Current collector for an electrically or hybrid-electrically powered road vehicle and a road vehicle equipped with such a current collector

Abstract

The invention relates to a pantograph (6) for an electrically or hybrid-electrically powered road vehicle (1) for supplying traction energy from contact wires (5) of a two-pole overhead line system. It comprises an erectable support frame (9) having at least one support arm (10) with a vehicle-side end (13) at which it can be supported on a chassis (4) of the road vehicle (1) via a base joint (14), and with a contact wire-side end (16) to which two contact strip carriers (19) supporting rocker arms (17) are rotatably articulated via a rocker joint (18) each.It has double electrical insulation, in which the contact strips (17) are at an intermediate electrical potential (PI) and are insulated on the one hand by electrical insulators (23) from the contact strips (19) which are at an overhead line potential (PO) and on the other hand by an arm section (24) of the at least one support arm (10) made of an insulating material from the base joint (14) which is at an electrical chassis potential (PC). According to the invention, the at least one support arm (10) has a sheathing (28) with a foreign-layer-repellent outer surface (29) that at least partially covers the arm section (24), thereby increasing the availability of the pantograph (6) while maintaining its electrical operational reliability.

Description

[0001] The invention relates to a current collector according to the preamble of patent claim 1.

[0002] Such a pantograph is known from the published patent application DE 10 2021 208 951 A1, which shows a pantograph for an electrically or hybrid-electrically powered road vehicle for feeding traction energy from a two-pole overhead line system. The pantograph comprises a main frame supported on a chassis, i.e. the undercarriage of the road vehicle, and on which an arm structure with a lower arm and an upper arm is mounted. The lower arm is rotatably connected to the main frame via a lower arm bearing and rotatably connected to the upper arm via an arm joint. The arm structure supports two adjacent rocker assemblies, each comprising a rocker support carrying two contact strips. Each rocker support is rotatably connected to the upper arm via a rocker joint.The arm structure can be moved up and down like a pantograph using a drive, allowing electrical contact to be established and broken between the contact strips and the contact wires of the overhead line system that provide electrical traction voltage. The pantograph comprises electrical insulation that separates three electrical potential layers from each other: The main frame, the lower arm bearing, and any adjoining part of the arm structure are located on a chassis potential layer. The contacting contact strips and power cables that conduct the traction current are located on a traction voltage potential layer of the contact wires. The rocker supports, the rocker joints, and at least one adjoining part of the arm structure are located on an intermediate potential layer.To separate the traction voltage potential level from the intermediate potential level, the insulation comprises electrical insulators between the contact strips and the rocker supports, which can be designed as leaf springs made of insulating material. To separate the intermediate potential level from the chassis potential level, the electrical insulation, in one embodiment, comprises an arm structure that acts as an insulator itself due to its material properties.

[0003] The pantograph monitors the electrical insulation between the traction voltage potential level and the intermediate potential level, as well as the electrical insulation between the intermediate potential level and the chassis potential level. Should the electrical insulation between two adjacent potential levels be compromised, the arm structure lowers the electrical contact between the contact strips and the contact wires, breaking the electrical contact before overhead line voltage can be applied to the chassis and potentially endangering people.

[0004] It has been shown that in road operation of a pantograph as described above, a critical insulation resistance may be undershot without any noticeable damage to one of the electrical insulators or to the arm structure, which itself acts as an insulator due to its material properties. This may lead to an unnecessary lowering of the pantograph and thus to an undesirable interruption of the power supply from the overhead line system.

[0005] The invention is therefore based on the object of providing a pantograph of the type mentioned above with increased availability for the supply of traction energy while maintaining its electrical operational reliability.

[0006] The invention relates to a current collector for an electrically or hybrid-electrically powered road vehicle, in particular for a heavy commercial vehicle, such as a truck or a bus. The current collector is designed and provided to feed traction energy from contact wires of a two-pole overhead line system into the road vehicle in order to supply it to an electric or hybrid-electric traction drive or an energy storage device of the road vehicle while driving. Two-pole overhead line systems for electrifying a lane of a road on which a road vehicle can travel are known; the two contact wires are arranged parallel to each other and symmetrically along a lane center above the roadway and can provide an overhead line voltage, for example, as a direct voltage. The current collector comprises an erectable support rod having at least one support arm.The support rod can have two parallel, rod-shaped support arms. It can also have a lower arm and an upper arm like a half-scissor. However, it can also have one lower arm and two upper arms. Other support rods are conceivable. The support rod has a vehicle-side end at which it can be supported on a chassis of the road vehicle via a base joint. Opposite this vehicle-fixed end, the support rod has a movable, contact wire-side end to which two rocker supports are each pivotally connected via a rocker joint. The rocker supports can be arranged next to one another in the direction of travel and each can be assigned to a contact wire. Each rocker support can carry one or two contact strips arranged one behind the other in the direction of travel, whereby each contact strip can be elongated and extend transversely to the direction of travel.By raising the support rod, for example, using a lifting device designed as an air bellows, the contact strips can be brought into electrical sliding contact with the contact wires during travel, transferring electrical traction energy from the overhead line system to the road vehicle. The contact strips can each have a graphite or copper contact strip mounted in a contact strip holder with an upward-facing contact surface. The support rod can be designed like a pantograph, whereby the contact surfaces always face upward when the support rod is raised and lowered. The axes of rotation of the rocker joints and the base joint are aligned parallel to each other, for example, transversely to the direction of travel.

[0007] The pantograph also includes double electrical insulation for electrical operational safety. The rocker supports are at an intermediate electrical potential. On the one hand, the rocker supports are insulated from the contact strips, which are at an electrical overhead line potential, by electrical insulators. On the other hand, the rocker supports are insulated from the base joint, which is at an electrical chassis potential, by an arm section of at least one support arm made of an insulating material. This means that the chassis of the road vehicle and the vehicle parts conductively connected to it, such as the base joint or a main frame of the pantograph connected to it and mounted on the chassis, are doubly electrically insulated from the contact strips.The rocker supports, the rocker joints and, if applicable, that electrically conductive part of the at least one support arm which is located on the contact wire side of the insulating arm section are at the intermediate potential.

[0008] According to the invention, the at least one support arm has a sheathing that at least partially covers the arm section and has a foreign layer-repellent outer surface. The invention is based on the finding that, during road operation of the pantograph, dirt, carbon abrasion, road salt, and / or liquids are deposited on the at least one support arm, in particular also on the arm section made of insulating material. Such deposits form a foreign layer with electrical conductivity that can reduce the design insulation resistance of the insulating arm section. The design insulation resistance is determined by the section length, the arm cross-section, and the insulation material used for the arm section of the support arm.The sheathing according to the invention prevents the formation of electrically conductive foreign layers in the area of ​​the insulating arm section by providing the outer side of the sheath with adhesion-reducing properties, meaning it exerts low adhesion forces on such deposits. As a result, the insulation resistance of the insulating arm section is not reduced or only slightly reduced by foreign layers of dirt, dust, water, and the like, resulting in fewer faults in which the pantograph is lowered from the overhead line because the insulation resistance drops below a critical threshold. This, in turn, increases the operating time during which the pantograph is available for power supply from the overhead line system.

[0009] In an advantageous embodiment of the current collector according to the invention, the sheathing is designed as an elastic covering. The covering can be made of silicone or a comparable hydrophobic material, for example, and can be slipped over the insulating arm section as an elastic tube during production of the current collector or applied to it using an injection molding process. Likewise, the covering can be subsequently applied to a support arm with an insulating section of an existing current collector. The smooth, hydrophobic surface of silicone has contaminant-repelling properties, so that dust or large-area liquid layers cannot form or adhere to it.

[0010] In a further advantageous embodiment of the current collector according to the invention, an adhesive layer is applied between an inner side of the covering and the at least one support arm. The adhesive layer increases the strength of the connection between the covering and the support arm and prevents the formation of an air gap between the covering and the support arm. Electrically conductive fluids could collect in such air gaps, which could undesirably reduce the insulation resistance of the support arm with the insulating arm section.

[0011] In a further advantageous embodiment of the current collector according to the invention, the sheath has one or more annular ribs. The ribs extend the path between the ends of the sheath and thereby reduce or prevent leakage currents that form in conductive foreign layers on the sheath, which reduce the insulation resistance of the insulating arm section. The ribs can be plate-shaped, shield-shaped, or bell-shaped, and their number can be adapted to the length of the sheath.

[0012] In a further advantageous embodiment of the current collector according to the invention, the sheathing is designed as a coating. The coating of the insulating arm section of the support arm with a hydrophobic material can be achieved, for example, by spraying or lamination. By coating, a thinner wall thickness of the sheathing can be achieved than is the case with a coating. The coating also reduces the adhesion of foreign layers to the sheathing.

[0013] In a further advantageous embodiment of the current collector according to the invention, the length between the front ends of the sheath is dimensioned so large that no continuous foreign layer forms between the ends. An extended sheath, on the one hand, extends the creepage distance between its front ends and, on the other hand, prevents the formation of continuous foreign layers due to its large surface area, which would otherwise reduce the insulation resistance.

[0014] In a further advantageous embodiment, the current collector according to the invention comprises a vibrating element for generating vibrations of at least one support arm. The vibrations periodically accelerate components of a foreign layer adhering to the casing, thereby exerting a force on the foreign layer components that exceeds the adhesion. The foreign layer is shaken off by the vibrations or at least its surface connection is destroyed. The vibrating element can be actively designed and, for example, can be formed as a voice coil coupled to the casing or to the inside of a hollow arm section.

[0015] In a further advantageous embodiment of the current collector according to the invention, the vibrating element has a shape that generates vibrations due to the airstream. The vibrating element is a passive, aerodynamic molded part from which periodic vortices of the airstream are ejected, causing the arm section and thus the casing to vibrate. This also shakes off electrically conductive dirt and water deposits from the casing without the need for activation or power supply.

[0016] In a further advantageous embodiment, the current collector according to the invention comprises first measuring units for detecting first insulation resistances of the electrical insulators. Furthermore, the current collector comprises at least one second measuring unit for detecting a second insulation resistance of the insulating arm section with sheath. The measured values ​​of the first and second insulation resistances are fed to a control unit of the current collector, where they are compared with threshold values. If one of the measured values ​​falls below a threshold value, the control unit triggers the lowering of an erected support rod, thereby interrupting the electrical contact between the contact strips and the contact wires and transferring the current collector to an electrically safe state.

[0017] The invention further relates to a road vehicle, in particular a heavy commercial vehicle, such as a truck or a bus. It comprises an ungrounded chassis supporting an electric or hybrid-electric traction drive and a pantograph according to one of the preceding claims.

[0018] Further features and advantages of the invention will become apparent from the following description of an embodiment with reference to the drawings, in which Fig. 1 a side view of a road vehicle according to the invention with pantograph, Fig. 2 a first embodiment of a casing, Fig. 3 a second embodiment of a casing, Fig. 4 a third embodiment of a casing and Fig. 5 a fourth embodiment of a casing, are illustrated schematically.

[0019] According to Fig. 1, a road vehicle 1 is equipped with an electric or hybrid-electric traction drive 2, which, thanks to the rubber-tired vehicle wheels 3, is carried by an ungrounded chassis 4 of the road vehicle 1. The road vehicle 1 can be designed as a heavy commercial vehicle, for example, a truck or bus. For feeding in electrical traction energy from contact wires 5 of a two-pole overhead line system, the road vehicle 1 comprises a pantograph 6. The traction energy fed in during travel is either fed directly to the traction drive 2 or stored in an energy storage device 7. The two contact wires 5 are stretched parallel to each other and symmetrically along a lane center above the lane 8 traveled by the road vehicle 1 and provide an overhead line voltage, for example in the form of a direct voltage.

[0020] The pantograph 6 comprises according to Fig. 1 an erectable support rod 9, which has a lower support arm 10 and two upper arms 11, each of which is rotatably connected to the support arm 10 via a knee joint 12. At least one support arm 10. The support rod 9 has a vehicle-side end 13, at which it is supported on the chassis 4 via a base joint 14 by means of a main frame 15 of the pantograph 6. Opposite this vehicle-fixed end 13, the support rod 9 has a movable, contact wire-side end 16, to which two rocker supports 17 are each rotatably connected via a rocker joint 18. The rocker supports 17 are arranged next to one another - viewed in the direction of travel V of the road vehicle 1 - and are each assigned to a contact wire 5. Each rocker support 17 carries two contact strips 19, which are elongated and extend transversely to the direction of travel V.By raising the support rod 9 by means of a lifting device 20 of the pantograph 6, designed, for example, as an air bellows, the contact strips 19 can be brought into electrical sliding contact with the contact wires 5 while the vehicle is moving, in order to transfer electrical traction energy from the overhead line system to the road vehicle 1. The contact strips 19 can each have a contact strip 22 made of graphite or copper, fastened in a contact strip holder 21, with an upwardly facing contact surface. The support rod 9 can be designed in the manner of a pantograph, whereby the contact surfaces always point upward when the support rod 9 is raised and lowered. The axes of rotation of the rocker joints 18, the knee joint 12, and the base joint 14 are aligned parallel to one another and transversely to the direction of travel V. Direction of travel V is understood here to mean a direction of a longitudinal axis of the road vehicle 1.

[0021] The pantograph 6 comprises as a device for electrical operational safety in accordance with Fig. 1 has double electrical insulation. The rocker supports 17 are at an electrical intermediate potential PI. On the one hand, the rocker supports 17 are insulated by electrical insulators 23 from the contact strips 19, which are at an electrical overhead line potential PO. On the other hand, the rocker supports 17 are insulated by an arm section 24 of the lower support arm 10 made of an insulating material from the base joint 14, which is at an electrical chassis potential PC. The chassis 4 of the road vehicle 1 and the vehicle parts conductively connected to it, such as the base joint 14 or main frame 15, are thus doubly electrically insulated from the contact strips 19. The rocker supports 17, the rocker joints 18, the upper arm 11 and, if applicable, that electrically conductive part of the lower support arm 10 which is on the contact wire side of its insulating arm section 24 are at the intermediate potential PI.The insulating arm section 24 can also extend over the entire support arm 10. Alternatively, the upper arm 11 can have the arm section 24 made of insulating material or be made entirely of insulating material. The current collector 6 comprises first measuring units 25 for detecting first insulation resistances of the electrical insulators 23. Furthermore, the current collector 6 comprises at least one second measuring unit 26 for detecting a second insulation resistance of the insulating arm section 24. The measured values ​​of the first and second insulation resistances are fed to a control unit 27 of the current collector 6, where they are compared with threshold values. If one of the measured values ​​falls below a threshold value, the control unit 27 triggers a lowering of an erected support rod 9 so that the electrical contact between contact strips 19 and contact wires 5 is interrupted and the current collector 6 is transferred to an electrically safe state.

[0022] According to the invention, the support arm 10 has a sheath 28 at least partially covering the arm section 24, having an outer surface 29 that repels foreign layers. Foreign layers are understood here to mean deposits on the outer surface 29 of the sheath 28 that can form during road operation of the current collector 6 due to dirt, carbon abrasion from the contact strips, road salt from the road surface, and / or liquids such as rain, snow, oil, or swirling spray. Such foreign layers can have an electrical conductivity that reduces the insulation resistance of the arm section 24 without the sheath 28, thereby triggering a lowering of the support frame 9 without damaging the double insulation. The sheath 28 prevents the formation of electrically conductive foreign layers in the area of ​​the insulating arm section 24 by virtue of its outer surface 29 having adhesion-reducing properties, i.e., exerting low adhesion forces on such deposits.As a result, the insulation resistance of the insulating arm section 24 is not reduced or only slightly reduced by foreign layers, resulting in fewer faults in which the pantograph 6 is lowered because the insulation resistance drops below a critical threshold. This, in turn, increases the operating time during which the pantograph 6 is available for power supply from the overhead line system.

[0023] According to Fig. 2, the sheath 28 is designed as an elastic covering 30 made of silicone or a comparable hydrophobic material and can be slipped over the insulating arm section 24 as an elastic tube or applied thereto by injection molding. A length L between the front ends 31 of the sheath 28 can be dimensioned so large that no continuous foreign layer forms between the ends 31. An extended sheath 28, on the one hand, extends the creepage path between its front ends 31 and, on the other hand, prevents the formation of continuous foreign layers due to its large surface area, which would reduce the insulation resistance.

[0024] According to Fig. 3, an adhesive layer 33 is applied between an inner side 32 of the covering 30 and the support arm 10, which increases the strength of the connection between the covering 30 and the support arm 10 and prevents the formation of an air gap between the covering 30 and the support arm 10. Electrically conductive fluids could collect in such air gaps, which could undesirably reduce the insulation resistance of the support arm 10 with the insulating arm section 24.

[0025] According to Fig. 4, the sheath 28 has one or more annular ribs 34, which extend the path between the front ends 34 of the sheath 28 and thereby prevent leakage currents forming in conductive foreign layers on the sheath 28, which reduce the insulation resistance of the insulating arm section 24. The ribs 34 can be plate-shaped, shield-shaped, or bell-shaped, and their number can be adapted to the length L of the sheath 28.

[0026] According to Fig. 5, the sheath 28 is formed as a coating 35. The coating 35 of the insulating arm section 24 of the support arm 10 with a hydrophobic material can be achieved, for example, by spraying or lamination. Coating can achieve a reduced wall thickness of the sheath 28.

[0027] According to Fig. 1 and Fig. 3, the current collector 6 according to the invention comprises a vibrating element 36 for generating vibrations of the at least one support arm. Due to the vibrations, components of a foreign layer adhering to the casing 28 are periodically accelerated, whereby a force exceeding the adhesion is exerted on the foreign layer components. The foreign layer is shaken off by the vibrations or at least its surface connection is destroyed. The vibrating element 36 can be actively designed and can be connected to the casing 28 or according to Fig.3, a voice coil 37 coupled to the inside of a hollow arm section 24 can be formed. However, the vibrating element 36 can also be designed as a passive molded part 38 that is set into vibration by the airstream. Vortices of the airstream periodically detach from the aerodynamic molded part, causing the arm section 24 and thus the casing 28 to vibrate. This also shakes off electrically conductive dirt and water deposits from the casing 28 without the need for activation or power supply. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 208 951 A1

[0002]

Claims

[1] Current collector (6) for an electrically or hybrid-electrically driven road vehicle (1), in particular for a heavy commercial vehicle, for feeding traction energy from contact wires (5) of a two-pole overhead line system, comprising - an erectable support rod (9) having at least one support arm (10) with a vehicle-side end (13) at which it can be supported on a chassis (4) of the road vehicle (1) via a base joint (14), and with a contact wire-side end (16) to which two rocker supports (17) carrying contact strips (19) are rotatably articulated via a rocker joint (18) each, and - a double electrical insulation, in which the rocker supports (17) are at an intermediate electrical potential (PI) and are insulated on the one hand by electrical insulators (23) from the contact strips (19) lying at an electrical overhead line potential (PO) and on the other hand by an arm section (24) of the at least one support arm (10) consisting of an insulating material from the base joint (14) lying at an electrical chassis potential (PC), characterized by , - that the at least one support arm (10) has a casing (28) at least partially covering the arm section (24) with an outer side (29) that repels foreign layers. [2] Current collector (6) according to claim 1, - wherein the sheath (28) is designed as an elastic cover (30). [3] Current collector (6) according to claim 2, - wherein an adhesive layer (33) is introduced between an inner side (32) of the cover (30) and the at least one support arm (10). [4] Current collector (6) according to claims 1 to 3, - wherein the casing (28) has one or more annular ribs (34). [5] Current collector (6) according to claim 1, - wherein the sheath (28) is designed as a coating (35). [6] Current collector (6) according to one of claims 1 to 5, - wherein a length (L) between the front ends (31) of the sheath (28) is dimensioned so large that no continuous foreign layer forms between the ends (31). [7] Current collector (6) according to one of claims 1 to 6, - comprising a vibrating element (36) for generating vibrations of the at least one support arm (10) which are suitable for shaking off a foreign layer forming on an outer side (29) of the casing (28) or for destroying its connection. [8] Current collector (6) according to claim 7, - wherein the vibrating element (38) has a shape by which it generates the vibrations due to the wind. [9] Current collector (6) according to one of claims 1 to 8, comprising - first measuring units () for detecting first insulation resistances () of the electrical insulators (), - at least one second measuring unit () for detecting a second insulation resistance of the arm section () of the at least one support arm () with sheath (), and - a control unit () for triggering a lowering of an erected support rod () if a first and / or second insulation resistance falls below a predetermined threshold value. [10] Road vehicle (1), in particular heavy commercial vehicle, comprising - an ungrounded chassis (4), - an electric or hybrid-electric traction drive (2) and - a current collector (6) according to one of the preceding claims.

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