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Publication numberUS3284591 A
Publication typeGrant
Publication dateNov 8, 1966
Filing dateOct 9, 1964
Priority dateOct 9, 1964
Publication numberUS 3284591 A, US 3284591A, US-A-3284591, US3284591 A, US3284591A
InventorsDaly Daniel F
Original AssigneeArrow Hart & Hegeman Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Enclosed switch with cover switch and connector interlocking means
US 3284591 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

Nov. 8, 1966 D. F. DALY 3,284,591


00/7/6/ F [Ba/y BY h/s affomeys D. F. DALY Nov. 8, 1966 3,284,591 ENCLOSED SWITCH WITH COVER SWITCH AND CONNECTOR INTERLOCKING MEANS 2 Sheets-Sheet 2 Filed Oct. 9, 1964 INVENTOR 00/7/6/ F flo/ BY his affameys United States Patent Ofitice 3,284,591 ENCLOSED SWITCH WITH COVER SWITCH AND CONNECTOR INTERLOCKING MEANS Daniel F. Daly, Newington, Conn., assignor to The Arrow- Hart & Hegeman Electric Company, Hartford, Conn.,

a corporation of Connecticut FiledOct. 9, 1964, Ser. No. 402,763 6 Claims. (Cl. 200-50) This invention relates to enclosed electric switches in which the cover of the enclosure is interlocked with the switch and cannot be opened when the switch is in closedcircuit position. More particularly, the invention relates to the provision in such switches of detachable connectors which cannot be separated or connected while the switch is in closed-circuit position.

By error or mistake, plug-in connectors frequently are disconnected from receptacles which are located in the electric switch boxes. When separation takes place while the power is on, or when connection is made while a heavy load remains on the load side, arcing occurs resulting in a hazard to the hand of the operator. On occasion severe arcing will cause burns and possibly electrically shock the operator. At high voltages, for example around 600 volts, the operator would be lucky if he did not suffer more serious injury or death.

Therefore, one object of this invention is to provide an improved interlocking arrangement between a connector plug, its socket and a control switch mechanism which prevents the plug from being withdrawn while the switch is closed, but which allows the connector parts to be separated when the switch is in open-circuit position.

A still further object is to provide, in interlocking connector and switch combinations having the foregoing characteristics, means for preventing connection of the connector parts while the switch is closed.

Another object is to provide an interlocking arrangement as aforesaid, applicable to an enclosed switch and to a connector of the ordinary rectilinear plug-in type, which will prevent completion of the insertion of the plug if, after it has been only partly inserted, the switch is moved toward closed-circuit position, and which will also prevent switch closing after the plug has been partly inserted.

Another object of the invention is to provide an improved interlocking connector and enclosed switch combination wherein the cover of the switch enclosure can only be opened when the switch is in open-circuit position and in which a separable connector is associated with the enclosure and switch in such manner that the connector parts can only be separated when the switch is in open-circuit position. An associated object is to provide such interlocking means when one connector part is within the enclosure.

Other objects and advantages of the invention will occur to those skilled in the art as the invention is described in connection with the accompanying drawing.

In the drawings:

FIG. 1 is a top plan view, partly broken away, of a switch casing and operating mechanism embodying the invention with the switch contacts omitted.

FIG. 2 is a side elevation view, partly broken away, of the device as illustrated in FIG. 1, but with the plug inserted part way.

FIG. 3 is a fragmentary view partly in section and partly broken away illustrating the interrelation between the interlocking bar, pin and shells of the plug and receptacle with the plug fully inserted and switch open.

FIG. 4 is a view similar to FIG. 3 with the plug fully inserted and switch closed.

FIG. 5 is a view similar to FIG. 3 with the plug partially inserted and the switch attempting to close.

3,284,591 Patented Nov. 8, 1966 2 FIG. 6 is an end view of the top portion of the structure shown in FIGS. 3, 4 and 5.

FIG. 7 is a fragmentary perspective view of the end of the interlocking bar.

FIG. 8 is a view similar to FIGS. 3 and 4, but of a modified form of locking pin and lock bar.

Referring to the drawings, a rectangular metal box having side walls 10, 10a, end walls 12, 12a and bottom wall 14 and hinged cover 16 contains a fused knife-blade switch operable between open and closed positions, as is customary. A pivoted handle 19 is mounted in the side walls 10 of the box for operating the switch contacts.

The mechanism for operating the switch may be interlocked with the cover as disclosed in the copending application Serial No. 286,443 of Daniel F. Daly and Joseph M. OMalley entitled Cover and Switch Interlock, or by any other suitable interlocking mechanism which pre vents opening of the cover when the switch is closed and closing of the switch when the cover is open. In such mechanism, a bail 20 is commonly used, being pivotally mounted at its ends 202 for swinging movement as the switch operating mechanism is actuated in response to movement of the handle. The bail movement operates the switch contacts (not shown) between open and closed positions, as is customary.

Integral with or secured to the bail is an arm or crank member 22 which is within the box and pivots with the bail 20 to the crank portion of which it is afiixed. Connected pivotally to the free or swinging end of the crank arm 22 by a pin 23 is an interlocking bar or rod 24 which extends toward the end wall 12 of the box and is movable lengthwise as the crank arm 22 swings between open and closed positions.

In the end of wall 12 (which may be inclined for convenience in inserting and removing a connector plug member 40, hereinafter described) is an attachment plug receptacle 40 for receiving such connector plug.

The receptacle is armored and comprises a metallic shell designated generally by numeral 32 of aluminum or other suitable metal or material. The shell is cylindrical in shape and secured to the box end 12 by screwbolts 31 passing through a fiange 33 radially extending from the shell and lying flush against the outside surface of the end wall 12. The shell has portions 32c and 32a extending respectively both inside and outside the box wall 12 through an aperture therein.

Secured to or formed integral with the shell at its inner end 32c is an end 34 on which is mounted an insulating block of electrically insulating material, designated generally by numeral 35. A portion 35a of such insulating block extends through the end wall of the shell into the switch box while the opposite portion 350 extends oppositely and within the shell and has formed therein a plurality of separate recesses in which are located a plurality of spring contact fingers 36. These are fixedly secured in the portion 350 of the insulating body and point parallel to the shell axis toward the outside of the switch box. Conventional connector wires 37 are attached in anyconvenient way to the contact fingers 36 and lead from the inner end of the insulating block portion 350 to the switch contacts, as usual.

If desired, the outer end of the shell may be closed, when not in use, by a cover 38 hinged on the shell (as shown) and biased closed by a spring (not shown).

For connection to and engagement with the receptacle, an armored plug 40 is provided comprising a shell made of metal or other suitable material in generally cylindrical or tubular shape and having an open-ended cylindrical protective sleeve 42 of less diameter than the receptacle shell 32 so as to be insertable into the latter. This plug shell is closed at its other end except for an aperture for entrance of conductor wires that are attached in conventional fashion to contact prongs 46. These prongs are equal in number to the receptacle fingers 36, but are or may be of hollow tubular form to receive and slide over the receptacle fingers 36 with which they are adapted to register as the plug and receptacle are connected together. The plug contact prongs 46 are mounted in and extend from an insulating block 45 which insulatingly supports them and is mounted itself in and is secured to the plug shell 40.

The sleeve 42 extends beyond the prongs 46 so as to protect them from injury or damage in case of rough handling of the plug. The extension of the sleeve 42 beyond the contact prongs also serves to prevent engagement of the prongs with the receptacle fingers 36 if the switch is closed before insertion of the plug is attempted, I

as will hereinafter more fully appear.

In order to prevent such insertion and also to prevent withdrawal of the plug when the switch is closed, a radially movable interlocking pin 50 is mounted slidably within an axial passageway in a stud 56 having a screwthreaded reduced neck 57 at one end adapted to screw into a tapped radial hole in the side of the inner portion 320 of the receptacle shell.

The pin 50 has a reduced shank 52 within the stud 56. To bias the pin radially inwardly, a compression spring 54 is coiled around the shank 52 and presses at one end on a shoulder between the shank and the innermost end of the pin. The other end of the spring presses against a shoulder at the opposite end of the passageway through the stud. Thus, the spring biases the pin radially inward toward the plug. The pin is adapted to enter a hole 42h in the sleeve 42 of the plug, as shown in FIG. 4, when the contacts 46 of the plug are fully engaged with the receptacle contacts 36.

In order to retract the interlocking pin 50 and allow the plug to be withdrawn when the switch is moved to open position, the end of the interlocking bar 24 and outer end of the pin 50 and stud 56 are formed and interengage as follows.

The extremity of the interlocking bar is bifurcated and upwardly bent obliquely, forming cam surfaces 24c. Between the bifurcations 24b of the interlocking bar projects a neck 53 outwardly extending from the reduced shank 52 of the interlocking pin 50 and of still smaller diameter than such shank. The neck 53 merges into an enlarged disc-like head 55 on the interlocking pin via diverging conical surface 550 having the same angularity as the cam surface 24c on the interlocking bar 24. The neck merges into the shank of the pin 52 via diverging conical surface 520.

The pin and stud assembly 50-56 is so positioned with relation to the end of the interlocking bar 24, that in closed position of the switch, the cam surface 24c lies to the right of the conical surface 550 and of the head 55 (as viewed in FIG. 4), with the surfaces 550 and 240 touching.

. As the interlocking bar 24 is moved to the left from the position of FIG. 4 to the position of FIG. 3 when the switch mechanism is moved from closed to open position, cam surface 24c of the interlocking bar acts onthe conical surface 550, elevating and retracting the pin 50 against the bias of the spring 54 until the position of FIG. 3 is reached at which time the pin 50 is withdrawn from the hole 42h in the sleeve of the plug. This frees the plug so that it may be pulled from the receptacle.

To support the end of the interlocking bar as it slides during its movement between switch-open and switchclosed positions, two small L-shaped angle brackets 25 are welded, brazed or otherwise suitably secured to the side edges of. the insulating bar 24, one bracket being opposite to the other near the end of the bar at about the point where the bifurcations bend. The feet 25' of the angle brackets are in-turned toward each other to lie in the same plane and enter opposite sides of a peripheral groove 58 formed in the stud 56 just inward of its outer end. These angle brackets 25 engage the groove walls to support the bifurcations of the insulating bar during outward camming of the interlocking pin 50; and the groove 58 also guides the interlocking bar in its back and forth sliding motion during switch-opening and switch-closing movement.

Should the switch be reclosed while the plug is not in the receptacle, the movement of the insulating bar will release the interlocking pin 50 so that the spring 54 will force it inwardly. If an attempt is made to insert the plug into the receptacle (while the switch remains closed), the end of the plug sleeve will abut up against the pin 50 as shown in FIG. 2, preventing inward movement of the plug sufliciently to engage the plug contacts 46 with the receptacle contacts 36. To accomplish this, the pin 50 is so located on the receptacle shell 320 with relation to the position of the tips of receptacle contacts 36 that when the end of the plug shell 42 abuts the pin, the receptacle contacts and plug prongs are out of contact. Thus, destructive arcing at the plug and receptacle contacts is prevented and damage to personnel is avoided.

If the switch is open and the plug is partly inserted (such as to the position illustrated in FIG. 5) and then the switch is moved from the open position of FIG. 3 toward the closed position, the interlocking bar will start to move from the position of FIG. 3 toward the position of FIG. 4, but the bar will only be able to move to the position of FIG. 5 and the interlocking pin will only be able to move until its inner end engages the sleeve 42 of the plug. In the FIG. 5 position, the switch contacts will still be open and the interlocking mechanism will jam, preventing further switch closing movement. Such jamming occurs by reason of the fact that the end of the interlocking bar has the bottom or inner surface (as viewed in FIGS. 3, 4, 5 and 7) engaged with the conical shoulder 520 while the top or outer surface of the interlocking bar is engaged with the conical under-surface 550 of the head 55 of the locking pin.

The locking bar must move rectilinearly because t he feet of legs 25 are guided by the edges of the groove 58 while the bar pressing on the conical surface 52c tends to move the pin in. But such movement of the pin is blocked by the plug shell. Thus, the switch cant close until the plug is fully inserted and hole 42h is in register with the pin 50.

In FIG. 8, a modified form of locking pin and lock bar is illustrated wherein a cylindrical stud 156 has a cylindrical pin 152 slida'bly mounted in an axial passageway as before, but the pin is normally urged into unlocking position or outwardly by a coiled compression spring 154. The head or outer end of the pin is beveled as at 152a to provide a cam surface and, when outwardly urged to fullest extent, as in unlocking position, the beveled head lies within a diametrical bore 156b through the outer end portion of stud 156.

Slidable within this bore 156b is a short. circular cam rod 160, one end of which is beveled to provide a cam surface 16% to engage with the cam surface of the pin 152. The other end of short rod is diametrically slotted to receive the end of interlock bar 124, which is pinned to short rod 160 by a transverse pin 162. The interlock bar is otherwise like bar 24 and is connected to the switch mechanism in the same way as bar 24. 1

When the interlock bar 124 is moved from switch-open to switch-closed position, the pin 152 is pushed inwardly against the bias of spring 154 by the camming action of short rod 160 on the pin 152. If the plug has been fully inserted, the pin 152 may enter the plug hole 42h; but if the pin 152 is only partly inserted, the pin 152 cannot move and prevents the interlock bar 124 from moving so that the switch cannot close.

If the plug is not inserted and the switch is then moved to closed position, the plug cannot be inserted because the pin 152 will have protruded into the passageway in the receptacle shell and will prevent inward movement of the plug past the protruding pin.

From the foregoing, it Will be apparent that the invention provides a simple, easily machined and assembled interlocking mechanism which can be used in large, heavy duty electric power circuits and which will withstand hard usage and the application of great forces such as are encountered in heavy duty switch mechanisms,

Moreover, the invention requires only minor modifications in common plug and receptacle shells and the attachment of only an interlocking rod that may be economically fabricated and attached to existing forms of heavy duty enclosed switch mechanisms. The interlocking mechanism is enclosed and entirely tamper proof.

Many modifications within the scope of the invention will occur to those skilled in the art. Therefore, the invention is not limited to the specific form and embodiments illustrated.

What is claimed is:

1. An interlocking connector and switch combination, comprising a box having an openable cover, an operating handle outside the box, switch contacts and operating mechanism -for said contacts in the box operated by said handle for moving the switch between open and closed positions, means on said cover and on said operating mechanism inter-engaging to lock said cover closed when said switch is closed, a connector member having contacts and mounted on said box, a second connector member having contacts connectable With the contacts of said first connector member, an interlocking bar moved lengthwise by said operating mechanism, and a locking pin moved laterally with respect to said second connector member by said bar as it and said operating mechanism move between switch-closed and switch-open positions, said second connector member being formed to engage said pin and prevent interconnection and disconnection of said connector members when said switch is closed.

2. The combination as claimed in claim 1 having means to bias said pin, and means on said bar exerting a camming action on said pin to move it between unlocking and locking positions.

3. The combination as claimed in claim 2 having mounting means on said first connector member adapted to guide said pin, and interengaging means between said mounting means and bar preventing said bar and operating mechanism from moving into switch-closed position when said pin is unable to move into connector-locking position.

4. The combination as claimed in claim 1 having means to bias said pin toward said second connector member, said second connector member being formed to receive said pin and be locked thereby in switch-closed position.

5. The combination as claimed in claim 4 having mounting means on said first connector member adapted to guide said pin, and interengaging means between said mounting means and bar preventing said bar and operating mechaism from moving into switch-closed position When said pin is unable to move into connector-locking position.

6. The combination as claimed in claim 5 in which the pin has head and neck portions with adjacent cam surfaces, and the locking bar has a bifurcated end embracing said neck portion and engaging said cam surfaces to prevent movement of the bar to switch-closed position when said pin is unable to move into connector-locking position.

References Cited by the Examiner UNITED STATES PATENTS 3/1955 Parish 4/1963 Mueller

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2705266 *Mar 21, 1951Mar 29, 1955Crouse Hinds CoSwitch and receptacle unit
US3088004 *May 11, 1960Apr 30, 1963Bassani SpaElectrical switches
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3634732 *Feb 24, 1970Jan 11, 1972Motorola IncHousing for electronic apparatus including multifunction handle mechanism
US4503293 *Dec 17, 1982Mar 5, 1985Midland-Ross CorporationInterlocking plug and receptacle mechanism with actuating means
US5868014 *Dec 18, 1996Feb 9, 1999Samsung Electronics Co., Ltd.Security locking device for a desk top computer
US5895981 *Feb 10, 1998Apr 20, 1999Reliance Time Control, Inc.Generator transfer panel with a terminal arrangement for establishing a direct connection to a remote power inlet
US5984719 *Dec 31, 1997Nov 16, 1999Reliance Controls CorporationRemote power inlet box for an auxiliary power supply system
US6107701 *Aug 24, 1998Aug 22, 2000Reliance Controls CorporationOptional meter panel for a transfer switch having a terminal compartment
US6163449 *Nov 23, 1998Dec 19, 2000Reliance Controls CorporationTransfer switch with optional power inlet and meter panel
US6184461Dec 12, 1997Feb 6, 2001Reliance Controls CorporationGenerator power inlet box with integral generator cord
US6365990Jun 21, 1999Apr 2, 2002Reliance Controls CorporationCover plate terminal assembly for a transfer switch
US6369321Feb 5, 2001Apr 9, 2002Reliance Controls CorporationGenerator power inlet box with selectively engageable generator cord
US6414240Mar 15, 2000Jul 2, 2002Reliance Controls CorporationGenerator transfer switch having a compartment with exposed wire leads for interconnection with a power input
US6504268Oct 19, 2000Jan 7, 2003Reliance Controls CorporationTransfer switch with selectively configurable cover structure with power input and meter capability
US6564427Feb 27, 2001May 20, 2003Reliance Time Controls, Inc.Hinged assembly for cover arrangement in power inlet box
US6861596May 28, 2003Mar 1, 2005Gen-Tran CorporationSwitch interlock apparatus
US6900400Jun 26, 2003May 31, 2005Aqua Signal Aktiengesellschaft SpezialleuchtenfabrikApparatus having an enclosure, at least one circuit breaker and at least one plug receptacle
US20040118667 *May 28, 2003Jun 24, 2004Paul SchnackenbergSwitch interlock apparatus
EP1378974A1 *Jun 3, 2003Jan 7, 2004Aqua Signal AktiengesellschaftDevice having a housing, at least one circuit breaker and at least one socket
U.S. Classification200/50.18, 439/372
International ClassificationH01R13/70, H01R13/707
Cooperative ClassificationH01R13/707
European ClassificationH01R13/707