JP3104507B2 - Abnormality determination device in power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality judging device in a power steering device, and more particularly to an abnormality judging device in a power steering device for judging whether or not an abnormality has occurred in the power steering device.

[0002]

2. Description of the Related Art A conventional power steering apparatus includes a vehicle speed detecting sensor for detecting a vehicle speed, a torque sensor for detecting a steering torque applied to a steering shaft, a motor for assisting rotation of the steering shaft, a steering torque and a vehicle speed. Control means for determining an assisting amount for assisting the rotation of the steering shaft based on the control amount, and controlling the rotation of the motor in accordance with the assisting amount.

[0003] In the power steering device configured as described above, when a failure of the torque sensor or the like occurs, a malfunction may occur in which the motor operates against the driver's intention. As described above, when the motor operates against the driver's intention, an uncomfortable feeling occurs, and the steering feeling deteriorates. In view of this point, the torque change rate is detected, the threshold value of the torque change rate is changed according to the vehicle speed, and the torque change rate is compared with the threshold value changed according to the vehicle speed. A power steering device has been proposed in which a failure of a sensor is determined, and if a failure occurs in the torque sensor, the auxiliary rotation of the steering shaft is stopped to shift to a manual operation (Japanese Patent Laid-Open No. 1-223072).
No.).

[0004]

However, erroneous operation of the motor, which occurs against the driver's intention, occurs due to various causes such as a failure of the torque sensor and a failure of the ECU. Therefore, in the power steering device that determines the failure of the torque sensor by comparing the rate of change of the torque with the threshold value that is changed according to the vehicle speed, the malfunction is reliably determined because only the failure of the torque sensor is determined. Not detectable.

On the other hand, if a plurality of detection items such as a failure of a torque sensor and a failure of an ECU are provided in order to reliably detect a malfunction, the control becomes complicated and the following problem occurs.

That is, in the power steering device,
The vehicle speed and the steering torque are detected, the auxiliary rotation amount of the motor is calculated according to the obtained vehicle speed and the steering torque, and control is performed to output a signal corresponding to the calculated auxiliary rotation amount to the motor. The time from the detection of the vehicle speed or the like to the output of the signal corresponding to the auxiliary rotation amount to the motor (torque-based calculation cycle) needs to be short in order to perform smooth auxiliary steering by the motor. On the other hand, in order to reliably detect the malfunction described above and drive the vehicle safely, it is necessary to detect whether or not the cause of the malfunction has occurred at every torque system calculation cycle or at a cycle close to the torque system calculation cycle. There is a need to. However, if all the causes of the malfunction described above are detected,
Since there are many detection items, it is necessary to lengthen the torque-related operation cycle. For this reason, smooth auxiliary steering by the motor cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and describes an abnormality in a power steering apparatus capable of detecting whether or not a malfunction of a motor occurs against a driver's intention by a simple method. It is an object to provide a determination device.

[0008]

According to the first aspect of the present invention, a steering torque is detected, and an assisting amount for assisting the rotation of the steering shaft is determined based on the detected steering torque. In a power steering apparatus that controls a rotation angle of a motor according to an amount to rotate a steering shaft, a motor rotation angle detection unit that detects a rotation angle of the motor, and a wheel rotation angle detection unit that detects a rotation angle of a steering wheel And abnormality determining means for determining that an abnormality has occurred when the detected motor rotation angle is ahead of the detected wheel rotation angle.

According to the second aspect of the present invention, the steering torque is detected, the assist amount for assisting the rotation of the steering shaft is determined based on the detected steering torque, and the rotation angle of the motor is controlled in accordance with the assist amount. In a power steering device for rotating a steering shaft, a motor rotation angle detection unit for detecting a rotation angle of the motor, a wheel rotation angle detection unit for detecting a rotation angle of a steering wheel, and integrating the detected steering torque. Integration means, and abnormality determination means for determining that an abnormality has occurred when the detected motor rotation angle precedes the detected wheel rotation angle and the integrated value is greater than a predetermined value,
It has.

[0010]

According to the first aspect of the present invention, the steering torque is detected, the assist amount for assisting the rotation of the steering shaft is determined based on the detected steering torque, and the rotation angle of the motor is controlled in accordance with the assist amount. To rotate the steering shaft. The motor rotation angle detection means detects the rotation angle of the motor, and the wheel rotation angle detection means detects the rotation angle of the steering wheel. The abnormality determining means determines that an abnormality has occurred when the detected motor rotation angle is ahead of the detected wheel rotation angle.

As described above, since it is determined that an abnormality has occurred when the motor rotation angle is ahead of the wheel rotation angle, it is determined whether or not the motor has malfunctioned against the driver's intention. Can be reliably detected.

That is, in the power steering device,
When the driver rotates the steering wheel, a steering torque is applied to the steering shaft, and an auxiliary rotation amount (hereinafter referred to as an assist amount) that assists the rotation of the steering shaft determined based on the steering torque obtained by detecting the steering torque. Is output to the motor.
Thus, the motor assists the rotation of the steering shaft according to the assist amount. Therefore, when there is no failure in the torque sensor, the ECU, or the like, the wheel rotation angle precedes the motor rotation angle of the motor. On the other hand, when a failure occurs in the torque sensor, the ECU, or the like, the motor rotation angle leads the wheel rotation angle as shown in FIG. Therefore, when the motor rotation angle is ahead of the wheel rotation angle, it is possible to reliably detect that a malfunction has occurred in which the motor operates against the driver's intention.

On the other hand, when the steering wheel is returned to its original position at the end of the corner running, when the tire tries to return to the direction of running on a straight road (when force is reversely input from the road surface to the tire), torque is applied to the steering shaft. As a result, the motor rotation angle of the motor may precede the wheel rotation angle of the steering wheel. As a result, it may be erroneously determined that a malfunction in which the motor operates against the driver's intention has occurred. However, the absolute value of the steering torque of the steering wheel in this case is small or an instantaneous value.

Therefore, in the present invention, the motor rotation angle detecting means detects the rotation angle of the motor, and the wheel rotation angle detecting means detects the rotation angle of the steering wheel. The integrating means integrates the detected steering torque. The abnormality determining means determines that an abnormality has occurred when the detected motor rotation angle precedes the detected wheel rotation angle and the integral value is greater than a predetermined value.

As described above, if the motor rotation angle precedes the wheel rotation angle and the integral value is larger than the predetermined value, it is determined that an abnormality has occurred. Therefore, the steering wheel at the end of corner running is returned to the original position. The torque applied to the steering shaft at the time or when the tire attempts to return to the direction of traveling on a straight road does not cause erroneous determination that a malfunction of the motor has occurred against the driver's intention.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic configuration of an abnormality determination device in the power steering device of the present embodiment.
As shown in FIG. 1, the abnormality determination device includes an electronic control device 12 as abnormality determination means and integration means.
The electronic control unit 12 includes a steering wheel 30
A wheel rotation angle sensor 14 as a wheel rotation angle detecting means for detecting the wheel rotation angle theta _h of a torque sensor 16 for detecting a steering torque applied to the steering shaft 32, a vehicle speed sensor 18 for detecting a vehicle speed, are connected ing. The electronic control unit 12 is connected with a motor 20 for assisting the rotation of the steering shaft 32 and an electromagnetic clutch 22 meshed with the motor 20, and further detects a rotation angle of the motor 20. A motor rotation angle sensor 24 as a motor rotation angle detecting means is connected. Further, a warning lamp 36 is connected to the electronic control unit 12.

The steering shaft 32 is meshed with a rack and pinion gear 28 via a reduction gear 26, and the reduction gear 26 is further meshed with the electromagnetic clutch 22.

FIG. 2 is a block diagram of the electronic control unit 12 described above. As shown in FIG. 2, the electronic control unit 12 includes a microcomputer 40. The microcomputer 40 includes a CPU (Central Processing Unit) 42, a ROM 44, a RAM 46, an input port device 48, and an output port device 50 connected to the CPU 42 via a bus 52.
The input port device 48 includes a wheel rotation angle sensor 14,
The torque sensor 16, the vehicle speed sensor 18, and the motor rotation angle sensor 24 are connected. Also, the output port device 50
Is connected to the motor 2 via the warning lamp 36 and the drive circuit 54.
0 is connected to the electromagnetic clutch 22 via the drive circuit 56. The ROM 44 stores in advance control routines and the like corresponding to flowcharts described later.

Next, the operation of the present embodiment will be described with reference to the control routine of the CPU 42 shown in FIGS. FIG. 3 shows a control main routine showing control of processing for assisting the rotation of the steering shaft 32, and FIG. 4 shows a control subroutine of abnormality determination processing. In addition,
The control main routine of the processing for assisting the rotation of the steering shaft 32 is executed at predetermined time intervals, and the control subroutine of the abnormality determination processing is interrupted and executed before the control main routine is executed. This control subroutine may be interrupted and executed when the control main routine is executed a plurality of times.

First, control of the process for assisting the rotation of the steering shaft 32 (see FIG. 3) will be described. In step 102, it is determined whether the flag F is set to "1". This flag F is set to 1 when it is determined that an abnormality has occurred in the abnormality determination processing control shown in FIG. 4, and is set to 0 when it is determined that no abnormality has occurred. When no abnormality has occurred (when no malfunction of the motor has occurred), since the flag F is 0,
In step 104, the electromagnetic clutch 22 is connected. In the next step 106, a signal from the torque sensor 16 and a signal from the vehicle speed sensor 18 are read, and the steering torque and the vehicle speed are captured. In step 108, the basic assist amount T
Read ab. Here, the basic assist amount Tab is a basic rotation amount of the assist amount of the motor that assists the rotation of the steering shaft 32 according to the steering torque. The basic assist amount Tab and the steering torque have the relationship shown in FIG. In this embodiment, this relationship is stored in the ROM 44 as a map. Therefore, a corresponding basic assist amount can be read from this map according to the taken steering torque.

In step 110, a vehicle speed coefficient Kv corresponding to the vehicle speed is read. Here, the vehicle speed and the vehicle speed coefficient Kv have the relationship shown in FIG. In this embodiment, this relationship is stored in the ROM 44 as a map. Therefore,
The corresponding vehicle speed coefficient Kv can be read from this map according to the taken vehicle speed.

In step 112, the assist amount Ta is calculated from the following equation (1). Ta = Kv × Tab (1) Here, the assist amount Ta is an assist amount of a motor that assists the rotation of the steering shaft 32 according to the steering torque and the vehicle speed. That is, when the host vehicle is traveling at a high speed, a large steering torque is required to reduce the assist amount and rotate the steering wheel 30, so that stable operation of the steering wheel 30 is achieved. Is what you can do. On the other hand, when the vehicle is traveling at a low speed, the assist amount is increased so that the rotation of the steering wheel 30 can be performed with a small steering torque, and the traveling direction of the vehicle can be increased with a small steering torque. It allows you to change it.

Next, at step 114, step 112
Is output to the motor 20 and the control ends.

On the other hand, if the flag F is set to 1 in step 102, it can be determined that an abnormality (a malfunction of the motor has occurred). Therefore, in step 116, the connection of the electromagnetic clutch 22 is released. Then, the operation is switched to the manual operation, and in step 118, the warning lamp 36 is turned on to notify the driver that a malfunction has occurred, and the control is terminated.

Next, control of the abnormality determination processing will be described with reference to FIG. In step 122, the motor rotation angle theta _m of the motor 20 uptake by the signal from the motor rotation angle sensor 24, at step 124, the wheel rotation angle theta _h of the steering wheel 30 takes in a signal from the wheel rotation angle sensor 14. Note that these rotation angles are such that the neutral point of the steering wheel 30 is 0, the right steering direction is positive, and the left steering direction is negative. Next step 126
In, by subtracting the motor rotation angle theta _m from the wheel rotation angle theta _h, to the subtraction value [Delta] [theta]. In step 128, the motor rotation angle θm _(n-1) in the previous control is subtracted from the motor rotation angle θm _{(n) in} the current control, and this subtraction value is represented by ΔD
ir. In step 130, Δθ is multiplied by ΔDir, and the multiplied value is set to H.

At step 132, it is determined whether or not the multiplication value H calculated at step 130 is positive. Here, when the multiplication value H is equal to or greater than zero is when the wheel rotation angle theta _h of the steering wheel 30 is ahead of the motor rotation angle theta _m of the motor 20. On the other hand, the multiplication value H
As in the case but a negative value, the wheel rotation angle of the motor rotation angle theta _m steering wheel 30 of the motor 20 theta
_This is the case where it is earlier than _h , that is, there is a possibility that an abnormality has occurred.

If the multiplied value H is a value equal to or greater than 0, the routine proceeds to step 144, and if the multiplied value H is a negative value, the routine proceeds to step 134 where the control is repeatedly executed for a predetermined time. In order to count the number of consecutive times when the multiplication value H is a negative value, the count value N is incremented by 1 and the basic assist amount Tab is added to the variable G in step 136. That is, the basic assist amount Tab in the current control is added again to the variable G to which the basic assist amount Tab has been added when the above-described multiplication value H is a negative value in the previous control. The reason will be described later.

[0028] In the next step 138, the count value N is determined whether or not a predetermined number value N ₀ or more. That is, when the count value N is equal to or larger than the predetermined number value N ₀ , in the present control that is repeatedly executed at predetermined time intervals, the motor rotation angle θ _m is ahead of the wheel rotation angle θ _h continuously N ₀ times. It is determined that you are doing. Count value N
If is not equal to or greater than the predetermined number value N ₀ , step
If the count value N is equal to or _larger than the predetermined number value N _0, it is determined in step 140 whether the variable G is equal to or larger than the predetermined value G ₀ .

That is, as described above, torque is applied to the steering shaft when the steering wheel is returned to its original position at the end of running at a corner or when the tire attempts to return to the direction of running on a straight road, and the motor rotation angle of the motor 20 is increased. there are cases where theta _m is precedes wheel rotation angle theta _h of the steering wheel 30. As a result, it may be erroneously determined that a malfunction in which the motor operates against the driver's intention has occurred. However, the steering torque of the steering wheel when a malfunction occurs is smaller than the steering torque at the time of returning the steering wheel at the end of corner running, or the like.
Or, it is a near value but an instantaneous value. Therefore, when the steering torque at the time of returning the steering wheel at the end of the corner traveling a plurality of times as in the above-described step 136 is added together, the added value becomes the steering torque when a malfunction occurs. It is smaller than the added value of the torque. Therefore, when the steering torques are added together, when a malfunction occurs, or when the steering wheel is returned to its original position at the end of the corner running, the motor rotation angle θ _m of the motor 20 becomes larger than the wheel rotation of the steering wheel 30. are you ahead angle theta _h, it can be determined. By the way, the basic assist amount Tab corresponds to the steering torque, and the assist amount Ta
Is obtained by multiplying the basic assist amount Tab by a vehicle speed coefficient corresponding to the vehicle speed, and thus corresponds to the steering torque. Therefore,
In this embodiment, as compared with a predetermined value G ₀ which corresponds to the sum of the steering torque when the sum of the basic assist amount Tab (the variable G in step 136), malfunction has occurred.

If the variable G is equal to or _larger than the predetermined value G0 in step 120, a malfunction has occurred, so in step 142, the flag F is set to 1 and the control is terminated.

If it is determined in step 132 that the multiplication value H is equal to or greater than 0, the count value N is set to 0 in step 144, and the variable G is set to 0 in step 146.
Set to. Here, when the multiplication value H is equal to or greater than 0, or when the count value N is not equal to or greater than the predetermined value N ₀ and when the variable G is not equal to or greater than the predetermined value G ₀ , it can be determined that no malfunction has occurred. , At step 128, the flag F
Is set to 0, and this control ends.

As described above, in this embodiment, it is possible to judge whether or not a malfunction of the motor has occurred against the driver's intention by comparing the motor rotation angle and the wheel rotation angle. Therefore, it is not necessary to detect various items such as a failure of the torque sensor, a failure of the ECU, and the like that cause a malfunction, and it is possible to determine whether the malfunction has occurred by a simple method.

Further, in this embodiment, since the cause of the malfunction is not detected, it is not necessary to detect all the causes of the malfunction by lengthening the operation cycle of the torque system. Can be realized.

Further, when the motor rotation angle is ahead of the wheel rotation angle and the added value (integral value) of the basic assist amount is larger than a predetermined value, it is determined that an abnormality has occurred. The torque applied to the steering shaft when returning the steering wheel to its original position or when trying to return the tire to the direction of traveling on a straight road does not mistakenly determine that the motor has operated incorrectly against the driver's will .

In the present embodiment described above, the basic assist amount is determined based on the torque applied to the steering shaft when the steering wheel is returned to the original position at the end of the corner running, so as not to judge that the motor has malfunctioned. Is added, but the present invention is not limited to this, and the assist amount may be added, or the steering torque may be added.

[0036]

As described above, according to the first aspect of the present invention, it is determined that an abnormality has occurred when the motor rotation angle is ahead of the wheel rotation angle. Has an excellent effect that it is possible to reliably detect whether or not malfunctions.

According to a second aspect of the present invention, when the motor rotation angle precedes the wheel rotation angle and the integral value is larger than a predetermined value, it is determined that an abnormality has occurred. The excellent effect that the torque applied to the steering shaft when returning the tire to the original direction or when trying to return to the direction in which the tire travels on a straight road does not mistakenly determine that the motor has malfunctioned against the driver's will. Having.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an abnormality determination device in a power steering device according to an embodiment.

FIG. 2 is a block diagram of an electronic control device.

FIG. 3 is a flowchart illustrating a control routine of a process for assisting rotation of a steering shaft.

FIG. 4 is a flowchart illustrating a control routine of an abnormality determination process.

FIG. 5 is a diagram showing a relationship between a steering torque and a basic assist amount stored as a map in a ROM.

FIG. 6 is a diagram showing a relationship between a vehicle speed and a vehicle speed coefficient stored as a map in a ROM.

FIG. 7 is a diagram illustrating a relationship between a motor rotation angle and a wheel rotation angle when a malfunction occurs in which a motor operates against a driver's intention;

[Explanation of symbols]

 Reference Signs List 12 electronic control device 14 wheel rotation angle detection sensor 16 torque detection sensor 18 vehicle speed sensor 20 motor 22 electromagnetic clutch 24 motor rotation angle detection sensor 26 reduction gear 28 rack and pinion gear 30 steering wheel 32 steering shaft 34 rack 36 warning lamp

Continuation of the front page (56) References JP-A-6-336167 (JP, A) JP-A-64-18776 (JP, A) JP-A-63-242771 (JP, A) JP-A-63-173758 (JP, A) JP-A-64-4572 (JP, A) JP-A-63-28761 (JP, A) JP-A-63-173760 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B62D 6/00 B62D 5/04

Claims (2)

(57) [Claims] 1. A steering torque is detected, an auxiliary amount for assisting rotation of a steering shaft is determined based on the detected steering torque, and a rotation angle of a motor is controlled in accordance with the auxiliary amount to rotate the steering shaft. In the power steering device, a motor rotation angle detection unit that detects a rotation angle of the motor, a wheel rotation angle detection unit that detects a rotation angle of a steering wheel, and a wheel rotation angle in which the detected motor rotation angle is the detected wheel rotation angle An abnormality determination device for a power steering device, comprising: abnormality determination means for determining that an abnormality has occurred when the vehicle is ahead of the vehicle. 2. A steering torque is detected, an auxiliary amount for assisting the rotation of the steering shaft is determined based on the detected steering torque, and the rotation angle of the motor is controlled according to the auxiliary amount to rotate the steering shaft. In the power steering device, a motor rotation angle detection unit that detects a rotation angle of the motor; a wheel rotation angle detection unit that detects a rotation angle of a steering wheel; an integration unit that integrates the detected steering torque; Abnormality determination means for determining that an abnormality has occurred when the detected motor rotation angle precedes the detected wheel rotation angle and the integral value is greater than a predetermined value. .