Electrically Heated Hair-curling Instrument

Abstract

A hair-curling instrument embodies a heat conductive shell which is internally heated by an electric heating element and which is supported from a hollow handle by means of an arrangement which inhibits the transfer of heat from the heating element to the handle. A tubular rivet extending through an aperture in an end closure on the shell and an opening in the end of the handle holds the handle and shell in axial alignment. The heating element leads pass through the rivet. Thermally nonconductive spacers secured to the handle end and seated in recesses in the shell end closure are interposed between the shell closure and the handle end so as to define air gap between the confronting surfaces of the handle end and the closure member.

Description

BACKGROUND OF THE INVENTION

The curling of hair through the use of heat is an ancient art. Up until quite recent times, it had fallen out of vogue as a means of curling other than at professional salons, due principally to the complexity of equipment and desire to save time. Instead, the cold wave kit became the most utilized form of home hair treatment.

As noted above, both costly equipment and the time required to obtain a satisfactory curl have posed problems in promoting widespread home curling with the heated curlers. Recent developments in the field have, however, resulted in a trend back toward the use of heat. See, for example, the U.S. Pat. to McNair, Nos. 3,250,895 and 3,283,122, which deal with quick heating heat transfer units which are operable to provide the heat necessary for curling and are convenient to use at home.

While devices such as mentioned above were a great improvement, still a problem which has long plagued manufacturers of curling irons and the like is one of obtaining a "hot iron" while preventing the handle from becoming so hot that it is uncomfortable to hold or worse, either damages the holder or is itself damaged. In most cases, this has been solved, if at all, by reducing the temperature to which the "iron" or heating unit is heated, or alternatively, through employment of expensive insulating constructions for protecting the handle. The use of lower heats has the drawback that it takes longer to achieve the curl and, of course, the drawback as to the utilization of expensive instrument construction is that it becomes unavailable to the average consumer.

SUMMARY OF THE INVENTION

The present invention derived from an effort to provide a low-cost, lightweight, portable electric heating unit for use in conjunction with hair-curling rolls like those disclosed in the aforesaid McNair patents and which would be capable of being held comfortably while still putting out heat at a greater rate than in conventional instruments. To this end, I conceived a construction which embodies a heat conductive shell which is internally heated by an electric heating element and which is supported from a handle by means of a support arrangement which effectively inhibits heat transfer from the heating element to the handle through a combination of limiting the rate of and pathways open to direct conduction and providing for convection dissipation of heat at the interface between the handle and heat transfer unit. All this is achieved while still obtaining optimum utilization of the heat supplied by the heating element.

A hair-curling instrument according to my invention has additional advantages in that it is light and easy to handle, can be manufactured and assembled with relative ease and at low cost (considering the benefits gained) and can be made quite attractive in appearance.

Other objects and advantages of devices embodying the invention will appear in the course of the following description.

DETAILED DESCRIPTION

in the accompanying drawing, which forms a part of the specification and is to be read in conjunction therewith, and in which like reference numerals indicate like parts in the various views;

FIG. 1 is an elevational view of a preferred form of the hair curling instrument embodying the invention;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1 in the direction of the arrows;

FIG. 3 is a perspective view showing the component parts absent the heating unit shell in exploded relationship;

FIG. 4 is an end view of the handle-mounted heat barrier element;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4 in the direction of the arrows; and

FIG. 6 is a perspective view showing the heat unit closure member in an inverted position from that illustrated in FIG. 3.

Referring now to the drawing and initially to FIGS. 1 and 2, the basic components of the preferred instrument illustrated therein comprise a handle 10 and a heat transfer unit 11 which is connected to and supported from one end of the handle. As seen in FIG. 2, the handle 10 has a recessed free end 10a in which are supported two electric terminal prongs 13 by which the implement may be connected with the plug (not shown) of a conventional electric cord leading to a source of electrical energy.

The heat transfer unit 11 includes a hollow cylindrical shell 14 having the upper or outer closed end 15. Preferably, the shell is composed of aluminum or other material having good heat conductivity.

Positioned interiorly of the shell is an electric heating element which comprises the heat-resistant plate member 16 on which is wrapped or wound an electric resistance heating wire 17. The width of the plate 16 is such that it fits easily within the interior of the shell 14.

The ends of the resistance wire 17 are respectively connected with a short conductor 18 and a longer conductor wire 19. The wire 18 is in turn electrically connected with an electrically nonconductive base member 20 which forms the base of a thermostatic switch having the bimetal thermal element 21. The thermal element operates to open and close a contact at 22 in response to predetermined temperature limits. The fixed end of the bimetal element is connected with a contact at 23 and this contact is in turn connected with another conductor 24.

The open lower end of the shell 14 is closed by means of a pluglike closure member 25 which fits telescopically within the end of the shell and which is composed of metal. The rim of the member 25 is provided with a circumferential groove 26. The shell is joined with the closure 25 by striking metal segments 14a into the groove at at least two points around the shell. The closure member is positioned properly within the shell by means of an end flange 27 which provides a shoulder which seats against the confronting end edge of the shell.

The closure member 25 is provided with a central aperture 25a. Received through this aperture and extending well beyond the closure member is the barrel portion 29 of a hollow rivet having the flanged head 29a which seats on the inside end of the closure member. The electric leads 19 and 24, which incidentally are thermally insulated, exit from the shell 14 through the axis of the rivet 29.

The heating unit 11 is completed by inclusion on the interior of shell 14 at the upper end of ceramic heat storage elements 30 which are press fitted into the interior of the shell.

The handle 10 includes the main handle portion 12 which may be made of any satisfactory plastic such as, for example, a molded high density polyethylene. The handle may be given any shape comfortable to the hand. The handle illustrated is a hollow handle having the relatively large head portion 12a which is formed internally with a counterbore 12b defining an annular shoulder 12c.

Press fitted within the counterbore 12b is an inverted cup-shaped end member 31. This member is constructed of a material having an extremely high resistance both to conductivity of and destruction by heat. Preferably, it is molded from a phenolic resin. While its form may vary, it has in the illustrated embodiment, a cylindrical skirt portion 31a which is slotted longitudinally at 31b in order to permit the necessary resilient flexing of the skirt for press fitting the end member into the end bore of the handle. The skirt depends from a web portion 31c which is centrally apertured at 31d to permit the passage therethrough of the rivet barrel 29 with the contained electric leads. The rivet is, of course, headed as at 29b on the underside of the web 31c to join the components 10 and 11 together.

Formed on the outer face of the web 31c of the handle end member are a plurality (in the illustrated embodiment, four) of spaced posts 31f. The posts are equiangularly spaced around the center of the end member. The posts are formed integrally with the end member.

The posts are of sufficient length to insure that when engaged with the outside face of the end closure 25 on the heat unit 11, the surface of the end closure will be spaced at all the points from any portion of the handle 10. Consequently, the posts serve to form a substantial air gap between the heat unit 11 and the handle through which air is free to circulate and from which convection currents can readily escape.

The posts also serve, as part of the connecting means between the handle 10 and heat transfer unit 11, to insure against twisting displacement of one component relative to the other. As can be best seen in FIG. 6, the outside, or under, face of the closure member 25 of the heat transfer unit is provided with a plurality of shallow cavities or recesses which are located to register respectively with the ends of the posts 31f. The post ends seat within these recesses and obviously any twisting of the heat transfer unit 11 relative to the handle 10 is effectively resisted.

To aid in maintaining the handle end member 31 within the receptacle, the surface of the counterbore 12b of the handle is provided near the outer end of the counterbore with a plurality of bosses or lips 12d. The overall length of the handle end insert member 31 is made such that when inserted to its seating depth, the upper or outer edge of the insert will be inside the lips. The material of which the handle is constructed is significantly flexible and resilient as to permit the lips 12d to give during insertion of the member 31, after which they will return to the projecting position and serve as lugs limiting outward displacement of the member.

From the foregoing, it will be evident that I have achieved all of the objects and advantages hereinbefore set forth. The "stand off" arrangement which separates the heated portions of the heating unit 11 from contact with the handle 10 limits greatly the direct conductively of heat. The only pathways open to direct conduction are the posts 31f and the very small cross-sectional area provided by the barrel of the rivet 29. Since the posts 31f are made of thermally nonconductive material, they provide very little, if any, conductivity. In addition, the air space provided between the two units through the construction described permits of ready dissipation of heat liberated at the outer surface of the plug 25. The normal and natural motions of the operator in handling the unit will assure of continuous dissipation of heat by convection and circulation from the zone between the heating unit and handle.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

Claims

I claim:

1. A hair-curling heating instrument comprising:

a hollow heat conductive shell,

a heat-conducting closure member closing one end of said shell,

a heating element within the shell having electric leads which exit from the shell through an aperture in said closure member,

a hollow handle having a closed end, said handle positioned with its said end confronting said end closure member of said shell, said leads extending into said handle through an opening in said handle end,

a tubular rivet extending through the aperture and opening respectively on said closure member and handle end and holding said handle and shell in axial alignment, said leads passing through said rivet, and

thermally nonconductive spacer means interposed between said shell closure member and handle end so constructed and positioned as to define a substantial air gap between the major confronting surfaces of said handle end and closure member for free air circulation therebetween, said spacer means secured to sad handle end and having end portions seated in recesses in said shell closure member to prevent said handle member and closure member from twisting relative to one another.