JP2999407B2 - Electromagnetic sensor - Google Patents

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 in which a sensitive element is insert-molded.

[0002]

2. Description of the Related Art There is known an electromagnetic sensor in which a fixed portion to a vehicle body and a covering portion of a sensitive element portion are integrally formed by insert-molding a sensitive element portion including a coil, a pole piece, a permanent magnet, and a yoke. (Japanese Unexamined Patent Publication No.
No. 342002).

[0003] In such an electromagnetic sensor, a primary manufactured sensitive element portion 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 portion. By doing so, the whole is integrally configured. Therefore, when forming the covering around the sensitive element section, the sensitive element section must be stably fixed in the mold.

[0004]

However, when a positioning projection for engaging with the mold is provided on the sensitive element portion, the projection interferes with the flow of the molten resin, so that the projection is moved away from the center of the gate. The smooth flow of the resin is hindered, and air accumulation is likely to occur on the downstream side of the positioning protrusion P as indicated by reference numeral A in FIG. Therefore, there has been a problem that the adhesion between the sensitive element portion and the coating portion is partially reduced.

An object of the present invention is to solve the problems imposed on the prior art and to provide an electromagnetic sensor provided with a mold positioning means which is configured so as not to interfere with the flow of molten resin. It was devised.

[0006]

In order to achieve the above object, according to the present invention, the sensitive element portion is inserted into a mold, and a molten resin is injected to cover the periphery of the sensitive element portion. In the electromagnetic sensor which forms a portion, a plurality of positioning protrusions which can be engaged with the mold are circumferentially arranged on a circumference centered on the resin injection gate at one axial end surface of the sensitive element portion. The shape of the portion of the positioning projection facing the cavity is such that the circumferential dimension gradually decreases as the distance from the center of the gate increases.

[0007]

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. In the electromagnetic sensor 1, a housing 3, which covers the periphery of a sensitive element 2, which will be described later, a mounting stay 4, which is attached to the vehicle body, and a cable lead-out portion 5, are integrally formed of a synthetic resin material. The mounting stay 4
, A metal collar 6 for receiving a bolt tightening force is inserted.

The sensitive element section 2 is manufactured in a separate process. As shown in FIG. 2, each of the sensitive element portions 2 has a bobbin 7 formed by injection molding of a synthetic resin material and a pair of terminal members 8 press-fitted and fixed to one end surface of the bobbin 7 in the axial direction. And a coil 9 composed of a conductive wire wound around the bobbin 7 with a pole piece 10, a permanent magnet 11, and a yoke 12 mounted in the center hole of the bobbin 7, and connectors (FIG. (Not shown).

As shown in FIG. 3, the terminal of the conductive wire 14 of the coil 9 is electrically connected to the conductive wire holding portion 15 of the terminal member 8 where the terminal is entangled, and an electric current is caused to flow therethrough. The layer is melted by heat, and the copper layer of the conductor 14 and the tin layer plated on the terminal member 8 are melted and fused to the conductor holding part 15.

The lead 13 is made to melt by melting the copper layer of the lead 13 and the tin layer plated on the terminal member 8 by applying an electric current to the lead holding portion 16 of the terminal member 8 while crimping the electrode. And 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 part 16. Note that high-temperature solder is used as the solder.

Each lead wire 13 is lightly press-fitted into a holding groove 17 formed on one end surface of the bobbin 7, thereby preventing the lead wire 13 from shifting. Note that a cable retainer 18 is molded in advance on the covering of the lead wire 13.

Sensitive element part 2 assembled in this way
And the metal collar 6 are set in the lower mold 19 and the upper mold 2
0, and the molten resin is injected from the gate 21 into the cavity formed between the outer surface of the sensitive element section 2 and the inner face of the lower mold 19, as shown in FIG. 6 with the housing part 3 inserted
And the stay part 4 are integrally formed.

At this time, a plurality (about 2 to 4 places, in this embodiment, 4 places) of axially extending portions 22 formed at the lower end of the bobbin 7 at positions dividing the circumference equally are shown in FIG. As shown in FIG. 4, the bobbin 7 is supported by the inner peripheral surface of the corresponding recess 23 formed in the lower die 19 and the plurality of protrusions 24 projecting from the bottom surface of the bobbin receiving portion of the lower die 19. Flange 25
When the lower surface of the sensor element abuts, the sensitive element portion 2 is positioned in the lower mold 19.

On the other hand, on the upper end surface of the bobbin 7, three sharp protrusions 26 having sharp tips are projected at equal intervals in the circumferential direction. Correspondingly, three positioning projections 28 are formed on the inner surface of the upper mold 20 so as to have tapered holes 27 that can receive the pointed projections 26 in a complementary manner. Thus, 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 sensitivity in the molds 19 and 20 is increased. The misalignment of the element 2 is corrected, and the sensitive element 2 is
It is securely fixed in the inside 20. Here, the pedestal 2 of the pointed projection 26
9 is formed with a flat surface, and after the pointed protrusion 26 is fitted into the tapered hole 27, the lower surface of the positioning protrusion 28 presses the upper surface of the pedestal 29 so that positioning in the axial direction is performed. It has become. Therefore, no pressing force acts on the tip of the pointed projection 26 with the upper mold 20 closed.

Incidentally, 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 flows uniformly in all directions on the outer periphery of the sensitive element section 2, and finally covers the entire periphery of the sensitive element section 2. Here, as shown in FIG. 6, the pedestal 29 of the pointed projection 26 has a shape in which the circumferential dimension gradually decreases outward in the radial direction, so that the molten resin flows from the gate 21 of the pedestal 29 as indicated by the arrow. It flows smoothly into the far surface. Therefore, since no air accumulation occurs in the same portion, generation of a weld mark can be prevented. Further, the molten resin passes through the 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 and the gap G2 between the plurality of extending portions 22 to form the pole piece. The resin also flows into the tip 10a of the pole piece 10 and the area around the tip of the pole piece 10 is also resin-molded.

The dies 19 and 20 in FIG. 2 show only cut end faces. The section of the recess 23 for receiving the pole piece 10 has a cross section along the line II-II in FIG.

[0018]

As described above, according to the present invention, since the molten resin easily flows around the positioning portion for the die, air accumulation is hardly generated in the same portion. Therefore, when the electromagnetic sensor is subjected to insert molding, the adhesion between the sensitive element portion and the covering portion is enhanced, and a great effect can be obtained in obtaining good waterproofness.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view showing a state where 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 unit.

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

FIG. 5 is a longitudinal sectional view showing a state in which molding is performed in a mold.

FIG. 6 is an end view of the bobbin.

FIG. 7 is a schematic diagram of a main part for describing inconvenience of the related art.

[Description of Signs] 1 Electromagnetic sensor 2 Sensitive element section 3 Housing section 4 Mounting stay section 5 Cable lead-out section 6 Metal collar 7 Bobbin 8 Terminal member 9 Coil 10 Pole piece 11 Permanent magnet 12 Yoke 13 Lead wire 14 Lead wire 15 Lead wire holding Part 16 Lead wire holding part 17 Holding groove 18 Cable holding 19 Lower die 20 Upper die 21 Resin injection gate 22 Axial extension 23 Depression 24 Projection 25 Flange 26 Pointed projection 27 Tapered hole 28 Positioning projection 29 Base

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-311211 (JP, A) JP-A-5-313822 (JP, A) JP-A-7-27775 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) G01P 3/488 G01P 3/487 G01D 5/245 G01P 1/02 G01P 3/04

Claims (2)

(57) [Claims] 1. An electromagnetic sensor in which a sensitive element section is inserted into a mold and a molten resin is injected to form a coating section around the sensitive element section, wherein an axis of the sensitive element section is provided. A positioning protrusion that can be engaged with the mold is projected on one end surface in the direction, and the shape of a portion of the positioning protrusion facing the inside of the cavity has a dimension perpendicular to a resin streamline as the distance from the center of the resin injection gate increases. An electromagnetic sensor characterized by gradually decreasing. 2. The electromagnetic sensor according to claim 1, wherein a plurality of the positioning projections are provided on a common circumference centered on the gate and are spaced apart from each other in a circumferential direction.