FIELD OF THE INVENTION

The present invention relates generally to various solutions for the management of the generation of heat in a retractable cord reel apparatus delivering electrical power. In some embodiments, the invention more is directed to specifically to insuring that the flow of electrical current in a cord which may be partially or fully coiled on a reel does not result in generation of excessive heat which could damage the cord, reduce its useful life, or create danger to the user. Cords used for charging batteries in, for example, electric vehicles, are frequently coiled when not in use to safely store the cord and protect it from the elements and damage.

A retractable cord reel may be part of a charging station in, for example, a parking lot at an airport or in a home or office garage. The charging station may be a post or other suitable structure containing the cord reel and associated circuitry. If used in a public location, storing the cord on a reel helps protect against theft of the cord for its copper, because the charging station can require use of a key card or similar means to allow use of the station.

In some embodiments of the present invention, the cord may be only partially unreeled when used to charge a battery. In other embodiments, the cord may only be partially extended (e.g., through a coiled cable or “curly cord”) that is extended or retracted through a coaxial connector via a reel. Heat generated by the flow of current will not escape as readily from a cord carrying electrical current when the cord is partially or completely coiled or retracted. As the amount of cord on the reel increases, more heat tends to be trapped. Overheating could occur even if the cord is simply looped over a hook, rather than being stored on a rotating reel.

The cord reel assembly described here includes improved features venting heat buildup and/or for limiting the current flow in the cord, with higher currents being permitted if the cord is substantially or fully unreeled, and for sensing the temperature of the reeled cord at one or more locations. Current flow therefore need not be limited to an unnecessarily low value suitable for a cord that is fully coiled. Higher currents, and therefore shorter charging times, are made possible.

BACKGROUND OF THE INVENTION

Retractable cord reels have been used in various applications to retractably store various types of cables. Typically, a reel might have a stationary end and a retractable end, the retractable end capable of extension from and retraction back into the reel, and which can be connected to, for example, a battery in an electric vehicle. Using a reel provides convenient storage for the cord. The reel also protects the cord from damage, since it need not be left on the ground. Damage to the cord is reduced. The hazard presented to a user by a damaged electrical cord is also avoided.

The use of a reel has a disadvantage, because the flow of current generates heat in the cord. A larger current tends to generate more heat. One application is a charging station for an electric vehicle. If the user parks his electric vehicle very close to the charging station, or if the vehicle is small, it may not be necessary to unreel more than a short length of cord sufficient to reach the battery connector on the vehicle. As current flows from the charging station to the vehicle, heat will be generated in the cord. Because most of the cord is coiled on the reel, heat cannot escape as readily, and the cord temperature can rise, possibly to the point where the function of the charging station, or the safety of the user, is jeopardized. An additional factor is the lack of experience or knowledge on the part of many vehicle operators.

Definition of Terms

The following terms are used in the claims of the patent as filed and are intended to have their broadest plain and ordinary meaning consistent with the requirements of the law:

A “retractable cord reel” refers to a cable storage unit and cable management systems having a spooling cord such as the type found in U.S. Pat. No. 5,094,396 to Burke, the subject matter of which is hereby incorporated by reference, and U.S. Patent Application No. 2007/0262185 to Burke, the subject matter of which is also hereby incorporated by reference. Depending upon the embodiment, the reel may coil the charging cable itself, or it may coil a supporting mechanical cord reel.

An electric vehicle means any vehicle, including one propelled solely by a rechargeable battery, and one using hybrid propulsion including a rechargeable battery. The vehicle can further include—but is not limited to—cars, trucks, motorcycles, electrical bicycles and scooters.

Where alternative meanings are possible, the broadest meaning is intended. All words used in the claims set forth below are intended for use in the normal, customary usage of grammar and the English language.

SUMMARY OF THE INVENTION

The present invention relates to one or more of the following features, elements or combinations thereof.

One disclosed embodiment is directed to improvements in a retractable cord reel for battery charging stations, including those used for vehicles propelled at least in part by rechargeable batteries. The charging station includes an electric cord connected to a source of power. An end of the cord has a vehicle connector assembly. Control circuitry regulates the current supplied to the battery being charged. The reel has one or more temperature sensors for determining the thermal buildup in the cord. The control circuitry includes a processor that receives an input signal from one or more of the sensors. The processor issues an output signal that is related to the input signal from the sensor or sensors. The output signal limits the charging current being supplied to the battery, so that the cord does not overheat. Heat generated in the cord is safely dissipated.

In another embodiment, the disclosed apparatus includes a sensor for determining the amount of cord that has been unreeled. As the length of unreeled cord increases, the processor receives an input signal representative of the length of unreeled cord, and issues an output signal increasing the maximum allowable current to the battery being charged.

In still another embodiment, the present disclosure includes a cord reel that spool a mechanical tether is coaxial with the charging cable, which surrounds the tether by virtue of being in a coiled cable or “curly cord” configuration. The charge station further includes venting at its bottom and a channel with opening at the top and the bottom to create a “chimney effect” to dissipate heat and ensure that the power supplies and the air around the power cord and related circuitry remain at or near ambient temperature. Optionally, this embodiment further includes one or more sensors to determine whether the thermal build up in the cord and/or the power supply requires decreasing current supplied to the battery to avoid overheating.

Thus, it can be seen that one object of the disclosed invention is to provide a mechanism for the avoidance of overheating a battery charging station, and in particular the charging cord.

A further object of the present invention is to allow the maximum charging current to be delivered to the battery being charged.

Another object of the invention is to detect damage to the cord, or removal of the cord.

It should be noted that not every embodiment of the claimed invention will accomplish each of the objects of the invention set forth above. For instance, certain claimed embodiments of the invention will not require a temperature sensing device. In addition, further objects of the invention will become apparent based upon the summary of the invention, the detailed description of preferred embodiments, and as illustrated in the accompanying drawings. Such objects, features, and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, and as illustrated in the accompanying drawings.

