US3521220A - Integral plug and strain relief cord set and method of manufacture - Google Patents

Description

July 1970 I E. E.-CLARKE, JR. ETAL 352L220 INTEGRAL PLUG AND STRAIN RELiEF CORD SET AND METHOD OF MANUFACTURE n Filed June 10, 1968 3 Sheets-Sheet 1 FIG. I.

INVENTORS EDWIN E. CLARKE,JR.

ATTORNEY July 21, 1970 v E. E. CLARKE, JR. E'I'AL 3,521,220- 'INTEGRAL PLUG AND STRAIN R EF CORD SET AND METHOD OF MANU TUBE Filed June 10, 1968 3 Sheets-Sheet 2 FIG. 4A

V //////////I/ ALIQ!L\ "4 V l III INVENTORS EDWIN E. CLARKE,JR.

AvsiQ/L 'ESHUL M BY M I M ATTORNEY om) SE1 AND 3 Sheets-Sheet 5 E. E. CLARKE. JR.. 5-1- RAIN RELIEF E MANUFACTUR INTEGRAL PLUG AND ST METHOD 0 July 21,1970

Filed June 10, 1968 .m m W R AVRA M. ESHULAM \Ny ATTORNEY 3,521,220 INTEGRAL PLUG AND STRAIN RELIEF CORD SET AND METHOD OF MANUFACTURE Edwin E. Clarke, Jr., Timonium, and Avram M. Mushulam, Baltimore, Md., assignors to The Black and Decker Manufacturing Company, Towson, Md., a corporation of Maryland Filed June 10, 1968, Ser. No. 735,789 Int. Cl. H01r 13/08 US. Cl. 339-62 Claims ABSTRACT OF THE DISCLOSURE SUMMARY OF THE INVENTION The present invention is directed to a novel plug and strain relief construction for a portable electric tool, appliance and the like. The plug and strain relief are of integral, one-piece, molded construction and eliminates both the need for a separate multi-conductor cord between the strain relief and plug, were they separate, as well as the cumbersome, tedious and costly task of stripping the end of this cord to facilitate connection of the plug blades to the individual conductors. In addition, an extension cord connector may be secured to or, preferably, molded integrally with the novel plug and strain relief, if desired.

Main objects of the present invention are to provide an improved cord set for portable electric tools, appliances and the like, which cord set embodies a one-piece molded plug and strain relief and thereby renders the cord set considerably easier and less expensive to manufacture and assemble to the tool or appliance, while possessing greater overall strength and better appearance.

An additional object of the present invention is to provide a novel cord set of the above character with which an extension cord connector may be integrally molded.

Further objects of the present invention will become more apparent from a consideration of the detailed description to follow taken together with the drawings annexed hereto.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view illustrating a portable electric tool embodying the present invention;

FIG. 2 is a view, partly in section and partly in elevation and illustrating a typical prior art cord set construction;

FIG. 2A is a sectional view of FIG. 2 taken along the line 2A-2A thereof;

FIG. 3 is an elevational view illustrating a cord set embodying the present invention;

FIG. 4 is a longitudinal sectional view of FIG. 3 illustrating a preferred form of the invention;

FIGS. 4A and 4B are views similar to FIG. 4 but showing modified forms of the invention;

FIG. 5 is a sectional view of FIG. 3 taken along the line 5-5 thereof;

FIG. 6 is a sectional view illustrating the cord set wires and terminals in position within a die before molding of the strain relief and plug takes place;

United States Patent 0 ice FIG. 7 is a view similar to FIG. 6 but showing the integral strain relief and plug after molding;

FIG. 8 is a perspective view illustrating the cord set of the present invention and shown with a further, integrally molded, inventive refinement;

FIG. 9 is a sectional view of FIG. 7 taken along the line 99 thereof; and

FIG. 10 is a sectional view of FIG. 7 taken along the line 1010 thereof.

BROAD STATEMENT OF THE INVENTION Broadly described, the present invention relates to a portable electric device of the type having a housing, an electric motor within said housing and adapted to be powered from -a remote electric source, electrical conductor interconnected with said motor and adapted to extend outwardly of said housing and each having a plug blade connected to its end; and includes the improvement which comprises a one-piece elongated member molded around said plug blades and said conductors outwardly of said housing, said member having means at one end enabling it to be fixed to said housing and its other end supporting and locating said plug blades for connection to a complementary, electrical receptacle, said member having a flexible intermediate portion allowing relative lateral movement between said ends.

In another aspect, the present invention relates to an electrical cord set construction which comprises a onepiece, elongated flexible member molded in place around a plurality of individual conductors, said member having a first end provided with means enabling it to be fixed to a motor housing, and a second end laterally flexible relative to said first end, said conductors terminating within said second end and each being fixed to a plug blade extending outwardly of said second end and adapted to be connected to an electrical receptacle.

In still another aspect, the present invention comprises an electrical cord set construction for use with a portable electric device powered from a remote, electric source, which includes a housing, said set comprising a one-piece, elongated member molded in place around a plurality of individual conductors, said member having a strain relief portion formed at one end and provided With means enabling it to be fixed to said housing partly inside and partly outside said housing, said member having a plug portion at its other end with plug blades supported thereby and extending outwardly therebeyond, said plug blades being connected to respective ones of said conductors said plug portion being laterally flexible relative to said strain relief portion.

DETAILED DESCRIPTION Referring now more specifically to the drawings, a portable electric device embodying the present invention is shown generally at 21 in FIG. 1 and is seen to be a hedge and shrub trimmer having a motor housing 23 provided with a pair of handles 25, 27. An electric motor (not shown) is disposed within the housing 23 and is adapted to reciprocate a blade 29 which is sandwiched between a fixed comb 31 and a cover plate 33 in the usual manner. Electric current is supplied to the motor (not shown) from a remote electric source through electrical conductors within a novel plug and strain relief 35 which depends from the housing 23 at the handle 27. The motor (not shown) is controlled by a switch 37 conveniently positioned on the handle 27.

It has been the custom, particularly with tools and appliances requiring relatively long cords such as, for example, electric lawn and garden tools, to provide the tool with a relatively short, permanent cord having a male plug at the outer end thereof. Then, the user can select an extension cord of a length to suit his needs and connect this extension cord to the short permanent cord on the tool and to a suitable wall receptacle.

In the past, the short, permanent cord on the tool consisted of a length of conventional electric line cord made up of separate, insulated wires or conductors 39, 41, 43 wrapped in a jute filler 45 and the latter wrapped in an outer, insulating sheath 47. (See FIGS. 2 and 2A.) Alternatively, other conventional electric line cords have these individual conductors set in a body of insulating material. These short, permanent cords customarily have a strain relief 49 of a suitably strong but flexible, preferably rubbery or plastic material molded thereon, and the purpose of which is to prevent stress concentration on the cord where it exits the motor housing. Thus, the strain relief 49 generally is provided with means such as a peripheral recess 51 near one end within which is received a projection (not shown) on the motor housing, with which it is used, to clamp this end of the strain relief 49 securely to the motor housing. The outer end of the cord 38 is then stripped back to expose the individual conductors 39, 41, 43 and a plug 53 mounted or molded thereon with suitable plug blades 55, 57, 59 I connected to the individual conductors '39, 41, 43, respectively.

It will be appreciated that the process of stripping back the outer end of the electric cord 38, Le, stripping the outer sheath 47, the jute filler 45 and the insulation on the conductors 39, 41, 43, is a relatively tedious, time consuming and therefore expensive proposition. In addition, attachment of the separate strain relief and plug required two separate operations which also added cost. The present invention greatly simplifies the forming and assembly sequence for these permanent, short cord sets by eliminating the aforesaid cord stripping task and the separate strain relief and plug attachment operations.

Thus, as shown in FIGS. 3 and 4, the cord set 35 of the present invention comprises a one-piece member 61 constructed from a suitable strong and flexible material, such as rubber or any of a number of thermoplastic or thermosetting resinous materials and which is molded directly on the individual conductors 39, 41, 43. The member 61 includes a strain relief portion 62 and a plug portion 64, the former having a peripheral recess 63 for attachment to the motor housing handle 27 and the latter has the plug blades 55, 57, 59 set therein. The strain relief portion 62 may be tapered, as shown, and preferably is slotted as at 78 for increased flexibility. Thus, instead of a separate strain relief 49 and plug 53 as in the prior art illustrated in FIG. 2, the present invention has a single member 61 performing both functions.

More importantly, however, this novel construction eliminates the complex stripping sequence referred to above. Thus, the cord set 35 of the present invention is formed by molding the one-piece member 61 around the individual conductors, 39, 41, 43, which have previously been attached to the plug blades 55, 57, 59. As shown in FIG. 6, the individaul conductors 39, 41, 43 are attached to the plug blades 55, 57, 59 and this assembly is set into a cavity 64 in a multi-section mold 65. The mold cavity 64 is shaped corresponding to the desired shape of the cord set body 61, and is provided with suitable pockets 67, 68, 69 for properly positioning and supporting the plug blades 55, 57, 59 and with locators or supports 70, 72, 74, 76 to properly support the conductors 39, 41, 43. The conductors 39, 41, 43, extend through an aperture 66 in the mold 65 and may lay loose in the cavity 64, being held in place and in close relation by and upon the supports 70, 72, 74, 76, or, if desired, they may be held together by a sheath 71 or tape 73 as shown in FIGS. 4A and 4B.

In any case, after the conductors 39, 41, 43 and blades 55, 57, 59 are in position within the mold 65, molten rubber or plastic material is delivered to and fills the cavity 64 as shown in FIG. 7. The plastic material is then allowed to cure which, in the case of thermoplastic materials, such as vinyl, requires cooling to room temperature in the mold 65, and in the case of thermosetting materials requires heating the material to an elevated temperature while in the mold. The cord set 35 is then completely formed and is ready for use and as assembled to the electric tool, appliance or the like simply by attaching the free ends of the conductors 39, 41, 43 to the motor (not shown), to ground and to the switch 37, and thereafter securing the end of the member 61 having the recess 63 to the motor housing 27, in this case, the handle part 27.

The supports 70, 72, 74, 76 form the complementary shaped, longitudinally extending slots 78 (only one of which is shown in FIG. 3) in the member 61 which, as described above contribute to this members flexibility in use. Thus, the cord set 35, and particularly the member 61, performs all the functions of the prior art arrangements, which included a separate strain relief 49 and plug 53, but does this with only a single member formed in a single operation and without the cumbersome and difficult task of stripping back the outer sheath 47 and filler 45, or the solid insulating outer body of the conventional electric line cord used in the prior art, short cord sets. This reduces the cost considerably and in addition provides a neater and stronger cord set construction.

FIG. 8 illustrates an additional inventive feature which may be employed with the integrally molded cord set disclosed above. Thus, the cord set 35A of FIG. 8 incorporates an extension cord connector 77 which could be separately formed and attached to the cord set body but which preferably is integrally molded with the cord set member 61A. The cord connector 77 is an elongated, flexible, generally flat body which extends somewhat beyond the plug part of the member 61A. The connector has two serially arranged slots 79, 81 cut into opposite sides thereof and which are adapted to receive and retain an extension cord 83 as shown. The extension cord 83 has a female plug receptacle 85 adapted to receive the plug blades on the member 51A while the other end of the extension 83 may be plugged into a wall receptacle (not shown). The connector 77 serves to prevent the extension receptacle 85 from pulling loose from the member 61A.

By the foregoing, there has been disclosed an improved cord set construction and method of manufacture thereof calculated to fulfill the inventive objects hereinabove set forth, and while a preferred embodiment of the present invention has been illustrated and described in detail, various additions, substitutions, modifications and omissions may be made thereto without departing from the spirit of the invention.

We claim:

1. In a portable electric device of the type having a housing, an electric motor within said housing and adapted to be powered from a remote electrical source, electrical conductors interconnected with said motor and adapted to extend outwardly of said housing and each having a plug blade connected to its end; the improvement which comprises a one-piece elongated member molded around said plug blades and said conductors outwardly of said housing, said member having means at one end enabling it to be fixed to said housing and its other end supporting and locating said plug blades for connection to a complementary, electrical receptacle, said member having a flexible intermediate portion allowing relative lateral movement between said ends.

2. The improvement of claim 1 wherein said one-piece memeber includes an extension cord connector which comprises an elongated, flat member extending beyond said plug blades and having at least two serially arranged slots cut into opposite sides thereof.

3. The improvement of claim 1 wherein said one-piece member is tapered in cross-section at an intermediate area between said ends.

4. The improvement of claim 1 wherein said one-piece member is provided with longitudinal slots at an intermediate area between said ends.

5. An electrical cord set construction which comprises a one-piece, elongated flexible member molded in place around a plurality of individual conductors, said member having a first end provided with means enabling it to be fixed to a motor housing, and a second end laterally flexible relative to said first end, said conductors terminating within said second end and each being fixed to a plug blade extending outwardly of said second end and adapted to be connected to an electrical receptacle.

6. A construction as defined in claim 5 wherein said one-piece member includes an extension cord connector which comprises an elongated, flexible member extending beyond said plug blades and having a plurality of serially arranged slots therein adapted to receive and retain an extension cord thereto.

7. A construction as defined in claim 5 wherein said one-piece member includes a strain relief portion including said first end and a plug portion including said second end, at least a part of said strain relief portion being tapered in cross-section.

8. A construction as defined in claim 5 wherein said one-piece member includes a strain relief portion including said first end and a plug portion including said second end, at least a part of said strain relief portion having longitudinal slots therein.

9. An electrical cord set construction for use with a portable electric device powered from a remote, electric source, which includes a housing, said set comprising a one-piece, elongated member molded in place around a References Cited UNITED STATES PATENTS 1,611,014 12/1926 Frantz 339-62 1,970,665 8/ 1934 Martinet 339-101 2,461,427 2/ 1949 Kneebone. 3,093,432 6/1963 King 339-59 3,440,592 4/ 1969 Zelle 339-14 3,444,618 5/ 1969 Sorlie 29-629 FOREIGN PATENTS 1,164,361 5/1958 France. 1,437,316 3/ 1966 France.

116,006 3/ 1946 Sweden.

MARVIN A. CHAMPION, Primary Examiner J. H. MCGLYNN, Assistant Examiner US. Cl. X.R.

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