, but the learned torque command value is maintained. In the next operation, idling is started using the torque command value learned during the previous operation as the initial value until ISC learning is executed.

In a vehicle that performs idling stop, if ISC learning has not yet been performed during a certain operation, idling stop is prohibited and idling is forcibly performed, while ISC learning is performed. This ensures opportunities for ISC learning. On the other hand, if there is no need to perform ISC learning again, such as when the engine is idling stably, idling for ISC learning increases fuel consumption. In this engine control device 12, when ISC learning is not necessary, idling is stopped early to stop the engine.

FIG. 3 is a diagram showing a control flow when idling is forcibly executed for ISC learning when an idling stop command is issued. First, it is determined whether the conditions for performing ISC learning are satisfied (S100). This condition is that the engine is currently in operation, that the coolant temperature of the engine 10 is above a predetermined value, and that in the current operation, the coolant temperature at the start of operation is below a predetermined value. . Do not start the engine when it is not running, that is, when it is stopped. Further, ISC learning is performed when the cooling water temperature reaches a predetermined value or higher, for example, 70° C. or higher and is sufficiently warmed. Furthermore, if the cooling water temperature at the start of the operation is high, almost no time has passed since the last operation, and it is considered that there has been almost no change in the engine since the last operation, so ISC learning is considered unnecessary. If the ISC learning conditions are not met, the engine is stopped (S102). Moreover, if the conditions for ISC learning are satisfied, the process moves to step S104.

Step S104 is a step for determining whether the idling state such as the idling rotation speed has changed from before, and if the change is sufficiently small, executing idle stop without performing ISC learning. The specific content will be explained after the steps related to ISC learning are explained.

In step S104, if the idling state has changed from before, the process moves to step S106 for ISC learning. In step S106, the absolute value DLN of the deviation between the actual value of the engine rotation speed and the target value is compared with a predetermined value (hereinafter referred to as a first deviation threshold DLNT1), and the engine torque to be fed back is The absolute value DLQ of the correction amount (hereinafter referred to as a feedback correction amount) is compared with a predetermined value (hereinafter referred to as a first correction amount threshold DLQT1). A state in which the absolute value DLN of the deviation of the engine speed is less than or equal to the first deviation threshold DLNT1 (DLN ≦ DLNT1), and the absolute value DLQ of the feedback correction amount is less than or equal to the first correction amount threshold DLQT1 (DLQ ≦ DLQT1). If this continues for a predetermined time t1 (step S108), the initial value of the torque command value is updated (S110). The first deviation threshold DLNT1 can be set to, for example, 25 rpm, and the first correction amount threshold DLQT1 can be set to, for example, 0.2 Nm. Further, the time t1 can be, for example, 3 seconds. After the update, the engine is stopped (S102). This updated torque command value is used in subsequent idling. Moreover, when the condition of step S106 is satisfied, the initial value of the torque command value may be updated each time, and the engine may be stopped after time t1 has elapsed. On the other hand, if the condition in step S106 is not satisfied, the engine is stopped without updating the initial value of the torque command value.

The explanation will return to step S104. In step S104, the absolute value DLN of the deviation of the engine speed is compared with a predetermined value (hereinafter referred to as the second deviation threshold DLNT2), and the absolute value DLQ of the feedback correction amount is compared with the predetermined value (hereinafter referred to as the second deviation threshold DLNT2). 2 correction amount threshold (denoted as DLQT2). The second deviation threshold DLNT2 is a value smaller than the first deviation threshold DLNT1 (DLNT2<DLNT1), and can be set to, for example, 10 rpm. The second correction amount threshold DLQT2 is a value smaller than the first correction amount threshold DLQT1 (DLQT2<DLQT1), and can be set to, for example, 0.1 Nm. In step S104, the absolute value DLN of the deviation of the engine speed is less than or equal to the second deviation threshold DLNT2 (DLN ≦ DLNT2), and the absolute value DLQ of the feedback correction amount is less than or equal to the second correction amount threshold DLQT2 (DLQ DLQT2 ). In step S104, the range for determining the engine speed deviation DLN and the feedback correction amount DLQ is made narrower than in ISC learning, and if this condition is met, it is determined that the change in the idling state from before is small. I can understand. In other words, it is considered that there is no need to perform ISC learning again.

When the condition in step S104 continues for a predetermined time t2 (S112), the engine is stopped (S102). The time t2 is shorter than the above-mentioned time t1, and can be, for example, 1 second. Thereby, if there is no change in the idling state, the engine can be stopped early, and fuel consumption can be suppressed accordingly.

In step S104 and step S106, it is monitored whether the deviation of the engine rotational speed and the feedback correction amount are within a predetermined range, but the present invention is not limited to this, and only one of them may be monitored.

Reference Signs List 10 engine, 12 engine control device, 14 accelerator pedal, 16 brake pedal, 18 vehicle speed sensor, 20 engine rotation speed sensor, 22 cooling water temperature sensor, 30 throttle valve, DLN deviation between the actual value and target value of engine rotation speed. Absolute value, DLNT1 first deviation threshold, DLNT2 second deviation threshold, DLQ absolute value of feedback correction amount, DLQT1 first correction amount threshold, DLQT2 second correction amount threshold.

Claims (1)

During idle rotation speed control in which the idle rotation speed is feedback-controlled via the engine torque command value, the absolute value of the deviation of the rotation speed from the target value is equal to or less than the first deviation threshold, and the absolute value of the feedback correction amount is the first An engine control device that performs learning of idle rotation speed control that updates an initial command value during idling to a value at that time when the engine is maintained at a value equal to or less than one correction amount threshold for a first predetermined time, the engine control device comprising:
When a command to automatically stop the engine is issued while the vehicle is idling in a state where learning of the idle rotation speed control has not been performed during a certain operation,
A second correction amount in which the absolute value of the deviation of the rotational speed is less than or equal to a second deviation threshold, which is smaller than the first deviation threshold, and the absolute value of the feedback correction amount is smaller than the first correction amount threshold. If the temperature is maintained below the threshold for a second predetermined time shorter than the first predetermined time , the engine is stopped and the learning of the idle rotation speed control is not performed;
If the absolute value of the rotational speed deviation is less than or equal to the second deviation threshold and the absolute value of the feedback correction amount is not maintained less than or equal to the second correction amount threshold for the second predetermined period of time, idling occurs. Continuing to perform the learning of the idle rotation speed control,
Engine control device.

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