JP2005195362A - Rotation angle detector and torque detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation angle detector capable of determining a trouble by only output signals. <P>SOLUTION: In this rotation angle detector, the first and second targets 3b, 3c mutually prime in their numbers are provided respectively in rotors 12b, 12c rotated coaxially, and a plurality of respective detection means C, D, E, F arranged respectively opposedly to the targets 3b, 3c to output detection signals different each other in phases in response to respective positions of the targets 3b, 3c, according to rotation of the rotors 12b, 12c, detect rotation angles of the rotors 12b, 12c, based on the detection signals output respectively. The rotation angle detector is provided with a map 15 for storing values taken respectively by the plurality of detection signals output from the plurality of detection means (C, D or E, F), and for storing a prescribed range including the values, as a combination correlated to a mutual relation of the plurality of detection signals, and a means for determining the propriety of including the combination of the detection signals output respectively from the plurality of detection means (C, D or E, F), in the map 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides one or a plurality of first targets provided on a rotating body, a second target provided on the rotating body with a number that is relatively prime to the number of first targets, and the first target and the second target. And a plurality of detection means that output detection signals having different phases according to the positions of the first target and the second target as the rotating body rotates. The present invention relates to a rotation angle detection device that detects a rotation angle of a rotating body based on a detection signal, and a torque detection device including the rotation angle detection device.

  There is an electric power steering device that reduces the burden on a driver by driving an electric motor to assist steering by an automobile steering device. This includes an input shaft connected to the steering member (steering wheel), an output shaft connected to the steering wheel by a pinion and a rack, etc., and a connecting shaft that connects the input shaft and the output shaft. The torque sensor detects a steering torque applied to the input shaft, and drives and controls a steering assisting electric motor linked to the output shaft based on the steering torque detected by the torque sensor. (Torque detection device) is required.

The applicant of the present application is that the first shaft connected to the steering member and the second shaft connected to the steering mechanism are connected by the connecting shaft, and the rotating body is provided coaxially on the first shaft and the second shaft, One or a plurality of targets are provided on each rotator, and two detection means arranged opposite to each target output detection signals whose phases differ from each other according to the position of the target as the rotator rotates. A means for detecting a steering torque applied to the first shaft based on the detection signal output by each means, assisting the steering in accordance with the detected steering torque, and obtaining a difference between the maximum value and the minimum value for each detection signal; An electric power steering apparatus comprising means for comparing the obtained differences for each detection signal with each other and failure determination means for determining whether any of the detection means has failed based on the comparison result A, it has been proposed in Japanese Patent Application No. 2002-149820.
JP 2003-83823 A

  In the conventional rotation angle detection device and torque detection device such as the electric power steering device described above, the failure of the detection means monitors the value of the detection signal (for example, the maximum value, the minimum value, the intersection, etc.) accompanying the operation of the steering member. When a predetermined condition was met, a failure was determined. Therefore, there is a problem that when the steering member is not operated, it is impossible to determine the failure of the detection means only by the output signal.

The present invention has been made in view of the circumstances as described above. In the first invention, a rotation angle detection device capable of determining a failure of a detection means only by an output signal even when a steering member is not operated. The purpose is to provide.
It is an object of the second invention to provide a torque detection device that can determine a failure of a detection means only by an output signal even when a steering member is not operated.

  According to a first aspect of the present invention, there is provided a rotation angle detection device, wherein one or a plurality of first targets provided on a rotating body and a number that is relatively prime to the number of the first targets are coaxial with the rotating body or the rotating body. According to each position of the 1st target and the 2nd target arranged so that the 2nd target provided in the other rotating body to rotate, and the 1st target and the 2nd target, respectively, and the rotating body rotates A plurality of detection means for outputting detection signals having different phases from each other, and a rotation angle detection device for detecting a rotation angle of the rotating body based on the detection signals output by the detection means. A value to be taken by each of the plurality of detection signals output from the detection means and a predetermined range including the value are described as a combination corresponding to the mutual relationship of the plurality of detection signals. And a means for determining whether or not a combination of detection signals output from each of the plurality of detection means is included in the map. It is characterized in that any one of the detection means is determined to be a failure.

  In the torque detector according to the second aspect of the present invention, a rotating body is provided coaxially on each of the first shaft and the second shaft connected by a connecting shaft, and each of the rotating bodies is provided with one or a plurality of targets. A plurality of detection means arranged opposite to each other outputs detection signals having different phases according to the position of the target as the rotating body rotates, and the detection means outputs the detection signals based on the detection signals output by the detection means. In the torque detection device for detecting the torque applied to one axis or the second axis, a value to be taken by each of the plurality of detection signals output from the plurality of detection means and a predetermined range including the value are represented by the plurality of detection signals. Whether the map includes a map stored as a combination corresponding to the mutual relationship and a combination of detection signals output from the plurality of detection means, respectively. Determining and means, when it is determined not include said means is characterized in that one of said plurality of detecting means are no order to determine that the malfunction.

  According to the rotation angle detection device according to the first aspect of the present invention, it is possible to realize a rotation angle detection device that can determine the failure of the detection means only by the output signal even when the rotating body does not rotate. Further, not only disconnection of the detection means, ground fault or intermediate failure, but also nonstandard output signal waveform due to deterioration of the detection means can be detected.

  According to the torque detection device of the second invention, it is possible to realize a torque detection device that can determine the failure of the detection means only by the output signal even when the rotating body does not rotate. Further, not only disconnection of the detection means, ground fault or intermediate failure, but also nonstandard output signal waveform due to deterioration of the detection means can be detected.

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a schematic diagram showing a main configuration of an embodiment of a rotation angle detection device and a torque detection device according to the present invention. This rotation angle detection device and torque sensor 4 (torque detection device) are used in an electric power steering device, and an input shaft 6 (rotary body, first shaft) whose upper end is connected to a steering member 1 (handle). The lower end of the output shaft 7 (rotary body, second shaft) connected to the steering mechanism pinion 8 is coaxially connected via a thin torsion bar 9 (connecting shaft), and the steering member 1 A steering shaft 13 that communicates with the steering mechanism is configured, and the vicinity of the connecting portion of the input shaft 6 and the output shaft 7 is configured as follows.

  A disk-shaped target plate 12 a is coaxially fitted and fixed to the input shaft 6 in the vicinity of the end portion on the connection side with the output shaft 7. On the outer peripheral surface of the target plate 12a, for example, 34 targets 3a, which are magnetic projections, are projected at equal intervals in the circumferential direction. The target 3a is composed of spur gear teeth having an involute tooth profile, and an annular spur gear constitutes the target plate 12a and the target 3a.

On the output shaft 7, disk-shaped target plates 12 b and 12 c (rotary bodies) are coaxially arranged in the vicinity of the end portion on the connection side with the input shaft 6, and the target plate 12 b is placed on the input shaft 6 side and fixedly fitted. Has been. On the outer peripheral surface of the target plate 12b, 34 targets 3b, which are projections made of a magnetic material, are projected in equal intervals with the target 3a in the circumferential direction, and are projected on the outer peripheral surface of the target plate 12c. The target 3c, which is a magnetic projection, is provided with a number that is relatively prime to the number of the targets 3b, for example, 33, and is projected at equal intervals in the circumferential direction. Here, being relatively prime means having no common divisor other than 1.
The targets 3b and 3c are spur gear teeth having involute teeth, and the annular spur gears constitute the target plates 12b and 12c and the targets 3b and 3c.

  A sensor box 11 is disposed outside the target plates 12a, 12b, and 12c so as to face the outer edges of the respective targets 3a, 3b, and 3c on the outer periphery. The sensor box 11 is fixedly supported at a non-moving part such as a housing (not shown) that supports the input shaft 6 and the output shaft 7. Inside the sensor box 11, the magnetic sensors A and B (detecting means) that face different parts in the circumferential direction of the target 3a on the input shaft 6 side, and the different parts in the circumferential direction of the target 3b on the output shaft 7 side. The magnetic sensors C and D (detecting means) that are to be stored are stored with their circumferential positions properly aligned. In addition, magnetic sensors E and F (detection means) facing different parts in the circumferential direction of the target 3c on the output shaft 7 side are housed.

  The magnetic sensors A, B, C, D, E, and F use elements having characteristics that change electrical characteristics (resistance) due to the action of a magnetic field, such as magnetoresistive elements (MR elements). The sensors are configured such that the detection signals change according to the adjacent parts of 3b and 3c, and these detection signals are given to the arithmetic processing circuit 10 using a microprocessor outside or inside the sensor box 11. Yes.

The arithmetic processing circuit 10 has a built-in table 14 that stores the rotation angle when the output shaft 7 rotates and the values of the respective detection signals actually measured by the magnetic sensors C, D, E, and F in association with each other. Yes. Further, in the image as shown in FIG. 6, the values of the detection signals of the magnetic sensors A and B and the predetermined range including the values and the electrical angle are associated with each other, that is, the detection signal value and the value are included. A map 15 that stores a predetermined range as a combination corresponding to the mutual relationship of each detection signal is incorporated. The map 15 can also be applied to each set of detection signals of the magnetic sensors C and D and detection signals of the magnetic sensors E and F.
The magnetic sensors A, B, C, D, E, and F output detection signals that approximate a sine wave according to the passage of the targets 3a, 3b, and 3c. This detection signal has a non-linear rate of change around the transition from rising to falling or falling to rising, but it can be supplemented by the following signal processing method.

  In the torque sensor 4 having such a configuration, each of the magnetic sensors A, B, C, D, E, and F is shown in FIG. 2 while the corresponding targets 3a, 3b, and 3c pass through the positions facing the respective sensors. As shown in (a), (b), and (c), a detection signal that rises and falls according to changes in the rotation angles of the input shafts 6 and 7 is output.

The detection signals of the magnetic sensors A and B correspond to the rotation angle of the input shaft 6 provided with the target 3a corresponding thereto, and the detection signals of the magnetic sensors C and D are provided by the target 3b corresponding thereto. Therefore, the detection signals of the magnetic sensors E and F correspond to the rotation angle of the output shaft 7 provided with the target 3c facing each other.
Therefore, the arithmetic processing circuit 10 can calculate the relative rotation angle of the input shaft 6 from the detection signals of the magnetic sensors A and B, and the arithmetic processing circuit 10 and the magnetic sensors A and B can detect the rotation angle of the input shaft 6. Operates as The arithmetic processing circuit 10 can calculate the relative rotation angle of the output shaft 7 from the detection signals of the magnetic sensors C and D, and the arithmetic processing circuit 10 and the magnetic sensors C and D can detect the rotation angle of the output shaft 7. Operates as

When torque is applied to the input shaft 6, there is a difference between the detection signals of the magnetic sensors A and B and the detection signals of the magnetic sensors C and D.
The magnetic sensors A and C and the magnetic sensors B and D have a phase difference of 90 °, for example, in the circumferential direction of the target plates 12a and 12b. Each detection signal has a maximum non-linear change rate at the maximum value and the minimum value which are turning points of ascending and descending, but since the phases are different, they can be complemented each other. As long as complementation is possible, the different phase angle may be any electrical angle between 1 ° and less than 360 °.

  Here, the difference between the detection signal of the magnetic sensor A and the detection signal of the magnetic sensor C, or the difference between the detection signal of the magnetic sensor B and the detection signal of the magnetic sensor D is the rotation angle between the input shaft 6 and the output shaft 7. Corresponding to the difference (relative angular displacement). This relative angular displacement corresponds to the twist angle generated in the torsion bar 9 that connects the input shaft 6 and the output shaft 7 under the action of torque applied to the input shaft 6. Therefore, the torque applied to the input shaft 6 can be calculated based on the difference between the detection signals described above.

  Similarly to the magnetic sensor C and the magnetic sensor D, the magnetic sensor E and the magnetic sensor F have a phase difference of 90 ° in the circumferential direction of the target plate 12c, but are opposed to the magnetic sensor C and the magnetic sensor D. While the number of targets 3b to be processed is 34, the number of targets 3c facing the magnetic sensors E and F is 33. Therefore, as shown in FIG. 3, the magnetic sensors C and E and the magnetic sensors D and F output detection signals whose phases are shifted from each other to the 1/34 phase whenever the output shaft 7 rotates one phase. .

  With only the magnetic sensors C and E or only the magnetic sensors D and F, as shown in FIG. 3, the same set of detection signal values appears twice while the output shaft 7 rotates 360 °. Although the rotation angle (absolute rotation angle, absolute steering angle) cannot be specified, the rotation angle of the output shaft 7 is specified by referring to the detection signal values of the magnetic sensors C, E, D, and F in the table 14. I can do it.

Hereinafter, the operation of the electric power steering apparatus having such a configuration will be described with reference to the flowcharts of FIGS.
When detecting the torque and the absolute steering angle, the arithmetic processing circuit 10 first performs failure detection of the magnetic sensors A, B, C, D, E, and F (S1 in FIG. 4).
In the failure detection (S1) of the magnetic sensors A, B, C, D, E, and F, the arithmetic processing circuit 10 first detects the detection signals A (θ) and the magnetic sensors A, B, C, D, E, and F. B (θ), C (θ), D (θ), E (θ), and F (θ) are read (S20 in FIG. 5).

  Next, the arithmetic processing circuit 10 refers to the map 15 to determine whether or not the map 15 includes a combination (reciprocal relationship) of the detection signals A (θ) and B (θ) of the magnetic sensors A and B. Is determined (S21). For example, in FIG. 6 showing the image of the map 15, when the detection signal A (θ) is in the range of A2 (θ) to A1 (θ), the detection signal B (θ) is B2 (θ) to B1 (θ ), When the detection signal A (θ) is in the range of A4 (θ) to A3 (θ), the detection signal B (θ) is in the range of B4 (θ) to B3 (θ). If it is not within the range (if not), it is determined that it is not included.

This can be determined by executing for each electrical angle on the map 15 even when the electrical angle is unknown.
If the combination of the detection signals A (θ) and B (θ) of the magnetic sensors A and B is not included in the map 15 (S21), the arithmetic processing circuit 10 determines that either or both of the magnetic sensors A and B are It is determined that there is a failure (S24).

Next, the arithmetic processing circuit 10 determines whether or not a combination (reciprocal relationship) of the detection signals C (θ) and D (θ) of the magnetic sensors C and D is included in the map 15. ) And B (θ) in the same manner as in the combination (S22).
If the combination of the detection signals C (θ) and D (θ) of the magnetic sensors C and D is not included in the map 15 (S22), the arithmetic processing circuit 10 determines that either or both of the magnetic sensors C and D are present. It is determined that there is a failure (S25).

Next, the arithmetic processing circuit 10 determines whether or not the combination (reciprocal) of the detection signals E (θ) and F (θ) of the magnetic sensors E and F is included in the map 15. ), B (θ), the same determination as in the case of the combination (S23), and returns.
If the combination of the detection signals E (θ) and F (θ) of the magnetic sensors E and F is not included in the map 15 (S23), the arithmetic processing circuit 10 determines that either or both of the magnetic sensors E and F are present. It determines with it being a failure (S26), and returns.

  The arithmetic processing circuit 10 executes the failure detection of the magnetic sensors A, B, C, D, E, and F (S1), and determines that one or both of the magnetic sensors A and B are failed (S2). After outputting the first failure signal indicating the failure of the sensor 4 (S5), the absolute steering angle is detected by the magnetic sensors C, D, E, and F (S6) and output (S7) and the process returns.

When the arithmetic processing circuit 10 determines that one or more of the magnetic sensors C, D, E, and F are malfunctioning (S3), it indicates a malfunction of the torque sensor 4 and the rotation angle detection device (absolute steering angle detection device). A second failure signal is output (S4) and the process returns.
When the arithmetic processing circuit 10 does not determine that the magnetic sensors A, B, C, D, E, and F have failed (S3), the arithmetic processing circuit 10 executes torque calculation and absolute steering angle detection (S8), and detects the detected torque value. Then, the absolute steering angle is output (S9) and the process returns.

It is a schematic diagram which shows the principal part structure of embodiment of the rotation angle detection apparatus and torque detection apparatus which concern on this invention. It is a wave form diagram which shows the example of each detection signal of a magnetic sensor. It is a wave form diagram which shows the example of each detection signal of the magnetic sensor from which the number of opposing targets differs. It is a flowchart which shows operation | movement of the arithmetic processing circuit of the rotation angle detection apparatus and torque detection apparatus which concern on this invention. It is a flowchart which shows operation | movement of the arithmetic processing circuit of the rotation angle detection apparatus and torque detection apparatus which concern on this invention. It is explanatory drawing which shows the image of a map.

Explanation of symbols

1 Steering member A, B, C, D, E, F Magnetic sensor (detection means)
3a, 3b, 3c Target 4 Torque sensor 6 Input shaft (first shaft, rotating body)
7 Output shaft (second shaft, rotating body)
8 Pinion (steering mechanism)
9 Connecting shaft (torsion bar)
10 Arithmetic Processing Circuits 12a, 12b, 12c Target plate (rotating body)
14 tables 15 maps

Claims (2)

A first target or a plurality of first targets provided on the rotating body, and a number of first targets provided on the rotating body or another rotating body rotating coaxially with the rotating body. Two targets are arranged opposite to the first target and the second target, respectively, and detection signals having different phases are output according to the positions of the first target and the second target as the rotating body rotates. A rotation angle detection device that includes a plurality of detection means and detects a rotation angle of the rotating body based on detection signals output from the detection means;
A map for storing a value to be taken by each of the plurality of detection signals output from the plurality of detection means and a predetermined range including the value as a combination corresponding to the mutual relationship of the plurality of detection signals; Means for determining whether a combination of detection signals output by the detection means is included in the map, and when it is determined that the means is not included, any one of the plurality of detection means A rotation angle detecting device characterized in that it is determined to be a failure. Rotating bodies are coaxially provided on the first axis and the second axis connected by the connecting shaft, respectively, and each of the rotating bodies is provided with one or a plurality of targets, and a plurality of detecting means respectively disposed facing the targets. As the rotating body rotates, detection signals having different phases according to the position of the target are output, and torque applied to the first shaft or the second shaft is calculated based on the detection signals output from the detection means. In the torque detection device to detect,
A map for storing a value to be taken by each of the plurality of detection signals output from the plurality of detection means and a predetermined range including the value as a combination corresponding to the mutual relationship of the plurality of detection signals; Means for determining whether a combination of detection signals output by the detection means is included in the map, and when it is determined that the means is not included, any one of the plurality of detection means A torque detection device characterized in that it is determined to be a failure.

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