JP3257149B2 - Wheel structure of annular magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for arranging a wheel of an annular magnet, and more particularly, to providing a ring magnet in a groove formed around an outer peripheral edge of a rotary wheel, the number of parts and the time required for manufacturing. The present invention relates to a proposal in which the number of steps and steps can be greatly reduced, and the magnet is suitably stopped from rotating in the groove.

[0002]

2. Description of the Related Art As shown in, for example, Japanese Patent Application Laid-Open No. 64-3512, there is generally known a rotation sensor mounted on a rotating body such as a wheel of an automobile to detect the rotating speed and the number of rotations of the rotating body. In this rotation sensor, as shown in FIG. 1 of the publication, a magnet ring 12 is pressed into the outer periphery of an inner ring 11 and an outer ring 14 is pressed into the outer periphery of the magnet ring 12 to prevent the magnet ring from falling off. It comprises a rotation sensor ring which has been prevented, and a magnetic sensor provided with a magnetic pole 5 disposed close to the rotation peripheral surface of the rotation sensor ring.
Since the outer peripheral surface of the plastic magnet constituting the magnet ring 12 is multipolar magnetized so that the N pole and the S pole are alternated, the magnet ring 12 is rotated with the rotation of the sensor ring.
The magnetic flux generated from the magnetized region and passing through the magnetic pole 5 changes with time. For this reason, the excitation voltage detected by the magnetic sensor also changes, and information on the rotation speed and the number of rotations of the rotating body is output.

[0003]

As described above, the rotation sensor ring is a magnet ring 12 made of a plastic magnet.
Is pressed into the outer periphery of the inner ring 11, and then the outer ring 14 is pressed from the outside to prevent the outer ring 14 from falling off. This has many parts and time and steps to manufacture, and the product cost is low. Has the major disadvantage of increasing.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned drawbacks inherent in the prior art rotation sensor ring, and has been proposed to solve the problem in a favorable manner. It is intended to provide means capable of reducing the number of steps and processes.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to appropriately achieve the intended purpose, a wheel arrangement structure of an annular magnet according to the present invention is mounted on a rotating body and rotates integrally. A groove provided around the outer peripheral edge of the wheel,
A gate formed in the wheel and communicating with the groove; and a ring magnet magnetized by multi-polarizing the solidified mixture by cooling and solidifying a molten mixture of magnetic powder and thermoplastic resin injected into the groove through the gate. The annular magnet is characterized in that the rotation of the groove portion of the wheel is stopped through a part of the mixture remaining and solidified in the gate.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a wheel arrangement structure for an annular magnet according to the present invention. FIG. 1 is a longitudinal sectional view showing a wheel mounting structure for an annular magnet according to an embodiment of the present invention. 14 is fixed. At the outer peripheral edge 16 of the wheel 12, a bottomed groove portion 18 having a vertical T-shaped cross section as shown in FIG. 1 is provided, and a molten mixture of magnetic powder and thermoplastic resin is injected into the groove portion 18, Is cooled and solidified to form the annular magnet 20. However, the annular magnet 20 is not magnetized when cooled and solidified, and is magnetized in a subsequent step so that the N pole and the S pole are alternately magnetized on the outer peripheral surface of the magnet. It is. The shape of the bottomed groove 18 provided around the outer peripheral edge of the wheel 12 may be trapezoidal in a longitudinal section as shown in FIG. 2 or rectangular as shown in FIG.

As described above, the bottomed groove 1 of the wheel 12
8 is filled with a molten mixture of a magnetic powder and a thermoplastic resin by an injection molding technique. In order to introduce the molten mixture into the groove 18, the wheel 12 is connected to a gate communicating with the groove 18. 22 is drilled. In the embodiment shown in FIG. 1, the gate 22 is formed in the axial direction of the wheel 12 (that is, in the direction parallel to the central axis of the rotating shaft 10), and at a required central angle in the circumferential direction of the wheel 12 as appropriate. Are provided. Further, the gate 22
May be set inward in the radial direction of the wheel 12, depending on the shape of the cross section on the outer peripheral side of the wheel 12, for example, as shown in the embodiment of FIG. 4 or FIG.
Further, as shown in the embodiment of FIGS. 6 and 7, it may be set on the radially outer side of the wheel 12. The gate 22 is formed in a stepped shape having different inner diameters as can be seen from the drawing.

FIG. 8 schematically shows a mold structure for injecting the molten mixture into the groove 18 of the wheel 12, and the mold structure 24 receives the wheel 12 from the left side and the right side. And a movable mold 28 which is in contact with the right side surface of the wheel 12 so as to be able to freely contact and separate therefrom. The runner 30 formed inside the movable mold 28 is mounted on the wheel 12 set in the fixed mold 26.
The opening is made to coincide with the gate 22 of FIG. The runner 30 is connected to the bush 3 via a sprue 32.
4, the molten mixture introduced from a nozzle 36 of an injection molding machine (not shown) is injected into the bottomed groove 18 of the wheel 12 through the gate 22. The magnetic powder constituting the molten mixture is, for example, neodymium.
Powders of rare earth elements such as iron-boron, samarium-iron-nitrogen, samarium-cobalt and powders of metal oxides such as ferrite are preferably used. As the thermoplastic resin, for example, nylon 12, nylon 6, nylon 66. A resin having high heat resistance such as polyphenyl sulfide (PPS) is preferably used. The mixing ratio was 8 for magnetic powder.
5-95 weight percent, with the balance being thermoplastic resin.

The molten mixture injected into the groove 18 through the gate 22 is cooled and solidified to form an annular magnet 20 (unmagnetized) located in the bottomed groove 18 of the wheel 12. At this time, as shown in FIG. 8, a part of the molten mixture remains in the gate 22 and is solidified in a pin shape.
0a. In this state, when the movable mold 28 is moved in the direction of arrow A with respect to the fixed mold 26, the pin-shaped portion 20a breaks in the middle as shown in FIG. That is, the broken portion of the pin-shaped portion 20 a connected to the annular magnet 20 remains at the position facing the corresponding gate 22. Therefore, even if the rotation sensor ring is exposed to a high temperature or ages due to long-term use, and the degree of adhesion between the annular magnet 20 and the bottomed groove portion 18 decreases, the pin-shaped portion facing the gate 22 is not affected. 2
0a holds the annular magnet 20.
The rotation of the annular magnet 20 with respect to the bottomed groove 18 is suitably stopped. Further, since the broken end of the pin-shaped portion 20a is located inside each corresponding gate 22 and is not exposed on the side surface of the wheel 12, there is an advantage that post-processing such as deburring is not required. As described above, the thus formed annular magnet 20 is subjected to a magnetizing process in a subsequent step, and the N pole and the S pole are alternately magnetized on the outer peripheral surface of the magnet. . Further, in the embodiment, the wheel of the automobile is assumed as the rotating body, but the rotating body is not limited to this, and includes all rotating members constituting a rotating system such as a rotating shaft of a motor.

[0010]

As described above, according to the wheel arrangement structure of the annular magnet according to the present invention, when the annular magnet is provided in the groove formed around the outer peripheral edge of the rotary wheel,
The number of parts and the labor and steps required for manufacturing can be greatly reduced. Moreover, since the annular magnet is held by the pin-shaped portion located in the gate, the rotation of the magnet with respect to the wheel groove is stopped. In addition, since the broken end of the pin-shaped portion is not exposed on the wheel side surface, there are obtained many useful advantages such as not requiring post-treatment such as deburring.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a wheel mounting structure for an annular magnet according to an embodiment of the present invention.

FIG. 2 shows a bottomed groove formed around the outer peripheral edge of the wheel,
It is a fragmentary sectional view showing the example which made trapezoidal in a longitudinal section.

FIG. 3 shows a bottomed groove formed around the outer peripheral edge of the wheel;
It is a fragmentary sectional view showing the example made into a rectangular shape in the longitudinal section.

FIG. 4 is a partial cross-sectional view showing an example in which the direction in which the gate is pierced is set inward in the radial direction of the wheel.

FIG. 5 is a partial cross-sectional view showing an example in which the direction in which the gate is pierced is set inward in the radial direction of the wheel.

FIG. 6 is a partial cross-sectional view showing an example in which the direction of piercing the gate is set to the outer side in the radial direction of the wheel.

FIG. 7 is a partial cross-sectional view showing an example in which the direction of piercing the gate is set to the outer side in the radial direction of the wheel.

FIG. 8 is a schematic sectional view showing a mold structure for injecting a molten mixture into a groove of a wheel.

FIG. 9 is a partial cross-sectional view showing that a pin-shaped portion facing the gate is broken halfway by moving the movable mold with respect to the fixed mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rotating body 12 Wheel 16 Outer peripheral edge 18 Groove 20 Ring magnet 20a Pin-shaped part (part of solidified mixture) 22 Gate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01D 5/00-5/62 G01B ⁷ /00-7/32 G01P 1/00-3/80

Claims (5)

(57) [Claims] 1. A groove (18) provided around an outer peripheral edge (16) of a wheel (12) mounted on a rotating body (10) and integrally rotating, and a groove formed in the wheel (12). A gate (22) communicating with (18), and a molten mixture of the magnetic powder and the thermoplastic resin injected into the groove (18) through the gate (22) is cooled and solidified, and the multipolar magnetization is applied to the solidified mixture. Ring magnet
The annular magnet (20) rotates with respect to the groove (18) of the wheel (12) via a part (20a) of the mixture remaining and solidified in the gate (22). A wheel arrangement structure for an annular magnet, which is stopped. 2. The wheel arrangement structure of an annular magnet according to claim 1, wherein said gate (22) is bored in an axial direction of said wheel (12). 3. The wheel arrangement structure for an annular magnet according to claim 1, wherein said gate (22) is bored radially inward of said wheel (12). 4. The wheel arrangement structure for an annular magnet according to claim 1, wherein said gate (22) is bored radially outward of said wheel (12). 5. The wheel arrangement structure for an annular magnet according to claim 1, wherein said gate (22) has steps having different inner diameters.