JP2927084B2 - Manufacturing method of electromagnetic pickup - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electromagnetic pickup, and more particularly to a method for manufacturing a main body of an electromagnetic pickup by injection molding.

[0002]

2. Description of the Related Art Electromagnetic pickups are widely used for detecting the rotational speed of wheels for anti-skid control, traction control, and the like, and for detecting the rotational speed of wheels in an electronically controlled brake device. One of the manufacturing methods of this electromagnetic pickup is, for example,
As disclosed in Japanese Patent Application Laid-Open No. 69711, there is a method of forming a main body of an electromagnetic pickup by injection molding. Positioning the sensor part of the electromagnetic pickup in the mold cavity by the end of the iron core which is one component of the sensor part,
The main body is formed by injection molding.

[0003]

However, in this case, if the iron core is shortened, it becomes impossible to position the sensor portion. Therefore, the iron core must be lengthened, so that the electromagnetic pickup becomes large and the sensitivity becomes low. There were problems such as lowering. Against this background, an object of the present invention is to provide a method of manufacturing an electromagnetic pickup that can shorten an iron core and reduce the size of the electromagnetic pickup.

[0004]

A feature of the present invention is that a sensor portion of an electromagnetic pickup is positioned in a mold cavity by an end of an iron core which is one component of the sensor portion, and a main body portion is formed by injection molding. In this method, an additional portion is provided at an end portion, the sensor portion is positioned by the additional portion to form a main body portion, and then the additional portion is removed.

[0005]

According to the present invention, when the main body of the electromagnetic pickup is formed by injection molding, the electromagnetic pickup can be positioned in the mold cavity of the sensor using the additional portion.
When the additional portion is provided, for example, the additional portion is integrally provided to the iron core with an adhesive or the like, or one of the female screw portion and the female screw portion is formed in the additional portion, and the other is formed in the iron core. The additional portion may be removably attached to the iron core. When the additional portion is provided integrally, the additional portion may be removed by cutting with a lathe or the like. In particular, when the additional portion is formed of resin or the like, the additional portion may be dissolved and removed with an organic solvent or the like. Can also. In any case, it is not essential to completely remove the additional part,
Some may be left.

[0006]

As described above, the iron core can be shortened when the product is completed, while the sensor portion is positioned using a sufficiently large additional portion when the main body of the electromagnetic pickup is formed. The mounting space can be reduced. Also, by shortening the iron core, the output voltage can be increased and the sensitivity of the sensor can be improved. Also, if a part of the additional part is left at the tip of the iron core,
The remaining portion functions as a duct cover. In particular, when irregularities are formed on the tip surface of the iron core, the resin is inserted into the concave portion to form the additional portion, and when the additional portion is removed, the resin in the concave portion is left. It is possible to avoid entry of iron powder and the like. In particular, when the electromagnetic pickup is disposed at a position where it comes into contact with the outside air, it is possible to prevent water, dust and the like from entering the concave portion.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a state where the main body of the electromagnetic pickup is formed by injection molding and held in a mold. 10 is a fixed type, 12 is a movable type, and 14, 16
Is a slide core. The main body 22 is formed by injection molding in a state where the sensor section 20 of the electromagnetic pickup 18 is wrapped around the illustrated position.

The sensor section 20 of the electromagnetic pickup 18 includes a coil 26, a case 28, an iron core 30, a magnet 32, and a spacer 34. An iron core 30 is held at the center of a case 28 around which the coil 26 is wound. The rear end of the iron core 30 is fixed to the magnet 32 in the case 28, and an additional portion 36 is provided at the front end protruding from the case 28. A positioning pin 38 is fixed to a portion of the fixed die 10 facing the additional portion 36. A connector 40 is fixed to the rear end of the case 28. The connector portion 40 is made of resin and is already formed when the main body 22 is molded. A fitting hole 44 is formed at the rear end of the connector part 40 so as to fit with the core 42 fixed to the movable die 12. Two plug contacts extend in the axial direction from the bottom surface of the fitting hole 44.
Are connected by lead wires (not shown). Therefore, an axial hole for receiving the plug contact is formed at the front end of the core 42.

A recess 48 is formed in the center of the front end face of the iron core 30 adjacent to the additional portion 36. The additional portion 36 is made of resin and is formed by injection molding at the tip of the iron core 30, and a part of the additional portion 36 enters the concave portion 48 of the iron core 30.

The slide cores 14 and 16 are respectively held by the movable die 12 so as to be slidable in a direction perpendicular to the moving direction of the movable die 12, and are engaged with an angular pin (not shown) provided on the fixed die 10. When the movable mold 12 moves to the left in the figure and the mold is closed,
The slide core 14 moves downward and the slide core 16 moves upward to reach the illustrated position.

A core 52 is fixed to the movable mold 12. The core 52 is projected into the cavity to form a bolt hole 54 in the projection 53 of the main body 22, and a metal tube 56 is fitted into the projection. The metal tube 56 forms a bush of the bolt hole 54 after the projection 53 is formed. After completion of the electromagnetic pickup, bolts are inserted through the bush and fixed to the mounting member. Ejector pins 60, 62, and 64 are inserted through the movable mold 12, and the base end is fixed to an ejector plate (not shown). When the mold is opened, the ejector pins 60, 62, and 64 are protruded toward the cavity, and the main body 2 formed in the cavity is opened.
2 is projected from the movable mold 12.

A method of molding the main body 22 of the electromagnetic pickup 18 using the injection mold having the above-described configuration will be described. The molds 10 and 12 are closed in a state where the sensor section 22 is substantially positioned by fitting the fitting hole 44 of the connector section 40 and the core 52. With the closing of the mold, the slide cores 14 and 16 move to the positions in the drawing, and the additional portion 36 is sandwiched between the slide cores 14 and 16. In the final stage of closing the mold, the additional portion 36 and the positioning pin 38 come into contact with each other, so that the sensor portion 22 is positioned in the axial direction, and at the same time, the additional portion 36 is sandwiched between the slide cores 14 and 16. Is accurately positioned in the mold cavity.

In this state, the mold is clamped, and a molten resin is supplied into the cavity from a nozzle (not shown), and the main body 22 is formed so as to cover the sensor section 20. Subsequently, the molds 10 and 12 are opened, the slide cores 14 and 16 are separated from each other, and the ejector pins 60, 62 and 64 project the main body 22 from the movable mold 12.

After the main body 22 is formed as described above, the additional portion 36 of the iron core 30 is dissolved by an organic solvent and removed from the iron core 30 to complete the electromagnetic pickup.

The electromagnetic pickup 18 is fixed with the tip of the iron core 30 close to a rotor (not shown).
Since the rotor has irregularities on its surface, the magnetic flux exiting the magnet 32 and passing through the iron core 30 changes with the rotation of the rotor, and an AC voltage is generated in the coil 26. Since the frequency of this AC voltage is proportional to the rotation speed of the rotor, the coil 26
Of the rotor can be obtained from the output voltage.

According to the method of the present embodiment, the sensor portion 22 can be accurately positioned by using the additional portion 36 during molding, and thereafter, by removing the additional portion 36 and shortening the iron core 30, Increase the output voltage of the coil 26,
Since the sensitivity of the sensor unit can be improved, the rotation speed of the rotor can be accurately detected.

FIGS. 2 to 5 show another embodiment of the iron core 30 which is applicable to the above embodiment and is different from the iron core 30 of the above embodiment. In FIG. 2, an additional portion 72 made of resin is provided at the end of the iron core 70 by insert molding of the iron core 70 as in the above-described embodiment. Two parallel convex portions 74 are formed on the end face of the iron core 70 on the additional portion 72 side. After the injection molding of the main body of the electromagnetic pickup, other portions are removed by cutting with a lathe except for the additional portion 72 around the convex portion 74 at the tip of the iron core 70. The remaining portion of the additional portion 72, that is, the portion left in the groove between the two convex portions 74 of the iron core 70 or in the notch outside the convex portion 74 acts as a dust cover, and serves as a dust cover. Accumulation of iron powder of the rotor in the rotor is avoided. Further, even if the electromagnetic pickup is arranged at a position where it comes into contact with the outside air, it is possible to prevent water, dust and the like from adhering to the inside of the groove or the notch.

In FIG. 3, an additional portion 82 made of resin is provided at the end of the iron core 80 by bonding with an adhesive. A convex portion 84 is formed at the center of the end face of the iron core 80 on the side of the additional portion 82, and a concave portion corresponding to the convex portion 84 is formed on the end surface of the additional portion 82. Also, a V-groove 8 is formed on the outer peripheral surface of the additional portion 82.
8 are formed. After molding the body of the electromagnetic pickup,
The additional portion 82 is cut in the V groove by a cutter or the like. A part of the additional portion 82 is left on the outer periphery of the convex portion 84 of the iron core 80.

In FIG. 4, an additional portion 92 made of resin is fixed to the end of the iron core 90 by press-fitting. An engagement recess 94 whose inner peripheral surface is a tapered surface is formed at the center of the end surface of the iron core 80 on the addition portion 92 side, and an engagement protrusion 96 corresponding to the engagement recess 94 is formed on the end surface of the addition portion 92. Have been. After the electromagnetic pickup is formed, the additional portion 92 is removed from the iron core 90 by being pulled.

In FIG. 5, an additional portion 102 made of metal is provided at the end of the iron core 100 by screwing. A female screw hole is formed in the iron core 100, and a male screw portion is formed in the additional portion 102. After the main body of the electromagnetic pickup is formed, it is removed from the iron core 100 by rotating the additional portion 102. Thus, the adding unit 102
Can be removed from the iron core 100, and if the female screw portions similar to the iron core 100 are formed in a plurality of iron cores, the additional portion 102 can be used for other iron cores.

As in these embodiments, an additional portion is provided on the iron core, and by using this, the sensor portion is positioned in the mold cavity and the main body portion is removed after injection molding.
The iron core can be shortened.

The method of adding the additional portion to the iron core and the method of removing the additional portion from the iron core are not limited to those described in the respective embodiments. In other embodiments, the additional portion is heated by heating the additional portion. It is also possible to adopt a method of removing. Further, the shape of the end face of the iron core is not limited to the above-described embodiment, and various modes can be considered. Further, although the closed magnetic path is not formed in the electromagnetic pickup of the present embodiment, the present invention can be applied to an electromagnetic pickup of a type in which the closed magnetic path is formed and the output voltage of the coil is detected.

Although not specifically exemplified, the present invention can be carried out in various modified and improved forms based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a main body of an electromagnetic pickup is molded in a mold in one embodiment of the present invention.

FIG. 2 is a sectional view of an iron core according to another embodiment of the present invention.

FIG. 3 is a sectional view of an iron core according to still another embodiment of the present invention.

FIG. 4 is a sectional view of an iron core according to still another embodiment of the present invention.

FIG. 5 is a sectional view of an iron core according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixed metal mold 12 Movable metal mold 14, 16 Slide core 18 Electromagnetic pickup 20 Sensor part 22 Main body 30, 70, 80, 90, 100 Iron core 36, 72, 82, 92, 102 Additional part

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01P 3/488 G01B 7/00 G01D 5/00

Claims (1)

(57) [Claims] 1. A method of positioning a sensor section of an electromagnetic pickup in a mold cavity by an end of an iron core, which is one component of the sensor section, and forming a main body by injection molding. A method of manufacturing an electromagnetic pickup, comprising: providing an additional portion; positioning the sensor portion with the additional portion; forming the main body portion; and removing the additional portion.