Power supply line for high-frequency current, manufacturing method for same, and power supply line holding structure

A power supply line for high-frequency current has a two-layered tubular conductor including an inner tube portion and an outer tube portion which is concentric to the inner tube portion and integrally linked thereto by four connecting portions along the entire length in the longitudinal direction. The four connecting portions are circumferentially disposed at predetermined intervals. By providing the four connection portions between the inner tube portion and the outer tube portion, it is possible to more accurately position the inner tube portion and to reduce high frequency resistance when compared with the likes of conventional power supply lines for high-frequency current having only one connecting portion between an inner tube portion and an outer tube portion.

FIELD OF THE INVENTION

The present invention relates to a power supply line for high-frequency current through which a high-frequency current flows, a power supply line manufacturing method and a power supply line holding structure for holding the power supply line.

BACKGROUND OF THE INVENTION

Conventionally, there is available a trolley system including a vehicle, such as a travelling hoist or a transfer mover, and a power supply device for supplying electric power to the vehicle. In the power supply device, electric power is exchanged between a power supply line arranged along a vehicle-travelling rail and a power receiver provided in the vehicle. The electric power received by the power receiver is supplied to the vehicle. One example of the power supply line is disclosed in Patent Document 1.

FIG. 12is a perspective view showing the outward appearance of a power supply line for high-frequency current disclosed in Patent Document 1.FIG. 13is a vertical section view showing a modified example of the power supply line shown inFIG. 12, which employs another conductor formed by extruding copper. As shown inFIGS. 12 and 13, the power supply line for high-frequency current100includes a two-layered tubular conductor200embedded in an insulating body300. The conductor200includes an inner tube portion200aand a concentric outer tube portion200bone-piece connected to the inner tube portion200aby a connecting portion200cover the longitudinal full length of the conductor200. The insulating body300is not arranged in the spatial portions400aand400bof the respective tube portions200aand200b.

In the example shown inFIG. 12, a conductor200is formed by, e.g., bending a single copper plate. More specifically, an inner tube portion200ais formed by bending the central portion of a plate into an annular cross-sectional shape. Two planar piece portions extending downward inFIG. 12from the opposite ends of the annular portion forming the inner tube portion200aare formed in a parallel-extending contact relationship with each other. An outer tube portion200bof annular cross-sectional shape concentric with the inner tube portion200ais formed by bending the planar piece portions into an arc shape to surround the inner tube portion200a, bringing the ends of the arc-shaped bent portions into contact with each other and welding the ends of the arc-shaped bent portions together. The two planar piece portions formed in a parallel-extending contact relationship make up a connecting portion200cfor interconnecting the inner and outer tube portions200aand200b.

In a trolley system, power supply lines are fixed in place by a line hanger500as shown inFIGS. 14 and 15. FIG. is a perspective view showing a state that two power supply lines101are fixed to a conventional line hanger500.FIG. 15is a front view of the line hanger500shown inFIG. 14. As shown inFIGS. 14 and 15, the line hanger500is used to fix the power supply lines101having a circular cross-sectional shape. The line hanger500is formed into a substantially U-like shape and includes a pair of holding members501and502for holding a pair of power supply lines101arranged in parallel and a connecting portion503for interconnecting the base end portions of the holding members501and502. In the tip end portions of the holding members501and502, there are formed recess portions501H and502H for holding the power supply lines101. The recess portions501H and502H are formed into a shape conforming to the outward shape of the power supply lines101, i.e., the cross-sectional shape of sheaths301of the power supply lines101. Thus, the recess portions501H and502H can hold the power supply lines101in a closely contacted state with no looseness.

FIG. 16shows the recess portion501H (or502H) of the holding member501(or502) shown inFIG. 14and the power supply line101held in the recess portion501H (or502H). As shown inFIG. 16, step-like stoppers501Ha (or502Ha) are formed inside the recess portion501H (or502H) of the holding member501(or502). The power supply line101is locked by the stoppers501Ha (or502Ha) and is prevented from being removed with ease.

Japanese Patent Application Publication No. 2008-117746

However, the power supply line for high-frequency current disclosed in Patent Document 1 suffers from the following problems.

(1) Since the inner tube portion and the outer tube portion are connected by the single connecting portion, the positioning of the inner tube portion becomes unstable and the alternating current resistance tends to increase. In this regard, the high-frequency resistance becomes smallest when the inner and outer tube portions are concentric with each other.

(2) A higher level of technique and an increased cost are required to form the inner tube portion, the outer tube portion and the connecting portion using a single copper plate.

(3) Copper is harder than aluminum, poor in extrusion formability (namely, throughput) and expensive.

The line hanger set forth above suffers from the following problem. Despite the fact that the step-like stoppers are formed in the recess portion of the holding member of the line hanger, the power supply line having a sheath of circular cross-sectional shape is easily removed upward from the holding member.

Since the holding member of the line hanger is not provided with a structure for restraining the power supply line from rotating in the circumferential direction, a problem is posed in that the power supply line is rotated when installed or repaired, which makes it difficult to keep the power supply line in position.

SUMMARY OF THE INVENTION

In view of the above, the present invention provides a power supply line for high-frequency current and a power supply line manufacturing method, which are capable of increasing the positioning accuracy of an inner tube portion with respect to an outer tube portion and capable of enhancing the forming throughput.

Furthermore, the present invention provides a power supply line holding structure for use in a system such as a trolley system employing a line hanger for fixing a power supply line, which is capable of preventing the power supply line from being removed upward and capable of reliably performing the positioning of the power supply line.

In accordance with a first aspect of the present invention, there is provided a power supply line for high-frequency current, which includes a conductor including an inner tube portion, an outer tube portion and a plurality of connecting portions provided between the inner tube portion and the outer tube portion.

With such configuration, the connecting portions are provided between the inner tube portion and the outer tube portion. It is therefore possible to increase the positioning accuracy of the inner tube portion and to reduce the high-frequency resistance.

The connecting portions may preferably include raised connecting portions formed on the inner tube portion, the raised connecting portions making contact with an inner surface of the outer tube portion. With such configuration, the inner tube portion and the outer tube portion are formed independently of each other. This makes it possible to enhance the forming throughput and to save the cost.

The outer tube portion may preferably include guide grooves formed on the inner surface thereof, the raised connecting portions engaging with the guide grooves. This makes it possible to increase the positioning accuracy of the inner tube portion. More specifically, depending on the machining accuracy of the inner surface of the outer tube portion, a deviation may sometimes occur in the position of the inner tube portion if the inner tube portion is rotated with respect to the outer tube portion in the circumferential direction. By fixing the position of the inner tube portion with respect to the outer tube portion, it is possible to prevent the inner tube portion from being deviated in position from the outer tube portion. It goes without saying that the positional deviation may be caused by the machining accuracy of the tip ends of the raised connecting portions as well as the machining accuracy of the inner surface of the outer tube portion.

The raised connecting portions may preferably be pressed against the inner surface of the outer tube portion. This makes it possible to increase the positioning accuracy of the inner tube portion.

In accordance with a second aspect of the present invention, there is provided a method for manufacturing a power supply line for high-frequency current, comprising: providing an inner tube portion having a plurality of raised connecting portions formed on an outer surface thereof; fitting an outer tube portion onto the inner tube portion, the outer tube portion having an inner surface surrounding the raised connecting portions; and reducing the diameter of the outer tube portion to obtain a conductor in which the raised connecting portions make contact with the inner surface of the outer tube portion.

With such configuration, the inner tube portion and the outer tube portion are connected by the raised connecting portions formed on the outer surface of the inner tube portion. It is therefore possible to increase the positioning accuracy of the inner tube portion and to reduce the high-frequency resistance. Since the inner tube portion and the outer tube portion are formed independently of each other, it is possible to enhance the forming throughput and to save the cost as compared with a case where the inner tube portion and the outer tube portion are one-piece formed from a single copper plate.

The number of the raised connecting portions may preferably be three or more. This makes it possible to increase the positioning accuracy of the inner tube portion.

Guide grooves engaging with the raised connecting portions may preferably be formed on the inner surface of the outer tube portion. This makes it possible to further increase the positioning accuracy of the inner tube portion.

The raised connecting portions may preferably be pressed against the inner surface of the outer tube portion by reducing the diameter of the outer tube portion. This makes it possible to prevent the inner tube portion from being deviated in position with respect to the outer tube portion.

In accordance with a third aspect of the present invention, there is provided a power supply line holding structure, including: a holding member including a recess portion with a stopper; and a power supply line including a sheath having a substantially circular cross-sectional shape, the power supply line being mounted to the recess portion of the holding member, the sheath having a flat shoulder portion engaging, through surface-to-surface contact, with the stopper of the recess portion.

With such configuration, when the power supply line is fixed to the recess portion of the holding member, the flat shoulder portion of the sheath of the power supply line are caught, through surface-to-surface contact, by the stopper of the recess portion. This makes it possible to prevent the power supply line from being removed upward or making rotation. It is therefore possible to reliably perform the positioning of the power supply line.

The recess portion of the holding member may preferably have an inner surface and a groove formed on the inner surface, the sheath of the power supply line having a protrusion engaging with the groove. Employing this structure makes it possible to more reliably perform the positioning of the power supply line.

In accordance with a fourth aspect of the present invention, there is provided a power supply line holding structure, including: a holding member including a recess portion; and a power supply line including a sheath having a substantially circular cross-sectional shape, the power supply line being mounted to the recess portion of the holding member, the recess portion of the holding member having an inner surface and a protrusion formed on the inner surface, the sheath having a groove engaging with the protrusion of the recess portion.

With such configuration, when the power supply line is fixed to the recess portion of the holding member, the protrusion provided in on the inner surface of the recess portion engages with the groove provided in the sheath of the power supply line. This makes it possible to reliably prevent the power supply line from being removed upward or making rotation. It is therefore possible to more reliably perform the positioning of the power supply line.

The present invention can provide a power supply line for high-frequency current and a power supply line manufacturing method, which are capable of increasing the positioning accuracy of an inner tube portion with respect to an outer tube portion and capable of enhancing the forming throughput.

Furthermore, the present invention can provide a power supply line holding structure for use in a system such as a trolley system employing a line hanger for fixing a power supply line, which is capable of preventing the power supply line from being removed upward and capable of reliably performing the positioning of the power supply line.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings forming a part of the subject specification. In the respective drawings, identical or similar components will be designated by like reference symbols with no repeated description given thereto.

FIG. 1is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a first embodiment of the present invention. Referring toFIG. 1, the power supply line for high-frequency current1of the present embodiment includes a two-layered tubular conductor2. The conductor2includes an inner tube portion2aand a concentric outer tube portion2bone-piece connected to the inner tube portion2aby four connecting portions2cover the longitudinal full length of the conductor2. Just like the conventional power supply line for high-frequency current100shown inFIGS. 12 and 13, the conductor2, when in use, is embedded in an insulating body300which is not shown inFIG. 1. The four connecting portions2cinterconnecting the inner tube portion2aand the outer tube portion2bare arranged at a specified interval (e.g., at an interval of 90 degrees) in the circumferential direction.

As set forth above, the power supply line1of the present embodiment includes the conductor2having the four connecting portions2cprovided between the inner tube portion2aand the outer tube portion2b. Therefore, as compared with the conventional power supply line100in which only one connecting portion200cexists between the inner tube portion200aand the outer tube portion200b, it is possible to increase the positioning accuracy of the inner tube portion2awith respect to the outer tube portion2band to reduce the high-frequency resistance.

The number of the connecting portions2cinterconnecting the inner tube portion2aand the outer tube portion2bis not limited to four but may be at least two.FIG. 2schematically shows a power supply line for high-frequency current10provided with two connecting portions2c.FIG. 3schematically shows a power supply line for high-frequency current20provided with three connecting portions2c. The connecting portions2care arranged at an interval of 180 degrees in the power supply line10shown inFIG. 2and at an interval of 120 degrees in the power supply line20shown inFIG. 3.

FIG. 4is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a second embodiment of the present invention. Referring toFIG. 4, the power supply line for high-frequency current30of the present embodiment includes a two-layered tubular conductor31. The conductor31includes an inner tube portion31awhich has four raised connecting portions31cand an outer tube portion31binto which the inner tube portion31ais inserted. The four raised connecting portions31cof the inner tube portion31aare arranged at a specified interval (e.g., at in interval of 90 degrees) in the circumferential direction of the inner tube portion31aover the longitudinal full length of the inner tube portion31a. The tip ends of the four raised connecting portions31chave such a height that they can make contact with the inner surface of the outer tube portion31b. By providing the four raised connecting portions31cin the inner tube portion31aand bringing the four raised connecting portions31cinto contact with the inner surface of the outer tube portion31b, it is possible to form the inner tube portion31aand the outer tube portion31bindependently of each other. This makes it possible to enhance the forming throughput and to save the cost.

As described above, the power supply line30of the present embodiment is configured such that the four raised connecting portions31care provided in the inner tube portion31ato make contact with the inner surface of the outer tube portion31b. This makes it possible to form the inner tube portion31aand the outer tube portion31bindependently of each other. As compared with a conventional example in which an inner tube portion and an outer tube portion are one-piece formed from a single copper plate, it is possible to enhance the forming throughput and to save the cost.

The number of the raised connecting portions31cis not limited to four but may be at least two as in the first embodiment described earlier.

FIG. 5is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a third embodiment of the present invention. Referring toFIG. 5, the power supply line for high-frequency current40of the present embodiment includes a two-layered tubular conductor41. The conductor41includes an inner tube portion41awhich has four raised connecting portions41cand an outer tube portion41binto which the inner tube portion41ais inserted. The power supply line40of the present invention remains the same as the power supply line30of the second embodiment in that the inner tube portion41ais provided with the four raised connecting portions41cbut differs from the power supply line30of the second embodiment in that guide grooves41dfor engaging with the raised connecting portions41care formed on the inner surface of the outer tube portion41b.

The tip ends of the raised connecting portions41cof the inner tube portion41aare formed into a substantially arc shape. Likewise, the guide grooves41dof the outer tube portion41bare formed into a substantially arc shape. By forming the tip ends of the raised connecting portions41cto have a round shape and forming the guide grooves41dinto an arc shape, it is possible to easily bring the raised connecting portions41cinto engagement with the guide grooves41d.

Since the guide grooves41dengaging with the raised connecting portions41care formed on the inner surface of the outer tube portion41bin the power supply line40of the present embodiment, it is possible to increase the positioning accuracy of the inner tube portion41a. More specifically, depending on the machining accuracy of the inner surface of the outer tube portion41b, a deviation may sometimes occur in the position of the inner tube portion41aif the inner tube portion41ais rotated with respect to the outer tube portion41bin the circumferential direction. By fixing the tip ends of the raised connecting portions41cof the inner tube portion41ato the guide grooves41dof the outer tube portion41b, it is possible to prevent the inner tube portion41afrom being deviated in position from the outer tube portion41b. It goes without saying that the positional deviation may be caused by the machining accuracy of the tip ends of the raised connecting portions41cas well as the machining accuracy of the inner surface of the outer tube portion41b.

While the guide grooves41dand the raised connecting portions41care formed into a round shape in the present embodiment, they may be formed to have other shapes, e.g., a triangular shape. The number of the raised connecting portions41cis not limited to four but may be at least two as in the first embodiment described earlier.

FIG. 6is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a fourth embodiment of the present invention. Referring toFIG. 6, the power supply line for high-frequency current50of the present embodiment includes a two-layered tubular conductor51just like the power supply line30of the second embodiment. The conductor51includes an inner tube portion51awhich has four raised connecting portions51cand an outer tube portion51binto which the inner tube portion51ais inserted. The power supply line50of the present embodiment differs from the power supply line30of the second embodiment in that the raised connecting portions51care pressed against the inner surface of the outer tube portion51b. By pressing the raised connecting portions51cagainst the inner surface of the outer tube portion51b, it is possible to fix the inner tube portion51ato the outer tube portion51bas in the power supply line30of the second embodiment. This makes it possible to prevent positional deviation of the inner tube portion51awith respect to the outer tube portion51b.

FIG. 7is a perspective view schematically illustrating a method for manufacturing the power supply line50of the present embodiment. Referring toFIG. 7, the inner tube portion51ahaving the four raised connecting portions51con the outer surface thereof is produced and, then, the outer tube portion51bfor holding the raised connecting portions51con the inner surface thereof is produced. Thereafter, the outer tube portion51bis fitted to the inner tube portion51a. Subsequently, the outer tube portion51bis moved through a ring-shaped die60having an inner diameter a little smaller than an outer diameter of the outer tube portion51b, thereby reducing the diameter of the outer tube portion51b. As a result, it is possible to obtain a conductor51in which the raised connecting portions51care kept in close contact with the inner surface of the outer tube portion51b. The conductor51is embedded in the afore-mentioned insulating body300(seeFIGS. 12 and 13) to thereby obtain a power supply line for high-frequency current50.

In the power supply line50of the present invention, the positioning accuracy of the inner tube portion51acan be increased by pressing the raised connecting portions51cof the inner tube portion51aagainst the inner surface of the outer tube portion51b.

The number of the raised connecting portions51cis not limited to four but may be at least two as in the first embodiment described earlier.

In the third embodiment described above, the raised connecting portions41cmay be pressed against the inner surface of the outer tube portion41b.FIG. 8is a perspective view schematically illustrating a method for manufacturing the power supply line40of the third embodiment. Referring toFIG. 8, the inner tube portion41ahaving the four raised connecting portions41con the outer surface thereof is produced and, then, the outer tube portion41bfor holding the raised connecting portions41con the inner surface thereof is produced. In the production of the inner tube portion41a, the tip ends of the raised connecting portions41care formed into an arc shape. In the production of the outer tube portion41b, the guide grooves41dare formed to have an arc shape. Thereafter, the outer tube portion41bis fitted onto the inner tube portion41a. Subsequently, the outer tube portion41bis moved through a ring-shaped die70having an inner diameter a little smaller than an outer diameter of the outer tube portion41b, thereby reducing the diameter of the outer tube portion41b. As a result, it is possible to obtain a conductor41in which the raised connecting portions41care kept in close contact with the guide grooves41dof the outer tube portion41b. The conductor41is embedded in the afore-mentioned insulating body300(seeFIGS. 12 and 13) to thereby obtain a power supply line for high-frequency current40.

FIG. 9is a view showing a power supply line holding structure according to a fifth embodiment of the present invention. InFIG. 9, the same components as those shown inFIG. 16are designated by like reference symbols with no description given thereto.

With the power supply line holding structure shown inFIG. 9, a power supply line11can be reliably fixed using a line hanger500having the same structure as that of the conventional line hanger500shown inFIGS. 14 and 15. For the details of the line hanger500, reference is made toFIGS. 14 and 15.

The power supply line11includes the same conductor200as that of the conventional power supply line101shown inFIG. 16. The power supply line11differs from the conventional power supply line101in that the sheath5of the power supply line11has flat shoulder portions5acapable of engaging, through surface-to-surface contact, with the stoppers501Ha (502Ha) of the recess portion501H (502H) of the holding member501(502) of the line hanger500. The provision of the flat shoulder portions5aengaging, through surface-to-surface contact, with the stopper pieces501Ha (502Ha) of the recess portion501H (502H) of the holding member501(502) restrains the power supply line11from moving upward. This makes it difficult for the power supply line11to be removed upward. Accordingly, it is possible to prevent upward removal of the power supply line11. In addition, the rotation of the power supply line11is restrained by the shoulder portions5a. This prevents the power supply line11from making rotation. As a result, it becomes possible to reliably perform the positioning of the power supply line11.

With the power supply line holding structure of the present embodiment described above, when the power supply line11is fixed to the recess portion501H (502H) of the holding member501(502), the flat shoulder portions5aof the sheath5of the power supply line11are caught, through surface-to-surface contact, by the stoppers501Ha (502Ha) of the recess portion501H (502H) of the line hanger500. This restrains the power supply line11from moving upward or making rotation. Accordingly, it is possible to prevent the power supply line11from being removed upward and to reliably perform the positioning of the power supply line11.

FIG. 10is a view showing a power supply line holding structure according to a sixth embodiment of the present invention. In the power supply line holding structure of the present embodiment, as shown inFIG. 10, a groove600H is provided on the bottom surface of the recess portion501H (502H) of the holding member501(502) of the line hanger500. A protrusion5bengaging with the groove600H of the line hanger500is provided in the sheath5A of a power supply line12similar to the power supply line11of the fifth embodiment. Since the protrusion5bprovided in the sheath5A of the power supply line12engages with the groove600H provided on the bottom surface of the recess portion501H (502H) of the holding member501(502) of the line hanger500, the rotation of the power supply line12is restrained in a more reliable manner as compared with a case where there is provided only the shoulder portions5a. Accordingly, it is possible to more reliably perform the positioning of the power supply line12.

With the power supply line holding structure of the present embodiment described above, when the power supply line12is fixed to the recess portion501H (502H) of the holding member501(502), the protrusion5bprovided in the sheath5A of the power supply line12engages with the groove600H provided on the bottom surface of the recess portion501H (502H). This restrains the rotation of the power supply line12in a more reliable manner. Accordingly, it is possible to reliably perform the positioning of the power supply line12in comparison with that in the power supply line holding structure of the fifth embodiment.

FIG. 11is a view showing a power supply line holding structure according to a seventh embodiment of the present invention. In the power supply line holding structure of the present embodiment, as shown inFIG. 11, protrusions601H (602H) are provided on the inner side surfaces of the recess portion501H (502H) of the holding member501(502) of the line hanger500. Grooves5cengaging with the protrusions601H (602H) of the line hanger500are provided in the sheath55of a power supply line13similar to the power supply line11of the fifth embodiment. Since the grooves5cprovided in the sheath5B of the power supply line13engages with the protrusions601H (602H) provided on the inner side surfaces of the recess portion501H (502H), the rotation of the power supply line13is restrained in a more reliable manner as compared with a case where there is provided only the shoulder portions5a. Accordingly, it is possible to more reliably perform the positioning of the power supply line13. The grooves5cand the protrusions601H (602H) restrain rotation of the power supply line13, thereby preventing the power supply line13from making rotation. As a result, it becomes possible to reliably perform the positioning of the power supply line13.

With the power supply line holding structure of the present embodiment described above, when the power supply line13is fixed to the recess portion501H (502H) of the holding member501(502), the protrusions601H (602H) provided on the inner side surfaces of the recess portion501H (502H) engage with the grooves5cprovided in the sheath5B of the power supply line13. This restrains the power supply line13from moving upward or making rotation. Accordingly, it is possible to prevent the power supply line13from being removed upward and to reliably perform the positioning of the power supply line13.

The fifth through seventh embodiments described above may be provided either independently or in combination. For example, the fifth embodiment and the seventh embodiment may be combined with each other. Alternatively, the sixth embodiment and the seventh embodiment may be combined with each other.

While the invention has been shown and described with respect to the embodiments, the present invention is not limited thereto. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.