Electromagnetic shield for an electrical terminal with integral spring contact arms

An electromagnetic terminal shield includes a shield body formed of sheet metal having a connector opening configured to receive a corresponding mating terminal shield and a cable opening configured to receive a wire cable. The terminal shield also includes a plurality of cantilevered spring arms integrally formed with the shield body having fixed ends attached to the connector opening and free ends disposed within a shield cavity defined by the shield body. A process for manufacturing the electromagnetic terminal shield is also presented.

TECHNICAL FIELD OF THE INVENTION

The invention generally relates to an electromagnetic shield for an electrical terminal, particularly to an electromagnetic shield with spring contact arms that are integrally formed with the electromagnetic shield.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 through 3illustrate an embodiment of an electromagnetic terminal shield, hereinafter referred to as the shield10, that is configured to be connected, for example to a shield conductor of a shielded cable (not shown), and provide electromagnetic shielding to an electrical terminal (not shown) connected to an inner conductor of the shielded cable. The shield10is configured to receive a corresponding mating electromagnetic terminal shield (not shown) within. The shield10includes a shield body12that is formed from a planar sheet of metal, such as a tin pelted copper-based material. The shield body12has a connector opening14that is configured to receive the corresponding mating terminal shield and a cable opening16that is configured to receive the shielded wire cable. The shielded wire cable is preferably terminated by a ferrule (not shown) that is received within the cable opening16. The shield10also includes a plurality of cantilevered spring arms18extending along a longitudinal axis X of the shield body12that is integrally formed with the shield body12and has fixed ends20that are attached to the connector opening14and free ends22that are disposed within a shield cavity24defined by the shield body12.

As best shown inFIG. 3, each spring arm18in the plurality of cantilevered spring arms18is bent toward an inner surface26of the shield body12within the shield cavity24. The free end22of each spring arm18in the plurality of cantilevered spring arms18is in contact with the inner surface26of the shield body12within the shield cavity24.

As best illustrated inFIG. 1, the plurality of cantilevered spring arms18includes a first spring arm18A, a second spring arm18B generally parallel to the first spring arm18A, and a third spring arm18C generally parallel to the second spring arm18B. The free ends22of the first, second and third spring arms18A-18C are interconnected by a cross bar28that is in contact with the inner surface26of the shield body12within the shield cavity24.

As best shown inFIG. 3, each spring arm18in the plurality of cantilevered spring arms18is opposite another spring arm18in the plurality of cantilevered spring arms18.

As shown inFIGS. 1-3, the shield10further includes a longitudinal contact rib30that is embossed in the shield body12and projects from the inner surface26into the shield cavity24.

FIG. 4illustrates the steps of a process100for manufacturing the shield10described above. The process100includes the following steps:

STEP102, FORM A TERMINAL SHIELD PREFORM, includes forming a terminal shield preform from a planar sheet of metal having a plurality of elongate projections extending longitudinally from one end of the terminal shield preform. The preform may be cut from the sheet metal using stamping, blanking, laser cutting, waterjet cutting, or any other sheet metal cutting process known to those skilled in the art;

STEP104, FOLD ELONGATE PROJECTIONS TOWARD THE TERMINAL SHIELD PREFORM, includes folding the plurality of elongate projections toward the terminal shield preform to form a plurality of cantilevered spring arms18. In the illustrated embodiment, the plurality of cantilevered spring arms18includes a first spring arm18A, a second spring arm18B generally parallel to the first spring arm18A, and a third spring arm18C generally parallel to the second spring arm18B. The free ends22of the first, second and third spring arms18A-18C are interconnected by a cross bar28. Other embodiments may include a different configuration of the plurality of cantilevered spring arms18;

STEP106, BEND EACH SPRING ARM TOWARD AN INNER SURFACE, is an optional step that includes folding the plurality of elongate projections toward the terminal shield preform to form a plurality of cantilevered spring arms18. STEP106is preferably performed prior to STEP108; and

STEP108, JOIN DISTAL EDGES OF THE TERMINAL PREFORM TO FORM A SHIELD BODY, includes joining distal edges of the terminal preform by rolling the terminal preform to form a tubular shield body12having a connector opening14configured to receive a corresponding mating terminal shield and a cable opening16configured to receive a wire cable. The plurality of cantilevered spring arms18is integrally formed with the shield body12and has fixed ends20that are attached to the connector opening14and free ends22that are disposed within a shield cavity24defined by the shield body12. Other embodiments may have a shield body that is rectangular, square, or any other desired shape.

STEP110, SPOT WELD A LONGITUDINAL SEAM JOINT, includes spot welding a longitudinal seam joint34of the shield body12near a cable opening16of the shield body12.

Accordingly, an electromagnetic terminal shield10and a process100of manufacturing the shield10is provided. The different spring rates of the first, second and third spring arms18A-18C on each side of the shield10results in six independent and compliant contact points between the shield10and the corresponding mating terminal shield. The shield10provides low engage forces but high normal contact forces to provide easy connection and high connection performance. The spring arms18contact the shield body12at the front and near the rear of the shield body12, thereby providing improves flow of energy in the shield10and optimal electromagnetic compliance (EMC) performance.

The shield10provides three different spring rates as the mating electromagnetic terminal shield is engaged with the shield10. The three spring rates are provided by 1) a cantilevered spring arm18, 2) a spring arm18forming a simply supported beam once the free end22of the spring arm18engages the inner surface26of the shield body12, and 3) the radial spring of the shield body12itself. As the mating electromagnetic terminal shield is inserted into the shield body12, a first spring rate is provided when the mating electromagnetic terminal shield engages the spring arm18when the free end22is away from the inside surface of the shield10. This provides a lower initial engagement force. A second spring rate is provided when the free end22of the spring arm18engages the inner surface26it becomes a simply supported beam. This provides a higher normal force once the initial alignment is mostly completed and the engagement force is mainly due to friction. The third spring rate is provided by the radial hoop shape of the shield10itself and the axial location of a spot weld32on the seam joint34of the shield body12near the cable opening16. This allows for greater tolerance in the connector opening14. A smaller connector opening14provides more interference with the mating electromagnetic terminal shield and a results in a higher engagement force. Before the engagement force gets too high, the shield body12will flex and the seam joint34will open instead.

The contact rib30provides stabilization of the shield10and improved normal force. Forming the spring arms18by folding projection back into the shield cavity24of the shield body12eliminates openings in the shield body12that improves EMC performance and increases contact protection.

While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to configure a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely prototypical embodiments.

Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the following claims, along with the full scope of equivalents to which such claims are entitled.

Additionally, while terms of ordinance or orientation may be used herein these elements should not be limited by these terms. All terms of ordinance or orientation, unless stated otherwise, are used for purposes distinguishing one element from another, and do not denote any particular order, order of operations, direction or orientation unless stated otherwise.