JPH0564027U - Rotation sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a rotation sensor of an electromagnetic induction type and a pole piece projecting type rotation sensor in which a projecting pole piece can be inserted from the lower side of a housing and which has an improved output voltage compared to the conventional one. [Structure] The rotation sensor 1 includes a coil 2, a bobbin 3, a magnet 4, a pole piece 5 (pole piece), a ferromagnetic ring 5a,
The lead wire 8 is connected to the detection portion including the yoke 6 and the like via the terminal 7.
And a sensor rotor 11 arranged facing the pole piece, and an electromagnetic induction type sensor main body sealed by a potting agent 10 housed in a housing 9. The pole piece 5 has a structure protruding from the extension space of the cylinder formed by the inner diameter of the bobbin, and the tip has a large diameter so as to approach the sensor rotor. The inner end is press-fitted into the ferromagnetic ring 5a to efficiently converge the magnetic flux and improve the output voltage.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rotation sensor that detects a rotation speed of a wheel of an automobile or the like.

[0002]

[Prior Art]

 There are various types of rotation sensors that detect the rotation speed of the wheels of automobiles, such as the electromagnetic power generation system, the system using a magnetoresistive element or a Hall element, but in any case, the sensor is generally a sensor. It consists of a main body and a gear-shaped sensor rotor, and the rotation of the sensor rotor attached to the rotating shaft causes a change in the magnetic flux density, which is detected by the sensor main body as an electrical signal to detect the rotation speed. FIG. 3 shows an example of the conventional rotation sensor. A magnet 4, a bobbin 3, a coil 2 wound around the bobbin, a magnetic pole piece 5 that conducts a magnetic flux of the magnet 4 and the like are housed in a case 9 of the sensor. In this sensor, the pole piece 5 is inserted from above in the drawing of the bobbin. In the sensor having such a structure, the diameter of the surface of the magnetic pole piece 5 in contact with the magnet 4 is made larger than the diameter in the bobbin to enhance the effect of converging the magnetic flux generated from the magnet and increase the output. There is.

On the other hand, FIG. 4 shows another example of a conventional rotation sensor. Since the sensor rotor 11 to be detected for rotation is far away from the central axis of the sensor, the portion of the pole piece 5 facing the sensor rotor is located inside the bobbin 3. The diameter is made larger than the diameter of the magnetic pole piece so that it can be brought closer to the sensor rotor.

[0004]

[Problems to be solved by the device]

 In the configuration of the other example of the related art described above, the pole piece 5 cannot be inserted from above the bobbin 3 and must be inserted from below. However, if it is inserted from below, the diameter of the surface of the pole piece that contacts the magnet cannot be larger than the inner diameter of the bobbin, and the effect of converging the magnetic flux is small and the output voltage drops.

There is also a problem that the inserted magnetic pole piece is easily removed from the tip of the bobbin.

In the present invention, in consideration of the problem of the rotation sensor having the configuration of the other conventional example described above, the magnetic pole can be inserted from the lower portion of the housing by the electromagnetic induction type and the magnetic pole protruding type rotation sensor. It is an object of the present invention to provide a rotation sensor having a high output voltage and a high reliability by increasing the magnetic flux converging effect by adding a ferromagnetic ring to the inner end of the magnetic pole of the type.

[0007]

[Means for Solving the Problems]

 As a means for solving the above problems, the present invention is a cylinder in which a magnet is housed in a bobbin around which a coil is wound, and a pole piece that abuts this magnet and penetrates the bobbin is provided, and the bobbin inner diameter is formed at the tip side of the pole piece. It consists of an electromagnetic induction type detection part protruding from the extension space of the magnetic pole.The ferromagnetic ring is pressed into the rear end of the pole piece that contacts the magnet, and the ring rear end surface and the pole piece rear end surface form a plane. This is the configuration of the rotation sensor that operates.

In the rotation sensor having the above structure, it is preferable that the ferromagnetic ring has a thickness of 1.5 mm or more.

[0009]

[Action]

 The rotation sensor according to the present invention configured as described above operates in the same manner as the conventional one in detecting the rotation speed. When the sensor rotor rotates, the magnetic flux density changes due to the influence of the tooth profile of the gear, and the detector detects the electrical signal corresponding to the change and sends it to the outside to measure the rotation speed.

In such a rotation sensor, since the tip of the magnetic pole piece is larger than the inner diameter of the bobbin, the pole piece cannot be inserted into the bobbin terminal side rear end portion as in the normal sensor assembly process, and is inserted from the tip end portion. There is a need. With such an assembling method, the diameter of the surface of the magnetic pole contacting the magnet cannot be made larger than the inner diameter of the bobbin.However, in the present invention, the ring-shaped ferromagnetic part is press-fitted into the surface of the magnet. The components have a convergence effect and the output voltage is improved.

A ring-shaped component is press-fitted into the rear end of the magnetic pole piece, and this component prevents the magnetic pole piece from moving in the front end direction, so that the magnetic pole piece can be prevented from coming off from the bobbin.

The thicker the press-fitted ring-shaped part is, the more easily the magnetic flux can pass through it, and the better the focusing ability is. When it is 1.5 mm or more, the ring-shaped part is less likely to collapse when press-fitted, and the magnetic pole piece including the magnet and the ring. Since there are few gaps on the contact surface of the, stable output voltage can be obtained.

[0013]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a rotation sensor of the embodiment.

The rotation sensor 1 is configured such that a lead wire 8 is connected to a detection portion including a coil 2, a bobbin 3, a magnet 4, a magnetic pole piece 5 (pole piece), a ferromagnetic ring 5 a, a yoke 6 and the like via a terminal 7. An electromagnetic sensor body which is housed in a housing 9 and sealed with a potting agent 10, and a gear-shaped sensor rotor which is provided so as to face the pole piece and detects rotation of a rotary shaft. 11 and 11.

The end portion of the pole piece 5 on the sensor rotor side is protruded in order to reduce the air gap between the pole piece 5 and the sensor rotor, as in the other conventional examples described above, and is an extension space of the cylinder formed by the inner diameter of the bobbin. It has a structure that overhangs. Therefore, the pole piece 5 is inserted and assembled from below the housing 9.

By assembling the pole piece 5, the ferromagnetic ring 5a is fitted to the end of the pole piece 5 on the housing side. Therefore, as the magnet 4 above the ferromagnetic ring 5a, a large magnet having a ring diameter larger than that of the pole piece 5 can be used, and the output voltage of the sensor is increased to improve the S / N ratio. You can get the output. In this case, the ferromagnetic ring 5a is press-fitted and attached to the surface of the magnetic pole piece 5 in contact with the magnet, and the magnetic flux from the large magnet can be efficiently converged on the magnetic pole piece.

In the rotation sensor of the embodiment configured as described above, when the sensor rotor 11 rotates due to the rotation of the rotation shaft, the amount of magnetic flux passing through the pole piece 5 changes due to the influence of the tooth profile of the gear, and the coil 2 A change proportional to the rotation speed occurs in the output voltage generated at. A signal is taken out through the lead wire 8 via the terminal 7 by the change of the output voltage, and the rotation speed is detected by calculating the changing frequency of the signal voltage.

FIG. 2 shows the relationship between the thickness of the ferromagnetic ring 5a and the output voltage of the rotation sensor. From this figure, it is desirable that the thickness of the ferromagnetic ring 5a be 1.5 mm or more, and in this embodiment it was 2.0 mm.

As described above, in the rotation sensor of the embodiment, the protruding tip side of the pole piece 5 is of a type protruding from the extension space of the cylinder formed by the inner diameter of the bobbin, but the end surface of the pole piece 5 on the magnet side is substantially formed. It is possible to increase the effective diameter, and thus enhance the ability to condense the magnetic flux generated from the magnet and obtain high output.

Further, since the ferromagnetic ring is press-fitted into the magnetic pole piece 5, the magnetic pole piece 5 is prevented from falling down, and reliability is improved.

[0022]

【effect】

 As described above in detail, in the rotation sensor of the present invention, the diameter of the contact surface is increased by press-fitting the ferromagnetic ring into the magnetic pole element that contacts the magnet of the detection section. The output voltage is improved. Further, since the ring-shaped component prevents the magnetic pole piece from moving in the tip direction, it is possible to prevent the magnetic pole piece from falling off the bobbin. Since such a high output voltage is obtained and the reliability is also excellent, it is effective when applied as a rotation sensor for automobiles.

[Brief description of drawings]

FIG. 1 is a sectional view of a rotation sensor according to an embodiment.

FIG. 2 is a graph showing the relationship between the thickness of the ferromagnetic ring and the output voltage.

FIG. 3 is a sectional view of a conventional rotation sensor.

FIG. 4 is a sectional view of another conventional rotation sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotation sensor 2 coil 3 bobbin 4 magnet 5 pole piece 5a ferromagnetic material ring 6 yoke 7 terminal 8 lead wire 9 housing 10 potting agent 11 sensor rotor

Claims (2)

[Scope of utility model registration request] 1. A magnet is housed in a bobbin around which a coil is wound, and a magnetic pole element is provided which is in contact with the magnet and penetrates the bobbin. Consists of an electromagnetic induction type detection unit,
A rotation sensor in which a ferromagnetic ring is press-fitted into a rear end portion of the magnetic pole piece which is in contact with a magnet, and the ring rear end surface and the rear end surface of the magnetic pole are positioned so as to form a plane. 2. The thickness of the ferromagnetic ring is 1.5 mm
The rotation sensor according to claim 1, wherein the rotation sensor is configured as described above.