Current collector for an electrically or hybrid-electrically driven road vehicle, and road vehicle equipped with a current collector of this type
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-06-26
- Publication Date
- 2026-04-08
Smart Images
Figure EP2024067891_06032025_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Pantograph for an electric or hybrid-electric road vehicle and a road vehicle equipped with such a pantograph
[0003] The invention relates to a current collector according to the preamble of patent claim 1.
[0004] Such a pantograph is known from the published patent application DE 10 2021 208 951 A1 and shows a pantograph for an electrically or hybrid-electrically powered road vehicle for feeding in traction energy from a two-pole overhead line system. The pantograph comprises a main frame which is 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 carries two rocker assemblies arranged next to one another, each of which comprises 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, so that electrical contact can be made and broken again between the contact strips and the contact wires of the overhead line system that provide electrical traction voltage. The current collector comprises electrical insulation that separates three electrical potential layers from one another: The main frame, the lower arm bearing and, if applicable, an adjoining part of the arm structure are located on a chassis potential layer of the chassis. The contacting contact strips and the 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 an 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 includes 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 includes an arm structure that acts as an insulator itself due to its material properties.
[0005] The pantograph monitors electrical insulation between the traction voltage potential level and the intermediate potential level, as well as electrical insulation between the intermediate potential level and the chassis potential level. Should the electrical insulation between two adjacent potential levels be faulty, the arm structure is lowered to interrupt the electrical contact between the contact strips and the contact wires, before overhead line voltage can be applied to the chassis and pose an electrical hazard to persons.
[0006] It has been shown that in road operation of a pantograph as described above, a critical insulation resistance can be undershot without any noticeable damage to one of the electrical insulators or to the arm construction which itself acts as an insulator due to its material properties, which can lead to a possibly unnecessary lowering of the pantograph and thus to an undesirable interruption of the energy feed from the overhead line system.
[0007] The invention is therefore based on the object of providing a current collector of the type mentioned at the outset with increased availability for the supply of traction energy while maintaining its electrical operational reliability.
[0008] The invention is based on 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 the vehicle is moving. 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 stretched parallel to one another and symmetrically along the center of the lane 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 link. However, it can also have one lower arm and two upper arms. Other support rods are conceivable. The support rod has an end on the vehicle side, at which it can be supported on a chassis of the road vehicle via a base joint. Opposite this end, which is fixed to the vehicle, the support rod has a movable end on the contact wire side, 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 rods, for example by means of a lifting device designed as an air bellows, the contact strips can be brought into electrical sliding contact with the contact wires while the vehicle is in motion in order to transfer electrical traction energy from the overhead line system to the road vehicle. The contact strips can each have a contact piece made of graphite or copper, fastened in a contact piece holder, with a contact surface facing upwards. The support rods can be designed like a pantograph, whereby the contact surfaces always face upwards when the support rods are raised and lowered. The axes of rotation of the rocker joints and the base joint are aligned parallel to one another, for example transverse to the direction of travel.
[0009] The pantograph also has double electrical insulation to ensure 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, which rests 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.
[0010] According to the invention, the at least one support arm has a sheathing which at least partially covers the arm section and has an outer side which repels foreign layers. The invention is based on the knowledge gained that during road operation of the pantograph, dirt, coal 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 an electrical conductivity which can reduce the designed insulation resistance of the insulating arm section. The designed insulation resistance is determined by the section length, by the arm cross-section and by the insulation material used in 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 the outer side of the sheathing having adhesion-reducing properties, i.e. developing low adhesive forces to 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, so that there are 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 energy supply from the overhead line system.
[0011] 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 manufacture of the current collector or applied to it using an injection molding process. The covering can also be subsequently applied to a support arm with an insulating section of an existing current collector. The smooth, hydrophobic surface of silicone has foreign layer-repellent properties, so that dust or large-area layers of liquid cannot form or adhere to it.
[0012] In a further advantageous embodiment of the current collector according to the invention, an adhesive layer is introduced 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 liquids could collect in such air gaps, which could undesirably reduce the insulation resistance of the support arm with the insulating arm section. 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 front ends of the sheath and thereby reduce or prevent leakage currents forming in conductive foreign layers on the sheath, which reduce the insulation resistance of the insulating arm section.The ribs can be plate-, umbrella- or bell-shaped and their number can be adapted to the length of the casing.
[0013] 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.
[0014] 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 reduce the insulation resistance.
[0015] In a further advantageous embodiment, the current collector according to the invention comprises a vibrating element for generating vibrations of the at least one support arm. The vibrations periodically accelerate components of a foreign layer adhering to the casing, 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 can be actively designed and, for example, can be constructed as a voice coil coupled to the casing or to the inside of a hollow arm section.
[0016] 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 eddies of the airstream periodically detach, 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 a power supply.
[0017] 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, in which they are compared with threshold values. If one of the measured values falls below a threshold value, the control unit triggers a lowering of an upright support rod so that the electrical contact between the contact strips and the contact wires is interrupted and the current collector is transferred to an electrically safe state.
[0018] 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 which carries an electric or hybrid-electric traction drive and a current collector according to one of the preceding claims. Further features and advantages of the invention will become apparent from the following description of an embodiment with reference to the drawings, in which
[0019] FIG 1 is a side view of a road vehicle according to the invention with pantograph,
[0020] FIG 2 shows a first embodiment of a casing,
[0021] FIG 3 a second embodiment of a sheath,
[0022] FIG 4 a third embodiment of a sheath and
[0023] FIG 5 shows a fourth embodiment of a casing, schematically illustrated.
[0024] According to FIG 1, a road vehicle 1 is equipped with an electric or hybrid-electric traction drive 2 which, due to the rubber-tired vehicle wheels 3, is carried by an unearthed chassis 4 of the road vehicle 1. The road vehicle 1 can be designed as a heavy commercial vehicle, for example as a truck or bus. In order to feed 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 one another 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.
[0025] 1, the current collector 6 comprises an adjustable 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, and 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 current collector 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, as seen 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 grinding strips 19 arranged one behind the other in the direction of travel V, which are elongated and extend transversely to the direction of travel V.By erecting the support rod 9 by means of a lifting device 20 of the pantograph 6, which is 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 traveling, 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 piece 22 made of graphite or copper, fastened in a contact piece 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 upwards 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. The direction of travel V is understood here as a direction of a longitudinal axis of the road vehicle 1 .
[0026] The current collector 6 comprises double electrical insulation as a device for electrical operational safety according to FIG 1. The rocker supports 17 are at an electrical intermediate potential PI. The rocker supports 17 are insulated on the one hand 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 from the base joint 14 which is at an electrical chassis potential PC by an arm section 24 of the lower support arm 10 made of an insulating material. 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 therefore 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 also have the arm section 24 made of insulating material or can consist 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, in which 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 upright support rod 9 so that the electrical contact between the contact strips 19 and the contact wires 5 is interrupted and the current collector 6 is brought into an electrically safe state.
[0027] According to the invention, the support arm 10 has a casing 28 which at least partially covers the arm section 24 and has an outer side 29 which repels foreign layers. Foreign layers are understood here to mean deposits on the outer side 29 of the casing 28 which can form during road use of the current collector 6 as a result of dirt, carbon abrasion from the contact pieces, 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 which reduces the insulation resistance of the arm section 24 without the casing 28, as a result of which the support frame 9 can be lowered without the double insulation being damaged.The sheathing 28 prevents the formation of electrically conductive foreign layers in the area of the insulating arm section 24 by its outer side 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, so that fewer faults occur in which the current collector 6 is lowered because the insulation resistance drops below a critical threshold. This, in turn, increases the operating time during which the current collector 6 is available for power supply from the overhead line system.
[0028] 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, lengthens the creepage path between its front ends 31 and, on the other hand, prevents the formation of continuous foreign layers due to the large surface area, which would reduce the insulation resistance.
[0029] According to FIG. 3, an adhesive layer 33 is applied between an inner side 32 of the covering 30 and the support arm 10. This adhesive layer 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.
[0030] 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.
[0031] According to FIG. 5, the sheathing 28 is designed 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 sheathing 28.
[0032] 1 and 3, the current collector 6 according to the invention comprises a vibrating element 36 for generating vibrations of the at least one support arm. As a result of the vibrations, components of a foreign layer adhering to the casing 28 are periodically accelerated, as a result of which 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 two-dimensional connection is destroyed. The vibrating element 36 can be actively designed and can be in the form of a voice coil 37 coupled to the casing 28 or, as shown in FIG. 3, to the inside of a hollow arm section 24. However, the vibrating element 36 can also be in the form of a passive molded part 38 which is set into vibration by the airstream. Vortices of the airstream periodically detach from the aerodynamic molded part, as a result of which it sets the arm section 24 and thus the casing 28 into vibration.This also shakes off electrically conductive dirt and water deposits from the sheath 28 without the need for activation or energy supply.
Claims
Patent claims 1. A 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 - a support rod (9) which can be directed and has at least one support arm (10) and has 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 connected 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 in that - 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 claim 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 a directed 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 unearthed chassis (4) , - an electric or hybrid-electric traction drive (2) and - a current collector (6) according to one of the preceding claims.