JP2011107085A - Moving object detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a variation of a bias magnetic field caused by a variation of a relative position between and among a magneto-sensing element, a bias magnet and a yoke, thereby reducing a variation of the maximum detection distance of each product. <P>SOLUTION: A moving object detection device holds, by a holding member, a Hall IC 10 with a built-in Hall element, the bias magnet 40, and the yoke 60 disposed between and among the Hall IC, the bias magnet, and the yoke 60 which is configured to face a magnetic pole surface of the bias magnet 40, and has a length in the x-direction of the yoke 60 longer than that in the x-direction of the magnetic pole surface of the bias magnet 40. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a detection device that detects a change in a magnetic field, and in particular, a detection target moving body that moves linearly or rotates, such as a rack or gear made of a soft magnetic material used in an engine of an industrial machine tool or an automobile, for example. The present invention relates to a moving body detection apparatus suitable for use in magnetically detecting a moving state.

  Bias magnet that is a permanent magnet for magnetically detecting the moving state of a moving object to be detected that moves linearly or rotates, such as racks and gears of soft magnetic materials used in industrial machine tools, automobile engines, etc. Thus, there is a moving body detection apparatus that utilizes the characteristic that the output signal of the magnetosensitive element changes when the soft magnetic body approaches the magnetosensitive element to which a bias magnetic field is applied.

  In such a moving body detection apparatus, a yoke having the same area and shape as the magnetic pole surface of the bias magnet is arranged between the magnetic sensing element and the bias magnet to attempt to smooth the bias magnetic field applied to the magnetic sensing element. The one is known (see Patent Document 1 below).

Japanese Patent No. 3469707

  In the case of the conventional example of Patent Document 1, due to the assembly error of those parts to the holding member (for example, the housing shell of the sensor package) holding the magnetosensitive element, the bias magnet, and the yoke, or the product variation of the holding member itself, There is a problem that the bias magnetic field applied to the magnetosensitive element fluctuates, resulting in individual differences in the maximum detection distance (maximum distance at which the movement of the detection target moving body can be detected) as a product when assembled as a moving body detection device. there were.

  The present invention has been made in view of such a situation, and its purpose is to suppress fluctuations in the magnetic field caused by variations in the positions of the magnetosensitive element, permanent magnet and yoke, and to reduce product variations in the maximum detection distance. It is an object of the present invention to provide a moving body detection apparatus capable of achieving the above.

A first aspect of the present invention is a moving body detection apparatus. The moving body detection apparatus includes a magnetic sensing element, a permanent magnet, and a yoke disposed between the magnetic sensing element and the permanent magnet.
The yoke faces the magnetic pole surface of the permanent magnet, and the length of the yoke in the same direction is larger than the length of the magnetic pole surface of the permanent magnet in a specific direction.

  In the first aspect, the length of the yoke in the specific direction may be 1.2 times or more the length of the magnetic pole surface in the specific direction.

The second aspect of the present invention is a moving body detection apparatus. The moving body detection apparatus includes two magnetic sensing elements, a permanent magnet, and a yoke disposed between the two magnetic sensing elements and the permanent magnet.
The yoke faces the magnetic pole surface of the permanent magnet,
The length of the yoke in the same direction is larger than the length of the magnetic pole surface in the linear direction connecting the two magnetosensitive elements.

  In the second aspect, the length of the yoke in the linear direction connecting the two magnetosensitive elements may be 1.2 times or more of the length in the same direction of the magnetic pole surface.

  In the first or second aspect, a holding member that holds the magnetosensitive element, the permanent magnet, and the yoke may be provided, and the holding member may have an insertion hole into which the permanent magnet and the yoke are inserted.

  The magnetosensitive element may be a surface mount type magnetosensitive element, and may be fixed to a substrate, and the substrate may be held by the holding member.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  According to the moving body detection apparatus of the present invention, by devising the yoke shape of the soft magnetic body, the magnetic field fluctuation at the position of the magnetic sensitive element due to the variation in the positions of the magnetic sensitive element, the permanent magnet and the yoke is suppressed. As a result, it is possible to reduce the product variation of the maximum detection distance.

  In addition, even if vibration or impact is applied during use and the mutual positional relationship of the magnetosensitive element, permanent magnet, and yoke changes, it is possible to suppress fluctuations in the applied magnetic field to the magnetosensitive element. In addition, malfunction caused by vibration and impact can be suppressed.

It is a principal part structure of the moving body detection apparatus which concerns on the 1st Embodiment of this invention, (A) is an exploded perspective view, (B) assembled | attached the Hall IC as a bias magnet, a yoke, and a magnetosensitive element. FIG. 1 is a side sectional view showing an overall configuration of a moving object detection apparatus according to a first embodiment of the present invention. The position (sensing point) of one Hall element built in the Hall IC and the arrangement of a bias magnet and a yoke facing the Hall element, wherein (A) shows a yoke having the same area and shape as the magnetic pole surface of the bias magnet. The front view in the case of the conventional example arranged in an overlapping manner, (B) is the same plan view, (C) is an overlapping yoke having a larger area than the magnetic pole face of the bias magnet (or longer than the length of the magnetic pole face in a specific direction). The front view in the case of 1st Embodiment arrange | positioned and (D) is the same top view. The position (sensing point) of the two Hall elements built in the Hall IC and the arrangement of the bias magnet and the yoke opposite to each other, (A) shows a yoke having the same area and shape as the magnetic pole surface of the bias magnet. The front view in the case of the conventional example arranged in an overlapping manner, (B) is the same plan view, (C) is an overlapping yoke having a larger area than the magnetic pole face of the bias magnet (or longer than the length of the magnetic pole face in a specific direction). The front view in the case of 1st Embodiment arrange | positioned and (D) is the same top view. It is a principal part structure of the moving body detection apparatus which concerns on the 2nd Embodiment of this invention, Comprising: (A) is a disassembled perspective view, (B) is a perspective view after attaching a bias magnet and a yoke, (C). FIG. 3 is a perspective view after assembling a substrate on which a Hall IC is further mounted. It is a whole structure of the moving body detection apparatus concerning the 2nd Embodiment of this invention, Comprising: (A) is the top view which abbreviate | omitted the lead wire before filling with sealing resin, (B) is a sectional side view. It is an illustration of a yoke shape arranged so as to overlap a bias magnet, and (A-1) is a plane of a conventional example (model: Y05) using a square plate-like yoke having the same area and shape as the magnetic pole surface of the bias magnet. (A-2) is the same front view, (B-1) is a strip (rectangular plate) on both sides in the x direction, in addition to the square plate portion whose length in the xy direction is the same as the length of the magnetic pole surface of the bias magnet. Model) using a yoke whose x-direction length is larger than the magnetic pole surface by having a protruding portion of (shape): a plan view of YMA1, (B-2) is the front view, and (C-1) is xy In addition to a square plate-like portion whose length in the direction is the same as the length of the magnetic pole surface of the bias magnet, a longer strip (rectangular plate-shaped) protruding portion is provided on both sides in the x direction so that the length in the x direction is the magnetic pole surface. Model with larger yoke: Plan view of YMA2, (C-2) The same front view, (D-1) shows that the length in the xy direction is the same as the length of the magnetic pole surface of the bias magnet, and in addition to the triangular plate-like protrusions on both sides in the x direction, Model using a yoke whose length is larger than the magnetic pole surface: a plan view of YMB1, (D-2) is the front view, and (E-1) is the length of the magnetic pole surface of the bias magnet in the xy direction. A model using a yoke having an arc plate-like protruding portion on both sides in the x direction in addition to a square plate portion having the same length as that of the yoke whose x direction length is larger than the magnetic pole surface: YMC1 plan view; (E-2) is the same front view, and (F-1) is a rectangular plate-shaped yoke whose length in the y direction is shorter than the length of the magnetic pole surface of the bias magnet and whose length in the x direction is larger than the magnetic pole surface. Model used: Plan view of YMD1, (F-2) is the same front view, (G-1) is A plan view of a conventional example (model: YC05) using a disk-shaped yoke having the same area and shape as the magnetic pole surface of the magnet, (G-2) is the front view, and (H-1) is the bias magnet. A plan view of a model (YC07) using a disk-shaped yoke having a diameter larger than that of the magnetic pole surface, and (H-2) is a front view thereof. The simulation results for each yoke shape when there is no center shift (center position shift) between the bias magnet and the yoke, (A) is a conceptual diagram of the simulation model, and (B) is the yoke and bias magnet shape of each model Y00-Y11. Table showing relationship between dimensions, element (sensing point) -magnet interval (in the case of Y00), and element-yoke interval (Y01-Y11), (C) is the x-direction position and z-direction for each model Y00-Y11 The Bz distribution map according to yoke shape which shows the relationship with magnetic flux density Bz. In the case where there is a center shift between two elements (for example, a Hall IC incorporating two Hall elements) and the yoke (no shift between the bias magnet and the yoke), (A) shows two element positions (2 (B) is a table showing ΔBz and | ΔBz | of each model Y00 to Y11, and (C) is an x-direction yoke width and ΔBz of Y00 to Y11. The graph which shows the relationship. The position in the x direction and the magnetic flux in the z direction for each model Y01S to Y11S (the yoke center of Y01 to Y11 is shifted by 0.5 mm in the x direction with respect to the bias magnet center) when there is a center deviation between the bias magnet and the yoke The Bz distribution map according to yoke shape which shows the relationship with density Bz. A center deviation exists between the bias magnet and the yoke, and a center deviation exists between the two elements (for example, a Hall IC incorporating two Hall elements) and the yoke, and (A) is a bias magnet, Front view showing an example of the positional deviation of the yoke and the element (sensing point), (B) is the same plan view, (C) is the deviation of ΔBz and | ΔBz | of each model Y00S to Y11S between the bias magnet and the yoke. (D) shows the relationship between the Y01S to Y11S x-direction yoke width and ΔBz in comparison with the models Y00 to Y11 having no deviation between the bias magnet and the yoke. Graph. Regarding models Y05, Y07, YMA1, YMA2, YMB1, YMC1, YMD1, YC05, and YC07 of various shapes, (A) is a Bz distribution diagram by yoke shape showing the relationship between the x-direction position and the z-direction magnetic flux density Bz. B) is a table showing ΔBz and | ΔBz | for each model when there is a center shift between two elements (for example, a Hall IC incorporating two Hall elements) and a yoke.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  1A and 1B show the main configuration of the mobile object detection device 100 according to the first embodiment of the present invention, and FIG. 2 shows the overall configuration of the mobile object detection device 100, respectively. As shown in these drawings, the moving body detection device 100 includes a case 20 and a holding member 30. The case 20 and the holding member 30 are made of an insulating resin, for example. The holding member 30 is composed of a Hall IC 10 incorporating a Hall element as a magnetosensitive element, a bias magnet 40 that is a permanent magnet for generating a bias magnetic field, and a soft magnetic material that faces (contacts) the magnetic pole surface of the bias magnet 40. The yoke 60 and the substrate 70 are held. The bias magnet 40 is magnetized in the thickness direction, and one magnetic pole surface is an N pole and the other magnetic pole surface is an S pole. The yoke 60 has a shape different from the magnetic pole surface of the bias magnet 40 (for example, an area larger than the magnetic pole surface), and has a portion protruding from the magnetic pole surface, details of which will be described later.

  As shown in FIGS. 1A and 1B, the Hall IC 10 (in this embodiment, having a lead terminal) includes a Hall element and an amplifier that amplifies its output. One or more. And Hall IC10 is located in the recessed part 39 formed in the front-end | tip part of the support part 31 which the holding member 30 has, and is hold | maintained fixedly.

  The support portion 31 of the holding member 30 is formed with an insertion hole 36 including a magnet insertion portion 36a and a yoke insertion portion 36b, and the bias magnet 40 is inserted and held in the magnet insertion portion 36a of the insertion hole 36. 60 is inserted and held in the yoke insertion portion 36b of the insertion hole 36 and is positioned in the vicinity of the Hall IC 10, and applies a bias magnetic field to the Hall IC 10. The opening of the insertion hole 36 is closed by covering the case 20 with the holding member 30 as shown in FIG.

  As shown in FIG. 2, the substrate 70 is supported and fixed on the upper side portion of the support portion 31 (in the vicinity of the Hall IC 10). The lead terminals 11 of the Hall IC 10 are connected to the board 70, and an electronic component (not shown) that protects (processes) the output signal of the Hall IC 10 is mounted (mounted) on the board 70, and an output signal protection (processing) circuit is provided. It is assembled.

  The end portions of the plurality of conductors 50 that are bent and formed in an L shape (insert molding) through the cylindrical plug body portion 32 of the holding member 30 are connected to the substrate 70, respectively, and the tip ends of the conductors 50 are the connectors. The pin 51 protrudes into the inner housing of the connector portion 33 of the holding member 30. The conductor 50 is for leading out the output signal detected by the Hall IC 10 to the outside. The substrate 70 is fixedly supported on the upper side portion of the support portion 31 by passing through the conductor 50 (integrated with the holding member 30) and soldering. The Hall IC 10 is fixedly held in the recess 39 at the tip of the support portion 31 by soldering the terminal 11 to the substrate 70.

  The case 20 has a bottomed cylindrical shape with one end serving as an opening, and is configured to be fitted to the holding member 30. A constricted portion 34 is formed in the cylindrical plug portion 32 of the holding member 30, and an O-ring 35 is attached to the constricted portion 34 as an elastic body for watertight sealing such as rubber. Then, by covering the case 20 on the outside of the cylindrical plug body 32, the inside of the case 20 is watertightly sealed. A flange portion 21 is formed integrally with the case 20, and a bush 22 is fitted and fixed inside the flange portion 21. Further, an O-ring mounting groove 45 is formed on the outer peripheral portion of the case 20 (on the front side of the flange portion 21) in order to mount the moving body detection device 100 on the other side, and a water-tight sealing elastic material such as rubber is formed around the O-ring mounting groove 45. An O-ring 46 as a body is attached.

  3 and 4, the mutual relationship between the sensing point (the position of the Hall element) of the Hall IC 10 and the bias magnet 40 and the yoke 60 will be described.

  FIG. 3 shows a case where a Hall IC incorporating a single Hall element is used. FIGS. 3A and 3B show a configuration corresponding to the conventional example, and a square having the same area and shape as the magnetic pole surface of the bias magnet. Is formed on the magnetic pole surface of the bias magnet. The sensing point of the Hall IC passes through the center 0 in the y direction perpendicular to the x direction of the yoke plane and in the z direction perpendicular to the xy direction. Is located.

  3C and 3D show the case according to the first embodiment, where the length in the x direction is larger than the length of the magnetic pole surface of the bias magnet 40 in the same direction, and the length in the y direction is the magnetic pole surface. A rectangular yoke 60 having the same length in the same direction is overlapped on the magnetic pole surface of the bias magnet 40 so that the centers of the two coincide with each other, and the Hall IC 10 is formed in the z direction passing through the center 0 of the yoke plane. The sensing point is located. In the normal usage method, the x direction faces the moving direction of the outer peripheral surface of the soft magnetic gear 1 shown in FIG.

  As shown in FIG. 2, the moving body detection device 100 is used in a state where the Hall IC 10 is supported so as to face the outer peripheral surface of the soft magnetic gear 1 that is an example of the detection target moving body. The teeth of the gear 1 move in a direction perpendicular to the paper surface. The magnetic field at the sensing point changes depending on whether the gear 1 is close to or far from the sensing point, and this is detected by the Hall element.

  3C and 3D, the fluctuation of the z-direction magnetic flux density at the sensing point due to the mutual displacement of the bias magnet 40, the yoke 60, and the Hall IC 10 in the x-direction compared to the conventional example. Is alleviated. This will be described in a later-described simulation, but is effective in reducing product variations in the maximum detection distance due to the positional deviation.

  FIG. 4 shows a case where a differential Hall IC incorporating two Hall elements is used. FIGS. 4A and 4B show a configuration corresponding to the conventional example, which has the same area and the same area as the magnetic pole surface of the bias magnet. A square-shaped yoke is superimposed on the magnetic pole face of the bias magnet, and passes through the center 0 in the x direction of the yoke plane and the y direction perpendicular to the yoke plane, and in the z direction perpendicular to the xy direction. An intermediate point (two division points) between the two sensing points is positioned.

  4C and 4D show the case according to the first embodiment, where the length in the x direction is larger than the length of the magnetic pole surface of the bias magnet 40 in the same direction, and the length in the y direction is the magnetic pole surface. A rectangular yoke 60 having the same length in the same direction is superposed on the magnetic pole face of the bias magnet so that the centers thereof coincide with each other, and the hall IC 10 2 is placed on the z direction passing through the center 0 of the yoke plane. The middle point (two split points) of the two sensing points is located. The x direction is set parallel to a straight line connecting two sensing points (two Hall elements) of the Hall IC 10. Further, in the normal usage method, the x direction and the linear direction connecting the two sensing points are directed to the moving direction of the outer peripheral surface of the soft magnetic gear 1 shown in FIG.

  As shown in FIGS. 4C and 4D, the yoke length in the direction parallel to the straight line connecting the two sensing points (two Hall elements) (that is, the x direction) is the same as that of the magnetic pole surface of the bias magnet 40. By making it larger than the length in the direction, fluctuations in the z-direction magnetic flux density at the sensing point due to the positional displacement of the bias magnet 40, the yoke 60, and the Hall IC 10 in the x direction are alleviated as compared with the conventional example. This will be described in a simulation described later, but is effective in reducing product variations in the maximum detection distance due to the positional deviation.

  5 (A), (B), and (C) show the main configuration of the moving body detection apparatus 200 according to the second embodiment of the present invention, and FIGS. 6 (A) and 6 (B) show the moving body. The whole structure of the detection apparatus 200 is shown, respectively. As shown in these drawings, the moving body detection device 200 includes a Hall IC 10 (surface-mounted type in this embodiment), a bias magnet 40, and a bias magnet 40 in a case 25 that also serves as a holding member. The yoke 60 facing the magnetic pole surface (contacted) and the substrate 70 are accommodated. The soft magnetic yoke 60 has a shape different from the magnetic pole surface of the bias magnet 40 (for example, an area larger than the magnetic pole surface), and has a portion protruding from the magnetic pole surface.

  The case 25 is made of, for example, insulating resin, has a bottomed structure with one opening, and has a board insertion hole 26 and a magnet / yoke insertion hole 27. The magnet / yoke insertion hole 27 includes a magnet insertion portion 27a and a yoke insertion portion 27b. The bias magnet 40 is inserted and held in the magnet insertion portion 27a of the magnet / yoke insertion hole 27, and the yoke 60 is inserted and held in the yoke insertion portion 27b.

  The Hall IC 10 is surface-mounted and fixed on the substrate 70, and an electronic component (not shown) for protecting (processing) the output signal of the Hall IC 10 is mounted (mounted) to assemble an output signal protection (processing) circuit. ing. A plurality of lead wires 55 are fixed to one end portion of the substrate 70. These lead wires 55 are for leading out an output signal detected by the Hall IC 10 to the outside. The board 70 on which the Hall IC 10, electronic components, lead wires 55, etc. are mounted is inserted and held in the board insertion hole 26.

  Finally, as shown in FIG. 6B, the opening of the case 25 is sealed by filling the case 25 with the sealing resin 29, so that the Hall IC 10 in the case 25, the bias magnet 40, the yoke 60, etc. Is fixedly positioned. In the case, the bias magnet 40 and the yoke 60 are located in the vicinity of the Hall IC 10 and apply a bias magnetic field to the Hall IC 10. For example, when a Hall IC incorporating one Hall element is used, the arrangement shown in FIGS. 3C and 3D is used. When a Hall IC incorporating two Hall elements is used, FIGS. D).

  As shown in FIG. 6B, the moving body detection device 200 is used in a state where the Hall IC 10 is supported so as to face the outer peripheral surface of the soft magnetic gear 1 that is an example of the detection target moving body. . The teeth of the gear 1 move in a direction perpendicular to the paper surface.

  In the case of the second embodiment, the case structure is different from that of the first embodiment, but the same effects as those of the first embodiment can be obtained.

  FIG. 7 is an illustration of another yoke shape that can be used in the first and second embodiments, and a configuration corresponding to a conventional example is also shown for comparison.

  FIGS. 7A-1 and 7A-2 show a model Y05 corresponding to the conventional example, which has a square plate shape with the same area and shape as the magnetic pole surface of the bias magnet with respect to the prismatic bias magnet. The yoke is stacked.

  FIGS. 7B-1 and 7B-2 are models that can be used in the first and second embodiments: YMA1, and a square plate-like portion in which the length in the xy direction is the same as the length of the magnetic pole surface of the bias magnet In addition, a yoke having a strip-like (rectangular plate-like) protruding portion on both sides in the x direction and having a length in the x direction larger than the magnetic pole surface is superimposed on a prismatic bias magnet.

  FIGS. 7C-1 and 7C-2 are models that can be used in the first and second embodiments: YMA2, and a square plate-like portion whose length in the xy direction is the same as the length of the magnetic pole surface of the bias magnet In addition, a yoke having a longer belt-like (rectangular plate-like) protruding portion on both sides in the x-direction so that the length in the x-direction is larger than the magnetic pole surface is superimposed on the prismatic bias magnet. is there.

  FIGS. 7D-1 and 7D-2 are models that can be used in the first and second embodiments: YMB1, and a square plate-like portion whose length in the xy direction is the same as the length of the magnetic pole surface of the bias magnet In addition, a yoke having a triangular plate-like protrusion on both sides in the x direction and having a length in the x direction larger than that of the magnetic pole surface is superimposed on a prismatic bias magnet.

  FIGS. 7E-1 and 7E-2 are models that can be used in the first and second embodiments: YMC1, and a square plate-like portion whose length in the xy direction is the same as the length of the magnetic pole surface of the bias magnet In addition, a yoke having an arc plate-like protruding portion on both sides in the x direction and having a length in the x direction larger than the magnetic pole surface is superimposed on a prismatic bias magnet.

  FIGS. 7F-1 and 7F-2 are models that can be used in the first and second embodiments: YMD1, and the length in the y direction is shorter than the length of the magnetic pole surface of the bias magnet, and the x direction A rectangular plate-like yoke whose length is longer than the magnetic pole surface is superimposed on a prismatic bias magnet.

  FIGS. 7G-1 and 7G-2 are models corresponding to the conventional example: YC05, and a disk-shaped yoke having the same area and shape as the magnetic pole surface of the bias magnet with respect to the cylindrical bias magnet. It is the structure which piled up.

  7 (H-1) and 7 (H-2) are models that can be used in the first and second embodiments: YC07, and a circular-shaped bias magnet has a larger diameter than the magnetic pole surface of the bias magnet. It is the structure which piled up the plate-shaped yoke.

  Hereinafter, comparison and examination of the simulation results for each yoke shape will be made with reference to FIGS.

  FIG. 8 shows a simulation result for each yoke shape in a state where there is no center shift between the prismatic bias magnet and the rectangular plate-shaped yoke. FIG. 8A is a conceptual diagram of a simulation model. In the case of models Y01 to Y11, a prismatic bias magnet (magnetic pole surface x-direction dimension: 5 mm, y-direction dimension: 5 mm, z-direction magnet thickness: 3 mm) is used. And a rectangular plate-shaped yoke (the x-direction dimension of the plane facing the magnetosensitive element (in the case of the embodiment, the hall element): 1 to 15 mm, the y-direction dimension: 5 mm = constant, This is a case where the magnet thickness in the z direction is 1 mm = constant). The distance dz between the element (sensing point) and the facing yoke plane is 2.1 mm in consideration of the package thickness of the Hall IC, the thickness of the holding member (case), the substrate, etc., and the z-direction magnetic flux density Bz is assumed to be 2.1 mm. calculate. Model Y00 is a case where there is no yoke, and Bz is calculated on the assumption that the distance dzmg between the magnetic pole surface of the bias magnet having the same shape and the element (sensing point) is 3.1 mm.

  FIG. 8B shows the distribution of Bz at x = −2.5 to +2.5 mm at a height dz away from the yoke surface and y = 0 as in the simulation model conceptual diagram of FIG. It is a table | surface which shows the result calculated about the model. In consideration of the thickness of the Hall IC package, the thickness of the holding member (case), the substrate, etc., dz = 2.1 mm. In the case of model Y00 without a yoke, the height was set to be dzmg (= 3.1 mm) away from the magnetic pole surface of the bias magnet.

  FIG. 8C is a graph showing the calculation result of FIG. 8B. The models Y00 to Y05 are angled curves, and the yoke width (x direction) is larger than the pole face width (x direction). When it is expanded so as to increase, Bz approaches uniformly regardless of the position in the x direction. It can be seen that in the models Y06 to Y11 in which the yoke x-direction length is larger than that of the bias magnet, the yoke x-direction length is substantially flatter than that of the model Y05 that is the same as the bias magnet. In other words, it can be said that it is effective to make the yoke width 1.2 times or more the x-direction length of the magnetic pole surface of the bias magnet.

  Therefore, by making the yoke width (x direction) larger than the magnetic pole face width (x direction) of the bias magnet, even if the arrangement of the magnetic sensing elements such as the Hall ICs with respect to the bias magnet and the yoke is shifted in the x direction, the magnetic There is little fluctuation of the bias magnetic field at the element position, which can contribute to the suppression of product variations.

  In consideration of the case where the yoke is placed in contact with the Hall IC package, the z-direction magnetic flux density Bz distribution at a position dz = 1.0 mm away from the yoke plane facing the element was also calculated. Almost similar results were obtained.

  FIG. 9 shows two element positions (two sensing points) when there is a center deviation between two elements (for example, a Hall IC incorporating two Hall elements) and the yoke (no deviation between the bias magnet and the yoke). The difference ΔBz of Bz at is considered. FIG. 9A shows how to obtain the difference Bz of Bz at two element positions (two sensing points), and when there is no center shift between the two elements and the yoke, the intermediate point between the two element positions. (2 division points) is equal to 0.0 in the x-direction position. Here, a case where an assembly error of 0.2 mm occurs in the x direction with respect to an element interval of 2 mm when dz = 2.1 mm is considered, and an intermediate point (two division points) between two element positions is in the x direction. The position is shifted from 0.0 to 0.2 mm. Accordingly, the two elements are positioned at x = 1.2 mm and x = −0.8 mm. Then, the Bz difference ΔBz at the two element positions can be obtained from the Bz distribution curve of each model obtained in FIG. FIG. 9A illustrates models Y05 and Y06. In model Y05 (conventional example), the Bz difference ΔBz at the two element positions is large because the Bz distribution is a mountain-shaped curve. In comparison, it can be seen that the model Y06 has a small value because the Bz distribution approaches flat.

  FIG. 9B is a table in which ΔBz and | ΔBz | are calculated for models Y00 to Y11. FIG. 9C is a graph showing the relationship between the x-direction yoke width and ΔBz of the models Y00 to Y11. From these results, it can be seen that ΔBz sharply decreases when the x-direction yoke width is equal to or greater than model Y06. In other words, the x-direction yoke width is 6 mm or more with respect to the x-direction length of 5 mm of the magnetic pole surface of the bias magnet (that is, the x-direction yoke width is 1.2 times or more the x-direction length of the magnetic pole surface of the bias magnet). By doing so, ΔBz can be significantly reduced. Furthermore, if the x-direction yoke width of model Y07 or more (x-direction yoke width of 1.4 times or more the x-direction length of the magnetic pole surface of the bias magnet) is used, ΔBz can be suppressed to near zero.

  The magnitude of these ΔBz is the offset of the analog signal of the Hall IC incorporating two Hall elements. By reducing this, the margin for the switching threshold of the Hall IC output between the high level and the low level is increased, and the maximum detection distance can be extended when considering product variations.

  FIG. 10 shows models Y01S to Y11S when the center deviation exists between the prismatic bias magnet and the rectangular plate-shaped yoke (the Y01 to Y11 yoke center is shifted by 0.5 mm in the x direction with respect to the bias magnet center). 3) is a Bz distribution diagram by yoke shape showing the relationship between the x-direction position and the z-direction magnetic flux density Bz. In the case of the x-direction yoke width of the model Y06S or more, it can be seen that the influence of the displacement in the x direction is suppressed because the Bz distribution is made uniform.

  FIG. 11 shows a case where there is a center shift between the prismatic bias magnet and the rectangular plate-shaped yoke, and there is a center shift between the two elements (for example, a Hall IC incorporating two Hall elements) and the yoke. FIGS. 4A and 4B show an example of positional deviation between the bias magnet, the yoke, and the two elements. In addition, when the x-direction length of the yoke is larger than the same length in the same direction as the magnetic pole surface of the bias magnet, the magnetic pole surface is covered with the yoke.

  FIG. 11C shows the models Y00S to Y11S having the above-mentioned misalignment (the magnet is deviated by −0.5 mm in the x direction with respect to the yoke, and the two elements are deviated by +0.2 mm in the x direction with respect to the yoke). ΔBz and | ΔBz | are compared with models Y00 to Y11 in which there is no deviation between the bias magnet and the yoke (however, the two elements are offset by +0.2 mm in the x direction with respect to the yoke). FIG. 4D is a graph showing the relationship between the Y direction yoke width of Y01S to Y11S and ΔBz in comparison with models Y00 to Y11 having no deviation between the bias magnet and the yoke.

  From FIG. 11 (D), when there is a center shift between the bias magnet and the yoke and there is a center shift between the two elements and the yoke, compared to a case where there is no center shift between the bias magnet and the yoke. ΔBz increases, but the difference in the magnitude of ΔBz is considerably reduced for the yoke width model of Y06S (x-direction yoke width 6 mm) or more. In other words, the x-direction yoke width is 6 mm or more with respect to the x-direction length of 5 mm of the magnetic pole surface of the bias magnet (that is, the x-direction yoke width is 1.2 times or more the x-direction length of the magnetic pole surface of the bias magnet). By doing so, ΔBz can be significantly reduced. In particular, in the case of a model with a yoke width equal to or greater than Y07S (x-direction yoke width 7 mm, that is, 1.4 times the x-direction length of the magnetic pole surface of the bias magnet), it can be seen that there is almost no difference in the magnitude of ΔBz. .

FIG. 12 shows a case where the length of the yoke in the same direction is longer than the length of the magnetic pole surface of the bias magnet in a specific direction (for example, the x direction) even when the yoke is not rectangular. It shows that ΔBz can be reduced. FIG. 12A shows the relationship between the x-direction position and the z-direction magnetic flux density Bz for Y05, Y07, YMA1, YMA2, YMB1, YMC1, YMD1, YC05, and YC07 including models of various shapes illustrated in FIG. The Bz distribution diagram by yoke shape showing the Bz distribution in other models compared to the models Y05 and YC05 corresponding to the conventional example.

  FIG. 12B shows ΔBz and | ΔBz when the center shift (0.2 mm) described in FIG. 9A exists between two elements (for example, a Hall IC incorporating two Hall elements) and the yoke. Is a table, and ΔBz of other models is smaller than the models Y05 and YC05 corresponding to the conventional example.

  As described above, according to the configuration of the moving body detection devices 100 and 200 according to the first or second embodiment, the following effects can be obtained.

(1) By making the length of the yoke 60 in a specific direction (for example, the x direction) larger than the length of the bias magnet 40 in the same direction, the feeling caused by variations in the positions in the specific direction among the magnetosensitive element, the permanent magnet, and the yoke. It is possible to suppress the magnetic field fluctuation at the magnetic element position and to reduce the product variation of the maximum detection distance.

(2) In particular, from the relationship between the yoke width in FIGS. 9C and 11D and the magnetic flux density difference ΔBz between the two elements, the x-direction yoke width is 6 mm with respect to the x-direction length of 5 mm of the magnetic pole surface of the bias magnet. In other words, by setting the x-direction yoke width to 1.2 times or more the x-direction length of the magnetic pole surface of the bias magnet, ΔBz can be greatly reduced, and there is a positional deviation between the element, the bias magnet, and the yoke. However, a magnetic detection characteristic equivalent to or better than that of the conventional example can be obtained.

(3) Even if vibration or impact is applied during the use of the moving body detection devices 100 and 200, and the mutual positional relationship between the magnetosensitive element, the bias magnet 40, and the yoke 60 changes, the application to the magnetosensitive element is performed. It is possible to suppress the fluctuation of the magnetic field to be small, and as a result, there is an effect that it is possible to suppress malfunction caused by vibration or impact.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way.

  In the above description, the bias magnet is exemplified as a prismatic shape or a cylindrical shape, but is not limited to this shape. Further, the yoke shape is not limited to that illustrated in FIG. 7, and if the length of the yoke in the same direction is larger than the length of the magnetic pole surface of the bias magnet in the specific direction, the magnet, yoke, This is effective for misalignment between elements. Furthermore, although the case of a Hall element has been mentioned as the magnetosensitive element, it is apparent that a magnetoresistive element or the like may be used. The yoke is illustrated as being in close contact with the bias magnet, but there may be a gap between them.

1 Soft magnetic gear 10 Hall IC
20, 25 Case 26 Substrate insertion hole 27 Magnet / yoke insertion hole 30 Holding member 31 Support part 32 Columnar plug body part 33 Connector part 36 Insertion hole 40 Bias magnet 50 Conductor 51 Connector pin 55 Lead wire 60 Yoke 70 Substrate 100, 200 Moving body detection device

Claims (6)

Comprising a magnetosensitive element, a permanent magnet, and a yoke disposed between the magnetosensitive element and the permanent magnet;
The yoke faces the magnetic pole surface of the permanent magnet,
The moving body detection apparatus in which the length of the yoke in the same direction is larger than the length of the magnetic pole surface of the permanent magnet in a specific direction.   The moving body detection apparatus according to claim 1, wherein a length of the yoke in the specific direction is 1.2 times or more a length of the magnetic pole surface in the specific direction. Two magnetic sensing elements, a permanent magnet, and a yoke disposed between the two magnetic sensing elements and the permanent magnet;
The yoke faces the magnetic pole surface of the permanent magnet,
The moving body detection apparatus, wherein a length of the yoke in the same direction is larger than a length of the magnetic pole surface in a linear direction connecting the two magnetosensitive elements.   4. The moving body detection apparatus according to claim 3, wherein the length of the yoke in the linear direction connecting the two magnetosensitive elements is 1.2 times or more the length of the magnetic pole surface in the same direction. Detection device.   5. The moving body detection device according to claim 1, further comprising: a holding member that holds the magnetosensitive element, the permanent magnet, and the yoke, wherein the holding magnet is inserted into the permanent magnet and the yoke. A moving body detection device having an insertion hole.   The moving body detection device according to claim 1, wherein the magnetosensitive element is a surface-mounted magnetosensitive element fixed to a substrate, and the substrate is held by the holding member. Detection device.