US3916264A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Time delay apparatus
Assignee: Texas Instruments Inc
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Filing: 1974-07-01
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Granted: 1975-10-28
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Expires: 1994-07-01
Abstract
Abstract Apparatus for reducing the energization of an electrical load after a preselected time delay. A first self-heating positive temperature coefficient resistor having a relatively low initial resistance which increases abruptly as its temperature rises above a given level is interconnected to an electrical power source thereby rapidly to heat it above the given level. A second self-heating positive temperature coefficient resistor having a relatively low initial resistance which increases abruptly as its temperature rises above a given level is interconnected in series with an electrical load across an electrical power source. Both self-heating resistors are secured to heat conductive means so that after these resistors are initially energized they both self-heat with heat being transferred from the first to the second resistor thereby to accelerate the heating of the latter. The conductive means includes an adjustable heat-transfer path between the resistors whereby the delay period between initial energization of the resistors and the time the second resistor''s temperature rises above its given level to effect reduced energization of the load may be varied. Also disclosed is apparatus in which a third self-heating positive temperature coefficient resistor is positioned in heat-exchange relationship with the second self-heating resistor and which includes means for independently connecting the first and/or third resistors to a power so that any of three selected time delay periods may be obtained.
Inventors
- 👤 Peter G Berg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:55
CPC Classifications
H; H01; H01H; H01H43/00; H01H43/30; H01H43/308; H02; H02H; H02H5/00; H02H5/04; H02H5/042
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
206 words
Apparatus for reducing the energization of an electrical load after a preselected time delay comprising: a first self-heating positive temperature coefficient resistor having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; means for interconnecting said resistor to an electrical power source thereby rapidly to heat it above said given level; a second self-heating positive temperature coefficient resistor having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; means for interconnecting said second self-heating resistor in series with an electrical load across an electrical power source; and heat conductive metal plate means having said self-heating resistors secured in spaced relation to each other adjacent respective opposite ends of said heat conductive means whereby after said resistors are initially energized they both selfheat with heat being transferred from the first to the second resistor thereby to accelerate the heating of the latter, said conductive means having notches of selected proportions intermediate said resistors providing a selected heat-transfer path between said resistors whereby the delay period between initial energization of the resistors and the time the second resistor''s temperature rises above its given level to effect reduced energization of the load is selectively predetermined.
Claim 2
Dependent Claim
206 words
Apparatus for reducing the energization of an electrical load after a preselected time delay comprising: a first self-heating positive temperature coefficient resistor having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; means for interconnecting said resistor to an electrical power source thereby rapidly to heat it above said given level; a second self-heating positive temperature coefficient resistor having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; means for interconnecting said second self-heating resistor in series with an electrical load across an electrical power source; and heat conductive metal plate means having said self-heating resistors secured in spaced relation to each other adjacent respective opposite ends of said heat conductive means whereby after said resistors are initially energized they both selfheat with heat being transferred from the first to the second resistor thereby to accelerate the heating of the latter, said conductive means having notches of selected proportions intermediate said resistors providing a selected heat-transfer path between said resistors whereby the delay period between initial energization of the resistors and the time the second resistor''s temperature rises above its given level to effect reduced energization of the load is selectively predetermined.
Claim 3
Dependent Claim
24 words
Apparatus as set forth in claim 1 in which the electrical load is the actuating coil of an electromagnetic device having a movable armature.
Claim 4
Dependent Claim
21 words
Apparatus as set forth in claim 2 wherein the electrical load is the coil of a solenoid-actuated valve or the like.
Claim 5
Dependent Claim
18 words
Apparatus as set forth in claim 2 wherein the electrical load is the coil of an electrical relay.
Claim 6
Dependent Claim
77 words
Apparatus as set forth in claim 2 wherein the maximum rated steady-state current of said devIce is substantially less than that which is carried by said coil during initial periods of energization and corresponds to said reduced energization effected by said heating of said second resistor and wherein said notch in said conductive means is proportioned to assure heating of said second resistor to its given level within a selected time to avoid overheating of said device.
Claim 7
Dependent Claim
94 words
Apparatus as set forth in claim 2 which further includes a resistor of substantially fixed resistance shunt-connected with said second resistor, the resistance of said second self-heating resistor being not substantially more than that of the fixed resistor at temperatures below its given level but substantially greater than that of the fixed resistor at temperatures above its given level whereby after initial energization of said load the power supplied to said load decreases as a function of time to a predetermined lower level as the temperature and resistance of said second self-heating resistor increase.
Claim 8
Dependent Claim
67 words
Apparatus as set forth in claim 6 wherein the combined resistance of shunt-connected fixed and second self-heating resistor at the increased temperature to which the latter resistor is heated is such that the current supplied to the load is substantially less than that initially supplied to the load and is of a value not greatly in excess of the minimum current required to hold in the armature.
Claim 9
Dependent Claim
198 words
Apparatus for reducing the energization of an electrical load after a preselected time delay comprising: a first self-heating positive temperature coefficient resistor having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; a second self-heating positive temperature coefficient resistor positioned in heat-exchange relationship with said first resistor and having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; means for interconnecting said second self-heating resistor in series with an electrical load across an electrical power source; a third self-heating positive temperature coefficient resistor positioned in heat-exchange relationship with said second resistor and having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; and means for independently interconnecting said first and third self-heating resistors across an electrical power source substantially concurrently with the interconnection of the second resistor and load across its electrical power source whereby any of three time delay periods for reducing the energization of the load may be obtained by so energizing the first or third or the first and third self-heating resistors simultaneously with the energization of the second self-heating resistor and the load.
Claim 10
Dependent Claim
198 words
Apparatus for reducing the energization of an electrical load after a preselected time delay comprising: a first self-heating positive temperature coefficient resistor having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; a second self-heating positive temperature coefficient resistor positioned in heat-exchange relationship with said first resistor and having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; means for interconnecting said second self-heating resistor in series with an electrical load across an electrical power source; a third self-heating positive temperature coefficient resistor positioned in heat-exchange relationship with said second resistor and having a relatively low initial resistance which increases abruptly as its temperature rises above a given level; and means for independently interconnecting said first and third self-heating resistors across an electrical power source substantially concurrently with the interconnection of the second resistor and load across its electrical power source whereby any of three time delay periods for reducing the energization of the load may be obtained by so energizing the first or third or the first and third self-heating resistors simultaneously with the energization of the second self-heating resistor and the load.
Claim 11
Dependent Claim
94 words
Apparatus as set forth in claim 8 which further includes a resistor of substantially fixed resistance shunt-connected with said second self-heating resistor, the resistance of said second self-heating resistor being not substantially more than that of the fixed resistor at temperatures below its given level but substantially greater than that of the fixed resistor at temperatures above its given level whereby after initial energization of said load the power supplied to said load decreases as a function of time to a predetermined lower level as the temperature and resistance of said self-heating resistor increase.
Claim 12
Dependent Claim
22 words
Apparatus as set forth in claim 9 in which all the electrical power sources are constituted by a single common power source.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |