Circuit protection devices

• US 4,599,597 A
• Filed: 10/15/1984
• Issued: 07/08/1986
• Est. Priority Date: 10/20/1983
• Status: Expired due to Fees

• Current Assignee: Societe D'Exploitation Soremec-Chess
• Original Assignee: Societe D'Exploitation Soremec-Chess
• Inventors: Rotbart, Guy
• Primary Examiner(s): Broome, Harold
• Application Number:
  US06/660,887
• Time in Patent Office: 631 Days
• Field of Search: 337/206, 337/221, 337/189, 337/188, 337/222, 337/223
• US Class Current: 337/206
• CPC Class Codes: H01H 2085/0275 Structural association with a printed circuit board
• CPC Class Codes: H01H 85/306 acting on an auxiliary switch or contact

Abstract

A circuit protection device, particularly for printed circuit boards, comprises a slider (25) which is held in a first operating position by fusible wire (49) extending between two pegs (19,20). The slider is propelled by a spring (48), upon fusion of the fusible wire, into a second position in which it closes a signalling circuit by means of a conductive plate (33) which comes to rest against the pegs (21,22). Means (40,41; 46, 47) is provided to prevent rebound of the plate (33) from the pegs (21,22).

Claims

1. A circuit protection device particularly for printed circuit boards, comprising:

a base made of an insulating material;

a first pair of pins projecting from one face of the base for connection to a circuit to be protected and projecting from the other face of the base to terminate in a first pair of pegs;

an elongate fusible element connected between said first pair of pegs;

a second pair of pins for connection to a circuit to be controlled and terminating in a second pair of pegs;

a slider which is adapted to be retained adjacent the first pair of pegs by the fusible element;

resilient means acting on the slider in the direction towards the second pair of pegs;

guide means provided on the base for guiding the travel of the slider;

a contact plate supported by the slider and engageable with the second pair of pegs after fusion of the fusible element; and

co-operating means provided on the base and the slider for ensuring effective rebound--free contact between the contact plate and the second pair of pegs.

2. A device as claimed in claim 1, in which the co-operating means is a mechanical means.

3. A device as claimed in claim 1 wherein said co-operating means is a magnetic means.

4. A device as claimed in claim 1 in which the slider carries a substantially U-shaped contact arrangement having one limb which extends transversely with respect the path of the slider and a web which is provided with an opening receiving a projection of the slider, the transverse limb of the contact element being provided with two lateral tongues as cooperating means the projection of the slider being guided in a groove provided in the base and the two lateral tongues arranged one on each side of the opening being intended to be guided in two other lateral channels provided in the base.

5. A device as claimed in claim 4, in which stop notches as cooperating means are provided in the lateral channels of the base which stop notches engage the two lateral tongues of the contact arrangement when the contact plate bears against the second pair of pegs and is flexed between them.

6. A device as claimed in claim 1, in which the slider, preferably made of a ceramic material, comprises a prismatic projecting portion having a convex frontal surface over which passes the fusible wire, the resilient means being compressed between the face opposite the convex surface and a corresponding wall of the base.

7. A device as claimed in claim 6, in which the base comprises a further wall similar to the wall against which the resilient means bears, these two walls, together, serving to locate a cover plate of the device, the whole being enclosed by a cover which frictionally engage the base.

8. A device as claimed in claim 7, in which the cover plate and the cover each have an opening which is disposed over the projecting portion of the slider allowing the latter to be observed when the slider is retained in position by the fusible element.

9. A device as claimed in claim 3, in which the contact plate bears a frontal steel block disposed opposite a permanent magnet supported by the base between the second pair of pegs the steel block being attracted to the magnet upon fusion of the fusible element causing the contact plate to flex inwards between the second pegs under the action of the resilient means.

10. A device as claimed in claim 2, in which the co-operating means on the slider, in the position in which it establishes electrical connection between the second pair of pegs, comprises a second spring which is separate from the resilient means and which acts in a direction which is perpendicular to the direction of action of the resilient means, the contact plate being retained in a flexed position between the second pair of pegs by a locking mechanism displaced by the second spring upon fusion of the fusible elements.

11. A device as claimed in claim 10, in which the locking mechanism comprises a casing with slits for guiding the contact plate which is held in its position away from the said second pair of pegs, against the action of the second spring, by two balls retained on a chamfer of the casing by a member which is connected to the slider and is adapted so that it may move out of engagement with the balls upon fusion of the fusible element, under the action of the resilient means.