Point 0 abnormality determination method and determination device of steering angle sensor

Abstract

To enable a steering angle sensor, which outputs a steering angle dependent on a rotatory manipulation quantity of a steering shaft with a rectilinear condition of a vehicle as point 0, to self-diagnose deviation of the point 0.SOLUTION: A travel time at a vehicle speed of 40 km / h or more is accumulated. When a vehicle has traveled until a cumulative value comes to 300 sec. or more (time t2), it is determined whether a steering angle θ outputted from a steering angle sensor remains equal to or larger than a predetermined threshold θsh during a period from when an ignition switch is turned on (time t1) to the time t2. When the steering angle remains equal to or larger than the threshold θsh, point 0 is thought to be abnormal. An abnormality determination flag is set to 1, and an alarm lamp is lit. This diagnosis is repeatedly carried out during travel.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a technique for determining an abnormality at the 0 point of a steering angle sensor that outputs a steering angle corresponding to an amount of rotation of a steering shaft, with the straight-ahead state of a vehicle being set as the 0 point. [Background technology]

[0002] In general, a steering angle sensor is provided on the steering shaft of a vehicle to detect the steering angle. As exemplified in Patent Document 1, the steering angle sensor outputs an output signal corresponding to the amount of rotation of the steering shaft as the steering angle, with the straight-ahead state of the vehicle being designated as 0 point. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-340625 A Summary of the Invention [Problem to be solved by the invention]

[0004] Calibration of the zero point of the steering angle sensor is performed, for example, in the final process of an automobile production line, such as a finished vehicle inspection process, by correctly aligning the steering device of the vehicle in a straight-ahead state and then resetting the output of the steering angle sensor. However, there is a risk that the zero point may be shifted due to some cause such as human error. In such a case, it is desirable to be able to quickly detect an abnormality in the zero point as one of the so-called self-diagnosis functions.

[0005] Incidentally, Patent Document 1 relates to fault detection when the output signal of the steering angle sensor does not change, and cannot detect an abnormality at the zero point. [Means for solving the problem]

[0006] The present invention is a zero point abnormality determination method for a steering angle sensor that outputs a steering angle according to a rotation operation amount of a steering shaft, with a straight traveling state of a vehicle being set as a zero point, If a steering angle equal to or greater than a threshold continues to be output while the vehicle is traveling at or above a predetermined speed until a predetermined cumulative time has elapsed, it is determined that the zero point has shifted.

[0007] If the zero point is deviated, a steering angle corresponding to the amount of deviation will be output when the vehicle is traveling straight with the steering device in a straight-ahead state. In the present invention, it is determined that the zero point is deviated when a steering angle equal to or greater than a threshold value continues to be output until the vehicle continues traveling at a predetermined speed or greater for a predetermined cumulative time. Effect of the Invention

[0008] According to this invention, if there is a deviation of the zero point of a magnitude corresponding to the threshold value, the abnormality can be detected while the vehicle is traveling. By setting a condition that a steering angle equal to or greater than the threshold value continues to be output until the vehicle is traveling at a predetermined speed or greater for a predetermined cumulative time, undesirable erroneous judgments can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is an explanatory diagram showing a system configuration of a zero-point anomaly determination device according to an embodiment. [Diagram 2] 4 is a flowchart showing a flow of processing by a controller. [Diagram 3] 4 is a time chart illustrating the operation of an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an explanatory diagram showing the system configuration of a zero point abnormality determination device according to an embodiment. The zero point abnormality determination device is configured as a part of the functions of a computer system mounted on a vehicle. The steering angle sensor 1 includes a sensor body 1A provided on a steering shaft equipped with a steering wheel, and a sensor unit 1B that processes the signal. The sensor body 1A may be of any type, such as an optical type, a magnetic type, or an electromagnetic induction type, and is configured to emit a pulse signal for each unit angle when the steering shaft rotates. The sensor unit 1B counts the pulse signals output by the sensor body 1A to obtain the rotation operation amount of the steering shaft (steering wheel), and outputs a signal of the steering angle θ based on the zero point to the controller 2. As described above, for example, in a finished vehicle inspection process, the zero point of the steering angle sensor 1 is calibrated by giving a reset signal to the sensor unit 1B with the steering device of the vehicle including the steering wheel in a correctly straight-ahead state.

[0011] An output signal from a vehicle speed detection unit 3 that detects a vehicle speed VSP is input to the controller 2. A warning light 4 provided in a meter unit in front of the driver's seat is also connected to the controller 2. When an abnormality is detected at the 0 point of the steering angle sensor 1 as described later, the controller 2 lights up the warning light 4 to notify the abnormality.

[0012] The controller 2 has various functions for controlling the vehicle, engine, etc., among which are an idling stop control unit 11 related to the idling stop function, and a zero point diagnosis unit 12 that performs self-diagnosis of zero point abnormalities of the steering angle sensor 1.

[0013] The idling stop control unit 11 automatically stops the engine of the vehicle (so-called idling stop) when a predetermined idling stop condition is satisfied, and then automatically restarts the engine when a predetermined restart condition is satisfied. The idling stop condition is an AND condition of several conditions (elements), such as the vehicle speed VSP being approximately 0, the brake switch being ON, the cooling water temperature being higher than the idling stop permission water temperature, and the battery voltage being equal to or higher than a predetermined level. The restart condition is an OR condition of several conditions (elements), such as the brake switch being OFF, a start request from the air conditioner, a drop in the battery voltage, and the cooling water temperature being equal to or lower than the idling stop permission water temperature. Here, in this embodiment, one of the elements of the idling stop condition is that the steering angle θ is less than a predetermined idling stop permission steering angle. This is in consideration of a change in steering reaction force accompanying engine stop, that is, kickback acting on the steering wheel, and idling stop is prohibited even if the vehicle is stopped in a state where the steering angle is equal to or higher than the idling stop permission steering angle.

[0014] Since the steering angle θ is one of the conditions for idling stop, if the zero point of the steering angle sensor 1 is abnormal, for example, even if the steering device of the vehicle is actually in a straight-ahead state, the calculated steering angle θ may be equal to or larger than the idling stop permission steering angle, and idling stop may be prohibited. As a result, the desired fuel economy characteristics may not be obtained.

[0015] In order to avoid such an undesirable prohibition of idling stop, the zero point diagnosis unit 12 repeatedly judges whether the zero point is abnormal after the ignition switch of the vehicle is turned on. The zero point diagnosis unit 12 judges that the zero point is deviated when a steering angle equal to or greater than the threshold value continues to be output until the driving at a predetermined speed or more reaches a predetermined cumulative time. As an example of a specific numerical value, when a steering angle θ equal to or greater than the threshold value θsh continues to be detected until the driving at a vehicle speed of 40 km / h or more reaches a cumulative time of 300 seconds, the zero point is judged to be abnormal. The threshold value θsh is, for example, 50° as the angle of the steering wheel. Note that the steering angle θ, which is set to 0 when traveling straight, can take positive and negative values ​​if one of the left and right sides is positive, so strictly speaking, the threshold value θsh is 50° for both positive and negative. "Equal to or greater than the threshold value θsh" means that in the case of a negative value, the magnitude of the value (absolute value) is equal to or greater than the value of the threshold value θsh.

[0016] The threshold value θsh is not limited to 50° and can be set to an appropriate value, but if it is too small, a normal zero point is likely to be erroneously determined to be abnormal, and conversely, if it is too large, a smaller deviation of the zero point is permitted. In a preferred embodiment, the threshold value θsh is set to a steering angle slightly larger than the idling stop permission steering angle. For example, when the idling stop permission steering angle is 45° as the angle of the steering wheel, the threshold value θsh is set to 50° with an appropriate margin (5°) added.

[0017] 2 is a flowchart showing the flow of processing executed by the controller 2 as the zero point diagnosis unit 12. In step 1, it is determined whether or not the vehicle has traveled at 40 km / h or more for a cumulative total of 300 seconds or more. If the result is NO, the determination in step 1 is repeated until the vehicle has traveled at 40 km / h or more for a cumulative total of 300 seconds or more.

[0018] If the determination in step 1 is YES, the process proceeds from step 1 to step 2, where it is determined whether the output value of the steering angle θ has remained equal to or greater than the threshold value θsh until the cumulative total of the driving time of 40 km / h or more reaches 300 seconds or more. If the determination in step 2 is YES, the process proceeds to step 3, where it is determined that the zero point of the steering angle sensor 1 is abnormal, and the warning light 4 is turned on.

[0019] On the other hand, if the determination in step 2 is NO, the process proceeds to step 4, where the driving history in step 1 is reset. Then, in step 1, the vehicle is driven again until it has traveled at 40 km / h or more for a cumulative total of 300 seconds or more, and when this total reaches 300 seconds, the determination in step 2 is performed. In other words, the processes in steps 1 and 2 are repeated while the vehicle is traveling.

[0020] FIG. 3 is a time chart showing an example of the operation of the zero point abnormality judgment device, and shows (a) the state of the ignition switch, (b) vehicle speed, (c) cumulative time of driving at 40 km / h or more, (d) steering angle θ (output value of steering angle sensor 1), and (e) zero point abnormality judgment flag.

[0021] In the illustrated example, after the ignition switch is turned on at time t1, the vehicle starts to run, and as shown in (b), the vehicle repeatedly starts and stops. As shown in (c), the running time during which the vehicle speed is 40 km / h or more is accumulated, and when it reaches 300 seconds (time t2), it is determined whether the steering angle θ has been continuously equal to or greater than the threshold value θsh during that time (i.e., between t1 and t2). In the illustrated example, as shown in (d), a steering angle θ equal to or greater than the threshold value θsh has been continuously output during the time from t1 to t2, so it is determined that a zero point abnormality has occurred, and the zero point abnormality determination flag shown in (e) is set to 1.

[0022] At time t2, if the steering angle θ is not continuously equal to or greater than the threshold value θsh between times t1 and t2, the cumulative time shown in section (c) is reset. For example, if the steering angle θ is below the threshold value θsh even temporarily between times t1 and t2, it is not determined to be a zero point abnormality. Then, every time the cumulative time reaches 300 seconds, the determination of the steering angle θ is repeated.

[0023] The change in steering angle θ in FIG. 3(d) indicates that the driver steers the steering wheel from a state in which the zero point is shifted.

[0024] The numerical examples of 40 km / h and 300 seconds are set based on the viewpoint that it is very rare to continue driving while steering in the same direction at such a vehicle speed. In other words, if the zero point deviates by more than the threshold value θsh, for example, when driving on a nearly straight road at 40 km / h or more for a cumulative total of 300 seconds, it is determined that there is an abnormality. Such a driving situation may generally occur. On the other hand, if the zero point is normal and the vehicle is driven at 40 km / h or more for a cumulative total of 300 seconds or more while steering in the same direction, it may be erroneously determined that there is an abnormality, but in reality, such a driving situation is almost impossible.

[0025] The present invention is not limited to the numerical examples of 40 km / h and 300 seconds, and may be set to appropriate values ​​from the above viewpoints.

[0026] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. In the above embodiment, the zero point abnormality of the steering angle sensor has been described as being related to the idling stop function, but the present invention can be widely applied as a technology for detecting deviation of the zero point of the steering angle sensor, regardless of the presence or absence of the idling stop function. [Explanation of symbols]

[0027] 1...Steering angle sensor 2. Controller 3…Vehicle speed detection section 4…Warning light 11...Idling stop control unit 12...0 point diagnostic section

Claims

1. A zero point abnormality determination method for a steering angle sensor that outputs a steering angle according to a rotation operation amount of a steering shaft, with a straight running state of a vehicle being set as a zero point, comprising: When a steering angle equal to or greater than a threshold continues to be output while the vehicle is traveling at or above a predetermined speed for a predetermined cumulative time, the zero point is determined to be shifted. A method for determining zero point abnormality of a steering angle sensor.

2. After the ignition switch is turned on, each time the vehicle is driven at a speed equal to or greater than a predetermined speed for a predetermined cumulative time, it is repeatedly determined whether a steering angle equal to or greater than a threshold value has been output.

2. The method for determining zero point abnormality of a steering angle sensor according to claim 1.

3. Used in a vehicle equipped with an idling stop function that stops the engine when a specified idling stop condition is met, One of the idling stop conditions is that the steering angle detected by the steering angle sensor is less than a predetermined value.

2. The method for determining zero point abnormality of a steering angle sensor according to claim 1.

4. The threshold value is set to a steering angle larger than the predetermined value that satisfies an idling stop condition.

4. The method for determining zero point abnormality of a steering angle sensor according to claim 3.

5. a steering angle sensor that outputs a steering angle according to a rotational operation amount of a steering shaft, with a straight-ahead state of the vehicle being set as 0 point; A vehicle speed detection unit that detects a vehicle speed; A controller; Equipped with The controller determines that the zero point is shifted when a steering angle equal to or greater than a threshold value continues to be output until a predetermined cumulative time has elapsed since the vehicle was driven at a predetermined speed or greater. A zero point abnormality determination device for a steering angle sensor.

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