JP5331717B2 - Failure diagnosis device, rotation angle detection device, and failure diagnosis method - Google Patents

Description

  The present invention relates to a failure diagnosis device, a rotation angle detection device, and a failure diagnosis method for diagnosing a failure of a detection device.

Conventionally, an apparatus for detecting the rotation angle of a rotating body that can rotate over 360 degrees has been proposed.
For example, Patent Document 1 describes a rotation angle detection device configured as follows. That is, the rotatable rotating body has a gear having n teeth. This gear is engaged with a gear having m teeth and two gears having m + 1 teeth. The angles ψ and θ of these two gears are measured using two periodic angle sensors. This measurement is performed in a contact or non-contact manner. Each of these angle sensors is connected to an electronic evaluation circuit, and this evaluation circuit performs a calculation necessary for detecting the rotation angle φ of the rotating body. In the rotation angle detection device configured as described above, the two angle sensors, which are so-called absolute value sensors, supply the rotation angles ψ and θ of the two gears at the time of switch-on immediately after the rotation angle detection device is switched on. . The angle φ of the rotating body is detected from these angle values, the angle marks or the number of teeth of the gears of the rotating body, and the angle marks or the number of teeth of the two gears.

Japanese Patent No. 3792718

  When the rotation angle detection device is configured to calculate the rotation angle of the rotating body by the electronic control unit (ECU) based on the rotation angle data of the two gears transmitted from the angle sensor, the two gears, the angle The electronic control unit needs to detect the failure of the sensor, the harness, the interface circuit on the ECU side, and the like. It is desirable to perform this failure detection without providing a separate circuit dedicated to failure detection.

  For this purpose, the present invention provides a first detection means for detecting the rotation angle of the first follower that rotates in conjunction with the rotation of the rotating body, and a first detector that rotates in conjunction with the rotation of the rotating body. Second detection means for detecting the rotation angle of the second follower, the rotation angle of the first follower detected by the first detection means, and the second follower detected by the second detection means. A failure diagnosis device for diagnosing a failure of a detection device for detecting a rotation angle of the rotating body, comprising: a calculation means for calculating the rotation angle of the rotating body based on an angle difference with the rotation angle of the body, Based on the rotation angle of the first follower detected by the first detection means and the rotation angle of the second follower detected by the second detection means, the rotation angle of the first follower Zero for calculating the zero rotation angle at which the angle difference with the rotation angle of the second follower is zero And the rolling angle calculating means, the zero rotation angle calculating means is a failure diagnosis apparatus, wherein a and a fault diagnosis means for diagnosing a failure of the detection device based on a zero rotation angle computed.

Here, the zero rotation angle calculation means includes the rotation angle of the first follower calculated backward from the rotation angle of the rotation body, and the rotation angle of the first follower detected by the first detection means. It is preferable to calculate the zero rotation angle based on
In addition, the zero rotation angle calculation means may calculate the rotation angle of the second follower calculated backward from the rotation angle of the rotation body and the rotation angle of the second follower detected by the second detection means. It is preferable to calculate the zero rotation angle based on this.
Further, the failure diagnosis means determines that a failure has occurred in the detection device when a state in which the zero rotation angle calculated by the zero rotation angle calculation means is outside the allowable range continues for a predetermined period. Is preferred.

  From another point of view, the present invention is a rotation angle detection device that detects a rotation angle of a rotating body, and detects a rotation angle of a first follower that rotates in conjunction with the rotation of the rotating body. 1 detection means, second detection means for detecting a rotation angle of a second follower rotating in conjunction with rotation of the rotary body, and the first follower detected by the first detection means Calculating means for calculating the rotation angle of the rotating body based on the angle difference between the rotation angle of the rotating body and the rotation angle of the second follower detected by the second detecting means, and detecting by the first detecting means Based on the rotation angle of the first follower and the rotation angle of the second follower detected by the second detection means, the rotation angle of the first follower and the second follower A zero rotation angle calculating means for calculating a zero rotation angle at which the angle difference with respect to the rotation angle is zero, Zero rotation angle calculating means is a rotation angle detection device, wherein a and a fault diagnosis means for diagnosing a fault based on the zero rotation angle computed.

Here, the zero rotation angle calculation means includes the rotation angle of the first follower calculated backward from the rotation angle of the rotation body calculated by the calculation means, and the first detection means detected by the first detection means. It is preferable to calculate the zero rotation angle based on the rotation angle of the driven body.
Further, the zero rotation angle calculation means includes the rotation angle of the second follower calculated backward from the rotation angle of the rotation body calculated by the calculation means, and the second follower detected by the second detection means. It is preferable to calculate the zero rotation angle based on the rotation angle of the body.

Further, it is preferable that the failure diagnosis unit determines that a failure has occurred when a state in which the zero rotation angle calculated by the zero rotation angle calculation unit is out of an allowable range continues for a predetermined period. .
The rotating body includes a gear, the first driven body includes a first driven gear, and the second driven body has a number of teeth different from the number of teeth of the first driven gear. The first driven body and the second driven body have a second driven gear, and the first driven gear and the second driven gear are applied with a rotational force by the gear. It is preferable to rotate in conjunction with the rotation of the rotating body.

  From another point of view, the present invention relates to first detection means for detecting the rotation angle of the first follower that rotates in conjunction with the rotation of the rotating body, and in conjunction with the rotation of the rotating body. A second detection means for detecting a rotation angle of the second driven body that rotates; a rotation angle of the first follower detected by the first detection means; and the second detection means detected by the second detection means. A failure diagnosis method for diagnosing a failure of a detection device for detecting a rotation angle of the rotating body, comprising: a calculation means for calculating the rotation angle of the rotating body based on an angle difference with the rotation angle of the second driven body. , Based on the rotation angle of the first follower detected by the first detection means and the rotation angle of the second follower detected by the second detection means. The zero rotation angle at which the angle difference between the rotation angle and the rotation angle of the second follower is zero is Calculated to a fault diagnosis method characterized by diagnosing faults of the detecting device based on zero rotation angle computed.

Here, the zero rotation angle is calculated based on the rotation angle of the first driven body calculated backward from the rotation angle of the rotating body and the rotation angle of the first driven body detected by the first detection means. It is preferable to calculate.
Further, the zero rotation angle is calculated based on the rotation angle of the second driven body calculated backward from the rotation angle of the rotating body and the rotation angle of the second driven body detected by the second detection means. It is preferable to do.

  According to the present invention, failure detection can be performed without separately providing a circuit dedicated to failure detection.

It is sectional drawing of the electric power steering device to which the detection apparatus which concerns on embodiment is applied. It is a perspective view of the detection apparatus which concerns on embodiment. It is a figure which shows the relationship between the rotation angle of a 2nd rotating shaft, and the rotation angle of a 2nd gearwheel and a 3rd gearwheel. It is a flowchart which shows the procedure of the rotation angle calculation process of the 2nd rotating shaft which ECU performs. It is the figure which illustrated the relationship between the rotation angle of a 2nd gearwheel, and the rotation angle of a 3rd gearwheel. The relationship between the rotation angle of the second gear and the rotation angle of the third gear when assembled with the rotation angle of the second gear advanced by 20 degrees relative to the rotation angle of the third gear. FIG. The rotation angle of the second rotation shaft, the second gear, and the third gear when the rotation angle of the second gear is assembled with the rotation angle of 20 degrees relative to the rotation angle of the third gear. It is a figure which shows the relationship with the rotation angle. It is a figure which shows the rotation angle of a 2nd gearwheel when the crossing angle is 120 degree | times, and the cumulative rotation angle of a 2nd gearwheel. It is a flowchart which shows the procedure of the failure diagnosis process which ECU performs. It is a flowchart which shows the other procedure of the failure diagnosis process which ECU performs.

DETAILED DESCRIPTION Hereinafter, embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of an electric power steering device 100 to which a detection device 1 according to an embodiment is applied. FIG. 2 is a perspective view of the detection apparatus 1 according to the embodiment. In FIG. 2, a flat cable cover 50 and a part of the base 60 which will be described later are omitted for easy understanding of the configuration.

The detection device 1 detects a relative angle between the first rotating shaft 120 rotatably supported by the housing 110 and the second rotating shaft 130 as an example of a rotating body that is also rotatably supported by the housing 110. And a device for detecting the rotation angle of the second rotation shaft 130.
The housing 110 is a member that is fixed to a body frame (hereinafter also referred to as “vehicle body”) of a vehicle such as an automobile, and the first housing 111 and the second housing 112 are coupled by, for example, a bolt or the like. Configured.
The first rotating shaft 120 is a rotating shaft to which, for example, a steering wheel is connected, and is rotatably supported by the first housing 111 via a bearing 113.

The second rotating shaft 130 is coaxially coupled to the first rotating shaft 120 via a torsion bar 140 and is rotatably supported by the second housing 112 via a bearing 114. A pinion 131 formed on the second rotating shaft 130 meshes with a rack (not shown) of a rack shaft (not shown) connected to the wheel. Then, the rotary motion of the second rotary shaft 130 is converted into linear motion of the rack shaft through the pinion 131 and the rack, and the wheels are steered.
A worm wheel 150 is fixed to the second rotating shaft 130 by, for example, press fitting. The worm wheel 150 meshes with a worm gear 161 connected to the output shaft of the electric motor 160 fixed to the second housing 112.

  The electric power steering device 100 configured as described above detects the steering torque applied to the steering wheel by the detection device 1, drives the electric motor 160 based on the detected torque, and generates torque generated by the electric motor 160. Is transmitted to the second rotating shaft 130 via the worm gear 161 and the worm wheel 150. Thereby, the torque generated by the electric motor 160 assists the driver's steering force applied to the steering wheel.

Below, the detection apparatus 1 is explained in full detail.
The detection device 1 includes a first magnet 10 attached to the first rotating shaft 120 and a first gear 20 fixed to the housing 110. In addition, the detecting device 1 is a first driven gear that rotates with the first gear 20 engaged with the first gear 20 while revolving around the axis of the second rotating shaft 130 as the second rotating shaft 130 rotates. It has the 2nd gearwheel 30 as an example. Further, as the second rotation shaft 130 rotates, the detection device 1 rotates while meshing with the first gear 20 while revolving around the axis of the second rotation shaft 130 as the rotation center, and the second gear 30. The third gear 40 has a number of teeth different from the number of teeth. The third gear 40 is an example of a second driven gear.

The first magnet 10 has a donut shape, and the first rotating shaft 120 is fitted inside the first magnet 10 and rotates together with the first rotating shaft 120. N poles and S poles are alternately arranged at least on the outer peripheral surface.
The first gear 20 is a gear provided on the entire inner peripheral surface of the upper portion of the flat cable cover 50. The flat gear cover 50 is fixed to the second housing 112 of the housing 110, so that the first gear 20 is fixed to the housing 110.

  As an aspect for fixing the flat cable cover 50 to the housing 110, the following aspects can be exemplified. That is, on the outer peripheral surface of the flat cable cover 50, a plurality of convex portions 50a (four in this embodiment at intervals of 90 degrees) are formed to extend outward at equal intervals in the circumferential direction. On the other hand, the same number of concave portions 112a as the convex portions 50a are formed in the second housing 112 of the housing 110 in which the convex portions 50a are fitted. Then, the convex portion 50 a of the flat cable cover 50 is fitted into the concave portion 112 a formed in the second housing 112, thereby positioning the second rotary shaft 130 in the rotational direction. Then, the second rotating shaft 130 is positioned in the axial direction by pressing the upper surface of the flat cable cover 50 with the first housing 111.

The detection device 1 has a base 60 that is fixed to the second rotating shaft 130 and rotates together with the second rotating shaft 130. The second gear 30 and the third gear 40 are rotatably supported by the base 60. In other words, the second gear 30 and the third gear 40 are provided to be rotatable about the axis of the second rotating shaft 130 with respect to the flat cable cover 50 fixed to the housing 110. .
A cylindrical second magnet 30a having a semi-cylindrical N pole and a semi-cylindrical S pole is mounted inside the second gear 30 by insert molding, for example. A third cylindrical magnet 40a having a semi-cylindrical N-pole and a semi-cylindrical S-pole is mounted inside the third gear 40 by insert molding, for example. The second gear 30 and the second magnet 30a constitute an example of a first follower, and the third gear 40 and the third magnet 40a constitute an example of a second follower.

  Examples of the aspect in which the second gear 30 is rotatably supported on the base 60 include the following aspects. As shown in FIG. 1, a cylindrical recess 60a is provided in the base 60, and a bearing 61 is mounted in the recess 60a. On the other hand, a cylindrical protrusion 30 b is provided on the lower surface of the second gear 30. Then, the convex portion 30 b of the second gear 30 is fitted to the inner peripheral surface of the bearing 61. Alternatively, a non-magnetic rotating shaft is provided at the center of rotation of the second gear 30, that is, at the center of the second magnet 30 a, and this rotating shaft is fitted to a bearing (for example, a bearing) provided on the base 60. May be. The third gear 40 is also rotatably supported on the base 60 in the manner described above.

A printed circuit board 70 on which a wiring pattern (not shown) is formed is attached to the base 60 by, for example, screwing so as to form a predetermined gap between the second gear 30 and the third gear 40. Has been. In other words, the printed circuit board 70 is provided so as to be rotatable about the axis of the second rotating shaft 130 with respect to the flat cable cover 50 fixed to the housing 110.
As shown in FIGS. 1 and 2, the printed circuit board 70 is located outside the outer peripheral surface of the first magnet 10 in the radial direction of the first rotating shaft 120 and in the axial direction of the first rotating shaft 120. A relative angle sensor 71 is mounted so as to be within the region where the first magnet 10 is provided. The relative angle sensor 71 according to the present embodiment can be exemplified as an MR sensor (magnetoresistive element) that is a magnetic sensor utilizing the fact that the resistance value changes due to a magnetic field. The relative angle sensor 71 constitutes a relative angle detector that detects the relative angle between the first rotating shaft 120 and the second rotating shaft 130 based on the magnetic field generated from the first magnet 10.

  The printed circuit board 70 includes a first detection unit as an example of a first detection unit so as to form a predetermined gap with the second magnet 30a at a position facing the center of the second magnet 30a. The rotation angle sensor 72 is mounted. Further, the printed circuit board 70 includes a second detection unit as an example of a second detection unit so as to form a predetermined gap with the third magnet 40a at a position facing the center of the third magnet 40a. The rotation angle sensor 73 is attached. It can be exemplified that the first and second rotation angle sensors 72 and 73 according to the present embodiment are also MR sensors (magnetoresistive elements). The first and second rotation angle sensors 72 and 73 detect the rotation angle of the second rotation shaft 130 based on the rotation angle of the second gear 30 and the rotation angle of the third gear 40. The rotation angle detecting means is configured.

  In addition, a connector 74 electrically connected to the wiring pattern is attached to the printed circuit board 70, and a connector (not shown) provided at one end of the flat cable 80 is connected to the connector 74. Has been. As shown in FIG. 2, the flat cable 80 is wound in a spiral shape below the base 60 and inside the flat cable cover 50. One end of the flat cable 80 is connected to a connector 74 above the base 60 through a hole formed in the base 60. Further, the other end portion of the flat cable 80 is led out from the inside of the flat cable cover 50 through a hole formed in the flat cable cover 50, and outside the flat cable cover 50, for example, the electric power steering device 100. It is connected to a connector (not shown) provided on a printed circuit board (control board) of an electronic control unit (ECU) (not shown) that performs the above control.

  In addition, the detection device 1 includes relative angle calculation means (not shown) that calculates the relative angle between the first rotation shaft 120 and the second rotation shaft 130 based on the detection value of the relative angle sensor 71, Rotation angle calculation means (not shown) that calculates the rotation angle of the second rotation shaft 130 based on detection values of the second rotation angle sensors 72 and 73 is provided. The relative angle calculation means constitutes the above-mentioned relative angle detection means, and the rotation angle calculation means constitutes the above-mentioned rotation angle detection means. These calculation means may be mounted on a printed circuit board provided outside the flat cable cover 50 separately from the printed circuit board 70 (for example, a circuit board provided in the ECU described above) or mounted on the printed circuit board 70. May be.

  When the calculation means is mounted on a printed circuit board different from the printed circuit board 70, the detected values of the relative angle sensor 71 and the first and second rotation angle sensors 72 and 73 are sent to the calculation means via the flat cable 80. To be output. Further, when the calculation means is mounted on the printed circuit board 70, the calculation means calculates the relative angle or the rotation angle based on the detection values of the relative angle sensor 71 and the first and second rotation angle sensors 72 and 73. Later, the calculated result is output to the ECU via the flat cable 80.

Next, a mode in which the rotation angle of the second rotation shaft 130 is detected will be described in detail assuming that the rotation angle calculation means is provided in the ECU.
FIG. 3 is a diagram illustrating a relationship between the rotation angle of the second rotation shaft 130 and the rotation angles of the second gear 30 and the third gear 40.
The number of teeth of the first gear 20 is, for example, 90, the number of teeth of the second gear 30 is, for example, 36, and the number of teeth of the third gear 40 is, for example, 39. Then, considering the relationship between the number of teeth of the first gear 20 and the number of teeth of the second gear 30, the relationship between the number of teeth of the first gear 20 and the number of teeth of the third gear 40, Considering the difference between the number of teeth of the second gear 30 and the number of teeth of the third gear 40, the rotation angle of the second rotating shaft 130, the second gear 30, and the third gear as shown in FIG. The figure which shows the relationship with the rotation angle of the gear 40 of this can be obtained.

Each of the first rotation angle sensor 72 and the second rotation angle sensor 73 generates a pulse width modulation signal PWM having a duty ratio corresponding to the detected rotation angle of the second gear 30 or the third gear 40, for example. Output at a predetermined cycle.
Then, the ECU detects based on the output values from the first rotation angle sensor 72 and the second rotation angle sensor 73, in other words, the detections input by the first rotation angle sensor 72 and the second rotation angle sensor 73. Based on the result, the rotation angle of the second rotation shaft 130 is calculated.

The ECU is an arithmetic logic operation circuit including a CPU, a ROM, a RAM, a backup RAM, and the like, reads the ON pulse time of the latest pulse width modulation signal PWM captured in the capture register at a predetermined cycle, An arithmetic process for calculating the rotation angle of the second rotary shaft 130 is performed based on this time and period.
Hereinafter, the rotation angle calculation process of the second rotating shaft 130 performed by the ECU will be described using a flowchart.
FIG. 4 is a flowchart showing the procedure of the rotation angle calculation process of the second rotation shaft 130 performed by the ECU. The ECU performs the rotation angle calculation process at a predetermined cycle.

First, the ECU calculates a rotation angle θA of the second gear 30 (step 401). This is a process of calculating based on the ON time and period of the PWM signal corresponding to the latest rotation angle of the second gear 30 captured in the capture register.
Next, the ECU calculates the rotation angle θB of the third gear 40 (step 402). This is a process of calculating based on the ON time and period of the PWM signal corresponding to the latest rotation angle of the third gear 40 captured in the capture register.

Next, the ECU calculates an angle difference ΔθAB between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 (step 403). This is a process of calculating by subtracting the rotation angle θB calculated in step 402 from the rotation angle θA calculated in step 401 (ΔθAB = θA−θB).
Thereafter, the ECU determines whether or not the angle difference ΔθAB calculated in step 403 is smaller than 0 degrees (deg) (step 404). If the determination in step 404 is affirmative, the value obtained by adding 360 degrees to the angle difference ΔθAB calculated in step 403 is replaced with ΔθAB (ΔθAB ← ΔθAB + 360) (step 405), and the process proceeds to step 406. On the other hand, if a negative determination is made in step 404, the process proceeds to step 406.

In step 406, the rotation angle φ of the second rotating shaft 130 is calculated (step 406). This is a process calculated by the following equation (1).
φ = ΔθAB × K1 (1)
Here, K1 is a coefficient for converting the angle difference ΔθAB between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 into the rotation angle φ of the second rotating shaft 130. , The number of teeth of the second gear 30, the number of teeth of the third gear 40, and 360 degrees which are detection angles of the first rotation angle sensor 72 and the second rotation angle sensor 73. It is a coefficient.
In this way, the ECU calculates the rotation angle φ of the second rotation shaft 130.

Next, the first gear 20, the second gear 30, the third gear 40, the first rotation angle sensor 72, and the second rotation angle sensor 73 that constitute the detection device 1 configured as described above. A failure diagnosis apparatus that diagnoses whether or not a failure has occurred will be described.
The failure diagnosis apparatus according to the present embodiment includes the rotation angles θA and θB of the second gear 30 and the third gear 40 that are fixed when the detection apparatus 1 is assembled to a vehicle, and the rotation angle of the second gear 30. A failure is diagnosed based on the angle difference ΔθAB between θA and the rotation angle θB of the third gear 40.

  More specific description will be given below. As described above, the detection device 1 according to the present embodiment is based on the angle difference ΔθAB between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40. Since the rotation angle φ is detected, the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 are within the range of the detectable rotation angle φ of the second rotation shaft 130. There is only one point (rotation angle) that is equal. This point (rotation angle) is determined by the design layout and assembly accuracy, and does not change as long as the detection device 1 operates normally after the detection device 1 is assembled to a vehicle. Focusing on this point, in the failure diagnosis apparatus according to the present embodiment, the second gear 30 is periodically based on the output values from the first rotation angle sensor 72 and the second rotation angle sensor 73. A rotation angle at which the rotation angle θA is equal to the rotation angle θB of the third gear 40 (hereinafter, also referred to as “intersection angle θK”) is calculated, and a failure is diagnosed based on the change in the intersection angle θK. To do. That is, when the change of the crossing angle θK is large, the rotation failure such as the first gear 20 or the second gear 30 being fixed, the failure of the first rotation angle sensor 72 or the second rotation angle sensor 73, etc. It is determined that a failure has occurred in the detection device 1 due to a sensing failure, a signal transmission failure from the first rotation angle sensor 72 or the second rotation angle sensor 73, and the like.

In other words, the crossing angle θK is a zero rotation angle at which the angle difference ΔθAB between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 becomes zero.
Further, the failure diagnosis apparatus according to the present embodiment calculates the intersection angle θK and diagnoses a failure based on the change in the intersection angle θK, and is provided in the ECU as with the calculation means described above. Alternatively, the printed circuit board 70 may be provided.

The following description is based on the assumption that the number of teeth of the first gear 20 is 90, the number of teeth of the second gear 30 is 36, and the number of teeth of the third gear 40 is 39.
FIG. 5 is a diagram illustrating the relationship between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40. Taking the rotation angle θA of the second gear 30 on the horizontal axis and the rotation angle θB of the third gear 40 on the vertical axis, the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 are The relationship is indicated by a thin line. Looking at this thin line, for example, when the rotation angle θB of the third gear 40 is zero degrees, the rotation angle θA of the second gear 30 is 30 degrees, 60 degrees, 90 degrees, 120 degrees, 150 degrees. , 180 degrees, 210 degrees, 240 degrees, 270 degrees, 300 degrees, and 330 degrees.

Further, a line in which the rotation angle θA of the second gear 30 is equal to the rotation angle θB of the third gear 40 is indicated by a bold line.
In the relationship between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 illustrated in FIG. 5, the point (rotation angle) where the thin line and the thick line intersect is zero (360) degrees. is there. This means that when the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 are zero (360) degrees, only the rotation angle θA of the second gear 30 and the third gear In this case, zero degree (360 degrees) is the above-described crossing angle θK.
The relationship between the rotation angle of the second rotation shaft 130 and the rotation angles of the second gear 30 and the third gear 40 shown in FIG. 3 is such that the crossing angle θK is zero degrees (360 degrees). It is the figure which showed the relationship in the case.

  By the way, in the design layout, the point (rotation angle) at which the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 are equal is zero degrees, that is, the crossing angle θK at the design stage is zero degrees. Even if designed, the crossing angle θK after the detection device 1 is assembled to the vehicle may not be zero degrees. This is due to dimensional variation of products such as the second gear 30 and the third gear 40 and poor assembly accuracy of the detection device 1 to the electric power steering device 100.

  FIG. 6 shows the rotation angle θA of the second gear 30 and the second rotation angle θA when the second gear 30 is assembled with the rotation angle θA of the third gear 40 advanced by 20 degrees with respect to the rotation angle θB of the third gear 40. It is a figure which shows the relationship with rotation angle (theta) B of the gear 40 of No.3. FIG. 7 shows the rotation angle of the second rotation shaft 130 when assembled in a state where the rotation angle θA of the second gear 30 is advanced by 20 degrees with respect to the rotation angle θB of the third gear 40; It is a figure which shows the relationship with the rotation angle of the 2nd gearwheel 30 and the 3rd gearwheel 40. FIG.

  In FIG. 6, the thick line that is the line where the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 are equal, and the rotation angle θA of the second gear 30 are the same as those of the third gear 40. The point (rotation) at which the thin line indicating the relationship between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 intersects when assembled in a state advanced by 20 degrees with respect to the rotation angle θB. Angle), that is, the crossing angle θK is 120 degrees.

As described above, after the detection device 1 is assembled to the vehicle, there is a possibility that it deviates from the crossing angle θK at the design stage. However, after the assembly, as long as the detection device 1 operates normally, the crossing angle θK does not change.
Therefore, in the failure diagnosis apparatus according to the present embodiment, after the detection apparatus 1 is assembled to the vehicle, the stage before the vehicle is used by the user, preferably immediately after the detection apparatus 1 is assembled to the vehicle, A crossing angle (hereinafter referred to as “initial crossing angle θK0”) is recognized. Then, the intersection angle θK is periodically calculated based on the output values from the first rotation angle sensor 72 and the second rotation angle sensor 73, and based on the calculated intersection angle θK and the initial intersection angle θK0. Diagnose the failure.

Hereinafter, a method for calculating the crossing angle θK based on output values from the first rotation angle sensor 72 and the second rotation angle sensor 73 will be described on the assumption that the failure diagnosis apparatus is provided in the ECU.
FIG. 8 is a diagram showing the rotation angle θA of the second gear 30 and the cumulative rotation angle θLA of the second gear 30 when the crossing angle θK is 120 degrees.
As can be seen from FIG. 8, the cumulative rotation angle θLA of the second gear 30 can be calculated by the following equation (2).
θLA = 360 × n + θA−θK (2)
n is the number of spans of the second gear 30 from 360 degrees to 0 degrees. FIG. 8 shows a case where n = 2.

Similarly, the cumulative rotation angle θLB of the third gear 40 can be calculated by the following equation (3).
θLB = 360 × m + θB−θK (3)
m is the number of spans of the third gear 40 from 360 degrees to 0 degrees.

On the other hand, the relationship between the angle difference ΔθAB between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 and the cumulative rotation angle θLA of the second gear 30 is expressed by the following equation (4). It becomes the relationship.
θLA = ΔθAB × K1 × KA (4)
Here, KA is a reduction ratio of the second gear 30 and is a value obtained by dividing the number of teeth of the first gear 20 by the number of teeth of the second gear 30 (= number of teeth of the first gear 20 / first gear. The number of teeth of the second gear 30).

The relationship between the angle difference ΔθAB between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 and the cumulative rotation angle θLB of the third gear 40 is expressed by the following equation (5). It becomes the relationship.
θLB = ΔθAB × K1 × KB (5)
Here, KB is a reduction ratio of the third gear 40, and is a value obtained by dividing the number of teeth of the first gear 20 by the number of teeth of the third gear 40 (= number of teeth of the first gear 20 / first gear. 3).

From the above formula (2) and formula (4),
360 × n + θA−θK = ΔθAB × K1 × KA
When this equation is organized,
θK = 360 × n + θA−ΔθAB × K1 × KA,
θK = 360 × n− (ΔθAB × K1 × KA−θA) (6)
It becomes.
Similarly, according to the above equations (3) and (5),
θK = 360 × m− (ΔθAB × K1 × KB−θB) (7)
It becomes.

However, in Equation (6), considering the case where n cannot be specified as described above, which is the number of times of crossing from the intersection angle θK of 360 ° → 0 °, such as immediately after the start of the ECU having the failure diagnosis apparatus, Equation (6) The remainder of “ΔθAB × K1 × KA−θA” divided by 360 is subtracted from 360 to calculate the intersection angle θK. That is, the intersection angle θK is calculated by the following equation (8).
θK = 360−MOD {(360 + ΔθAB × K1 × KA−θA), 360} (8)
Note that MOD {X, Y} is the remainder when X is divided by Y.
Similarly, the intersection angle θK may be calculated by the following equation (9) obtained by modifying the equation (7).
θK = 360−MOD {(360 + ΔθAB × K1 × KB−θB), 360} (9)

Then, the failure diagnosis device causes a failure in the detection device 1 when the intersection angle θK calculated using the above equation (8) or equation (9) continues for a predetermined period of time outside the allowable range. Judge that it is.
The allowable range is preferably determined based on the initial crossing angle θK0. For example, if the initial crossing angle θK0 ± α degrees is within the allowable range, and the calculated crossing angle θK continues outside the initial crossing angle θK0 ± α degrees for a predetermined period, the detection device 1 fails. Is determined to have occurred. At that time, when the initial crossing angle θK0 is zero degrees, it is used as 360 degrees.

Hereinafter, a failure diagnosis process performed by an ECU as an example of a failure diagnosis apparatus will be described using a flowchart.
FIG. 9 is a flowchart showing a procedure of failure diagnosis processing performed by the ECU. The ECU performs this failure diagnosis process at a predetermined cycle. In addition, it is preferable to perform this failure diagnosis process at the same cycle as the rotation angle calculation process.

  First, the ECU calculates the rotation angle θA of the second gear 30 (step 901). This is the same process as step 401 in the rotation angle calculation process described above. The rotation angle θA of the second gear 30 calculated in step 401 in the rotation angle calculation process may be stored in the RAM, and the value stored in the RAM may be read here.

  Next, the ECU calculates the rotation angle θB of the third gear 40 (step 902). This is the same process as step 402 in the rotation angle calculation process described above. The rotation angle θB of the third gear 40 calculated in step 402 in the rotation angle calculation process may be stored in the RAM, and the value stored in the RAM may be read here.

  Next, the ECU calculates an angle difference ΔθAB between the rotation angle θA of the second gear 30 and the rotation angle θB of the third gear 40 (step 903). This is a process of calculating by subtracting the rotation angle θB calculated in step 902 from the rotation angle θA calculated in step 901, and is the same process as step 403 in the rotation angle calculation process described above.

Thereafter, the ECU determines whether or not the angle difference ΔθAB calculated in step 903 is smaller than 0 degrees (deg) (step 904). If the determination in step 904 is affirmative, the value obtained by adding 360 degrees to the angle difference ΔθAB calculated in step 903 is replaced with ΔθAB (ΔθAB ← ΔθAB + 360) (step 905), and the process proceeds to step 906. On the other hand, if a negative determination is made in step 904, the process proceeds to step 906.
Instead of steps 903 to 905, the final angle difference ΔθAB calculated by the rotation angle calculation process stored in the RAM may be read.

  In step 906, the intersection angle θK is calculated (step 906). This is a process of calculating by the above-described equation (8) or equation (9). That is, this is a process of calculating by substituting the rotation angle θA calculated in step 901 and the angle difference ΔθAB calculated in step 903 or 905 into equation (8). Alternatively, the calculation is performed by substituting the rotation angle θB calculated in step 902 and the angle difference ΔθAB calculated in step 903 or 905 into equation (9).

Then, the ECU determines whether or not the intersection angle θK calculated in step 906 is within an allowable range (step 907). If a negative determination is made in step 907, one count value Cn is added (Cn ← Cn + 1) (step 908). Thereafter, it is determined whether or not the count value Cn is greater than or equal to a predetermined value CT (step 909). If an affirmative determination is made in step 909, it is determined that a failure has occurred in the detection apparatus 1 assuming that the intersection angle θK has been outside the allowable range for a predetermined period (step 910). On the other hand, if a negative determination is made in step 909, it is determined that the period has not been continued for a predetermined period, and the failure diagnosis process is terminated.
On the other hand, if the determination in step 907 is affirmative, that is, if it is determined that the intersection angle θK is within the allowable range, the count value Cn is set to zero (Cn ← 0) (step 911), and the failure diagnosis process is terminated.

By such processing, the failure diagnosis device can diagnose whether or not a failure has occurred in the detection device 1 based on the calculated intersection angle θK. The first rotation angle sensor 72 and the second rotation angle sensor used to calculate the rotation angle φ of the second rotation shaft 130 based on the intersection angle θK calculated by the failure diagnosis apparatus in this way. Since it is possible to diagnose whether or not a failure has occurred in the detection device 1 based on the output value from 73, it is possible to diagnose whether or not a failure has occurred without providing a dedicated circuit for failure diagnosis. it can.
Note that the ECU as an example of the failure diagnosis apparatus performs the process of step 906 described above, so that the ECU is an example of a zero rotation angle calculation unit. By performing the processes of steps 907 to 910 described above, the ECU This is an example of failure diagnosis means.

In the above-described failure diagnosis process, when the calculated crossing angle θK continues for a predetermined period of time outside the range of the allowable angle determined based on the initial crossing angle θK0 (predetermined period) When the count value Cn counted in (1) is equal to or greater than a predetermined value CT), it is determined that a failure has occurred in the detection device 1, but the present invention is not limited to this mode.
For example, when the state where the deviation between the calculated intersection angle θK and the initial intersection angle θK0 is equal to or greater than the upper limit value of the predetermined deviation continues for a predetermined period, the detection device 1 has a failure. You may judge.

In addition, the latest intersection angle θK in a state where the change amount of the intersection angle θK is within a predetermined range is set as a reference point for the change amount determination, and the change amount of the intersection angle θK from the reference point is a predetermined value. When the above state is continued for a certain period, it may be determined that a failure has occurred in the detection device 1. More specific description will be given below.
FIG. 10 is a flowchart showing another procedure of the failure diagnosis process performed by the ECU as an example of the failure diagnosis apparatus. The ECU may perform failure diagnosis processing according to this procedure at a predetermined cycle. In the following, differences from the procedure in the flowchart shown in FIG. 9 will be mainly described, and the same processes will be denoted by the same step numbers and detailed description thereof will be omitted.

  In step 906, after calculating the intersection angle θK, a change amount ΔθK of the intersection angle θK with respect to the reference angle θCP is calculated (ΔθK = θK−θCP) (step 1012). The reference angle θCP is a reference angle when determining whether or not a failure has occurred based on the calculated crossing angle θK, and the initial crossing angle θK0 is preferably used as the initial value of the reference angle θCP. .

  Then, it is determined whether or not the absolute value of the change amount ΔθK is equal to or larger than a predetermined allowable upper limit value θU (step 1007). If an affirmative determination is made, the processing from step 908 onward is executed as shown in FIG. On the other hand, if a negative determination is made in step 1007, the count value Cn is set to zero (Cn ← 0) (step 911), and the intersection angle θK calculated in step 906 is replaced with the reference angle θCP (θCP ← θK). (Step 1013).

  As a result, in the failure diagnosis process after the next time, the failure diagnosis is performed based on the intersection angle θK calculated this time and in an allowable state. Even in such an aspect, the failure diagnosis device can accurately diagnose whether or not a failure has occurred in the detection device 1 based on the calculated intersection angle θK.

  In the above-described embodiment, it is described that the failure diagnosis device for diagnosing the failure of the detection device 1 exists separately from the detection device 1, but it can be regarded as the detection device 1 having a failure diagnosis function. Needless to say, it is good. That is, for example, the ECU, the first gear 20, the second gear 30, and the second gear that perform the rotation angle calculation process described using the flowchart of FIG. 4 and the failure diagnosis process described using the flowchart of FIG. 9 or FIG. The first rotation angle sensor 72, the second rotation angle sensor 73, and the like may be regarded as the detection device 1 and may be interpreted as a detection device having a failure diagnosis function.

DESCRIPTION OF SYMBOLS 1 ... Detection apparatus, 10 ... 1st magnet, 40 ... 3rd gearwheel, 50 ... Flat cable cover, 60 ... Base, 70 ... Printed circuit board, 71 ... Relative angle sensor, 72 ... 1st rotation angle sensor, 73 DESCRIPTION OF SYMBOLS 2nd rotation angle sensor, 80 ... Flat cable, 100 ... Electric power steering apparatus, 110 ... Housing, 120 ... 1st rotating shaft, 130 ... 2nd rotating shaft, 140 ... Torsion bar, 150 ... Worm wheel, 160 ... Electric motor

Claims (12)

First detecting means for detecting a rotation angle of a first follower that rotates in conjunction with rotation of the rotating body;
Second detection means for detecting a rotation angle of a second follower that rotates in conjunction with rotation of the rotating body;
The rotation angle of the rotating body based on the angular difference between the rotation angle of the first follower detected by the first detection means and the rotation angle of the second follower detected by the second detection means. A failure diagnosing device for diagnosing a failure of a detecting device for detecting a rotation angle of the rotating body, comprising:
The rotation of the first follower based on the rotation angle of the first follower detected by the first detection means and the rotation angle of the second follower detected by the second detection means. Zero rotation angle calculation means for calculating a zero rotation angle at which the angle difference between the angle and the rotation angle of the second follower is zero;
A failure diagnosis device comprising failure diagnosis means for diagnosing a failure of the detection device based on the zero rotation angle calculated by the zero rotation angle calculation means.   The zero rotation angle calculation means is based on the rotation angle of the first follower calculated backward from the rotation angle of the rotation body and the rotation angle of the first follower detected by the first detection means. The fault diagnosis apparatus according to claim 1, wherein the zero rotation angle is calculated.   The zero rotation angle calculation means is based on the rotation angle of the second follower calculated backward from the rotation angle of the rotation body and the rotation angle of the second follower detected by the second detection means. The fault diagnosis apparatus according to claim 1, wherein the zero rotation angle is calculated.   The failure diagnosis unit determines that a failure has occurred in the detection device when a state in which the zero rotation angle calculated by the zero rotation angle calculation unit is outside an allowable range continues for a predetermined period. The fault diagnosis apparatus according to any one of claims 1 to 3. A rotation angle detection device for detecting a rotation angle of a rotating body,
First detection means for detecting a rotation angle of a first follower that rotates in conjunction with rotation of the rotating body;
Second detection means for detecting a rotation angle of a second follower that rotates in conjunction with rotation of the rotating body;
The rotation angle of the rotating body based on the angular difference between the rotation angle of the first follower detected by the first detection means and the rotation angle of the second follower detected by the second detection means. Computing means for computing
The rotation of the first follower based on the rotation angle of the first follower detected by the first detection means and the rotation angle of the second follower detected by the second detection means. Zero rotation angle calculation means for calculating a zero rotation angle at which the angle difference between the angle and the rotation angle of the second follower is zero;
Failure diagnosis means for diagnosing a failure based on the zero rotation angle calculated by the zero rotation angle calculation means;
A rotation angle detection device comprising:   The zero rotation angle calculation means includes a rotation angle of the first driven body calculated backward from the rotation angle of the rotating body calculated by the calculation means, and the first driven body detected by the first detection means. 6. The rotation angle detection device according to claim 5, wherein the zero rotation angle is calculated based on the rotation angle.   The zero rotation angle calculation means includes a rotation angle of the second driven body calculated backward from the rotation angle of the rotating body calculated by the calculation means, and the second driven body detected by the second detection means. 6. The rotation angle detection device according to claim 5, wherein the zero rotation angle is calculated based on the rotation angle.   The failure diagnosis unit determines that a failure has occurred when a state in which the zero rotation angle calculated by the zero rotation angle calculation unit is outside an allowable range continues for a predetermined period. The rotation angle detection device according to any one of 5 to 7. The rotating body has a gear;
The first driven body has a first driven gear;
The second driven body has a second driven gear having a number of teeth different from the number of teeth of the first driven gear;
The first driven body and the second driven body rotate in conjunction with the rotation of the rotating body by applying a rotational force to the first driven gear and the second driven gear by the gear. The rotation angle detection device according to claim 5, wherein the rotation angle detection device is a rotation angle detection device. First detecting means for detecting a rotation angle of a first follower that rotates in conjunction with rotation of the rotating body;
Second detection means for detecting a rotation angle of a second follower that rotates in conjunction with rotation of the rotating body;
The rotation angle of the rotating body based on the angular difference between the rotation angle of the first follower detected by the first detection means and the rotation angle of the second follower detected by the second detection means. A failure diagnosis method for diagnosing a failure of a detection device that detects a rotation angle of the rotating body, comprising:
The rotation of the first follower based on the rotation angle of the first follower detected by the first detection means and the rotation angle of the second follower detected by the second detection means. A failure diagnosis method comprising: calculating a zero rotation angle at which an angle difference between the angle and the rotation angle of the second follower is zero, and diagnosing a failure of the detection device based on the calculated zero rotation angle .   Calculating the zero rotation angle based on the rotation angle of the first driven body calculated backward from the rotation angle of the rotating body and the rotation angle of the first driven body detected by the first detection means; The fault diagnosis method according to claim 10.   Calculating the zero rotation angle based on the rotation angle of the second driven body calculated backward from the rotation angle of the rotating body and the rotation angle of the second driven body detected by the second detection means; The fault diagnosis method according to claim 10.

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