Patent Publication Number: US-5425645-A

Title: Electric power cord connector having two axes of movement

Description:
FIELD OF THE INVENTION 
     The present invention relates to flexible electrical power connectors and, more specifically, to a rotatable and pivotable connector useful for hair dryers and other hand-held small appliances. 
     BACKGROUND OF THE INVENTION 
     At the present time, electrical power cords are generally connected to hand-held small appliances, such as hair dryers, by passing an electric cord through a resilient sleeve connected to the appliance. However, the sleeve allows for little or virtually no degree of movement in any direction. Thus, when the appliance is turned, the cord may become twisted or even knotted. It is an inconvenience to untangle the cord and a tangled cord may be unsightly. Additionally, twisting of the cord causes much stress and strain of the cord at the point where the cord exits the appliance body, thereby ultimately resulting in a break or split in the insulative outer body of the cord. Once the cord insulation is broken, the electrical wires contained therewithin may be exposed. This poses a high safety concern for the user. Accordingly, by preventing twisting of the cord, we are able to produce a product that is not only convenient, but also much safer and has a longer life. 
     It has been suggested, in a series of patents, that a commutator-brush type of electrical connection may be used to provide a rotative connector. This permits the appliance to be turned about one axis without twisting the power cord. However, it does not provide for any other movement. 
     U.S. Pat. No. 4,040,896 (&#39;896 patent), entitled &#34;Electric Device Having Rotary Current Collecting Means&#34;, is directed to a three part structure having an inner rotatable electrode carrier (&#34;device body 5&#34;or &#34;first conductor carrier&#34;) and a housing (&#34;device body 2&#34;). 
     U.S. Pat. No. 4,061,381 (&#39;381 patent), entitled &#34;Twist Prevention Device&#34;, relates to a rotatable cable connector. It shows two helically wound connectors forming a wire spring. 
     U.S. Pat. No. 3,937,543 (&#39;543 patent), entitled &#34;Electrical Swivel Contact Assembly&#34;, relates to a system in which one pair of contacts is spring-biased and another pair of contacts is through the spring. 
     Other patents on swiveling electrical connections for hand-held appliances are U.S. Pat. Nos. 3,950,052; 4,003,616 and 3,957,331. 
     OBJECTIVES OF THE INVENTION 
     It is an object of the present invention to provide an electrical connection between a power cord and a hand-held appliance which permits the appliance to be rotated, about one axis, and pivoted in pendulum fashion, about a different axis, without twisting the power cord. 
     It is a further object of the present invention that the electrical connection be sturdy and reliable so that power to the appliance is continued even when the appliance is being twisted or moved from side to side. 
     It is yet a further object of the present invention to provide such a connection for a hand-held hair dryer so that it can be manipulated by the user without tangling or damaging the power cord or interrupting the power, and permits the cord to extend downwardly while the hair dryer is being used. 
     SUMMARY OF THE INVENTION 
     The present invention provides an electrical connector between a power cord and a hand-held appliance, such as a hair dryer, in which the appliance may be rotated about one axis, and pivoted like a pendulum about an axis perpendicular to the axis of rotation, without detrimentally twisting the power cord. 
     The connector comprises two half outer case housings affixed together to form a cylindrical outer case which is an integral part of, or fixed within, a hand-held appliance, such as a hair dryer. The outer case preferably has a cover portion with two slits therein, through which protrude two prong-like spring contacts. 
     Two cylindrically shaped half inner housings are affixed together to form a rotor-like main housing which is supported and rotatable within the outer case. Two metal conductor slip rings are concentrically fixed onto respective cylindrical portions on the top of the main housing via, for example, a friction fit, and are in continuous electrical contact with the two spring contacts extending from the outer case. 
     A T-shaped cord bushing has a central vertical bore, through which a power cord passes, and horizontal arms supported within the main housing to drive the main housing in rotating fashion. The vertical portion of the cord bushing extends out of said housings and appliance to provide a pivoting motion to the power cord. The power cord extending through the central bore of the cord bushing enters the main housing and splits into two lead wires, each of which is in electrical connection with one of the metal conductor slip rings positioned atop the main housing. 
     The cord bushing permits the power cord to have a swing-like pendulum effect without creating any stress or strain on the cord. The rotation of the main housing, which carries the cord bushing therewithin, permits the appliance to be rotated relative to the axis of the power cord without twisting the cord. Thus, the power cord is provided with two axes of movement. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objectives and features of the present invention will be apparent from the following detailed description taken conjunction with the accompanying drawings. In the drawings: 
     FIG. 1 is a side cross-sectional view of the connector of the present invention; and 
     FIG. 2 is a perspective and exploded view of the connector of FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in FIG. 1, the handle of a hand-held appliance, shown partially at 1, such as a hair dryer, curling iron, or electric toothbrush has a conventional electrical power cord 2 exiting therefrom and adapted to be plugged into an electrical power source at one end (not shown). The other end of the power cord 2 splits into two lead wires 3, 4 which carry the current from the electrical source to power the appliance. 
     The connector of the present invention includes an outer case housing 5, which is held within the appliance 1 by either a compressive or friction fit within the inner body of appliance 1, or by some other means of securement. Alternatively, the outer casing 5 can be an integrally formed part of the inner body of appliance 1. The case housing 5 preferably consists of a cylindrical hollow left chamber half 6 and a cylindrical hollow right chamber half 7, as clearly shown in FIG. 2. Of course, the two outer case halves can alternatively be top and bottom halves instead. In a preferred embodiment, the outer case housing 5 has a top cover portion 8, two slits 14 and 16, an annular internal central flange 9 and a bottom flange 10 with an annular base opening 11. The central and bottom flanges serve to rotatively support an inner main housing therewithin and prevent vertical movement thereof. A first prong-like elongated spring 13 (contact brush) extends through slit 14 in cover portion 8, and a second similar spring 15 extends through slit 16. The springs 13, 15 are fixedly held in place in slits 14, 16. The springs 13, 15 are electrically connected at one end to a switch assembly (not shown) of the appliance. In an alternative embodiment (not shown), the springs can be fastened to an interior wall of the outer case housing and extend radially therefrom to the center of the outer case housing chamber. 
     Inner main housing 12 acts as a rotor relative to the outer case housing 5. Inner main housing 12 is rotatively supported between central flange 9 and bottom flange 10 of outer casing 5. Inner main housing 12 typically consists of left half 17 and right half 18, each of which is a generally cylindrical hollow member having a stepped portion at the top thereof. Of course, as with outer case housing 5, the two halves of inner main housing 12 can possibly be top and bottom halves instead. The stepped portion of inner main housing 12 has a first ring portion 19, a first step 20, a second ring portion 21, and a second step 22. Metal conductor slip rings 23, 24 fit concentrically about ring portions 19, 21 respectively, sitting atop steps 20, 22, respectively. Conductor slip rings 23 and 24 are held via a compressive friction fit onto the exterior of ring portions 19 and 21. Through-holes 25, 26 in ring portions 19, 21 provide openings through which exposed lead wires 3, 4 can pass and electrically contact slip rings 23, 24, respectively. In turn, conductor rings 23, 24 are in electrical contact with springs 13, 15 extending downwardly from cover 8 of case housing 5. Alternatively, as previously mentioned, the springs may extend radially inward from an interior wall of case housing 5 in direct electrical contact with conductor rings 23, 24. The compressive force of springs 13, 15 against conductor rings 23, 24 assures continuous electrical contact therebetween, even upon movement thereof caused by the rotating motion of inner main housing 12. The connection created between the electrical power source, power cord 2, lead wires 3, 4, conductor rings 23, 24, spring contacts 13, 15 and the switch/motor assembly of appliance 1 completes the electrical circuit to power the appliance. The conductor slip rings 23, 24 not only conduct electricity from the power cord 2, but also help to maintain inner main housing halves 17 and 18 together via a compressive force. Additionally, the tight fit of conductor rings 23, 24 around ring portions 19, 21 further serves to firmly and tightly wedge the exposed lead wires 3, 4 between the outside surface of ring portions 19, 21, respectively, and the inside surface of conductor rings 23, 24, respectively. This further prevents the power cord 2 from being yanked out of the appliance body. 
     The bottom portion of inner main housing 12 typically consists of a left bearing half 27 and left socket 29, and a right bearing half 28 and right socket 30 for supporting a T-shaped cord bushing 31. Bearings 27, 28 can be integrally formed with the bottom of inner main housing 12. The bottom of inner main housing 12 has a rectangular opening 32 large enough to permit cord bushing 31 to extend therethrough and have a pendulum motion of close to 90 degrees. 
     T-shaped cord bushing 31 has a horizontal top portion with oppositely extending cylindrical arms 32, 33 and a central lower vertical portion 34 with a bore therethrough creating openings at the top 35 and bottom 36 of cord bushing 31. The arms 32, 33 rotatively fit into sockets 29, 30 formed within bearings 27, 28 of inner main housing halves 17, 18, respectively, to provide a rocking motion to the cord bushing 31. 
     The power cord 2 extends through the bore of the cord bushing vertical portion 34 and is integrally molded with the top 35 and bottom 36 openings thereof. This provides strength to the part of the connection at the joint of power cord 2 and appliance body 1. This also serves to further prevent the possibility of power cord 2 from being yanked out of the appliance body. 
     Preferably, the outer case housing 5, the inner main housing 12, and cord bushing 31 are injection molded from a suitable low-friction plastic insulative resin such as polypropylene, acetal, nylon and polyesters. Preferably, the cord bushing 31 is molded to the power cord 2. The conductor slip rings 23, 24, inner main housing 12 and lead wires 3, 4 extending through holes 25, 26 must be properly dimensioned to allow for a good, custom fit. 
     As is evident, the power cord 2 has two axes of movement; one of which is a rotating motion about a central axis of inner main housing 12. As cord bushing 31 rotates, it drives inner main housing 12 in similar freely rotating fashion within outer case housing 5. Even though conductor slip rings 23 and 24 rotate along with inner main housing 12, the elongated springs 13 and 15 extending vertically downward (or radially inward) from outer case housing 5 remain firmly compressed against the outer surfaces of conductor slip rings 23 and 24, respectively, to maintain a continuous electrical circuit. The second axis of movement of the power cord is a pendulum motion created by the rocking of the cord bushing 31 within the rectangular opening 32 formed at the base of inner main housing 20. It should be understood that the power cord can rotate about the central vertical axis of outer case housing 5 even when cord bushing 31 is not perfectly vertical. To maintain an electrical contact while providing two axes of movement to a power cord is a great improvement over that heretofore known in the art. 
     It will of course be appreciated that the embodiment which has just been described has been given purely by way of illustration and may be modified as to detail without thereby departing from the basic principles of the invention. It is intended that such other modifications are encompassed within the scope of this description.