JP2022030880A - Engine control apparatus - Google Patents

Abstract

To suppress fuel consumption by an idle speed control self-diagnosis (ISC-OBD) and secure the execution result of the ISC-OBD.SOLUTION: In a case where a normality is determined before a period of time required for abnormality determination elapses in an ISC-OBD, an engine is stopped to suppress fuel consumption. Furthermore, the engine stop is maintained and when the time required for an abnormality determined elapses after starting the ISC-OBD, the number of times of executing the ISC-OBD is counted to record execution result.SELECTED DRAWING: Figure 4

Description

The present invention relates to an engine control device having an idle speed control self-diagnosis function for determining whether or not idle speed control that feedback-controls idle rotation speed to a target value is functioning normally.

There is known an engine control device that performs idle speed control (hereinafter referred to as ISC) in idling of an engine to maintain the rotation speed of the engine at a predetermined rotation speed by feedback control. Further, there is known a device that learns the value of the control parameter of the feedback control, updates the value up to that point, and starts ISC with the learned and updated value in the next idling. Learning and updating the value of this control parameter is referred to as ISC learning. Further, an engine control device that performs idle speed control self-diagnosis (hereinafter referred to as ISC-OBD) that self-diagnoses whether the ISC is functioning normally is also known. Regarding ISC-OBD, there are cases where it is required by law or the like that the frequency of such execution is equal to or higher than a predetermined value. Further, there is known an engine control device that stops idling when the driving force of the engine is not required, such as when the vehicle is stopped, that is, so-called idling stop.

In Patent Document 1 below, even if the idle rotation speed is stable and idling stop can be performed, if ISC-OBD is not completed, idling stop is not performed. The technology to secure the opportunity of ISC-OBD is disclosed.

Japanese Unexamined Patent Publication No. 2019-183653

In Patent Document 1, the frequency of execution of ISC-OBD can be increased, but since idling is performed for ISC-OBD, fuel consumption may increase.

An object of the present invention is to suppress fuel consumption during idling for ISC-OBD and to secure the number of times ISC-OBD is executed.

The engine control device according to the present invention stops the engine when the idle speed control self-diagnosis (ISC-OBD) determines normally before the time required for abnormality determination elapses, and further, the engine is stopped. The number of times ISC-OBD is executed is counted up after the time required for abnormality determination has elapsed from the start of the idle speed control self-diagnosis.

In ISC-OBD, the normality determination can be completed in a relatively short time, while the abnormality determination requires more time than the normality determination. By stopping the engine as soon as a normal judgment is made, fuel consumption is suppressed, while by counting up the number of ISC-OBD executions after the time required for abnormality judgment has elapsed, many achievements have been made. can do.

Further, the idle speed control (ISC) is feedback-controlled via the engine torque command value, and the engine control device provides feedback during the ISC that the absolute value of the rotational speed deviation with respect to the target value is equal to or less than the first deviation threshold value. When the absolute value of the correction amount is maintained below the first correction amount threshold for the first predetermined time, the idle speed control learning to update the initial command value at the time of idling to the value at that time is performed, and further, the engine In the control device, during the second predetermined time shorter than the first predetermined time, the absolute value of the deviation of the rotation speed is equal to or less than the second deviation threshold value smaller than the first deviation threshold value, and the absolute value of the feedback correction amount is the first. When it is maintained below the second correction amount threshold smaller than the first correction amount threshold, it is determined that the learning of the idle speed control is unnecessary, and further, the engine control device determines that the learning of the idle speed control is unnecessary. , Idle speed control Judge normal in self-diagnosis.

By determining that learning of idle speed control is unnecessary and determining normality in the idle speed self-diagnosis, the engine can be stopped at an early stage.

In ISC-OBD, if ISC is normal, fuel consumption can be suppressed by stopping the engine at an early stage, and even if the engine is stopped, ISC-OBD is executed after the time required for abnormality determination has elapsed. By counting up the number of times, the execution record of ISC-OBD can be increased.

It is a figure which shows the schematic structure of the system including the engine control device and an engine of this embodiment. It is a block diagram related to idle speed control. It is a flowchart related to learning of idle speed control. It is a flowchart which concerns on the idle speed control self-diagnosis.

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

The engine 10 idles when a driving force is not required, such as when the vehicle stops. Further, in order to suppress fuel consumption due to idling, automatic stop (idling stop) is performed when a predetermined condition is satisfied. Then, when the driving force is required, it is restarted. For the idling speed, for example, the intake air amount is finely adjusted and the ignition timing is adjusted by the opening degree of the throttle valve 30, particularly the opening degree of the idle speed control valve arranged in parallel with the main valve. Is controlled. The target value of the idle rotation speed is set in advance, and the 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 associated and stored as a control map, and the engine rotation speed is the torque command value. Feedback is given via. As shown in FIG. 2, the value of the control parameter such as the opening degree of the throttle valve 30 is 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, the torque correction amount is calculated with reference to the control map based on the deviation (B42), and is fed back to the torque command value. For example, when the actual idle rotation 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 the increased torque command value. As a result, the rotation speed increases. 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 the time of idling, but the friction of the engine 10 changes due to individual differences of the engine 10 and aging, and the target rotation The torque required for speed changes. In order to cope with this change, engine control that learns idle speed control (ISC learning) that learns and updates an appropriate torque command value is known. During one operation of the vehicle, that is, during the period from when the ignition switch is turned on to when it is turned off, the torque command value when the target rotation speed is reached at the first idling after the engine has warmed up is memorized. That is, after learning, this command value is used as an initial value at the start of idling thereafter. After the start of idling, the torque command value changes based on the feedback control, but the learned torque command value is maintained. In the next operation, idling is started with the torque command value learned in the previous operation as the initial value until the ISC learning is executed.

In a vehicle that performs idling stop, if ISC learning has not yet been performed in a certain operation, idling stop is prohibited, idling is forcibly performed, and ISC learning is performed during that time. This secures opportunities for ISC learning. On the other hand, when it is not necessary to perform ISC learning again, such as when the engine idling is stable, idling for ISC learning increases fuel consumption. In the engine control device 12, idling is stopped at an early stage to stop the engine when ISC learning is not required.

FIG. 3 is a diagram showing a control flow when idling is forcibly executed for ISC learning when an idling stop command is given. First, it is determined whether the conditions for performing ISC learning are satisfied (S100). This condition is that the engine is currently in operation, the cooling water temperature of the engine 10 is at least a predetermined value, and in the current operation, the cooling water temperature at the start of operation is at least a predetermined value. .. Do not dare to start the engine when it is not running, that is, when it is stopped. Further, ISC learning is performed in a state where the cooling water temperature is equal to or higher than a predetermined value, for example, 70 ° C. or higher, and the temperature is sufficiently warm. Further, when the cooling water temperature at the start of operation is high, almost no time has passed since the previous operation, and it is considered that there is almost no change in the engine from the previous operation, so that ISC learning is considered unnecessary. If the conditions for ISC learning are not satisfied, the engine is stopped (S102). If the conditions for ISC learning are satisfied, the process proceeds to step S104.

Step S104 is a step for determining whether the idling state such as the idle rotation speed has changed from the past, and if the change is sufficiently small, the idle stop is executed without performing ISC learning. The specific contents will be described after the explanation of the steps related to ISC learning.

In step S104, when the idling state has changed from before, the process proceeds 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 the first deviation threshold value DLNT1), and the engine torque is corrected for feedback. The absolute value DLQ of the amount (hereinafter referred to as feedback correction amount) is compared with a predetermined value (hereinafter referred to as first correction amount threshold DLQT1). The absolute value DLN of the deviation of the engine rotation speed is smaller than the first deviation threshold DLNT1 (DLN <DLNT1), and the absolute value DLQ of the feedback correction amount is smaller than the first correction amount threshold DLQT1 (DLQ <DLQT1). However, if it continues for the 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 set to, for example, 3 seconds. After the update, the engine is stopped (S102). In the subsequent idling, this updated torque command value is used. Further, 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 the lapse of time t1. On the other hand, if the condition of step S106 is not satisfied, the initial value of the torque command value is not updated and the engine is stopped.

The explanation will be given by returning to step S104. In step S104, the absolute value DLN of the deviation of the engine rotation speed is compared with a predetermined value (hereinafter, referred to as a second deviation threshold value DLNT2), and the absolute value DLQ of the feedback correction amount is a predetermined value (hereinafter, the second). 2 Corrected amount threshold value is referred to as DLQT2). The second deviation threshold DLNT2 is a value smaller than the first deviation threshold DLNT1 (DLNT2 <DLNT1), and can be, 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, for example, 0.1 Nm. In step S104, the absolute value DLN of the deviation of the engine rotation speed is smaller than the second deviation threshold value DLNT2 (DLN <DLNT2), and the absolute value DLQ of the feedback correction amount is smaller than the second correction amount threshold value DLQT2 (DLQ). <DLQT2) is determined. In step S104, the width of determination of the absolute value DLN of the deviation of the engine rotation speed and the absolute value DLQ of the feedback correction amount is narrower than that in the case of ISC learning. It can be understood that the change from is small. In other words, it is considered unnecessary to perform ISC learning again.

When the state in which the condition of step S104 is satisfied continues for the 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. As a result, if there is no change in the idling state, the engine can be stopped at an early stage, and fuel consumption can be suppressed accordingly.

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

The engine control device 12 has a function of self-diagnosing (ISC-OBD) whether or not the idle speed control (ISC) is operating normally. Specifically, when the rotation speed does not converge even after a predetermined time (for example, 10 seconds) has elapsed since the start of idling, and the rotation speed remains equal to or higher than the upper limit value or the lower limit value of the predetermined range during idling. , ISC abnormality is determined. If ISC-OBD has already been executed in one operation, it will not be executed again in the same operation. Further, each time the ISC-OBD is executed, the number of executions is accumulated and the execution result is recorded. It may be required that the number of times ISC-OBD is executed is a predetermined ratio to the total number of operations, that is, a predetermined frequency or more. That is, it may be required that the value obtained by dividing the number of executions of ISC-OBD by the total number of operations (hereinafter referred to as self-diagnosis rate) becomes a predetermined value or more (for example, one-third or more).

In ISC-OBD, if the conditions of step S104 and step S112 of FIG. 2 described above are satisfied, it can be determined that the ISC is functioning normally. That is, if the absolute value DLN of the deviation of the engine rotation speed is smaller than the second deviation threshold DLNT2, the absolute value DLQ of the feedback correction amount is smaller than the second correction amount threshold DLQT2, and this state continues for time t2. , ISC can be determined to be normal. The time required for this normal determination is shorter than the time required for the above-mentioned abnormality determination. If the idling stop is performed after the normal determination is made, the fuel consumption can be suppressed as compared with the case where the idling is continued until the time required for the abnormality determination elapses. Further, when the normality determination is made, the number of times the ISC-OBD is executed is counted up when the time required for the abnormality determination elapses from the start of the ISC-OBD. This helps to secure the self-diagnosis rate.

FIG. 4 is a diagram showing a control flow related to ISC-OBD. When the ISC-OBD determines that the ISC is normal (S120), the engine 10 is stopped (S124). The normality determination can be made when the idle rotation speed has converged to a predetermined value. For example, the normality of ISC can be determined when the conditions of steps S104 and S112 shown in FIG. 3 (the same conditions as the ISC learning unnecessary determination) are satisfied. Alternatively, instead of this, the normality of the ISC can be determined when the conditions of steps S106 and 108 shown in FIG. 3 (the same conditions as the ISC learning completion determination) are satisfied. Further, in steps S104 and S106, it is a condition that both the condition related to the absolute value DLN of the deviation of the engine rotation speed and the condition related to the absolute value DLQ of the feedback correction amount are satisfied, but the condition is not limited to this. If either one is true, it may be normal. Further, the conditions for determining normality may be set separately from the above-mentioned conditions related to ISC learning.

When the normality is not determined in step S120, the process proceeds to step S122, and it is determined whether or not the time t3 has elapsed since the start of ISC-0BD. This time t3 is the time required for determining an abnormality in ISC-OBD. In step S122, if the time t3 has not elapsed, the process returns to step S120, and if it has elapsed, the control related to ISC-OBD ends.

After the engine is stopped in step S124, it is determined in step S126 whether the engine is stopped, that is, the engine is not restarted, and if the engine is not stopped (restarted), the ISC-OBD is displayed. The control concerned is terminated. If the engine is stopped and the time t3 has not elapsed from the start of ISC-OBD, the process returns to step S126 to determine whether the engine is stopped, while if the time t3 has elapsed, the process proceeds to step 130 (S128). ). As described above, the time t3 is the time required for determining an abnormality in ISC-OBD. In step S130, the number of times ISC-OBD is executed is counted up, and then this control flow ends.

By determining normality before the time required to determine ISC abnormality has elapsed and stopping the engine based on this normality determination, idling is performed until the time required to determine ISC abnormality has elapsed. Fuel consumption can be reduced as compared to the case of continuing. Further, even when the engine is stopped, the execution record of ISC-OBD can be increased by counting up the number of times of execution of ISC-OBD after the time required for determining the abnormality of ISC has elapsed.

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 The deviation between the actual value of the engine rotation speed and the target value Absolute value, DLNT1 first deviation threshold, DLNT2 second deviation threshold, absolute value of DLQ feedback correction amount, DLQT1 first correction amount threshold, DLQT2 second correction amount threshold.

Claims (2)

In an engine control device having an idle speed control self-diagnosis function that determines whether idle speed control that feedback-controls the idle rotation speed to a target value is functioning normally.
In the idle speed control self-diagnosis, if a normal determination is made before the time required for abnormality determination elapses, the engine is stopped, the stopped state of the engine is maintained, and the idle speed control self-diagnosis is started. An engine control device that counts up the number of times the idle speed control self-diagnosis is executed after the time required for abnormality determination has elapsed. In the engine control device according to claim 1,
The idle speed control is feedback controlled via the engine torque command value.
In the engine control device, during the idle speed control, the absolute value of the deviation of the rotation speed with respect to the target value is equal to or less than the first deviation threshold value, and the absolute value of the feedback correction amount is equal to or less than the first correction amount threshold value. 1 When the engine is maintained for a predetermined time, the idle speed control learning to update the initial command value at the time of idling to the value at that time is performed.
Further, in the engine control device, the absolute value of the deviation of the rotation speed is equal to or less than the second deviation threshold value smaller than the first deviation threshold value during the second predetermined time shorter than the first predetermined time, and the above-mentioned engine control device is used. When the absolute value of the feedback correction amount is maintained below the second correction amount threshold value smaller than the first correction amount threshold value, it is determined that learning of the idle speed control is unnecessary.
Further, when the engine control device determines that learning of the idle speed control is unnecessary, the engine control device determines normality in the idle speed control self-diagnosis.
Engine control device.

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