Charging station for charging an electric energy storage device of an electric or hybrid electric vehicle

Abstract

The invention relates to a charging station (4) for charging an electric energy storage device (2) of a vehicle (1), in particular a road or rail vehicle which has a current collector (5) with at least one raisable and lowerable contact strip (10) in order to supply energy from a single- or double-pole overhead line system. The charging station (4) comprises at least one charging contact (11) per contact pole (9), said charging contact being arranged above a charging position for the vehicle (1) such that at least one point of contact (14) can be produced between the contact strip (10) and the charging contact (11) for each contact pole (9). Charging processes can be carried out with higher charging currents, and therefore with shorter charging times, in that the charging contact (11) of the charging station (4) according to the invention has a heat sink (15) for cooling the point of contact (14).

Description

[0001] Description

[0002] Charging station for charging an electrical energy storage device of an electric or hybrid-electric vehicle

[0003] The invention relates to a charging station for charging an electrical energy storage device of an electrically or hybrid-electrically powered vehicle at a standstill, in particular a road or rail vehicle, according to the preamble of patent claim 1.

[0004] A charging station for charging an electrical energy storage device of an electrically powered rail vehicle is known from the published patent application DE 10 2010 029 450 A1. To supply the electrical drive of the rail vehicle, an electrical circuit is provided which is also connected to the energy storage device and controls the electrical charging of the energy storage device via two electrical contacts. The electrical circuit has a switch via which the energy storage device and / or the drive can be supplied with energy from the charging station. The first electrical contact is designed as a contact between an overhead line and a current collector for electrically contacting an energy source of the charging station. The second electrical contact of the charging station is designed between a wheel of the rail vehicle and a rail.The energy source is connected to both the overhead line and the rail on which the wheels run. For example, a positive voltage connection of the energy source is connected to the overhead line and a negative voltage connection is connected to the rail via a supply line. The energy storage device is connected to the negative voltage connection of the charging station with a further supply line, either directly or via the electrical circuit. The electrical circuit is designed in such a way that, before the electrical connection is established or before the electrical connection between the vehicle and the charging station is interrupted, the electrical voltage and / or current between the energy storage device and the charging station is adjusted in such a way that little or no current flows via the electrical contacts when the electrical connection is established or interrupted.

[0005] From the published patent application DE 10 2017 203 046 A1, it is known for electrically or hybrid-electrically powered road vehicles to charge the energy storage device while driving via an energy feed from a two-pole overhead line system using a vehicle-mounted pantograph. The pantograph comprises a pantograph-like frame, which carries a rocker with two contact strips for each contact pole. While driving, the contact strips of each contact pole are in sliding contact with the contact wires assigned to the respective contact pole, so that electrical energy can be fed in both directly for the traction drive and for charging the energy storage device.In contrast to ferry operation, when the vehicle is stationary, there is no movement of the point contact point between the contact strip and the contact wire, nor is there any cooling airflow. Therefore, the supply current must be selected so low that overheating-related damage to the contact strip and / or contact wire does not occur. Charging the energy storage system while the vehicle is stationary is therefore time-consuming.

[0006] From the published patent application DE 10 2019 214 552 A1, a charging station for charging an electrical energy storage device of a road vehicle is known, which charging station has a current collector with at least one raising and lowering contact strip per contact pole for feeding in energy from a two-pole overhead line system. The charging station comprises at least two charging contacts per contact pole, which are arranged above a charging position for the road vehicle and next to one another in such a way that at least two contact points can be established between the contact strip and the charging contacts for each contact pole. The electrical contact between the overhead line system and the road vehicle is formed by a large number of contact points, via which the charging power is transferred. The electrical heat generated per contact point decreases with an increasing number of contact points and can be dissipated better due to the spatial distribution of the contact points.Due to limitations in vehicle weight and dimensions, the dimensions of the contact strips are predetermined so that the two or more charging contacts allow for a higher charging current, which reduces charging time. Depending on the desired charging current, the number of charging contacts can be varied, with two, three, or four charging contacts being preferred.

[0007] The disclosure document DE 10 2019 214 708 A1 shows a charging station for charging an electrical energy storage device of a road vehicle when stationary, for example at transshipment points for transported goods, in vehicle depots or in parking lots where no overhead line system is available. In order to feed in energy from a two-pole overhead line system while in motion, the road vehicle has a current collector with at least one raising and lowering contact strip per contact pole. The charging station comprises at least one charging contact for each contact pole. The charging contacts are arranged above a charging position for the road vehicle, for example on a charging mast, and next to one another in such a way that at least one contact point can be established between the contact strip and the charging contact for each contact pole.At least one charging contact has a contact body at its lower end which comprises a cushion which can be deformed by the pressure of the current collector and an electrically conductive, flexible sheath. The lower ends of the charging contacts face the contact strips of a road vehicle in the charging position, so that by lifting the contact strips a contact can be made between the contact strips and the contact bodies. Because the contact body has a deformable cushion and a flexible sheath, when the contact strips are pressed against it a large contact surface is created with the contact body of the charging contacts for the transfer of the charging current. This reduces the current density and the associated heating of the contact strips.

[0008] The invention is therefore based on the object of providing a charging station of the type mentioned at the beginning, which enables shorter charging times when the vehicle is stationary.

[0009] The object is achieved by a charging station with the features specified in patent claim 1. Accordingly, a charging station is designed and provided for charging an electrical energy storage device of a vehicle which has a current collector with at least one raising and lowering contact strip for feeding energy from a trackside overhead line system while driving. The vehicle can be a rail vehicle with earthed wheels, the current collector having at least one contact strip for electrical contact with a contact wire of a single-pole overhead line system. However, the vehicle can also be a road vehicle with rubber-tired wheels, the current collector having at least one contact strip for each contact pole for electrical contact with the two contact wires of a two-pole overhead line system.The charging station comprises at least one charging contact for each contact pole, which is arranged, for example, on a charging mast above a charging position for the vehicle in such a way that at least one contact point can be created between the contact strip and the charging contact for each contact pole. According to the invention, the at least one charging contact has a heat sink for cooling the contact point. The heat sink can be designed as a separate component or integrated into the charging contact. This allows the electrically conductive contact point of the charging contact, which can be made of copper or another metallic material, to be effectively cooled. Depending on the design, the heat sink can be actively or passively cooled, so that heat generated at higher charging currents exceeding 100 A can be dissipated via the heat sink, which in turn allows shorter charging times.In an advantageous embodiment of the charging station according to the invention, the cooling body has at least one cooling channel of a closed cooling circuit in which a cooling fluid circulates. The system of cooling channels can actively convey cooling air, moved by means of a conveying device, to the contact point and, after absorbing electrical heat, away from this point. The course and cross-section of the cooling channels can be adapted to the size and shape of the charging contact or its cooling body using optimization methods. The cooling channels can be formed by straight or serpentine tubes or slots, which can also be combined with cooling fins.

[0010] In a further advantageous embodiment of the charging station according to the invention, the heat sink has an open-pore structure through which a cooling fluid flows. The heat sink is interspersed with a multitude of interconnected, small cavities. This structure can be formed, for example, from a metal foam and has a very large inner surface along which the cooling fluid, for example cooling air, flows through the heat sink, absorbing and dissipating the heat generated in the charging contact during the charging process. This allows the energy storage device to be charged at higher charging currents.

[0011] In a further advantageous embodiment of the charging station according to the invention, the open-pore structure is designed such that cooling fluid flowing through it flows out of the heat sink in the direction of the contact point. The open-pore structure can be unsealed, in particular on a side facing the contact point between the charging contact and the contact strip, or it can have a device such as a flow channel or a guide plate that directs the cooling fluid to the contact point, whereby the contact strip is additionally cooled by the escaping cooling fluid. This can reduce the temperature of the two contact partners, the charging contact and the contact strip, and in turn enable higher charging currents to be used.

[0012] In a further advantageous embodiment of the charging station according to the invention, the heat sink has at least one latent heat accumulator. The heat sink can preferably have a metallic, closed-pore structure with a large inner surface in which a large number of latent heat accumulators are evenly distributed. A latent heat accumulator absorbs the electrical heat generated in the charging contact or in its heat sink and stores it, so that during the charging process the electrical heat does not lead to an increase in the temperature of the charging contact, or only leads to a minor increase. In this way, the latent heat accumulators stabilize the surrounding thermally and electrically conductive structure for transmitting the charging current.The stored energy is released again by the latent heat storage devices after the charging process, for example while the vehicle is moving, which puts them in a state ready to absorb energy again during the next charging process.

[0013] In a further advantageous embodiment of the charging station according to the invention, the latent heat storage device is designed as an encapsulated phase change material integrated into the heat sink. Phase change materials utilize the effect that during a phase transition, for example from the solid to the liquid phase of the material, despite a continuous supply of thermal energy, there is no increase in the material temperature until the phase transition is fully completed. During the phase transition, a significantly larger amount of energy can be absorbed and stored than is necessary to heat the material in one phase. The absorbed energy is released evenly again after the charging process and leads to the conversion of the material from the liquid to the solid phase. The phase change material can, for example, be paraffin or salt-based and can be adjusted for almost any temperature range.They exhibit different energy densities and storage capacities and can be optimally selected for each application. Phase-change materials can also be used, whose phase changes from liquid to gaseous upon energy absorption. However, it should be noted that the increase in volume associated with the phase change is greater than with materials that utilize the phase change from solid to liquid. This may require measures due to the encapsulation of the phase-change material.

[0014] In a further advantageous embodiment of the charging station according to the invention, the encapsulation of the latent heat storage device has a compensation volume in addition to the phase-change material. By considering small compensation volumes for each individual reservoir of a phase-change material in the form of only partially filled capsules, the problem of the material's volume increase during the phase change can be managed without placing excessive mechanical stress on the metallic structure of the heat sink.

[0015] In a further advantageous embodiment of the charging station according to the invention, an encapsulation of the latent heat storage device has a flexible compensation membrane, which separates the interior volume of the encapsulation from a compensation channel leading from the heat sink. If the encapsulation is completely filled with the phase-change material, volume increases during the phase change can be compensated for by the expansion of one or more flexible compensation membranes of the encapsulation, which allow the material to expand into one or more compensation channels leading outwards.

[0016] In a further advantageous embodiment of the charging station according to the invention, the heat sink has at least one thermochemical heat storage device. Alternatively or in addition to latent heat storage devices, thermochemical heat storage devices can also be used, some of which have even higher energy densities. Thermochemical heat storage devices, for example those based on metal hydrides or zeolites, store the heat generated in the heat sink during the charging process through endothermic reactions and later release it through exothermic reactions. Care must be taken to ensure a sufficiently even distribution of the heat storage devices in the conductive structure of the heat sink in order to achieve an optimal energy sink. This can preferably be optimized with the help of evolutionary algorithms.Evolutionary algorithms are nature-analogous stochastic optimization methods in which solution candidates - here: a distribution of heat storage devices in a heat sink - are artificially evolved for a specific problem - here: a large heat absorption by the heat storage devices.

[0017] In a further advantageous embodiment of the charging station according to the invention, the charging contact has a contact side facing the contact strip, with a large number of contact filaments arranged on the contact side. The electrically conductive contact filaments increase the current transmission area between the charging contact and the contact strip, since in practice there are no flat contact surfaces between the charging contacts and the contact pieces due to wear, such as chipping and uneven wear on the carbon contact pieces of the contact strips. The large number of contact filaments, which can also be spring-loaded or flexurally elastic, increases the contact area and thus the contact quality while maintaining a constant contact force between the contact strip and the charging contact, which in turn allows the charging currents to be increased.The contact filaments can protrude from the contact side of the charging contact in the form of a column, rod, spiral, tube, or grid and, for example, have barbs like those on a Velcro fastener. The contact filaments can be manufactured in one piece with the charging contact by direct metal laser sintering using a 3D printer. The contact element is optimized based on the maximum transferable charging current for a given contact force, taking into account not only the contact area but also the maximum heat that can be extracted from the carbon. Further advantages and properties of the invention will become apparent from the following description of exemplary embodiments with reference to the drawings.

[0018] FIG 1 shows a front view of a road vehicle positioned in a charging station according to the invention,

[0019] FIG 2 a front view of the sliding strip and charging contact of a contact pole from FIG 1 ,

[0020] FIG 3 shows a first embodiment of a heat sink for a charging contact,

[0021] FIG 4 shows a second embodiment of a heat sink for a charging contact,

[0022] FIG 5 a third embodiment of a heat sink for a charging contact and

[0023] FIG 6 shows a fourth embodiment of a heat sink for a charging contact schematically.

[0024] According to FIG 1, an electrically or hybrid-electrically powered vehicle 1 is positioned in a charging station 4 installed on a roadway 3 for charging its electrical energy storage device 2. The vehicle 1 is designed as a road vehicle and is equipped with a current collector 5 for feeding energy during travel from a two-pole overhead line system, of which, for the sake of simplicity, only the contact wires 6 designed as forward and return conductors are shown above a lane of the roadway 3 adjacent to the charging position. The current collector 5 has, for example, a pantograph-like support frame 7, which is supported on a chassis (not shown) of the vehicle 1 and can be set up and folded up by means of a lifting device (likewise not shown).The support frame 7 carries two contact rockers 8 arranged next to one another in the vehicle's longitudinal direction X - one for each contact pole 9 - which are each equipped with a pair of contact strips 10 arranged one behind the other in the vehicle's longitudinal direction X and extending in a vehicle transverse direction Y. If the vehicle 1 uses the electrified lane, the contact strips 10 can be brought into sliding contact with the respective contact wire 6 by setting up the support frame 7 in a vehicle vertical direction Z in order to feed energy from the overhead line system into the vehicle 1.

[0025] However, in the illustrated embodiment, the charging station 4 is arranged away from the electrified lane and comprises a charging contact 11 for each contact pole 9, which is arranged above the charging position for the vehicle 1. It is also possible to provide several, for example two or four, charging contacts 11 for each contact pole 9. For this purpose, the charging contacts 11 can be connected to a side arm 12 of the charging station 4, which projects above the charging position from a charging mast 13 set up to the side of the lane 3. The charging voltage is provided to the charging contacts 11 of the respective contact poles 9 via electrical lines (not shown) running in the charging mast 13 and the side arm 12.To charge the energy storage device 2 in the charging station 4, the vehicle 1 is brought into the charging position in which the current collector 5 is set up and its contact strips 10 are pressed against the charging contacts 11 to create an electrical charging contact. The pressure force acting at a contact point 14 between the contact strip 10 and the charging contact 11 can be, for example, 100 N. Once contact has been made, a charging current of at least 100 A is switched on, which flows via one of the two contact poles 9 from the associated charging contact 11 into the contacting contact strip 10 and via the other of the two contact poles 9 from the contacting contact strip 10 back into the associated charging contact 11.

[0026] According to FIG 2, the at least one charging contact 11 has a heat sink 15 for cooling the contact point 14. The heat sink 15 can be designed as a separate component or integrated into the respective charging contact 11. This allows the electrically conductive contact point 14 of the charging contact 11, which can consist of copper or another metallic material, to be effectively cooled. Depending on the design, the heat sink 15 can be cooled actively or passively, so that current heat that arises at higher charging currents exceeding 100 A can also be dissipated via the heat sink 15, which leads to shorter charging times.

[0027] Furthermore, the charging contact 11 according to FIG 2 has a contact side 16 facing the contact strip, on which a large number of contact filaments 17 are arranged. The electrically conductive contact filaments 17 increase the current transmission area between the charging contact 11 and the contact strip 10. The contact piece 19, which is carried by a contact piece holder 18 of the contact strip 10, is typically made of carbon and is subject to wear in practical use. For example, breakages and uneven wear of the contact piece 19 can lead to unevenness in the area of ​​the contact point 14, which is compensated for by the large number of contact filaments 17. The contact filaments 17 can be spring-loaded or flexurally elastic and thus increase the contact quality with a constant contact force between the contact strip 10 and the charging contact 11, which in turn allows an increase in the charging currents.The contact filaments 17 can protrude from the contact side 16 of the charging contact 11 in a columnar, rod-shaped, helical, tubular, or grid-shaped manner and, for example, have barbs like those of a Velcro fastener. The contact filaments 17 can be manufactured in one piece with the charging contact 11 by direct metal laser sintering using a 3D printer. The contact element 17 is optimized based on the maximum transferable charging current for a given contact force, taking into account not only the contact area but also the maximum heat that can be extracted from the contact piece 19.

[0028] According to FIG 3, the heat sink 15 has cooling channels 20 of a closed cooling circuit 21 in which a cooling fluid circulates. The system of cooling channels 20 can actively convey cooling liquid or cooling air, moved by means of a conveying device 22, to the contact point 14 and, after absorbing electrical heat, away from this, where the absorbed thermal energy can be released into the environment. The course and cross-section of the cooling channels 20 can be adapted to the size and shape of the charging contact 11 or its heat sink 15 using optimization methods. The cooling channels 20 can be formed by straight or serpentine tubes or slots, which can also be combined with cooling fins.

[0029] 4, the heat sink 15 has an open-pored structure through which a cooling fluid 23 flows. The heat sink 15 is penetrated by a large number of connected, small cavities 24. This structure can be formed, for example, from a metal foam and has a very large inner surface along which the cooling fluid 23, for example cooling air, flows through the heat sink 15 and can absorb and transport away the heat generated in the charging contact 11 during the charging process. The open-pored structure is designed in particular such that cooling fluid 23 introduced into the heat sink, for example by means of a conveying device 22, flows out of the heat sink 15 in the direction of the contact point 14.The open-pore structure can be unsealed, particularly on a contact side 16 facing the contact point 14 between the charging contact 11 and the contact strip 10, which additionally cools the contact strip 10 by the escaping cooling fluid 23. This allows the temperature of the two contact partners, charging contact 11 and contact strip 10, to be lowered, thus enabling higher charging currents to be used.

[0030] According to FIGS. 5 and 6, the heat sink 15 has a metallic, closed-pore structure with a large inner surface, which is not shown in more detail and in which a large number of latent heat accumulators 25 are evenly distributed. A latent heat accumulator 25 absorbs the electrical heat generated in the charging contact 11 or in its heat sink 15 and stores it, so that during the charging process the electrical heat does not lead to an increase in the temperature of the charging contact 11, or only to a minor extent. In this way, the latent heat accumulators 25 stabilize the thermally and electrically conductive structure surrounding them for transmitting the charging current. The stored energy is released again by the latent heat accumulators 25 after the charging process, for example while the vehicle 1 is traveling, whereby they are put into a state for renewed energy absorption during the next charging process.Alternatively, instead of the latent heat storage 25, the heat sink 15 can also have thermochemical heat storage, which sometimes has even higher energy densities. Thermochemical heat storage, for example based on metal hydrides or zeolites, store the electrical heat generated during the charging process in the heat sink 15 through endothermic reactions and later release it through exothermic reactions. Care must be taken to ensure a sufficiently uniform distribution of the heat storage in the conductive structure of the heat sink 15 in order to achieve an optimal energy sink. This can preferably be optimized with the aid of evolutionary algorithms.

[0031] According to FIGS. 5 and 6, the latent heat storage devices 25 are designed as encapsulated phase change materials 26 integrated into the heat sink 15. Phase change materials 26 utilize the effect that during a phase transition, for example from the solid to the liquid phase of the material 26, despite a continuous supply of thermal energy, there is no increase in the material temperature until the phase transition is fully completed. The absorbed energy is released evenly after the charging process and leads to the conversion of the material 26 from the liquid to the solid phase. The phase change material 26 can, for example, be produced on a paraffin or salt basis and can be adjusted for almost any temperature range. They have different energy densities and storage capacities and can be optimally selected for the respective application.Phase-change materials can also be used, whose phase changes from liquid to gaseous through energy absorption. However, it should be noted that the volume increase associated with the phase change is greater than with materials 26 that utilize the phase change from solid to liquid. This may require measures due to the encapsulation 27 of the phase-change material 26.

[0032] Thus, according to FIG. 5, an encapsulation 27 of the latent heat storage device 25 has a compensation volume 28 in addition to the phase-change material 26. By considering small compensation volumes 28 for each individual reservoir of a phase-change material 26 in the form of only partially filled encapsulations 27, the problem of the increase in volume of the material 26 during the phase change can be managed without subjecting the metallic structure of the heat sink 15 to excessive mechanical stress.

[0033] According to FIG 6, an encapsulation 27 of the latent heat accumulator 25 can have a flexible compensation membrane 29, which separates the internal volume of the encapsulation 27 from a compensation channel 30 leading from the heat sink 15. If the encapsulation 27 is completely filled with the phase change material 26, volume increases during the phase change can be compensated by the expansion of one or more flexible compensation membranes 29 of the encapsulation 27, which enable the material 26 to expand into one or more compensation channels 30 leading outwards.

Claims

Patent claims 1. Charging station (4) for charging an electrical energy storage device (2) of a vehicle (1), in particular a road or rail vehicle, which has a current collector (5) with at least one raising and lowering contact strip (10) for feeding energy from a single-pole or two-pole overhead line system, comprising at least one charging contact (11) for each contact pole (9), which is arranged above a charging position for the vehicle (1) in such a way that at least one contact point (14) can be produced between the contact strip (10) and the charging contact (11) for each contact pole (9), characterized in that the charging contact (11) has a cooling body (15) for cooling the contact point (14).

2. Charging station (4) according to claim 1, - wherein the heat sink (15) has at least one cooling channel (20) of a closed cooling circuit (21) in which a cooling fluid circulates.

3. Charging station (4) according to claim 1, - wherein the heat sink (15) has an open-pored structure through which a cooling fluid flows.

4. Charging station (4) according to claim 3, - wherein the open-pore structure is designed such that cooling fluid flowing through the heat sink (15) flows out in the direction of the contact point (14).

5. Charging station (4) according to claim 1, - wherein the heat sink (15) has at least one latent heat accumulator (25).

6. Charging station (4) according to claim 5, - wherein the latent heat storage device (25) is designed as an encapsulated phase change material (26) integrated into the heat sink (15).

7. Charging station (4) according to claim 6, - wherein an encapsulation (27) of the latent heat storage device (25) has a compensation volume (28) in addition to the phase change material (26).

8. Charging station (4) according to claim 6, - wherein an encapsulation (27) of the latent heat accumulator (25) has a flexible compensating membrane (29) by which the internal volume of the encapsulation (27) is separated from a compensating channel (30) leading from the cooling body (15).

9. Charging station (4) according to claim 1, - wherein the heat sink (15) has at least one thermochemical heat accumulator.

10. Charging station (4) according to one of the preceding claims, - wherein the charging contact (11) has a contact side (16) facing the contact strip (10), - wherein a plurality of contact filaments (17) are arranged on the contact side (16).

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