JPH07167875A - Electromagnetic sensor - Google Patents

Abstract

PURPOSE:To provide an electromagnetic sensor in which a position of an end of a pole piece to a reference surface of a stay can be simply and effectively specified. CONSTITUTION:An electromagnetic sensor comprises a sensor body 8 formed by covering a coil bobbin 4 wound with a lead 3, a pole piece 5 engaged with a center of the bobbin and a permanent magnet 6 arranged at an end of the piece 5 with synthetic resin material, and a stay 11 formed of a synthetic resin material and having a sensor body holder for tightly receiving an end of the body 8 in a predetermined axial sizes. A position of the end of the piece 5 to a reference surface of the stay 11 is specified by a stroke of an ultrasonic welder when the holder is integrally coupled to the end of the body by ultrasonic fusion bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave having a coil bobbin around which a conductive wire is wound, a pole piece fitted in the center of the coil bobbin, and a permanent magnet arranged at the end of the pole piece. It relates to a sensor.

[0002]

2. Description of the Related Art As a sensor for detecting the rotational speed of an automobile engine or wheels, an electromagnetic wave utilizing a voltage induced by a change in magnetic flux when a magnetic body comes into contact with and separates from a permanent magnet around which a coil is wound. Many sensors are used.

In this electromagnetic sensor, constituent elements such as a permanent magnet, a coil, and a pole piece are housed in a case, and the case is connected to a stay for attachment to a vehicle body, and an opening of the case and a stay. By filling a potting material made of synthetic resin or the like at the joint with the case, the unit is integrally formed (JP-A-63-2).
85414).

By the way, since the distance between the pole piece and the magnetic material which comes into contact with and separates from the pole piece greatly affects the sensitivity characteristic,
These mechanical dimensions must be tightly controlled.

[0005]

However, according to the above-mentioned conventional type electromagnetic sensor, if there are variations in the manufacturing dimensions of each element constituting the sensor, the tip of the pole piece with respect to the vehicle body mounting reference plane of the stay will be assembled when assembled. Individual differences occur in the position of. Therefore, it is necessary to control the dimensional accuracy by using a special jig or gauge at the time of assembly, and the assembly process tends to be complicated.

The present invention has been devised in order to eliminate such disadvantages of the prior art, and its main purpose is to:
An object of the present invention is to provide an electromagnetic sensor that can easily and reliably define the position of the tip of the pole piece with respect to the reference surface of the stay.

[0007]

According to the present invention, there is provided a coil bobbin formed by winding a conductive wire, a pole piece fitted in the center of the coil bobbin, and an electromagnetic sensor. A sensor body formed by covering a permanent magnet disposed at the end of the pole piece with a synthetic resin material, and a sensor body formed of a synthetic resin material, and the end portion of the sensor body being closely packed with a predetermined axial dimension. A stay provided with a sensor body holding portion for receiving the position of the tip of the pole piece with respect to the reference surface of the stay when the sensor body holding portion and the sensor body end portion are integrally joined by ultrasonic welding. Of the ultrasonic welding machine of FIG.

[0008]

According to this structure, in the step of connecting the sensor body and the stay, the sensor body is fitted into the sensor body holding portion of the stay and the ultrasonic cone of the ultrasonic welding machine is pressed to contact the stay. The position of the tip of the pole piece with respect to the reference plane is defined.

[0009]

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

1 to 3 show an electromagnetic sensor constructed according to the present invention. The electromagnetic sensor 1 includes a coil bobbin 4 formed by winding a conductor 3 around a bobbin 2 injection-molded of nylon resin, a generally cylindrical pole piece 5 fitted in a center hole of the coil bobbin 4, and a pole piece 5. A sensor main body 8 including a permanent magnet 6 joined to one end of the permanent magnet 6 and a yoke 7 joined to the side opposite to the pole piece of the permanent magnet 6, and a stay 11 including a sensor main body mounting portion 9 and a mounting bracket 10 for the vehicle body. Has been done.

Each end of the conductive wire 3 wound around the bobbin 2 is connected to a pair of male terminals 12 press-fitted to the bobbin 2 by fusing.

The sensor main body 8 is formed by sequentially assembling the above-mentioned elements and then inserting the same into a mold, and molding the periphery except for the other end of the pole piece 5 and the connecting portion of the male terminal 12 into a substantially cylindrical shape with nylon resin or the like. It is molded. An annular protrusion 8a is formed on the outer peripheral surface of the sensor body over the entire circumference.

On the other hand, the stay 11 is injection-molded with nylon resin or the like, and the sensor body mounting portion 9 tightly receives the end portion of the sensor body 8 on the side where the male terminal 12 is led out. A concave portion 13 as a holding portion is formed. On the outer end side of the inner peripheral surface of this concave portion, a step portion 13a is formed over the entire circumference so as to receive the annular protrusion 8a of the sensor body 8. Further, the stay 1 is provided on the bottom surface of the recess 13.
1 is formed with a lead wire insertion hole 15 penetrating a boss 14 provided at the center of the outer surface of the lead wire 1.
The female terminal 17 to which the respective terminals 6 are coupled is fixed.
The mounting bracket 10 has a metal collar 1 for each.
A pair of bolt insertion holes 19 into which 8 are inserted are formed so that the tightening force when bolting to the vehicle body is received by each metal collar 18.

A rubber boot 20 for waterproofing is fitted on the inner surface of the lead wire insertion hole 15 in the boss 14.
And on the outer surface of the boss, the sleeve 2 for the cord clamp.
1 is fitted. The sleeve 21 is caulked inwardly at a portion adjacent to the base end portion of the boss 14 so that the boss 1
4 is integrally connected. Further, the sleeve 21 has a reduced diameter at a portion overlapping the rubber boot 20, and the urethane cabtire 22 having two cores is inserted into the lead wire insertion hole 15 and then the entire circumference thereof is caulked. Tightened so that there is no gap between them.

When connecting the sensor body 8 and the stay 11 to each other, an O-ring 23 is attached to the end of the sensor body 8.
Then, the sensor body 8 is fitted into the recess 13 while inserting the male terminal 12 on the sensor body side into the female terminal 17 in the recess. This temporary assembly is set in the ultrasonic welding machine, and the annular protrusion 8a formed on the outer peripheral surface of the sensor body 8 on one end side and the stepped portion 13a formed on the opening side of the recess 13 in the sensor body mounting portion 9 are formed. Weld the entire circumference of the joint. Here, the annular projection 8a and the stepped portion 13a have a margin for the lap margin in the axial direction, and the pressing stroke of the ultrasonic welding machine is defined with reference to the reference surface S of the mounting bracket 10. It has become so. Thus, at the time of this welding, the ultrasonic cone of the ultrasonic welding machine is pressed against the tip P of the pole piece and pushed down, so that the tip P of the pole piece with respect to the reference plane S of the mounting bracket 10 is pushed.
The position of is defined.

In this way, since the joint between the sensor body 8 and the mounting bracket 10 is ultrasonically welded all around, water does not enter from the joint, but the O-ring 2
Double waterproofing using 3 provides almost complete waterproofness.

[0017]

As described above, according to the present invention, since the position of the tip of the pole piece with respect to the reference surface of the stay can be defined easily and reliably, the assembling workability and the accuracy control are further promoted, and the manufacturing A great effect can be achieved in reducing the cost.

[Brief description of drawings]

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

FIG. 2 is a vertical sectional view of an electromagnetic sensor according to the present invention.

FIG. 3 is a plan view of a sensor body mounting surface of a stay.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic sensor 2 Bobbin 3 Conductive wire 4 Coil bobbin 5 Pole piece 6 Permanent magnet 7 Yoke 8 Sensor body 8a Annular protrusion 9 Sensor body mounting portion 10 Mounting bracket 11 Stay 12 Male terminal 13 Recess 13a Step portion 14 Boss 15 Lead wire insertion hole 16 Lead wire 17 Female terminal 18 Metal collar 19 Bolt insertion hole 20 Waterproof rubber boot 21 Sleeve 22 Urethane cab tire 23 O-ring

Claims (1)

[Claims] 1. A synthetic resin material covers a coil bobbin formed by winding a conductor wire, a pole piece fitted in the center of the coil bobbin, and a permanent magnet disposed at an end of the pole piece. And a stay formed of a synthetic resin material and provided with a sensor body holding portion that tightly receives the end portion of the sensor body with a predetermined axial dimension. An electromagnetic sensor, wherein the position of the tip of the pole piece is defined by the stroke of an ultrasonic welding machine when the sensor body holding portion and the sensor body end portion are integrally joined by ultrasonic welding.