Bus bar distribution system

Abstract: Conductor (1, 1', 2) and non-conductor (3,3) components, have uniform cross-section. The nominal cross-section, including two single interspaced bars (1, 1') provides a channel (101) with two parallel opposed walls (10, 10'), set at such a distance (2r - 2h) to receive screws (5), particularly self-tapping screws, cutting their own thread (5', 5') into the same walls (10, 10'), whereby terminals (9) can be connected and an elastic strain (T e ) is provided, to prevent unscrewing. Each bar unit comprises five components (1, 1', 2, 3, 3), three of which (1, 1', 2) are conductor and two (3, 3) non-conductor., wherein the centrifugal components (2, 3), act as encompassing members. The ensemble (3, 01, 3,3, 02, 3,3, 03, 3,3, 04, 3) is bound by a frame (7) including longitudinal rods (70, 70') with grooves (00), for fastening grounded conductors terminals (9).

Description: The present invention relates to a bus bar distributing system, wherein each bus bar comprises several uniform cross-section components, set to receive, anywhere, therealong, a number of terminals and the like. At the present state of the art, bus bars for distributing and/or collecting electrical energy and providing for the connection of terminals and the like, are individual and are rectangular in cross-section. Generally, the longer side of their rectangular cross-section is from three to six times longer as the shorter side thereof. Such rectangular cross-section bars are drilled and tapped with mating threads, through their main surfaces, to receive the machine screws for terminal and connection fastening. When the number and assignment of such terminals and/or connections is known, the tapped holes are provided correctly, in number and position. Instead, when use and density of connections or terminals are unknown, the holes are provided according to an estimated modular rule, and more frequently, in accordance with a statistical probability. Of course, in the latter case, holes are provided in excess, with the drawback that boring and tapping involve additional costs, while the cross-section, of the bored bar lengths is reduced. Such reduction, of course, is inversely proportional to bar thickness. Moreover, the thinner the bar is, the least safe is the screw and terminal holding, due to the scarce number of threads which can be provided, and this drawback is unavoidable. Since bar conductivity of a bar does not depend only on its cross-section but also on its heat dissipation power, rectangular cross-sections are preferred. However another drawback of rectangular cross-sectioned bars, mainly of those having a high base/height side ratio, is to be cumbersome, not only for having a wider width, but even clue to the air gap to be provided between bars for reasons of fault resistance. Moreover, contact between a terminal and a bar occurs substantially in three spots, among which the pressure provided by the screw is shared, and the screw, substantially never is a self-tapping screw but a conventional screw or bolt, as such not adapted to prevent unscrewing. Thus, it is necessary to provide an additional nut, both in case of screws or bolts; in no case, the friction between the screw or bolt thread and its tapped holes and/or nut are safe, as in the case of self-tapping machine screws, making their own thread in the bar into which are driven. The invention as claimed is intended to remedy these drawbacks. The inventor, with ingenious perception, has conceived a bus bar distribution system as defined in claim 1. Preferred embodiments are defined in the dependent claims. One way of carrying out the invention is described in detail below with reference to drawings which illustrate only one specific embodiment thereof, in which: Figure 1 is a perspective, schematic view, of a set of four bar units, wherein, at one end thereof, breakings have been made fbr showing, at different levels, the details otherwise hidden. Figure 2 is a perspective, detailed, view, in an enlarged scale, of a terminal fastened to a pair of single bars, in accordance with the present invention. Figure 3 is a scheme of principle, with two positions, indicating the strain characteristics of the device in accordance with the present invention, in two cases: the former in screwing attitude (left side half) and the latter showing the finally fastened screw (right side half). Figure 4 is an exploded, perspective, view of a half frame (right side) embodying the principle of the present invention and comprising a particularly advantageous and generic container, for a bar unit system of the subject kind. Figure 5 is an assembled, perspective view of a (left side) half frame similar and complementary to that shown in Figure 4. Referring now to the drawings, in particular to Figure 3, in accordance with the present invention, a system unit is made of conductor (1, 1', 2) and non-conductor (3,3) material components all of uniform cross-section. The conductor material, providing the nominal cross section, provides at least a channel (101) having the opposed parallel walls (10, 10'), which are set at such a distance (2r - 2h) to receive therebetween, a screw, particularly self-tapping screw (5), having mutually such features to engrave and cut the thread (5', 5') into such opposed walls (10, 10') of the channel (101), providing at the same time a permanent elastic strain (Te) on the structure, operating at least locally, on the screw (5), substantially in accordance with the following formula: T e = M e · D ; being D = n · S · R + F b · tan α wherein: Fb = Screw (maximum) holding power; Te = Elastic strain; Me = Elastic module (of the outer holding material); D = Deformation; S = Deformed cross-section; n = Number of threads concerned; R = Conductor material strength; α = Thread inclination. In practice, e.g., to provide bus bar distributing systems, as shown in the drawings, four units 01, 02, 03, 04 are provided. Each bus bar unit comprises more component rods 1, 1', 2, 3, 3, all of them having uniform cross-section, set to receive, anywhere, therealong, a number of adjacent terminals 9 and the like, The more uniform cross-section rod components 1, 1', 2, 3, 3, comprising each bar unit 01, 02, 03, 04, satisfy at least the condition of providing two parallel walls 10, 10', at a distance d, corresponding to the width 2', such as to engage self-tapping screws 5, which, when driven in the interwall groove 101, engrave the two opposed walls 10, 10', fastening thereto . The uniform cross-section components, substantially comprising each bar unit 01, 02, 03, 04, in accordance with the shown embodiment, are five 1, 1', 2, 3, 3. Three of them: 1, 1', 2, are conductors and two, 3 non conductors. The two conductor components 1, 1' provide the parallel walls 10, 10', which can be engaged by the screws 5, fastening the terminals and the like and the third conductor component 2, and insulator components 3, provide encompassing functions: the conductor member 2 is in inner central position, in touch, even through the rib 2', with the single bars 1, 1' or parallel walls 10, 10' which can be engaged by the screws 5, fastening the terminals 9 and the like; the insulator components 3 are in outer position which is complementary to that of enveloping conductor component 2; the former 2 having "U" or "C" or channel like cross-section, the latter 3 having "L" like cross-section. The arrangement of the single bars 1, 1', parallel, paired with the longer side 10, 10' in vertical disposition, minimizes the overall dimensions thereof, while the conducting area is increased. The insulation space between bar units 01, 02, 03, 04, is provided by components 3 of higher height; they are coupled in stepped conditions and project from the upper side of single bars 1, 1'; they are fit paired to adjacent bar units 01, 02, 03, 04, to provide here too, mainly in vertical direction, the necessary dielectric distance with minimum overall dimensions. Of course the cross-section of the enveloping conductor component 2 is additional to the cross-section of the single bars 1, 1' to provide, coeteris paribus a compacted unit. Regarding the holding power or mutual coupling between the fastening screws 5 of terminals 9 and the like and the single bars 1, 1' or parallel walls 10, 10' engageable thereby, the following equation must be fulfilled: F b = L · S · R m wherein: Fb = Screw (maximum) holding power; L = Height concerned; Rm= Material (specific) strength; S= Cross-section concerned i.e., area of two segments; The cross-section concerned i.e., the area of two segments, is mathematically given by: S= 2 . 0,5 [rl - c (r-h)] wherein: r= radius of the circle segment; l= arc length of circle segment; c= chord subtending the circle segment arc; h= arc height of the circle segment; In practice, in accordance with the preferred embodiment of the present invention, shown in the drawings, the following example may be given: EXAMPLE I For provision of each bus bar unit 01, 02, 03, 04, of the cross-section of 200 mm 2 , were used two copper rectangular single bars 1, 1', of mm 5 x mm 20, contained by an aluminium channel rod 2, of the dimensions of mm 17,5 x mm 20 x mm 2,5, whose inner bottom 2", 2"' is provided with a central rib 2', which is mm 5 width and mm 3 height. Thus the single bars 1, 1', standing with the short side of the rectangular cross-section against the inner bottom of the channel rod 2, aie fit, respectively into the grooves 2", 2"', aside the rib 2', in order to provide their adjacent main surfaces 10, 10', parallel at a distance corresponding to that of rib 2' i.e., of mm 5. This distance is correct to receive any of so said "Parker" screws 5 or equivalent, having an outer diameter of mm 6,3, and a length of 20 mm, i.e. shorter than the corresponding dimension of single bars 1, 1'. Such screws 5, are duly provided with lock washers 6 and applied to terminals 9 and the like, in order that the same screws 5 cut their own thread into the single bars 1, 1' of copper, along an height L concerned of mm 18. The so fastened terminal 9, provides a contact in at least four spots 09, with a conductivity increase of about 80%. An attempt was made to force a screw 5, in order to strip its matching copper thread 5' it cut thereinto. This took place when the force applied was at least three times as much as the usual fastening force. Thereupon the same screw 5 was driven into again at a distance of mm 5 from the stripped thread 5' and the same results were obtained with an equivalent fastening. EXAMPLE II For provision of each bus bar unit 01, 02, 03, 04, having a cross-section of 500 mm 2 were used two copper rectangular single bars 1, 1', of mm 5 x 50, contained by an aluminium channel rod 2, of the dimensions of mm 17,5 x mm 20 x mm 2,5,whose inner bottom is provided with a central rib 2', which is mm 5 width and mm 3 height. Thus the single bars 1, 1', standing with the short side of the rectangular cross-section respectively on the bottom 2", 2"' of the grooves siding the rib 2' of channel rod 2, in order to provide their adjacent main surfaces 10, 10' parallel at a distance corresponding to that of rib 2' i.e., of mm 5. This distance is correct to receive any of so said "Parker" screws 5 or equivalent, having a outer diameter of mm 6,3, and a length of mm 40, i.e. shorter than the corresponding dimension of single bars 1, 1'. Such screws 5, are duly provided with lock washers 6 and applied to terminals 9 and the like, in order that the same screws 5 cut their own thread into the single bars 1, 1' of copper along an height L concerned of mm 35. The so fastened terminal 9, provides a contact in at least four spots 09, with a conductivity increase of' about 80%. An attempt was made to force the screw 5, in order to strip its matching copper thread 5' it cut thereinto. This took place when the force applied was at least four times as much as the usual fastening force. Thereupon the same screw 5 was driven into again at a distance of mm 7 from the stripped thread 5' and the same results were obtained with an equivalent fastening. It will be appreciated that the ensemble 3, 01, 3,3, 02, 3,3, 03, 3,3, 04, 3 is bound with an annular frame 7 comprised by a pair of uniform cross-section rod lengths 70,70', having, in general, a "Y" like cross-section, connected crosswise, at the bottom by screws, i.e., self-tapping screws 71, 71', engaging. the ends of a distancing rod 72, it too comprised by uniform cross-section rods. Instead, in the upper side, the structural components rod lengths 70, 70' are connected through staples 73, thickness 74, self-tapping screws 75 and bridges 76, all of them, except the screws 75, being comprised by uniform cross-section rods. Even for the rod components 70, 70', 72, i.e. for all connections 9, all over the whole system, they may be made anywhere, limited only by the principle of impenetrability of bodies. In fact between the fastening screws 5 and the grooves 00 there is the same arrangement than between the fastening screws 5 and channel 101 provided with walls 10, 10' for terminal fastening. As in that case grooves 00 are adapted for grounded conductors terminals 9 (figures 4 and 5) which can be fastened with screws 5. On the contrary the same grooves 00 may be used for structural binding as in the case of screws 71, 71', 75. For fastening together the conductor components 1, 1', 2, of each bus bar unit, they are joined by pins 8. As regards as the "L" like cross-section rods 3, of dielectric material they are extended in vertical direction well over the top of the single bars 1, 1' and possibly coupled as to provide a step.

Claims: Bus bar distribution system, of the kind substantially comprised of rods (1, 1', 2, 70, 70', 72, 73, 74, 76) of uniform cross-section, the rods preferentially being extruded, and being connectible mechanically and electrically together, to terminals (9) and the like and to structural means (70, 70', 72, 73, 74, 76), by screws (5, 71, 71'), characterized in that it comprises the following features: a) at least one unit comprising: a pair of spaced parallel rods (1, 1', 2) of conducting material electrically and mechanically connected together, each rod having a uniform cross-section along its length, and said unit being connectable to structural means (70) and terminals (9) whereby said rods are arranged to provide a channel therebetween; b) at least one screw for attachment of a said terminal to said unit or member anywhere along its length, said screw (5) being of a size to cut a thread into the opposed walls of said channel. System, as claimed in claim 1, characterized in that, it further comprises at least a member of conducting material having a uniform cross-section along its length comprising at least a pair of spaced parallel walls (1, 1', 2) said member being connectable to structural means (70) and terminals (9), whereby said walls are arranged to provide a channel therebetween. System, as claimed in claim 1 or claim 2, characterized in that, each individual bar unit comprises a system ensemble also including non-conducting, uniform cross-section rod components (3), wherein the conductor material bars (1, 1') are of nominal cross-section, and the channel (101) is formed by the opposed parallel walls (10, 10') of the conducting rods, which are set at such a distance (2r-2h) to receive therebetween the screw (5), which is preferably a self-tapping screw, having features adapted to cut the thread (5', 5') into the opposed walls (10, 10') of the channel (101), providing, at the same time, a permanent elastic strain (T e ), on the structure operating at least locally, on the screw (5), substantially in accordance with the following formula: T e = M e · D ; being:: D = n· S· R + F b · tan α wherein: Fb = Screw (maximum) holding power; Te = Elastic strain; Me = Elastic module (of the outer holding material); D = Deformation; S = Deformed cross-section; n = Number of threads concerned; R = Conductor material strength; α = Thread inclination. System as claimed in claim 1 or claim 2, characterized in that each bar unit (01, 02, 03, 04) comprises several components (1, 1', 2, 3) having uniform cross-section, which fulfil at least the condition of providing two parallel walls (10, 10'), at a distance (d), such as to engage self-tapping screws (5) which, when driven in the interwall groove (101), cut (in 5') their own thread sections into the opposed walls (10, 10') thereby fastening thereto. System, as claimed in claim 1, characterized in that there are five components (1, 1', 2, 3, 3) having uniform cross-section, which substantially comprise each bar unit, three of which (1, 1', 2), conductors and two (3, 3) non-conductors, wherein two (1, 1') of the three (1, 1', 2), conductors provide the parallel walls (10, 10') engageable by the screws (5), to fasten the terminals (9) and the third conductor component (2) and the insulator components (3), act as encompassing members: the conductor member (2) being in an inner central position, contacting the single bars (1, 1') and the non-conducting components (3), having an "L" like cross-section, and being in an outer symmetrical position, complementary to each other and to the conducting encompassing member (2); the latter being formed as a channel, which in an inner central position, on its inner bottom side, there is provided with a distancing rib (2') for spacing the single bars (1, 1') and having, for each of same, a groove (2",2"'). System, as claimed in claim 4, characterized in that the spacing of the single parallel paired bars (1, 1') with their longer side (10, 10') in vertical disposition, minimizes the overall dimensions thereof, while the surface area is increased, wherein insulation is provided by the non-conducting rod components (3) of higher height than the conducting bars, the non conducting bars being arranged in longitudinal stepped fashion to extend over the single bars (1, 1'), and that they are placed in at least at one side (3), or on both (3) sides in case of adjacent bar units (3, 01, 3,3, 02, 3,3, 03, 3,3, 04, 3), to provide here too, mainly in vertical direction, the necessary dielectric distance, with a minimum of overall dimensions. System, as claimed in preceding claims, characterized in that regarding the holding power or mutual coupling between the fastening screws (5) of terminals (9) and the like and the single bars (1, 1') or parallel walls (10, 10') engageable thereby, the following equation must be fulfilled: F b = L · S· R m wherein: Fb = Screw (maximum) holding power; L = Height concerned; Rm= Material (specific) strength; S= Cross-section concerned i.e., area of two segments; wherein la Cross- section concerned i.e., area of two segments is mathematically given by: S= 2 0,5 [rl - c (r-h)] wherein: r= radius of the circle segment; l= arc length of circle segment; c= chord subtending the circle segment arc; h= arc height of the circle segment. System as claimed in claim 1 or claim 2, characterized in that the ensemble of bar units (3, 01, 3,3, 02, 3,3, 03, 3,3, 04, 3) is bound with an annular frame (7) comprised by a pair of uniform cross-section rod lengths (70,70') having in general a "Y" like cross-section, and in particular, including an "L" shaped section, an "E" shaped section and an "h" shaped section, with three grooves (00) to receive screws (5), such a pair of rod lengths (70,70') being in turn bound with rod means having uniform cross-section too and with self-tapping screws (71, 75). System, as claimed in claim 8, characterized in that the rod lengths (70, 70') comprising the annular frame (7) with the grooves (00) are made with a good conducting material, such as aluminium, in order that with screws (5), particularly self-tapping screws, terminals (9) of grounded conductors, may be electrically connected, rod lengths (70, 70') being connected crosswise at the bottom by screws, i.e., self-tapping screws (71, 71'), engaging the ends of a distancing rod (72), it too comprised by uniform cross-section rods, whereas on the upper side, the structural components rod lengths (70, 70') are connected with staples (73), a wall (74), self-tapping screws (75) and bridges (76), all of them, except the screws (75), being comprised by uniform cross-section rods. Bus bar distribution system means, as claimed in preceding claims, characterized in that for fastening together conductor components (1, 1', 2) they are joined by pins (8). Bus bar distribution system means, as claimed in claim 10, characterized in that the "L" like cross-section rods (3), of dielectric material are extended in the vertical direction well over the top of the single bars (1, 1') and possibly providing a step.

Inventors: MASPER ROBERTO, MASPER, ROBERTO
Applicants: MASPER ROBERTO SRL, MASPER ROBERTO S.R.L.
Application year: 1992
Main classification: H01R25
IPC codes: H01R25