Pipe joints or couplings – With means blocking release of holding means – Thread lock
Reexamination Certificate
1998-06-17
2001-09-25
Luu, Teri Pham (Department: 3627)
Pipe joints or couplings
With means blocking release of holding means
Thread lock
C285S086000
Reexamination Certificate
active
06293595
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an anti-rotation locking unit for mechanically and selectively locking two elements against relative rotation thereof.
The invention relates more particularly, but not in a limiting manner, to selective locking of screw connections between two elements, for preventing undesired untightening of such connections. This invention also applies, in a non-limiting manner, to adjustable rods in which a threaded arrangement allows to vary the length of the rod and to secure the length-adjustment which has been made, to clamping collars having a threaded means for adjustable clamping effect of the collar on a clamped element, to pipe couplings using threaded connecting means, especially standardized pipe couplings having a nipple at the end of one of the pipes, intended to be pressed into a flaring at the end of the other pipe under the effect of tightening a captive nut of one of the pipes engaging with a thread formed on the other pipe.
BACKGROUND OF THE INVENTION
Several braking or locking techniques are used at present:
the locking wire technique. This technique, which is much used in the aeronautical field, does not guarantee the mechanical holding together of the assembly. This locking system is more moral than mechanical.
locking techniques using a plastic washer set into a nut, using an elastic or deformed nut, using an elastic washer or using friction. These systems either limit the assembly clearance between the thread of the nipple and the nut, or they increase the torque necessary for loosening. They do not therefore totally guarantee against the risk of the installation becoming loosened during its use.
Most of these techniques cannot be used again after a dismantling.
According to another locking technique known from U.S. Pat. No. 5,083,819, for pipe connections, locking tabs fixed to the nipple resiliently engage the nut. This technique is expensive.
Furthermore, a locking device is known from FR-A-917 287 in which one of the pipes has a thread made beyond splines on which a locking member is slidably mounted. The locking member is biassed by a spring into a locking position in which, in use, said locking member immobilizes the nut carried by the other pipe and engaging said thread. This device is not compatible with the standard couplings since it requires the provision of splines between the thread and the actual piping. The total length of the coupling is modified by this and the total cost is very high. The device according to U.S. Pat. No. 5,188,398 is of the same type but has the additional disadvantage that the splines of the locking member must be strong because they also serve to transmit the tightening torque.
According to U.S. Pat. No. 4,655,482, the nut and the hexagonal conformation of the threaded pipe end are used to rotationally immobilize locking parts which fit over them. The hexagonal conformations of the nut and of the threaded pipe are therefore no longer accessible for the tightening operation. To overcome this, the locking parts have external hexagonal conformations. The radial dimension is increased by the locking parts, which must furthermore transmit the tightening torque.
Thus, most of the known locking devices require an extensive re-designing work of the basic structure comprising the elements to be locked, and that the locking device be an integral part thereof.
SUMMARY OF THE INVENTION
An object of this invention is therefore to provide a locking device which is effective, economical, compact, versatile, and/or compatible with many standards and preexisting structures without substantially modifying the overall size of the apparatus which is equipped therewith.
A further object of this invention is to provide an anti-rotation locking unit which is easily adaptable to preexisting or predesigned basic structures without significantly or even without altering at all the basic structure.
According to the invention, there is provided an anti-rotation locking unit comprising:
a support member having a mounting portion, a lock-support portion and first engagement means;
a locking member having a bearing portion which is movably supported by said lock-support portion of said support member between a locking position and a withdrawn or release position, a coupling formation, and second engagement means, wherein, at least in said locking position of the locking member, said first and second engagement means are mutually engaged so as to prevent rotation of said locking member with respect to said support member; and
a return means mounted operatively between said locking member and said support member for biassing said locking member into said locking position.
The support member is intended or adapted to be made stationary with respect to one of the mutually rotatable elements which are to be selectively locked by the anti-rotation locking unit. The locking unit according to the invention is i.a. suitable to be designed as a separate unit which is ready to be mounted on a basic structure. The mounting consists in securing the support member to one of the mutually rotatable elements of the basic structure, in a location in which, at least in the locking position of the locking member, the locking member coupling formation engages a complementary formation, such as an hexagonal tool-grip formation, provided or preexisting on the other of said two mutually rotatable elements of the basic structure. Thus, the conditions that the basic structure has to fulfil in order to allow adapatation of the anti-rotation locking unit are minimal and, in most cases, correspond to requirements already bearing upon the basic structure for its own operability or compliance with standards.
The locking member is movably mounted onto the support member, and not directly onto said one rotatable element which therefore needs not be modified for this purpose.
The device can be used again after each locking and unlocking sequence.
In the release position, the locking member provides a discoupling between the support member and the complementary coupling formation of said other rotatable element of the basic structure. This can be the result of a discoupling between said first and second engagement means, and/or between the coupling formation of the locking member and the complementary coupling formation of said other element.
It is advantageous that the locking member, when it is in the release position, has a freedom of rotation with respect to the support member. This allows a mounting in which the coupling formation of the locking member and the complementary coupling formation of said other element of the basic structure remain mutually engaged in the release position of the locking member. This is advantageous because the first and second engagement means can be designed for safe reengagement when the locking member moves from the release to the locking position, whereas the coupling formations might be less appropriate therefor.
The engagement of the first and second engagement means can preferably take place in several and even multiple relative angular positions, by choice, of the locking member with respect to the support member. This aids in a safe reengagement in any angular position of the locking member with respect to the support member when the locking member is returned to the locking position from the release position.
If the locking member, when it is in the withdrawn—or release—position, has total freedom of rotation with respect to the support member, the first and second engagement means can consist together of a kind of free wheel allowing the locking member to rotate in the direction of tightening said other element (such as a nut) but not in the direction of loosening it. For this purpose, one of the support and locking members can comprise a set of asymmetrical teeth, and the other one of these members can comprise complementary teeth or simply one or more isolated teeth. The return means allows the teeth of the two members to ride over each other like a ratchet in the direction of tightening the
Barre Bernard
Marc Jean-Pierre
JPB Systeme
Luu Teri Pham
Young & Thompson
LandOfFree
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