Patent US3793567A successfully refreshed from Google Patents.
US3793567A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Safety interlock circuit
Assignee: Unisys Corp
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Filing: 1972-07-25
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Granted: 1974-02-19
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Expires: 1992-07-25
Abstract
Abstract A safety interlock circuit suitable for preventing the operation of a machine with an interlock is described. The safety interlock circuit comprises an interlock switch connected to a start/stop manual/relay operated switch. When the interlock switch is in a non-interlock state, closure of the start/stop manual/relay switch allows the machine to operate normally. When the interlock switch is in an interlock state, the machine cannot be energized. Moreover, closure of the start/stop manual/relay switch when the interlock switch is in an interlock state merely energizes the relay portion of the start/stop manual/relay switch causing it to reopen.
Inventors
- 👤 G Hotte
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 16:29
CPC Classifications
H; H02; H02H; H02H11/00; F; F16; F16P; F16P3/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
206 words
A safety interlock circuit for preventing the operation of a machine with an interlock comprising: an interlock switch adapted to change position from a noninterlock position to an interlock position when an interlock occurs in the machine incorporating said interlock switch; a manual/relay start/stop switch including: a relay coil connected so as to be in series with said interlock switch when said interlock switch is in its interlock position so as to allow current to flow through said relay coil when said interlock switch is in said interlock position; and, a first set of contacts adapted to be manually closed, and opeNed by current flowing through said relay coil, said first set of contacts connected so as to be in series with said interlock switch when said interlock switch is in its noninterlock position; and, control means for controlling the operation of said machine, said control means being power energizable and connected in series with said first set of contacts of said manual/relay start/stop switch and said interlock switch when said interlock switch is in its non-interlock position, said control means adapted to allow power to flow to said machine when it is energized and prevent power from flowing to said machine when it is unenergized.
Claim 2
Dependent Claim
206 words
A safety interlock circuit for preventing the operation of a machine with an interlock comprising: an interlock switch adapted to change position from a noninterlock position to an interlock position when an interlock occurs in the machine incorporating said interlock switch; a manual/relay start/stop switch including: a relay coil connected so as to be in series with said interlock switch when said interlock switch is in its interlock position so as to allow current to flow through said relay coil when said interlock switch is in said interlock position; and, a first set of contacts adapted to be manually closed, and opeNed by current flowing through said relay coil, said first set of contacts connected so as to be in series with said interlock switch when said interlock switch is in its noninterlock position; and, control means for controlling the operation of said machine, said control means being power energizable and connected in series with said first set of contacts of said manual/relay start/stop switch and said interlock switch when said interlock switch is in its non-interlock position, said control means adapted to allow power to flow to said machine when it is energized and prevent power from flowing to said machine when it is unenergized.
Claim 3
Dependent Claim
59 words
A safety interlock circuit as claimed in claim 1 wherein said manual/relay start/stop switch includes a second set of contacts adapted to be manually closed, and opened by energization of said relay coil, said second set of contacts being connected in series with said relay coil and said interlock switch when said interlock switch is in its interlock position.
Claim 4
Dependent Claim
67 words
A safety interlock circuit as claimed in claim 2 wherein said control means comprises a power relay having a coil connected in series with said first set of contacts and said interlock switch wnen said interlock switch is in its non-interlock position, and power contacts connected between said machine and its source of power, said power contacts being closed when said coil has current flowing through it.
Claim 5
Dependent Claim
67 words
A safety interlock circuit as claimed in claim 3 including a cam operated switch connected in series with the relay coil of said manual/relay start/stop switch so as to allow power to flow to said relay coil when said cam is in a predetermined position, said cam operated switch being rotated by a motor, said motor being energized when the contacts of said power relay are closed.
References Cited (Backward Citations)
US3056905A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-18 | 1977-08-20 | 1978-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-18 | 1981-08-20 | 1982-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-18 | 1985-08-20 | 1986-02-19 | $7700.00 | Window Closed / Lapsed |