JP2588983Y2 - 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, and more particularly to a rotation sensor for detecting the rotation speed of a toothed wheel by magnetically detecting the rotation of the toothed wheel. And a method that is effective for detecting the number of rotations of wheels.

[0002]

2. Description of the Related Art Some vehicles such as automobiles employ an anti-lock brake system as a system for ensuring the stability and controllability of the vehicle. In this system, a method is adopted in which the rotation speed of a wheel is detected by a rotation sensor, and whether or not the wheel is locked is determined based on the rotation speed.

A conventional rotation sensor of this type includes a toothed wheel that rotates in conjunction with a wheel, and a main body that is disposed with a fixed gap between the toothed wheel. A pole piece housed at the tip of the case and magnetically opposed via the toothed wheel and the case, and a coil wound around the outer periphery of the pole piece via a coil bobbin are provided,
It is known that a coil is configured to generate an electric signal in accordance with a change in magnetic flux of a pole piece with rotation of a toothed wheel.

[0004]

In the above-mentioned conventional rotation sensor, a thin wire having a diameter of 0.1 mm or less is used as a coil wire in order to increase the detection sensitivity.
For this reason, if an excessive impact is applied to the rotation sensor body from the outside, or if a tool or the like accidentally collides with the rotation sensor due to wheel replacement or the like, the case that protects the inside of the rotation sensor body is dented, and the coil bobbin is There is a risk that the shock will be applied and the coil wound around the coil bobbin will be damaged or disconnected.

An object of the present invention is to provide a rotation sensor capable of suppressing the application of an impact force to a coil bobbin and preventing the coil from being damaged or disconnected.

[0006]

SUMMARY OF THE INVENTION A rotation sensor according to the present invention has a toothed wheel in which teeth formed of a magnetic material are arranged in a circular ring and rotated, and a fixed gap is maintained between the toothed wheel. A body having a cylindrical shape, a shaft-shaped pole piece housed in the tip of the case and magnetically opposed to the toothed wheel via the case, and a pole. A coil wound around the outside of the piece via a coil bobbin to generate an electric signal in response to a change in magnetic flux of the pole piece, wherein the coil bobbin has a space formed between the coil bobbin and the inner surface of the tip of the case. Protector ring formed to be housed in the space between the case tip and the coil bobbin is mounted on the outer periphery of the pole piece. Ri, wherein the detent portion for preventing movement of the coil bobbin side of the protector ring on the tip portion of the casing is formed.

[0007]

According to the above-mentioned means, the coil bobbin is arranged leaving a space between the coil bobbin and the case, and the protector ring is mounted between the coil bobbin and the tip of the case. When this occurs, the impact force acts on the case or the protector via the case. Therefore, the impact force applied to the case can be absorbed by the deformation of the case and the protector ring. By this absorption, it is possible to suppress an impact force from being applied to the coil bobbin, so that even if an impact force is applied to the case, the coil can be prevented from being damaged or disconnected.

[0008]

FIG. 1 is a side sectional view showing an assembled state of a rotation sensor to a wheel according to an embodiment of the present invention. FIG.
(A), (b) is each partial cutaway side view which shows the rotation sensor main body which is another Example of this invention.

In the present embodiment, the rotation sensor according to the present invention is configured to detect the number of rotations of wheels in an anti-lock brake system of an automobile. The rotation sensor 10 includes a toothed wheel 11 and a rotation sensor body 13.

[0010] The toothed wheel 11 is formed in a circular ring shape using a magnetic material such as iron. On one end surface, a tooth row 12 composed of a large number of irregularities is arranged in a circular ring with a minute pitch. It is formed. The toothed wheel 11 is disposed concentrically with the wheel 1 and is attached so as to rotate integrally.

On the other hand, the rotation sensor main body 13 is supported by the sensor bracket 2 and arranged near the wheel 1. The rotation sensor main body 13 includes a cylindrical case 14 made of a non-magnetic material such as stainless steel. The outer peripheral side of the case 14 is fitted into and supported by the mounting hole 3 of the sensor bracket 2 via the clamping bush 4. I have.

The clamping bush 4 is made of a thin plate having elasticity such as phosphor bronze and is formed in a substantially cylindrical shape, and the sensor bracket 2 has its own elasticity.
Is press-fitted into the mounting hole 3. Clamping bush 4
A plurality of pressing portions 5 having an arc-shaped cross section are arranged in the cylindrical wall at equal intervals in the circumferential direction and in two rows in the axial direction, and are bulged inward in the radial direction. Then, when the pressing portion 5 is pressed against the outer periphery of the case 14, the case 14 is fixed to the mounting hole 3 of the sensor bracket 2 via the clamping bush 4.

On the other hand, the distal end side of the case 14 is arranged with a certain gap from the tooth row 12 of the toothed wheel 11. A connection portion 15 containing a lead wire or the like is attached to the base end of the case 14, and the rotation sensor body 13 is connected to the controller (not shown) of the antilock brake system via the connection portion 15. ) Is electrically connected.

A magnet case 16 and a coil bobbin 18 are housed integrally in the case 14, a magnet 17 is housed in the magnet case 16, and a pole piece 19 is housed in the coil bobbin 18. The magnet 17 and the pole piece 19 are magnetically coupled with each other.
Is in contact with the inner surface of the tip.

A coil 20 is wound around the pole piece 19 via a coil bobbin 18. The coil bobbin 18 and the magnet case 16 are housed in the case 14 with an appropriate gap left therebetween.

A space is formed between the coil bobbin 18 and the inner surface of the distal end of the case 14, and a protector ring 21 formed to be accommodated in the space is interposed in the space. . This protector ring 21
Is fitted on the outer periphery of the pole piece 19. The protector ring 21 has a small-diameter portion 22 and a large-diameter portion 23, and the large-diameter portion 23 is formed so as to abut on the inner peripheral surface of the cylindrical wall near the distal end surface of the case 14. By forming the small-diameter portion 22 at the tip of the protector ring 21, a cavity 24 is formed between the small-diameter portion 22 and the large-diameter portion 23.

At the position facing the rear end of the protector ring 21 on the cylindrical wall of the case 14, a protector ring 2 is provided.
The convex part 25 as a detent part for preventing the 1 from moving backward is formed by appropriate means such as crimping.
The protrusion 25 has a circular ring shape and projects inward in the radial direction. The front end of the protrusion 25 is in contact with the rear end of the large diameter portion 23 of the protector ring 21 over the entire circumference.

Next, a signal generating operation of the rotation sensor 10 according to the above configuration will be described. When the toothed wheel 11 having the teeth 12 arranged along the wheel 1 rotates integrally with the wheel 1, the magnetic air gap between the tip of the pole piece 19 and the toothed wheel 11 in the rotation sensor body 13 changes. . That is, the magnetic flux of the pole piece 19 is changed between a state in which the peak of the tooth row 12 of the toothed wheel 11 faces the tip of the pole piece 19 and a state in which the valley of the tooth row 12 of the toothed wheel 11 faces the pole piece 19. Changes.

When the magnetic flux of the pole piece 19 changes, an electromotive force is generated in the coil 20 according to the change of the magnetic flux, and an electric signal corresponding to the rotation of the wheel 1 is output from the coil terminal of the coil 20. The number of rotations of the wheel 1 (including rotation within 360 degrees) is determined from the number of the electric signals.

Next, the operation when an impact force is applied to the rotation sensor body 13 will be described.

For example, when the rotation sensor body 13 is assembled to the sensor bracket 2, an impact force is applied to the tip of the case 14, or when the rotation sensor body 13 is fixed to the sensor bracket 2, a tool or the like is used. When an impact force is applied to the tip of the case 14 due to an accidental collision, the case force is dented and the coil bobbin 18 receives an impact. The impact on the coil bobbin 18 causes the coil 20 wound around the coil bobbin 18 to be wound.
May be damaged or disconnected.

However, in this embodiment, since the protector ring 21 is interposed between the coil bobbin 18 and the case 14, an impact force acts on the case 14 or the protector ring 21. And, since the protector ring 21 is in a state of being prevented from moving backward by the convex portion 25 protruding from the case 14,
The force applied to the tip of the case 14 is the protector ring 2
1 again, it moves to the case 14, and the whole of the sensor main body 13 is moved backward. Therefore, Case 1
It is possible to prevent the coil bobbin 18 from being deformed or the coil 20 from being damaged or disconnected due to the impact force applied to 4.

In particular, in this embodiment, the cavity 24 is formed between the case 14 and the distal end of the protector ring 21 by forming the small diameter portion 22 on the distal end side of the protector ring 21. When an impact force is applied to the tip of the case 14, the cylindrical wall of the case 14 is simply dented. Therefore, the impact force is hardly transmitted to the coil bobbin 18.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

In the above embodiment, the case where the convex portion 25 is formed in a circular annular shape as the detent portion has been described.
As shown in FIG. 2A, the protrusions 26 are formed intermittently in the circumferential direction as detent portions, and the plurality of protrusions 26 are formed.
May be configured to prevent the protector ring 21 from moving backward.

As shown in FIG. 2B,
Case 14 in large diameter portion 23 of protector ring 21
The concave portion 27 may be submerged in a circular ring shape at a position corresponding to the convex portion 25, and the protector ring 21 may be more securely fixed by engaging the convex portion 25 and the concave portion 27.

[0027]

[Effects of the Invention] As described above, according to the present invention,
Since a space is formed between the coil bobbin and the case, and a protector ring is interposed in this space, even when an impact force is applied to the case, the sensor body is connected to the case via the case and the protector ring by the impact force. Can be moved backward, and the coil can be prevented from being damaged or disconnected due to the impact force, which can contribute to the improvement of the reliability of the rotation sensor.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an assembled state of a rotation sensor according to an embodiment of the present invention.

FIGS. 2 (a) and 2 (b) are partially cut-away side views showing main parts of a rotation sensor according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wheel, 2 ... Sensor bracket, 3 ... Mounting hole, 4 ... Clamping bush, 5 ... Holding part, 10 ... Rotation sensor, 11 ... Toothed wheel, 12 ... Tooth row, 13 ... Rotation sensor main body, 14 ... Case , 15 ... connection part, 16 ... magnet case, 17 ... magnet, 18 ... coil bobbin, 19 ... pole piece, 20 ... coil, 21 ... protector ring, 22 ... small diameter part, 23 ... large diameter part, 24 ... cavity, 25 ... Detent projection, 26 ... Detent projection, 27 ...
Detent recess.

Claims (2)

(57) [Scope of request for utility model registration] 1. A toothed wheel, in which teeth formed by a magnetic material are arranged and rotated in a circular annular shape, and a main body arranged at a constant gap on the toothed wheel. The main body is wound around a cylindrical case, a shaft-shaped pole piece housed in the tip of the case and magnetically opposed to the toothed wheel via the case, and a coil bobbin on the outside of the pole piece. A coil that generates an electric signal in response to a change in magnetic flux of the pole piece, wherein the coil bobbin is disposed leaving a space between the coil bobbin and the inner surface of the tip of the case, A protector ring formed so as to be housed in the space between the coil bobbin and the coil bobbin is mounted on the outer periphery of the pole piece, and a protector ring is provided at the tip of the case. Rotation sensor, characterized in that the detent portions for blocking movement of the coil bobbin side. 2. The rotation sensor according to claim 1, wherein a small-diameter portion that forms a cavity between the protector ring and a front end of the case is formed on an outer periphery of the protector ring.