US4990883A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Actuator which can be locked when exposed to a high temperature
Assignee: Raychem Corp
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Filing: 1989-06-09
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Granted: 1991-02-05
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Expires: 2009-06-09
Abstract
Abstract An actuator such as an electrical switch which responds to an event such as a change in temperature by movement of an element between first and second positions, for example in which an electrical circuit is open and closed respectively, includes a dimensionally heat-recoverable component which, on recovery when the actuator is exposed to a high temperature, changes configuration so that a portion of the component is positioned between the element while in its first position and a support for the component, so as to restrain movement of the element towards its second position. This allows the actuator to be locked as a result of exposure to the high temperature, which can be desirable, for example, because of damage to equipment to which the actuator is connected.
Inventors
- 👤 Jesus Escobar
- 👤 Donald Wilkerson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 04:35
CPC Classifications
H; H01; H01H; H01H37/00; H01H37/02; H01H37/32; H01H37/323
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
142 words
An electrical switch having at least three positions: (i) an open switch position; (ii) a closed switch position; and (iii) a locked open switch position; said switch comprising: (a) a first electrical contact; (b) a support member; (c) a moveable arm element comprising a second electrical contact, which second contact is moveable from said open switch position to said closed switch position in response to an event; and (d) a component comprising heat-recoverable shape memory alloy having an initial austenitic phase transformation temperature A s , at least a part of which component, on its first exposure to a temperature above A s , moves to a position such that said component is interposed between said support member and said element whereby said switch is fixed in the locked open switch position even on subsequent exposure to temperatures below A s .
Claim 2
Dependent Claim
142 words
An electrical switch having at least three positions: (i) an open switch position; (ii) a closed switch position; and (iii) a locked open switch position; said switch comprising: (a) a first electrical contact; (b) a support member; (c) a moveable arm element comprising a second electrical contact, which second contact is moveable from said open switch position to said closed switch position in response to an event; and (d) a component comprising heat-recoverable shape memory alloy having an initial austenitic phase transformation temperature A s , at least a part of which component, on its first exposure to a temperature above A s , moves to a position such that said component is interposed between said support member and said element whereby said switch is fixed in the locked open switch position even on subsequent exposure to temperatures below A s .
Claim 3
Dependent Claim
17 words
A switch in accordance with claim 1, wherein said shape memory alloy is a nickel titanium alloy.
Claim 4
Dependent Claim
25 words
A switch as claimed in claim 1, in which the element moves in a plane between the open switch position and the closed switch position.
Claim 5
Dependent Claim
29 words
A switch as claimed in claim 3, in which the element is mounted pivotally so that it can rotate between the open switch position and the closed switch position.
Claim 6
Dependent Claim
29 words
A switch as claimed in claim 3, in which the element is flexible and is moved between the open switch position and the closed switch position by being flexed.
Claim 7
Dependent Claim
17 words
A switch as claimed in claim 1 in which the component is formed from a single material.
Claim 8
Dependent Claim
42 words
A switch as claimed in claim 1, in which the element is less stable at a point between the open switch position and the closed switch position than it is in each of the open switch position and the closed switch positions.
Claim 9
Dependent Claim
24 words
A switch as claimed in claim 1, in which the element moves between the first and second positions in response to an electrical event.
Claim 10
Dependent Claim
31 words
A switch as claimed in claim 1, in which the component is generally U-shaped, and in which the legs of the U move relative to one another when the component recovers.
Claim 11
Dependent Claim
42 words
A switch as claimed in claim 1, in which the component has a long transverse dimension and a short transverse dimension, and in which, on recovery of the component, a part thereof rotates to a position between the element and a stop.
Claim 12
Dependent Claim
32 words
A switch as claimed in claim 1, in which the component changes its configuration on heating from a configuration in which it is relatively straight to one in which it is I-shaped.
Claim 13
Dependent Claim
18 words
A switch as claimed in claim 1, in which the first contact is affixed to the support member.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-04 | 1994-08-06 | 1995-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-04 | 1998-08-06 | 1999-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-04 | 2002-08-06 | 2003-02-05 | $7700.00 | Window Closed / Lapsed |