Aeronautics and astronautics – Retarding and restraining devices – Friction brakes
Reexamination Certificate
2000-03-17
2001-09-11
Barefoot, Galen L. (Department: 3644)
Aeronautics and astronautics
Retarding and restraining devices
Friction brakes
C239S265190, C060S226200
Reexamination Certificate
active
06286784
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to airplane thrust reverser control systems, and more particularly to thrust reverser control systems for avoiding uncommanded thrust reverser deployment.
BACKGROUND OF THE INVENTION
Airplane thrust reversers come in a variety of designs depending on the engine manufacturer, the engine configuration, and the propulsion technology being utilized. Thrust reversers for turbofan engines
10
such as the one shown in
FIG. 1
are typically reversed in three ways. Cascade-type thrust reversers are located at an engine's midsection and redirect fan flow air
18
through cascade vanes
16
positioned on the engine periphery. Cascade-type reversers are normally used on high-bypass ratio engines. Target-type thrust reversers, sometimes called clamshell reversers, utilize two doors to block the entire jet efflux. These doors are in the aft portion of the engine and form the rear part of the nacelle. Target reversers are typically used with low-bypass ratio engines. Pivot door thrust reversers are similar to cascade-type thrust reversers except that no cascade vanes are provided. Instead, four doors on the engine nacelle blossom outward to redirect flow.
A cascade-type thrust reverser works as follows. Referring to
FIG. 2
, an engine fan case
12
includes a pair of semi-circular thrust reverser translating sleeves
14
(sometimes called cowls) that are positioned circumferentially on the outside of the fan case
12
and that cover a plurality of cascade vanes
16
(i.e., non-rearwardly facing air vents.) The cascade vanes
16
are positioned between the thrust reverser sleeves
14
and the bypass air flow path
18
. Referring to
FIGS. 2 and 3
, series of blocker doors
20
are mechanically linked to the thrust reverser sleeves
14
via a drag link
22
rotatably connected to an inner wall
24
that surrounds the engine case
26
. In their stowed position, the blocker doors
20
form a portion of the inner wall and are therefore oriented parallel to fan air
18
flow. When the thrust reversers are activated, the thrust reverser sleeves
14
translate aft, causing the blocker doors
20
to rotate into a deployed position in which they block the fan air flow passage. This also causes the cascade vanes
16
to be exposed and the fan air
18
to be redirected out the cascade vanes. The re-direction of fan air
18
in a forward direction works to slow the airplane.
Still referring to
FIG. 3
, the thrust reverser sleeves
14
are operated by one or more hydraulic actuators
28
per engine. The actuators
28
are attached between a stationary torque box
30
and the translating sleeve. The actuators
28
interconnect with each other via a synchronization mechanism, such as a flexible shaft
32
. The synchronization mechanism ensures that the actuators move at the same rate. The torque box
30
also provides structural support for the synchronization mechanism and the cascade vanes
16
. As shown in
FIG. 2
, the torque box is typically formed as a pair of rigid semicircular beams located at the forward end of the fan case
12
(i.e., just forward of the cascade vanes.)
An actuation activation system translates the thrust reverser sleeves
14
from a locked and stowed position to an unlocked and translated position for reverse thrust. Due to significant physical forces present during flight that can work to push the translating sleeve
14
to an open position, current actuation systems include a number of ways of preventing uncommanded translation. For example, it is known to provide actuators that are capable of locking in order to retain the thrust reverser sleeve in the stow position. Or, an electrically-operated synchronization shaft lock
34
may be provided to control synchronization shaft movement. It is also known to provide automatic restow capability in which dedicated system control logic automatically causes the actuators
28
to stow the thrust reverser during detection of rearward movement of the sleeves
14
.
One known auto-restow arrangement is described below with reference to FIG.
4
. In this arrangement, two electric proximity sensors
36
,
38
are mounted to the aft side of the torque box
30
and are facing rearward. Two spring-loaded targets
40
,
42
are affixed to the translating sleeve
14
. The sensors
36
,
38
are targeted to a “normally near” condition (i.e., they are adjusted to expect under normal conditions the return signal from their target to be from a particular pre-defined “near” distance.) One of these sensors
36
is used for locating the position of the translating sleeve. The other sensor
38
is used for sleeve control by indicating an unlocked thrust reverser condition to the actuation activation system.
When the translating sleeve
14
is stowed for normal engine forward thrust, the targets
40
,
42
are sensed by the sensors
36
,
38
and the auto restow control logic is not accessed. If the sleeve moves aft, either powered or unpowered, the targets
40
,
42
move away from the sensors
36
,
38
. This causes the distance between the sensors and the targets to increase and the sensors to trigger. Upon triggering, the sensors
36
,
38
send a signal to the actuation activation system which energizes the auto restow control logic which immediately attempts to restow the thrust reversers. The autorestow system is activated only when both targets are triggered by translation of the sleeve. This is referred to as ‘AND’ logic
44
and is shown in FIG.
7
A.
During normal operations, the sleeve
14
moves relative to the torque box
30
because of aerodynamic loads, vibrations, and relative motion between the engine and nacelle structures. Relative motion, however, can result in the targets being sensed in the “far” condition, which in turn trips one or both sensors
36
,
38
and energizes the auto restow function, even though the sleeve is in fact still in its stowed and locked position.
Another undesirable aspect of this arrangement is that it is difficult and time consuming to position the sensors and target. To ensure proper detection of the target by the sensor, a specific required distance must be present between the sensors
36
,
38
and the targets
40
,
42
. Prior to use, a mechanic must adjust the distance until it is within an acceptable range of values. This is done by using an iterative process, since the proximity sensor and target are covered by the translating sleeve
14
. In particular, a mechanic must repeatedly test and readjust the location of the target until the required distance is obtained. Typically, the mechanic applies clay or other deformable substance to either the target (or the sensor.) The mechanic then closes and reopens the sleeve. The mechanic measures the resulting thickness of clay. Using this information, the mechanic calculates an adjustment to the position of the target. After the adjustment is made and more clay is added, the sleeve is once again closed and reopened. The mechanic again checks the clay thickness to see if the proper distance has been attained. If not, the process is repeated until it is within acceptable limits. As can be appreciated, this is a very labor intensive and cumbersome process.
Thus, a need exists for an improved actuation activation system in which the thrust reverser is automatically restowed. The ideal system would be easy to install and easy to calibrate without requiring labor intensive and time consuming distancing steps. The present invention is directed to fulfilling this need.
SUMMARY OF THE INVENTION
In accordance with aspects of the present invention, an aircraft engine thrust reverser actuation activation system is provided for use with an aircraft thrust reverser system having stowed and extended positions. The system includes at least one locking actuator for moving a thrust reverser translating sleeve. The locking actuator has locked and unlocked states corresponding to the thrust reverser system stowed and extended positions, respectively. The locking actuator includes a slide-by first sensor capable of p
Hardy Brant B.
Hills Gregory S.
Kraft Kurt R.
Sternberger Joe E.
Barefoot Galen L.
The Boeing Company
LandOfFree
Automatic restow system for aircraft thrust reverser does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automatic restow system for aircraft thrust reverser, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic restow system for aircraft thrust reverser will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2482735