JPH075184A - Magnetic rotation sensor - Google Patents

Abstract

PURPOSE:To provide a magnetic rotation sensor comprising a core, a magnet, a yoke, and a lead terminal integrally molded of a synthetic resin forming a bobbin in which the magnet and the yoke are prevented from shifting or touching the lead terminal due to the molding pressure. CONSTITUTION:In a magnetic rotation sensor 10 comprising a yoke 3, a magnet 2, and a core 1 integrally molded of a synthetic resin 6 forming a bobbin, a tubular member 5 is applied to the yoke 3 and the magnet 2 or to the yoke 3, magnet 2, and the core 1 and positioned thus preventing positional shift thereof at the time of molding. Since the magnet 2 and the yoke 3, which can not be secured using a mold because of their structure, can be secured by means of the tubular member 5 and the magnetic force of the magnet 2, the magnet 3 and the yoke 2 can be prevented from shifting or touching the lead terminals 4a, 4b due to the molding pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation sensor of a type having a coil wound around a core magnetized by a magnet and detecting a voltage induced in the coil by a change in magnetic flux passing through the core. In particular, the present invention relates to a magnetic rotation sensor suitable for detecting the number of revolutions of an automobile engine, the crank angle, and the vehicle speed.

[0002]

2. Description of the Related Art As a kind of rotation sensor for detecting the rotation speed and rotation angle of an engine or the like, a magnetic signal disk having a protrusion or a tooth profile formed on the outer periphery thereof, a yoke, and a magnet.
A magnetic rotation sensor including a (permanent magnet), a core, and a coil (electromagnetic pickup coil) wound around the core is known, and has been widely used from the past because of its small size, light weight, and high reliability.

As a magnetic rotation sensor of this type, a case member made of a synthetic resin material on which a bobbin for winding a coil is formed, as described in, for example, Japanese Utility Model Laid-Open No. 60-53060. After creating a magnetic circuit element consisting of a core, a magnet, and a yoke, a lead terminal for coil connection, etc. in it, insert a lid plate such as a synthetic resin body and adhere it. The unitized method was common.

However, in recent years, in order to improve work efficiency, it has been desired to omit the above-mentioned step of inserting and adhering the core, magnet, yoke, cover plate, etc. A magnetic rotation sensor has been used in which a magnetic circuit element including a magnet, a yoke and the like and a lead terminal are integrally molded with a synthetic resin member forming a bobbin.

In this prior art, the positioning of the magnet and the yoke to be integrated (molded) in the synthetic resin member at the time of integral molding is fixed by a molding die.

[0006]

The magnetic circuit elements such as the core, the magnet, and the yoke and the lead terminals described above are integrally molded with the synthetic resin member forming the bobbin, and are housed in the magnet and the yoke. In the conventional technique in which the position of the mold is integrally fixed at the time of molding, the work efficiency can be improved, but there are the following points to be improved.

That is, in the magnetic type rotation sensor, there is a market demand to increase the detection output voltage as much as possible, and in order to meet this demand, the volume of the core, the magnet, the yoke, and the number of turns of the electromagnetic pickup coil are increased. On the other hand, there is a contradictory market demand for miniaturization of the magnetic type rotation sensor. Therefore, there has been a problem that the structure for fixing the magnet and the yoke by the molding die cannot be taken during the integral molding.

However, if the magnet and the yoke are to be fixed only by the magnetic force of the magnet, not by the molding die, the position of the magnet and the yoke due to the pressure of the molten resin at the time of molding and the relocation -The problem of contact with the terminal will occur.

The object of the present invention is to provide a core, a magnet and a yoke.
In a magnetic type rotation sensor having a structure in which the crank and lead terminals are integrally molded with the synthetic resin member forming the bobbin, there is a gap between the magnet and the yoke that cannot be fixed by the molding die and the lead terminal An object is to provide a highly reliable electromagnetic rotation sensor that can reliably prevent contact at low cost.

[0010]

In order to achieve the above object, the present invention basically employs the following means. That is, in a magnetic type rotation sensor having a structure in which a magnetic circuit element including a core, a magnet, and a yoke and a lead terminal are integrally molded with a synthetic resin member forming a bobbin, the magnetic rotation sensor is integrated with the synthetic resin member having the bobbin. When molding,
When at least one of the magnet and the yoke cannot be fixed by the molding die because of the structure, the yoke and the magnet or the yoke, the magnet and the core are covered with a cylindrical member having insulation and heat resistance, Combined with the magnetic force of the magnet,
It is designed to be fixed to each other.

[0011]

The tubular member functions to position the yoke and the magnet, or the yoke, the magnet and the core with respect to each other. Therefore, in combination with the magnetic force of the magnet, the yoke and the magnet, or the yoke, the magnet, and the core are fixed to each other with a sufficient force, and are integrally molded with the synthetic resin member forming the bobbin. It is possible to sufficiently withstand the pressure of the molten resin that is applied at the time, and it is possible to reliably suppress the risk of misalignment and contact with the lead terminals.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic rotation sensor according to the present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is an embodiment of the present invention and shows a necessary portion in cross section. In this figure, 1 is a core, 2 is a magnet, 3 is a yoke,
Reference numerals 4a and 4b are lead terminals, 5 is a tubular member, 6 is a synthetic resin member integrally molded with the coil bobbin, 7 is a coil (electromagnetic pickup coil), and 8 is a synthetic resin mold molded body. The magnetic rotation sensor according to this embodiment is generally designated by 10.

The core 1 has an end portion which works as a magnetic pole close to the above-mentioned projection or tooth profile of the signal disk, and has a substantially columnar thick portion on the opposite side. A magnet 3 and a yoke 2 having the same thickness and having a substantially columnar shape are sequentially attached here.

Then, the coil 7 detects that the magnetic line of force passing from the magnet 2 to the core 1 is changed due to the change of the magnetic path due to the projection or tooth profile of the signal disk.

By the way, such a magnetic type rotation sensor is usually manufactured as follows. First, as shown in FIG. 2, the core 1, the magnet 2, and the yoke 3 are combined by utilizing the attractive force of the magnetic force of the magnet 2.

At this time, in the prior art, the combination of the core 1 and the lead terminals 4a and 4b is set and fixed as it is in a molding die of a synthetic resin member 6 having a bobbin, a connector portion and the like. Although it is integrally molded as shown in FIG. 3, in this embodiment, a tubular member 5 made of synthetic resin having good electric insulation such as PP (polypropylene) and having high heat resistance is used. Cover the tubular member 5 from the yoke 3 to the magnet 2 so that the yoke 3 and the magnet 2 are not displaced from each other.
A combination of these is set in a molding die and integrally molded with a synthetic resin such as PBT (polybutylene terephthalate) as shown in FIG.

At this time, the molding die is formed so that the molding die holding portion 6a is formed on the synthetic resin member 6 after molding, whereby the core 1, the magnet 2 and the yoke 3 are formed. Are positioned in the mold. It should be noted that this is the same in the conventional technique.

Next, a predetermined wire is wound around the bobbin provided on the synthetic resin member 6, and the electromagnetic pickup coil 7 is wound.
Is formed, and both ends of the wire are connected to the lead terminals 4a and 4b and soldered. Finally, the electromagnetic pickup coil 7, the lead terminals 4a, 4b, etc. are covered with a synthetic resin mold molding 8 such as an epoxy resin to complete the magnetic rotation sensor 10.

As described above, in both the prior art and the embodiment of the present invention, the core 1 and the magnet 2 are formed on the synthetic resin member 6 at the time of integral molding as shown in FIG. The position is fixed by the mold pressing portion 6a. However, at this time, for structural reasons, these molding die pressing portions 6a are
It must be positioned at an intermediate portion between the molding die pressing portion 6b and the bobbin portion of the synthetic resin member 6 when the synthetic resin mold molding 8 is molded.

Therefore, with respect to the yoke 3, even if the position and shape of the molding die pressing portion 6a are devised, the position cannot be defined by the molding die. And this is the reason why the conventional technique causes a position shift or the like.

In this embodiment, however, as shown in FIG. 2, a tubular member 5 is used, which is covered with the yoke 3 and the magnet 2. Therefore, the yoke 3 has the tubular member 5 And the magnetic force of the magnet 2 causes the resin to be positioned. In this state, the synthetic resin member 6 is set and fixed in the molding die and integrally molded. As a result, the pressure of the molten resin at the time of molding is set. In spite of this, the molding can always be obtained with the accurate position, and the deviation of the yoke 3 and the contact with the lead terminals 4a and 4b due to the molding pressure during the integral molding are surely prevented. be able to.

For this reason, the cylindrical member 5 needs to be prepared with sufficient accuracy in accordance with the outer dimensions of the yoke 3 and the magnet 2 whose dimensions are substantially cylindrical. Since the tubular member 5 is made of a synthetic resin material having a relatively high elasticity, the tubular member 5 is made to have a slightly small size, and the elasticity is utilized to make the yoke 3 move to the magnet 2
Just cover it.

Also, as is apparent from FIG. 1, the tubular member 5 includes a yoke 3, a magnet 2 and a lead terminal 4.
Since it also plays the role of insulating between a and 4b, it is necessary to ensure a sufficient insulation thickness for the sensor output voltage generated between the lead terminals 4a and 4b. As long as a synthetic resin material is used, this degree of insulation can be easily obtained, so there is not much problem.

Further, since the tubular member 5 is integrally molded with the core 1 and the like by molten resin, it goes without saying that sufficient heat resistance must be ensured even at the molding temperature at this time.

Next, FIG. 4 shows another embodiment of the present invention.
In this embodiment, the cylindrical member 5 is used not only for positioning the yoke 3 and the magnet 2, but also for the magnet 2 and the core 1.
It is also used for positioning.

Also in this embodiment, the core 1, the magnet 2, the yoke 3 and the lead terminals 4a and 4b are integrally molded with the synthetic resin member 6 forming the bobbin.
In this embodiment, only the core 1 is positioned and fixed by the molding die pressing portion 6a provided on the synthetic resin member 6 and integrally molded.

However, as described above, the yoke 3 and the magnet 2 cannot be fixed by the molding die pressing portion 6a due to their structure. Therefore, in this embodiment, the tubular member 5 is covered not only from the yoke 3 to the magnet 2 but also onto a part of the core 1, whereby the yoke 3
The magnet 2 is also positioned on the core 1.

As a result, the core 1, the magnet 2 and the yoke 3 are sufficiently fixed by the magnetic force of the tubular member 5 and the magnet 2, and the yoke due to the molding pressure at the time of integral molding. It is possible to reliably prevent the displacement of the magnet 3 and the magnet 2 and the contact with the lead terminals 4a and 4b.

FIG. 5 is a front view showing an embodiment of the tubular member 5, and FIG. 6 is a side sectional view thereof. This tubular member 5
Although, as its name suggests, it may remain simply cylindrical, but in this embodiment it is made as a cap with a bottom, as shown, and thus according to this embodiment, FIG.
As shown in FIG. 3, the insertion position when the yoke 3 is placed over the magnet 2 or even the core 1 is automatically defined, so that there is an effect that the covering work becomes easy.

Further, in this embodiment, since the hole 5a is provided in the bottom portion of the cap, as shown in FIG. 2, air is not released during the work of inserting the yoke 3 etc. The difficult situation is improved and the workability can be improved.

Next, the magnetic rotation sensor 10 according to the present invention.
An example of mounting will be described. First, FIG. 7 shows a mounting example in which the magnetic rotation sensor 10 according to the present invention is applied to an automobile engine 11 and is used as a crank angle sensor or a rotation speed sensor. In FIG. 10a, a signal disk is attached to a cam shaft. The mounting position when the signal disk is mounted on the crankshaft is indicated by 10b.

FIG. 8 shows an example in which the magnetic rotation sensor 10 according to the present invention is mounted on an automobile transmission 12 and used as a rotation speed sensor, and is an example of mounting when the gear 13 is used as a signal disk.

As shown in FIGS. 6 and 7, the magnetic type rotation sensor including the embodiment of the present invention has a projection and a tooth profile formed on the outer peripheral portion of the signal disk provided on the rotating portion of each portion of the automobile. Etc., the output signal is sent to the control unit for control and used for control or the like.

At this time, as described above, recently, there has been a demand for miniaturization of the magnetic type rotation sensor as a part of the automobile system. However, the present invention is implemented in response to such a demand. According to the example, a larger magnet can be used without changing the size of the entire sensor, so that the size can be reduced without sacrificing the output voltage characteristic.

Therefore, according to the above embodiment, in the magnetic type rotation sensor in which the core, the magnet, the yoke and the lead terminal are integrally molded with the synthetic resin member having the bobbin, the mannet and the yoke are structurally arranged. Even if it cannot be fixed with the molding die, it is possible to prevent the displacement of the magnet and the yoke and the contact with the lead terminal due to the molding pressure during the integral molding.

Further, in the above-mentioned embodiment, by providing an air vent hole in the cap, it is possible to improve the situation in which the air is not released when the cap is inserted into a yoke or the like, and the yoke is difficult to insert. It is possible to improve the sex.

[0037]

According to the present invention, the following effects can be obtained. In a magnetic rotation sensor in which a core, a magnet, a yoke and a lead terminal are integrally molded with a synthetic resin body having a bobbin, it is possible that the magnet and the yoke cannot be fixed by a molding die because of the structure. Also, it is possible to prevent the displacement of the magnet and the yoke and the contact with the lead terminal due to the molding pressure at the time of integral molding. Further, since the cap can be provided with an air vent hole, it is possible to improve the workability by improving the situation that air is not released and it is difficult to insert the yoke when inserting the yoke into the cap. .

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a cross section of an essential part showing an embodiment of a magnetic rotation sensor according to the present invention.

FIG. 2 is an explanatory diagram showing a usage state of a tubular member according to an embodiment of the present invention.

FIG. 3 is an explanatory view showing a state after molding with a mold according to an embodiment of the present invention.

FIG. 4 is an overall configuration diagram showing a cross section of a main part of another embodiment of the magnetic rotation sensor according to the present invention.

FIG. 5 is a front view showing details of an embodiment of a tubular member according to the present invention.

FIG. 6 is a side sectional view showing details of an embodiment of a tubular member according to the present invention.

FIG. 7 is an explanatory view showing an example of mounting the magnetic rotation sensor according to the present invention on an automobile engine.

FIG. 8 is an explanatory view showing an example of mounting the magnetic rotation sensor according to the present invention on an automobile transmission.

[Explanation of symbols]

 1 Core 2 Magnet 3 Yoke 4a, 4b Lead Terminal 5 Cylindrical Member 6 Synthetic Resin Member 6a, 6b Mold Holding Section 7 Coil 8 Synthetic Resin Mold Molded Body 10 Magnetic Rotation Sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Kikuchi 2520 Takaba, Katsuta-shi, Ibaraki Hitachi, Ltd. Automotive Equipment Division (72) Inventor Kazuhiko Kawakami 2520, Takata, Katsuta-shi, Ibaraki Hitachi, Ltd. Factory Automotive Equipment Division

Claims (2)

[Claims] 1. A magnetic circuit element and a lead terminal in which a substantially cylindrical permanent magnet and a yoke are sequentially attached to an end portion on the opposite side to the end portion on the detection side of a core, and a lead terminal are integrally formed by a synthetic resin member forming a bobbin. In a molded magnetic rotation sensor, a cylindrical member made of an insulating and heat-resistant material that covers at least a part of the outer peripheral surface of the magnet from the end of the yoke opposite to the end on the magnet side is formed. A magnetic rotation sensor, wherein the magnetic rotation sensor is provided so as to prevent displacement of the yoke and the magnet during integral molding with the synthetic resin body. 2. The magnetic rotation sensor according to claim 1, wherein the tubular member is made of a cap having a bottom, and an opening is formed in the bottom.