Patent Publication Number: US-7722377-B2

Title: Power connection system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/071,787, filed May 16, 2008. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to power tools and, more particularly, to a power connection system having a power cord that is interchangeable among a variety of power tools. 
   2. Description of the Related Art 
   A power tool generally includes a housing with an electric motor disposed therein, the electric motor driving a tool element, such as, e.g., a reciprocating sanding member. The motor is electrically connected to an electrical power source by a power cord. Typically, the power cord is directly wired to the electrical circuit of the motor, such as to the on/off switch, and is non-irremovably fixed to the housing or handle of the power tool. 
   One problem with the above-described power tool is that, if the power cord is damaged or accidentally severed during operations, a cord must be rewired to the electrical circuit. In order to rewire the new cord, the handle of the power tool must be disassembled so that the new cord can be directly wired to the on/off switch. Alternatively, if a sufficient length of the damaged cord is still connected to the power tool, a new plug can be rewired to the severed end of the cord. In either event, rewiring of the power cord is time consuming and inconvenient. Moreover, suitable cords and plugs may not be readily available at a work site for replacement of or attachment to the damaged cord. 
   Another problem with the above-described power tool is that, occasionally, an operator will suspend the power tool by the cord. If the cord is not properly and securely connected to the power tool, the body of the power tool can separate from the cord and fall, possibly injuring another worker or damaging the power tool. Moreover, a non-universal power connection system is generally limited to a specific tool and does not facilitate interchangeability of a power cord with other tools. 
   Thus, a power connection system solving the aforementioned problems is desired. 
   SUMMARY OF THE INVENTION 
   The power connection system provides a base and a removably connectable, replaceable power cord. The power cord can be positively locked to the base in the housing of a power tool to prevent the power cord from being inadvertently disconnected from the electrical circuit and from the housing of the power tool. 
   In particular, the power connection system is useful for a power tool in which the power tool has a housing defining a recess, a plurality of electrical connector guide grooves, a plurality of arcuate electrical prongs disposed in the recess, an electric motor supported by the housing and operable to drive a tool member, and an electrical circuit connected to the motor. The power cord has a receptacle having complementary arcuate slots for receiving the prongs when connected to the base defined in the power tool housing, the slots being connected to power cord wires with a plug that can be inserted into an A.C. outlet to provide power to the tool. Advantageously, the power cord is quickly and easily removable and replaceable if the cord is damaged or severed. Moreover, the power cord is interchangeable with other power tools having the base, which is a universal adaptation for the cord. 
   These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an environmental side view of a power tool having a power connection system according to the present invention. 
       FIG. 2  is a front view of a receptacle portion of a power connection system according to the present invention. 
       FIG. 3  is an environmental top view of a power tool having a power connection system including an attached power cord. 
       FIG. 4  is a front view of a power tool equipped to receive a cord of the power connection system according to the present invention. 
       FIG. 5  is a side view of a power tool having a power connection system according to the present invention, including an alternative cord locking feature. 
       FIG. 6  is a partially exploded, perspective view of a power tool equipped to receive a power cord of the power connection system according to the present invention. 
   

   Similar reference characters denote corresponding features consistently throughout the attached drawings. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The power connection system provides a power cord and base removably connectable to each other. The power cord can be positively locked to the base, which is defined in a housing of a power tool, to prevent the power cord from being inadvertently disconnected from the electrical circuit and from the housing of the power tool. 
   In particular, the cord and base provide a power connection system for a power tool in which the power tool has a housing defining a recess and a plurality of electrical connector guide grooves, an electric motor disposed in the housing and operable to drive a tool member, and an electrical circuit connected to the motor. The power cord is connectable to the base defined in the housing and operable to connect the tool to an A.C. power source. The power cord is quickly and easily removable and replaceable if the cord is damaged or severed. Moreover, the power cord is interchangeable with other power tools equipped having a universal base adapted for the cord. 
   A power tool, including a curved prong adaptor and removable power cord  10  embodying the invention, is illustrated in  FIGS. 1-4 . In the illustrated construction, the power tool may be any type of tool  14 , such as a sander, a drill, reciprocating saw, or the like. 
   The power tool  14  includes a motor housing having a handle portion  15   a . An electric motor is disposed in the housing of tool  14  and is operable to drive a tool member, such as a sanding member, drill, or saw. The motor can be electrically connected by an electrical circuit to an on/off switch disposed on the tool  14 . The circuit includes arcuate electrical connecting prongs  30  defined in the base for connection with the power cord C. 
   A recessed portion  15   b  of the handle portion  15   a  defines the base, which provides an enclosure for the arcuate electrical connecting prongs  30 . The recessed portion  15   b  supports the power cord C when the power cord C is connected to the housing  14 . The power cord  10  includes a plurality of wires, preferably including a hot wire, a neutral wire, and a ground wire having, for example, a conventional three-prong plug P at one end and a clamshell-shaped receptacle  50  at the opposite end, the wires being disposed in an insulated jacket. The tool  14  includes a plurality of electrical connector guide grooves  40   a , which mate with complementary ridges  40   b  disposed on the powerhead, i.e., clamshell receptacle  50 . 
   The clamshell receptacle  50  of power cord C includes an electrical receptacle having arcuately curved slots  35  having contacts electrically connected to the conductive wires of the cord C. The arcuately curved slots  35  are designed to receive the arcuately curved prongs  30  as the clamshell receptacle  50  is snapped onto and pivoted into the recess  15   b  in the handle portion  15   a  of power tool  14  to provide the tool with electrical power. 
   The clamshell receptacle  50  has a pivotal joint  25  that engages pivot bar  20  of tool handle portion  15   a . Complementary grooves  40   a  and  40   b  laterally constrain clamshell receptacle  50  as it pivots into the tool  14 . Clamshell receptacle  50  and recess  15   b  also have sets of complementary eyelets  55   a  and  55   b , respectively. During a connecting procedure by a user, clamshell receptacle eyelets  55   a  are aligned with tool handle eyelets  55   b  and secured by lock pin  48 , the lock pin  48  being pushed into the aligned eyelets  55   a  and  55   b.    
   As shown in  FIG. 5 , alternative pivotal joint  525  of receptacle/power head  50  may be a crescent-shaped, concave member that can directly contact cylindrical pivot bar  20  of tool handle portion  15   a , rather than hooking around the bar  20  as the aforementioned pivotal member  25  does. Moreover, alternatively to alignment eyelets  55   a  and  55   b , removable power head member  50  may have a substantially C-shaped hook  550   a  that removably locks into complementary rectangular head  550   b  of lock pin  551 . Lock pin  551  is slidable along its axis within recess  15   b . A cavity inside the recess  15   b  allows the lock pin  551  to slidably engage or disengage the head  550   b  of pin  551  with hook  550   a  to lock and alternatively unlock the removable receptacle  50  from the recess portion  15   b  of tool  14 . 
   As shown in  FIG. 6 , the removable power cord system  10  may be packaged as a retrofit unit  602  that can be attached to a power tool  614 . Power supplying leads  650   a  are electrically connected (via pig tailing, crimping, soldering, circuit board leads, or any other method known by a person having ordinary skill in the art) to power receiving leads  650   b  of power tool  614 . The retrofit unit  602  can be secured to the tool  614  by any means known to persons having ordinary skill in the art. As shown in  FIG. 6 , the retrofit unit  602  is secured to the tool  614  by retaining collars  600 , which are held together by fasteners F. 
   The power cord C may be easily removed and replaced if damaged during cutting operations. Also, the power cord C is positively locked to the power tool to ensure a conveniently removable electrical and physical connection  10  of the power cord C and the power tool  14 . 
   It will be understood that the arcuate prongs may extend from the power cord and the arcuate slots may be defined in the power tool housing, if desired. 
   It is to be understood that the present invention is not limited to the embodiment described above, but encompasses any and all embodiments within the scope of the following claims.