JPH09152441A - Electromagnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor which is provided with a counter-die positing means so arranged as to let a molten resin flow to the tip part of a pole piece after held accurately at the center of a die. SOLUTION: In this sensor, a bobbin 7 wound with a coil 9 and a sensitive element part 2 having a pole piece 10 inserted into the center part of the bobbin 7 are inserted into dies 19 and 20 to form a cover part 3 in the perimeter of the sensitive element part 2 by injecting a melted resin. The bobbin 7 is provided with a plurality of axially extensions 22 allowed to contact the inner circumferential surface of the dies 19 and 20 almost closely for molding the perimeter of the tip end part of the pole piece 10 and the molten resin flows into the tip part of the pole piece 10 through a clearance G2 between the extensions 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated electromagnetic sensor formed by insert-molding a sensitive element section.

[0002]

2. Description of the Related Art An electromagnetic sensor is known in which a sensitive element portion including a coil, a pole piece, a permanent magnet and a yoke is insert-molded to integrally form a fixing portion for a vehicle body and a covering portion of the sensitive element portion. (JP-A-6-
342002).

In the electromagnetic sensor of this type, the sensitive element part manufactured first is inserted into a mold, and molten resin is injected into a cavity formed between the inner surface of the mold and the outer surface of the sensitive element part. By doing so, the whole is integrally configured. Therefore, when forming the coating portion around the sensitive element portion, the sensitive element portion must be stably fixed in the mold.

On the other hand, when the electromagnetic sensor as described above is used in the rotation speed detector, in order to improve the magnetic efficiency, it is necessary to cut the tip of the pole piece in accordance with the tooth profile of the pulsar gear.

[0005]

However, if the tip end of the pole piece is cut, the strength is reduced, so it is desirable to protect the tip of the pole piece by resin molding to the full extent, and also to prevent the pole piece from rotating. Although it can be achieved, it is difficult to hold the pole piece in the center of the mold if the tip is to be molded.

According to the present invention, the problems imposed on the prior art can be solved, and the molten resin can be made to flow into the tip of the pole piece after the pole piece is securely held in the center of the mold. The present invention has been devised for the purpose of providing an electromagnetic sensor provided with the mold positioning means configured as described above.

[0007]

In order to achieve such an object, according to the present invention, there is provided a sensitive element portion having a bobbin around which a coil is wound and a pole piece inserted through the central portion of the bobbin. In an electromagnetic sensor that inserts into the mold and injects molten resin to form a coating around the sensitive element, the inside of the mold that molds around the tip of the pole piece The bobbin is provided with a plurality of axially extending portions that can be brought into close contact with the peripheral surface, and the molten resin is allowed to flow into the tip portions of the pole pieces through the gaps between the extending portions.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an electromagnetic sensor constructed according to the present invention. The electromagnetic sensor 1 is formed by integrally molding a housing part 3 covering the periphery of a sensitive element part 2 described below, a mounting stay part 4 for the vehicle body, and a cable pulling part 5 with a synthetic resin material. The mounting stay 4
A metal collar 6 for receiving a bolt tightening force is inserted in the.

The sensitive element section 2 is manufactured in a separate process. As shown in FIG. 2, the sensitive element portion 2 has a bobbin 7 injection-molded of a synthetic resin material and a pair of terminal members 8 press-fitted and fixed to one end face of the bobbin 7 in the axial direction. A coil 9 composed of a conductive wire that is wound around the bobbin 7, a pole piece 10, a permanent magnet 11 and a yoke 12 mounted in the center hole of the bobbin 7, and a connector (Fig. Lead wire 13 connected via (not shown).

As shown in FIG. 3, the end of the conductor wire 14 of the coil 9 is insulated from the surface of the conductor wire by applying a current to the conductor holding portion 15 of the terminal member 8 with which the terminal is entwined and crimping the electrode. The layers are melted by heat, the copper layer of the conductive wire 14 and the tin layer plated on the terminal member 8 are melted, and fused to the conductive wire holding portion 15 by fusing.

In the lead wire 13, a copper layer of the lead wire 13 and a tin layer plated on the terminal member 8 are melted by applying an electric current to the lead wire holding portion 16 of the terminal member 8 while crimping the electrode. In addition, the solder previously applied to the end of the lead wire 13 melts into the entire joint,
It is firmly joined to the lead wire holding portion 16. High-temperature solder is used as the solder.

Then, the lead wires 13 are lightly press-fitted into the holding grooves 17 formed in the one end surface of the bobbin 7 to prevent the lead wires 13 from being displaced. A cable retainer 18 is previously molded on the coating of the lead wire 13.

By the way, the tip portion 10 of the pole piece 10
A is cut corresponding to the tooth profile of the pulsar gear. In order to resin-mold the cut tip portion 10a as well, the lower end of the bobbin 7 is equally divided into positions at the circumference.
A plurality of (about 2 to 4 places, 4 places in this embodiment) axially extending portions 22 are formed, and the axially extending portions are formed on the inner peripheral surface of the corresponding recesses 23 formed in the lower mold 19. The tip of the projecting portion 22 is held (see FIG. 4). With it
A plurality of protrusions 2 protruding from the bottom surface of the bobbin receiving portion of the lower mold 19.
The lower surface of the flange 25 of the bobbin 7 is brought into contact with the shaft 4. These ensure that the sensitive element portion 2 is positioned within the lower mold 19.

On the other hand, on the upper end surface of the bobbin 7, three pointed projections 26 having pointed tips are provided at equal intervals in the circumferential direction. Correspondingly, the inner surface of the upper mold 20 is provided with three positioning protrusions 28 each having a tapered hole 27 capable of complementarily receiving the pointed protrusion 26. As a result, when the mold is closed, the three pointed projections 26 on the upper end surface of the bobbin 7 are fitted into the tapered holes 27 while being guided by the slopes of the tapered holes 27, and the sensitive parts in the molds 19 and 20. The misalignment of the element unit 2 is corrected, and the sensitive element unit 2 is formed by the mold 19.
It is securely fixed in 20. Here, the pedestal 2 of the pointed portion 26
A flat surface is formed on the upper surface of 9, and after the pointed projection 26 is fitted into the tapered hole 27, the lower surface of the positioning projection 28 presses the upper surface of the pedestal 29 for axial positioning. It has become. Therefore, the pressing force does not act on the tip of the pointed portion 26 with the upper die 20 closed.

In this way, the sensitive element portion 2 and the metal collar 6 are set in the lower die 19 and the upper die 20 is closed, and the cavity formed between the outer surface of the sensitive element portion 2 and the inner surface of the lower die 19. By injecting the molten resin from the gate 21,
As also shown in FIG. 5, the sensitive element portion 2 and the collar 6
With the housing part 3 and the stay part 4 inserted
Are integrally formed.

The resin injection gate 21 is provided on the upper mold 20 so as to be located on the center line of the sensitive element section 2. Therefore, the molten resin injected from the gate 21 uniformly flows in all directions of the outer periphery of the sensitive element portion 2 and finally covers the entire periphery of the sensitive element portion 2. At this time,
The molten resin is a gap G1 between the lower surface of the flange 25 of the bobbin 7 formed by the plurality of protrusions 24 and the bottom surface of the lower mold 19.
Also, it flows into the periphery of the tip portion 10a of the pole piece 10 through the gap G2 between the plurality of extending portions 22, and the periphery of the tip portion 10a of the pole piece 10 is also resin-molded.

In the dies 19 and 20 shown in FIG. 2, only the cut end face is shown. Further, a portion of the recess 23 that receives the pole piece 10 is shown in a cross section taken along line II-II in FIG.

[0019]

As described above, according to the present invention, the center of the pole piece is securely held in the mold and the molten resin easily flows into the tip of the die, so that the tip of the pole piece is cut. However, the tip can be fully molded. Therefore, enhance the protection effect of the tip of the pole piece,
And the pole piece can be stopped.

[Brief description of the drawings]

FIG. 1 is a perspective view of an electromagnetic sensor according to the present invention.

FIG. 2 is a vertical sectional view showing a state in which a sensitive element portion and a collar are set in a mold.

FIG. 3 is a perspective view of a main part of a sensitive element section.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is a vertical cross-sectional view showing a state in which a sensitive element portion and a collar are molded in a mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic sensor 2 Sensitive element part 3 Housing part 4 Mounting stay part 5 Cable extension part 6 Metal collar 7 Bobbin 8 Terminal member 9 Coil 10 Pole piece 11 Permanent magnet 12 Yoke 13 Lead wire 14 Conductive wire 15 Conductive wire holding portion 16 Lead wire holding Part 17 Retaining groove 18 Cable retainer 19 Lower mold 20 Upper mold 21 Resin injection gate 22 Axial extension 23 Recess 24 Projection 25 Flange 26 Sharp projection 27 Tapered hole 28 Positioning projection 29 Pedestal

Claims (1)

[Claims] 1. A sensitive element part having a bobbin around which a coil is wound and a pole piece inserted through the center of the bobbin is inserted into a mold to inject a molten resin, whereby the sensitive element part An electromagnetic sensor configured to form a coating portion on the periphery thereof, wherein the bobbin is provided with a plurality of axially extending portions that can be brought into close contact with an inner peripheral surface of a mold for molding the periphery of the tip portion of the pole piece. An electromagnetic sensor, wherein the electromagnetic sensor is provided so that the molten resin flows into the tip portion of the pole piece through a gap between the extending portions.