Harmonic force generator for an active vibration control system

• US 20050075210A1
• Filed: 10/01/2003
• Published: 04/07/2005
• Est. Priority Date: 10/01/2003
• Status: Active Grant

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Frederickson, Kirk Charles
• Granted Patent: US 7,958,801 B2
• Time in Patent Office: Days
• US Class Current: 475/346
• CPC Class Codes: B06B 1/16 operating with systems involving rotary unbalanced masses
• CPC Class Codes: B64C 2027/004 using actuators, e.g. active systems
• CPC Class Codes: B64C 27/001 Vibration damping devices
• CPC Class Codes: F03G 3/00 Other motors, e.g. gravity or inertia motors
• CPC Class Codes: F03H 99/00 Subject matter not provided for in other groups of this subclass
• CPC Class Codes: F16F 15/22 Compensation of inertia forces suppression of vibrations of rotating systems by favourable grouping or relative arrangements of the moving members of the system or systems F16F15/20, counterweights F16F15/28; correcting-weights for balancing rotating bodies F16F15/32
• CPC Class Codes: F16F 7/1005 characterised by active control of the mass
• CPC Class Codes: Y10T 74/2109 Balancing for drum, e.g., washing machine or arm-type structure, etc., centrifuge, etc.
• CPC Class Codes: Y10T 74/2121 Flywheel, motion smoothing-type

Abstract

A force generator for an active vibration control (AVC) system provides a mass located upon an inner circular member which is movable within an outer circular member to simultaneously complete one revolution about its axis as it orbits within the outer circular member to compensate for sensed vibrations. A crank mounts the inner circular member and a counterweight. The crank is rotated by a prime mover such as an electric motor. The mass will therefore generate a sinusoidal inertial force in a straight line. Multiple systems are suitably arranged to be used in conjunction with one another to provide a wide range of inertial force outputs.

Claims

1. A force generator comprising:

a first circular member defined about a first axis to define a first inner diameter, said first circular member having a first radius;

an second circular member defined about a second axis to define a second radius, said second radius one-half said first radius, said second circular member movable to simultaneously complete one revolution about said second axis and one orbit around said first axis; and

a mass located at a circumference of said second circular member to generate a vibratory inertial force.

2. The force generator as recited in claim 1, wherein said vibratory inertial force is a sinusoidal inertial force in a straight line.

3. The force generator as recited in claim 1, wherein said path of the mass is two-cusp hypocycloid.

4. The force generator as recited in claim 1, wherein said first circular member comprises a ring gear.

5. The force generator as recited in claim 1, wherein said second circular member comprises a planet gear.

6. The force generator as recited in claim 1, further comprising a crank which mounts said second circular member, said crank rotates about said first axis.

7. The force generator as recited in claim 6, further comprising a motor which drives said crank.

8. The force generator as recited in claim 6, further comprising an opposed circular counter member mounted to said crank.

9. The force generator as recited in claim 1, wherein said opposed circular counter member comprises a planet gear.

10. The force generator as recited in claim 1, further comprising a counter balance for said second circular member.

11. The force generator as recited in claim 1, wherein said first circular member comprises a ring.

12. The force generator as recited in claim 11, wherein said second circular member comprises a wheel which rolls within said ring.

13. A method of force generation for active vibration control comprising the steps of:

(1) defining a circular path about a first axis;

(2) defining a second circular member about a second axis;

(3) locating a mass at a circumference of the second circular member; and

(4) controlling movement of the second circular member about the circular path such that the second circular member simultaneously completes one revolution about the second axis and one orbit around said first axis to generate a vibratory inertial force.

14. A method as recited in claim 13, further comprising the step of:

counterbalancing the second circular member.

15. A method as recited in claim 13, further comprising the step of:

interconnecting the second circular member and a opposed circular counter member, the opposed circular counter member movable about the circular path.

16. A method as recited in claim 13, further comprising the step of:

moving the second circular member at a constant angular velocity.

17. A method as recited in claim 13, further comprising the step of:

(a) interconnecting the second circular member and a counterbalance with a crank; and

(b) rotating the crank about the first axis.

18. A method as recited in claim 13, further comprising the step of:

(5) transmitting the vibratory inertial force of said step (4) to a helicopter fuselage to minimize the sensed vibratory response to forces from a main rotor assembly.