US2923909A

US2923909A - modrey

Info

Publication number: US2923909A
Authority: US
Publication date: 1960-02-02
Anticipated expiration: 1977-02-02

Description

Feb. 2, 1960 H. J. MODREY 2,923,909

PLUG FOR AN ELECTRICAL CONNECTOR Filed March 5, 1956 A 1 l8 u k\ FIG. 9

FIG. IQ

INVENTOR.

HENRY J. MODREY Y MWM ATTORNEYS United States Patent PLUG FDR AN ELECTRICAL CONNECTOR Henry J. Modrey, Stamford, Conn.

Application March 5, 1956, Serial No. 569,403

6 Claims. (Cl. 339-61) The present invention relates to two-part electric Wire connectors, and more particularly to cord connectors. As the terminology used by the industry for component parts of electrical connectors is not always consistent, the removable part of such connector which is generally attached to the cord, is hereafter referred to as plug, and the stationary part which is generally attached to or integral with a base or housing, is referred to as receptacle.

An advantageous though not exclusive field of application of the invention are cord connectors for electrical devices, especially devices the connector cord of which is or may be subjected to a pull tending to separate the cord from the device when the latter is in use. Devices of this kind are for instance, portable tools, appliances and electric shavers. The tendency towards involuntary separation is aggravated if the cord used is of the springy coiled type. Another field of application of the invention are electric connectors in which turning of one member relative to the other effects a positive lock.

Cords of the general kind above referred to, frequently terminate at the end to be connected to the appliance or other device in a plug attached to or molded integrally with the insulation material of the cord and having two tubular outlet contacts. The receptacle on the device generally comprises two or more contacts, frequently set in'& well or recess in the body of the device. Contact and mechanical retention are obtained by the friction between the engaging contact elements of the plug and 'the receptacle. Experience shows that this frictional retention materially deteriorates by repeated connection and disconnection. As a result, the contact pressure decreases correspondingly and finally the cord plug is no longer safely retained.

Accordingly, one of the objects of the invention is to provide a novel and improved plug which is more safely -yet releasably retained in the receptacle of the appliance or' device.

Another object of the invention is to provide a novel 'and improved plug which affords substantially constant contact pressure for a prolonged period of use. j

Still another object of the invention is to provide a novel and improved interchangeable plug designedto coact with receptacles of conventional design.

The expression conventional design shall be deemed to describe electrical connectors which have found widespread acceptance, with contact members in the shape of pins or fiat prongs. It shall be deemed to include connectors with flat, curved hooloshaped contact members in which turning of the plug relative to the receptacle effects a positive lock. The interchangeability of the plugs according to the invention affords the advantage "that the plug can be readily used instead of a plug of conventional design without alteration of the conventional receptacles.

A further and more general object of the invention is :to' provide a novel and improved plugwhich can be strongly secured to the receptacle of an electric connector ice by temporary deformation of a component of the plug according to the invention, and can be released by similar temporary deformation of the same component.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and set forth in the appended claims forming part of the application.

In the accompanying drawing several preferred embodiments of the invention are shown by way of illustration and not by way of limitation.

In the drawing:

Fig.- 1 is a sectional view of a plug according to the invention and of a receptacle of conventional design coacting with the plug of the invention.

Fig. 2 is a section taken on line 22 of Fig. 1.

Fig. 3 is an isometric view of a modification of the plug according to the invention and a plan view of the application of this plug to a receptacle of conventional design.

Fig. 4 is a section taken on line 4-4 of Fig. 3.

Fig. 5 is a sectional view of a locking plug and receptacle according to the invention.

Fig. 6 is a fragmentary view showing the contact elements of Fig. 5 applied to each other on an enlarged scale, the view of Fig. 6 being turned through Fig. 7 is a modification of the plug of Figs. 5 and 6, shown partly in section.

Fig. 8 is a locking plug according to the invention, designed for receiving flat, curved, hook shaped contact elements.

Fig. 9 is a locking receptacle of conventional design comprising flat, curved, hook-shaped contact elements, for coaction with the locking plug shown in Fig. 8.

I Fig. 10 is a fragmentary isometric sectional view of the contact elements of Figs. 8 and 9 applied to each other. I-

Fig. 11 shows a tool suitable for the manufacture of plugs as shown for instance in Figs. 1, 3 and 5; and

Fig. 12 shows a tool for producing a plug as show for instance in Fig. 8.

Referring first in detail to Figs. 1 and 2, the two-part connector shown in these figures comprises a plug according to the invention generally designated by 15 and applicable to a receptacle generally designated by 16; vReceptacle 16 is of conventional design. It is shown as com.- prising a housing 17 in which is seated an insulation disc 18 mounting two contact pins 19 shown as being of the round pin type.

The plug comprises a body 20 made of rubber or other suitable elastic material. Body 20 may be molded integrally with the insulation of the wires. Two contact sleeves 21 for receiving contact pins 19 are fitted in .body 20 in electric contact with

cord wires

22 and 23. The sleeves end short of the forward face of body 20 and bores 24 extend from the forward face to the sleeves. Bores 24 and sleeves 21 are axially misaligned when body 20 is in its normal relaxed condition which is the condition shown. 7

Let it now be assumed that it is desired to apply plug .15 to receptacle 16. To this end the forward part of body 20, that is, the part including bores 24 is inserted into housing 17. Pins 19 will enter holes 24 but further insertion is blocked by abutment of the tips of pins 19 with the edges of the misaligned contact sleeves. To complete the insertion of plug 15, the rear part thereof, that is, the part including sleeves 21 is circumferentially turned relative to the front part which is held stationary by the engagement of pins 19 with bores 24. This stretches and elongates bores 24. As soon as sleeves 21 and bores 24 have reached a position of axial alignment, ingress is no longer blocked and the plug can be pushed home.

As is evident, the torsion applied to the rearpart of body 20 stores potential energy in the body due to the elasticity of the body material. Consequently, the tensioned rear part of the body when released seeks to unwind itself and to return into its initial or relaxed position relative to the front part. However, the insertion of the contact pins permits a partial unwinding of the rear part only. As a result, the remaining stored potential energy presses the contact sleeve against the pin thereby gripping the same with a strong frictional pressure. This pressure will remain as long as the connector parts are applied to each other thus assuring a safe retention of the plug in its receptacle and an improvement of the electrical contact pressure.

This advantage applies even when the contact elements are worn out, that is, if there is insuflicient'friction between pins 19 and sleeves 21. The stored potential energywill nevertheless cause pressure of the pins against the sleeves and will thus maintain good electric contact.

The degree of misalignment between bores 24 and sleeves 21 can be so chosen that the turning or twisting motion, required for insertion, is effected automatically. If the degree of misalignment is such that the tip of contact pins 19 rest against the inside sidewalls of sleeves 21, pressure on the rear of plug body 20 will tend to force the pins 19 into the sleeves, against the pressure of the rubber which resists deformation. The contact pins 19 in conjunction with sleeves 21 will therefore'act cam-like in producing a rotary action of the front part of plug body 20 and an accompanying elongation of bores 24. Manual turning of the plug body 20 is therefore unnecessary. This manner of operation is hereinafter referred to as automatic cam action.

While the plug can be forcibly pulled out of its receptacle and vice versa it is preferable to separate the connector parts by again twisting the rear part of plug body 20 in the same direction as it was wound for aligning the sleeves and the bores for purpose of insertion.

To facilitate twisting of the rear part relative to the front part, an annular groove 25 may be provided at the plane of junction between the front and rear part of plug body 20.

Figs. 1 and 2 show a round plug and a round receptacle, but the invention is also applicable to non-round shapes such as the rectangular shape frequently used for the connectors of an electric shaver.

Figs. 3 and 4 show such an arrangement. The front part 26' of the plug body 26 has a rectangular shape and fits the well or cavity 27 formed in the casing 27 ofthe receptacle. The shape of the plug body 26 is shown slightly exaggerated. The rectangular shape of its front is generally blended smoothly into the rear position of the plug body.

The function of the connector of Fig. 3 will be evident from the previous description. It suffices to state that front part 26' is first fitted in well 27' and the rear part 26" of body 26 is then wound to permit the completion of the insertion. Automatic cam action can be arranged by suitably spaced misalignment between the front bores and the contact sleeves inside the plug.

It will be'observed that with a non-round plug according to the invention, the elongation of the bores in the front part of the plug body is eliminated because the said front part is secured against rotation by its fit inside the receptacle housing. The rear portion of the plug body must therefore be reduced in dimensions to an extent such that it can twist inside the receptacle housing as shown in broken lines in Fig. 4.

In the two embodiments previously described, the

contact pins are frictionally retained in the contact sleeves. The principle of the invention also embraces a positive retention of the contact pins in the .contact sleeves. The subsequent figures show designs in which the contact pins are positively locked in the contact sleeves by torsional action.

Referring now to Fig. .5, the plug 15 of these figures is similar to plug 15 of Figs. 1 and Z and the same components are designated by the same numerals. Plug 15' is distinguished from plug 15 in that a space or cavity 3% extends laterally from the inner end of each sleeve 21 but in opposite direction.

The receptacle 16' is similar to receptacle 16 but each contact pin 19' is formed at its end into a onesidedly overhanging head or hook 19". The two hooks extend in opposite directions and the diameters of both, sleeves 21 and bores 24 are slightly increased so that they will permit passage of books 19".

To engage the connector, the forward end of plug 15' is inserted into housing 17 until the misaligned sleeves 21 block further ingress. Then the rear part of plug 15' is circumferentially twisted until the sleeves and the bores are in alignment and plug 15' is pushed home. When now the rear part of the plug is released thereby permitting this part to unwind itself in opposite direction each hook 19 enters its cavity 30 overhanging the respective sleeve 21. At the same time, the inner wall of each sleeve is pressed against the respective contact pin. As is apparent, the two connector members are now positively locked to each other and remain in the locked condition until they are released by turning the rear part of plug 15' in the same direction in which it was wound for insertion.

Automatic cam action can be applied to insertion and coupling, as hereinbefore described. The cam action is facilitated if the contact hook is formed so as to facilitate its entry into the contact sleeve. Such contact hook is shown by way of example at 19a in Fig. 6.

Fig. 7 shows a modification distinguished from the design of Figs. 5 and 6 in the same manner'as Figs. 3 and 4 are distinguished from Figs. 1 and 2, that is, the front part 20" of the plug is rectangular. The well of the coacting receptacle must, of course, have a cot-- responding rectangular outline.

. The rectangular shape of the front part of the plug as shown in Figs. 4 and 7 has the advantage that the front part is rotationally secured not only by the pins, but also by the fit of its own shape in the well. This affords the advantage that the constantly acting reverse torsion is more evenly distributed within the rubber or the front part than in the ound shapes of Figs. 1 and 5.

Figs. 8 and 9 and 10 show an application of the torsion principle of the invention to a locking type of connector of conventional design, with flat, curved hoolishaped contact elements.

As is shown in Fig. 9, the male contact element in the conventional locking receptacle has a shank 31 from which one sidedly extends a hook 32. The two hooks face in opposite directions and are curved in the circle of their circumferential distance.

' The coacting plug according to the invention is similar in principle to the connector plugs previouslydescribed in that its elastic body 33 has in its front part circumferentially curved .bores 34, and in its rear part two circumferentially curved contact sleeves. 35. -A cavity 36 extends circumferentially from the rear end of each sleeve 35, the two cavities facing in opposite direction. Both, bores 34 and sleeves 35 have a circumferential length such that they fit hooks 32.

The application of the connector members to each other is apparent from the previous description and from Fig. 10 which shows the contact elements in locked conducting engagement. As can be clearly seen in this figure, the contact hooks 32 overhang the contact sleeves 35 when the rear part of body 33 is released after having been previously twisted to permit insertion of. the contact elements. Due to the overhang, the two connector members are positively locked to each other and remain in the locked condition by the torsional action of the wound rubber body which also presses shanks 31 against the sleeve walls thereby improvingthe contact pressure. I I

It may be observed that the position of the locking contact elements as shown in Fig. is achieved also with locking connectors of conventional design. The torsionally wound connector plug according to the invention adds a constant spring force to the conventional locked engagement which prevents involuntary un-twisting and disengagement and which further produces positive and constant contact pressure.

Automatic cam action may be applied to this embodiment of the invention, as hereinbefore described. Its application is facilitated by shaping the contact hooks so as to facilitate their entry into the contact sleeve, from the misaligned position in a manner similar to the one shown in Fig. 6.

To release the two connector members, the rear part of plug 33 is again twisted in the same direction as it was wound for the insertion of the contact elements.

The plugs as hereinbefore described may be manufactured by bonding together two halves. However, the designs of the plugs according to the invention also permit manufacture of the plugs in a single operation and basically in the same manner in which standard cord connector plugs are manufactured.

Fig. 11 shows a mold insert suitable for manufacturing a cord connector plug as shown in Fig. 5. The insert according to this figure comprises two pins 50 which define mold cavities forming the bores 24. The upper part of each pin is set ofi to form parts 50' which serve to carry the wired sleeves 21 during the molding process and to produce the required misalignment of the sleeves and the bores in the body of the plug. As the rubber of the body should be highly elastic to permit the required torsional action, the pins can be easily withdrawn upon completion of the molding operation.

Fig. 12 shows a mold insert similar in principle to the one just described and suitable for molding cord connector plugs as shown in Fig. 8. The insert of Fig. 12 has a part 52 to form bores 34, a set-off part 53 to form cavities in the body receiving the contact sleeves and a hook part 54 to form cavities 36.

The invention is also applicable to connectors with more or less than two contact elements.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. An electrical connector comprising a recessed receptacle and a plug coacting with said receptacle, said receptacle including a pair of contact elements mounted in the receptacle recess in fixed spaced apart positions and each ending in a one-sidedly enlarged head, and said plug comprising an elastic torsionally twistable single piece connector body of insulation material, and a pair of elongated hollow contact members embedded in said bodyeach for receiving the respective contact element of the receptacle, said body including a pair of -bores each extending from the outside of the body to the near edge of the respective contact member and further including within its body a pair of detaining spaces each transversely extending from the far end of the respective contact member beyond the peripheral outline thereof, said contact members and said bores occupying in the relaxed state of said body a detaining position relative to each other, blocking passage of the contact elements through the bores and insertion in the contact members and in a torsionally twisted state of the body a receiving position in which the contact members and the bores are disposed relative to each other to form a passage for insertion of each contact element and passage of the head thereof into the respective space whereby upon re;- lease of said body the'contact members 'andthe bores return into said detaining position relative to each other in which the inserted contact elements are positively detained in the contact members by the position of the head in each respective space.

2. An electrical connector comprising a recessed receptacle and a plug coacting with said receptacle, said receptacle including a pair of contact elements each mounted in the receptacle recess in a fixed position and ending in a one-sidedly enlarged head and said plug comprising an elastic torsionally twistable single piece connector body of insulation material and a pair of contact sleeves each embedded in said body for receiving the respective contact element of the receptacle, said body including a pair of bores each extending from the outside of the body in axially parallel relationship with the re spective sleeve and further including within its body a pair of detaining spaces each transversely extending from the inner end of the respective sleeve beyond the peripheral outline thereof, each sleeve and the respective bore occupying in the relaxed state of said body an axially misaligned but parallel position relative to each other blocking passage of the respective contact element through the bore and insertion in the contact sleeve and in a torsionally twisted state an axially aligned position in which each sleeve and the respective bore form a continuing opening for passage and insertion of the respective contact element and passage of the head thereof into said space whereby upon release of the body the same unwinds towards its relaxed state in which each inserted contact element is positively detained in the respective sleeve by the position of the head in the respective space.

3. An electrical connector comprising a recessed receptacle and a plug coacting with said receptacle, said receptacle including a pair of contact elements each mounted in the receptacle recess in afixed position and ending in a one-sidedly enlarged head, and said plug comprising an elastic torsionally twistable single piece connector body of insulation material, part of said body fitting said recess for retention therein and the protruding part of the body being twistable in a circumferential direction relative to said retainable part, and a pair of contact sleeves each embedded in said twistable part for receiving the respective contact element, said retainable part including a pair of bores therethrough each extending from the front of said part parallel to the respective sleeve to the front thereof and said retainable part further incuding within its body a pair of retaining spaces each transversely extending from the inner end of the respective sleeve beyond the peripheral outline thereof, the peripheral outlines of each bore and associated sleeve fitting the respective head for passage therethrough, each sleeve and associated bore occupying in the relaxed state of said part an axially misaligned but parallel position relative to each other blocking passage of the respective contact element through the bore and insertion in the respective contact sleeve and in a torsionally twisted state of said body parts relative to each other an axially aligned position in which each sleeve and associated bore form a continuing opening for insertion of the respective contact element and passage of the head thereof into the respective space whereby upon release of the body parts the same unwind toward the relaxed state in which the head of each contact element is positively detained in the respective space.

4. A connector according to claim 3 wherein each contact element is in the form of a round pin shaped at its free end to form said head.

5. A connector according to claim 3 wherein each contact element comprises a fiat shank having at its free end a one-sided lateral extension forming said head.

6. A connector according to claim 2 wherein the portion of each head engageable with the respective contact sleeve upon insertion of the respective contact element in