The present application relates to towing, and particularly to electrical connectors for detachably connecting electrical systems of towing vehicles and trailers (or other towed loads). Common known towing electrical connectors or plugs include 4-flat, 4 way round, 5-flat, 6-way, 7-pin USCAR, SAE J3008 12 pin, and 13-way connectors. For instance, common 4-flat electrical tow connectors include contacts for:
e) a brake power signal wire, typically colored blue, indicative of braking or of braking power to be applied to the towed trailer or towed vehicle brakes.
In common seven way electrical tow connections, contact sets are included additionally for:
The traditional male-female interconnect systems used in these connectors require near-perfect prong/socket alignment to ensure a quality connection and minimize damage potential. Over time and use, the male-female prongs and sockets of such electrical connections can bend, corrode or otherwise degrade, making the electrical connection intermittent or ineffective, or requiring difficult or impossible alignment adjustments of the user. With standard towing electrical connections having at least four different wires being connected, even having a single prong or a single socket out of alignment can prevent connection (or disconnection) from being easily achieved.
One potential solution is disclosed in U.S. Pat. No. 6,478,619, incorporated by reference, which discloses a magnetic assisted plug connection using spring loaded pins within first and second sealing mechanisms. However, the solution of U.S. Pat. No. 6,478,619 requires a complicated wiring assembly process including tightening of set screws onto wires, and the set screws and wires move for each connection and disconnection. Better solutions are needed.
The present invention is an electrical connection for towing which in a sense replaces the sliding relative movement of prongs within sockets with face contact elements which are much more forgiving during connection and disconnection. In many embodiments, the inventive connection is achieved with one or two adapter pieces, which have the face contact elements exposed on one side and have a standard configuration of prongs/sockets on a back side. The adapter piece(s) are plugged onto the standard electrical plug a single time, leaving the face contact elements exposed for repeated connection and disconnection each time the trailer is connected or disconnected from the towing vehicle. A magnetic attraction force is used to pull and hold the face contact elements in electrical connection, such as by magnets insert molded into a housing of the adapter piece(s) immediately adjacent the exposed face contact elements. The preferred housings allow a short twisting rotation of the adapter piece about a longitudinal axis to be used during connection and disconnection.
While the above-identified drawing figures set forth preferred embodiments, other embodiments of the present invention are also contemplated, some of which are noted in the discussion. In all cases, this disclosure presents the illustrated embodiments of the present invention by way of representation and not limitation. Numerous other minor modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention.
The towing-vehicle-side adapter plug 12, at its leading end, has a male-female 4-flat pin connection sized and configured for attachment to the towing vehicle output plug 16. In particular, the towing-vehicle-side adapter plug 12 includes three male metal prongs 24 extending outside of a molded polymer housing 26 in a longitudinal direction for longitudinal insertion sliding forwardly into the three sockets 28 of the towing vehicle output plug 16, as well as one female metal socket 30 extending within the housing 26 for longitudinal sliding around the exposed male prong 32 of the towing vehicle output plug 16. The prongs 24 and socket 30 are fully stationary relative to the housing 26, so the sliding connection motion can be achieved by the user grasping and pushing the housing 26 forwardly relative to the towing vehicle output plug 16. The trailer-side adapter plug 14, at its trailing end, has a male-female 4-flat pin connection sized and configured for attachment to the trailer input plug 18. In particular, the trailer-side adapter plug 14 includes three female metal sockets 34 extending within its molded polymer housing 36 for longitudinal sliding rearwardly around the three male metal prongs 38 of the trailer input plug 18, as well as one male metal prong 40 extending outside of the housing 36 for longitudinal sliding insertion into the female metal socket 42 of the trailer input plug 18. The sockets 34 and prong 40 are fully stationary relative to the housing 36, so the sliding connection motion can be achieved by the user grasping and pushing the housing 36 forwardly relative to the trailer input plug 18. Thus, both the towing-vehicle-side adapter plug 12 and the trailer-side adapter plug 14 include four sockets/prongs 24, 30, 34, 40 in a standard towing electrical configuration which can make male-female pin connections by first coming into contact with corresponding sets of prongs and sockets 28, 32, 38, 42 and then sliding relative movement in the longitudinal direction. While the connection is made, each socket 28, 30, 34, 42 presses inwardly on the corresponding prong 24, 32, 38, 40 as known in the art.
At the interface between the two adapter plugs 12, 14, four spring loaded electrical face contact pins (a/k/a “pogo pins”) 44, each formed of metal, are used opposite four corresponding stationary face contact pads 46 also formed of metal, making face contact and electrical connections therebetween when attached together. Each pin 44 or pad 46 is electrically connected within its housing 26 or 36 to its correspondingly aligned prong 24 or 40 or socket 30 or 34.
Standard spring loaded face contact pins 44 and stationary face contact pads 46, formed of gold over nickel plated brass but allowing a wire connection on their back end, could be obtained from Shenzhen Czx Hardware Electronics Co. Ltd. of Shenzhen, China. The face contact pins 44 and pads 46 of the preferred embodiment require adaptation from standard face contact pins and pads, so the back side of the pins 44/pads 46 is either a male prong 24 or 40 or a female socket 30 or 34 in accordance with the standard 4-flat connection. The preferred spring loaded electrical face contact pins 44 can easily retract a longitudinal distance of about 2 to 5 mm against the internal spring force. It will thus be understood that, when connected as shown in
In the preferred embodiment, the arrangement of spring-loaded pins 44 versus stationary pads 46 mirrors the male/female arrangement of a standard 4-flat, with one of the adapter plugs 14 having three spring-loaded pins 44 and a single stationary pad 46, and the other adapter plug 12 having three stationary pads 46 and one spring-loaded pin 44. As a first alternative, one of the adapter plugs could have four spring-loaded pins (such as one with a female socket back end and three with a male prong back end, to be one-time-pluggable relative to the existing towing-vehicle 4-flat 16) and the other adapter plug could have four stationary pads (one with a male prong back end and three with a female socket back end, to be one-time-pluggable relative to the existing trailer 4-flat 18). As a second alternative, each adapter plug could have two spring-loaded pins and two stationary pads. However, the preferred embodiment, in which every spring-loaded pin 44 has a female socket back end 30 or 34 (four total for the adapter 10) and every stationary pad 46 has a male prong back end 24 or 40 (four total for the adapter 10), requires fewer distinct parts during insert molding manufacture.
In use, the towing-vehicle-side adapter 12 can be plugged into the output plug 16 a single time, and the trailer-side adapter piece 14 can be plugged into the input plug 18 a single time, while the interface between the two adapter pieces 12, 14 can be connected and disconnected multiple times (including hundreds or thousands of times) each time the trailer is hitched to or unhitched from the towing vehicle. Because the spring-loaded pins 44 mate with opposing pads 46 without any sliding of prongs in sockets, there is more offset tolerance during manufacture. There is also much more alignment tolerance when the user makes the electrical connection, which speeds up attaching a trailer to a towing vehicle and reduces the likelihood of damage.
Magnets 50 are preferably used to hold the face contact connection closed. In particular, the preferred embodiment includes four disc magnets 50 (shown in dashed lines in
With two sets of magnets 50 embedded within the plastic, the sum of magnetic attraction forces (at the distance of separation required by the molded plastic) should be equal to the sum of four spring forces in the pogo pins 44 plus the pull force necessary to separate a standard mechanical male-female 4-flat connector pull out. The most preferred magnets 50 are P125AF-N42 nickel (Ni—Cu—Ni) plated Neodymium (NdFeB) or similar rare earth magnets 50, each about ½ inch (12 mm) in diameter and ⅛ inch (3 mm) in width, with the preferred embedded depth of the magnets 50 beneath each contact face of the molded plastic housings 26, 36 being about 0.025 inches (0.6 mm). Alternatively, other types, sizes or shapes of magnets, or other numbers of magnet pairs, can be used. For instance, another preferred embodiment locates two magnets within the plastic of each plug portion, one over the line of face contact pins 44/pads 46 and one under the line of face contact pins 44/pads 46, with each magnet having dimensions of 0.125×0.125×0.75 inches (3×3×19 mm).
The preferred adapter plugs 12, 14 also include an interlock feature, in the preferred embodiment including a pair of tabs 56 on the housing 36 of the trailer-side adapter piece 14 which rotationally slide into a pair of recesses 58 in the housing 26 of the towing-vehicle-side adapter piece 12. The interlock should occur over a rotational twist angle which is less than about 180°, so it can be achieved by the user by wrist movement with one adapter plug 12 or 14 in one hand the and the other adapter plug 14 or 12 in the other hand and without releasing the grasp of either hand on its adapter plug 12, 14. More preferably, the interlock should occur over a rotational twist angle which is less than about 30°, so magnetic attraction between the magnets 50 can cause the force which self-induces the twisting action. In the preferred embodiment, the interlock occurs over a rotational twist angle of about 9°, shown by arrows 60 and the rotational displacement of adapter piece 14 in
If desired, each stationary pad 46 could be encircled by its own protruded circular molded seal, whereas each spring-loaded pin 44 could be encircled by a sunken circular molded seal. Such molded seals help to prevent debris and liquids from interfering with the connections when seated. Further, such seals should be sized relative to each other so as to have a negligible friction force during separation, i.e., substantially all of the force holding the two adapter portions 12, 14 together should be provided by magnetic attraction. However, the preferred embodiment shown omits such molded seals in favor of having a flat, planar interface between the two housings 26, 36 allowing the user to more easily perform twisting to overcome the magnetic attraction between the magnet sets.
The molded portions 26, 36 could also include molded female and male alignment features which allow straight pull separation in the longitudinal direction, but positively interfere to prevent rotational motion between the two molded portions 26, 36 about a longitudinal pull axis as long as the two molded portions 26, 36 are close enough together. Such longitudinal alignment features can be arranged around the periphery of the molded portions and most preferably off the ends of each magnet, with male-female orientations that only allow one orientation of connection about the longitudinal pull axis. Such longitudinal alignment features can greatly reduce the likelihood of inadvertent separation through a twisting force, which could otherwise overcome the magnetic attraction force. However, the preferred embodiment shown omits such longitudinal alignment features in favor of allowing the user to perform twisting to more easily overcome the magnetic attraction between the magnet sets.
The adapter 10 including two adapter plug portions 12, 14 is a consumer-purchased product, installable by the user without performing any wiring operations, and instead performing two one-time-only plug-ins. The user merely plugs the leading side of the towing-vehicle-side adapter plug 12 onto the existing 4-flat 16 of the towing vehicle, and plugs the back side of the other trailer-side adapter plug 14 onto the existing 4-flat 18 of the trailer. Thereafter, the standard 4-flat plugging/unplugging connection has been replaced with a magnetic connection/disconnection interface. With this face contact adapter concept, the user need never perform an unplugging operation, and longitudinal sliding of prongs within sockets is never again necessary.
The adapter concept could alternatively be applied to other types of trailer electrical plug connections, such as 4 way round, 5-flat, 6-way, 7-pin USCAR, SAE J3008 12 pin, and 13-way connectors. As used herein, the depicted 4-flat configuration and each of these other known types of trailer electrical plug connections, are considered “standard” towing electrical configurations which make male-female pin connections by first making contact with corresponding sets of prongs and sockets and then sliding relative movement in the longitudinal direction. For each of these standard towing electrical connections, prongs and sockets line up and make contact (whether any side, towing-vehicle-side or trailer side, provides the socket or the prong depends upon the particular configuration, but all of these standard connections use prongs/sockets) and then are slid together through longitudinal movement established by the length and orientation of the prongs/sockets. The important consideration is that the present invention significantly reduces the frequency of the prong/socket sliding over the life of the towing vehicle and/or trailer, instead using a face contact connection without requiring another prong/socket sliding each time the trailer is connected to and disconnected from the towing vehicle.
The magnetic attraction interface between the two adapter portions 12, 14 provides a quick and stable connection, with no chance of bending of pins or prongs and less chance for corrosion. Whenever the user connects the trailer to the towing vehicle, the user merely brings the two adapter portions 12, 14 together in alignment at a slight twist angle and allows the magnet attraction force to draw and twist the two adapter portions 12, 14 together. When disconnecting the trailer from the towing vehicle, the user merely grasps the two molded portions 26, 36, performs a slight twist and pulls them apart with sufficient force to overcome the magnetic attraction. Once the two molded portions 26, 36 are apart, the interface is easy to clean, further minimizing the likelihood of corrosion. The plug-style back ends never need to be unplugged from either the towing vehicle plug 16 or the trailer plug 18, so even if corrosion should occur on the back ends to fuse the plugs (12 and 16, or 14 and 18) together and make unplugging impossible, the two adapter portions 12, 14 can still be separated when needed to disconnect.
An alternative half adapter plug arrangement (not shown) is basically a reversal of the embodiment of
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. In particular, all of the dimensions and materials, unless included in the claims, are exemplary only.
The present application claims priority from U.S. Provisional Application No. 63/128,478 entitled MAGNETIC FACE-CONTACT ELECTRICAL CONNECTOR FOR TOWING filed Dec. 21, 2020, incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
63128478 | Dec 2020 | US |