Abstract:
The inventive power supply system ( 1 ) comprises a ground placed power supply device ( 2 ) provided with at least one linear supply wire ( 7 ) connected to a voltage supply, a rail ( 6 ) comprising at least one zero reset conductor strip ( 8 ) and at least one protective profile in a flat L-shaped position profile masking the conductor wire. The system also comprises an on-board current sensing device ( 3 ) comprising at least one movable sensing subassembly ( 38 ) comprising a power sliding contactor ( 41 ) and a zero volts sliding contactor ( 42 ) which are electrically connected to the vehicle load circuits and used for slidingly contacting the supply wire and the zero reset conductor strip. The invention is useful for manufacturers of public transport vehicles and the lines therefor.

Description:
This application is a national stage completion of PCT/FR2005/002338 filed Sep. 21, 2005 which claims priority from French patent application serial number 04/10356 filed Sep. 30, 2004. 
   FIELD OF THE INVENTION 
   The present invention relates to a ground power supply for electric vehicles, preferably vehicles guided by a guide assembly traveling on a guide rail. 
   More specifically, it concerns a continuous low voltage electrical ground supply. 
   The electric vehicles in question are land vehicles such as road vehicles, but also railway vehicles. The invention is particularly well suited for supplying electricity to an electrically propelled self-guided public transport vehicle, either a railway vehicle or a wheeled vehicle. However, the invention is not limited to this preferred embodiment. 
   This type of electrically propelled or driven vehicle is conventionally supplied with electrical energy through overhead or catenary cables located above the travel tracks. 
   The present tendency, however, for esthetic or other reasons, consists of eliminating these overhead electrified wires and replacing them with ground level or subterranean supply systems. 
   Several ground supply systems for these vehicles have been proposed in the prior art. However, these systems pose a certain number of disadvantages, principally from the safety standpoint. 
   In actuality, these prior art systems provide high voltage electrical supply, specifically a continuous supply, which can prove to be extremely dangerous for humans if they contact the conductive elements. Furthermore, with the use of high voltage, there is an additional risk related to vagabond electrical current. 
   SUMMARY OF THE INVENTION 
   The goal of the invention is to furnish a completely safe system for the ground supply of power to electrical vehicles. 
   Another goal of the invention is to furnish a ground power supply that is simple and quick to position and assemble. 
   Yet another objective of the invention is to furnish a ground power supply that is simple to maintain. 
   To resolve this technical problem, the invention provides a ground power supply of electricity to a land vehicle that moves along a predetermined path, said ground power supply being a sliding contact type supply with at least one conductive element. This system comprises a device located on the ground for furnishing electrical current and a current sensing device located on the vehicle and moving along with the vehicle. 
   The electrical supply device of the invention is placed in a cable duct that is open at the top. It comprises at least one linear supply wire connected to an electrical voltage source, said at least one wire being placed in the cable duct laterally relative to a rail that holds at least one zero reset conductor strip. It further comprises at least one protective profile that has a generally flat L-shape surrounding and masking the linear conductor wire placed beneath it. 
   The on board current sensor comprises at least one movable sensor subassembly supported by a support device which circulates, within the cable duct, laterally relative to the rail. This sensor subassembly comprises a power contactor designed to form a sliding electrical contact with the supply wire and a zero volt contactor designed to form a sliding electrical contact with the zero volt reset strip, said power contactors being electrically connected to the vehicle utility circuits. 
   Advantageously the contact between the power contactor and the supply wire takes place below the protective profile and it is surrounded by the return of this protective profile. 
   Said at least one linear supply wire may preferentially be connected to a continuous electrical voltage supply. 
   The ground supply system of the invention thus ensures the complete safety of pedestrians or others using the street. 
   In addition, the placement and maintenance of this supply system are especially simple. 
   Advantageously, the system according to the invention may comprise a supplemental safety device in case a problem arises that would jeopardize safety, consisting of a means for disconnecting the at least one subassembly sensor that is displaced within the cable duct, which allows the support assembly, which is no longer live, to be extracted while on line. 
   According to a preferred embodiment of the invention, the electrical current supply device may comprise two linear supply wires each connected to an electrical voltage source, said two wires being placed in the cable duct on either side of a central rail that supports two zero reset conductor strips. It also comprises two flat L-shaped protective profiles, each of said protective profiles surrounding and masking one of the conductive wires placed beneath it. 
   According to this variation the on-board current sensor device comprises two movable sensor subassemblies held by a support device, which circulate within the cable duct on either side of the central rail, each of said sensor subassemblies comprising a power contactor designed to form a sliding electrical contact with the corresponding supply line and a zero volt contactor designed to form a sliding electrical contact with the corresponding zero reset conductor strip, said power contactors and zero volt contactors being electrically connected to the utility circuits of the vehicle. 
   Advantageously, the contact between each power contactor and the corresponding supply wire may then occur below the corresponding protective profile and may be surrounded by the return of this protective profile. 
   Preferably the two linear supply wires may each be connected to a continuous low voltage source, one positive and the other negative, for example, and of equal value. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other characteristics and advantages of the invention will become apparent from reading the following detailed description in conjunction with the attached drawings, in which: 
       FIG. 1  is a transverse cross-section of one example of the entire electrical supply system, according to the invention, comprising a ground current supply device and an on-board sensor; 
       FIG. 2  is a transverse cross-section of the current supply device installed in the ground corresponding to the exemplary embodiment of the invention illustrated in  FIG. 1 ; 
       FIGS. 3 through 8  are transverse cross-sections illustrating embodiments of the principal elements constituting an electrical supply device installed in the ground according to the invention, said elements being shown either alone or in association with a few other elements: 
       FIG. 3  represents a central rail; 
       FIG. 4  represents a central rail mounted in a cable duct and cooperating with the guide assembly of the sensor arm or of the vehicle; 
       FIG. 5  represents a cross piece to which a central rail is attached, as well as one of the side profiles, including its protective profile; 
       FIG. 6  represents a support bracket for a conductor wire; 
       FIG. 7  represents a portion of a side profile to which a bracket is attached supporting a conductor wire and a protective profile; 
       FIG. 8  is similar to  FIG. 7  but illustrates another variation of a linear supply wire; 
       FIG. 9  is a perspective view of one example of the on-board current sensor according to the invention completed by a guide device; 
       FIG. 10  is a perspective of a support unit according to the variation in  FIG. 9 , with one of its connecting elements being separated from the interface element; 
       FIGS. 11 and 12  are perspective views of two sliding sensors designed to be attached to the support unit of  FIG. 10  and located on either side of the central rail. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The electrical supply system, according to the present invention, will now be described in detailed fashion with reference to  FIGS. 1 through 12 . Equivalent elements shown in different drawings will bear the same reference numerals. 
   The different drawings and the associated detailed description that follows concern a particular embodiment of the invention with two supply wires, two zero volt reset conductor strips and two sensor subassemblies. However, it should be noted that this sets forth only one preferred example of the invention and it is in no way limiting. 
   As previously mentioned, although not shown, the supply system of the invention may comprise only one supply wire, only one zero volt reset conductor strip and only one sensor subassembly. 
   In the same way the voltage supply to the one or more supply wires may be any type and value. 
   It is possible, but not obligatory, to have continuous electrical voltage, high drive voltage, low safety voltage or the like. 
   A high drive voltage generally used is of the order of 750 volts. 
   Low safety voltage means a voltage lower than or equal to 60 volts for each polarity. These voltages are safety voltages, that is, non-lethal and not physically dangerous to humans. 
   The electrical supply system  1  of the invention is formed of two complementary devices that cooperate to form a ground supply of electricity to utility circuits on board an electric vehicle moving along a predetermined course. 
   It is formed of an electric current supply device  2  located on the ground and a current sensor device  3  on the vehicle and moving with the vehicle, which will be described in succession for the preferred variation that is shown. 
   The current supply device  2  is shown by itself in  FIG. 2 . 
   This device is contained within a cable duct  4  preferably made of concrete, generally rectangular in section and open at the upper surface. 
   This cable duct  4  is designed to be placed inside a trench and immobilized inside it using a suitable fill. The height of the trench is preferably selected so that the top of the cable duct is essentially level with the surface of the ground. Concrete cable duct  4  may extend beyond the surface of the ground, however. In certain cases it may not even be buried, but simply placed and immobilized on a preexisting finished ground, for example, a road. 
   To evacuate water that may infiltrate cable duct  4 , the inside area is drained by a central collecting line  5  and two gutters, not shown, running along and bordering the edges of the cable duct. Pipes or conduits then evacuate the water that has collected to a manhole and then to a gutter. 
   The ground electrical supply device  2 , in the variation shown, is composed principally of a rail  6 , preferably a central rail, and two linear supply wires  7  each connected to a voltage source that is preferably continuous in the form of two symmetrical supply subassemblies, one positive and one negative. 
   The electrical energy comes from a network, after being transformed and rectified in distribution stations and substations, to reach a fixed voltage supply, in the preferred example that is described as +60 volts and −60 volts. 
   The zero electrical reset takes place along rail  6 , preferably a central rail, which has two zero volt reset conductor strips  8 , for this purpose, that are preferably symmetrical. 
   Rail  6  may function uniquely as a support for the zero volt reset strip or strips  8 . Preferably, however, it may also be a guide rail, although the invention remains valid even if it does not function as a guide rail. 
   Advantageously rail  6  may be made of electrically insulating and mechanically resistant material, preferably through extrusion. Several current methods can produce pieces with maximum resistance in the extrusion direction using reinforcing fibers, if necessary. 
   It is also possible to use a metal rail  6  because the rail has nil electrical potential and thus poses no danger to people. 
   In the preferred embodiment shown, rail  6  has a body  9  with a generally triangular section. 
   To economize material while still ensuring satisfactory resistance against lateral stress, body  9  of rail  6  is shaped like a hollow case and supports two generally trapezoidal superimposed cases  10 , separated by a wall  11  and surmounted by cylindrical cavity  12 . 
   According to an essential characteristic of the invention, rail  6  supports on at least one of its lateral walls  13 , but preferably on each of them, a zero volt reset conductor strip  8  preferably made of steel. Strips  8  are preferably symmetrical and generally vertical, as shown in the different drawings. 
   Rail body  9  extends upward into a full rail head  14 , also called a mushroom. In the example shown, it has a generally trapezoidal section with two angled lower sides  15  diverging upward, two angled contact surfaces  16  joined at the upper portion by a table  17  which may be slightly concave. 
   It may also serve as a guide rail for a vehicle guide assembly or sensor arm which, as shown in  FIGS. 4 and 9 , may comprise two guide wheels  18  angled in a V shaped moving along the two corresponding angled surfaces  16  of the head  14  of the rail  6 . 
   Toward the bottom, body  9  of rail  6  preferably terminates in a broad base  19  allowing a longitudinal contact edge  20  to extend on either side in order to anchor it to the base of cable duct  4 . 
   Rail  6  is immobilized within the base of cable duct  4  by the cross pieces  21  disposed at regular intervals, for example, every 0.80 m and using of gripping elements  22 , called clamps, bolted to the cross pieces. 
   At the level of each lateral extremity  23  of these cross pieces  21  the lower extremity  24  of a side profile  25  is immobilized using a clips. 
   The two side profiles  25  laterally define the electrical current supply device. Their exterior surface is set in the concrete. These side profiles  25  may be made of a very low charged, pultruded plastic material, for example. 
   As previously mentioned, current supply device  2  of the invention comprises at least one, but preferably two, supply wires  7  located within cable duct  4  on either side of rail  6  and at a distance therefrom. 
   These wires  7  preferably are symmetrical and generally trapezoidal in section and may be made from any suitable conductive material, such as stainless steel, aluminum or copper, for example. 
   In the situation where they are connected to a very low voltage (+60 volts or −60 volts), supply wires  7  are subjected to a high amp current. Therefore they must have a relatively large surface cross section. For reasons of weight and cost, the use of aluminum would be favored for manufacturing these lines. 
   To ensure good contact conditions between the contactors on the current sensor device  3  and supply wires  7 , the corresponding surface of the latter is preferably covered with a thin contact plate of stainless steel  26 , for example, about 1 millimeter thick. In the preferred example shown, this contact plate  26  is attached to the flat lower surface  27  of each of the supply wires  7 . 
   As shown in  FIG. 8 , the supply wire  7  is not necessarily a line made of a single piece. In a situation where a smaller surface section is sufficient, the supply wire  7  may be formed of a conductive linear web  55  housed in an insulating support  56  which may be trapezoidal in cross section, for example. 
   Insulating support  56  comprises, in the lower portion, a receptor groove  57  to which conductive linear web  55  is securely attached and maintained in place. The lower flat surface  58  of conductive linear web  55  remains free and is preferably slightly retracted inside insulating support  56 . 
   The supply wires  7  are supported by a series of brackets  28  from which they are suspended. Each of these brackets  28  preferably comprises an upper wall  29  extending downward, near its lateral edges, into two lateral walls  30  assuming the shape of the upper portion of the supply wire  7  or of the corresponding insulating support  56 . 
   At least one, and preferably each one of these brackets  28 , may be formed of two right-angled pieces  31  that are placed on either side of wire  7 , then reconnected at the level of their upper wall  29  and tightly connected so as to grip and maintain wire  7  or its insulating support  56 . 
   Bracket  28  also preferably comprises an upper heel  32  projecting upward, the function of which will be described below. 
   Brackets  28  are positioned at intervals. The are spaced at about 800 m apart, for example, but they may located closer together and more regularly, especially on curves. 
   As can be seen in  FIGS. 7 and 8 , brackets  28  rest on a contact rib  33  on side profile  25  and may be affixed to it with screws  34  and nuts set into the concrete. 
   A protective profile  35  is attached to at least one and preferably to each side profile  25 . This attachment may be made at the level of the upper extremity of each side profile  25  in which the extremity of the protective profile  35  engages, which is preferably also attached by screws  34  and nuts set into the concrete. 
   This protective profile  35  preferably has a generally flattened L-shape and surrounds supply wire  7  placed below it. 
   Its presence prevents any possible contact between users and live wire  7 , ensuring complete safety. In addition, it prevents any undesirable penetration by objects, tools, debris or the like, either accidental or malicious, into the current supply system of the invention. It also protects the unit from weather. 
   The architecture of the unit described above is designed so that each supply wire  7  is completely masked by L-shaped protective profile  35 , which makes it inaccessible. This feature, in combination with the use of low voltage, makes the electrical supply system of the invention a completely safe system. 
   Protective profile  35  preferably has an upper surface  36  that slopes slightly toward the exterior to allow rainwater to flow toward the corresponding bank forming the gutter. An intermediate seal, not shown, attached to either side in a longitudinal end groove  37  of side profile  25  forms a watertight separation. 
   Advantageously, a space exists between the rail  6  and the protective profile  35  to allow water and foreign objects, for example, debris or small objects, to be evacuated toward the base of cable duct  4 . 
   To prevent jamming, if there is no cross piece  21 , the existing space between the base  19  of the rail  6  and the lower extremity  24  of side profile  25  is larger in size than the space between the rail  6  and the protective profile  35 . 
   The protective profiles  35  must be resistant enough to support the weight of another electric vehicle at intersections or to allow ordinary vehicles, pedestrians, cyclists or motorcyclists to pass over them at intersections and passages at that level formed by conventional traffic routes. 
   Since these profiles are slightly flexible, the projecting upper heel  32  on certain brackets or each wire-supporting bracket  28  forms a contact stop for the profile, as can be seen in  FIG. 7 , for the purpose of stress recovery if there is significant deformation. 
   The structure described above is continuous. As far as brackets  28  are concerned, they may be individual, that is, in the form of one piece that is repeated at intervals. Side profile  25  itself is continuous, but is attached to inserts submerged in the concrete and spaced at regular intervals. 
   A more detailed description of the current sensor located on the vehicle follows, which is illustrated by  FIGS. 9 through 11 . 
   Collecting the electrical energy necessary to operate the utility circuits of the vehicle is accomplished using at least one, and preferably two, movable subassembly sensors  38 , which may be symmetrical and which circulate inside cable duct  4  on either side of rail  6 . 
   The principal portion of each sensor subassembly  38  is a sensor shoe  39  shown in perspective in  FIGS. 11 and 12 . The two sensor shoes  39  are preferably identical, the position of one shoe simply being reversed relative to the other one. 
   In the preferred embodiment shown, each shoe  39  has an elongated body  40  and comprises in the central position an essentially horizontal power contactor  41  designed for sliding contact with subsurface  27  or  58 , preferentially covered with contact plate  26 , of the corresponding supply wire  7 . 
   Obviously this power contactor  41  can be elastically recalled from contact with supply wire  7  so as to ensure satisfactory electrical contact in any circumstance. 
   Advantageously, during operation the contact between power contactor  41  and supply wire  7  takes place below flattened L-shaped protective profile  35  and is surrounded by the return of this protective profile. 
   Each sensor shoe  39  also comprises, on the side that will be facing the rail  6 , a zero volt contactor  42  disposed to be and to remain in sliding electrical contact on the corresponding zero volt reset conductor strip  8  supported by the rail  6 . These contactors  42  may also be capable of elastic recall from contact with corresponding strip  8 . 
   Power contractors  41  and zero volt contactors  42  are made of electrically conductive material. The body  40  of sensor shoes  39 , made of electrically insulating material, ensures electrical insulation between the two contactors. 
   Advantageously, body  40  of sensor shoe  39  may also integrate shock absorbers  43 , which may be formed of a case surrounding each contactor and its spring. 
   Each one of the power contactors  41  and zero volt reset contactors  42  is electrically connected to a conductive supply strip so that it can be electrically connected to the vehicle 
   A protective cover  44  integrating a quick connection device for the electrical contactors may advantageously maintain each contactor in position. Preferably, and in order to facilitate maintenance, the contactors and their electrical connections may be removed, specifically for replacement, by unscrewing a single screw  45  that is connected with cover  44 . 
   The two sensor shoes  39  are supported and mechanically connected by a support unit  46  preferably attached to the vehicle guide arm to provide dynamic stability. 
   Support unit  46 , shown in  FIG. 9 , comprises two support arms  47  generally shaped like an inverted U, whose free extremities  48 , located near the bottom and preferably curved outwardly, form attaching plates  49  for attaching sensor shoes  39 . 
   The two U-shaped support arms  47  form the front and rear portion of the support unit  46 . They are connected by two lateral reinforcing bars  50 , preferably generally horizontal, joining on each side the corresponding lateral branches of the two U-shaped support arms  47 . 
   Support unit  46  fulfills two functions. 
   On the one hand, it supports sensor subassemblies  38  inside the cable duct and on the other hand, it ensures the electrical connection between these sensor subassemblies  38  and the utility circuits in the vehicles. 
   The latter function is preferably achieved using copper bars submerged in an armature made of composite material forming support arms  47  and ensuring that the bars are electrically insulated. 
   Each of the sensor shoes  39  is attached, at the front and the back, to support unit  46  using two attaching plates  49  each belonging to a different support arm  47 . 
   One of the attaching plates  49  is electrically connected to electrical contactor  41  allows current to be transmitted to the vehicle&#39;s utility circuit, for example, through the lateral branch of corresponding support arm  47 . The other plate  49  is electrically connected to zero volt contactor  42  to allow zero volt resetting, for example, through the lateral branch of corresponding support arm  47 . 
   In the realm of normal vehicle operation, the system for the ground power supply, according to the invention, provides for sensor subassemblies  38  to be inserted in cable duct  4  in the sensor position at the beginning of the line and to leave it only at the end of the line. 
   However, for reasons of safety and quick intervention and disengagement, the system of the invention allows subassemblies  38  to be disconnected and support unit  46  to be extracted while on line, for example, if there is a breakdown, an accident, or any type of problem. 
   Advantageously, this separation while on line may be accomplished if there is a serious breakdown threatening passenger safety without damaging the other elements present in the cable duct. Furthermore, it ensures that elements outside the cable duct are disconnected from the electrical source. 
   For this purpose, and as shown in  FIG. 9 , support assembly  46  can be longitudinally disconnected at the level of lateral reinforcing bars  50 . It can also be split into an upper interface piece  52  and at least one, preferably two, lower connection pieces  53 . Upper interface piece  52  preferably extends on each of its sides into a lower connecting piece  53 , each terminating in two connection plates  49 . 
   Preferably, the two connecting pieces  53  are identical and are generally U-shaped. They may be joined to upper interface piece  52  with a pin or shear screw  54  that yields to a predetermined amount of overhead pressure. 
   It is evident that the invention is not limited to the preferred modes of embodiment described above and shown in the different drawings, since a person skilled in the art could make numerous modifications and conceive of other variations without departing from the scope and context of the invention.