Mechanism for locking and fault detection in the electrical vehicle supply equipment cord reel

Abstract

An electric vehicle charging assembly includes a cord reel, a cord reel locking mechanism, and a master control unit for selectively unlocking the cord reel in response to an authorization signal. The electric vehicle charging assembly monitors the rotational position of the cord reel to prevent unauthorized use, and to record or relay information related to the improper use or malfunction of the electric vehicle charging assembly.

Claims

1. An external, Level 1 vehicle charging system comprising: a) An external cord reel subassembly for providing an electrical cord to facilitate an extension of a vehicle connector; b) a ground fault detection mechanism connected to the cord reel subassembly to determine a presence of a fault event; c) a control circuit operatively connected to the detection mechanism for automatically shutting down the external, Level 1 vehicle charging system in an occurrence of a fault event, the control circuit further connected to the external cord reel subassembly for further automatically reinitiating the charging event at a short, predetermined interval; and d) a detection verification circuit for generating a simulated ground fault signal for verifying an operability of the ground fault detection mechanism in connection with a charging event.

2. The external, Level 1 vehicle charging system of claim 1, wherein the ground fault detection mechanism initially determines the presence of a fault event prior to the occurrence of a charging event.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a partially exposed perspective figure of a cord reel subassembly and charger interface connector in an electric vehicle charging station in accord with another preferred embodiment of the present invention;

(2) FIGS. 2a and 2b are perspective figures of a cord reel subassembly mounted to a support for an electric vehicle charging station in accord with one preferred embodiment of the present invention;

(3) FIG. 3 is an exploded view of a vehicle connector with a locking mechanism in accord with a preferred embodiment of the present invention; and

(4) FIG. 4 is a schematic showing the connection in operation between the master control unit and the encoder, the card swipe mechanism, and the first and second solenoids of a preferred embodiment of the present invention.

(5) FIG. 5 is a ground fault detection circuit and self-test mechanism according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(6) As can be seen in FIG. 1, a charging system 10 includes a cord real subassembly 20, a housing 40, and a vehicle connector 60. The housing 40 preferably contains or is otherwise attached to a master control unit (MCU) 50 as detailed in FIGS. 4 and 5, and described in greater detail below. In this embodiment, because the battery is used for propulsion in a vehicle, vehicle connector 60 is constructed in accordance with SAE Surface Vehicle Recommended Practice J1772, SAE Electric Vehicle Conductive Charge Coupler, issued by the Society of Automotive Engineers for electric vehicles. For different applications not involving an electric vehicle, connector 16 need not comply with J1772, and its design can be modified as required by the intended use.

(7) As shown in FIG. 2, the cord reel subassembly 20 preferably includes a series of apertures 22 to enable the spool 24 of the cord reel to be locked into a specific rotational location to the housing 40 or a similar fixed support. The physical locking of the cord reel will be enabled by a solenoid 26 which slidably engages one of the apertures 22 and an encoder 28 which is adjacent to the spool 24. The encoder 28 will read marks 30 on the spool 24 indicating the rotational status of the spool 24, i.e., the degree to which the cord 32 is wound or unwound. The encoder 28 communicated readings of the marks 30 to a MCU 50, as shown in FIG. 4. The MCU 50 provides an authorization signal to the solenoid 26, causing the solenoid 26 to slide through aperture 22 into locked or unlocked positions as desired.

(8) As further shown in FIG. 4, the unlocking of solenoid 26which, in turn, permits or causes the cord 32 to be wound or unwoundmay be initiated by the MCU 50 in response to receiving an authorization signal input from a card swipe device 52, which may be alternative mechanisms including a key fob, phone swipe mechanism and/or similar user authorization interface. The MCU 50 can further compare the input from the encoder 28 with the presence or absence of the authorization signal so as to determine if an unauthorized unwinding of the cord 32 (e.g., vandalism or theft) is taking place. The MCU 50 can, in the instance of such an event, record the time of the event and/or the identity information of the last user so as to determine (potentially) the identity of the vandal or thief. Alternatively, the MCU 50 can communicate the unauthorized use event via a remote communication module 52, such a wifi connection or the like, to a remote service facility so as to enable the repair or replacement of the assembly 10 right away. As a further alternative, the MCU 50 can provide a deactivation signal in the event of an unauthorized use so as to prevent the flow of current through the cord 32.

(9) Those of skill will understand that this system 10 will further account for the presence of malfunctions in the cord reel subassembly 20, such as a malfunction of the spring (not shown) which could be detected by the encoder 28 through the failure of the cord 32 to retract.

(10) As shown in FIG. 5, an alternative embodiment of the present invention further provides a ground fault detection circuit 54, which may be located on the same printed circuit board, or is otherwise operatively connected to or integrated with MCU 50. The ground fault detection circuit 54 provides protection to the user and to the device from dangerous conditions that can arise in the field either externally through an unintended path through which current can flow and at different subassembly levels, such as a failed current transformer 58 or wiring connecting that part to circuitry that resides on a circuit board, or the circuitry itself. A self testing scheme of this entire system provides a guarantee of safety of the above subassemblies. Following a successful test, a higher level of safety and lower overall risk is provided.

(11) In this embodiment, the self test may be accomplished through a command from the Microcontroller unit 50 which sends a pulse signal to a transistor 56 that is connected to a specific resistance value, RSET, and a given power supply 62, e.g., 12V. This voltage and resistance generate a corresponding current that is passed through current transformer 58, as well as amplifier 64, which is the same circuitry used to detect and signal the existence of genuine Ground Fault conditions.

(12) As yet another further alternative feature, the MCU 50 can further provide signals which enable the system 10 to recover from ground fault conditions more readily. Specifically, where a genuine ground fault condition has occurred, e.g., where a ground fault happens while charging the vehicle. In such an instance, the MCU 50 will send a signal opening relay 68 to discontinue charging such that the vehicle coupler or connector 60 will not deliver a charge, so as to preserve the safety of the charging locale. However, simply leaving the circuit open in the event of a transient ground fault condition may create an unintended deleterious effect of stopping the charging event where a user is not in attendance to observe such conditions (e.g., an overnight charge). Thus, in such a situation, it is desirable for the MCU 50 to automatically reinitiate the charging event at a short, predetermined interval by sending a second signal to close the relay 68. Thus, in this alternative embodiment, the MCU 50 automatically avoids any long term disabling of the system 10 because of transient ground fault events.

(13) As a variant of handling transient ground fault conditions, a further alternative embodiment could be provided for the MCU 50 to disable and reengage the system 10 in the event of a transient ground fault condition in the act of connecting the vehicle connector 60 to the vehicle, i.e., at the beginning of the charging process. If a ground fault condition were sensed (via the current transformer 58 described above), the MCU 50 could generate a signal opening the relay 68, while basing the timing for reinitiating the charging process upon disengaging the vehicle connector 60 from the vehicle. That is, rather than having a preset time for reinitiating after detecting the ground fault event or opening the relay, the MCU could sense the vehicle connector 60 being disengaged and time the restart of the ability to charge to some preselected time thereafter.

(14) As a further alternative embodiment referenced in FIGS. 3 and 5, the system 10 can include a second solenoid 66 for locking the vehicle connector 60 to a holder 70 in the absence of an authorization signal, the authorization signal being provided from the MCU 50 in the manner as described above.

(15) When used for charging an electric vehicle, the preferred embodiment of the system described herein is a Level 1 charger, as that functionality is described by the California Air Resources Board and codified in title 13 of the California Code of Regulations, the U.S. 1999 National Electrical Code section 625 and in SAE International standards. Such systems use lower voltage and are therefore less expensive and suitable for use at a home or other locations where 120 volt AC power is readily available. Due to the relatively low voltage, charging times are longer, possibly as much as ten to twelve hours for a full recharge of an electric vehicle battery. However, those of skill will understand that the present invention as defined by the claims covers not only Level 1 chargers, but also chargers designated as (for instance) Level 2 under those same standards.

(16) Card swipe device and remote communication module 52 are connected to MCU 50 which can be programmed by one of skill in the art. One suitable microcontroller for the MCU is an Atmel ATMEGA328P from Atmel Corporation of San Jose, Calif.

(17) While the disclosure is susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and have herein been described in detail. It should be understood, however, that there is no intent to limit the disclosure to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure as defined by the appended claims.