JP2004012190A - Rotation detection sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance sealability of a space between a rotation detection sensor and a vehicle body side. <P>SOLUTION: On a ring-like base part of a bracket 7 to be mounted on a vehicle body and fitted into a casing 1 of the sensor, an annular groove 7b running along the periphery of the casing 1 is provided over the entire circumference. When an exterior resin 6 is molded, for covering a connection part between a detection part 2 and a cable 4, its periphery, and the bracket 7 base part, the annular groove 7b is filled with a sealant 8 thereby making it hard for the sealant 8 to flow out of the groove 7b, thus enhancing the sealability of a space between the resin 6 after the molding and the bracket 7 base part. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation detection sensor such as an automobile wheel speed sensor and an engine speed sensor.
[0002]
[Prior art]
2. Description of the Related Art Generally, an automobile incorporates several types of rotation detection sensors, such as a sensor for detecting a rotation speed of a wheel and a sensor for detecting a rotation speed of an engine. An example of the wheel speed sensor is shown in FIG. In this wheel speed sensor, a detection unit 52 is housed in a covered cylindrical casing 51 provided to face the object B to be detected, and the detection unit 52 is connected to an output cable 54 via a relay terminal 53 and detected. The holder 55 holding the part 52 is fitted into the opening of the casing 51, and the connecting part between the detecting part 52 and the cable 54 and its surroundings are covered with an exterior resin 56. A base of a mounting bracket 57 formed in a ring shape is fitted on the outer diameter surface of the casing 51, and the sensor is mounted on the vehicle body by the bracket 57.
[0003]
The detected object B generates a magnetic field fluctuation by rotation, and has a ferromagnetic pulsar ring provided with gear-shaped teeth on the peripheral edge as shown in FIG. 3 or an S pole and an N pole on the peripheral surface. Are magnetized so that 現 れ る appear alternately and continuously in the circumferential direction.
[0004]
On the other hand, the detection unit 52 includes a magnetic detection IC chip and an electronic component (circuit) for controlling the same, as disclosed in JP-A-5-302932 and JP-A-7-198736. A pole piece provided inside a bobbin for winding and holding a coil and having a magnet on the rear side of the pole piece (electromagnetic pickup) or the like, which is disclosed in Japanese Patent No. 302932 or the like, is employed.
[0005]
A seal member 58 is provided annularly along the outer periphery of the casing 51 on the side of the casing 51 at the base of the bracket 57 along the outer periphery of the casing 51. It is formed from the connection with the cable 54 to the base of the bracket 57.
[0006]
The sealing material 58 is for protecting the connecting portion between the detecting portion 52 and the cable 54 by preventing intrusion of water or the like from the vehicle body side, and is easily performed by heating and melting a hot melt adhesive or the like. A material that can be attached to the surface of the bracket 57 and has a strong adhesive force to the exterior resin 56 at room temperature is used.
[0007]
This wheel speed sensor has the above configuration, and detects a magnetic field variation due to the rotation of the detection target B by the detection unit 52 and converts it into an electric signal. This electric signal is output to the outside by a cable 54 via a relay terminal 53. Output. Then, in order to stabilize the output signal, the connection between the detection unit 52 and the cable 54 and the periphery thereof are covered with the exterior resin 56, and a sealing material 58 is interposed between the exterior resin 56 and the bracket 57 base. In this way, the sealing performance with the vehicle body is ensured.
[0008]
However, since the sealing material 58 such as a hot melt adhesive generally has a slightly lower melting point than the exterior resin 56 such as nylon, the surface is melted by the heat received from the resin 56 when the resin 56 is heated and melted. As a result, the fluid flows along the surface of the bracket 57, and there is a possibility that sufficient sealing properties cannot be obtained. As a result, water or the like may enter between the resin 56 and the bracket 57 during use of the sensor, causing an abnormality in the output signal and shortening the life of the sensor.
[0009]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to improve the sealing performance between the rotation detection sensor and the vehicle body.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides an output cable in which a detection unit that detects a magnetic field fluctuation due to rotation of a detection target and converts the detection into an electric signal is housed in a covered cylindrical casing in which a mounting bracket is fitted. In a rotation detection sensor in which the connecting portion between the detecting portion and the cable and the periphery thereof are covered with the outer resin by covering the bracket, an annular groove is provided along the outer periphery of the casing on the resin-coated surface of the bracket. That is, a structure filled with a sealing material was adopted.
[0011]
That is, by filling the sealing material into the annular groove provided on the resin-coated surface of the bracket, when molding the exterior resin, even if the sealing material surface melts, the unmelted portion of the sealing material is covered by the side wall of the annular groove. By locking and making it difficult to flow out of the groove, the sealing property between the molded exterior resin and the bracket was improved.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. This rotation detection sensor is a wheel speed sensor that detects the rotation speed of the wheels of an automobile. As shown in FIG. 1, a detection unit 2 that detects a magnetic field fluctuation is housed in a covered cylindrical casing 1. The detection unit 2 is connected to the output cable 4 via the relay terminal 3, the holder 5 holding the detection unit 2 is fitted into the opening of the casing 1, and the connection between the detection unit 2 and the cable 4 and its surroundings are covered with an exterior resin. 6. Then, the magnetic field fluctuation generated by the object to be detected (not shown) is detected by the detection unit 2 and converted into an electric signal, and the electric signal is sent to an external controller (not shown) via the cable 4 via the relay terminal 3. The output is then converted by the controller to the rotational speed of the wheels.
[0013]
A base of a mounting bracket 7 formed in a ring shape is fitted into the outer diameter surface of the casing 1. Then, as shown in FIG. 2, the sensor is attached to the vehicle body by an attachment hole 7a provided at the tip of the bracket 7.
[0014]
As shown in FIG. 1, an annular groove 7b along the outer periphery of the casing 1 is provided over the entire periphery of the opening side of the casing 1 at the base of the bracket 7, and the annular groove 7b is filled with a sealing material 8. Have been. For the sealing material 8, a hot melt adhesive mainly composed of polyamide is used. The exterior resin 6 is formed from the connection between the detection unit 2 and the cable 4 to the base of the bracket 7 so as to cover the sealing material 8.
[0015]
Thereby, even when the surface of the sealing material 8 is melted by receiving heat from the resin 6 when the exterior resin 6 is molded, the unmelted portion is locked to the side wall of the annular groove 7b and goes out of the groove 7b. A sufficient sealing property can be obtained without flowing.
[0016]
That is, in this wheel speed sensor, since the sealing property between the exterior resin 6 and the base 7 of the bracket on the vehicle body side is high, there is little possibility that water or the like enters the resin 6 coating portion, and the detection unit 2 and the cable 4 is reliably protected, and a signal can be output stably.
[0017]
Further, the difference from the conventional sensor is only that the annular groove 7b is provided in the base of the bracket 7, so that the cost increase is very small.
[0018]
In the above-described embodiment, the hot melt adhesive is used as the sealing material, but a viscoelastic liquid gasket may be used. The liquid gasket, like the hot melt adhesive, can be easily filled into the annular groove, and a stable adhesive force can be obtained between the bracket and the resin after molding the exterior resin. In addition, even if the resin expands or contracts due to a change in temperature during use of the sensor, the resin can smoothly follow the deformation of the resin due to the elasticity after solidification and maintain the sealing property.
[0019]
The present invention is not limited to the wheel speed sensor described in the embodiment, but can be applied to other rotation detection sensors.
[0020]
【The invention's effect】
As described above, the present invention provides an annular groove on a resin-coated surface of a mounting bracket fitted into a casing of a rotation detection sensor, and fills the annular groove with a sealing material to form a seal when molding an exterior resin. Since the material is less likely to flow out of the annular groove, the sealing between the molded exterior resin and the bracket can be improved, and the connection between the sensor detection part and the cable is securely protected. As a result, the life of the sensor can be extended.
[Brief description of the drawings]
FIG. 1 is a partially cutaway front sectional view of a rotation detection sensor according to an embodiment; FIG. 2 is an arrow view from a direction A in FIG. 1; FIG. Explanation of code]
DESCRIPTION OF SYMBOLS 1 Casing 2 Detecting part 3 Relay terminal 4 Cable 5 Holder 6 Exterior resin 7 Bracket 7a Mounting hole 7b Annular groove 8 Seal material

Claims (1)

The detection unit 2 that detects a magnetic field fluctuation due to the rotation of the detection target B and converts it into an electric signal is housed in the covered cylindrical casing 1 in which the mounting bracket 7 is fitted, and is connected to the output cable 4. In the rotation detecting sensor in which the connecting portion between the cable 2 and the cable 4 and its periphery are covered with the bracket 7 and covered with the exterior resin 6, an annular groove 7b is provided along the outer periphery of the casing 1 on the surface of the bracket 7 covered with the resin 6. A rotation detection sensor characterized in that a sealing material 8 is filled in 7b.

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