KR20140020556A - Fail-safe control method on steering angle detection error of hybrid electric vehicle - Google Patents

Abstract

The present invention relates to a fail-safe control method for a steering angle detection error of a hybrid vehicle. The purpose is to provide a fail-safe control method for a steering angle detection error of a hybrid vehicle capable of performing an idle stop mode in a normal idle entering condition if it is not a U-turn or a corner driving when a normal steering is not inputted from a steering angle sensor due to a CAN communication error or the malfunction of the sensor. For this purpose, the invention provides the fail-safe control method including a step of determining the malfunction of the steering angle sensor when the steering angle detected from the sensor exceeds a reference value while indicating a small difference in a preset range or right and left wheel speeds of the hybrid vehicle are the same, a step of comparing the right and left wheel speeds to each other when the idle stop entering condition is satisfied, and a step of permitting idle stop when the right and left wheel speeds are the same or a difference between them is small. [Reference numerals] (AA) Steering angle <= 1rad; (BB) Speeds of both wheels are the same; (CC) Steering angle; (DD) Generates a difference between the speeds of the wheels

Description

Fail-safe control method on steering angle detection error of hybrid electric vehicle

The present invention relates to a fail-safe control method of a hybrid vehicle, and more particularly, even if a normal steering angle signal is not inputted from a steering angle sensor due to a failure of a steering angle sensor or a CAN communication error, etc. The present invention relates to a fail safe control method when a steering angle detection error of a hybrid vehicle enables an idle stop mode to be performed under an entry condition.

A hybrid vehicle means an efficient combination of two or more different power sources to drive a vehicle. However, most of them use an engine and a battery that generate rotational power by burning fuel (fossil fuels such as gasoline and diesel) to obtain rotational power. Means a vehicle driven by a motor, it is commonly referred to as a hybrid electric vehicle (HEV).

The hybrid vehicle is a future vehicle that can improve fuel efficiency and reduce exhaust gas by adopting not only an engine but also an electric motor as an auxiliary power source, and in response to the demand of the times to improve fuel efficiency and develop environmentally friendly products, more active researchers It's going on.

The hybrid vehicle is an electric vehicle (EV) mode, which is a pure electric vehicle mode using only the power of an electric motor (drive motor), and an HEV (Hybrid Electric Vehicle, HEV) using the rotational power of the driving motor as an auxiliary power while using the engine rotational power as the main power. ) Mode, when braking the vehicle or driving due to inertia, driving in regenerative braking (RB) mode where the braking and inertia energy is recovered through the generation of the driving motor and charged to the battery.

As such, the hybrid vehicle utilizes the engine's mechanical energy and the battery's electrical energy together to use the optimum operating area of the engine and the driving motor, and also recovers energy to the driving motor during braking, thereby improving fuel efficiency of the vehicle and making efficient use of energy. .

Meanwhile, fuel efficiency and eco-friendliness have emerged as key factors for vehicle development due to high oil prices and CO2 emission regulations. To achieve this goal, each automobile manufacturer is devoted to developing technologies to reduce fuel consumption.

In particular, the economic effect of improving fuel economy in a commercial vehicle such as a bus with a high oil use ratio can be very large, and the application of a hybrid system in a commercial vehicle as well as a passenger car is increasing in importance and weight.

The purpose of the hybrid vehicle is to implement an eco-friendly vehicle by improving fuel economy and reducing exhaust gas as described above, and to achieve this purpose, a function of maximally controlling engine loss consumed in unnecessary parts is required.

As a method for reducing engine loss, methods such as driving control at an optimum operating point of the engine through motor assist and idle stop control are known.

Idle stop control is the most distinctive control method from general engine vehicles, and refers to a control method that prevents unnecessary idling by stopping the engine during vehicle stop, and can reduce fuel consumption since the engine idle state is stopped when the vehicle is stopped. Emissions can also be reduced, greatly contributing to the achievement of fuel efficiency and emissions reduction.

Commercial vehicles, especially recently developed hybrid buses, are applying a soft parallel hybrid system and improving fuel economy by implementing functions such as idle stop, motor driving, and regenerative braking, which are typical functions of the hybrid system.

1 is a schematic diagram showing the configuration of a hybrid powertrain applied to a hybrid bus. As shown in FIG. 1, the hybrid system has a layout in which the engine 11, the driving motor 13, and the transmission 14 are arranged in a row. .

In addition, the engine 11 and the drive motor 13 are connected to the power transmission in the state via the engine clutch 12, the drive motor 13 and the transmission 14 are directly connected to each other.

In this configuration, when the engine clutch 12 is open, the drive shaft 15 of the vehicle is driven by the drive motor 13, and when the engine clutch 12 is locked, the engine 11 and the drive are driven. The drive shaft 15 of the vehicle is driven by the motor 13.

In addition, the driving motor 13 plays a role of engine starting, vehicle driving, regenerative braking, and battery charging, and accessories such as a hydraulic pump of a power steering device and a compressor of an air conditioner are driven by the engine 11 like a general vehicle.

In addition, the power steering system in the hybrid bus is a hydraulic power steering system that assists steering power by forming hydraulic pressure in a hydraulic pump driven by an engine.

In addition, the idle stop function is applied to stop the engine and improve fuel efficiency when the vehicle stops for a while after driving, and the engine is restarted if there is a driver's intention to start again from the idle stop state. The vehicle will start.

On the other hand, when the vehicle is stopped when the driver brakes at the corner of the vehicle (when turning the direction) or during a U-turn, and enters the idle stop mode, the engine is stopped and the hydraulic pressure supplied to the power steering device is released. As soon as it is released, the handle can be released with a strong force.

However, if the driver is holding the steering wheel, the sudden release of the steering wheel may cause injury to the driver. Therefore, the hybrid bus vehicle sets the steering angle of the steering wheel so that when the hydraulic pressure is released, the steering wheel is strongly released. Is turned on (judged from the signal from the steering angle sensor), the function to prohibit the idle stop is applied.

In addition, the steering angle sensor transmits the current steering angle information to the vehicle control unit (HCU) through CAN communication. As shown in FIG. 2, the steering angle detection error, for example, the detected steering angle is greater than or equal to a certain value (more than a maximum value). If the deviation is determined to be an error), if the steering angle sensor value is out of the physical range (invalid value) or CAN communication is lost (CAN communication error), the vehicle controller unconditionally limits the idle stop function (S1, S2).

As a result, when the steering angle sensor failure or CAN communication error occurs as described above, the idle stop function is unconditionally prohibited, so the fuel efficiency improvement effect is deteriorated during the continuous vehicle driving.

Therefore, the present invention has been created to solve the above problems, even if the normal steering angle signal is not input from the steering angle sensor due to a failure of the steering angle sensor or a CAN communication error, etc., the normal idle entry unless the actual corner driving or u-turn time, etc. It is an object of the present invention to provide a fail-safe control method in case of a steering angle detection error of a hybrid vehicle, which enables an idle stop mode to be performed under a condition.

In order to achieve the above object, the present invention, the process of comparing the left wheel speed and the right wheel speed in a hybrid vehicle; Comparing the steering angle detected by the steering angle sensor with a set reference value when the left wheel speed and the right wheel speed of the vehicle are the same; And determining that the steering angle sensor is a failure when the steering angle detected by the steering angle sensor exceeds a reference value.

Here, when the left wheel speed and the right wheel speed of the vehicle are the same and the steering angle detected by the steering angle sensor is less than the reference value, the steering angle sensor is determined to be normal, and the reference value is preferably set to 1rad.

In addition, the present invention provides a method of determining a steering angle sensor as a failure when a steering wheel detected by a steering angle sensor is equal to a left wheel speed and a right wheel speed in a hybrid vehicle; Comparing the left wheel speed and the right wheel speed when the steering angle sensor fails and a steering angle detection error including a CAN communication error is satisfied and the idle stop entry condition is satisfied; And when the left wheel speed and the right wheel speed of the vehicle is the same provides a fail-safe control method when the steering angle detection error of the hybrid vehicle comprising the step of allowing the idle stop.

Here, in the process of comparing the left wheel speed and the right wheel speed, the idle stop is prohibited when there is a difference between the left wheel speed and the right wheel speed.

Accordingly, according to the fail safe control method according to the present invention, it is configured to determine whether the idle stop is allowed using the left and right wheel speeds, so that even if a steering angle detection error such as a steering angle sensor failure or a CAN communication error occurs, corner driving is performed. Otherwise, the idle stop mode may be performed under normal idle stop entry conditions (ie, idle stop allowance), and thus, fuel efficiency may be reduced compared to the conventional art, in which an idle stop prohibition is unconditionally performed at the steering angle detection error. It can be increased.

1 is a schematic diagram showing the configuration of a hybrid powertrain applied to a hybrid bus.
2 is a view showing that the idle stop function is limited due to a signal of the steering angle sensor and a CAN communication error.
3 is a flowchart illustrating a process of diagnosing a failure of a steering angle sensor in the present invention.
4 is a diagram illustrating a difference in wheel speed according to a steering angle.
5 is a flowchart illustrating a process of determining whether an idle stop is allowed when a steering angle sensor breaks down in the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be easily understood by those skilled in the art.

3 is a flowchart illustrating a process of diagnosing a failure of a steering angle sensor in the present invention, and FIG. 4 is a flowchart illustrating a process of determining whether an idle stop is allowed when a steering angle sensor is failed in the present invention.

The present invention allows the idle stop mode to be performed under normal idle entry conditions even when a steering angle detection error such as a failure of the steering angle sensor or a CAN communication error occurs in actual corner driving or u-turn time (allowing idle stop). To provide a way.

To this end, the present invention performs fault diagnosis of the steering angle sensor using the wheel speed values of the left and right, and further, even if a steering angle detection error occurs, when the predetermined condition is satisfied using the left and right wheel speed values, an idle stop function is performed. There is a main feature to making this acceptable.

Basically, the idle stop should be banned normally to prevent driver injury due to the handle loosening during corner driving (turning direction) or U-turn of the vehicle.However, to reduce unnecessary idle stop ban (which causes lower fuel consumption), Idle stops should be prohibited only when driving or during U-turns, and idle stops should be allowed even if steering angle detection errors occur in corner driving or non-U-turn situations.

In the conventional case, the idle stop is prohibited to prevent a risk of driver injury due to the loosening of the handle during corner driving or u-turn, and furthermore, it is not possible to determine the corner driving or u-turn time to prevent the above-mentioned danger. In the case of a steering angle detection error situation, the idle stop was unconditionally prohibited.

However, even in the case of a steering angle detection error situation, it is not necessary to prohibit the idle stop unless it is a real corner driving or a U-turn time. If the idle stop is unconditionally prohibited only by the determination of the steering angle detection error, the fuel economy of the vehicle is deteriorated.

Therefore, in the present invention, it is possible to prohibit the idle stop only when the driving angle or the U-turn is true after determining that the steering angle detection error occurs, thereby solving the conventional problem.

That is, even when a steering angle detection error occurs, the idle stop is allowed to be allowed when the corner is not driven or the u-turn time, so that the idle stop is performed under normal idle stop entry conditions.

First, a failure diagnosis method of the steering angle sensor according to the present invention will be described with reference to FIG. 3.

In the related art, when the signal value of the steering angle sensor is out of the maximum value or more, it is determined to be an error, and the abnormality of the value within the steering angle range cannot be detected. In the present invention, the failure determination criteria of the steering angle sensor are supplemented.

As shown in FIG. 3, the vehicle controller performs fault diagnosis of the steering angle sensor by using left and right wheel speed values received from an ABS controller (ABS ECU). On the other hand, if the steering angle detected by the steering angle sensor is equal to or less than a preset reference value (eg, 1 rad), the steering angle sensor is normal (S11, S12).

However, if the steering angle detected by the steering angle sensor exceeds the reference value while the wheel speed values of the left and right sides are the same, the steering angle sensor is abnormal because the steering angle sensor is abnormal (S13).

4 is a diagram showing a difference in left and right wheel speeds according to a steering angle. As shown in FIG. 4, when the steering angle is less than a reference value, for example, 1 rad or less, the wheel speed difference of both left and right sides coincides with each other, but when the steering angle increases. There is a difference in wheel speeds on both sides.

That is, referring to FIG. 4, when the wheel speed values of both sides are the same, the steering angle detected by the steering angle sensor becomes 1 rad or less, and when the steering is performed by the driver operating the steering wheel during the rotation of the vehicle, the difference between the wheel speeds of both sides is obvious. It can be seen that.

Accordingly, in view of the above, the present invention is set to determine that the steering angle sensor is a failure when the wheel speed values at the left and right sides are the same and the steering angle exceeds the reference value.

In addition, the fail-safe control process at the time of detecting the failure of the steering angle sensor will be described. After the vehicle controller determines the failure of the steering angle sensor, if the steering angle value is an invalid value and a CAN communication error occurs (S21), When the idle stop entry condition is satisfied, the left and right wheel speed values are used to determine whether to allow or prohibit the idle stop.

For example, in the case where the current vehicle speed is a preset reference vehicle speed (eg, 2 km / h), if the left and right wheel speed values are the same, the idle stop function is allowed (S22, S23, S24), otherwise the idle stop is only Prohibit the function (S25).

Here, allowing the idle stop function means that the idle stop mode can be performed under normal idle entry conditions.

As a result, the present invention permits an idle stop even when a steering angle detection error occurs, but not during actual vehicle corner driving (turning direction) or u-turn time (i.e., when there is no vehicle rotation or steering). It is possible to reduce the idle stop prohibition rate during actual vehicle driving by allowing idle stops by judging that the vehicle is not driving in the corner of the vehicle or not in the u-turn time (by determining that the steering angle is almost zero).

As a result, even if an error in steering angle detection occurs, the case where the steering angle is almost zero is determined by using the wheel speed value, and even in this case, the fuel economy reduction rate can be reduced.

In this way, the present invention is configured to determine whether the idle stop is allowed by using the left and right wheel speeds, so that even if a steering angle detection error such as a steering angle sensor failure or a CAN communication error occurs, it is not a corner driving or a u-turn time. The idle stop mode can be performed under the idle stop entry condition of (i.e., the idle stop is allowed), and the fuel efficiency reduction effect can be increased as compared with the conventional case where the idle stop prohibition is unconditionally performed at the steering angle detection error.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. Modified forms are also included within the scope of the present invention.

11: engine 12: engine clutch
13: drive motor 14: transmission
15:

Claims (6)

Comparing the left wheel speed and the right wheel speed in the hybrid vehicle;
Comparing the steering angle detected by the steering angle sensor with a set reference value when the left wheel speed and the right wheel speed of the vehicle are the same; And
Determining that the steering angle sensor is faulty when the steering angle detected by the steering angle sensor exceeds a reference value;
Steering angle sensor failure diagnosis method of a hybrid vehicle comprising a.
The method according to claim 1,
The steering angle sensor failure diagnosis method of a hybrid vehicle, characterized in that the steering angle sensor is determined to be normal when the left wheel speed and the right wheel speed of the vehicle are the same and the steering angle detected by the steering angle sensor is less than the reference value.
The method according to claim 1 or 2,
Steering angle sensor failure diagnosis method for a hybrid vehicle, characterized in that the reference value is set to 1rad.
Determining that the steering angle sensor is faulty when the left wheel speed and the right wheel speed are the same in the hybrid vehicle and the steering angle detected by the steering angle sensor exceeds a set reference value;
Comparing the left wheel speed and the right wheel speed when the steering angle sensor fails and a steering angle detection error including a CAN communication error is satisfied and the idle stop entry condition is satisfied; And
Allowing an idle stop if the left wheel speed and the right wheel speed of the vehicle are the same;
Fail-safe control method when the steering angle detection error of a hybrid vehicle comprising a.
The method of claim 4,
And an idle stop is prohibited when there is a difference between the left wheel speed and the right wheel speed in the process of comparing the left wheel speed and the right wheel speed.
The method of claim 4,
The reference value is set to 1rad fail safe control method when a steering angle detection error of a hybrid vehicle.

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