JP2016055678A - Steering device and electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device which can detect an abnormal situation in which deviation occurs in a correspondence relationship between rotational angle information which is detected by a rotation angle detection device and an actual steering angle of a steering wheel.SOLUTION: The electric power steering device comprises a torque sensor 30 which is arranged at a column shaft, and detects steering torque Th, a motor which imparts an assist force to the column shaft, and a rotation angle detection device 44 which detects a rotation angle θe of an output shaft 21a of the motor. The rotation angle detection device 44 comprises a rotation detection part 61 which changes a value of a counter 61a on the basis of the motor rotation angle θe, and an abnormality detection part 62 which detects an abnormality on the basis of the steering torque Th which is detected by the torque sensor 30, and the value of the counter 61a. A microcomputer 40 calculates a steering angle on the basis of the value of the counter 61a. When the abnormality detection part 62 detects a change of the value of the counter 61a, the abnormality detection part detects the abnormality on the basis that the steering torque Th is smaller than a prescribed threshold.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a steering device and an electric power steering device.

  2. Description of the Related Art An electric power steering device (EPS) that assists a driver's steering operation by applying an assist force to a column shaft of a vehicle is known. This EPS includes a torque sensor that detects a steering torque applied to a steering wheel, a motor that applies an assist force to a steering shaft, a rotation angle detection device that detects a rotation angle of an output shaft of the motor, and a drive of the motor. And a control device for controlling. The steering shaft has a configuration in which a column shaft, an intermediate shaft, and a pinion shaft are sequentially connected from the steering wheel side. The pinion shaft is connected to the rack shaft via a rack and pinion mechanism. The output shaft of the motor is connected to the column shaft via a speed reducer. The control device calculates a current command value based on the steering torque detected by the torque sensor, and controls the motor supply current based on the calculated current command value and the motor rotation angle detected by the rotation angle detection device. To control the motor drive.

  Some EPSs detect the rotation angle of the column shaft based on the motor rotation angle detected by the rotation angle detection device, in other words, the steering angle of the steering wheel. As this kind of EPS, there is an EPS described in Patent Document 1, for example.

  In the EPS of Patent Document 1, an ASIC (Application Specific Integrated Circuit) that detects and stores a steering angle is provided in the rotation angle detection device. The ASIC intermittently detects and stores the steering angle while the IG switch is on. Thereby, when the steering angle is changed by operating the steering wheel while the IG switch is turned off, the change is detected and stored by the ASIC. Therefore, the control device can detect the change in the steering angle while the IG switch is turned off by acquiring the steering angle information from the ASIC when the IG switch is turned on. False detection can be suppressed.

Japanese Patent No. 5333994

  By the way, in the rotation angle detection device of Patent Document 1, when the steering wheel is operated in a special situation, a deviation occurs in the correspondence relationship between the steering angle detected by the ASIC and the actual turning angle of the steered wheels. there is a possibility.

  For example, it is assumed that an operator removes the intermediate shaft from the EPS during vehicle maintenance. At this time, if the worker does not remove the in-vehicle battery, the ASIC continues to detect and store the steering angle because the power supply to the ASIC is still performed. Therefore, when the steering angle is changed by the operator operating the steering wheel, the change is detected by the ASIC. However, in the state where the intermediate shaft is removed, the mechanical connection between the column shaft and the pinion shaft is eliminated, so that the steering torque applied to the steering wheel is not transmitted to the rack shaft. Therefore, the turning angle of the steered wheels does not change. Therefore, when the operator subsequently connects the intermediate shaft to the column shaft and the pinion shaft at an arbitrary position, a deviation occurs in the correspondence between the steering angle detected by the ASIC and the actual turning angle of the steered wheels. there is a possibility.

  The present invention has been made in view of such circumstances, and its purpose is an abnormality in which the correspondence between the rotation angle information detected by the rotation angle detection device and the actual turning angle of the steered wheels is shifted. It is an object of the present invention to provide a steering device and an electric power steering device that can detect various situations.

  When the intermediate shaft is removed from the steering device, the mechanical connection between the column shaft and the pinion shaft is eliminated, so that the road surface reaction force applied to the vehicle tire is not transmitted to the steering wheel. Therefore, the steering wheel rotates only by the operator applying a slight steering torque to the steering wheel. Focusing on this point, when the steering angle of the steering wheel changes, if the steering torque is small, it can be determined that the steering wheel is operated with the intermediate shaft removed from the steering device.

  Therefore, in order to solve the above problem, in the steering device, a torque sensor that is provided on the column shaft of the vehicle and detects steering torque, and a rotation angle detection device that detects rotation angle information related to the steering angle of the steering wheel, When a change in the rotation angle information detected by the rotation angle detection device is detected, the steering torque detected by the torque sensor is a mechanical connection between the column shaft and the pinion shaft connected to the column shaft. And an abnormality detection unit that detects an abnormality based on being less than a threshold value indicating cancellation.

  According to this configuration, since it is possible to detect the operation of the steering wheel with the intermediate shaft removed from the steering device, the correspondence between the actual turning angle of the steered wheels and the rotation angle information An abnormal situation in which a deviation occurs can be detected.

  Further, when the steering wheel is operated with the intermediate shaft removed from the steering device, the steering angle changes, but the axial displacement of the rack shaft does not change. Paying attention to this point, when the rotation angle information related to the steering angle of the steering wheel changes, if the axial displacement of the rack shaft does not change, the intermediate shaft is removed from the steering device. It is also possible to determine that the steering wheel has been operated.

  Therefore, in order to solve the above problems, in the steering device, a displacement sensor that detects the amount of displacement of the rack shaft of the vehicle in the axial direction, a rotation angle detection device that detects rotation angle information related to the steering angle of the steering wheel, When a change in the rotation angle information detected by the rotation angle detection device is detected, an abnormality is detected based on the amount of axial displacement of the rack shaft detected by the displacement sensor being less than the threshold value. And an abnormality detection unit.

  Even in this configuration, since the operation of the steering wheel with the intermediate shaft removed from the steering device can be detected, the correspondence between the actual turning angle and the rotation angle information of the steered wheels is not shifted. The abnormal situation that occurs can be detected.

  It should be noted that a situation where the steering wheel is operated with the intermediate shaft removed from the steering device is likely to occur when the ignition switch is turned off, such as during vehicle maintenance.

Therefore, in the steering apparatus, it is preferable that the abnormality detection unit detects the abnormality only during a period in which the ignition switch of the vehicle is off.
In the steering apparatus, it is preferable that the rotation angle detection device intermittently detects the rotation angle information while a vehicle ignition switch is turned off.

According to this configuration, it is possible to reduce power consumption while the ignition switch is turned off.
In the steering apparatus, it is preferable that the rotation angle detection device switches to a state in which the rotation angle information is constantly detected when a change in the rotation angle information is detected while the ignition switch is turned off.

According to this configuration, when the steering angle starts to change, the rotation angle detection device is switched to a state in which the rotation angle information is always detected, so that a change in the rotation angle information can be detected with higher accuracy.
In the steering device, the rotation angle detection device intermittently detects the rotation angle information when the rotation angle information remains unchanged for a predetermined time while the rotation angle information is constantly detected. It is preferable to switch to the state to do.

According to this configuration, when the steering angle stops changing, the rotation angle detection device returns to a state in which the rotation angle information is intermittently detected, so that power consumption can be reduced.
In the steering apparatus, the torque sensor stops when the ignition switch of the vehicle is turned off, and detects a change in the steering torque when the change of the rotation angle information is detected while the ignition switch is turned off. It is preferable to switch to a state in which detection is performed.

  According to this configuration, since the torque sensor is stopped when the ignition switch is turned off, power consumption can be reduced. Also, if the rotation angle information changes while the ignition switch is off, the torque sensor starts detecting the steering torque, so the correspondence between the actual turning angle of the steered wheels and the rotation angle information It is possible to detect an abnormal situation in which the relationship is shifted.

  A motor that applies power to a column shaft of the vehicle; a rotation angle detection device that detects a rotation angle of the motor; and a drive of the motor is controlled based on the rotation angle of the motor detected by the rotation angle detection device. In the electric power steering device including the control device, the rotation angle detection device is preferably used as the rotation angle detection device.

  According to this configuration, by using the rotation angle detection device provided in the electric power steering device, an abnormal situation in which the correspondence between the actual turning angle of the steered wheels and the rotation angle information is shifted is detected. can do. That is, since it is not necessary to separately provide a rotation angle detection device for detecting rotation angle information related to the steering angle for abnormality detection, the structure can be simplified.

  According to the present invention, it is possible to detect an abnormal situation in which the correspondence between the rotation angle information detected by the rotation angle detection device and the actual turning angle of the steered wheels is shifted.

The block diagram which shows the schematic structure about one Embodiment of an electric power steering apparatus. The block diagram which shows the structure of the control apparatus about the electric power steering apparatus of embodiment. The block diagram which shows the structure of the rotation angle detection apparatus about the electric power steering apparatus of embodiment. The block diagram which shows schematic structure in the state from which the intermediate shaft was removed about the electric power steering apparatus of embodiment. The flowchart which shows the procedure of the process performed by the abnormality detection part about the electric power steering apparatus of embodiment. The flowchart which shows the procedure of the process performed by the abnormality detection part about the modification of an electric power steering device.

Hereinafter, an embodiment of an electric power steering apparatus (EPS) will be described.
As shown in FIG. 1, the EPS 1 of the present embodiment includes a steering mechanism 10 that steers steered wheels 16 based on a driver's operation of a steering wheel 11, and an assist mechanism that applies assist force to the steering mechanism 10 by a motor 21. 20.

  The steering mechanism 10 includes a steering shaft 12 connected to a steering wheel 11. The steering shaft 12 has a configuration in which a column shaft 12a, an intermediate shaft 12b, and a pinion shaft 12c are sequentially connected from the steering wheel 11 side. A lower end portion of the pinion shaft 12 c is connected to the rack shaft 14 via a rack and pinion mechanism 13. In the steering mechanism 10, when the steering shaft 12 rotates as the driver rotates the steering wheel 11, the rotational motion is converted into a reciprocating linear motion in the axial direction of the rack shaft 14 via the rack and pinion mechanism 13. The reciprocating linear motion of the rack shaft 14 in the axial direction is transmitted to the steered wheels 16 via the tie rods 15 connected to both ends thereof, thereby changing the steered angle θt of the steered wheels 16 and changing the traveling direction of the vehicle. Is done.

  The assist mechanism 20 includes a motor 21, a speed reducer 22 that decelerates rotation of the output shaft 21 a of the motor 21 and transmits it to the column shaft 12 a, and a control device 23 that controls driving of the motor 21. The motor 21 is a brushless motor. The assist mechanism 20 applies assist force (assist torque) to the steering shaft 12 by transmitting the rotation of the output shaft 21 a of the motor 21 to the steering shaft 12 via the speed reducer 22.

  The EPS 1 is provided with various sensors that detect the state amount of the vehicle and the operation amount of the driver. For example, the steering shaft 12 is provided with a torque sensor 30 that detects a steering torque Th applied to the steering shaft 12 when the driver performs a steering operation. The vehicle is provided with a vehicle speed sensor 31 that detects its traveling speed V. Outputs of these sensors 30 and 31 are taken into the control device 23. The control device 23 executes assist control for applying assist force to the steering shaft 12 by PWM (pulse width modulation) control of the motor 21 based on the steering torque Th and the vehicle speed V detected by the sensors 30 and 31.

  As shown in FIG. 2, the control device 23 includes a microcomputer 40, a memory 41, a drive circuit 42, a current sensor 43, and a rotation angle detection device 44. In the following, the microcomputer 40 is abbreviated as “microcomputer 40”.

  The drive circuit 42 is configured around a known inverter circuit that converts DC power supplied from a power source such as an in-vehicle battery into three-phase (U-phase, V-phase, W-phase) AC power. The drive circuit 42 drives the motor 21 by supplying three-phase AC power to each phase coil of the motor 21 via each phase power supply line WL. In FIG. 2, for convenience, the power supply lines WL of each phase are collectively shown.

The current sensor 43 is provided on the power supply line WL of each phase, and detects each phase current value I supplied to the motor 21. In FIG. 2, for convenience, the current sensors 43 of the respective phases are collectively shown.
The rotation angle detection device 44 detects the rotation angle θe of the output shaft 21 a of the motor 21. The motor rotation angle θe is an electrical angle and is a relative angle represented in the range of “0 ° ≦ θ <360 °”.

  The microcomputer 40 takes in outputs of the torque sensor 30, the vehicle speed sensor 31, the current sensor 43, and the rotation angle detection device 44. The microcomputer 40 performs PWM (pulse width modulation) control of driving of the motor 21 based on the steering torque Th, the vehicle speed V, the phase current value I, and the motor rotation angle θe detected by them. Specifically, the microcomputer 40 calculates the q-axis current command value based on the steering torque Th and the vehicle speed V, and sets the d-axis current command value to zero. The d-axis current command value and the q-axis current command value indicate target values for the supply current of the motor 21 in the d / q coordinate system. Further, the microcomputer 40 calculates the d-axis current value and the q-axis current value by mapping each phase current value I to the d / q coordinate system using the motor rotation angle θe. The d-axis current value and the q-axis current value indicate the actual current value of the motor 21 in the d / q coordinate system. The microcomputer 40 executes current feedback control based on the deviations so that the d-axis current value follows the d-axis current command value and the q-axis current value follows the q-axis current command value. The d-axis voltage command value and the q-axis voltage command value are calculated. Then, the microcomputer 40 converts the d-axis voltage command value and the q-axis voltage command value into each phase voltage command value using the motor rotation angle θe, and generates a drive signal (PWM signal) Sc based on each phase voltage command value. By outputting to the drive circuit 42, the drive circuit 42 is driven. The motor 21 is PWM-controlled based on the drive of the drive circuit 42, and assist control for applying assist force to the column shaft 12a is executed.

  The microcomputer 40 is communicably connected to another in-vehicle control device 3 via an in-vehicle network 2 such as a CAN (Controller Area Network). The other vehicle-mounted control device 3 is, for example, a brake control device that performs vehicle brake control, a vehicle stability control device that performs vehicle skid prevention control, or the like. In EPS1, since the output shaft 21a of the motor 21 is connected to the column shaft 12a via the speed reducer 22, there is a correlation between the motor rotation angle θe and the steering angle θs. The microcomputer 40 calculates the steering angle θs based on the motor rotation angle θe by using this correlation. Note that the steering angle θs is an absolute angle representing the rotation angle (mechanical angle) of the steering wheel 11 in a range exceeding 360 °. The microcomputer 40 not only uses the calculated information of the steering angle θs by itself, but also transmits it to the other in-vehicle control device 3 through the in-vehicle network 2. Thereby, the other vehicle-mounted control apparatus 3 can perform various control using the steering angle (theta) s transmitted from EPS1, even if it does not have the sensor for detecting the steering angle (theta) s itself.

Next, the configuration of the rotation angle detection device 44 will be described in detail.
As shown in FIG. 3, the rotation angle detection device 44 includes a magnet rotor 50, a rotation angle sensor 51, an ASIC 52, and a communication interface (I / F) 53.

  The magnet rotor 50 is integrally assembled with the output shaft 21 a of the motor 21 and applies a bias magnetic field to the rotation angle sensor 51. Therefore, the direction of the bias magnetic field applied to the rotation angle sensor 51 changes according to the change in the motor rotation angle θe.

  The rotation angle sensor 51 is composed of an MR sensor composed of a magnetoresistive effect element. That is, the rotation angle sensor 51 outputs a voltage signal corresponding to the direction of the bias magnetic field applied by the magnet rotor 50, in other words, the motor rotation angle θe. The rotation angle sensor 51 outputs, as voltage signals, a sine signal Ssin that changes in a sine wave shape according to the motor rotation angle θe and a cosine signal Scos that changes in a cosine shape according to the motor rotation angle θe.

  The ASIC 52 includes an amplifier 60, a rotation detection unit 61, an abnormality detection unit 62, and a power supply control unit 63. The ASIC 52 includes an integrated circuit in which these elements are integrated into one.

  The amplifier 60 amplifies the sine signal Ssin and the cosine signal Scos output from the rotation angle sensor 51. The amplifier 60 outputs the amplified sine signal Ssin ′ and cosine signal Scos ′ to the rotation detection unit 61.

  The rotation detector 61 detects the rotation state of the output shaft 21a of the motor 21 based on the sine signal Ssin 'and the cosine signal Scos'. Specifically, the rotation detector 61 has a counter 61a. The rotation detector 61 detects the motor rotation angle θe and its changing direction based on the sine signal Ssin ′ and the cosine signal Scos ′, and each time the motor rotation angle θe changes by a predetermined angle (for example, 90 °) in the increasing direction, Increment the value. Further, the rotation detector 61 decrements the value of the counter 61a every time the motor rotation angle θe changes by a predetermined angle in the decreasing direction. That is, the value of the counter 61a is rotation information related to the motor rotation angle θe. Further, the steering angle θs can be calculated from the value of the counter 61a by utilizing the correlation between the motor rotation angle θe and the steering angle θs. That is, the value of the counter 61a is also rotation angle information related to the steering angle θs.

  The power supply control unit 63 controls the power supply states of the rotation angle sensor 51, the amplifier 60, and the torque sensor 30. Note that elements other than the amplifier 60 in the ASIC 52 are always supplied with power. The power supply control unit 63 includes a first power switch 63a, a second power switch 63b, and a switch control unit 63c.

The first power switch 63a is a switch capable of intermittently supplying power from the in-vehicle battery B to the rotation angle sensor 51 and the amplifier 60.
The second power switch 63b is a switch capable of intermittently supplying power from the in-vehicle battery B to the torque sensor 30.

  The switch control unit 63c maintains the switches 63a and 63b in an on state while an IG (ignition) switch (not shown) of the vehicle is turned on, so that the rotation angle sensor 51, the amplifier 60, and the torque sensor 30 are turned on. Always supply power. That is, while the IG switch is on, the rotation angle sensor 51, the amplifier 60, and the torque sensor 30 are always driven. The switch controller 63c intermittently supplies power to the rotation angle sensor 51 and the amplifier 60 by intermittently turning on the first power switch 63a while the IG switch is turned off. The switch control unit 63c cuts off the power supply to the torque sensor 30 by turning off the second power switch 63b. That is, while the IG switch is turned off, the rotation angle sensor 51 and the amplifier 60 are driven intermittently, and the torque sensor 30 is stopped. Thereby, power consumption while the IG switch is turned off can be reduced. Further, the switch control unit 63c switches the switching state of the switches 63a and 63b based on an instruction from the abnormality detection unit 62 while the IG switch is turned off.

  While the IG switch is on, the microcomputer 40 takes the sine signal Ssin 'and the cosine signal Scos' from the ASIC 52 via the communication interface 53, and calculates the motor rotation angle θe based on these values. Further, the microcomputer 40 calculates the steering angle θs based on the motor rotation angle θe by using the correlation between the motor rotation angle θe and the steering angle θs.

  On the other hand, the microcomputer 40 is stopped while the IG switch is turned off. Therefore, if the steering wheel 11 is operated and the steering shaft 12 rotates while the IG switch is turned off, the microcomputer 40 cannot detect the change. Therefore, when the IG switch is subsequently turned on, the microcomputer 40 may erroneously detect the steering angle θs.

  In this regard, in the EPS 1 of the present embodiment, since the rotation angle sensor 51 and the amplifier 60 are intermittently driven while the IG switch is turned off, the sine signal Ssin ′ and the cosine signal Scos ′ are detected by the rotation detection unit 61. Taken intermittently. That is, the rotation angle detection device 44 detects the motor rotation angle θe intermittently. The rotation detection unit 61 changes the value of the counter 61a based on the sine signal Ssin 'and the cosine signal Scos' that are intermittently captured. That is, when the steering wheel 11 is operated while the IG switch is turned off, the steering angle θs changes, and when the motor rotation angle θe changes, the change is stored as a change in the value of the counter 61a. When the IG switch is turned on, the microcomputer 40 detects the steering angle θs using the value of the counter 61a.

  Specifically, the microcomputer 40 stores information on the steering angle θs detected immediately before in the memory 41 when the IG switch is turned off. Thereafter, when the IG switch is turned on, the microcomputer 40 takes in the value of the counter 61a from the rotation detector 61, and calculates the change amount of the motor rotation angle θe while the IG switch is turned off based on the value. Further, the microcomputer 40 takes in the sine signal Ssin 'and the cosine signal Scos' from the ASIC 52, and calculates the motor rotation angle θe when the IG is on based on these values. Then, the microcomputer 40 determines the IG based on the change amount of the motor rotation angle θe while the IG switch is turned off, the motor rotation angle θe when the IG is on, and the steering angle θs when the IG is off stored in the memory 41. The initial value of the steering angle θs immediately after being turned on is calculated. Thereafter, the microcomputer 40 continues to calculate the steering angle θs based on the motor rotation angle θe based on the initial value of the steering angle θs.

  By the way, for example, when the operator removes the intermediate shaft 12b from the EPS 1 as shown in FIG. 4 with the IG switch turned off during vehicle maintenance, the mechanical connection between the column shaft 12a and the pinion shaft 12c. Connection is eliminated. At this time, if the worker does not remove the in-vehicle battery B, the power supply to the rotation angle detection device 44 is still performed. Therefore, if the operator operates the steering wheel 11 to rotate the column shaft 12a and the motor rotation angle θe changes, the rotation detector 61 changes the value of the counter 61a according to the change. However, in the state where the intermediate shaft 12b is removed, the steering torque Th applied to the steering wheel 11 is not transmitted to the rack shaft 14, and therefore the turning angle θt of the steered wheels 16 does not change. Therefore, when the operator subsequently connects the intermediate shaft 12b to the column shaft 12a and the pinion shaft 12c at an arbitrary position, the correspondence between the actual turning angle θt of the steered wheels 16 and the value of the counter 61a is shifted. May occur.

  Therefore, in this embodiment, while the IG switch is turned off, the abnormality detection unit 62 of the ASIC 52 monitors whether or not the steering wheel 11 is operated with the intermediate shaft 12b removed, and such an operation is performed. Is detected as abnormal. Hereinafter, for the sake of convenience, steering of the steering wheel 11 with the intermediate shaft 12b removed is abbreviated as “abnormal steering”. First, the detection principle of abnormal steering will be described.

  When the intermediate shaft 12 b is removed from the EPS 1, the road surface reaction force applied to the tires of the vehicle is not transmitted to the steering wheel 11. That is, the steering reaction force (load) hardly acts when the steering wheel 11 is operated. Therefore, the steering wheel 11 and the column shaft 12a rotate only when the operator applies a slight steering torque Th to the steering wheel 11. Focusing on this point, it is possible to determine that abnormal steering has been performed if the steering torque Th detected by the torque sensor 30 is small when the motor rotation angle θe changes.

  Therefore, the abnormality detection unit 62 takes in the value of the counter 61a of the rotation detection unit 61 and the steering torque Th detected by the torque sensor 30 while the IG switch is turned off. Then, the abnormality detection unit 62 determines whether or not abnormal steering has been performed based on the value of the counter 61a and the steering torque Th, and turns on the abnormality detection flag 62a when abnormal steering is detected.

  Next, with reference to FIG. 5, a procedure of processing for detecting abnormal steering will be described together with an operation example of the abnormality detecting unit 62. The abnormality detection unit 62 performs the process shown in FIG. 5 when the IG switch is turned off. Further, the abnormality detection flag 62a is off in the initial state.

  As shown in FIG. 5, the abnormality detection unit 62 monitors whether or not the value of the counter 61a of the rotation detection unit 61 has changed (S1). Here, when the operator operates the steering wheel 11 after removing the intermediate shaft 12b from the EPS 1, the motor rotation angle θe changes and the value of the counter 61a changes. At this time, if the abnormality detection unit 62 detects a change in the value of the counter 61a (S1: YES), the switch control unit 63c is instructed to always turn on both the first power switch 63a and the second power switch 63b. (S2). Based on this instruction, the switch controller 63c always turns on each of the switches 63a and 63b, so that the rotation angle sensor 51 and the amplifier 60 are changed from the intermittent power supply state to the constant power supply state, and the torque sensor 30 is constantly supplied from the non-power supply state. Switch to As a result, it is possible to detect the change in the motor rotation angle θe with higher accuracy and to detect the steering torque Th. Then, the abnormality detection unit 62 takes in the output of the torque sensor 30 via the communication interface 53, and determines whether or not the steering torque Th detected by the torque sensor 30 is equal to or greater than a predetermined threshold Th1 (S3). The threshold value Th1 is set to a lower limit value of the steering torque that can rotate the steering wheel 11 when the intermediate shaft 12b is not removed when the vehicle stops, for example. Here, when the operator operates the steering wheel 11 with the intermediate shaft 12b removed from the EPS 1, the steering torque Th detected by the torque sensor is less than the threshold value Th1 (S3: NO). The detector 62 turns on the abnormality detection flag 62a (S4), and ends this process.

  On the other hand, when the operator operates the steering wheel 11 without removing the intermediate shaft 12b from the EPS 1, the steering torque Th detected by the torque sensor 30 is equal to or greater than the threshold Th1 (S3: YES). Therefore, the abnormality detection unit 62 determines whether or not a state in which the value of the counter 61a has not changed continues for a predetermined time or more (S5). Then, while the value of the counter 61a is changing (S5: NO), that is, while the motor rotation angle θe is changing, the abnormality detection unit 62 causes the steering torque Th detected by the torque sensor 30 to be greater than or equal to the threshold Th1. It is continuously monitored whether or not (S3). Thereafter, when the change of the motor rotation angle θe is stopped, that is, the rotation of the steering wheel 11 is stopped and the value of the counter 61a remains unchanged for a predetermined time or longer (S5: YES), the first power switch 63a is intermittently operated. The switch control unit 63c is notified of an instruction to turn on automatically and an instruction to turn off the second power switch 63b (S6). Based on this instruction, the switch controller 63c intermittently turns on the first power switch 63a and turns off the second power switch 63b, so that the rotation angle sensor 51 and the amplifier 60 are in the intermittent power supply state, and the torque sensor 30. Returns to the non-powered state. That is, when the steering wheel 11 once rotates and then stops rotating, the rotation angle sensor 51 and the amplifier 60 are intermittently driven and the torque sensor 30 returns to the stopped state. Can be reduced. Thereafter, the abnormality detection unit 62 returns to the state of monitoring whether or not the value of the counter 61a of the rotation detection unit 61 has changed (S1). That is, the abnormality detection unit 62 returns to the state where the change in the motor rotation angle θe is monitored.

  The microcomputer 40 takes in the abnormality detection flag 62 a of the abnormality detection unit 62 via the communication interface 53 when the IG switch is turned on. When the abnormality detection flag 62a is in the on state, the microcomputer 40 determines that the correspondence between the actual turning angle θt of the steered wheels 16 and the value of the counter 61a has shifted, and is provided to the vehicle. The driver is notified of the abnormality through the device. By this notification, the driver can recognize an abnormal situation in which the correspondence relationship between the actual turning angle θt of the steered wheels 16 and the steering angle θs detected by the rotation angle detection device 44 is shifted. Therefore, it is possible to take appropriate measures such as bringing the vehicle into a dealer.

According to EPS1 of this embodiment demonstrated above, the following effects can be acquired.
(1) Abnormal steering can be detected by the abnormality detection unit 62 executing the process shown in FIG. As a result, it is possible to detect an abnormal situation in which a deviation occurs in the correspondence between the actual turning angle θt of the steered wheels 16 and the value of the counter 61a.

  (2) The rotation angle detection device 44 intermittently supplies the rotation angle sensor 51 and the amplifier 60 while the IG switch is turned off, thereby intermittently detecting the motor rotation angle θe. did. Thereby, power consumption can be reduced.

  (3) When the rotation angle detection device 44 detects a change in rotation angle information while the IG switch is turned off, the rotation angle detection device 44 is in a state where power is always supplied to the rotation angle sensor 51 and the amplifier 60, in other words, the motor. The rotation angle θe is switched to a state where it can be detected at all times. Thereby, when the steering wheel 11 is operated, each change of the motor rotation angle θe and the steering angle θs can be detected with higher accuracy.

  (4) The rotation angle detection device 44 detects the motor rotation angle θe intermittently when the motor rotation angle θe remains unchanged for a predetermined time while the motor rotation angle θe is constantly detected. I decided to return to Thereby, power consumption can be reduced.

  (5) The torque sensor 30 is stopped when the IG switch is turned off. Thereby, power consumption can be reduced. In addition, when the value of the counter 61a changes while the IG switch is turned off, the torque sensor 30 is switched to a state in which the steering torque Th can be detected by supplying power to the torque sensor 30. As a result, when the steering angle θs changes while the IG switch is turned off, the torque sensor 30 starts detecting the steering torque Th, so that the abnormal steering is detected, in other words, the actual of the steered wheels 16. It is possible to detect an abnormal situation in which a deviation occurs in the correspondence between the turning angle θt and the value of the counter 61a.

  (6) The motor rotation angle θe detected by the rotation angle detection device 44 is used as rotation angle information related to the steering angle θs. As a result, the steering angle θs can be detected without separately providing a steering angle sensor for detecting the steering angle θs.

In addition, the said embodiment can also be implemented with the following forms.
-The structure of the said embodiment can also detect the following abnormal situations. For example, when both front wheels of a vehicle are lifted from the ground during vehicle maintenance, road reaction force does not act on the tires of the front wheels. Therefore, since the steering reaction force (load) hardly acts when the steering wheel 11 is operated, the steering shaft 12 rotates at a high speed. Here, when the rotation speed of the steering shaft 12 is increased, the rotation angle detection device 44 cannot accurately detect the change in the motor rotation angle θe because of the intermittent detection of the motor rotation angle θe. Therefore, there is a possibility that a deviation occurs in the correspondence between the value of the counter 61a and the actual motor rotation angle θe. This becomes a factor causing a shift in the correspondence relationship between the steering angle θs calculated by the microcomputer 40 based on the value of the counter 61a and the actual turning angle θt. In this regard, in a state where both the front wheels of the vehicle are floating from the ground, the steering wheel 11 and the steering shaft 12 rotate only by the operator applying a slight steering torque Th to the steering wheel 11. Therefore, when the steering angle Th detected by the torque sensor 30 is small when the motor rotation angle θe is changed, it can be determined that the front wheel is in an abnormal state where both floats. Therefore, when the abnormality detection unit 62 executes the process shown in FIG. 5, an abnormal situation in which both front wheels float, that is, the correspondence between the actual turning angle θt of the steered wheels 16 and the value of the counter 61a. It is possible to detect an abnormal situation in which an error occurs.

  As shown in FIG. 4, when the steering wheel 11 is operated with the intermediate shaft 12b removed from the EPS 1, the steering angle θs changes, but the amount of axial displacement of the rack shaft 14 does not change. If attention is paid to this point, it can be determined that the abnormal steering is similarly performed when the rack shaft 14 does not change in the axial direction when the motor rotation angle θe changes. Therefore, the following configuration may be adopted. First, as shown in FIG. 4, a displacement sensor 32 that detects the amount of displacement of the rack shaft 14 in the axial direction is provided in the EPS 1. Moreover, the abnormality detection part 62 performs the process shown in FIG. In the process shown in FIG. 6, the same processes as those shown in FIG. As shown in FIG. 6, following the process of S2, the abnormality detection unit 62 determines whether the displacement amount of the rack shaft 14 detected by the displacement sensor 32 is equal to or greater than a predetermined threshold Th2 (S7). . The threshold value Th2 is set, for example, as a lower limit value of the axial displacement amount of the rack shaft 14 detected by the displacement sensor 32 when the value of the counter 61a changes when the intermediate shaft 12b is not removed. When the displacement amount of the rack shaft 14 is less than the threshold Th2 (S7: NO), the abnormality detection unit 62 determines that the rack shaft 14 is not displaced in the axial direction, and turns on the abnormality detection flag 62a (S4). . In addition, when the amount of displacement of the rack shaft 14 is equal to or greater than the threshold Th2 (S7: YES), the abnormality detection unit 62 performs the process of S5. Even in such a configuration, abnormal steering can be detected in the same manner as in the above-described embodiment. Therefore, an abnormal situation in which a deviation occurs in the correspondence between the actual turning angle θt of the steered wheels 16 and the value of the counter 61a. Can be detected. As the displacement sensor 32, a sensor that detects a physical quantity correlated with the axial displacement of the rack shaft 14, for example, a turning angle sensor that detects the turning angle θt of the steered wheels 16 may be used. .

  -While the IG switch is turned off, power may be constantly supplied to the rotation angle sensor 51, the amplifier 60, and the torque sensor 30. That is, while the IG switch is off, the rotation angle detection device 44 may constantly detect the motor rotation angle θe, and the torque sensor 30 may always detect the steering torque Th. If this configuration is adopted, the power supply control unit 63 can be excluded from the ASIC 52, and thus the structure of the ASIC 52 can be simplified. In addition, since the processes of S2 and S6 can be eliminated from the process shown in FIG. 5, the processing load on the abnormality detection unit 62 can be reduced.

  In the case where it is not necessary to amplify the sine signal Ssin and the cosine signal Scos output from the rotation angle sensor 51, the amplifier 60 may be excluded from the ASIC 52. In this case, the rotation detection unit 61 and the microcomputer 40 perform various calculations using the sine signal Ssin and the cosine signal Scos output from the rotation angle sensor 51.

The abnormality detection unit 62 may execute the processing shown in FIG. 5 not only while the IG switch is turned off, but for example while the IG switch is on and the vehicle is stopped.
The rotation angle detection device 44 of the above embodiment detects and stores the steering angle θs based on the value of the counter 61a, but the detection method and storage method of the steering angle θs can be changed as appropriate. For example, the rotation detector 61 may calculate the steering angle θs based on the sine signal Ssin ′ and the cosine signal Scos ′ while the IG switch is turned off, and hold the calculation result.

The rotation angle sensor 51 is not limited to the MR sensor, and may be, for example, a hall sensor or a rotary encoder.
The abnormality detection unit 62 may be provided in a device other than the rotation angle detection device 44.

  The configuration of the rotation angle detection device 44 of the above embodiment is also applicable to a rotation angle detection device that directly detects the rotation angle of the column shaft 12a, in other words, a rotation angle detection device that directly detects the steering angle θs. In short, the rotation angle detection device only needs to detect rotation angle information related to the steering angle θs.

  -The structure of the said embodiment is applicable not only to EPS but to an appropriate steering device.

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus (EPS), 11 ... Steering wheel, 12a ... Column shaft, 14 ... Rack shaft, 21 ... Motor, 23 ... Control apparatus, 30 ... Torque sensor, 32 ... Displacement sensor, 44 ... Rotation angle detection apparatus 62: Abnormality detection unit.

Claims (8)

A torque sensor provided on the column shaft of the vehicle for detecting steering torque;
A rotation angle detection device for detecting rotation angle information related to the steering angle of the steering wheel;
When a change in the rotation angle information detected by the rotation angle detection device is detected, the steering torque detected by the torque sensor is a mechanical connection between the column shaft and the pinion shaft connected to the column shaft. An anomaly detection unit that detects an anomaly based on being less than a threshold indicating cancellation;
A steering apparatus comprising: A displacement sensor for detecting the axial displacement of the rack shaft of the vehicle;
A rotation angle detection device for detecting rotation angle information related to the steering angle of the steering wheel;
When a change in the rotation angle information detected by the rotation angle detection device is detected, an abnormality is detected based on the amount of axial displacement of the rack shaft detected by the displacement sensor being less than the threshold value. An anomaly detector;
A steering apparatus comprising: The steering apparatus according to claim 1, wherein the abnormality detection unit detects the abnormality only during a period in which an ignition switch of the vehicle is off. The steering device according to any one of claims 1 to 3, wherein the rotation angle detection device intermittently detects the rotation angle information while an ignition switch of a vehicle is turned off. The steering device according to claim 4, wherein the rotation angle detection device switches to a state in which the rotation angle information is always detected when a change in the rotation angle information is detected while the ignition switch is turned off. The rotation angle detection device switches to a state in which the rotation angle information is intermittently detected when a state in which the rotation angle information does not change continues for a predetermined time while the rotation angle information is constantly detected. Item 6. The steering device according to Item 5. The torque sensor stops when the ignition switch of the vehicle is turned off, and detects the steering torque when the change of the rotation angle information is detected while the ignition switch is turned off. The steering apparatus according to claim 1, wherein the steering apparatus is switched. A motor for applying power to the column shaft of the vehicle;
A rotation angle detection device for detecting the rotation angle of the motor;
An electric power steering apparatus comprising: a control device that controls driving of the motor based on a rotation angle of the motor detected by the rotation angle detection device;
The electric power steering device according to any one of claims 1 to 7, wherein the rotation angle detection device according to any one of claims 1 to 7 is used as the rotation angle detection device.