JPH062231U - Movement detection sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a movement detection sensor that does not require adjustment of the position of the magnetoelectric conversion element, is easy to assemble, and can be mass-produced. [Structure] Using a magnetoelectric conversion element, a movement detection sensor for detecting the moving speed of an object having the projection by detecting the number of passages of a projection made of a magnetic body per unit time, and a base part of the movement detection sensor 2 attached so as to sandwich
It consists of two bifurcated yokes and four magnets attached to the lower surfaces of the bifurcated tips of the bifurcated yokes. , Magnets are attached to the same yoke with their polarities reversed, and the distance between two sets of magnets of different polarities attached to different yokes both match the pitch dimension of the protrusions that pass under this sensor. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a movement detection sensor, and more particularly to a movement detection sensor that detects the moving speed of an object equipped with a protrusion by making a magnetic change to detect the number of passages of the protrusion made of a magnetic material such as iron in a unit time. Regarding a detection sensor.

[0002]

[Prior art]

 Conventionally, as a method of detecting the rotation speed of rotating equipment such as internal combustion engines and motors, an iron gear is attached to the rotating shaft, a magnet is positioned near the tooth tip, and magnetic flux changes in the magnet due to passage of the tooth tip. A rotation detection sensor for gears has been put to practical use, which detects magnetic field using a magnetic sensor.

FIG. 7 shows an example of the rotation detecting sensor 40 of the gear. In the conventional rotation detection sensor 40, bar magnets 42 and 43 are attached to the lower surfaces of both ends of a horizontal portion 41a of a T-shaped yoke 41 so that their polarities are opposite to each other, and a magnetic neutral portion is attached to a vertical portion 41b of the yoke 41. And the magnetoelectric conversion element 44 is attached to the free end side of the vertical portion 41b of the yoke 41. In this magnetic neutral portion, the tip of the vertical portion 41b of the yoke 41 is in a state of being polarized into S and N poles, and is a zero magnetic field portion. The bottom surface of the magnetoelectric conversion element 44 is flush with the bottom surfaces of the bar magnets 42 and 43. As the magnetoelectric conversion element 44, a Hall element, a magnetoresistive effect element (MR element) or the like is used. I was there.

FIG. 8 and FIG. 9 show the operation when the rotation speed of the iron gear 50 is detected by the rotation detection sensor 40 configured as shown in FIG. 7, and the bar magnets 42, 43 and the magnetoelectric conversion. The rotation detection sensor 40 is attached so that the bottom surface of the element 44 faces the passage area of the tooth tip 51 of the gear 50.

As shown in FIG. 8, when the tooth tip 51 of the gear 50 comes between the bar magnet 42 and the magnetoelectric conversion element 44, the magnetic force line from the N pole of the bar magnet 42 passes through the tooth tip 51. It flows into the magnetoelectric conversion element 44, and returns to the S pole through the vertical portion 41b and the horizontal portion 41a of the yoke 40. At this time, since the tooth tip 51 is not close to the bar magnet 43, the magnetic force lines from the bar magnet 43 do not pass through the inside of the yoke 41.

After that, the gear rotates as shown by the arrow A to be in the state of FIG. 9, and when the tooth tip 51 comes between the magnetoelectric conversion element 44 and the bar magnet 43, the N pole of the bar magnet 43 comes out. The lines of magnetic force pass through the horizontal portion 41a and the vertical portion 41b of the yoke 40, and flow back from the magnetoelectric conversion element 44 to the S pole via the tooth tip 51. At this time, since the tooth tip 51 is not close to the bar magnet 42, the magnetic force line from the bar magnet 42 does not pass through the inside of the yoke 41.

In this way, since an alternating magnetic field is applied to the magnetoelectric conversion element 44 of the rotation detection sensor 40 according to the rotation of the gear 50, conventionally, the magnetic flux density from the magnetoelectric conversion element 44 within a unit time is reduced. The rotation speed of the gear 50 was detected by calculating the number of passages of the addendum 51 of the gear 50 from the output signal (electrical signal) due to the change.

The electric signal indicating the increase / decrease in the magnetic flux density is actually signal-amplified by a circuit element or an amplification IC, and this signal is transmitted as a sensor output to an external device (not shown) via a wire and a connector, so that an external device In the above, the number of changes in the magnetic flux density per unit time is detected from the rotation detection sensor 40, and the rotation speed of the gear 50 is calculated from this detection value, but this process is not directly related to the present invention. , Not explained here.

[0009]

[Problems to be solved by the device]

 However, in the conventional rotation detecting sensor 40 configured as described above, it is necessary to align the central portion of the magnetoelectric conversion element 44 with the magnetic neutral portion of the vertical portion 41b of the yoke 41. The width of the magnetic part is narrow (about 0.2 mm), and (2) there is variation in the position of the magnetic neutral part (differences in the amount of magnetization of the bar magnets and the mounting positions of the left and right bar magnets 42, 43). For reasons such as (due to variations), the work of aligning the central portion of the magnetoelectric conversion element 44 with the magnetic neutral portion of the vertical portion 41b of the yoke 41 must be performed individually for each sensor. There was a problem that it was difficult to mass-produce.

Therefore, the present invention can detect the passage of a protrusion of a magnetic material such as a tooth tip of a gear without adjusting the position of a magnetoelectric conversion element, and a movement detection cell that is easy to assemble. The purpose is to provide a sensor.

[0011]

[Means for Solving the Problems]

 The movement detection sensor of the present invention that achieves the above object uses a magnetoelectric conversion element to detect the number of passages of a protrusion made of a magnetic material per unit time, thereby detecting the movement speed of an object having the protrusion. A sensor for detecting, comprising two bifurcated yokes whose bases are mounted so as to sandwich the magnetoelectric conversion element, and four magnets respectively mounted on the lower surfaces of the front ends of the bifurcated ends of each yoke. The yokes are formed so that the tip positions of the two arms are different from each other in the moving direction of the protrusion, the magnets are attached to the same yoke in opposite polarities, and different polarities are attached to different yokes. The distance between the two sets of magnets is the same as the pitch dimension of the protrusions that pass under the sensor.

[0012]

[Action]

 The movement detection sensor of the present invention comprises two bifurcated yokes whose bases are mounted so as to sandwich the magnetoelectric conversion element, and four magnets which are respectively attached to the lower surfaces of the front ends of the bifurcated ends of each yoke with their polarities reversed. Since it is composed of, the mounting position of the magnetoelectric conversion element is outside the magnetic circuit and is the magnetic neutral part, so that it is not necessary to adjust the mounting position of the magnetoelectric conversion element.

[0013]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an assembly perspective view showing a configuration of a movement detection sensor 10 according to an embodiment of the present invention. The movement detection sensor 10 of this embodiment includes a magnetoelectric conversion element 11, two yokes 12 and 13 attached to both sides of the magnetoelectric conversion element 11, and two rods attached to the lower surfaces of the yokes 12 and 13, respectively. It is composed of magnets 14, 15, 16, and 17.

In this embodiment, the magnetoelectric conversion element 11 is composed of a Hall element, an MR element or the like, and has a rectangular parallelepiped shape. In this embodiment, the yokes 12 and 13 have the same shape, and are bifurcated with the surface X on which the magnetoelectric conversion element 11 is mounted as a base, and one of them is used upside down. Each yoke 12, 13 has a first arm 12a, 13a and a second arm 12b, 13b, respectively. The first arms 12a and 13a have the same length and are longer than the base X, and the second arm The lengths of 12b and 13b are also the same and shorter than the base portion X. Two of the bar magnets 14 to 17 have the same polarity.

When the movement detection sensor 10 is assembled, bar magnets 14 and 17 having the same polarity are attached to the bottom surfaces of the tips of the first arms 12a and 13a, and the bottom surfaces of the tips of the second arms 12b and 13b are also attached. Bar magnets 15 and 16 having the same polarity but different polarities from the bar magnets 14 and 17 are attached. The yoke 12 to which the magnets 14 and 15 are attached and the yoke 13 to which the magnets 16 and 17 are attached are made to face each other with the surface X facing each other, and are joined with the magnetoelectric conversion element 11 interposed therebetween. In this case, the surface X that joins the magnetoelectric conversion element 11 is outside the magnetic circuit and is therefore a magnetic neutral portion. Therefore, it is not necessary to adjust the position when joining the magnetoelectric conversion element 11.

FIG. 2A is a plan view of the movement detection sensor 10 assembled as described above. As can be seen from this figure, the distance (pitch) P1 between the magnets 14 and 16 and the distance (pitch) P2 between the magnets 15 and 17 are equal, and the protrusions provided on the substance whose velocity is to be detected. Be equal to the interval of.

Next, the operation of detecting the rotational speed of the gear 20 using the movement detection sensor 10 configured as described above will be described with reference to FIG. As described above, when the joint surface X of the yokes 12 and 13 with the magnetoelectric conversion element 11 is a magnetic neutral portion outside the magnetic circuit, there is no magnetic substance around the movement detection sensor 10. The magnetic field is not applied to the magnetoelectric conversion element 11.

When the addendum 21 of the gear 20 approaches the magnet 14, the addendum 22 approaches the magnet 16 because the pitch P 1 between the magnet 14 and the magnet 16 and the pitch of the addendums 21 and 22 are equal. Then, as indicated by the solid arrow, the N pole of the magnet 14 → the tooth tip 21 → the gear 20 → the tooth tip 22 → the magnet 16 → the yoke 13 → the magnetoelectric conversion element 11 → the yoke 12 → the closed magnetic circuit of the magnet 14 becomes The magnetic flux is formed and passes through the magnetoelectric conversion element 11. The magnetic flux passing through the magnetoelectric conversion element 11 decreases as the tooth tips 21 and 22 move away from the magnets 14 and 16, respectively.

After that, when the addendum 21 of the gear 20 approaches the magnet 15 as shown by the broken line, the pitch P2 between the magnet 15 and the magnet 17 and the addendum 21 and 22 are equal. Approaching the magnet 17. Then, as shown by a broken arrow, a closed magnetic circuit of the N pole of the magnet 17, the tooth tip 22, the gear 20, the tooth tip 21, the magnet 15, the yoke 12, the magnetoelectric conversion element 11, the yoke 13, and the magnet 17 is formed. , The magnetic flux passes through the magnetoelectric conversion element 11 from the opposite side. The magnetic flux passing through the magnetoelectric conversion element 11 decreases as the tooth tips 21 and 22 move away from the magnets 15 and 17, respectively.

In this way, since the alternating magnetic field is applied to the magnetoelectric conversion element 11 of the movement detection sensor 10 according to the rotation of the gear 20, the output due to the change of the magnetic flux density from the magnetoelectric conversion element 11 within a unit time. The signal (electrical signal) is amplified by a circuit element or an amplification IC (not shown), and this is transmitted as a sensor output to an external device (not shown) via a wire and a connector, and the unit time from the movement detection sensor 10 is transmitted to the external device. The number of changes in the magnetic flux density per hit is detected, and the rotation speed of the gear 20 is detected from this detected value. At this time, the pitch P1 between the magnet 14 and the magnet 16, the pitch P2 between the magnet 15 and the magnet 17, and the pitch between the tooth tips 21 and 22 are equal, so that the magnetic flux passing through the magnetoelectric conversion element 11 is large and the detection accuracy is improved. To do.

The movement detection sensor 10 of the embodiment described above has no problem when the rotating body (gear 20) has a large rack gear or a large radius of curvature, but when the radius of curvature is small, the magnets 14 to 16 are used. In some cases, the spacing between the tooth tips 21, 22 becomes wider, the change in the magnetic flux density becomes smaller, and the detection resolution decreases.

Therefore, when the radius of curvature of the gear 20 is small, the distance between the tooth tips 21 and 22 of the gear 20 and the magnets 14 to 16 may be set to the same distance D. This embodiment will be described with reference to FIGS. 3 to 5. However, the same components as those of the embodiment of FIGS. 1 and 2 are designated by the same reference numerals and the description thereof will be omitted.

The movement detection sensors 10-1 of the embodiment shown in FIG. 3 are mounted on the lower surfaces of the yokes 12 and 13 in the movement detection sensor 10 of the embodiment shown in FIG. The end portions of the bar magnets 14, 15, 16, 17 that are to be extended are extended so that the distances D to the tooth tips 21 and 22 of the gear 20 are all equal and cut so as to be parallel to the tooth tips 21 and 22. The bar magnets 14 ', 15', 16 'and 17' are used. In this case, the magnets 14 and 17 and the magnets 15 and 16 have the same shape. As a result, the distance D between the four magnets 14 'to 17' and the tooth tops 21 and 22 is kept small even when the radius of curvature of the gear 20 is small, so that the magnetic flux density changes due to the rotation of the gear 20. As in the case of the rack gear, the detection ability is improved. When the tips of the addendums 21 and 22 are arcuate, the tips of the four extended magnets 14 'to 17' may also be arcuate.

In the movement detection sensor 10-2 of the embodiment shown in FIG. 4, in the movement detection sensor 10 of the embodiment shown in FIG. 2 (a), the shapes of the four magnets 14 to 17 are not changed, By changing the shapes of the teeth 12 and 13, the distances between the tooth tips 21 and 22 of the gear 20 and the magnets 14 to 16 are set to the same distance D. Therefore, as shown in FIG. 4 (a), the yokes 12 ', 13' of this embodiment are the same as the first arms 12a, 13a and the second arms 12b, 13b of the yokes 12, 13 of FIG. 2 (a). The first arm 12a ', 13a' and the second arm 12b ', 13b' are formed by extending the distal end of the first arm and bending the extended part downward at a predetermined portion. The bending of the first arms 12a ', 13a' and the second arms 12b ', 13b' is performed when the same bar magnets 14 to 17 as in FIG. ), The tip portions of the magnets 14 to 17 may be parallel to the tip surfaces of the tooth tips 21 and 22 with a predetermined distance D therebetween. Also in this embodiment, since the length of the yoke magnetic path between the magnets 14 and 16 and the length of the yoke magnetic path between the magnets 15 and 17 are the same, the operation is as shown in FIG. 2 (b). It will be the same as the one.

Two movement detecting sensors 10-3 of the embodiment shown in FIG. 5 are attached to the lower surfaces of the yokes 12 and 13 of the movement detecting sensor 10 of the embodiment shown in FIG. The bar magnets 14, 15, 16 and 17 to be used are not linear magnets but curved magnets 14 ″, 15 ″, 16 ″ and 17 ″, and the distance between their free ends and the tips 21 and 22 is set. This is so that all D are equal. In this case, the magnets 14 "and 17" and the magnets 15 "and 16" have the same shape. Therefore, also in this embodiment, since the length of the yoke magnetic path between the magnets 14 ″ and 16 ″ and the length of the yoke magnetic path between the magnets 15 ″ and magnets 17 ″ are the same, the operation is It is the same as that in Fig. 2 (b).

As described above, if the distance between the magnet attached to the lower surface of the yoke and the tooth tip is equal, the detection capability is improved even with a gear having a small radius of curvature.

2 (b) to 5 illustrate the operation of detecting the rotation speed of the gear 20 using the movement detection sensor 10 of FIG. 1, the movement detection sensor 10 of FIG. As shown in 6, not only the rotation speed of the gears but also the moving speed of the object having the protrusions 31 and 32 that are equal to the pitch P1 between the magnets 14 and 16 and the pitch P2 between the magnets 15 and 17 It can also be effectively used when detecting.

[0029]

[Effect of device]

 As described above, according to the movement detection sensor of the present invention, since the movement detection sensor can be assembled without adjusting the position of the magnetoelectric conversion element, the movement detection sensor can be easily assembled. Therefore, there is an effect that mass production becomes possible.

[Brief description of drawings]

FIG. 1 is an assembled perspective view showing a configuration of an embodiment of a movement detection sensor of the present invention.

2A is a plan view of the movement detection sensor of FIG. 1, and FIG. 2B is an explanatory diagram showing an operation when the rotation speed of the gear is detected by the movement detection sensor of FIG.

FIG. 3 is an explanatory diagram showing a configuration of a modified example of the movement detection sensor of the embodiment of FIG.

4A and 4B show a configuration of another modified example of the movement detection sensor of the embodiment of FIG. 1, where FIG. 4A is a perspective view of a yoke, and FIG. 4B shows an operation when detecting a rotation speed of a gear. It is an explanatory view shown.

5 is an explanatory diagram showing a configuration of still another modification of the movement detection sensor of the embodiment of FIG. 1. FIG.

FIG. 6 is an explanatory diagram showing an operation when the moving speed of an object moving in a horizontal direction is detected by the movement detection sensor of FIG.

FIG. 7 is an assembled perspective view showing a configuration of a conventional rotation detection sensor.

FIG. 8 is an explanatory diagram showing an operation of the rotation detection sensor of FIG.

9 is an explanatory diagram showing the operation of the rotation detection sensor of FIG.

[Explanation of symbols]

10, 10-1, 10-2, 10-3 Movement detection sensor of the present invention 11 Magnetoelectric conversion element 12, 13, 12 ', 13' Yoke 12a, 12b, 13a, 13b, 12a ', 12
b ', 13a', 13b 'arms 14, 15, 16, 17, 14', 15 ', 16', 1
7'Bar magnets 14 ", 15", 16 ", 17" Magnets 20 Gears 21,22 Tooth tips 30 Moving objects 31,32 Protrusions X Magnetoelectric conversion element mounting surface

Claims (4)

[Scope of utility model registration request] 1. A magnetoelectric conversion element is used to detect the number of passages of a magnetic protrusion per unit time,
A sensor for detecting the moving speed of an object having the protrusion, wherein the base is attached so as to sandwich the magnetoelectric conversion element.
It consists of two bifurcated yokes and four magnets attached to the lower surfaces of the bifurcated tips of each of the yokes. Are formed, and the magnets are attached to the same yoke with their polarities reversed, and
A movement detecting sensor, characterized in that the distance between two sets of magnets of different polarities attached to different yokes both match the pitch dimension of the protrusions that pass under the sensor. 2. The protrusion is a tooth of a gear, and a gap between two magnets of different polarities attached to the different yokes corresponds to a pitch of the tooth of the gear. The movement detection sensor according to claim 1, wherein the rotation speed of the gear is detected. 3. The movement detection sensor according to claim 1, wherein the shape of the magnet attached to the yoke is determined so that the protrusions and all the magnets have the same spacing. 4. The movement detection sensor according to claim 1, wherein the shape of the tip of the yoke is determined so that the protrusions and all the magnets have the same spacing.