JP2010127162A - Fail-safe device for throttle control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detrimental effects of fail-safe due to erroneous detection of abnormality, in a fail-safe device for a throttle control system. <P>SOLUTION: When an abnormality is detected where generated torque of an engine exceeds the required torque by an abnormal determination value or more, the operation transfers to a fail-safe mode. In the fail-safe mode, the fail-safe device compares a target throttle opening degree for engine control arithmetically calculated by the CPU 1 and a target throttle opening degree for engine control arithmetically calculated by the CPU 2, and if a state in which a difference between both becomes equal to or greater than a predetermined value continues for a predetermined time period or longer, it is determined as a true abnormality. If it is determined as a true abnormality, the fail-safe device causes a warning lamp to be lit or warns a driver, as well as executes additional fail-safe (e.g., energization cut-off of throttle motor 15, fuel cut-off) to reduce generated torque of the engine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fail-safe device for a throttle control system that adjusts the throttle opening of an internal combustion engine to a fail-safe throttle opening when an abnormality in the throttle control system or the like is detected.

  In a throttle control system installed in an automobile, the accelerator pedal depression amount (accelerator operation amount) is detected by an accelerator sensor, a target throttle opening is set according to the detected value, and the throttle opening detected by the throttle sensor In some cases, the motor that drives the throttle valve is feedback-controlled so that is matched with the target throttle opening.

  In this throttle control system, as described in Japanese Patent Application Laid-Open No. 4-350332, for fail-safe, when an abnormality of the throttle sensor is detected, the motor and the throttle valve are connected. The electromagnetic clutch is turned off to stop the throttle control, and after that, there is one that shifts to retreating that adjusts the throttle opening mechanically in conjunction with the accelerator pedal depression, and displays an abnormality warning. .

Also, in order to prevent the vehicle from running away, the engine generated torque is monitored. When the engine generated torque exceeds the required torque and exceeds the allowable value, it is determined that there is an abnormality and the generated torque is reduced. Some safe measures (for example, energization cut of a throttle motor, fuel cut, etc.) are performed. During this fail safe operation, the generated torque of the engine is suppressed and the running performance of the vehicle is severely limited. Therefore, a warning lamp is lit to warn the driver to bring the vehicle to a maintenance shop such as a dealer. I am doing so.
JP-A-4-350332

  By the way, it is desirable that the fail-safe state does not occur, but due to various uncertain disturbances, the possibility of fail-safe due to erroneous detection of an abnormality is not low. For this reason, there is a demand for reducing the traveling performance of the vehicle as much as possible even when shifting to fail-safe.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a fail-safe device of a throttle control system that can improve the adverse effects of fail-safe due to erroneous detection of an abnormality.

  In order to achieve the above object, the invention according to claim 1 is directed to a fail-safe device of a throttle control system for controlling the throttle opening of an internal combustion engine to coincide with a target throttle opening, the throttle control system and the internal combustion engine. An abnormality diagnosis means for executing an abnormality diagnosis of at least one of the output control systems, and a fail-safe mode for adjusting the throttle opening of the internal combustion engine to a fail-safe target throttle opening when an abnormality is detected by the abnormality diagnosis means And fail-safe monitoring means for monitoring whether or not the abnormality diagnosis result of the abnormality diagnosis means is due to erroneous detection during the fail-safe mode.

  According to this configuration, when the failure diagnostic means shifts to the fail safe mode when an abnormality is detected, the fail safe monitoring means monitors whether the abnormality diagnosis result of the abnormality diagnosis means is due to false detection. It becomes possible to take measures so as to prevent fail-safe due to erroneous detection from continuing without knowing that it is erroneous detection.

  Specifically, as in claim 2, when the fail-safe monitoring means determines that the abnormality diagnosis result of the abnormality diagnosis means is due to erroneous detection, the control mode of the throttle control system is changed from the fail-safe mode to the normal time ( It is better to return to the normal control mode. In this way, even after the transition to the fail-safe mode, if it is confirmed that the diagnosis target of the abnormality diagnosis means is operating normally, it is possible to immediately return to the normal (normal) control mode.

  Further, as described in claim 3, when the fail-safe monitoring means determines that the abnormality diagnosis result of the abnormality diagnosis means is not a false detection but a real abnormality, the warning means is activated to warn the driver. It is good to make it. In this way, even if the failure safe mode is entered, it is not necessary to activate the warning means until it is confirmed that there is a real abnormality. This eliminates the need for the driver to notice that the vehicle has shifted to, and eliminates unnecessary concern for the driver.

  According to a fourth aspect of the present invention, an additional fail-safe measure for suppressing the output of the internal combustion engine when it is determined by the fail-safe monitoring means that the abnormality diagnosis result of the abnormality diagnosis means is not abnormal detection but really abnormal. It is better to run. This makes it possible to control the throttle control system so as not to impair the driving performance of the vehicle until it is confirmed that the vehicle is actually abnormal even after the transition to the fail-safe mode. If it is confirmed, it is possible to immediately suppress the output of the internal combustion engine by executing an additional fail-safe measure.

  Further, as in claim 5, the first CPU for calculating the target throttle opening used in the normal (normal) control mode, and an input substantially the same as or simpler than the input of the first CPU And a second CPU for calculating a fail-safe target throttle opening based on the converted input, and the fail-safe monitoring means detects the target throttle opening and the fail-safe target throttle opening during the fail-safe mode. Based on the difference, it may be monitored whether or not the abnormality diagnosis result of the abnormality diagnosis means is due to erroneous detection. As described above, if the second CPU calculates the fail-safe target throttle opening based on the input that is substantially the same as or simplified from the input of the first CPU, the system can When functioning normally, the target throttle opening calculated by the first CPU and the target throttle opening for fail-safe calculated by the second CPU substantially coincide with each other. If the difference between the target throttle opening and the fail-safe target throttle opening is small to some extent during the fail-safe mode, the abnormality diagnosis result of the abnormality diagnosis means is due to false detection. Judgment can be made.

  In this case, as in claim 6, the target throttle opening calculated by the first CPU and the target throttle opening for fail safe calculated by the second CPU during the fail safe mode are compared, and the smaller one is finally determined. It is preferable that the target throttle opening for failsafe is selected to adjust the throttle opening of the internal combustion engine to the final target throttle opening for failsafe. In this way, even if the second CPU that calculates the fail-safe target throttle opening malfunctions or fails, fail-safety can be ensured.

  The inventions according to claims 1 to 6 described above embody a technical idea that supplements the reliability of abnormality diagnosis of the abnormality diagnosis means, but in a system with high reliability of abnormality diagnosis of the abnormality diagnosis means. On the other hand, the fail-safe function may be supplemented by assuming that the abnormality diagnosis result of the abnormality diagnosis means is reliable.

  As a means for supplementing this fail-safe function, a fail-safe monitoring means for monitoring whether or not the fail-safe operation by the fail-safe means is operating correctly during the fail-safe mode may be provided as in claim 7. In a system in which the abnormality diagnosis of the abnormality diagnosis unit is highly reliable, the reliability of the fail safe operation can be improved only by monitoring whether or not the fail safe operation is working correctly during the fail safe mode.

  In this case, as in claim 8, when it is determined that the fail-safe operation by the fail-safe means does not work correctly during the fail-safe mode, an additional fail-safe measure for suppressing the output of the internal combustion engine is executed. It is good to make it. In this way, if it is confirmed that the fail-safe operation is not working correctly during the fail-safe mode, an additional fail-safe measure can be immediately executed to reliably suppress the output of the internal combustion engine.

  Further, as in the ninth aspect, the failsafe target is based on the first CPU for calculating the target throttle opening and the input substantially the same as or simpler than the input of the first CPU. A second CPU for calculating the throttle opening, based on a duration of a state in which the difference between the target throttle opening and the fail-safe target throttle opening is equal to or greater than a predetermined value during the fail-safe mode by the fail-safe monitoring means. It is better to monitor whether or not the fail-safe operation by the fail-safe means is working correctly. If the fail safe operation is working correctly during the fail safe mode, the fail safe target throttle opening calculated by the second CPU is different from the abnormal target throttle opening calculated by the first CPU. If the state where the difference between the target throttle opening and the failsafe target throttle opening is equal to or greater than a predetermined value (a state where the difference is large) continues to some extent, it can be determined that the failsafe operation is working correctly.

  Also in this case, the target throttle opening calculated by the first CPU and the target throttle opening for fail-safe calculated by the second CPU during the fail-safe mode are compared, and the smaller one is finally determined. The target throttle opening for failsafe may be selected to adjust the throttle opening of the internal combustion engine to the final target throttle opening for failsafe. In this way, even if the second CPU that calculates the fail-safe target throttle opening malfunctions or fails, fail-safety can be ensured.

  Hereinafter, two Examples 1 and 2, which embody the best mode for carrying out the present invention, will be described.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 which is an internal combustion engine, and an air flow meter 14 for detecting the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a throttle motor 15 and a throttle opening sensor 17 that detects the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14. . A surge tank 18 is provided downstream of the throttle valve 16, and an intake manifold 20 for introducing air into each cylinder of the engine 11 is provided in the surge tank 18, and in the vicinity of the intake port of the intake manifold 20 of each cylinder. Further, a fuel injection valve 21 for injecting fuel is attached. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  A cooling water temperature sensor 26 that detects the cooling water temperature is attached to the cylinder block of the engine 11. The crankshaft 27 of the engine 11 is fitted with a signal rotor 29 having teeth formed at a predetermined crank angle pitch on the outer periphery, and a crank angle sensor 28 is attached to face the outer periphery of the signal rotor 29. A crank pulse signal is output from the crank angle sensor 28 every time the teeth of the rotor 29 face the crank angle sensor 28 (each time the crankshaft 27 rotates a predetermined crank angle). The engine speed is detected from the cycle (pulse output frequency) of the output pulse of the crank angle sensor 28. Although not shown, a cam angle sensor is provided that outputs a cam pulse signal at a predetermined cam angle in synchronization with the rotation of the cam shaft of the engine 11.

  Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and controls the fuel injection amount and injection timing of the fuel injection valve 21 and the ignition timing of the spark plug 22 according to the engine operating state detected by various sensors.

Next, a fail-safe function mounted on the ECU 30 will be described based on FIG.
The ECU 30 is equipped with functions such as a torque monitoring unit 31, a fail safe unit 32, a fail safe monitoring unit 33, a warning display control unit 34, a fuel injection control unit 35, an ignition control unit 36, and a throttle control unit 37. .

  Here, the torque monitoring unit 31 (abnormality diagnosis means) monitors the requested torque calculated according to the accelerator depression amount and the generated torque of the engine 11, and determines that the generated torque of the engine 11 is more abnormal than the required torque. When the value exceeds the value, an abnormality is diagnosed, and the diagnosis result is transmitted to the fail safe unit 32.

  The fail-safe unit 32 receives an abnormality diagnosis result from the torque monitoring unit 31 and an additional fail-safe measure for reducing the torque generated by the engine 11 when receiving a later-described abnormal signal from the fail-safe monitoring unit 33. (For example, the energization cut of the throttle motor 15, the fuel cut, etc.) are performed.

  The warning display control unit 34 (warning means) turns on (or flashes) a warning lamp when the fail safe unit 32 executes an additional fail safe measure, or displays a warning display unit (see FIG. (Not shown) to warn the driver. The fuel injection control unit 35 controls the injection amount (injection pulse width) of the fuel injection valve 21 of each cylinder and the fuel injection timing according to the required fuel injection amount. The ignition control unit 36 controls the ignition timing of the spark plug 22 based on the required ignition timing set according to the operating state of the engine 11 and the like.

  The throttle control unit 37 (fail-safe means) includes a first CPU (hereinafter referred to as “CPU1”) for calculating a target throttle opening for engine control used in a normal (normal) control mode, and an input of the CPU1. The configuration includes a second CPU (hereinafter referred to as “CPU2”) that calculates the target throttle opening for fail-safe based on substantially the same input or an input simplified more than that. Further, the CPU 2 also functions as a target throttle opening selection unit 38, and compares the engine control target throttle opening and the failsafe target throttle opening in the fail-safe mode with the smaller one being the final target throttle opening. And the final target throttle opening signal is output to the throttle drive circuit 39, and the throttle motor 15 is driven by the throttle drive circuit 39 to finalize the opening degree of the throttle valve 16 (throttle opening degree). Match the target throttle opening. Even in the normal (normal) control mode, as in the fail-safe mode, the target throttle opening for engine control and the target throttle opening for fail-safe are compared and the smaller one is selected as the final target throttle opening. Also good. The CPU 1 may have a function as the target throttle opening degree selection unit 38.

  On the other hand, the fail safe monitoring unit 33 (fail safe monitoring means) compares the target throttle opening for engine control calculated by the CPU 1 with the target throttle opening for fail safe calculated by the CPU 2 during the fail safe mode. Based on the difference between the two, it is monitored whether the abnormality diagnosis result is due to erroneous detection or whether it is really abnormal. Specifically, during the fail-safe mode, the engine control target throttle opening and the fail-safe target throttle opening are compared, and a state in which the difference therebetween is equal to or greater than a predetermined value Ath (for example, 30 °) is a predetermined time. If it continues for Cth (for example, 1 second) or more, it is determined as a true abnormality.

  When the fail-safe monitoring unit 33 determines that the abnormality is true, the failure-safe monitoring unit 33 outputs this abnormality signal to the warning display control unit 34 and the fail-safe unit 32 to turn on (or blink) the warning lamp, A warning is displayed on a warning display section (not shown) of the instrument panel to warn the driver, and an additional fail-safe measure (for example, energization cut of the throttle motor 15, fuel cut, etc.) is executed to generate the engine 11 Reduce torque.

  Further, the fail-safe monitoring unit 33, when the difference between the engine control target throttle opening and the fail-safe target throttle opening continues to some extent during the fail-safe mode (for example, a predetermined time from the transition to the fail-safe mode). When it is not determined that there is a real abnormality before the time elapses, or when the difference between the target throttle opening for engine control and the target throttle opening for failsafe is equal to or less than a predetermined value) Determines that the abnormality diagnosis result is due to erroneous detection, and returns the control mode of the throttle control system from the fail-safe mode to the normal (normal) control mode.

  The fail-safe operation of the throttle control system of the first embodiment described above is executed as follows according to the program of FIG. 3 during engine operation. When this program is started, first, in step 101, an abnormality in which the generated torque of the engine 11 becomes excessive depending on whether or not the difference between the generated torque of the engine 11 and the required torque is larger than the abnormality determination value (for example, target It is determined whether or not the throttle opening is stuck. As a result, if it is determined that the difference between the generated torque of the engine 11 and the required torque is equal to or less than the abnormality determination value, it is determined that no abnormality has occurred, and the process proceeds to step 102 where the control mode of the throttle control system is set to normal ( Maintain control mode during normal operation.

  On the other hand, if it is determined in step 101 that the difference between the generated torque of the engine 11 and the required torque is greater than the abnormality determination value, it is determined that an abnormality has occurred, and the process proceeds to step 103. Switch the control mode of the throttle control system to fail-safe mode. During the fail-safe mode, the engine control target throttle opening Ae calculated by the CPU 1 is compared with the fail-safe target throttle opening Af calculated by the CPU 2, and the smaller one is selected as the final target throttle opening. Then, a signal of the final target throttle opening is output to the throttle drive circuit 39 to make the throttle opening coincide with the final target throttle opening. Even in the fail-safe mode, as will be described later, warning display by a warning lamp or the like is not performed until it is determined as a true abnormality.

  Thereafter, the routine proceeds to step 104, where the difference (Ae−Af) between the target throttle opening Ae for engine control calculated by the CPU 1 and the target throttle opening Af for fail safe calculated by the CPU 2 is a predetermined value Ath (for example, 30 °). ), And if the difference (Ae−Af) is larger than the predetermined value Ath, the process proceeds to step 105, and the time counter Cnt (up / down counter) for erroneous detection determination is counted up, and the difference is determined. If (Ae−Af) is less than or equal to the predetermined value Ath, the routine proceeds to step 106 where the time counter Cnt for erroneous detection determination is counted down.

  After that, the routine proceeds to step 107, where it is determined whether or not the count value of the time counter Cnt for determining misdetection [the duration in which the difference (Ae−Af) is equal to or greater than the predetermined value Ath] exceeds the predetermined value Cth. If the count value of the time counter Cnt for misdetection exceeds the predetermined value Cth, the process proceeds to step 108, where it is determined that the abnormality is true, and in the next step 109, the warning lamp is turned on (or flashes). A warning is displayed on a warning display (not shown) on the instrument panel of the driver's seat to warn the driver, and at step 110, additional fail safe (for example, energization cut of the throttle motor 15, fuel cut, etc.) is provided. This is executed to reduce the torque generated by the engine 11.

  On the other hand, if it is determined in step 107 that the count value of the time counter Cnt for erroneous detection determination is equal to or less than the predetermined value Cth, the process proceeds to step 111, where the elapsed time after the transition to the failsafe mode has exceeded the predetermined time. If the predetermined time has not been exceeded, the processing from step 104 onward is repeated.

  Thereafter, when the count value of the time counter Cnt for erroneous detection determination continues to be equal to or less than the predetermined value Cth, and the elapsed time after the transition to the failsafe mode exceeds the predetermined time, the process proceeds from step 111 to step 112, and erroneous detection is performed. And the process returns to step 101. In this case, if the difference between the generated torque of the engine 11 and the required torque is equal to or less than the abnormality determination value, no abnormality has occurred, so the control mode of the throttle control system is changed from the failsafe mode to the normal (normal) control mode. (Step 102).

  In step 111, when the difference between the engine control target throttle opening and the failsafe target throttle opening is equal to or smaller than a predetermined value (small difference) during the fail safe mode for a predetermined time or more. In addition, it may be determined that there is an erroneous detection, and the control mode of the throttle control system may be returned from the fail-safe mode to the normal (normal) control mode.

Next, an example of the fail-safe operation of the throttle control system according to the first embodiment will be described with reference to the time chart of FIG.
In the example of FIG. 4, when an abnormality occurs in which the generated torque of the engine 11 becomes excessive at time t 1, the mode shifts to the fail safe mode. Thereafter, during a period in which the difference (Ae−Af) between the engine control target throttle opening Ae calculated by the CPU 1 and the fail safe target throttle opening Af calculated by the CPU 2 is larger than the predetermined value Ath, The time counter Cnt for erroneous detection determination counts up. Thereafter, a state in which the difference (Ae−Af) is larger than the predetermined value Ath continues, and at the time t2 when the count value of the time counter Cnt for erroneous detection determination exceeds the predetermined value Cth, it is determined that there is a real abnormality and is erroneous. The detection determination flag is set to “1”, the warning lamp is turned on (or flashes) to warn the driver, and additional fail safe is executed to reduce the generated torque of the engine 11.

  In the first embodiment described above, when an abnormality in which the torque generated by the engine 11 becomes excessive is detected, the operation proceeds to the fail safe mode, and the fail safe monitoring unit 33 determines whether or not the abnormality diagnosis result is due to erroneous detection. Since the monitoring is performed, it is possible to prevent the fail-safe due to the erroneous detection of the abnormality from continuing without knowing the erroneous detection.

  Moreover, when the fail-safe monitoring unit 33 determines that the abnormality diagnosis result is not a false detection but a real abnormality, the warning means is activated to warn the driver. However, it is not necessary to activate the warning means until it is confirmed that there is a problem. If the driver shifts to the fail-safe mode due to erroneous detection of the abnormality, the driver does not have to be aware that the switch has been made to the fail-safe mode. , So you don't have to worry about drivers.

  Furthermore, when the fail-safe monitoring unit 33 determines that the abnormality diagnosis result is not a false detection but a real abnormality during the fail-safe mode, an additional fail-safe procedure is executed. However, it is possible to control the throttle control system so as not to impair the driving performance of the vehicle until it is confirmed to be really abnormal. It is possible to execute the safe measure and reliably suppress the output of the engine 11.

  Further, in the first embodiment, the CPU 1 that calculates the target throttle opening for engine control used in the normal (normal) control mode, and the input that is almost the same as or simplified to the input of the CPU 1 Therefore, when the system is functioning normally, the CPU 2 calculates the target throttle opening for engine control calculated by the CPU 1 and the CPU 2 calculates the target throttle opening for fail safe. The target throttle opening for fail-safe is almost the same, so that the running performance of the vehicle in the fail-safe mode can be saved, and the target throttle opening for engine control and the target for fail-safe during fail-safe mode. If the difference from the throttle opening is small, the abnormality diagnosis result may be due to false detection. It can be determined that.

  In this case, the target throttle opening for engine control calculated by the CPU 1 during the fail safe mode and the target throttle opening for fail safe calculated by the CPU 2 are compared, and the smaller one is set as the final target throttle opening for fail safe. Since the throttle opening of the internal combustion engine is selected and adjusted to the final fail-safe target throttle opening, even if the CPU 2 that calculates the fail-safe target throttle opening malfunctions or fails, Fail-safety can be ensured.

  The first embodiment is a technical idea that supplements the reliability of abnormality diagnosis itself, but for a system with high reliability of abnormality diagnosis, the abnormality diagnosis result is regarded as reliable, You may make it supplement a fail safe function. A second embodiment of the present invention that embodies this will be described below with reference to FIGS. However, description of the same parts as those of the first embodiment will be omitted or simplified, and only different parts will be mainly described.

  In the second embodiment, as a means for supplementing the fail-safe function, the ECU 30 is provided with a fail-safe monitoring unit 33 (fail-safe monitoring means) that monitors whether or not the fail-safe operation is working correctly during the fail-safe mode. Yes. In addition, as in the first embodiment, the ECU 30 has functions such as a torque monitoring unit 31, a fail safe unit 32, a warning display control unit 34, a fuel injection control unit 35, an ignition control unit 36, a throttle control unit 37, and the like. It is installed.

  In the second embodiment, when the fail safe monitoring unit 33 determines that the fail safe operation is not working correctly during the fail safe mode, additional fail safe measures (for example, energization cut of the throttle motor 15, fuel cut, etc.) are performed. This is executed to reduce the torque generated by the engine 11.

  Further, the CPU 1 that calculates the target throttle opening for engine control used in the normal (normal) control mode, and the input that is almost the same as the input of the CPU 1 or an input that is more simplified than that is used for fail safe. A duration time in which the difference between the engine control target throttle opening and the failsafe target throttle opening is equal to or greater than a predetermined value during the failsafe mode by the failsafe monitoring unit 33. Based on the above, it is monitored whether or not the fail-safe operation is working correctly.

  If the fail-safe operation is working correctly during the fail-safe mode, the target throttle opening for fail-safe calculated by the CPU 2 is different from the target throttle opening for abnormal engine control calculated by the CPU 1. If the state where the difference between the target throttle opening and the failsafe target throttle opening is equal to or greater than a predetermined value (a state where the difference is large) continues to some extent, it can be determined that the failsafe operation is working correctly.

  In this case as well, the target throttle opening calculated by the CPU 1 during the fail safe mode is compared with the target throttle opening for fail safe calculated by the CPU 2, and the smaller one is selected as the final target throttle opening, and the final throttle opening is determined. The target throttle opening is adjusted.

  The fail-safe operation of the throttle control system of the second embodiment is executed as follows according to the program of FIG. 5 during engine operation. When this program is started, first, in step 201, an abnormality (for example, target) in which the generated torque of the engine 11 becomes excessive depending on whether or not the difference between the generated torque of the engine 11 and the required torque is larger than the abnormality determination value. It is determined whether or not the throttle opening is stuck. As a result, if the difference between the generated torque of the engine 11 and the required torque is equal to or less than the abnormality determination value, it is determined that no abnormality has occurred, and the routine proceeds to step 202 where the control mode of the throttle control system is set to normal (normal) ) Maintain the control mode.

  On the other hand, if it is determined in step 201 that the difference between the generated torque of the engine 11 and the required torque is greater than the abnormality determination value, it is determined that an abnormality has occurred, and the process proceeds to step 203. Switch the control mode of the throttle control system to fail-safe mode. During the fail safe mode, the engine control target throttle opening Ae calculated by the CPU 1 is compared with the fail safe target throttle opening Af calculated by the CPU 2, and the smaller one is selected as the final target throttle opening.

  Thereafter, the routine proceeds to step 204, where is the difference (Ae−Af) between the engine control target throttle opening Ae calculated by the CPU 1 and the fail safe target throttle opening Af calculated by the CPU 2 equal to or less than a predetermined value Eth? If the difference (Ae−Af) is equal to or smaller than the predetermined value Eth, the process proceeds to step 205, where the time counter Cnt (up / down counter) for fail-safe confirmation is counted up, and the difference (Ae−Af) Is larger than the predetermined value Eth, the process proceeds to step 206, and the fail safe confirmation time counter Cnt is counted down.

  Thereafter, the process proceeds to step 207, where it is determined whether or not the count value of the time counter Cnt for fail-safe confirmation [the duration in which the difference (Ae−Af) is equal to or less than the predetermined value Eth] exceeds the predetermined value Fth. If the count value of the time counter Cnt for confirming the fail safe exceeds the predetermined value Fth, the process proceeds to step 208, it is determined that the fail safe operation is abnormal, and the fail safe abnormality flag is set to “1”. In the next step 209, a warning lamp is turned on (or flashes), a warning is displayed on a warning display (not shown) on the instrument panel of the driver's seat, and the driver is warned. Fail safe (for example, cut off the energization of the throttle motor 15, fuel cut, etc.) is executed to reduce the torque generated by the engine 11.

  On the other hand, if it is determined in step 207 that the count value of the time counter Cnt for failsafe confirmation is equal to or less than the predetermined value Fth, the process proceeds to step 211 to determine that the failsafe operation is normal and failsafe. The abnormality flag is reset to “0”, and the processing after step 204 described above is repeated.

Next, an example of the fail-safe operation of the throttle control system according to the second embodiment will be described with reference to the time chart of FIG.
In the example of FIG. 6, when an abnormality occurs that causes the torque generated by the engine 11 to be excessive at time t1, the mode shifts to the fail safe mode. Thereafter, during a period in which the difference (Ae−Af) between the target throttle opening Ae for engine control calculated by the CPU 1 and the target throttle opening Af for fail-safe calculated by the CPU 2 is equal to or less than a predetermined value Eth. The time counter Cnt for safe confirmation counts up. Thereafter, the state where the difference (Ae−Af) is equal to or less than the predetermined value Eth continues, and at time t2 when the count value of the time counter Cnt for fail-safe confirmation exceeds the predetermined value Fth, it is determined that the fail-safe operation is abnormal. Then, the fail safe abnormality flag is set to “1”, the warning lamp is turned on (or flashes) to warn the driver, and additional fail safe is executed to reduce the generated torque of the engine 11. .

  If the count value of the time counter Cnt for fail-safe confirmation is equal to or less than the predetermined value Fth, it is determined that the fail-safe operation is normal and the fail-safe abnormality flag is reset to “0”.

  In the second embodiment described above, when the fail-safe monitoring unit 33 determines that the fail-safe operation is not working correctly during the fail-safe mode, an additional fail-safe procedure is executed. If it is confirmed that the fail-safe operation is not working correctly, an additional fail-safe procedure can be immediately executed to reliably suppress the output of the engine 11.

  In the first and second embodiments, the abnormality diagnosis is performed by comparing the torque generated by the engine 11 with the required torque. For example, the target throttle opening for engine control calculated by the CPU 1 and the CPU 2 Compare the calculated fail-safe target throttle opening and determine whether there is an abnormality based on whether or not the difference between the two is greater than the abnormality determination value, or diagnose the throttle sensor abnormality that detects the throttle opening And when the abnormality of the throttle sensor is detected, the mode may be shifted to the fail safe mode. In addition, an abnormality diagnosis of the throttle control system or the engine output control system may be performed, and when any abnormality is detected, the mode may be shifted to the fail safe mode.

It is a schematic block diagram of the whole engine control system in Example 1 of this invention. It is a block diagram explaining the fail safe function of ECU of Example 1. FIG. It is a flowchart explaining the flow of a process of the fail safe program of Example 1. FIG. 3 is a time chart illustrating an example of a fail-safe operation according to the first embodiment. It is a flowchart explaining the flow of a process of the fail safe program of Example 2. 6 is a time chart illustrating an example of a fail-safe operation according to the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine, 12 ... Intake pipe, 15 ... Throttle motor, 16 ... Throttle valve, 17 ... Throttle opening sensor, 21 ... Fuel injection valve, 23 ... Exhaust pipe, 28 ... Crank angle sensor, 30 ... ECU, 31 ... Torque Monitoring unit (abnormality diagnosing unit), 32... Fail-safe unit (fail-safe unit), 33... Fail-safe monitoring unit (fail-safe monitoring unit), 34... Warning display control unit (warning unit), 37. Safe means), 38 ... Target throttle opening selection section

Claims (10)

In a fail-safe device of a throttle control system that controls the throttle opening of an internal combustion engine to match a target throttle opening,
An abnormality diagnosis means for performing abnormality diagnosis of at least one of the throttle control system and an output control system of the internal combustion engine;
Fail-safe means for shifting to a fail-safe mode for adjusting the throttle opening of the internal combustion engine to a fail-safe target throttle opening when an abnormality is detected by the abnormality diagnosis means;
A fail-safe device for a throttle control system, comprising: fail-safe monitoring means for monitoring whether or not the abnormality diagnosis result of the abnormality diagnosis means is due to erroneous detection during the fail-safe mode.   The fail-safe monitoring means returns the control mode of the throttle control system from the fail-safe mode to a normal control mode when it is determined that the abnormality diagnosis result of the abnormality diagnosis means is due to erroneous detection. The fail-safe device of the throttle control system according to claim 1.   3. The fail-safe monitoring unit operates a warning unit to warn a driver when it is determined that the abnormality diagnosis result of the abnormality diagnosis unit is not a false detection but a real abnormality. A fail-safe device for the throttle control system described in 1.   The fail-safe monitoring unit performs an additional fail-safe measure for suppressing the output of the internal combustion engine when it is determined that the abnormality diagnosis result of the abnormality diagnosis unit is not abnormal detection but really abnormal. A fail-safe device for a throttle control system according to any one of claims 1 to 3. The first CPU for calculating the target throttle opening used in the normal control mode, and the fail-safe based on an input substantially the same as the input of the first CPU or an input simplified more than that. A second CPU for calculating a target throttle opening for use,
The fail safe monitoring means monitors whether or not the abnormality diagnosis result of the abnormality diagnosis means is due to an erroneous detection based on a difference between the target throttle opening and the fail safe target throttle opening during the fail safe mode. The fail-safe device for a throttle control system according to any one of claims 1 to 4, wherein:   The fail-safe means compares the target throttle opening calculated by the first CPU and the fail-safe target throttle opening calculated by the second CPU during the fail-safe mode, and finally selects the smaller one. 6. The throttle control system according to claim 5, wherein the throttle opening of the internal combustion engine is adjusted to the final target throttle opening for fail-safe by selecting it as a target throttle opening for fail-safe. Fail-safe device. In a fail-safe device of a throttle control system that controls the throttle opening of an internal combustion engine to match a target throttle opening,
An abnormality diagnosis means for performing abnormality diagnosis of at least one of the throttle control system and an output control system of the internal combustion engine;
Fail-safe means for shifting to a fail-safe mode for adjusting the throttle opening of the internal combustion engine to a fail-safe target throttle opening when an abnormality is detected by the abnormality diagnosis means;
A fail-safe device for a throttle control system, comprising: fail-safe monitoring means for monitoring whether or not a fail-safe operation by the fail-safe means is operating correctly during the fail-safe mode.   The fail-safe monitoring means performs an additional fail-safe measure for suppressing the output of the internal combustion engine when it is determined that the fail-safe operation by the fail-safe means is not working correctly during the fail-safe mode. The fail-safe device for a throttle control system according to claim 7, A first CPU for calculating the target throttle opening, and a first CPU for calculating the target throttle opening for fail-safe based on an input substantially the same as the input of the first CPU or an input simplified more than that. 2 CPUs,
The fail-safe monitoring unit is configured to perform a fail-safe operation by the fail-safe unit based on a duration of a state in which a difference between the target throttle opening and the fail-safe target throttle opening is a predetermined value or more during the fail-safe mode. 9. The fail-safe device for a throttle control system according to claim 7, wherein whether or not the engine is operating correctly is monitored.   The fail-safe means compares the target throttle opening calculated by the first CPU and the fail-safe target throttle opening calculated by the second CPU during the fail-safe mode, and finally selects the smaller one. 10. The throttle control system according to claim 9, wherein the throttle opening of the internal combustion engine is adjusted to the final target throttle opening for fail-safe by selecting as a target throttle opening for fail-safe. Fail-safe device.

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