JPH0736291Y2 - Electromagnetic type moving state detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an electromagnetic moving state detecting device for detecting a rotational speed and a linear moving speed by utilizing a change in magnetic resistance.

[Prior Art] An electromagnetic speed sensor is composed of a magnetic core, a coil wound around a bobbin, and a permanent magnet. The magnetic resistance changes when a magnetic object facing the permanent magnet moves relatively, Based on this, the magnetic flux of the magnetic core is changed, and the induced voltage of the coil is also changed.

[Problems to be Solved by the Invention] By the way, conventionally, since the permanent magnet is held on the end surface of the magnetic core by utilizing this attraction force, there is a possibility that the position shift occurs. Therefore, an object of the present invention is to provide an electromagnetic type movement state detecting device which can easily and stably dispose a permanent magnet at a predetermined position.

[Means for Solving the Problems] The invention according to claim 1 for achieving the above object is an electromagnetic movement for detecting relative movement of an object to be detected in which teeth made of a magnetic material are arranged at a predetermined pitch. A state detecting device, wherein a bobbin having a hollow portion, and a magnet at least a part of which is inserted into the hollow portion of the bobbin and one end of which is arranged to reach an end surface of the bobbin on the side of the detected object. A core, a coil wound around the bobbin for detecting a change in magnetic flux of the magnetic core, and a flat plate of a non-magnetic material, and a hole for magnet placement from one main surface to the other main surface. A magnet holder disposed on the end surface of the bobbin on the side of the detected object, and inserted into the magnet arranging hole of the magnet holder so that at least a portion thereof contacts the end surface of the magnet core. Placed The present invention relates to an electromagnetic type moving state detecting device, which comprises a permanent magnet and a moisture-proof enclosure that surrounds the bobbin, the coil, and the magnet holder.

As described in claim 2, it is preferable that the bobbin is provided with a positioning portion and the magnet holder is provided with a positioned portion.

[Operation and Effect of the Invention] According to the invention of claim 1, since the permanent magnet is arranged by providing the magnet holder and the magnet arranging hole therein, the permanent magnet can be easily and accurately arranged at a predetermined position. can do.

Further, since the magnet holder is a flat plate, the moving state detecting device can be downsized, and the position of the permanent magnet can be accurately set.

According to the invention of claim 2, the positional relationship between the bobbin and the magnet holder can be set easily and accurately.

[Embodiment] Next, a rotation speed sensor according to an embodiment of the present invention will be described with reference to FIGS. The speed sensor 1 includes a bobbin 2 made of an electrically insulating and moisture-proof synthetic resin, a detection coil 3 wound around the bobbin 2, a magnetic core 4, a moisture-proof resin enclosure 5, and first and second permanent magnets. 6 and 7, a magnet holder 8 and a pair of leads 9 and 10.

Each part will be described in more detail. The bobbin 2 is composed of a central part 11 and first and second flange parts 12 and 13 provided at both ends of the bobbin 2 from the first flange part 12 toward the second flange part 13. It has a dead end hole 14. This hole 14 preferably extends beyond the central portion 11.

The core 4 is made of a rod-shaped magnetic material and is inserted into the hole 14 of the bobbin 2. The magnet holder 8 is made of a non-magnetic and elastic material (rubber) and has two holes as shown in FIGS. 3 and 4.
It has 15 and 16. These two holes 15, 16 are permanent magnets 6, 7
It has a positioning function and a holding function. Therefore, the dimensions of the holes 15, 16 before fitting the permanent magnets 6, 7 are slightly smaller than the dimensions of the permanent magnets 6, 7.

The permanent magnets 6 and 7 have a prismatic shape as shown in FIG.
It has pole faces 6a and 7a and S pole faces 6b and 7b, respectively. The permanent magnets 6 and 7 elastically deform the magnet holder 8 to fit the holes 15 and 16, respectively. At this time, the first permanent magnet 6 is arranged such that the N pole surface 6a is on the outside and the S pole surface 6b is on the core 4 side,
The second permanent magnet 7 has the N pole surface 7a on the core 4 side and the S pole surface.
Arrange so that 7b is on the outside. The first and second permanent magnets 6 and 7 arranged in opposite directions are non-magnetically separated by the central portion 17 of the magnet holder 8.

The bobbin 5 is provided with a holder positioning portion 18 formed of a protrusion, and the magnet holder 8 is provided with a positioned portion 19 formed of a recess engaged with the holder.

The resin enclosure 5 as a moisture-proof coating is molded by using a mold and surrounds the bobbin 2, the coil 3 and the holder 8 so that the end faces of the permanent magnets 6 and 7 are exposed.

When the rotation is detected by the speed sensor 1, the exposed surfaces of the permanent magnets 6 and 7 are arranged to face each other at the passage position of the teeth 21 of the gear 20 made of a magnetic material. As a result, the magnetic resistance of the magnetic circuit changes according to the movement of the teeth 21, the output voltage of the coil 3 also changes, and a frequency output corresponding to the speed can be obtained. Since the second permanent magnet 7 has a relationship so as to face the tooth 21 when the first permanent magnet 6 is located between the teeth 21, the conventional single magnet is Compared to the case, the amount of change in the magnetic flux of the core 4 increases in response to the movement of the teeth 21, and the amplitude of the output voltage of the coil 3 increases.

This embodiment has the following effects.

(1) Positioning and mounting of the permanent magnets 6 and 7 can be achieved easily and accurately.

(2) The holder 8 is used to separate the first and second permanent magnets 6 and 7.
It can be easily achieved by the central part 17 of the.

(3) The positioning of the holder 8 with respect to the bobbin 2 can be easily achieved by the positioning portion 18 and the positioned portion 19.

(4) Since the hole 14 of the bobbin 2 does not penetrate, moisture does not enter the coil 3 through this hole.

(5) By arranging the two magnets 6 and 7 in directions opposite to each other, a large magnetic flux change occurs, and a velocity detection signal having a large amplitude can be obtained.

[Modification] The present invention is not limited to the above-described embodiments, and the following modifications are possible, for example.

(1) As shown in FIG. 6, one hole 21 is formed in the magnet holder 8a.
2 may be provided, and two permanent magnets 6 and 7 and non-magnetic separators (corresponding to the central portion 17) thereof may be fitted into the hole 21 in the same manner as in FIG. Also, one permanent magnet may be fitted into this hole 21.

(2) As shown in FIG. 6 and FIG.
A plurality (2 or 4) can be provided.

(3) As shown in FIG. 7, a cut 22 is provided so as to be continuous with the hole 21 of the magnet holder 8b so that the size of the hole 21 does not change, and even if the size of the permanent magnet is slightly changed. You may allow it.

(4) As shown in the magnet holder 8c in FIGS. 8 and 9,
It is also possible to provide a positioned portion 19a composed of a projection and provide the bobbin 2 with a corresponding concave portion so that both of them are engaged with each other.

(5) As shown in FIG. 10, a pair of flat surfaces 23 may be provided on the magnet holder 8d and the flat surfaces 23 may be used for positioning.

(6) As shown in FIG. Each part may be inserted into the non-magnetic housing 24. In FIG. 13, the magnet holder 8d of FIG. 10 is used, and the front end surface of the housing 24 is formed so as to correspond to the magnet holder 8d of FIG.

[Brief description of drawings]

1 is a central longitudinal sectional view showing a speed sensor according to a first embodiment of the present invention, FIG. 2 is a plan view of the speed sensor of FIG. 1, and FIG. 3 is a magnet holder of the speed sensor of FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, FIG. 5 is a perspective view showing the permanent magnet of FIG. 1, and FIGS. 6, 7, and 8 show modified examples. FIG. 9 is a plan view showing a magnet holder, FIG. 9 is a front view of the magnet holder of FIG. 8, FIG. 10 is a plan view showing a magnet holder of another modification, and FIG. 11 is a cross section showing a speed sensor of the modification. It is a figure. 2 ... Bobbin, 3 ... Coil, 4 ... Core, 6,7 ... Permanent magnet, 8 ... Magnet holder, 15, 16 ... Hole.

Claims (2)

[Scope of utility model registration request] 1. An electromagnetic movement state detecting device for detecting relative movement of an object to be detected in which teeth made of a magnetic material are arranged at a predetermined pitch, the bobbin having a hollow portion, and the bobbin, A magnetic core, at least a part of which is inserted into the hollow portion and one end of which is arranged so as to reach the end surface of the bobbin on the detected object side, and the bobbin for detecting a change in magnetic flux of the magnetic core. A magnet that is composed of a wound coil and a flat plate of a non-magnetic material, has a magnet placement hole from one main surface to the other main surface, and is placed on the end surface of the bobbin on the side of the detected object. A holder; a permanent magnet that is inserted into the magnet placement hole of the magnet holder and is disposed so that at least a portion thereof contacts the end surface of the magnetic core; and the bobbin, the coil, and the magnet holder. Electromagnetic moving state detecting device characterized by comprising a moistureproof enclosure to enclose. 2. The electromagnetic movement state detecting device according to claim 1, wherein the bobbin has a positioning portion for the magnet holder, and the magnet holder has a positioned portion that engages with the positioning portion.