US3625632A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual servo hydraulic actuator cylinder for pitch control
Assignee: Bell Aerospace Corp
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Filing: 1969-10-13
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Granted: 1971-12-07
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Expires: 1989-10-13
Abstract
Abstract This invention relates to the mounting of a servo hydraulic actuator for cyclic or collective pitch control of the rotor blades on a helicopter. The actuator is constructed with a cylinder barrel mounted on the frame of the helicopter with a coupling having bearing surfaces shaped to correspond to a portion of a sphere having its center substantially displaced from the coupling toward the pitch horn.
Inventors
- 👤 Lesley C Casterline
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:27
CPC Classifications
B; B64; B64C; B64C27/00; B64C27/54
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
211 words
In a helicopter of the type including a frame, rotor blades, and a swashplate connected to the rotor blades, a dual servo hydraulic actuator mounted to introduce cylic or collective pitch by way of the swashplate to the rotor blades of the helicopter which comprises: a. a first connector on the frame of said helicopter, b. a first piston connected to said first connector, a first barrel cooperating with said first piston to produce motion of said barrel relative to the piston upon the introduction of hydraulic fluid into said barrel, d. a second barrel mounted coaxially above said first barrel, e. a second piston cooperating with said second barrel for relative movement therebetween upon the introduction of hydraulic fluid into said second barrel, said second piston being connected at the upper end thereof to the swashplate and said second piston extending through said second barrel and coupled to said first barrel, and f. a second connector on the frame of said helicopter located above said first connector for mounting said second barrel, said second connector having a support surface shaped to correspond to a portion of a sphere the center of which is located in the region of the midpoint of the stroke of the top of the second piston.
Claim 2
Dependent Claim
211 words
In a helicopter of the type including a frame, rotor blades, and a swashplate connected to the rotor blades, a dual servo hydraulic actuator mounted to introduce cylic or collective pitch by way of the swashplate to the rotor blades of the helicopter which comprises: a. a first connector on the frame of said helicopter, b. a first piston connected to said first connector, a first barrel cooperating with said first piston to produce motion of said barrel relative to the piston upon the introduction of hydraulic fluid into said barrel, d. a second barrel mounted coaxially above said first barrel, e. a second piston cooperating with said second barrel for relative movement therebetween upon the introduction of hydraulic fluid into said second barrel, said second piston being connected at the upper end thereof to the swashplate and said second piston extending through said second barrel and coupled to said first barrel, and f. a second connector on the frame of said helicopter located above said first connector for mounting said second barrel, said second connector having a support surface shaped to correspond to a portion of a sphere the center of which is located in the region of the midpoint of the stroke of the top of the second piston.
Claim 3
Dependent Claim
110 words
The combination set forth in claim 1 wherein: said second connector has a center bore through which said second barrel passes of diameter greater than the diameter of the second barrel for accommodation of structural displacement due to loading and to variations within permitted tolerances of the locations of the first and second connectors and for inhibition of vibrations without applying bending forces to the actuator below the said second connector, and further includes structure including valve means and flow channels for selectively introducing hydraulic fluid into said barrels for controlled movement of said first barrel and said second piston relative to said first piston and said second barrel respectively.
Claim 4
Dependent Claim
30 words
The combination set forth in claim 1 in which a control rod connected to said swashplate is provided with a universal coupling to the upper end of said second piston.
Claim 5
Dependent Claim
26 words
The combination as set forth in claim 1 in which two independent valves control flow of hydraulic fluid to said barrels in response to pilot input.
Claim 6
Dependent Claim
73 words
The combination set forth in claim 4 in which said valves are mounted in fixed relation to said first barrel and in which flow channels extend from above and below a piston seal in said first barrel and in which additional flow channels extend from the upper valve through said second piston to portions above and below a piston seal in said second barrel and common actuator means are provided for both valves.
Claim 7
Dependent Claim
101 words
The combination set forth in claim 1 in which valving means responsive to pilot control simultaneously adjusts the flow of said fluid to one of a pair of sets of chambers in which the first set comprises the chamber between the second piston and the second barrel below a piston seal and a chamber between the first piston and the first barrel above a piston seal in which the second set comprises the chamber between the second piston and the second barrel above the piston seal and the chamber between the first piston and the first barrel below the piston seal.
Claim 8
Dependent Claim
114 words
In a control system of the type in which a hydraulic actuator is connected between a helicopter frame and a swashplate and is employed to control the pitch of rotor blades, the improvement comprising: a first piston connected to the helicopter frame; a barrel for the first piston; a second piston connected to the first barrel and to the swashplate; a barrel for the second piston; and a support structure for the second barrel which comprises mating, concentric spherical bearing surfaces on the helicopter frame and the second barrel the center of which is located above the sUrfaces in the region of the midpoint of the stroke of the top of the second piston.
Claim 9
Dependent Claim
114 words
In a control system of the type in which a hydraulic actuator is connected between a helicopter frame and a swashplate and is employed to control the pitch of rotor blades, the improvement comprising: a first piston connected to the helicopter frame; a barrel for the first piston; a second piston connected to the first barrel and to the swashplate; a barrel for the second piston; and a support structure for the second barrel which comprises mating, concentric spherical bearing surfaces on the helicopter frame and the second barrel the center of which is located above the sUrfaces in the region of the midpoint of the stroke of the top of the second piston.
Claim 10
Dependent Claim
60 words
The combination set forth in claim 14 wherein said support structure includes a cup mounted on said frame with a central bore through the bottom thereof and with an internal upfacing support ring and wherein said second barrel has a downfacing ring with the confronting surfaces of said rings being complementary and of configuration to a slice from said sphere.
Claim 11
Dependent Claim
30 words
The combination set forth in claim 8 in which a first bearing insert of shape corresponding with a slice from said sphere is positioned in said cup between said rings.
Claim 12
Dependent Claim
33 words
The combination set forth in claim 9 wherein a second spherical bearing insert is secured for contacting the bottom of said cup with locking means secured to said second barrel below said cup.
Claim 13
Dependent Claim
176 words
A servo hydraulic actuator mounted to introduce cyclic or collective pitch by way of a swashplate to the rotor blades of a helicopter which comprises: a. a first hydraulic cylinder barrel, b. a first piston cooperating with said first barrel for relative movement therebetween upon the introduction of hydraulic fluid into said first barrel, said y first piston being connected at the upper end thereof to the swashplate, c. a connector on the frame of said helicopter and located below said swashplate for support of said first barrel, said connector having a support surface shaped to correspond to a portion of a sphere whose center is located in the region of the midpoint of the stroke of the top of said first piston, d. a second hydraulic cylinder barrel connected to said first hydraulic piston, and e. a second piston cooperating with said first barrel for relative movement therebetween upon the introduction of hydraulic fluid into said second barrel, said second piston being connected at the lower end thereof y to the frame of said helicopter.
Claim 14
Dependent Claim
176 words
A servo hydraulic actuator mounted to introduce cyclic or collective pitch by way of a swashplate to the rotor blades of a helicopter which comprises: a. a first hydraulic cylinder barrel, b. a first piston cooperating with said first barrel for relative movement therebetween upon the introduction of hydraulic fluid into said first barrel, said y first piston being connected at the upper end thereof to the swashplate, c. a connector on the frame of said helicopter and located below said swashplate for support of said first barrel, said connector having a support surface shaped to correspond to a portion of a sphere whose center is located in the region of the midpoint of the stroke of the top of said first piston, d. a second hydraulic cylinder barrel connected to said first hydraulic piston, and e. a second piston cooperating with said first barrel for relative movement therebetween upon the introduction of hydraulic fluid into said second barrel, said second piston being connected at the lower end thereof y to the frame of said helicopter.
Claim 15
Dependent Claim
51 words
The combination set forth in claim 11 wherein said connector includes a cup mounted on said frame with an internal upfacing support surface and wherein said first barrel has a downfacing bearing surface with said surfaces being complementary and of configuration corresponding to a portion of the surface of said sphere.
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) | 1974-12-06 | 1975-06-07 | 1975-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-06 | 1979-06-07 | 1979-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-06 | 1983-06-07 | 1983-12-07 | $7700.00 | Window Closed / Lapsed |