US4533296A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pitch control system for variable pitch propeller
Assignee: RTX Corp
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Filing: 1983-11-07
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Granted: 1985-08-06
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Expires: 2003-11-07
Abstract
Abstract A propeller pitch control system having a mechanical low pitch stop which includes an electrical backup therefor. The backup comprises an electrically operatable means (245) to effect blade pitch adjustment toward feather under conditions of failure of the low pitch stop indicated by propeller operation at pitch angles in the range of beta operation, but power settings in the range of normal engine speed governor pitch control. Such operating conditions actuate a pair of switches (190 and 195) connecting the means (245) to a voltage source to increase blade pitch toward feather, thereby preventing overspeed operation of the propeller.
Inventors
- 👤 Jerome G. Duchesneau
- 👤 Robert A. Schwartz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:17
CPC Classifications
B; B64; B64C; B64C11/00; B64C11/30; B64C11/38; B64C11/40
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
205 words
A pitch control system for variable pitch propeller powered by an engine, said pitch control system including means for controlling blade pitch in response to the output power of said engine being in a first range corresponding to a first range of blade pitch angle settings greater than a predetermined low pitch angle; beta means for controlling blade pitch in a second range of blade pitch angle settings less than said low pitch angle; and a mechanical low pitch stop for preventing control of blade pitch within said second range by other than said beta means, said system being characterized by an electrically operated backup for said mechanical low pitch stop, said backup comprising: a voltage source; a first switch actuatable by adjustment of blade pitch to angles less than said low pitch angle; a second switch actuatable by adjustment of engine power to levels within said first range thereof; and electrically operable means for adjusting the pitch of said propeller blades, said electrically operable pitch adjusting means being adapted for connection to a voltage source and actuation thereby for driving said blades toward feather by actuation of said first and second switching means under conditions of a malfunction of said mechanical low pitch stop.
Claim 2
Dependent Claim
205 words
A pitch control system for variable pitch propeller powered by an engine, said pitch control system including means for controlling blade pitch in response to the output power of said engine being in a first range corresponding to a first range of blade pitch angle settings greater than a predetermined low pitch angle; beta means for controlling blade pitch in a second range of blade pitch angle settings less than said low pitch angle; and a mechanical low pitch stop for preventing control of blade pitch within said second range by other than said beta means, said system being characterized by an electrically operated backup for said mechanical low pitch stop, said backup comprising: a voltage source; a first switch actuatable by adjustment of blade pitch to angles less than said low pitch angle; a second switch actuatable by adjustment of engine power to levels within said first range thereof; and electrically operable means for adjusting the pitch of said propeller blades, said electrically operable pitch adjusting means being adapted for connection to a voltage source and actuation thereby for driving said blades toward feather by actuation of said first and second switching means under conditions of a malfunction of said mechanical low pitch stop.
Claim 3
Dependent Claim
17 words
The pitch control system of claim 1 characterized by said first and second switches being serially connected.
Claim 4
Dependent Claim
45 words
The pitch control system of claim 1 characterized by an hydraulic actuator connected to said blades for driving said blades in the adjustment of pitch thereof, said electrically operated pitch adjusting means comprising an electrically operated valve for controlling the fluid pressurization of said actuator.
Claim 5
Dependent Claim
35 words
The pitch control system of claim 3 characterized by said electrically operated valve connecting said hydraulic actuator to drain, said valve when actuated, causing a draining of said actuator for driving said blades toward feather.
Claim 6
Dependent Claim
71 words
The pitch control system of claim 1 characterized by: first means, said first means applying said voltage source directly to one of said switches, thereby simulating actuation of the other of said switches for the testing said one switch without influence of said other switch; and second means, said second means short circuiting said one switch, thereby simulating actuation thereof for testing said other switch without influence of said one switch.
Claim 7
Dependent Claim
46 words
The pitch control system of claim 5 characterized by: said first means comprising a third switch connected between said voltage source and a point on said circuit between said first and second switches; and said second means comprising a fourth switch connected across said second switch.
Claim 8
Dependent Claim
44 words
The pitch control system of claim 1 characterized by said third and fourth switches comprising a single conductor connected to said point on said circuit between said first and second switches and movable connection with said voltage source and connection across said second switch.
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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) | 1988-08-05 | 1989-02-04 | 1989-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-05 | 1993-02-04 | 1993-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-05 | 1997-02-04 | 1997-08-06 | $7700.00 | Window Closed / Lapsed |