Patent Publication Number: US-6335489-B1

Title: Connecting device for high-voltage cable

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a connecting device used for connecting a high-voltage cable to a connector portion provided in a transformer. The transformer generates a high electrical voltage. The high electrical voltage thus produced is applied to electrical apparatuses, such as office or home appliances for different purposes. The connecting device according to the invention is used for sending the high electrical voltage to the electrical apparatuses. Further, the invention concerns methods of connecting such a high-voltage cable to a transformer. 
     2. Description of Background Information 
     FIG. 1 shows a known connecting technique, according to which a high-voltage cable used for sending a high electrical voltage is connected to a connector portion  3  of a transformer  1  in such electrical apparatuses. With this technique, once a connector portion  3  of the transformer  1  is connected to a high-voltage cable  5  for sending a high electrical voltage, there is no need to detach them. Accordingly, the high-voltage cable  5  is stripped off of its coating, thereby yielding a conductive portion  5   a,  and the conductive portion  5   a  is soldered to the connector portion  3  of transformer  1 . 
     The transformer  1  comprises a vertically-extending housing  7 . The housing  7  contains a primary coil and a secondary coil which generate high electrical voltages as a function of the inputted variable current. The housing  7  may also contain various electronic parts such as condensers, diodes or impedance elements, connected to each coil. The housing  7  is provided with a hollow portion  7   a  and a base from which a connector portion  3  of the transformer  1  extends into the hollow portion  7   a.  The end portion of the secondary coil of transformer  1  may thus be connected to an electronic component. The latter includes an end section which may form a rod-shaped terminal portion. Accordingly, the connector portion  3  of transformer  1  may be comprised of the terminal portion of an impedance element, e.g. a capacitor in the housing  7 . However, the connector portion  3  of transformer  1  may also be comprised of a lead wire extending from the electronic component. 
     The high-voltage cable  5  usually has a conductive portion  5   a  consisting of a plurality of copper wires, and a resin coating. When the high-voltage cable  5  is connected to a connector portion  3  of transformer  1 , an epoxy resin or the like is filled into the hollow portion  7   a,  so that the connected portion between the high-voltage cable and the connector portion  3  of the transformer  1  is sealed with the resin. Thereafter, a rubber grommet  9  is fitted onto part of the circular peripheral zone of the high-voltage cable  5 . The hollow portion  7   a  of housing  7  includes a rectangular side chamber, whose outermost face has a notch  7   b  vertically atop thereof. After the high-voltage cable  5  has been mounted into the housing  7 , the space formed between the notch  7   b  and the high-voltage cable  5  is closed by the rubber grommet  9 , such that the sealing resin is prevented from overflowing. 
     When the transformer  1  generates a high electrical voltage, it also generates noise through the high-voltage cable  5 , and hence a countermeasure for reducing noise becomes necessary. To this end, either a magnetic core is set around the cylindrical outer surface of the high-voltage cable  5 , or an impedance element is inserted in the conductive part of the high-voltage cable  5  so as to curb the noise current flowing in the high-voltage cable  5 . However, these methods yield only a limited effect, and there is a need for a more efficient noise-suppressing technique. 
     To further improve noise-suppressing efficiency, a coiled-type, high-voltage noise-suppressing cable may be used, instead of the high-voltage cable  5 . The coiled-type, high-voltage noise-suppressing cable comprises at least a core element of magnetic material, a coiled portion at least including a conductive wire for passing a high electrical voltage. The coil is helically wound around the core element, and a coating entirely covers the core element and coiled portion. Such a structure is designed to suppress noise efficiently. 
     The conductive wires commonly used in a coiled-type cable for preventing high-voltage noise include wires such as nickel-chromium wires. However, such conductive wires are ill suited for soldering. Accordingly, when using the above technique, the high-voltage cable  5  cannot be soldered directly to the connector portion  3  of the transformer  1 . 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a connecting device with improved noise-suppressing capacity using a coiled-type cable for preventing high-voltage noise and which can easily connect the coiled-type, high-voltage noise-suppressing cable to a transformer, as well as to provide a method of connecting the coiled-type, high-voltage noise-suppressing cable to the transformer. 
     To this end, according to one aspect of the present invention, there is provided a metallic connecting device for connecting a high-voltage electrical cable to a transformer having a connector portion from which a high electrical voltage is outputted. The high-voltage electrical cable includes a coiled-type high-voltage noise-suppressing cable including at least a coiled core element containing a magnetic material and at least a conductive wire through which the high electrical voltage is passed, the conductive wire being wound around the magnetic material, and a coating covering the coiled core element. 
     The connecting device includes a crimping connector portion adapted for press-fitting the coiled-type high-voltage noise-suppressing cable, and a solder connector portion formed in extension of the crimping connector portion and adapted for connecting to the connector portion of the transformer by soldering. 
     In another aspect of the present invention, the transformer is provided with an electronic part including a rod-shaped terminal portion. The connector portion of the transformer may include the rod-shaped terminal portion, while the solder connector portion of the connecting device may be substantially in the form of a cup having a base with a through hole. The rod-shaped terminal portion is then passed through the through hole, and connected and fixed to the solder connector portion by soldering. 
     Alternatively, the solder connector portion of the metallic connecting device may include a substantially flat plate which is put into contact with the rod-shaped terminal portion along the length direction thereof. The rod-shaped terminal portion is then connected and fixed to the solder connector portion by soldering. 
     In a further alternative, the solder connector portion of the connecting device may include a pair of lips extending substantially in parallel, between which the rod-shaped terminal portion is inserted. The rod-shaped terminal portion is then connected and fixed to the solder connector portion by soldering. 
     When using the metallic connecting device of the invention, the coiled-type high-voltage noise-suppressing cable typically includes an end portion which is stripped of its coating so that the coiled portion is exposed. The crimping connector portion may include a first barrel portion in which the coiled portion of the coiled-type high-voltage noise-suppressing cable is press-fitted, and a second barrel portion in which the coiled-type high-voltage noise-suppressing cable is crimped from above its coating. 
     Advantageously, the second barrel portion includes a base wall and a detent formed on the base wall. 
     According to another aspect of the present invention, there is also provided a method of connecting a transformer containing a connector portion to a high-voltage electrical cable having an end portion. The method includes: a) preparing a coiled-type high-voltage noise-suppressing cable used as a high-voltage electrical cable, the coiled-type high-voltage noise-suppressing electrical cable including a coiled core element containing a magnetic material and a coiled portion, the coiled portion including a conductive wire through which a high electrical voltage is passed, the conductive wire being wound around the magnetic material, and a coating covering the coiled core element. 
     The method also includes: b) stripping the end portion of the coating so that the coiled portion is exposed, and c) preparing a connecting device. The metallic connecting device includes a crimping connector portion adapted for press-fitting the coiled-type high-voltage noise-suppressing cable, and a solder connector portion provided in extension of the crimping connector portion and adapted for connecting the connector portion of the transformer to the end portion of coiled-type high-voltage noise-suppressing cable by soldering. 
     The method further includes: d) press-fitting the coiled-type high-voltage noise-suppressing cable in the crimping connector portion, while connecting and fixing the end portion of the coiled-type high-voltage noise-suppressing cable to the connector portion of the transformer by soldering at the solder connector portion, 
     whereby the transformer is connected and fixed to the coiled-type high-voltage noise-suppressing cable via the metallic connecting device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will be made apparent from the following description of the preferred embodiments, given as non-limiting examples, with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view showing how a high-voltage electrical cable is connected to a transformer according to a known technique; 
     FIG. 2 is a top plan view of a metallic connecting device according to a first embodiment of the present invention; 
     FIG. 3 is a cross-sectional side view of the connecting device of FIG. 2 along line I—I; 
     FIG. 4 is a transverse cross-sectional view of the connecting device of FIG. 2 along line II—II; 
     FIG. 5 is a transverse cross-sectional view of the connecting device of FIG. 2 along line III—III; 
     FIG. 6 is a partially exploded side view of a coiled-type high-voltage noise-suppressing cable which is connected to a transformer via the connecting device of FIG. 2; 
     FIG. 7 is a top plan view of the metallic connecting device of FIG. 2 when it is press-fitted to the coiled-type high-voltage noise-suppressing cable of FIG. 6; 
     FIG. 8 is a transverse cross-sectional view of the connecting device of FIG. 7 along line IV—IV; 
     FIG. 9 is a transverse cross-sectional view of the connecting device of FIG. 7 along line V—V; 
     FIG. 10 is a cross-sectional side view of the connecting device of FIG. 2, when it is soldered to a transformer while press-fitted to the coiled-type high-voltage noise-suppressing cable; 
     FIG. 11 is a top plan view of a second embodiment of the connecting device according to the present invention; 
     FIG. 12 is a side view of the second embodiment of FIG. 11, with hidden features shown in phantom; 
     FIG. 13 is an end elevation view of the solder connector portion of the second embodiment of FIG. 11, when it is placed into contact with a connector portion of a transformer; 
     FIG. 14 is a cross-sectional side view of the second embodiment of FIG. 11, when the connecting device is soldered to the connector portion of a transformer; 
     FIG. 15 is a top plan view of a third embodiment of the connecting device according to the present invention; 
     FIG. 16 is a side view of the third embodiment of FIG. 15, with hidden features shown in phantom; and 
     FIG. 17 is a top plan view of the third embodiment of FIG. 15, when it is placed into contact with a connector portion of a transformer. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 2 is a top plan view of the metallic connecting device according to a first embodiment of the present invention. FIGS. 3,  4  and  5  are, respectively, cross-sectional view of the connecting device along lines I—I, II—II and III—III of FIG.  2 . FIG. 6 is a partially exploded view of a coiled-type high-voltage noise-suppressing cable. This cable is connected to a transformer through a metallic connecting device according to the invention. 
     According to the embodiments of the present invention, commonly known high-voltage electrical cables  5  are replaced by coiled-type high-voltage noise-suppressing cables  11  (hereinafter referred to as “noise-suppressing electrical cable”) shown in FIG.  6 . The noise-suppressing electrical cable  11  is connected to a connector portion  3 , mounted in a transformer  1  as shown in FIG. 1, via a connecting device  13  shown in FIGS. 2 to  5 . Otherwise, the configuration of transformer  1  used is the same as the known one. As in the known techniques, the hollow portion  7   a  of transformer  1  is filled with resin after a noise-suppressing electrical cable  11  has been connected. Likewise, the space formed between the noise-suppressing electrical cable  11  and the notched portion  7   b  of the housing  7  is sealed by a rubber grommet  9 . 
     The noise-suppressing electrical cable  11  used in the present embodiments has the following technical features. As shown in FIG. 6, this cable  11  first includes a fibrous reinforcement thread  21   a  formed of glass fibers and synthetic fibers. A resin material mixed with ferrite powder (a magnetic material) is then extruded thereon, yielding a core element  21  having a small diameter. Subsequently, a conductive wire  23  for sending a high-electrical voltage is wound around the core element  21 , to form a coiled portion  25 . Thereafter, the cylindrical outer surface of the coiled portion  25  is covered with a coating  33  comprising a conductive internal layer  27 , an insulating layer  29  and an external sheath  31 . 
     As shown in FIGS. 2 to  5 , the metallic connecting device  13  may be integrally formed by a stamping method from a single metal piece. One end of the connecting device  13  has a crimping connector portion  41  into which a noise-suppressing electrical cable  11  is press-fitted. The other end of connecting device has a solder connector portion  43 , to which a connector portion  3  mounted in the transformer  1  (FIG. 1) is soldered. 
     As shown in FIGS. 4 and 5, the crimping connector portion  41  has a generally U-shaped cross-section. The crimping connector portion  41  may include a first barrel portion  41   a  located at a position to be fitted with the edge side of noise-suppressing electrical cable  11 , a second barrel portion  41   b  located at a position farther therefrom, and a detent  41   c.  The detent  41   c  is cut out from the base wall of the second barrel portion  41   b  and raised inwardly therefrom so as to project into the second barrel portion. 
     In the first barrel portion  41   a,  shown in FIGS. 7 and 9, a coiled portion  25  is exposed by stripping off the coating  33  from the end portion of noise-suppressing electrical cable  11 . The bare coiled portion  25  is then press-fitted into the first barrel portion  41   a  and held therein. In the second barrel portion  41   b,  shown in FIGS. 7 and 8, the coated end portion of noise-suppressing electrical cable  11  is crimped from over its coating  33  and held in the second barrel portion  41   b.    
     As shown in FIG. 8, the second barrel portion  41   b  is longitudinally open, so as to form two longitudinal edges, and holds the noise-suppressing electrical cable  11  by penetrating the longitudinal edges into the coating  33 . By contrast, as shown in FIG. 9, the longitudinal edges of first barrel portion  41   a  hold the coiled portion  25  by wrapping, but without cutting into it. The connector portion  3  of the transformer is thus press-connected to the conductive wire  23  contained in the coiled portion  25 . 
     As shown in FIG. 10, the detent  41   c  is formed by notching part of the base and raising it up along a fulcrum line such that its edge becomes inclined towards the advancing direction of the electrical cable. Accordingly, when the noise-suppressing electrical cable  11  is fixed into the crimping connector portion  41 , the edge of detent  41   c  penetrates into the noise-suppressing electrical cable  11 , so that the latter is prevented from moving back. In this compressed state, the detent  41   c  continuously presses against the outer surface of noise-suppressing electrical cable  11  along the diametrically inward direction by its elastic force. 
     In the first embodiment of the invention, shown in FIGS. 2 and 3, the solder connector portion  43  is in the form of a cup, the base center of which is provided with a through hole  43   a  having a diameter slightly greater than that of the connector portion  3  of transformer  1  (see FIG.  1 ). 
     When a noise-suppressing electrical cable  11  is connected to a transformer  1 , the end portion of the noise-suppressing electrical cable  11  is first stripped of its coating  33 . The noise-suppressing electrical cable  11  having the end portion thus prepared is then inserted into a crimping connector portion  41  of metallic connecting device  13  and press-fitted therein as shown in FIGS. 7 to  9 . The connector portion  3  of transformer  1  is then inserted into the solder connector portion  43  of the connecting device  13  via the through hole  43   a  from the base side of the solder connector portion  43  (see FIG.  10 ). Subsequently, the solder connector portion  43  and the connector portion  3  of the transformer  1  are joined by soldering. Since the solder connector portion  43  is in the form of a cup, the solder  45  forms a mass inside the cup and solidifies. The solder connector portion  43  is thus firmly soldered. 
     According to the above described embodiment, the noise-suppressing electrical cable  11  can be connected to the transformer  1  by means of a connecting device  13 . Because the noise-suppressing electrical cable  11  is used as a high-voltage cable, noise suppression is further improved, compared to the other types of high-voltage cables. Furthermore, the connections between the connecting device  13  and the noise-suppressing electrical cable  11  on the one hand, and between the connecting device  13  and the transformer  1  on the other, are obtained simply by crimping or soldering. The noise-suppressing electrical cable  11  can thus be easily, but reliably, connected to the transformer  1 . 
     Further, the solder connector portion  43  of connecting device  13  is in the form of a cup having a base center which is provided with a through hole  43   a.  By virtue of this configuration, the connector portion  3  of transformer  1  can be inserted into the cup-shaped solder connector portion  43  from the base side thereof, via the through hole  43   a.  Thereafter, the solder connector portion  43  is fixed by soldering. The solder  45  then forms a mass in the solder connector portion  43 , so that the solder connector portion  43  is firmly soldered to the connector portion  3  of transformer  1 . Further, the soldering process is easily carried out, for example, by dripping molten solder onto the solder connector portion  43 . The soldering process is thus simplified. 
     Moreover, the crimping connector portion  41  of connecting device  13  may include a first barrel portion  41   a  in which the coiled portion  25  at the bared end portion of the noise-suppressing electrical cable  11  is held by press-fitting. The crimping connector portion may further include a second barrel portion  41   b  in which the noise-suppressing electrical cable  11  is held by press-fitting from above the coating  33 . In this manner, the noise-suppressing electrical cable  11  can be firmly and reliably connected to the metallic connecting device  13 . 
     When the noise-suppressing electrical cable  11  is press-fitted, the edge portion of detent  41   c  provided in the connecting device  13  penetrates into the outer circular surface of noise-suppressing electrical cable  11 , so that the latter is prevented from being pulled out. Moreover, the detent  41   c  presses the outer circular surface of noise-suppressing electrical cable  11  constantly inwardly by its elastic force, so that the latter is kept stably in a pressed state even after a prolonged use. 
     FIG. 11 shows a top plan view of a connecting device  51  according to a second embodiment (first variant) of the present invention, while FIG. 12 shows a side view thereof. In this second embodiment of the connecting device  51 , the cup-shaped solder connector portion  43  is replaced by a flat-type solder connector portion  53 . 
     As shown in FIGS. 13 and 14, when connecting the connecting device  51  of the second embodiment to the transformer  1 , the flat-type solder connector portion  53  is placed into contact with the connector portion  3  of transformer  1  along its length direction, and soldered. 
     According to the method described above, the flat-type solder connector portion  53  of the metallic connecting device  51  of the second embodiment is very easily soldered to the connector portion  3  of transformer  1 . Further, the flat-type solder connector portion  53  of the metallic connecting device  51  of the second embodiment has a simple, substantially flat shape. The shape of the metallic connecting device  51  constructed therewith can be simplified accordingly, and manufactured more easily. 
     FIG. 15 is a top plan view of a connecting device  61  according to a third embodiment (second variant) of the present invention, while FIG. 16 shows a side view thereof. In the connecting device  61  of the third embodiment, the cup-shaped solder connector portion  43  of the first embodiment is replaced by a lip-type solder connector portion  63  which includes a pair of lips  63   a  and  63   b  extending in parallel from the edge of the crimping connector portion  41 . 
     The lip-type solder connector portion  63  includes a link portion  63   c  which leads to the edge of crimping connector portion  41 , and a pair of flat lips  63   a  and  63   b . The latter is formed by bending each lateral end of the link portions  63   c  downwardly (or upwardly). Both lips  63   a  and  63   b  protrude forwardly (in the insertion direction of the noise-suppressing electrical cable  11 ) from the link portion  63   c.  They face each other along their longitudinal direction over a distance slightly greater than the diameter of connector portion  3  of transformer  1 . 
     As shown in FIG. 17, the connector portion  3  of transformer  1  is flanked by the respective lips  63   a  and  63   b  of the lip-type solder connector portion  6 , and fixed thereto, whereby the connecting device  61  of the third embodiment is connected to the transformer  1 . 
     According to the above embodiment, the connector portion  3  of transformer  1  is interposed between a pair of lips  63   a  and  63   b  of the lip-type solder connector portion  63  of the connecting device  61  of third embodiment, and they are soldered in place. As the connector portion  3  of transformer  1  and the lip-type solder connector portion  63  are positioned as desired beforehand, the soldering process is easily carried out. Furthermore, as the pair of lips  63   a  and  63   b  are soldered while flanking the connector portion  3  of transformer  1 , the mechanical strength of the connecting portion is enhanced. 
     According to the present invention, a high-voltage electrical cable is connected to a transformer through a connecting device. By virtue of this configuration, the coiled-type high-voltage noise-suppressing cable can be used as a high-voltage electrical cable, resulting in a further enhanced noise suppression effect. Furthermore, the connections between the connecting device, the coiled-type high-voltage noise-suppressing cable and the transformer are made by a simple process such as crimping or soldering. As a result, the coiled-type high-voltage noise-suppressing cable and the transformer can be connected easily and reliably. 
     According to a first embodiment, the solder connector portion of connecting device is in the form of a cup provided with a through hole in its base center. A connector portion of the transformer, such as a rod-shaped terminal portion  3 , is then passed through the through hole from the base side of cup-shaped solder connector portion, inserted there into, and soldered in this condition. As the solder forms a mass in the solder connector portion, the latter and the rod-shaped terminal portion are firmly soldered. Moreover, the soldering process is easily carried out by dripping molten solder from above the solder connector portion. The soldering process can thus be greatly simplified. 
     According to a second embodiment, the surface of the solder connector portion of the connecting device is placed into contact with the length direction of a connector portion of transformer  1  such as a rod-shaped terminal portion  3 , and are fixed together by soldering. The soldering process can thus be carried out easily. Moreover, the solder connector portion of the connecting device is formed of a simple, substantially flat plate. By virtue of this simple construction of the solder connector portion, the whole structure of connecting device itself can be simplified. The metallic connecting device can thus be manufactured more easily. 
     According to a third embodiment, a connector portion of the transformer  1 , such as a rod-shaped terminal portion  3 , is inserted between a pair of lips provided in the solder connector portion of the metallic connecting device. The connector portion of transformer  1  and the pair of lips of the connecting device are soldered in this condition, so that the connector portion of the transformer and the solder connector portion of the connecting device can be positioned properly. By virtue of this configuration, the soldering process is easily conducted, and the mechanical strength of connected portions is improved. According to another embodiment, the crimping connector portion of the connecting device includes a first barrel portion, in which the coiled core element, prepared by baring the end portion of coiled-type high-voltage noise-suppressing cable, is held by press-fitting. The crimping connector portion further includes a second barrel portion, in which the coiled-type high-voltage noise-suppressing cable is held by crimping from above its coating. In this manner, the coiled-type high-voltage noise-suppressing cable is firmly and reliably press-connected to the connecting device. 
     Although the invention has been described with reference to particular means, materials and embodiments, it is to be understood that the invention is not limited to the particulars disclosed and extends to all equivalents within the scope of the claims.