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US4970622A
Expired / Lapsed
US
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Method and apparatus for controlling the operation of an electromagnet
Assignee: Individual
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Filing: 1988-05-02
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Granted: 1990-11-13
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Expires: 2008-05-02
Abstract
Abstract A method and apparatus for controlling the operation of an electromagnet by comparing the frequency of its holding current pulses against a reference frequency and by initiating another energization cycle if a difference exceeding a predetermined value is detected.
Inventors
- 👤 Josef Buchl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:20
CPC Classifications
H; H01; H01H; H01H47/00; H01H47/22; H01H47/32; H01H47/325; F; F01; F01L; F01L9/00; F01L9/20; H01F; H01F7/00; H01F7/06; H01F7/08; H01F7/18; H01F7/1805; F02; F02D; F02D41/00; F02D41/20; H01F7/1844
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
100 words
A method of controlling the engagement in an electromagnet of an armature with a stator, comprising the steps of: energizing said electromagnet with high level current to attract the armature into engagement with the stator; turning off said high level current; feeding to said electromagnet pulses of lower level current cycling between upper and lower limits sufficient to maintain said engagement; comparing the frequency of said pulses with a reference frequency; generating a signal if said pulse frequency differs from said reference frequency by a predetermined value; and reenergizing said electromagnet with high level current in response to said signal.
Claim 2
Independent Claim
100 words
A method of controlling the engagement in an electromagnet of an armature with a stator, comprising the steps of: energizing said electromagnet with high level current to attract the armature into engagement with the stator; turning off said high level current; feeding to said electromagnet pulses of lower level current cycling between upper and lower limits sufficient to maintain said engagement; comparing the frequency of said pulses with a reference frequency; generating a signal if said pulse frequency differs from said reference frequency by a predetermined value; and reenergizing said electromagnet with high level current in response to said signal.
Claim 3
Dependent Claim
20 words
The method of claim 1, wherein said signal is generated if said reference frequency is higher than said pulse frequency.
Claim 4
Dependent Claim
21 words
The method of claim 2, wherein said signal is generated if said reference frequency exceeds said pulse frequency by about 20%.
Claim 5
Independent Claim
121 words
An apparatus for controlling the position of an armature relative to its stator in an electromagnet, comprising: means for selectively energizing said electromagnet with high level current for attracting said armature into engagement with said stator and for thereafter applying to said electromagnet pulses of current cycling between predetermined upper and lower limits below said high level current for maintaining said engagement between said armature and said stator; means for comparing the frequency of said current pulses with a reference frequency; means responsive to a predetermined difference between the frequency of said pulses and said reference frequency for generating a signal; and means for causing said energizing means to reenergize said electromagnet with high level current in response to said signal.
Claim 6
Independent Claim
121 words
An apparatus for controlling the position of an armature relative to its stator in an electromagnet, comprising: means for selectively energizing said electromagnet with high level current for attracting said armature into engagement with said stator and for thereafter applying to said electromagnet pulses of current cycling between predetermined upper and lower limits below said high level current for maintaining said engagement between said armature and said stator; means for comparing the frequency of said current pulses with a reference frequency; means responsive to a predetermined difference between the frequency of said pulses and said reference frequency for generating a signal; and means for causing said energizing means to reenergize said electromagnet with high level current in response to said signal.
Claim 7
Dependent Claim
25 words
The apparatus of claim 4, wherein said energizing means is connected to switch means for connecting said electromagnet to a source of high level current.
Claim 8
Dependent Claim
26 words
The apparatus of claim 5, wherein said switch means comprises a transistor the base of which is connected to the output means of said energizing means.
Claim 9
Dependent Claim
21 words
The apparatus of claim 6, wherein said energizing means renders said transistor conductive when said reference frequency exceeds said pulse frequency.
Claim 10
Dependent Claim
24 words
The apparatus of claim 7, wherein said energizing means renders said transistor conductive when said reference frequency exceeds said measured frequency by about 20%.
Claim 11
Dependent Claim
56 words
The apparatus of claim 4, wherein said means for comparing is adapted to emit a pulse train of a first pulse width when the frequency of said current pulses substantially corresponds to said reference frequency, and a pulse train of a second pulse width when the frequency of said current pulses differs from said reference frequency.
Claim 12
Dependent Claim
47 words
The apparatus of claim 9, wherein said means for comparing is connected to logic means having a first output state in response to said pulse train of said first pulse width and a second output state in response to said pulse train of said second pulse width.
Claim 13
Dependent Claim
13 words
The apparatus of claim 10, wherein said logic means comprises monostable vibrator means.
Claim 14
Dependent Claim
33 words
The apparatus of claim 11, wherein said monostable vibrator means is connected to said energizing means and said energizing means is adapted to reenergize said electromagnet in response to said second output state.
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) | 1993-11-12 | 1994-05-14 | 1994-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-12 | 1998-05-14 | 1998-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-12 | 2002-05-14 | 2002-11-13 | $7700.00 | Window Closed / Lapsed |