Abstract:
A cord set for connecting a vehicle to a power source includes a first cord having a first connector adapted to be selectively connected to the power source and a second cord having a second connector adapted to be selectively connected to the vehicle. In addition, the cord set includes a coupling mechanism that selectively couples the first cord to the second cord. The coupling mechanism includes a first fitting fixedly attached to the first cord having a plurality of projections and a second fitting fixedly attached to the second cord having a plurality of apertures for matingly receiving the projections of the first fitting. The projections engage the apertures to connect the first fitting to the second fitting under normal operation and disengage the apertures to disconnect the first fitting from the second fitting when the cord set is place under a predetermined tensile force.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to power cords and more particularly to an improved connector for a power cord assembly.  
       BACKGROUND OF THE INVENTION  
       [0002]     Many heavy duty trucks include a sleeper cab that provides a driver with a space in which to rest and sleep during regulated hours of service. Such sleeper cabs commonly include household appliances such as televisions, refrigerators, microwave ovens, and heating/air conditioning systems for use by the driver during a typical 10 hour rest period. Each of the appliances require a power source to function and therefore require the driver to provide ample electricity if any of the appliances are to be used.  
         [0003]     Generally speaking, a driver can supply power to cab appliances from three sources. A first power supply is provided through operation of a truck engine such that electrical power is generated via an alternator/battery arrangement. Second, an auxiliary power generator or an auxiliary battery bank with an inverter may be used to power the appliances directly. Finally, the driver can supply power to the truck cab by connecting the cab to an external power source.  
         [0004]     While connecting appliances such as a heater, refrigerator, or television set directly to a truck battery will certainly provide such appliances with a requisite energy supply, doing so will quickly drain the truck battery. Draining the truck battery is obviously not a viable option as the battery is required to start the truck. Furthermore, powering such appliances from a running truck engine is similarly impracticable. In many states, heavy duty truck engines must be turned off within 3 to 5 minutes once the truck begins to idle (i.e., the engine is running, but the truck is at rest). Most laws penalize drivers who allow their truck engines to continue operation after the 5 minute threshold by imposing large fines and other penalties. Therefore, running a truck engine over an extended period of time to power cab appliances is not a viable option for the truck driver.  
         [0005]     Due to the limitations of conventional truck electrical systems and the recent enactment of laws restricting idling time of truck engines in most states, an external power source is a viable option for a truck driver. Thankfully, most states either are starting to provide, or already do provide, such external power sources at truck stops across the country. Therefore, the remaining challenge for the driver is simply connecting the truck cab to the power source.  
         [0006]     Most power sources are disposed adjacent to truck parking spaces such that a driver can connect the truck cab to the power source by using an extension cord in order to provide a constant supply of electricity to the cab. Once the extension cord is firmly attached to the power source, the driver connects the other end of the cord into a receptacle mounted to the truck cab to thereby supply the truck cab with electricity.  
         [0007]     Conventional extension cords adequately provide the truck driver with the ability to temporarily connect an external power source to a truck cab. However, the length of a typical rest period, combined with the frequency of such stops, results in some truck drivers forgetting to disconnect the extension cord from the external power source prior to pulling out of the parking stop. Due to the large electrical capacity of such extension cords (generally capable of connecting to a 120 VAC grid), the connection at both the external power source and at the truck cab is often very secure to prevent against an inadvertent disconnection at either location. The secure connections, while safely connecting the truck cab to the external power source, do not allow for the cord to be easily pulled from either the truck cab or the power source when a driver inadvertently pulls out from a parking space with the extension cord still attached. The result of such an occurrence is damage to either, or both of, the truck cab and the external power source connection points.  
         [0008]     While conventional extension cords adequately provide a truck driver with the ability to supply a constant supply of electricity to a truck cab by connecting the truck cab to an external power source, conventional extension cords suffer from the disadvantage of causing damage to either or both of the truck cab and the external power source if a driver pulls out of a parking space prior to disconnecting the extension cord from the power source and truck cab.  
         [0009]     Therefore, an extension cord incorporating a breakable connector that allows for safe disconnection of power between the truck cab and power source in the event that the truck cab is driven from a parking space with the extension cord still attached at both the truck cab and the power source is desirable in the industry.  
       SUMMARY OF THE INVENTION  
       [0010]     A cord set for connecting a vehicle to a power source includes a first cord having a first connector adapted to be selectively connected to the power source and a second cord having a second connector adapted to be selectively connected to the vehicle. In addition, the cord set includes a coupling mechanism that selectively couples the first cord to the second cord. The coupling mechanism includes a first fitting fixedly attached to the first cord having a plurality of projections and a second fitting fixedly attached to the second cord having a plurality of apertures for matingly receiving the projections of the first fitting. The projections engage the apertures to connect the first fitting to the second fitting under normal operation and disengage the apertures to disconnect the first fitting from the second fitting when the cord set is placed under a predetermined tensile force.  
         [0011]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0013]      FIG. 1  is a side view of a power cord assembly incorporating a connector in accordance with the principals of the present invention;  
         [0014]      FIG. 2  is a side view of the connector of  FIG. 1  in a connected state;  
         [0015]      FIG. 3  is a perspective view of the connector of  FIG. 1  in a disconnected state;  
         [0016]      FIG. 4  is a cross-sectional view of the power fitting of the connector of  FIG. 1  in a connected state;  
         [0017]      FIG. 5   a  is a front view of a cab fitting in accordance with the principals of the present invention;  
         [0018]      FIG. 5   b  is a cross-sectional view of the cab fitting of  FIG. 5   a;    
         [0019]      FIG. 6   a  is a front view of a power fitting in accordance with the principals of the present invention;  
         [0020]      FIG. 6   b  is a cross-sectional view of the power fitting of  FIG. 6   a;    
         [0021]      FIG. 7  side view of the power cord assembly of  FIG. 1  in a connected state and attached to a truck cab and a power outlet; and  
         [0022]      FIG. 8  is a side view of the power cord assembly of  FIG. 1  in a disconnected state and partially attached to a truck cab and a power outlet. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0024]     With reference to the figures, an extension cord assembly  10  is provided and includes a flexible power cable  12 , a power connector  14 , a cab connector  16 , and a breakable connector  18 . The breakable connector  18  is disposed at a predetermined position along the length of the power cable  12 , generally between the power connector  14  and cab connector  16 , as best shown in  FIG. 1 . The breakable connector  18  allows the power cable  12  to transmit electrical power between the power connector  14  and cab connector  16  while concurrently providing for selective disconnection between the power connector  14  and cab connector  16  if a predetermined force is applied to the extension cord  10 , as will be discussed further below.  
         [0025]     The power cable  12  includes cable sections  12   a  and  12   b,  each having a wire  20  encapsulated by a flexible outer cover  22 . The flexible outer cover  22  insulates the wire  20 , thereby protecting the wire  20  from shorting out and allowing for handling of the extension cord  10  when the power cable  12  is carrying current. The power cable  12  of the present invention is designed for connection to a 120 V power source. Therefore, the cable  12  is generally rated for carrying 100-300 volts AC and up to 50 amps of current. While the cable  12  of the present invention is designed for connection to a 120 V power source, it should be understood that the power rating, and thus the size and weight of the cable  12 , can be reduced or enhanced, depending on the particular application and power source to which the cable  12  may be tied. Therefore, while the present invention will be described as associated with a 120 V power source, it should be understood that the connectors  14 ,  16 ,  18  could be adapted and used with a cable of greater or lesser weight and should be considered as part of the present invention.  
         [0026]     Power cable section  12   a  is fixedly and electrically connected to the power connector  14  such that the cable  12   a  extends between the power connector  14  and the breakable connector  18 , as best shown in  FIG. 1 . The power connector  14  is designed to be releasably attached to an external power source  24  ( FIG. 7 ) such that power supplied by the external power source  24  can be transmitted through the cable  12   a.  In operation, a user inserts the power connector  14  into a receptacle  26  of a power source  24  such that the power connector  14  is electrically connected to the source  24 . Once properly attached to the receptacle  26 , the power connector  14  receives electrical power from the power source  24  and transmits the power along the power cable  12   a.    
         [0027]     The cab connector  16  is similarly fixedly and electrically attached to power cable section  12   b,  but is disposed at an opposite end of the power cable  12  from the power connector  14 . Therefore, the power connector  14  and cab connector  16  are disposed at opposite ends of the extension cord  10  with the breakable connector  18  disposed therebetween, as best shown in  FIG. 1 . The cab connector  16  is designed to be releasably connected to a truck cab  28  ( FIG. 7 ) such that power supplied to the extension cord  10  at power connector  14  is transmitted to the truck cab  28  via power cables  12   a,   12   b,  breakable connector  18 , and cab connector  16 , as will be discussed further below.  
         [0028]     The breakable connector  18  is disposed generally between the power connector  14  and the cab connector  16  and serves to transmit electrical power received from the power connector  14  to the truck cab  28  via cab connector  16 . The breakable connector  18  includes a power fitting  30  and a cab fitting  32 , as best shown in  FIGS. 2 and 3 . The power fitting  30  is fixedly and electrically connected to power cable section  12   a  such that the power fitting  30  is electrically tied to the power connector  14 . Similarly, the cab fitting  32  is fixedly and electrically connected to power cable section  12   b  such that the cab fitting  32  is fixedly and electrically connected to the cab connector  16 .  
         [0029]     The cab fitting  32  includes a main body  34  and a number of current-carrying pins  36 . The main body  34  fixedly receives power cable  12   a  and serves to electrically connect the power cable  12   b  with current-carrying pins  36 . In addition, the main body  34  includes a flange  38 , plurality of circumferential ribs  40 , and a series of projections  42 . The flange  38  radially extends from the main body  34  and serves as a stop for engagement with the power fitting  30 , as will be discussed further below. The ribs  40  are generally positioned between the current-carrying pins  36  and the flange  38 , as best shown in  FIG. 3 . The ribs  40  are axially spaced apart from one another and are integrally formed with the main body  34 . The ribs  40  are received by the power fitting  30  such that a weather-proof seal is formed between the power and cab fittings  30 ,  32 .  
         [0030]     The projections  42  are integrally formed with the main body  34  and radially extend therefrom. The projections  42  are spaced apart in a circumferentially equally spaced apart pattern and include an insertion surface  39  and a back surface  41 . A recess  43  is disposed generally adjacent to the back surface  41 , as best shown in  FIGS. 4 and 5   b.  The projections  42 , in combination with the current-carrying pins  36  and axial ribs  40 , serve to releasably attach the cab fitting  32  to the power fitting  30  such that the power cable sections  12   a,    12   b  are electrically connected. The projections  42  are matingly received by the power fitting  30  such that the cab fitting  32  is releasably secured to the power fitting  30 . As shown in  FIGS. 3 and 5   a,  one of the three projections  42  is smaller in size than the other two projections  42 . The smaller projection  42  serves to help a user properly align the cab fitting  32  with the power fitting  30  to ensure an electrical connection having the proper polarity between the power cables  12   a,    12   b.    
         [0031]     The overall number and size of the projections  42  can be altered to tailor a force required to separate the cab fitting  32  from the power fitting  30 . For example, by including a smaller projection  42  and two larger projections  42 , the force required to separate the fittings  30 ,  32  can be reduced when compared to a similar connector having three large projections  42 . While three projections  42  are disclosed, it should be understood that any number of projections, incorporating a plurality of shapes and sizes, could alternately be used to weaken or strengthen the connection between the fittings  30 ,  32 , depending on the particular application of the extension cord  10 . In addition to varying the overall number and size of the projections  42 , the geometry of each projection  42  can be tailored to provide a desired separation force required to disconnect the cab fitting  32  from the power fitting  30 , as will be discussed further below.  
         [0032]     The power fitting  30  includes a main body  44  having a receptacle  46 , electrical sockets  48 , and a series of projection apertures  50  integrally formed therewith, as best shown in  FIGS. 3, 6   a,  and  6   b.  In addition, the power fitting  30  includes a groove  45  disposed adjacent to each aperture  50  and a lock surface  47 . The main body  44  fixedly receives power cable  12   a  and serves to electrically connect the power cable  12   a  with electrical sockets  48 . In addition, the main body  44  releasably receives the cab fitting  32  such that the ribs  40  engage an inner surface  52  of the receptacle  46  and the flange  38  abuts an end surface  54 .  
         [0033]     When the connection between the power and cab fittings  30 ,  32  is made, the insertion surface  39  of the projection  42  engages the groove  45  of the cab fitting  32  to help facilitate insertion of the projection  42  into the aperture  50 . As can be appreciated, the generally sloped nature of the insertion surface  39  cooperates with the recessed groove  45  to help ease insertion of the cab fitting  32  into the power fitting  30  such that less force is required to engage projections  42  with their respective apertures  50 .  
         [0034]     Once the insertion surface  39  has sufficiently traveled along the groove  45 , the back surface  41  of the projection engages the lock surface  47  of the aperture  50  to releasably hold the power fitting  30  and cab fitting  32  together. In this manner, the projection  42  is disposed generally within aperture  50  such that the groove  45  opposes recess  43 , creating a gap  49  therebetween. At this point, a portion of the main body  44   a  extends into the recess  43  such that the end surface  54  engages the flange  38  and the lock surface  47  engages the back surface  41 , as best shown in  FIGS. 5   b  and  6   b.    
         [0035]     Interaction between the inner surface  52  of the cab fitting  32  and the ribs  40  provides a weather-proof seal between the respective fittings  30 ,  32 . In other words, the seal between the power fitting  30  and the cab fitting  32  created through the interaction between the ribs  40  and the inner surface  52  of the receptacle  46  restricts water from reaching a connection between the current-carrying pins  36  and the electrical sockets  48 . At this point, the projections  42  are seated within apertures  50  and flange  38  abuts end surface  54  of the main housing  44  to ensure that the current-carrying pins  36  are fully and matingly received by the electrical sockets  48  to create an electrical connection between power cables  12   a,    12   b.    
         [0036]     The engagement between the power fitting  30  and the cab fitting  32  is designed to withstand a 20 to 40 lb axial force applied to the extension cable  10 . In other words, small forces (i.e., generally less than 20 lbs.) will not cause the projections  42  to disengage the projection apertures  50  and allow the cab fitting  32  to separate from the power fitting  30 . However, if a larger force is applied to the extension cord  10  (i.e., generally greater than 20 lbs.), the projections  42  will compress and disengage the projection apertures  50 , thereby allowing the cab fitting  32  to separate from the power fitting  30 .  
         [0037]     The separation force required to separate the power fitting  30  and the cab fitting  32  can be tailored based on the geometry of both the projections  42  and the apertures  50 . Specifically, to increase the force required to separate the power fitting  30  and the cab fitting  32 , the engagement between the back surface  41  and the lock surface  47  can be increased such that each projection  42  is seated deeper into each aperture  50 . Conversely, to decrease the force required to separate the power fitting  30  and the cab fitting  32 , the engagement between the back surface  41  and the lock surface  47  can be decreased such that each projection  42  only extends partially into each aperture  50 .  
         [0038]     In addition to adjusting the depth of each projection  42 , an angle of back surface  41  can be adjusted such that the force required to separate the power fitting  30  and cab fitting  32  is increased or decreased. For example,  FIG. 4  shows the back surface  41  as having a substantially 90° angle relative to the main body  34 . In this position, the back surface  41  is generally parallel to the lock surface  47 , thereby maximizing the resistance to separation between the power and cab fittings  30 ,  32 . To reduce the separation force, the angle of back surface  41  is simply increased relative to the main body  34 . The angle of the back surface  41  can be adjusted substantially between 90° and 140°, depending on the desired separation force and application of the extension cord  10 .  
         [0039]     In addition to adjustments to the depth of the projections  42  and angle of the back surface  41 , the junction between the groove  45  and the lock surface  47  can be adjusted to increase or decrease the separation force required to separate the power fitting  30  from the cab fitting  32 . Specifically, the depth of the groove  45  can be increased to decrease the separation force or can be decreased to increase the requisite separation force. As shown in  FIGS. 5   a  and  6   a,  each projection  42  can include a generally arcuate surface  51  that engages a mating arcuate surface  53  of aperture  50 . The arcuate surfaces  51 ,  53  improve the ability to align the respective fittings  30 ,  32  and contribute to increasing the required separation force.  
         [0040]     It should be noted that any of the foregoing modifications to the geometry of the projections  42  or apertures  50  can be used independently or in combination to tailor the separation force required to disconnect the power fitting  30  from the cab fitting  32 .  
         [0041]     In the embodiment depicted, approximately half of a force applied to the extension cord  10  is transmitted through engagement between the current-carrying pins  36  and the electrical sockets  48 . The remaining force is transmitted through engagement between the ribs  40  and the receptacle and by the engagement between the projections  42  and the projection apertures  50 . The magnitude of force transmitted through engagement between the pins  36  and the electrical sockets  48  is generally fixed as the size and shape of the pins  36  is typically dictated by the power requirements of the cable  12 . Therefore, because the pin design is usually a constant, and further because the force transmitted by the ribs  40  is relatively small, the design of the projections  42  and projections apertures  50  must be tailored to adjust the ability of the breakable connector  18  to withstand a predetermined axial force.  
         [0042]     With particular reference to  FIGS. 7 and 8 , the extension cord and breakable connector  18  are shown in use with the power source  24  and truck cab  28 . The extension cord  10  is attached at the power source  24  through the interaction between the power connector  14  and the receptacle  26  of the power source  24 . Extension cord  10  is attached to the truck cab  28  via the cab connector  16 , as previously discussed.  
         [0043]     Under normal circumstances, the respective power cables  12   a,    12   b  are electrically connected by the breakable connector  18  through connection of the current-carrying pins  36  and the electrical sockets  48 . Therefore, when the power and cab fittings  30 ,  32  are connected, electrical power is continuously supplied from the power source  24  to the truck cab  28  via extension cord  10 , as shown in  FIG. 4 .  
         [0044]     Prior to moving the truck cab  28 , the extension cord  10  should first be disconnected from the power source  24  and from the side of the cab  28 . To accomplish this task, the power and cab connectors  14 ,  16  are disconnected and the extension cord  10  is stored prior to movement of the truck  28 . However, in the event that a driver forgets to disconnect the extension cord  10  from the power source  24  and truck cab  28 , the breakable connector  18  will prevent damage to the power source  24 , truck cab  28 , or extension cord  10 .  
         [0045]     When a driver moves the truck  28  away from the power source  24  in a direction “X” with the extension cord  10  still connected to the power source  24  and to the cab  28 , the extension cord  10  is placed under tension, as best shown in  FIG. 7 . The tensile force applied to the extension cord  10  is applied generally along the length of the cable  12  and perpendicular to the connection between the power and cab fittings  30 ,  32  as represented by arrow “Y” in  FIGS. 2 and 8 .  
         [0046]     Due to the relationship between the power and cab fittings  30 ,  32 , the breakable connector  18  will disconnect cable  12   a  from cable  12   b  prior to damage being caused to either the power connector  14  or cab connector  16 . Specifically, the cab fitting  32  will separate from the power fitting  30  prior to experiencing a great enough force to cause damage to the power connector  14 , cab connector  16 , or extension cord  10  due to the relationship between the projections  42  and projection apertures  50 , as previously discussed.  
         [0047]     Once the truck cab  28  has sufficiently moved away from the power source  24  such that the force applied to the breakable connector  18  has severed the cab fitting  32  from the power fitting  30 , cable  12   a  will remain connected to the power source  24  and cable  12   b  will remain connected to the cab  28 . At this point, the extension cord  10 , power source  24 , and truck cab  28  have not been damaged due to the efforts of the breakable connector  18 .  
         [0048]     Placement of the breakable connector  18  along the length of the power cable  12  is important in preventing damage to the cable  12   a  once the cab fitting  32  is severed from the power fitting  30 . The breakable connector  18  should be spaced apart from the cab connector  16  a distance to ensure that the cab fitting  32  is not in danger of being run over by the truck  28  once the power fitting  30  is disconnected from the cab fitting  32 . It should be noted, however, that the breakable connector  18  must also be sufficiently spaced apart from the cab fitting  32  to allow the connector  18  to be placed under tension when the truck  28  pulls away from the power source  24  while still connected by the extension cord  10  (i.e., so the force applied to the breakable connector  18  is applied in the direction Y of  FIGS. 2 and 8 ). For most truck cabs  28 , placement of the breakable connector  18  within 1 to 2 feet from the cab connector  16  ensures protection of the connector  18  once the cab fitting  32  is disconnected from the power fitting  30  and proper orientation when a tensile load is applied to the extension cord  10 .  
         [0049]     It should be appreciated that breakable connector  18  is reusable after cab fitting  32  has been separated from power fitting  30 . A user may re-assemble extension cord  10  by simply aligning projections  42  with projection apertures  50  and applying compressive force. Projections  42  will engage projection apertures  50  in a snap-fit arrangement as previously described. Current of a proper polarity will once again flow between power connector  14  and cab connector  16 . The breakable connector  18  is therefore able to securely and releasably attach the truck cab  28  to the power source  24  while concurrently protecting the power source  24 , truck cab  28 , and extension cord  10  if the truck  28  is inadvertently moved away from the power source  24  with the extension cord  10  still attached to the power source  10 .  
         [0050]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.