Magnetic Sensor Unit

Abstract

To provide a magnetic sensor unit that can accurately detect a change in the magnetic field of a magnetic sensor and also can accurately determine the position of each magnet to a yoke.SOLUTION: A magnetic sensor unit 50 includes: a yoke 30 fixed to a rotor 13, the rotor being relatively displaced with respect to a substrate 21; a magnet 34 and a magnet 35 fixed to the yoke 30 and arranged to be separate from each other in the direction in which the rotor 13 is relatively displaced; and a magnetic sensor 22 fixed to the substrate 21, the magnetic sensor detecting a change in a magnetic field formed by the magnet 34 and the magnet 35. The yoke 30 has a protruding unit 38 protruding between the magnet 34 and the magnet 35. The protruding unit 38 has a contact unit 383 in contact with the magnet 34 and a contact unit 385 in contact with the magnet 35.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a magnetic sensor unit. [Background technology]

[0002] Conventionally, a magnetic sensor unit that uses a magnetic sensor to detect changes in a magnetic field generated by a magnet has been known (Patent Document 1). For example, a magnet is fixed to one member and a magnetic sensor is fixed to the other member, and the relative displacement of the two members is obtained from the results of detection by the magnetic sensor of changes in the magnetic field when the two members are displaced relative to each other. The range in which the displacement of the detection target can be detected depends on the range of the magnetic field generated by the magnet.

[0003] Patent Document 1 discloses a rotation angle detection unit including a cylindrical yoke, two magnets fixed to the inner periphery of the yoke, and a magnetic sensor disposed at the center of rotation of the yoke. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-132819 Summary of the Invention [Problem to be solved by the invention]

[0005] In the invention described in Patent Document 1, two magnets are arranged spaced apart from each other in the circumferential direction of the yoke. This leaves a space between the magnets. In this space, the magnetic flux density is likely to decrease depending on the size of the space between the magnets, making them more susceptible to the influence of external magnetic fields. This makes it difficult for the magnetic sensor to accurately detect changes in the magnetic field. Furthermore, in the invention described in Patent Document 1, it is difficult to accurately position each magnet relative to the yoke.

[0006] An object of the present invention is to provide a magnetic sensor unit that can accurately detect changes in a magnetic field using a magnetic sensor and can accurately position each magnet relative to a yoke. [Means for solving the problem]

[0007] In order to achieve the above object, the magnetic sensor unit of the present invention comprises a magnetic body fixed to a second member that is displaced relatively to a first member, at least two magnets fixed to the magnetic body and spaced apart in the direction of relative displacement of the second member, and a magnetic sensor fixed to the first member that detects changes in the magnetic field generated by the magnets, wherein the magnetic body has a protruding portion that protrudes between the two magnets, and the protruding portion has a contact portion with which the magnets come into contact. The magnetic body has recesses in the portions where the magnets are fixed, and each recess creates a protrusion between the two magnets of the magnetic body, and the depth of each recess on the contact side is deeper than the depth of the other portions. [Effects of the Invention]

[0008] According to the present invention, the magnetic sensor can accurately detect changes in the magnetic field, and the magnets can be accurately positioned relative to the yoke. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a throttle grip device to which a magnetic sensor unit is applied; [Figure 2] FIG. 2 is an external perspective view of a base plate and a rotor provided in the throttle grip device. [Figure 3] FIG. 2 is a perspective view of a main part of a magnetic sensor unit supported by a substrate and a rotor. [Figure 4] FIG. 2 is an exploded perspective view of a main part of the magnetic sensor unit. [Figure 5] FIG. 5 is a cross-sectional view taken along line AA in FIG. [Figure 6] FIG. 4 is a view seen from the direction of arrow B in FIG. 3. [Figure 7] FIG. 4 is a view seen from the direction of arrow C in FIG. 3. [Figure 8] FIG. 1 is a side view of a conventional magnetic sensor unit. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the configurations described in the following embodiments are merely examples, and the scope of the present invention is not limited to the configurations described in the embodiments.

[0011] The throttle grip device 100 shown in FIG. 1 is attached to a portion extending to the right of a handlebar 14 of a motorcycle, as an example. Vehicles to which the throttle grip device 100 is applied are not limited to motorcycles, but include, for example, three- and four-wheeled buggies equipped with bar-type handlebars, as well as various other vehicle bodies such as snowmobiles and jet skis. The throttle grip device 100 includes a grip portion 10 and a housing 11. With respect to the direction of the handlebar 14 (X direction), the tip side of the handlebar 14 is defined as the +X side, and the center side of the vehicle body is defined as the -X side. The grip portion 10 is disposed in an area including the tip end of the handlebar 14. The grip portion 10 is made of a rubber material or the like. The housing 11 is disposed adjacent to the grip portion 10 on the -X side (center side of the vehicle body).

[0012] A throttle pipe 12 is supported on the handlebar 14. The throttle pipe 12 is substantially cylindrical and is rotatable around a rotation center C1 of the handlebar 14 along the outer periphery of the handlebar 14. The rotation center C1 is parallel to the X direction. A grip portion 10 is disposed on the outer periphery of the throttle pipe 12. The throttle pipe 12 rotates around the rotation center C1 of the handlebar 14 in response to the rotation of the grip portion 10 by the rider.

[0013] The housing 11 accommodates a substrate (first member) 21, a rotor (second member) 13 that rotates and displaces around a rotation center C1 relative to the substrate 21, and a magnetic sensor unit 50 (see FIG. 2). As shown in FIG. 3, the magnetic sensor unit 50 includes a magnetic sensor 22, a magnet (first magnet) 34, a magnet (second magnet) 35, and a yoke (magnetic body) 30. While the magnetic sensor unit 50 includes two magnets (magnet 34 and magnet 35) in this embodiment, the number of magnets is not limited to two and may be, for example, three or more. The housing 11 also has outer walls, and the wall closest to the motorcycle body (-X side) is outer wall 11a, and the wall closest to the grip portion 10 (+X side) is outer wall 11b. In the X direction, the yoke 30, the magnets 34 and 35, and the magnetic sensor 22 are positioned in descending order of proximity to the outer wall 11a. This allows the yoke 30 to effectively reduce the effect of external magnetic fields on the magnetic sensor 22, contributing to the miniaturization of the housing 11. The yoke 30, magnets 34, 35, and magnetic sensor 22 may be arranged such that the yoke 30 is disposed between the magnetic sensor 22 and the outer wall closer to the magnetic sensor 22. The arrangement of the yoke 30, magnets 34, 35, and magnetic sensor 22 is not limited to the arrangement shown in FIG.

[0014] The substrate 21 is fixed to the housing 11 via a fixing member (not shown). A magnetic sensor 22 is mounted (fixed) on the substrate 21. The rotor 13, the object of displacement detection, is fixed to the throttle pipe 12. A yoke 30 is fixed to the rotor 13. A magnet 34 and a magnet 35 are fixed to the yoke 30. Therefore, when the grip portion 10 rotates, the rotor 13, yoke 30, magnet 34, and magnet 35 rotate together in conjunction with the throttle pipe 12. The rotation angle of the throttle pipe 12 is detected by a magnetic sensor unit 50 serving as an accelerator position sensor (APS).

[0015] As shown in FIGS. 3 and 4 , the yoke 30 is formed of a plate-shaped member. Examples of materials used for the yoke 30 include soft magnetic materials such as iron, silicon steel, and permalloy. This allows the yoke 30 to be easily magnetized by the magnetic fields from the magnets 34 and 35. The yoke 30 has a flat portion 31 extending along the displacement direction of the rotor 13, i.e., the rotation direction, a bent portion 32 bending from one end of the flat portion 31 in the displacement direction, and a bent portion 33 bending from the other end. As shown in FIGS. 6 and 7 , the flat portion 31 is arc-shaped about the center of rotation C1 and is substantially perpendicular to the center of rotation C1. This allows the yoke 30 to rotate stably together with the magnets 34 and 35 as the rotor 13 rotates. When using two magnets, for example, the central angle θ30 of the arc-shaped flat portion 31 is preferably 90° to 180°, more preferably 90° to 120°. The bent portion 32 and the bent portion 33 each protrude (stand) in a direction intersecting the flat portion 31, i.e., toward the +X side. The protruding height H32 of the bent portion 32 and the protruding height H33 of the bent portion 33 are the same.

[0016] Magnets 34 and 35 are fixed on the +X side of flat portion 31, between bent portions 32 and 33. Magnet 34 is located on the bent portion 32 side, and magnet 35 is located on the bent portion 33 side. Magnets 34 and 35 are each a rectangular parallelepiped permanent magnet, and are fixed to flat portion 31 by magnetic force. Note that the method of fixing magnets 34 and 35 to flat portion 31 is not limited to the method using magnetic force; for example, molding, in which magnets 34 and 35 and yoke 30 are covered with resin, may be used in combination with the method using magnetic force. Magnets 34 and 35 are arranged spaced apart in the longitudinal direction of flat portion 31 (the direction of relative displacement of rotor 13). Furthermore, the north pole of one of magnets 34 and 35 faces the yoke 30, and the south pole of the other magnet faces the yoke 30. In this embodiment, the north pole of magnet 34 faces the flat surface portion 31 side of yoke 30, and the south pole of magnet 35 faces the flat surface portion 31 side of yoke 30. In this way, adjacent magnets 34 and 35 are arranged so that the magnetic poles that abut against flat surface portion 31 are opposite to each other.

[0017] As shown in Fig. 6, magnet 34 and magnet 35 are arranged at the shortest distance (straight-line distance) with gap D1 maintained between them. Magnet 34 is arranged at the shortest distance with gap D2 maintained between them and bending portion 32. Magnet 35 is arranged at the shortest distance with gap D3 maintained between them and bending portion 33. Gap D1, gap D2, and gap D3 may be the same as or different from one another. As shown in Fig. 7, +X side surface 341 of magnet 34, +X side surface 351 of magnet 35, +X side surface 321 of bending portion 32, and +X side surface 331 of bending portion 33 are located on the same plane.

[0018] As described above, the magnetic sensor 22 is fixed to the substrate 21. As shown in FIG. 3 (also in FIGS. 6 and 7), the magnetic sensor 22 is disposed opposite the flat portion 31. The magnetic sensor 22 detects changes in the magnetic field formed by the magnets 34 and 35. The rotation of the grip portion 10 by the driver is the throttle operation. This throttle operation causes the yoke 30 and the magnets 34 and 35 to rotate together with the rotor 13, as described above. The magnetic sensor 22 detects the rotational displacement of the rotor 13 in accordance with the change in the magnetic field, and detects this rotational displacement as the throttle opening. Then, the amount of intake air into the engine is adjusted in accordance with the throttle opening, thereby controlling the engine output and engine speed.

[0019] Next, a description will be given of the relationship between the magnetic field lines of the magnets 34 and 35 and the detection by the magnetic sensor 22. In FIG.

[0020] 7, a magnetic field line M1 is formed from the north pole of surface 351 of magnet 35 to the south pole of surface 341 of magnet 34. In addition, the north pole of magnet 34 abuts against flat portion 31. As a result, the polarity of surface 321 of bent portion 32 closest to magnet 34 becomes north, and a magnetic field line M2 is formed from the north pole of surface 321 to the south pole of surface 341 of magnet 34. Meanwhile, the south pole of magnet 35 abuts against flat portion 31. As a result, the polarity of surface 331 of bent portion 33 closest to magnet 35 becomes south, and a magnetic field line M3 is formed from the north pole of surface 351 of magnet 35 to the south pole of surface 331 of bent portion 33.

[0021] When the throttle is operated, the yoke 30, the magnet 34, and the magnet 35 are rotationally displaced about the center of rotation C1 relative to the magnetic sensor 22. At this time, the magnitude of the magnetic field passing through the magnetic sensor 22 and the direction of the magnetic lines of force change.

[0022] Now, consider the case where bent portions 32 and 33 are omitted from yoke 30. In this case, magnetic field lines corresponding to magnetic field lines M2 and M3 are hardly formed, and only magnetic field line M1 is formed. Therefore, the detection range of the rotational displacement of rotor 13 is limited to the range where magnet 34 and magnet 35 face magnetic sensor 22.

[0023] On the other hand, in this embodiment, not only magnetic field line M1 but also magnetic field lines M2 and M3 are formed, so that the detection range of the rotational displacement of rotor 13 can be expanded to the range where the area between bent portions 32 and 33 faces magnetic sensor 22.

[0024] Furthermore, the yoke 30, being made of a magnetic material, serves as a shield. This suppresses the influence of external magnetic fields on the magnetic sensor 22 from the -X side, thereby improving the detection accuracy of the rotational displacement of the rotor 13. Furthermore, the yoke 30 allows the magnetic field lines to be concentrated toward the magnetic sensor 22, thereby enabling the magnets 34 and 35 to be made smaller. As described above, the magnets 34 and 35 are spaced apart by a gap D1. The magnet 34 is spaced apart from the bent portion 32 by a gap D2. The magnet 35 is spaced apart from the bent portion 33 by a gap D3. This arrangement increases the range of the magnetic field in the longitudinal direction of the yoke 30, making it easier to widen the detection range. Furthermore, the magnets 34 and 35 have opposite magnetic poles that abut against the flat portion 31, thereby further widening the detection range.

[0025] As described above, the magnets 34 and 35 are disposed at a distance from each other. This leaves a gap between the magnets 34 and 35. This gap can easily reduce the magnetic flux density depending on the size of the gap between the magnets 34 and 35, making them susceptible to the influence of external magnetic fields. In this case, it may be difficult for the magnetic sensor 22 to accurately detect changes in the magnetic field that accompany the rotation of the rotor 13. Furthermore, if the magnets 34 and 35 are not accurately positioned relative to the yoke 30, it may be difficult to detect the rotational displacement of the rotor 13.

[0026] Therefore, the magnetic sensor unit 50 is configured to be able to reduce such problems. The configuration and operation of this unit will be described below.

[0027] 4, the flat surface portion 31 of the yoke 30 is provided with a recess (first recess) 36 in the portion where the magnet 34 is fixed, and a recess (second recess) 37 in the portion where the magnet 35 is fixed. The recesses 36 and 37 form a protruding portion 38 between the magnets 34 and 35 of the yoke 30 and around the magnets 34 and 35. Therefore, the yoke 30 has a protruding portion 38 between the magnets 34 and 35, i.e., a portion of the flat surface portion 31 in the longitudinal direction. The recesses 36 and 37 are formed by, for example, press working.

[0028] The protrusion 38 has a contact portion (first contact portion) 383 that contacts the magnet 34, and a contact portion (second contact portion) 385 that contacts the magnet 35. As shown in Fig. 6, the contact portion 383 and the contact portion 385 are arranged symmetrically with respect to a virtual line VL1 that passes through the midpoint C2 between them and the rotation center C1.

[0029] The contact portion 383 is in surface contact with the surface 342 of the magnet 34 facing the magnet 35. This allows the contact portion 383 to have a wide contact area with the magnet 34. The contact portion 385 is in surface contact with the surface 352 of the magnet 35 facing the magnet 34. This allows the contact portion 385 to have a wide contact area with the magnet 35. As shown in FIG. 7 , the portion between the contact portions 383 and 385 forms a magnetic path, which can concentrate magnetic field lines M4 from the north pole of the magnet 34 to the south pole of the magnet 35, thereby further increasing the magnetic flux density between the magnets 34 and 35. This suppresses the influence of external magnetic fields in the space between the magnets 34 and 35. The magnetic sensor 22 can also more accurately detect changes in the magnetic field occurring as the rotor 13 rotates, even between the magnets 34 and 35, thereby further improving detection accuracy.

[0030] Further, a wall surface (auxiliary abutment portion) 384 that comes into surface contact with the outer surface 343 of the magnet 34 is formed and connected to the abutment portion 383. A wall surface (auxiliary abutment portion) 386 that comes into surface contact with the outer surface 353 of the magnet 35 is formed and connected to the abutment portion 385.

[0031] Furthermore, abutment portion 383 allows magnet 34 to be accurately positioned in the circumferential direction of yoke 30, and wall surface 384 allows magnet 34 to be accurately positioned in the radial direction of yoke 30. Meanwhile, abutment portion 385 allows magnet 35 to be accurately positioned in the circumferential direction of yoke 30, and wall surface 386 allows magnet 35 to be accurately positioned in the radial direction of yoke 30. Furthermore, by providing abutment portion 383 and abutment portion 385 between magnets 34 and 35, magnets 34 and 35 can be accurately positioned, allowing displacement to be detected with greater precision.

[0032] The area between the contact portion 383 and the wall surface 384 is recessed to form a clearance portion 387 that escapes from the corner portion 344 of the magnet 34 (see FIG. 6). Similarly, the area between the contact portion 385 and the wall surface 386 is recessed to form a clearance portion 388 that escapes from the corner portion 354 of the magnet 35.

[0033] Consider a magnetic sensor unit 50' in which the protrusion 38 having the abutment portion 383 and the abutment portion 385 is omitted from the yoke 30. In this case, as shown in FIG. 8, the omission of the protrusion 38 makes it difficult to sufficiently form magnetic field lines M4' extending from the north pole of the magnet 34 to the south pole of the magnet 35. That is, the magnetic flux density is lower than that of the magnetic field lines M4 in the magnetic sensor unit 50. Accordingly, the magnetic flux densities M1 to M3 are also lower. For example, depending on various conditions such as the materials of the magnet 34 (magnet 35) and the yoke 30 and the size of the gap D1, the magnetic flux density in the magnetic sensor unit 50' (the portion generating the magnetic field lines M4') may be approximately 20 to 40% lower than that in the magnetic sensor unit 50 (the portion generating the magnetic field lines M4). This may affect the accurate detection of changes in the magnetic field by the magnetic sensor 22. Furthermore, in the magnetic sensor unit 50', the protrusion 38 is omitted, so the positions of the magnets 34 and 35 on the yoke 30 are not fixed, making accurate positioning difficult.

[0034] As shown in Fig. 4, the depth (DP1 + DP2) of recess 36 on the contact portion 383 side is deeper than the depth (DP2) of the other portions. This ensures that contact portion 383 and wall surface 384 with which magnet 34 comes into surface contact are secured. Similarly, the depth (DP3 + DP4) of recess 37 on the contact portion 385 side is deeper than the depth (DP4) of the other portions (see Fig. 5). This ensures that contact portion 385 and wall surface 386 with which magnet 35 comes into surface contact are secured.

[0035] Furthermore, the depth DP3 of the recess 37 is preferably 25% to 100% of the thickness T30 of the yoke 30, and more preferably 25% to 50% (the same applies to the depth DP1 of the recess 36). This ensures a sufficient contact area between the abutment portion 383 and the magnet 34, and a sufficient contact area between the abutment portion 385 and the abutment portion 35, and further increases the magnetic flux density at the protrusion 38.

[0036] The displacement member (rotor 13 in this embodiment) whose displacement is detected by magnetic sensor 22 may be any member that displaces relative to magnetic sensor 22. Therefore, either or both of magnetic sensor 22 and the displacement member may be configured to actually displace. Furthermore, the manner of relative displacement of the displacement member is not limited to rotational displacement. [Explanation of symbols]

[0037] 13 Rotor (second member) 21 substrate (first member) 22 Magnetic Sensor 30 York 34 Magnet (1st Magnet) 35 Magnet (Second Magnet) 38 Convex part 50 Magnetic sensor unit 383 Contact part (1st contact part) 385 Contact part (second contact part)

Claims

1. a magnetic body fixed to a second member that is displaceable relative to the first member; At least two magnets fixed to the magnetic body and spaced apart in the direction of relative displacement of the second member; a magnetic sensor fixed to the first member and configured to detect a change in the magnetic field generated by the magnets; the magnetic body has a protruding portion between the two magnets, the protrusion has a contact portion with which each of the magnets contacts, The magnetic body has recesses formed in portions where the magnets are fixed, The recesses form the protrusions between the two magnets of the magnetic body, The magnetic sensor unit, wherein the depth of each recess on the contact portion side is deeper than the depth of the other portion.

2. The magnetic body has a plate shape, 2. The magnetic sensor unit according to claim 1, wherein the length of each of the contact portions along the thickness direction of the magnetic body is 25% to 100% of the thickness of the magnetic body.

3. The magnetic body has a plate shape, 3. The magnetic sensor unit according to claim 2, wherein the length of each of the contact portions along the thickness direction of the magnetic body is 25% to 50% of the thickness of the magnetic body.

4. The magnetic sensor unit according to claim 1 , wherein each of the contact portions is in surface contact with the magnet.

5. 2. The magnetic sensor unit of claim 1, wherein the magnetic body has a flat portion extending in the displacement direction and having the convex portion arranged midway in the displacement direction, and two bent portions bent from both ends of the flat portion in a direction intersecting the flat portion in the displacement direction.

6. 6. The magnetic sensor unit according to claim 5, wherein one of the two magnets has an N pole facing the magnetic body, and the other magnet has an S pole facing the magnetic body.

7. The magnetic sensor unit according to claim 6 , wherein the magnetic sensor is disposed opposite the flat portion.

8. the second member is rotationally displaced about a rotation center, The magnetic sensor unit according to claim 7 , wherein the planar portion is substantially perpendicular to the center of rotation.

9. The second member is rotated by operating a throttle on a handle of the motorcycle, 2. The magnetic sensor unit according to claim 1, wherein the magnetic sensor detects a throttle opening in response to a change in the magnetic field.

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