JP3407221B2 - Rotation sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation sensor for detecting a rotation speed of a rotating body part.

[0002]

2. Description of the Related Art Conventionally, as a rotation sensor for detecting the rotation speed (rotation speed) of a rotating body portion, there has been disclosed in Japanese Utility Model Laid-Open No. 61-14091.
The rotation detector disclosed in Japanese Patent No. 2 is known.

In the rotation detector disclosed in the above publication, a bobbin having a coil wound around a magnetic body through which magnetic flux flows is mounted, and the rear end of this magnetic body (iron core) is brought into contact with a permanent magnet. The permanent magnet and the magnetic body are housed in a cylindrical casing, and the transmission changes from the voltage induced in the coil based on the unevenness of the transmission gear (rotating body portion) passing in front of the magnetic body. The rotation speed of the gear can be detected.

[0004]

However, the conventional rotation sensor including the rotation detector disclosed in the above publication generally has the following problems to be solved.

First, because of the large magnetic resistance due to the geometrical configuration, high detection sensitivity cannot be obtained, and eventually detection accuracy, stability and reliability deteriorate.

Secondly, due to the complicated structure, the assemblability and the productivity are lowered, and the cost and the size of the entire sensor are increased.

The present invention solves the problems existing in such conventional techniques. The detection sensitivity, as well as the detection accuracy, stability and reliability can be improved, and the simplification of the configuration provides An object of the present invention is to provide a rotation sensor capable of improving the assembling property and the productivity and further reducing the cost and the size.

[0008]

MEANS FOR SOLVING THE PROBLEMS AND THE PREFERRED EMBODIMENTS The present invention is directed to a gear-shaped rotating body portion R formed of a magnetic material having irregularities on a peripheral portion Rr, and a sensor main body portion arranged close to the rotating body portion R. When constructing the rotation sensor 1 including the pole piece 3, a pole piece 3 integrally formed with a cylindrical portion 3r formed of a magnetic material and an end surface portion 3s closing one end of the cylindrical portion 3r.
And the outer diameter is smaller than the inner diameter of the pole piece 3,
A cylindrical magnet 4 arranged coaxially inside the pole piece 3 and having one end 4r in contact with the inner surface of the end face portion 3s, and a detection coil 5 for detecting a change in magnetic flux generated by the magnet 4 are provided. It is characterized by including the sensor main body portion 2 having the sensor main body portion 2.

In this case, according to the preferred embodiment, it is desirable to interpose a cylindrical non-magnetic member 11 between the pole piece 3 and the magnet 4. On the other hand, the coil bobbin 12 mounted on the outer peripheral surface of the cylindrical portion 3r can be provided, and the detection coil 5 can be wound around the coil bobbin 12. The coil bobbin 12 is provided with a plurality of small convex portions 12p ... on the inner peripheral surface facing the outer peripheral surface of the cylindrical portion 3r, and the wire ends 5x and 5y of the detection coil 5 and the lead wire 13 are provided.
The terminal mounting portion 15 having the lead terminals 14x and 14y for connecting x and 13y can be integrally formed. Also,
The sensor main body 2 integrally has an external mounting portion 16c,
In addition, it is desirable to provide the overmolded portion 16 that covers the entire sensor body 2.

With this structure, the other end 4f of the magnet 4 and the other end of the cylindrical portion 3r are opposed to the concavities and convexities provided on the gear-shaped rotor portion R formed of a magnetic material. At this time, the other end 4f of the magnet 4 and one of the other ends of the cylindrical portion 3r become the N pole (S pole) and the other becomes the S pole (N pole), and the other end 4f of the magnet 4 and the cylindrical portion 3r are Since a magnetic circuit having no air gap is formed between the ends, the magnetic resistance becomes extremely small, the detection sensitivity is enhanced, and the structure is simplified.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the parts used in the rotation sensor 1 according to this embodiment will be described with reference to FIGS.

As shown in FIG. 1, the rotation sensor 1 is composed of a gear-shaped rotating body portion R and a sensor body portion 2 which is arranged so as to face and be close to a peripheral portion Rr of the rotating body portion R. The rotating body portion R is formed of a magnetic material, and has peripheral portions Rr having recessed portions Rra ... And protruding portions Rrb formed alternately. It should be noted that the rotating body portion R is attached to the rotating shaft portion Rx provided in the detection target.

On the other hand, in the sensor main body 2, 12 is a coil bobbin integrally formed of synthetic resin, and as shown in FIG. 4, a cylindrical bobbin main body 12m and one provided on one end of the bobbin main body 12m. Barrier part 12b
And a cylindrical terminal mounting portion 15 which also serves as the other barrier portion provided at the other end of the bobbin main body portion 12m. in this case,
The terminal mounting portion 15 has two lead terminals 14x and 14y integrally provided by insert molding. Each of the lead terminals 14x, 14y is formed in an L shape, one end of which protrudes from the end surface of the terminal mounting portion 15, and the other end of which extends from the inside of the accommodating recesses 21, 22 provided on the peripheral surface of the terminal mounting portion 15 to the peripheral surface. Let it protrude outward.

Reference numeral 3 is a pole piece integrally formed of a magnetic material. The pole piece 3 is formed in a bag shape by the cylindrical portion 3r and the end surface portion 3s that closes one end of the cylindrical portion 3r. Reference numeral 4 denotes a cylindrical magnet. The magnet 4 has an outer diameter smaller than the inner diameter of the pole piece 3, is coaxially arranged inside the pole piece 3, and when the one end 4r is brought into contact with the inner surface of the end surface portion 3s, The end 4f is the other end 3 of the cylindrical portion 3r of the pole piece 3.
It is formed so that the axial position thereof coincides with rf.
The magnet 4 has one end 4r having one pole (for example,
The south pole) and the other end 4f become the other pole (for example, N pole).
Reference numeral 11 is a non-magnetic member formed of aluminum, brass or the like in a cylindrical shape, and is formed in a shape that can be interposed between the pole piece 3 (cylindrical portion 3r) and the magnet 4.

Next, a method of manufacturing the rotation sensor 1 (sensor main body 2) according to this embodiment will be described with reference to FIGS.

First, the detection coil 5 is wound around the coil bobbin 12, and the wire ends 5x and 5y led out from the detection coil 5 are connected to the lead terminals 14x and 14y protruding from the peripheral surface of the terminal mounting portion 15 (FIG. 4). Then, the lead terminal 14x to which the wire end 5x (the same on the 5y side) is connected is housed in the housing recess 21 by being bent at a substantially right angle, as shown by an imaginary line in FIG.

On the other hand, the non-magnetic member 11 is accommodated (inserted) inside the pole piece 3, and the magnet 4 is further accommodated (inserted) inside the non-magnetic member 11.
This state is shown in FIG. As a result, the magnet 4
The magnet 4 is coaxially arranged inside the pole piece 3, and one end 4r of the magnet 4 contacts the inner surface of the end surface portion 3s.

Then, the obtained pole piece 3 is inserted into the bobbin main body 12m of the coil bobbin 12. This state is shown in FIG. In this case, the outer peripheral surface of the cylindrical portion 3r of the pole piece 3 and the inner peripheral surface of the coil body 12m do not necessarily have to be in close contact with each other. Therefore, as shown in FIG. 6, on the inner peripheral surface of the bobbin main body portion 12m facing the outer peripheral surface of the cylindrical portion 3r, a plurality of small convex portions 12p ...
If the small convex portions 12p ... Are pressed by their own elasticity toward the outer peripheral surface of the cylindrical portion 3r toward the center, the adhesion to the pole piece 3 can be further enhanced and mechanical backlash can be prevented. You can In addition, in FIG.
The same parts as those in FIG. 5 are designated by the same reference numerals to clarify the configuration. On the other hand, lead wires 13x and 13y are connected to the lead terminals 14x and 14y protruding from the end surface of the terminal mounting portion 15, respectively.

Next, the assembly unit manufactured through the above steps is secondarily molded. That is, by covering the entire assembly unit with synthetic resin, the overmolded portion 16
To provide. As a result, the whole becomes cylindrical. At this time, the external mounting portion 16c shown in FIG. 2 is integrally formed with the overmolded portion 16. The rotation sensor 1 can be attached to a target portion by the external attachment portion 16c and can be positioned with respect to the rotating body portion R.
Therefore, the sensor body 2 shown in FIG. 1 can be obtained.

According to the rotation sensor 1 of this embodiment, as shown in FIG. 7, the other end 4f of the magnet 4 is used.
The magnetic flux F output from the (N pole) is input to the gear-shaped rotating body portion R formed of a magnetic material, passes through the inside of the rotating body portion R, and then is output from the rotating body portion R, and the cylindrical portion 3r
To the other end 3rf (S pole). Accordingly, when the rotating body portion R rotates, the concave portions Rra ... And the convex portions Rrb provided on the peripheral portion Rr alternately approach the tip end surface of the sensor body portion 2, so that the rotating body portion R can be rotated. Then the magnetic flux changes. Since the change in the magnetic flux is detected as the voltage induced in the detection coil 5, the rotation speed (rotation speed) of the rotating body part R can be detected based on the change in the voltage.

Further, with such a structure, a magnetic circuit having no air gap is formed between the other end 4f of the magnet 4 and the other end 3rf of the cylindrical portion 3r, so that the magnetic resistance becomes extremely small and the detection sensitivity, Furthermore, detection accuracy, stability and reliability are improved. Moreover, due to the simplification of the configuration,
Assembling and productivity are improved, and further cost reduction and size reduction are achieved. In addition, since the pole piece 3 and the magnet 4 are arranged concentrically, there is no phase restriction (directivity) in the circumferential direction, and the sensor body 2 is rotationally displaced in the circumferential direction.
That is, even if the position shift occurs, the voltage drop or the detection waveform disturbance induced in the detection coil 5 does not occur. Therefore, it is suitable for use in, for example, a vehicle speed sensor provided in an ABS (anti-lock braking system) of an automobile.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The detailed configuration, shape, material, quantity, etc. can be arbitrarily changed, added, or deleted without departing from the scope of the present invention. For example, although the case where the cylindrical non-magnetic member 11 is interposed between the pole piece 3 and the magnet 4 is illustrated, resin or the like may be filled. Also, the terminal mounting portion 15
And the overmold part 16 can be implemented arbitrarily.

[0024]

As described above, in the rotation sensor according to the present invention, the pole portion integrally formed with the cylindrical portion formed of the magnetic material and the end surface portion closing one end of the cylindrical portion, and the outer diameter is the inner diameter of the pole piece. A cylindrical magnet whose diameter is smaller than that of the pole piece and is coaxially arranged inside the pole piece, and one end of which is in contact with the inner surface of the end face portion, and a detection coil which detects a change in magnetic flux generated by this magnet. Since the sensor main body having the above is provided, the following remarkable effects are exhibited.

(1) Since the other end of the magnet and the other end of the cylindrical portion of the pole piece can be constituted by a magnetic circuit having no air gap, the magnetic resistance becomes extremely small, and the detection sensitivity, and further the detection accuracy and stability. And reliability can be improved.

(2) By simplifying the structure, the assemblability and the productivity can be improved, and the cost and the size can be reduced.

(3) According to a preferred embodiment, the coil bobbin is mounted on the cylindrical portion of the pole piece, and
If a plurality of small convex portions are provided on the inner peripheral surface of the cylindrical portion facing the outer peripheral surface, the elasticity of the cylindrical portion presses the outer peripheral surface of the cylindrical portion toward the center, and the adhesion can be further improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a rotation sensor according to a preferred embodiment of the present invention,

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a perspective view showing a state in which a magnet and a non-magnetic member are assembled to a pole piece of the rotation sensor.

FIG. 4 is a longitudinal sectional view showing a state before molding an overmolded portion of the rotation sensor,

5 is a sectional view taken along line BB in FIG. 4,

FIG. 6 is a sectional view taken along the line AA in FIG. 1, showing a part of a rotation sensor according to a modified example of the invention.

FIG. 7 is a principle explanatory view of a rotation sensor according to a preferred embodiment of the present invention,

[Explanation of symbols]

1 rotation sensor 2 Sensor body 3r Cylinder of pole piece 3s end piece of pole piece 3 pole pieces 4 magnets 4r One end of magnet 5 detection coil 5x ... Wire end 11 Non-magnetic material 12 coil bobbins 12p ... Small convex part 13x ... Leader 14x ... Lead terminal 15 Terminal mounting part 16 Overmolded part 16c External mounting part R rotor part Rr Perimeter of rotating body

Continuation of front page (56) Reference JP-A-7-1113812 (JP, A) JP-A-11-23602 (JP, A) JP-A-11-264837 (JP, A) JP-A-7-140157 (JP , A) JP-A-8-166398 (JP, A) JP-A-8-101226 (JP, A) JP-A-8-105908 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) G01P 3/488 G01D 5/245 G01B 7/00

Claims (6)

(57) [Claims] 1. A rotation sensor including a gear-shaped rotating body portion formed of a magnetic material having an unevenness on a peripheral portion thereof, and a sensor main body portion arranged close to the rotating body portion. A pole piece integrally formed with an end surface portion that closes one end of the cylindrical portion, and an outer diameter formed to be smaller than an inner diameter of the pole piece, and arranged coaxially inside the pole piece, and one end of the end surface portion. A rotation sensor, comprising: a sensor main body having a cylindrical magnet that is in contact with the inner surface of the sensor and a detection coil that detects a change in magnetic flux generated by the magnet. 2. The rotation sensor according to claim 1, wherein a cylindrical non-magnetic member is interposed between the pole piece and the magnet. 3. The rotation sensor according to claim 1, further comprising a coil bobbin mounted on an outer peripheral surface of the cylindrical portion, wherein the detection coil is wound around the coil bobbin. 4. The rotation sensor according to claim 3, wherein the coil bobbin has a plurality of small convex portions on an inner peripheral surface facing the outer peripheral surface of the cylindrical portion. 5. The rotation sensor according to claim 3, wherein the coil bobbin is integrally formed with a terminal mounting portion having a lead terminal for connecting a wire end of the detection coil and a lead wire. 6. The rotation sensor according to claim 1, wherein the sensor main body portion integrally has an external mounting portion and an overmolded portion that covers the entire sensor main body portion.