US3787798A

US3787798A - Heavy duty plug

Info

Publication number: US3787798A
Application number: US00251347A
Authority: US
Inventors: V Carissimi; G Kress
Original assignee: Harvey Hubbell Inc
Current assignee: Hubbell Inc
Priority date: 1972-05-08
Filing date: 1972-05-08
Publication date: 1974-01-22
Anticipated expiration: 1991-01-22
Also published as: CA995325A

Abstract

An apparatus for containing an electrical plug, particularly where a large force is required to either insert or withdraw the plug from a mating outlet. Gripping wells are disposed on opposite sides of the plug which provide both a protective lip and a gripping lip. The protective lip avoids arc burns and electrical shocks during plug insertion. The gripping lip facilitates the applicaton of force during plug withdrawal. Sophisticated fabricaton of parts and the need for additional parts are both avoided by constructing the plug from routine component parts which are cooperatively configured to create the gripping wells upon assembly.

Description

[ Jan.'22, 1974 tal.

issimi e HEAVY DUTY PLUG [75] Inventors: Vincent L. Carissimi, Fair-field, j i i l fi j gz C G K N k, ssls an xammer awrence a eorge less ewar Attorney, Agent, or F irmWooster, Davis & Cifelli [57] ABSTRACT An apparatus for containing an electrical plug, particularly where a large force is required to either insert [73] Assignee: Harrey I'Iubbell, Incorporated,

Bridgeport, Conn.

May 8, 1972 [22] Filed:

or withdraw the plug from a mating outlet. Gripping Appl' 25l347 wells are disposed on opposite sides of the plug which provide both a protective lip and a gripping lip. The protective lip avoids arc burns and electrical shocks during plug insertion. The gripping lip facilitates the applicaton of force during plug withdrawal. Sophisticated fabricaton of parts and the need for additional parts are both avoided by constructing the plug from routine component parts which are cooperatively configured to create the gripping wells upon assembly.

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 716,483 10/1954 Great Britain 339/196 M 6 Claims, 4 Drawing Figures HEAVY DUTY PLUG BACKGROUND OF THE INVENTION The present invention relates to an electric plug and especially to a plug having provisions. for protecting against electrical hazard during plug insertion and for providing a positive grip during plug withdrawal. Hitherto, electric plugs have been contained in housings configured to comply with the particular requirements of various applications. For high power applications, the cable connecting to the plug is quite large and inflexible. Where the plug is adapted to receive such a cable in line with the protruding contact blades the clearance distance necessary above the plug is prohibitive due to the very large cable bend radius encountered. Therefore, in such applications most plugs are adapted to receive the cable perpendicularly to the contact blades and these plugs have become known as right angle plugs.

In high power applications, a very tight fit exists between the contact blades on the plug and the contact slots in the outlet and therefore, a large force is required for both plug engagement and disengagement. This large force and the cable inflexibility previously mentioned, cause particular difficulties when right angle plugs are utilized. On engagement, a struggle is usually encountered in correcting any misalignment between the contact blades and the contact slots due to the inflexible nature of the cable and its orientation relative to the outlet. On disengagement, any force applied to the cable only results in a turning moment which binds the contact blades within the contact slots and therefore, the total force must be applied to. the plug.

Most right angle plugs merely provide flat gripping surfaces located on opposite sides of the plug, with which both engagement and disengagement must be accomplished. Any alignment struggle encountered on engagement of such plugs presents a safety hazard in that the operators hand or fingers may be burned by an electrical are or may slip from the gripping surface to receive an electrical shock on touching the contact blades. On disengagement of such plugs, superfluous forces must be applied perpendicular to the gripping surfaces in attaining a sufficient frictional force to withdraw the blades from the contact slots.

Some right angle plugs provide for gripping lips to facilitate plug disengagement, however, these plugs provide no protective lip to avoid the electrical hazards encountered on plug engagement. Other right angle plugs provide for both the gripping lip and the protective lip but not without incurring a greater manufacturing expense due to the addition of component parts to the plug or by complicating the manufacture of the routine component parts.

SUMMARY OF THE INVENTION It is therefore, a general object of the present invention to provide a right angle plug which minimizes and obviates the disadvantages of the prior art.

It is a specific object of the present invention to provide a right angle plug which includes gripping wells having both the protective and gripping lips.

It is a more specific object of the present invention to provide a right angle plug having routine component parts of cooperating configurations from which gripping wells result upon assembly.

It is another object of the present invention to provide a right angle plug which assembles from routine component parts of simplified configuration and relatively low manufacturing expense.

These objects areaccomplished in one form according to the present invention by modifying the configurations of what would otherwise be routine component parts for a heavy duty plug. A plug housing is configured to have depressions on opposing side surfaces. Each depression has a bottom surface which is partially enclosed by a ledge and the discontinuous portions of the ledges are located to the same side of the plug housing. A blade holder assembles to the plug housing and is configured to provide the discontinuous portions of each ledge and thereby enclose the depressions. Each closed depression creates a gripping well which has both a protective lip and a gripping lip.

BRIEF DESCRIPTION OF THE DRAWING The manner in which these and other objects of the invention are achieved will be best understood by reference to the following description, the appended claims, and the attached drawing wherein:

FIG. 1 is a perspective view of a right angle plug having a cable connected thereto and incorporating the gripping wells of this invention;

FIG. 2 is an exploded view thereof illustrating the component parts utilized in assembly;

FIG. 3 is a sectional view thereof, taken substantially along line 3--3 of FIG. 1 and illustrating the cooperative configuration existing between the plug housing and the blade holder to establish the gripping wells upon asembly of the component parts; and

FIG. 4 is an elevational view of the plug housing illustrating its simplicity for manufacture.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawing, a heavy duty electrical plug 10 incorporating the improvements of this invention is illustrated in FIGS. 1 3. As is standard for such plugs 10, contact blades 12 extend from a blade holder 14 which is secured to a plug housing 16, as illustrated in FIG. 1. Suitable fastener means, such as screws 18, is utilized for securing the blade holder 14 to the plug housing 16. An electrical cable 20 enters the plug 10 perpendicularly to the contact blades 12 and connects therein to the contact blades 12. A cable clamp insert 22 affixes the cable 20 to the plug housing 16 and is secured thereto by suitable means, such as screws 24. At least one gripping well 26 is established upon assembly of the blade holder 14 to the plug housing 16, due to the cooperative configuration existing therebetween.

As shown in FIG. 2, the blade holder 14 includes an insulated housing 28 to which the contact blades 12 are affixed by any suitable means, such as an interference fit. Portions of the contact blades 12 protrude on both sides of the housing 28 and on one side, each contact blade 12 is adapted to have a suitable terminal means for connecting to the electrical connectors of the cable 20, such as a bearing screw 30. Clearance holes 32 are disposed through the housing 28 for passing the screws 18 and where desirable the screws 18 and holes 32 may be adapted to provide a captive arrangement.

The cable clamp insert 22 is generally configured in the form of a bearing block and is fabricated of insulative material. One portion 34 of the insert 22 is specially configured to bear against the cable 20. This portion 34 is arcuately contoured to be of complementary shape to the cable 20 and raised ribs 36 are disposed across the contoured surface perpendicularly to the arcuate axis. Clearance holes 38 are disposed through the insert 22 to pass the screws 24.

The plug housing 16 is fabricated of insulative material by any suitable means such as molding. As is illustrated in FIGS. 2 and 4, the plug housing 16 is partitioned into two open compartments, a contact terminal compartment 40 and a cable clamping compartment 42. A channel 44 provides an opening between the

compartments

40 and 42 and a cable entrance 46 is provided into the cable clamping compartment 42 directly across from the channel 44. Except for depressions 48 on opposite sides of the contact terminal compartment 40, all exterior surfaces on the plug housing 16 are continuous. Each depression 48 is rectangular in shape and has a bottom surface 50. A ledge 52 arises from each bottom surface 50 on three of its four sides and each side having no ledge is disposed to the same side of the plug housing 16 as the openings for both the contact terminal compartment 40 and the cable clamping compartment 42.

The blade holder 14 assembles to the plug housing 16 with the terminal means on the blade holder 14 disposed within the contact terminal compartment 40 of the plug housing 16. The screws 18 securing this assembly are fastened into threaded posts 54 which are disposed within the contact terminal compartment 40. The housing 28 of the blade holder. 14 is configured to cooperate with the configuration of the plug housing '16 in two ways when assembly occurs therebetween. First, the external opening into the contact terminal compartment 40 is closed off. Secondly, the ledge 52 of each depression 48 on the plug housing 16 is extended to enclose the bottom surface 50 and thereby, the depressions 48 are changed into gripping wells 26.

The cable clamp insert 22 is configured to slide into the cable clamping compartment 42 in which threaded posts 56 are disposed for securing the screws 24. Across the bottom of the cable clamping compartment 42, arcuate ribs 58 are disposed which cooperate with the ribs 36 on the cable clamp insert 22 to firmly grip the cable 20.

When a cable 20 is connected to the plug both the blade holder 14 and the cable clamp insert 22 are detached from the plug housing 16 by untightening the

screws

18 and 24. The electrical connections are then made between the conductors of the cable 20 and the terminal means on the blade holder 14. Then the termi-, nal means are directed into the contact terminal compartment 40 of the plug housing 16 while the cable 20 is directed into the conduit established within the plug housing 16 by the in line arrangement of the channel 44, the cable clamping compartment 42, and the cable entrance 46. The clearance holes 32 in the blade holder 14 are then aligned with the threaded posts 54 within the plug housing 16, after which the screws 18 are inserted and tightened. Then the cable clamp insert 22 is directed into the cable clamping compartment 42 of the plug housing 16 with the ribs 36 disposed to bear against the cable 20. The screws 24 are then inserted through the clearance holes 38 in the insert 22 and tightened into the threaded posts 56 within the plug housing 16.

The gripping wells 26 are utilized by the operator during engagement and disengagement of the plug 10 with an electrical outlet (not shown). On engagement of the plug 10 into the outlet, the operator grips the plug 10 across the gripping wells 26 and aportion of each ledge 52 serves as a protective lip 60 which shields against electrical arc and prevents the operators fingers from slipping onto the contact blades 12. On disengagement of the plug 10 from the outlet, another portion of the ledge 52 serves as a gripping lip 62 which facilitates the application of force during plug 10 with drawal.

Although two gripping wells 26 are shown in FIGS. 1 4, a single gripping well 26 could be effectively utilized. The gripping well 26 would be disposed on the end of the plug 10 opposite to the endat which the cable entrance 46 is disposed. On either engagement or disengagement of the plug 10 with the outlet, the operator would grip the cable 20 with one hand and place the fingers of the other hand into the gripping well 26. The hand gripping the cable 20 would then be located away from the zone of electrical hazard during engagement and would also be capable of applying forces during disengagement without difficulty. In the same manner as described above for dual gripping wells 26, the hand placed within the single gripping well 26 would be shielded from electrical hazard by the protective lip 60 during engagement and would have the gripping lip 62 to facilitate the application of force during disengagement.

When a molding process is chosen for the fabrication of the plug housing 16, the adaptation of the process is simplified and straightforward. This is so because the contact terminal compartment 40, the cable clamping compartment 42, and the depressions 48 all open to the same side of the plug housing 16 and therefore, a relatively uncomplicated molding cavity may be utilized.

It should be readily appreciated by those skilled in this art that the heavy duty plug embodied by this invention includes gripping wells which provide both a protective lip during plug engagement and a gripping lipduring plug disengagement. Also, component parts of a routine plug are modified with cooperative configurations to establish the gripping wells upon assembly of the plug. Furthermore, the configuration of each component part remains simplified so as not to complicate fabrication and thereby increase manufacturing expense.

It should be understood that the present disclosure has been made only by way of example and that numerous changes in details of construction and the combinations or arrangements of parts may be resorted to without departing from the true spirit and scope of the invention and, therefore, the present disclosure should be construed as illustrative rather than limiting.

What we claim is:

1. An electrical plug apparatus comprising:

a blade holder for securing contact blades, said contact blade including terminal means for connecting to the conductors of an electrical cable;

a plug housing for enclosing said terminal means on said contact blades; and

fastener means for securing said blade holder to said plug housing, said blade holder and said plug housing being cooperatively configured to establish at least a single gripping well when assembled, said gripping well including a bottom surface with a ledge arising therefrom, said ledge extending completely around the periphery of said bottom surface, said bottom surface being rectangularly shaped and said ledge having four sides, said blade holder comprising only one side of said ledge, gripping well providing a protective lip and a gripping lip, said protective lip shielding the operator from electrical hazard upon engagement of said plug into an outlet, and said gripping lip facilitating disengagement of said plug from the outlet.

2. The apparatus of claim 1 wherein said plug housing includes a clamping means for securing the electrical cable to relieve said terminal means of stress.

3. The apparatus of claim 1 wherein said fastener 6 means comprises screws extending through said blade holder and being received in screw receiving openings formed in said plug housing.

4. The apparatus of claim 1 wherein a pair of said said 5 gripping wells are disposed on said plug.

5. The apparatus of claim 1 wherein: a pair of said gripping wells are disposed on said plug, and said plug housing includes a clamping means for securing the electrical cable to relieve said terminal means of stress.

6. The apparatus of claim 5 wherein said fastener means comprises screws extending through said blade holder and being received in screw receiving openings Patent No. 3,787,798 Dated January 22, 1974 Inventor) Vinoent L. Carissimi 8c George H. Kress It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column A, line 60 (Claim 1) "blade" should be -blades--.

Signed and sealed this 1mm day of May 197E.

(SEAL) Atte st:

. v EDWARD M.FLETCHER,JH. (.1. MARSHALL DAM-I Attesting Officer Commissioner of Patents 9-1050 uscoMM-oc scan-Pea a 0.5. GOVERNMENT PRINTING OFFICE III, 0-385-334.

Claims

1. An electrical plug apparatus comprising: a blade holder for securing contact blades, said contact blade including terminal means for connecting to the conductors of an electrical cable; a plug housing for enclosing said terminal means on said contact blades; and fastener means for securing said blade holder to said plug housing, said blade holder and said plug housing being cooperatively configured to establish at least a single gripping well when assembled, said gripping well including a bottom surface with a ledge arising therefrom, said ledge extending completely around the periphery of said bottom surface, said bottom surface being rectangularly shaped and said ledge having four sides, said blade holder comprising only one side of said ledge, said gripping well providing a protective lip and a gripping lip, said protective lip shielding the operator from electrical hazard upon engagement of said plug into an outlet, and said gripping lip facilitating disengagement of said plug from the outlet.

3. The apparatus of claim 1 wherein said fastener means comprises screws extending through said blade holder and being received in screw receiving openings formed in said plug housing.

4. The apparatus of claim 1 wherein a pair of said gripping wells are disposed on said plug.

6. The apparatus of claim 5 wherein said fastener means comprises screws extending through said blade holder and being received in screw receiving openings formed in said plug housing.