US2619515A - Vapor and explosion proof plug and receptacle - Google Patents

Description

Nov. 25, 195 2 L. C. DOANE VAPOR AND EXPLOSION PROOF PLUG AND RECEPTACLE Filed Dec. 20, 1947 4 Sheets-Sheet 1 W 29 I k I 35 a [I n: al '0 5 44 4557 4 55 Zhmentor 3g AfPOY C floA/w Gttome s Nov. 25, 1952 c, DOANE 2,619,515

VAPOR AND EXPLOSION PROOF PLUG AND RECEPTACLE Filed Dec. 20, 1947 4 Sheets-Sheet 2 Nov. 25, 1952 1 c. DOANE I VAPOR AND EXPLOSION PROOF PLUG AND RECEPTACLE 4 Sheets-Sheet 3 Filed Dec. 20, 1947 Zinogntor y 3 L w, A m m w Nov; 25, 1952 L. c. DOANE 2,619,515

VAPOR AND EXPLOSION PROOF PLUG AND RECEPTACLE Filed Dec. 20, 1947 4 Sheets-Sheet 4 O I /,fllll///l////// \QIIIIIIIIiID-IIWQ /7 Z'mventor A590 c flea/v5 u 791.44, M, 6 mm 76 attorneys Patented Nov. 25, 1952 UNITED STATE S PATENT OFF ICE VAPOR AND EXPLOSION: PROOF PLUG AND .RECEPTACLE Leroy C(Doane, Essex, Conn.

Application-DecemberZO, 1947, Serial'No. 792,906

The present invention relates to electrical plugs andreceptacles of the .vapor.proof .type.

An object of .the inventionis to provide an electrical connector comprising a plug portion and a receptacleportion in which the vpluglmay be separatedfrom the receptacle without exposing the current carryingparts of the receptacle to vapors whichmay be present in the surrounding atmosphere. The invention contemplates that the plugportion will be electricallyenergized fromthereceptacle portionandthat therewill be no danger in exposing the plug itself .to the vapors.

A further object. of theinvention isto provide a receptacle in whichany arcing which mayoccur upon engagement or disengagementbetweenthe currentcarrying partsof'the plugandthe receptacle will occur in anenclosedchamberfrom which vaporsare excluded.

Still .another object of the inventionis to provide a receptacle having an enclosed arcing chamher which will remain sealedas theplug is-insertedor withdrawn.

It is a feature of the invention that the plug is provided with a. heavily constructedshell which is arranged-toprotect theprongs of the plug. from mechanical injury notwithstanding rough usage and severe conditions of service.

It is a furtherobject of the invention .to provide a receptacle which, while permitting ready application and removal. of vthe. plug,.is nevertheless sealed against external pressures, ..such as waterpressure. Such a device. is very useful. upon ships where submerging .of .a compartment in which the receptacle is'located would short ,circuit the electric system if .waterreached theinterior of the receptacle.

Other and further objects will become apparent upon reading the following specification together with the accompanying drawing forming a part hereof.

Referring tothe drawing:

Figure 1 shows a view in elevation ofan embodiment of the invention with theplug removed from the receptacle,

Figure 2 is an approximately sectional view in elevation showing the plug inserted in'the recept-acle,

Figure 3 is-asectional plan view showingithe plug removed-from thereceptacle,

Figure 4 is a sectional view taken along the line L-4 of Fig. 2,"looking inthe directiorrof the-arrows,

Figure 5 is a sectional .view taken along the line 5-- 5 of Fig. 2,.looking in the direction of the arrows.

lFiguresG, 7. and Bare perspective views of pertions of the receptacle,

iFigure 'Bshows a plan view of .a cluster of receptacles, partly broken away,

Figure lo is'an elevational view of the cluster shown infF-ig. 9, partly'broken away,

.LFigure l1 isa sectional View taken alongthe lineH-H oflFiglO,.looking'inthe direction of the arrows.

Figure12 is an enlarged longitudinal sectional view of a modified form of receptacle.

fFigurel13 isa fragmentary perspective view of a .part of the valved insulator plate shown in Fig. '12.

Figure'fl llis a longitudinal sectional view of an insulator plate .of the form 'shown in Fig. 12 beforeibeing clamped in the receptacle.

'Figure"l5 is. an enlarged longitudinal sectional view of a .form of receptacle especially constructed to withstand external pressure.

Figure 16 is a'perspective view of a modified form of valved insulator plate to be used with a plug'having prongs of flat cross-section.

Figure 17 is a fragmentary perspective view of a plug'having prongs of flat cross-section.

Re'ferring'to Fig. l, the invention comprises a connector having aplug portion designated generally as 20 and a receptacle portion designated generallyas 2 I. Ailexible cord 22 enters the shell 23 or plug 20 through a .vapor tight gland .consisting of the packing nut 24 and packing "25. Nut 24 is threaded into shell '23 and may be tightened to compress packing 25 firmly against the external surface of cord 22 forming a vapor proof. seal.

Cord 22 is shown comprising three conductors 26, .21 and 28 whichextend within shell 23 to three prongs 129, v30.and 3|, respectively. These prongsare secured in a plate of insulating material .32 which is held in shell 23 by a threaded retaining ring 33. Each-prong is shown with a hollow .portion which .passes through plate -32 and-whichis headed over to secure the prong firmly in position. The hollow portion is arranged to receive theconductor which may be firmly secured and electrically connected by soldering, brazing, orsimilar means. A gasket 34 of rubber or similar flexible material is fitted tightly over the prongs 29, 30, and 3|. Gasket 34 is provided with annular concentric ridges -35 which are arranged for sealing engagement with a flat face of the receptacle -2I as hereinafter described.

.A snap ring .36 extends circumferentially around shell 23 and is provided with two straight portions 37 which fit into slots 38 in shell 23. The slots 36 communicate with diametrically opposed grooves 39 in shell 23 and the straight portions 3? of snap ring 35 traverse these grooves for engagement with looking lugs on the receptacle 2| as described below. A third groove 46} is provided to prevent the plug from being inserted in the receptacle in any other than one particular positon. This makes certain that the same polarity will always be observed in establishing the electrical connections between the plug 26 and the receptacle 2!.

The receptacle 2! comprises a body portion 45 which is threaded at one end for insertion in a conduit or metallic wall. A pair of diametrically opposed lugs 42 project outwardly from body Al and are shaped for engagement with the corresponding grooves 39 in shell 23. When the plug 2!! is firmly seated in the receptacle 2!, as clearly seen in Fig. 4, the lugs 42 engage the straight portions 37 of snap ring 36 and prevent plug 2d from being removed unless sufficient force is exerted to spread the straight portions 31. 'A third lug 53 is arranged to engage groove 48 to maintain the correct polarity for the connections. The face of body M is fiat and will engage the two annular ridges 35 of gasket 34 when the plug 29 is firmly seated in receptacle 25 thereby forming a tight seal which will exclude vapors from the space in the vicinity of the current carrying parts.

There are three holes M in the fiat face portion of body 31 which are large enough to provide suitable clearance for the three prongs 29, 3!], and BI of plug 26. Disposed within body GI and immediately behind the flat face thereof is a sealing insulator 45. This insulator is made of a flexible material such as rubber and is provided with three inwardly extending recessed portions 15 each of which is generally conical in shape and each of which is provided with an aperture 47 which is self-closing. VJhen plug 28 is inserted in receptacle 2|, the three prongs 29, 30, nd 3! enlarge the apertures 31 so that the prongs may penetrate into the interior of the receptacle at the same time maintaining a vapor tight seal. When the plug is removed, the apertures close, thus excluding vapors from the interior portion of the receptacle. A further insulating member 48 which is made of yielding material such as rubber is provided with three contact members 49 which are arranged for engagement with the three prongs 29, 30, and 3!. These contact-members are shown as being constructed from a single strip of electrically conductive sheet material which has a good degree of resiliency in order to grip the prongs of plug 29. Acting conjointly with the resilency of the flexible insulating material of insulator 43, the spring action of contact member it tends to maintain good electrical contact with each of the prongs. The semicircular portions 50 are flared and enlarged at 51 to guide the contact prong upon insertion in the receptacle and to prevent the contact member from being pulled out from the rear of the receptacle through the insulator it. Contact member G9 is provided with a hole 52 for the attachment of a conductor which may then be soldered to establish a permanent connection.

Sealing insulator 35 and insulator d3 are assembled in body ll with the sealing insulator d disposed immediately behind the holes 44 with the apertures d? in alignment with the holes. A metallic plate 53 having a Y-shaped aperture therein is placed in position behind insulator 48, the aperture in plate 53 fitting around the Y- shaped projection 55 at the rear of insulator 48. The Y-shaped aperture thus prevents insulator 48 from rotating and the Y-shaped projection 55 provides an increased path to prevent electrical leakage to the body 4| and plate 53. In the embodiment of the invention illustrated, plate 53 is permanently secured by rolling over the edge of body 4! at 5 3 to hold the plate 53 securely in position. Other means of fastening may be used if desired. Body 4! is shown threaded at its rear port-ion and the cutting of these threads should be deferred until after completion of the rolling operation which secures plate 53 in order to avoid injury to the threads.

In operation, the plug 25 is inserted in receptacle 2i and the prongs 29, 38 and SI engage the closed apertures 41 in flexible seal-ing 1nsulator d5 penetrating into the interior of body 4! without affording an opportunity for vapors to enter the portion where electrical contact is made. Thus, any spark which may occur when the circuit is completed will not be likely to cause an explosion. Furthermore, any spark which may occur will be confined within the interior of the body 4| and within a closed chamber formed by the three spaces between the insulators 5 and 48. The construction may be made sufiiciently heavy so that any explosions which may occur will be confined within the interior of body 4! and so that any flames accompanying the explosion will be confined within the interior of the receptacle. If the flames remain so confined, there will be no danger of communicating the explosion to other vapors in the area surrounding the place where the plug and receptacle are in use.

Similarly, the are or sparking which may take place on removal of the plug will have been dissipated before the plug 26 can be removed. Moreover, the self-closing action of apertures 47 prevents communication between the surrounding atmosphere and the interior of the receptacle 2| as the prongs 29, 33, and ti are removed.

Prong 3| has been shown somewhat longer than prongs 29 and 39. It is contemplated that in certain instances, as a safety precaution, the apparatus connected to plug 29 will be grounded by a separate grounding conductor. In such cases it is desirable that the ground be applied before the other conductors become energized and that the ground be not removed until after the other conductors have first been deenergized. By using a longer prong such as 3'! for the grounding conductor, this sequence will be observed.

In Fig. 9, a group of receptacles 25 is arranged in a cluster to facilitate the connection of several plugs 29. It is desirable, where several pieces of portable apparatus are to be used at the same location which is at a distance from the nearest power receptacle, to avoid running a separate cord from each individual piece of apparatus back to the power receptacle. This arrangement also avoids the necessity for the installation of several permanent power receptacles in order to be able to establish simultaneous connection temporarily to the several pieces of apparatus.

The cluster comprises a housing 69 with an internal wall 61 in which are threaded three receptacles 2| as previously described. A hinged cover 52 is provided with three slots 63 arranged to permit the cords 22 to emerge from the cover 62. A main cord 64 is provided with a plug 65 similar in all respects to the plugs 20. 00rd enters housing 69 through a vapor and explosion proof packing gland 66 of construction similar to that of th gland provided in each of the plugs. Connections from cord 64 extend in multiple to the three receptacles within the wireway 6'! inside housing 68. This wireway 61 is enclosed by a plate 63 which is sealed at- 69 for the exclusion of vapors.

Disposed on a shelf portion H! of housing 60 are three plug releasing levers H which are arranged to assist in the removal of any-plug from each of the receptacles. These levers are particularly desirable when all three receptacles are in use and it is difficult to obtain a firm grasp on the plug to be removed. Each lever is pivoted at 72 and is provided with an extending flange 73 shaped for engagement with the end of one of the plugs. Upon moving lever H laterally, flange '13 urges the plug away from the receptacle as shown in Fig. 9. Once it has been moved a sufficient distance to disengage snap ring 38 from lugs 52, the plug may be readily removed without great effort. This arrangement also reduces the inclination on the part of persons using this apparatus to remove the plug by pulling on the cord.

The cluster may be provided if desired with magnetic means which will serve to hold it in position upon any iron or steel surface on which it may be placed, as for instance upon the steel deck of a ship. In the construction shown, a permanent magnet 15 is secured in a recess 16 in the housing Gil, the lower face of the magnet being exposed so that it will rest upon and cling to a surface of magnetic material.

Figure 12 shows a modified form of receptacle from that shown in Figs. 2 and 3. In this figure a sealing insulator or diaphragm 80 is utilized which is somewhat thinner than that shown in Fig. 2. This makes the valve portion more flexible and it is easier to'insert and withdraw the prongs of the plug. The conical recess 82 is of such depth that its apex extends beyond the plane of the face of the diaphragm, as indicated by the broken line 84. This facilitates the insertion' of the prongs of the plug, as the material of the valve portion of the diaphragm can bend in order to permit the aperture 86 to open to receive the prong. Bodily displacement of the yielding material of the diaphragm is therefore minimized.

Figures 12 and 13 also show the use of a metal reinforcing disc 88 having a number of spring fingers 9i] projecting therefrom, the tips of which bear against the conical valve portion of the diaphragm near the apex thereof, so as to assist in tight closing of the aperture 85. The fingers 90 are preferably bowed outward between their ends, as indicated at 92, so that the firmest engagement is between the tips of the fingers and the cone near its apex.

As the diaphragm 88, which is thinner than the form of valve insulator shown in Figs. 2 and 3, may not be sufiiciently stiff to resist outward pull of the prongs of the plug or internal pressure caused by explosions within the explosion chambers 94, it is preferable to provide a reinforcing disc 96 of rigid insulating material mounted in the end of the receptacle outside of the diaphragm 80. The rigid member 96 has openings 98 big enough to permit the plug prongs to pass freely through the same. The member 96 is furthermore provided with conical projections Hill on its inner surface which extend part :way into the conical recess 82 in the diaphragm so as to limit the movement of the conical valve portions.

Figure 14 shows a shapein which the valve insulator or diaphragm 23%} may be initially molded and cured. It will be seen that the diaphragm is molded in concavo-convex form with the valve cones extending from the convex side. Whena diaphragm of this shape is clamped between two fiat surfaces in the receptacle, it is thereby flattened out into flat shape, as shown in Fig. 12. This produces increasedpressure betweenthe side walls ofthe apertures 86'adjacent to the apices of the valve cones and helps to secure a tight seal.

Figure 15 shows a receptacle especially constructed to withstand external pressures of either vapors or liquids. Such a construction is particularly useful under conditions where the receptacle may be submerged so as to besubjected to external water pressure. This is a condition frequently encountered on naval or other vessels. If water enters the receptacle and reaches the electrical connections, it may cause a short circult entailing serious consequences. In the construction shown in Fig. 15 the receptacle is provided with a diaphragm Hi1 shown as similar to the diaphragm in Fig. 12, but reversedwith the valve cones pointing outwardly. The diaphragm is clamped between the insulating block H2 similar to the block shown in Fig. 12, but placed behind the diaphragm with the conical projections pointing outwardly, and a block of insulating material Ii i having chambers H6 for reception of the valve cones, and openings H8 to permit entrance of the contact prongs. Pressure entering the chambers 1 it through the openings H8 will exert pressure on the valve cones, so as to seal the valve apertures therethrough and exclude the water or other fluid under pressure from reaching the electrical connections.

Figure 16 shows a form of valve diaphragm I29 having cone shaped valve protuberances I22 thereon which are of flattened or elliptical crosssection and provided with apertures I24 of fiat shape. This construction permits the use of a plug having prongs 126 of flat shape, as shown in Fig. 17. Such form of prongs and apertures is desirable where heavy currents are to be carried, as the section of the prongs may be made as large as desired by simply utilizing prongs of greater width. The valve apertures of flat shape will readily receive such wide flat prongs without undue distortion and will seal properly when the prongs are removed.

Figure 16 also shows a slightly modified form of spring reinforcing member for the valve cones. As here shown, a metal disc I 28 having the same diameter as the diaphragm I25 is provided, this disc having spring fingers I30 struck therefrom to press upon the several valve cones and assist in sealing the same.

I have described what I believe to be the best embodiments of my invention. I do not wish, however, to be confined to the embodiments shown but what I wish to cover by Letters Patent is set forth in the appended claims.

I claim:

1.In a connector of the class described, a receptacle body having a contact therein for engagement with a removable contact prong, and means for sealing said receptacle against admission of a fluid under pressure into contact with said contact in the receptacle body, said means comprising a diaphragm of rubber-like 7 material having an outwardly projecting conical valve projection having a self-closing opening through the apex thereof, and means for clamping said flexible diaphragm in the receptacle.

2. In a connector of the class described, a receptacle having a body of insulating material therein, a contact member within said insulating body exposed at its outer end for engagement by a contact prong, and an insulating diaphragm of rubber-like material having a conical portion provided with a self-closing opening at the apex of the conical portion, said insulating diaphragm being mounted adjacent to the insulating body, and a metal plate surrounding the conical portion of said diaphragm, said plate carrying spring fingers engaging the outer surface of said conical portion and constructed to press thereon so as to assist in sealing said self-closing opening.

3. In a. connector of the class described, a receptacle body having a contact therein for engagement with a removable contact prong and sealing means for said receptacle comprising a thick diaphragm of rubber-like material having a portion thereof molded and cured to form an elastic conical valve projection, said valve projection having an opening through the apex thereof through which the contact prong may be inserted or removed, the walls of said opening when the prong is removed closing into sealing contact clue to the resiliency of the rubber-like material so as to render the opening self-closing and means for clamping said rubber-like diaphragm in the receptacle.

4. In a connector of the class described, a re- A cured in convex form and means for flattening out said convex body and clamping the same in flat shape within the receptacle thereby increasing the self-closing pressure between the walls of the valve opening.

5. In a connector of the class described, a receptacle including an insulating member having a recess therein opening in a direction to receive a contact prong, said insulating member carrying a contact within the recess for engagement with the contact prong, said recess providing an arcing chamber, and sealing means for said receptacle and arcing chamber comprising a thick diaphragm of rubber-like material having a conelike formation thereon projecting part way into said arcing chamber and having an opening extending through the apex thereof through which the contact prong may be inserted or removed, the walls of said opening when the prong is removed closing into sealing contact due to the resiliency of the rubber-like material so as to render the opening self-closing, and means for clamping said rubber-like diaphragm in the receptacle.

LEROY C. DOANE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 768,175 Fritchle Aug. 23, 1904 914,038 Gugler Mar. 2, 1909 2,002,177 Hastings May 21, 1935 2,183,651 Langston et a1 Dec. 19, 1939 2,279,516 OBrien Apr. 14, 1942 2,295,214 Jackson Sept. 8, 1942 2,306,821 Markey Dec. 29, 1942 2,383,926 White Aug. 28, 1945 2,386,177 Andersen Oct. 9, 1945 2,440,279 Larkins, Jr. Apr. 27, 1948 2,443,654 Else et al June 22, 1948 FOREIGN PATENTS Number Country Date 53,218 Holland Sept. 16, 1942 102,071 Australia Sept. 30, 1937

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