US3909569A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inertia switch having movable liquid contact medium retained in reciprocating actuator and engaging helical fixed contact array
Assignee: Individual
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Filing: 1974-07-19
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Granted: 1975-09-30
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Expires: 1994-07-19
Abstract
Abstract A hermetically sealed piston in cylinder type inertia switch employing an electrically insulative piston with mercury seal rings which serve both as bearings and as movable electric switch contacts to engage helically arranged and very closely spaced mercury wetted contacts embedded in and flush with the inner surface of a close fitting electrically insulative cylinder case. Response of the piston to acceleration is spring controlled in acceleration switching applications and is gas metering controlled in velocity change amount switching applications. The fluid engagement between the movable and fixed contacts and the very close axial spacing of the fixed contacts enables the invention to avoid switching error commonly resulting from engagements of compliant type contacts, to virtually avoid calibration error and to be programmed to switch within broad acceleration and velocity change amount ranges.
Inventors
- 👤 W Dale Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:46
CPC Classifications
H; H01; H01H; H01H35/00; H01H35/14; H01H35/141; H01H35/142; G; G01; G01P; G01P15/00; G01P15/02; G01P15/08; G01P15/135; H01H29/00; H01H29/002
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
167 words
An inertia switch comprising a closed casing of electrical insulating material having a hermetically sealed non-oxidizing cylindrical internal chamber, a close fitting piston mounted in said chamber for axial movement in response to acceleration of said case, means defining a circumferentially extending deposit of liquid metal on a restricted portion on the periphery of said piston to constitute an annular bearing surface slidably supporting said piston, and a plurality of axially extending rows of axially spaced electrical contacts fixedly embedded in said casing and having inner surfaces flush with the inner wall of said chamber in axial alignment with said deposit of liquid metaL to be slidably engaged and electrically contacted by said deposit during movement of said piston along said chamber, said rows of said contacts being circumferentially spaced from each other with said contacts of any one said row being uniformly axially offset from said contacts of adjacent said rows to produce a generally helical arrangement of said contacts about the axis of said casing.
Claim 2
Dependent Claim
167 words
An inertia switch comprising a closed casing of electrical insulating material having a hermetically sealed non-oxidizing cylindrical internal chamber, a close fitting piston mounted in said chamber for axial movement in response to acceleration of said case, means defining a circumferentially extending deposit of liquid metal on a restricted portion on the periphery of said piston to constitute an annular bearing surface slidably supporting said piston, and a plurality of axially extending rows of axially spaced electrical contacts fixedly embedded in said casing and having inner surfaces flush with the inner wall of said chamber in axial alignment with said deposit of liquid metaL to be slidably engaged and electrically contacted by said deposit during movement of said piston along said chamber, said rows of said contacts being circumferentially spaced from each other with said contacts of any one said row being uniformly axially offset from said contacts of adjacent said rows to produce a generally helical arrangement of said contacts about the axis of said casing.
Claim 3
Dependent Claim
71 words
The invention defined in claim 1 wherein said close fitting surface is electrically insulative and extends around the entire circumferential periphery of said piston, and said liquid metal deposit constitutes a pool of said liquid metal confined in an endless annular groove in said close fitting surface, meniscally sealing the clearance between said close fitting surface and the inner diameter of said casing, said clearance limited to 0.0002 to 0.0005 inch.
Claim 4
Dependent Claim
54 words
The invention defined in claim 2 further comprising passage means including a restricted orifice for controlling the flow of inert fluid from one side of said piston to the other induced by movement of said piston in said chamber to thereby regulate the rate of response of said piston to acceleration of said case.
Claim 5
Dependent Claim
54 words
The invention of claim 3 further comprising cooperating magnetic means mounted on said case adjacent one end of said chamber for magnetically attracting said piston toward said end of said chamber to establish a minimum acceleration of said case necessary to cause movement of said piston away from said one end of said chamber.
Claim 6
Dependent Claim
32 words
The invention defined in claim 1 further comprising spring means coupled between said piston and an end of said case for controlling movement of said piston relative to acceleration of said case.
Claim 7
Dependent Claim
30 words
A switch as defined in claim 1 further comprising damping means for damping the response of said piston to acceleration of said casing in a direction axially of said chamber.
Claim 8
Dependent Claim
46 words
The invention defined in claim 5 wherein said spring is electrically conductive, with means for connecting a first end of said spring to said deposit and means for connecting the second end of said spring to an electric terminal accessible at the exterior of said casing.
Claim 9
Dependent Claim
17 words
The invention defined in claim 7 wherein said deposit extends only a portion of the entire circumference.
Claim 10
Dependent Claim
38 words
The invention defined in claim 7 wherein at least a portion of said close fitting surface is solid metal and said liquid metal deposit constitutes a puddle of said liquid metal wetting said solid metal close fitting surface.
Claim 11
Dependent Claim
103 words
The invention defined in claim 7 wherein said piston comprises a hollow cup-shaped member of electrical insulating material having said annular bearing surface on its periphery, an electrical conductive member mounted on one end of said cup-shaped member to define an enclosed chamber, and an electrically conductive inertial mass mounted in said enclosed chamber and connected to said first end of said spring, for axial sliding movement between opposite end limits defined by an end wall of said cup-shaped member and an opposite end wall constituted by said conductive member, where said first means constitutes engagement of said mass with said conductive member.
Claim 12
Dependent Claim
144 words
An inertia switch comprising a closed casing of electrical insulating material having a hermetically sealed non-oxidizing cylindrical internal chamber, a plurality of electrical contacts embedded in said casing and having exposed inner surfaces flush with the wall of said chamber and exterior surfaces accessible at the exterior of said casing, an inertial piston of electrical insulating material slidably received in said chamber, said piston having a circumferentially extending groove on its periphery, a pool of mercury confined in said groove and contacting the wall of said chamber to slidably support said piston and to electrically contact said contacts as said piston is displaced along said chamber, electrically conductive spring means coupled between said piston and said casing at one end of said chamber, an electriC terminal on said casing, and means electrically connecting said spring to said terminal and to said pool of mercury.
Claim 13
Dependent Claim
144 words
An inertia switch comprising a closed casing of electrical insulating material having a hermetically sealed non-oxidizing cylindrical internal chamber, a plurality of electrical contacts embedded in said casing and having exposed inner surfaces flush with the wall of said chamber and exterior surfaces accessible at the exterior of said casing, an inertial piston of electrical insulating material slidably received in said chamber, said piston having a circumferentially extending groove on its periphery, a pool of mercury confined in said groove and contacting the wall of said chamber to slidably support said piston and to electrically contact said contacts as said piston is displaced along said chamber, electrically conductive spring means coupled between said piston and said casing at one end of said chamber, an electriC terminal on said casing, and means electrically connecting said spring to said terminal and to said pool of mercury.
Claim 14
Dependent Claim
30 words
A switch as defined in claim 11 further comprising damping means for damping the response of said piston to acceleration of said casing in a direction axially of said chamber.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |