Overload protective system

• US 5,565,826 A
• Filed: 10/14/1994
• Issued: 10/15/1996
• Est. Priority Date: 11/02/1992
• Status: Expired due to Fees

• Current Assignee: Per Olof Karlstrom
• Original Assignee: Per Olof Karlstrom
• Inventors: Karlstrom, Per Olof
• Primary Examiner(s): DONOVAN, LINCOLN D
• Application Number:
  US08/318,789
• Time in Patent Office: 732 Days
• Field of Search: 335/16, 335/147, 335/195, 361/58, 361/59, 218/22, 218/24, 218/26
• US Class Current: 335/16
• CPC Class Codes: H01C 7/027 consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
• CPC Class Codes: H01C 7/13 current responsive
• CPC Class Codes: H01H 77/10 with electrodynamic opening combined with electromagnetic release mechanism H01H71/2418
• CPC Class Codes: H02H 9/026 Current limitation using PTC resistors, i.e. resistors with a large positive temperature coefficient

Abstract

The protective device for protecting against over currents in electric circuits includes at least one electrically conductive body and two electrodes which function to supply circuit current through the conductive body and which lie against the conductive body at corresponding positions either directly or through the medium of an intermediate part. An abutment pressure is applied to the electrode so that the electrodes are maintained in abutment at the corresponding positions of the conductive body. When the devices are subjected to high short circuiting currents, the current density in the deformed abutment surfaces of the conductive body will increase, thus increasing the resistance of the device.

Claims

1. A device for protecting against overcurrents in electric circuits comprising:

at least one electrically conductive body which is comprised of elastomeric material; and

two electrodes which supply circuit current through the body and each of which is in abutment with the body at corresponding abutment surfaces, either directly or through the intermediary of an intermediate part, and in which abutment pressure is obtained through the medium of a pressure device,

the electrodes being constructed so as to repel one another under the influence of overcurrents,

the abutment surfaces decreasing as overcurrent passes through the body and at least one electrode/intermediate part being convex in a pressureless state but being deformed by the pressure device at respective abutment surfaces by the pressure exerted thereon.

2. The device according to claim 1, wherein the intermediate part is also comprised of elastomeric material.

3. The device according to claim 2, wherein the elastomeric body and the intermediate part have a Shore number between 20-80.

4. The device according to claim 1, wherein the pressure device is resilient.

5. The device according to claim 1, wherein the pressure device is a spring mechanism having two mechanically stable equilibrium states, on and off respectively,

at least one of the electrodes being mechanically coherent with the spring mechanism for galvanic electrodes.

6. The device according to claim 1, wherein the pressure device is adjustable to adjust the applied abutment pressure.

7. The device according to claim 1, wherein the electrodes are provided with ferromagnetic circuits which function to amplify the repelling force between the electrodes.

8. The device according to claim 1, wherein elastomeric material is expanded over the electrodes.

9. The device according to claim 1, wherein the body is compressed by the pressure device to at least 5% when the body is homogeneous.

10. The device according to claim 9, wherein the pressure device functions to compress the body to 5%-40% when the body is homogeneous.

11. The device according to claim 1, wherein the body has a central cavity.