Thermal switch disc for short circuit protection of batteries

• US 4,973,936 A
• Filed: 04/27/1989
• Issued: 11/27/1990
• Est. Priority Date: 04/27/1989
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Bragg, Bobby J., Dimpault-Darcy, Eric C.
• Primary Examiner(s): Reynolds, Bruce A.
• Assistant Examiner(s): LATEEF, MARVIN M
• Application Number:
  US07/343,652
• Time in Patent Office: 579 Days
• Field of Search: 338/22 R, 338/221, 338/220, 338/8, 320/49, 320/51
• US Class Current: 338/32.00R
• CPC Class Codes: H01M 10/613 Cooling or keeping cold
• CPC Class Codes: H01M 10/637 characterised by the use of reversible temperature-sensitive devices, e.g. NTC, PTC or bimetal devices; characterised by control of the internal current flowing through the cells, e.g. by switching means for preventing undesired use or discharge H01M50/572
• CPC Class Codes: H01M 10/64 characterised by the shape of the cells
• CPC Class Codes: H01M 10/643 Cylindrical cells
• CPC Class Codes: H01M 2200/00 Safety devices for primary or secondary batteries
• CPC Class Codes: H01M 2200/106 PTC
• CPC Class Codes: H01M 50/574 Devices or arrangements for the interruption of current
• CPC Class Codes: H01M 50/581 in response to temperature
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A protective device for one battery or serially arranged battery cells is adapted to fit between one battery and its terminal connector or between adjacent battery cells. The device incorporates a disk of positive temperature coefficient material having a pair of circular end faces for contact. The disk is supported by a ring adhesively joined thereto, the ring having a central axial opening to enable the button terminal of a battery cell to contact against the disk as the disk and battery cell are arranged in a single battery application or in serial contact with similar battery cells.

Claims

1. A protective insert for use with one battery or with one or more battery cells connected in serial connection wherein one of the cells has a central current providing terminal shaped as a button, and the insert comprises a circular disk of specified diameter having parallel opposing faces and wherein the circular disk is formed of positive temperature coefficient resistive material increasing to a high resistance at a specified operating temperature, and also includes a joined circular spacer ring having a central aperture wherein the aperture is sized to received the battery terminal therein for contact with said disk, and said ring is formed of electrical insulation material, and wherein said disk and ring are joined by an adhesive material therebetween.

2. The apparatus of claim 1 wherein said disk has exposed upper and lower circular surfaces and said lower surface is positioned within said aperture in said ring, and wherein said ring has a diameter permitting said ring to fit around a typical positive terminal and within a battery case bead surrounding said terminal.

3. The apparatus of claim 2 wherein said ring includes an axially located aperture concentric within a circular surrounding outer periphery.

4. The apparatus of claim 3 wherein said circular disk includes metal clad upper and lower faces.