Vehicle charging method and apparatus

Abstract

Aspects of the present invention relates to a locking pin (3) for locking a charging plug (5) in a charging socket (7) to secure a vehicle charging cable (9). The locking pin (3) includes a shaft port

Description

TECHNICAL FIELD The present disclosure relates to a vehicle charging method and apparatus. Aspects of the invention relate to a locking pin for locking a charging plug in a charging socket; a locking pin assembly, a charging plug, a charging socket, a vehicle, a charging station, a fracture detector, a charging controller, a method of detecting a fracture and a method of controlling charging of a vehicle. BACKGROUND It is known to provide a locking pin for locking a charging plug in a charging socket of an electric vehicle. The locking pin may be engaged to prevent the withdrawal or insertion of a charging socket, for example when the vehicle is locked. The locking pin may be fractured, for example if a user attempts to insert or withdraw the charging plug when the locking pin is in a locked position. The fractured locking pin may not be capable of locking the charging plug in the charging socket. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a locking pin for locking a charging plug in a charging socket; a locking pin assembly, a charging plug, a charging socket, a vehicle, a charging station, a fracture detector, a charging controller, a method of detecting a fracture and a method of controlling charging of a vehicle as claimed in the appended claims. According to an aspect of the present invention there is provided a locking pin for locking a charging plug in a charging socket to secure a vehicle charging cable, the locking pin comprising: a shaft portion having a proximal end and a distal end; and an electrically conductive element extending at least partway along a length of the shaft portion towards the distal end thereof, the electrically conductive element forming a continuous electrical loop for detecting a fracture in the shaft portion of the locking pin. The electrically conductive element is provided to enable detection of a fracture in the shaft portion of the locking pin. A fracture in the shaft portion will typically cut, sever or otherwise interrupt the electrically conductive element. By measuring a voltage across the electrically conductive element (or an electric current through the electrically conductive element), a fracture in the shaft portion can be detected. At least in certain embodiments the electrically conductive element enables the structural integrity of the locking pin to be monitored. A fracture in the locking pin may be detected in dependence on a determination that the electrically conductive element has been cut or severed. At least in certain embodiments, the distal end of the shaft portion locates in an aperture or a recess to lock the charging plug in the charging socket. Alternatively, or in addition, the shaft portion may comprise a locking tab for engaging a cooperating feature to lock the charging plug in the charging socket. The locking tab may, for example, be disposed at the distal end of the shaft portion. The electrically conductive element may extend into the distal end of the shaft portion. If the shaft portion is fractured, for example the distal end of the shaft portion is severed from the remainder of the shaft portion, the electrically conductive element is interrupted. By monitoring the voltage across the electrically conductive element, the fracture in the shaft portion can be detected. The fracture may cause the distal end of the shaft portion to be removed (sheared) from the remainder of the shaft portion. Alternatively, or in addition, the fracture may comprise a crack, fissure or cut in the shaft portion. The shaft portion may be formed of an electrically insulating material. At least in certain embodiments, the shaft portion may be composed of a plastic material. At least the shaft portion of the locking pin may be moulded from the plastics material. The electrically conductive element may comprise first and second sections electrically connected to each other at the distal end of the shaft portion to form the continuous electrical loop. The first and second sections may each extend at least partway along the length of the shaft portion towards the distal end thereof. The first and second sections may form a continuous loop. The first and second sections may be coaxial. Alternatively, the first and second sections may extend parallel to each other. The electrically conductive element may comprise a loop section for electrically connecting the first and second sections. The electrically conductive element may comprise a continuous wire or filament. The first and second sections may be electrically insulated from each other. An electrical insulator may be disposed between the first and second sections to insulate the first and second sections from each other along their length. The electrical insulator may be formed integrally with the shaft portion. For example, the shaft portion may be formed of a plastic material. The shaft portion could, for example, be moulded around the electrically conductive element. At least one of the first and second sections extends from the proximal end to the distal end of the shaft portion. The locking pin may comprise one or more electrical connector for connecting the electrically conductive element to a control unit or a fracture detector. A first electrical connector may be connected to the first electrical section; and a second electrical connector may be connected to the second electrical section. At least one of the first and second sections may comprise one or more frangible section. The or each frangible section may be predisposed to break, thereby interrupting the continuous electrical loop. The or each frangible section may comprise or consist of a reduced thickness or width. The electrically conductive element may comprise a plurality of the frangible sections, for example spaced apart along the length of the first section and / or the second section. The shaft portion may comprise one or more stress raiser. The shaft portion may be predisposed to fracture coincident with the one or more stress raiser. The one or more stress raiser may comprise an aperture or a localised narrowing of the shaft portion. The or each stress raiser may be aligned with a frangible section of the electrically conductive element. The electrically conductive element may be at least partially embedded in the shaft portion. For example, the electrically conductive element may be at least partially encapsulated within the shaft portion. Alternatively, at least a portion of the electrically conductive element may be disposed on an exterior of the shaft portion. According to a further aspect of the present invention there is provided apparatus comprising a locking pin as described herein and a fracture detector for detecting a fracture in the shaft portion of the locking pin. The fracture detector may be connected to the electrically conductive element. In use, the fracture detector may be configured to supply a voltage to the electrically conductive element to detect a fracture in a shaft portion of the locking pin. At least in certain embodiments the fracture detector may check the integrity of the shaft portion. The apparatus may comprise a locking pin assembly. The locking pin and the fracture detector may be incorporated into the locking pin assembly. Alternatively, the fracture detector may be discrete from the locking pin assembly. The locking pin assembly may comprise an actuator for displacing the locking pin between a retracted position and a deployed position. The locking pin assembly may comprise a position detector for detecting a position of the locking pin. The fracture detector may be integrated into the position detector. For example, the electrically conductive element may be connected in series to the position detector. An interruption in the operation of the position detector may indicate a fracture in the locking pin. According to a further aspect of the present invention there is provided a charging plug for connection to a charging socket, the charging plug comprising a locking pin assembly as described herein. The charging plug may comprise one or more electrical pin for connection to a terminal in the charging socket. The one or more electrical pin may extend parallel to a longitudinal axis of the charging plug. The locking pin of the locking pin assembly may extend parallel to, or perpendicular to, the longitudinal axis of the charging plug. The charging socket may comprise a locking pm assembly as described herein. The charging socket may comprise one or more electrical terminal for connection to an electrical pin in the charging plug. The one or more electrical terminal may extend parallel to a longitudinal axis of the charging socket. The locking pin of the locking pin assembly may extend parallel to, or perpendicular to, the longitudinal axis of the charging socket. According to a further aspect of the present invention there is provided a vehicle comprising a charging plug as described herein. According to a further aspect of the present invention there is provided a charging cable for an electrical vehicle. The charging cable may comprise at least one charging plug as described herein and / or at least one charging socket as described herein. According to a further aspect of the present invention there is provided an electrical vehicle charging station comprising a charging plug as described herein, or a charging socket as described herein. The electrical vehicle charging station may be in the form of a wall box. According to a further aspect of the present invention there is provided a fracture detector for detecting a fracture in a shaft portion of a locking pin for locking a charging plug in a charging socket, the locking pin comprising an electrically conductive element forming a continuous electrical loop in the shaft portion, wherein the fracture detector comprises one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal and an electrical output for outputting an output signal, the fracture detector comprising at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon, the input signal providing an indication of a voltage across, or an electric current through, the electrically conductive element. The at least one electronic processor may be configured to receive the input signal and monitor the electric current through, or the voltage across, the electrically conductive element. The at least one electronic processor may determine that the locking pin is fractured in dependence on a determination that the electric current through, or the voltage across, the electrically conductive element is zero or less than a predetermined threshold. The electrical output of the at least one electronic processor may comprise or consist of a pin status signal indicating that the locking pin is fractured. The pin status signal may be output in dependence on the determination that the electric current through, or the voltage across, the electrically conductive element is zero or less than the predetermined threshold. According to a further aspect of the present invention there is provided a charging controller for controlling charging of a traction battery disposed in a vehicle. The charging controller may be in communication with a fracture detector of the type described herein. The charging controller may be configured to inhibit or interrupt charging of the traction battery in dependence on the determination by the fracture detector that the locking pin is fractured. According to a further aspect of the present invention there is provided a charging controller for controlling charging of a traction battery disposed in a vehicle, wherein a charging plug and a charging socket are connected to each other to establish an electrical connection, and a locking pin having a shaft portion is provided for locking the charging plug in the charging socket; wherein the charging controller comprises one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal and an electrical output for outputting an output signal, the charging controller comprising at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon, the input signal providing an indication of a voltage across, or an electric current through, an electrically conductive element disposed in the shaft portion of the locking pin to lock the charging plug in the charging socket. The at least one electronic processor may be configured to receive the input signal and monitor the electric current through, or the voltage across, the electrically conductive element. The at least one electronic processor may be configured to inhibit or interrupt charging of the traction battery in dependence on a determination that the electric current through, or the voltage across, the electrically conductive element is zero or less than a predetermined threshold indicative of a fracture in the shaft portion of the locking pin. According to a further aspect of the present invention there is provided a method of detecting a fracture in a shaft portion of a locking pm for locking a charging plug in a charging socket, the locking pin comprising an electrically conductive element forming a continuous electrical loop in a shaft portion of the locking pin. The method may comprise monitoring the electric current through, or the voltage across, the electrically conductive element. The method may comprise detecting a fracture in the locking pin in dependence on a determination that the electric current through, or the voltage across, the electrically conductive element is zero or less than a predetermined threshold. The method comprises generating a notification that the locking pin is fractured. According to a further aspect of the present invention there is provided a method of controlling charging of a traction battery disposed in a vehicle. The method may comprise detecting a fracture in the locking pin using the method(s) as described herein. The method may comprise inhibiting or interrupting charging of the traction battery in dependence on detection of the fracture. According to a further aspect of the present invention there is provided a method of controlling charging of a traction battery disposed in a vehicle, wherein a locking pin having a shaft portion is provided for locking a charging plug in a charging socket, the locking pin comprising an electrically conductive element forming a continuous electrical loop in the shaft portion. The method may comprise monitoring the electric current through, or the voltage across, the electrically conductive element. The method may comprise detecting a fracture in the locking pin in dependence on a determination that the electric current through, or the voltage across, the electrically conductive element is zero or less than a predetermined threshold, The method may comprise inhibiting or interrupting charging of the traction battery in dependence on detection of the fracture. The locking pin may be of the type described herein. The charging of the traction battery may be inhibited or interrupted in dependence on the determination that the locking pin is fractured (i.e., not structurally intact). The method may comprise enabling charging of the traction battery in dependence on a determination that the locking pin is structural intact (i.e. not fractured). The method may comprise determining that the locking pin is structurally intact in dependence on a determination that the electric current through, or the voltage across, the electrically conductive element is greater than a predetermined threshold. The method may comprise displacing the locking pin to a locked position. The method may comprise monitoring a position of the locking pin. The method may comprise enabling the charging of the traction battery in dependence on a determination that the locking pin is disposed in the locked position. The charging of the traction battery may be inhibited or interrupted in dependence on a determination that the locking pin is not in the locked position. According to a further aspect of the present invention there is provided a control system comprising one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal; and at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon so as to implement the method(s) described herein. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a schematic representation of a vehicle incorporating a locking pin assembly in accordance with an embodiment of the present invention; Figure 2 shows a charging plug having an aperture for receiving a locking pm; Figure 3 shows a charging socket having a locking pin for locating in the aperture of the charging plug shown in Figure 2; Figure 4 shows a schematic representation of the charging socket shown in Figure 3; Figure 5 shows a control unit for controlling the operation of a locking pin actuator provided in the locking pin assembly shown in Figure 1; Figure 6A shows the locking pin assembly with the locking pin retracted to an unlocked position; Figure 6B shows the locking pin actuator of the locking pin assembly shown in Figure 6A with the locking pin in the unlocked position; Figure 7A shows the locking pin assembly with the locking pin extended to a locked position; Figure 7B shows the locking pin actuator of the locking pin assembly shown in Figure 7A with the locking pin in the locked position; Figure 8 shows a position detector for detecting a position of the locking pin in the locking pin assembly; Figure 9 illustrates a locking pin comprising a fracture detection element in accordance with an embodiment of the present invention; Figure 10 illustrates a fractured locking pin comprising a fracture detection element in accordance with an embodiment of the present invention; Figure 11 is a block diagram illustrating a method of controlling charging of a vehicle in accordance with an embodiment of the present invention; Figure 12 is a block diagram illustrating a method of detecting a fracture in a locking pin in accordance with an embodiment of the present invention; Figure 13 illustrates a locking pin in accordance with a further embodiment of the present invention; and Figure 14 shows a charging plug comprising a locking pin assembly in accordance with a further embodiment of the present invention. DETAILED DESCRIPTION A locking pin assembly 1 and a locking pin 3 in accordance with an embodiment of the present invention are described herein with reference to the accompanying Figures. As illustrated in Figure 1, the locking pin assembly 1 is configured to lock a charging plug 5 in a charging socket 7. The locking pin 3 in the present embodiment is configured to lock the charging plug 5 in the charging socket 7 to secure a vehicle charging cable 9. The charging plug 5 is shown in Figure 2; and the charging 7 is shown in Figure 3. The vehicle charging cable 9 is used to charge a traction battery 11 in a vehicle 13. The vehicle 13 is an automobile in the present embodiment. The traction battery 11 is provided to supply electrical energy to one or more electric drive unit 15 to propel the vehicle 13. The vehicle 13 in the present embodiment is a battery electric vehicle (BEV). Ina variant, the vehicle 13 may be a plug-in hybrid electric vehicle (PHEV). A charging controller 21 is provided to control charging of the traction battery 11. The charging controller 21 is provided onboard the vehicle 13. The charging socket 7 is provided on the vehicle 13, for example in a charging port. The charging socket 7 is configured to receive the charging plug 5 to establish an electrical connection. A schematic representation of the charging socket 7 is shown in Figure 4. The charging plug 5 and the charging socket 7 comprise a plurality of electrical connectors 19 having complementary profiles. The electrical connectors 19 typically comprise male and female connectors which contact each other when the charging plug 5 is introduced into the charging socket 7 to establish an electrical connection. In the present embodiment, the plurality of electrical connectors 19 comprise a plurality of electrical pins 19A and complementary sockets 19B. The charging plug 5 is introduced into the charging socket 7 along a first axis X. The electrical connectors 19 extend parallel to the first axis X. The first axis X is parallel to a longitudinal axis of the charging plug 5. The vehicle charging cable 9 connects the vehicle 13 to an electric vehicle charging station 17 (shown in Figure 1). The charging station 17 is connected to a mains electrical power supply and is operative to supply electrical energy via the vehicle charging cable 9 to charge the traction battery 11. The electric vehicle charging station 17 may be a charging wall box, for example a domestic charging wall box. Alternatively, the electric vehicle charging station 17 may be a commercial charging station. As shown in Figure 4, the locking pin assembly 1 comprises one or more locking pin actuator 23 and a mounting plate 25. The mounting plate 25 may be omitted, for example by mounting the locking pin assembly 1 directly to the charging socket 7. A control system 51 (shown in Figure 5) is provided to control operation of the locking pin assembly 1. The mounting plate 25 mounts the locking pin assembly 1 to the charging socket 7 (or an associated vehicle body structure). The locking pin actuator 23 comprises an electromechanical actuator, such as a solenoid, which is connected to the locking pin 3. The locking pin actuator 23 is configured selectively to displace the locking pin 3 between an unlocked position (shown in Figures 5 6A and 6B); and a locked position (shown in Figures 7A and 7B). In the unlocked position, the locking pin 3 is retracted to enable insertion and / or removal of the charging plug 5 from the charging socket 7. In the locked position, the locking pin 3 is extended so as to engage the charging plug 5 and prevent the charging plug 5 being withdrawn from the charging socket 7. In particular, the locking pin 3 is configured to locate in an aperture 29 (shown in Figure 2) formed in a sidewall 31 of the charging plug 5. When located in the aperture 29, the locking pin 3 prevents the charging plug 5 being displaced along the first axis X. In the present embodiment the locking pin actuator 23 is configured to displace the locking pin 3 along a second axis Y. The locking pin 3 travels along the second axis Y as it displaced between the retracted position and the extended position. In the present embodiment the second axis Y extends perpendicular to the first axis X. In a variant, the second axis Y may extend substantially parallel to the first axis X. In a further variant, the locking pin 3 may rotate between the retracted position and the extended position. The locking pin 3 comprises a head portion 41 and a shaft portion 43. The locking pin actuator 23 is bi-directional and applies an actuating force to displace the locking pin 3 between the locked position and the unlocked position. The locking pin actuator 23 is connected to the head portion 41. As described herein, the shaft portion 43 is configured to engage the charging plug 5 when the locking pin 3 is in the locked position. The shaft portion 43 is elongated along the second axis Y and comprises a proximal end 45 (disposed proximal to the head portion 41) and a distal end 47 (disposed remote from the head portion 41). The distal end 47 of the shaft portion 43 is configured to locate in the aperture 29 formed in the sidewall 31 of the charging plug 5. The distal end 47 of the locking pin 3 thereby performs the locking function. At least the shaft portion 43 of the locking pin 3 is formed from an electrically insulating material. In the present embodiment, the head portion 41 and the shaft portion 43 are moulded integrally from a plastics material. The locking pin assembly 1 may comprise a manual override mechanism (not shown) for applying a release force to displace the locking pin 3 to the unlocked position. As illustrated in Figure 5, the control system 51 comprises one controller 53, although it will be appreciated that this is merely illustrative. The controller 53 comprises processing means 55 and memory means 57. The processing means 55 may be one or more electronic processing device 55 which operably executes computer-readable instructions. The memory means 57 may be one or more memory device 57. The memory means 57 is electrically coupled to the processing means 55. The memory means 57 is configured to store instructions, and the processing means 55 is configured to access the memory means 57 and execute the instructions stored thereon. The control system 51 is configured to control operation of the locking pin actuator 23. As illustrated in Figure 5, the controller 53 comprises an input means 59 and an output means 61. The input means 59 may comprise an electrical input 59 of the controller 53. The electrical input 59 is configured to receive at least one control signal CS(n). The at least one control signal CS(n) may be received from the charging controller 21. The at least one control signal CS(n) is an electrical signal which is indicative of a requested state for the locking pin 3. The operation of the locking pin actuator 23 is controlled in dependence on the at least one control signal CS(n). The at least one control signal CS(n) comprises a lock request signal CS(1) to lock the charging plug 5; and an unlock request signal CS(2) to unlock the charging plug 5. The control system 51 is configured to control the locking pin actuator 23 to advance the locking pin 3 in dependence on the lock request signal CS(1). Conversely, the control system 51 is configured to control the at least one locking pin actuator 23 to retract the locking pin 3 in dependence on the lock request signal CS(1). The lock request signal CS(1) is generated in dependence on a request to lock the vehicle 13. Conversely, the unlock request signal CS(2) is generated in dependence on a request to unlock the vehicle 13. A position detector 71 is provided for detecting the position of the locking pin 3. The position monitor 71 is incorporated into the locking pin assembly 1 in the present embodiment. As shown schematically in Figure 8, the position detector 71 comprises a monitoring circuit 73 which includes first, second and third resistors R1, R2, R3 connected in parallel to each other. The monitoring circuit 73 also comprises firstand second switches S1, S2 connected in series to the first and second resistors R1, R2 respectively. The first and second switches S1, S2 are spaced apart from each other along the second axis Y. The first and second switches S1, S2 are actuated by the locking pin 3 as it travels between the locked position and the unlocked position. In particular, the head portion 41 of the locking pin 3 sequentially closes the first and second switches S1, S2 as it travels between the locked position and the unlocked position. The resistance of the monitoring circuit 73 changes depending on the operating state of the first and second switches S1, S2. By measuring the voltage across the monitoring circuit 73, the position detector 71 can determine if the locking pin 3 is disposed in the (retracted) unlocked position or the (advanced) locked position. The third resistor R3 provides a reference (base) voltage to indicate that the locking pin assembly 1 is operating. The position detector 71 is implemented by the control system 51 in the present embodiment but could 6 be implemented in a separate controller. A voltage signal VS(1) is input to the electrical input of the controller 53 to provide an indication of the voltage across the monitoring circuit 73. The output means 61 may comprise an electrical output 61 of the controller 53. The electrical output 61 is configured to output a pin status signal PS(n) indicating a determined position of the locking pin 3. The at least one pin status signal PS(n) is an electrical signal which is indicative of a determined locking pin state. A first pin status signal PS(1) indicates that the locking pin 3 is in the locked position; and a second pin status signal PS(2) indicates that the locking pin 3 is in the unlocked position. The pin status signal PS(n) is output to the charging controller 21 and optionally also the charging station 17. The charging controller 21 is configured to control the charging of the traction battery 11 in dependence on the pin status signal PS(n). The charging controller 21 is configured to enable charging of the traction battery 11 in dependence on a determination that the locking pin 3 is in the locked position. The charging controller 21 is configured to inhibit or stop charging of the traction battery 11 in dependence on a determination that the locking pin 3 is in the unlocked position. The locking pin 3 may be damaged due to incorrect or improper use. For example, the locking pin 3 may shear if excessive force is applied to the charging plug 5 when the locking pin 3 is in the locked position. A user may, for example, attempt forcibly to insert or remove the charging plug 5 when the locking pin 3 is in the locked position (or an intermediate position). The force applied to the locking pin 3 may fracture the shaft portion 43, for example by shearing the distal end 47 from the remainder of the locking pin 3. The fractured locking pin 3 may be unsuitable for locking the charging plug 5 in the charging socket 7. The head portion 41 typically remains intact and, in use, may continue to actuate the first and second switches S1, S2 of the position detector 71 as the locking pin 3 is displaced by the locking pin actuator 23. Thus, the position detector 71 may determine that the locking pin 3 is in the locked position even when the locking pin 3 is fractured and unsuitable for locking the charging plug 5 in the charging socket 7. The locking pin 3 according to the present embodiment comprises a fracture detection element 79, as shown in Figure 9. The fracture detection element 79 is in the form of an electrically conductive element 81 which extends at least partway along a length of the shaft portion 43 of the locking pin 3. At least a portion of the electrically conductive element 79 is encapsulated within the plastics material forming the shaft portion 43. In a variant, part or all of the electrically conductive element 79 may be disposed on an exterior of the shaft portion 43. A fracture detector 91 is provided for detecting a fracture in the shaft portion 43 of the locking pin 3. The fracture detector 91 is electrically connected to the fracture detection element 79. In use, an electric current is supplied to the fracture detection element 79. The fracture detector 91 measures the voltage across the fracture detection element 79 to detect a fracture or breakage in the locking pin 3. The control system 51 in the present embodiment is configured to implement the fracture detector 91. In a variant, the fracture detector 91 may be a separate controller. The electrically conductive element 79 forms a continuous (i.e. uninterrupted) electrical loop in the shaft portion 43 of the locking pin 3. The electrically conductive element 79 extends to the distal end 47 of the locking pin 3. In the present embodiment the electrically conductive element 79 extends into distal end 47 of the locking pin 3 which locates in the aperture 29 formed in the sidewall 31 of the charging plug 5. The electrically conductive element 79 comprises first and second sections 83A, 83B which extend along the length of the shaft portion 43 from the proximal end 45 to the distal end 47 thereof. The first and second sections 83A, 83B are electrically insulated from each other along their length. The electrically conductive element 79 in the present embodiment comprises a U-shaped electrically conductive element 79. The electrically conductive element 79 comprises or consists of a metal wire. In a variant, the electrically conductive element 79 may comprise or consist of a metal trace or a metal strip. The shaft portion 43 is moulded around the electrically conductive element 79, thereby encapsulating the electrically conductive element 79 inside the locking pin 3. The plastic material used to form the shaft portion 43 at least partially encapsulates the first and second sections 83A, 83B so as to electrically insulate them from each other along their length. The first and second sections 83A, 83B are electrically connected to each other at the distal end 47 of the shaft portion 43 to form the continuous electrical loop. The electrically conductive element 79 in the present embodiment comprises a loop section 83C which connects the first and second sections 83A, 83B to each other at the distal end 47 of the shaft portion 43, thereby closing the continuous electrical loop. The loop section 83C in the present embodiment is formed integrally with the first and second sections 83A, 83B. In a variant, the loop section 83C may be a separate component, such as a metal insert or a collar, which connects the first and second sections 83A, 83B. In a variant, the electrically conductive element 79 may comprise a co-axial cable (not shown) having inner and outer sections 83A, 83B electrically connected to each other by the loop section 83C. The first and second sections 83A, 83B comprise respective first and second connectors 85A, 85B for connection to the fracture detector 91. As illustrated in Figure 10, the electrically conductive element 79 is severed or interrupted when the shaft portion 43 of the locking pin 3 is fractured. By monitoring the voltage through the electrically conductive element 79, the fracture detector 91 can check the integrity of the locking pin 3. The fracture detector 91 identifies a break or a fracture in the locking pin 3 in dependence on a determination that the measured voltage across the electrically conductive element 79 is zero (i.e., 0V) or less than a predetermined threshold value. The electrically conductive element 79 in the present embodiment is connected in series with the position detector 71. The voltage signal VS(1) input to the electrical input of the controller 53 provides an indication of the voltage across the electrically conductive element 79. If the electrically conductive element 79 is severed or interrupted, the voltage measured by the control system 51 is zero (i.e., 0V). As described herein, the fracture detector 91 in the present embodiment is integrated into the control system 51. The voltage across the electrically conductive element 79 is monitored in dependence on the voltage signal VS(1) input to the controller 53. The fracture detector 91 is configured to determine that the locking pin 3 is fractured if the voltage signal VS(1) indicates that the voltage across the electrically conductive element 79 is zero (i.e., 0V) or is less than a predetermined threshold. The output means 61 of the control system 51 is configured to output a third pin status signal PS(3) configured to indicate that the locking pin 3 is fractured. The third pin status signal PS(3) in the present embodiment is output to the charging controller 21. The charging controller 21 is configured to inhibit or interrupt charging of the traction battery 11 in dependence on a determination that the locking pin 3 is fractured. Alternatively, or in addition, the fracture detector 91 may generate an alert that a fault has been detected in the locking pin 3. It will be understood that the electrically conductive element 79 may be independent of the position detector 71. Figure 11 illustrates a method 100 according to an embodiment of the invention. The method 100 is a method of controlling the charging of a traction battery 11 in a vehicle 13, such as the vehicle 13 illustrated in Figure 1. The method 100 may be performed by the control system 51 described herein. In particular, the memory 57 may comprise computer-readable instructions which, when executed by the processor 55, perform the method 100 according to an embodiment of the invention. The method 100 starts (BLOCK 105). The locking pin assembly 1 is controlled to displace the locking pin 3 to the locked position (BLOCK 110). The locking pin assembly 1 may, for example, be controlled in dependence on a lock request signal CS(1). The locking pin assembly 1 controls the locking pin actuator 23 to displace the locking pin 3 to the locked position. A check is performed to determine that the locking pin 3 is in the locked position (BLOCK 115). I n the above embodiment, the position detector 71 operates to detect the position of the locking pin 3. Other techniques may be used to check that the locking pin 3 is in the locked position. For example, the operating state of the locking pin actuator 23 may be used to provide an indirect indication of that the locking pin 3 is in the locked position. If the locking pin 3 is determined to be in the unlocked position, an alert is generated to indicate that the charging plug 5 is not locked in the charging socket 7 (BLOCK 120). The charging of the traction battery 11 is halted or inhibited in dependence on a determination that the locking pin 3 is in the unlocked position (BLOCK 125). A request to lock the charging plug 5 in the charging socket 7 may optionally be generated (BLOCK 130). If the locking pin 3 is determined to be in the locked position, the process continues. The fracture detector 91 operates to detect a fracture in the locking pin 3 (BLOCK 135). The structural integrity of the locking pin 3 is monitored by measuring a voltage through the electrically conductive element 79. If the measured voltage is greater than zero (i.e., 0V) or greater than a predetermined voltage threshold, the fracture detector 91 determines that the locking pin 3 is intact (BLOCK 140). The charging of the traction battery 11 is enabled in dependence on a determination that the locking pin 3 is intact (BLOCK 145). If the measured voltage is zero (i.e., 0V) or less than the predetermined threshold voltage, the fracture detector 91 determines that the locking pin 3 is fractured (BLOCK 150). The charging of the traction battery 11 is halted or inhibited in dependence on a determination that the locking pin 3 is fractured (BLOCK 155). If the locking pin 3 is determined to be fractured, an alert may optionally be generated to identify the fault (BLOCK 160). It will be understood that the integrity of the locking pin 3 may be checked before or independently of the check to determine the position of the locking pin 3. For example, the integrity of the locking pin 3 may be checked before the locking pin 3 is advanced to the locked position. If the locking pin 3 is determined not to be in the locked position (BLOCK 115), the process may optionally continue to check the integrity of the locking pin 3 (BLOCK 135). This may help to identify a fault condition that may have prevented the locking pin 3 being displaced to the locked position. Figure 12 illustrates a method 200 according to an embodiment of the invention. The method 200 is a method of detecting a fracture in a shaft portion 43 of a locking pin 41 of the type described herein. The method 200 may be performed by the control system 51 described herein. In particular, the memory 57 may comprise computer-readable instructions which, when executed by the processor 55, perform the method 100 according to an embodiment of the invention. The method 200 starts (BLOCK 205). The voltage across (or the current through) the electrically conductive element 79 is measured (BLOCK 210). The structural integrity of the locking pin 3 is monitored by measuring a voltage across (or the current through) the electrically conductive element 79 provided in the shaft portion 43 of the locking pin 39. A check is performed to determine if the measured voltage is greater than zero (i.e., 0V) or greater than a predetermined voltage threshold (BLOCK 215). If the measured voltage is greater than zero or the predetermined voltage threshold, the method comprises determining that the locking pin 3 is intact (BLOCK 220). The method may optionally comprise generating a signal to indicate that the locking pin 3 is structurally intact (BLOCK 225). If the measured voltage is zero (i.e., 0V) or less than the predetermined threshold voltage, the method comprises determining that the locking pin 3 is fractured (BLOCK 230). The method 200 may optionally comprise inhibited or interrupting charging of the traction battery 11 in dependence on a determination that the locking pin 3 is fractured (BLOCK 235). If the locking pin 3 is determined to be fractured, an alert is generated to identify the fault condition (BLOCK 240). The method ends (BLOCK 245). As shown in Figure 13, the electrically conductive element 79 may optionally comprise one or more frangible section 95. The electrically conductive element 79 is illustrated as comprising a frangible section 95. The or each frangible section 95 comprises a localised weakness, for example a section having a reduced thickness. The electrically conductive element 79 is predisposed to break at one or more of the frangible section 95. The inclusion of the one or more frangible section 95 helps to ensure that electrically conductive element 79 is interrupted in the event that the shaft portion 43 is fractured. Alternatively, or in addition, the shaft portion 43 may comprise one or more stress raiser 97. The one or more stress raiser is provided to provide a localised increase in the stresses in the shaft portion 43 in order to promote fracture at or proximal to a predetermined location. The stress raiser 97 may, for example, comprise a localised weakness, for example a localised section of the shaft portion 43 having a reduced width. The shaft portion 43 is predisposed to break at the one or more stress raiser 97. The fracture of the shaft portion 43 is illustrated by a broken (dashed) line in Figure 13. The one or more frangible section 95 and the one or more stress raiser 97 may optionally be aligned with each other, as shown in Figure 13. In the above embodiment, the locking pin assembly 1 and the locking pin 3 are disposed in the charging socket 7 provided in the vehicle 13. Alternatively, or in addition, the locking pin assembly 1 and the locking pin 3 may be disposed in a charging socket 7 provided in the charging station 17. The locking pin assembly 1 and the locking pin 3 may, for example, be provided in the charging station 17 to retain a charging plug 5 provided on the vehicle charging cable 9. This arrangement is illustrated in the charging station 17 shown in Figure 1. Alternatively, or in addition, the locking pin assembly 1 and the locking pin 3 may be disposed in the charging plug 5. The locking pin assembly 1 and the locking pin 3 may, for example, be disposed in a charging plug 5 connected to the vehicle charging cable 9. In the above embodiment, the charging plug 5 is introduced into the charging socket 7 along the first axis X. The locking pin 3 is displaced along the second axis Y to lock the charging plug 5 in position. In a variant, the locking pin 3 may be displaced parallel to the first axis X. The locking pin 3 may, for example, comprise a locking tab which engages a cooperating feature to lock the charging plug 5 in the charging socket 7. A charging plug 5 in which the locking pin 3 is displaced at least substantially parallel to the direction in which the charging plug 5 is inserted into the charging socket 7 is shown in Figure 14 by way of example. The locking pin 3 may comprise a locking tab 99 for engaging a cooperating feature (not shown) in the charging socket to lock the charging plug 5. The locking pin assembly 1 is provided in the charging plug 5 in this embodiment (rather than the charging socket 7). It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. The position detector 71 is provided to determine if the locking pin 3 is disposed in the locked or unlocked position. The position detector 71 in the above embodiment comprises one or more switch S1, S2 and one or more resistor R1-R3. The position of the locking pin 3 is determined in 9 dependence on the resistance of the monitoring circuit 73 which varies depending on the operating state of the first and second switches S1, S2. It will be appreciated that the position detector 71 may utilise different types of sensor to determine the position of the locking pin 3. For example, the position detector 71 may comprise an optical sensor or a Hall-effect sensor. The position detector 71 may directly sense the position of the locking pin 3. Alternatively, one or more switch may be actuated when the locking pin 3 is in the locked position and / or the unlocked position. Alternatively, 5 or in addition, the position detector 71 may monitor an operating state of the locking pin actuator 23 to determine the position of the locking pin 3 indirectly. The second axis Y is illustrated herein as being substantially horizontal. It will be understood that the present invention is not limited in this respect. For example, the second axis Y may extend substantially vertically. Other configurations are contemplated. LABELS FOR BLOCK DIAGRAM 100 Reference Label 105 START 110 LOCKING PIN ACTUATOR(S) OPERATED TO DISPLACE LOCKING PIN TO LOCKED POSITION 115 CHECK IF LOCKING PIN LOCKED 120 GENERATE ALERT INDICATING THAT LOCKING PIN IS NOT IN LOCKED POSITION 125 HALT OR INTERRUPT CHARGING OF VEHICLE 130 OPTIONALLY GENERATE REQUEST TO CONTROL LOCKING PIN ACTUATOR(S) TO LOCK THE LOCKING PIN 135 IF LOCKING PIN IS LOCKED, CHECK INTEGRITY OF LOCKING PIN 140 DETERMINE THAT LOCKING PIN IS INTACT (I.E., NOT FRACTURED) 145 PERFORM CHARGING OF VEHICLE 150 DETERMINE THAT LOCKING PIN IS FRACTURED (I.E., NOT INTACT) 155 HALT OR INTERRUPT CHARGING OF VEHICLE 160 GENERATE ALERT INDICATING THAT LOCKING PIN IS FRACTURED LABELS FOR BLOCK DIAGRAM 200 Reference Label 205 START 210 MEASURE VOLTAGE (OR CURRENT) IN ELECTRICALLY CONDUCTIVE ELEMENT DISPOSED IN LOCKING PIN 215 MONITOR MEASURED VOLTAGE (OR CURRENT) 220 IF MEASURED VOLTAGE (OR CURRENT) IS NON-ZERO OR GREATER THAN A THRESHOLD, DETERMINE THAT THE LOCKING PIN IS INTACT 225 OPTIONALLY GENERATE NOTICATION THAT LOCKING PIN IS INTACT 230 IF MEASURED VOLTAGE (OR CURRENT) IS ZERO OR LESS THAN A THRESHOLD, DETERMINE THAT THE LOCKING PIN IS FRACTURED 235 (OPTIONALLY) INHIBIT OR INTERRUPT CHARGING OF TRACTION BATTERY 240 GENERATE NOTICATION THAT LOCKING PIN FRACTURED 245 END

Claims

1. A locking pin for locking a charging plug in a charging socket to secure a vehicle charging cable, the locking pin comprising: a shaft portion having a proximal end and a distal end; andan electrically conductive element extending at least partway along a length of the shaft portion towards the distal end thereof, the electrically conductive element forming a continuous electrical loop for detecting a fracture in the shaft portion of the locking pin.

2. A locking pin as claimed in claim 1, wherein the first and second sections are electrically connected to each other at the distal end of the shaft portion to form the continuous electrical loop.

3. A locking pin as claimed in claim 2, wherein an electrical insulator is disposed between the first and second sections to insulate the first and second sections from each other along their length.

4. A locking pin as claimed in claim 2 or claim3, wherein at least one of the first and second sections extends from the proximal end to the distal end of the shaft portion.

5. A locking pin as claimed in any one of claims 2, 5 or 4, wherein at least one of the first and second sections comprises one or more frangible section.

6. A locking pin as claimed in any one of the preceding claims, wherein the shaft portion comprises a stress raiser.

7. A locking pin as claimed in any one of the preceding claims, wherein the electrically conductive element is at least partially embeddedin the shaft portion.

8. A locking pin assembly comprising a locking pin as claimed in any one of the preceding claims, and a fracture detector for detecting a fracture in the shaft portion of the locking pin, the fracture detector being connected to the electrically conductive element; wherein, in use, the fracture detector is configured to supply a voltage to the electrically conductive element to detect a fracture in the shaft portion.

9. A locking pin assembly as claimed in claim 8 comprising an actuator for displacing the locking pin between a retracted position and a deployed position, and a position detector for detecting a position of the locking pin; wherein the fracture detector is integrated into the position detector.

10. A charging plug for connection to a charging socket, the charging plug comprising a locking pin assembly as claimed in claim 8 or claim 9, the charging plug comprising one or more electrical pin for connection to a terminal in the charging socket, the one or more electrical pin extending parallel to a longitudinal axis of the charging plug, wherein the locking pin of the locking pin assembly extends parallel to, or perpendicular to, the longitudinal axis of the charging plug.

11. A charging socket for connection to a charging plug, the charging socket comprising a locking pin assembly as claimed in claim 8 or claim 9, the charging socket comprising one or more electrical terminal for connection to an electrical pin in the charging plug, the one or more electrical terminal extending parallel to a longitudinal axis of the charging socket, wherein the locking pin of the locking pin assembly extends parallel to, or perpendicular to, the longitudinal axis of the charging socket.

12. A vehicle comprising a charging plug as claimed in claim 10, or a charging socket as claimed in claim 11.

13. A charging cable for an electrical vehicle, the charging cable comprising at least one charging plug as claimed in claim 10 and / or at leastone charging socket as claimed in claim 11.

14. An electrical vehicle charging station comprising a charging plug as claimed in claim 10, or a charging socket as claimed in claim 11.

15. A fracture detector for detecting a fracture in a shaft portion of a locking pin for locking a charging plug in a charging socket, the lockingpin comprising an electrically conductive element forming a continuous electrical loop in the shaft portion, wherein the fracture detector comprises one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal) and an electrical output for outputting an output signal), the fracture detector comprising at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon, the input signal) providing an indication of a voltage across, or an electric current through, the electrically conductive element, wherein the at least one electronic processor is configured to:receive the input signal) and monitor the electric current through, or the voltage across, the electrically conductive element;determine that the locking pin is fractured in dependence on a determination that the electric current through, or the voltage across, the electrically conductive element is zero or less than a predetermined threshold.

16. A fracture detector as claimed in claim 15, wherein the output signal) is a pin status signal) indicating that the locking pin is fractured, the pin status signal) being output in dependence on the determination that the electric current through, or the voltage across, the electrically conductive element is zero or less than the predetermined threshold.

17. A charging controller for controlling charging of a traction battery disposed in a vehicle, the charging controller being in communication with a fracture detector as claimed in claim 15 or claim 16, wherein the charging controller is configured to inhibit or interrupt charging of the traction battery in dependence on the determination by the fracture detector that the locking pin is fractured.

18. A method of detecting a fracture in a shaft portion of a locking pin for locking a charging plug in a charging socket, the locking pin comprising an electrically conductive element forming a continuous electrical loop in a shaft portion of the locking pin, wherein the method comprises: monitoring the electric current through, or the voltage across, the electrically conductive element;detecting a fracture in the locking pin in dependence on a determination that the electric current through, or the voltage across, the electrically conductive element is zero or less than a predetermined threshold.

19. A method as claimed in claim 18, wherein the method comprises generating a notification that the locking pin is fractured.

20. A method of controlling charging of a traction battery disposed in a vehicle, the method comprising detecting a fracture in the locking pinusing the method claimed in claim 18 or claim 19; and inhibiting or interrupting charging of the traction battery in dependence on detection of the fracture.

Images