Abstract:
An insulating tubeless transformer, by using special winding tubings to achieve the safety requirement and automatic winding without using insulating tubes or other insulation materials, has the advantages of saving material, space reduction and automatic winding.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the structure of a transformer, and more specifically to a transformer for use on an alternative power supply, for the purpose of the transmission and amplification of electronic signals. The invention also concerns the effects of electrical insulations. 
     An alternative power supply as the power source of a computer and its peripheral equipments must conform to electrical safety requirements. There are many international institutions specifying safety inspection standards on electrical items, such as UL, CSA, IEC, etc, and VDE&#39;s standards are considered be the most rigorous. The transformer is one of the major items on the list of safety inspections. As far as the safety structure is concerned, a transformer may be divided into a primary winding coil, a secondary winding coil and an iron core, as shown in FIG. 1B. The primary winding is the portion which connects directly with the input power, and has a higher potential; the potential of the second winding is usually lower, and it is a part which people can easily touch. The iron core then comes as a long conductor. 
     VDE&#39;s safety requirement with respect to transformers is summarized as follows: 
     
         ______________________________________       Absolute resistance       to pressure  Safe distance______________________________________Between the primary         3 750 VAC for 1 min.                        6 mm min.winding and the secondwinding.Between the primary         2 500 VAC for 1 min.                        4 mm min.winding and the ironcore.Between the second         500 VAC for 1 min.                        --winding and the ironcore.______________________________________ 
    
     Up to the present, to meet these above-mentioned requirements, in a traditional transformer, as shown in FIG. 1A, it is a common practice to apply an insulating tube 300 on both the beginning end and the closing end of both the primary winding 100 and the second winding 200. In addition, a clearance of a length no less than 3 mm must be maintained on both sides inside the winding coil in relation to the winding tube. Also at least three layers of tape 400 have to be wound between the primary and the second windings. Such a conventional type of transformer, because of the failure to employ automatic sleeving of the insulating tube, 300 requires more time and labor to manufacture, and is impractical for the application of automatic winding. 
     SUMMARY OF THE INVENTION 
     In view of the many defects found with conventional transformers disclosed hereinbefore, it is an object of the present invention to provide a newly structured transformer. According to the transformer of the invention, no insulating tube is needed to be applied on either the beginning or the terminating end of either the primary winding or the secondary winding, and no tape is required to be wound between the primary and secondary windings, thereby saving material. Also, the absence of a conventional insulating tube makes possible automatic winding, thereby promoting productivity. 
     According to the transformer of the invention, the transformer doesn&#39;t have to observe a clearance of 3 mm with regard to the interior rim of the winding tube, so that the utility rate of the winding window can be increased, thereby reducing the volume of the iron core, which meets another object of the present invention. 
     A more complete understanding of these and other features and advantages of the present invention will become apparent from a careful consideration of the following detailed description of an embodiment which is illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a cross-sectional view of a conventional transformer. 
     FIG. 1B is an electrical circuit of a transformer. 
     FIG. 2 is a three-dimensional perspective view of the transformer of the invention. 
     FIG. 3 is a cross-sectional view of the whole embodiment of the invention. 
     FIG. 4 is an illustration of the winding tubing used in the transformer of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in FIG. 2 and FIG. 3, the transformer of the invention has two identical winding tubing 1, 2, each comprising essentially a tubing 11, 21 and a seat 12, 22, as shown in FIG. 4. The tubings 11, 21 are each shaped like a clevis, that is, U-shaped in cross section. The tops of the seats 12 and 22 and the tops of the tubings 11 and 21 are respectively provided with externally extending partitions 13, 23 and 14, 24, wherein the partitions 13, 23 at the top section of the respective tubings 11 and 21 extend a small distance toward open mouths thereof. Recesses in the seats 12, 22 are respectively in communication with the interiors 10 and 20 of the tubings 11 and 21. The partitions 13, 14 and 23, 24 are initially all extending in planes perpendicular to the axes of the tubings. Therefore, it is possible to wind the coil over the tubings 11, 21 between the partitions 13, 14, 23, 24 by means of an automatic winder in order to assemble the winding tubing 1, 2. After winding, the partitions 13, 14, 23, 24 are to be folded into the central section of the tubing so as to bring partition 13, 14 respectively close to partition 23, 24. Finally, U-shaped iron cores 31 and 32 are inserted into opposite ends of tubings 11, 21 to obtain the whole embodiment of the transformer of the invention. 
     The clearance of 6 mm for the interspacing between the primary winding coil and the secondary winding coil of the transformer can be achieved by bending the partitions in the tubings, with the advantage that the partitions 13, 23 on top of the tubings 11, 21 can serve to restrict the position of the upper iron core. Therefore, the nearest distance between the iron cores from the primary and secondary winding coils can be greater than what is required, say, 4 mm. Furthermore, as it is not necessary to maintain a distance of 3 mm on the interior rim during the coil running, which is otherwise necessary in conventional cases, it is achieved to greatly enhance the utility rate of the coil window around the iron core. This serves to reduce the relative volume of the iron core by one third or so, the other material costs can be reduced by up to one third, and the manufacturing time can be reduced by up to 50%. It is therefore of practical use. 
     Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made by way of example and that changes in details of structure may be made without departing from the spirit thereof.