Electrical connectors – With stress relieving means for conductor to terminal joint – Conductor gripped by or entirely within connector housing
Reexamination Certificate
2000-03-06
2002-04-09
Bradley, P. Austin (Department: 2833)
Electrical connectors
With stress relieving means for conductor to terminal joint
Conductor gripped by or entirely within connector housing
C439S459000
Reexamination Certificate
active
06368145
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a plug including a plug body having an axial bore for insertion of a cable at one end of the plug body for connection to electric contact elements arranged at the other end of the plug body, and more particularly to a plug including a strain relief mechanism located at the first end of the plug body and having at least two clamping elements adjustably supported for clamping the cable.
BACKGROUND
In a prior plug, a strain relief mechanism is formed by three annular clamping segments that are joined by screws. When the screws are tightened, an area through which the cable passes is reduced. The annular segments are movably supported on an end of the plug body, and are covered by a cover screwed onto the plug body when the plug is assembled. An o-ring is arranged between the cover and the annular segments. When the cover is screwed on to the plug body, the o-ring is compressed and pressed in the direction of the cable to seal the cable. The cable extends through an axial bore in the plug body up to the contact elements to which it is connected.
The strain relief mechanism can be fitted to cables of different diameters in a simple manner and safely prevents a direct tensile load on the connection between the cable and the electric contact elements.
SUMMARY
In one general aspect, the invention features a plug including a plug body with an axial bore. A cable may be inserted into the plug body at the first end of the plug body and may be connected to contact elements arranged at the second end. A strain relief mechanism positioned at the first end of the plug body has at least two clamping elements adjustably supported for clamping the cable. The plug body includes at least two sliding guides open towards the axial bore and towards the outside, with the clamping elements being movably guided in the sliding guides.
Use of the sliding guides provides a plug that tends to be even simpler and less expensive than known plugs, while also providing improved accessibility to the strain relief mechanism. Through use of the sliding guides, the clamping elements are directly supported in the plug body and not at one of its ends. Furthermore, since the clamping elements are accessible through the sliding guides, which are open to the outside, they can be adjusted for clamping the cable. The sliding guides can be formed in a simple and inexpensive manner as radially inwardly extending openings provided in a wall of the plug body. Side walls of these openings may serve for guiding the clamping elements. The sliding guides permit a highly efficient strain relief mechanism that provides safe clamping of cables having different diameters.
The plug body includes at least one plug inset provided with the contact elements, a plug cap, and a plug sleeve arranged between the plug inset and the plug cap. At least the plug cap and the plug sleeve can be rotated with respect to one another. To realize simple accessibility to the strain relief mechanism, the sliding guides can be formed directly in the plug cap.
To secure the cable against tension directly after insertion, the sliding guides may be arranged adjacent to an insertion opening of the first end of the plug cap. To permit secure coupling to cables having different diameters, the sliding guides may be in the form of longitudinal holes extending transversely to the axial bore beyond the insertion opening, and the clamping elements may have shapes complementary to the longitudinal holes. In this manner, the clamping elements are guided on all sides in the longitudinal holes.
In one implementation, each clamping element has substantially planar side faces extending transversely to the axial bores and end curves connecting the ends of the side faces. This leads to an approximately elongate, oval cross-section for a clamping element of this kind.
Each clamping element may include a protruding edge extending transversely to the cable on a lower side of the clamping element pointing to the cable. When the clamping element approaches a cable, this protruding edge is pressed into the cable's insulation. The cable may be held on both sides by the use of two opposite clamping elements to secure against tension on the contact elements. To enlarge the surface contact between the clamping element and the cable or the cable's insulation, the lower side of the clamping element facing the axial bore may have a concave recess for at least partially accommodating the cable. Since the cables usually have a circular cross section, the recess can also be substantially circular.
The recess may have at least one clamping projection protruding in the direction of the cable on the clamping side facing the cable. When the clamping elements are tightened, this clamping projection is pressed partially in to the insulation of the cable. In one implementation, the clamping projection can be formed as a clamping rail extending in the axial direction. The clamping rail serves both to support the cable and to reduce rotation of the cable.
To prevent a clamping element from falling out of a sliding guide when releasing the clamping elements from one another, at least one clamping element may have an abutment projecting from the clamping side in the axial direction over a side face to the outside. The abutment contacts the insertion opening, such that the clamping element only moves radially to the outside until the abutment contacts the inner rim of the insertion opening. Each of the clamping elements may have such an abutment. The abutments may be arranged such that the insertion opening is fully open when the abutments contact the inner rim of the insertion opening. In some implementations, at least one of the clamping elements may be removable from the clamping element's sliding guide.
To improve movement of the clamping elements in the sliding guides, a guiding projection may project toward the outside from at least one side face of a clamping element. The guiding projection movably engages a corresponding guide groove which extends in the displacement direction of the clamping element.
The appearance of the plug may be improved and a possible risk of injury may be avoided by forming an outer side of the clamping element opposite to the lower side to have a radius of curvature substantially equal to the outer side of the plug cap. In this way, the clamping elements do not protrude with sharp edges, and, instead, are arranged in the sliding guides, depending on the diameter of the cable to be secured, in a flush or countersunk manner.
Although the cable is held partially secure against rotation, as stated above, a rotation of the cable relative to the electric contact elements may, however, still take place if, for example, the plug cap is twisted relative to the plug body. This can be prevented through use of a rotation prevention projection that extends from at least one clamping element substantially in the axial direction. The projection engages in different rotational positions of the plug cap relative to the plug sleeve through interaction with engagement recesses formed in the plug sleeve. By the mutual engagement of the rotation preventing projection and the engagement recess, a further rotation of the plug cap relative to the plug sleeve or an accidental release of both members is prevented.
In one implementation, the engagement recess is formed between walls extending radially outward relative to the axial bore. The walls restrict the rotation of the plug cap relative to the plug sleeve in that the rotation prevention projection abuts one of the walls in the direction of rotation.
To enable multiple relative positions between the plug cap and the plug sleeve, and at the same time to maintain the protection against rotation, multiple engagement recesses can be arranged equidistantly around the circumference of the plug sleeve.
To easily connect the plug sleeve and the plug cap, the plug sleeve may include an end section at least partially provided with an external thread, with the plug cap having an inte
Deschner Helmut
Grimm Theo
Hofmann Gerd
Naumann Reiner
Sauer Dieter
Bradley P. Austin
Ceag Sicherheitstechnik GmbH
Fish & Richardson P.C.
Gilman Alexander
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