Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Reexamination Certificate
2000-12-06
2002-12-31
Poon, Peter M. (Department: 3643)
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
Reexamination Certificate
active
06499690
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a rotor blade flap drive apparatus that drives a flap provided at a trailing edge of each rotor blade in a helicopter or the like.
2. Background Art
In recent years, demand has increased for commuter helicopters that take off and land at urban heliports. To realize this operation, noise reduction of helicopters is strongly required. As one effective means for accomplishing such a noise reduction strategy, a technique is contemplated wherein a flap is attached to a helicopter rotor blade and drives those flap at a high speed of approximately 30 Hz to 50 Hz in order to improve aerodynamic characteristics of the rotor blade.
As an apparatus for realizing high-speed driving of a flap in this manner, the present applicant has proposed the rotor blade flap drive apparatus of Japanese Patent Application No. 10-076246 (1998). In order to be housed within the blade, an actuator employed by the flap drive apparatus should be small and lightweight, and in the aforementioned rotor blade flap drive apparatus a piezoelectric actuator is used as the actuator therein. Because piezoelectric actuator displacement is very small, in driving the flap, actuator displacement is magnified by means of a displacement magnification mechanism.
FIG. 16
is a plan view showing one example of such a conventional rotor blade flap drive apparatus
1
, and
FIG. 17
is a side view thereof. In the rotor blade flap drive apparatus
1
, an eccentric shaft
3
is employed as a displacement magnification mechanism
2
. Eccentric shaft
3
possesses a first shaft
12
and a second shaft
13
having mutually eccentric axes
10
,
1
, and a bearing
4
which supports the first shaft
12
is fixed relative to the blade. Output portions
6
a
,
7
a
of two actuators
6
,
7
are coupled by way of a coupling member
14
to a bearing
5
which supports the second shaft
13
. Fixed to this eccentric shaft
3
is a swing arm
8
, and a connecting rod
9
, which is, coupled to the tip of this swing arm
8
, is connected to-the flap.
Simultaneous extension/contraction of the two actuators
6
,
7
causes reciprocating angular displacement of the eccentric shaft
3
about the axis
10
of the first shaft
12
, which is supported fixedly relative to the blade, resulting in large lead-lag swing of the swing arm
8
which is fixed to this eccentric shaft
3
. Swing of the swing arm
8
, which is thus made to swing-in a lead and lag direction with large amplitude, is transmitted by way of the connecting rod
9
to the flap, resulting in the flap motion in vertical reciprocating angular displacement fashion.
In order to obtain a large driving force with such a flap drive apparatus
1
, the two actuators
6
,
7
are employed, as has been described above, and the respective actuators
6
,
7
are driven in synchronous fashion. The output portions
6
a
,
7
a
of the two actuators
6
,
7
are fixed together in an integral fashion by the coupling member
14
, and are coupled to the bearing
4
for the second shaft
13
of the eccentric shaft
3
. Accordingly, while there is no Ads problem when the two actuators
6
,
7
are displaced in proper synchronous fashion, even a slight disagreement in synchronization will result in slight distortion at the periphery of the eccentric shaft
3
, causing a large reduction in the displacement magnification factor and resulting in swing instability. Furthermore, it is extremely difficult to control the actuators
6
,
7
, which are displaced at high speed, such that they are synchronized with high precision.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a rotor blade flap drive apparatus having a simple construction and being capable of causing stable swing of a swing arm in a displacement magnification mechanism.
The invention provides a rotor blade flap drive apparatus comprising: a flap attached to a trailing edge of a blade so as to permit vertical angular displacement, and a pair of actuators housed within the blade and having output portions which are displaced in mutually reverse phases. A swing arm has a base portion which forms a side end of the actuator and is coupled to the respective output portions of the pair of actuators so as to be angularly disposed, and has a tip that swings in a lead and lag direction, and which is at a side opposite to the base portion. A connecting rod connects the tip of the swing arm and the flap.
In accordance with the present invention, the two actuators have output portions that are displaced in mutually reverse phase. That is, when one of the actuators is extended the other actuator contracts, and conversely, when one of the actuators contracts the other actuator is extended.
Accordingly, the tip of the swing arm, the base portion of which is coupled to the output portions of two such actuators, will as a result hereof swing in a lead and lag. direction with large amplitude, and the swing of the swing arm will, by way of the connecting rod, cause vertical reciprocating angular displacement of the flap.
With the above-described conventional flap drive apparatus, the two actuators are extended/contracted simultaneously in synchronous fashion and the output portions are fixedly coupled. Therefore, even a slight disagreement in synchronization causes the swing arm to no longer swing smoothly but rather to become unstable. In contrast, in the present invention swing is made to occur such that the output portions of the two actuators are displaced so as to be mutually reverse in phase. Therefore, the swing arm swings about an imaginary central swing axis located centrally between respective output portions. Accordingly, even when the phases of the two actuators are not exactly reverse but are in slight disagreement, the location of the imaginary central axis of swing of the swing arm will simply be displaced slightly and there will be no reduction in displacement magnification factor, permitting automatic adjustment of swing. The swing arm can thus be made to swing stably through employment of a simple structure.
Furthermore, in the conventional method, the angle of the swing arm would be changed in the event that a large centrifugal force caused application of a compressive force on the actuator and slight contraction of the actuator. However, the present invention has the advantage that because the angle of the swing arm will remain unchanged, there is no need to take into account the effect of the magnitude of the centrifugal force on the angle of the swing arm.
Moreover, because in the invention the swing arm is made to swing through use of the difference in phase between the output portions of two actuators (as compared with the conventional structure wherein actuators are simultaneously extended/contracted in synchronous fashion), it is possible to achieve output displacement magnification relative to actuator displacement that are approximately two times those of flap drive apparatuses having conventional structures.
In the invention it is preferable that the apparatus comprises an eccentric shaft in which a first shaft and a second shaft have axes that are mutually parallel and are mutually eccentric in a direction perpendicular to the axial direction, and the shafts are connected end-to-end in the axial direction to form an integral structure. A first support supports the first shaft so as to permit angular displacement, and the first support is coupled to the output portion of a first one of the actuators. A second support supports the second shaft so as to permit angular displacement, and the second support is coupled to the output portion of the second one of the actuators. The swing arm is fixed to a periphery of the eccentric shaft perpendicularly with respect to the eccentric shaft.
In accordance with the present invention, actuator displacement is magnified by the eccentric shaft and the swing arm which is fixed to the eccentric shaft. Because the magnification factor is determined by the ratio between the amount of eccentricity and th
Hongu Tatsuro
Katayama Noriaki
Yamakawa Eiichi
Advanced Technology Institute of Commuter-Helicopter, Ltd.
Jakel Kevin
Poon Peter M.
LandOfFree
Rotor blade flap drive apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rotor blade flap drive apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotor blade flap drive apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2995003