JP2000054868A - Fail-safe control device for electronically controlled throttle type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a fail-safe function when an accelerator opening sensor and a throttle opening sensor are troubled in a full electronically controlled throttle system. SOLUTION: In the case that the diagnosed results of the failure of two accelerator opening sensors and two throttle openign sensors are read (S1) and one out of two sensors is troubled (S2), and that an idle switch is switched on (S3) and the opening of the throttle valve is near a default opening to compensate low speed fail-safe operation (S4), throttle valve opening control using the rest of one sensor is allowed (S5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine provided with an electronically controlled throttle system for opening and closing a throttle valve interposed in an intake system by an actuator so as to attain a target opening degree, and in particular, abnormality of a sensor constituting the system. The present invention relates to a fail-safe control technique at the time.

[0002]

2. Description of the Related Art Conventionally, based on an accelerator opening (accelerator pedal depression amount) or an engine speed, etc.
There is an electronically controlled throttle system that electronically controls the opening of a throttle valve so as to obtain a target air amount (Japanese Patent Laid-Open No. 7-1).
No. 80570). Among such electronically controlled throttle systems, particularly those that do not have a fail-safe mechanism that mechanically interlocks the throttle valve with a wire or the like by operating the accelerator when the drive system fails (full electronically controlled throttle system), for example, The following method is adopted.

In other words, two accelerator opening sensors and two throttle opening sensors are provided.
The smaller one of the detected values is selected (to prevent an excessive output), and the throttle valve opening is determined by using the detected value of the main throttle opening. In some cases, the larger of the two detected values is used. Is selected (because selecting the larger one in the feedback control is corrected in the smaller direction and preventing an excessive output).

If one of the two sensors fails, there is no compensation for the remaining one of the sensors, so that the output of the actuator is stopped and two springs (a return spring and a default spring) are stopped. (Springs) to connect the throttle valves to maintain a predetermined default opening that balances the springs, so-called limp home state (minimally compensated low-speed fail-safe operation state that enables running with minimum output) and I am trying to do it.

[0005]

In view of the above-mentioned situation, even if only one throttle opening sensor fails in the above-mentioned fully electric throttle system, for example, the energization of the actuator for driving the throttle valve is performed. Is stopped, and a predetermined default opening is maintained by the balance between the return spring and the default spring.

However, in the limp home control in which the default opening is maintained, the maximum vehicle speed is limited to about 40 km. Moreover, among the components of the electronically controlled throttle system, the accelerator opening sensor and the throttle opening sensor have a high failure rate, and therefore, when a single failure occurs in these sensors, it has been required to guarantee a certain level of running performance. The present invention has been made in view of such a conventional problem. In the event of a single failure of the sensor, the limp home control at the time of a single failure that operates at a desired speed using the detection value of the normal sensor. It is another object of the present invention to provide a fail-safe control apparatus for an electronically-controlled throttle-type internal combustion engine, which is capable of smoothly executing the limp home control.

[0007]

According to the first aspect of the present invention, as shown in FIG. 1, a throttle valve interposed in an intake system is set to a target opening degree in accordance with engine operating conditions including an accelerator opening degree. And an electronically controlled throttle system that opens and closes with an actuator so as to provide an accelerator opening sensor for detecting the accelerator opening and a throttle opening sensor for detecting the opening of the throttle valve. In a throttle-type internal combustion engine, when one of the two sensors fails, the fail-safe means at the time of a single failure that controls the throttle valve opening using the detection value of the remaining one sensor; A single failure permitting operation of the failsafe means in the event of a single failure after experiencing a low speed failsafe operation with a minimum compensation after one of the two failures of each sensor is determined. Characterized by being configured to include a fail-safe permission means.

With this configuration, when one of the two sensors, the accelerator opening sensor and the throttle opening sensor, fails, the single-failure fail-safe means uses the fail-safe means based on the detected values of the remaining sensors. The throttle valve can be controlled to a desired target opening in accordance with the accelerator opening, and can be operated at a desired speed. However, if the fail-safe at the time of the single failure is performed simultaneously with the determination of the single failure of the sensor, for example, when a single failure occurs while the accelerator is open during traveling, the throttle opening is increased, The output suddenly increases, causing anxiety.

Therefore, the fail-safe permitting means at the time of a single failure allows the driver to experience and confirm the low-speed fail-safe operation with the minimum compensation, and then, from this state, the operation of the fail-safe means at the time of the single failure is permitted to perform the accelerator operation. The operation at the desired desired speed is performed. Also,
The invention according to claim 2 is characterized in that the fail-safe operation with the minimum compensation is an operation in a state where the throttle valve is near a predetermined opening degree after the accelerator opening operation to compensate for the fail-safe operation with the minimum compensation. And

With this configuration, after the occurrence of a single failure, when the accelerator is released and the intention of deceleration operation is indicated, low-speed stable operation in a state where the throttle valve is in the vicinity of the predetermined opening for compensating the fail-safe operation of minimum compensation. After experiencing and confirming the running, the state smoothly shifts to the single failure limp home control from that state, and the vehicle can be driven at a desired speed according to the accelerator opening.

Further, the invention according to claim 3 is characterized in that the fail-safe operation of the minimum compensation is an operation in a state where, after the brake operation, the throttle valve is in the vicinity of a predetermined opening for compensating the fail-safe operation of the minimum compensation. There is a feature.
According to this configuration, after the occurrence of a single failure, when the brake is operated and the intention of the deceleration operation is indicated, the vehicle experiences low-speed traveling in a state where the throttle valve is in the vicinity of the predetermined opening to compensate for the fail-safe operation of the minimum compensation. After confirming the state, the state smoothly shifts to the limp home control at the time of a single failure, and the vehicle can be driven at a desired speed according to the accelerator opening.

According to a fourth aspect of the present invention, when the driving of the actuator is stopped, the throttle valve is maintained at a predetermined opening for compensating the fail-safe operation of the minimum compensation by the balance of the urging forces of the two springs. It is characterized by making it. According to such a configuration, usually, the above-mentioned 2
The throttle valve can be controlled to a desired opening while expanding and contracting the two springs, and when the driving of the actuator is stopped, the throttle valve can be held at the predetermined opening by the static balance of the urging forces of the two springs. Then, before the single failure of the sensor is determined, or in the case of a double failure in which both sensors fail, the actuator is stopped and the opening of the throttle valve is maintained at a predetermined opening to reduce the minimum compensation. Cause low-speed fail-safe operation.

According to a fifth aspect of the present invention, one of the two failures of each of the sensors is determined to be a failure when the failure of the one sensor continues for a predetermined time. Features. According to such a configuration, a transient sensor failure can be eliminated, and a continuous failure can be determined.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a system configuration according to an embodiment of the present invention. Two accelerator opening sensors (APS) 1
A and 1B detect the depression amount (accelerator opening) of the accelerator pedal depressed by the driver.

The crank angle sensor 2 generates a position signal for each unit crank angle and a reference signal for each cylinder stroke phase difference, and measures the number of the position signals generated per unit time, or generates the reference signal. By measuring the period, the engine speed can be detected. The air flow meter 3 detects the amount of intake air to the engine 4 (the amount of intake air per unit time = the amount of intake air).

The water temperature sensor 5 detects the temperature of the cooling water of the engine. The engine 4 is provided with a fuel injection valve 6 that is driven by a fuel injection signal and supplies fuel directly into the combustion chamber, and an ignition plug 7 that is mounted in the combustion chamber and ignites. By the direct injection method into the combustion chamber, leaning by stratified combustion becomes possible, and the air-fuel ratio can be variably controlled over a wide range.

A throttle valve 9 is interposed in the intake passage 8 of the engine 4. The throttle valve 9 can be electronically controlled by driving the throttle valve 9 via a lever 10 connected to the valve shaft. Actuator 11 is provided. The lever 10 has a return spring 1 on both sides.
2 and the default spring 13 are connected, and in a state where the energization of the actuator 11 is turned off, the throttle valve 9 is set to a predetermined default opening at a position where the urging forces of the return spring 12 and the default spring 13 are balanced. Is to be retained. Also,
The throttle valve 9 is provided with two throttle opening sensors 14A and 14B for detecting the opening of the throttle valve 9.

The exhaust passage 15 has an air-fuel ratio sensor 16 as air-fuel ratio detecting means for detecting the air-fuel ratio of the combustion mixture by detecting the concentration of a specific component such as oxygen in the exhaust gas.
Is provided. Furthermore, to detect the driver's deceleration operation,
Idle switches 17A and 17B for detecting an idle state (accelerated opening state) are provided in association with the accelerator opening sensors 1A and 1B, and a brake switch 18 for detecting a brake operation is provided.

The detection signals from the various sensors are input to a control unit 19, and the control unit 19 drives the actuator 11 in accordance with the operation state detected based on the signals from the sensors. Controlling the opening degree of the throttle valve 9, controlling the fuel injection amount (fuel supply amount) by driving the fuel injection valve 6, setting the ignition timing, and igniting the ignition plug 7 at the ignition timing. Do.

Next, the accelerator opening sensor 1A (AP
S1), 1B (APS2) and throttle opening sensor 1
The failure diagnosis of 7A (TPS1) and 17B (TPS2) and fail-safe control at the time of failure will be described with reference to FIG. Referring to the figure, the accelerator opening sensor system diagnosis will be described. In the accelerator opening sensor 1A (1B) output diagnosis, open / short faults are detected, and the flag APS1CA (APS2CA) is set to 1 when a fault occurs. The flag APS1N is set when the failure state continues for a predetermined delay time in order to eliminate a temporary failure.
G (APS2NG) is set to 1 to determine the failure of the accelerator opening sensor 1A (1B). When each flag (including the flag described later) is set to 1,
The output to each circuit described later is at a high level, and when reset to 0, the output to each circuit is set to a low level.

Diagnosis of whether the difference between the accelerator opening sensors 1A and 1B is large and mismatch (APS mismatch diagnosis)
The flag APSXCA is set to 1 when there is an inconsistency. In this case, too, in order to remove excessive inconsistency, the flag APSXNG is set to 1 when the inconsistency continues for a predetermined delay time. Is determined to be inconsistent. When a single failure occurs in the sensor, a large difference occurs in the output value between the failed side and the normal side. Therefore, the mismatch state is determined first, and then the single failure is determined.

On the other hand, the throttle opening sensor system diagnosis is the same as the accelerator opening sensor system diagnosis. That is, the open / short failure of the throttle opening sensor 14A (14B) is detected, and when a failure occurs, the flag TPS1CA (TPS2CA) is set to 1.
When the failure state continues for a predetermined delay time, the flag TPS1NG (TPS2NG) is set to 1 to determine the failure of the throttle opening sensor 14A (14B),
When the difference between the throttle opening sensors 14A and 14B is largely mismatched, the flag TPSXCA is set to 1;
When the mismatch state continues for a predetermined delay time, the flag TPSXNG is set to 1 and it is determined that there is a mismatch. The same applies to the case where the single failure is determined after the mismatch state is determined.

For the accelerator opening sensor system, three flags APS1NG, APS2NG, APS
When both XNGs are 0 (first from the top of the table in the same system), that is, when all the diagnostic results of the accelerator opening sensor system are normal, the smaller value of the two detected values of the accelerator opening sensors 1A and 1B Is selected (LOWER). For the throttle opening sensor system, three flags TP
When S1NG, TPS2NG, and TPSXNG are all 0 (first from the top of the table in the same system), the detection value TPO1 of one throttle opening sensor 14A is selected.

If all the systems have been diagnosed as normal, there is no need for the limp home. Therefore, the limp home permission flag is set to 0 when the sensor has a single failure, and the power-traffer off flag and the relay off flag are set to 0. When both systems are normal, both the actuator driving power transistor and the driving relay are turned on, the actuator 11 is driven, and the target throttle opening set based on the smaller accelerator opening APO is set. The degree of opening of the throttle valve 9 is controlled so as to obtain In this case, since the output of the first OR circuit 31 is maintained at a low level, the warning lamp does not light.

When only the mismatch flag APSXCA (TPSXCA) is set to 1 for at least one of the systems (second in the table of each system), any of the accelerator opening sensors 1A and 1B (throttle It is also determined that the detection values of the opening sensors 14A and 14B) are not reliable, and the power-traffer off flag and the relay off flag are set to 1. As a result, the first OR circuit 31 goes high and the warning lamp is lit, and the second OR circuit 32 and the third
The output of the OR circuit 33 becomes high level, and the power transistor for driving the actuator and the relay for driving both become O.
The FF is turned on, the power supply to the actuator 11 is stopped, and the throttle valve 9 is held at a default opening degree where the urging forces of the return spring 12 and the default spring 13 are balanced, and the necessary minimum speed (for example, 40 km / h) Run with. As described below, six flags APS1NG, APS2NG, APSXNG,
When at least one of TPS1NG, TPS2NG, and TPSXNG is 1, the first OR circuit 31 is at a high level and the warning lamp is turned on, so that the description is omitted below.

Next, a flag APS1N is set for each system.
G, APS2NG (TPS1NG, TPS2NG) is one, that is, the accelerator opening sensors 1A, 1B
If only one of the throttle opening sensors 14A and 14B is diagnosed as a failure (single failure) (third to sixth in the table of each system), and after the single failure is determined, a predetermined condition described later will be applied. After the establishment, the limp home permission flag at the time of single failure of the sensor is set from 0 to 1, and the power-traffer off flag and the relay off flag are also changed from 1 to 0 in synchronization with the change of the flag from 0 to 1. Regarding the accelerator opening APO (throttle opening TPO), the detected value on the side not diagnosed as a failure, APS1 or APS2
(TPO1 or TPO2) is selected.

Here, a routine for setting the limp home permission flag at the time of a single failure to 1 after the single failure of the sensor is determined will be described with reference to the flowchart of FIG. In addition,
The same operation is performed for both the accelerator opening sensor and the throttle opening sensor. In step 1, the diagnosis result of the accelerator opening sensor (throttle opening sensor) is read.

In step 2, it is determined from the value of each of the flags whether a single failure has occurred in one of the accelerator opening sensors (throttle opening sensor). If it is determined that the single failure has occurred, the process proceeds to step 3, where it is determined whether or not the idle switch has been turned ON by the accelerator opening operation. If it is determined that the idle switch is ON, the routine proceeds to step 4, where it is determined whether or not the opening of the throttle valve is close to the default opening (default opening ± α).

If it is determined that the value is close to the default opening, the limp home permission flag at the time of a single failure of the accelerator opening sensor (throttle opening sensor) is set to 1. FIG. 5 shows a routine for setting a limp home permission flag upon single failure according to another embodiment.

4 is different from FIG. 4 in that it is determined in step 13 whether or not the brake switch is ON instead of the idle switch. However, the same determination step is performed in that the intention of the driver to decelerate more than a predetermined speed is detected. It is. In this manner, when the limp home permission flag at least one of the accelerator opening sensor system and the throttle opening sensor system is set to 1 when the single failure occurs, the output of the fourth OR circuit 34 in FIG. At the level, the limp home control is executed at the time of a single failure. Specifically, since the power traverse off flag and the relay off flag are simultaneously switched to 0, the actuator 11 is driven and the throttle valve is set to the target throttle opening set based on the selected accelerator opening APO. 9 can be controlled. In other words, the vehicle can be driven at a desired vehicle speed without forcibly keeping the throttle opening at the default opening and without being limited to a low speed of about 40 km / h.

As described above, after the occurrence of the single failure and before the single failure is determined, first, the values of the two sensors become inconsistent and the inconsistency flag APSXCA (TPSXC
A) is set to 1, and at this time, the relay-off flag also becomes 1, and the drive of the actuator is stopped, and the throttle valve attempts to move to the Cartesian opening where the return spring and the default spring are balanced. However, there is a delay in reaching the default opening due to intake resistance or mechanical delay, etc.Before reaching, when shifting to limp home control in the event of a single failure, the throttle valve is still open. The home control is started. In particular, when the accelerator opening is larger, the opening of the throttle valve is further increased to cause unintended acceleration by the driver.

In this regard, as a configuration according to the present invention, a deceleration operation at a predetermined level or more such as an accelerator release operation or a brake operation is performed, and the throttle valve actually returns to near the default opening to perform a low-speed fail-safe operation with minimum compensation. After experience and confirmation, it is possible to shift to limp home control at the time of a single failure and smoothly shift to running at a desired speed corresponding to the accelerator opening according to the driver's will.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration and functions of the present invention.

FIG. 2 is a diagram showing a system configuration according to an embodiment of the present invention.

FIG. 3 is a circuit block diagram showing throttle control based on diagnosis of an accelerator opening sensor and a throttle opening sensor according to the embodiment.

FIG. 4 is a flowchart showing an example of a routine for setting a limp home permission flag when a single sensor failure occurs.

FIG. 5 is a flowchart showing another example of a routine for setting a limp home permission flag when a single sensor failure occurs.

[Explanation of symbols]

 1A, 1B Accelerator opening sensor 4 Engine 9 Throttle valve 11 Actuator 12 Return spring 13 Default spring 14A, 14B Throttle opening sensor 17A, 17B Idle switch 18 Brake switch 19 Control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 45/00 364 F02D 45/00 364J (72) Inventor Masahiro Iriyama 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Automobile Co., Ltd. F-term (reference) 3G065 CA39 CA40 DA04 EA03 FA04 GA10 GA29 GA43 GA46 KA15 KA16 3G084 AA04 BA05 BA33 CA03 DA26 DA27 DA30 EB22 FA06 FA10 FA33 3G301 HA01 HA16 JB01 JB08 JB09 JB10 KA07 LA03 NE22 PA14B01 PE03B05

Claims (5)

[Claims] An electronically controlled throttle system that opens and closes a throttle valve interposed in an intake system with an actuator according to engine operating conditions including an accelerator opening so as to reach a target opening. In an electronically controlled throttle type internal combustion engine having two accelerator opening sensors for detecting and two throttle opening sensors for detecting the opening of the throttle valve, when one of the two sensors fails. A single-failure-fail-safe means for controlling the throttle valve opening using the detection value of the remaining one sensor; and a low-speed minimum compensation after the failure of one of the two sensors is determined. And a fail-safe permitting means for permitting operation of the fail-safe means for single failure after experiencing the fail-safe operation. Fail-safe control apparatus of a throttle type internal combustion engine. 2. The low-speed fail-safe operation with the minimum compensation is an operation in a state where the throttle valve is near a predetermined opening for compensating the fail-safe operation after the accelerator is opened. 4. The fail-safe control apparatus for an electrically controlled throttle internal combustion engine according to claim 1. 3. The fail-safe operation of the lowest compensation is an operation in a state in which, after a brake operation, a throttle valve is near a predetermined opening for compensating the fail-safe operation. Fail-safe control system for electronically controlled throttle-type internal combustion engine. 4. The throttle valve according to claim 1, wherein when the driving of said actuator is stopped, the throttle valve is held at a predetermined opening for compensating said minimum-compensation low-speed fail-safe operation by a balance of biasing forces of two springs. Item 1
The fail-safe control apparatus for an electronically controlled throttle-type internal combustion engine according to claim 1. 5. The method of claim 1, wherein one of two of said sensors is:
5. The fail-safe control of an electronically controlled throttle-type internal combustion engine according to claim 1, wherein the failure is determined when the failure of the one sensor continues for a predetermined time. apparatus.