JP2005134150A - Rotation angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the miniaturization of a detector, to accurately detect a rotation angle of a rotary shaft, and to lower a cost, as to a rotation angle detector for detecting a rotation angle of a rotary shaft with its axial movement regulated. <P>SOLUTION: This rotation angle detector 1 is equipped with a magnetometric sensor 5, a conversion mechanism 6, and an absolute angle computation part. The magnetometric sensor 5 includes a movable part 3 held by a support member 12 movably in the axial direction S of a shaft 2 under measurement and a fixed part 4 provided so as not to make contact with the movable part 3, and detects displacement of the movable part 3 with respect to the fixed part 4. The conversion mechanism 6 includes a helical groove 19 provided in an integrally rotable manner on the periphery of the shaft 2 and an engaged part 20 provided in an axially movable manner integrally with the movable part 3 to engage with the helical groove 19, and converts the turn of the shaft 2 into a movement of the movable part 3 in the axial direction S. The computation part computes the turning angle of the shaft 2 based on the displacement of the movable part 3 detected by the magnetometric sensor 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rotation angle detection device that detects the rotation angle of a rotating shaft whose movement in the axial direction is restricted.

  Various devices have been proposed as rotation angle detection devices that detect the rotation angle of a rotating shaft (measured shaft) that rotates multiple times (rotates more than 360 °) from a reference position. For example, by forming a spiral groove on one side surface of a rotating member such as a gear connected to the rotating shaft so as to be able to rotate in conjunction with each other, a tracer as an engaging member is engaged with the groove so as to be relatively movable, A device for detecting the rotation angle of the rotation shaft has been proposed (see, for example, Patent Documents 1, 2, and 3).

  Specifically, the tracer is moved (oscillated) on one side surface of the rotating member by moving the tracer relative to the spiral groove with the rotation of the spiral groove. The amount is detected and the rotation angle of the rotation shaft is calculated. In particular, Patent Documents 2 and 3 use two sensors, a sensor for detecting the movement of the tracer and a sensor capable of detecting the rotation of the rotation shaft in a range of 0 ° to 360 °, in order to improve detection accuracy. The rotation angle of the rotating shaft is calculated based on the detection values of both sensors.

Further, the rotary shaft is screwed into the housing so as to be movable in the axial direction, the amount of axial movement of the rotary shaft accompanying the rotation of the rotary shaft is detected by the first sensor, and 0 ° of the rotary shaft is detected. There has been proposed a technique in which a rotation angle of ˜360 ° is detected by a second sensor and an absolute rotation angle of a rotation shaft is calculated based on detection values of both sensors (see, for example, Patent Document 4).
Further, a cylindrical moving member is screwed to the outer periphery of the rotating shaft so as to be axially movable and non-rotatable, and the rotational angle of the rotating shaft is detected by moving the moving member in the axial direction as the rotating shaft rotates. (See, for example, Patent Document 5). Specifically, the contact point is fixed to the outer periphery of the moving member, and the resistance value of the resistor slidably contacting the contact point is changed by the movement of the contact point in the axial direction accompanying the rotation of the rotation shaft, so that the rotation shaft The rotation angle of is detected.
Japanese Patent Application Laid-Open No. 10-30909. Japanese Patent Application No. 2002-2121776. Japanese Patent Application No. 2002-286253. Japanese Patent Application No. 2002-249602. JP 2001-354144 A.

  However, according to the configurations described in Patent Documents 1 to 3, since it is necessary to form a spiral groove on one side surface of the rotating member and swing the tracer on this one side surface, the radial dimension of the rotating member Increases the size of the device. In particular, according to the configurations described in Patent Documents 2 and 3, since it is necessary to use a plurality of sensors, the number of parts increases and the cost increases. Further, according to the configuration described in Patent Document 4, since the rotary shaft needs to be moved in the axial direction as the rotary shaft rotates, the configuration is applied to a rotary shaft such as a steering shaft that is restricted from moving in the axial direction. Cannot be used. Furthermore, according to the configuration described in Patent Document 5, a contact failure may occur between the contact and the resistor, and the rotation angle of the rotating shaft may not be accurately detected.

  The present invention has been made under such a background, and in a rotation angle detection device for detecting the rotation angle of a rotation shaft whose movement in the axial direction is restricted, the device can be miniaturized and the rotation angle of the rotation shaft can be achieved. It is an object to make it possible to accurately detect and to reduce the cost.

  In order to achieve the above object, the present invention provides a rotation angle detecting device for detecting a rotation angle of a shaft to be measured which is rotatable and cannot be moved in the axial direction, and is supported by a support member so as to be movable in the axial direction of the shaft to be measured. A detecting means for detecting displacement of the movable part relative to the fixed part, a helical engagement part provided on the outer periphery of the shaft to be measured, and a movable part. A conversion mechanism for converting the rotation of the shaft to be measured into the movement of the movable portion in the axial direction, and a detecting means, And a calculation means for calculating the rotation angle of the shaft to be measured based on the displacement of the movable part detected by the above-mentioned method.

  According to the present invention, since the movable part is moved in the axial direction of the shaft to be measured, the overall length in the radial direction of the shaft to be measured can be sufficiently reduced to achieve downsizing of the apparatus. Moreover, since the movable part and the fixed part are not in contact with each other, it is possible to prevent a contact failure between the movable part and the fixed part. As a result, the rotation angle of the shaft to be measured can be accurately detected. Furthermore, the number of detection means is only one, and the number of parts can be reduced to reduce the cost. Further, the rotation of the shaft to be measured can be converted into the axial movement of the movable portion with a simple configuration in which a spiral engaging portion and an engaged portion that engages with the helical engaging portion are provided. In addition, as a helical engaging part, a helical groove | channel or a protruding item | line can be illustrated.

In the present invention, there may be further provided a rotation restricting means for restricting the rotation of the movable portion around the support member. In this case, the rotation of the shaft to be measured can be reliably converted into the movement of the movable part.
In the present invention, the fixed portion may be fixed at a position opposite to the movable portion in the axial direction. In this case, the overall length of the apparatus in the radial direction of the shaft to be measured can be further reduced.

  In the present invention, the movable part may have magnetism, and the fixed part may detect a change in the magnetic field accompanying the movement of the movable part. In this case, the displacement of the movable part relative to the fixed part can be accurately detected.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional side view of a rotation angle detection device 1 according to an embodiment of the present invention. Referring to FIG. 1, a rotation angle detection device 1 detects a rotation angle of a shaft 2 to be measured that is rotatable and cannot move in the axial direction.
The rotation angle detection device 1 includes a movable part 3 movable in the axial direction S of the shaft 2 to be measured and a fixed part 4 provided in non-contact with the movable part 3, and detects the displacement of the movable part 3 relative to the fixed part 4. Based on the displacement of the movable part 3 detected by the magnetic sensor 5, the conversion mechanism 6 that converts the rotation of the shaft 2 to be measured into the movement of the movable part 3 in the axial direction S, and the like. An absolute angle calculation unit 7 (see FIG. 3 which is a block diagram showing a main part of the electrical configuration) is provided as a calculation means for calculating the rotation angle of the measurement shaft 2. Hereinafter, the axial direction S of the shaft 2 to be measured is simply referred to as “axial direction S”.

In the present embodiment, a description will be given based on the case where the rotation angle detection device 1 is applied to an electric power steering device of an automobile to detect the rotation angle of a steering member (not shown) such as a steering wheel. In this case, the shaft 2 to be measured is constituted by a shaft that rotates integrally with the steering member. However, the present invention can be applied to general rotation angle detection of a rotation shaft.
A housing 8 that houses the shaft 2 to be measured, the magnetic sensor 5, and the conversion mechanism 6 is provided. Bearings 9 and 10 are attached to the shaft 2 to be measured at a predetermined interval in the axial direction S. The shaft 2 to be measured is supported by the housing 8 via these bearings 9 and 10 so as to be rotatable and immovable in the axial direction.

  The movable part 3 of the magnetic sensor 5 is formed of, for example, a magnet and has magnetism. When the movable part 3 moves, the distance G (air gap) between the fixed part 4 and the fixed part 4 changes. The surrounding magnetic field changes. The fixing unit 4 detects the surrounding magnetic field and outputs a signal corresponding to the detected magnetic field value to the absolute angle calculation unit 7. With the above configuration, the fixed unit 4 can detect a change in the magnetic field accompanying the movement of the movable unit 3, that is, a displacement of the movable unit 3 relative to the fixed unit 4.

  The fixed portion 4 is disposed in the vicinity of the shaft 2 to be measured, and one side surface is fixed to the inner surface 11 of the housing 8. A support member 12 is fixed to the other side surface of the fixed portion 4. The support member 12 is disposed in parallel with the measured shaft 2 and extends along the axial direction S. The movable part 3 is supported by the support member 12 so as to be movable in the axial direction S and restricted in rotation around the support member 12, and is disposed at a position opposite to the fixed part 4 in the axial direction S.

  FIG. 2 is a cross-sectional front view of the periphery of the movable part 3 and the support member 12 of the magnetic sensor 5. Referring to FIGS. 1 and 2, the support member 12 includes a main portion 13 having a circular cross section, for example, and a ridge 14 as a rotation restricting means for restricting the rotation of the movable portion 3 around the support member 12. And. The ridges 14 project from the outer peripheral surface of the main body 13. An engagement hole 15 is formed in the movable portion 3, and the support member 12 is inserted through the engagement hole 15. The concave portion 16 formed on the peripheral surface of the engagement hole 15 of the movable portion 3 is engaged with the ridge 14 so that the rotation of the movable portion 3 with respect to the support member 12 is restricted.

  The conversion mechanism 6 includes a spiral groove 19 as a spiral engagement portion formed on the outer periphery 18 of the large-diameter portion 17 of the shaft 2 to be measured and rotatable integrally with the shaft 2 to be measured, and the movable portion 3 and the shaft. And an engaged portion 20 that is provided so as to be integrally movable in the direction S and engages with the spiral groove 19. The engaged portion 20 is formed in, for example, a rod shape, one end portion is fixed to one side surface 3 a of the movable portion 3 of the magnetic sensor 5, and the other end portion is in sliding contact with the spiral groove 19.

  With the above configuration, when the spiral groove 19 rotates with the shaft 2 to be measured, the engaged portion 20 and the movable portion 3 are displaced in the axial direction S by an amount corresponding to the rotation angle of the shaft 2 to be measured. G changes. As a result, the magnetic field around the fixed unit 4 changes, and the fixed unit 4 detects the change in the magnetic field and outputs a detection signal to the absolute angle calculating unit 7 (see FIG. 3). The absolute angle calculator 7 calculates the rotation angle of the shaft 2 to be measured based on the given detection signal, that is, the displacement of the movable portion 3 accompanying the rotation of the shaft 2 to be measured.

  Thus, according to the present embodiment, the rotation angle of the shaft 2 to be measured is detected by moving the movable part 3 in the axial direction S of the shaft 2 to be measured. Miniaturization can be achieved by sufficiently reducing the total length of the angle detection device 1. Moreover, since the movable part 3 and the fixed part 4 are not in contact with each other, it is possible to prevent a contact failure between the movable part 3 and the fixed part 4. Furthermore, since the fixed part 4 detects a change in the magnetic field accompanying the movement of the movable part 3, the displacement of the movable part 3 relative to the fixed part 4 can be detected accurately. As a result, the rotation angle of the shaft 2 to be measured can be accurately detected. Furthermore, the number of magnetic sensors 5 is only one, and the number of parts can be reduced and the cost can be reduced.

  Further, the rotation of the shaft 2 to be measured can be converted into the movement of the movable portion 3 in the axial direction S with a simple configuration in which the spiral groove 19 and the engaged portion 20 engaged therewith are provided. Further, since the rotation of the movable portion 3 around the support member 12 is restricted by the ridges 14 of the support member 12, the rotation of the shaft 2 to be measured is reliably converted into the movement of the movable portion 3 in the axial direction S. be able to. Further, by fixing the fixed portion 4 at a position opposite to the movable portion 3 in the axial direction S, the total length of the rotation angle detecting device 1 in the radial direction of the shaft 2 to be measured can be further reduced.

  The present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the claims. For example, as shown in FIG. 4, a spiral ridge 21 is provided in place of the spiral groove 19, and the groove 22 that engages the ridge 21 at the other end (tip) of the engaged portion 20. May be formed. Further, as shown in FIG. 5, the main body 13 of the support member 12 is formed in a polygonal cross section (in FIG. 5, a square cross section), and the shape of the engagement hole 15 of the movable section 3 is changed to the shape of the main body 13. You may form in a corresponding shape (cross-sectional polygonal shape). In this case, the main body 13 of the support member 12 also functions as a rotation restricting means for the movable portion 3.

  Furthermore, a conversion mechanism is formed by screwing a cylindrical member into the outer periphery 18 of the large-diameter portion 17 of the shaft 2 to be measured so as to be axially movable and non-rotatable, and the movable portion 3 is formed on the outer periphery of the cylindrical member. The structure which provides may be sufficient. In this case, the cylindrical member and the movable portion 3 move in the axial direction S as the measured shaft 2 rotates.

It is a typical section side view of the rotation angle detection device of one embodiment of the present invention. It is a section front view around the movable part and support member of a magnetic sensor. It is a block diagram which shows the principal part of the electrical structure of a rotary body detection apparatus. It is a partial cross section side view around the conversion mechanism of other embodiments of the present invention. It is a partial cross section front view of the support member periphery of other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation angle detection apparatus 2 Measuring shaft 3 Movable part 4 Fixed part 5 Magnetic sensor (detection means)
6 Conversion mechanism 7 Absolute angle calculation unit (calculation means)
12 Support member 13 Main part (rotation restricting means)
14 Projection (turning restricting means)
18 outer periphery 19 spiral groove (helical engagement part)
20 engaged portion 21 spiral protrusion (spiral engaging portion)
S axis direction

Claims (4)

In a rotation angle detecting device for detecting a rotation angle of a shaft to be measured that is rotatable and cannot be moved in an axial direction, a movable portion that is supported by a support member so as to be movable in the axial direction of the shaft to be measured is provided in a non-contact manner. Detecting means for detecting the displacement of the movable part relative to the fixed part,
A shaft to be measured includes a helical engagement portion provided on the outer periphery of the shaft to be measured so as to be integrally rotatable and a portion to be engaged that is provided so as to be movable integrally with the movable portion in the axial direction and engage with the spiral engagement portion. A conversion mechanism that converts the rotation of the movable part into an axial movement of the movable part;
A rotation angle detection apparatus comprising: a calculation unit that calculates a rotation angle of the shaft to be measured based on the displacement of the movable part detected by the detection unit.   The rotation angle detection device according to claim 1, further comprising a rotation restricting unit that restricts rotation of the movable portion around the support member.   3. The rotation angle detection device according to claim 1, wherein the fixed portion is fixed at a position opposite to the movable portion in the axial direction. 4. The rotation angle detecting device according to claim 1, wherein the movable part has magnetism, and the fixed part detects a change in magnetic field accompanying the movement of the movable part.

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