Controller of internal combustion engine

Abstract

To provide a controller of an internal combustion engine capable of suppressing erroneous detection of decrease in engine speed due to clutch operation as an abnormal state.SOLUTION: A controller of an internal combustion engine is mounted on a vehicle equipped with a manual transmission and comprises an ISC monitor that monitors an engine speed during idling operation. When an abnormality occurs in which the engine speed deviates from a target speed, the ISC monitor detects this phenomenon as an abnormal state of decrease in engine speed. A period in which the difference between the engine speed, which is an input shaft speed of a clutch, and an input shaft speed of a manual transmission, which is an output shaft speed of the clutch, is equal to or larger than a predetermined value (step S120: NO) is excluded from an abnormality diagnosis object by the ISC monitor (step S140).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a control device for an internal combustion engine.

Background Art

[0002] Patent Document 1 discloses a rotational speed control device for an internal combustion engine mounted on a vehicle provided with a manual transmission. The vehicle is provided with a half-clutch detection switch that detects a half-clutch state when the clutch pedal is in the half-clutch position.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A control device for an internal combustion engine performs ISC (Idle Speed Control) to maintain the engine speed at a target speed during idling operation. Despite performing ISC, an abnormality may occur where the engine speed deviates from the target speed.

[0005] In order to detect such an ISC abnormality, it is conceivable to provide an ISC monitor that monitors the engine speed during idling operation. However, in a vehicle equipped with a manual transmission, the engine speed may decrease when the driver operates the clutch to enter the half-clutch state. In such a case, although there is no abnormality in the engine, the engine speed deviates from the target speed. Therefore, it is misdetected as an abnormal state of a decrease in the engine speed by the ISC monitor.

Means for Solving the Problems

[0006] Means for solving the above problems and their effects will be described below. A control device for an internal combustion engine for solving the above problems is a control device for an internal combustion engine mounted on a vehicle provided with a manual transmission, and includes an ISC monitor that monitors the engine speed during idling operation. When an abnormality occurs in which the engine speed deviates from the target speed, the ISC monitor detects it as an abnormal state of engine speed decrease. The ISC monitor excludes, from the target of abnormality diagnosis by the ISC monitor, a period during which the difference between the engine speed, which is the input shaft speed of the clutch, and the input shaft speed of the manual transmission, which is the output shaft speed of the clutch, is equal to or greater than a predetermined value.

Advantages of the Invention

[0007] The above control device for an internal combustion engine can suppress misdetection of a decrease in engine speed due to clutch operation as an abnormal state.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Hereinafter, an embodiment of a control device for an internal combustion engine will be described with reference to FIGS. 1 to 3. <Configuration of a Control System of a Vehicle Equipped with a Manual Transmission 100> FIG. 1 schematically shows a control system including a control device 50 for an internal combustion engine.

[0010] As shown in FIG. 1, the control system includes an engine 10, a clutch 40, a manual transmission 100, and a control device 50. The engine 10 uses an internal combustion engine that converts combustion gas generated by burning fuel into power as a prime mover. The clutch 40 is attached between the output shaft 70 of the engine 10 and the input shaft 80 of the manual transmission 100. The clutch 40 transmits or cuts off the driving force of the engine 10 to the manual transmission 100 by the driver's operation. The manual transmission (MT) 100 is a manual transmission that the driver selects and operates the reduction ratio (gear).

[0011] An engine rotation sensor 20 (hereinafter referred to as Ne sensor 20) for detecting the engine rotation speed NE, which is the rotation speed of the output shaft 70 of the engine 10, is provided in the engine 10. The Ne sensor 20 is connected to the control device 50. Information on the engine rotation speed NE detected by the Ne sensor 20 is input to the control device 50. An input shaft rotation sensor 30 (hereinafter referred to as Ni sensor 30) for detecting the input shaft rotation speed NI, which is the rotation speed of the input shaft 80 of the manual transmission 100, is provided in the manual transmission 100. The Ni sensor 30 is connected to the control device 50. Information on the input shaft rotation speed NI detected by the Ni sensor 30 is input to the control device 50.

[0012] The control device 50 performs ISC to control the engine rotation speed NE to the target rotation speed during idling operation. The control device 50 has an ISC monitor 51 that monitors the engine rotation speed NE during idling operation. The ISC monitor 51 monitors whether the ISC is being performed normally and determines the presence or absence of an abnormality. The ISC monitor 51 measures the time during which the engine rotation speed NE deviates from the target rotation speed during idling operation and determines the presence or absence of an abnormality.

[0013] The control device 50 is connected to an idle switch 60 (hereinafter referred to as the idle SW60). The idle SW60 is a switch that detects that the accelerator is not being operated. The idle SW60 turns "ON" when the accelerator is not being operated. The idle SW60 turns "OFF" when the accelerator is being operated. Information indicating whether the idle SW60 is "ON" or "OFF" is input to the control device 50.

[0014] <Abnormality diagnosis by the ISC monitor 51> Hereinafter, with reference to FIG. 2, the flow of the process executed by the ISC monitor 51 will be specifically described. This series of processes is executed by the ISC monitor 51 when the idling operation is being performed under the condition that the preconditions are satisfied.

[0015] The idling operation is a state in which the engine 10 is running with the shift position of the manual transmission 100 in the neutral state and the accelerator not being operated. During the idling operation, the ISC is executed by the control device 50.

[0016] The preconditions are conditions for determining that the state is suitable for monitoring the state of the ISC. When it is cold, the engine speed NE is unstable. Also, immediately after the engine 10 is started, the engine speed NE is unstable. These states are not suitable for monitoring the state of the ISC. Therefore, the control device 50 determines that the preconditions are satisfied when both of the following two conditions are satisfied.

[0017] · It is not cold. · A certain period of time has elapsed since the engine 10 was started. Here, the certain period of time is, for example, several seconds.

[0018] As shown in FIG. 2, when starting this series of processes, the ISC monitor 51 executes the process of step S120. In the process of step S120, the ISC monitor 51 determines whether the difference (|NE - NI|) between the engine speed NE and the input shaft speed NI is equal to or greater than a predetermined value.

[0019] In step S120, if it is determined that the difference between the engine speed NE and the input shaft speed NI is smaller than the predetermined value (step S120: YES), the ISC monitor 51 advances the process to step S130. Then, in the process of step S130, the ISC monitor 51 starts the monitor.

[0020] When starting the monitor, as described above, the ISC monitor 51 measures the time during which the engine speed NE deviates from the target speed. Specifically, the ISC monitor 51 measures the time during which the engine speed NE deviates from the target speed by a predetermined amount or more while the monitor is being executed. The time thus measured by the ISC monitor 51 is the abnormal detection time. Also, the ISC monitor 51 measures the time during which the monitor is being performed as the monitor time.

[0021] After starting the monitor in step S130, the ISC monitor 51 advances the process to step S150 and determines whether the monitor time has exceeded a first predetermined value. If it is determined that the ISC monitor time has exceeded the first predetermined value (step S150: YES), the ISC monitor 51 advances the process to step S160. The first predetermined value is, for example, 10 seconds.

[0022] On the other hand, if it is determined that the monitor time has not exceeded the first predetermined value (step S150: NO), the ISC monitor 51 returns the process to step S120. Also, when the ISC monitor 51 determines in step S120 that the difference between the engine speed NE and the input shaft speed NI is equal to or greater than a predetermined value (step S120: NO), the process proceeds to step S140. In the process of step S140, the ISC monitor 51 stops the monitoring. When the monitoring is stopped, the measurement of the abnormal detection time and the monitoring time stops. Then, the ISC monitor 51 returns the process to step S120.

[0023] In this way, the ISC monitor 51 repeatedly executes the processes of steps S120 to S140 until the monitoring time exceeds the first predetermined value. When the difference between the engine speed NE and the input shaft speed NI becomes less than the predetermined value after the monitoring is stopped, the monitoring is restarted. In this case, the measurement of the abnormal detection time and the monitoring time continues from the values at the time of stoppage.

[0024] In step S160, the ISC monitor 51 determines whether the abnormal detection time exceeds a second predetermined value. The second predetermined value is, for example, 3 seconds. When the ISC monitor 51 determines that the abnormal detection time exceeds the second predetermined value (step S160: YES), the process proceeds to step S170. In step S170, the ISC monitor 51 determines that an abnormality has occurred in the ISC and ends the process. On the other hand, when the ISC monitor 51 determines in step S160 that the abnormal detection time does not exceed the second predetermined value (step S160: NO), the process proceeds to step S180. In step S180, the ISC monitor 51 determines that the ISC is normal and ends the process.

[0025] <Operation of this Embodiment> The control device 50 of the internal combustion engine includes an ISC monitor 51 that monitors the engine speed NE during idling operation. When an abnormality occurs in which the engine speed NE deviates from the target speed, the ISC monitor 51 detects it as an abnormal state of engine speed reduction. However, the ISC monitor 51 excludes a period during which the difference between the engine speed NE and the input shaft speed NI of the manual transmission 100 is equal to or greater than a predetermined value from the target of the abnormality diagnosis by the ISC monitor 51.

[0026] Referring to FIG. 3, the operation of this embodiment will be described while showing an example. In the example shown in FIG. 3, at timing T1, the driver depresses the clutch pedal and turns on the ignition switch to start the engine 10. As shown in FIG. 3(d), when the driver depresses the clutch pedal, the clutch stroke increases and the power transmission by the clutch 40 is interrupted. With the power transmission by the clutch 40 interrupted, the ignition switch is turned on to start the engine 10. As a result, as shown by the solid line in FIG. 3(a), the engine speed NE increases and the engine 10 starts. After starting, the engine speed NE is controlled by the ISC and the operation shifts to idling operation.

[0027] As shown in FIG. 3(b), the vehicle speed is "0" at this time. As shown in FIG. 3(c), the idle switch 60 is "ON" at this time. As shown in FIG. 3(e), the shift position of the manual transmission 100 is in neutral at this time. In FIG. 3(e), the neutral state is shown as "N".

[0028] At timing T2 after a certain period has elapsed since the engine 10 started, the series of processes shown in FIG. 2 is started. In the example shown in FIG. 3, at timing T2, the clutch pedal is released by the driver. As a result, as shown in FIG. 3(d), the clutch stroke becomes "0" and the clutch 40 is engaged. Consequently, the engine speed NE, which is the input shaft rotational speed of the clutch 40, and the input shaft rotational speed NI of the manual transmission 100, which is the output shaft rotational speed of the clutch 40, match. At this time, due to the engagement of the clutch 40, as indicated by the dashed line in FIG. 3(a), the input shaft rotational speed NI is pulled up to match the engine speed NE.

[0029] During the period from timing T2 to timing T3, since the engine speed NE and the input shaft rotational speed NI match (step S120: YES), the monitoring by the ISC monitor 51 continues to be executed. In FIG. 3, the period during which such monitoring continues is indicated as the "monitoring period". The monitoring period is the period subject to abnormality diagnosis by the ISC monitor 51.

[0030] In the example shown in FIG. 3, at timing T3 during idling operation, the clutch pedal is depressed again by the driver. As shown in FIG. 3(d), when the driver depresses the clutch pedal, the clutch stroke increases and the power transmission by the clutch 40 is interrupted. As a result, from timing T3, the input shaft rotational speed NI decreases and the engine speed NE and the input shaft rotational speed NI deviate. When the difference between the engine speed NE and the input shaft rotational speed NI becomes equal to or greater than a predetermined value (step S120: NO), the monitoring is stopped. Thereby, the monitoring period ends.

[0031] In the example shown in FIG. 3, at timing T4, as shown in FIG. 3(e), the driver is operating the shift position of the manual transmission 100 to the first gear. Then, as shown in FIG. 3(d), while gradually releasing the clutch pedal, the driver operates the accelerator pedal to start the vehicle.

[0032] The idling operation has ended because the idle switch 60 turns "OFF" at timing T5. During the idling operation, the driving force of the engine 10 is transmitted from the input shaft of the clutch 40 to the output shaft of the clutch 40. Since the shift position is in the neutral state during the idling operation, the output shaft of the clutch 40 rotates freely. Therefore, the engine speed NE, which is the input shaft rotation speed of the clutch 40, and the input shaft rotation speed NI of the manual transmission 100, which is the output shaft rotation speed of the clutch 40, are the same (timing T2 to timing T3).

[0033] When the driver performs a clutch operation from this state, the transmission of the driving force from the input shaft side to the output shaft side of the clutch 40 stops. Therefore, the input shaft rotation speed NI decreases, and the engine speed NE and the input shaft rotation speed NI deviate from each other (after timing T3). Thus, when the driver performs a clutch operation during the idling operation, the engine speed NE and the input shaft rotation speed NI deviate from each other.

[0034] Thus, when the driver's clutch operation causes a semi-clutch state when the input shaft rotation speed NI is lower than the engine speed NE, the engine speed NE decreases. As a result, there is a possibility of false detection as an abnormal state of the engine speed decrease by the ISC monitor 51. Therefore, the above internal combustion engine control device 50 excludes the period during which the difference between the engine speed NE and the input shaft rotation speed NI is equal to or greater than a predetermined value from the target of the abnormality diagnosis by the ISC monitor 51. Thereby, this control device 50 excludes the period during which the driver operates the clutch 40, which is a period during which a semi-clutch state may occur, from the target of the abnormality diagnosis by the ISC monitor 51.

[0035] <Advantages of the present embodiment> This control device 50 excludes the period during which the driver operates the clutch 40, which is a period during which a semi-clutch state may occur, from the target of the abnormality diagnosis by the ISC monitor 51.

[0036] Therefore, the above-described internal combustion engine control device 50 can suppress the erroneous detection of a decrease in the engine speed due to clutch operation as an abnormal state.

Explanation of Signs

[0037] 10…Engine 20…Ne sensor 30…Ni sensor 40…Clutch 50…Control device 51…ISC monitor 60…Idle SW 70…Output shaft of the engine 80…Input shaft of the manual transmission 100…Manual transmission

Claims

[Claim 1] A control device for an internal combustion engine mounted on a vehicle equipped with a manual transmission, Equipped with an ISC monitor that monitors engine speed during idling. The ISC monitor is: If an abnormality occurs in which the engine speed deviates from the target speed, this is detected as an abnormal state of engine speed drop. A period during which the difference between the engine speed, which is the input shaft speed of the clutch, and the input shaft speed of the manual transmission, which is the output shaft speed of the clutch, is equal to or greater than a predetermined value is excluded from the targets of abnormality diagnosis by the ISC monitor. A control device for an internal combustion engine.

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