JP3614021B2 - Vehicle self-diagnosis device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle self-diagnosis apparatus having a function of automatically stopping an engine when engine output is unnecessary.
[0002]
[Prior art and problems to be solved]
A hybrid vehicle that has both an engine and a motor (a rotating electric machine that serves both as an electric motor and a generator) as a power source of the vehicle and that is driven by one or both driving forces is known (for example, a railway (See page 39-52, June 1997 issue of “Automotive Engineering” VOL.46 No.7, published by Japan). In such a hybrid vehicle, the engine is stopped when the engine output is unnecessary, for example, when the vehicle is running or stopped only by the motor. In addition to hybrid vehicles, in so-called idle stop vehicles, the engine is stopped when the vehicle stops to save fuel consumption.
[0003]
By the way, there is known a self-diagnosis device that automatically detects engine abnormality so that the mechanic can easily grasp the cause of failure. When applied to a vehicle that is temporarily stopped, there arises a problem that accurate failure diagnosis cannot be performed. In other words, it is conceivable to provide a backup circuit for storing the abnormality detection history immediately before the engine is stopped and to take over the stored contents after the engine is started. In particular, it is not preferable because there is a possibility that the accuracy of diagnosis may be reduced or a misdiagnosis may be caused due to a change in atmospheric conditions during engine stop.
[0004]
The present invention has been made paying attention to such problems, and aims to solve the conventional problems by temporarily prohibiting the engine from being stopped when a probability of abnormality occurs. .
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, in an engine automatic stop vehicle that automatically stops the engine when output is unnecessary, an abnormality during operation of the engine is detected, and the integrated value of the number of abnormality detections is equal to or greater than a first set value. a failure determination device for performing the failure determination when it becomes the integrated value, the when a first set value 1 or more second set value or more is set smaller than the predetermined automatic stop of the engine And an engine stop prohibition device for prohibiting the period.
[0006]
The invention according to claim 2 satisfies the conditions for the engine stop prohibition device when a predetermined stop prohibition time has elapsed or when the integrated value of abnormality detection becomes equal to or greater than the first set value. When the engine stop prohibition was released.
[0007]
The invention of claim 3 applies the invention of claim 1 to an idle stop vehicle that automatically stops idle operation when the vehicle is stopped.
[0008]
The invention of claim 4 applies the invention of claim 1 to a hybrid vehicle provided with a rotating electrical machine as a power source in addition to the engine, and stopping the engine in an operating state where the driving force by the engine is unnecessary. To do.
[0009]
According to a fifth aspect of the present invention, the failure determination device according to the first aspect of the invention detects a monitor clamp state of an air-fuel ratio control device that feedback-controls a fuel supply amount based on a signal from an exhaust oxygen sensor or an air-fuel ratio sensor. Occasionally, abnormality detection integration was performed.
[0010]
According to a sixth aspect of the present invention, the engine stop prohibiting device according to the fifth aspect of the present invention is provided with an engine control device that increases the load or rotation speed of the engine during the engine stop prohibiting period.
[0011]
According to a seventh aspect of the present invention, the engine stop prohibiting device according to the fifth aspect includes a shift schedule correcting device that corrects the shift schedule of the automatic transmission in a direction in which the engine rotation is relatively increased during the engine stop prohibiting period. It was supposed to be.
[0012]
[Action / Effect]
In each of the first and subsequent inventions, the failure determination device determines that a failure has occurred when the integrated value of abnormality detection during engine operation reaches a first set value. After this failure determination, the engine is automatically stopped when a predetermined stop condition is satisfied and generally during the operation when it is determined that the engine output is unnecessary. However, when the integrated value of abnormality detection is equal to or greater than the second set value and less than the first set value, the engine stop control is temporarily prohibited by the engine stop prohibition device. As a result, the abnormality detection is continued under the condition that the abnormality is detected and the occurrence of the failure is predicted. Therefore, when an abnormality occurs, the failure is detected more reliably and the failure determination is performed with high accuracy. Is possible.
[0013]
The period for prohibiting the engine stop may be set, for example, until a predetermined time elapses as shown in the invention of claim 2 or until the integrated value of abnormality detection becomes equal to or higher than the first set value. it can. If the first set value is not reached even after a certain period of time has elapsed since the integrated value became equal to or greater than the second set value, it can be considered that no serious failure has occurred, so the engine is stopped. Remove the ban. Further, since the failure determination is made when the integrated value reaches the first set value, it is not necessary to prohibit the engine from being stopped any more, and may be caused by prohibiting the engine stop by allowing the engine to stop after that. Deterioration of fuel consumption and exhaust performance can be minimized.
[0014]
As the engine automatic stop vehicle, as shown in the invention of claim 3 or 4, an idle stop vehicle that automatically stops idle operation when the vehicle stops, or a rotating electric machine as a power source in addition to the engine, A hybrid vehicle or the like in which the engine is stopped when it is in an unnecessary operation state. According to the present invention, the self-diagnosis of the engine can be more appropriately performed in these vehicles.
[0015]
According to the fifth aspect of the present invention, the abnormality detection integration is performed when the monitor clamp state of the air-fuel ratio control device that feedback-controls the fuel supply amount based on the signal from the exhaust oxygen sensor or the air-fuel ratio sensor is detected. The monitor clamp detects a deviation from the target air-fuel ratio based on a signal from the air-fuel ratio sensor, and corrects the fuel supply amount to the engine in a direction approaching the target air-fuel ratio according to the deviation, for example, a fuel system This is a state in which the correction coefficient reaches a limit value that cannot be further corrected due to a system failure or the like, and has become a constant value. This monitor clamp is integrated every control cycle, and when a certain degree, that is, in this case, the first set value is exceeded, it is determined that there is a failure, and thereafter, for example, the control proceeds to air-fuel ratio control by open loop. An air-fuel ratio abnormality such as a monitor clamp is an abnormality that should be detected with the highest priority in an engine that requires precise fuel control. Accurate determination of this failure minimizes deterioration in fuel consumption and exhaust performance of the engine. It is important from the viewpoint of restraining. Therefore, according to the present invention, this failure determination can be performed with higher accuracy, and the purpose of the original failure diagnosis can be better achieved.
[0016]
According to a sixth aspect of the present invention, the engine stop prohibiting device according to the fifth aspect of the present invention is provided with an engine control device that increases the load or rotation speed of the engine during the engine stop prohibiting period. When the monitor clamp is generated, the more frequently the engine load or rotation speed is increased, the more frequently it is detected as abnormal, and the failure determination can be performed in a shorter time, so that the accuracy of the failure determination is improved. .
[0017]
According to a seventh aspect of the present invention, the engine stop prohibiting device according to the fifth aspect further includes a shift schedule correcting device for correcting the shift schedule of the automatic transmission in a direction in which the engine rotation is relatively increased during the engine stop prohibiting period. It is supposed to be. By correcting the shift schedule of the automatic transmission so that the engine speed is relatively increased, the engine speed increases under the same operating conditions as compared to before the shift schedule is changed. Thus, it is possible to improve the failure detection accuracy.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 to FIG. 2 show a configuration example of a hybrid vehicle to which the present invention can be applied. This is a parallel hybrid vehicle that travels using the power of either one or both of the engine and the motor according to the traveling conditions. The power train of the vehicle includes a motor 1, an engine 2, a clutch 3, a motor 4, a continuously variable transmission 5, a speed reducer 6, a differential device 7, and drive wheels 8. The output shaft of the motor 1, the output shaft of the engine 2, and the input shaft of the clutch 3 are connected to each other. The motor 1 and the engine 2 are connected to each other via a reduction gear (not shown) having a predetermined rotation ratio so that they can be driven mutually. Further, the output shaft of the clutch 3, the output shaft of the motor 4, and the input shaft of the continuously variable transmission 5 are connected to each other.
[0019]
When the clutch 3 is engaged, the engine 2 and the motor 4 serve as a vehicle propulsion source, and when the clutch 3 is released, only the motor 4 serves as a vehicle propulsion source. The driving force of the engine 2 or the motor 4 is transmitted to the drive wheels 8 via the continuously variable transmission 5, the speed reducer 6, and the differential device 7. The continuously variable transmission 5 is supplied with pressure oil from the hydraulic device 9, and the belt is clamped and lubricated.
[0020]
The motor 1 is mainly used for engine start and power generation, and the motor 4 is mainly used for power running of the vehicle and regenerative operation during deceleration. The motor 10 is for driving an oil pump of the hydraulic device 9. However, when the clutch 3 is engaged, the motor 1 can also be used for powering and braking the vehicle, and the motor 4 can also be used for engine starting and power generation. The clutch 3 is an electromagnetic powder clutch, and its transmission torque can be adjusted by current control.
[0021]
The motors 1, 4 and 10 are driven by inverters 11, 12 and 13, respectively. In the case where a DC electric motor is used for the motors 1, 4 and 10, a DC / DC converter is used instead of the inverter. The inverters 11 to 13 are connected to the high-power battery 15 through a common DC link 14, and the direct-current power of the high-power battery 15 is converted into alternating current power and supplied to the motors 1, 4, and 10. The high-power battery 15 is charged by converting the AC generated power into DC power. Since the inverters 11 to 13 are connected to each other via the DC link 14, the electric power generated by the motor during the regenerative operation can be directly supplied to the motor during the power running operation without going through the high-power battery 15.
[0022]
Reference numeral 16 denotes a controller having functions of various control circuits such as a failure determination device and an engine stop prohibition device according to the present invention, which includes a microcomputer and its peripheral parts, various actuators, etc. The number of revolutions and output torque of 10, the gear ratio of the continuously variable transmission 5, the fuel injection amount / injection timing of the engine 2, the ignition timing, etc. are controlled.
[0023]
As shown in FIG. 2, the controller 16 includes a key switch 20, a select lever switch 21, an accelerator pedal sensor 22, a brake switch 23, a vehicle speed sensor 24, a battery temperature sensor 25, a battery SOC detection device 26, and an engine speed sensor 27. A throttle opening sensor 28 is connected. The select lever switch 21 is one of P, N, R, and D switches according to the set position of a select lever (not shown) that switches to any of the ranges of parking P, neutral N, reverse R, and drive D. Turns on.
[0024]
The accelerator pedal sensor 22 detects the amount of depression of the accelerator pedal, and the brake switch 23 detects the depression state of the brake pedal. The vehicle speed sensor 24 detects the traveling speed of the vehicle, and the battery temperature sensor 25 detects the temperature of the high-power battery 15. The battery SOC detection device 26 detects SOC (State Of Charge) which is a representative value of the actual capacity of the high-power battery 15. The engine speed sensor 27 detects the speed of the engine 2, and the throttle opening sensor 28 detects the throttle valve opening of the engine 2.
[0025]
The controller 16 is further connected to a fuel injection device 30, an ignition device 31, a variable valve operating device 32, and the like of the engine 2. The controller 16 controls the fuel injection device 30 to supply and stop the fuel to the engine 2 and adjust the fuel injection amount / injection timing, and drives the ignition device 31 to control the ignition timing of the engine 2. Further, the controller 16 controls the variable valve device 32 to adjust the operating state of the intake / exhaust valve of the engine 2. The controller 16 is supplied with power from a low-voltage auxiliary battery 33.
[0026]
The above is an example of a basic configuration of a hybrid vehicle to which the present invention can be applied. In the present invention, the self-diagnosis accuracy of the engine is improved in a vehicle in which the engine is automatically stopped during operation like the hybrid vehicle. The purpose is to let you. In the following, an embodiment of the control contents of the controller 16 for this purpose will be described with reference to FIGS.
[0027]
FIG. 3 is a flowchart showing an outline of the engine stop prohibition control according to the present invention. This control is periodically executed as part of the vehicle / engine control by the controller 16. In this control, initially, an engine stop prohibition flag #EGOPR, a counter integrated value N of the number of monitor clamps, and a timer value T of an elapsed time from the start of engine stop prohibition are each initialized to 0 (step 301). The #EGOPR is referred to in engine stop control (not shown). When #EGOPR is 0, the engine stop is permitted, and when #EGOPR is 1, the engine stop is prohibited.
[0028]
Next, the success or failure of the diagnosis condition and area condition is determined (steps 302 and 303). The diagnosis condition is whether or not the engine is in a state where it can be diagnosed. For example, when the engine is forcibly stopped by a key switch operation of the driver during the diagnosis, the subsequent diagnosis is impossible. The above-mentioned #EGOPR, N, and T are initialized to prepare for the next diagnosis (step 304). Also, since this control is based on the premise that a monitor clamp indicating an abnormal state of the air-fuel ratio feedback control is detected, it is determined whether or not the operating condition is that the air-fuel ratio feedback control is performed as the region condition. determined based on the operating state signals from the sensor 28 or the like, for example, when the deceleration fuel cut when a throat engine detects that the operating region is not performed the air-fuel ratio feedback control is not performed diagnosis.
[0029]
When the diagnosis condition and the area condition are satisfied, the monitor clamp is next detected (step 305). The monitor clamp is a process of clamping the air-fuel ratio correction coefficient to a constant value when the air-fuel ratio correction reaches the rich side or lean side limit as described above. In general, in the air-fuel ratio feedback control of the engine, as shown by the following equation, the fuel supply amount Te is set to various basic fuel amounts Tp determined from a map search based on the engine speed and the intake air amount by the cooling water temperature or the like. It is determined by multiplying the correction coefficient Co and the air-fuel ratio correction coefficient ALPHA.
[0030]
Te = Tp / Co / ALPHA
The air-fuel ratio correction coefficient ALPHA gives a correction amount for Te so that the actual air-fuel ratio approaches the target air-fuel ratio based on the deviation between the actual air-fuel ratio detected by the exhaust oxygen sensor or the air-fuel ratio sensor and the target air-fuel ratio. . The correction range is set to, for example, 1.25 to 0.75. If the air-fuel ratio sensor fails or the like, the air-fuel ratio is biased to the rich side to become ALPHA ≦ 0.75, or biased to the lean side to ALPHA ≧ 1. When it becomes .25, no further correction is possible, so ALPHA = 1 and the feedback control is temporarily stopped.
[0031]
In this control, the integrated value N is added every time the monitor clamp is detected (step 306), the addition result is compared with the set value CMC1, and the monitor clamp detection process is repeated until N ≧ CMC1 (step 308). ). The set value CMC1 corresponds to the second set value of the present invention, and is set to an appropriate value of 1 or more as a reference value for the number of occurrences of monitor clamps where a failure is predicted to occur. Here, if N ≧ CMC1, the engine stop prohibition flag #EGOPR is set to 1 to prohibit the engine stop, and then the integrated value N is compared with the set value CMC2 (where CMC2> CMC1) (step) 309, 310). The set value CMC2 corresponds to the first set value of the present invention, and is a reference value for making a final failure determination with respect to the number of monitor clamp occurrences. Since it is not necessary to compare the integrated value N and the set value CMC1 after # EGOPR = 1, #EGOPR is referred to in the previous stage of comparison by CMC1 (step 307), and when # EGOPR = 1 Bypasses the comparison with CMC1 and moves directly to the comparison process with CMC2.
[0032]
Since the set value CMC2 is an original failure determination reference value with respect to the number of occurrences of the monitor clamp, when N ≧ CMC2, an NG determination process, for example, a process of lighting the monitor lamp of the self-diagnosis device is performed, and then the flag #EGOPR is set. The prohibition of the engine stop is canceled by resetting, and the integrated value N and the timer value T are initialized to 0, and the failure diagnosis is finished (step 314). On the other hand, the timer value T is updated (added) while N <CMC2, and the above processing is repeated until T reaches the reference value TMCON (steps 311 and 312).
[0033]
If the timer value T reaches the reference value TMCON before the integrated value N of the number of monitor clamps reaches the set value CMC2, this is because the frequency of monitor clamps generated after the number of monitor clamps exceeds CMC1 is low. Therefore, it can be determined that there is no serious failure at present. Therefore, the flag #EGOPR is reset to cancel the prohibition of engine stop, and the integrated value N and timer value T are initialized to 0, and then the diagnosis process is performed. Returning to the initial stage (step 302), a new diagnosis process is started (step 313). If the integrated value N becomes equal to or greater than the set value CMC2 before the timer value T reaches the reference value TMCON, an NG determination process (step 314) is performed as described above.
[0034]
FIG. 4 or FIG. 5 shows a control operation example based on the engine stop prohibition control. Each of these shows a rich abnormality case where the air-fuel ratio correction coefficient ALPHA reaches a limit value smaller than 1 (shown as “100%” in the figure). Further, since CMC = 1 is set, 1 is set in the flag #EGOPR to prohibit the engine (ENG) from being stopped when the first monitor clamp is generated.
[0035]
FIG. 4 shows the case where the timer value T reaches the reference value TMCON before the monitor clamp integrated value N reaches the set value CMC2 after the engine stop is prohibited by the first monitor clamp. In this case, as described above. The prohibition of the engine stop is canceled (# EGOPR = 0) without performing the diagnosis NG process. On the other hand, FIG. 5 shows a case where the monitor clamp integrated value N reaches the set value CMC2 before the timer value T reaches the reference value TMCON after the engine stop is prohibited by the first monitor clamp. In this case, NG is determined when N = CMC2 and the prohibition of engine stop is cancelled.
[Brief description of the drawings]
[Fig. 1]
FIG. 2 is a schematic configuration diagram showing a configuration example of a hybrid vehicle to which the present invention is applicable.
FIG. 3 is a flowchart showing an embodiment of control according to the present invention.
[Figure 4]
FIG. 5 is an explanatory diagram of a control operation example by the control of the embodiment.
[Explanation of symbols]
1 Motor 2 Engine 3 Clutch 4 Motor (Rotating Electric Machine)
5 continuously variable transmission 9 hydraulic device 10 hydraulic pressure generating motor 15 battery 16 controller 19 DC / DC converter 20 key switch 21 select lever switch 22 accelerator pedal sensor 23 brake switch 24 vehicle speed sensor 25 battery temperature sensor 26 battery SOC detection device 27 engine Rotation speed sensor 28 Throttle opening sensor 33 Auxiliary battery

Claims (7)

In an engine automatic stop vehicle that automatically stops the engine when output is unnecessary,
A failure determination device that detects an abnormality during operation of the engine and performs failure determination when an integrated value of the number of abnormality detections is equal to or greater than a first set value;
An engine stop prohibiting device that prohibits automatic engine stop for a predetermined period when the integrated value is equal to or greater than one or more second set value set smaller than the first set value; A vehicle self-diagnosis device characterized by the above. The engine stop prohibition device cancels the engine stop prohibition when a predetermined stop prohibition time has elapsed or when either of the conditions when the integrated value of abnormality detection exceeds the first set value is satisfied. The vehicle self-diagnosis device according to claim 1, which is configured as described above. The vehicle self-diagnosis device according to claim 1, wherein the engine automatic stop vehicle is an idle stop vehicle that automatically stops idle operation when the vehicle is stopped. The self-stopping vehicle is a hybrid vehicle that includes a rotating electric machine as a power source in addition to the engine, and is configured to stop the engine in an operation state that does not require driving force from the engine. Diagnostic device. 2. The failure determination device according to claim 1, wherein the failure determination device integrates abnormality detection when detecting a monitor clamp state of an air-fuel ratio control device that feedback-controls a fuel supply amount based on a signal from an exhaust oxygen sensor or an air-fuel ratio sensor. Vehicle self-diagnosis device. 6. The vehicle self-diagnosis device according to claim 5, wherein the engine stop prohibiting device includes an engine control device that increases an engine load or a rotational speed during the engine stop prohibiting period. The vehicle self-diagnosis device according to claim 5, wherein the engine stop prohibition device includes a shift schedule correction device that corrects the shift schedule of the automatic transmission in a direction in which the engine rotation is relatively increased during the engine stop prohibition period.

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