JPH07325100A - Wheel speed sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] A wheel speed sensor that prevents breakage and breakage of a winding coil wound around an electromagnetic power generation type wheel speed sensor and prevents water from entering from the outside. [Structure] Functional components of a magnet 2, an iron core 3, and a winding coil 5 are integrally fixed by a resin portion 9 and housed in a housing 1, and the entire outer peripheral portion is integrally molded by another resin molded body 11. It will be done. The lower end flange portion of the coil bobbin 4 and the lower bottom portion of the housing are doubly overlapped to prevent the winding coil 5 from being broken by the resin that flows in when the resin molded body 11 is injection-molded, and the sealing seal 20 allows water to enter. Are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a wheel speed sensor for detecting the rotation speed of automobile wheels and the like.

[0002]

2. Description of the Related Art An electromagnetic power generation type wheel speed sensor has high sensitivity even under severe conditions such as strong impact such as when detecting the rotation speed of an automobile wheel due to its structure being robust. It can detect the rotation speed stably and is widely used.

An example of the wheel speed sensor is shown in FIG. The illustrated wheel speed sensor is provided by joining a magnet 2 and an iron core 3 in a housing 1 made of non-magnetic metal, winding a coil 5 around the outer circumference of a bobbin 4 surrounding the iron core 3, and a yoke on the opposite side of the magnet 2. 6, the terminal 8 connected to the coil is projected from the housing 1, the upper portion is closed by the resin portion 9, the output wire 10 is connected to the terminal 7, and the connection portion is fixed by the resin forming body 11. . Reference numeral 12 denotes a mounting bracket, which is fixed to the housing 1 by copper brazing 12.

The illustrated wheel speed sensor is called a pole piece protruding type, and the iron core 3 has a pole piece 1 made of the same material.
3 is provided so as to project to the outside of the housing 1. In this formation type, the pole piece 13 can be provided closer to the sensor rotor X than in the type in which the iron core 3 is built in, and therefore the rotational speed can be detected with higher sensitivity. The joint 14 where the pole piece 13 projects from the housing 1 is sealed by laser welding.

FIG. 3 shows another conventional electromagnetic rotation sensor. The same functional members as those in the example of FIG. 2 are designated by the same reference numerals. The basic structure is almost the same as that of FIG. 2, but the housing 1 is integrally formed with the upper resin molded body 11,
The coil bobbin 4 is integral with the resin portion 9, and a tubular member 15 is provided on the outer periphery of the coil 5 which is a little different. The tubular member 15 is for protecting the coil 5 from the thermal influence at the time of resin molding of the housing 1.

[0006]

However, in the conventional wheel speed sensor shown in FIG. 2, copper brazing is performed to fix the bracket, and the pole piece protruding outward is fixed to the housing to ensure airtightness. Laser welding or copper brazing is performed to achieve this, but both require complicated work and require a long process time.In laser welding, processing accuracy such as squareness between the iron core and the housing end face is low, and copper brazing is required. In addition, there are various problems such that the core of the magnetic circuit component is exposed to high heat and the magnetic characteristics are deteriorated.

In the electromagnetic type rotation sensor of the conventional example shown in FIG. 3, the housing is made of a resin molding and a resin material so as to reduce the manufacturing cost. A tubular member is provided to prevent disconnection and damage due to the effect of high temperature. However, only by providing the tubular member 15, it is possible for high-pressure and high-temperature resin to flow into the coil due to the pressure at the time of resin molding from the gap where the inner circumference of the tubular member indicated by the arrow contacts the coil bobbin. There is a property, and the tubular member alone is insufficient. or,
The sealing property of the member from which the pole piece projects from the housing is not sufficient.

In the present invention, paying attention to various problems of the above-described conventional wheel speed sensor or electromagnetic type rotation sensor, the winding coil provided inside the housing of the sensor is injection-molded on the top or the whole. Prevents high-pressure and high-temperature resin from entering and causing wire breakage and damage when it is protected and fixed as a resin molded body, and the lower bottom of the housing is surrounded by the resin outer peripheral part, and the gap between the protruding part of the iron core An object of the present invention is to provide a wheel speed sensor that prevents water from entering and is less likely to cause a failure.

[0009]

As a means for solving the above problems, the present invention integrates a magnet, an iron core, an output terminal and the like with a resin forming body including a coil bobbin, and winds a winding coil around the coil bobbin. The functional parts are housed in a non-magnetic housing, and while the output wire is connected to the output terminal, the entire outer peripheral part of the iron core except for the projecting part and the output wire is made of thermoplastic resin. A wheel speed sensor is provided in which a lower bottom portion of the housing is provided so as to overlap the lower end flange portion, and a hermetic seal is provided at a joint portion of the three members of the housing, the iron core, and the resin portion.

As one mode of the wheel speed sensor, a mounting bracket is press-fitted into the housing, and the lower bottom portion of the housing is fitted with an interference fit at a portion where the iron core protruding portion penetrates. preferable.

[0011]

The wheel speed sensor having the above-mentioned structure basically operates in the same manner as the conventional electromagnetic power generation type and the protruding type of the iron core. Since the change in the detection signal is large, the wheel speed sensor has a high sensitivity. Detect the rotation speed.

When the wheel speed sensor is manufactured, a magnet, an iron core, an output terminal, etc. are put in and integrated with a resin including a coil bobbin, and a winding coil is wound around the coil bobbin and put in the housing. Most of the outer peripheral portion is surrounded and integrated with another resin molded body. Therefore, even when the resin molding on the outer peripheral portion is molded by injection molding, high-temperature, high-pressure resin does not enter the winding coil, preventing the winding coil from being damaged or broken by the resin. To be done.

As in the second aspect of the invention, when the outer peripheral portion is integrated with the resin molding, a mounting bracket is provided on the housing to facilitate mounting.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a main sectional view of a wheel speed sensor of the embodiment. The basic principle is the electromagnetic power generation type as in the past,
The same functional parts are designated by the same reference numerals and the description thereof will be omitted, and the characteristic part of this embodiment will be mainly described.

First, the iron core 3 is of a protruding type in which a pole piece is integrally formed, and the coil bobbin 4 and the resin portion 9 are integrally formed of the same resin material. The functional parts including the above (the magnet 2, most of the iron core 3, the winding coil 5, the yoke 6,
The terminals 8 and the like) are housed in the non-magnetic housing 1.

The housing 1 is formed so that the lower end flange portion of the coil bobbin 4 and the lower bottom portion of the housing 1 overlap with each other, and the portion where the projecting portion of the iron core 3 penetrates the lower bottom portion is an interference fit. Is fitted to. The nonmagnetic housing 1 is made of austenitic stainless steel, for example. The resin portion 9 is made of nylon 66, for example, and is integrally formed by injection molding or the like including the functional parts. The output terminal 8 is provided so that the upper end thereof protrudes from the resin portion 9. A mounting bracket 12 is press-fitted onto the outer periphery of the housing 1.

Further, the functional component in the integrally formed housing 1 is wholly surrounded by another resin molding 11 in a state where the output wire 10 is connected to the output terminal 8 and is integrally molded. However, the protruding portion of the iron core 3, the output wire 10, and the mounting bracket 12 are excluded. The resin molded body 11 is molded by high temperature, high pressure injection molding. As the resin, for example, nylon 66 is used as in the resin portion 9. At the time of injection molding, resin flows into the groove 12a provided in the mounting bracket 12 to fix the housing 1 and the resin molded body 11 to each other.

A sealing seal 20 is provided at a portion where the projecting portion of the iron core 3 penetrates the lower bottom of the housing 1 and the lower end of the resin molded body 11. The hermetic seal 20 is made of a polyamide resin.

The wheel speed sensor having the above-mentioned structure is used as a pair with a sensor rotor in the same manner as in the conventional example to detect the rotation speed. The basic operating principle is the same as that of the conventional example, and since the iron core 3 is of the protruding type, the change in the detection signal is large and the speed detection is performed with high sensitivity.

Further, even when the entire exterior is integrated as the resin molded body 11 by injection molding, since the lower bottom portion of the housing 1 is double provided with the lower end flange portion of the coil bobbin 4, a gap between the housing and the coil bobbin is provided. The resin is prevented from flowing backward by pressure and pushed in.

Further, since the sealing seal 20 is provided at the joint between the lower bottom of the housing 1 and the lower end of the resin molded body 11, it is possible to prevent water from entering through the gap with the iron core 3 during use. To be done.

[0022]

As described in detail above, the wheel speed sensor of the first invention of this application has a structure in which the lower end of the coil bobbin and the lower bottom part of the housing are overlapped to form a double housing.
Since a sealing seal is provided at the joint of the iron core and the resin part, it prevents the high temperature and high pressure resin from entering the winding coil when forming the resin molded body on the entire outer peripheral part of the housing. The wheel speed sensor is completely sealed, which prevents wire breakage and breakage of the coil, and prevents water from entering with a hermetic seal. It is easy to process and mold, has excellent airtightness, and is an economical sensor. There is an advantage.

According to the second aspect of the invention, the mounting bracket is mounted on the housing, and the fitting of the portion where the iron core protruding portion penetrates the lower bottom portion of the housing is an interference fit. Therefore, a wheel speed sensor having higher airtightness can be obtained. The advantage of being able to be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a main sectional view of a wheel speed sensor according to an embodiment.

FIG. 2 is a main sectional view of a conventional wheel speed sensor.

FIG. 3 is a main cross-sectional view of another conventional electromagnetic rotation sensor.

[Explanation of symbols]

 1 Housing 2 Magnet 3 Iron Core 4 Coil Bobbin 5 Winding Coil 6 Yoke 8 Output Terminal 9 Resin Part 10 Output Wire 11 Resin Molded Body 12 Mounting Bracket

Claims (2)

[Claims] 1. A magnet, an iron core, an output terminal and the like are integrated with a resin forming body including a coil bobbin, a winding coil is wound around the coil bobbin, and these functional components are housed in a non-magnetic housing to form an output terminal. With the output wire connected, the entire outer peripheral part of the iron core except the protruding part and the output wire is molded with a thermoplastic resin, and the housing lower bottom part is provided so that the lower housing bottom part and the coil bobbin lower end flange part overlap with each other. A wheel speed sensor provided with a hermetic seal at a joint portion of three members including an iron core, and a resin portion. 2. The wheel according to claim 1, wherein the mounting bracket is press-fitted into the housing in the first term, and the fitting of a portion where the iron core protruding portion penetrates the lower bottom portion of the housing is an interference fit. Speed sensor.