Magnetostrictive torque sensor and method for manufacturing a magnetostrictive torque sensor

Abstract

To provide a magnetostrictive torque sensor capable of preventing a flexible substrate having a plurality of detection coils from being pressed strongly in a thickness direction at high temperatures, and a method for manufacturing the magnetostrictive torque sensor.SOLUTION: A magnetostrictive torque sensor 1 comprises: a bobbin 2 having a cylindrical part 21 with a cavity 20 formed in a center part through which a rotational shaft 90 is inserted; a flexible substrate 4 wound around an outer periphery of the cylindrical part 21 of the bobbin 2, and having a plurality of detection coils 410 to 449 formed by a wiring pattern; a cylindrical magnetic ring 6 that houses the flexible substrate 4 between itself and the cylindrical part 21; and a filler 7 made of a hardening resin, which is filled between the cylindrical part 21 of the bobbin 2 and the flexible substrate 4 and the magnetic ring 6. A linear expansion coefficient of the bobbin 2 is higher than that of the magnetic ring 6, and the filler 7 is hardened when the cylindrical part 21 of the bobbin 2, the flexible substrate 4, and the magnetic ring 6 are at a temperature higher than an upper limit temperature of an operating temperature range of the magnetostrictive torque sensor 1.SELECTED DRAWING: Figure 5

Claims

1. A magnetostrictive torque sensor mounted around a rotating shaft having a magnetostrictive effect, which detects the torque transmitted by the rotating shaft within a predetermined operating temperature range, A resin molded body having a cylindrical portion with a cavity formed in the center through which the aforementioned rotating shaft is inserted, A flexible substrate is wrapped around the outer circumference of the cylindrical portion of the resin molded body, and a plurality of detection coils are formed by a wiring pattern, A cylindrical magnetic ring that houses the flexible substrate between itself and the cylindrical portion, The device comprises a filler made of a curable resin, which is filled between the cylindrical portion, the flexible substrate, and the magnetic ring. The coefficient of linear expansion of the resin molded body is higher than the coefficient of linear expansion of the magnetic ring. The filler is hardened when the cylindrical portion, the flexible substrate, and the magnetic ring are at a temperature higher than the upper limit temperature of the operating temperature range. Magnetostrictive torque sensor.

2. The linear expansion coefficient of the filler is lower than that of the resin molded body and higher than that of the magnetic ring. The magnetostrictive torque sensor according to claim 1.

3. The filler is a thermosetting resin whose curing temperature is higher than the upper limit temperature. The magnetostrictive torque sensor according to claim 1.

4. The flexible substrate has a strip-shaped portion extending in the circumferential direction of the cylindrical portion, and both longitudinal ends of the strip-shaped portion are fastened with tape. The magnetostrictive torque sensor according to claim 1.

5. The aforementioned filler material forms a locking portion that prevents the magnetic ring from coming off. The magnetostrictive torque sensor according to claim 1.

6. A method for manufacturing a magnetostrictive torque sensor, which is mounted around a rotating shaft having a magnetostrictive effect and detects the torque transmitted by the rotating shaft within a predetermined operating temperature range, A preparation step to prepare a resin molded body having a cylindrical portion with a cavity formed in the center through which the rotating shaft is inserted, a flexible substrate with multiple detection coils formed by a wiring pattern, and a cylindrical magnetic ring with a lower coefficient of linear expansion than the resin molded body. The arrangement step involves winding the flexible substrate around the outer circumference of the cylindrical portion and arranging the magnetic ring on the outer circumference of the cylindrical portion and the flexible substrate. The process includes a curing step in which a filler made of a curable resin, which is filled between the cylindrical portion, the flexible substrate, and the magnetic ring, is cured while the temperature of the cylindrical portion, the flexible substrate, and the magnetic ring is raised above the upper limit temperature of the operating temperature range. A method for manufacturing a magnetostrictive torque sensor.

7. The filler is a thermosetting resin whose curing temperature is higher than the upper limit temperature. In the curing step, the liquid filler material before curing is filled between the cylindrical portion, the flexible substrate, and the magnetic ring, and then the temperature of the filler material is raised above the upper limit temperature to cure it. A method for manufacturing a magnetostrictive torque sensor according to claim 6.

8. The flexible substrate has a strip-shaped portion that extends in the circumferential direction of the cylindrical portion, In the arrangement step, both ends in the longitudinal direction of the strip-shaped portion of the flexible substrate are secured with tape. A method for manufacturing a magnetostrictive torque sensor according to claim 6.

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