Note: Descriptions are shown in the official language in which they were submitted.
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TOOL HANDLE HEATER
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to heaters in general and in particular to a
method and apparatus for heating a tool handle.
2. Description of Related Art
In the field of construction, many hand tools are required to be utilized at
locations experiencing cold temperatures. Such hand tools commonly have a
handle which may be grasped or otherwise held by a user and a tool or
working and for performing the required tools of function. As a user is
required to grab the handle so as to operate the tool, the hands of an
operator
may be exposed to the cold temperatures. Such cold temperatures may
reduce the operator's ability to properly operate the tool, or may also reduce
the length of time that the operator is able to work with the tool.
One common solution to operating hands tools in cold environments has been
to provide a tent or other heated structure around the work location. Such
solutions are expensive and time-consuming to set up and also limit the
flexibility of the hand tools to be utilized inside such locations. Another
solution to prevent cold hands of an operator has been for the operator to
wear insulated gloves or mittens so as to keep their hands warm during the
operation. It will be appreciated that such gloves may limit the mobility and
dexterity of the users fingers and therefore may compromise the accuracy to
operate the hand tool.
Previous attempts have been made to heat handles of tools or other objects
so as to reduce discomfort on the user. Such attempts however have
commonly applied a heated grip around the handle which includes such
heaters. Disadvantageously these extra grips either increases the size of the
overall handle from the original dimensions thereby making the handle more
difficult to hold or require replacement of the original grip with the heated
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grips. Examples of such solutions may be found in U.S. Patent Nos.
5,735,037 to Ogata and 7,802,812 to Ohishi et al. as well as U.S. Patent
Application Publication No. 2011/0232038 to Miller.
SUMMARY OF THE INVENTION
According to a first embodiment of the present invention there is disclosed an
apparatus for heating the handle of an electric hand tool, the handle having
an
interior wall defining a cavity therein. The apparatus comprises an electric
heating element adapted to be adhered to the interior wall of the handle and
an electrical connection adapted to be electrically connected to an electrical
supply for the tool.
Each electric heating element may be sized to extend around a majority of the
interior wall of the handle. The electric heating element may comprise two
electric heating elements. Each of the two electric heating elements may be
located inside one half of the handle of the tool. The electric heating
element
may comprise a flexible heating element.
The electrical connection may be connected to a switch of the electric hand
tool. The electrical connection may include a temperature controller to
interrupt the electrical connection above a predetermined temperature.
According to a further embodiment of the present invention there is disclosed
an
electric hand tool comprising a tool body having a handle therein, the handle
having an interior wall defining a cavity therein and an electrical supply
input
cord operable to be connected to a power source. The electric hand tool
further comprises an electric heating element adapted to be adhered to the
interior wall of the handle and an electrical connection adapted to be
electrically connected to an electrical supply for the tool.
The interior wall of the handle may include a recessed portion sized to
receive
the electric heating element therein. Each electric heating element may be
sized to extend around a majority of the interior wall of the handle. The
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electric heating element may comprise two electric heating elements. Each of
the two electric heating elements may be located inside one half of the handle
of the tool.
The electric heating element may comprise a flexible heating element. The
electrical connection may be connected to a switch of the electric hand tool.
The electrical connection may include a temperature controller to interrupt
the
electrical connection above a predetermined temperature.
Other aspects and features of the present invention will become apparent to
those ordinarily skilled in the art upon review of the following description
of
specific embodiments of the invention in conjunction with the accompanying
figures.
BRIEF DESCRIPTION OF THE DRAWINGS
In drawings which illustrate embodiments of the invention wherein similar
characters of reference denote corresponding parts in each view,
Figure 1 is a perspective view of an electric hand tool.
Figure 2 is a cross sectional view of the electric hand tool of
Figure 1 as
taken along the line 2-2 having an electric heating element therein.
Figure 3 is an exploded view of the electric hand tool of Figure 1
at an
intermediate step of installing the electric heating element.
Figure 4 is a cross sectional view of the electric hand tool of
Figure 1 as
taken along the line 2-2 having an electric heating element therein
according to an alternative embodiment.
Figure 5 is an illustration of a wiring diagram for the electric
hand tool of
Figure 1 having the electric heating element therein.
DETAILED DESCRIPTION
Referring to Figure 1, an electric hand tool according to a first embodiment
of
the invention is shown generally at 10. As illustrated in Figure 1, the
electric
hand tool 10 may comprise an angle grinder although it will be appreciated
that any other electric tool may also be utilized, such as by way of non-
limiting
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example, a drill, saw, impact driver, sander or the like. The electric hand
tool
includes a handle 12 and a power cord 14. As illustrated, the electric hand
tool 10 may also include an on/off switch 16 or a trigger to activate the
tool. In
operation, the power cord 14 is plugged into a power supply as is commonly
5 known and the user may then press the trigger or otherwise turn the
on/off
switch on to activate the power tool.
Turning now to Figures 2 through 4, a cross section of the handle 12 of the
electric hand tool is illustrated. The handle 12 has an inner surface 18
10 defining a central cavity 20 therein. The inner surface 18 includes an
electric
heating element 30 disposed on the inner surface 18 to provide heat thereto.
As illustrated in Figure 3, the inner surface 18 may include a recessed
portion
24 in which a portion of the handle 12 has been removed so as to provide a
mounting location for the electric heating element 30. It will be appreciated
that as much material from the handle 12 may be removed as is possible so
as to improve heat flow through the handle wall to the user's hand on the
outside thereof while still maintaining structural integrity of the handle 12.
Optionally, the cavity may thereafter be filled with spray in foam or other
insulating material to prevent contact between and electrical supply or
control
wire and the electric heating element 30.
As illustrated in Figure 3, the tool 10 may be assembled by separating the
first
and second halves 12a and 12b from each other and thereafter forming the
recessed portion 24 into the inner surface thereof by any known means, such
as, by way of non-limiting example, machining, abrading etching or the like.
Thereafter the electric heating elements 30 may be secured within the
recessed portions 24 and secured therein through any known method, such
as, by way of non-limiting example, adhesives, fasteners or the like.
Turning now to Figure 4, the electric hand tool 10 may optionally be formed of
a unitary casing. Although a single electric heating element 30 is illustrated
in
Figure 4, and two electric heating elements 30 are illustrated in Figure 2, it
will
be appreciated that other quantities of electrical heating elements may be
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utilized as well. In such applications the electric heating element 30 may be
rolled smaller than the cavity and a layer of adhesive applied to the rear
thereof such that the electrical heating element may then be inserted into the
cavity and allowed to adhere to the inner surface 18 of the handle.
The electric heating element 30 may comprise any suitable resistive heating
element operable to be formed to the interior of the handle 12. In particular,
it
has been found that silicone rubber heaters or polyimide, such as, by way of
non-limiting example, manufactured under the trademark Kapton have been
useful although it will be appreciated that any other heater, such as, by way
of
non-limiting example, polymer thick film heaters and mica heaters may be
useful as well.
Turning now to Figure 5, an electrical circuit diagram is illustrated for use
in
the providing an electric heating element 30 to the handle 12. As illustrated
in
Figure 5, the electric hand tool 10 will commonly include a switch 16 and an
electric motor 15 operable to receive electricity from a power supply 8, such
as, by way of non-limiting example, through the power cord 14. The electric
heating element 30 may be electrically connected to the switch 16 in common
with the electric motor 15 so as to be activated at the same time thereas. The
electric hand tool 10 may also include a bimetallic strip 40 in series
connection with the electric heating element 30 so as to be operable to permit
operation of the electric heating element 30 when the interior of the handle
12
is below a predetermined set point, such as, by way of non-limiting example,
approximately 120 degrees Fahrenheit although it will be appreciated that
other temperatures may be useful as well. The bimetallic strip 40 may be
located within the cavity 20 or may optionally be secured to a portion of the
electric hand tool casing to measure the temperature thereof. The bimetallic
strip 40 may also be secured to or under the electric heating element 30.
Bimetallic strip 40 prevents the operation of the electric heating element 30
above the desired temperature to avoid heating the users hand during warm
weather or to prevent damage to the electric hand tool due to overheating.
Although a bimetallic strip 40 is illustrated and set out above, it will be
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appreciated that other temperature control switches may also be utilized such
as, by way of non-limiting example, thermocouples and the like. By way of
non-limiting example, a separate heater engagement switch 42 may be
utilized.
While specific embodiments of the invention have been described and
illustrated, such embodiments should be considered illustrative of the
invention only and not as limiting the invention as construed in accordance
with the accompanying claims.
