Aeronautics and astronautics – Aircraft control
Reexamination Certificate
2003-04-29
2004-03-02
Barefoot, Galen L. (Department: 3644)
Aeronautics and astronautics
Aircraft control
C244S215000, C244S04500R, C244S089000, C244S048000, C074S09900A
Reexamination Certificate
active
06698688
ABSTRACT:
FIELD OF THE INVENTION
The present disclosure relates to apparatus and methods for actuating rotatable members and, more specifically, for actuating rotatable aircraft control surfaces.
BACKGROUND OF THE INVENTION
Many existing commercial and military aircraft include a pressurized fuselage, a wing assembly positioned toward a middle portion of the fuselage, and a tail assembly positioned aft of the wing assembly. The tail assembly typically includes horizontal control surfaces that provide pitch control, and vertical control surfaces that provide yaw control. The tail assembly may be mounted to an unpressurized empennage attached to an aft portion of the fuselage. Alternately, some aircraft are equipped with canard surfaces that are mounted on the fuselage at locations forward of the wing assembly and which provide the desired pitch stability and control. Regardless of the location of the control surface on the aircraft, many existing control surfaces (pitch and yaw) may be actuated by rotating a rotatable member (e.g. a drive shaft). Typically, the rotation of the rotatable member causes a corresponding deflection or rotation of the control surface, thereby providing the desired pitch or yaw control.
A side elevational view of a conventional actuator assembly
20
for actuating a rotatable control surface
22
is shown in FIG.
1
. The actuator assembly
20
includes a longitudinally-extendible actuator
24
that is extendible in a first direction
26
, and retractable in a second direction
28
. The actuator
24
has a first end
30
pivotally coupled at a first point A to a first end
32
of a drive arm
34
. A second end
36
of the drive arm
34
is non-pivotally (e.g. rigidly) coupled to a drive shaft
38
(shown in end view in
FIG. 1
) at a second point B. The drive shaft
38
is, in turn, coupled to the control surface
22
.
As shown in
FIG. 1
, a second end
40
of the actuator
24
is pivotally coupled at a third point C to a first end
44
of a hangar link
42
. A second end
46
of the hangar link
42
is pivotally coupled at a ground point G to a relatively stationary support
48
(e.g. an airframe). The actuator assembly
20
further includes a reaction link
50
having a first end
52
pivotally coupled to the second point B, and a second end
54
pivotally coupled to the third point C. Alternately, for applications that require increased torque, the drive arm
34
may extend beyond the second point B, and the reaction link
50
′ may be pivotally coupled to the second end
36
′ of the elongated drive arm
34
′ at an alternate point B′.
In operation, as the actuator
24
is extended in the first direction
26
, a force is exerted on the drive arm
34
that, coupled with a corresponding force in the reaction link
50
, causes a rotation of the drive shaft
38
, thereby rotating the control surface
22
in a first rotational direction
52
. Similarly, when the actuator
24
is retracted in the second direction
28
, the combination of forces in the drive arm
34
and the reaction link
50
cause the drive shaft
38
, and thus the control surface
22
, to rotate in a second rotational direction
54
. Because the second end
46
of the hangar link
42
is pivotally coupled at the ground point G, the third point C may translate in the first and second directions
26
,
28
during actuation of the actuator
24
. Thus, actuation loads provided by the actuator
24
are close-coupled to local structure through the reaction link
50
, which is conventionally attached to the second point B, or to the alternate point B′ that is co-linear with the first and second pivot points A and B. Similarly, torsional loads are reacted by the hangar link
42
. The actuator assembly
20
shown in
FIG. 1
is of a type commonly-known as a “walking beam” kinematic linkage assembly.
Although desirable results have been achieved using the conventional actuator assembly
20
, continued advances in aircraft technology are placing increased demands on such assemblies. For example, in some advanced aircraft configurations, particularly those being developed for trans-sonic and supersonic flight conditions, it may be desirable to provide relatively large canard surfaces for optimal pitch control, while at the same time reducing the size of the aircraft fuselage cross-section to minimize drag. These factors may tend to increase the load requirements on the actuator assembly, while at the same time increasing the demand for more effective utilization of space within the aircraft. Thus, there is an unmet need to provide actuator assemblies that more fully satisfy the competing demands being presented by continued advances in aircraft technology.
SUMMARY OF THE INVENTION
The present invention is directed to apparatus and methods for actuating rotatable members. Apparatus and methods in accordance with the present invention may advantageously decrease the amount of space occupied by such apparatus in comparison with the prior art. When used in aircraft, the apparatus and methods disclosed herein may therefore provide improved utilization of space within the aircraft.
In one embodiment, an assembly for actuating a rotatable member includes an extendible actuator having a first end and a second end, and a drive member having a first portion pivotally coupled to the second end, and a second portion non-pivotally coupled to the rotatable member. The second portion of the drive member is spaced apart from the first portion. The drive member further includes a third portion spaced apart from the first and second portions in a non-linear orientation. The assembly further includes a reaction link having an anchoring end pivotally coupled to the first end of the extendible actuator, and a driving end pivotally coupled to the third portion of the drive member.
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patent: 2370893 (1945-03-01), Utsch
patent: 2430793 (1947-11-01), Wells
patent: 3874617 (1975-04-01), Johnson
patent: 4121483 (1978-10-01), Sedlock
patent: 4482108 (1984-11-01), Sutton
patent: 4497461 (1985-02-01), Campbell
patent: 4763862 (1988-08-01), Steinhauer et al.
patent: 5722615 (1998-03-01), Bilange et al.
patent: 6371408 (2002-04-01), Halwes
patent: 6450050 (2002-09-01), Luo et al.
patent: 6520717 (2003-02-01), Otto et al.
patent: 6572209 (2003-06-01), Koepff et al.
Barefoot Galen L.
Black Lowe & Graham
The Boeing Company
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