Electrical connectors – With coupling movement-actuating means or retaining means in... – Coupling part with relatively pivotable concentric...
Reexamination Certificate
2000-03-17
2002-04-09
Abrams, Neil (Department: 2839)
Electrical connectors
With coupling movement-actuating means or retaining means in...
Coupling part with relatively pivotable concentric...
C439S333000
Reexamination Certificate
active
06368133
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to power tools and, more particularly, to a power cord for power tools.
A power tool, such as a circular saw, generally includes a housing supporting an electric motor which drives a tool element, such as a saw blade. 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-removably fixed to the housing or handle of the power tool.
SUMMARY OF THE INVENTION
One problem with the above-described power tool is that, if the power cord is damaged or accidentally severed during cutting operations, a cord must be rewired to the electrical circuit. In order to rewire the new cord, the handle of the power tool is disassembled and the new cord is 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 is rewired to the severed end of the cord. In either case, rewiring of the power cord is time consuming and inconvenient. Also, 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.
The present invention provides a power cord for a power tool that alleviates the problems with the above-described power tools. The invention provides a power cord that is removable and replaceable. Also, the present invention provides a power cord that can be positively locked to the housing of the 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 present invention provides a power tool including a housing defining a housing thread, an electric motor supported by the housing and operable to drive a tool member, and an electrical circuit connected to the motor. The power tool also includes a power cord connectable to the housing and to the circuit and operable to connect the circuit to the power source. The cord defines a cord thread complementary to and engageable with the housing thread.
The power tool further includes a locking assembly for locking the cord to the housing and to the circuit. The locking assembly includes a first locking member supported by one of the housing and the cord and a second locking member supported by one of the housing and the cord. The first locking member is movable between a locking position, in which the first locking member and the second locking member are engaged, and an unlocked position, in which the first locking member and the second locking member are disengaged.
To connect the cord, the cord is electrically connected to the circuit. The cord is engaged with the housing so that the cord thread engages the housing thread. The first locking member is then moved to the locking position to prevent the cord thread and the housing thread from being disengaged.
Preferably, the first locking member includes a locking projection, and the second locking member is a recess engageable by the locking projection in the locking position. Preferably, the locking member is slidable generally parallel to the axis of the member on which it is supported between the locking position and the unlocked position.
The cord preferably includes a mounting portion is preferably rotatable relative to the cord electrical connector and relative to the support portion to engage the cord thread and the housing thread. Also, the power tool preferably includes an indicator to indicate when the cord is locked to the housing.
In one construction, the first locking member is preferably supported on the support portion, and the second locking member is preferably supported on the mounting portion. In an alternative construction, both locking members of the locking assembly are supported on the cord. In the alternative construction, the first locking member is supported on the mounting portion, and the second locking member is supported on the cord electrical connector housing.
In addition, the present invention provides a method of assembling a power tool, the method comprising electrically connecting the cord and the circuit, engaging the cord and the housing so that the cord thread engages the housing thread, and moving the first locking member to the locking position to engage the second locking member to prevent the cord thread and the housing thread from being disengaged. The cord is thus positively locked with the housing and with the circuit.
One advantage of the present invention is that the power cord is quickly and easily removable and replaceable if the cord is damaged or severed.
Another advantage of the present invention is that the power cord is positively locked to the housing to ensure that the cord is electrically connected to the circuit and to ensure that that cord is physically connected to the housing. Also, in order to remove the cord, the operator must perform two separate and distinct motions. The first locking member must be moved to the unlocked position, and the mounting portion must then be rotated relative to the housing to disengage the threads. This reduces the likelihood of the cord being inadvertently disconnected from the housing.
Yet another advantage of the present invention is that, in the construction in which the both locking members of the locking assembly are supported on the cord, such a cord may be used with a power tool capable of accommodating a removable cord. Such a cord provides a positive locking arrangement without modification of the power tool (i.e., providing one of the locking members on the power tool).
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.
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Hessenberger Jeffrey C.
Marinkovich Dragomir C.
Ottens-Rendon Melissa A.
Zeiler Jeffrey M.
Abrams Neil
Le Thanh-Tam
Michael & Best & Friedrich LLP
Milwaukee electric Tool Corporation
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