JP2011043345A - Magnetic rotation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic rotation detector hardly affected by disturbances. <P>SOLUTION: In the magnetic rotation detector 10, a case 33 housing a magnetic sensing element 42 therein includes a first case body 31 with a partition section intervening between a magnet body 20 and the magnetic sensing element 42 and a second case body 32 covering the magnetic sensing element 42 together with the first case body 31. Both of the first case body 31 and the second case body 32 are electrically-conductive. The first case body 31 is formed of a non-magnetic material and the second case body 32 is formed of a magnetic material. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a magnetic rotation detection device for detecting an angular position, a rotation speed, and the like of a rotating body.

  Among the rotation detectors, there are two types of non-contact type: optical type and magnetic type. The magnetic type rotation detection device has more dust and moisture than the optical type rotation detection device. There is an advantage that it can be used in an environment or in a liquid. That is, a magnetic rotation detection device generally includes a magnet body in which a magnetic pole pair composed of an S pole and an N pole is formed, and a magnetosensitive element that detects an angular position and a rotation speed when the magnet body rotates. Even if dust or moisture adheres to the magnet body, the sensitivity does not decrease. In such a magnetic rotation detection device, for example, a plurality of magnetic pole pairs composed of an S pole and an N pole are formed on the outer peripheral surface of the magnet body, and a magnetosensitive element is disposed at a position facing the outer peripheral surface of the magnet body. (See Patent Document 1).

JP 2008-151774 A

  On the other hand, the magnetic rotation detector has a problem that it is more susceptible to disturbances such as electrical noise and magnetic noise than an optical type.

  In view of the above problems, it is an object of the present invention to provide a magnetic rotation detection device that is not easily affected by disturbance.

  In order to solve the above-described problems, in the present invention, a magnetic pole pair including a south pole and a north pole is formed, and a magnet body provided on the rotating body side and a magnetosensitive element facing the magnet body are provided. The rotation detection device further includes a case that houses the magnetosensitive element therein, and the case includes a first case body including a partition wall interposed between the magnet body and the magnetosensitive element; A first case body and a second case body that covers the magnetosensitive element, and both the first case body and the second case body have conductivity.

  In the present invention, since both the first case body and the second case body used for the case in which the magnetosensitive element is housed are provided with conductivity, the inside of the case is electrically shielded from the surroundings. is there. In addition, since the conductive first case includes a partition wall interposed between the magnet body and the magnetic sensing element, the case is electrically shielded from the surroundings even on the side where the magnet body is located. Is in a state. Therefore, in the case, since the signal output from the magnetosensitive element is not easily influenced by the electric noise from the surroundings, an error due to the electric noise is not easily generated in the output signal.

  In the present invention, the second case body is preferably made of a magnetic material. According to such a configuration, the magnetosensitive element can be magnetically shielded by the second case body. That is, the magnetosensitive element detects a rotating magnetic field generated from the magnet body. Therefore, if the magnetic sensing element is magnetically shielded by the second case body, the rotating magnetic field generated from the magnet body is less likely to be disturbed, so that the magnetic sensing element can detect the rotating magnetic field without any disturbance.

  In this invention, it is preferable that the said 2nd case body is provided with the plate-shaped part facing the said partition part, and the side-plate part bent to the said 1st case body side from this plate-shaped part. According to this configuration, the entire case is electrically shielded. In addition, since almost the entire surface of the case excluding the partition wall is magnetically shielded, the rotating magnetic field generated from the magnet body is hardly disturbed in the case. Therefore, the magnetosensitive element can detect a rotating magnetic field without disturbance.

  In the present invention, the first case body is preferably made of a nonmagnetic material. According to this configuration, even when the case is used as a magnetic shield and the first case body includes a partition wall interposed between the magnet body and the magnetosensitive element, the magnetic lines of force of the magnet body are applied to the magnetosensitive element. Because it reaches, rotation detection is not hindered.

  In the present invention, it is preferable that a hole communicating with the second case body is formed in the second case body. If comprised in this way, even if it does not remove a 2nd case body from a magnetic type rotation detection apparatus, if a pin-shaped terminal is inserted from the hole of a 2nd case body, offset adjustment etc. will be carried out with respect to the semiconductor IC provided in the case Parameter input and parameter change can be performed. Further, when the second case body is a magnetic body, the characteristics check and adjustment of the magnetic rotation detection device can be performed in a state where the second case body exists, so that the magnetic influence of the second case body is also included. Adjustments can be made.

  In the present invention, since both the first case body and the second case body used for the case in which the magnetosensitive element is housed are provided with conductivity, the inside of the case is electrically shielded from the surroundings. is there. In addition, since the conductive first case has a partition wall interposed between the magnet body and the magnetosensitive element, the case is electrically shielded from the surroundings even on the side where the magnet body is located. It is in. Therefore, in the case, the signal output from the magnetosensitive element is not easily affected by electrical noise from the surroundings.

(A), (b) is the external view of the magnetic-type rotation detection apparatus to which this invention is applied, and its disassembled perspective view. (A), (b) is sectional drawing which shows typically the structure of the principal part of the magnetic-type rotation detection apparatus to which this invention is applied, and explanatory drawing which shows the detection principle. It is an external view of the circuit unit used for the magnetic rotation detection apparatus to which the present invention is applied. (A), (b) is the top view of the circuit unit used for the magnetic rotation detection apparatus to which this invention is applied, and an expanded sectional view when a circuit unit is cut | disconnected by the AA 'line. It is explanatory drawing which looked at a mode that the circuit unit of the magnetic type rotation detection apparatus to which this invention was applied was decomposed | disassembled from the 1st case body side. It is explanatory drawing which looked at a mode that the circuit unit of the magnetic type rotation detection apparatus to which this invention was applied was decomposed | disassembled from the 2nd case body side. It is explanatory drawing which shows the manufacturing method of the magnetic-type rotation detection apparatus to which this invention is applied.

  Below, with reference to drawings, the magnetic rotation detection apparatus of this invention and its manufacturing method are demonstrated.

(Overall configuration of magnetic rotation detector)
1A and 1B are an external view and an exploded perspective view of a magnetic rotation detector to which the present invention is applied. 2A and 2B are a cross-sectional view schematically showing a configuration of a main part of a magnetic rotation detection apparatus to which the present invention is applied, and an explanatory view showing the detection principle.

  A magnetic rotation detection device 10 shown in FIGS. 1A, 1B, and 2A is a device that magnetically detects the rotation position, rotation direction, and rotation speed of a rotating body. The rotation of the rotating shaft 22 of the motor 2 is detected. In this embodiment, the rotation of the rotating shaft 22 is detected based on the motor case 27. Here, the magnetic rotation detection device 10 is configured integrally with the motor 2 and constitutes the motor 1 with an encoder. The rotating shaft 22 corresponds to the opposite end portion of the output shaft 28 of the motor 2.

  The magnetic rotation detection device 10 includes a magnet body 20 fixed to the rotation shaft 22 of the motor 2, and a circuit unit 30 in which a substrate 40 on which a magnetosensitive element 42 and a semiconductor IC 46 are mounted is incorporated in a case 33. The magnetosensitive element 42 faces the magnet body 20 in the direction of the rotation center axis L of the rotation shaft 22. In this embodiment, the magnetosensitive element 42 is composed of an MR element, and the magnetoresistive film 421 is arranged in a predetermined pattern.

  The magnet body 20 includes a metal magnet holder 21 fixed to the rotating shaft 22 and a disk-shaped permanent magnet 25, and the permanent magnet 25 has a diameter enlarged at the tip of the shaft portion 211 of the magnet holder 21. Is fixed to the upper surface of the flange portion 213 by an adhesive. Here, as shown in FIGS. 1B and 2B, the permanent magnet 25 has a pair of S and N poles magnetized in the circumferential direction on the surface facing the magnetosensitive element 42.

  In the magnetic rotation detection device 10 configured as described above, the case 33 of the circuit unit 30 is fixed to the motor case 27 via the spacer 50 having a rectangular parallelepiped shape. That is, the spacer 50 is fixed to the end surface of the motor case 27 by the two bolts 59 as the fastening members at the diagonal position, and the case 33 is fixed to the end surface of the spacer 50 by the two bolts 39 at the diagonal position. Has been.

  Although the outer shape of the spacer 50 used in this embodiment is a rectangular parallelepiped shape, a circular through hole 51 opened in the direction of the rotation center axis L of the rotating shaft 22 is formed, and the magnet body 20 is placed in the through hole 51. To position. The inner diameter dimension of the through hole 51 is larger than the outer diameter dimension of the flange portion 213 of the magnet body 20, and an annular gap is formed between the inner peripheral surface of the through hole 51 and the outer peripheral surface of the magnet body 20. Is formed. The end of the ring 15 held by the circuit unit 30 is inserted into the gap. The outer diameter of the ring 15 is substantially the same as the inner diameter of the through hole 51, and the ring 15 is in a state of being fitted in the through hole 51. In this state, a gap is interposed between the outer peripheral surface of the flange portion 213 of the magnet body 20 and the inner peripheral surface of the ring 15. In this way, the ring 15 is positioned in the radial direction with respect to the spacer 50.

  In the circuit unit 30, a rotation detection circuit constituted by a semiconductor IC 46 to be described later includes a pair of amplifier circuits 481 that output signals from the magnetosensitive element 42 and these amplifier circuits 481, as shown in FIG. An arithmetic circuit 482 (interpolation circuit) that obtains a zero-cross point by performing an interpolation process on the output sine wave signals sin and cos and an output interface 483, and a signal output from the rotation detection circuit to the outside, This is done via a female connector 48 mounted on the substrate 40.

(Configuration of circuit unit)
FIG. 3 is an external view of a circuit unit used in a magnetic rotation detector to which the present invention is applied. 4A and 4B are a plan view of a circuit unit used in a magnetic rotation detector to which the present invention is applied, and an enlarged cross-sectional view when the circuit unit is cut along the line AA ′. FIG. 5 and FIG. 6 are an explanatory diagram viewed from the side of the first case body and an explanatory diagram viewed from the side of the second case body, in which the circuit unit of the magnetic rotation detector to which the present invention is applied is disassembled.

  As shown in FIGS. 3, 4 (a), (b), FIG. 5, and FIG. 6, in the magnetic rotation detection device 10 of the present embodiment, the circuit unit 30 has a case in which the magnetosensitive element 42 is housed. 33. The case 33 includes a first case body 31 located on the magnet body 20 side with respect to the substrate 40, and a second case body 32 located on the opposite side of the magnet body 20 with respect to the substrate 40, The first case body 31 constitutes a partition member interposed between the magnet body 20 and the magnetosensitive element 42.

  The first case body 31 includes a substantially pentagonal plate-like portion 315, and four side plate portions 316 erected from the outer peripheral end of the plate-like portion 315 toward the second case body 32. A part of the plate-like portion 315 stands up at an inner position from the outer peripheral end portion. The plate-like portion 315 is formed with a circular recess 318 that is recessed from the plate-like portion 315 toward the outer surface where the magnet body 20 is located. The bottom 318a of the recess 318 is thinner than the portion of the plate-like portion 315 other than the recess 318, and constitutes a partition wall interposed between the magnet body 20 and the magnetosensitive element 42. .

  As shown in FIG. 4B, the annular inner peripheral wall 318g of the recess 318 has a conical surface inclined so as to reduce the inner diameter of the recess 318 from the opening edge 318h of the recess 318 toward the bottom 318a. . In this embodiment, a region surrounded by the side plate portion 316 is an arrangement space for the substrate 40, and the substrate 40 is supported by a portion surrounded by the side plate portion 316 on the inner surface of the plate-like portion 315. In this embodiment, the substrate 40 is supported in a posture facing the plate-like portion 315 by a plurality of protrusions 315s (substrate receiving portions) formed on the plate-like portion 315. The plate-like portion 315 is formed with holes 315k through which the bolts 39 shown in FIG. Further, a semi-cylindrical projection 315p is formed at a corner portion of the plate-like portion 315 that is connected to the side plate portion 316. The projection 315p abuts on the outer peripheral edge of the substrate 40 to bring the substrate 40 in the in-plane direction. Responsible for positioning.

  In the present embodiment, the first case body 31 is a resin molded product such as PPS. However, in this embodiment, the first case body 31 is made of a conductive resin molded product filled with a conductive filler.

  The substrate 40 has a magnetosensitive element 42 mounted at the approximate center on the surface side facing the magnet body 20. Further, on the back side of the substrate 40, the semiconductor IC 46 and the female connector 48 that constitute the rotation detection circuit described with reference to FIG. 2B are mounted. The female connector 48 includes the plate-like portion 315. Among them, it is mounted near the side where the side plate portion 316 is not formed. The substrate 40 configured as described above is received by the plate-like portion 315 when it is disposed in the first case body 31. As a result, the magnetic sensitive element 42 is located inside the recess 318. Therefore, the magnetic sensitive element 42 can be brought close to the magnet body 20. In this state, a gap is interposed between the magnetosensitive element 42 and the bottom 318a of the recess 318, and the magnetosensitive element 42 and the bottom 318a of the recess 318 are in a non-contact state.

  In the first case body 31, a circular annular groove 319 is formed on the outer surface side where the magnet body 20 is located in the plate-like portion 315 so as to surround the bottom portion 318 a of the recess 318, and in the annular groove 319, An end of the annular ring 15 is fitted and fixed by a method such as adhesion. Only the end of the ring 15 opposite to the side where the magnet body 20 is located (the side where the magnetic sensing element 42 is located) is fitted in the annular groove 319, and the opposite end is the bottom of the recess 318. It protrudes to the side where the magnet body 20 is located from 318a.

  The inner diameter dimension of the ring 15 is slightly larger than the outer diameter dimension of the magnet body 20 shown in FIG. The permanent magnet 25 and the flange portion 213 of the magnet body 20 are located inside the ring 15 configured as described above, and in this state, the ring 15 is disposed on the outer peripheral surface of the magnet body 20 in the radial direction outside via a gap. Opposite states. The ring 15 is made of a magnetic material and has a function of performing a magnetic shield on the magnet body 20. Further, in the magnetic rotation detection device 10 of the present embodiment, the centers of the magnet body 20 and the magnetosensitive element 42 are aligned with the ring 15 as a reference, as will be described later. For this reason, the center of the magnetosensitive element 42 is located on the center axis of the ring 15, and the center of the magnet body 20 is located on the center axis of the ring 15.

  The second case body 32 includes a plate-like portion 325 facing the plate-like portion 315 of the first case body 31, and the outer shape of the plate-like portion 325 substantially overlaps the side plate portion 316 of the first case body 31. It has a shape. In the second case body 32, the side plate portion 326 stands up from the outer peripheral end of the plate-like portion 325 toward the side plate portion 316 of the first case body 31, and the second case body is in relation to the first case body 31. When 32 is covered, the side plate portion 316 and the side plate portion 326 overlap in the inner and outer directions so that the side plate portion 316 is positioned outside the side plate portion 326. Here, the protruding dimension (height dimension) of the side plate part 326 from the plate-like part 325 is shorter than the protruding dimension (height dimension) of the side plate part 316 from the plate-like part 315. For this reason, the side plate portion 326 of the second case body 32 does not reach the plate-like portion 315 of the first case body 31 in a state where the second case body 32 is covered with the first case body 31, and the side plate portion 326. There is a gap between the lower end of the plate and the plate-like portion 315.

  In the plate-like portion 325 of the second case body 32, a protrusion 325 t is formed at a portion where the end portion of the side plate portion 326 is interrupted, and when the second case body 32 is covered with the first case body 31, the protrusion 325t is hooked on the side plate portion 326 so as to ride on the upper end portion of the side plate portion 326. Therefore, even when a structure in which the second case body 32 is dropped inside the first case body 31 is employed, the height position of the second case body 32 is defined. When the second case body 32 is covered with the first case body 31 in this way, a part of the first case body 31 and the second case body 32 are opened sideways. It becomes. Accordingly, the female connector 48 is exposed to the outside. In the second case body 32, the side plate portion 326 is interrupted at a portion other than the side where the female connector 48 is disposed. However, the interrupted portion of the side plate portion 326 is blocked by the side plate portion 316 of the first case body 31. Will be removed.

  Here, on the inner peripheral surface of the side plate portion 316 of the first case body 31, a plurality of shallow recesses 316c are formed from a midway position in the height direction to the upper edge, while the side plate portion of the second case body 32 is formed. The outer surface of 326 is flat. For this reason, when the second case body 32 is covered with the first case body 31, a narrow gap 33g is formed between the side plate portion 316 and the side plate portion 326, and a wide gap opened upward by the recess 316c. Is formed. Accordingly, when the sealing adhesive 33f is poured into a narrow gap between the side plate portion 316 and the side plate portion 326, the recess 316c functions as a reservoir portion of the adhesive 33f. Accordingly, if the adhesive 33f is solidified, the first case body 31 and the second case body 32 can be joined to form the case 33, and the adhesive between the side plate portion 316 and the side plate portion 326 can be formed. It can be reliably blocked by 33f. Therefore, the case 33 has a waterproof performance. At this time, the lower end portion of the side plate portion 326 of the second case body 32 is also fixed to the side plate portion 316 of the first case body 31 with the adhesive 33f, but the lower end portion of the side plate portion 326 and the plate shape of the first case body 31 are also fixed. There is a gap between the part 315 and the part 315. Therefore, the second case body 32 is not lifted by the adhesive 33f that has entered between the lower end portion of the side plate portion 326 and the plate-like portion 315, so that the second case body 32 is accurately positioned at a predetermined height. Fixed. The interrupted portion of the side plate portion 326 is blocked only by the side plate portion 316, but in such a portion, the sealing material is provided between the upper end edge of the side plate portion 316 and the end portion of the plate-like portion 325 of the second case body 32. If the is applied, the waterproof performance of the case 33 can be ensured.

  In the present embodiment, the second case body 32 is entirely made of a metal made of an iron-based magnetic material, and has conductivity. The first case body 31 is also conductive. For this reason, if the 1st case body 31 and the 2nd case body 32 are made to contact in any one part, the 1st case body 31 and the 2nd case body 32 will be in the state which is electrically connected. That is, in this embodiment, a wiring material or the like is connected from the first case body 31 or the second case body 32 to the substrate 40, the motor case 27 (see FIG. 1), or a motor frame (not shown) fixed to the motor case 27. Then, it is possible to conduct to the ground. For this reason, the electric noise that tries to enter the case 33 from the outside flows through the first case body 31 and the second case body 32 to the ground via the wiring material. Therefore, it is possible to protect the semiconductor IC 46 and the magnetosensitive element 42 constituting the rotation detection circuit described with reference to FIG. 2B from electrical noise. The signal is less susceptible to electrical noise from the surroundings. Therefore, the magnetic rotation detection device 10 can perform desired detection without being affected by disturbance noise. Further, the side of the magnetic sensitive element 42 where the substrate 40 is located is covered with the plate-like portion 325 of the second case body 32 and is magnetically shielded.

  In this embodiment, the plate-like portion 325 of the second case body 32 is formed with an oval or perfect circle hole 325h. The hole 325h communicates with the inside of the case 33 and opens at a position overlapping the semiconductor IC 46 mounted on the substrate 40, the wiring pattern of the substrate 40, and the like. For this reason, from the hole 325h, the terminal of the semiconductor IC 46 mounted on the substrate 40, the wiring of the substrate 40, etc. can be seen. Therefore, in the circuit unit 30 of this embodiment, as shown in FIG. 1A, even after the magnetic rotation detector 10 is mounted on the motor 2, if the pin-like terminal is inserted from the hole 325h, the semiconductor IC 46 On the other hand, it is possible to perform parameter input or parameter change for offset adjustment or the like. That is, in the case of the magnetic rotation detection device 10 according to the present embodiment, the circuit unit 30 and the magnet body 20 are completed with the motor 2 mounted thereon, so that the characteristics are obtained only after the circuit unit 30 and the magnet body 20 are mounted on the motor 2. Although the check cannot be performed, in the magnetic rotation detection device 10 of the present embodiment, since the hole 325h is formed in the plate-like portion 325 of the second case body 32, even if the second case body 32 is not removed, Parameters can be input or changed for the semiconductor IC 46. Therefore, it is possible to input or change parameters for the semiconductor IC 46 while monitoring the magnetic rotation detection device 10 mounted on the motor 2 while the second case body 32 is provided. Adjustment can be performed in the state of the finished product in which the influence of the second case body 32 made of a body exists.

  In addition, after the characteristic check and the input and change of the parameters for the semiconductor IC 46 are performed, a sheet 99 such as a seal is pasted and the hole 325h is closed as shown by a one-dot chain line L99 in FIG. No foreign matter enters inside 33.

(Manufacturing method of magnetic rotation detector 10)
FIG. 7 is an explanatory view showing a method for manufacturing the magnetic rotation detector 10 to which the present invention is applied. In order to manufacture the magnetic rotation detection device 10 of this embodiment, first, the ring 15 is fixed to the first case body 31 before being coupled to the second case body 32 in the first alignment step, and the ring 15 After aligning the ring 15 and the magnetosensitive element 42 so that the center of the magnetosensitive element 42 is positioned on the center axis of the substrate 40, the substrate 40 is fixed to the first case body 31. More specifically, for example, each of the two robot hands holds the ring 15 and the substrate 40, and after adjusting the positions thereof, the substrate 40 is fixed to the first case body 31. At this time, the substrate 40 is temporarily bonded to the first case body 31 using a quick-drying adhesive such as UV adhesive, and then the substrate 40 is bonded to the first case body 31 using an adhesive made of a thermosetting resin. Glue. Thereafter, the first case body 31 is covered with the second case body 32, and the small groove 315e of the second case body 32 is fitted into the small hole 315e of the first case body 31 and fixed. After the sealing agent 35 is applied to the groove portion 37, it is solidified and the case 33 is sealed.

  Next, in the second alignment step, the ring 15 and the magnet body 20 are aligned so that the center of the magnet body 20 is positioned on the center axis of the ring 15. First, as shown in FIGS. 7A and 7E, after the rotating shaft 22 of the motor 2 is fitted in the hole formed in the end portion of the shaft portion 211 of the magnet holder 21, the shaft portion 211 A set screw 219 is fitted into a hole formed in the peripheral surface from the side to restrict movement in the rotation direction, and the magnet body 20 is fixed to the rotating shaft 22. Next, as shown in FIGS. 7B and 7E, the spacer 50 is disposed on the end surface of the motor case 27 so that the magnet body 20 enters the through hole 51 of the spacer 50 (first operation).

  Next, as shown in FIGS. 7C and 7E, the cylindrical portion 61 of the jig 60 is inserted between the inner wall of the through hole 51 of the spacer 50 and the outer peripheral surface of the magnet body 20, and the jig 60 is interposed therebetween. The spacer 50 and the magnet body 20 are aligned (second operation). That is, the jig 60 includes a cylindrical portion 61 having a constant thickness in the circumferential direction, and the inner diameter of the cylindrical portion 61 is substantially the same as the outer dimensions of the flange portion 213 of the magnet body 20 and the permanent magnet 25. The inner diameter of the through hole 51 of the spacer 50 is substantially the same. Accordingly, in the state shown in FIGS. 7C and 7E, the through hole 51 of the spacer 50, the flange portion 213 of the magnet body 20, and the permanent magnet 25 are arranged concentrically.

  Next, as shown in FIG. 7D, after fixing the spacer 50 to the motor case 27 with the bolt 59, the jig 60 is removed (third operation).

  After that, after inserting the ring 15 of the circuit unit 30 into the through hole 51 of the spacer 50, the case 33 of the circuit unit 30 is fixed to the spacer 50 by the bolt 39 (fourth operation). As a result, the magnetic rotation detection device 10 is assembled in a state where the ring 15 and the magnet body 20 are aligned so that the center of the magnet body 20 is positioned on the center axis of the ring 15.

(Main effects of this form)
As described above, in the magnetic rotation detection device 10 of the present embodiment, the ring 15 is fixed to the plate-like portion 315 of the first case body 31 interposed as a partition member between the magnet body 20 and the magnetic sensing element 42. The positions of the magnet body 20 and the magnetic sensing element 42 are determined based on the ring 15. That is, in the method of manufacturing the magnetic rotation detection device 10, the position of the magnetic sensing element 42 on the first case body 31 is determined with reference to the ring 15, and the spacer 15 and the jig 60 are used as a reference. The positions of the magnetosensitive element 42 and the magnet body 20 are determined. Therefore, the positional accuracy between the magnetosensitive element 42 and the magnet body 20 is high.

  Further, when the ring 15 is fixed to the first case body 31, the ring 15 is fitted in the annular groove 319 surrounding the recess 318, so that the ring 15 is securely fixed to a predetermined position of the first case body 31. can do.

  Further, in the magnetic rotation detection device 10 of this embodiment, the number of magnetic pole pairs formed in the magnet body 20 is reduced, and instead, for example, interpolation processing is performed on the signal obtained by the magnetosensitive element 42 to obtain a zero cross point. The resolution is ensured by performing arithmetic processing such as obtaining. According to such a configuration, the number of magnetic pole pairs formed on the magnet body 20 is reduced to a minimum of a pair, so that sufficient sensitivity is provided even if the magnet body 20 and the magnetosensitive element 42 are somewhat separated. Moreover, since the magnet body 20 and the magnetosensitive element 42 are opposed to each other in the direction of the rotation center axis L of the rotary shaft 22, even if the magnet body 20 and the magnetosensitive element 42 are somewhat separated from each other, the magnetosensitive element A sine wave signal with little waveform distortion can be obtained via the line 42. Therefore, a partition wall (the bottom 318 a of the recess 318 of the first case body 31) can be provided between the magnet body 20 and the magnetic sensing element 42.

  Further, the partition wall portion is a bottom portion 318 a of a recess portion 318 that is recessed toward the side where the magnet body 20 is located in the plate-like portion 315, and the magnetosensitive element 42 is disposed in the recess portion 318. For this reason, although there is a limit in making the whole plate-shaped part 315 thin in the 1st case body 31, the magnetosensitive element 42 and the magnet body 20 can be made to approach. Further, since the magnetic sensitive element 42 is spaced from the bottom 318a of the recess 318, the magnetic sensitive element 42 can be disposed in a non-contact state on the partition wall (the bottom 318a of the concave 318). Therefore, even when the magnetosensitive element 42 and the magnet body 20 are brought close to each other, no extra stress is applied to the magnetosensitive element 42, so that the magnetosensitive element 42 exhibits high sensitivity.

  Further, since the ring 15 is made of a magnetic material, it functions as a magnetic shield portion for the magnet body 20. In addition, since the second case body 32 is also made of a magnetic material, it functions as a magnetic shield portion for the magnetosensitive element 42. In addition, since the second case body 32 includes the plate-like portion 325 and the side plate portion 326, the magnetic sensing element 42 is in a state in which substantially the entire periphery is magnetically shielded. Therefore, since it is not easily affected by magnetic noise in the case 33, the semiconductor IC 46 and the magnetosensitive element 42 constituting the rotation detection circuit described with reference to FIG. 2B can be used without using a dedicated shield member. Can be protected from magnetic noise. In particular, the magnetic sensing element 42 detects a rotating magnetic field generated from the magnet body 20. Therefore, if the magnetic sensing element 42 is magnetically shielded by the second case body 32, the rotating magnetic field generated from the magnet body 20 is less likely to be disturbed, so that the magnetic sensing element 42 can detect a rotating magnetic field without any disturbance. It becomes.

  Further, since the first case body 31 is non-magnetic, even if the partition wall portion (the bottom portion 318a of the recess 318) of the first case body 31 is interposed between the magnet body 20 and the magnetic sensing element 42, the magnet The first case body 31 does not prevent the magnetic field lines from moving from the body 20 to the magnetic sensing element 42, and there is no hindrance to rotation detection. Further, the second case body 32 opposite to the side where the magnet body 20 is located with respect to the magnetic sensing element 42 is made of a magnetic material. For this reason, since the magnetic force lines of the magnet body 20 can be efficiently guided to the side where the second case body 32 is located, that is, the side where the magnetosensitive element 42 is located, the detection sensitivity of the magnetic rotation detection device 10 is improved. There is an advantage that you can.

  In addition, since both the first case body 31 and the second case body 32 have conductivity, the inside of the case 33 is electrically shielded. For this reason, it is possible to protect the semiconductor IC 46 and the magnetosensitive element 42 constituting the rotation detection circuit described with reference to FIG. In addition, since the second case body 32 includes the plate-like portion 325 and the side plate portion 326, the semiconductor IC 46 and the magnetosensitive element 42 are in a state where substantially the entire periphery is electrically shielded. For this reason, the signal output from the magnetosensitive element 42 is not easily affected by electrical noise. In addition, since the first case body 31 includes a partition wall (the bottom 318a of the recess 318) interposed between the magnet body 20 and the magnetic sensing element 42, the semiconductor IC 46 and the magnetic sensing element 42 are completely surrounded. It is in an electrically shielded state. Therefore, the signal output from the magnetosensitive element 42 is not easily affected by electrical noise, and thus has high detection sensitivity.

  Further, the second case body 32 is formed with a hole 325 h communicating with the inside of the case 33. For this reason, even if the second case body 32 is not removed from the magnetic rotation detection device 10, if a pin-like terminal is inserted from the hole of the second case body 32, a soft IC is provided for the semiconductor IC 46 provided in the case 33. Downloading can be performed, and parameter input and parameter change for offset adjustment and the like can be performed. In addition, since the characteristic check and adjustment of the magnetic rotation detector 10 can be performed in the state where the second case body 32 made of a magnetic material exists, adjustment including the magnetic influence of the second case body 32 can be performed. Can be done.

[Other embodiments]
In the above embodiment, the rotating body is the rotating shaft 22 of the motor 2 and the stationary body is the motor case 27. However, the magnet body 20 is formed on the rotating body of another rotating mechanism, and the stationary body supports the rotating body. The circuit unit 30 may be attached to the body via the spacer 50. Note that “stationary” in the stationary body means to confront “rotation” of the rotating shaft 22, and includes the case where the stationary body itself moves together with the rotating shaft 22. Further, the stationary body may be a member other than the motor case 27, for example, a part of a device on which the motor 2 is mounted.

  In the above embodiment, the permanent magnet 25 is formed with a pair of S poles and N poles, but the present invention may be applied when a plurality of pairs of S poles and N poles are formed.

  In the above-described embodiment, the positioning using the ring 15 is applied in the case of two case bodies. However, for the positioning using the ring 15, the substrate 40 on which the magnetosensitive element 42 is mounted is made of a resin having a small stress, For example, the present invention may be applied to a structure in which a short glass fiber is integrally molded with a BMC resin mixed with a reinforcing agent or a filler in a thermosetting resin mainly composed of an unsaturated polyester resin. In this case, the partition member is formed by the portion covering the magnetic sensitive element 42 in the mold resin.

DESCRIPTION OF SYMBOLS 1 Motor with encoder 2 Motor 10 Magnetic rotation detector 15 Ring 20 Magnet body 22 Rotating shaft (rotating body) of motor
25 Permanent magnet 27 Motor case (stationary body)
40 Substrate 42 Magnetosensitive element 30 Circuit unit 31 First case body 32 Second case body 33 Case 315, 325 Plate portion 316, 326 Side plate portion 318 First case body recess 318a First case body recess bottom (partition wall) Part)

Claims (5)

A magnetic pole pair composed of an S pole and an N pole is formed, and a magnet body provided on the rotating body side;
A magnetosensitive element facing the magnet body;
In a magnetic rotation detection device having
Furthermore, it has a case that houses the magnetosensitive element inside,
The case includes a first case body having a partition wall interposed between the magnet body and the magnetic sensing element, and a second case body that covers the magnetic sensing element together with the first case body,
Both the first case body and the second case body have electrical conductivity.   The magnetic rotation detection device according to claim 1, wherein the second case body is made of a magnetic material.   The said 2nd case body is equipped with the plate-shaped part which opposes the said partition part, and the side-plate part bent to the said 1st case body side from this plate-shaped part, The Claim 1 characterized by the above-mentioned. 3. A magnetic rotation detector according to 2.   The magnetic rotation detection device according to claim 1, wherein the first case body is made of a nonmagnetic material.   5. The magnetic rotation detection device according to claim 1, wherein a hole communicating with the second case body is formed in the case.

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