Nickel alloy magnetostrictive wire and displacement detection device using same

• US 5,886,518 A
• Filed: 12/27/1996
• Issued: 03/23/1999
• Est. Priority Date: 01/12/1996
• Status: Expired due to Fees

• Current Assignee: Sumitomo Seika Chemicals Company Limited, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Sumitomo Seika Chemicals Company Limited, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Hayashi, Hideo, Ogata, Kentaro, Kuroda, Kazushi
• Primary Examiner(s): Patidar, Jay M.
• Application Number:
  US08/774,370
• Time in Patent Office: 816 Days
• Field of Search: 324/207.13, 324/207.24, 324/207.22, 324/533, 73/290 V, 73/314, 148/301, 420/416, 333/148, 365/157
• US Class Current: 324/207.13
• CPC Class Codes: G01D 5/485 using magnetostrictive devices
• CPC Class Codes: H10N 35/85 Magnetostrictive active materials

Abstract

A displacement detection device and a wire therefor in which the drawbacks of the conventional Elinvar-type alloy are eliminated, the magnetostriction intensity as well as the magnetostriction propagation speed does not vary with temperature, and a magnetostriction coefficient is sufficiently great to enable an amplification at a high speed of response to be unnecessary. A magnetostrictive wire used in a displacement detection device together with a magnetostriction-generating magnet disposed close thereto and movable relative thereto, said wire substantially composed of 35 to 60 wt % Ni and the balance consisting of Fe and unavoidable impurities, cold-wire-drawn and then heat-treated and having a magnetostriction coefficient greater than that exhibited in an as-cold-wire-drawn state. A displacement detection device includes the above-mentioned magnetostrictive wire and a magnetostrictive-generating magnet disposed movable relative thereto and therealong for detecting a relative displacement between the magnetostrictive wire and the magnet based on a time of propagation, through the wire, of a magnetostriction signal generated in the wire in the portion close to the magnet by a pulse current applied to the wire.

Claims

1. A magnetostrictive wire used in a displacement detection device together with a magnetostriction-generating magnet disposed close thereto and movable relative thereto, said wire substantially composed of 35 to 60 wt % Ni and the balance consisting of Fe and unavoidable impurities, cold-wire-drawn and then heat-treated and having a magnetostriction coefficient greater than that exhibited in an as-cold-wire-drawn state.

2. A magnetostrictive wire according to claim 1, wherein said heat treatment is carried out at a temperature of from 400°

C. to 1100°

C.

3. The magnetostrictive wire according to claim 1, wherein the wire is 50 wt % Ni and 50 wt % Fe.

4. The magnetostrictive wire according to claim 1, wherein the wire has a magnetostriction coefficient of 2×

10^-6.

5. The magnetostrictive wire according to claim 1, wherein the heat treatment is performed about 600°

C.

6. A displacement detection device comprising a magnetostrictive wire and a magnetostrictive-generating magnet disposed movable relative thereto and therealong for detecting a relative displacement between the magnetostrictive wire and the magnet based on a time of propagation, through the wire, of a magnetostriction signal generated in the wire in the portion close to the magnet by a pulse current applied to the wire, said wire being substantially composed of 35 to 60 wt % Ni and the balance consisting of Fe and unavoidable impurities, cold-wire-drawn and then heat-treated and having a magnetostriction coefficient greater than that exhibited in an as-cold-wire-drawn state.