Coaxial Plug-Type Inner Conductor Connection

The present invention refers to a coaxial plug-type inner conductor connection, and in particular to an inner conductor connection with a rigid metallic socket and a plug which is insertable into the socket and includes a radially resilient forward portion of reduced outer diameter which ends at an annular shoulder defining a stop for the front or leading end face of the socket.

The quality of a coaxial plug connection depends primarily on the construction of the plug-type inner conductor connection. The most common plug-type connection for the inner conductor combines the use of a resilient socket and a rigid plug. However, the combination of a rigid socket with a radially resilient plug is also known. Both constructions attempt a contact at the front end face or at least in the area near the front end face of the socket in order to prevent an undesired lengthening of the electric path.

German publication No. DE-GM 72 11 401 describes a coaxial plug-type inner conductor connection in which a rigid socket cooperates with a radially resilient plug of hollow cylindrical design and made of resilient bronze. The plug is axially slotted beyond the contact point and is bent up in barrel-shaped manner so that the outer diameter of the plug--after being inserted into the socket--is reduced to a value required for the wave impedance and simultaneously attains a contacting primarily in the area of the inner end face of the socket.

It is further known to provide a massive plug insertable into a rigid socket and including a groove or the like at its outer surface for receiving a spring contact ring.

Both these constructions have proven to be insufficient when high precision of the plug connection is demanded because the plug could not accurately be centered in the socket and the resiliency of the plug proved to be unsatisfactory.

It is thus an object of the present invention to provide an improved coaxial plug-type inner conductor connection obviating the afore-stated drawbacks.

This object and others which will become apparent hereinafter is attained in accordance with the present invention by surrounding the forward portion of the plug with a contact cap of resilient material and including a base connected to the opposing end face of the forward portion and a wall which is slotted in axial direction and increasingly expands radially in direction toward the annular shoulder.

Through the provision of such a contact cap surrounding the forward portion of the plug, the plug can be a simple turned member which can be manufactured with high accuracy and does not have to be made of resilient material For the contact cap, on the other hand, the best suited resilient material can be selected and the springiness or resiliency can be adapted in an optimum manner to the respective application. The plug connection shows superior mechanical stability and superior electric properties.

Suitably, the wall of the contact cap is so shaped that its greatest diameter is located at or near the edge facing the annular shoulder in order to keep the electric path as short as possible.

According to another feature of the present invention, the wall of the contact cap is axially slotted to provide spring plates which may be twisted by a small angle about their respective longitudinal axis. Instead of being twisted in this manner, the spring plates may also be arched transversely to their respective longitudinal axis. By shaping the spring plates in this manner, a notch effect is created resulting between the inner end face of the socket and the circumferential area of the plug lying within the same radial plane in a contact of very low impedance and even distribution about the circumference.

The above and other objects, features and advantages of the present invention will now be described in more detail with reference to the accompanying drawing in which:

FIG. 1 is a schematically simplified longitudinal section of a first embodiment of a plug-type inner conductor connection in accordance with the present invention, with the inner conductor being in unplugged position;

FIG. 2 is a longitudinal section of the plug-type inner conductor connection of FIG. 1, with the inner conductor being in plugged position;

FIG. 3 is a cross sectional view of the inner conductor plug taken along the line A-A in FIG. 1 and illustrating the forward portion of the plug provided with a spring plate arrangement;

FIG. 4 is a cross sectional view of the inner conductor similar to FIG. 3 and illustrating a modified spring plate arrangement;

FIG. 5 is a schematically simplified longitudinal section of a second embodiment of a plug-type inner conductor connection in accordance with the present invention, with the inner conductor being in unplugged position;

FIG. 6 is a schematically simplified longitudinal section of a third embodiment of a plug-type inner conductor connection in accordance with the present invention, with the inner conductor being in unplugged position; and

FIG. 7 is a cross sectional view of the inner conductor plug as illustrated in FIG. 6.

Referring firstly to FIGS. 1 and 2, there is illustrated a plug-type inner conductor connection with a hollow cylindrical socket 1 and a solid cylindrical plug 2. The plug 2 has an outer diameter which corresponds to the outer diameter of the socket 1, and includes a forward portion 2a of reduced diameter by which the plug 2 is inserted into the socket 2 to attain the plugged connection. Defined at the junction of the plug 2 with the forward portion 2a is an annular shoulder or step 3 which provides a stop for the annular end face 1a of the socket 1 when the plug 2 is inserted into the socket 1.

Placed over the forward portion 2a of the plug 2 is a contact cap which is generally designated by reference numeral 4 and realizes a contact of the plug 2 with the socket 1. The contact cap 4 has a base 4a which is fixedly attached to the forward portion 2a of the plug 2 via a rivet 5 and is connected to a wall 4c extending toward the annular shoulder 3. In order to facilitate insertion of the plug 2 into the socket, the base 4a is provided with rounded edges 4b at the junction to the wall 4c.

Extending from its rearward edge facing the annular shoulder 3 of the plug 2, the wall 4c s provided with a plurality of axial slots along a major part of its length so as to define a plurality of spring plates or spring lamella 4d of radial resiliency.

As shown in FIG. 3 which is a cross sectional view of the inner conductor plug taken along A-A in FIG. 1, the plates 4d are twisted about their respective longitudinal axis by a small angle. The degree of twist is dependent on the width of the plates 4d and is selected in such a manner that the contact cap 4 in unplugged state has an outer diameter which increases in direction toward the annular shoulder 3 of the socket 2. As illustrated in FIG. 1, the increase of the outer diameter of the contact cap 4 is such that its greatest value is at or in the area of the rearward edge of the contact cap 4 opposing the annular shoulder 3 and clearly exceeds the inner diameter of the socket 1. Suitably, the contact cap 4 is made of resilient material such as e.g. bronze so that by inserting the plug 2 into the socket 1 as shown in FIG. 2, the plates 4d intimately bear against the inside surface of the socket 1 so as to attain an inner conductor connection of plug 2 and socket 1 at very low contact resistance which is also evenly distributed over the circumference of the plug-type connection.

Instead of being twisted as shown in FIG. 3, the plates 4d may also be provided in semicircular shape--as illustrated in FIG. 4--by bending or arching the plates 4d transverse to the longitudinal axis thereof so that each spring plate 4d defines a longitudinal fold which extends parallel to the plug axis.

Advantageously, the contact cap 4 may be manufactured by shaping a respective sheet metal blank in non-cutting manner e.g. by deep-drawing. The plates 4d are then provided by suitably slotting the sheet metal and twisting or arching the same in order to accomplish either of the configurations as shown in FIGS. 3 and 4.

The contact cap 4 may, however, also be a turned member as shown e.g. in FIG. 5 which illustrates a longitudinal section of a second embodiment of a plug-type inner conductor connection in accordance with the invention, with the forward section 2a of the plug 2 being enclosed by contact cap 54. The base 54a of the contact cap 54 is connected to the forward section 2a by a bolt 55. At the junction of the base 54a with the wall 54c, the contact cap 54 is provided with a bevelled edge 54b to facilitate insertion of the plug 2 into the socket 1 and to ensure centered positioning thereof within the socket 1.

Turning now to FIGS. 6 and 7, there is shown a third embodiment of a plug-type inner conductor connection in accordance with the present invention which differs from the previously described embodiments only by the design of the contact cap. Accordingly, a contact cap generally designated by reference numeral 64 includes a base 64a which is connected to the forward portion 2a of the plug 2 by a rivet 5 and includes a rounded edge 64b for facilitating insertion thereof into the socket 1. In contrast to the previously described embodiments, the contact cap 64 is provided with a non-slotted wall 64d which--as shown in FIG. 7 attains its radial resiliency through corrugation about its circumference so as to be of star-like shape in a cross sectional view. FIG. 6 shows that the crown height of the corrugation as viewed from the rounded edge 64b extends parallel to the plug axis and increases steadily in direction toward the annular shoulder 3 so that the contact cap 64 has at its rearward edge opposing the annular shoulder 3 its greatest outer diameter which considerably exceeds the inner diameter of the socket 1 before inserting the plug 2 into the socket 1.

While the invention has been illustrated and described as embodied in a coaxial plug-type inner conductor connection, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims: