Acceleration sensor

• US 5,196,660 A
• Filed: 11/18/1991
• Issued: 03/23/1993
• Est. Priority Date: 12/25/1990
• Status: Expired due to Fees

• Current Assignee: Takata Corporation (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Takata Corporation (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Sato, Ryo, Yoshimura, Kazuo, Shimozono, Shigeru
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US07/793,154
• Time in Patent Office: 491 Days
• Field of Search: 200/61.45 R-61.53
• US Class Current: 200/61.45M
• CPC Class Codes: B24B 49/105 using eddy currents
• CPC Class Codes: H01H 2300/052 Controlling, signalling or testing correct functioning of a switch see also H01H2300/056 - H01H2300/066 and H01H11/0062
• CPC Class Codes: H01H 35/14 Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch wherein the liquid constitutes a contact of the switch H01H29/002

Abstract

An accelerator sensor comprising a cylinder of a conductive material, a magnetized inertial member mounted in the cylinder so as to be movable longitudinally of the cylinder, a conductive member mounted at least on one end surface of the inertial member that faces a first longitudinal end of the cylinder, a pair of electrodes disposed at the first longitudinal end of the cylinder, and an atracting member disposed near the other longitudinal end of the cylinder. When the conductive member of the inertial member comes into contact with the electrodes, these electrodes are caused to conduct via the conductive member. The attracting member is made of a magnetic material such that the attracting member and the inertial member are magnetically attracted toward each other. The sensor further comprises a coil for testing the operation of the sensor and an another coil capable of biasing magnetically the inertial member to compensate operation of the cylinder due to temperature.

Claims

1. An acceleration sensor comprising:

a cylinder made of a conductive material and having first and second ends located at longitudinal ends thereof;

a magnetized inertial member situated in the cylinder so as to be slidable longitudinally of the cylinder;

a conductive member mounted on at least one end surface of the inertial member, said end surface facing the first end of the cylinder,

a pair of electrodes disposed at the first end of the cylinder, said electrodes being electrically connected together when the conductive member mounted on the inertial member contacts the electrodes,

an attracting member disposed near the second end of the cylinder, said attracting member being made of a magnetic material and attracting the inertial member to be located near the second end of the cylinder,

a first coil wound around the cylinder, said first coil, when actuated, operating to move the inertial member toward the first end to electrically connect the electrodes together by contacting the conductive member on the inertial member to the electrodes,

a second coil wound around the cylinder near the first end to compensate movement of the inertial member when acceleration is applied to the inertial member, said second coil being actuated in a condition such that a braking force which is created and applied to the inertial member when the inertial member is moved inside the cylinder upon detection of a predetermined acceleration is outside a predetermined range, and said second coil forming a magnetic field around the cylinder to move the inertial member inside the cylinder within the predetermined range, and

means for actuating the second coil to compensate a variation of resistance of the cylinder so that the braking force applied to the inertial member is within the predetermined range.

2. The acceleration sensor of claim 1 wherein said second coil is actuated to increase the braking force applied to the inertial member when the braking force is not sufficiently applied to the inertial member due to increase of the temperature surrounding the sensor above a predetermined value.

3. The acceleration sensor of claim 1, wherein said second coil is actuated to decrease the braking force applied to the inertial member when the braking force is excessively applied to the inertial member due to decrease of the temperature surrounding the sensor below a predetermined value.