Power plants – Reaction motor – Interrelated reaction motors
Patent
1997-05-22
1999-09-21
Freay, Charles G.
Power plants
Reaction motor
Interrelated reaction motors
23926529, 244110B, F02K 302
Patent
active
059539046
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a lock for an engine thrust reverser.
Aero jet engines are commonly provided with a thrust reverser system comprising a number of doors in the engine housing which are normally kept closed and do not impede the rearward flow of jet gases, but which are openable to direct at least a part of the jet gas flow forwards to generate a reverse thrust, aircraft braking action. For reasons of safety, operation of a thrust reverser system is tightly controlled and locks are provided to hold the doors in their closed position until the need for reverse thrust is confirmed. In some applications, for example, when these locks are provided as a back-up to primary locks for extra safety, they will not normally be loaded. However, if they do become loaded because of a system failure, it is critical that they should not be operated to allow the doors to open.
In these circumstances, it has been proposed that the opening load applied to each back-up lock should be transferred to a lock release mechanism so as to actively impede or prevent release of the back-up lock. The proposed lock release mechanism takes the form of a solenoid with a spring-loaded plunger that cooperates with a ratchet formation on the back-up lock, the back-up lock being a pivoted latch member mounted so that the ratchet formation displaces the plunger against its spring loading when the latch member is rotated to a door closed position, and the return spring action of the plunger causes it to automatically engage an abutment shoulder of the ratchet formation to hold the latch member in the door closed position. Any opening load applied to the latch member by the door is then applied through the abutment shoulder to one side of the plunger and reacts against a fixed abutment on the opposite side of the plunger so that the end of the plunger is trapped between the abutment shoulder and the fixed abutment with sufficient force to resist axial movement of the plunger by energisation of the solenoid.
A problem with this proposed lock release mechanism is that it is vulnerable to damage by the door opening load applied laterally to the plunger of the solenoid so that it no longer works freely in the solenoid. This represents a serious shortcoming in such a safety-critical assembly.
An object of the present invention is to provide an improved lock for an engine thrust reverser, in particular, a lock in which the aforesaid problem is mitigated.
According to one aspect, the invention consists in a lock for an engine thrust reverser comprising a latch member adapted to cooperate with a thrust reverser door to keep it closed, an actuator with a plunger that moves longitudinally to cooperate with the latch member to hold it against movement that would allow the door to open, and a sleeve member located longitudinally on the plunger so that opposite lateral sides thereof are engaged between the latch member and a fixed abutment, whereby it is restrained against longitudinal movement by a door opening load applied to the latch member, said sleeve having a lateral clearance with the plunger so that the plunger is substantially isolated from the forces acting laterally on the sleeve.
The latch member may be a pivoted latch member and the actuator may be a solenoid-operated actuator with a spring-loaded plunger, as in the aforesaid known lock release mechanism. However, instead of the end of the plunger being engaged by an abutment shoulder of the latch member on one side and a fixed abutment on the other side, the abutment shoulder and fixed abutment engage opposite sides of the sleeve member on the plunger, and any consequential lateral movement of the sleeve member is accommodated by its lateral clearance with the plunger and is not transferred to the plunger. However, the longitudinal location of the sleeve member on the plunger serves to lock the two together longitudinally for normal engagement and disengagement with the latch member.
According to another aspect, the invention consists in a lock for an engine thrust reverser comprising
REFERENCES:
patent: 5735557 (1998-04-01), Harvey
Dowty Boulton Paul Limited
Freay Charles G.
Ram, D. Sc. Michael J.
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