Note: Descriptions are shown in the official language in which they were submitted.
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PNEUMATIC FASTENER DRIVING SYSTEM
WITH SELF-CONTAINED GAS SOURCE
Field of the Invention
This invention relates to pneumatic tools. In particular, this invention
relates to a self contained pneumatic fastener driving system.
Background of the Invention
A pneumatic fastener driver, commonly known as a "nail gun" or "air
miler," is very useful for jobs require the driving of a large number of
fasteners or the
driving of fasteners in tight places where there is insufficient clearance to
swing a
hammer.
A typical pneumatic fastener driving tool has a drive head affixed to a
fastener magazine having a spring-loaded feeder that feeds nails or brads to a
fastener
outlet. The drive head contains a pneumatic cylinder containing a piston that
has a
shaft or "driver blade" aligned with the fastener outlet. The cylinder is in
communication with an air compressor, through a valve actuated by a trigger.
When
the trigger is depressed the cylinder is momentarily pressurized, driving the
piston
shaft against the fastener head to in turn drive the fastener into a
workpiece, for
example a piece of wood.
Typically the source of compressed gas for actuating the pneumatic
2o fastener driving tool is an air compressor, and the tool is connected to
the air
compressor by a hose. The primary disadvantage of connecting the tool to a
compressor using a hose is that the hose is limited in length, thereby
restricted the
distance between the tool and the air compressor. Accordingly, the compressor
must
always be within a certain distance of the pneumatic fastener driving tool.
Moreover,
the hose is subject to wear and tear by being dragged about during use, and
can form a
tripping hazard at a work site.
In some situations, for example where work needs to be done on the soffit
of a house, either the pneumatic hose must be long enough to permit the
extension of
the tool to the desired location, for example to the top of an extension
ladder, or the
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compressor must be elevated to allow the pneumatic fastener driving tool to
reach the
desired position. A long pneumatic hose can be unwieldy, rendering it
difficult to
manipulate the tool. On the other hand, an air compressor capable of driving
such a
tool is typically fairly heavy and therefore awkward to carry and/or support
above the
ground, and also requires an electrical power supply to operate. Moreover,
where the
job requires the application of fasteners over a long distance the compressor
must be
moved along as the user progresses, which can be cumbersome and inefficient.
It would accordingly be advantageous to provide a self contained gas-
driven fastener driving tool. Combustion gas-powered fastener driving tools
have been
proposed, for example that described and illustrated in U. S. Patent No.
4,483,474
issued November 20, 1984 to Nikolich, which is incorporated herein by
reference.
Such self contained tools provide a chamber or reservoir for containing a
combustible
gas. Air is drawn from outside the tool and mixed with the gas in the
cylinder, and
ignited to drive the piston and thus the fastener. However, such devices are
complex
and the hand-held portion is heavy, requiring what is effectively a self
contained
combustion engine in order to drive the fastener. This is in contrast to a
compressor-
driven pneumatic fastener driving tool, which has relatively few moving parts
in the
hand-held portion and is accordingly lighter and easier to manipulate and
maintain.
It would accordingly beneficial to provide a self contained pneumatic
2o fastener driving tool that is simple and lightweight, without the complex
mechanical
construction required for a combustion gas-powered fastener driving tool.
Summary of the Invention
The present invention provides a self contained pneumatic fastener driving
system comprising a fastener driving tool that operates from a compressed gas
canister
and a local holder for mounting the gas canister in proximity of the tool. The
gas
canister is either connected to the tool by a short pneumatic hose, which is
light and
easy to manoeuvre, or in some preferred embodiments integrated into the
driving tool
itself. The gas canister provides a source of compressed gas sufficient for
hundreds of
strokes having the required percussive force to drive a large brad, while not
suffering
3o from the constraints of attachment to a bulky air compressor.
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In embodiments of the invention the gas canister, for example a carbon
dioxide (C02) bottle, may be mounted alongside a handle of the fastener tool,
or
through the handle of the fastener tool, or may be mounted directly to the
drive head
of the tool such that the gas canister itself serves as a handle for the tool.
According to another embodiment of the invention a compressed gas
canister is coupled to a short pneumatic hose that is in turn coupled to the
pneumatic
fastener driver. The gas canister is preferably secured to a belt or other
device which is
mounted on or attached to the user. The tool belt or other canister holding
device may
be expandable, to allow for canisters of different sizes and types to be
secured to the
user.
The fastener driving tool of the invention accordingly provides a self
contained, lightweight and easy to manipulate fastener driver that can drive
hundreds
of fasteners before the gas canister needs to be changed or recharged. These
and other
advantages of the invention will become apparent from the description which
follows.
The present invention thus provides a pneumatic fastener driving system,
comprising a fastener driving tool having a fastener magazine for feeding
fasteners to
a fastener outlet and a drive head comprising a pneumatic cylinder containing
a piston
having a driver blade aligned with the fastener outlet and actuated by a valve
for
momentarily pressurizing the cylinder to drive a fastener, a gas canister, and
a local
holder for mounting the gas canister in proximity of the tool, wherein when
the gas
canister is charged and coupled to the tool the cylinder is pressurized when
the valve
is actuated.
The present invention further provides, in combination, a fastener driving
tool having a fastener magazine for feeding fasteners to a fastener outlet and
a drive
head comprising a pneumatic cylinder containing a piston having a driver blade
aligned with the fastener outlet and actuated by a valve for momentarily
pressurizing
the cylinder to drive a fastener, a gas canister, and a local holder for
mounting the gas
canister in proximity of the tool, wherein when the gas canister is charged
and coupled
to the tool the cylinder is pressurized when the valve is actuated.
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The present invention further provides a kit of parts for a pneumatic
fastener driving system, comprising a fastener driving tool having a fastener
magazine
for feeding fasteners to a fastener outlet and a drive head comprising a
pneumatic
cylinder containing a piston having a driver blade aligned with the fastener
outlet and
actuated by a valve for momentarily pressurizing the cylinder to drive a
fastener, a gas
canister, and a local holder for mounting the gas canister in proximity of the
tool,
wherein when the gas canister is charged and coupled to the tool the cylinder
is
pressurized when the valve is actuated.
Brief Description of the Drawings
1o In drawings which illustrate by way of example only a preferred
embodiment of the invention,
Figure 1 is a partially cutaway elevation of a first embodiment of the
pneumatic fastener driving tool according to the invention, in which the
canister is
affixed to the head of the driving tool,
15 Figure 2 is a perspective view of a further embodiment of a pneumatic
fastener driving tool according to the invention, in which the canister is
secured to a
tool belt and affixed to the tool by a hose.
Figure 3 is a perspective view of a canister holder for the tool belt of
Figure 2.
2o Figure 4 is a perspective view of a fastener tool holder for the tool belt
of
Figure 2.
Figure 5 is a perspective view of a further embodiment of the fastener
driving system of the invention, in which the canister is affixed directly to
the tool
alongside the tool handle.
25 Figure 6 is a perspective view of a further embodiment of a fastener
driving system of the invention, in which the canister is affixed directly to
the tool to
serve as the tool handle.
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Detailed Description of the Invention
The fastener driving tool 10 of the invention will be described in the
context of a nail driver or "nail gun" for driving nails or brads. It will be
appreciated
by those skilled in the art that the fastener driver could equally be a staple
gun, roofing
gun or any other hand-held tool that drives a fastener, and the invention is
not limited
to the particular fastener driving tool 10 so described.
Figure 1 illustrates a first preferred embodiment of the invention. A hand-
held pneumatic fastener driving tool 10 has a drive head 20 affixed to a
fastener
magazine 14 having a spring-loaded feeder 16 that feeds nails or brads 2 to a
fastener
outlet 18. A handle 12 is affixed between the drive head 20 and the magazine
14,
creating a stable, unitary construction that maintains the drive head 20 in
proper
alignment with the magazine 14. The pneumatic cylinder 22 contains a piston 24
mounted in a bearing 26 for axial reciprocation within the cylinder 22 and
affixed to a
shaft or "driver blade" 28 which is aligned with the fastener outlet 18. The
cylinder 22
is in communication with the air inlet 21 through a valve 30 actuated by a
trigger 32,
such that when the trigger 32 is depressed the valve 30 is momentarily opened
to
momentarily pressurize the cylinder 22, driving the driver blade 28 against
the head of
the fastener 2 and thus in turn driving the fastener 2 out of the fastener
outlet 18 and
into a workpiece (not shown), for example a piece of wood. For safety reasons
often
2o the trigger 32 includes a secondary actuator which must be depressed to
enable the
trigger valve 30, for example a depressible nose 19 projecting from the
fastener outlet
18, which ensures that the driving tool 10 will only operate when the fastener
outlet
18 is safely pressed against a workpiece, as is conventional.
In the preferred embodiment of the fastener driving system of the invention
illustrated in Figure 1, the threaded neck 61 of a gas canister 60 is coupled
to the head
20 via a local canister holder comprising a complementary threaded female
receptacle
23 that is in communication with a regulator valve 112, provided in the drive
head 20
between the cylinder gas inlet 21 and the coupling for the canister 60. The
trigger
valve 30 is interposed between the regulator valve 112 and the inlet 21.
Optionally a
pressure gauge (not shown) can be provided in the head 20, although the
desired
pressure (which determines the degree to which the fastener is set in the
workpiece)
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can be easily attained by test firing brads 2 into the workpiece and
increasing or
decreasing the pressure as required to achieve the desired set depth.
The gas canister 60 may be any suitable compressed gas canister, for
example a rechargeable carbon dioxide (C02) bottle which is preferred because
it is
readily available, provides a relatively constant pressure until it is almost
empty, and
is inexpensive to refill.
In the operation of the embodiment of Figure 1, the user inserts a charged
gas canister 60 through the handle 12 and attaches the threaded neck 61 to the
complementary threaded receptacle 23 in the head 20. The user sets the
pressure via
1o regulator valve 112 and can thereafter use the tool 10 in the conventional
manner.
When the safety nose 19 is pressed against a workpiece and the trigger 32 is
manually
depressed, the trigger valve 30 opens momentarily to allow a burst of gas from
the
canister 60 into the cylinder 22. The pressurization of the cylinder 22 forces
the piston
24 to drive the driver blade 18 against the brad 2 (or nail, staple or other
fastener),
15 which in turn drives the brad 2 into the workpiece.
A further embodiment of the invention is illustrated in Figure 2. The
pneumatic cylinder 22 is in communication with an air inlet 40, typically
disposed at
the rear of the handle 12 and typically providing a male coupler end 42 of a
quick-
release connector.
2o A pneumatic hose 50 is provided having a female end 52 for coupling to
the male coupler end 42 of the tool 10 and a male coupler end 54 for
connection to a
gas canister 60. In this embodiment the gas canister 60 is preferably coupled
(typically
by a threaded connection about the canister neck 61 ) to a regulator head 62
having a
pressure regulator valve 63 for regulating the pressure of gas fed to the tool
10 (which
25 determines the driving power and therefore the depth to which the nail or
brad is
driven), a pressure gauge 64, and a female coupler end 66 of a quick-release
connector
for attachment to the male coupler end 54 of the hose 50.
The fastener driving system of the invention provides a local holder for
mounting the gas canister in proximity of the tool. In the first preferred
embodiment
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the gas canister 60 is preferably mounted in a canister holder portion 72 of a
tool belt
70. The canister holder portion 72, illustrated in Figure 3, comprises slots
74 through
which a belt 7I passes, a sheath or holster 76 comprising horizontal straps
76a affixed
by a vertical strap 76b for supporting the canister 60, and a pair of U-shaped
braces 78
for stabilizing the regulator head 62 when the canister 60 is mounted to the
tool belt
70.
Preferably the tool belt 70 also provides a tool holder 80 for stowing.the
tool 10, illustrated in Figure 4. The tool holder 80 comprises slots 82
through which
the belt 71 passes, a support bracket 84 which supports the handle 12 of the
tool 10,
1o and a detachable strap 86 for attachment to the bracket 84 (for example by
mating
grommet portions 86a and 86b) to secure the tool 10 in the holder 80. In the
preferred
embodiment a trigger lock 88 is movably secured to the bracket 84 in a
position which
blocks the trigger 32 from being depressed while the tool 10 is in the holder
80.
In the operation of the embodiment of Figure 2, the user threads a regulator
15 head 62 to a charged gas canister 60 and couples the male coupler end 54 of
the hose
50 to the female coupler end 66 of the regulator head 62. The female coupler
end 52
of the hose 50 is connected to the male coupler end 42 at the air inlet 40 of
the tool 10.
The belt 71 is threaded through the canister holder 70 and the tool holder 80
and
secured to the user. The canister 60 is mounted into the holster 76 and the
tool 10 is
2o mounted to the holder 80 and secured by the strap 86. The user sets the
pressure via
regulator 72 and can thereafter use the tool 10 in the conventional manner,
replacing it
in the holder 80 when finished.
A small (for example 9 ounce) gas canister 60 provides hundreds of
strokes before requiring recharging. Preferably the holster 70 is expandable,
for
25 example being made from an elastic material or fabric fastener strips such
as Velcro
(trademark), to allow for gas canisters of different sizes to be securely
mounted into
the holster 70.
In a further embodiment of the invention, illustrated in Figure 5, the gas
canister 60 is coupled to a regulator head 90 having a regulator valve 92 and
a
30 pressure gauge 94, which provides a return coupler 96 for connection
directly to the
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male coupler end 42 at the air inlet 40 of the tool 10. The local holder for
mounting
the gas canister 60 in proximity of the tool comprises a bracket 100 having a
clamping
portion 102 for affixing the bracket 100 to the drive head 20 and a hook or
stirrup 104
for supporting the canister 60 opposite the regulator head 90. The operation
of this
embodiment is similar to that of the embodiment of Figure 1. This embodiment
is
particularly suitable for retrofitting to existing pneumatic fastener driving
tools 10.
In a still further embodiment of the invention, illustrated in Figure 6, the
gas canister 60 is coupled directly to the drive head 20 and also forms a
handle for the
tool 10. In the preferred embodiment a regulator valve 112 and optionally a
pressure
1o gauge (not shown) are provided in the drive head 20, and the trigger 32 is
configured
as in the embodiment of Figure 1. The opposite end of the canister 60 is
suitably
supported by a bracket 120 having a portion 122 for affixing the bracket 100
to the
rear end of the magazine 14 and a loop or stirrup 124 for supporting the
canister 60.
The operation of this embodiment is similar to the embodiment of Figure 1,
except
15 that the canister 60 itself forms the handle of the tool, reducing the
weight of the tool.
In order to avoid user discomfort from cooling of the canister 60 when driving
multiple fasteners 2 in rapid succession, optionally the canister 60 can be
wrapped
with a fabric, tape or the like (not shown) to insulate the user's hand.
Various embodiments of the present invention having been thus described
2o in detail by way of example, it will be apparent to those skilled in the
art that
variations and modifications may be made without departing from the invention.
The
invention includes all such variations and modifications as fall within the
scope of the
appended claims.
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