CA1141834A - Electrical connector for coaxial cable - Google Patents
Electrical connector for coaxial cableInfo
- Publication number
- CA1141834A CA1141834A CA000343890A CA343890A CA1141834A CA 1141834 A CA1141834 A CA 1141834A CA 000343890 A CA000343890 A CA 000343890A CA 343890 A CA343890 A CA 343890A CA 1141834 A CA1141834 A CA 1141834A
- Authority
- CA
- Canada
- Prior art keywords
- cable
- braid
- clamp member
- conductor
- nut
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R24/00—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure
- H01R24/38—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts
- H01R24/40—Two-part coupling devices, or either of their cooperating parts, characterised by their overall structure having concentrically or coaxially arranged contacts specially adapted for high frequency
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R2103/00—Two poles
Landscapes
- Coupling Device And Connection With Printed Circuit (AREA)
Abstract
ELECTRICAL CONNECTOR FOR COAXIAL CABLE
Abstract of the Disclosure An electrical connector assembly for terminating a coaxial cable of the type having a central electrical conductor separated from a braid-type outer electrical conductor by an insulation layer with a jacket around the outer conductor, said conductor assembly comprising a rear nut, a forward body, and a medial clamp member. The clamp member has a body with a central aperture extending there-through from front to rear for receiving the insulation layer and central conductor therein and a tapering frusto-conical outer surface of a smaller diameter at the rear of the clamp. The frusto-conical surface is provided with a helical groove (or portions thereof) which are machined into the body to provide a series of undercuts or depres-sions. The connector assembly is assembled over the co-axial cable with the nut slipped over the cable, and the clamp member inserted between the braid and the insulation layer. The clamp member is rotated in the direction of the helical grooves to progressively draw the clamp member within the braid of the cable until the entire frusto-conical portion is within the braid. An edge of each helical groove provides a corner surface which engages the braid, securing it and providing a resistence to un-desirable axial movement of the clamp member away from (out of) the cable. The body and the nut are provided with interfitting threads to secure the entire assembly to-gether, with the clamp member captivated therebetween in proper position.
Abstract of the Disclosure An electrical connector assembly for terminating a coaxial cable of the type having a central electrical conductor separated from a braid-type outer electrical conductor by an insulation layer with a jacket around the outer conductor, said conductor assembly comprising a rear nut, a forward body, and a medial clamp member. The clamp member has a body with a central aperture extending there-through from front to rear for receiving the insulation layer and central conductor therein and a tapering frusto-conical outer surface of a smaller diameter at the rear of the clamp. The frusto-conical surface is provided with a helical groove (or portions thereof) which are machined into the body to provide a series of undercuts or depres-sions. The connector assembly is assembled over the co-axial cable with the nut slipped over the cable, and the clamp member inserted between the braid and the insulation layer. The clamp member is rotated in the direction of the helical grooves to progressively draw the clamp member within the braid of the cable until the entire frusto-conical portion is within the braid. An edge of each helical groove provides a corner surface which engages the braid, securing it and providing a resistence to un-desirable axial movement of the clamp member away from (out of) the cable. The body and the nut are provided with interfitting threads to secure the entire assembly to-gether, with the clamp member captivated therebetween in proper position.
Description
1~41834 ELECTRICAL CONNECTOR FOR COAXIAL CABLE
Background of the Invention This invention relates to an electrical connector for terminating a length of coaxial electrical cable. Such coaxial cable has two coaxial conductors separated by in-sulation, with the outer conductor surrounded by an in-sulating protective jacket.
Many approaches have been suggested for securing an electrical contact to the end of a coaxial-type electrical cable. Some of the approaches require a time consuming and costly preparation of the cable for installation of the connector. Others approaches include a significant number of parts, making assembly difficult. Still another approach is simple and works reasonably well, but is not appropriate for cables with heavy or non-yielding jackets and/or multiple layers of braid.
One approach involves a significant number of parts which the user must arrange and assembly himself in a proper sequence and position. This is undesirable for many reasons: Many parts may result in possible loss of a part or the failure of the assembler to include the part at all or in its proper location; each part must be separately manufactured and inventoried and detailed assembly instructions must be prepared and supplied; this approach leads to some rather small parts which are easily lost or misplaced and hard to identify and handle.
It has been suggested (e.g., U.S. Patent No.
3,373,243) to provide a three-part assembly (a nut, a body, and a clamp mèmber with a frusto-conical shape) for terminating a coaxial cable. The frusto-conical portion of the clamp is pushed axially inward over the central conductor and within the jacket and braid. When the cable ''~
~41834 jacket is thick, or made of a heavy, non-yielding material, or when the axial movement of the clamp member inward is resisted and the jacket and/or braid layers resist, the clamp member is pushed axially outward. In such cases when the clamp member is not properly positioned substantially fully engaged with ~he braid, a poor electrical connection is made between the braid and the clamp, creating undesirable resistance in the outer body assembly. If the clamp member is not properly positioned, the central conductor may not be in proper position within the central contact, again creating a poor electrical connection. Although the nut and body are assembled over the clamp and hold the clamp in place, the clamp in the design shown in this patent can move out of position while the nut and body are being assembled.
Further, a thick jacket or a tight fitting cable or multi-layer braid resists insertion of the clamp.
Other approaches to terminating a coaxial cable require that the cable be prepared by stripping the jacket, braid, insulator layer, and central conductor to progressively longer lengths (in a "stepped~ arrangementl prior to insertion of an electrical connector assembly.
Such a "stepped" arrangement of the conductor is un-desirable in that it requires additional time and effort by the user and provides a chance that the preparation would not be properly done. Such an arrangement is shown in U.S. Patents 3,264,602; 3,107,135; and 3,054,981.
Other terminations of coaxial conductors involving the preparation of the cable in the stepped arrangement are known. ~owever, such an arrangement is undesirable practice because of the time-consuming preparation which is required.
1~41834 Other approaches to obtain a termination of a coaxial connector are shown in U.S. Patents 3,209,287 and 3,634,815.
Accordingly, the prior art coaxial terminations lack a design which has few parts, is easy and quick to assemble at low cost, and yet resists outward axial movement of the clamp member, even before the nut and body are assembled.
1141a~4 The present invention is a connector termination for a ~ial cable which overcomes the limitations and un-desirable features of the prior art while prQviding an as-semb.ly which is easy and quick to assemble, and resists out-ward movement of the clamp member prior to complete assembly of the contact.
According to one aspect of the present invention there is provided an apparatus for use in terminating an electrical cable of the coaxial type having a central con-ductor, a layer of insulation disposed about the central conductor, a braided outer conductor and an external sheet jacket surrounding the conductors. The apparatus includes a rotatable clamp member having a generally frusto-conical external body with tapering sides and a central aperture for receiving the insulated central conductor. The surface of the tapering sides includes a helical groove having a corner at the meeting of the groove with the external surface, such that after the insulated central conductor is received in the aperture and the clamp member is rotated about the cable, the corner progressively engages the braided outer conductor to thereby secure and electrically terminate the cable to the clamp member.
According to another aspect of the present inven-tion there is provided a method of terminating a coaxial cable of ~41834 the type having a jacket, conductive braid and insulation layers surrounding a central conductor. The method includes the steps of cutting the jacket, braid and insulating layer of the coaxial cable perpendicular to the axis of the cable in a substantially uniform length, shorter than the central conductor to provide the cable with a square cut end. A con-ductor body of the type having a central aperture extending therethrough from front to rear and an external frusto-conical surface including a helical groove machined into the body to provide a series of undercuts therearound is assembled over the square cut end such that the body is inserted between the conductive braid and the insulation layer. The frusto-conical body is rotated about the cable, the rotation causing the helical grooves to progressively engage the braid and thereby progressively draw the body within the braid of the ~- cable until the frusto-conical surface is within the braid, thereby preventing axial withdrawl of the body from the cable.
The rear nut and a forward contact element are assembled over t~e frusto-conical body to captivate the body therebetween, the forward contact element contacting the central conductor to complete the contact for the coaxial termination.
According to yet another aspect of the present in-vention there is provided a coaxial cable having an electrical connector termination, including a coaxial cable having a central conductor, an insulating layer surrounding the con-ductor, a braid conductor surrounding the insulating layer, and a protective sheet surrounding the braid conductor, the cable being characterized by the terminable free end being square cut and the central conductor extending forwardly _ 5 _ ~C
therefrom. An electrical connector is provided which in-cludes a terminal body, a clamp member disposed within the terminal body, and a nut assembling the clamp member to the terminal body, the clamp member having a tapered external surface, a bore for receiving the cable and a spiral groove described by a series of undercuts disposed on the tapered external surface. The clamp member is mounted proximate the free end of the cable with a portion of the braid conductor extending forwardly and fully covering the tapered external surface of the clamp member with the braid conductor having portions progressively engaged within the series of under-cuts and electrically terminated to the clamp member secured within the connector.
The assembly of the present invention is advanta-geous in that it uses a "square cut" cable termination in ~' which the jacket, braid conductor and insulation layer are cut to a uniform length (i.e., in a single cut for cable pre-paration). The central conductor extends forwardly of the single cut. Such a square cut termination is an easy and quick one to accomplish in preparation of the cable and economizes on labor costs.
The connector of the present invention is compatible with any type of jacket and does not require the slitting of the jacket maintaining the cable's integrity is advantag-eous in that it increases the life of the cable and the termination.
The connector of the present invention has an ad-vantage in that the electrical joint between the braid and the connector is improved in its reliability and uniformity.
- 5a -,~
As a further advantage of the present invention, the connector of the present invention involves the use of only three separate assemblies of relatively large size to be handled conveniently. The use of a minimum number of pieces reduces the chance of inadvertant loss of a part during packaging or assembly. With only three dissimilar parts, assembly instructions can be quite simple.
The connector of the present invention has an advantage in that the clamp member is merely rotated to draw it into progressive engagement with the cable. Such an engagement minimizes possible damage to the cable.
Other objects and advantages of the present inven-tion will be apparent to one skilled in the art in view of the following detailed description and claims in the ac-companying drawings.
,~' - 5b -C
1~41834 Brief Description of the Drawings FIGURE 1 is a cross sectional view of an electrical connector and coaxial cable of the present invention.
FIGURE 2 is an enlarged side view of a clamp member used in the connector of the present invention, showing the helical groove.
FIGURE 3 is a cross sectional view of the clamp member of FIGURE 2, looking along the lines 3-3 of FIGURE 2 in the direction of the arrows.
FIGURE 4 shows a coaxial cable and a clamp member of the present invention partially inserted over it, with the small rear portion of the clamp member in engagement with the leading edge of the cable braid.
FIGURE 5 shows a cross sectional view of the coaxial cable and clamp member of FIGURE 4 when the clamp member is in complete engagement within the coaxial cable and held in place by the helical thread.
FIGURE 6 is an enlarged cross sectional view of heli-cal thread structure within a circle identified by an arrow and a numeral VI in FIGURE 3.
FIGURE 7 and 8 are views of alternate embodiments of the thread structure shown in FIGURE 6.
FIGURE 9 is a cross sectional view of an alternate embodiment of the connector of FIGURE 1, in which the nut is a multi-piece member.
1~41834 Detailed Description of the Drawin~s FIGURE 1 is a cross sectional view of a coaxial cable 10 terminated by a coaxial electrical connector 100 of the present invention.
The coaxial cable 10 includes a central electrical conductor 12, an outer braid conductor 14, and a layer of dielectric material 16 between the central conductor 12 and the braid conductor 14. An outer jacket 18 surrounds the conductors. The outer jacket 18 and the dielectric material 16 are both made of electrically insulating mat~rials to electrically isolate the conductors 12, 14 from each other and from the environment.
The coaxial connector 100, in its preferred embodi-ment, has three components (or assemblies) which are supplied and handled as separate pieces: a forward body 200, an internal clamp member 300 and a rear nut 400.
The forward body 200 is of conventional design and includes a mating central contact 210 surrounded by an electrically insulating material 220. An outer electrical contact 230 is disposed outside the insulating material 220, electrically isolated from the central contact 210.
When the connector 100 is attached to the cable 10, the central contact 210 is electrically coupled to the central conductor 12 of the cable 10 and the outer contact 230 is electrically coupled to the braid conductor 14 of the cable 10.
The body 200 includes an internal thread 240 at the rear end thereof for coupling to the nut 400.
The clamp member 300 includes an electrically con-ductive body 310 and an insulator 320. The insulator 320 fits within an undercut portion 312 extending rearwardly from the front end of the conductive member. The insulator 320 electrically isolates the exposed portion of the central conductor 12 of the cable and the contact 210 from the body 310. The insulator 320 is retained within the undercut in a known manner (e.g., adhesively or frictionally, through pressing in a member in an interference fit).
Other structure and features of the body 310 of the clamp 300 wi'll be discussed later in conjunction with FIGURES 2-8 of this application.
The nut 400 may be of the type described in U.S.
Patent 3,373,243. The nut 400 includes a rear portion 410 which is grasped during installation and an ,external screw thread 420 located forward of the rear portion 410. The screw thread 420 engages the thread 240 of the ~ody to secure the connector assembly 100 to-gether.
The nut 400 includes a central aperture 430 throughwhich the cable 10 extends. The nut 400 also includes steps 440 which provide increasingly larger diameters of the central aperture 430 in the forward region of the nut.
Such steps, when used in conjunction with a clamp as described in the present design having a frusto-conical surface of increasing diameter, enables the connector 100, when assembled, to retain the cable 10 therein by captivating the jacket 18 and thereby providing resistance .
to decoupling forces applied on the cable. The captivating occurs between the steps and the frusto-conical surface.
1~4~834 FIGURE 2 is an enlarged view of the external surface of the clamp body 310 of the present invention. The clamp body 310 has a forward portion 313 of a larger diameter and a rear frusto-conical portion 314. The portion 314 tapers from a smaller rear end 314a to a larger forward end 314b, where it meets the larger forward portion 313.
A helical groove 316 spirals around the frusto-conical portion 314, making several revolutions. Although a spiral in a form similar to a raised (exposed) screw thread could be used to advantage in the present design, a quicker and less expensive approach is shown in these drawings, that is, to form or cut a groove 316 into the outer surface, which requires the removal of less material. The formation of the helical groove is advantageously formed on an automatic screw machine.
Other methods of fabrication such as stamping and rolling, casting, forging and spinning - could also be used to advantage to create the clamp 300 of the present invention. Using such other methods of fabrication may make it easier and less expensive to have exposed threads.
The pitch and depth of the helical groove are somewhat a matter of design choice. It has been found that a continuous spiral of 40 pitch, .005 deep, right handed buttress type thread works to advantage. Left-handed threads could be substituted and used to advantagein the present design although they would be un-conventional and more difficult to install manually, as an operator is accustomed to install a screw member with right handed threads. The threads on the nut should be of the same type (i.e., right-handed) as on the clamp so that the application of the nut does not tend to uncouple the clamp from the braid.
~41W4 FIGURE 3 shows a cross sectional view of the clamp body 310 without the insulator. The forward undercut portion 312 for receiving the insulator is shown, as are the enlarged forward portion 313, the helical groove 316 and the frusto-conical tapering portion 314.
FIGURE 4 shows a cross sectional view of the clamp member 300 (with body 310 and insulator 320) being inserted over the "square cut" cable 10. The nut 400 has already been inserted over the cable 10 and is moved to the rear of the forward end of the cable, away from the area of the cable upon which the clamp 300 will be applied.
- The body 310 of the clamp and the insulator 320 each have a central aperture (311 and 321, respectively). The central aperture 311 of the clamp is large enough to receive the layer of insulation 16 of the cable 10, while the aperture 321 in the insulator is smaller, merely large enough to receive the central conductor 12 therein.
The cable 10 has been prepared in a manner which is referred to as a "square cut" in the industry. The square cut preparation has the central conductor 12 extending forwardly of the rest of the cable (outer layers:
insulation 16, braid conductor 14, and jacket 18), all of which extend a uniform, but lesser, distance forwardly.
The outer rear surface of the clamp 300 has been pressed between the layer of insulation 16 and the braid layer 14, urging the braid 14 and the jacket radially outward slightly.
li4~834 At the stage shown in FIGURE 4, the helical grooves 316 are in contact with the braid, and because the braid 14 is being urged radially inward by the surrounding jacket 18, the braid 14 is urged partially into the groove 316.
As the body 310 is rotated in the direction of heli-cal groove 316, the grooves 316 coact with the braid 14 to draw the body 310 further in, in the nature of a screw being drawn into wood as it rotates. Similarly, the body 310 is retained by the grooves against undesirable axial movement out of the cable 10 because the braid 14 is engaged upon the groove 316.
FIGURE 5 shows the clamp 300 when the body 310 fully engages the cable 10. The braid 14 and the jacket 18 extend forwardly on the clamp to the enlarged portion 313 thereof, fully covering the tapering frusto-conical portion 314, with the helical groove 316 being imbedded along its length within the braid 14. The insulation layer 16 is well forward within the clamp body in the central aperture thereof.
FIGURE 6 is a cross sectional view showing a portion of the clamp body 310 with the thread or helical groove 316 shown. The helical groove 316 shown here is "U"
shaped and has corners 316a, 316b at the meeting of the groove with the external surface. The rear or trailing corner 316b will engage or "bite into" the braid and prevent it from moving rearwardly, even if the cable is pulled rearwardly with respect to the connector. A
portion of the braid will be forced into the groove, pro-viding a more reliable and uniform electrical connectionbetween the braid and the connector.
1~4~834 While other types of grooves and threads could be used - either exposed external threads, discontinuous grooves, or varying shapes of grooves, the threads of the type shown in FIGURE 6 are believed the preferred embodi-ment as they can be formed quite easily on automatic screw machines. Of course, as previously mentioned, the threads could be formed using other techniques.
FIGURES 7 and 8 show alternate embodiments of helical threads 316' and 316", where the threads are ~V~ shaped.
These threads are also formable on automatic screw machines with a slightly different tool. In FIGURE 7, a leading corner 316a' is flatter than the leading cQrner 316a corner 316b of FIGURE 6 to bite into the braid. In FIGURE 8, the "V" is substantially symmetrical with respect to the surface of the body, giving a front corner 316a" and a rear corner 316b" between which the braid is captivated. The rear corner 316b" does most of the engagement of the braid in this instance.
~- FIGURE 9 shows an alternate embodiment of the con-nector 100 of the present invention. In place of a rear nut of the type shown in FIGURE 1, this embodiment has a rear nut 500 of the type shown in U.S. Patent Nos.
3,634,815. The nut-500 ~n this embodiment includes a res~lient member 510 having a frusto-conical forward bore 512, with sealing members 520, 530 located forward and rearward of the resilient member 510. Since the structure of the nut is of only peripheral concern to the present invention, other nut structures could also be used to advantage.
V
i 1~411~34 The rotary clamp which has the tapered frusto-conical body with the helical groove providing a series of undercuts cut into the external surface of the body engages the braid conductor of the coaxial cable to make an elec-trical termination therewith. As the clamp is rotated about the axis of the cable, corners formed by the helical groove meeting with the external tapered surface draw the clamp progressively deeper into the braid. Further rotation of the clamp draws the clamp progressively further into the cable braid until the braid fully covers the tapered ex-ternal surface of the clamp, resulting in the braid con-ductor having portions progressively engaged with the undercuts to provide a good electrical termination and a greater resistance to undesired outward axial movement of the clamp from the cable.
While a preferred embodiment of the invention has been disclosed, it will be apparent to those skilled in the art that changes may be made to the invention as set forth in the appended claims and, in some instances, certain features of the invention may be used to advantage without corresponding use of other features. ~or example, additional members could be used in the present assembly. The clamp of the present invention could also be used for tri-axial cables with appropriate modifications. Accordingly, it is intended that the illustrative and descriptive materials herein be used to illustrate the principles of the inven-tion and not to limit the scope thereof.
Background of the Invention This invention relates to an electrical connector for terminating a length of coaxial electrical cable. Such coaxial cable has two coaxial conductors separated by in-sulation, with the outer conductor surrounded by an in-sulating protective jacket.
Many approaches have been suggested for securing an electrical contact to the end of a coaxial-type electrical cable. Some of the approaches require a time consuming and costly preparation of the cable for installation of the connector. Others approaches include a significant number of parts, making assembly difficult. Still another approach is simple and works reasonably well, but is not appropriate for cables with heavy or non-yielding jackets and/or multiple layers of braid.
One approach involves a significant number of parts which the user must arrange and assembly himself in a proper sequence and position. This is undesirable for many reasons: Many parts may result in possible loss of a part or the failure of the assembler to include the part at all or in its proper location; each part must be separately manufactured and inventoried and detailed assembly instructions must be prepared and supplied; this approach leads to some rather small parts which are easily lost or misplaced and hard to identify and handle.
It has been suggested (e.g., U.S. Patent No.
3,373,243) to provide a three-part assembly (a nut, a body, and a clamp mèmber with a frusto-conical shape) for terminating a coaxial cable. The frusto-conical portion of the clamp is pushed axially inward over the central conductor and within the jacket and braid. When the cable ''~
~41834 jacket is thick, or made of a heavy, non-yielding material, or when the axial movement of the clamp member inward is resisted and the jacket and/or braid layers resist, the clamp member is pushed axially outward. In such cases when the clamp member is not properly positioned substantially fully engaged with ~he braid, a poor electrical connection is made between the braid and the clamp, creating undesirable resistance in the outer body assembly. If the clamp member is not properly positioned, the central conductor may not be in proper position within the central contact, again creating a poor electrical connection. Although the nut and body are assembled over the clamp and hold the clamp in place, the clamp in the design shown in this patent can move out of position while the nut and body are being assembled.
Further, a thick jacket or a tight fitting cable or multi-layer braid resists insertion of the clamp.
Other approaches to terminating a coaxial cable require that the cable be prepared by stripping the jacket, braid, insulator layer, and central conductor to progressively longer lengths (in a "stepped~ arrangementl prior to insertion of an electrical connector assembly.
Such a "stepped" arrangement of the conductor is un-desirable in that it requires additional time and effort by the user and provides a chance that the preparation would not be properly done. Such an arrangement is shown in U.S. Patents 3,264,602; 3,107,135; and 3,054,981.
Other terminations of coaxial conductors involving the preparation of the cable in the stepped arrangement are known. ~owever, such an arrangement is undesirable practice because of the time-consuming preparation which is required.
1~41834 Other approaches to obtain a termination of a coaxial connector are shown in U.S. Patents 3,209,287 and 3,634,815.
Accordingly, the prior art coaxial terminations lack a design which has few parts, is easy and quick to assemble at low cost, and yet resists outward axial movement of the clamp member, even before the nut and body are assembled.
1141a~4 The present invention is a connector termination for a ~ial cable which overcomes the limitations and un-desirable features of the prior art while prQviding an as-semb.ly which is easy and quick to assemble, and resists out-ward movement of the clamp member prior to complete assembly of the contact.
According to one aspect of the present invention there is provided an apparatus for use in terminating an electrical cable of the coaxial type having a central con-ductor, a layer of insulation disposed about the central conductor, a braided outer conductor and an external sheet jacket surrounding the conductors. The apparatus includes a rotatable clamp member having a generally frusto-conical external body with tapering sides and a central aperture for receiving the insulated central conductor. The surface of the tapering sides includes a helical groove having a corner at the meeting of the groove with the external surface, such that after the insulated central conductor is received in the aperture and the clamp member is rotated about the cable, the corner progressively engages the braided outer conductor to thereby secure and electrically terminate the cable to the clamp member.
According to another aspect of the present inven-tion there is provided a method of terminating a coaxial cable of ~41834 the type having a jacket, conductive braid and insulation layers surrounding a central conductor. The method includes the steps of cutting the jacket, braid and insulating layer of the coaxial cable perpendicular to the axis of the cable in a substantially uniform length, shorter than the central conductor to provide the cable with a square cut end. A con-ductor body of the type having a central aperture extending therethrough from front to rear and an external frusto-conical surface including a helical groove machined into the body to provide a series of undercuts therearound is assembled over the square cut end such that the body is inserted between the conductive braid and the insulation layer. The frusto-conical body is rotated about the cable, the rotation causing the helical grooves to progressively engage the braid and thereby progressively draw the body within the braid of the ~- cable until the frusto-conical surface is within the braid, thereby preventing axial withdrawl of the body from the cable.
The rear nut and a forward contact element are assembled over t~e frusto-conical body to captivate the body therebetween, the forward contact element contacting the central conductor to complete the contact for the coaxial termination.
According to yet another aspect of the present in-vention there is provided a coaxial cable having an electrical connector termination, including a coaxial cable having a central conductor, an insulating layer surrounding the con-ductor, a braid conductor surrounding the insulating layer, and a protective sheet surrounding the braid conductor, the cable being characterized by the terminable free end being square cut and the central conductor extending forwardly _ 5 _ ~C
therefrom. An electrical connector is provided which in-cludes a terminal body, a clamp member disposed within the terminal body, and a nut assembling the clamp member to the terminal body, the clamp member having a tapered external surface, a bore for receiving the cable and a spiral groove described by a series of undercuts disposed on the tapered external surface. The clamp member is mounted proximate the free end of the cable with a portion of the braid conductor extending forwardly and fully covering the tapered external surface of the clamp member with the braid conductor having portions progressively engaged within the series of under-cuts and electrically terminated to the clamp member secured within the connector.
The assembly of the present invention is advanta-geous in that it uses a "square cut" cable termination in ~' which the jacket, braid conductor and insulation layer are cut to a uniform length (i.e., in a single cut for cable pre-paration). The central conductor extends forwardly of the single cut. Such a square cut termination is an easy and quick one to accomplish in preparation of the cable and economizes on labor costs.
The connector of the present invention is compatible with any type of jacket and does not require the slitting of the jacket maintaining the cable's integrity is advantag-eous in that it increases the life of the cable and the termination.
The connector of the present invention has an ad-vantage in that the electrical joint between the braid and the connector is improved in its reliability and uniformity.
- 5a -,~
As a further advantage of the present invention, the connector of the present invention involves the use of only three separate assemblies of relatively large size to be handled conveniently. The use of a minimum number of pieces reduces the chance of inadvertant loss of a part during packaging or assembly. With only three dissimilar parts, assembly instructions can be quite simple.
The connector of the present invention has an advantage in that the clamp member is merely rotated to draw it into progressive engagement with the cable. Such an engagement minimizes possible damage to the cable.
Other objects and advantages of the present inven-tion will be apparent to one skilled in the art in view of the following detailed description and claims in the ac-companying drawings.
,~' - 5b -C
1~41834 Brief Description of the Drawings FIGURE 1 is a cross sectional view of an electrical connector and coaxial cable of the present invention.
FIGURE 2 is an enlarged side view of a clamp member used in the connector of the present invention, showing the helical groove.
FIGURE 3 is a cross sectional view of the clamp member of FIGURE 2, looking along the lines 3-3 of FIGURE 2 in the direction of the arrows.
FIGURE 4 shows a coaxial cable and a clamp member of the present invention partially inserted over it, with the small rear portion of the clamp member in engagement with the leading edge of the cable braid.
FIGURE 5 shows a cross sectional view of the coaxial cable and clamp member of FIGURE 4 when the clamp member is in complete engagement within the coaxial cable and held in place by the helical thread.
FIGURE 6 is an enlarged cross sectional view of heli-cal thread structure within a circle identified by an arrow and a numeral VI in FIGURE 3.
FIGURE 7 and 8 are views of alternate embodiments of the thread structure shown in FIGURE 6.
FIGURE 9 is a cross sectional view of an alternate embodiment of the connector of FIGURE 1, in which the nut is a multi-piece member.
1~41834 Detailed Description of the Drawin~s FIGURE 1 is a cross sectional view of a coaxial cable 10 terminated by a coaxial electrical connector 100 of the present invention.
The coaxial cable 10 includes a central electrical conductor 12, an outer braid conductor 14, and a layer of dielectric material 16 between the central conductor 12 and the braid conductor 14. An outer jacket 18 surrounds the conductors. The outer jacket 18 and the dielectric material 16 are both made of electrically insulating mat~rials to electrically isolate the conductors 12, 14 from each other and from the environment.
The coaxial connector 100, in its preferred embodi-ment, has three components (or assemblies) which are supplied and handled as separate pieces: a forward body 200, an internal clamp member 300 and a rear nut 400.
The forward body 200 is of conventional design and includes a mating central contact 210 surrounded by an electrically insulating material 220. An outer electrical contact 230 is disposed outside the insulating material 220, electrically isolated from the central contact 210.
When the connector 100 is attached to the cable 10, the central contact 210 is electrically coupled to the central conductor 12 of the cable 10 and the outer contact 230 is electrically coupled to the braid conductor 14 of the cable 10.
The body 200 includes an internal thread 240 at the rear end thereof for coupling to the nut 400.
The clamp member 300 includes an electrically con-ductive body 310 and an insulator 320. The insulator 320 fits within an undercut portion 312 extending rearwardly from the front end of the conductive member. The insulator 320 electrically isolates the exposed portion of the central conductor 12 of the cable and the contact 210 from the body 310. The insulator 320 is retained within the undercut in a known manner (e.g., adhesively or frictionally, through pressing in a member in an interference fit).
Other structure and features of the body 310 of the clamp 300 wi'll be discussed later in conjunction with FIGURES 2-8 of this application.
The nut 400 may be of the type described in U.S.
Patent 3,373,243. The nut 400 includes a rear portion 410 which is grasped during installation and an ,external screw thread 420 located forward of the rear portion 410. The screw thread 420 engages the thread 240 of the ~ody to secure the connector assembly 100 to-gether.
The nut 400 includes a central aperture 430 throughwhich the cable 10 extends. The nut 400 also includes steps 440 which provide increasingly larger diameters of the central aperture 430 in the forward region of the nut.
Such steps, when used in conjunction with a clamp as described in the present design having a frusto-conical surface of increasing diameter, enables the connector 100, when assembled, to retain the cable 10 therein by captivating the jacket 18 and thereby providing resistance .
to decoupling forces applied on the cable. The captivating occurs between the steps and the frusto-conical surface.
1~4~834 FIGURE 2 is an enlarged view of the external surface of the clamp body 310 of the present invention. The clamp body 310 has a forward portion 313 of a larger diameter and a rear frusto-conical portion 314. The portion 314 tapers from a smaller rear end 314a to a larger forward end 314b, where it meets the larger forward portion 313.
A helical groove 316 spirals around the frusto-conical portion 314, making several revolutions. Although a spiral in a form similar to a raised (exposed) screw thread could be used to advantage in the present design, a quicker and less expensive approach is shown in these drawings, that is, to form or cut a groove 316 into the outer surface, which requires the removal of less material. The formation of the helical groove is advantageously formed on an automatic screw machine.
Other methods of fabrication such as stamping and rolling, casting, forging and spinning - could also be used to advantage to create the clamp 300 of the present invention. Using such other methods of fabrication may make it easier and less expensive to have exposed threads.
The pitch and depth of the helical groove are somewhat a matter of design choice. It has been found that a continuous spiral of 40 pitch, .005 deep, right handed buttress type thread works to advantage. Left-handed threads could be substituted and used to advantagein the present design although they would be un-conventional and more difficult to install manually, as an operator is accustomed to install a screw member with right handed threads. The threads on the nut should be of the same type (i.e., right-handed) as on the clamp so that the application of the nut does not tend to uncouple the clamp from the braid.
~41W4 FIGURE 3 shows a cross sectional view of the clamp body 310 without the insulator. The forward undercut portion 312 for receiving the insulator is shown, as are the enlarged forward portion 313, the helical groove 316 and the frusto-conical tapering portion 314.
FIGURE 4 shows a cross sectional view of the clamp member 300 (with body 310 and insulator 320) being inserted over the "square cut" cable 10. The nut 400 has already been inserted over the cable 10 and is moved to the rear of the forward end of the cable, away from the area of the cable upon which the clamp 300 will be applied.
- The body 310 of the clamp and the insulator 320 each have a central aperture (311 and 321, respectively). The central aperture 311 of the clamp is large enough to receive the layer of insulation 16 of the cable 10, while the aperture 321 in the insulator is smaller, merely large enough to receive the central conductor 12 therein.
The cable 10 has been prepared in a manner which is referred to as a "square cut" in the industry. The square cut preparation has the central conductor 12 extending forwardly of the rest of the cable (outer layers:
insulation 16, braid conductor 14, and jacket 18), all of which extend a uniform, but lesser, distance forwardly.
The outer rear surface of the clamp 300 has been pressed between the layer of insulation 16 and the braid layer 14, urging the braid 14 and the jacket radially outward slightly.
li4~834 At the stage shown in FIGURE 4, the helical grooves 316 are in contact with the braid, and because the braid 14 is being urged radially inward by the surrounding jacket 18, the braid 14 is urged partially into the groove 316.
As the body 310 is rotated in the direction of heli-cal groove 316, the grooves 316 coact with the braid 14 to draw the body 310 further in, in the nature of a screw being drawn into wood as it rotates. Similarly, the body 310 is retained by the grooves against undesirable axial movement out of the cable 10 because the braid 14 is engaged upon the groove 316.
FIGURE 5 shows the clamp 300 when the body 310 fully engages the cable 10. The braid 14 and the jacket 18 extend forwardly on the clamp to the enlarged portion 313 thereof, fully covering the tapering frusto-conical portion 314, with the helical groove 316 being imbedded along its length within the braid 14. The insulation layer 16 is well forward within the clamp body in the central aperture thereof.
FIGURE 6 is a cross sectional view showing a portion of the clamp body 310 with the thread or helical groove 316 shown. The helical groove 316 shown here is "U"
shaped and has corners 316a, 316b at the meeting of the groove with the external surface. The rear or trailing corner 316b will engage or "bite into" the braid and prevent it from moving rearwardly, even if the cable is pulled rearwardly with respect to the connector. A
portion of the braid will be forced into the groove, pro-viding a more reliable and uniform electrical connectionbetween the braid and the connector.
1~4~834 While other types of grooves and threads could be used - either exposed external threads, discontinuous grooves, or varying shapes of grooves, the threads of the type shown in FIGURE 6 are believed the preferred embodi-ment as they can be formed quite easily on automatic screw machines. Of course, as previously mentioned, the threads could be formed using other techniques.
FIGURES 7 and 8 show alternate embodiments of helical threads 316' and 316", where the threads are ~V~ shaped.
These threads are also formable on automatic screw machines with a slightly different tool. In FIGURE 7, a leading corner 316a' is flatter than the leading cQrner 316a corner 316b of FIGURE 6 to bite into the braid. In FIGURE 8, the "V" is substantially symmetrical with respect to the surface of the body, giving a front corner 316a" and a rear corner 316b" between which the braid is captivated. The rear corner 316b" does most of the engagement of the braid in this instance.
~- FIGURE 9 shows an alternate embodiment of the con-nector 100 of the present invention. In place of a rear nut of the type shown in FIGURE 1, this embodiment has a rear nut 500 of the type shown in U.S. Patent Nos.
3,634,815. The nut-500 ~n this embodiment includes a res~lient member 510 having a frusto-conical forward bore 512, with sealing members 520, 530 located forward and rearward of the resilient member 510. Since the structure of the nut is of only peripheral concern to the present invention, other nut structures could also be used to advantage.
V
i 1~411~34 The rotary clamp which has the tapered frusto-conical body with the helical groove providing a series of undercuts cut into the external surface of the body engages the braid conductor of the coaxial cable to make an elec-trical termination therewith. As the clamp is rotated about the axis of the cable, corners formed by the helical groove meeting with the external tapered surface draw the clamp progressively deeper into the braid. Further rotation of the clamp draws the clamp progressively further into the cable braid until the braid fully covers the tapered ex-ternal surface of the clamp, resulting in the braid con-ductor having portions progressively engaged with the undercuts to provide a good electrical termination and a greater resistance to undesired outward axial movement of the clamp from the cable.
While a preferred embodiment of the invention has been disclosed, it will be apparent to those skilled in the art that changes may be made to the invention as set forth in the appended claims and, in some instances, certain features of the invention may be used to advantage without corresponding use of other features. ~or example, additional members could be used in the present assembly. The clamp of the present invention could also be used for tri-axial cables with appropriate modifications. Accordingly, it is intended that the illustrative and descriptive materials herein be used to illustrate the principles of the inven-tion and not to limit the scope thereof.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An apparatus for use in terminating an electrical cable of the coaxial type having a central conductor, a layer of insulation disposed about the central conductor, a braided outer conductor and an external sheath jacket surrounding the conductors, said apparatus including:
a rotatable clamp member having a generally frusto-conical external body with tapering sides and a central aperture for receiving the insulated central conductor, the improvement wherein the surface of the tapering sides includes a helical groove having a corner at the meeting of the groove with the external surface, such that after the insulated central conductor is received in the aperture and the clamp member is rotated about the cable, the corner progressively engages the braided outer conductor to thereby secure and electrically terminate the cable to the clamp member.
a rotatable clamp member having a generally frusto-conical external body with tapering sides and a central aperture for receiving the insulated central conductor, the improvement wherein the surface of the tapering sides includes a helical groove having a corner at the meeting of the groove with the external surface, such that after the insulated central conductor is received in the aperture and the clamp member is rotated about the cable, the corner progressively engages the braided outer conductor to thereby secure and electrically terminate the cable to the clamp member.
2. An apparatus for terminating a, cable of the type described in Claim 1 wherein the helical groove corner is continuous.
3. An apparatus for terminating a cable of the type described in Claim 1 wherein the apparatus includes a connector body receiving the clamp, a nut securing the clamp within the connector body, and thread means for coupling the nut to the connector body, with the thread means on the nut and the helical groove being rotated in the same direction for engage-ment, whereby the coupling of the nut about the connector body tends to further engage the braid with the clamp.
4. A method of terminating a coaxial cable of the type having a jacket, conductive braid and insulation layers surrounding a central conductor, the method comprising the steps of:
cutting the jacket, braid and insulation layer of the coaxial cable perpendicular to the axis of the cable in a substantially uniform length, shorter than the central conductor to provide the cable with a square cut end;
providing a conductive body of the type having a central aperture extending therethrough from front to rear and an external frusto-conical surface including a helical groove machined into the body to provide a series of undercuts there-around;
assembling the body over the square-cut end such that the body inserted between the conductive braid and the insulation layer;
rotating the frusto-conical body about the cable, the rotation causing the helical grooves to progressively engage the braid and thereby progressively draw the body within the braid of the cable until the frusto-conical surface is within the braid, thereby preventing axial withdrawl of the body from the cable; and assembling a rear nut and a forward contact element over the frusto-conical body to captivate the body there-between, the forward contact element contacting the central conductor to complete the contact for the coaxial termination.
cutting the jacket, braid and insulation layer of the coaxial cable perpendicular to the axis of the cable in a substantially uniform length, shorter than the central conductor to provide the cable with a square cut end;
providing a conductive body of the type having a central aperture extending therethrough from front to rear and an external frusto-conical surface including a helical groove machined into the body to provide a series of undercuts there-around;
assembling the body over the square-cut end such that the body inserted between the conductive braid and the insulation layer;
rotating the frusto-conical body about the cable, the rotation causing the helical grooves to progressively engage the braid and thereby progressively draw the body within the braid of the cable until the frusto-conical surface is within the braid, thereby preventing axial withdrawl of the body from the cable; and assembling a rear nut and a forward contact element over the frusto-conical body to captivate the body there-between, the forward contact element contacting the central conductor to complete the contact for the coaxial termination.
5. A coaxial cable having an electrical connector termination comprising:
a coaxial cable including a central conductor, an insulating layer surrounding the conductor, a braid conductor surrounding the insulating layer, and a protective sheath surrounding the braid conductor, said cable being charac-terized by the terminable free end being cut square and the central conductor extending forwardly therefrom; and an electrical connector, the connector including a terminal body, a rotatable clamp member disposed within the terminal body and a nut assembling the clamp member to the terminal body, said clamp member having a generally frusto-conical external body with a tapered external surface, a bore for receiving the cable, the tapered surface includes a spiral groove described by a series of undercuts disposed and having a corner at the meeting of the groove with the external surface;
said clamp member being mounted proximate the free end of the cable with a portion of the braid conductor ex-tending forwardly and fully covering the tapered external surface of the clamp member with the braid conductor having portions progressively engaged within the series of under-cuts and electrically terminated to said clamp member secured within the connector.
a coaxial cable including a central conductor, an insulating layer surrounding the conductor, a braid conductor surrounding the insulating layer, and a protective sheath surrounding the braid conductor, said cable being charac-terized by the terminable free end being cut square and the central conductor extending forwardly therefrom; and an electrical connector, the connector including a terminal body, a rotatable clamp member disposed within the terminal body and a nut assembling the clamp member to the terminal body, said clamp member having a generally frusto-conical external body with a tapered external surface, a bore for receiving the cable, the tapered surface includes a spiral groove described by a series of undercuts disposed and having a corner at the meeting of the groove with the external surface;
said clamp member being mounted proximate the free end of the cable with a portion of the braid conductor ex-tending forwardly and fully covering the tapered external surface of the clamp member with the braid conductor having portions progressively engaged within the series of under-cuts and electrically terminated to said clamp member secured within the connector.
6. A coaxial cable of the type described in Claim 5 wherein the larger end of the clamp member is mounted to-ward the free end of the cable.
7. A coaxial cable of the type described in Claim 6 wherein the nut and contact are joined by threads and the rotation of the nut to secure it to the contact is in a direction to urge the helical undercut into relatively greater engagement of the clamp member and braid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US4166779A | 1979-05-23 | 1979-05-23 | |
| US41,667 | 1979-05-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1141834A true CA1141834A (en) | 1983-02-22 |
Family
ID=21917707
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000343890A Expired CA1141834A (en) | 1979-05-23 | 1980-01-17 | Electrical connector for coaxial cable |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0020188B1 (en) |
| JP (1) | JPS55159579A (en) |
| CA (1) | CA1141834A (en) |
| DE (1) | DE3061857D1 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1145430A (en) * | 1980-06-02 | 1983-04-26 | James J. Karol | Method of and electrical termination for coaxial cable |
| EP0140185A3 (en) * | 1983-11-01 | 1985-07-10 | Allied Corporation | An electrical connector assembly including means for grounding and terminating a coaxial cable |
| EP0341251B1 (en) * | 1987-01-20 | 1993-03-17 | The Whitaker Corporation | Electrical tap connector assembly |
| US4744775A (en) * | 1987-02-12 | 1988-05-17 | Amp Incorporated | Electrical tap connector assembly |
| US4825021A (en) * | 1987-02-12 | 1989-04-25 | Amp Incorporated | Electrical tap connector assembly |
| JPH0247781U (en) * | 1988-09-27 | 1990-04-03 | ||
| FR2667731B1 (en) * | 1990-10-05 | 1993-03-26 | Itt Composants Instr | SHIELDED ELECTRICAL CONNECTOR, WATERPROOF AND ELECTRICALLY INSULATED. |
| FR2671434A1 (en) * | 1991-01-04 | 1992-07-10 | Berault Michel | Electrical connection device for linking a cable and an appliance |
| GB9101685D0 (en) * | 1991-01-25 | 1991-03-06 | Ramm Stephen G | Outdoor lighting system |
| WO1998024155A1 (en) * | 1996-11-29 | 1998-06-04 | Microproject Di Capani L. & C. S.N.C. | Connection sleeve for coaxial connectors |
| US6497587B2 (en) | 1996-11-29 | 2002-12-24 | Microproject Di Campani L. & C. S.N.C. | Connector coupled by pressure for telecommunications systems |
| JP4649213B2 (en) * | 2004-03-08 | 2011-03-09 | 株式会社オートネットワーク技術研究所 | Manufacturing method of shielded wire harness and terminal structure of shielded cable |
| RU210673U1 (en) * | 2021-12-07 | 2022-04-26 | Акционерное общество "Научно-исследовательский институт Приборостроения имени В.В. Тихомирова" | Cable shield termination unit |
| CN114678717B (en) * | 2022-03-10 | 2023-09-22 | 中国航天时代电子有限公司 | Vacuum high-power low PIM radio frequency connector |
| CN115332893B (en) * | 2022-10-17 | 2023-02-28 | 天津市路灯管理处 | Wire joint mechanism |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3264602A (en) * | 1964-03-13 | 1966-08-02 | Automatic Metal Products Corp | Electrical connectors for coaxial cables |
| US3373243A (en) * | 1966-06-06 | 1968-03-12 | Bendix Corp | Electrical multiconductor cable connecting assembly |
| DE2159867A1 (en) * | 1971-12-02 | 1973-06-07 | Spinner Georg | COAXIAL PLUG FOR COAXIAL CABLE WITH FULL DIELECTRIC |
| IT998613B (en) * | 1973-09-14 | 1976-02-20 | Sits Soc It Telecom Siemens | CONNECTOR FOR PROVISIONAL FLYING TYPE CONNECTIONS BETWEEN A RIGID COAXIAL CABLE AND A FLEXIBLE LE COAXIAL CABLE |
| US4070751A (en) * | 1977-01-12 | 1978-01-31 | Amp Incorporated | Method of making a coaxial connector |
| US4135776A (en) * | 1977-01-28 | 1979-01-23 | E. F. Johnson Company | Solderless coaxial cable connector |
-
1980
- 1980-01-17 CA CA000343890A patent/CA1141834A/en not_active Expired
- 1980-04-04 EP EP19800400458 patent/EP0020188B1/en not_active Expired
- 1980-04-04 DE DE8080400458T patent/DE3061857D1/en not_active Expired
- 1980-05-23 JP JP6879380A patent/JPS55159579A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0020188A2 (en) | 1980-12-10 |
| DE3061857D1 (en) | 1983-03-17 |
| JPS55159579A (en) | 1980-12-11 |
| EP0020188A3 (en) | 1981-01-14 |
| EP0020188B1 (en) | 1983-02-09 |
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Legal Events
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| MKEX | Expiry | ||
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