JPH0736012U - Electromagnetic rotation detector - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an electromagnetic power generation type rotation sensor which has a small number of cutting steps during manufacturing and is advantageous in terms of cost. [Structure] In an electromagnetic power generation type sensor having a permanent magnet 4, an iron core 1 through which a magnetic flux from this magnet passes, and a coil 2 wound around the iron core, the detection end of the iron core is 2 in view of detection sensitivity.
May have teeth. In the present invention, the detection end of the iron core 1 is formed into a pillar having a circular cross section, and the slit 9 of one letter or cross is formed at the center of the tip, so that the cutting process of the tip is performed in one or two steps, and the cost can be reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electromagnetic rotation detector for detecting the number of rotations of an automobile wheel or the like.

[0002]

[Prior art]

 In the electromagnetic power generation type rotation detector, the magnetic flux from the magnet is made to flow through the iron core (pole piece) of the magnetic material with the coil for power generation wound around it, with the tip (detection end) facing the teeth of the gear sensing rotor. The strength change of the magnetic flux coupling generated by the rotation of the rotor between the iron core and the sensing rotor is utilized to generate an electromotive force corresponding to the change in the coil, and this is taken out as a rotation detection signal.

In this type of conventional rotation detector, in order to improve the detection sensitivity, the detection end of the iron core has a shape having two teeth in accordance with the pitch between the teeth of the sensing rotor, and the coupling magnetic flux with the sensing rotor is formed. It is often done to increase the change amount of.

[0004]

[Problems to be solved by the device]

 When the detection end of the iron core has two teeth, conventionally, the shape of the detection end of the iron core is made to match the shape of the tooth tip surface of the sensing rotor, or is approximated as much as possible.

FIG. 7 and FIG. 8 show the shape of the detection end that has been conventionally used. In FIG. 1, 1 is an iron core, and 1a is a tooth for detection.

In the conventional rotation detector adopting such a shape, when the number of cutting man-hours at the detecting end is the shape shown in FIG. 7, there are 5 steps of the outer peripheral surface and the central slit, and in the case of the shape shown in FIG. There were three processes of slitting, which contributed to the cost increase.

Further, when changing the installation direction of the sensing rotor to the direction rotated by 90 °, the direction of the iron core also needs to be rotated by 90 °, and the rotation is not allowed after manufacturing. There was also a problem that we had to make two types of detectors in consideration.

The present invention seeks to provide a rotation detector that eliminates these problems.

[0009]

[Means for Solving the Problems]

 In order to solve the above problems, in the present invention, the detection end of the iron core is a pillar having a circular cross section, and a slit having a predetermined width is formed at the center of the tip.

If the slit formed in the center of the detection end is a cross slit in which two slits are orthogonal to each other, the same detector can respond to changes in the mounting direction of the sensing rotor.

Further, the detection end of the iron core can be made flat by filling the slit with a non-magnetic filling material.

[0012]

[Action]

 If the detection end has a circular cross section and a slit is inserted in the center, the cutting man-hour is reduced to one step in the case of a single-character slit and the cost is reduced to two steps even with a cross slit.

Further, the cross-shaped slit is slightly disadvantageous in terms of the detection function due to the reduction of the area of the magnetic flux coupling surface, but since it has an end face shape symmetrical with respect to the left, right, up and down, it corresponds to the detection of two orthogonal directions without doing anything. it can.

[0014]

【Example】

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

In each drawing, 1 is an iron core, 2 is a coil wound around a bobbin and concentrically attached to the outer circumference of the iron core, 3 is a mounting bracket, 4 is a permanent magnet attached to the rear end of the iron core, and 5 is an auxiliary iron core ( (York), 6 is a molding resin for sealing the rear part, 7 is a signal cable for extracting the output voltage of the coil, and 8 is a housing.

The tip or detection end of the iron core 1 has a straight cylindrical shape as shown in FIGS. 1 to 3 and a tapered cylindrical shape (taper) as shown in FIG. This detection end may have the same diameter as the intermediate portion diameter of the iron core as shown in FIGS. 1 and 2, or may have a different diameter as shown in FIG.

In the present invention, a slit having a single character as shown in FIG. 5A or a slit 9 having a cross as shown in FIG. 5B is provided at the center of the detection end having a circular cross section. Produces arc-shaped teeth 1a.

The detection end of the iron core 1 may be projected from the housing 8 as shown in FIGS. 1 and 4, or may be built in the housing as shown in FIGS.

FIG. 6 is an example of the use of the exemplary detector 10. The detector with the cross-shaped slit shown in Fig. 5 (b) has symmetrical detection edges on both the left and right sides, so the mounting direction of the sensing rotor A can be changed by 90 ° to suit different vehicle types. However, it can be handled without changing the direction of the iron core.

[0020]

[Effect of device]

 As described above, according to the present invention, a slit having a cutting step of one step or two steps is provided on the end face of the detection end, so that a detector having a high detection capability can be obtained at low cost.

In addition, one having a cross-shaped slit can support two types of mounting modes with one type of detector.

Further, when the slit is filled with a non-magnetic filling material, magnetic foreign matter such as iron powder or muddy water that causes rust can be prevented from accumulating inside the slit, so that it may be caused by foreign matter. The disturbance of the magnetic flux and the decay of the magnetic flux concentration due to the collapse of the tooth profile due to corrosion do not occur, and the reliability for maintaining the performance is enhanced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the present invention.

FIG. 2 is a sectional view of another embodiment.

FIG. 3 is a sectional view of another embodiment.

FIG. 4 is a sectional view of another embodiment.

5A is a perspective view showing an example of a detection end. FIG. 5B is a perspective view showing another example of the detection end.

FIG. 6 is a side view showing an example of use of a detector.

FIG. 7 is a perspective view showing an example of a detection end of a conventional detector.

FIG. 8 is a perspective view showing another example of the detection end of the conventional detector.

[Explanation of symbols]

 1 iron core 1a tooth 2 coil 3 bracket 4 permanent magnet 5 auxiliary iron core 6 mold resin 7 signal cable 8 housing 9 slit 10 detector A sensing rotor

Claims (3)

[Scope of utility model registration request] 1. A magnet, an iron core through which a magnetic flux from this magnet passes, and a coil for power generation wound around the iron core, the electromotive force changing the strength of magnetic flux coupling between the sensing rotor and the iron core. In the electromagnetic power generation type rotation detector which outputs in place of the above, the detection end of the iron core is a pillar having a circular cross section, and a slit having a predetermined width is formed at the center of the tip of the iron rotation core. 2. The electromagnetic rotation detector according to claim 1, wherein the slit is a cross slit in which two slits are orthogonal to each other. 3. The electromagnetic rotation detector according to claim 1, wherein the slit is filled with a non-magnetic filling material to flatten the detection end of the iron core.