JPH0714899Y2 - Electromagnetic rotation sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an electromagnetic rotation sensor suitable for use in, for example, a crank angle sensor, and more particularly to an electromagnetic rotation sensor that can be formed compactly.

[Conventional technology]

FIG. 2 shows a crank angle sensor as an example of a conventional electromagnetic rotation sensor.

In the drawings, reference numeral 1 denotes a rotary plate as a rotary member formed of a magnetic material in the shape of a toothed disc.
For example, it is fixed to the crankshaft 2 of the engine or the like, and is rotated together with the crankshaft 2 in the arrow A direction.
A plurality of tooth portions 1A, 1A, ... Are radially provided on the outer peripheral side of the rotary plate 1, and the tooth portions 1A are arranged at predetermined intervals in the circumferential direction of the rotary plate 1.

Reference numeral 3 denotes an electromagnetic crank angle sensor, 4 denotes a casing of the sensor 3, the casing 4 is formed of a resin material or the like into a substantially L shape, and has a bottomed cylindrical casing body 4A.
And a bracket portion 4B protruding in the radial direction from the bottom side of the casing body 4A. A mounting hole 4C is formed in the bracket portion 4B, and a cylindrical fixing ring 5 is fitted in the mounting hole 4C. The bracket portion 4B is provided with a bolt 7 on a frame 6 of the engine so that a tip end side of a core member 10 described later may be brought close to the rotary plate 1.
It is fixed by a nut 8 via a fixing ring 5.

Reference numeral 9 denotes a permanent magnet formed in a short cylindrical shape, 10 denotes a core member abutting on one axial side surface of the permanent magnet 9, and the core member 10 is made of a magnetic material such as iron or ferrite. It is composed of a disc-shaped large-diameter portion 10A and a small-diameter portion 10B axially extending from the large-diameter portion 10A. Here, the large diameter portion 10A of the core member 10 is the permanent magnet 9 and the magnetic member 1 described later.
Together with 1, they are arranged in the casing body 4A of the casing 4 by means such as integral molding. And the core member
The tip of the small-diameter portion 10B of 10 is arranged close to the outer peripheral side of the rotary plate 1 by the casing 4.

Reference numeral 11 denotes a magnetic member that abuts on the other side surface in the axial direction of the permanent magnet 9 and is provided inside the casing body 4A. The magnetic member 11 is formed of a magnetic material such as electromagnetic soft iron into a columnar shape, and is provided inside the casing body 4A. Has a relatively long dimension and extends axially. By forming the magnetic member 11 with a predetermined volume, the magnetic flux density of the permanent magnet 9 is increased, and a relatively strong magnetic force is generated in the core member 10 together with the permanent magnet 9.

Reference numeral 12 denotes a coil bobbin fitted to the outer peripheral side of the small-diameter portion 10B of the core member 10, 13 denotes a detection coil wound around the coil bobbin 12, and the detection coil 13 is used when the rotary plate 1 rotates in the arrow A direction. Since the magnetic flux of the core member 10 changes due to the reason described below, an induced electromotive force is generated by the electromagnetic induction action, and the rotation of the rotary plate 1 is detected by this induced electromotive force. Further, 14 denotes a lead wire for leading a detection signal from the detection coil 13 to the outside, one end side of the lead wire 14 is extended in the casing body 4A and connected to the detection coil 13, and the other end side is a control unit. It is adapted to be connected to an input end (not shown).

In the prior art configured as described above, when the rotary plate 1 rotates in the direction of arrow A together with the crankshaft 2 when the engine is started, each tooth portion 1A of the rotary plate 1 made of a magnetic material causes the small diameter portion 10B of the core member 10 to rotate. Since the magnetic field of the core member 10 is changed in response to the approach and separation of the tip, the induced electromotive force is generated in the detection coil 13 by the electromagnetic induction action.
The induced electromotive force increases / decreases each time the tooth portions 1A of the rotating plate 1 approach and separate from each other, so that the induced electromotive force is controlled via the lead wire 14 as a rotation signal corresponding to the angle between the tooth portions 1A. Output to the unit, the rotation angle of the crankshaft 2,
That is, it is used as a crank angle detection signal to detect the engine speed.

[Problems to be solved by the device]

By the way, in the above-mentioned conventional technique, since the magnetic flux density of the permanent magnet 9 is increased and a relatively strong magnetic force is generated in the core member 10, the magnetic member 11 having a predetermined volume is provided on the other side surface in the axial direction of the permanent magnet 9. The magnetic members 11 are made to abut against each other so that the magnetic member 11 is elongated in the axial direction in the casing body 4A.

Therefore, the conventional technique has a drawback in that the axial dimension of the casing body 4A becomes long and the crank angle sensor 3 as a whole cannot be formed compactly. Further, since the bracket portion 4B of the casing 4 is made of a resin material,
The rigidity of the bracket portion 4B cannot be increased, and when the bracket portion 4B is attached to the engine frame 6 or the like through the bolts 7 and the nuts 8, the bracket portion 4B is easily damaged by vibration of the engine or the like. There is a drawback that.

The present invention has been made in view of the above-mentioned drawbacks of the prior art.The present invention can prevent the axial dimension from becoming long, can form a compact body, and can damage the bracket portion due to engine vibration or the like. It is intended to provide an electromagnetic rotation sensor capable of preventing the occurrence of abrasion.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, an electromagnetic rotation sensor according to the present invention is provided with a casing, a permanent magnet provided in the casing, and one side surface in the axial direction of the permanent magnet, and a tip portion thereof is close to a rotating member. And a magnetic member provided in the casing located on the other side surface in the axial direction of the permanent magnet for sagging to increase the magnetic flux density of the permanent magnet, and wound around the core member. And a detection coil for detecting the rotation of the rotating member.

And, the feature of the configuration adopted by the present invention is that the magnetic member is composed of one rod-shaped body having a predetermined length dimension and arranged in the radial direction of the permanent magnet, and one end side of the magnetic member is a permanent magnet. This is because the other end side is made to abut on the other side surface in the axial direction, the other end side is projected in the radial direction of the permanent magnet, and the mounting portion is provided on the other end side of the magnetic member.

[Action]

By disposing one magnetic member made of a rod-shaped body in the radial direction of the permanent magnet with a predetermined length dimension, the axial dimension of the rotation sensor can be shortened and the volume of the magnetic member can be used in the conventional technique. The magnetic flux density of the permanent magnet can be increased in the same manner as the above, and the other end of the magnetic member made of a magnetic material such as iron integrally provided with the permanent magnet and the core member in the casing. By using the side as the mounting portion, the rigidity of the mounting portion can be increased.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the embodiment, the same components as those of the prior art shown in FIG. 2 described above are designated by the same reference numerals and the description thereof will be omitted.

In the figure, 21 is the crank angle sensor of this embodiment, and 22 is the sensor.
21 shows a casing, which is made of a resin material like the casing 4 described in the prior art, but has a casing body 22A formed in a short bottomed tubular shape, and a shaft of the casing body 22A. And a bracket portion 22B that is provided so as to project from the intermediate portion in the radial direction in the radial direction. Here, the bracket portion 22B is formed to be hollow, and a magnetic member 25, which will be described later, is disposed inside the bracket portion 22B as a core metal.

Reference numeral 23 indicates a permanent magnet, and 24 indicates a core member composed of a large diameter portion 24A and a small diameter portion 24B. The core member 24 and the permanent magnet 23 are formed in the same manner as described in the prior art and have the same function. It has become. Reference numeral 25 denotes a magnetic member whose one end side is disposed in the casing main body 22A and abuts on the other side surface in the axial direction of the permanent magnet 23. The magnetic member 25 is a plate having a predetermined length dimension made of a magnetic material such as electromagnetic soft iron. As a single rod-shaped body, for example, it is formed into an elliptical plate shape, and the plate thickness is 3
It is about 5 mm. The other end of the magnetic member 25 projects in the radial direction of the permanent magnet 23, and the projecting end has a mounting hole 25A as a mounting portion through which the bolt 7 and the like are inserted.

Here, the magnetic member 25 is disposed in the casing 22 as shown in the figure by means such as integral molding together with the permanent magnet 23 and the large diameter portion 24A of the core member 24, and the magnetic member is provided in the bracket portion 22B of the casing 22. The protruding end side of 25 is arranged as a core metal. The magnetic member 25 is the magnetic member described in the prior art.
By having the same volume as 11, the magnetic flux density of the permanent magnet 23 is increased and a relatively strong magnetic force is generated in the core member 24. Further, the protruding end side of the magnetic member 25 together with the bracket portion 22B is attached to the frame 6 through the mounting hole 25A.
It is inserted through the bolt 7 and is fastened to the frame 6 by the nut 8. The mounting hole 25A may be covered with a part of the bracket portion 22B as shown in the drawing when the casing 22 is molded.

Reference numeral 26 denotes a coil bobbin, and 27 denotes a detection coil. The detection coil 27 and the coil bobbin 26 are formed in the same manner as described in the prior art and have the same action.
The detection coil 27 is connected to a lead wire 28, and outputs a detection signal to a control unit (not shown) or the like via the lead wire 28.

The crank angle sensor 21 as the electromagnetic rotation sensor according to the present embodiment has the above-mentioned configuration, and its basic operation is not different from that of the prior art.

Therefore, in the present embodiment, the magnetic member 25 is arranged so as to extend in the radial direction with respect to the permanent magnet 23, one end side of the magnetic member 25 is abutted against the other axial side surface of the permanent magnet 23, and the other end side is arranged. Since it is configured to project in the radial direction, a predetermined volume can be secured in the magnetic member 25, the magnetic flux density of the permanent magnet 23 can be increased, and the detection performance of the detection coil 27 can be stabilized, and The axial dimension of the casing body 22A can be shortened, and the crank angle sensor 21 as a whole can be surely made compact and compact.

Further, a mounting hole 25A is formed on the protruding end side of the magnetic member 25,
Since the magnetic member 25 is used as a cored bar of the bracket portion 22B, the rigidity of the bracket portion 22B can be significantly increased, and the bracket portion 22B is provided together with the protruding end side of the magnetic member 25 through the mounting hole 25A or the like. When mounted on the frame 6 or the like of the engine, it is possible to prevent the bracket portion 22B or the like from being damaged by vibration of the engine or the like, and the crank angle sensor 21 can be reliably supported and fixed to the frame 6 or the like. .

Although the crank angle sensor 21 has been described as an example in the above-described embodiment, the electromagnetic rotation sensor according to the present invention is not limited to the crank angle sensor 21, and the rotation angle, rotation speed, rotation speed, etc. of various rotating members can be determined. It can also be used as a rotation sensor for detecting.

[Effect of device]

As described in detail above, according to the present invention, the magnetic member provided on the other side surface in the axial direction of the permanent magnet is projected in the radial direction of the permanent magnet with a predetermined length dimension to secure a predetermined volume. Since it is formed from one rod-shaped body and its protruding end side is used as the mounting portion, the axial dimension of the rotation sensor can be shortened, and the entire body can be made compact, and as a cored bar in the casing. The rigidity of the mounting part etc. can be surely increased by the integrated magnetic member, the rotation sensor can be firmly fixed and supported, and the mounting part side will be damaged by vibration etc. It can be surely prevented.

[Brief description of drawings]

1 is a vertical sectional view showing a mounted state of a crank angle sensor according to an embodiment of the present invention, and FIG. 2 is a vertical sectional view similar to FIG. 1 showing a conventional crank angle sensor. 1 ... Rotating plate (rotating member), 1A ... Tooth, 6 ... Frame, 21 ... Crank angle sensor, 22 ... Casing, 23 ...
… Permanent magnet, 24 …… Core member, 25 …… Magnetic member, 25A…
… Mounting hole (mounting part), 26 …… Coil bobbin, 27 …… Detection coil.

Claims (1)

[Scope of utility model registration request] 1. A casing, a permanent magnet provided in the casing, and one side surface in the axial direction of the permanent magnet,
A core member whose tip side is disposed in the vicinity of the rotating member, and a magnetic member provided in the casing located on the other axial side surface of the permanent magnet to increase the magnetic flux density of the permanent magnet, In an electromagnetic rotation sensor that is wound around the core member and includes a detection coil that detects the rotation of the rotating member, the magnetic member has a predetermined length and is arranged in a radial direction of the permanent magnet. A rod-shaped body, one end side of the magnetic member is abutted against the other axial side surface of the permanent magnet, and the other end side is projected in the radial direction of the permanent magnet,
An electromagnetic rotation sensor characterized in that a mounting portion is provided on the other end side of the magnetic member.