Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Having structure to restrict rotation of threaded – mating... – Pawl and ratchet
Patent
1997-05-05
1999-04-27
Wilson, Neill
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Having structure to restrict rotation of threaded, mating...
Pawl and ratchet
411120, 411150, 411327, F16B 3910, F16B 3924, F16B 3932
Patent
active
058972773
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to an obturating device comprising a plug which automatically locks when screwed in thus preventing spontaneous unscrewing.
DESCRIPTION OF THE RELATED ART
In aeronautics, an aircraft engine requires regular maintenance and very rigorous inspection examinations in order to ensure the perfect reliability of the engine during its operation. In order to be able to inspect the internal parts and their possible wear, orifices are provided in the engine casing. During maintenance operations, a plug obturating the orifice is unscrewed and an endoscope can be inserted in order to examine internal cavities and to observe the state of the engine parts. In this way the opening of the casing and the complete dismantling of the engine are avoided.
The commonly used plugs of this type, also called "endoscope plugs" have a thread and they are screwed by means of a torque wrench into the casing which has a corresponding thread.
When the engine is running, its functioning generates vibrations which can cause the loosening of screwed parts and more particularly the loosening of the endoscope plugs.
Various means are of course known to prevent such damage. These means can consist in placing an added part in contact with the plug, before or after tightening. The parts used are of the lock washer type, or of the locking pin or locking wire type.
However, the accessibility of the plugs in an engine can be very bad because pipes and other peripheral devices clutter the space around the casing. Thus the positioning of an additional locking part on a plug requires great dexterity and even luck in order to avoid losing the said part. In certain cases, the plug is accessible only with the help of a long tool, any direct manual access to the plug is even impossible when the plug is in place. Locking systems are also known which could be permanently mounted on the plug. But these locking systems are not totally reliable, especially after several screwing and unscrewing operations.
U.S. Pat. No. 2,997,090 describes a device for locking a threaded rod in any position with respect to a tapped bore, the free end of the said rod forming an adjustable stop. A locking ring surrounding the rod comprises a pin engaged in an axial groove of the rod. This ring, which is thus connected to the rod in rotation, comprises a toothed face. A spring pushes the ring towards a shoulder integral with the bore and comprising complementary teeth. Thus, whatever the position of the rod in the bore may be, the ring locks the rod with respect to the bore. In order to make an adjustment, there is applied to the rod a rotational torque which is sufficient to cause the teeth of the ring to clear the teeth of the shoulder, with the simultaneous and spontaneous compression of the spring. This device would not be suitable for locking a plug because it would make a complete rotation manoeuvre over several turns in order to screw and unscrew the plug very awkward and difficult, particularly if the latter has poor access. Furthermore, this device would eliminate, at least partially, the sensation of tightening the plug, thus giving rise to a serious risk of defective closure of the plug, particularly in the case of poor accessibility.
SUMMARY OF THE INVENTION
The purpose of the invention is to overcome these disadvantages by proposing an obturating device comprising a stop system, opposing any accidental unscrewing under the effect of vibrations produced in particular by an engine such as an aircraft engine, which is directly integrated with the obturating device, and which is not a hindrance or a risk to opening and closing operations, even in the case of poor accessibility.
According to the invention, the obturating device comprising a plug intended to be placed on an orifice or to be removed from it, by screwing and unscrewing respectively, comprising a body carrying a thread and stop means opposing the spontaneous unscrewing of the plug, is characterized in that the said means are locking and unlocking
REFERENCES:
patent: 1082389 (1913-12-01), Armstrong
patent: 2152977 (1939-04-01), Schindel
patent: 2997090 (1961-08-01), Anderson
patent: 3669472 (1972-06-01), Nadsady
patent: 3866878 (1975-02-01), Yamamoto
patent: 4512697 (1985-04-01), Cascini
patent: 4704058 (1987-11-01), Crunwell
patent: 4815276 (1989-03-01), Hansel et al.
patent: 5533849 (1996-07-01), Burdick
Barre Bernard
Marc Jean-Pierre
JPB Systeme
Wilson Neill
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