Home electric vehicle charging system

Abstract

A mobile electric vehicle (EV) charging unit 1 includes a platform 2 carrying a payload, which includes an electrical storage accumulator (e.g., battery) for charging an EV. A plurality of wheels (e.g

Description

TECHNICAL FIELD OF THE INVENTION This invention relates to a charging system for electric vehicles, and more particularly to a charging system which incorporates a mobile charging unit suitable for use in domestic or other environments with limited access. BACKGROUND Although the UK Government has proposed a ban on the sale of new petrol and diesel vehicles by 2030 there is a critical lack of electric vehicle (EV) charging infrastructure in the country. The cost of installing home charging units is prohibitive for many home owners, and many households lack access to off-road parking or garages with access to a suitable electricity supply. Where nearby on-road parking is available it is undesirable to run electrical cables across a public footpath where they might present a trip hazard to the public. Robotic charging units for use in car parking areas are already known. For example, US 2019 / 0315240-Al discloses an autonomous EV charger which manoeuvres itself to a parked vehicle, plugs itself into the vehicle and couples itself to a charging receptacle. When charging is complete the robot returns to a base station and recharges via a retractable power cord. Another robotic charger is disclosed in WO 2019 / 185 589-Al. In this case the robot incorporates a rotatable take-up reel which is configured to automatically wind and unwind a cable to connect the EV to a power supply. In one embodiment the robot is provided with caterpillar tracks which, to a limited extent, enables the robot to negotiate steps, although the central platform does maintain a safe level attitude. Another known motorised charging unit the size of a shopping-trolley contains batteries which are charged at a wall charger before being driven to where the EV is parked. The unit uses Muscular Strength Enhancement technology as the human-robot interface, directly correlating movement of a push-bar with drive system inputs. A combination of ultrasound and LiDAR (Light Direction and Ranging) is used to reduce the risk of driving the unit into obstacles. The design of most of the known products assumes a substantially flat driving surface, such as in a multi-storey car park. This cannot be guaranteed in public spaces which frequently include obstacles such as kerbs and steps. If the connecting cable is eliminated such mobile chargers are required to carry an electrical accumulator, which could typically weigh as much as 750kg, and would therefore require several people to move the unit up or down a kerb. Furthermore, space is often at a premium in road-side parking areas, with little room to parka mobile charging unit near an EV. The present invention seeks to provide a new and inventive EV charging system which is suitable for home use or other applications where there is no fixed charging point close at hand, where access may be physically difficult, space may be limited, and where an unattended unit may be vulnerable to theft or vandalism. SUMMARY OF THE INVENTION When viewed from one aspect the present invention proposes a mobile electric vehicle charging unit which includes a platform carrying a payload which includes an electrical storage accumulator for charging an electric vehicle. A plurality of wheels are driven to move the platform along a surface and a plurality of outriggers connect the wheels to the platform. The outriggers are angularly movable relative to the platform to raise and lower the platform relative to the said surface. The charging unit includes a control unit for manually controlling movement of the charging unit, and a flexible cable extends between the control unit and the platform to carry electrical signals between the control unit and the platform. The flexible cable includes a breakaway connector which is configured to immobilise the charging unit in the event that the electrical signals are interrupted by separation of the connector. The breakaway connector preferably has two parts which are held together by a magnetic connection. In a preferred embodiment one of the connector parts incorporates pins which form an electrical connection with contact pads on the other connector part. In a preferred embodiment first and second planar outriggers are joined to front and rear ends of the platform by hinge connections which are independently movable to vary the angle between the respective outrigger and the platform. In a preferred embodiment each outrigger has a pair of mecanum wheels mounted on the opposite edge from the platform enabling the platform to be steered around or over substantial obstacles. In a preferred embodiment the charging unit has a memory to store a negotiable route from a storage position to an electric vehicle. The charging unit preferably also has collision avoidance sensors which provide feedback to the user if the unit approaches an obstacle. BRIEF DESCRIPTION OF THE DRAWINGS The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: Figure 1 is a general view of a mobile electric vehicle charging unit, shown in a step-climbing configuration; Figure 2 is a top plan view of the EV charging unit shown in Fig. 1; Figure 3 is a detailed internal view of the EV charging unit as viewed from above; Figure 4 shows a detailed internal view of the main platform of the charging unit; Figure 5 shows a detailed internal view of one of the outriggers; Figure 6 is a general view of a breakaway connector of the charging unit, with a portion removed for clarity; Figure 7 is a plan view of the breakaway connector as shown in Fig. 6; Figures 8a-8d are side views of the EV charging unit in various configurations. DETAILED DESCRIPTION OF THE DRAWINGS Referring firstly to Fig.s 1 and 2, the EV charging unit 1 comprises a platform 2 which is provided with front and rear outriggers 3 and 4. A flexible cable 5 connects the platform 2 to a control unit 6 for manually controlling movement of the charging unit, and the cable incorporates a breakaway connector 7. The platform 2 is of generally planar rectangular shape and is configured to carry a payload which includes an electrical storage accumulator (not shown) which is suitable for charging an electric vehicle. The outriggers 3 and 4 are also of generally planar rectangular shape and are pivotably connected to opposite front and rear edges of the platform 2 to move angularly in a hinging manner between an upwardly-inclined position (as with outrigger 3) to a downwardly-inclined position (as with outrigger 4). The outer edges 8 and 9 of the outriggers 3 and 4 are each provided with a pair of spaced ground wheels 10, 11 and 12, 13 respectively, which are driven to move the platform along the ground or other suitable surface. The preferred internal structure of the EV charging unit will now be described in greater detail. Referring to Fig.s 3 and 4, the platform 2 includes parallel front and rear walls 20 and 21 and a pair of parallel side walls 22 and 23. The side walls carry LiDAR units 24 and 25 which use light in the form of a pulsed laser to measure ranges (variable distances) from potential obstructions. The side walls 22 and 23 also extend beyond the front and rear walls, 20 and 21, which each carry a pair of inset flanges 26, 27 and 28, 29. As can be seen in Fig.s 3 and 5, the outrigger 3 (outrigger 4 being substantially identical) has a base plate 31, a cross wall 32, and parallel side walls, 33 and 34. The side walls are pivotably connected to the side walls 22 and 23 of platform 2 by aligned pivot connections 35 and 36 (Fig. 3). The base plate 31 is formed with notches 37 and 38 to receive the flanges 22 and 27 so that pivotal movement of the outrigger is not impeded. As shown in Fig.s 3 and 4, electric stepper motors 40 and 41, which are are fixed to the base plate 31, are coupled to the flanges 28 and 29 via respective gearing and output spindles which are aligned with the pivot connections 35 and 36. The motors can therefore adjust the hinge angle between the outrigger and the platform 2 allowing both outriggers to be independently adjusted through 180 degrees. Referring again to Fig. 5, the outer edge 8, 9 of each outrigger is provided with a further LiDAR unit 43 to detect potential obstructions in a forward or rearward direction. The wheels 10 and 11 are mounted at the same edge, on opposite sides of the LiDAR unit, also driven by respective electric motors 44 and 45 via suitable powertrains. As can be seen in Fig.s 3 and 5, the EV charging unit uses mecanum wheels. These are a form of tyreless wheel, with a series of rubberized external rollers obliquely attached around the whole circumference of the rim. Each mecanum wheel is an independent non-steering drive wheel with its own high torque powertrain, and when rotating, generates a propelling force perpendicular to the roller axles. By varying the relative speed and direction of rotation of the four wheels the propelling force can be vectored to produce movement of the charging unit forward, rearward or sideways in any direction, or rotate the unit about its centre. The control unit 6 enables the speed and direction of the EV charging unit to be manually controlled via the cable 5. The control unit also provides visual and tactile feedback to alert the user to any potential operational dangers. The breakaway connector 7 provides safety measure when operating the charging unit, allowing a reliable two-way connection in normal use while enabling easy detachment of the hand controller 6. As shown in Fig.s 6 and 7, the connector 7 has a male part 50 and a female part 51, both of which include an injection moulded outer casing. A portion of the male casing 50 is shown removed to reveal the internal structure. Each connector part comprises a printed circuit board (PCB) 52 which is housed within the respective casing. The male PCB has a set of electrical contact pins 54, arranged in a circular configuration, which contact corresponding SMD pads on the opposing female PCB. A notch 55 and corresponding lug are incorporated to ensure that the two halves of the connector can only be joined in one orientation. The mating faces of the two halves 50 and 51 also incorporate high strength neodymium magnets 53 which normally hold the two parts together. However, if the charging unit begins to move too far away from the user, the electrical connection will be lost, causing the unit to come to an immediate standstill. Apart from operational safety, the connector also provides a safe and reliable way of ensuring that the charging unit cannot be stolen when unattended since the unit cannot easily be moved without the hand controller connected. The changing unit incorporates a memory which enables the user to store a series of inputs required to manoeuvre the charger from a storage location to a charging location negotiating around, or over, any obstacles which are encountered on route. On-board tilt sensors also ensure that the platform is automatically maintained level and alerts the user if the platform approaches an unsafe inclination and, if the tilt is not corrected, brings the unit to a halt. The low profile of the unit enables it to be safely driven and stowed under most EVs while the vehicle is being charged. Fig. 8 shows various charger configurations which, for example, enable the unit to move over a kerb or step without tilting the platform 2 to an unstable angle, which could risk the unit rolling over. Fig. 8a shows the unit in a co-planar configuration which can be used for movement over flat level ground and facilitates stowing the unit under a vehicle during charging. Fig. 8b shows the unit encountering a step, with the outriggers being adjusted to maintain the platform is a safe level condition. The mecanum wheels grip sufficiently to drive up a near-vertical surface with continued forward movement. Fig. 8c shows one end of the platform at the top of the step while the rear end remains at the lower level. Again, the platform remains substantially level throughout the step-climbing procedure. In Fig. 8d the two outriggers are both adjusted to raise the platform, which might be more suitable for traveling over rough ground. Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

Claims

1. A mobile electric vehicle charging unit:- a platform (2) carrying a payload which includes an electrical storage accumulator for charging an electric vehicle;- a plurality of wheels (10-13) which are driven to move the platform along a surface;- a plurality of outriggers (3, 4) which connect the wheels to the platform, said outriggers being angularly movable relative to the platform to raise and lower the platform relative to said surface;- a control unit (6) for manually controlling movement of the charging unit;- a flexible cable (5) extending between the control unit and the platform to carry electrical signals between the control unit and the platform;- a breakaway connector (7) included in the flexible cable and configured to immobilise the charging unit in the event that the electrical signals are interrupted by separation of the connector.

2. The mobile electric vehicle charging unit of claim 1 wherein the breakaway connector has two parts (50, 51) held together by a magnetic connection.

3. The mobile electric vehicle charging unit of claim 2 wherein one of the connector parts incorporates pins (54) which form an electrical connection with contact pads on the other connector part.

4. The mobile electric vehicle charging unit of any preceding claim wherein first and second planar outriggers (3, 4) are joined to front and rear ends of the platform by hinge connections which are independently movable to vary the angle between the respective outrigger and the platform.

5. The mobile electric vehicle charging unit of any preceding claim wherein each outrigger has a pair of mecanum wheels mounted on the opposite edge from the platform.

6. The mobile electric vehicle charging unit of any preceding claim wherein the charging unit has a memory to store a negotiable route from a storage position to an electric vehicle.

7. The mobile electric vehicle charging unit of any preceding claim wherein the charging unit has collision avoidance sensors (24, 25, 43).

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