Circuit-closing Adapter

Abstract

A circuit-closing adapter is provided with a continuous contact extending beyond one end of the adapter body and with a two-part contact, one part of which extends beyond said body, said contact-extensions being adapted for insertion into an electrical receptacle, said parts of the latter contact being normally spaced apart. A dielectric member is removably affixed to the body, the same both physically and electrically connecting the opposite ends of the contacts to the respective prongs of an electric plug that is attached to a machine or appliance. Key-operated lock means to move one of the parts of the two-part contact into direct electrical contact with the other end of said parts and to retain such contact while the key remains in the lock, is provided. Upon removal of the key from the lock, the moved contact part is released so the same may resume its spaced position, thereby opening the operative circuit between the electrical receptacle and the machine or appliance. The adapter is provided with means to receive a third wire prong provided on the plug to enable grounding the ground line of a three-wire system.

Description

is primarily devised for the safe operation of machine tools such as drill presses, saws, etc. in home work ships, or in places where such machines may be available for unauthorized use, as by children.

following U.S. Pat. Nos. Williams 1,143,676 Ronneberger 1,684,148 Yates 2,217,585 Sepulveda 2,777,023 Wintriss 2,846,530

The above art teaches that circuit closers for purposes of safety are known. Special devices that replace the common plug ordinarily provided on the end of the cord, attached to a machine, appliance or other such device, also, appear to be old, as is the broad concept of key-locking such devices to prevent unauthorized control of such devices.

Of the art above listed, only the patent to Wintress requires discussion. This patent requires the use of a three-element element contact consisting of a prong 17, a contact 35, and a conductor element 33, the latter being part of the key 45. There is no lock, as such. This prior organization of elements greatly differs from that of the present device because any similarly shaped metal object, or even a piece of wire may be inserted in the keyhole 40, can be substituted for the key 45 to effect closing of the circuit. Moreover, the engagement between prong 17 and the contact 35 is not a direct one but rather depends on the bridging element 33. Further, the plug 10 cannot be separated from plug 15 without destroying the latter and, perhaps, also requiring replacement of plug 10.

A circuit-closing adapter having a dielectric body with a continuous contact and a parallel contact comprising two normally-spaced sections, said contacts having end prongs extending beyond one end of the body for electrical engagement with the conductors of an electric socket or receptacle, key-operated means to move one of said contact sections into electrical engagement with the other section so that current in said socket or receptacle is conducted through the parallel contacts to the two prongs of a plug, respectively engaged with said parallel contact when the key is turned in one direction and remains so turned, thereby providing operating current for a machine or appliance to which said plug is attached. Upon turning the key in the opposite direction, the moved contact section returns to its normal spaced, current-opening position. Then, the key may be extracted from the lock, thereby preventing the machine from being operated due to an open circuit in the adapter. The adapter and the plug are connected to prevent their separation. Such separation may occur only when a difficult-to-remove dielectric pin, which connects the parallel contacts and the plug prongs, is removed from the body, thus enabling the electric plug to be withdrawn from the adapter. To accommodate machines or appliances provided with three-wire systems, the adapter is provided with ground-wire connection means.

An object of the invention is to provide a lock-provided adapter that is secured to the prongs of an electric plug of a power machine or like device and is key-controlled so that the device can be operated only which when the key is operated to close the circuit to the device and remains in the lock after such operation.

Another object of the invention is to provide an adapter as characterized in which the contact of the adapter and the prongs of the plug are connected in a manner to retain the adapter and plug connected until, for whatever reason, the same are desired to be separated.

A further object of the invention is to provide an adapter as characterized with means to accommodate the ground prong of a three-wire plug so that ground connection of the plug through the adapter is facilitated.

This invention also has for its objects to provide such means that are positive in operation, convenient in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description, which is based on the accompanying drawings. However, said drawings merely show, and the following specification merely describes one embodiment of the present invention, which is given by way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views.

FIG. 1 is a perspective view of a circuit-closing adapter according to the present invention.

FIG. 2 is a perspective view as seen from the far side of FIG. 1.

FIG. 3,to an enlarged scale, is a sectional view as taken on the plane of line 3--3 of FIG. 1, the cylinder lock there shown being in elevation.

FIG. 4 is a cross-sectional view as taken on the line 4--4 of FIG. 3, the adapter being shown in the open-circuit position of the contacts thereof.

FIG. 5 is a fragmentary sectional view as taken on the plane of said line 4--4 of FIG. 3, the terminals thereof being shown in the closed-circuit position of the contacts.

FIG. 6 is a sectional view as taken on the plane of line 6--6 of FIG. 4.

FIGS. 7 and 8, respectively are longitudinal sectional views as taken on the lines 7--7 and 8--8 of FIG. 6.

FIG. 9 is a sectional view as taken on the plane of line 9--9 of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present circuit-closing adapter comprises, generally, a sectional body 10 formed of high impact, dielectric material, preferably of one of the molded plastics; a pair of electric contacts 11 housed in the body, one of which comprises a contact 12 that has permanent electrical contact with one prong 13 of an electric plug 14 that, in the usual manner, is connected to an electric machine or device, such as a drill, lathe, milling machine, etc., and the other of which comprises a contact portion 15 that is in permanent electrical contact with the other prong 16 of the plug 14; a prong contact 17 comprises a normally spaced extension of the contact portion 15; a key-controlled cylinder lock 18 housed in the body 10; means 19 operated by said lock to move the contact portion 15 into electrical engagement with the prong contact 17, whereby said contact portion and contact prong become an electrical extension of the prong 16 of the electric plug 14; dielectric means 20 for permanently securing the plug prongs 13 and 16, and the pair of electrical contacts 11 to the body 10; and ground-connection means 21 mounted on the body 10 to provide for a ground connection when the adapter is to be connected to a plug of a three-wire electric system.

The body 10 is shown as comprising sections 25, 26 and 27, preferably stacked with the section 26 between the sections 25 and 27, and with a single rivet 28 permanently connecting the sections of the stack after the pair of contacts 11 are assembled between the sections 26 and 27 and the lock 18 and means 19 are assembled between the sections 25 and 26. Projection 29 extend from an inner face of one body section and enter seats or sockets 30 in the inner face of an adjacent body section to retain said sections against relative rotative movement about the axis of the rivet 28. The body, thus formed, is shown as of parallelepiped form. The form of the body, however, may vary.

The contact 12 extends from one end of the housing through the opposite end thereof to form a resilient prong 31 that is adapted to be introduced into an electric socket or receptacle. The body sections 26 and 27 are formed with mating notches that form an opening 32 through which the prong 31 extends.

The contact portion 15 extends from the first-mentioned end of the housing toward the opposite end but terminates within the housing, said contact portion having an end extension 33 that is offset from the part thereof adjacent to the first-mentioned end of the housing. The end extension is resilient and the same is provided with a wear bead 34 that, as will be hereinafter described, is engaged by the means 19.

The prong contact 17 is formed to have a part 35 inwardly spaced from the extension 33 of the contact portion 15, an integral extension 36 is bent at right angles to the part 35 and is housed in a seat formed in adjacent portions of sections 26 and 27, and a resilient prong 37 extends from the part 35 to constitute a companion to the prong 31 and is adapted to be introduced in the mentioned electrical socket at the time said prong 31 is so introduced. The body sections 26 and 27 are provided with an opening 38, similar to opening 32, through which the prong 37 extends.

To make certain that the prong portion 15 and prong contact 17 remains normally spaced apart, as in FIG. 6, an expansion spring 39 biases the former in a direction away from the part 35 of the latter.

The lock 18 is shown as an ordinary cylinder lock and is housed in a recess 40 formed of complementary portions in the body sections 25 and 26. The barrel or cylinder of said lock is fixedly held in said recess as by a pin 41 engaged in a seat formed in the body section 25. The present lock has its key-rotated plug 42 provided with an eccentric cam 43 that has one position (FIG. 4) when the key of the lock is withdrawn, and another position (FIG. 5) when the plug is turned by the key in which position the key cannot be withdrawn.

The cam 43 is engaged with the means 19 which is shown as a slide 44 that is provided with an opening 45 in which said cam is engaged. Said slide 44 is provided with a bevel 46 that is directed toward the extension 33 of contact portion 15 to operatively engage the bead 34 on the contact extension 33. As shown in FIG. 4, when the cam 43 is retracted (the position thereof when the key is removed) the slide 44 is retracted. Thus, the extension 33 remains in the position of FIG. 6, i.e., spaced from the part 35 of the prong contact 17. Of course, no current can flow toward the prong 37 from the end thereof in contact with the prong 16 of the plug 14.

When the key is turned to cause shift of the slide 44 toward but rearward of the extension 33, the bevel thereof will engage the bead 34 of said extension and cam or wedge the same into firm electrical engagement part 35 of prong contact 17, as shown in FIG. 5. Such electrical engagement of the contact portion 15 and the prong 17 will establish an electric circuit from a socket in which the prongs 31 and 37 are engaged to the motive means of the machine to which the plug 14 is connected. Upon rotation by the key of the plug 42 of the lock, the cam 45 causes retraction of the slide 44 allowing the expansion spring 39 to bias the extension in a direction away from the prong contact 17. Now the key may be removed from the lock so the adapter can remain in a non-operative condition.

The means 20 is shown as a dielectric locking pin 47 that extends transversely through the body 10 and through aligned holes in the plug contacts 13 and 16, contact 12, and contact portion 15. Said pin 47 is sealed in by means of a plug 48 preferably of plastic, whereby, if necessary, the same can be removed, but with some difficulty, to allow removal of the pin 47.

The above-described adapter will serve to extend the terminals or prongs 13 and 16 of a two-wire plug 14 to bring current of said lines to the prongs 31 and 37, respectively, while the key, as above described, remains in the plug 42, inasmuch as major appliances ordinarily are required to have three-wire systems. In order that such systems may still be powered by old two-wire systems, the present adapter may be provided with the means 21. Such means is shown as housed in a fourth body section 50 secured to the body section 27, as by drive screws 51. Said means comprises a terminal 52 that is adapted to receive the prong of the third or grounding wire. The terminal 52 may be provided with a pigtail 53 that may be grounded to a fastening screw of the socket or receptacle or to the plate thereof.

Where a three-wire system exists in the receptable, such pigtail may be replaced by a prong that fits directly into the receptacle, the openings 54 for the prongs 13 and 16 and and the opening 55 to the terminal 52 being clustered, as in FIG. 1, for convenience.

While the foregoing has illustrated and described what is now contemplated to be the best mode of carrying out the invention, the construction is, of course, subject to modification without departing from the spirit and scope of the invention.

Claims

Having thus described the invention, what is claimed and desired to be

1. Circuit closing means comprising the combination with the prongs of an electric plug that is attached to a machine which is rendered operative by electric current received by said prongs of: an adapter provided with a pair of electric contacts, one of which is continuous and the other comprises two normally spaced parts, means connecting said pair of contacts, respectively, to said prongs of the electric plug and retaining the respective connected contacts and prongs electrically spaced, the other ends of said pair of contacts extending from the adapter for separable connection with the receptacle of a current-conducting line, and key-operated means to engage and move only one of the two normally spaced contact parts into direct and resilient electrical engagement with the other of said parts, to thereby electrically connect said line and the

2. The circuit-closing combination according to claim 1 in which one end of one part of the two-part electric contact is in overlapping relation to the other part, and the key-operated means engages and moves one of said

3. The circuit-closing combination according to claim 2 in which the adapter is provided with a spring element to bias said one part of the two-part electric contact into the mentioned spaced relationship to the

4. The circuit-closing combination according to claim 1: a dielectric body housing said pair of contacts with the receptacle-engaging ends extending therebeyond, and the mentioned means that connects the contacts and the plug prongs comprising a dielectric pin transversely extending across the dielectric

5. The circuit-closing combination according to claim 4 in which the body, at one end of said pin, is provided with a destructible and, thereby, removable plug that, when removed, exposes one end of said pin for removal,thereby enabling the electric plug to be separated from the

6. The circuit-closing combination according to claim 5 in which the pair of electric contacts and the prongs of the electric plug are provided with aligned holes, and the mentioned dielectric pin extends through said holes

7. The circuit-closing combination according to claim 1 in which the key-operated means comprises: a cylinder lock, the key-turned plug of which is provided with an eccentric cam, and a dielectric member engaged with said cam and movable thereby to effect engagement with and movement of the normally spaced contact part into

8. The circuit-closing combination according to claim 7 in which the dielectric member comprises a slide that has a bevel end that wedges the contact part it engages into engagement with the other contact part.