Current interrupt apparatus for electrochemical cells

• US 6,210,824 B1
• Filed: 12/18/1998
• Issued: 04/03/2001
• Est. Priority Date: 01/15/1998
• Status: Expired due to Fees

• Current Assignee: Sensata Technologies Massachusetts Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Dexter, Mark G., Sullivan, Steven K., French, Kevin R.
• Primary Examiner(s): Kalafut, Stephen
• Assistant Examiner(s): Martin, Angela J.
• Application Number:
  US09/216,046
• Time in Patent Office: 837 Days
• Field of Search: 429/53, 429/7, 429/56, 429/61, 429/54, 429/55, 429/72, 429/59
• US Class Current: 429/53
• CPC Class Codes: H01H 35/343 by snap acting diaphragm
• CPC Class Codes: H01H 37/54 wherein the bimetallic element is inherently snap acting
• CPC Class Codes: H01M 50/3425 in the form of rupturable membranes or weakened parts, e.g. pierced with the aid of a sharp member
• CPC Class Codes: H01M 50/574 Devices or arrangements for the interruption of current
• CPC Class Codes: H01M 50/578 in response to pressure
• CPC Class Codes: H01M 50/581 in response to temperature
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

End cap apparatus (2) is received in the open end of an electrochemical cell casing (6) and is particularly adapted to be crimped thereto electrically separated from the casing by a gasket (4). The end cap apparatus incorporates current interrupt safety protection features including high rate overcharge protection through an over-temperature and/or low pressure switch (22, 12d-18, 18′, 18″, 118a), low rate overcharge and overdischarge protection through a low pressure switch (12d-18, 18′, 18″, 118a), extended short circuit protection through an over-temperature switch driven by l²r heating of internal components (20, 22, 16, 12, 12′, 16′, 16″, 16′″, 12^v, 102, 122, 120), and pressure venting through a frangible portion (12e) of a diaphragm. The diaphragm can be integrally formed with a header (12, 12″, 12′″, 12^iv) or can be a separate element (32, 82, 92, 108, 112, 112′ 112″, 112′″).

Claims

1. Electrically conductive end cap apparatus for use with an electromechanical cell comprising an electrically conductive header having a rigid, circumferential flange extending about the periphery thereof, a switch cavity formed in, the header,

a stationary electrical contact mounted within the switch cavity electrically connected to the header,

a generally annular insulative member received in the switch cavity, the annular insulative member having a disc seat,

an electrically conductive spring member having a movable contact portion movable into and out of electrical engagement with and normally biased into engagement with the stationary contact,

a snap acting thermostatic disc having first and second oppositely dished configurations and having a centrally disposed aperture, the disc being received on the disc seat, the stationary electrical contact aligned with the centrally disposed aperture, the stationary contact extending through the centrally disposed aperture when the disc is in one of the first and second configurations, the disc biasing the movable contact away from the stationary contact when in the other of the first and second configurations,

an electrically conductive top cap having an outer periphery supported on the annular insulative member and electrically connected to the spring member, the header having a peripherally extending lip deformed over to fixedly grasp the outer peripheral portion of the top cap with a portion of the insulative member therebetween to electrically separate the header from the top cap, the top cap having vent holes formed therethrough,

the header having a thin diaphragm extending across the switch cavity formed with a frangible portion aligned with the switch cavity, the frangible portion being breakable when exposed to a selected pressure, the diaphragm being snap-acting when exposed to sufficient increase in pressure up to the selected pressure;

and

and electrically insulative motion transfer member movably mounted in the switch chamber between the diaphragm and the spring member and having a length selected so that an increase in pressure above a given level will cause the diaphragm to snap to transfer motion to the spring member via the motion transfer member so as to move the movable contact out of engagement with the stationary contact.

2. Electrically conductive end cap apparatus according to claim 1 in which the diaphragm is formed integrally with the header.

3. Electrically conductive end cap apparatus according to claim 1 in which the diaphragm and header are separate elements.

4. Electrically conductive end cap apparatus according to claim 1 in which motion transfer member comprises an elongated pin.

5. Electrically conductive end cap apparatus according to claim 1 in which the motion transfer member comprises a main body portion formed with a plurality of legs.

6. Electrically conductive end cap apparatus according to claim 1 in which the spring member is suspended from the top cap.

7. Electrically conductive end cap apparatus according to claim 1 in which the spring member is supported on the annular insulative member.

8. Electrically conductive end cap apparatus according to claim 1 in which the top cap is overmolded with annular insulative material with the annular insulative material extending over the vent holes.

9. Electrically conductive end cap apparatus according to claim 1 in which the diaphragm has an outer periphery and the frangible portion of the diaphragm is located inboard of the outer periphery of the diaphragm to provide a sudden deflection of the diaphragm at a selected pressure level.

10. Electrically conductive end cap apparatus according to claim 1 in which the diaphragm is formed with a dished configuration so that it will snap from one configuration to an opposite configuration at a selected pressure level.

11. Electrically conductive end cap apparatus according to claim 1 in which the header member is formed of a plate having generally uniform thickness and bent into selected configurations.

12. Electrically conductive end cap apparatus according to claim 1 in which the head member is formed of a block of material having varying thickness.