JP2023106909A - Rotation angle detection sensor - Google Patents

Abstract

To provide a rotation angle detection sensor in which a magnet can be surely attached to a prescribed position of a driven gear without possibly attaching the magnet to a wrong magnet accommodation part.SOLUTION: There are provided: a main driving gear 2; driven gears 3A and 3B meshing with a large diameter part 21 and a small diameter part 22 of the main driving gear 2; magnets 4A and 4B attached to the driven gears 3A and 3B; and magnetic sensors 5A and 5B for detecting the magnetism of the magnets 4A and 4B. In the main driving gear 2 and the driven gears 3A and 3B, rotation axes 2S, 3SA, and 3SB cross an attachment reference plane 6. The driven gears 3A and 3B are arranged on a first plane P1. The magnetic sensors 5A and 5B are a rotation angle detection sensor 100 arranged on a second plane P2. The driven gears 3A and 3B are identical in shape, and are attached in opposite directions in the rotation axes 3SA and 3SB directions. Centers 4CA and 4CB of the magnets 4A and 4B are arranged on respective middle point positions in the rotation axes 3SA and 3SB directions.SELECTED DRAWING: Figure 2A

Description

The present invention relates to a rotation angle detection sensor that detects the rotation angle of a steering shaft of a vehicle.

In recent years, vehicles such as automobiles are equipped with various systems for improving running stability, such as a vehicle stability control system and an electronically controlled suspension system. In these systems, the steering angle of the steering wheel is acquired as one of the posture information of the vehicle, and the posture of the vehicle is controlled based on the posture information so that the posture of the vehicle becomes stable. For this reason, a rotation angle detection sensor for detecting the rotation angle of the shaft is attached to the steering shaft.

As such a rotation angle detection device, in Patent Document 1, in order to reduce the manufacturing cost, the main driving gear is provided with two main driving gear portions with different numbers of teeth that rotate about the same axis, and two driven gears. have the same number of teeth, and the two driven gears are meshed with the two main driving gear portions of the main driving gear.

JP-A-2006-234573

However, in the two driven gears of the rotation angle detection device described in Patent Document 1, magnet housing portions are formed at both ends of the shaft portion, respectively, and the magnet housing portions are selected according to the mounting direction of the driven gears. to place the magnet. For this reason, there is a possibility that the magnet may be attached to the opposite side of the predetermined magnet accommodating portion, and there is a problem that the magnet may be attached at a position shifted from the predetermined position when the magnet accommodating portion is mistaken.
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a rotation angle detection sensor in which a magnet can be securely attached to a predetermined position of a driven gear without fear that the magnet will be attached to the wrong magnet accommodating portion.

The present invention has the following configurations as means for solving the above-described problems.
A main driving gear having a large diameter gear portion and a small diameter gear portion, two driven gears meshing with the large diameter gear portion and the small diameter gear portion, two magnets attached to each of the driven gears, and the magnetism of each of the magnets. and two magnetic sensors for detecting the main driving gear and the driven gear, the rotation axes of which are perpendicular to the mounting reference plane, and the two driven gears are arranged in parallel to the mounting reference plane. The two magnetic sensors are arranged on one plane, and the two magnetic sensors are rotation angle detection sensors arranged on a second plane parallel to the mounting reference plane and different from the first plane, and the two driven gears have the same shape and are mounted opposite to each other in the rotation axis direction, and the magnet is arranged on the rotation axis of the driven gear and at the midpoint position of the driven gear in the rotation axis direction. and a rotation angle detection sensor.

With the above configuration, the positional relationship of the magnet with respect to the mounting reference surface of the lower case does not change regardless of which direction the driven gear is mounted in the rotation axis direction. Even if it is mounted as the driven gear for the small diameter gear portion, the mounted driven gear for the large diameter gear portion can function as the driven gear for the small diameter gear portion. The same applies vice versa. Therefore, it is possible to eliminate the occurrence of defective products due to the wrong attachment position of the magnet. Further, the same gear can be used as both the driven gear for the large-diameter gear portion and the driven gear for the small-diameter gear portion. Therefore, by reducing the types of parts, manufacturing costs and part management costs can be reduced.

The driven gear has a cylindrical shaft portion centered on the rotation shaft, and a flange portion extending in a disc shape from the shaft portion and having gear teeth on an outer peripheral end portion thereof. may be provided at a position shifted from the midpoint position of the shaft portion in the direction of the rotation axis, and the magnet may be arranged at the midpoint position of the shaft portion in the direction of the rotation axis.
Further, when the flange portion of the driven gear is mounted on the mounting reference plane so that one side of the rotating shaft faces the other side of the rotating shaft, the flange portion is at a position where it can be engaged with the large-diameter gear portion. It may be in a position where it can be engaged with the small-diameter gear portion when mounted on the mounting reference plane so that the sides face each other.
With this configuration, by changing the mounting direction of the driven gear with respect to the mounting reference surface of the lower case, the position of the flange portion in the rotation axis direction changes. Therefore, it is possible to select whether the driven gear is engaged with the large-diameter gear portion or the small-diameter gear portion depending on the mounting direction of the driven gear.

The driven gear may be provided with the magnet mounting portion only on one side in the rotation axis direction. By providing the magnet mounting portion only on one side of the driven gear, it is not necessary to select the magnet mounting portion when mounting the magnet. Therefore, it is possible to reliably prevent the magnet from being attached to the wrong magnet attachment portion.

The magnet has a ring shape, and is magnetized so that different magnetic poles are alternately arranged along the circumferential direction of the ring. The magnets may be arranged inside or outside the .
By forming the magnet into a ring, the center of the ring of the magnet can be easily arranged at the center of the shaft. Also, the support shaft that supports the driven gear can be inserted through the opening of the magnet. As a result, the support shaft can be lengthened, so that the driven gear can be supported stably.

When viewed from the rotation axis direction, the magnet has a polygonal outer or inner peripheral shape, and when viewed from the rotation axis direction, the inner peripheral surface of the shaft engages the outer periphery of the magnet. or a shape that allows the outer peripheral surface of the shaft portion to engage the inner periphery of the magnet.
With this configuration, it is possible to easily stop rotation and position the magnet with respect to the driven gear.

In the rotation angle detection sensor of the present invention, the magnet is arranged on the rotation shaft and at the midpoint position in the direction of the rotation axis of the driven gear. The position of the magnet with respect to the mounting reference plane does not change. Therefore, it is possible to provide a rotation angle detection sensor that can reliably attach the magnet to a predetermined position of the driven gear without the possibility of mistaking the attachment side of the magnet.

FIG. 2 is a plan view showing the main part of the rotation angle detection sensor according to the embodiment of the invention; FIG. 2 is a cross-sectional view taken along line AA in FIG. 1 of the rotation angle detection sensor according to the embodiment of the present invention; FIG. 2B is an enlarged cross-sectional view showing some members in FIG. 2A; 1 is a perspective view showing a main part of a rotation angle detection sensor according to an embodiment of the invention; FIG. FIG. 2B is a cross-sectional view of a portion corresponding to FIG. 2A of the rotation angle detection sensor according to the reference example; FIG. 4B is a cross-sectional view showing an enlarged view of some members in FIG. 4A;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The same numbers are assigned to the same members in each drawing, and the description thereof will be omitted as appropriate. Each figure shows XYZ coordinates as reference coordinates.

FIG. 1 is a plan view showing the essential parts of a rotation angle detection sensor 1 according to this embodiment. The figure shows a state in which the upper case (upper case 61) of the case 60 of the rotation angle detection sensor 1 is removed (see FIG. 2A).
The rotation angle detection sensor 1 includes a main driving gear 2 rotatably held in a case 60, driven gears 3A and 3B that rotate with the main driving gear 2, magnets 4A and 4B that rotate together with the driven gears 3A and 3B, It has magnetic sensors 5A and 5B for detecting the rotation of the magnets 4A and 4B. The lower case (lower case 62) has a mounting reference surface 6 for the main driving gear 2 and the driven gears 3A and 3B. It is orthogonal to this mounting reference plane 6 .

The main drive gear 2 has a large-diameter gear portion 21 and a small-diameter gear portion 22 around a cylinder formed of synthetic resin. The main driving gear 2 rotates with the rotation of the detected rotating body (not shown). A rotating body to be detected includes, for example, a rotating shaft that rotates multiple times, such as a steering shaft of a vehicle.

The large-diameter gear portion 21 and the small-diameter gear portion 22 have different numbers of teeth. Further, as will be described later, the driven gears 3A and 3B are the same component only with different mounting orientations. Therefore, as the main driving gear 2 rotates, the rotation generated in the driven gear 3A meshing with the large-diameter gear portion 21 differs from the rotation generated in the driven gear 3B meshing with the small-diameter gear portion 22 . Therefore, when the magnets 4A and 4B attached to the driven gears 3A and 3B rotate with the rotation of the driven gears 3A and 3B, the magnets 4A and 4B have different magnetic field changes caused by the rotation. The magnetic sensors 5A and 5B for detecting magnetic fields detect changes in the magnitude and direction of these magnetic fields, so that the rotation angle of the detected rotating body can be accurately detected. As the magnetic sensors 5A and 5B, sensors whose magnetic detection portions are composed of GMR elements, MR elements, TMR elements, Hall elements, or the like are used.

FIG. 2A is a cross-sectional view of the rotation angle detection sensor 1 shown in FIG. 1 taken along line AA. FIG. 2B is an enlarged sectional view showing each two driven gears 3A, 3B, magnets 4A, 4B, and magnetic sensors 5A, 5B in FIG. 2A. As shown in the figure, the driven gears 3A and 3B are arranged on a first plane P1 parallel to the mounting reference plane 6 of the case. In addition, in the rotation angle detection sensor 1 according to the present embodiment, the mounting reference plane 6 and the first plane P1 are the same plane. The magnetic sensors 5A and 5B are arranged on a second plane P2 parallel to the mounting reference plane 6 and different from the first plane P1.

The rotation angle detection sensor 1 uses the same driven gears 3A, 3B, magnets 4A, 4B, and magnetic sensors 5A, 5B. For this reason, hereinafter, items common to these will be appropriately referred to as the driven gear 3, the magnet 4, and the magnetic sensor 5 without the A and B. Similarly, for each part of the driven gear 3, A and B are omitted as appropriate.

As described above, in the rotation angle detection sensor 1 of this embodiment, the driven gears 3A and 3B use the same parts. On the other hand, a rotation angle detection sensor 100 in which the driven gears are not made up of the same parts (driven gears 3A, 3B) but different parts (driven gears 3A, 103) is taken as a reference example, and the two are compared below. while explaining.

FIG. 4A is a cross-sectional view of a portion corresponding to FIG. 2A of a rotation angle detection sensor 100 according to a reference example, and FIG. 4B shows driven gears 3A and 103, two magnets 4A and 4B, and a magnetic sensor 5A in FIG. 4A. , 5B in an enlarged manner.

Here, the driven gears 3A and 103 are composed of cylindrical shaft portions 33A and 133 having the same size, shape and internal structure, and shaft portions 33A and 133 extending from the outer peripheral surfaces of the shaft portions 33A and 133 in parallel with the mounting reference plane 6 (first plane P1). It is provided with flange portions 34A and 134 that protrude in the direction and become gear portions that engage with the main drive gear 2, respectively. The flange portion 134 is a disk-shaped portion extending from the shaft portion 133 and has gear teeth 1341 on its outer peripheral end portion.

The cylindrical shaft portions 33A and 133 have magnet mounting portions 35A and 135, which are openings into which the magnets 4A and 4B can be inserted, at one end side, respectively, and are configured so that the magnets 4A and 4B can be inserted inside through the openings. Further, the cylindrical shaft portions 33A and 133 may be divided into several parts in the circumferential direction of the cylinder. The magnets 4A and 4B arranged inside the shaft portions 33A and 133 are arranged at the same positions separated by a predetermined distance from the ends 31A and 131 which are one ends of the shaft portions 33A and 133, respectively. Further, the shaft portions 33A, 133 are arranged such that the end portions 32A, 132, which are the other ends of the shaft portions 33A, 133, face the mounting reference plane 6 (first plane P1). As a result, the distances between the magnets 4A and 4B with respect to the mounting reference plane 6 (the first plane P1) become the same.

2A and 4A, the large-diameter gear portion 21 and the small-diameter gear portion 22 of the main driving gear 2 are attached to the lower case 62 in the direction of the rotation shaft 2S (rotational axis direction, Z-axis direction). The distances from the reference plane 6 are different. Therefore, in the rotation angle detection sensor 100 shown in FIGS. 4A and 4B, the position of the flange portion 34A with respect to the shaft portion 33A of the driven gear 3A and the position of the flange portion 134 with respect to the shaft portion 133 of the driven gear 103 have different structures. and That is, the flange portions 34A and 134 had to be positioned differently according to the positions of the large-diameter gear portion 21 and the small-diameter gear portion 22 in the direction of the rotation shaft 2S (rotational axis direction, Z-axis direction). Here, the distance from the mounting reference surface 6 to the flange portion 34A means the distance between the end portion 32A of the lower case 62 on the side contacting the mounting reference surface 6 and the flange portion 34A in the directions of the rotation shafts 2S and 3SA. The distance from the mounting reference surface 6 to the flange portion 134 refers to the distance between the end portion 132 of the lower case 62 on the side contacting the mounting reference surface 6 and the flange portion 134 in the directions of the rotation shafts 2S and 103S. Driven gears 3A and 103 are mounted on a mounting reference surface 6 provided on the lower case 62, and magnetic sensors 5A and 5B are positioned on the opposite side of the driven gears 3A and 103 to the mounting reference surface 6. FIG.

The rotation angle detection sensor 100 requires two different types of driven gears 3A and 103, which causes an increase in manufacturing costs. Therefore, in the rotation angle detection sensor 1 of this embodiment, by using the driven gears 3A and 3B of the same shape, it is possible to reduce the manufacturing cost and the management cost.

As shown in FIGS. 2A and 2B, the driven gear 3 in this embodiment has a shaft portion 33 and a flange portion 34 . The shaft portion 33 is a portion that is formed in a tubular shape around the rotating shaft 3S. The flange portion 34 is a disk-shaped portion extending from the shaft portion 33 and has gear teeth 341 on its outer peripheral end portion.

A schematic configuration of the driven gear 3 will be described based on the cross-sectional view of the driven gears 3A and 3B shown in FIG. 2B.
The driven gears 3A, 3B are provided with flanges 34A, 34B closer to one end 32A, 32B than the midpoint position C of the shafts 33A, 33B in the direction along the rotation shafts 3SA, 3SB. ing. The ends 31A and 31B on the other side are open, and the magnets 4A and 4B can be held inside the shaft portions 33A and 33B.

The driven gear 3A is attached to the mounting reference surface 6 of the lower case 62 so that one end portion 32A of the shaft portion 33A is in contact with the opposing gear teeth 341A of the flange portion 34A. engage. The driven gear 3B is mounted on the mounting reference surface 6 of the lower case 62 so that the other end portion 31B of the shaft portion 33B is in contact with the shaft portion 33B. mesh with.

The flange portion 34 of the driven gear 3 is provided at a position shifted from the midpoint position C of the shaft portion 33 in the direction of the rotating shaft 3S toward one end side or the other end side. When the driven gear 3 is arranged so that the end portion 32 of the shaft portion 33 faces and contacts the mounting reference surface 6, the distance from the mounting reference surface 6 to the flange portion 34 and the distance from the mounting reference surface 6 to the large diameter gear The distance to the part 21 is the same. Further, when the driven gear 3 is arranged so that the end portion 31 of the shaft portion 33 faces and contacts the mounting reference surface 6, the distance from the mounting reference surface 6 to the flange portion 34 and the small diameter from the mounting reference surface 6 The distance to the gear portion 22 is the same. In this manner, the flange portion 34 can be engaged with the large-diameter gear portion 21 when attached to the mounting reference surface 6 so that the end portion 32 on one side of the shaft portion 33 is in contact with the other end portion 32 of the shaft portion 33 . It is provided at a position where it can be engaged with the small-diameter gear portion 22 when it is mounted on the mounting reference surface 6 so that the portion 31 is in contact with it.

The magnet 4 is arranged at the midpoint position C of the shaft portion 33 of the driven gear 3 in the direction of the rotating shaft 3S. The distance L1 from the end 31 of the shaft portion 33 to the center 4C (4CA, 4CB) of the magnet 4 in the direction of the rotation axis 3S and the distance L1 from the end 32 of the shaft portion 33 to the center 4C of the magnet 4 in the direction of the rotation axis 3S is equal to the distance L2.

With the above configuration, by changing the mounting direction of the driven gear 3 to the mounting reference plane 6, it is possible to change the position of the flange portion 34 from the mounting reference plane 6 of the lower case 62 in the direction of the rotating shaft 3S. Therefore, depending on the mounting direction of the driven gear 3, it is possible to determine which of the large-diameter gear portion 21 and the small-diameter gear portion 22, which are located at different positions from the mounting reference plane 6 in the direction of the rotating shaft 3S, to engage with.

In the rotation angle detection sensor 1 , the magnet 4 is arranged on the rotation axis 3S of the driven gear 3 and at the midpoint position C in the direction of the rotation axis 3S of the driven gear 3 . Therefore, even when the driven gears 3A and 3B are mounted in opposite directions in the direction of the rotating shaft 3S, that is, even when the driven gear 3 is mounted upside down, the magnets do not contact the mounting reference surface 6 of the lower case 3C. The positional relationship of 4 does not change. Therefore, by changing the mounting direction to the mounting reference surface 6 of the lower case 3C of the driven gear 3 having the same shape, that is, by changing the end portion facing and contacting the mounting reference surface 6, the driven gear 3 for the large-diameter gear portion 21 ( 3A) and the driven gear 3 (3B) for the small-diameter gear portion 22. As a result, the number of types of parts can be reduced, and costs such as manufacturing and management costs can be reduced.

The driven gear 3 includes a magnet mounting portion 35 that opens toward the end portion 31 only on one end portion 32 side in the direction of the rotating shaft 3S. Specifically, the shaft portion 33 is formed in a hollow cylindrical shape, and protrudes in the direction of the rotation shaft 3S from a position near the end portion 32 on one side from the midpoint position C in the direction of the rotation shaft 3S on the inner wall surface of the shaft portion 33. A magnet mounting portion 35 having a bottom portion 36 formed thereon is formed.

The magnet mounting portion 35 (35A, 35B) has a through hole 37 (37A, 37B) centered on the rotation shaft 3S. A wall portion 38 (38A, 38B) projecting cylindrically toward the side is provided. The wall portion 38 may not be completely cylindrical, and may be divided in the outer peripheral direction of the cylinder.

Note that the distance L3 from the midpoint position C of the shaft portion 33 in the direction of the rotation axis 3S to the surface of the bottom portion 36 facing the opening on the other end portion 31 side of the shaft portion 33 on the side where the magnet 4 is stored is the rotation axis. It is substantially the same dimension as the distance L4 from one surface or the other surface of the magnet 4 to the center 4C of the magnet 4 in the 3S direction. Therefore, the magnet 4 is inserted from the opening on the other end 31 side of the shaft portion 33, and the surface of the bottom portion 36 that faces the opening on the other end portion 31 side of the shaft portion 33 and accommodates the magnet 4 is By arranging them in contact with each other, the magnet 4 is arranged at the midpoint position C of the shaft portion 33 in the direction of the rotation axis 3S. That is, the magnet 4 is arranged at a position where the center 4C of the magnet 4 and the midpoint position C of the shaft portion 33 in the direction of the rotating shaft 3S overlap.

Therefore, when driven gears 3 having the same shape are used, it is not necessary to select the magnet mounting portion 35 from among a plurality of mounting portions depending on which of the large-diameter gear portion 21 and the small-diameter gear portion 22 to mesh with. . Therefore, it is possible to reliably prevent erroneous attachment of the magnets 4A and 4B.

In the driven gear 3A having the end portion 32A attached to the mounting reference surface 6 of the lower case 3C, the bottom portion 36A of the magnet mounting portion 35A is positioned between the magnet 4A and the mounting reference surface 6. On the other hand, in the driven gear 3B with the end portion 31B attached to the mounting reference surface 6 of the lower case 3C, the bottom portion 36B of the magnet mounting portion 35B is located between the magnet 4B and the magnetic sensor 5A. However, the bottom portion 36B located between the driven gear 3B and the magnet 4B does not affect the magnetic field of the magnet 4B sensed by the magnetic sensor 5A.

In addition, on the surface of the bottom portion 36 on the side of the end portion 32 , notches 361 ( 361 A, 361 B) with chamfered corners are provided at the end portions of the through hole 37 . Therefore, even if the end portion 31 on the other end side of the shaft portion 33 is placed in contact with the mounting reference surface 6 and the distance between the bottom portion 36 and the magnetic sensor 5 (5B) is reduced, the driven gear 3 and the magnetic sensor 5 (5B) are close to each other. , interference with the magnetic sensor 5 can be prevented. In addition, it is possible to insert a part of the magnetic sensor 5 into the notch 361 within the range where the notch 361 and the magnetic sensor 5 do not come into contact with each other. It is also possible to contribute. Moreover, when the support shaft 63 described later is inserted into the through hole from the notch 361 side, it also functions as a guide portion for the support shaft 63 .

FIG. 3 is a perspective view showing the structure of the main part of the rotation angle detection sensor 1 according to this embodiment. The driven gears 3A and 3B and the magnets 4A and 4B are the same, and the only difference is the mounting direction. As shown in the figure, the shape of the magnet 4 is a ring. The magnet 4 is magnetized so that different magnetic poles are alternately arranged along the circumferential direction of the ring. For example, two different magnetic poles of the same size may be arranged along the circumferential direction of the ring. The magnet 4 is arranged on the inner peripheral surface 351 or the outer peripheral surface 352 of the magnet mounting portion 35 of the shaft portion 33 so that the center 4C of the ring of the magnet 4 and the rotating shaft 3S of the driven gear 3 are aligned.

By making the magnet 4 ring-shaped, it becomes easier to dispose the center 4C of the magnet 4 on the rotation shaft 3S of the driven gear 3 . Also, a support shaft 63 (see FIG. 2A) protruding from the mounting reference surface 6 and supporting the driven gear 3 can be inserted through the central opening of the magnet 4 . More specifically, the wall portion 38 (see FIG. 2B) of the driven gear 3 into which the support shaft 63 is inserted can be passed through the central opening of the magnet 4 . As a result, the support shaft 63 can be made longer by the length for inserting the support shaft 63 into the central opening, compared to the case where the magnet 4 is flat, so that the driven gear 3 can be stably supported. can. The center 4C of the magnet means the center of the outer shape of the magnet 4 when viewed from the direction of the rotating shaft 3S and the center in the direction of the rotating shaft 3S.

In addition, the magnet 4 has a polygonal outer peripheral shape or inner peripheral shape when viewed from the direction along the rotating shaft 3S. The shape of the inner peripheral surface 351 of the magnet mounting portion 35 is such that the outer periphery 41 of the magnet 4 can be locked when viewed from the direction along the rotating shaft 3S. Therefore, positioning of the magnet 4 with respect to the driven gear 3 is facilitated. Further, since the rotation of the magnet 4 with respect to the driven gear 3 is also stopped, the magnet 4 can be rotated as the driven gear 3 rotates. The magnet mounting portion 35 shown in FIG. 3 has an inner peripheral shape of an inner peripheral surface 351 that is capable of engaging the outer periphery 41 of the magnet 4 , and an outer peripheral shape of the outer peripheral surface 352 that is capable of engaging the inner periphery 42 of the magnet 4 . It may be of any possible shape.

INDUSTRIAL APPLICABILITY The present invention can be used, for example, to detect the rotation angle of a multiple rotatable component such as a steering shaft of a vehicle.

1: rotation angle detection sensor 2: main driving gear 2S: rotating shafts 3, 3A, 3B: driven gears 3S, 3SA, 3SB: rotating shafts 4, 4A, 4B: magnets 4C, 4CA, 4CB: centers 5, 5A, 5B: Magnetic sensor 6 : Mounting reference plane 60 : Case 61 : Upper case 62 : Lower case 63 : Support shaft 21 : Large-diameter gear portion 22 : Small-diameter gear portions 31, 31A, 31B: Ends 32, 32A, 32B: Ends 33 , 33A, 33B: shaft portions 34, 34A, 34B: flange portions 341, 341A, 341B: gear teeth 35, 35A, 35B: magnet mounting portion 351: inner peripheral surface 352: outer peripheral surfaces 36, 36A, 36B: bottom portion 361, 361A, 361B: notches 37, 37A, 37B: through holes 38, 38A, 38B: wall 41: outer circumference 42: inner circumference 100: rotation angle detection sensor 103: driven gear 103S: rotating shaft 131: end 132: end Portion 133: Shaft portion 134: Flange portion 1341: Gear tooth 135: Magnet mounting portion C: Midpoint positions L1, L2, L3, L4: Distance P1: First plane P2: Second plane

Claims (6)

a main driving gear having a large diameter gear portion and a small diameter gear portion;
two driven gears meshing with the large-diameter gear portion and the small-diameter gear portion;
two magnets attached to each said driven gear;
and two magnetic sensors that detect the magnetism of each of the magnets,
The main driving gear and the driven gear have rotation axes orthogonal to the mounting reference plane,
The two driven gears are arranged on a first plane parallel to the mounting reference plane,
The two magnetic sensors are rotation angle detection sensors arranged on a second plane parallel to the mounting reference plane and different from the first plane,
The two driven gears have the same shape and are mounted opposite to each other in the rotation axis direction,
A rotation angle detection sensor, wherein the magnet is arranged on the rotating shaft of the driven gear and at a midpoint position in the direction of the rotating shaft of the driven gear. The driven gear has a cylindrical shaft portion centered on the rotation shaft, and a flange portion extending in a disk shape from the shaft portion and having gear teeth on an outer peripheral end thereof,
The flange portion is provided at a position shifted from the midpoint position of the shaft portion in the direction of the rotation axis,
The center of the magnet is arranged at the midpoint position in the rotation axis direction of the shaft portion,
The rotation angle detection sensor according to claim 1. The flange portion of the driven gear is
being in a position where it can be engaged with the large-diameter gear portion when mounted on the mounting reference surface so that one side of the rotating shaft faces each other;
3. The rotation angle detection sensor according to claim 2, wherein the rotation angle detection sensor is positioned so as to be engageable with the small-diameter gear portion when mounted on the mounting reference surface so that the other side of the rotation shaft faces the other side. The driven gear has a magnet mounting portion only on one side in the direction of the rotation axis,
The rotation angle detection sensor according to claim 1. The magnet has a ring shape and is magnetized so that different magnetic poles are alternately arranged along the circumferential direction of the ring,
The magnet is arranged inside or outside the shaft so that the center of the ring and the rotation axis of the driven gear are aligned.
The rotation angle detection sensor according to claim 2. an outer peripheral shape or an inner peripheral shape of the magnet is polygonal when viewed from the direction of the rotation axis;
When viewed from the rotation axis direction, the inner peripheral surface of the shaft has a shape capable of engaging the outer circumference of the magnet, or the outer peripheral surface of the shaft has a shape capable of engaging the inner circumference of the magnet. ,
The rotation angle detection sensor according to claim 5.