US3125394A - Explosion proof plug and receptacle - Google Patents

Description

March 17, 1964 I A. I. APPLETON 3,125,394

- EXPLOSION PROOF PLUG AND RECEPTACLE Filed Oct. 28, 1960 4 S heets-Sheet 1 INVENT OR.

I Mai-ch 17, 1964 A. I. APPLETON EXPLOSION PROOF PLUG AND RECEPTACLE Filed Oct. 28, 1960 4 Sheets-Sheet 2 BY w mm; WQWM.

March 17, 1964 A. l. APPLETON EXPLOSION PROOF PLUG AND RECEPTACLE 4 Sheets-Sheet 3 Filed Oct. 28, 1960 March 17, 1964 A. 1. APPLETON EXPLOSION PROOF PLUG AND RECEPTACLE 4 Sheets-Sheet 4 Filed Oct. 28, 1960 United States Patent 3,125,394 EXPLOSION PROOF PLUG AND RECEPTACLE Arthur I. Appleton, Northbrook, Ill. (1713 Wellington Ave., Chicago 13, Ill.) Filed Oct. 28, 1960, Ser. No. 65,642 13 Claims. (Cl. 339-111) The present invention relates to electrical plugs and receptacles. More particularly the invention relates to explosion proof electrical fittings of the type comprising a telescopically operative plug and receptacle having cooperating terminals and incorporating a delayed action construction so that a momentary time delay occurs during insertion or withdrawal of the plug from the receptacle, in order to insure that any are formed between the respective terminals is extinguished before the plug and receptacle are completely separated.

The invention has, as its principal object, a simple and improved plug and receptacle structure affording positive, safe, and foolproof protection in explosive atmospheres.

More specifically, it is an object of this invention to incorporate into such a plug and receptacle an improved delayed withdrawal action between the plug and the receptacle in which it is telescopically received so that a delay is imparted as the plug terminals are separated from the receptacle terminals whereby any arc which is formed is extinguished before the plug is completely withdrawn from the receptacle.

Another object of the invention is to provide an improved plug and receptacle of the foregoing character in which a two step delayed withdrawal is provided in a simple and reliable manner and which device can be manually operated by even the most inexperienced user.

A more detailed object of the present invention is to provide a receptacle of the foregoing character which is foolproof in its operation and which cannot be tampered with to avoid a two step withdrawal of a plug without destroying the operation of the receptacle.

It is a further object of the invention to provide an improved two step type receptacle which can receive conventional type plugs and yet insures a two step withdrawal action. It is a related object to provide an improved plug which, While incorporating the objects of this invention, is interchangeable with conventional commercial receptacles.

Still another object of the invention is to mount a hinged cover on a receptacle of the foregoing character in such a manner that the receptacle can be easily and readily operated to receive or release a plug with a two step delayed action and yet can be completely closed when the plug is removed.

Still a further object of the invention is to provide an improved plug locking safety mechanism which prevents accidental disconnection of the plug and receptacle.

Other objects and advantages of the present invention will become apparent as the following description proceeds taken in connection with the accompanying drawings wherein:

FIGURE 1 is an elevation view of a plug and receptacle embodying the present invention.

FIG. 2 is a view taken substantially in the plane of line 2-2 of FIG. 1 and illustrating a plug mounted in the receptacle with the receptacle cover held open.

3,125,394 Patented Mar. 17, 1964 ice FIG. 3 is a view taken substantially in the plane of line 3-3 of FIG. 1 and illustrating the cover slide and lock arrangement.

FIG. 4 is a fragmentary section view of a plug and receptacle embodying the present invention with the plug in its initial stages of insertion or final stage of withdrawal from the receptacle.

FIG. 5 is a section View taken substantially in the plane of line 5-5 of FIG. 4.

FIG. 6 is a fragmentary section view of the plug and receptacle shown in FIG. 4 but with the plug in an intermediate position of engagement or withdrawal.

FIG. 7 is a section view taken substantially in the plane of line 7-7 of FIG. 6.

FIG. 8 is a fragmentary section view of the plug and receptacle shown in FIG. 4 and with the plug and receptacle in complete engagement.

FIG. 9 is a perspective view of a cover hinge and slide block used in the receptacle embodying the present invention.

FIG. 10 is an elevation view of a modified form of receptacle embodying the present invention.

FIG. 11 is a vertical section View through a plug and receptacle of the character shown in FIG. 10.

FIG. 12 is a section view taken substantially in the plane of line 12-12 on FIG. 11 and illustrating an improved cable clamping device.

FIG. 13 is a perspective view of a slide block used in the receptacle of the type shown in FIGS. 10 and 11.

FIG. 14 is a section view taken substantially in the plane of line 14-14 on FIG. 11 and illustrating a receptacle with the slide in position for initially receiving a plug.

FIG. 15 is a View similar to FIG. 14 but with the plug inserted and the slide in a position wherein the plug can be completely inserted within the receptacle.

FIG. 16 is a view similar to FIG. 14 but showing the plug completely inserted and the slide in a locking position.

FIG. 17 is a view taken substantially in the plane of line 17-17 of FIG. 11 and showing the terminals on the receptacle.

FIG. 18 is a fragmentary section view taken substantially in the plane of line 18-18 on FIG. 17 and illustrating a locking construction for the receptacle contacts.

While certain illustrative embodiments of the present invention have been shown in the drawings and will be described below in considerable detail, it should be understood that there is no intention to limit the invention to the specific forms disclosed. On the contrary, the intention is to cover all modifications, alternative constructions, equivalents and uses falling within the spirit and scope of the invention as expressed in the appended claims.

In general, my invention relates to an explosion proof plug and receptacle each having cooperating terminals therein. The plug is of a conventional type and has one or more radially extending arcuate shoulders thereon. In accordance with my invention, means are provided for applying a two step withdrawal for engagement between the plug and receptacle. To impart such a time delay, there is provided on the receptacle a hinged cover and slide, the slide providing a pair of opposed stops which engage with the shoulder on the plug as the plug is respectively inserted or withdrawn. In this manner, any are which might be formed between the corresponding terminals as they are separated is extinguished before the plug is completely withdrawn from the receptacle.

The socket member FIGS. 1-9 comprises a suitable tubular casing having mounted therein an internal insulating block 11 formed with axially extending chambers 12 in which are mounted terminals 13. These chambers are generally arc-tight passages which completely surround the terminals. The casing or housing is mounted on a siutable support by means of a mounting flange 14 through which electrical wires enter. These wires are secured to the terminals 13 on the terminal mounting block 11 which is mounted in the casing in an improved manner, shown in FIGS. 17 and 18, which will be described in detail.

The plug member likewise comprises a tubular casing 16 which is dimensioned to fit within the receptacle housing 10. For coaction with the receptacle terminals 13 there is mounted within the plug corresponding plug terminals 18. The latter are generally sleeve shaped members adapted to slide within the arc-tight chambers 12 and engage around the receptacle terminals 13. If desired, the various terminals may be of different sizes or cross sectional shapes so that the plug can be inserted in only one orientation.

The plug 16 is provided, at the end opposite from the terminals, with a suitable clamping device 19 for receiving and holding a cable 20 containing electrical wires, an improved form of which is shown in FIGS. 11 and 12 and will be described in detail. These wires are connected to the plug terminals by solder type connections in which the ends of the wires are permanently attached to the internal ends of the plug terminals 18.

The plug and receptacle construction thus far described, with the exception of the noted improvements, is generally conventional in the art. Many such plugs also include a pair of diametrically opposite radially extending projections 21, 22 which are are shaped and extend outwardly from the plug intermediate its ends. These shoulders conventionally serve as stops for use in delayed action devices now known in the art such as the device described in US. Patent 2,002,177. In order to orient the plug within the receptacle, these shoulders are also each a different slze.

In accordance with one aspect of the present invention, novel means are provided for obtaining a two step withdrawal of a plug from a receptacle which means makes use of a radially extending arcuate projection 22 on the plug. One illustrative means embodying the invention comprises a slide 25 shown in perspective in FIG. 9. Referring to FIGS. 1-9, the slide 25 is mounted in a sleevelike extension 26 of the receptacle housing 10 for transverse sliding movement with respect to the longitudinal axis of the receptacle and in position for selective engagement with one arcuate projection 22 on the plug 16. For providing the necessary stops to effect a delayed withdrawal, the upper surface of the slide 25 is formed with a pair of spaced parallel relieved or depressed arcuate areas 28, 29. These areas are connected by a channel 30 which defines, with the relieved areas, a pair of opposed spaced stop surfaces or shoulders 31, 32. These shoulders 31, 32 face each other but are spaced apart transversely along the slide 25.

The slide is mounted in the receptacle housing extension 26 for transverse sliding movement and the relieved areas are cut to a sutficient depth to receive and pass the plug shoulder 22. Referring more specifically to FIG. 9, as the plug 16 is inserted into the receptacle, the plug shoulder 22 passes through the first relieved area 23, in the direction of the dotted arrow a and engages against the stop shoulder 31. The slide is then pushed transversely, in the direction of the solid arrow A, so that the plug shoulder 22 is positioned in the channel 30 and in front of the second relieved area 29. The plug can then be inserted further into the receptacle, in the direction of the dotted arrow [7, so that the respective terminals are engaged. It will also be appreciated that when the terminals are engaged the slide cannot be returned inasmuch as the relieved area 29 will not slide past the plug shoulder 22. This sequence of steps is shown in FIGS. 4-8, inclusive.

In order to produce an improved and simplified plug delay action, the operation of the slide and cover are correlated. To this end, the slide supports a hinged cover for closing the open plug receiving end of the receptacle. For this purpose, the slide 25 includes a pair of spaced depending ears 34 provided at their lower ends with an aperture 35 in which a pivot pin 36 is received. This pin hingeably supports a cover 38, the cover having a hinge mounting portion 39 extending substantially at right angles to the main cover portion and provided with an aperture through which the pin 36 passes.

For holding the cover in an open position when a plug 16 is inserted into the receptacle 10, a suitable key and slot arrangement is provided between the cover 38 and a plate 4% which serves to hold the slide 25 in position on the receptacle. To this end, the plate 40 is generally T-shaped and extends between the ears of the slide and is secured at each of its extremities to the receptacle housing portion 26, as shown in FIG. 3. Depending from the plate at an intermediate point and between the ears of the slide is a key 41 adapted to engage in a slot 42 defined in the projecting hinge portion 39 of the cover 38. So that the cover may close when the plug is withdrawn, the projecting portion 39 includes a cut out or relieved area 43 (FIG. 5 which is wide enough to receive the key and allow the cover to swing upwardly under the force of a spring mounted between the cover and the receptacle. When the cover is swung downwardly to expose the receptacle, and a plug is inserted, the key 41 is initially positioned in front of the slot 42. After the plug is inserted so that the plug shoulder 22 engages the first stop shoulder 31, the slide and cover is then moved laterally relative to the receptacle. This positions the plug shoulder 22 in front of the relieved area 29 and at the same time engages the key 41 in the slot 42 on the cover 39. The cover is thus held open when the slide is moved so that it is not urged closed and does not ride up against the plug.

A modified form of plug and receptacle embodying the present invention is shown in FIGS. 10-18, inclusive. In this modification, the operation of the time delay slide and the cover is similarly correlated; however the slide is mounted for movement independent of the cover and the cover is mounted directly on the receptacle so that only the slide is moved back and forth. In describing this form of the invention, reference characters similar to those used above will be employed with the distinguishing addition of a prime mark. Thus, in describing this modification, the slide will be identified as element 25'.

In the modification shown in FIGS. 1018, as in the modification shown in FIGS. 19, there is provided a receptacle comprising a tubular casing 10, in which is mounted a terminal block 11, the casing having a mounting flange 14 by which the receptacle can be mounted on a junction box or the like. The receptacle is adapted to receive a plug comprising a tubular casing 16' dimensioned to fit within the receptacle casing 10 and carrying terminals 13' engageable with corresponding terminals 13' in the receptacle terminal block 11' (FIGS. 1416).

For receiving the plug with a time delay action, the receptacle is provided with a sleeve-like extension 26 as described above in which is mounted a transversely shiftable time delay slide 25' engageable with an extending arcuate projection 22' on the plug. As in the slide construction described above, the upper surface of the slide 25 is formed with a pair of spaced parallel relieved or depressed arcuate areas 28, 29. These areas are connected by a channel 30' which defines with the relieved areas 23', 2%, a pair of opposed spaced stop surfaces or shoulders 31, 32. As described above, these shoulders 31, 32 face each other but are spaced apart transversely along the slide 25. The operation of the slide is the same as described above in connection with the slide 25 shown in FIG. 9.

Referring more specifically to FIG. 13, as the plug is inserted into the receptacle, the plug shoulder 22 passes through the first relieved area 28, in the direction of the dotted arrow a and engages against the stop shoulder 31'. The slide is then pushed transversely, in the direction of the solid arrow A, so that the plug shoulder 22' is positioned in the channel 30 and in front of the second relieved area 29". The plug can then be inserted further into the receptacle, in the direction of the dotted arrow 17', so that the respective terminals are engaged. It will also be appreciated that when the terminals are engaged the slide cannot be returned inasmuch as the relieved area 29' will not slide past the plug shoulder 22'. This sequence of steps is shown in FIGS. 14-16 inclusive.

Provision is made in this modification for locking the plug against Withdrawal from the receptacle. To this end, a third relieved area 33 is provided along the edge of the slide opposite from the first relieved area 23' and opening into relieved area 29'. This relieved area defines a shoulder 37 opposite from shoulder 31. When the plug is completely inserted into the receptacle as shown in F168. 16 and 17, the slide 25 can 'be pushed partially back, in the direction of solid arrow B' to position the shoulder 37 behind the plug shoulder or projection 22', thereby locking the plug against withdrawal.

For enclosing the plug receiving opening of the receptacle, the construction of which is essentially the same as described above with reference to FIGS. 1-9, a cover 38 is hingeably supported between a pair of spaced depending ears 34 secured to a plate 45 fastened across a pair of lugs or ridges 46 depending from the receptacle housing 26'. The plate 45 together with the depending lugs 46 defines a slot 47 which opens into the interior of the receptacle housing 26. As described above, the hinge connection is formed by a pivot pin 36' mounted in apertures 35' in the depending cars 34 and a spring 48 mounted in an aperture 49 in the cover and engaged between the cover and the pin 36', serves to bias the cover to a closed position.

The slide 25 is positioned in the slot 47 defined in the portion 26' of the receptacle and enclosed by the plate 45 on which the cover is mounted. In this modification, the lower surface of the slide 25' is formed with an extending key 51) which projects through a slot 51 in the plate and is positioned for engagement with a slot and shoulder arrangement 42' (FIG. 16) defined in the projecting hinge portion 39 of the cover 38'. The slot portion 42 is constructed in a manner such that the cover may close when the plug is withdrawn and the slide 25 is positioned in the location shown in FIG. 14, that is with the slide extending outwardly of the slot towards the left. This is the position the slide assumes when moved in a direction opposite to the direction indicated by the solid arrow A shown in FIG. 13.

For engaging the slide and slide projection or key 5%), the projecting portion 39 of the hinge includes a cut out or relieved area 43' (FIG. 15) which is wide enough to pass the key 5t and allow the cover to swing upwardly under the force of the spring 48. When the cover 38 is swung downwardly to expose the receptacle and a plug is inserted thereinto, the key 5% being initially positioned in front of the slot 42 much in the manner described above, the plug shoulder 22 engages the first stop shoulder 31 of the slide 25. The slide is then moved laterally relative to the receptacle (in the direction of solid arrow A in FIG. 13). This positions the relieved area 29 of the slide in front of the plug shoulder 22' as described above, and at the same time engages the key 5th in the slot 42' on the cover portion 39' as shown in FIG. 15. The cover is thus held open and locked against the force of the spring. The plug is then pushed all the way into the receptacle effecting engagement of the respective contacts.

The locking means, including the relieved area 33 and shoulder 37 on the slide 25 serve to prevent any slight withdrawal of the plug which might disengage the contacts. As can be seen in FIGS. 13 and 16, the slide can be moved slightly back to lock the plug in position by engaging the plug shoulder 22' in the relieved area 33. When the slide is so moved (in the direction of solid arrow B in FIG. 13), one portion of the key 5t] remains engaged in the hinge slot 42 so that the cover is held open as shown in FIG. 16.

Successive steps in the insertion or withdrawal of a plug from a receptacle embodying the present invention are shown in detail in FIGS. 4-8, inclusive for the first modification, and in FIGS. 14- 16 for the second modification. Assuming that a plug has been completely inserted, as shown in FIG. 8, the plug terminals 1 8 are positioned within the chambers 12 and the respective plug and receptacle terminals 18 and 13 are engaged. The plug shoulders 211, 22 are positioned against the end of the receptacle housing 10 and within the auxiliary housing 26. The slide 25 is in its far right position as shown in FIG. 7 with the key 41 engaged in the slot 42 holding the cover 38 open. The first step in the withdrawal of the plug is to pull it outwardly as far as it will go so that the plug shoulder 22 engages the stop shoulder 32 on the slide as shown in FIG. 6. In this position the plug terminals -18 are disengaged from the receptacle tenminals 16 but have not been removed from the are tight chambers 12 so that any arc occurring between the receptacle and the plug terminals is extinguished. This position (FIG. 6) constitutes the first withdrawal step or delay step.

To remove the plug from the receptacle, the slide 25 is pushed to its far left position as shown in FIG. 5. As this is done the plug shoulder-22 slides through the channel 3d and is positioned in front of the second slide relieved area 28 as shown in FIG. 5. This step also removes the key 41 from the slot 42 and thereby releases the cover which can then swing upwardly. The plug is then removed, as shown in FIG. 4, with the plug shoulder 22 sliding out through the relieved area 28 in the slide. When the plug is removed the cover swings upwardly to its closed position and the receptacle is completely enclosed.

The reverse procedure is followed to insert the plug and receptacle. In this procedure as the slide is moved to the right the cover is engaged with the key depending from the slide plate so that the cover is held in an open position. As a safety feature, the cover must be held open when the plug is inserted. Otherwise, the slide cannot be moved to release the plug for insertion in the receptacle. Similarly, the slide cannot be manipulated to permit the plug to be withdrawn in one continuous step. Starting with a closed receptacle, the operation of the unit is obvious and foolproof even when used by those inexperienced in handling heavy duty explosion proof connectors, and most important, the construction insures that a two step withdrawal of the plug from the receptacle must be followed so that any danger of an arc igniting an explosive atmosphere surrounding the fitting is eliminated.

In addition to the above desirable features, the plug and receptacle construction embodying the invention has additional features which serve to enhance the ease of coupling the members together and improve the gripping of the cable attachment portion of the plug and thereby facilitate handling of the plug. While the arcuate shoulders 21, 22 afford an orienting action and also allow some play to facilitate alinement of the plug and receptacle contacts, means are provided to accommodate the plug and receptacle contacts to slight misalinement of the contacts when the plug is force ably inserted into the receptacle. This is embodied in the receptacle and particularly in an improved contact block structure. AS shown in the drawings, the improved receptacle contact insulating block 11 is mounted within the receptacle housing in a manner affording slight rotary movement. This has been found not only to facilitate insertion of the plug but also to substantially simplify the assembly of the receptacle contact and the mounting of the contact block 11 in the receptacle housing 10. This structure is shown in detail in FIGS. 11 and 17.

The terminal mounting or insulating block 11 is formed with means by which it may be removably mounted in the casing 10. One illustrative means, shown in FIGS. 11, 17 and 18, comprises a threaded portion on the block 11 behind the contact carrying portion. The threaded portion 55 terminates in an annular radially extending rear shoulder 56 defined by a rearrnost body member 53 which includes a plurality of apertures 59 in which are mounted terminal clips 61% which are electrically connected with the contact terminals 13 in the chambers 12 of the insulating block. The block 11 is threadably secured within the casing 16 and is held in place by a screw 61 and washer 62 arranged on the casing. The washer extends over the shoulder 56, as shown in FIG. 18, to prevent the withdrawal of the block 11. To accommodate the washer to engagement with the shoulder 56, the latter includes a cutout portion 64, which is slightly larger than the washer, so that some play is permitted between the washer 62 and the insulating block 11. This provision of play between the washer 62 and the block 11 enables the block 11 carrying the contacts to rotate slightly when mounted in the casing and in this manner accommodate the plug and receptacle contacts in cases of slight misalignment.

As still another feature of the present invention, improved means are provided for use in gripping the plug for withdrawing it from or inserting it into the receptacle, which gripping means contemplates the inclusion of means for securing the cable thereby to avoid loosening the cable connection. One such an illustrative means is shown in FIGS. 11 and 12 of the drawings and comprises a cable gripping and sealing member, indicated generally at 65, wluch can be mounted in sealing relationship with the exposed end of the plug housing 16 and which includes a cable gripping means or clamp 66. More specifically, the cable gripping and sealing means comprises an outwardly flared sleeve-shaped member 68 having a flange portion 69 at one end thereof defining a bore 79 through which a cable 71 extends. The flange and bore terminate in a counterbore '72 defined by the sleeve-shaped member 68 in which the cable gripping clamp 66 is mounted. A second counterbore 74 is defined by an extending sleeve portion 75 of the member 68 which surrounds the end of the plug casing 16. The counterbore sleeve portion 75 defines with the intermediate bore 72 an internal shoulder 76 against which is positioned an annular washer member 78 having an internal aperture '79, the diameter of which is approximately equal to that of the flange bore 70. This washer is supported within the member 68 by means of a pair of threaded screws 8t each having a reduced shank 81 extending through the body portion defining the bore 72. The screws 89 are formed with a head 82, and a fiber washer 84- on the shank 31 serves to hold the washer '78 in place. The threaded end of the screws are engaged with tapped holes in the end of the plug housing 16.

For purposes of gripping the cable within the housing 65 the cable clamp 66 is formed with a pair of opposed clamp members 85 (FIG. 12) each having a shallow arcuate center portion 86 engageable with opposite side portions of a cable. For gripping the cable 71, the arcuate portion 66 of the cable clamp members 35 has an outwardly punched portion 8% defining at the inner surface a recess 39 (FIG. 11) so that when the clamp is tightened against the cables the resilient cable sheath is deformed into this recess. As a result the gripping action of the clamp on the cable is substantially increased. The clamp members 85 are tightened together by a pair of opposed bolts 90 each of which is threaded to receive a clamping nut 91. The clamp members are formed with suitable apertures through which the bolts extend and the bolts are oriented in opposite directions with respect to each other so that when they are tightened the clamp members are squeezed together and grip the cable. In order to center the cable and hold it tightly within the housing 65, one end of each clamp member 85 is engaged in a slot )2 formed in the interior wall of the sleeve-shaped member 68 (FIG. 12). When the clamp bolts 86 are tightened, the ends of the clamping members 85 are held within the slots 92 and each member 85 tends to swing about that end as a pivot. The clamping bolts 96 extend through the wall of the member 68 and are provided with a suitable head 94 on their outer ends for receiving a screwdriver or the like. In order to afford an outer surface on the sleeve 68 which is free of projections, each clamping screw head Wt is recessed in a suitable aperture 95 in the surface of the member 68.

For purposes of sealing the clamping member sleeve or body 68 onto the end of the plug casing "16, there is provided a sealing member 98. This sealing member 98 is formed of a resilient, compressible material, for example a suitable flexible compound such as neoprene rubber or the like, which is compressed into sealing relation with the cable and the plug when positioned within the counterbore. In order to sealingly engage the plug, the sealing member 98 is provided with a tapered external surface 87 which fits within a correspondingly tapered bore or socket 99 in the end of the plug housing 16. To 'sealingly grip the cable, the internal surface of the resilient sealing member 98 is preferably roughened such as by the provision of suitable corrugations or threads 1%. To seal the cable 71 into the plug, the clamping member 65 is tightened onto the end of the plug 16 so that resilient member 98 is squeezed tightly into engagement with both the sealing washer 78 and the tapered surface $9 of the plug casing 16. At the same time this compressing action will squeeze the corrugations 1% tightly into engagement with the outer sheath of the cable thereby effecting an explosion proof and a weather proof seal which is effective to prevent the access of moisture, gases, and the like to the interior of the plug where the terminal clips are located.

It will be appreciated that, in addition to the above features, many others are provided. The enlarged outwardly flaring outer surface of the body portion or sleeve 68 will afford a grip on the end of the plug for easing the insertion and withdrawal of the plug from the receptacle. A waterproof seal is effected by the cooperation between the internal washer 71 and the resilient sealing member 85. At the same time, the washer 71 and sleeve 63 affords a suitable housing for the clamping members 76. Furthermore, the body portion 62 with the notches 92 afford a novel means for cooperating with the cable clamps to securely grip the cable and thereby relieve the plug terminal clips from any strain should the plug be removed by pulling on the cable, while at the same time a smooth, projection free, yet substantial gripping surface is provided on the cable end of the plug.

This application is a continuation-in-part of my copending application, Serial No. 852,082, filed November 10, 1959 and now abandoned.

I claim as my invention:

1. An explosion proof receptacle for use with a plug having a plug body carrying a plurality of plug terminals extending therefrom, an annularly extending plug housing surrounding said plug terminals, and a radially extending arcuate shoulder on the outer surface of the plug housing, said receptacle comprising a receptacle body mounting a terminal block having a plurality of receptacle terminals telescopically engageable with the plug terminals, an

annular receptacle housing extending from said receptacle body in spaced surrounding relation with said terminal block, said plug housing being received within said receptacle housing and closely surrounding said terminal block when the receptacle terminals are engaged with the plug terminals, a slide member mounted on said receptacle housing for transverse sliding movement with respect thereto between opposite positions, said slide member having means thereon defining opposed transversely spaced stop shoulders for successively engaging the plug shoulder upon transverse movement of said slide member from one to the other of said opposite positions so as to afford a two step delayed withdrawal and insertion of the plug respectively from and into the receptacle, a cover hingedly mounted on said slide and biased for closing the receptacle when the plug is removed therefrom and the slide is in one of said opposite positions, and means on said receptacle housing engageable with said cover for holding the same open when the slide is in the other of said opposite positions wherein the plug is inserted in place within the receptacle.

2. An explosion proof receptacle for use with a plug having a plug body carrying a plurality of plug terminals extending therefrom, an annularly extending plug housing surrounding said plug terminals, and a radially extending arcuate shoulder on the outer surface of the plug housing, said receptacle comprising a receptacle body mounting a terminal block having a plurality of receptacle terminals telescopically engageable with the plug terminals, an annular receptacle housing extending from said receptacle body in spaced surrounding relation with said terminal block, said plug housing being received Within said receptacle housing and closely surrounding said terminal block when the receptacle terminals are engaged with the plug terminals, a slide member mounted on said receptacle housing for transverse sliding movement with respect thereto between opposite positions, said slide member having means thereon defining opposed transversely spaced stop shoulders for successively engaging the plug shoulder upon transverse movement of said slide member from one to the other of said opposite positions so as to afford a two step delayed withdrawal and insertion of the plug respectively from and into the receptacle, a cover having an arm fixed thereto hingedly mounted on said slide, means engaged between said arm and said slide for biasing said cover to close the receptacle when the plug is removed therefrom and the slide is in one of said extreme positions, a key member on said receptacle housing, and means defining a slot on said cover arm engageable with said key for holding the cover open when the slide is in the other extreme position wherein the plug is inserted in place Within the receptacle.

3. An explosion proof receptacle for use with a plug having a plug body carrying a plurality of plug terminals extending therefrom, an annularly extending plug housing surrounding said plug terminals, and a radially extending arcuate shoulder on the outer surface of the plug housing, said receptacle comprising a receptacle body mounting a terminal block having a plurality of receptacle terminals telescopically engageable with the plug terminals, an annular receptacle housing extending from said receptacle body in spaced surrounding relation with said terminal block, said plug housing being received within said receptacle housing and closely surrounding said terminal block when the receptacle terminals are engaged with the plug terminals, a slide member mounted on said receptacle housing for transverse sliding movement with respect thereto between opposite extreme positions, said slide member having means defining a first outer relieved area for receiving the plug shoulder when the slide is in one extreme position and having means defining a second relieved area parallel to and spaced from the first area for successively receiving the plug shoulder when the slide is in its other extreme position, said slide further having means defining a channel connecting the two relieved areas for receiving the plug shoulder as the slide is moved between its extreme opposite positions, said channel and relieved area defining means forming opposed stop shoulders for engaging the plug shoulder to afford a two step delayed withdrawal and insertion of the plug respectively from and into the receptacle, a cover hingedly mounted on said slide and biased for closing the receptacle when the plug is removed therefrom and the slide is in said one extreme position, and means on said receptacle housing engageable with said cover for holding the same open when the slide is in the other extreme position wherein the plug is inserted in place within the receptacle.

4. A retardation means for use with explosion proof electrical connectors including a separable plug having a radial shoulder thereon and a receptacle telescopically receiving the plug, said means comprising a slide mounted on said receptacle for movement transverse to the telescoping axis thereof between opposite positions, said slide having relieved areas thereon defining opposed transversely spaced stop shoulders for stepwise engagement with the plug shoulder upon transverse movement of said slide member from one to the other of said opposite positions so as to atford stepwise delayed insertion and withdrawal of the plug respectively into and from the receptacle, a cover hingedly mounted on said slide for closing said receptacle when the plug is withdrawn therefrom, and means on said receptacle engaging said cover to hold the same open when the slide is in position with the plug completely received within the receptacle.

5. An explosion proof receptacle for use with a plug having terminals therein and a radially extending arcuate shoulder thereon, said receptacle comprising a housing having terminals for cooperatively receiving the plug terminals, a slide member mounted on said receptacle for sliding movement transverse to the longitudinal axis thereof and having means defining a first outer relieved area for receiving the plug shoulder when the slide is in one extreme position, means defining a second relieved area parallel to and spaced from the first area for successively receiving the plug shoulder when the slide is in its other extreme position, and means defining a channel connecting the two relieved areas for receiving the plug shoulder as the slide is moved between its extreme positions, said channel and relieved area defining means forming spaced opposed shoulders which serve as stops against which the plug shoulder abuts when the plug is being inserted into and removed from the receptacle.

6. An explosion proof receptacle for use with a plug having terminals therein and a radially extending arcuate shoulder thereon, said receptacle comprising a housing having terminals for cooperatively receiving the plug terminals, a slide member mounted on said receptacle for sliding movement transverse to the longitudinal axis thereof, said slide having means defining a first outer relieved area for receiving the plug shoulder when the slide is in one extreme position, said slide having means defining a second relieved area parallel to and spaced from the first area for successively receiving the plug shoulder when the slide is in its other extreme position, said slide having means defining a channel connecting the two relieved areas for receiving the plug shoulder as the slide is moved between its extreme positions, said channel and relieved area defining means forming spaced opposed shoulders which serve as stops against which the plug shoulder abuts when the plug is being inserted into and removed from the receptacle, a cover hingedly mounted on said slide, and means biasing said cover to close the receptacle when the plug is removed therefrom.

7. An explosion proof receptacle for use with a plug having a plug body carrying a plurality of plug terminals extending therefrom, an annularly extending plug housing surrounding said plug terminals, and a radially extending arcuate shoulder on the outer surface of the plug housing, said receptacle comprising a receptacle body mounting a terminal block having a plurality of receptacle terminals telescopically engageable with the plug terminals, an annular receptacle housing extending from said receptacle body in spaced surrounding relation with said terminal block, said plug housing being received within said receptacle housing and closely surrounding s id terminal block when the receptacle terminals are engaged with the plug terminals, a slide member mounted on said receptacle housing for transverse sliding movement with respect thereto between opposite positions, said slide member having means thereon defining transversely spaced stop shoulders for successively engaging the plug shoulder upon transverse movement of said slide member from one to the other of said opposite positions so as to afford a two step delayed withdrawal and insertion of the plug respectively from and into the receptacle, a cover hingedly mounted on said receptacle housing and biased for closing the receptacle when the plug is removed therefrom and the slide is in one of said opposite positions, and means on said slide engageable with said cover for holding the same open when the slide is in the other of said opposite positions wherein the plug is inserted in place Within the receptacle.

8. An explosion proof receptacle for use with a plug having a plug body carrying a plurality of plug terminals extending therefrom, an annularly extending plug housing surrounding said plug terminals, and a radially extending arcuate shoulder on the outer surface of the plug housing, said receptacle comprising a receptacle body mounting a terminal block having a plurality of receptacle terminals telescopically engageable with the plug terminals, an annular receptacle housing extending from said receptacle body in spaced surrounding relation with said terminal block, said plug housing being received within said receptacle housing and closely surrounding said terminal block when the receptacle terminals are engaged with the plug terminals, a slide member mounted on said receptacle housing for transverse sliding movement with respect thereto between opposite positions, said slide member having means thereon defining transversely spaced stop shoulders for successively engaging the plug shoulder upon transverse movement of said slide member from one to the other of said opposite positions so as to afford a two step delayed Withdrawal and insertion of the plug respectively from and into the receptacle, a cover having an arm fixed thereto hingedly mounted on said receptacle housing, means engaged between said arm and said receptacle housing for biasing said cover to close the receptacle when the plug is removed therefrom and the slide is in one of said extreme positions, a key member on said slide, and means defining a slot on said cover arm engageable with said key for holding the cover open when the slide is in the other extreme position wherein the plug is inserted in place within the receptacle.

9. A retardation means for use with explosion proof electrical connectors including a separable plug having a radial shoulder thereon and a receptacle telescopically receiving the plug, said means comprising a slide mounted on said receptacle for movement transverse to the telescoping axis thereof between opposite positions, said slide having relieved areas thereon defining transversely spaced stop shoulders for stepwise engagement with the plug shoulder upon transverse movement of said slide member from one to the other of said opposite positions so as to afford stepwise delayed insertion and withdrawal of the plug respectively into and from the receptacle, a cover hingedly mounted on said receptacle for closing said receptacle when the plug is withdrawn therefrom, and means on said slide engaging said cover to hold the same open when the slide is in position with the plug completely engaged within the receptacle.

10. An explosion proof receptacle for use with a plug having terminals therein and a radially extending arcuate shoulder thereon, said receptacle comprising a housing having terminals for cooperatively receiving the plug terminals, a slide member mounted on said receptacle for sliding movement transverse to the longitudinal axis thereof and having means defining a first outer relieved area for receiving the plug shoulder when the slide is in one extreme position, means defining a second relieved area parallel to and spaced from the first area for successively receiving the plug shoulder when the slide is in its other extreme position, means defining a channel connecting the two relieved areas for receiving the plug shoulder as the slide is moved between its extreme positions, said channel and said first and second relieved area defining means forming spaced opposed shoulders which serve as stops against which the plug shoulder abuts when the plug is being inserted into and removed from the receptacle, and said slide having means defining a third relieved area parallel to and spaced from said first and second areas and opening directly into said second area for receiving the plug shoulder when the plug is completely inserted in the receptacle and the slide is in an intermediate position thereby locking the plug in the receptacle.

11. An explosion proof receptacle for use with a plug having a plurality of terminals extending therefrom, said receptacle comprising a sleeve-like body having an internally threaded bore in one end, a terminal block having at one end a plurality of receptacle terminals telescopically engageable with the plug terminals, means formed on said receptacle for cooperating with the plug so as to orient said receptacle terminals in substantially axial alignment with the plug terminals, the other end of said block having an external threaded portion for threadably engaging within said threaded body, means defining a shoulder on the threaded end of said block, said block having an enlarged arcuate relieved portion adjacent said shoulder, and means on said body extending into said enlarged arcuate relieved portion and loosely engaging said shoulder, whereby said terminal block is free for limited rotation with respect to said sleeve-like body so that the receptacle terminals align themselves with the plug terminals when the plug is inserted into the receptacle while maintaining said receptacle explosion proof.

12. An explosion proof receptacle for use with a plug carrying a plurality of plug terminals, said receptacle comprising a body having a threaded bore in one end thereof and an enlarged annular housing portion extending from the other end thereof, a terminal block mounted within said annular housing and having at one end a plurality of receptacle terminals telescopically engageable with the plug terminals, means formed on said housing for cooperating with the plug so as to orient said receptacle terminals in substantially axial alignment with the plug terminals, the other end of said block having a threaded portion for engaging within said threaded body, said threaded portion terminating in a reduced diameter portion defining a radial shoulder, said reduced diameter portion of said block having an arcuate notch adjacent said shoulder, and means on said body loosely engaging said shoulder and extending into said arcuate notch for preventing the withdrawal of said terminal block from said body whereby said block is free for limited rotation within said body so that said receptacle terminals align themselves with the plug terminals when the plug is inserted into the receptacle while maintaining said receptacle explosion proof.

13. An explosion proof receptacle for use with a plug carrying a plurality of plug terminals, said receptacle comprising a body having a threaded bore in one end thereof and an enlarged annular housing portion extending from the other end thereof, a terminal block mounted within said annular housing and having at one end a plurality of receptacle terminals telescopically engageable with the plug terminals, means formed on said housing for cooperating with the plug so as to orient said receptacle terminals in substantially axial alignment with the plug terminals, the other end of said block having a threaded portion for engaging within said threaded body, said threaded portion terminating in a reduced diameter portion, and means on said body loosely engaging said block for preventing the Withdrawal of said terminal block from said body while permitting limited relative rotational movement between said block and said body, whereby said receptacle terminals align themselves with the plug terminals when the plug is inserted into the receptacle While maintaining said receptacle explosion proof.

Riley Apr. 29, 1924 Cannon Apr. 22, 1930 14 Meuer Oct. 18, 1932 To'rnblom Apr. 12, 1938 Wulle et al May 5, 1942 Richardson et al Nov. 30, 1948 Quackenbush Apr. 15, 1952 Howard et al Jan. 27, 1953 Castelli Dec. 14, 1954 Swanson et al Aug. 9, 1955 Petree Sept. 10, 1957 FOREIGN PATENTS Switzerland June 15, 1959

Claims (1)

1. AN EXPLOSION PROOF RECEPTACLE FOR USE WITH A PLUG HAVING A PLUG BODY CARRYING A PLURALITY OF PLUG TERMINALS EXTENDING THEREFROM, AN ANNULARLY EXTENDING PLUG HOUSING SURROUNDING SAID PLUG TERMINALS, AND A RADIALLY EXTENDING ARCUATE SHOULDER ON THE OUTER SURFACE OF THE PLUG HOUSING, SAID RECEPTACLE COMPRISING A RECEPTACLE BODY MOUNTING A TERMINAL BLOCK HAVING A PLURALITY OF RECEPTACLE TERMINALS TELESCOPICALLY ENGAGEABLE WITH THE PLUG TERMINALS, AN ANNULAR RECEPTACLE HOUSING EXTENDING FROM SAID RECEPTACLE BODY IN SPACED SURROUNDING RELATION WITH SAID TERMINAL BLOCK, SAID PLUG HOUSING BEING RECEIVED WITHIN SAID RECEPTACLE HOUSING AND CLOSELY SURROUNDING SAID TERMINAL BLOCK WHEN THE RECEPTACLE TERMINALS ARE ENGAGED WITH THE PLUG TERMINALS, A SLIDE MEMBER MOUNTED ON SAID RECEPTACLE HOUSING FOR TRANSVERSE SLIDING MOVEMENT WITH RESPECT THERETO BETWEEN OPPOSITE POSITIONS, SAID SLIDE MEMBER HAVING MEANS THEREON DEFINING OPPOSED TRANSVERSELY SPACED STOP SHOULDERS FOR SUCCESSIVELY ENGAGING THE PLUG SHOULDER UPON TRANSVERSE MOVEMENT OF SAID SLIDE MEMBER FROM ONE TO THE OTHER OF SAID OPPOSITE POSITIONS SO AS TO AFFORD A TWO STEP DELAYED WITHDRAWAL AND INSERTION OF THE PLUG RESPECTIVELY FROM AND INTO THE RECEPTACLE, A COVER HINGEDLY MOUNTED ON SAID SLIDE AND BIASED FOR CLOSING THE RECEPTACLE WHEN THE PLUG IS REMOVED THEREFROM AND THE SLIDE IS IN ONE OF SAID OPPOSITE POSITIONS, AND MEANS ON SAID RECEPTACLE HOUSING ENGAGEABLE WITH SAID COVER FOR HOLDING THE SAME OPEN WHEN THE SLIDE IS IN THE OTHER OF SAID OPPOSITE POSITIONS WHEREIN THE PLUG IS INSERTED IN PLACE WITHIN THE RECEPTACLE.

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