Isolated dual AC-DC plug

Various embodiments of the present invention are directed to electrical plug apparatus for selectively connecting a device such as a battery charger, for example, to sources of AC and DC electrical power and comprise a housing, a first connector attached to the housing for connecting to a DC source of electrical power, a second connector attached to the housing for connecting to an AC source of electrical power wherein the first and second connectors are configured to enable only one of the connectors to be used at the same time.

BACKGROUND OF THE INVENTION

The present invention generally relates to electrical connecting devices.

There has been a proliferation of electrical tools and devices that are powered by batteries or can be plugged into common electrical outlets, with the latter capability requiring an AC to DC power conversion device. If a device is essentially DC powered, it may be connected directly to a battery or source of DC power or it may have a converter and be connected to a converter to an AC power outlet.

A common source of DC power is provided by motor vehicles through a cigarette lighter socket receptacle or similar auxiliary receptacle that is connected to the DC battery of the motor vehicle itself. If that type of source is used, a DC plug may be provided to connect a device directly to the socket to power for the device of interest. If it is to be powered by converted AC power, then a common two or three prong plug must be provided which is interconnected to an AC to DC converter for providing the DC voltage necessary to run the device. Many products currently commercially available include multiple devices that can be used for connecting to AC and DC sources, which requires the user to carry both kinds of connectors if they wish to use either type of power source.

It should be appreciated that a device that can be connected to such AC and DC sources should be designed in a manner whereby it is not possible to simultaneously connect both sources to a device for the obvious reason that internal circuitry could be destroyed or significantly damaged. Also, such a condition could present a safety hazard to a user. Plugs have been designed with adjustable configurations that can be used for different types of sockets that are found in different countries of the world, including configurations that are adapted to plug into standard electric AC outlets as well as DC cigarette lighter sockets contained in single housing. All of such known configurations are not designed to be completely foolproof in the sense that they could not be simultaneously connected to AC and DC sources.

SUMMARY OF THE INVENTION

Various embodiments of the present invention are directed to electrical plug apparatus for selectively connecting a device such as a battery charger, for example, to sources of AC and DC electrical power and comprise a housing, a first connector attached to the housing for connecting to a DC source of electrical power, a second connector attached to the housing for connecting to an AC source of electrical power wherein the first and second connectors are configured to enable only one of the connectors to be used at the same time.

DETAILED DESCRIPTION

Various embodiments of an electrical connecting plug are shown which are configured to selectively connect a device, such as a battery charger for power packs of portable tools, for example, to electrical power sources. Such an electrical connecting plug may be connected to a source of DC power as well as an AC source. In the case of connection to an AC source, the connecting plug is typically connected to an AC to DC converter since most power tools are powered with DC motors. While there are commercially available devices having plugs that can be connected to either AC or DC sources, such known devices are not designed and configured to absolutely prevent both of the connectors from being connected to power sources at the same time. In the event that such a condition were to develop, it is highly likely that associated electrical circuitry could be damaged or destroyed. Such a condition could also create a safety hazard to the user or to anyone in the vicinity of the device.

The preferred embodiments that are described herein typically have a cylindrical DC connector of the type that fits within a cigarette lighter socket or similar type of socket that is provided in motor vehicles, boats, and other apparatus, such as portable power generators and the like.

Turning now to the drawings and particularlyFIG. 1, a preferred embodiment of the plug is indicated generally at10and includes a housing12, a box shaped connector body, indicated generally at14, which is pivotable relative to the housing12and includes a DC connector portion16on one end of the body14, and an AC connector portion18located on the opposite end portion and an intermediate pivot portion20, that is located between the DC and AC connector portions16and18.

As is best shown inFIG. 6, the connector body14has the intermediate portion20provided with a pair of generally cylindrical extensions22which fit into apertures (not shown) of the housing12thereby making the body portion14pivotable therein. Each of the extensions22has a number of elongated ridges24that cooperate with a retention structure within the housing12to hold the body in one of its two preferred orientations during use. In this regard, inFIG. 1, the DC connector16is shown extending from the housing adapted to be used by being inserted into a DC receptacle such as a cigarette lighter socket of the type shown inFIG. 9which has a positive connector pad24located in the center of the bottom of the socket recess and a negative preferably metal cylinder26. The receptacle is typically connected to the battery of the motor vehicle or boat or other DC source. An alternative embodiment of the body portion14′ is shown inFIG. 7, which is functionally equivalent to the embodiment ofFIG. 6, except that the shape of the intermediate portion is not box-like, but is cylindrically shaped. Because it is functionally equivalent, it is not described in any detail.

The position of the DC connector inFIG. 1is vertical relative to the housing as shown and it can rotate between this position and a second position as shown inFIG. 2where the DC connector16fits within a recess30and is therefore unusable. However, in this position the AC connector portion18is exposed so that it can be inserted into a conventional electrical outlet31such as that shown inFIG. 8.

As is most clearly illustrated inFIG. 6, the electrical connector18has a pair of prongs32that are configured to connect to the neutral and live conductors of an AC source. The DC connector16has a generally cylindrical elongated portion34with a reduced diameter end portion36from which a positive connector38extends, with the connector16also having one or more side electrodes40that are preferably metallic and flexible or flexibly mounted so that they can retract and extend toward the side of the socket and reliably contact the negative electrode26as shown inFIG. 9.

The housing12preferably has the recess30extending along the top of the housing12as shown inFIG. 1, and also extends along the end30awhere the AC connector18is located. When the DC connector is exposed as shown inFIG. 1, the housing12preferably has a pair of slots42sized to receive the blades or prongs32of the AC connector so that they are substantially retracted or hidden and are unavailable for use. The depth of the slots42can be appropriately sized so that the narrow edges of the blades32will contact the housing and limit rotation of the plug body so that it cannot move past the vertical position as shown inFIG. 1. Similarly, the depth of a portion of the slot30which receives the DC connector16is preferably such that the DC connector16is substantially horizontal as shown inFIG. 2when it is fully retracted.

The blades32of the AC connector portion18are preferably connected to wires46and extend from an opening48in the illustrated near extension22that are then extended by an electrical cord or other suitable conductive arrangement to a device to be connected to. Also, the DC connector portion16is similarly connected to wires50that run through a similar opening in an extension22located on the opposite side of the intermediate portion20for connection to a device to be connected to. It should be understood that there are other paths in which electrical connections may be made than those shown.