Magnetic sensor unit

Abstract

To enable the center position of a magnetic sensor in an adjustment direction to be adjusted so that it rests on a reference normal.SOLUTION: A sensor unit 50 comprises: a sensor gear 2 having a protruding and recessed tooth part 2a and fixed to a revolving shaft 1; a magnetic sensor 10 facing the sensor gear 2; a fitting table 20 on which the magnetic sensor 10 is located; and a fixing table 30 on which the fitting table 20 is located. The magnetic sensor 10 includes a permanent magnet and a plurality of magnetoresistive elements disposed between the permanent magnet and the protruding and recessed tooth part 2a. The fitting table 20 can be pivoted on the fixing table 30 to adjust a gap between the magnetic sensor 10 and the sensor gear 2. The magnetic sensor 10 is capable of moving to the fitting table 20 along a direction in which the magnetoresistive elements are aligned (adjustment direction). The magnetic sensor 10 has a curved circumferential surface 15 whose distance from the center of the revolving shaft 1 is constant or almost constant when the center in the adjustment direction of the magnetic sensor 10 lies on a reference normal linking the contact point of the circumferential tangent of the sensor gear 2 which is parallel to the adjustment direction and the center of the revolving shaft 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a magnetic sensor unit, and more particularly to a magnetic sensor unit that detects the rotational position of a rotating shaft, etc. [Background technology]

[0002] 2. Description of the Related Art Magnetic sensor units have been known for use in machine tools, etc. The magnetic sensor units detect, for example, the rotational position and speed of a rotating shaft of an electric motor in the machine tool.

[0003] 6 is a perspective view showing a conventional magnetic sensor unit 150 (hereinafter referred to as sensor unit 150). The sensor unit 150 includes a sensor gear 2, a magnetic sensor 110, a mounting base 20, and a fixed base 30. The sensor gear 2 is an annular member, and has equally spaced concave and convex teeth 2a (magnetic material) on its outer periphery. A rotating shaft 1 of an electric motor is fixed inside the sensor gear 2.

[0004] The magnetic sensor 110 is fixedly disposed so as to face the concave-convex tooth portion 2a of the sensor gear 2. The magnetic sensor 110 is disposed on a mounting base 20. The mounting base 20 is disposed on a fixed base 30.

[0005] The fixed base 30 is a member fixed to the main body of the machine tool (or a non-rotating part of the electric motor). The fixed base 30 has a hole (not shown) through which the rotating shaft 1 of the electric motor passes.

[0006] The mounting base 20 has a plate shape and is a member that extends long in one direction in a plan view. The mounting base 20 has a protrusion 40 on the sensor gear 2 side. The protrusion 40 extends in the longitudinal direction of the mounting base 20, and the side surface of the protrusion 40 opposite the sensor gear 2 forms the reference surface 12 of the magnetic sensor 110.

[0007] 3, 7, and 8 show the magnetic sensor 110 alone. Fig. 3 is a view of the magnetic sensor 110 as viewed from the direction of arrow C in Fig. 6 (from the sensor gear 2 side). Fig. 7 is a view of the magnetic sensor 110 as viewed from the direction of arrow A in Fig. 6 (from the side). Fig. 8 is a view of the magnetic sensor 110 as viewed from the direction of arrow B in Fig. 6 (from above).

[0008] The magnetic sensor 110 has a rectangular shape in a plan view, as shown in Fig. 8. The magnetic sensor 110 has recesses at both ends on the upper side facing the sensor gear 2, as shown in Fig. 6, and has holes 114 (see Fig. 8) for the screws 17 that penetrate in the vertical direction. The magnetic sensor 110 also has a recess that extends in the longitudinal direction (into the depth direction of the paper in Fig. 7) at the lower side facing the sensor gear 2 (left side in Fig. 7), as shown in Fig. 7. This recess receives the protrusion 40 of the mounting base 20, as shown in Fig. 6, and the reference surface 12 of the protrusion 40 contacts the inner surface of this recess.

[0009] As shown in Fig. 8, the magnetic sensor 110 includes two magnetoresistance elements 18a, 18b and a permanent magnet 19. As shown in Fig. 3, the two magnetoresistance elements 18a, 18b are disposed inside the magnetoresistance element unit 18 (constituting part of the magnetoresistance element unit 18). Note that the outer casing of the magnetoresistance element unit 18 is omitted in Fig. 8. The permanent magnet 19 is disposed on the rear side of the two magnetoresistance elements 18a, 18b, i.e., on the opposite side of the two magnetoresistance elements 18a, 18b from the sensor gear 2 (see Fig. 6).

[0010] Here, a line connecting the tangent point of the outer periphery tangent (the tangent to the outer periphery) of the sensor gear 2 (see FIG. 6), which is parallel to the direction in which the two magnetic resistance elements 18a, 18b are arranged (the same as the longitudinal direction of the magnetic sensor 110), and the center of the rotating shaft 1, is defined as a reference normal line. The magnetic sensor 110 is attached and used such that the reference normal line is located at the center SC of the two magnetic resistance elements 18a, 18b. Note that the center SC of the two magnetic resistance elements 18a, 18b is also the center of the magnetic sensor 110 in the longitudinal direction.

[0011] The permanent magnet 19 generates a magnetic flux between itself and the concave-convex tooth portion 2a of the sensor gear 2. The two magnetic resistance elements 18a, 18b each detect the magnetic flux density (density of magnetic flux generated by the permanent magnet 19) of the magnetic resistance element 18a (or 18b) portion, which changes due to the concave-convex tooth portion 2a of the sensor gear 2 as the rotating shaft 1 rotates. As a result, the magnetic sensor 110 outputs a two-phase sinusoidal analog signal corresponding to the detection values ​​of the two magnetic resistance elements 18a, 18b. Wiring such as a power line and a signal line (not shown) is connected to the magnetic sensor 110. The output signal (two-phase sinusoidal analog signal) of the magnetic sensor 110 is sent from the magnetic sensor 110 to a control device of a machine tool or the like. The two-phase sinusoidal analog signal (hereinafter also referred to as a two-phase signal) is subjected to an interpolation process and combined with an output value of a counter circuit to calculate the angle of the rotating shaft 1.

[0012] The magnetic sensor 110 is positioned in contact with the reference surface 12 of the mounting base 20, as shown in Fig. 6. The magnetic sensor 110 is fixed to the mounting base 20 by inserting two screws 17 from above into two holes 114 (see Fig. 8) and screwing them into screw holes (not shown) of the mounting base 20.

[0013] The mounting base 20 has holes (not shown) for passing two screws 22 at both ends in the longitudinal direction of the portion opposite the sensor gear 2. The mounting base 20 is fixed to the fixed base 30 by inserting the two screws 22 into these holes from above and screwing the two screws 22 into screw holes (not shown) provided in the fixed base 30.

[0014] Here, one of the two screws 22 (the upper screw 22 in FIG. 6) is passed through a hole in the mounting base 20 with the eccentric circle nut 21 in between. FIG. 4 is a perspective view of the eccentric circle nut 21. The eccentric circle nut 21 includes a nut portion 21a and a cylindrical portion 21b. The eccentric circle nut 21 has a hole 21c, through which the screw 22 is passed, at a position offset from the center. Of the holes in the mounting base 20 (see FIG. 6) through which the screw 22 is passed, the hole on the side where the eccentric circle nut 21 is provided is formed large so as to receive the cylindrical portion 21b of the eccentric circle nut 21.

[0015] A spring pin 25 is disposed near the screw 22 (the lower screw 22 in FIG. 6) that does not have the eccentric circle nut 21 among the two screws 22. The spring pin 25 is inserted into and held in holes provided in the mounting base 20 and the fixed base 30.

[0016] When adjusting the gap between the magnetic sensor 110 and the sensor gear 2, the two screws 22 are loosened and the nut portion 21a of the eccentric circle nut 21 is turned with a hexagonal wrench to slightly rotate (pivot) the mounting base 20 around the spring pin 25 as the rotation axis. By turning the nut portion 21a of the eccentric circle nut 21, the cylindrical portion 21b of the eccentric circle nut 21 presses the inner surface of the hole in the mounting base 20, rotating the mounting base 20 relative to the fixed base 30 and adjusting the gap between the magnetic sensor 110 and the sensor gear 2. After the gap adjustment, the two screws 22 are tightened to fix the mounting base 20 to the fixed base 30.

[0017] The signal output by the magnetic sensor 110 becomes larger as the gap between the magnetic sensor 110 and the sensor gear 2 becomes shorter, and becomes smaller as the gap becomes longer. Therefore, the gap between the magnetic sensor 110 and the sensor gear 2 requires fine adjustment.

[0018] When manufacturing the magnetic sensor 110, the magnetic sensor 110 is installed so that the line (i.e., the reference normal) connecting the contact point of the outer periphery tangent (the tangent touching the outer periphery) of the adjustment sensor gear of the production device, which is parallel to the longitudinal direction (the direction in which the magnetic resistance elements are arranged) of the magnetic sensor 110, and the center of the rotation axis of this adjustment sensor gear is located at the center of the longitudinal direction of the magnetic sensor 110, and so that the gap with this adjustment sensor gear is a determined distance. In this state, the offset and amplitude ratio of the two-phase signal are precisely adjusted by the volume in the magnetic sensor 110.

[0019] When the magnetic sensor 110 is attached to the electric motor, the gap is adjusted as described above so as to absorb any assembly error in the fixed base 30.

[0020] Incidentally, a rotation angle detector that detects the rotation angle of a rotating body has been publicly known and is disclosed in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0021] [Patent Document 1] JP 2015-158423 A Summary of the Invention [Problem to be solved by the invention]

[0022] In conventional magnetic sensor units, when adjusting the gap between the magnetic sensor and the sensor gear, the eccentric nut is rotated to rotate the mounting base around the spring pin as the rotation axis, so that the center of the longitudinal direction of the magnetic sensor (the direction in which the magnetic resistance elements are arranged) is shifted from the reference normal. As described above, the reference normal is the line that connects the contact point of the outer circumferential tangent of the sensor gear, which is parallel to the direction in which the magnetic resistance elements of the magnetic sensor are arranged, and the center of the rotation axis.

[0023] If there is this misalignment, the mounting position of the magnetic sensor will differ from the mounting position assumed when the magnetic sensor was manufactured, resulting in offset errors and amplitude ratio errors in the two-phase signals output from the magnetic sensor.

[0024] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS An object of the present invention is to make it possible to adjust the position of a magnetic sensor so that the center of the direction in which the magnetoresistance elements of the magnetic sensor are arranged is on a reference normal line. [Means for solving the problem]

[0025] The magnetic sensor unit according to the present invention comprises a sensor gear having a concave-convex toothed portion on its outer periphery and attached to a rotating shaft, a magnetic sensor fixedly arranged opposite the concave-convex toothed portion of the sensor gear, a mounting base on which the magnetic sensor is arranged, and a fixed base on which the mounting base is arranged, the magnetic sensor including a permanent magnet that generates a magnetic flux between the concave-convex toothed portion of the sensor gear and a plurality of magnetic resistance elements arranged between the permanent magnet and the concave-convex toothed portion, the mounting base being capable of rotating relative to the fixed base to adjust a gap between the magnetic sensor and the sensor gear, the magnetic sensor being capable of moving along an adjustment direction in which the magnetic resistance elements are aligned relative to the mounting base, and the magnetic sensor having an outer periphery curved surface arranged such that when the center of the adjustment direction of the magnetic sensor is on a reference normal line connecting a tangent point of a tangent line of the outer periphery of the sensor gear that is parallel to the adjustment direction and the center of the rotation shaft, the distance from the center of the rotation shaft to each position along the outer periphery is constant or nearly constant.

[0026] In the magnetic sensor unit according to the present invention, the outer circumferential curved surface of the magnetic sensor may have an outer periphery along a circle concentric with the sensor gear in a predetermined positional relationship between the magnetic sensor and the sensor gear.

[0027] In the magnetic sensor unit according to the present invention, the magnetic sensor may have a plurality of the outer circumferential curved surfaces corresponding to the radial sizes of the respective sensor gears. Effect of the Invention

[0028] According to the present invention, it is possible to adjust the position of the magnetic sensor so that the center of the direction in which the magnetoresistance elements of the magnetic sensor are arranged (adjustment direction) is on the reference normal line. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a perspective view showing a magnetic sensor unit according to an embodiment. [Diagram 2] FIG. 1 is a plan view of a magnetic sensor according to an embodiment. [Diagram 3] FIG. 4 is a view of the magnetic sensor as viewed from the sensor gear side. [Figure 4] A perspective view of an eccentric circle nut. [Figure 5A] 5A and 5B are diagrams for explaining position adjustment of the magnetic sensor according to the embodiment. [Figure 5B] 5A and 5B are diagrams for explaining position adjustment of the magnetic sensor according to the embodiment. [Figure 5C] 5A and 5B are diagrams for explaining position adjustment of the magnetic sensor according to the embodiment. [Figure 6] FIG. 1 is a perspective view showing a magnetic sensor unit according to a conventional technique. [Figure 7] FIG. 1 is a side view showing a conventional magnetic sensor. [Figure 8] FIG. 1 is a plan view showing a magnetic sensor according to a prior art; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiment described herein. In all drawings, the same elements are given the same reference numerals, and duplicated explanations are omitted. Note that in each drawing, members may be drawn larger than they are, and the intervals between members and the amount of movement of members may be drawn larger than they are.

[0031] 1 is a perspective view showing a magnetic sensor unit 50 (hereinafter referred to as sensor unit 50) according to an embodiment. The sensor unit 50 of this embodiment is different from a conventional sensor unit 150 (see FIG. 6) in that it has a magnetic sensor 10. The configuration of the sensor unit 50 other than the magnetic sensor 10 is the same as that of the conventional sensor unit 150.

[0032] 2 is a view of the magnetic sensor 10 of this embodiment seen from the direction of arrow B in FIG. 1 (from above). The magnetic sensor 10 has a modified shape compared to a conventional magnetic sensor 110 (see FIG. 8). Specifically, the magnetic sensor 10 has two holes 14 (see FIG. 2) through which two screws 17 pass, which are elongated holes. The magnetic sensor 10 also has two curved surfaces 15, 16 on the rear side (the side opposite the sensor gear 2). However, as will be described later, only one curved surface 15, 16 may be provided.

[0033] The two holes 14 (see FIG. 2) of the magnetic sensor 10 extend in the direction in which the two magnetic resistance elements 18a, 18b are lined up, i.e., in the longitudinal direction of the magnetic sensor 10 (the direction in which the reference surface 12 of the mounting base 20 extends). These holes 14 (slots) enable the magnetic sensor 10 to slide along the reference surface 12. In other words, by moving the magnetic sensor 10 along the reference surface 12 with the two screws 17 loosened, the position of the magnetic sensor 10 relative to the mounting base 20 can be changed.

[0034] As shown in FIG. 5A, the curved surface 15 (also referred to as the outer peripheral curved surface 15) of the magnetic sensor 10 has an outer periphery that follows a circle concentric with the sensor gear 2 (a concentric circle, a circle centered at RC) when the magnetic sensor 10 and the sensor gear 2 are in a predetermined positional relationship (normal positional relationship) as shown in FIG. 5A.

[0035] Since the radial size of the sensor gear 2 differs depending on the type of the rotating shaft 1 of the electric motor, the position of the magnetic sensor 10 with respect to the center RC of the rotating shaft 1 changes. To accommodate this, that is, to enable the same magnetic sensor 10 to be used in a sensor unit 50 having a different sensor gear with a different radial size, the magnetic sensor 10 has a different outer circumferential curved surface 16 (see FIG. 2) corresponding to the different sensor gear. The magnetic sensor 10 may have only one outer circumferential curved surface, or may have three or more outer circumferential curved surfaces. When the magnetic sensor 10 is provided with a plurality of outer circumferential curved surfaces, it is preferable to provide the plurality of outer circumferential curved surfaces 15, 16 so that they are aligned in the vertical direction, as shown in FIG. 1.

[0036] Fig. 3 is a view of the magnetic sensor 10 as viewed from the direction of arrow C in Fig. 1 (from the sensor gear 2 side). This figure shows the same as the conventional magnetic sensor 110. Fig. 4 is a view showing the eccentric circle nut 21 of this embodiment, which is also the same as the conventional one, and there is no change in the eccentric circle nut 21.

[0037] Here, we will explain the fixing position of the magnetic sensor 10. Hereinafter, the direction in which the two magnetoresistance elements 18a, 18b (see FIG. 2) of the magnetic sensor 10 are aligned, i.e., the longitudinal direction of the magnetic sensor 10 (the direction in which the reference surface 12 of the mounting base 20 extends), will also be referred to as the adjustment direction.

[0038] 5A to 5C are diagrams for explaining the position adjustment of the magnetic sensor 10, and in these diagrams, the shapes of the members are drawn in a schematic manner. As shown in FIG. 5A, a line that is parallel to the longitudinal direction of the magnetic sensor 10 and tangent to the outer periphery of the sensor gear 2 is a tangent (an outer periphery tangent). A line that connects the contact point where the tangent is tangent to the outer periphery of the sensor gear 2 and the center RC of the rotating shaft 1 is a reference normal. The magnetic sensor 10 is attached and used so that the reference normal is located at the center SC of the two magnetic resistance elements 18a, 18b. The center SC of the two magnetic resistance elements 18a, 18b is also the center of the longitudinal direction (adjustment direction) of the magnetic sensor 10. If the center SC of the longitudinal direction of the magnetic sensor 10 is deviated from the reference normal (see FIG. 5B), an offset error or an amplitude ratio error occurs in the two-phase signal output from the magnetic sensor 10.

[0039] FIG. 5(B) shows an example of a state after the gap between the magnetic sensor 10 and the sensor gear 2 is adjusted by rotating the eccentric nut from the state of the sensor unit 50 shown in FIG. 5A and rotating the mounting base 20 around the spring pin 25 as the rotation axis. When adjusting the gap, first, the two screws 22 are loosened and the eccentric direction of the eccentric nut 21 (see FIG. 1) is aligned with the tangential direction of the sensor gear 2 so as to be in a neutral state. In addition, the two screws 17 of the magnetic sensor 10 are temporarily fastened so that the screws 17 are located in the center of the hole 14 (long hole, see FIG. 2) of the magnetic sensor 10. Next, a thickness gauge is inserted between the magnetic sensor 11 and the sensor gear 2, and the gap is adjusted by rotating the eccentric nut 21 to a desired gap. When the gap adjustment is completed, the two screws 22 are tightened.

[0040] When the gap is adjusted in this manner, the center SC of the magnetic sensor 10 in the longitudinal direction (the direction in which the magnetoresistance elements are arranged) is shifted from the reference normal line, as shown in Fig. 5(B). Therefore, as shown in Fig. 5(C), the magnetic sensor 10 is moved along the reference surface 12 so that the center SC of the magnetic sensor 10 in the longitudinal direction is aligned on the reference normal line.

[0041] However, in reality, when moving the magnetic sensor 10 along the reference surface 12, the worker is unable to grasp, or finds it difficult to grasp, in which direction and to what extent the magnetic sensor 10 needs to be moved so that the longitudinal center SC of the magnetic sensor 10 is on the reference normal line.

[0042] Therefore, the outer circumferential curved surface 15 is used. Specifically, a fixed portion of a dial gauge (not shown) is fixed to the sensor gear 2 side with a magnet or the like, and the probe of the dial gauge is brought into contact with the outer circumferential curved surface 15 of the magnetic sensor 10. Then, the two screws 17 are loosened, and while swinging the rotating shaft 1, the magnetic sensor 10 is slid along the reference surface 12 so that the runout of the outer circumferential curved surface 15 of the magnetic sensor 10 measured by the dial gauge becomes zero, thereby adjusting the center SC of the magnetic sensor 10 in the longitudinal direction to be on the reference normal line. After the adjustment is completed, the two screws 17 are tightened.

[0043] In Fig. 5(C), three lines (lines with arrows at both ends) are drawn, one end of which is on the outer periphery of the sensor gear 2, passes through the center RC of the rotating shaft 1, and the other end of which is on the outer periphery curved surface 15 of the magnetic sensor 10. The position adjustment of the magnetic sensor 10 using the dial gauge described above involves sliding the magnetic sensor 10 so that the lengths of such lines drawn at each position on the outer periphery curved surface 15 of the magnetic sensor 10 are constant or nearly constant. Note that the position adjustment of the magnetic sensor 10 can also be performed by performing the above measurements only on both ends of the outer periphery curved surface 15 of the magnetic sensor 10 (the left and right ends of the outer periphery curved surface 15 in Fig. 5C) and sliding the magnetic sensor 10 so that the lengths are constant (the same).

[0044] In this way, the outer curved surface 15 of the magnetic sensor 10 is formed so that when the center SC of the longitudinal direction of the magnetic sensor 10 is on a reference normal line connecting the tangent point of the outer circumferential tangent (tangent to the outer circumference) of the sensor gear 2, which is parallel to the longitudinal direction (adjustment direction) of the magnetic sensor 10, and the center RC of the rotating shaft 1, the distance from the center RC of the rotating shaft 1 to each position along the outer curved surface 15 is constant or nearly constant.

[0045] Furthermore, by repeatedly performing a series of adjustment processes, including adjusting the gap between the magnetic sensor 10 and the sensor gear 2 and adjusting the position of the magnetic sensor 10 along the reference surface 12, the installation accuracy of the magnetic sensor 10 can be further improved.

[0046] According to the embodiment described above, even if the gap between the magnetic sensor 10 and the sensor gear 2 is adjusted, the center SC in the longitudinal direction of the magnetic sensor 10 can be adjusted to be on the reference normal line. When the sensor unit 50 is assembled to the electric motor, the mounting position of the magnetic sensor 10 is the same as or close to the mounting position assumed at the time of manufacturing the magnetic sensor 10, so that offset errors and amplitude ratio errors can be suppressed from occurring in the two-phase signal output from the magnetic sensor 10.

[0047] In the above-described embodiment, the sensor unit 50 includes one sensor gear 2 (disk) and two corresponding magnetic resistance elements 18a, 18b. However, the sensor unit 50 may include one or three or more magnetic resistance elements. The sensor unit 50 may include another disk attached to the rotating shaft 1 in addition to or instead of the sensor gear 2 having the equally spaced concave-convex tooth portion 2a. The disk may be, for example, an absolute position code disk to which an irregular cyclic code consisting of a binary random number sequence is assigned, and in this case, the sensor unit 50 constitutes an absolute type encoder. The disk may be, for example, a position code disk to which only the origin position is assigned, and in this case, the sensor unit 50 constitutes an incremental type encoder. When such another disk is included, a magnetic resistance element corresponding to the disk is provided in the magnetic sensor 10. [Explanation of symbols]

[0048] 1 rotating shaft, 2 sensor gear, 2a uneven tooth portion, 10 magnetic sensor, 12 reference surface, 14 hole, 15, 16 outer peripheral curved surface, 17 screw, 18 magnetic resistance element unit, 18a, 18b magnetic resistance element, 19 permanent magnet, 20 mounting base, 21 eccentric circle nut, 21a nut portion, 21b cylindrical portion, 21c hole, 22 screw, 25 spring pin, 30 fixing base, 40 protrusion, 50 magnetic sensor unit, 110 magnetic sensor, 114 hole, 150 magnetic sensor unit.

Claims

1. A sensor gear having a concave-convex tooth portion on an outer periphery and attached to a rotating shaft; a magnetic sensor fixedly disposed opposite the concave-convex tooth portion of the sensor gear; a mounting base on which the magnetic sensor is disposed; a fixed base on which the mounting base is disposed, The magnetic sensor includes: a permanent magnet that generates a magnetic flux between itself and the concave-convex tooth portion of the sensor gear; a plurality of magnetoresistance elements disposed between the permanent magnet and the uneven teeth portion; the mounting base is rotatable relative to the fixed base to adjust a gap between the magnetic sensor and the sensor gear; the magnetic sensor is movable along an adjustment direction, which is a direction in which the magnetic resistance elements are arranged relative to the mounting base; the magnetic sensor has an outer circumferential curved surface provided such that, when the center of the adjustment direction of the magnetic sensor is on a reference normal line connecting a tangent point of an outer circumferential tangent of the sensor gear, which is parallel to the adjustment direction, and the center of the rotation shaft, the distance from the center of the rotation shaft to each position along the outer circumferential direction is constant or nearly constant; A magnetic sensor unit comprising:

2. 2. The magnetic sensor unit according to claim 1, The outer circumferential curved surface of the magnetic sensor is In a predetermined positional relationship between the magnetic sensor and the sensor gear, the magnetic sensor has an outer periphery along a circle concentric with the sensor gear. A magnetic sensor unit comprising:

3. 3. The magnetic sensor unit according to claim 1, The magnetic sensor has a plurality of the outer circumferential curved surfaces corresponding to the radial sizes of the plurality of the sensor gears, A magnetic sensor unit comprising:

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