Propeller blade position controller

• US 5,551,649 A
• Filed: 01/18/1994
• Issued: 09/03/1996
• Est. Priority Date: 10/20/1989
• Status: Expired due to Fees

• Current Assignee: Fokker Aircraft, B.V.
• Original Assignee: Fokker Aircraft, B.V.
• Inventors: Kaptein, Dick
• Primary Examiner(s): Barefoot, Galen L.
• Application Number:
  US08/184,752
• Time in Patent Office: 959 Days
• Field of Search: 244/1 N, 244/118.5, 244/129.1, 416/33, 416/34, 416/50, 381/71, 181/206, 364/574, 364/508, 364/474.22, 364/431.01, 364/494, 415/119, 60/39.21, 60/281
• US Class Current: 244/1.00N
• CPC Class Codes: B64C 11/50 Phase synchronisation between multiple propellers
• CPC Class Codes: G10K 11/175 using interference effects; Masking sound

Abstract

System for reducing vibrations in the cabin of an aircraft driven by two or more propellers each having n blades (n being an integer equal or larger than 2) of which the relative phase angle can be adjusted, said system comprising synchrophase means for adjusting said relative phase angle such that a predetermined relative phase angle is maintained. The system furthermore comprises means supplying information about the vibration level at one or more positions within the cabin or thereto related information and for generating a thereto corresponding level signal, and a control unit which in response to said level signal supplies an error signal to the synchrophase means causing the synchrophase means to adjust the blades of the various propellers such that a new relative phase angle is maintained which differs m.(2π/n) radians (m being an integer) from the previous relative phase angle. Each propeller comprises at least one recognizing means attached to one of its propeller blades, the recognizing means being detectable by a sensor in order to establish the absolute position of the various propeller blades.

Claims

1. A system for reducing vibrations in the cabin of an aircraft driven by two or more propellers each having n blades, n being an integer equal to or larger than 2, and having a relative, adjustable phase angle between one and another of a pair of said propellers, said system comprising:

a) a synchrophase system for adjusting said relative phase angle such that a predetermined relative phase angle is maintained;

b) a vibration-level detecter to supply vibration level related information from one or more positions within said cabin, and to generate a corresponding vibration level signal;

c) a control unit for supplying an error signal to said synchrophase system in response to said vibration level said error signal causing said synchrophase means to adjust an initial predetermined relative phase angle to a new predetermined relative phase angle providing a reduced vibration level, said new relative phase angle differing by m.(2π

/n) radians (m being an integer) from said initial predetermined relative phase angle;

d) for each said propeller of said pair of propellers, at least one recognizing mark identifying one propeller blade and distinguising said one propeller blade from other blades on said each propeller; and

e) a respective sensor for detecting each said recognizing mark, said sensor being connected to said control unit to send a blade detection signal to said control unit upon passing of said recognizing mark past each said respective sensor;

whereby said blade detection signal can be used to relate said predetermined relative phase angles to an absolute phase angle between said one propeller blades of said pair of propellers distinguished by one said recognizing mark.

2. A system according to claim 1, which is arranged to carry out an adjustment procedure in order to establish a desired relative phase angle, wherein said vibration level detecting means are arranged to supply information about the actual vibration level to said control unit at successive measuring times after the synchrophase means has shifted the propeller blades to successive relative phase angles of φ

₀ +m.(2π

/n), in which φ

₀ =an initial predetermined relative phase angle set by the synchrophase means and m is an integer ≦

n and wherein said control unit is arranged to store said information about the actual vibration level and to receive said detection signals from each respective sensor in order to establish whether at any of said measuring times the relative phase angle as set is disturbed and, if so, to interrupt measuring said vibration level and to interrupt shifting the propeller blades to said successive relative phase angles and to start a new adjustment procedure.

3. A system according to claim 1, which is arranged to carry out an adjustment procedure in order to establish a desired relative phase angle, wherein said vibration level detecting means are arranged to supply information about the actual vibration level to said control unit at successive measuring times after the synchrophase means has shifted the propeller blades to successive relative phase angles of φ

₀ +m.(2π

/n), in which φ

₀ =an initial predetermined relative phase angle set by the synchrophase means and m is an integer and wherein said control unit is arranged to store said information about the actual vibration level and to average measured vibration level data for each individual phase angle, and is arranged to receive said detection signals from each respective sensor in order to establish whether at any of said measuring times the relative phase angle as set is disturbed and, if so, to interrupt measuring said vibration level and to interrupt shifting the propeller blades to said successive relative phase angles and to restart the adjustment procedure while using vibration level data already collected.

4. A system according to claim 1, wherein said control unit compares said information, which corresponds to an actual vibration value, with a prefixed reference vibration value, determining therefrom an optimum combination between the blades of the various propellers, and supplying a control signal to said synchrophase means in the case of a substantial difference in value between the said reference value and the actual vibration value.

5. A system according to claim 2, wherein if measuring said vibration level and shifting the propeller blades to said successive relative phase angles is not stopped said control unit determines from said information delivered by said vibration level detecting means a combination between the blades of the various propellers causing a minimum vibration value, and supplying a control signal to said synchrophase means to adjust the predetermined relative phase angle to a new relative phase angle corresponding to said minimum vibration value.

6. A system according to claim 3, wherein if measuring said vibration level and shifting the propeller blades to said successive relative phase angles is not stopped said control unit determines from said information delivered by said vibration level detecting means a combination between the blades of the various propellers causing a minimum vibration value, and supplying a control signal to said synchrophase means to adjust the predetermined relative phase angle to a new relative phase angle corresponding to said minimum vibration value.

7. A system according to claim 1, wherein said vibration level detecting means comprises a number of vibration level sensors all supplying vibration level data to said control unit, which analyses said vibration level data according to a predetermined algorithm.

8. A system according to claim 1 wherein each recognizing mark is located on a propeller shaft.

9. A system according to claim 1 wherein each recognizing mark is located on a propeller back plate.

10. A system for controlling the dynamic behavior of the propellers of an an aircraft driven by one or more propellers having at least two propeller blades, said system comprising:

a) a control system for controlling the dynamic behavior of said propeller or propellers independently;

b) for each of said propellers, at least one recognizing mark identifying one propeller blade and distinguising said one propeller blade from other blades on said each propeller; and

e) a respective sensor for detecting each said recognizing mark, said sensor being connected to said control system to send a blade detection signal to said control unit upon passing of said recognizing mark past each said respective sensor;

whereby said blade detection signal can be used to control said propeller or propellers according to the detected position of said recognizably marked blade.